Environmental Impact Assessment

 

Proposed Development at

 

Fung Lok Wai, Yuen Long

 

Lot 1457 R. P. in D.D. 123

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


CH2M HILL Hong Kong Limited

in association with

 

RPS

ADI Ltd.

Archaeological Assessments

MVA Hong Kong Limited

 

 

 

Reference                     R228-2.07

 

Client                            Mutual Luck Investment Limited

 

Date                             July 2008

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 


TABLE OF CONTENTS

 

 

1.           Introduction_ 1-1

1.1     Background_ 1-1

1.2     Historical Land Use of the Site_ 1-1

1.3     Ecological Importance of Fish Ponds 1-2

1.4     Project Objective_ 1-2

1.5     Objectives of the EIA Study 1-2

1.6     Scope of the EIA_ 1-3

1.7     Structure of the EIA_ 1-5

2.           Project description_ 2-7

2.1     The Proposed Development and the Environs 2-7

2.2     Construction of the Project 2-9

2.3     Potential Concurrent Projects that Could Lead to Cumulative Impacts 2-14

3.           Consideration of alternatives schemes_ 3-1

3.1     Background_ 3-1

3.2     Identified constraints 3-1

3.3     Modifications of the development proposal to meet the identified constraints 3-1

3.4     Shifting of Residential Development Area_ 3-1

3.5     Alternative Route for Development Access 3-2

3.6     Establishment of a potential alternative egretry within the Wetland Nature Reserve_ 3-4

3.7     Consideration of Alternative Building Heights 3-4

3.8     Comparison of Development Options 3-5

3.9     The Preferred Development Option_ 3-8

4.           air quality impact_ 4-1

4.1     Introduction_ 4-1

4.2     Legislation and Guidelines 4-1

4.3     Ambient Air Quality 4-2

4.4     Construction Phase Impact 4-2

4.5     Operational Phase Impact 4-8

4.6     Conclusion_ 4-9

5.           Noise impact assessment_ 5-1

5.1     Introduction_ 5-1

5.2     Background Information and Relevant Studies 5-1

5.3     Possible Cumulative Impact 5-1

5.4     Assessment Area_ 5-2

5.5     Noise Sensitive Receivers 5-2

5.6     Construction Phase Impact 5-3

5.7     Operational Phase Impact 5-16

5.8     Impacts Summary and Conclusion_ 5-18

6.           Water quality impact assessment_ 6-1

6.1     Introduction_ 6-1

6.2     Description of Existing Water Systems and Respective Catchments 6-1

6.3     Characterisation of Baseline Water & Sediment Quality 6-3

6.4     Existing and Planned Activities In Relation to Water Systems 6-12

6.5     Identification of Alteration of Water Systems Arising from the Project 6-14

6.6     Identification of Existing and Future Water & Sediment Pollution Sources 6-15

6.7     Identification of Water Sensitive Receivers 6-17

6.8     Water and Sediment Quality Assessment Criteria and Existing Policies 6-18

6.9     Water and Sediment Quality Impact Assessment 6-20

6.10   Recommendations of Mitigation Measures 6-22

6.11   Conclusion_ 6-25

7.           Potential Problem of Biogas_ 7-1

7.1     Introduction_ 7-1

7.2     Assessment Methodology 7-1

7.3     Field Sampling and Laboratory Analysis 7-1

7.4     Risk Assessment Criterion_ 7-2

7.5     Estimation of potential Gas Emissions 7-3

7.6     Evaluation of Significance of Potential Gas Emissions 7-6

7.7     Monitoring, Mitigation and Precautionary Measures 7-7

7.8     Impacts Summary and Conclusion_ 7-8

8.           Sewerage and Sewage Treatment Implications_ 8-1

8.1     Introduction_ 8-1

8.2     Existing Sewage Disposal and Treatment Facilities 8-1

8.3     Planned Sewage Disposal and Treatment Facilities in the Area_ 8-2

8.4     Planned Population and Sewerage Flows Projections 8-2

8.5     Proposed Development, Sewerage Options and Projection_ 8-3

8.6     Adequacy of Existing and Planned Sewerage and Treatment Facilities to accept flows 8-3

8.7     New & Upgrading Works of Sewerage Systems Required for Either Options 8-4

8.8     Environmental Impacts of Sewerage Systems 8-5

8.9     Preliminary Design, Operation and Maintenance Requirements of the Proposed Sewerage System for Either Options 8-6

8.10   Conclusion_ 8-8

9.           Waste Management_ 9-1

9.1     Introduction_ 9-1

9.2     Legislation and Guidelines 9-1

9.3     Analysis of Activities and Waste Generation_ 9-2

9.4     Proposal for Waste Management 9-7

9.5     Impacts Summary and Conclusion_ 9-8

10.          cultural heritage impact assessment_ 10-1

10.1   Introduction_ 10-1

10.2   Objectives of the Cultural Heritage Impact Assessment (CHIA) 10-1

10.3   CHIA Methodology 10-1

10.4   The Study Area_ 10-2

10.5   Historical Buildings and Structures Survey 10-2

10.6   Historical Landscape Features Survey 10-9

10.7   Summary of the CHIA Findings and Recommendations 10-11

10.8   References 10-12

11.          LANDSCAPE AND VISUAL IMPACT ASSESSMENT_ 11-1

11.1   Introduction_ 11-1

11.2   Standards and Legislation_ 11-1

11.3   Landscape and Visual Impact Assessment Methodology 11-2

11.4   Selection of the Preferred Option_ 11-7

11.5   Review of Planning and Development Control Framework 11-15

11.6   Review of Study on the Ecological Value of Fish Ponds in Deep Bay Area_ 11-20

11.7   Existing Landscape Context 11-21

11.8   Landscape Impact Assessment 11-22

11.9   Existing Visual Context and Visual Impacts 11-44

11.10  Cumulative Impacts 11-66

11.11  Mitigation Measures 11-66

11.12  Programme for Landscape Works 11-72

11.13  Operational (Residual) Landscape and Visual Impacts 11-86

11.14  Conclusion_ 11-89

12.          Fisheries impact assessment_ 12-1

12.1   Introduction_ 12-1

12.2   Methods 12-2

12.3   Description of the Physical Environment 12-2

12.4   Baseline condition_ 12-8

12.5   Impact Identification and Assessment 12-10

12.6   Fisheries Mitigation / Compensation Measures 12-15

12.7   Monitoring and Audit Programme_ 12-15

12.8   Conclusion_ 12-16

12.9   References/ Bibliography 12-16

13.          Ecological impact Assessment_ 13-1

13.1   Introduction_ 13-1

13.2   Description of the Physical Environment 13-3

13.3   Literature Review_ 13-6

13.4   Review of Recognised Sites of Conservation Importance in the Vicinity of Fung Lok Wai 13-7

13.5   Field Survey Methodology 13-12

13.6   General Ecological Profile and Evaluation of Valued ecological Components 13-19

13.7   Identification of Potential Impacts 13-44

13.8   Evaluation of impacts 13-49

13.9   Mitigation Measures 13-69

13.10  Identification and evaluation of residual ecological impacts 13-86

13.11  Ecological Monitoring and Audit 13-87

13.12  References 13-88

14.          Draft Habitat creation and Management PLan FOR the Wetland NaTure Reserve  14-1

14.1   Study background and objectives 14-1

14.2   Mitigation objectives 14-10

14.3   Detailed design and construction methods 14-15

14.4   Management Strategy 14-26

14.5   Monitoring and action plans 14-35

14.6   HCMP Reporting and Review process 14-39

14.7   References 14-43

15.          The Long-term Management OF the Wetland NAture Reserve_ 15-1

15.1   Introduction_ 15-1

15.2   Overview of Wetland Nature Reserve Management Arrangements 15-1

15.3   Management of the Wetland Nature Reserve_ 15-2

15.4   Conclusions 15-3

16.          Environmental monitoring and audit (EM&A) requirements_ 16-1

16.1   Introduction_ 16-1

16.2   Objectives of Environmental Monitoring and Audit 16-1

16.3   Summary of Areas Requiring EM&A_ 16-1

16.4   Air Quality 16-1

16.5   Noise Monitoring_ 16-2

16.6   Water Quality 16-2

16.7   Waste Management 16-2

16.8   Ecology 16-3

16.9   Landscape and Visual 16-3

16.10  Cultural Heritage_ 16-3

16.11  Implementation Schedule of Environmental Mitigation Measures 16-3

17.          Summary of environmental outcomes and overall conclusion_ 17-1

17.1   Introduction_ 17-1

17.2   Key Environmental Issues 17-1

17.3   Air Quality Impact 17-1

17.4   Noise Impacts 17-2

17.5   Water Quality 17-3

17.6   Potential Problem of Biogas 17-4

17.7   Sewerage and Sewerage Treatment Implications 17-4

17.8   Waste Management 17-5

17.9   Ecological Impact Assessment 17-6

17.10  Fisheries Impact Assessment 17-8

17.11  Cultural Heritage Impact Assessment 17-8

17.12  Landscape and Visual Impact Assessment 17-9

17.13  Overall Conclusion_ 17-11

 

 

Volume 3

LIST OF APPENDICES

Appendix 1-1    Study Brief

Appendix 4-1    Calculation of Particulate Emission Rates for Fugitive Dust Impact Assessment

Appendix 4-2    Typical FDM Result File for Fugitive Dust Impact Assessment

Appendix 5-1    PME Equipment Inventory for Construction Noise Impact Assessment

Appendix 5-2    Typical Calculation Worksheet for Construction Noise Impact Assessment

(Unmitigated Scenario)

Appendix 5-3    Silenced PME Equipment Inventory for Construction Noise Impact Assessment

Appendix 5-4    Typical Calculation Worksheet for Construction Noise Impact Assessment

(With Silenced PME)

Appendix 5-5    Reduced SWL of the PME when noise barriers and machinery enclosures applied

Appendix 5-6    Typical Calculation Worksheet for Construction Noise Impact Assessment

(Silenced PME with noise barriers and machinery enclosures)

Appendix 8-1    Sewerage Impact Assessment

Appendix 10-1   Historical buildings and Structures Catalogue  

Appendix 11-1   Preliminary Tree Survey Report

Appendix 13-1  Ramsar Classification System for Wetlands

Appendix 13-2  Photographs of each habitat type defined within the Assessment Area for the proposed development at Fung Lok Wai.

Appendix 13-3  Vegetation survey results, site wide excluding route of original proposed access road.

Appendix 13-4  Aquatic invertebrates recorded at Fung Lok Wai during the required survey period.

Appendix 13-5   Odonata species recorded at Fung Lok Wai during the required survey period.

Appendix 13-6   Butterfly species recorded at Fung Lok Wai during the required survey period.

Appendix 13-7   Fish species recorded during surveys at Fung Lok Wai

Appendix 13-8   Amphibian species recorded during surveys at Fung Lok Wai

Appendix 13-9   Reptile species recorded during surveys at Fung Lok Wai

Appendix 13-10 Summary bird survey results from transects T1-5 and T7

Appendix 13-11 Summary bird survey results from transect T6

Appendix 13-12 Analysis of recent bird records within the Deep Bay area

Appendix 14-1   Generic Bund Designs

Appendix 14-2   Water Budget

Appendix 14-3   Planting Zones

Appendix 14-4   Specification for footpaths/ broad walks

Appendix 14-5   Indicative design of hides

Appendix 14-6   Details of Floating Platforms

Appendix 16-1   Implementation Schedule of Recommended Environmental Mitigation Measures


LIST OF ANNEX

 

Annex                                      A Proposal for the Management of HKSAR WETLAND NATURE FOUNDATION

 

LIST OF FIGURES

Figure 1‑1       The Proposed Development 1-6

Figure 2‑1       The Proposed Development and the Environs 2-15

Figure 2‑2       Extract of Tin Shui Wai, Lau Fau Shan & Tsim Bei Tsui Zoning Plan_ 2-16

Figure 2‑3       Tentative MLP of the Proposed Residential Development 2-17

Figure 2‑4       The Assessment Area_ 2-18

Figure 2‑5       Tentative Layout Plan of Wetland Nature Reserve 2-19

Figure 2‑6       Existing Drainage and Catchment Area in the Vicinity 2-20

Figure 2‑7       Tentative Construction Programme for the Project 2-21

Figure 2‑8       The Proposed Access Road of the Development 2-22

Figure 2‑9       Pond Numbering System Used Prior to WNR Establishment 2-23

Figure 2‑10     Pond Enhancement Sectors of the Proposed WNR_ 2-24

Figure 2‑11      Locations of New Bunds and the Removal / Modification Sequence of the Bunds 2-25

Figure 2‑12     Possible Concurrent Projects in the Vicinity 2-26

Figure 3‑1       The Original Preliminary Layout of the Project 3-9

Figure 3‑2       The Modified Development 3-10

Figure 3‑3a     The Three Building Height Scenarios – Option 1A_ 3-11

Figure 3‑3b     The Three Building Height Scenarios – Option 1B_ 3-12

Figure 3‑3c      The Three Building Height Scenarios – Option 1C_ 3-13

Figure 3‑4       Photomontages of the Three Building Height Scenarios 3-14

Figure 3‑5       Original Location and Shifted Location of the Proposed Residential Development 3-15

Figure 4‑1       Location of Representative ASRs for Construction Dust Impact Assessment 4-10

Figure 4‑2       The Alignment of Haul Roads, Locations of Representative Emission Points of Stage A_ 4-11

Figure 4‑3       The Alignment Of Haul Roads, Locations Of Representative Emission Points Of Stage B_ 4-12

Figure 4‑4       Mitigated Maximum Hourly Average TSP Concentrations Predicted at 10.0 mPD under Stage A  4-13

Figure 4‑5       Mitigated Daily Average TSP Concentrations Predicted at 5.3mPD under Stage A_ 4-14

Figure 4‑6       Mitigated Maximum Hourly Average TSP Concentrations Predicted at 6.3mPD under Stage B  4-15

Figure 4‑7       Mitigated Maximum Daily average TSP Concentrations Predicted at 6.3mPD under Stage B  4-16

Figure 5‑1       Locations of the Representative Assessment Point (RAPs) selected for Construction Noise Impact Assessment 5-19

Figure 5‑2       The Noise Sensitive Receivers around the Site 5-20

Figure 5‑3       Construction Area for Access Road, Residential Site and Wetland Nature Reserve 5-21

Figure 6‑1       The Assessment Area of the Water Quality Impact Assessment 6-26

Figure 6‑2       Existing Water Systems and Respective Catchments 6-27

Figure 6‑3       Locations of EPD’s Water Quality Monitoring Stations in Deep Bay 6-28

Figure 6‑4       Locations of EPD’s Marine Sediment Quality Monitoring Stations in Deep Bay 6-29

Figure 6‑5       Locations and WQI of EPD’s River Water Quality Monitoring Stations at Yuen Long Creek and Kam Tin River 6-30

Figure 6‑6       Locations of Sampling Ponds for Fishpond Water Quality 6-31

Figure 6‑7       Locations of Sampling Ponds for Fishpond Sediment Quality 6-32

Figure 6‑8       Sampling Locations for River Water Quality 6-33

Figure 6‑9       21 Larger Ponds will be Consolidated in the WNR_ 6-34

Figure 6‑10     Details of Marsh Structure 6-35

Figure 6‑11      Drainage Channel X and Y for Water Discharge in the WNR_ 6-36

Figure 6‑12     Daily Variation of Rainfall from 1989 to 1998_ 6-37

Figure 6‑13     Discharge Volume from Water Ponds within the Site from 1989 to 1998_ 6-38

Figure 7‑1       Locations of Sediment Sampling Ponds for Biogas Investigation_ 7-9

Figure 8‑1       Existing Sewerage Systems near the Subject Site 8-9

Figure 8‑2       The YLSTW Effluent Pipelines and its Alternative of the YLKTSSD Stage 2_ 8-10

Figure 8‑3       The Sub-catchment of Sewerage Network under Tin Wah Road_ 8-11

Figure 8‑4       Proposed Sewerage Options 8-12

Figure 8‑5       Total Flow to Yuen Long STW from 2000 to 2016_ 8-13

Figure 10‑1     Location of the Study Area in Hong Kong_ 10-13

Figure 10‑2     Aerial View of Study Area 1949 (GEO Ref.# YO2388) 10-14

Figure 10‑3     Aerial View of Study Area 1963 (GEO Ref.# YO9690 ) 10-15

Figure 10‑4     Aerial View of Study Area 2000 (GEO Ref.# CN26484 ) 10-16

Figure 10‑5     Photographs Illustrating Examples of Structures in the Study Area_ 10-17

Figure 10‑6     Map Showing the Locations of Historical Structures in Shing Uk Tsuen_ 10-18

Figure 10‑7     Map Showing the Locations of the Historical Structures in Tai Tseng Wai 10-19

Figure 10‑8a   Map Showing the Locations of the Historical Structures in Ng Uk Tsuen_ 10-20

Figure 10‑8b   Map Showing the Locatios of the Tin Hau Temple near Ng Uk Tsuen_ 10-21

Figure 10‑9     Map Showing the Locations of Graves and Fung Shui Wood_ 10-22

Figure 10‑10   Aerial View of the Study Area 1924 (GEO Ref.# Y00159) 10-23

Figure 10‑11    Map showing the Evolution of the Bunds (1927-2000) and Locations of Existing Bunds Still Following the Original Alignment 10-24

Figure 10‑12   Photographs illustrating the Study Area: (A) Example of road hardening; (B) View of the bunds; (C) View of a sluice gate 10-25

Figure 11‑1A   Alternative Building Height Profiles 11-95

Figure 11‑1B   Alternative Block Plans – Option 1A_ 11-96

Figure 11‑1C   Alternative Block Plans – Option 1B_ 11-97

Figure 11‑1D   Alternative Block Plans – Option 1C_ 11-98

Figure 11‑2      Landscape Resources 11-99

Figure 11‑3      Preliminary Tree Survey Plan_ 11-100

Figure 11‑4      Landscape CharacterAreas 11-101

Figure 11‑5A   Landscape Character Area Photograph_ 11-102

Figure 11‑5B   Landscape Character Area Photograph_ 11-103

Figure 11‑6      Visual Envelope and Zone of Visual Influence 11-104

Figure 11‑7      Visual Characteristics of the Study Area_ 11-105

Figure 11‑8      Review of Planning and Development Control Framework_ 11-106

Figure 11‑9      Impacts on Landscape Resources Option 1A and 1B_ 11-107

Figure 11‑10A Visual Impacts for Option 1A_ 11-108

Figure 11‑10B Visual Impacts for Option 1B_ 11-109

Figure 11‑11A  Design Concept Drawing and Recommended Landscape Mitigation Measures for Option 1A  11-110

Figure 11‑11B  Landscape Master Plan for Option 1A_ 11-111

Figure 11‑12A Design Concept Drawing and Recommended Landscape Mitigation Measures for Option 1B  11-112

Figure 11‑12B Landscape Master Plan for Option 1A_ 11-113

Figure 11‑13A Section A-A’ for Option 1A_ 11-114

Figure 11‑13B Section B-B’ for Option 1A_ 11-115

Figure 11‑13C Section A-A’ for Option 1B_ 11-116

Figure 11‑13D Section B-B’ for Option 1B_ 11-117

Figure 11‑14A Photomontages Vantage Point A – Option 1A_ 11-118

Figure 11‑14B Photomontages Vantage Point A – Option 1A_ 11-119

Figure 11‑14C Photomontages Vantage Point B – Option 1A_ 11-120

Figure 11‑14D Photomontages Vantage Point B – Option 1A_ 11-121

Figure 11‑14E Photomontages Vantage Point C – Option 1A_ 11-122

Figure 11‑14F Photomontages Vantage Point C – Option 1A_ 11-123

Figure 11‑14G Photomontages Vantage Point D – Option 1A_ 11-124

Figure 11‑14H Photomontages Vantage Point D – Option 1A_ 11-125

Figure 11‑14I  Photomontages Vantage Point E – Option 1A_ 11-126

Figure 11‑14J  Photomontages Vantage Point E – Option 1A_ 11-127

Figure 11‑14K Photomontages Vantage Point F – Option 1A_ 11-128

Figure 11‑14L  Photomontages Vantage Point F – Option 1A_ 11-129

Figure 11‑14MPhotomontages Vantage Point G – Option 1A_ 11-130

Figure 11‑14N Photomontages Vantage Point G – Option 1A_ 11-131

Figure 11‑14O Photomontages Vantage Point H – Option 1A_ 11-132

Figure 11‑14P Photomontages Vantage Point H – Option 1A_ 11-133

Figure 11‑15A Photomontages Vantage Point A – Option 1B_ 11-134

Figure 11‑15B Photomontages Vantage Point A – Option 1B_ 11-135

Figure 11‑15C Photomontages Vantage Point B – Option 1B_ 11-136

Figure 11‑15D Photomontages Vantage Point B – Option 1B_ 11-137

Figure 11‑15E Photomontages Vantage Point C – Option 1B_ 11-138

Figure 11‑15F Photomontages Vantage Point C – Option 1B_ 11-139

Figure 11‑15G Photomontages Vantage Point D – Option 1B_ 11-140

Figure 11‑15H Photomontages Vantage Point D – Option 1B_ 11-141

Figure 11‑15I  Photomontages Vantage Point E – Option 1B_ 11-142

Figure 11‑15J  Photomontages Vantage Point E – Option 1B_ 11-143

Figure 11‑15K Photomontages Vantage Point F – Option 1B_ 11-144

Figure 11‑15L  Photomontages Vantage Point F – Option 1B_ 11-145

Figure 11‑15MPhotomontages Vantage Point G – Option 1B_ 11-146

Figure 11‑15N Photomontages Vantage Point G – Option 1B_ 11-147

Figure 11‑15O Photomontages Vantage Point H – Option 1B_ 11-148

Figure 11‑15P Photomontages Vantage Point H – Option 1B_ 11-149

Figure 12‑1     Location and Layout of the Assessment Area_ 12-18

Figure 12‑2     Sequence of Pond Enhancement Works 12-19

Figure 13‑1     Site Outline and Extent of Ecological Assessment Areas 13-92

Figure 13‑2     Location of Ecologically Sensitive Receivers near the Fung Lok Wai Site 13-93

Figure 13‑3     Vegetation Survey Quadrat Locations 13-94

Figure 13‑4     Aquatic Invertebrate Sampling Locations 13-95

Figure 13‑5     Insect and Herpetofauna Transect Routes 13-96

Figure 13‑6     Freshwater Fish Survey Locations 13-97

Figure 13‑7     Bird Survey Transect Locations 13-98

Figure 13‑8     Location of Current Egretry and Flightline Survey Observers 13-99

Figure 13‑9     Distribution of Habitat Types within the Study Area_ 13-100

Figure 13‑10   Flight line Survey Results for the Entire Study Site at Fung Lok Wai 13-101

Figure 13‑11    Flight Lines Associated with the Fung Lok Wai Egretry 13-102

Figure 13‑12   Location of Disturbance Exclusion and Reduced Density Buffers for Waterbird Species of Conservation Importance during Construction and Operation Phases 13-103

Figure 13‑13   Habitat Enhancement Work Programme for The Fung Lok Wai WNR_ 13-104

Figure 14‑1     Location of the Fung Lok Wai Wetland Nature Reserve 14-45

Figure 14‑2     Average Monthly Rainfall, Evaporation and Deficits at Fung Lok Wai. 14-46

Figure 14‑3     Existing Water Systems and Respective Catchments 14-47

Figure 14‑4     Broad Layout of the Wetland Nature Reserve 14-48

Figure 14‑5     Details of Habitat Layout within the Wetland Nature Reserve 14-49

Figure 14‑6     Developments Associated with the Construction of the Wetland Nature Reserve 14-50

Figure 14‑7     Location of Aquaculture Pond Habitat Features and Water Control Structures 14-51

Figure 14‑8     Details of Marsh Habitats and Infrastructure 14-52

Figure 14‑9     Habitats within the Constructed Marsh Area_ 14-53

Figure 14‑10   Status of Storage Pond under Normal and Extreme Rainfall Scenarios 14-54

Figure 14‑11    Management Compartments for the Mai Po and Inner Deep Bay Ramsar Site 14-55

Figure 14‑12   Proposed Layout of Footpaths 14-56

Figure 14‑13   Pond Enhancement Sectors 14-57

Figure 14‑14   Definition of Operating Water Levels for Ponds 14-58

 


LIST OF TABLES

 

Table 2‑1         Basic Parameters of the Proposed Residential Development 2-7

Table 2‑2         Habitat Enhancement Work Programme For The Fung Lok Wai WNR_ 2-12

Table 3‑1         Comparison of the Two Access Options 3-3

Table 4‑1         Hong Kong Air Quality Objectives 4-1

Table 4‑2         Annual Average Concentrations of NO2 and RSP measured at EPD’s Air Quality Monitoring Station in Yuen Long from 2002 to 2006_ 4-2

Table 4‑3         Representative ASRs for the Dust Emission Impact Assessment 4-4

Table 4‑4         Predicted Unmitigated TSP Level at selected ASRs 4-5

Table 4‑5         Predicted mitigated TSP Level at selected ASRs 4-7

Table 5‑1         Noise Limits for Daytime Construction Activities 5-3

Table 5‑2         Key Construction Activities for Construction Noise Impact Assessment 5-4

Table 5‑3         Representative Assessment Phases studied in the Construction Noise Impact Assessment 5-5

Table 5‑4         RAPs Selected for Construction Noise Impact Assessment 5-7

Table 5‑5         Unmitigated Noise Levels Predicted At CN 1_ 5-7

Table 5‑6         Unmitigated Noise Levels Predicted At CN 2_ 5-8

Table 5‑7         Unmitigated Noise Levels Predicted At CN 3_ 5-8

Table 5‑8         Unmitigated Noise Levels Predicted At CN 4_ 5-9

Table 5‑9         Unmitigated Noise Levels Predicted At CN 5_ 5-9

Table 5‑10       Mitigated Noise Levels at CN1 with Silenced PME_ 5-10

Table 5‑11       Mitigated Noise Levels at CN2 with Silenced PME_ 5-11

Table 5‑12       Mitigated Noise Levels at CN3 with Silenced PME_ 5-11

Table 5‑13       Mitigated Noise Levels at CN4 with Silenced PME_ 5-12

Table 5‑14       Mitigated Noise Levels at CN5 with Silenced PME_ 5-12

Table 5‑15       Mitigated Noise Levels at CN1 with Silenced PME + Temporary Noise Barriers + Machinery Enclosure  5-14

Table 5‑16       Mitigated Noise Levels at CN2 with Silenced PME + Temporary Noise Barriers + Machinery Enclosure  5-14

Table 5‑17       Area Sensitivity Ratings of NSRs 5-17

Table 6‑1         Summary Statistics of Marine Water Quality of Deep Bay WCZ in 2005 (Inner Deep Bay) 6-4

Table 6‑2         Summary Statistics of Marine Bottom Sediment Quality of Deep Bay WCZ, 2001 -2005_ 6-5

Table 6‑3         Summary of River Water Quality Monitoring results for Yuen Long Creek, Kam Tin River and Tin Shui Wai Nullah in 2005_ 6-7

Table 6‑4         Results Of Water Quality Monitoring In Fishponds At Fung Lok Wai (1995) 6-9

Table 6‑5         Results of Fishpond/ River Water Quality Survey at Fung Lok Wai 6-10

Table 6‑6         Results of Fishpond Sediment Quality Survey at Fung Lok Wai 6-10

Table 6‑7         Estimated Runoff After Development 6-15

Table 6‑8         Estimated Peak Rate of Runoff After Development 6-15

Table 6‑9         Water Quality Objectives for Deep Bay WCZ_ 6-18

Table 6‑10       Classification of Sediment 6-18

Table 6‑11       Sediment Quality Criteria for the Classification of Sediment 6-19

Table 6‑12       Summary of Annual Evaporation and Rainfall (1989 to 1998) 6-20

Table 7‑1         Sampling Locations and Levels of Total Organic Carbon (TOC) and Sediment Oxygen Demand (SOD) 7-1

Table 7‑2         Calculation of Methane Flux from the Fung Lok Wai Development 7-5

Table 8‑1         Development Schedule the Project 8-2

Table 8‑2         Required Upgrading of the Sewerage Network Leading to the TWR pumping Station_ 8-5

Table 9‑1         Sumamry Table of Estimate Quantity of Materials to be Generated or Imported during the Construction of the Fung Lok Wai Project 9-4

Table 10‑1       The impacts associated with cultural heritage resources outside the Study Area_ 10-8

Table 10‑2       Mitigation Recommendations for Cultural Heritage Resources Outside the Study Area_ 10-9

Table 11‑1       Degree of Impact 11-5

Table 11‑2       Residual Impact Significance Threshold Matrix 11-6

Table 11‑3       Alternative Schemes Comparison_ 11-10

Table 11‑4       Review of Existing Planning and Development Control Framework_ 11-17

Table 11‑5       Existing Landscape Resources and Predicted Impacts – Options 1A and 1B_ 11-25

Table 11‑6       Existing Landscape Character and Predicted Impacts – Options 1A and 1B_ 11-37

Table 11‑7A     Visually Sensitive Receivers and Predicted Impacts – Option 1A_ 11-48

Table 11‑7B     Visually Sensitive Receivers and Predicted Impacts – Option 1B_ 11-63

Table 11‑8       Proposed Construction Phase Mitigation Measures 11-67

Table 11‑9       Proposed Operational Phase Mitigation Measures 11-68

Table 11‑10     Provisional Programme for Landscape Works 11-72

Table 11‑11      Landscape and Visual Mitigation Measures Implementation Schedules 11-73

Table 12‑1       Results of Fishpond/ River Water Quality Survey at Fung Lok Wai 12-4

Table 12‑2       Area of Ponds and Inland Fresh Fish Production In Hong Kong. Source AFCD Annual Reports, 2002  12-5

Table 12‑3       Optimum Water Quality Objectives for Initiating Fish Rearing_ 12-6

Table 12‑4       Summary Of Fish Species Typical Of Polyculture Practice In The Deep Bay Area And Examples Of The Sources Of Stock_ 12-7

Table 12‑5       Production Time And Acceptable Market Size Of Species Of Fish Raised In Aquaculture Ponds  12-7

Table 12‑6       Extent of Habitats Identified Within the Fung Lok Wai Assessment Area_ 12-8

Table 12‑7       Wholesale price range per kg of freshwater fish during the period January – December 2001. Source: AFCD, fax 11/9/02_ 12-11

Table 12‑8       Schedule for pond enhancement works. Bund numbers are illustrated in Figure 12‑2_ 12-12

Table 12‑9       Summary of importance of the fisheries resources within the Fung Lok Wai Assessment Area and evaluation of predicted impacts 12-14

Table 13‑1       Results of Water Quality Monitoring in Fishponds at Fung Lok Wai (May 2002) 13-5

Table 13‑2       Survey Time Segments for Bird Flight Line Surveys 13-17

Table 13‑3       Target Species for Flightline Surveys and Their Species Codes used on Recording Sheets  13-18

Table 13‑4       Altitude Categories Adopted to Record the Bird Flight Line Data_ 13-18

Table 13‑5       Extent of Habitat Types within the Assessment Area (ha.) 13-20

Table 13‑6       Ecological Evaluation Of Intertidal Forested Wetlands 13-21

Table 13‑7       Ecological Evaluation of Permanent Rivers, Streams and Creeks 13-22

Table 13‑8       Ecological Evaluation of Ditches and Drainage Channels 13-22

Table 13‑9       Ecological Evaluation of Aquaculture Ponds 13-23

Table 13‑10     Ecological Evaluation of Reedbed_ 13-24

Table 13‑11     Ecological Evaluation of Permanent Freshwater Marsh and Pools 13-24

Table 13‑12     Ecological Evaluation of Seasonally Flooded (wet) Agricultural Land_ 13-25

Table 13‑13     Ecological Evaluation of Dry Agricultural Land_ 13-25

Table 13‑14     Ecological Evaluation of Inactive Agricultural Land_ 13-25

Table 13‑15     Ecological Evaluation of Orchards 13-26

Table 13‑16     Ecological Evaluation of Fung Shui Woodland_ 13-26

Table 13‑17     Ecological Evaluation of Semi-natural Secondary Woodland_ 13-27

Table 13‑18     Ecological Evaluation of Plantation Woodland_ 13-27

Table 13‑19     Ecological Evaluation of Grassland_ 13-28

Table 13‑20     Ecological Evaluation of Grassland-Shrubland Mosaic 13-28

Table 13‑21     Ecological Evaluation of Landscaped Area_ 13-28

Table 13‑22     Ecological Evaluation of Wasteland Habitats 13-29

Table 13‑23     Ecological Evaluation of Recreated Wetland_ 13-29

Table 13‑24     Ecological Evaluation of Developed Areas 13-30

Table 13‑25     Summary of habitat evaluations in order of ecological value. 13-31

Table 13‑26     Plant Species of Potential Conservation Interest Recorded within the Assessment Area_ 13-32

Table 13‑27     Reptile Species of Some Conservation Value, Their Habitat Preferences and Observed Relative abundance within the Assessment Area at Fung Lok Wai 13-35

Table 13‑28     Bird Species of Conservation Importance Recorded in Significant Numbers within the Assessment Area of Fung Lok Wai 13-37

Table 13‑29     List of Bird Species of Conservation Importance Recorded in Each Section of the Assessment Area at Fung Lok Wai. 13-40

Table 13‑30     Abundance and Proportion of Birds Observed Within the Study Site by Altitude Category (February-December 2001) 13-41

Table 13‑31     Dominant Species by Altitude Category 13-41

Table 13‑32     Comparison of Total Individuals for Each Altitude Category within the Study Site and the Proposed Development Area_ 13-41

Table 13‑33     Abundance and Proportion of Birds Observed within the Proposed Development Area by Altitude Category (February-December 2001) 13-42

Table 13‑34     Dominant Species Recorded at Each Altitude Category within the Proposed Development Area  13-42

Table 13‑35     Comparison of Potential Affect on Egretry Flightlines of Alternative Development Scenarios  13-46

Table 13‑36     Summary Matrix of Potential Impacts on Various Types of Habitats 13-49

Table 13‑37     Summary of Impacts to Aquaculture Ponds from Habitat Loss 13-50

Table 13‑38     Summary of Impacts to Ditches and Drainage Channel from Habitat Loss 13-51

Table 13‑39     Summary of Impacts to Wetland Mosaic Habitats (Including Wet Agriculture, Reedbed, and Freshwater Marsh) from Habitat Fragmentation_ 13-51

Table 13‑40     Summary of Impacts to Fung-shui Woodland from Habitat Fragmentation_ 13-52

Table 13‑41     Summary of Impacts to Aquaculture Ponds from Disturbance 13-53

Table 13‑42     Summary of Impacts to Fung Shui Woodland (Including Egretry) from Disturbance 13-53

Table 13‑43     Summary of Impacts to Intertidal Forested Wetland from Disturbance 13-54

Table 13‑44     Summary of Impacts to Wetland Mosaic Habitats (including Wet Agriculture, Reedbed, and Freshwater Marsh) from Disturbance 13-54

Table 13‑45     Summary of Impacts to Dry/Inactive Agricultural Land from Disturbance 13-54

Table 13‑46     Summary of impacts to Semi-natural Secondary Woodland from Disturbance 13-54

Table 13‑47     Summary of Impacts to Aquaculture Ponds from Pollution_ 13-55

Table 13‑48     Summary of Impacts to Fung-shui Woodland (including Egretry) from Pollution_ 13-56

Table 13‑49     Summary of Impacts to Intertidal Forested Wetland from Pollution_ 13-56

Table 13‑50     Summary of Impacts Wetland Mosaic Habitats (including Wet Agriculture, Reedbed, and Freshwater Marsh) from Pollution_ 13-56

Table 13‑51     Summary of Impacts to Dry/Inactive Agricultural Land from Pollution_ 13-57

Table 13‑52     Summary of Impacts to Semi-natural Secondary Woodland from Pollution_ 13-57

Table 13‑53     Summary of Impacts to Aquaculture Ponds from Soil Compaction_ 13-57

Table 13‑54     Summary of Impacts to Ditches and Drainage Channels from Hydrological Disruption_ 13-58

Table 13‑55     Predicted Disturbance Impacts from the Construction and Operation of the Residential Development on Regularly Occurring Species of Conservation Importance at Fung Lok Wai 13-62

Table 13‑56     Habitat Loss During the Construction Phase on Regularly Occurring Species of Conservation Importance at Fung Lok Wai 13-63

Table 13‑57     Habitat Loss during the Operation Phase on Regularly Occurring Species of Conservation Importance at Fung Lok Wai 13-65

Table 13‑58     Significance of impacts on Species of Conservation Importance at Fung Lok Wai 13-68

Table 13‑59     Observed maximum, mean (counts and densities) of wetland bird species using the wetland in the Study Site and Assessment Area during 2001_ 13-72

Table 13‑60     Extent and proportion of direct and indirect (due to disturbance) habitat loss during construction for sensitive wetland bird species. 13-73

Table 13‑61     Mitigation targets for key wetland bird species of conservation importance within remaining wetland areas of the Study Site required to fully compensate for habitat loss and disturbance impacts during construction_ 13-74

Table 13‑62     Extent and proportion of direct and indirect (due to disturbance) habitat loss during operation for wetland bird species 13-77

Table 13‑63     Mitigation targets for wetland bird species of conservation importance within remaining wetland areas of the Study Site required to fully compensate for habitat loss and disturbance impacts during operation  13-78

Table 13‑64     Mitigation Targets for Enhanced Aquaculture Ponds 13-79

Table 13‑65     Mitigation Targets for Marsh Habitat 13-80

Table 13‑66     Bird SpeciesExpected to Use the Marsh Habitat 13-80

Table 13‑67     The Overall Levels Of Compensation Predicted From Compensation Measures For Species Of Conservation Importance That Were Recorded During The Baseline Surveys At Fung Lok Wai 13-84

Table 13‑68     Proposed Mitigation Measures and Predicted Residual Impacts 13-86

Table 13‑69     Mitigation targets for Key Bird Species and other Species of Conservation Importance 13-87

Table 14‑1       Ecological evaluation of habitats within the Fung Lok Wai Assessment Area_ 14-4

Table 14‑2       Species of Conservation Importance that occur within the Fung Lok Wai Assessment Area  14-5

Table 14‑3       Summary matrix of potential impacts on habitats 14-7

Table 14‑4       Potential physical constraints on the creation of a Wetland Nature Reserve at Fung Lok Wai. 14-7

Table 14‑5       Mitigation targets for enhanced fishponds 14-12

Table 14‑6       Mitigation targets for Marsh Habitat 14-13

Table 14‑7       Mitigation targets for Species of Conservation Importance associated with fishpond habitats  14-13

Table 14‑8       Species Expected to Use the Marsh Habitat 14-14

Table 14‑9       The area of habitats in the proposed WNR_ 14-15

Table 14‑10     Pond enhancement schedule. 14-18

Table 14‑11     Wetland species to be established in the aquaculture pond mitigation area_ 14-19

Table 14‑12     Species to be established in the Marsh Habitat area_ 14-24

Table 14‑13     Long-term pond management (5 year cycle) 14-32

Table 14‑14     General management actions for the Fung Lok Wai WNR_ 14-33

Table 14‑15     Ecological monitoring programme for Fung Lok Wai WNR_ 14-36

Table 14‑16     Key Action Levels and Limits and their associated management actions 14-40

 


1.                  Introduction

1.1              Background

1.1.1          The Project Proponent - Mutual Luck Investment Limited (MLI), proposes to develop a residential development and a Wetland Nature Reserve (“WNR”) (hereinafter collectively called the “Project”) at existing fishponds at Lot 1457 R.P., D.D. 123 Fung Lok Wai, (the Subject Site). The Project comprises the following main components: -

·        About 4 ha of residential land for 148,000m2 GFA residential development and a club house for residents;

·        About 76 ha of enhanced and managed WNR, including a potential alternative egretry.

1.1.2          The entire development will be about 80 ha in size. The about 4 ha of residential land will be formed by filling fishponds at the southern part of the site, whilst the WNR will be established to its immediate north. The Project complies with the “no-net-loss in wetland” principle stipulated in the notes of the Approved Lau Fau Shan and Tsim Bei Tsui OZP No. S/YL/-LFS/7.

1.1.3          This is achieved through enlargement of existing fishponds by removal of part of the dividing bunds. The Project is scheduled to be completed and with population intake in third quarter of 2016.

1.1.4          The Subject Site abuts the Inner Deep Bay and lies within the Wetland Conservation Area.  About 43 ha of the Site has been designated as a Mai Po Inner Deep Bay Ramsar Site since September 1995. The Site is close to the Hong Kong Wetland Park (HKWP), with Mai Po area to its northeast and Yuen Long Industrial Estate (YLIE) to southeast.

1.1.5          The existing Fuk Shun Street at the southern side of the Subject Site will be used as the access road of the Project. The location of the Project, the site boundary and the proposed access road are shown as Figure 1‑1

1.1.6          This Project is a Designated Project according to Item P of Part I, Schedule 2 of the EIA Ordinance, since it is a residential development other than New Territories exempted house within the Deep Bay Buffer Zone 1 and 2.

1.1.7          MLI submitted an application (No. ESB-055/2000) for an Environmental Impact Assessment (EIA) Study Brief under section 5(1)(a) of the Environmental Impact Assessment Ordinance (EIAO) on 26 May 2000 with a project profile (No. PP-091/2000).

1.1.8          A Study Brief [No. ESB-055/2000] was issued by the Authority to the MLI under Section 5(7)(a) of the EIAO in July 2000 for preparation of the EIA report.  A copy of the Study Brief is given in Appendix 1-1 for reference.

1.1.9          CH2M HILL Hong Kong Limited, formerly traded as CH2M-IDC Hong Kong Limited, has been commissioned by the MLI on 16 November 2000 as the lead consultant to carry out this EIA in associated with RPS, Asia Ecological Consultant, ADI Ltd., Archaeological Assessments and MVA Hong Kong Limited.

1.1.10      This EIA report is prepared in accordance with the requirements stated in the Study Brief and the relevant criteria and guidelines as stated in various Annexes of the EIA TM.

 

1.2              Historical Land Use of the Site

1.2.1          The earliest useful map indicated that the area of Fung Lok Wai was swamp and marsh in the early 1900’s. The area was then reclaimed for brackish water rice cultivation.  During the period between 1938 and 1945, the Deep Bay area was transformed into gei wais.  By 1974, the area was converted to deep water fish ponds as fish farming was then a profitable business.  These fish ponds remain up to the present, however many of them have been abandoned as a result of severe competition from the cheap fish imports from mainland China.

 

1.3              Ecological Importance of Fish Ponds

1.3.1          Fresh water fish farming was once an important agricultural activity in Deep Bay area supporting the livelihoods of many local people.  These fish ponds, it so happened, also served as an extensive area of wetland habitat that are of ecological importance to birds, in particular to migratory birds on their migratory path as a refuelling station.

1.3.2          The Fish Pond Study identified that the traditional aquaculture management practices adopted in the fish ponds within Deep Bay were of particular ecological value to wetland birds when the ponds were drained at harvest time.  These water birds feed on trash fish that are of no commercial value and which are bi-product of traditional aquaculture management practices.

1.3.3          However, with the continual decline of the fish farming industry in Hong Kong throughout the past decades, many of the fish ponds in Deep Bay area are abandoned.  With the absence of active management, the ecological value of fish ponds to birds will be lost.  Therefore, there is an imminent need to conserve these fish ponds together with the traditional aquaculture management practices in order to conserve the ecological value of this important wetland habitat in Deep Bay.

 

1.4              Project Objective

1.4.1          The objective of the Project is to develop a sustainable model for the conservation of the existing fish ponds together with the traditional aquaculture management practices with value creation stemming from the development of a residential complex.

1.4.2          Three major principles are proposed to be upheld in the design of the Project:

·        No net loss of wetland;

·        Sustainability;

·        Wise use of the wetland.

1.4.3          These principles are embedded in the physical design of the Project and the proposed operation of the Wetland Nature Reserve:

No net loss of wetland

1.4.4          The Project will comply with the “no-net-loss in wetland” principle as stipulated in the notes of the Approved Lau Fau Shan and Tsim Bei Tsui OZP No. S/YL/LFS/7.  The fishponds will be re-profiled and enlarged through removal of some pond bunds to result in a habitat more suitable and sympathetic to wetland birds.  A corollary in doing so (enlargement and removal of pond bunds) also resulted in complying with the “no net loss in wetland” principle as there will be a slight overall increase in water body area.  The residential development site will be restricted to occupy only 5% of the Site at the southern edge. 

Sustainability

1.4.5          The enhanced fish ponds and habitats created will form a dedicated Wetland Nature Reserve.  The Proponent will be responsible for the creation, enhancement and management of the Wetland Nature Reserve during the construction phase and shall provide an undertaking to take sole responsibility for management until a successor, such as an independent Foundation, is identified to the satisfaction of EPD or its agent.

Wise use of wetland

1.4.6          The long-term management of the fish ponds in the Wetland Nature Reserve ensures the preservation of the cultural practice of aquaculture in-situ, which is consistent with concepts of “wise use” fore-shadowed in Article 3.1 of the Ramsar Convention. It also provides opportunities for ongoing research into sustainable fish production and wildlife conservation.

 

1.5              Objectives of the EIA Study

1.5.1          The main objective of this EIA study is to provide information on the nature and extent of environmental impacts arising from the construction and operation of the proposed designated projects and related activities taking place concurrently. The study will provide information for DEP’s decisions on:

·        Overall acceptability of any adverse environmental consequences that are likely to arise as a result of the proposed project;

·        Conditions and requirements for the detailed design, construction and operation of the proposed project to mitigate against adverse environmental consequences wherever practicable; and

·        Acceptability of residual impacts after the proposed mitigation measures are implemented.

1.5.2          The objectives of this EIA study, as stated in Section 2.1 of the Study Brief, are as follows:

·        To describe the proposed project and associated works together with the requirements for carrying out the proposed project;

·        To identify and describe the elements of the community and environment likely to be affected by the proposed project and/or likely to cause adverse impacts to the proposed project, including both the natural and man-made environment;

·        To identify and quantify all environmental sensitive receivers, emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;

·        To identify and quantify any potential losses or damage to flora, fauna and wildlife habitats;

·        To identify any negative impacts on sites of cultural heritage and to propose measures to mitigate these impacts;

·        To identify and quantify any potential landscape and visual impacts and to proposed measures to mitigate these impacts;

·        To propose the provision of infrastructure or mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the project;

·        To identify, predict and evaluate the residual (i.e. after practicable mitigation) environmental impacts and the cumulative effects expected to arise during the construction and operation phases of the project in relation to the sensitive receivers and potential affected uses;

·        To identify, assess and specify methods, measures and standards, to be included in the detailed design, construction and operation of the project which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;

·        To investigate the extent of side-effects of proposed mitigation measures that may lead to other forms of impacts;

·        To identify constraints associated with the mitigation measures recommended in the EIA study;

·        To identify, within the study area, any individual project(s) that fall under Schedule 2 and/or Schedule 3 of the EIA Ordinance; to ascertain whether the findings of this EIA study have adequately addressed the environmental impacts of those projects; and where necessary, to identify the outstanding issues that need to be addressed in any further detailed EIA study; and

·        To design and specify the environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution and pollution control measures adopted.

 

1.6              Scope of the EIA

1.6.1          Clause 3.2 of the Study Brief sets out the scope of the EIA study for the Project and associated works. The EIA study covers the combined impacts of all the proposed developments and the cumulative impacts of the existing, committed and planned developments in the vicinity of the Project including the Hong Kong Wetland Park, Mai Po Inner Deep Bay Ramsar Site etc., in accordance with the requirements laid down in Section 3.4 of the TM. The environmental impacts of on-site and off-site works and facilities associated with the proposed developments shall be addressed. The EIA study shall address the likely key issues described below, together with any issues identified during the course of the EIA study:

·        Noise impacts arising from construction and operation of the development to the nearby village areas;

·        Dust impacts arising from construction of the development to the nearby villages;

·        Landscape and visual impacts during construction and operation of the development;

·        Water quality impacts during construction and operation, including pond draining and filling, sewage collection, treatment and disposal systems, surface runoff and land drainage and stormwater system;

·        Potential impacts on historical buildings/architectures and monuments;

·        Wetland loss and impacts to the adjacent fishponds, Hong Kong Wetland Park, Recognized Sites of Conservation Importance including Wetland Conservation Area, Wetland Buffer Area and Mai Po Inner Deep Bay Ramsar Site due to the construction and operation of the proposed development;

·        Terrestrial and aquatic ecological impacts to the adjacent area with conservation importance and ecologically sensitive areas including the Hong Kong Wetland Park, Mai Po Inner Deep Bay Ramsar site with particular attention to possible fragmentation of the wetland, ecological link between Deep Bay area and the project area, the future buildings on the site to the bird’s flight line with special attention to the ambient light at night-time and the little woodland to the north of Fung Lok Wai;

·        Fisheries impacts during construction and operation of the development;

·        Collection and disposal of potentially contaminated dredged spoil arising from the project; and

·        Proposals for the short term and long term management of the proposed Wetland Nature Reserve with the project area including trust and financial arrangement.


1.7              Structure of the EIA

1.7.1          The structure of this EIA is as follows:

Volume 1

Section 1          Introduction

Section 2          Project Description

Section 3          Consideration of Alternative Schemes

Section 4          Air Quality Impact Assessment

Section 5          Noise Impact Assessment

Section 6          Water Quality Impact Assessment

Section 7          Potential Problem of Biogas

Section 8          Sewerage and Sewage Treatment Implications

Section 9          Waste Management

Section 10        Cultural Heritage Impact Assessment

Section 11        Landscape and Visual Impact Assessment

 

Volume 2

Section 12        Fisheries Impact Assessment

Section 13        Ecological Impact Assessment

Section 14        The Habitat Creation and Management Plan of the Wetland Nature Reserve

Section 15        The Long-term Management of the Wetland Nature Reserve

Section 16        Environmental Monitoring and Audit Requirements

Section 17        Summary of Environmental Outcome and Overall Conclusion

 

2.                  Project description

2.1              The Proposed Development and the Environs

2.1.1          The Subject Site is located at Lot 1457 R.P. in D.D. 123, Fung Lok Wai, Yuen Long and is about 2 km north of the Yuen Long New Town. To the west of the subject site is the Hong Kong Wetland Park (HKWP), with Mai Po located to its northeast and Yuen Long Industrial Estate (YLIE) to southeast. The total site area is about 80.1 ha.  Figure 21 shows the proposed Project and its environs.

2.1.2          As per the latest Approved Lau Fau Shan & Tsim Bei Tsui Zoning Plan No. S/YL-LFS/7 gazetted on 1 February 2005, the Subject Site is zoned “Other Specified Uses (Comprehensive Development and Wetland Enhancement Area)”. Figure 2‑2 refers. Pertaining to the Approved Outline Zoning Plan of Tin Shui Wai Plan No. S/TSW/11 gazetted on 26 October 2007, the planned zoning areas in the Tin Shui Wai Reserve Zone are also presented in the same figure.

2.1.3          The Subject Site abuts the Inner Deep Bay and lies within the Wetland Conservation Area. About 43 ha of the Site has been designated as a Mai Po Inner Deep Bay Ramsar Site since September 1995.

The Residential Development

2.1.4          The proposed residential development has the following basic parameters as tabulated below.

Table 21          Basic Parameters of the Proposed Residential Development

Total Site Area (approximate)

80.1 ha

Area of residential development (approximate)

4 ha

Area of wetland nature reserve (approximate)

76.1 ha

Proposed Plot Ratio

0.185

Proposed Residential GFA

148,000 m2

Design Population

8,490

No. of Flats

Not more than. 2,860 units

 

2.1.5          The about 4 ha residential site will be formed by filling the fishponds at the southern part of the Subject Site with a WNR to be established to its north. Vehicular access to the Project will be via the existing Fuk Shun Street. The whole residential site lies outside the Mai Po Inner Deep Bay Ramsar Site.

2.1.6          Figure 2‑3 presents a tentative master layout plan of the proposed residential development.

The Access Road

2.1.7          The proposed vehicular access of the site, viz. the Southern Development Access, will be via the existing Fuk Shun Street and Yuen Long Industrial Estate to Yuen Long. Fuk Shun Street is currently a substandard road. The project proponent is proposing to upgrade this sub-standard Fuk Shun Street to a standard of not less than 7.3 m single 2-lane public road with not less than 2m wide footpath on both sides of the road.

2.1.8          The EIA Study Brief stipulates in general an assessment area of 300m and 500m from the boundary of the project site including the access road with respect to noise and air quality impact assessment respectively. Figure 2‑4 shows these boundaries.

The Wetland Nature Reserve

2.1.9          The WNR will be established on the remaining 95% (about 76.1 ha.) of the site unaffected by the residential development. The WNR lies within Wetland Conservation Area while approximately half of the WNR lies within the Mai Po Inner Deep Bay Ramsar Site. The northern boundary adjoins the Inner Deep Bay Site of Special Scientific Interest (SSSI).

2.1.10      The goal of the WNR is to provide a permanent purpose-built nature reserve and compensate for any disturbances associated with the construction and operation of the residential development. The result will be no net loss in either area or function of wetland habitat.

2.1.11      No net loss in waterbodies area will be achieved through reconfiguration of fishponds to create fewer, larger but more suitable ponds for birds and the creation of a complex of freshwater marsh habitats. Increasing fishpond size has an additional benefit, as there is evidence that many wetland birds prefer larger, less enclosed water bodies to small ponds, which typify most aquaculture practices. The removal of some bunds is predicted to have low or negligible impact as their intrinsic ecological value is low. The complex of freshwater marsh habitats proposed will provide a range of additional habitats for birds and other flora and fauna, including dragonflies.

2.1.12      Functional enhancement will be achieved through enhancement of both the ponds and the approach to aquaculture management. The carrying capacity of fishponds is limited by the uniform design of ponds and management that is not specifically targeted at conservation. Modifications to both will significantly improve foraging opportunities for birds and other fauna. To ensure ongoing functional replacement, key ecological indicators, including birds, will be monitored to guide management of the reserve.

Outline Design of Wetland Nature Reserve

2.1.13      The proposed WNR will comprise two key elements (Figure 2‑5):

·        A large expanse of retained, but ecologically enhanced, fishponds; and,

·        An area of re-created ‘natural’ marshland.

2.1.14      Actively managed ponds in the Deep Bay area are currently full for most of the year and their use by birds is severely limited due to their relatively steep sides, deep water and their frequent lack of marginal vegetation. These characteristics also limit their use by other species and hence fishponds tend to have relatively low biodiversity compared to many wetland habitats.

2.1.15      The active management of fishponds for commercial purposes, however, creates a key by-product in the form of abundant “trash fish” – small, non-commercial fish and invertebrates.  When ponds are drained down during the winter months for harvesting, large concentrations of birds can be observed foraging in the shallow water for trash fish. As only a small proportion of fishponds are drained at any one time, and only for short periods, the spatial distribution of feeding birds is highly dynamic and variable as birds seek out ponds as they are drained. ‘Feeding bottlenecks’ may occur if there are insufficient ponds to support foraging bird populations.

2.1.16      Although much of the Assessment Area is composed of wetland habitats in the form of aquaculture ponds, poor water quality and unsympathetic pond design severely limit its value for most faunal groups. Furthermore, there is inadequate vegetation cover on the site to support breeding populations of most wetland birds.

2.1.17      The main objectives of enhancing fishponds are, therefore, to:

·        Increase the value of fishponds to herons and egrets outside harvesting periods (i.e. draw-down), by increasing food resources and food availability and by reducing disturbance effects. Enhancement of the value of fishponds to such birds outside harvest periods could reduce the potential for ‘feeding bottlenecks’ thereby possibly reducing the area of fishponds needed to support the population.

 

·        Increase their overall biodiversity value and suitability for other non-bird Species of Conservation Importance, such as some mammals (e.g. Eurasian Otter), amphibians and reptiles, whilst maintaining their current important functions for herons, egrets and other water birds.

2.1.18      The ponds will be enhanced through the following specific actions:

·        The size of the fishponds will be increased by re-profiling unwanted bunds.

·        Emergent vegetation will be allowed to develop.

·        Areas of shallow water and intermittently exposed muddy islands will be created.

2.1.19      The enhanced fishponds will be located away from the residential development area to minimise disturbance impacts. They will also be contiguous with the main area of fishponds in the WCA and Mai Po Inner Deep Bay Ramsar site as a whole. Maintaining a contiguous area for compensation, which is linked, with an existing area of recognized conservation importance is of significant ecological value.

2.1.20      The natural wetland area will consist of a marshland complex, including areas of shallow open mesotrophic water (i.e. of moderate nutrient status), with adjoining reed beds and other emergent vegetation, shallow margins, islands, irregular shorelines, and an area of seasonally inundated grazed marsh and pools. Such fresh water marshes are a scarce habitat in Hong Kong and would develop rich and abundant aquatic and emergent plant communities. This in turn may support rich invertebrate, amphibian and reptile communities.

2.1.21      There are three key features of this proposed layout:

·        The majority of the fishponds on site are maintained, including all those within the Mai Po Inner Deep Bay Ramsar site boundary. This avoids the loss or detrimental modification of any wetland area within the Mai Po Inner Deep Bay Ramsar site and maintains the large open contiguous block of fishpond habitat in the area.

·        The location of the proposed area for the re-creation of natural wetlands will maximise the potential for ecological links with the following complementary adjacent habitats:

o        Scrub and woodland habitats on the hillsides to the south of the site;

o        Inter-tidal mangrove habitats along the former Tai River outfall; and,

o        The wetland creation at Hong Kong Wetland Park (HKWP).

o        These habitats may provide sources for the natural spread and establishment of some plants and animals within the wetland area. In addition they will provide additional shelter, food or breeding sites for wetland species and ecological ‘corridors’, which may facilitate dispersal.

·        As the re-created wetland will contain abundant tall reed beds, as well as other tall wetland vegetation and scattered trees, this will serve as a buffer between the residential development and the fishponds. This will reduce disturbance of birds feeding within the fishponds.

 

2.2              Construction of the Project

Preliminary Construction Program

2.2.1          Figure 2‑7 shows the tentative construction programme of the Project. Construction activities are planned to commence in the 3rd quarter of 2010 for completion in the 3rd quarter of 2016. i.e. a total of 6 years. Assessments of potential construction phase environmental impacts have been carried out based on this assumed construction programme. While the actual construction programme may require adjustment during the detailed design stage, the relevant assessments as presented in this report will allow the identification of sufficient mitigation measures at an early planning stage. Implementation of sufficient environmental mitigation measures would be audited through an Environmental Monitoring and Audit (EM&A) Programme.

2.2.2          The construction programme consists of the following three main phases: -

·        First phase (3rd quarter of 2010 to 2nd quarter of 2013) - establishment of the WNR. Key construction activities to be carried out include:

o        Relocating water from Sector 1, Sector 2 and Sector 3 ponds at different phases;

o        Draining, removing bunds and installing water controls at Sector 1, Sector 2 and Sector 3 of the WNR at different phases;

o        Re-filling ponds at Sector 1, Sector 2 and Sector 3 of the WNR;

o        Selective felling and vegetation management at Sector 1, Sector 2 and Sector 3 of the WNR at different phases;

o        Land formation and water control structures construction of the Marshland area;

o        Habitat creation of the Marshland area;

o        Constructing facilities of the Marshland area, such as board walks, hides, toilets and shelters.

·        Second phase (2nd quarter of 2011 to 3rd quarter of 2016) - construction works for development area. Key construction activities to be carried out are listed below:

o        Site clearance for the construction works for development area;

o        Pond draining and dredging at built area;

o        Delivery of fill material by trucks to the site;

o        Spreading and compaction of fill material at built area;

o        Foundation and superstructure works for buildings;

o        Construction of sewage pump house;

o        Laying of drainage, sewerage and utilities;

o        Paving of internal access road.

·        Third phase (4th quarter of 2014 to 3rd quarter of 2016) – widening works of the access road leading to the Project site. Key construction activities include:

o        Site clearance and formation for the widening of the Access Road leading to the site;

o        Laying of drainage, sewerage and utilities;

o        Formation of road sub-base, levelling and compaction;

o        Road paving and installation of road furniture;

o        Construction of landscape works;

o        Soft landscape establishment works

2.2.3          The above activities are categorized and described below.

Establishment and Management of Wetland Nature Reserve

2.2.4          Except for the residential portion, the remaining fishponds at the site will be modified and converted into a WNR. The pond bunds will be re-profiled to provide shallow sloping and irregular margins to increase feeding opportunities and efficiency for herons, egrets, waders, rails and crakes etc.

2.2.5          Thirty-seven (approximately 61.7 ha) of the existing fish ponds will be modified and enhanced to increase their value for Species of Conservation Importance, particularly birds recorded regularly on the site.

2.2.6          Thirty-one out of these 37 ponds will be consolidated through bund removal to create 18 ponds with an average size of about 2.6 ha. These ponds will undergo a series of enhancement to improve their attractiveness to wildlife, particularly birds including:

·        Creation of shallows and muddy islands through re-distribution of bund material; and,

·        Cut back of vegetation.

2.2.7          The remaining six ponds will be consolidated into three and permanently set aside and planted, to varying degrees, with reeds (Phragmites australis) to provide attractive habitat for water birds, particularly duck and reed bed passerines. These ponds will be fed by rain water and their level allowed to fluctuate seasonally.

2.2.8          An area of approximately 14.4 ha adjacent to the development area will be converted into a complex of freshwater marsh habitats. This area will comprise:

·        Permanent marsh composed of a series of shallow inter-locking lakes with occasional deep areas and islands.

·        Seasonal marsh composed of vegetation that is inundated only during the wet season.

·        Storage pond. The water deficit usually experienced every dry season is a constraint on the design and management of marsh habitats. To ensure a supply of freshwater of suitable quality for the permanent marsh throughout the year an existing fishpond will be enlarged to provide storage. The optimum size of this storage has been established through modelling of typical and extreme rainfall patterns.

2.2.9          A potential alternative egretry will be constructed in a part of the WNR that is as remote as possible to minimise disturbance.

2.2.10      Water levels within the marsh complex will be managed according to broad habitat requirements – i.e. permanent or seasonal inundation. Within the permanently inundated marsh areas, levels will still be allowed to fluctuate (within bounds) to facilitate the periodic exposure of muddy areas.

2.2.11      The water supply to the natural wetland will be from direct rainfall supplemented by run-off from the residential development and catchments A and B (see Figure 2‑6). Run-off from the residential site and catchments A and B will enter the storage pond via a ditch running along the southern border of the development area. The natural wetland area will not flood surrounding land and residential developments. The lakes within the area will eventually discharge via Channel X or, during storm events, via Channel Y (see Figure 2‑6) into the Tai River outfall.

2.2.12      Figure 2‑5 illustrates the proposed design for the Fung Lok Wai WNR in the context of its surrounding. By adopting the design, there will be no net loss of but a slight increase in waterbodies area. Figure 2‑10 presents the areas of various habitats, both before and after the implementation of the ecological enhancement works.

2.2.13      In order to minimise disturbance, the intensity of the establishment works of WNR will be kept low, for site clearance works at fishponds where the proposed WNR lies, only a few ponds will be drained each time for dredging and filling, to ensure the ecological value of the area can still be maintained during the construction phase. It is intended that construction works in the WNR requiring heavy equipment be focused in the the dry season because experience gained during the construction of the Hong Kong Wetland Park indicates that the substrate may be too soft for heavy machinery to rework the ponds into the required profile during the wet season.

2.2.14      Works on the ponds will involve relatively small machinery as are used during the fishpond farming cycle. Works can be kept within each individual pond after draining down as occurs during fishpond farming operations.

Work Programme

2.2.15      The programme and stages of construction are described in detail in Section 14 of this report.

2.2.16      An outline list of the main actions necessary for the creation of the marshland and enhancement of the fish pond habitats is provided in Table 2‑2. Time periods, start and completion dates for these actions are dependent on the overall residential area construction programme, which has yet to be finalised.

2.2.17      Prior to construction works associated with the Residential Development and the WNR all ponds will continue to be managed under their existing aquaculture regime (aquaculture production).

2.2.18      The broad strategy proposed is to stage enhancement works to reduce disturbance and to complete habitat enhancement works within the northern part of the site before construction of the residential development (in the southern part of the site) commences.

2.2.19      The first stage will involve, enhancement works in the 13 existing ponds located within Sector 1 (Figure 2‑10). Once these works are complete then work can commence on ponds within Sector 2.

2.2.20      On completion of enhancement works in Sectors 1 and 2, works can commence on construction of the Created Marsh Habitat and formation of the residential area. It is proposed to coordinate these ativities to minimise use of heavy machinery on the site. Once the main structure of the marsh is formed, works can commence on Sector 3.

2.2.21      Following enhancement fishponds will be managed under the modified regime outlined in the Habitat Creation and Management Plan.

2.2.22      The major construction works involved in pond enhancement relate to the removal of bunds between adjoining ponds. To minimise disturbance to the rest of the site it is proposed that enhancement works are conducted on one pair of ponds at a time.

2.2.23      Figure 2‑11 illustrates the location of new bunds. Further details are discussed in the Habitat Creation and Management Plan (Section 14).

Interim Management

2.2.24      To compensate for disturbance associated with the construction of the residential development and the WNR, it is proposed that ponds in Sectors 1, 2 and 3 will be managed according to an interim management regime that is intended to enhance their short-term value for Species of Conservation Importance, particularly wetland birds. Enhancement will be achieved through the following specific actions which have yielded demonstrated improvements to the value of fishponds for wetland birds when implemented elsewhere in Hong Kong:

·        The fish populations within ponds will vary greatly depending on previous management. A rapid assessment of remaining populations will be carried out and ponds re-stocked, as required, with trash fish species;

·        Initial and ongoing correction of water quality, specifically pH to ensure appropriate conditions for fish survival. Although trash fish species are relatively hardy compared to many commercial fish, they can be affected by low pH conditions. If pH drops below 4.5 then peanut residue will be added to raise pH; and,

·        Rotational, partial drain down of pairs ponds. Once drained down each pair of ponds will be maintained with shallow water < 30 cm deep for a period of 4weeks.

Long-term Management

2.2.25      Once all construction works are completed, the WNR will be managed according to a long-term management plan following guidelines described within the Habitat Creation and Management Plan for the site.

 

Table 22         Habitat Enhancement Work Programme For The Fung Lok Wai WNR

Construction Phase

Period

Construction activities

Pre-construction Phase I

 

Jul 2010

Site handover

All ponds under existing management

Pre-construction Phase II

 

Oct 2010 – Mar 2011

Enhance Sector 1 ponds

All other ponds remain under existing management regime

Pre-construction Phase III

Apr – Sep 2011

Commence site clearance of Residential Development area and Marsh area

Enhance Sector 2 ponds

Interim management of Sector 1 ponds.

Sector 3 and marsh area ponds remain under existing management regime

Pre-construction Phase IV

Oct 2011 – Mar 2012

Continue site clearance and forming of Residential Development area

Commence Marsh Creation works

Interim management of Sector 1, 2 and 3 ponds

Pre-construction Phase V

Apr – Sep 2012

Continue site clearance and forming of Residential Development area

Complete Marsh Creation works and commence establishment

Enhance Sector 3 ponds

Interim management of Sector 1 and 2

Pre-construction Phase VI

Oct 2012 – Jun 2013

Continue site clearance and forming of Residential Development area

Establishment of Marsh habitats

Interim management of Sector 1, 2 and 3 ponds

Construction Phase

Jul 2013 – Sep 2016

Residential Development construction

Management of Marsh habitat

Interim management of Sector 1, 2 and 3 ponds

Operation Phase

Oct 2016 onwards

Occupation of Residential Development

Long-term management of the WNR

 

Improvement works of Access Road Leading to the Subject Site

2.2.26      Based on a preliminary MLP, the existing Fuk Shun Street will be used as the proposed access road of the proposed residential development and the WNR.

2.2.27      Fuk Shun Street roots from the southern side of the Site and terminates at Fuk Hi Street at northern side of Yuen Long Industrial Estate. It is currently a local road of various widths ranging between 6m to 7m. It is the principal access of Ng Uk Tsuen and other scattered developments along the road.

2.2.28      As Fuk Shun Street is currently a substandard road, the project proponent is proposed to upgrade it to a 7.3m wide single 2-lane road with standard 2m wide footpath provided on both sides of the road (see Figure 2‑8).

2.2.29      Improvement works at Fuk Shun Street is planned to be completed in the 3rd quarter of 2016 prior to the occupation of the Project.

2.2.30      Various construction activities of the improvement of access road include site clearance and formation, laying of drainage, sewerage and utilities, formation of road sub-base, levelling and compaction, road paving and installation of road furniture.

Construction Works for the Residential Development

2.2.31      The Subject site is currently occupied by a total of 56 fishponds, which are fed by rainwater. Overflowing to the nearby rivers occurs in heavy rainstorms. Figure 2‑9 presents a pond numbering system used throughout in the EIA before the construction of the WNR.

2.2.32      The residential portion of the Project will be located at the southwestern edge of the Subject Site and occupies around 5% of the entire site (approximately 4ha). A total of 5 existing bunded ponds No. 19, 23, 25, 59 and 62 will be affected.

2.2.33      All the bunds situated within the residential site will be demolished during site clearance. In order to minimise the generation of solid waste, the demolished materials from the bunds will be temporarily stored on-site and re-used as filling materials for the Project.

2.2.34      After the clearance of bunds, the affected ponds will be dredged, and filled, with fill materials spreaded over the site and compacted to form the residential area. These works will be completed prior to the commencement of foundation and superstructure works.

2.2.35      To the extent possible, pond draining and dredging will be planned during the dry seasons when water levels of the fishponds are relatively lower and the substrate will not be too soft.

2.2.36      During ponds draining, the opportunities to retain the existing pond water for reuse will be maximized through re-distribution of the pond water at the worksite to other existing ponds as far as practicable so as to avoid discharging them to the nearby river channel.

2.2.37      Excavators used in common civil works will be employed for pond dredging. From the experience of the development at Tin Shui Wai, the amount of topsoil required to be dredged is estimated to be about 0.3m deep i.e. 12,300m3 of dredged materials will be generated. The dredged substrate will also be temporarily stored and reused on-site for the establishment of the WNR.  It is anticipated that there will be no surplus dredged materials to be disposed of. If there is any, the dredged pond sediment which is usually not allowed to be disposed of at landfills and also may not be accepted by the public fill area because of its high organic content, will adopt marine disposa1. It is understood that before any disposal, a full set of parameters as required under ETWB TCW No.34/2002 will be tested to determine the disposal options.

2.2.38      Spreading and compaction of fill material will be performed at the residential area after pond filling. It is envisaged that fill materials such as marine sand or recycled C&D materials would be used for pond filling at residential area and this would be brought to site by dump trucks via the access road. The quantity of fill materials required for the residential area is estimated to be in the range of 94,300 m3.

2.2.39      Bored piling will be employed for foundation works for the residential buildings. The internal roads, drainage and utilities can be constructed under the respective development packages. The residential blocks will be constructed on suspended slab to address settlement problem while the pavement can be constructed on slab at grade. For using bored piling, it is estimated that some 180 numbers of 2.5m diameter bored piles will be required.

2.2.40      Furthermore, a small sewage pumping facilities and associated sewers will be constructed within the development to divert the sewage to public sewers leading to existing public sewerage network for ultimate treatment at Government sewage treatment works. The sewage will be domestic in nature and no industrial wastewater will be generated.

2.2.41      All the associated sewers within the residential development will be built beneath the building areas. Further details of the sewage pump house and sewers are presented in Section 8 - Sewerage and Sewage Treatment Implications.

 

2.3              Potential Concurrent Projects that Could Lead to Cumulative Impacts

2.3.1          According to the EIA study of “Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2” (EIA-094/2004) approved on 17 June 2004, there are two schemes proposed – Conforming Scheme of 2A-1T and Alternative scheme of 2A-1. Two of the Designated Projects (DPs) identified in the project are Package 2A-1T and its alternative, which are the construction of the Yuen Long Sewerage Treatment Works (YLSTW) Effluent Pipeline. They will be close to the Project as they include the construction of pumping station to the north of YLSTW and twin rising mains. In particular the twin rising mains of Package 2A-1T will be laid from YLSTW to Tin Tsz Road in Tin Shui Wai via the southern boundary of the Project. EIA-094/2004 concluded that the Alternative scheme of 2A-1T which was further away from the Fung Lok Wai Project was the preferred option. However, the proposed sewerage project is now classified as a Category B project under the Public Works Programme. It is our understanding that Drainage Services Department (DSD) is preparing to conduct the feasibility study.  The final alignment and construction schedule of the sewerage works as discussed in the approved EIA report is not confirmed.  After carrying out and confirmation of the feasibility study, DSD will initiate the detail design process and get funding approval from the Legislative Council.  It is estimated that DSD will need years to complete the study, design and approval process. Therefore, no construction programme is available at the present stage for the proposed sewerage work.  On the other hand, construction work for the proposed residential development at the Subject Site is scheduled to complete by 2016. Since there is no anticipated overlapping of construction works between the two projects, hence cumulative dust impact assessment is considered not necessary.

2.3.2          The construction of Hong Kong Wetland Park (HKWP) has been completed and is considered to have no cumulative impact on the construction work of the Project.

2.3.3          The HKWP is located to the east of the Project site.  Mitigation measures as presented in Section 4.4 and Section 5.6 to 5.7 are proposed to minimize the potential air and noise impacts on nearby ASR and NSR, including the HKWP. In addition, the water bodies of the HKWP and the Project are not inter-connected. Given no significant amount of water will be discharged to the surrounding water bodies by the Project during the construction and operational phase and all domestic sewers of the Project would be diverted to the public sewerage system. It is thus considered that no unacceptable impacts would be imposed on the HKWP by the Project during both the construction and operational phase. Further details on water quality impact and sewerage implications are discussed in Section 6 and Section 8 respectively.

2.3.4          The possible concurrent projects in the vicinity of the subject site are illustrated in Figure 2‑12.

 

3.                  Consideration of alternatives schemes

3.1              Background

3.1.1          The Site has a long planning history dating back to 1980’s.  The initial development proposal was to develop the site for low density residential houses and a golf course.

3.1.2          Realizing the ecological importance of the Site to wildlife, in particular to birds, the land owner subsequently made various applications to the Town Planning Board for the permission of a development comprising low density houses on about half of the site and a nature reserve on the remaining half in the early 1990’s.  These applications were all rejected by the Board.

3.1.3          The development proposal then further evolved to be more sympathetic to the ecological value of the Site.  A revised development scheme comprising apartments development on a development footprint of only 5% (i.e. 40,000m²) of the Site with plot ratio of 0.185 plus a 76 Ha (95% of the Site) Wetland Nature Reserve was proposed to the Town Planning Board in 1999.  This proposal was accepted by the Board.  As a consequence, the Site was rezoned to “Other Specified Uses – Comprehensive Development and Wetland Enhancement Area” with a maximum gross floor area of 148,000m² in 1999.

3.1.4          As presented in the Project Profile (No. PP-091/2000), the preliminary MLP has a footprint area for the residential development at the southwestern corner of the Subject Site with an access road to the west. The approximate size of this footprint for the residential area is 4 ha. The original preliminary layout of the Project is illustrated in Figure 3‑1.

3.1.5          In accordance with the requirements of the EIA Study Brief (ESB-055/2000) issued by EPD under the terms of the EIAO in 2000, ecological investigations were undertaken at Fung Lok Wai including a 12-month flora and fauna survey between January and December 2001.

 

3.2              Identified constraints

3.2.1          Analysis of the baseline data obtained from the ecological surveys indicated three constraints on the proposed development:

·        The location of the egretry (present at the time of ecological survey but is now abandoned) in the southern part of the assessment area could result in flight line interference of birds attempting to access food resources within Fung Lok Wai;

·        Accessing the site from the west adjacent to the Hong Kong Wetland Park, as originally proposed, will require additional construction work and may potentially cause disturbance to the egretry; and

·        It is desirable to maintain linkages between all the wetland habitats within the Fung Lok Wai assessment area, including the mosaic of wetlands in the southern part of the Assessment Area.

 

3.3              Modifications of the development proposal to meet the identified constraints

3.3.1          To minimize the potential direct and indirect impacts of the residential development on the habitats and species populations of Fung Lok Wai, a range of development options have been examined and several modifications are made to the development proposal (Figure 3‑2) including:

·        Shifting of residential development area;

·        Alternative route for development access; and

·        Establishment of a potential alternative egretry within the proposed Wetland Nature Reserve.

 

3.4              Shifting of Residential Development Area

3.4.1          A four-season ecological survey and flight path study was conducted to investigate the impacts of the presence of buildings on the bird flight path in January 2001. Details of the survey including the methodology and findings are presented in Section 13 Ecological Impact Assessment.

3.4.2          During the survey, a newly formed egretry was identified in April 2001 to the southwest of the subject site located within the Fung Shui Woodland at Shing Uk Tsuen. Initial analysis of the original proposed location of the residential development area indicated the potential for interference with the flightlines of herons and egrets moving to and from the egretry.  The flight path patterns showed that most flights occur at low altitudes and are equally affected by low or high rise buildings and location of the buildings is more important than building height in respect of obstruction to flight path.

3.4.3          Consequently, various options were considered to investigate the impacts of the location of the development footprint.  It was found that while shifting the development footprint eastwards, obstruction to bird flight path would decrease.  However, with the development footprint moves more and more towards the centre position along the southern boundary, it will result in more disturbance impacts to the proposed Wetland Nature Reserve.

3.4.4          Balancing the above said factors, it was decided that the proposed development area be moved approximately 150m eastwards of its original position (i.e. about 200m away from the egretry).  This will dramatically reduce potential interference with flight lines associated with the egretry and will provide an additional benefit of retaining the linkage between the Fung Lok Wai wetlands and the adjacent wetlands lying to the south and southwest of the site.

 

3.5              Alternative Route for Development Access

3.5.1          Two alignments for the access road to the Project are considered, namely the Western Development Access (which is the access proposed in the Project Profile) and the Southern Development Access (which is an existing access from Fuk Shun Street).

The Western Development Access

3.5.2          The Western Development Access follows an existing village track from the west along the southern boundary of the Hong Kong Wetland Park.  This road will connect the western boundary of the subject site to Junction P (Tin Wah Road/Wetland Park Road/Tin Tsz Road) in Tin Shui Wai.

Engineering Concerns

3.5.3          It is proposed that the existing village track will be upgraded and widened to a 6.75m wide single carriageway with one-sided footpath (1.6m wide).

Land Status

3.5.4          The proposed access road will be entirely on government land albeit a portion of the road (about 4,543 m²) will encroach into the Hong Kong Wetland Park boundary.

Air and Noise Impacts

3.5.5          A few village huts are found locating near the Western Development Access. They will be mostly affected if the Western Development Access is adopted.

Ecological Impact

3.5.6          The footprint of the access road comprises six habitats namely intertidal forested wetlands (8 m²), permanent stream (6 m²), grassland (2,004 m²), aquaculture pond bund (460 m²), wasteland (2,291 m²) and works-in-progress (2,047 m²).

3.5.7          Apart from the intertidal forested wetlands (8 m²) and the permanent stream (6 m²) which are of high and moderate ecological value respectively, all other habitats affected by the road are of low ecological value.

3.5.8          Although there are potential disturbance generated during construction and operation of the access road to wetland birds which roost and forage within the intertidal forested wetlands present along the southern boundary of the Hong Kong Wetland Park, these impacts can be satisfactorily mitigated.

3.5.9          Possible impacts may occur on the flight lines of Ardeids from the Shing Uk Tsuen egretry across the access road to the Hong Kong Wetland Park and the Wetland Nature Reserve.

Landscape and Visual Impact

3.5.10      The Western Development Access would skirt the fishpond area to the north of the development site leading to landscape and visual disturbance of the existing fishponds.

3.5.11      The footprint of the proposed Western Development Access would lead to the additional loss of landscape resources namely wetlands (8 m²), watercourses (6 m²) and grassland (2,004 m²). The proposals would also lead to the loss of approximately 100m length of scrub on the existing pond bund along the south western boundary of the proposed WNR. This area acts as a landscape buffer between the existing intact fishpond areas which form the large part of the proposed WNR and the abandoned fishpond area to the south west.

The Southern Development Access

3.5.12      The Southern Development Access is via an existing village road Fuk Shun Street connecting the subject site with Yuen Long Industrial Estate.

Engineering Concerns

3.5.13      Fuk Shun Street is currently a surfaced substandard road.  In order to use it as development access, it would be necessary to widen it to about 7.3 m wide single 2-lane road with 2 m wide footpath provided on both sides of the road.

Land Status

3.5.14      The road widening works will involve government land only.  However, it will be subject to government’s assistance in the clearance of any licence, short-term tenancy or unauthorised occupation along the existing roadside.

Air and Noise Impacts

3.5.15      A number of low-rise village houses are built along both sides of Fuk Shun Street.  However, with the mitigation measures proposed in Chapters 4 and 5 in place, the air and noise impacts can be satisfactorily mitigated.

Ecological Impacts

3.5.16      As the Southern Development Access is already a surfaced road in operation running through Yuen Long Industrial Estate, the use of this road for access will have no ecological impact.

Landscape and Visual Impact

3.5.17      The Southern Development Access would involve the widening of the existing Fuk Shun Street through Tai Tseng Wai within the existing land take and so would not lead to any significant further loss of landscape resources within the Study Area. Beyond the short term construction phase impacts relating to the disturbance of the existing landscape the operational phase would not lead to any degradation of the landscape character of the existing road corridor or the visual amenity available to the residents of the adjacent village houses.

3.5.18      The table below compares the two access options:

 

Table 31         Comparison of the Two Access Options

 

Western access

Southern access

Engineering concerns

Upgrading an existing village track to 6.75m wide with one-sided footpath (1.6m wide)

Widening an existing substandard surfaced access to about 7.3m wide single 2-lane road with 2m wide footpath on both sides of the road

Land Status

-Entirely on government land

A portion of the road (about 4,543m²) will encroach into the Hong Kong Wetland Park boundary

Entirely on government land, however, government’s assistance in the clearance of any licence, short term tenancy or unauthorised occupation if any along the existing roadside is required

Air & noise impacts

A few village huts near the access will be affected by the road

Some village houses near the access will be affected.  However with the proposed mitigation measures in place, impacts can be mitigated satisfactorily

Ecological impact

Impact on a small area (8 m²) of intertidal forested wetlands which is of high ecological value

Potential disturbance to wetland birds roosting and foraging in the intertidal forested wetlands within the Hong Kong Wetland Park and the Wetland Nature Reserve but can be satisfactorily mitigated

Possible impacts may occur on the flight lines of Ardeids from the Shing Uk Tsuen egretry across the access road to the Hong Kong Wetland Park and the Wetland Nature Reserve.

As the Southern Development Access is already a surfaced road in operation running through Yuen Long Industrial Estate, the use of this road for access will have no ecological impact.

Landscape & visual

Landscape and visual disturbance of the fishponds including the additional loss of landscape resources.

Short-term construction phase impacts relating to the disturbance of the existing road landscape. The operational phase would not lead to any degradation of the landscape character of the existing road corridor or the visual amenity available to the residents of the adjacent village houses.

 

 

3.5.19      Taking into account the above said factors and the shifting of the residential development to a more easterly location, the Southern Development Access is considered to be more preferable especially from ecological perspective.

 

3.6              Establishment of a potential alternative egretry within the Wetland Nature Reserve

3.6.1          During the four-season ecological survey, an egretry on the southwest perimeter of the Assessment Area was found established in April 2001. The flightlines of birds to and from this egretry tended to track across the southwest corner of the study site, particularly at low altitudes (<40m).

3.6.2          It was found that by shifting the development footprint eastwards to 200m away from the egretry location, the obstruction to the flightlines from the egretry to the Wetland Nature Reserve can be substantially reduced and that a reasonable buffer is maintained between the residential development and the egretry.  Furthermore, a further measure is proposed by creating a potential alternative egretry of similar size (about 2,000 m²) and plant species within the Wetland Nature Reserve.  Although the egretry was subsequently found abandoned, a potential alternative egretry is proposed in the northeastern section of the Study Site, which will be subject to minimal disturbance from both the construction, and operational stages of the development.

 

3.7              Consideration of Alternative Building Heights

3.7.1          In accordance with the requirements of Clause 3.5.9.5(iv) under the Landscape and Visual Impact section of the Study Brief, alternative building heights of maximum 10-storey, 15-storey and 25-storey shall be assessed to examine the visual compatibility with the surrounding rural setting. 

3.7.2          Three development options for the residential portion are assessed: (Figure 3‑3a to c and Figure 34)

·        Option 1A – all buildings not more than 18 storeys (8 blocks of 14-18 storeys, 7 groups of low-rise buildings of 4-8 storeys including a resident’s club house erected on 40,000m² residential site area i.e. 32.8% Site Coverage);

·        Option 1B – all buildings not more than 15 storeys (9 blocks of 15 storeys, 7 groups of low-rise buildings of 4-10 storey including a resident’s club house erected on 40,000m² residential site area i.e. 34.4% Site Coverage); and

·        Option 1C – all buildings not more than 10 storeys (29 blocks of 7-10 storeys, 27 4-storey terrace houses and a resident’s club house erected on 60,000 m² residential site area i.e. 34% Site Coverage).

3.7.3          Full details of the assessment are presented in Section 11 Landscape and Visual Impact Assessment.

 

3.8              Comparison of Development Options

3.8.1          In respect of air quality impact, noise impacts, water quality impacts, sewerage and sewage treatment implications, waste management implications, fisheries impact and cultural heritage impact, , the impacts on the three development scenarios, namely Option 1A, Option 1B and Option 1C are considered similar and acceptable. However, the three options will differ in the aspects of ecological impact and landscape and visual impact.  The following table sets out the comparison:

 

 

Option 1A

Option 1B

Option 1C

Development parameters

Residential Development Site Area

4 Ha

4 Ha

6 Ha

GFA

148,000 m²

148,000 m²

148,000 m²

Building height

Medium-rise blocks:    14 to 18 storeys

Low-rise blocks:        4 to 8 storeys

Club house: 2 storeys

Medium-rise blocks:  15 storeys

Low-rise blocks:      4 to 10 storeys including club house

Low-rise blocks:    7 to 10 storeys

Terraced houses:       4 storeys

Club house: 2 storeys

No. of blocks

Medium-rise blocks: 8

Low-rise blocks: 6

Club house: 1

Medium-rise blocks: 9

Low-rise blocks: 7 including club house

Low-rise blocks: 29

Terraced houses: 27

Club house: 1

Building site coverage on Residential Development Site Area

About 32.8% of 4 Ha site area

About 34.4% of 4 Ha site area

About 34% of 6 Ha site area

Site area of the Wetland Nature Reserve

76 Ha

76 Ha

74 Ha

Compliance with planning intention of “OU(CDWEA)” zone under Outline Zoning Plan

Compliance with “No net loss in wetland” principle

Yes

Yes

No

Ecological Impacts

Habitat loss

No net loss of wetland area achievable through pond enlargement and marsh habitat creation

No net loss of wetland area achievable through pond enlargement and marsh habitat creation

Net loss of wetland area will arise

Habitat fragmentation

Fragmentation will be low due to relatively small footprint and maintenance of sight lines for birds

Fragmentation will be slightly greater than Option 1A as there will be less visibility for birds due to greater number of buildings – more obstruction of sightlines

Fragmentation will be greater than Options 1A and 1B as there will be less visibility for birds due to greater number of buildings – more obstruction of sightlines. The larger footprint will also reduce connectivity between fish pond habitats and wetland mosaic habitats

Disturbance

Predicted disturbance of sensitive species, particularly birds, during construction and operation can be fully mitigated through interim and long-term management of the WNR

Predicted disturbance of sensitive species, particularly birds, during construction and operation can be fully mitigated through interim and long-term management of the WNR

Disturbance effects greater than Options 1A and 1B (due to large development area) and area for compensation (WNR area) will be less. It is less likely, therefore, that disturbance effects can be fully mitigated

Pollution

No significant pollution effects predicted

No significant pollution effects predicted

No significant pollution effects predicted

Soil compaction

 

No significant soil compaction effects predicted

No significant soil compaction effects predicted

No significant soil compaction effects predicted

Hydrological disruption

No significant hydrological disruption predicted

No significant hydrological disruption predicted

No significant hydrological disruption predicted

Landscape and Visual Impacts

Landscape Resources

Residential development area is restricted to 4 Ha to minimize the impact on landscape resources

Impacts on landscape resource similar to those for Option 1A.

Larger impact on landscape resource due to increased residential development area resulting in greater loss in fishponds and larger extent of land formed area.

Landscape Character

Residential development area is restricted to 4 Ha to minimize the impact on the existing landscape character

 

Impacts of Option 1B on the existing landscape character of the area similar to those for Option 1A due to the shared characteristics of the two schemes.

The larger residential development area leading to the truncation of the fishponds from the wooded hill sides which form their settings, the loss of area and the indirect impacts on the character of the remaining fishponds will be greater than in Option 1A & Option 1B

Visual Impacts

The developments adopts a medium-rise form utilising a stepped building profile (14-18 storeys) in response to the existing landform and maximises visual permeability through the creation of view corridors and sky gardens allowing visual access to the hillsides beyond through the locations of the low-rise buildings between the proposed medium-rise blocks. This development profile will minimize the visual impacts experienced by nearby VSRs. The slightly taller buildings in Option 1A (14-18 storeys) will have a slightly greater impact on the VSRs immediately adjacent to the proposed development including the residents on the northern periphery of Ng Uk Tsuen and Shing UK Tsuen than in Option 1B which is lower in height at 15 storeys

The medium-rise form of Option 1B (15 storeys) incorporates blocks of equal height (15 storeys) and will not incorporate the stepped building height profile. Although the constant height for the individual blocks will not create the same dynamic relationship in terms of the building form with the existing landscape context which exists with Option 1A, the slightly lower buildings than in Option 1A has improved the impact on the VSRs immediately adjacent to the proposed development.  Similar to Option 1A the creation of a permeable and responsive building form preserves, as far as possible, the visual relationship between the existing estuarine landscape and its setting of wooded hillsides.

Option 1C comprises buildings of 7-10 storeys aligning along the southwest portion of the site and 4-storey terraced houses fronting onto the WNR.  Although when viewed from a distance, this development form is more akin to the traditional vernacular village architecture of the region in terms of its form, the development does not respond to the visual dynamics of the existing landscape context especially when viewed from the north the development visually coalesces to form a wall with no visual access to the landscape beyond.

 

3.8.2          Only Option 1A and Option 1B can comply with the planning intention of “OU(CDWEA)” zone for the principle of “no net loss in wetland” as stipulated in Outline Zoning Plan No. S/YL-LFS/7.

3.8.3          In respect of ecological impacts Option 1C will result in a net loss of wetland area. It has the largest development site area which will result in greater level of disturbance to the WNR. Under Option 1C the WNR will be correspondingly smaller reducing the area available for wetland compensation. On this basis the potential ecological impacts arising from Option 1C are considerably greater than those arising from Options 1A and 1B.

3.8.4          The ecological impacts of Options 1A and 1B are similar in many respects and are considered acceptable.  The only slight difference between these two options arising from the larger number of buildings in Option 1B. The gaps between buildings will be smaller in this option creating a slightly greater blockage of sightlines for birds. It is predicted, therefore, that Option 1B will result in slightly greater habitat fragmentation than Option 1A. On this basis there is a preference for Option 1A over 1B on ecological grounds.

3.8.5          The findings of the assessment suggest that Options 1A and 1B are more acceptable than Option 1C from a landscape and visual perspective due to responsive building heights, incorporation of view corridors and their smaller development site area. This allows both schemes to be better integrated into the landscape and visual context while maintaining the relationship between the upland and the flat expanse of the coastal plane. While both Options 1A and 1B are acceptable from landscape and visual impact point of view, Option 1B is slight better than Option 1A in respect of the slightly lower buildings which will improve the impact on the VSRs immediately adjacent to the proposed development. Whereas Option 1C which although having slightly lower building height would create wall like affect due to the number of buildings required, the consistent building heights and the lack of space available for the creation of view corridors. In addition the more extensive development site area would lead to an additional loss of landscape resources and create barrier between the fishponds and their upland setting.

 

3.9              The Preferred Development Option

3.9.1          In order to minimize the potential impacts of the residential development on the habitats within the Study Area, the proposed residential development area has been shifted eastwards to 200m from the (now abandoned) egretry at Shing Uk Tsuen and the Southern Development Access is adopted.  Figure 3-5 shows the original location and the shifted location of the proposed residential development. The development options with development area of 4 ha (i.e. Option 1A and 1B) are the preferred scenarios from both ecological impact and landscape and visual impact perspectives.

3.9.2          Option 1C will result in a net loss of wetland area and is therefore eliminated from further study.  The development options with development area of 4 ha (i.e. Option 1A and 1B), which will result in no net loss in waterbody area, are similar in many respects such as air quality impact, noise impacts, water quality impacts, sewerage and sewage treatment implications, waste management implications, fisheries impact and cultural heritage impact. However, in respect of ecological impacts Option 1A is slightly superior to option 1B whereas in respect of landscape and visual impacts Option 1B is considered slightly superior to Option 1A.  In general terms though these differences are slight and the environmental impacts of both Options 1A and 1B are found to be acceptable and are therefore taken as the preferred scenarios for this environmental impact assessment exercise.

 


4.                  air quality impact

4.1              Introduction

4.1.1          This section presents an air quality impact assessment for the construction of the Project in accordance with Clause 3.5.1 of the Study Brief. Fugitive dust emissions from construction activities are considered a key issue and are hence addressed here. Air quality impact during the operational phase of the Project is expected to be insignificant and is not required in the Study Brief.

4.1.2          This section addresses the potential air quality impact associated with the construction of the proposed residential development, the associated access road and the Wetland Nature Reserve at Fung Lok Wai. Air sensitive receivers (ASRs) have been identified in the vicinity of the Project with representative ones selected for this assessment to predict quantitatively the possible worst-case impact.

4.1.3          The assessment covers an area of 500m from the Project site boundary (including the Southern Development Access) in accordance with the requirements of the EIA Study Brief. (Appendix 1-1 refers).

 

4.2              Legislation and Guidelines

4.2.1          The principal legislation regulating air quality in Hong Kong is the Air Pollution Control Ordinance (APCO) (Cap. 311).  Air Quality Objectives (AQOs) are set for the whole territory, which specify the statutory limits for various criteria pollutants and the maximum numbers of times of exceedance allowed over a specified period of time.  The AQOs for Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Total Suspended Particulates (TSP) and Respirable Suspended Particulates (RSP), which are relevant to this assessment, are summarised in Table 41 below.

 

Table 41         Hong Kong Air Quality Objectives

Pollutant

Pollutants Concentration (μg/m3)

Averaging Time

1 hour (i)

8 hours (ii)

24 hours (ii)

1 year (iii)

CO

30,000

10,000

N.A.

N.A.

NO2

300

N.A.

150

80

SO2

800

N.A.

350

80

TSP

N.A.

N.A.

260

80

RSP

N.A.

N.A.

180

55

 

(i)       Not to be exceeded more than 3 times per year;

(ii)      Not to be exceeded more than once per year;

(iii)     Arithmetic means;

N.B.   Concentrations measured at 298 K and 101.325 kPa (one atmospheric pressure).

 

4.2.2          In addition to the AQOs, EPD requires under Annex 4 in the Technical Memorandum on EIA Process issued under the EIA Ordinance an hourly TSP limit of 500mg/m3 for construction dust impact assessment.

4.2.3          It is noted that the Air Pollution Control (Construction Dust) Regulation came into effect since 16 June 1997.  Site formation, construction of the foundation and superstructure of buildings, road construction works, etc. are classified as “notifiable work” under the Regulation.  Any works which involve stockpiling of dusty materials, loading, unloading or transfer of dusty materials, transfer of dusty materials using a belt conveyor system, use of vehicles, debris handling, excavation or earth moving, site clearance, etc. are regarded as “regulatory work”. 

4.2.4          A Schedule specifying the dust control requirements for a variety of construction activities is included in the Regulation. Contractors responsible for a construction site where a notifiable work and/ or regulatory work is involved have to ensure that the work is carried out in accordance with the Schedule with regard to dust control.

 

4.3              Ambient Air Quality

4.3.1          Quantitative air quality impact study requires the consideration of background air quality for presentation of the cumulative impact. The ambient air quality in the assessment area has been assumed to be same as the annual average of air pollutant concentrations of NO2, RSP, TSP and SO2 measured at EPD’s Air Quality Monitoring Station in Yuen Long.

4.3.2          Average values for each pollutant in year 2002 to 2006 were obtained and summarised below in Table 42

 

Table 42         Annual Average Concentrations of NO2 and RSP measured at EPD’s Air Quality Monitoring Station in Yuen Long from 2002 to 2006

Air Pollutant

Concentration (mg/m3)

NO2

60

TSP

100

RSP

62

SO2

24

 

4.4              Construction Phase Impact

4.4.1          The construction of the Project is scheduled to commence in the 3rd quarter of 2010 and will be completed by the 3rd quarter of 2016. Various construction activities include site clearance and formation for construction of access road and the residential portion of the Project, ponds draining, dredging and filling, foundation and superstructure works, roadworks, construction of sewerage facilities, and establishment of the Wetland Nature Reserve, etc. No concrete batching plants and crushers would be necessary for the works. In addition, blasting would not be required.

Major Sources of Air Quality Impact

4.4.2          Major sources of air quality impact during the construction phase would be fugitive dust emissions. Emissions of other air pollutants such as carbon monoxide and dioxide, nitrogen oxides and sulphur dioxide generated by powered mechanical equipment and vehicle exhausts on-site should not be significant, considering their limited number and percentage on-time on-site. 

4.4.3          There will also be emissions from diesel trucks used in haulage of materials.  As there will only be limited number of trucks concurrently on-site, impact on the air quality is not considered significant.

4.4.4          Other major sources of dust emissions could be attributed to the following activities: -

·        Unloading of fill materials from dump trucks for pond filling;

·        Vehicle movements on unpaved haul roads;

·        Wind erosion on exposed ground and stockpiling areas; and

·        Handling of excavated material and construction debris.

4.4.5          The residential portion of the Project will occupy an area of approximately 4 ha. It is envisaged that the total amount of topsoil that could be dredged (~12,300m3) from the residential portion can be retained and transferred within the site as fill material for the establishment of the WNR during the 4th quarter of 2011 to 1st quarter of 2012. Given that the materials are mainly derived from fishponds with high moisture content and dredging works will be carried out at a few fish ponds each time, fugitive dust emission is not considered a problem during ponds dredging, re-profiling of pond bunds and partial filling of ponds at the WNR.

4.4.6          As the access road of the Development will rely on existing paved Fuk Shun Street, the limited site clearance works and junction improvement works to widen the road will be constructed in 50m section by section. The volumes of excavated spoil are expected to be low.  The number of vehicle trips during construction is expected to be very small and vehicle movements will be on existing paved roadways. The construction works for access road is anticipated to cause insignificant dust emission impacts when the construction mitigation measures as recommended in Section 4.4.25 are implemented and through the Environmental Monitoring & Audit programme.

4.4.7          The sewers will be constructed in 50m section by section. With such small scale of construction works, the potential dust impact would be limited and short term in nature. The volumes of excavated spoil are expected to be low. The number of vehicle trips during construction is expected to be very small and for most areas, vehicle movements will be on paved roadways. Only minimal movement of vehicles on unpaved roads is anticipated. Subject to government’s approval on the sewer alignment along Fuk Shun Street, the sewers will be constructed together with the improvement works on Fuk Shun Street.

4.4.8          Particulate emission rates of the dust emitting activities given in Section Error! Reference source not found. were based on typical values and emission factors documented in Compilation of Air Pollutant Emission Factors (AP-42) 5th Edition published by USEPA. Dust emission sources resulting from material handling and excavation have been modelled as point sources. Dust generation from traffic movement on unpaved site roads have been modelled as line sources. Detailed calculation of emission factors are given in Appendix 4-1.

Evaluation of Dust Impacts

4.4.9          Critical periods of fugitive dust emissions will be during land formation for the marshland (i.e. between 4th quarter of 2011 and 1st quarter of 2012) and site formation for the residential portion of the Project when fill material have to be imported and handled for ponds filling, spreading and compaction (i.e. between 2nd quarter of 2012 and 1st quarter of 2013). For the prediction of the worst-case dust impact, all the major activities in each of the 2 stages described in Section 4.4.15 below have been modelled and are assumed to be in concurrent operation.

4.4.10      The fill materials imported for land formation of marshland will be in composition similar to pond mud while the fill materials imported for site formation of residential portion are anticipated to be marine sand and recycled C&D materials. Both of those imported materials are in relative high moisture content. Thus the dust emissions modelled are anticipated to be in conservative estimation. 

4.4.11      As the topsoil beneath the ponds are of high moisture content and dredging works will be carried out at a few fish ponds each time, dust emission is not considered a problem during pond dredging at residential portion, and re-profiling of pond bunds, partial filling of ponds during the establishment of WNR if mitigation measures are properly implemented. 

Air Sensitive Receivers

4.4.12      Existing and planned residential developments at Tin Shui Wai are more than 500m away from the Project, only those existing village huts scattered around the Project, mostly at the southern side of the Site, are identified as Air Sensitive Receivers (ASRs). Worst affected representative points were selected for the assessment. The locations of these representative ASRs are shown in Figure 4‑1 and are described in Table 4‑3.

4.4.13      These representative ASRs are all situated close to the Project. Should the dust impact on these worst affected representative ASRs be mitigated to an acceptable level, dust impact on other ASRs on the assessment area should also be mitigated satisfactorily.

4.4.14      Particulate levels were predicted at the representative ASRs at 1.5m and 4.5m and 7.5m above ground for the 3–storeys village huts. 

 

Table 43         Representative ASRs for the Dust Emission Impact Assessment

ASR Label

Type of ASRs

No. of Storeys

Distance from boundary of FLW Site

Assessment Point (metres above ground)

A1

Village House (Man Wa Garden)

3

32 m

1.5, 4.5, 7.5

A2

Village House

3

104 m

1.5, 4.5, 7.5

A3

Village House

3

124 m

1.5, 4.5, 7.5

A4

Village House

3

127 m

1.5, 4.5, 7.5

A5

Village House (Tin Hau Temple)

1

126 m

1.5

A6

Village House (Ng Uk Tsuen)

1

214 m

1.5

A7

Village House

1

15 m

1.5

A8

Village House

1

33 m

1.5

A9

Village House

1

22 m

1.5

A10

Village House

1

249 m

1.5

A11

Village House

1

32 m

1.5

A12

Village House

1

9 m

1.5

A13

Village House

1

9 m

1.5

A14

Village House

1

34 m

1.5

A15

Village House

1

27 m

1.5

 

Methodology

4.4.15      Fugitive dust impact on nearby existing ASRs have been predicted for the following identified worst case construction stages: -

·        Stage A - land formation works for the marshland area (4th quarter 2011 to 1st quarter 2012)

·        Stage B - Site formation works for pond filling, spreading and compaction of fill materials at the residential footprint (2nd quarter 2012 to 1st quarter 2013)

4.4.16      The air quality model “Fugitive Dust Model” (FDM), which was specifically developed for the prediction of fugitive dust emissions is well accepted by EPD and the USEPA for this purpose. The model was developed based on the commonly accepted Gaussian dispersion formulae for the estimation of pollutant concentrations but has been adapted to incorporate a gradient-transfer deposition algorithm to account for the settling of dust particles, and to include a wind dependent factor on dust emission rates. The model is designed for fugitive dust impact prediction for point, line, area and volume sources.

4.4.17      The following meteorological data of year 2000 relevant to the study area have been obtained from Hong Kong Observatory and used in the modelling of the dust emission dispersion:

·        Hourly wind direction and speed, air temperature together with atmospheric Pasquill stability class at Lau Fau Shan automatic weather station;

·        Daily morning and maximum mixing heights based on the radiosonde ascent at King’s Park; and

·        Hourly total sky cover, cloud amount and cloud based height of the 1st - 4th layers observed at the Hong Kong Observatory Headquarters in Chek Lap Kok.

4.4.18      Based on particle size multiplier for the unpaved road emission and the handling of excavated and construction materials documented in the Compilation of Air Pollutant Emission Factors (AP-42) 5th Edition published by USEPA, it was assumed that 80% of particulates have size equal to 30µm, with the remaining 20% assumed to be respirable with a size of 10µm.  An average dust density of 2500 kg/m3 was also assumed in the study.

4.4.19      The worst-case situations were studied.  Given the stringent noise limits that need to be satisfied for construction works within the restricted hours (1900 – 0700 the next day, Sunday and public holidays), it was assumed that the working hours for construction activities is restricted to 0700 to 1900 hours only.

4.4.20      The alignment of haul roads, locations of representative emission points of Stage A and Stage B are presented in Figure 4‑2 and Figure 4‑3 respectively.

4.4.21      Maximum 1-hour average and 24-hour average TSP concentrations were predicted at the representative ASRs and superimposed with the background TSP level of 100mg/m3 to compare with the 1-hour and daily TSP limits of 500mg/m3 and 260mg/m3 respectively to assess the acceptability.

4.4.22      Details of calculation of particulate emission rates are presented in Appendix 4-1.

Modelled Results

4.4.23      The predicted highest 1-hour average and daily average TSP concentrations at the representative ASRs at various heights are shown in Table 44. Appendix 4-2 presents a typical FDM result file for reference. The TSP levels that exceed the relevant TSP criteria are shown in bold.

4.4.24      The modelling results show that under the hypothetical worst case situations when all major dust generating operation are assumed to be in concurrent operation and under worst case meteorological conditions, the unmitigated cumulative dust levels including all the dust sources plus the background dust level will exceed the TSP criteria at some ASRs.

 

Table 44         Predicted Unmitigated TSP Level at selected ASRs

Representative ASRs

Predicted levels, µg/m3

(Stage A - unmitigated)

Predicted levels, µg/m3

(Stage B – unmitigated)

Location

ASR

mPD

1-hour TSP

24-hour TSP

1-hour TSP

24-hour TSP

Village House

(Man Wa Garden)

A1

6.3

662

250

649

315

 

9.3

483

199

561

274

 

12.3

368

163

460

230

Village House

A2

12.2

356

156

309

186

 

15.2

298

146

262

169

 

18.2

262

139

219

154

Village House

A3

10.0

724

194

303

173

 

13.0

643

181

259

163

 

16.0

556

168

233

153

Village House

A4

9.6

364

169

430

155

 

12.6

331

158

356

146

 

15.6

278

141

284

136

Village House

(Tin Hau Temple)

A5

8.9

312

146

437

140

Village House

(Ng Uk Tsuen)

A6

11.4

237

133

206

120

Village House

A7

5.6

242

127

191

116

Village House

A8

5.6

311

146

235

127

Village House

A9

5.3

630

305

165

123

Village House

A10

5.3

234

161

168

128

Village House

A11

5.6

192

118

156

110

Village House

A12

5.6

174

119

123

108

Village House

A13

5.6

144

112

131

107

Village House

A14

5.6

162

115

122

105

Village House

A15

5.6

180

121

151

112

Note:

1.          A background TSP level of 100 mg/m3 has been included in the results.

2.          Figures in Bold represent dust level that can exceed the relevant standards.

Control/ Mitigation Measures for Fugitive Dust Emission

4.4.25      In view of the exceedance in dust level predicted in the previous section, sufficient dust mitigation measures have to be implemented following the control requirements set out in the Air Pollution Control (Construction Dust) Regulation to ensure full protection of the nearby ASRs.  The following measures are specifically recommended for implementation together with those presented in the Regulation:

General Site Management

4.4.26      Appropriate working methods should be devised and arranged to minimise dust emissions and to ensure that any installed air pollution control system and measures are operated and/or implemented in accordance with their design merits. In the event of malfunctioning of any control system or equipment, the relevant dusty activities shall stop until the relevant control system or equipment are restored to proper functioning.

4.4.27      Watering should be applied on dusty areas and all dust emission sources twice daily. The frequency of spraying required should be adjusted depending upon local meteorological conditions such as rainfall, temperature, wind speed and humidity. The amount of mist spraying should be just enough to dampen the material without over-watering, which could result in unnecessary surface water runoff.

Vehicles and Site Haul Road

4.4.28      Dust emission from unpaved roads comes predominantly from travelling of vehicles. Areas within the site where there are regular vehicle movements should have an approved hard surface. Speed controls at an upper limit of 10 kph will be imposed and their movements should be confined to designed roadways within the site. All dusty vehicle loads should have side and tail boards and should be covered by tarpaulin extending at least 300 mm over the edges of the side and tail boards.  Wheel-wash troughs and hoses should be provided at exit points of the site.

4.4.29      The access road and the main haul road (i.e. Haul Road A in Figure 4‑2 and Figure 4‑3) at the entrance of the subject site have already been paved currently.

Material Stockpiling and Handling

4.4.30      Fill materials required for site formation works will be delivered regularly by dump trucks to the site and for use in filling the ponds. Aiming to minimize the amount of stockpiling as far as practicable, the trucks should maximize the opportunity to directly unload the fill materials into the drained pond. The surface of the ponds under filling and stockpile, if any, should be kept wet by spraying with water. Compaction of fill material at the ponds could further reduce dust generation. Dust emission during loading of fill material to dump trucks, or from dump trucks to the drained ponds should be mitigated by spraying to sufficiently damp the materials prior to any loading or unloading operations.

4.4.31      Dusty construction debris should be covered where practicable to avoid dust generation.  Watering is an effective dust control measure commonly employed in storage piles and handling operations and should be implemented where appropriate.

Phasing of Construction Activities

4.4.32      The phasing of dusty construction activities can effectively control the dust generation during the construction period. The pond filling activities during site formation for the residential portion of the Project and establishment of WNR will be conducted in a “portion-by-portion” approach to mitigate dust generation.

4.4.33      With the implementation of the above-recommended dust mitigation measures together with those required in the Air Pollution Control (Construction Dust) Regulation, a conservative dust control efficiency of 75% is considered achievable. (e.g. through regular and frequent water spraying, say every 2 hours during very dry days or worst dust situation). Table 4‑5 presents the mitigated dust levels (75% control efficiency) estimated at the ASRs with the implementation of sufficient dust emission measures, as recommended above. The fugitive dust impacts have been predicted to fully satisfy the relevant criteria when the dust control measures are implemented.

4.4.34      Figure 4‑4 and Figure 4‑5 present the worst-case maximum 1-hour at 10.0 mPD and 24-hour TSP levels at 5.3 mPD in the vicinity of the site predicted by the air quality model under Stage A.  For Stage B, the worst-case maximum 1-hour and 24-hour TSP concentrations are presented in Figure 4‑6 and Figure 4‑7 accordingly. The background TSP concentration has been incorporated into the contours. The contours in Figure 4-4 to Figure 4-7 show the exceedances of hourly and daily average TSP in some areas within the Subject Site, however, no air sensitive uses were identified within those areas.

 

Table 45         Predicted mitigated TSP Level at selected ASRs

Representative ASRs

Predicted levels, µg/m3

(Stage A - mitigated)

Predicted levels, µg/m3

(Stage B – mitigated)

Location

ASR

mPD

1-hour TSP

24-hour TSP

1-hour TSP

24-hour TSP

Village House

(Man Wa Garden)

A1

6.3

241

138

237

154

 

9.3

196

125

215

144

 

12.3

167

116

190

133

Village House

A2

12.2

164

114

152

121

 

15.2

150

112

141

117

 

18.2

140

110

130

113

Village House

A3

10.0

256

124

151

118

 

13.0

236

120

140

116

 

16.0

214

117

133

113

Village House

 

A4

9.6

166

117

183

114

 

12.6

158

114

164

111

 

15.6

145

110

146

109

Village House

(Tin Hau Temple)

A5

8.9

153

112

184

110

Village House

(Ng Uk Tsuen)

A6

11.4

134

108

127

105

Village House

A7

5.6

136

107

123

104

Village House

A8

5.6

153

112

134

107

Village House

A9

5.3

233

152

116

106

Village House

A10

5.3

134

115

117

107

Village House

A11

5.6

123

105

114

102

Village House

A12

5.6

118

105

106

102

Village House

A13

5.6

111

103

108

102

Village House

A14

5.6

116

104

106

101

Village House

A15

5.6

120

105

113

103

 

Note:  A background TSP level of 100 mg/m3 has been included in the results.

Potential Odour Nuisance during Construction Phase

4.4.35      Pond sediment which is usually rich in organic material could pose certain odour nuisance to the surrounding when they are exposed and in vast amount. Since any exposed surface and stockpiled material will be covered by impervious sheet or immediately filled by filling materials during the construction phase, the potential odour nuisance pose by the exposed pond sediment during dredging and pond filling is considered to be minimal.

4.4.36      The potential odour nuisance is considered to be in minor extent or at least similar to the normal pond draining and dredging activities commonly performed in the existing site as convential practices of fish farming.

Environmental Monitoring and Audit

4.4.37      Based on the findings of the foregoing study, it is recommended that an Environmental Monitoring and Audit (EM&A) Programme be implemented during the construction phase of the Project to ensure implementation of the recommended dust mitigation measures. This will enable the contractor to identify the potential dust emission problems, and to react timely with remedial measures when dust criteria are about to be exceeded (e.g. more frequent watering of site haul roads).  Details of the recommended EM&A on air quality issues are presented in the EM&A Manual.

Concurrent Construction Activities

4.4.38      The approved EIA of “Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2” (EIA-094/2004) justified that no cumulative impact with the Fung Lok Wai Project would be anticipated. However, the proposed sewerage project is now classified as a Category B project under the Public Works Programme. It is our understanding that Drainage Services Department (DSD) is preparing to conduct the feasibility study.  The final alignment and construction schedule of the sewerage works as discussed in the approved EIA report is not confirmed.  After carrying out and confirmation of the feasibility study, DSD will initiate the detail design process and get funding approval from the Legislative Council.  It is estimated that DSD will need years to complete the study, design and approval process. Therefore, no construction programme is available at the present stage for the proposed sewerage work.  On the other hand, construction work for the proposed residential development at the Subject Site is scheduled to complete by 2016. Since there is no anticipated overlapping of construction works between the two projects, hence cumulative dust impact assessment is considered not necessary. 

Impacts Summary

4.4.39      Construction activities have the potential to generate dust impacts on nearby Air Sensitive Receivers, if unmitigated. Mitigation measures in the form of various dust suppression techniques based on those specified in the Air Pollution Control (Construction Dust) Regulation are proposed.  These dust mitigation measures should be implemented to alleviate dust emission level arising from activities associated with the construction works to acceptable levels. The implementation of these mitigation measures should also be checked by an EM&A programme.

 

4.5              Operational Phase Impact

4.5.1          There are no air and odour emission sources within the Project, except potential odour nuisance from a proposed pump house. However, the pump house will have a setback distance of more than 150m from the residential block and any nearby ASRs, and with the implementation of proper enclosure and ventilation system to divert the odour emission to odour scrubbing device (e.g. enclosed concrete structure and activated carbon filter at the air vent of the pump house), no insurmountable odour impact is anticipated. Further discussions are presented in Section 8.8.2.

4.5.2          A minimum setback distance of 125m is provided between the closest existing local distributor Fuk Shun Street and the proposed development.  Referring to the Hong Kong Planning Standard and Guidelines (HKPSG), a buffer distance of not less than 5m shall be provided between a local distributor and an open space site for active and passive recreational uses.  In this regard, sufficient buffer distance will be provided and the buffer requirements as recommended in the HKPSG could be met. The operational air quality impact arising from the vehicular emission is considered insignificant.

4.5.3          Given the remoteness of the chimneys located in the YLIE and the YLSTW from the Development (about 400m and 500m away from the Subject Site respectively), the operational air quality impact arising from the chimney emissions from the YLIE and odour from the YLSTW are also considered insignificant.

 

4.6              Conclusion

4.6.1          Fugitive dust emissions due to site formation works for the access road, pond filling, spreading and compaction of fill materials at the residential portion of the Project have been predicted quantitatively. The hypothetical worst-case scenarios were assessed by assuming concurrent emissions from all identified major dust emission sources and under worst-case meteorological conditions.

4.6.2          The findings of the construction dust emission impact assessment indicate that without adequate mitigation, fugitive dust levels generated from site formation works could exceed the hourly TSP limit of 500mg/m3 and the 24-hour TSP limit of 260mg/m3 at some of the nearby air sensitive receivers (ASRs). The movement of trucks on haul roads was found to be the principal source of excessive dust generation.

4.6.3          Implementation of sufficient mitigation measures including those specified in the Air Pollution Control (Construction Dust) Regulation as well as those recommended in this EIA for the contractor through inclusion of relevant clauses into the Contract Specification are recommended and are considered effective in this assessment to reduce fugitive dust impact at the ASRs to within acceptable levels. An EM&A programme is also recommended for the Project to protect the nearby air sensitive uses further. During the operational phase of the development, air quality impact due to industrial emissions and vehicular emissions are considered minimal.


5.                   Noise impact assessment

5.1              Introduction

5.1.1          This section presents an assessment of the noise impact arising from the construction and operation of the Project in accordance with the requirements specified under Clause 3.5.2 of the EIA Study Brief. Key issues include construction noise impact arising from use of powered mechanical equipment (PME) during the construction phase, and impact due to fixed noise sources during the operational phase. This noise impact assessment has been carried out following the criteria and guidelines given in Annexes 5 and 13 of the EIAO TM.

5.1.2          Clause 3.5.2 (v) of the Study Brief requires that the construction noise arising from the Project be addressed.  Relevant assessments and recommended mitigation measures are presented in this section.  Potential impact from envisaged fixed noise source(s) as proposed at the Project inception stage has also been assessed

 

5.2              Background Information and Relevant Studies

5.2.1          An EIA of “Agreement No. CE 10/95 – Tin Shui Wai Development Engineering Investigations for Development of Areas 3, 30 & 31 of the Development Zone and the Reserve Zone” was completed in 1997 prior to the enactment of EIAO to study further developments at Tin Shui Wai area. The Tin Shui Wai Ecological Mitigation Area otherwise known as the International Wetland Park (it was eventually renamed as Hong Kong Wetland Park) was accepted as mitigation for a variety of environmental impacts of the development.

5.2.2          The Hong Kong Tourist Association and Agriculture, Fisheries and Conservation Department (AFCD) commissioned a “Hong Kong International Wetland Park and Visitor Centre Feasibility Study – Preliminary Environmental Review” in 1999 to further assess the potential environmental impact of the Hong Kong Wetland Park.

5.2.3          An EIA on the Designated Project - “Tin Shui Wai Phase 4 Rail Extension” was conducted by Kowloon-Canton Railway Corporation in 1999. The study has assessed the impacts of the Phase 4 Light Rail Extension. Its construction work is planned to start by early 2001 and last for approximately 3 years.

5.2.4          The “Review of Yuen Long and Kam Tin Sewerage and Sewage Treatment Requirements” was completed by Drainage Service Department. Being part of the “Yuen Long and Kam Tin Sewerage and Sewage Disposal” (YLKTSSD) scheme recommended by the “Review of Yuen Long and Kam Tin Sewerage and Sewage Treatment Requirements”, a Study Brief No. ESB-082/2001 was issued on 21 Sept 2001 for an EIA Study for the Designated Project “Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2”.

 

5.3              Possible Cumulative Impact

5.3.1          During the construction phase of the Project, two concurrent projects are identified within the assessment area, namely the Hong Kong Wetland Park (HKWP) Phase 2 and the Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2. The possible cumulative noise impacts are considered insignificant for the following reasons.

5.3.2          The construction of Hong Kong Wetland Park has been completed and is considered to have no cumulative impact on the construction work of the Project.

5.3.3          According to the EIA study of “Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2” (EIA-094/2004) approved on 17 June 2004, there are two schemes proposed – Conforming Scheme of 2A-1T and Alternative scheme of 2A-1. Two of the Designated Projects (DPs) identified in the project are Package 2A-1T and its alternative, which are the construction of the Yuen Long Sewerage Treatment Works (YLSTW) Effluent Pipeline. They will be close to the Project as they include the construction of pumping station to the north of YLSTW and twin rising mains. In particular the twin rising mains of Package 2A-1T will be laid from YLSTW to Tin Tsz Road in Tin Shui Wai via the southern boundary of the Project. EIA-094/2004 concluded that the Alternative scheme of 2A-1T which was further away from the Fung Lok Wai Project was the preferred option. Cumulative impact would not be anticipated as justified in the Sec 2.5 of the EIA-094/2004. Furthermore, the proposed sewerage project is now classified as a Category B project under the Public Works Programme. It is our understanding that Drainage Services Department (DSD) is preparing to conduct the feasibility study.  The final alignment and construction schedule of the sewerage works as discussed in the approved EIA report is not confirmed.  After carrying out and confirmation of the feasibility study, DSD will initiate the detail design process and get funding approval from the Legislative Council.  It is estimated that DSD will need years to complete the study, design and approval process. Therefore, no construction programme is available at the present stage for the proposed sewerage work.  On the other hand, construction work for the proposed residential development at the Subject Site is scheduled to complete by 2016. Since there is no anticipated overlapping of construction works between the two projects, hence cumulative noise impact assessment is considered not necessary.

 

5.4              Assessment Area

5.4.1          Figure 2‑4 in Section 2 presents the assessment area for noise impact assessment. As stated in the Study Brief, Clause 3.5.2.2 (i), the assessment area is defined by a region of 300m from the boundary of the Project, including the access road.

 

5.5              Noise Sensitive Receivers

5.5.1          Existing and planned NSRs situated within the assessment area were identified based on the definition given in Annex 13 of the EIAO TM and are described below. The locations of the representative assessment points (“RAPs”), i.e. CN1 to CN5 are shown in Figure 5‑1.

Existing Noise Sensitive Receivers

5.5.2          The Project is situated in a rural area. Within the assessment area, low-rise village huts can be found scattered around the site boundary, with most of them concentrated at the south. A Tin Hau Temple is also found at some 138m from the southeast boundary of the Project. These NSRs are identified to include the following: -

·        Village huts close to the southern boundary of the Project (Man Wa Garden);

·        Village huts close to the south-eastern boundary of the Project;

·        Village huts close to the eastern boundary of the Project;

·        Village huts close to the northern boundary of the Project;

·        Village hut at the western side of the Project;

·        Village huts located at the north-western boundary of the Project;

·        Tin Hau Temple;

·        Shing Uk Tsuen;

·        Tai Tseng Wai;

·        Ng Uk Tsuen;

·        Vienna Villa;

·        Jade Court;

·        Lai Yin Garden;

·        Leon Court; and

·        Other village houses adjacent to Fuk Shun Street

5.5.3          The locations of the above NSRs around the Site are illustrated in Figure 5-2.

Planned Noise Sensitive Receivers

5.5.4          Besides the Project, no planned noise sensitive receivers are identified within the 300m study area.

 

5.6              Construction Phase Impact

Introduction

5.6.1          This section presents an assessment of noise impact on surrounding Noise Sensitive Receivers (NSRs) during the construction phase of the Project. In accordance with the construction programme, the potential cumulative noise impacts of the construction of the access road, the residential portion and the WNR have been assessed.

5.6.2          The assessment of construction noise impact was in accordance with the methodology stipulated in Para. 5.3 and 5.4 of Annex 13 of the EIAO TM.  Noise generated from construction works other than percussive piling during the non-restricted hours (i.e. 7a.m. to 7 p.m. on weekdays other than general holidays) is the focus of the study in accordance with the requirement stated in Clause 3.5.2.2 (v) of the Study Brief. 

5.6.3          Representative worst case scenarios were identified based on the construction programme (see Figure 2‑7). 

Legislation and Assessment Criteria

5.6.4          Construction noise is controlled under the Noise Control Ordinance (NCO) which prohibits the use of powered mechanical equipment (PME) during the restricted hours (7 p.m. to 7 a.m. on normal weekdays and any time on a public holiday, including Sunday) without a valid Construction Noise Permit (CNP) granted by the Authority. The criteria and procedures for issuing such a permit are specified in the “Technical Memorandum on Noise From Construction Works Other than Percussive Piling” (TM1).

5.6.5          For construction works other than percussive piling, although TM1 do not provide control over daytime construction activities, noise limits are set out in Annex 5 of the EIAO-TM. The TM applies to designated projects, including residential or recreational development planned within Deep Bay Buffer Zone 1 or 2.  The noise standards are summarised in Table 5‑1.

 

Table 51         Noise Limits for Daytime Construction Activities

NSR

0700 to 1900 hours on any day not being a Sunday or general holiday Leq (30min.) dB (A)

All domestic premises including temporary housing accommodation

75

Educational institutions including kindergartens, nurseries.

70

65 (during examination)

N.B.     (i) The above standards apply to uses which reply on opened windows for ventilation.;

(ii) The above standards shall be viewed as the maximum permissible noise levels assessed at 1m from the external facade.

 

5.6.6          It is understood that whether the Noise Control Authority will issue a CNP would depend on the application submitted to the Authority according to the procedures laid down in TM1 issued under the NCO instead of the assessment presented in this EIA.  When assessing an application of a CNP, the Authority will compare the Corrected Noise Level (CNL) calculated based on the methodology presented in TM1 with the required Acceptable Noise Level (ANL), which depends on the noise sensitivity of the NSRs in question and is determined based on the criteria set out in TM1.

5.6.7          With effect from 1 November 1996, the use of specified powered mechanical equipment (SPME) for carrying out construction work other than percussive piling and/ or the carrying out of prescribed construction work (PCW) within a designated area are also brought under control. The relevant technical details are provided in the “Technical Memorandum on Noise from Construction Work in Designated Areas” (TM2). Based on the plan (no. EPD/NP/NT-04) issued by the Planning and Lands Bureau, The Project is just outside the boundary of the noise control designated areas under the Noise Control Ordinance.

5.6.8          Percussive piling is controlled similarly by a noise permit system and described in the NCO and the “Technical Memorandum On Noise From Percussive Piling” (TM3) which restrict the number of hours during which piling can be conducted.  No percussive piling may be carried out in the territory without a valid CNP issued by the Authority.  Besides, a CNP will only be granted for percussive piling, which is scheduled during normal working hours between 7 a.m. to 7 p.m. from Monday to Saturday.  The carrying out percussive piling is prohibited at any time on Sundays and public holidays as well as during the weekday from 7 p.m. to 7 a.m. the next day. 

5.6.9          Despite any description or assessment made in this EIA Report on construction noise aspects, there is no guarantee that a Construction Noise Permit (CNP) will be issued for the project construction. The Noise Control Authority will consider a well-justified CNP application, once filed, for construction works within restricted hours as guided by the relevant Technical Memorandum issued under the Noise Control Ordinance (NCO). The Noise Control Authority will take into account of contemporary conditions/situations of adjoining land uses and any previous complaints against construction activities at the site before making this decision in granting a CNP. Nothing in this EIA Report shall bind the Noise Control Authority is making his decision. If a CNP is to be issued, the Noise Control Authority shall include in it any     condition he thinks fit. Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution action under the NCO.

Assessment Methodology

5.6.10      The approach used in the assessment of noise from construction works other than percussive piling is based on standard acoustic principles, and the guidelines given Para. 5.3 and 5.4 of Annex 13 of the EIAO TM.  The methodology adopted is the same as that presented in TM1.

5.6.11      The construction area of the Project is divided into 3 portions as shown in Figure 53 to represent the construction area for access road, the residential portion and the wetland nature reserve.

5.6.12      Noise impact arising from the construction works have been predicted using the following typical procedures: -

·        Based on the tentative construction programme (see Figure 2‑7), the worst construction scenarios were identified;

·        Identify from TM1 the Sound Power Level (SWL) of each powered mechanical equipment (PME) preliminarily planned for used in the construction works;

·        Select representative NSRs for the construction noise impact assessment;

·        Identify the notional source position for each representative assessment point (RAP).  As it is an elongated site for the residential portion and an irregular one for the WNR, the dominant construction portion should be the fish pond nearest to the NSRs, the notional source position is considered to be at a position mid-way between the approximate geographical centre of that fish pond and its boundary nearest to the NSRs;

·        For the construction area of access road, the notional source position is defined as the shortest distance between the access road and the NSRs;

·        Calculate the Predicted Noise Level (PNL) based on distance attenuation from notional source positions to the representative NSRs;

·        With consideration of the effect of facade reflection at the NSRs, the Corrected Noise Level (CNL) at the NSRs was predicted; and

·        Based on a comparison of the CNL with the noise criteria presented in Table 5‑1, situations/ locations where the need for noise mitigation measures can be identified.

Key Construction Activities and Assessment Scenarios

5.6.13      As described in Section 2.2, the concerned main construction activities of the Project which will generate considerable noise impact involve the following:

 

Table 52         Key Construction Activities for Construction Noise Impact Assessment

Tasks

Descriptions

A

Establishment of Wetland Nature Reserve (WNR)

A1

Drain, remove bunds and install water controls at Sector 1

A2

Drain, remove bunds and install water controls at Sector 2

A3

Land formation and construction of water control structures of marshland

A4

Drain, remove bunds and install water controls at Sector 3

B

Construction works for development area

B1

Site Clearance

B2

Pond draining and dredging

B3

Pond filling

B4

Spreading and compaction of fill material at built area

B5a

Foundation works – Bored piling or H piling

B5b

Remaining Foundation works, including sheet piling and pile cap construction

B6

Superstructure and steel-bending at work area

B7

Construction of sewage pump house

B8

Laying of drainage, sewerage and utilities

B9

Paving of internal access road

C

Widening works of the access road leading to the Site

C1

Site Clearance and formation

C2

Laying of drainage, sewerage and utilities

C3

Formation of road sub-base, levelling and compaction

C4

Road paving and installation of road furniture

 

5.6.14      The contractor(s) will be required to carry out the construction works such that the associated noise impact is minimised as far as possible to comply with the Noise Control Ordinance (NCO) and the daytime noise limits recommended in the EIAO-TM.

5.6.15      Before the appointment of contractors, it would not be possible to define in full details of the type and frequency of utilization of different construction plants, a representative A Powered Mechanical Equipment (PME) inventory has been worked out and is considered practicable at this planning stage. 

5.6.16      While it is understood that the future appointed Contractor(s) may propose a different PME inventory, the carrying out of a representative quantitative assessment at this planning stage would enable an early focus on the potential noise problem, the practicality and sufficiency in the noise mitigation measures as proposed and planned at an early stage.

5.6.17      Appendix 5-1 presents the preliminary PME Inventory that is considered practicable in meeting the target construction programme and the Sound Power Levels for each of the PME. 

5.6.18      It should be noted that the percentage of time used for every PME is based on the actual situation of the construction activities.  A reasonable reduction in percentage on-time can reflect the actual situation which is used as a basic assumption for specific kind of PME. 

5.6.19      As mentioned in Section 5.6.8 above, percussive piling is controlled by a noise permit system under the NCO and the “Technical Memorandum on Noise from Percussive Piling” (TM3) which restrict the number of hours during which piling can be conducted. In order to minimize the noise impact of the construction activities, percussive piling will not be used in the foundation works.  The preliminary PM Inventory and the assessment with respect to the foundation works (Task B5a of Table 5‑2) are thus assumed employing bored piling only.

5.6.20      Based on the identified key construction activities in Table 5‑2 and the preliminary construction programme shown in Figure 2‑7, worst-case impact at each phase with different tasks of construction activities taking place concurrently were identified. These are presented in Table 5‑3 below.

 

Table 53         Representative Assessment Phases studied in the Construction Noise Impact Assessment

Construction Period

Possible Concurrent Tasks performed at site

(Task Ref. no. refers to Table 5‑2)

2010

3rd Q

-

 

4th Q

A1

2011

1st Q

A2

 

2nd Q

B1

 

3rd Q

B1

 

4th Q

B1+B2+A3+A4

2012

1st Q

B2+A3

 

2nd Q

B3+B4

 

3rd Q

B3+B4

 

4th Q

B3+B4

2013

1st Q

B4

 

2nd Q

-

 

3rd Q

B5a

 

4th Q

B5a

2014

1st Q

B5a

 

2nd Q

B5b

 

3rd Q

B6+B7+C1

 

4th Q

B6+B7+C1

2015

1st Q

B6+B8+C2

 

2nd Q

B6+B8+C2

 

3rd Q

B6+B9+C3

 

4th Q

B6+B9+C3

2016

1st Q

B6+C3

 

2nd Q

B6+C4

 

3rd Q

B6+C4

 

Emission Inventory of Noise Sources

5.6.21      Before appointment of the contractor, full details of the type and number of construction plant to be used for the construction works are not known. Nevertheless, based on typical construction activities, a preliminary PME inventory has been drawn up to allow a representative construction noise impact assessment be conducted. The PME list is realistic, practical and practicable, although it is formulated on a preliminary planning stage.  The equipment list is presented in Appendix 5-1. The assessment will give information on the individual and combined SWLs of the PME that could be “allowed” given the locations of the nearby Noise Sensitive Receivers (NSRs) such that the overall noise levels at the NSRs can be controlled within the daytime construction noise limits.  It is noted that there is no construction works to be carried out during the restricted hours (7 p.m. to 7 a.m. on normal weekdays and any time on a public holiday, including Sunday) unless a valid Construction Noise Permit (CNP) granted by the Authority.

5.6.22      An assessment of the worst case scenario of construction noise impact at this stage will enable the likely impacts, problem areas and necessary construction noise mitigation/ control measures be identified at an early stage for incorporation into the design of the construction works.  All SWL of the PME have been selected based on TM1.  These noise levels adopted in the study are considered representative of the plant under normal operating conditions.

5.6.23      In order to predict the worst-case situation, PME have been assumed to operate continuously (i.e. 100% on-time), except for dump trucks and lorries for which a 50% on-time has been adopted. This is considered realistic, given that the trucks/ lorries are not expected to be in operation full time on-site within any 30-minute period during the transport of fill/ excavated materials or other construction materials.

Representative Assessment Points (RAPs)

5.6.24      Existing and planned noise sensitive receivers within the assessment area that would be affected by construction noise impact have been identified in Section 5.5.2 and 5.5.4 above.  Representative Assessment Points (RAPs) were selected to represent these NSRs as illustrated in Figure 5‑1.  Based on the building height of the NSRs, noise levels were predicted at the lowest, medium and highest noise sensitive floors at each RAP.  RAPs were selected at locations closest to the construction site such that the assessment should be representative of the worst-case scenario. 

5.6.25      Table 1B of the EIAO TM only gives the noise standards for daytime construction activities at domestic premises (including temporary housing accommodation), hotels and hostels, and educational institutions. Locations of the RAPs (CN1 to CN5) are presented in Figure 5‑1. These RAPs are described below in Table 5‑4.

Table 54         RAPs Selected for Construction Noise Impact Assessment

RAP

Noise Sensitive Use

Building Type

Assessment Height (mPD)

CN 1

Village Huts near South-western boundary of the site (Man Wa Garden)

Low rise residential

6.0, 9.0, 12.0

CN 2

Village Huts close to Fuk Shun street (Leon Court)

Low rise residential

5.9, 8.9, 11.9

CN 3

Village Huts at South-eastern boundary of the site

Low rise residential

5.0

CN 4

Village Huts at North-western boundary of the site

Low rise residential

5.3

CN 5

Village Hut at northern boundary of the site

Low rise residential

5.3

 

Assessment Results (Unmitigated Scenario)

5.6.26      Table 55 to Table 59 present the unmitigated noise levels predicted at the RAPs for the identified worst-case representative assessment phases. Those predicted noise levels exceeding the noise criteria are highlighted in bold. Worksheet showing the calculation is provided in Appendix 5-2 for reference.

 

Table 55         Unmitigated Noise Levels Predicted At CN 1

 

 

 

Overall PNL , dB(A) at CN1

Period

 

Concurrent Tasks

G/F

1/F

2/F

2010

3rd Q

-

Not applicable

Not applicable

Not applicable

 

4th Q

A1

76

76

76

2011

1st Q

A2

76

76

76

 

2nd Q

B1

77

77

77

 

3rd Q

B1

77

77

77

 

4th Q

B1+B2+A3+A4

83

83

83

2012

1st Q

B2+A3

80

80

80

 

2nd Q

B3+B4

80

79

79

 

3rd Q

B3+B4

80

79

79

 

4th Q

B3+B4

80

79

79

2013

1st Q

B4

75

75

75

 

2nd Q

-

Not applicable

Not applicable

Not applicable

 

3rd Q

B5a

83

83

82

 

4th Q

B5a

83

83

82

2014

1st Q

B5a

83

83

82

 

2nd Q

B5b

82

82

82

 

3rd Q

B6+B7

81

81

81

 

4th Q

B6+B7+C1

87

87

87

2015

1st Q

B6+B8+C1

87

87

87

 

2nd Q

B6+B8+C2

87

87

87

 

3rd Q

B6+B9+C2

86

86

86

 

4th Q

B6+B9+C3

83

83

83

2016

1st Q

B6+C3

83

83

82

 

2nd Q

B6+C4

82

82

82

 

3rd Q

B6+C4

82

82

82

 

Table 56         Unmitigated Noise Levels Predicted At CN 2

 

 

 

Overall PNL , dB(A) at CN2

Period

 

Concurrent Tasks

G/F

1/F

2/F

2010

3rd Q

-

Not applicable

Not applicable

Not applicable

 

4th Q

A1

58

58

58

2011

1st Q

A2

58

58

58

 

2nd Q

B1

61

61

61

 

3rd Q

B1

61

61

61

 

4th Q

B1+B2+A3+A4

66

66

66

2012

1st Q

B2+A3

63

63

63

 

2nd Q

B3+B4

63

63

63

 

3rd Q

B3+B4

63

63

63

 

4th Q

B3+B4

63

63

63

2013

1st Q

B4

58

58

58

 

2nd Q

-

Not applicable

Not applicable

Not applicable

 

3rd Q

B5a

62

62

62

 

4th Q

B5a

62

62

62

2014

1st Q

B5a

62

62

62

 

2nd Q

B5b

62

62

62

 

3rd Q

B6+B7

62

62

62

 

4th Q

B6+B7+C1

88

87

87

2015

1st Q

B6+B8+C1

88

87

87

 

2nd Q

B6+B8+C2

87

87

87

 

3rd Q

B6+B9+C2

87

87

87

 

4th Q

B6+B9+C3

83

83

83

2016

1st Q

B6+C3

83

83

83

 

2nd Q

B6+C4

82

82

82

 

3rd Q

B6+C4

82

82

82

 

Table 57         Unmitigated Noise Levels Predicted At CN 3

Period

 

Concurrent Tasks

Overall PNL , dB(A) at CN3 – G/F

2010

3rd Q

-

Not applicable

 

4th Q

A1

76

2011

1st Q

A2

75

 

2nd Q

B1

70

 

3rd Q

B1

70

 

4th Q

B1+B2+A3+A4

80

2012

1st Q

B2+A3

78

 

2nd Q

B3+B4

72

 

3rd Q

B3+B4

72

 

4th Q

B3+B4

72

2013

1st Q

B4

67

 

2nd Q

-

Not applicable

 

3rd Q

B5a

72

 

4th Q

B5a

72

2014

1st Q

B5a

72

 

2nd Q

B5b

72

 

3rd Q

B6+B7

72

 

4th Q

B6+B7+C1

72

2015

1st Q

B6+B8+C1

72

 

2nd Q

B6+B8+C2

72

 

3rd Q

B6+B9+C2

70

 

4th Q

B6+B9+C3

70

2016

1st Q

B6+C3

68

 

2nd Q

B6+C4

68

 

3rd Q

B6+C4

68

 

Table 58         Unmitigated Noise Levels Predicted At CN 4

 

 

 

Overall PNL , dB(A) at CN4

Period

 

Concurrent Tasks

G/F

2010

3rd Q

-

Not applicable

 

4th Q

A1

78

2011

1st Q

A2

78

 

2nd Q

B1

63

 

3rd Q

B1

63

 

4th Q

B1+B2+A3+A4

82

2012

1st Q

B2+A3

81

 

2nd Q

B3+B4

66

 

3rd Q

B3+B4

66

 

4th Q

B3+B4

66

2013

1st Q

B4

61

 

2nd Q

-

Not applicable

 

3rd Q

B5a

65

 

4th Q

B5a

65

2014

1st Q

B5a

65

 

2nd Q

B5b

65

 

3rd Q

B6+B7

65

 

4th Q

B6+B7+C1

66

2015

1st Q

B6+B8+C1

66

 

2nd Q

B6+B8+C2

66

 

3rd Q

B6+B9+C2

65

 

4th Q

B6+B9+C3

64

2016

1st Q

B6+C3

62

 

2nd Q

B6+C4

62

 

3rd Q

B6+C4

62

 

Table 59         Unmitigated Noise Levels Predicted At CN 5

 

 

 

Overall PNL , dB(A) at CN5

Period

 

Concurrent Tasks

G/F

2010

3rd Q

-

Not applicable

 

4th Q

A1

79

2011

1st Q

A2

79

 

2nd Q

B1

57

 

3rd Q

B1

57

 

4th Q

B1+B2+A3+A4

83

2012

1st Q

B2+A3

81

 

2nd Q

B3+B4

59

 

3rd Q

B3+B4

59

 

4th Q

B3+B4

59

2013

1st Q

B4

54

 

2nd Q

-

Not applicable

 

3rd Q

B5a

58

 

4th Q

B5a

58

2014

1st Q

B5a

58

 

2nd Q

B5b

58

 

3rd Q

B6+B7

58

 

4th Q

B6+B7+C1

60

2015

1st Q

B6+B8+C1

60

 

2nd Q

B6+B8+C2

59

 

3rd Q

B6+B9+C2

58

 

4th Q

B6+B9+C3

57

2016

1st Q

B6+C3

56

 

2nd Q

B6+C4

56

 

3rd Q

B6+C4

56

 

5.6.27      Noise levels predicted at all RAPs would exceed the Leq(30min) 75dB(A) by 1-13dB(A). Construction noise mitigation measures are therefore necessary to protect the NSRs represented by all RAPs.

5.6.28      It should be noted that the assessment results only represent the worst-case construction scenarios i.e. when equipment adopted for different construction activities are in concurrent and continuous operation, and located at the same notional source position nearest to each RAP in question. In reality, the occurrence of these scenarios would be rare. Nevertheless, the assessment results revealed that particular attention should be paid to implement sufficient control/ mitigation measures to alleviate the noise impact during the construction, especially near the RAPs which are in close proximity to the construction site of the Project. The construction site of the Project includes the construction area of the residential footprint, wetland nature reserve and the access road to the site.

Recommended Construction Noise Mitigation Measures

5.6.29      Noise emissions from construction sites can be minimised by adopting a combination of practicable noise mitigation options, such as:

·        Use of quiet equipment;

·        Erecting temporary noise barriers and Provision of Noise Enclosure;

·        Phasing of the Construction Activities;

·        Reduce the number of equipment;

·        Good site practice and noise management; and

·        Use of silenced PME.

Selecting Quiet PME

5.6.30      Silenced types of equipment for use in construction activities are available in Hong Kong.  For each item of PME listed in Appendix 5-1, the SWL of quieter plant were identified from TM1 or BS 5228 Noise and vibration control on construction and open sites: Part I: 1997 for the purpose of the assessment. The SWL of the silenced PME are presented in Appendix 5-3. It is recommended that the contractor should diligently seek equivalent models of silenced PME with a SWL similar to or less than that presented in that table.

5.6.31      Table 510 to Table 514 present the mitigated noise levels predicted at CN1 to CN5 when silenced PME with the reduced SWL presented in Appendix 5-3 are in employed. Worksheets showing calculation of noise levels are provided in Appendix 5-4 for reference.

5.6.32      It can be observed that by adopting the silenced type of PME, the noise levels at the RAPs will be substantially reduced.  Despite this, the noise criteria will still be exceeded at CN1 and CN2 by a maximum noise level of 1-6 dB(A). 

 

Table 510       Mitigated Noise Levels at CN1 with Silenced PME

 

 

 

Overall PNL , dB(A) at CN1

Period

 

Concurrent Tasks

G/F

1/F

2/F

2010

3rd Q

-

Not applicable

Not applicable

Not applicable

 

4th Q

A1

67

67

67

2011

1st Q

A2

67

67

67

 

2nd Q

B1

66

66

66

 

3rd Q

B1

66

66

66

 

4th Q

B1+B2+A3+A4

73

73

73

2012

1st Q

B2+A3

71

71

71

 

2nd Q

B3+B4

71

71

71

 

3rd Q

B3+B4

71

71

71

 

4th Q

B3+B4

71

71

71

2013

1st Q

B4

69

69

69

 

2nd Q

-

Not applicable

Not applicable

Not applicable

 

3rd Q

B5a

81

81

81

 

4th Q

B5a

81

81

81

2014

1st Q

B5a

81

81

81

 

2nd Q

B5b

76

76

76

 

3rd Q

B6+B7

71

71

71

 

4th Q

B6+B7+C1

77

77

76

2015

1st Q

B6+B8+C1

78

78

77

 

2nd Q

B6+B8+C2

78

78

78

 

3rd Q

B6+B9+C2

77

77

77

 

4th Q

B6+B9+C3

79

79

79

2016

1st Q

B6+C3

79

79

78

 

2nd Q

B6+C4

74

74

74

 

3rd Q

B6+C4

74

74

74

 

 

Table 511       Mitigated Noise Levels at CN2 with Silenced PME

 

 

 

Overall PNL , dB(A) at CN2

Period

 

Concurrent Tasks

G/F

1/F

2/F

2010

3rd Q

-

Not applicable

Not applicable

Not applicable

 

4th Q

A1

49

49

49

2011

1st Q

A2

49

49

49

 

2nd Q

B1

49

49

49

 

3rd Q

B1

49

49

49

 

4th Q

B1+B2+A3+A4

56

56

56

2012

1st Q

B2+A3

53

53

53

 

2nd Q

B3+B4

54

54

54

 

3rd Q

B3+B4

54

54

54

 

4th Q

B3+B4

54

54

54

2013

1st Q

B4

53

53

53

 

2nd Q

-

Not applicable

Not applicable

Not applicable

 

3rd Q

B5a

61

61

61

 

4th Q

B5a

61

61

61

2014

1st Q

B5a

61

61

61

 

2nd Q

B5b

56

56

56

 

3rd Q

B6+B7

53

53

53

 

4th Q

B6+B7+C1

77

77

76

2015

1st Q

B6+B8+C1

77

77

76

 

2nd Q

B6+B8+C2

78

77

77

 

3rd Q

B6+B9+C2

78

77

77

 

4th Q

B6+B9+C3

79

79

79

2016

1st Q

B6+C3

79

79

79

 

2nd Q

B6+C4

74

74

73

 

3rd Q

B6+C4

74

74

73

 

Table 512       Mitigated Noise Levels at CN3 with Silenced PME

 

 

 

Overall PNL , dB(A) at CN3

Period

 

Concurrent Tasks

G/F

2010

3rd Q

-

Not applicable

 

4th Q

A1

66

2011

1st Q

A2

66

 

2nd Q

B1

58

 

3rd Q

B1

58

 

4th Q

B1+B2+A3+A4

71

2012

1st Q

B2+A3

69

 

2nd Q

B3+B4

63

 

3rd Q

B3+B4

63

 

4th Q

B3+B4

63

2013

1st Q

B4

62

 

2nd Q

-

Not applicable

 

3rd Q

B5a

71

 

4th Q

B5a

71

2014

1st Q

B5a

71

 

2nd Q

B5b

66

 

3rd Q

B6+B7

62

 

4th Q

B6+B7+C1

63

2015

1st Q

B6+B8+C1

65

 

2nd Q

B6+B8+C2

65

 

3rd Q

B6+B9+C2

63

 

4th Q

B6+B9+C3

63

2016

1st Q

B6+C3

62

 

2nd Q

B6+C4

62

 

3rd Q

B6+C4

62

 

Table 513       Mitigated Noise Levels at CN4 with Silenced PME

 

 

 

Overall PNL , dB(A) at CN4

Period

 

Concurrent Tasks

G/F

2010

3rd Q

-

Not applicable

 

4th Q

A1

69

2011

1st Q

A2

69

 

2nd Q

B1

52

 

3rd Q

B1

52

 

4th Q

B1+B2+A3+A4

73

2012

1st Q

B2+A3

71

 

2nd Q

B3+B4

57

 

3rd Q

B3+B4

57

 

4th Q

B3+B4

57

2013

1st Q

B4

55

 

2nd Q

-

Not applicable

 

3rd Q

B5a

63

 

4th Q

B5a

63

2014

1st Q

B5a

63

 

2nd Q

B5b

58

 

3rd Q

B6+B7

56

 

4th Q

B6+B7+C1

57

2015

1st Q

B6+B8+C1

58

 

2nd Q

B6+B8+C2

59

 

3rd Q

B6+B9+C2

57

 

4th Q

B6+B9+C3

58

2016

1st Q

B6+C3

57

 

2nd Q

B6+C4

56

 

3rd Q

B6+C4

56

 

Table 514       Mitigated Noise Levels at CN5 with Silenced PME

 

 

 

Overall PNL , dB(A) at CN5

Period

 

Concurrent Tasks

G/F

2010

3rd Q

-

Not applicable

 

4th Q

A1

69

2011

1st Q

A2

69

 

2nd Q

B1

45

 

3rd Q

B1

45

 

4th Q

B1+B2+A3+A4

74

2012

1st Q

B2+A3

72

 

2nd Q

B3+B4

50

 

3rd Q

B3+B4

50

 

4th Q

B3+B4

50

2013

1st Q

B4

49

 

2nd Q

-

Not applicable

 

3rd Q

B5a

57

 

4th Q

B5a

57

2014

1st Q

B5a

57

 

2nd Q

B5b

52

 

3rd Q

B6+B7

49

 

4th Q

B6+B7+C1

50

2015

1st Q

B6+B8+C1

52

 

2nd Q

B6+B8+C2

52

 

3rd Q

B6+B9+C2

51

 

4th Q

B6+B9+C3

51

2016

1st Q

B6+C3

51

 

2nd Q

B6+C4

49

 

3rd Q

B6+C4

49

 

Use of Temporary Noise Barriers and Machinery Enclosures

5.6.33      The erection of temporary mobile noise barriers between noise sources and NSRs will be effective in reducing the potential construction noise impact, especially for the low-rise village huts which are the target NSRs to be protected.

5.6.34      The minimum effective height of the mobile noise barriers should be such that no part of the noise sources should be visible from the target NSRs to be protected. The guidelines given in the Booklet entitled “A Practical Guide for the Reduction of Noise from Construction Works” issued by EPD is recommended to be referenced to in the design of the temporary acoustic barriers. Barriers should have no openings or gaps, and preferably have a superficial surface density of at least 10 kg/m2.  Where required, temporary barriers of sufficient height with skid footing and a cantilevered upper portion can be erected within a few meters from stationary plants, and at practicable distance from mobile plants operating over a small area or using a well defined route, to alleviate potential construction noise impact.

5.6.35      Particular attention should be drawn to bored piling works at the residential area where they are considered the major construction noise sources. Noise barriers are recommended to be erected close to the stationary point of piling works during piling to alleviate the potential noise impact to the adjacent village huts.

5.6.36      To the NSRs along Fuk Shun Street which are represented by CN2, the widening works of access road is considered the major noise nuisance during the construction phase. Considering the close proximity of the village huts (CN2) to the construction site of access road, setting up of a noise barrier with approximate 3m height between the noise source and those village huts along Fuk Shun Street is considered necessary during the construction works of access road. Given the low-rise nature of those village huts (1 to 3 storeys only), most noise sources should be completely shielded from the target NSRs after the erection of these noise barriers. The barrier effect is anticipated to provide a noise reduction effect of at least 10dB(A).

5.6.37      In addition to temporary mobile noise barriers, certain types of PME such as generators and compressors can be totally shielded by machine enclosures, giving a noise reduction of 10dB(A) or more.

5.6.38      It is expected that the proper use of barriers/ enclosures for PME can achieve a noise reduction of 10dB(A) when the noise barriers completely hides the sources from the receiver in accordance with BS 5228.  To be conservative, a –5dB(A) reduction has been applied for mobile noise sources. With the erection of proper designed noise barriers, a 10dB(A) noise reduction has been applied in the calculation of the construction noise attributed to excavation and piling works. For generators and compressors which can be effectively enclosed to minimize noise generation, a –10dB(A) noise reduction has also been applied in the calculation.  Appendix 5-5 presents the reduced SWL of the PME when the noise reduction effect of noise barriers and machinery enclosures are applied. 

5.6.39      Table 5‑15 to Table 516 present the further mitigated noise levels predicted at CN1 and CN2 when temporary noise barriers and machinery enclosures are also used on-site in addition to silenced PMEs.  Noise levels at CN3, CN4 and CN5 are not further assessed, as the predicted construction noise levels with silenced PMEs in place would meet the noise criteria. Worksheet showing the calculation at CN1 and CN2 of the worst scenario is provided in Appendix 5-6 for reference.

5.6.40      The results of the calculation as presented show that with the combined use of silenced PME, noise barriers and machinery enclosures, the construction noise levels at all RAPs can be mitigated to acceptable levels.

 

Table 515       Mitigated Noise Levels at CN1 with Silenced PME + Temporary Noise Barriers + Machinery Enclosure

 

 

 

Overall PNL , dB(A) at CN1

Period

 

Concurrent Tasks

G/F

1/F

2/F

2010

3rd Q

-

Not applicable

Not applicable

Not applicable

 

4th Q

A1

63

63

63

2011

1st Q

A2

63

63

63

 

2nd Q

B1

63

63

63

 

3rd Q

B1

63

63

63

 

4th Q

B1+B2+A3+A4

69

69

69

2012

1st Q

B2+A3

67

67

67

 

2nd Q

B3+B4

67

67

67

 

3rd Q

B3+B4

67

67

67

 

4th Q

B3+B4

67

67

67

2013

1st Q

B4

64

64

64

 

2nd Q

-

Not applicable

Not applicable

Not applicable

 

3rd Q

B5a

71

71

71

 

4th Q

B5a

71

71

71

2014

1st Q

B5a

71

71

71

 

2nd Q

B5b

71

71

71

 

3rd Q

B6+B7

64

64

64

 

4th Q

B6+B7+C1

72

72

72

2015

1st Q

B6+B8+C1

73

73

73

 

2nd Q

B6+B8+C2

74

74

73

 

3rd Q

B6+B9+C2

73

73

73

 

4th Q

B6+B9+C3

74

74

74

2016

1st Q

B6+C3

74

73

73

 

2nd Q

B6+C4

70

70

70

 

3rd Q

B6+C4

70

70

70

 

 

Table 516       Mitigated Noise Levels at CN2 with Silenced PME + Temporary Noise Barriers + Machinery Enclosure

 

 

 

Overall PNL , dB(A) at CN2

Period

 

Concurrent Tasks

G/F

1/F

2/F

2010

3rd Q

-

Not applicable

Not applicable

Not applicable

 

4th Q

A1

45

45

45

2011

1st Q

A2

45

45

45

 

2nd Q

B1

46

46

46

 

3rd Q

B1

46

46

46

 

4th Q

B1+B2+A3+A4

52

52

52

2012

1st Q

B2+A3

49

49

49

 

2nd Q

B3+B4

50

50

50

 

3rd Q

B3+B4

50

50

50

 

4th Q

B3+B4

50

50

50

2013

1st Q

B4

48

48

48

 

2nd Q

-

Not applicable

Not applicable

Not applicable

 

3rd Q

B5a

51

51

51

 

4th Q

B5a

51

51

51

2014

1st Q

B5a

51

51

51

 

2nd Q

B5b

51

51

51

 

3rd Q

B6+B7

46

46

46

 

4th Q

B6+B7+C1

73

73

73

2015

1st Q

B6+B8+C1

73

73

73

 

2nd Q

B6+B8+C2

74

74

73

 

3rd Q

B6+B9+C2

74

74

73

 

4th Q

B6+B9+C3

74

74

74

2016

1st Q

B6+C3

74

74

74

 

2nd Q

B6+C4

70

70

70

 

3rd Q

B6+C4

70

70

70

 

Other Noise Mitigation Measures Recommended

5.6.41      The assessment results presented above demonstrate with the use of silenced PME, temporary noise barriers and machinery enclosure, noise levels at the NSRs will be mitigated to acceptable levels.  To be prudent in noise control, additional measures are recommended below.

Phasing of Construction Activities

5.6.42      The noise levels predicted at the NSRs presented in Table 55 to Table 516 are based on concurrent operation of all equipment at all time within a 30-minute period.  In real life situations, it is expected that under the construction programme, different construction activities could be arranged in sequences such that different PMEs do not necessary have to be in operation concurrently. Cumulative noise impact arising from the construction site can therefore be minimizedGood Housekeeping

5.6.43      Significant noise impact during the construction phase can be avoided when noise management is regarded one of the key components of the construction works.  The following good site practices are recommended for incorporation into contract document.

·        Contractor shall comply with and observe the Noise Control Ordinance (NCO) and its current subsidiary regulations;

·        Before the commencement of any work, the Contractor shall submit to the Engineer for approval the method of working, equipment and sound-reducing measures intended to be used at the site;

·        Contractor shall devise and execute working methods that will minimise the noise impact on the surrounding environment; and shall provide experienced personnel with suitable training to ensure that these methods are implemented;

·        Only well-maintained plants should be operated on-site;

·        Plants should be serviced regularly during the construction programme;

·        Machines that may be in intermittent use should be shut down or throttled down to a minimum between work periods;

·        Silencer and mufflers on construction equipment should be utilised and should be properly maintained during the construction programme;

·        Noisy activities can be scheduled to minimise exposure of nearby NSRs to high levels of construction noise.  For example, noisy activities can be scheduled for midday or at times coinciding with periods of high background noise (such as during peak traffic hours);

·        Noisy equipment such as emergency generators shall always be sited as far away as possible from noise sensitive receivers;

·        Mobile plants should be sited as far away from NSRs as possible; and

·        Material stockpiles and other structures should be effectively utilised as noise barrier, where practicable.

Reduce No. of PME operating together in Areas close to the Boundary of the Site

5.6.44      Construction noise can be reduced by increasing the distance between the operating equipment and the NSRs or by reducing the number of equipment items in use simultaneously.  By controlling the number of equipment (particularly those relatively noisy one) working near the existing NSRs or the boundary of the site, potential construction noise impact can be further reduced.

EM&A Requirements

5.6.45      In order to protect the nearby NSRs from unacceptable construction noise impact, an environmental monitoring and audit (EM&A) programme should be implemented to check the proper use of noise mitigation measures and noise management. Details on the noise monitoring requirements, methodology and action plans are described in details in the EM&A Manual

Conclusion

5.6.46      The construction noise impact assessment revealed that unmitigated noise levels predicted at some existing dwellings located close to the Project site would exceed the EIAO-TM requirements, if not mitigated properly. 

5.6.47      Mitigation measures in form of use of silenced equipment, noise barriers, and machinery enclosure, phasing of construction activities, good housekeeping practices, and reduced numbers of equipment operating together close to the NSRs and the boundary of the site have been recommended as effective measures to reduce the construction noise impact.

 

5.7              Operational Phase Impact

Introduction

5.7.1          This section presents an assessment of the noise impact during the operational phase of the Project in accordance with Clause 3.5.2.2 (vi) of the Study Brief. Issue of concern will be the fixed noise impact that could be associated with major on-site installations, which may affect the future residential development – the nearest noise sensitive uses to the sources envisaged.

Fixed Noise Sources

Legislation and Assessment Criteria

5.7.2          Noise standards required to be met at NSRs for noise generated from fixed noise sources are stated in the Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites (TM4).  In order to plan for a better environment, in accordance with the requirements under Table 1 in Annex 5 of the EIAO-TM, the maximum noise level arising from the noise sources, measured in terms of Leq(30 min) at the NSRs shall be 5 dB(A) below the Acceptable Noise Level (ANL) as specified in TM4.

5.7.3          In determining the ANL, appropriate Area Sensitivity Rating (ASR) for a NSR have to be established first. Section 2.3.4 of the TM specifies that the Area Sensitivity Rating depends upon the characteristics of the area in which the NSRs are located.  There are four types of areas described in the TM, which are summarised in Table 5-17 below. According to the rural nature of the subject site not affected by any Influencing Factor (IF), an ASR “A” was assumed for residential blocks within the Project and also the village huts at the surrounding.

5.7.4          For ASR “A”, the ANL for the daytime/ evening (0700-2300) and night-time (2300-0700 next day) periods measured at 1m in front of the building facade of the NSR shall be Leq(30min.) 60 dB(A) and 50 dB(A), respectively.  Taking into account the EIAO-TM requirements, a “5dB(A) margin has been applied to the noise limits stipulated in the TM. The noise assessment criteria adopted in this study are therefore Leq(30min.) 55 dB(A) and 45 dB(A) during the daytime/ evening and night time periods, respectively. 

 

Table 517       Area Sensitivity Ratings of NSRs

Type of Area Containing NSR

Degree to which NSR is affected by Influencing Factors (Ifs)

 

Not Affected

Indirectly Affected

Directly Affected

(i)       Rural area, including country parks, or village type developments

A

B

B

(ii)     Low density residential area consisting of low-rise or isolated high-rise developments

A

B

C

(iii)    Urban area

B

C

C

(iv)   Area other than those above

B

B

C

 

Assessment Approach

5.7.5          The assessment on fixed plant noise impact was conducted based standard acoustics principles presented in TM4 and are summarized below:

·        Based on the preliminary design layout plans and equipment inventory required to be provided at the new facility, identify the key noise sources of potential concern;

·        Estimate the sound power levels (SWL) associated with operation of each of these activities based on available measurement results or typical SWL figures;

·        Calculate the Corrected Noise Level (CNL) at selected representative NSRs based on consideration of distance attenuation, noise shielding effect, and façade correction;

·        Compare the CNL with the relevant noise criteria and recommend noise mitigation measures if necessary.

Noise Impact Evaluation

5.7.6          No electricity sub-station is likely to be built in the subject site. Only small-scale transformer room(s) may be found at the proposed development. Although the information such as design, specification and location of the transformer room(s) was not yet available, since the transformer room is likely to be enclosed inside concrete structure, its noise impact is considered minimal.

5.7.7          A review of the design for the Project suggests that the planned sewage pump house within the residential portion of the Project will be the only major noise source during the operational phase. Other activities, e.g. the management and operation of the WNR should not be causing unacceptable noise impact on the surroundings. The pump for the recirculation of water to the ponds at the WNR is just for emergency use. Alhough the detail design of the pump was no yet confirmed. Considering its small in scale needed, and its very limited usage of time and duration, the operational noise impact from the pump for the recirculaion of water at the WNR is considered minimal.

5.7.8          Due to the relatively lower topography of the site, the conveyance of sewage generated by the residential development to nearby Government sewage treatment works should be accomplished by pumping.

5.7.9          Reference is made to the Drainage Service Department (DSD)’s standard design on the latest sewerage pumping station, which is totally enclosed by 100mm thick concrete wall. The opening of the pumping station will usually be located away from any NSRs. According to the approved “Comprehensive Feasibility Study for the Revised Scheme of South East Kowloon Development - Environmental Impact Assessment Report” Appendix 3c and the “Sound Analysis and Noise Control, John Forman, 1990, Van Nostrand Reinhold, Table 55, pp. 154”, the noise attenuation effect caused by building enclosure can be up to 29 dB(A).

5.7.10      The proposed pump house will be made reference to the DSD’s standard design on the latest sewerage pumping station which will be a totally enclosed building with 100mm thick concrete wall.  A design will also be adopted to avoid any opening or louvers, if any, facing the nearest NSR. 

5.7.11      The proposed pump house design envisaged for the residential development will be made reference to larger district pumping stations which can provide more conservation assumptions. With reference to the approved “Drainage Service Department Agreement No. CE 29/2001 Outlying Islands Sewerage Stage 1 Phase 1 Ngong Ping Sewage Treatment Works and Sewerage Investigation, Design and Construction – Final EIA” Appendix 4B and with taking into account of the tonal, impulsive and intermittent characteristic and effects of the pump operation, the sound power level of the pump would be 100 dB(A). A calculation of the likely impact is presented as follows: -

Sound power level (SWL) of one pump                                                = 100 dB(A)

Sound power level (SWL) of two duty and one standby pumps   = 103 dB(A)

Minimum setback distance of the NSR from the pump house     = 150 m

Distance attenuation                                                                            = -52 dB(A)

Façade correction                                                                               = 3 dB(A)

Noise reduction due to building enclosure                                              = -29 dB(A)

Corrected Noise Level at the nearest NSR, [Leq (30min)]                     = 25 dB(A)

5.7.12      It is obvious that the above can comfortably be achieved for pump house of a size suitable for a residential development of this scale in terms of the minimum setback distance and the power (hence the sound power) needed. The attenuation in noise impact should be enough to enable compliance with the assessment criteria given in Section 5.6.4 above.

5.7.13      Subject to the selected sewerage option and the final design of the MLP and the pump house, it is expected to be housed inside a concrete structure near the car-park area for the visitors with openings at the southern side facing away from any NSRs. The pump house will have a setback distance of more than 150m from the residential block, and any nearby NSRs.

5.7.14      The detailed information of the exact design and the plant list will be submitted to the relevant Authority for approval prior to the commencement of the construction works of the pump house.

 

5.8              Impacts Summary and Conclusion

Construction Phases

5.8.1          A quantitative construction noise impact assessment has been conducted to predict the potential construction noise impact on Noise Sensitive Receivers situated in the vicinity of the development site. The study has been carried out in accordance with procedures outlined in the “Technical Memorandum on Noise from Construction Work Other Than Percussive Piling”.  Based on the preliminary construction programme and an equipment inventory, the likely construction noise levels at the nearby NSRs were predicted for a number of worst construction scenarios.

5.8.2          Control/ mitigation measures should be implemented to reduce the noise impact arising from the construction works as far as practicable for the protection of the NSRs. Mitigation measures recommended include use of silenced equipment, erection of temporary noise barriers, use of noise enclosure, phasing of construction activities, good site practice and noise management, and reduce number of equipment operating near the site boundary and in the vicinity of NSRs.

5.8.3          With these mitigation measures in place, the predicted construction noise impact at all NSRs will be reduced to acceptable levels.

5.8.4          The implementation of these noise mitigation measures during the construction phase is recommended to be monitored by an EM&A programme as described in the EM&A Manual.

Operational Phase

5.8.5          Sewage pump house at the residential portion of the Project is the only major noise source identified to be of concern to the future noise sensitive receivers. Based on conservative assumptions of the possible noise power levels for the sewage pump house, the noise impact was evaluated and has been found to be acceptable if a minimum setback of 150m (or less for smaller pumps) is observed. The pumps should be housed inside a concrete structure with openings facing away from any NSRs.

5.8.6           

6.                  Water quality impact assessment

6.1              Introduction

6.1.1          This section presents an assessment of the potential water quality impact that may arise from construction and operation of the Project.  The assessment has been carried out in accordance with the requirements given in Clause 3.5.3 of the EIA Study Brief and the criteria and guidelines as stated in Annexes 6 and 14 of the EIA-TM respectively. 

6.1.2          The “assessment area” covers fishponds surrounding the Subject Site and surrounding areas in the larger Deep Bay Catchment Area of the Deep Bay Water Control Zone (WCZ), the Mai Po Inner Deep Bay Ramsar Site, and Hong Kong Wetland Park as shown in Figure 6‑1.

 

6.2              Description of Existing Water Systems and Respective Catchments

General

6.2.1          The Subject Site is situated close to the Inner Deep Bay with some 43 ha of the Site is designated as Mai Po Inner Deep Bay Ramsar Site since September 1995. The site lies within Wetland Conservation Area, which is subject to planning control for protecting the adjoining Mai Po Inner Deep Bay Ramsar Site from incompatible land uses. The Site is also close to the Hong Kong Wetland Park (HKWP) and the Mai Po area to its northeast. The Subject Site is abutted by fishponds on 3 sides with a village situated to the south.

6.2.2          Early maps and aerial photographs suggested that the Site was formerly part of an extensive swamp that existed around the fringes of Deep Bay. During this century the swamp has gradually been reclaimed first for paddy cultivation and later for fish and duck ponds.

6.2.3          The Site is a flat low-lying area divided by low earth bunds into a mosaic of fishponds used for fish farming. Water systems in the vicinity of the Site are mainly drainage channels, natural rivers, fishponds, wetland, and marine waters etc.

Drainage channels within the Subject Site

6.2.4          At the Site, the level on top of the fishpond bunds varies from approximately +3.1 to +3.3 mPD, at the north and east to about +4.2 mPD at the south. All of the catchments upstream of the Site drain via 3 unlined drainage channels within and adjacent to the Site into two river channels leading to the Inner Deep Bay. The two drainage channels flowing to the west discharge to the Deep Bay via one of the tidal channels – the Tai River forming the delta to the Tin Shui Wai catchment drainage system. The other drainage channel flowing to the east discharges into Deep Bay via the San Pui River. None of the 3 drainage channels on-site includes control structures, and therefore water levels are controlled by both fluvial and surge tide conditions. The locations of these water bodies and catchments are illustrated in Figure 6‑2.

Tai River

6.2.5          The Tai River flows beside the northwestern part of the Subject Site, and receives flow from its southwestern catchment.

6.2.6          The Tai River is a mangrove-lined channel and is intertidal. The perimeter bunds abutting the Tai River are approximately +3.8 mPD and are higher than the predicted mean high water in the channel (+2.4 m PD). Under normal circumstances, the interior of the Subject Site remains free of tidal influence. Overtopping of the perimeter might occur in an extreme combined high tide and storm event. However, this is likely to be extremely rare given the past extreme sea levels at nearby Tsim Bei Tsui to the northwest of the Subject Site, which peaked at +3.85 mPD with a return period of 100 years for records between 1974 and 1990. The predicted tidal range for 2002 at Tsim Bei Tsui is 0-3 mPD with an average peak tide of +2.4 mPD.

Shan Pui River

6.2.7          The Shan Pui River is lying east of the Subject Site, and is the downstream section of the Yuen Long Creek with a length of 60km and a catchment area of about 26.7km2. Limited water circulation in the Inner Deep Bay has enhanced sedimentation and retention of pollutants in the creek (EPD, 1999). To reduce the tidal effects and odour problems in the lower creek, an inflatable dam and a dry weather flow channel were installed at Yuen Long Nullah to prevent back flushing from Deep Bay.

6.2.8          Shan Pui River collects stormwater drainage discharge from catchment within the southeast part of the Subject Site and areas to the immediate southeast apart from catchment flow in Yuen Long area carried by Yuen Long Creek.

6.2.9          Flooding has been a major problem in the North West New Territories.  As part of the Main Drainage Channel Project for Ngau Tam Mei, Yuen Long and Kam Tin, Shan Pui River was widened and channelised to form a 3.3km long trapezoidal-shaped drainage channel. The new channel is mainly unlined except for a 0.46km section located upstream of the confluence with the existing Kam Tin River. The downstream un-lined section has a constant bed level of about -0.65mPD (ERM, 1996). Width of the channel ranges from 80m at upstream to 320m at the downstream section.  The drainage works at Shan Pui River commenced in October 1993 and were completed in mid 1999.

Tin Shui Wai Nullah

6.2.10      Tin Shui Wai Nullah collects catchment flows from areas southwest of Inner Deep Bay and drains to Inner Deep Bay eventually. It is a concrete channel built to collect runoff. The Hong Kong Wetland Park to the west of the Subject Site is developed alongside the Nullah.

6.2.11      The exit points of Tai River and Shan Pui River are situated over 180 m and 460 m respectively from the boundary of the Subject Site. The exit point of Tin Shui Wai Nullah is located further away from the Subject Site at some 600m apart.

Marine Waters and Ramsar Site

6.2.12      The Deep Bay Water Control Zone (WCZ) was gazetted on 1 December 1990. The WCZ covers the Mai Po Marshes together with the inner Deep Bay area. It contains 4 Sites of Special Scientific Interest (SSSIs), including Inner Deep Bay, Mai Po Marshes, Tsim Bei Tsui and Tsim Bei Tsui Egretry. Oyster beds were found near Lau Fau Shan, Sheung Pak Nai and Ha Pak Nai.  The estuarine mud flats of Inner Deep Bay are of international importance for migrating and wintering birds.

6.2.13      The Mai Po Marshes and Inner Deep Bay are classified as Mai Po Inner Deep Bay Ramsar Site included in the Ramsar List of Wetlands of International Importance (Ramsar List) in 1995. The Convention on Wetlands, signed in Ramsar, Iran, in 1971, is an inter-governmental treaty, which provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources.  Wetlands included in the Ramsar List acquire a new status at the national level and are recognized by the international community as being of significant value not only for the country, or the countries, in which they are located, but also for humanity as a whole.

6.2.14      Deep Bay is located on the east bank of the Pearl Estuary.  It is a shallow bay and has a surface area of about 112 km2.  During mean sea level, it contains approximately 330 Mm3 of water.  The rivers of interest that drain into Deep Bay include Shenzhen River on the PRC side, River Indus, River Beas, River Ganges, Yuen Long Creek, and Kam Tam River on the Hong Kong SAR side. Shenzhen River provides approximately 55% of the annual runoff into Deep Bay.

Fishponds and Wetland

6.2.15      There are altogether 105 nos. of fishponds within the study area amongst which 46 of the fishponds that occupy a total area of 60ha are currently actively managed and 10 of fishponds with a total area of 10ha have already been abandoned within the site boundary. Abandoned fishpond within the Subject Site concentrates mainly at the southern part.

6.2.16      The Subject Site is surrounded by existing fishponds to the immediate north, east and west.  Three tidal ponds are located to the immediate north of the Subject Site. Marine water and water in these three ponds mix together during high tide. Further north is a shallow wetland area where the Inner Deep Bay SSSI is located.

6.2.17      In the past, water in actively managed fishponds was drained into the Inner Deep Bay during heavy storm to avoid any overflow that may affect the fisheries. For the abandoned fishponds, it is logically assumed that water will flow over the access and bunds to the other fishponds as well as to other water bodies nearby upon overflow due to flooding.

Hong Kong Wetland Park

6.2.18      Hong Kong Wetland Park is situated to the west of the Subject Site, which is built as a compensation for the development of the Tin Shui Wai new town area. The wetland park has a total area of about 64 ha. Hong Kong Wetland Park provides created fresh water marshes and mud flats, as well as different types of habitats including grassland, mixed woodland, paddy fields, fishponds and mangrove.

6.2.19      Hong Kong Wetland Park creates a green buffer between the Tin Shui Wai new town development and the nearby Mai Po Marshes to the northeast of the Subject Site.

 

6.3              Characterisation of Baseline Water & Sediment Quality

6.3.1          Clause 3.5.3.4 (ii) of the Brief requires the characterisation of water and sediment quality of the natural/ artificial watercourses and manmade fishponds based on existing information or site survey.

6.3.2          A water and sediment quality survey covering the potential water sensitive receivers in the vicinity of the Project and the potential pollution sources such as fishpond water and mud has been conducted in May 2002 to record the baseline water and sediment quality prior to the construction and operational phases of the Project.

6.3.3          To make good use of the existing comprehensive data, the EPD routine water and sediment monitoring results have been reviewed to characterize the surrounding environment of the study area as far as possible. These data have the advantages of their abundance and completeness and are representative of seasonal and long-term trends.

6.3.4          Additional sampling data have also been obtained in-situ by the Consultant to fill the information gap of the existing water quality at the downstream of nearby rivers, which are close to the Subject Site and selected fishponds therein.

Marine Water Quality

6.3.5          There are 5 monitoring stations in the Deep Bay WCZ with DM1, DM2 and DM3 located in the inner sub-zone and DM4 and DM5 in Outer Deep Bay. Amongst all, DM1 is the nearest monitoring station to the Subject Site. Locations of these monitoring stations are shown in Figure 6‑3.

6.3.6          Water quality in the Deep Bay WCZ is not considered satisfactory with the inner bay polluted even more. The monitored 5-day Biochemical Oxygen Demand (BOD5), suspended solids (SS) and inorganic nutrient levels support this assertion.

6.3.7          At DM1, the monitored levels of Dissolved Oxygen (DO) ranges from 1.3 to 6.3 mg/L. About 80% of the samples have levels less than 4mg/L. This means that the DO objective was hardly met. Low DO was occasionally observed in the Inner Deep Bay during summer, indicating anoxic conditions. The total inorganic nitrogen (TIN) at all stations in the Inner Deep Bay did not comply with the WQO; while the unionised ammonia (NH3-N) was also recorded at above WQO levels except in the outer reaches of the bay. This persistently non-compliance signifies nutrient pollution problem in the Inner Deep Bay.

6.3.8          DO levels have improved when compared with earlier data in 1999 whereas the nutrient level increases at the same time. E.coli levels, on the other hand, experience a long-term increase, which can be attributed to faecal pollution problem in the Inner Deep Bay.

6.3.9          In summary, Deep Bay water quality is characterised by long-term pollution including nutrient enrichment, ammonia toxicity and bacterial contamination. This has led to Government’s effort to exercise more stringent control in this WCZ.

6.3.10      Table 6‑1 below summarises the marine water quality of the Deep Bay WCZ in 2005.

 

Table 61         Summary Statistics of Marine Water Quality of Deep Bay WCZ in 2005 (Inner Deep Bay)

Determinant

Inner Deep Bay

DM1

DM2

DM3

Number of samples

12

12

12

Temperature (oC)

24.2

24.2

24.2

 

(15.7 – 31.8)

(15.6 – 32.1)

(16.1 – 31.5)

Salinity (psu)

16.6

18.5

21.5

 

(1.8 – 24.1)

(3.1 – 27.0)

(4.1 – 30.0)

Dissolved Oxygen (mg/L)

2.9

4.3

5.3

 

(1.3 – 6.3)

(2.2 – 9.0)

(4.1 – 7.2)

Bottom

NM

NM

NM

Dissolved Oxygen (% Saturation)

38

57

72

 

(16 - 87)

(26 - 106)

(56 - 89)

Bottom

NM

NM

NM

pH

7.5

7.6

7.8

 

(7.0 – 8.0)

(7.1 – 8.2)

(7.3 – 8.3)

Secchi Disc Depth (m)

0.3

0.4

0.6

 

(0.2 – 0.5)

(0.2 – 0.6)

(0.2 – 1.0)

Turbidty (NTU)

42.7

40.4

38.0

 

(21.2 – 80.7)

(16.1 – 96.4)

(12.9 – 87.6)

Suspended Solids (mg/L)

49.5

42.4

40.7

 

(12.0 - 130)

(15.0 - 100)

(7.8 – 93.0)

5-day Biochemical Oxygen Demand (mg/L)

5.0

3.8

1.7

 

(2.1 – 8.9)

(1.7 – 7.7)

(0.4 – 3.9)

Ammonia Nitrogen (mg/L)

4.84

3.00

0.75

 

(2.10 – 6.80)

(1.20 – 4.90)

(0.27 – 1.40)

Unionised Ammonia (mg/L)

0.096

0.060

0.025

 

(0.023 – 0.460)

(0.015 – 0.164)

(0.005 – 0.075)

Nitrite Nitrogen (mg/L)

0.29

0.38

0.25

 

(0.13 – 0.48)

(0.20 – 0.75)

(0.16 – 0.37)

Nitrate Nitrogen (mg/L)

0.35

0.51

0.73

 

(0.08 – 1.20)

(0.23 – 1.70)

(0.27 – 2.00)

Total Inorganic Nitrogen (mg/L)

5.48

3.89

1.73

 

(3.68 – 7.01)

(3.20 – 5.58)

(0.99 – 2.87)

Total kjeldahi Nitrogen (mg/L)

5.79

3.68

1.19

 

(2.60 – 8.40)

(1.50 – 6.10)

(0.47 – 2.00)

Total Nitrogen (mg/L)

6.43

4.56

2.17

 

(4.18 – 8.61)

(3.50 – 6.78)

(1.47 – 3.18)

Orthophosphate Phosphorus (mg/L)

0.48

0.35

0.13

 

(0.23 – 0.65)

(0.18 – 0.53)

(0.07 – 0.19)

Total Phosphorus (mg/L)

0.68

0.48

0.21

 

(0.45 – 0.93)

(0.23 – 0.75)

(0.10 – 0.31)

Silica (as SIO2) (mg/L)

6.1

5.0

3.5

 

(1.0 – 11.0)

(1.2 – 9.9)

(0.8 – 7.3)

Chlorophyll-a (μg/L)

35.9

15.7

6.3

 

(0.6 - 260)

(0.4 - 140)

(0.2 – 39.0)

E.coli (cfu/100mL)

9800

1300

150

 

(2100 - 360000)

(160 - 26000)

(2 - 3800)

Faecal Coliforms (cfu/100mL)

17000

3100

430

 

(3000 - 740000)

(270 - 91000)

(8 - 5600)

 

Note:      1. Except as specified, data presented are depth-averaged (A) values calculated by taking the means of three depths: Surface (S), Mid-depth (M), and Bottom (B).

              2. Data presented are annual arithmetic means of depth-averaged results except for E.coli and faecal coliforms, which are annual geometric means.

              3. Data in brackets indicate the ranges.

              4. NM- not measured.

 

Marine Sediment Quality

6.3.11      There are 4 monitoring stations DS1, DS2, DS3 and DS4 located within Deep Bay WCZ. DS1 and DS2 are located in the inner sub-zone. DS1, which overlap with the location of DM1, is the nearest monitoring station to the subject site. Heavy metals, trace organics, electrochemical potential and others were monitored at these monitoring stations with locations shown in Figure 6‑4. Table 6‑2 summarizes the marine bottom sediment quality of Deep Bay WCZ from 2001 to 2005. There is a higher concentration of ammonical nitrogen, total sulphide, zinc and high molecular weight PAHs in DS1. On the other hand, highly anaerobic sediments are found, which are subject to the deposition of fish excreta and excessive feedstock on the seabed, resulting in anoxic situation.

 

Table 62        Summary Statistics of Marine Bottom Sediment Quality of Deep Bay WCZ, 2001 -2005

Determinant

Inner Deep Bay

DS1

DS2

Number of samples

10

 

10

 

Particle Size Fractionation <63um (%w/w)

68

(8 - 92)

79

(6390)

Electrochemical Potential (mV)

-273

(-366 to –145)

-175

(-272 to –34)

Total Solids (%w/w)

47

(3453)

47

(43 – 50)

Total Volatile Solids (%w/w)

6.6

(4.77.8)

6.9

(6.07.5)

Chemical Oxygen Demand (mg/kg)

20000

(15000 –25000)

17000

(12000 – 19000)

Total Carbon (%w/w)

0.6

(0.4 – 0.7)

0.6

(0.5 – 0.7)

Ammonical Nitrogen (mg/kg)

42.9

(2.5230)

10.5

(<0.0553.0)

Total Kjeldahl Nitrogen (mg/kg)

383

(210 – 750)

391

(160-510)

Total Phosphorus (mg/kg)

259

(110 - 580)

291

(140 – 380)

Total Sulphide (mg/kg)

365

(221200)

124

(29320)

Total Cyanide (mg/kg)

0.2

(<0.1 – 0.3)

0.2

(<0.1 – 0.6)

Arsenic (mg/kg)

11.2

(8.514.0)

13.2

(9.9 – 18.0)

Cadmium (mg/kg)

0.3

(<0.1 – 0.6)

0.3

(0.1 – 0.4)

Chromium (mg/kg)

40

(2856)

41

(22 – 49)

Copper (mg/kg)

56

(16100)

57

(2670)

Lead (mg/kg)

59

(39 – 86)

57

(3087)

Mercury (mg/kg)

0.12

(<0.05 – 0.29)

0.14

(0.06 – 0.23)

Nickel (mg/kg)

25

(1833)

26

(14 – 29)

Silver (mg/kg)

0.8

(<0.22.0)

0.8

(<0.2 – 1.0)

Zinc (mg/kg)

195

(100 – 380)

180

(91 – 240)

Total Polychlorinated Biphenyls (PCBs) (ug/kg)

18

(1818)

18

(1818)

Low Molecular Wight Polycyclic Aromatic Hydrocarbons (PAHs) (ug/kg) (3) (5)

92

(90104)

92

(9096)

High Molecular Weight Polycyclic Armoatic Hydrocarbons (PAHs) (ug/kg) (4) (5)

104

(18355)

99

(54190)

 

Note:      1. Data presented are arithmetic means; data in brackets indicate ranges.

2. All data are based on the analyses of bulk (unsieved) sediment and are reported on a dry weight basis unless stated otherwise.

3. Low molecular weight polyaromatic hydrocarbons (PAHs) include 6 congeners of molecular weight below 200, namely: Acenaphthylene, Acenaphthene, Flourence, Naphthalene, Phenanthrene and Anthracene.

             4. High molecular weight polyaromatic hydrocarbons (PAHs) include 10 congeners with    molecular weight above 200, namely: Fluoranthene, Pyrene, Benzo(a)anthracene, Chrysene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Dibenzo(a,h)anthracene, Benzo(g, h, i)perylene and Indeno(1,2,3-cd)pyrene.

5. Low Molecular Weight PAHs results are based on sediment samples collected in 2002-2005 only.

6. N.D.: Not detected – all congeners are below the detection limits.

 

River Water Quality

6.3.12      There are a number of river monitoring stations located within Deep Bay WCZ. The directly related monitoring stations are the four stations, YL1, YL2, YL3 and YL4 at Yuen Long Creek and the two stations, KT1 and KT2 at Kam Tin River, which eventually flow to the downstream river (Shan Pui River) to Inner Deep Bay. Furthermore, the two stations, TSR1 and TSR2, at Tin Shui Wai Nullah flow to the same water body (Inner Deep Bay) eventually. No monitoring station exists for Tai River.

6.3.13      Water Quality Index (WQI) is a numerical value summarising the general quality of a river. Referring to data in 2005, the Water Quality Index (WQI) in Yuen Long Creek are graded either “very bad” or “bad” in 2005. The water quality in Yuen Long Creek are far from satisfactory. The unsewered villages and livestock farms are expected to be the main sources of pollution.

6.3.14      Similar to Yuen Long Creek, Kam Tin River has been severely impacted by unsewered villages and livestock wastes. The WQI in Kam Tin River was graded “bad” in 2005. The locations and WQI of EPD’s monitoring stations at Yuen Long Creek (YL1 to YL4) and Kam Tin River (KT1 and KT2) are shown in Figure 6‑5.

6.3.15      On the other hand, the WQI in Tin Shui Wai Nullah, which is a concrete channel further away from the Subject Site, have been improved to “fair and “good” respectively for TSR1 and TSR2 in 2005. The locations and WQI of EPD’s monitoring stations at Tin Shui Wai Nullah are shown in Figure 6‑5.

6.3.16      No monitoring station exists for Tai River so that no information is available regarding to its water quality.

6.3.17      Table 6‑3 has summarized the river water quality of Yuen Long Creek, Kam Tin River and Tin Shui Wai Nullah in 2005.

Catchment Water Quality

6.3.18      All the catchments (Catchment A, B and C) for the drainage channels within the Subject Site are dominated by dense semi-natural scrub and woodland vegetation. There are no apparent point sources of pollutants such as pig farms etc. Water from catchment flow is likely to be of relatively low nutrient and Biological Oxygen Demand (BOD) content. It is also anticipated that suspended solid (mainly silt) in runoff during heavy rainfall periods is relatively low due to the existing dense vegetation cover in the catchments.

 


Table 63         Summary of River Water Quality Monitoring results for Yuen Long Creek, Kam Tin River and Tin Shui Wai Nullah in 2005

Parameters

Unit

Sampling Station

Yuen Long Creek

Kam Tin River

Tin Shui Wai Nullah

YL1

YL2

YL3

YL4

KT1

KT2

TSR1

TSR2

Dissolved oxygen

mg/L

3.9

6.6

3.1

3.6

4.3

3.8

7.6

10.1

 

 

(1.8 - 7.8)

(3.2 - 9.9)

(1.5 - 7.8)

(1.6 - 6.9)

(1.2 - 7.1)

(1.7 - 7.2)

(1.6 - 10.6)

(8.0 - 12.4)

PH

 

7.4

7.4

7.4

7.2

7.3

7.3

7.5

8.7

 

 

(7.1 - 7.8)

(7.1 - 8.1)

(7.1 - 7.7)

(7.0 - 7.5)

(7.1 - 7.4)

(7.1 - 7.5)

(7.1 - 8.4)

(7.6 - 9.3)

Suspended Solids

mg/L

25

15

58

47

18

36

13

13

 

 

(2 - 100)

(3 - 53)

(10 - 130)

(25 - 220)

(5750)

(3 - 200)

(2 - 46)

(4 - 820)

5-day Biochemical

mg/L

38

8

80

74

14

52

12

1

Oxygen Demand

 

(6 - 130)

(5 - 20)

(18 - 150)

(24 - 120)

(6 - 740)

(5 - 150)

(5 - 27)

(1 - 5)

Chemical Oxygen

mg/L

46

19

88

93

22

74

13

7

Demand

 

(6- 360)

(11 - 59)

(24 - 410)

(30 - 180)

(10 - 1600)

(8 - 210)

(8 - 60)

(2 - 12)

Oil & grease

mg/L

0.9

0.5

4.9

6.4

0.5

3.6

0.5

0.5

 

 

(0.5 - 15.0)

(0.5 – 0.9)

(0.5 - 15.0)

(0.7 - 23.0)

(0.5 - 140.0)

(0.5 - 40.0)

(0.5 - 3.1)

(0.5 - 1.0)

Faecal coliforms

cfu/

740,000

100,000

3,100,000

3,900,000

550,000

970,000

630,000

41,000

 

100mL

(84,000 – 4,700,000)

(29,000 - 330,000)

(1,200,000 - 9,000,000)

(1,400,000 – 26,000,000)

(54,000 - 3,200,000)

(150,000 – 5,000,000)

(100,000 - 7,900,000)

(3,600 - 350,000)

E coli

cfu/

510,000

42,000

1,900,000

1,300,000

150,000

730,000

250,000

15,000

 

100mL

(38,000 - 3,900,000)

(8,000 - 180,000)

(660,000 - 6,500,000)

(360,000 – 4,700,000)

(24,000 – 1,700,000)

(80,000 – 3,700,000)

(39,000 - 4,100,000)

(600 - 110,000)

Ammonia-nitrogen

mg/L

24.50

7.30

12.50

4.20

9.65

15.00

2.20

0.15

 

 

(0.62 – 59.00)

(1.50 - 16.00)

(4.20 - 40.00)

(2.30 - 24.00)

(1.00 - 27.00)

(0.98 - 43.00)

0.73 - 7.50)

(0.04 - 2.00)

Nitrate nitrogen

mg/L

0.12

1.50

0.01

0.01

0.59

0.01

0.96

1.25

 

 

(0.011.30)

(0.47 - 3.00)

(0.01 - 1.30)

(0.01 - 0.03)

(0.01 - 1.00)

(0.01 - 0.72)

(0.01 - 2.40)

(0.69 - 2.00)

Total Kjeldahl

mg/L

29.50

8.45

18.0

7.85

11.40

20.00

3.00

0.45

nitrogen. SP

 

(1.40 - 72.0)

(2.50 - 19.00)

(5.80 - 61.00)

(3.8 - 33.00)

(1.70 - 84.00)

(1.50 - 58.00)

(1.50 – 12.00)

(0.13 - 2.50)

Ortho-phosphate

mg/L

3.10

1.65

2.05

0.58

1.85

3.05

0.15

0.03

 

 

(0.237.50)

(0.52 - 4.90)

(0.85 - 6.90)

(0.25 - 3.80)

(0.47 - 8.30)

(0.36 - 8.60)

(0.06 - 0.70)

(0.02 - 0.28)

Total phosphorus,

mg/L

3.65

2.00

3.05

1.25

2.45

4.15

0.36

0.05

SP

 

(0.37 - 11.0)

(0.74 - 5.90)

(1.20 - 11.00)

(0.56 - 5.10)

(0.63 - 26.00)

(0.48 - 11.00)

(0.22 - 1.30)

(0.02 - 0.39)

Sulphide, SP

mg/L

0.04

0.02

0.06

0.05

0.03

0.06

0.02

0.02

 

 

(0.02 - 0.75)

(0.02 - 0.10)

(0.02 - 0.19)

(0.02 - 0.09)

(0.02 - 2.40)

(0.02 - 0.43)

(0.02 - 0.18)

(0.02 - 0.02)

Aluminium

μg/L

200

230

260

295

110

110

155

170

 

 

(90 - 280)

(80 - 580)

(100 - 540)

(100 - 1,200)

(50 - 230)

(50 - 450)

(50 - 430)

(90 - 980)

Cadmium

μg/L

0.10

0.10

0.10

0.10

0.10

0.10

0.10

0.10

 

 

(0.10 - 0.20)

(0.10 - 0.20)

(0.10 - 0.3)

(0.10 - 0.30)

(0.10 - 0.30)

(0.10 - 0.30)

(0.10 - 0.20)

(0.10 - 0.30)

Chromium

μg/L

1.0

1.0

2.0

1.0

1.0

1.0

1.0

1.0

 

 

(1.0 - 3.0)

(1.0 - 2.0)

(1.0 - 5.0)

(1.0 - 5.0)

(1.0 - 3.0)

(1.0 - 5.0)

(1.0 - 14.0)

(1.0 - 1.0)

Copper

μg/L

19.0

7.0

23.0

5.0

8.0

11.0

5.0

2.0

 

 

(2.0 - 573.0)

(4.0 - 29.0)

(7.0 - 59.0)

(2.0 - 32.0)

(3.0 - 47.0)

(3.0 - 65.0)

(2.0 - 21.0)

(1.0 - 11.0)

Lead

μg/L

4.0

4.0

5.0

6.0

2.0

2.0

3.0

2.0

 

 

(2.0 - 6.0)

(1.0 - 8.0)

(2.0 - 16.0)

(2.0 - 24.0)

(1.0 - 4.0)

(1.0 - 19.0)

(1.0 - 15.0)

(1.0 - 97.0)

Zinc

μg/L

100

55

75

60

45

85

75

20

 

 

(20 - 240)

(20 - 110)

(30 - 340)

(20 - 360)

(20 - 180)

(20 - 510)

(20 – 1,500)

(10 - 120)

Flow

L/s

166

120

615

230

474

158

NM

84

 

 

(32 - 990)

(68 - 255)

(2501,523)

(64 - 518)

(75 - 2,000)

(81,323)

 

(201,575)

Note:

1.       Data presented are in annual medians of monthly samples; except those for faecal coliforms and E. coli, which are in annual geometric means.

2.       Figures in brackets are annual ranges.

3.       NM indicates no measurement taken.

4.       Cfu – colony forming unit.

5.       SP – soluble and particulate fractions (i.e. total value).

6.       Values at or below laboratory reporting limits are presented as laboratory reporting limits.

7.       Equal values for annual medians and ranges indicate that all data are the same as or below laboratory reporting limits.


Fishpond Water and Sediment Quality

6.3.19      In the “Objection to Draft Lau Fau San & Tsim Bei Tsui Outline Zoning Plan S/YL/-lFS/1 Lot 1457 R.P., D.D. 123 – Fung Lok Wai Alternative Proposal”, water quality sampling has been conducted in 6 fishponds at Fung Lok Wai in 1995.  The results are shown as follow. The mean DO level amounts to more than 3 times of the DO objective of Deep bay WCZ. The mean pH value falls within the range specified in the WQO. The salinity is not more than 3 ppt and would not contribute to any significant change. There is, however, no SS, nutrient and E.coli level available.

 

Table 64         Results Of Water Quality Monitoring In Fishponds At Fung Lok Wai (1995)

 

Mature ponds

Recently filled ponds

 

No. 8

No. 10

No. 53

Mean

No. 11

No. 38

No. 76

Mean

Temperature (oC)

13.9

14.15

14.25

14.1

13.5

13.35

14.65

13.83

Dissolved oxygen (mg l-1)

11.95

11.59

7.48

10.34

15.41

13.44

10.22

13.02

Dissolved oxygen sat. (%)

117.4

115.05

74.25

102.23

150.4

127.8

102.25

126.82

pH

8.15

8.25

7.94

8.11

8.51

8.54

7.85

8.3

Salinity (ppt)

2

3

2

2.3

3

3

3

3

Turbidity (Nephelometric Turbidity Units)

100.75

20.95

23.45

48.38

33.05

53.6

21.85

36.17

Note: All measurements taken by C.E.S. (Asia) Ltd on 3/2/95. See Figure 2‑9 “the Pond Numbering System” for the location of ponds.

 

Source: Objection to Draft Lau Fau San & Tsim Bei Tsui Outline Zoning Plan S/YL/-lFS/1 Lot 1457 R.P. D.D. 123 – Fung Lok Wai Alternative Proposal

 

Further Water and Sediment Quality Survey

6.3.20      To confirm the current baseline pond water and sediment quality at the Subject Site, pond water and sediment samples were collected by a HOKLAS accredited laboratory at a selection of 6 and 2 ponds respectively for laboratory analysis (see Figure 6‑6 and Figure 6‑7 for locations of these ponds).  Furthermore, in order to fill the information gap of the river water quality of the river downstream in the vicinity, water samples were also collected downstream of Tai River (W2) and Shan Pui River (W1).  The river water quality sampling locations is shown in Figure 6‑8.

6.3.21      The selected pond water sampling locations include active fishponds (Pond no. 2, 56, 59, and 62) and abandoned ones (Pond no. 13 and 19).  Sampled fishpond no. 2, 13 and 56 are located in the area for the proposed WNR whilst sampled fishpond no. 19, 59 and 62 are situated at the footprint of the proposed Residential Development. Also, the selected sediment sampling ponds (Pond no. 19 and 62) will coincide with the footprint of the proposed Residential Development.

6.3.22      Table 6‑5 and Table 6‑6 present the results of survey on fishponds/ river water and fishpond sediment quality respectively. 

 

Table 65         Results of Fishpond/ River Water Quality Survey at Fung Lok Wai

 

Sampled Fishpond

River water Sampling Stations

Parameters

Pond 2

Pond 13

Pond 19

Pond 56

Pond 59

Pond 62

W1 (Shan Pui River)

W2 (Tai River)

pH

6.2

7.7

9.3

6.9

8.9

7.0

7.8

7.5

Conductivity (uS/cm)

2510

1860

635

1640

1100

1100

16500

21500

D.O. (mg/L)

5.4

4.4

7.2

2.6

8.2

2.4

3.1

2.1

% Saturation of D.O. (%)

72.5

62.2

98.1

38.5

108

28.1

41.7

28.7

Temp. (oC)

31.3

31.0

30.4

30.7

32.5

30.5

30.0

29.0

Salinity (g/L)

1.1

0.5

0.3

0.7

0.5

0.5

8.8

11.9

Turbidity (NTU)

45.2

30.7

23.1

63.3

23.5

42.4

12.7

20.0

SS (mg/L)

72.7

57.0

28.3

93.7

47.0

49.7

32.3

26.3

Ammonia as N (mg/L)

0.03

0.03

0.04

2.96

0.07

0.39

5.4

2.8

Nitrate as N (mg/L)

<0.01

<0.01

<0.01

0.04

0.04

0.23

0.6

0.7

Nitrite+Nitrate as N (mg/L)

0.02

0.02

0.02

0.16

0.17

0.31

0.9

1.2

Total Kjeldahl Nitrogen as N (mg/L)

3.2

2.9

3.9

4.6

3.3

3.6

7.3

3.1

Total Nitrogen (mg/L)

3.2

2.9

3.9

4.8

3.5

3.9

8.2

4.3

Total Phosphorus (mg/L)

0.2

0.2

0.2

0.2

0.2

0.3

0.7

0.5

Reactive Phosphorus as P (mg/L)

0.03

0.03

0.02

0.02

0.03

0.02

0.6

0.4

BOD (mg/L)

10.0

8.7

14.3

5.3

9.0

4.7

3.0

<2

Note: All measurements by ALS Technichem (HK) Pty Ltd. on 30 May 2002.

 

Table 66         Results of Fishpond Sediment Quality Survey at Fung Lok Wai

 

Sampled Fishpond

Parameters

Pond 19

Pond 62

Heavy Metals

Silver (mg/ kg)

<1

<1

Arsenic (mg/ kg)

3.3

3.8

Cadmium (mg/ kg)

0.04

0.09

Chromium (mg/ kg)

9.5

37.4

Copper (mg/ kg)

4.2

17.4

Nickel (mg/ kg)

3.5

8.4

Lead (mg/ kg)

16.8

15.6

Zinc (mg/ kg)

21.5

71

Mercury (mg/ kg)

0.14

<0.05

Nutrients

Nitrite+Nitrate as N (mg/L)

0.15

0.11

Total Kjeldahl Nitrogen as N (mg/L)

552.7

978.6

Total Nitrogen (mg/L)

552.7

978.6

Total Phosphorus (mg/L)

186.17

759

Trace organics

Total PAHs (mg/L)

<0.5

<0.5

Total PCBs (mg/ kg)

<0.1

<0.1

Note: All measurements taken by ALS Technichem (HK) Pty Ltd. on 30/5/02.

 

6.3.23      The water sampling results are summarised below:

·        The average pH values of the samples are within WQO with the lowest and highest value of 6.2 and 9.3 recorded.

·        DO levels of the sampled fishponds range from 2.6 to 8.2 mg/L with the mean value complying with the Objective, and is higher than that of river water.

·        The sampled fishponds have high SS levels and BOD5 value. This could be attributed to extensive fish farming activities, limited water movement and air exchange at the fishponds.

·        The measured nutrients levels (TKN, TN and TP) at the Tai River have similar levels as the fishponds but the nutrients levels in Shan Pui River is higher than that of the Tai River.

6.3.24      Pond sediments were sampled for analysis of heavy metal contents.  A comparison with the Dutch criteria indicates that the fishpond sediment is in the uncontaminated category (A level). All measured heavy metal levels are below the relevant Dutch criteria. Furthermore, with reference to the ETWB TCW No. 34/2002 “Management of Dredged/ Excavated Sediment”, the sediment quality are well within the Lower Chemical Exceedance Level (LCEL) and can be classified as Category L sediment to represent uncontaminated material. Based on the pond sediment sampling results and the nature of the use associated with the fishponds, it is not expected that the operation of the ponds will result in any significant accumulation of heavy metal which could pose an environmental impact on the surrounding water sensitive receivers. On the other hand, the nutrient level of the samples is high as expected due to fish farming.

Summary of Existing Water and Sediment Quality of the Water Sensitive Receivers

6.3.25      Shan Pui River - The nutrient level of the flow in Shan Pui River is especially high. On the other hand, DO level is relatively low. Pollutants are mainly originated from upstream catchment in Yuen Long area carried by Yuen Long Creek and Kam Tin River though there is an indication of slight improvement of river water quality. The unsewered villages and livestock farms are expected to be the main pollution sources bringing about nutrients, faecal organic wastes.

6.3.26      Tai River - Compared with Shan Pui River, the water quality of Tai River is generally better. Still, there is a considerable level of nutrients.

6.3.27      Fishponds within the Site and in the Surroundings - Owing to the nature of use of the water ponds, there are high levels of nutrients found in both water and sediments. For abandoned fishponds, the SS and nutrient level is slightly lower in general but comparative to the actively managed ones.

6.3.28      Inner Deep Bay - Owing to the slow circulation of water flow, pollutants tend to accumulate within this water body. Pollutants brought from River Indus, Shenzhen River, Tin Shui Wai Nullah, Shan Pui River (Yuen Long Creek) includes nutrients, faecal and organic wastes. Inner Deep Bay is subject to long-term problem of nutrient enrichment, ammonia toxicity and bacterial contamination.

 

6.4              Existing and Planned Activities In Relation to Water Systems

Existing Activities

6.4.1          Both point and non-point discharges from the fishponds could possibly occur in wet seasons during heavy rain. Parts of the Subject Site are still being used for fish farming although some of them have been abandoned. For active fishponds, pond water is being discharged intentionally during heavy storm to avoid overflow of the fishpond and loss of fish stock. Such discharges contain fish excreta and could be one of the factors causing the anoxic situation in the Inner Deep Bay. For the abandoned fishponds, overflow will occur only during heavy storm.

6.4.2          Other construction works and livestock farms upstream of Yuen Long Creek and Tin Shui Wai Nullah generate particulates, BOD5 and others, which result in poor water and sediment quality in the Inner Deep Bay.

Planned Activities during Construction Phase

6.4.3          Construction of the Project includes the improvement works of an access road, site formation, superstructure work and construction of other associated facilities for the residential development, and establishment of the Wetland Nature Reserve (WNR).

6.4.4          Construction works involve clearance of sheds, demolition of some existing fish pond bunds/ access paths, ponds dredging followed by partial or complete pond filling, compaction and piling works, road paving, foundation and superstructure works. The establishment of the WNR will also involve creation of marshland and re-profiling and landscaping of the ponds.

6.4.5          Pond filling will be divided into a number of steps including draining of pond water, mud dredging and filling of pond using public fill materials. Pond re-profiling, on the other hand, involves temporary emptying of water ponds, dredging, removal and/or reconstruction of bunds and refilling of the ponds, partial filling of mud for formation of marsh land. Some of the bunds currently separating ponds will be lowered and side cast to create shallow sloping margins to islands and / or shoals.

6.4.6          Particulates as well as effluent, liquid spillage and the like will be generated on-site during construction. Pollutants can runoff to nearby water bodies as non-point discharge if not properly controlled.

Construction of Residential Development and Access Road - Dredging and Pond Draining and Filling

6.4.7          The construction of the residential portion and the WNR visitor centre of the Project requires ponds draining, dredging and filling. The affected ponds are Pond No. 58, 59, 62, 25, 23 and 19 as per the preferred footprint for residential development and WNR visitor centre.

6.4.8          After pond filling would be foundation and superstructure works, and construction of other associated facilities for the residential development and the WNR.

Construction and Establishment of WNR

6.4.9          There are currently 56 fishponds within the study site. Through the strategic removal of bunds these will be consolidated into 21 larger ponds (See Figure 6‑9).

6.4.10      At selected locations, bund materials currently separating ponds will be lowered and side cast to create shallow sloping margins to islands and / or shoals. The remaining bunds to be modified will be used to create islands. Each island will rise at a slope 1:20 from the indicated waterline, based on initial operating levels. The below water level slope will be as shallow as feasible.

6.4.11      Each pond will be drained, dried and re-profiled on a 3 to 5-year cycles (please refer to Section 14 the Draft Habitat Creation and Management Plan – Long-term Pond Management (Table 14‑13)) as typically currently carried out on fishponds. During this process each pond bund will be re-profiled to create as shallow a slope as feasible according to the properties of the bund material. 

6.4.12      In addition, following re-profiling, further works will be undertaken under the direction of the Site Conservation Manager to provide variation in the shoreline profile along the typical waterline. This will be carried out by using a backhoe to create indentations along the water line at the Initial Operating Level by small-scale excavations and pressing down with the back of the excavator bucket on the bund. Approximately 30% of the margins of each pond should be worked in this way to create a ‘scalloped edge’ with shallow shelves just below the Initial Operating Level (0.1 – 0.3m depth).

6.4.13      For flow control amongst ponds, the engineering requirements will consist of installation of a series of adjustable sluices to interconnect the ponds

6.4.14      All fishpond water will be obtained by direct rainfall and will be retained and re-circulated during drain-down periods as necessary. One pond will also be used in each year as a reservoir pond as a contingency measure to ensure that pond water levels are kept within tolerance levels. No surface or groundwater water supplies will be used for fishpond operations.

6.4.15      The establishment of WNR will involve the followings: -

·        Enlargement of some fishponds for herons and egrets

·        Re-profiling of a no. of selected pond bunds to enhance feeding of birds

·        Development of emergent vegetation on selected pond margins for screening

·        Creation of areas of shallow water and intermittently exposed muddy islands to enhance feeding and roosting of birds 

Planned Activities during Operational Phase

Residential Development and Access Road

6.4.16      The proposed residential development will be located remote from the famous Mai Po Marshes to minimise possible disturbances to this natural habitat.

6.4.17      All domestic wastewater will be discharged to the public sewerage system. Water quality impact due to emergency discharge from sewage pump house and sewer bursting are discussed in Section 8.8 of Section 8 Sewerage and Sewage Treatment Implications.

6.4.18      Drainage system will be provided for the formed and paved road/areas to drain stormwater runoff into the storage pond next to the Marshland. Sand trap and oil interceptor will be provided especially for car park and similar facilities, which would possibly generate grease, oil and other pollutants.

Operation Of The Wetland Nature Reserve

6.4.19      The development of the Wetland Nature Reserve provides another buffer zone for the famous Mai Po Marshes other than the Hong Kong Wetland Park. In fact, as it is relatively closer to the Mai Po Marshes as compared with the Hong Kong Wetland Park, the proposed Wetland Nature Reserve will play a more important role in minimising disturbance to the natural habitat in Mai Po.

6.4.20      Maintenance of fishponds and wetland reservation areas is necessary during the operation of the proposed development. A management plan is to be devised to determine a most environmental friendly option including but not limited to details for feeding of fisheries, set up of fencing and restriction from trespassing.

6.4.21      The water levels of the fishponds inside the wetland nature reserve will be managed and controlled by the Reserve Manager. During normal operation, the wetland nature reserve will be self-contained and pond water will not be discharged to the surrounding. Water will only be discharged when there is overflow. As the size of wetland area is enhanced and the operating levels of the fishponds will be wisely controlled and maintained at a relatively lower water levels comparing with the water levels of conventional practices, the frequency of discharge upon overflow will be less than existing situation.

6.4.22      The generation of fish excreta and excessive feedstock are expected to be similar to the existing situation but with slight improvement due to the devising of more environmental friendly management plan including but not limited to careful selection of species and control of fish population. Although existing fishponds of over 76ha will be redeveloped as Wetland Nature Reserve, the hydrology remains the same. The overall impact due to discharge upon overflow of the wetland area is expected to be slightly improved.

Operation of The Marshland

6.4.23      The Marshland complex will comprise 3 distinct regions as follows: -

·        A relatively large area of permanent marsh comprising a series of interconnected lakes and reed beds;

·        Seasonal marsh dominated by tussocky grasses and sedges and temporary pools; and,

·        A storage pond.

6.4.24      The proposed Marshland complex will be operated and maintained according to following principles:

·        The water supply will be from the storage pond, which collects direct rainfall and run-off from the residential development and catchments A and B (see Figure 6‑11).

·        Treated effluent will not be discharged into the wetland and there will be no reliance on groundwater.

·        The marsh area will not flood surrounding land and residential developments.

·        The lakes within the marsh area will eventually discharge via Channel X or, during storm events, via Channel Y (see Figure 6‑11) into the Tai River outfall.

6.4.25      Water control structures will be installed at the locations indicated in Figure 6‑10 to facilitate water management within the marsh complex.

6.4.26      Water levels at the Permanent Marsh Area will be allowed to fluctuate with seasonal patterns in rainfall but will be kept within defined limits to prevent drying out or flooding of susceptible vegetation through controlled release of water from the storage pond. Water will also be released judiciously to reduce the rate at which levels drop during the transition between wet and dry seasons.

6.4.27      At the Seasonable Marsh Area, a segment of the western part of the marsh complex will be managed as seasonal wetland receiving water from direct rainfall, and, during wet months, from the permanent marsh area. When water exceeds a pre-determined depth within the permanent marsh area water will flow into the seasonal marsh area via a sluice placed between the two areas. Excess water with the seasonal marsh area will gather at the northern end and exit via channel Y into the Tai River outflow.

 

6.5              Identification of Alteration of Water Systems Arising from the Project

Natural/ Artificial Watercourse

6.5.1          There will be no alteration of the any natural watercourse arising from implementation of the Project. However, the Project will affect 3 on-site artificial drainage channels.

6.5.2          Channel X will be incorporated into the proposed Marshland and Channel Z removed, as runoff will be collected in the Storage Pond.

6.5.3          Channel Y will be unaltered and be sluice controlled to allow orderly discharge of excess stormwater during flooding periods.

Manmade Fishponds

6.5.4          The Project occupies an area 80 ha in which the residential portion at the southern edge will occupy about 4 ha. This piece of land will be created by filling up a number of man-made fishponds there. Assuming 100% concrete-paving, the residential portion will contribute to an additional runoff due to change of catchment characteristics. This additional runoff will be collected in the proposed Storage Ponds for continuous discharge into the proposed marshland.

6.5.5          The surface runoff hydrographs before and after the Project has been estimated using the SCS method. Only 4 ha of land located southwest of the Site, which has changes in land use, were quantified.

6.5.6          The increase in volume of runoff from the built area of the Project before and after implementation has been calculated and tabulated as follows: -

Table 67         Estimated Runoff After Development

Return Period (Year)

Estimated Volume of Runoff (m3)

Before Development

After Development

Increase

50

7,513

7,640

127

200

8,992

9,120

128

 

6.5.7          The increases in volume of runoff are approximately 127 m3 and 128m3 for 50-year and 200- year return periods respectively. The increase in peak runoff rates from the residential portion before and after implementation has also been calculated and tabulated as follows: -

 

Table 68         Estimated Peak Rate of Runoff After Development

Return Period (Year)

Estimated Volume of Runoff (m3)

Before Development

After Development

Increase

50

1.574

2.143

0.569

200

1.871

2.521

0.65

 

Artificial Marshland

6.5.8          The Project will create 13.9 ha of artificial marshland to enhance the ecological values of the WNR. This Marshland will alter the flow regime by diverting the stormwater flowing in Channel Z through the Marshland. The flow is however buffered by the Storage Ponds, which act as water reserve for the Marshland during dry seasons.

 

6.6              Identification of Existing and Future Water & Sediment Pollution Sources

Construction Phase

6.6.1          Major potential sources of water pollution may include the followings: -

·        Runoff and erosion from exposed soil surface;

·        Runoff from stockpiles;

·        Fuels and lubricants from machinery and trucks;

·        Liquid spillage such as chemical, oil, diesel, and solvent;

·        General waste material;

·        Wastewater generated from dewatering activities.

6.6.2          Water pollution due to site facilities such as toilets could also be source of pollution if appropriate measures are not implemented properly during construction in respect of storage and discharge.

6.6.3          Additional impacts would arise from runoff that is contaminated by chemical, oil, diesel, lubricant, and solvent, etc. due to spillage or improper disposal. The implementation of Best Management Practices (BMPs) by the contractor during the project period is therefore important to control the release of these wastes. In addition, wastewater could also be generated from other phases of works such as site clearance, site preparation and completion of road construction.

Wetland Nature Reserve

6.6.4          Renovation of ponds may include the demolition of existing bunds and boundary as well as construction of new ones, partial filling and change of depth of the ponds. Draining of water is necessary during construction. Renovation will be carried out in a phased manner where water will be temporarily drained to other unaffected ponds and will be drained back after renovation.

6.6.5          Construction of the WNR will not alter the flow regime in the vicinity.

 

Residential Development

6.6.6          Construction of the proposed residential development involves:

·        Pond mud dredging

·        Pond filling

·        Compaction and foundation work

·        Superstructure construction

6.6.7          The strip of construction area to be formed for residential development is located along the southern boundary of the Subject Site remotely located from the Inner Deep Bay.

6.6.8          It is a general practice not to dredge mud if possible to avoid any adverse impact due to increase in particulate and re-exposure of any likely pollutants such as heavy metals. The amount of mud that can be retained on-site depends upon the soil nature and the method of construction of foundation. Yet, the possibility of the filling of pond using public filling material, which will inevitably be carried out for site formation, requires the draining of pond water to other places. The drained water may need to be discharged to other fishponds within the Subject Site. Compaction and foundation work involves piling and use of other powered mechanical equipment. Runoff during construction will bring along particulate to the water body including the existing fishponds.

6.6.9          Superstructure works are typical of many building construction works, which would generate insignificant degree of wastewater impact. If not properly controlled, the stormwater runoff may bring along other pollutants so as to pollute the nearby water bodies depending upon the topography.

Access Road Formation

6.6.10      The proposed alignment of the access road is to make use of existing Fuk Shun Street to connect the Development starting from the southern boundary of the Subject Site to the Yuen Long Industrial Estate. The road improvement works comprise the following construction stages:

·        Site clearance

·        Installation of utilities required

·        Road foundation work and paving of road

6.6.11      The proposed road works may pose water quality impact mainly due to surface runoff containing suspended solids, which might be generated as a result of excavation activities, earthworks. Apart from excavation, other construction tasks including compaction and paving of roads would unlikely generate considerable amount of dust.

Operational Phase

General Runoff and Sewage

6.6.12      Water for use in the WNR will be provided by direct rainfall supplemented by run-off from the residential development and catchments A and B via a ditch running along the southern border of the development area. Water will drain into the storage pond at the eastern end of the proposed WNR.

6.6.13      The run-off from residential site will pass through traps to remove oil and grease, and sand and gravel filters to reduce silt loads and particulate organic matter prior to discharge into the ditch and the storage pond. As runoff water from the catchments and development area will be stored for long periods before entering the wetland area any remaining silt that is present will be able to settle out in the water. This will further significantly reduce pollutant levels (from the residential runoff and catchments A and B). Regular maintenance, e.g. periodic de-silting will be required.

6.6.14      Foul water, on the other hand, will be discharged to the public sewer.

Discharge from WNR

6.6.15      The fishponds comprising the WNR will be interconnected with adjustable sluices to allow the circulation of water to reduce the likelihood of overflow upon heavy storm. In wet season, though unlikely, excess water will be drained and discharged to the Tai River under the management of conservation manager. This would not be frequent and depends on the intensity of rain.

 

6.7              Identification of Water Sensitive Receivers

General

6.7.1          Annex 14 of the TM on EIA Process listed the criteria of existing and potential beneficial uses that are considered sensitive to water pollution: -

·        Areas of ecological or conservation values including marine conservation areas, existing or gazetted proposed marine parks and marine reserves, sites of special scientific interest (SSSI), existing or gazetted proposed country parks and special areas, wetlands, mangroves and important freshwater habitats;

·        Areas for abstraction of water for potable water supply;

·        Water abstraction for irrigation and aquaculture;

·        Fish spawning grounds, fish culture zones, shellfish harvesting/culture site and brackish/freshwater fishponds;

·        Beaches and other recreational areas;

·        Water abstraction for cooling, flushing and other industrial purposes;

·        Areas for navigation/shipping including typhoon shelters, marinas and boat parks

6.7.2          Criteria of relevance to this Project include only point 1, 3 and 4. Water sensitive uses of these kinds are described as follows: -

SSSI

6.7.3          There are 4 SSSIs existing in the Deep Bay WCZ, viz.: -

·        Inner Deep Bay SSSI

·        Mai Po Marshes SSSI

·        Tsim Bei Tsui SSSI

o        Located next to the Tsim Bei Tsui Sub-divisional police station, it comprises mainly a mature mangrove community, which provides the only known habitat in Hong Kong for the large mangrove pulmonate snail.

·        Tsim Bei Tsui Egretry

6.7.4          All of the 4 SSSIs are situated downstream of the FLW Site which could be directly or indirectly affected by its effluents and runoff.

Wetlands, Mangroves and Important Freshwater Habitats

6.7.5          The existing wetland area (i.e. the Inner Deep Bay SSSI) to the north of the Subject Site fronting Inner Deep Bay is separated from the Site by a number of fishponds. Water draining from the Tai River and the San Pui River sustain an estuary, which is rich in important freshwater habitats including mangroves near the river mouths. Runoff from the Subject Site could indirectly affect these sensitive areas.

Water Abstraction for Irrigation and Aquaculture

6.7.6          As agricultural activities have already ceased for a long time in areas surrounding and downstream of the Subject Site, it is unlikely that water will be abstracted for irrigation. However, some of the existing fishponds outside the Subject Site could still be practicing fish farming and thus relies on occasional abstraction of water from the rivers.

Existing Freshwater Fishponds

6.7.7          There are a number of existing, actively managed fishponds situated to the north of the Subject Site, which could be affected by runoff from the Project during a heavy rainstorm.

Hong Kong Wetland Park

6.7.8          The Hong Kong Wetland Park (HKWP) has recently been completed.


6.7.9          It is obvious from the existing hydrology and flow regime that the Hong Kong Wetland Park and the Subject Site are separated by the Tai River and share no common catchment. Runoff from within the Subject Site, either from point or non-point source, should not in any way get into HKWP directly.

6.7.10      The Hong Kong Wetland Park is therefore not regarded as water sensitive receiver in respect of impact attributed by the Subject Site.

 

6.8              Water and Sediment Quality Assessment Criteria and Existing Policies

Water Quality Objectives

6.8.1          The Water Pollution Control Ordinance (WPCO) (Cap. 358) enacted in 1980 is the principal legislation controlling water quality in Hong Kong. Under the WPCO, Hong Kong waters are classified into 10 Water Control Zones (WCZ). Statutory Water Quality Objectives (WQOs) are specified for each WCZ.  The WQOs for any particular waters, as defined in the WPCO, shall be the quality, which should be achieved and maintained in order to promote conservation and best use of those waters in the public interest.  The Subject Site is situated within the catchment area of the Deep Bay WCZ. Table 6‑9 presents the WQOs for Deep Bay WCZ, which has been adopted for the assessment.

Table 69         Water Quality Objectives for Deep Bay WCZ

Parameter

Objective

Dissolved Oxygen (depth-average)

Not less than 4mg/L in 90% of the samples

Dissolved Oxygen (within 2m of bottom)

Not less than 2mg/L in 90% of the samples

Unionized Ammonia

Annual mean not exceeding 0.021mg/L

Total Inorganic Nitrogen

Annual mean depth average not to exceed 0.5mg/L and 0.7mg/L for Outer and Inner Sub-zone respectively

E.coli

Annual geometric mean not exceeding 610/100mL in secondary contact recreational areas

Salinity

Change due to waste discharge not to exceed 10% of natural ambient level

Temperature

Change due to waste discharge not to exceed 2°C

Suspended Solids

Waste discharge not to raise the natural ambient level by 30% nor cause the accumulation of suspended solids which may adversely affect aquatic communities

Toxicants

Not to be present at levels producing significant toxic effect

 

Sediment Quality Criteria

6.8.2          With reference to the ETWB TCW No. 34/2002 “Management of Dredged/ Excavated Sediment”, sediment quality can be classified as Category L, M and H sediment to represent uncontaminated materials, moderately contaminated materials and seriously contaminated materials respectively.

Table 610       Classification of Sediment

Category L :

Sediment with all contaminant levels not exceeding the LCEL

Category M :

Sediment with any one or more contaminant levels exceeding the LCEL and none exceeding the UCEL

Category H :

Sediment with any one or more contaminant levels exceeding UCEL

 

6.8.3          The selected sediment quality criteria for classification of sediment stated in ETWB TCW No. 34/2002 is given in Table 611 below: -

 

Table 611     Sediment Quality Criteria for the Classification of Sediment

Contaminants

Lower Chemical Exceedance Level (LCEL)

Upper Chemical Exceedance Level (UCEL)

Heavy metals (mg/kg dry wt.):

 

 

Cadmium (Cd)

1.5

4

Chromium (Cr)

80

160

Copper (Cu)

65

110

Lead (Pb)

75

110

Mercury (Hg)

0.5

1

Nickel (Ni)

40

40

Organic-PAHs (mg/kg dry wt.)

 

 

Low Molecular Weight PAHs

550

3160

High Molecular Weight PAHs

1700

9600

Total PCBs

23

180

 

6.8.4          The quality of sediment generated from the Project has been evaluated against the criteria.

Other Hong Kong Legislation and Requirements

6.8.5          Other Hong Kong legislation and requirements relevant to the Study include the Water Pollution Control (General) Regulations and the Water Pollution Control (Sewerage) Regulations as well as Annexes 6 and 14 of the EIAO TM. 

6.8.6          The Technical Memorandum on “Standards for Effluent Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters” (TM-Effluents) issued under Section 21 of the WPCO defines acceptable discharge limits of effluent to different types of receiving waters.  Under the Ordinance, any discharge into the WCZ requires licensing and must comply with the terms and conditions specified in the licence, except for domestic sewage discharged into public foul sewers, and unpolluted water into stormwater drains and river courses.

6.8.7          The Livestock Waste Control Scheme (LWCS) under the Waste Pollution Control Ordinance in 1994 is also to prevent further deterioration in water quality as a result of livestock waste discharged into rivers.

6.8.8          For the Deep Bay WCZ, the standards in Table 8 of the TM-Effluents also apply for discharge into the coastal waters of Deep Bay WCZ.

Waters Under Stressed Conditions

6.8.9          According to Annex 6 of the EIA-TM, a water body is considered stressed if the existing water quality is in breach of or likely to breach the WQOs or that necessary to protect the beneficial uses designated for that particular water body. A water body under stress must adopt the following criteria:

·        Activity must not contribute to, increase or perpetuate stressed conditions;

·        Activity must not retard recovery of the water body if level of pollution from other sources decrease.

6.8.10      The Inner Deep Bay is considered under stressed conditions as water quality data did show non-compliance with the WQOs.

Deep BayNo Net Increase Requirement

6.8.11       It requires that major developments within Deep Bay catchments and all new developments in sensitive areas of the catchments do not increase existing pollution loads by connecting the sewage system of the developments to the public sewer system. If connection of the public sewer system is not feasible, the development should include properly designed sewage treatment facilities to treat the wastewater generated to achieve no net increase of pollution loads to Deep Bay.

 

6.9              Water and Sediment Quality Impact Assessment

Baseline Impact

6.9.1          Without the proposed Project, there are already pollution loadings to the Inner Deep Bay arising from various uses upstream of this receiving water body.

6.9.2          As far as the Subject Site is concerned, there will be uncontrolled overflow of fishpond water in the event of heavy rainstorms leading to non-point discharge into the surrounding water bodies, i.e. the Tai River, San Pui River and ultimately into the Inner Deep Bay.

6.9.3          For actively managed ones, excess water will be pumped out and discharged to the nearby drainage and river channels to regulate water levels from time to time. Both abandoned and actively managed fishponds will have either point or non-point discharge to the nearby rivers during heavy rainstorms despite the difference in the ways they are managed. This will lead to discharge of pond water of higher nutrient levels into the Inner Deep Bay.

6.9.4          By examining the changes of evaporation and rainfall data of these areas with time, the frequency and volume of discharge can be estimated accordingly.

6.9.5          Table 6‑12 shows a summary of annual evaporation and rainfall data.

6.9.6          Figure 6‑12 shows the daily variation of water rainfall during a 10-year period from 1989 to 1998 inclusive.

 

Table 612       Summary of Annual Evaporation and Rainfall (1989 to 1998)

Year

Evaporation (mm)

Rainfall (mm)

1989

1227

771

1990

1144.1

569

1991

1169.6

1009.5

1992

1126.6

1994

1993

1119.4

1581.5

1994

1053.2

2314

1995

1131.8

477

1996

1210.1

1010

1997

1109.3

1994

1998

1158.7

1616.5

 

6.9.7          The volume and frequency of water discharge from water ponds for the baseline scenario (without this Project) has been determined based on time series of rainfall data. The area of the actively managed and abandoned ponds within the Site has been estimated to be about 60 ha and 10 ha respectively.

6.9.8          The daily change in water level of the ponds during the period from 1989 to 1998 has been calculated by taking into account the daily evaporation and rainfall intensity. For actively managed ponds, a minimum water level (about 700mm below the top level) is maintained which resembles that in the real situation or else fish farming will be adversely affected. On the other hand, the calculations have allowed the possibility for the entire abandoned fishponds to dry up theoretically due to the lack of control.

6.9.9          Figure 6‑13 shows the volume of water discharged from the water ponds within the Site before the development determined based on the time series calculation model. Discharge from actively managed fishponds has dominated over 90% of overall volume. An average outflow volume of about 215,000 m3 per year was estimated.

6.9.10      It has been found in the previous section and Table 6‑5 that the water quality of the actively managedand abandoned ponds are comparative. The quality of the discharged volume can therefore be regarded as typical water quality of the fishponds if the Project were not developed, but with comparatively higher SS, BOD5 and nutrient levels.

Possible Impact during the Construction of the Project

6.9.11      It has been proposed, as a broad strategy, to carry out habitat enhancement works within the northern part of the site before construction of the residential development commences in order to mitigate the interim ecological impacts.

6.9.12      These pre-construction works, involving enhancements to ponds in Sectors 1, 2 and 3 (Figure 122) and the construction of the Marshland will be staged to reduce disturbance. Whilst works are being undertaken in Sector 1, the remaining ponds of the site (Sectors 2 and 3 and the future Marsh Habitat Area) will be managed to improve their interim value for birds. Once works are completed in Sectors 1, 2 and 3, the newly enhanced ponds will be managed according to the new long-term regime outlined in Section 14 the Draft Habitat Creation and Management Plan.

6.9.13      The first stage will involve enhancement works in the 13 existing ponds located within Sector 1 (Figure 122). Once these works are complete then work can commence on ponds within Sector 2. On completion of enhancement works in Sectors 1 and 2 works can commence on construction of the Marshland. Once the main structure of the marsh is formed work can commence on Sector 3. Following enhancement fishponds will be managed under the modified regime outlined in the Habitat Creation and Management Plan.

6.9.14      The major construction works involved in pond enhancement relate to the removal of bunds between adjoining ponds. To minimise disturbance to the rest of the site it is proposed that enhancement works are conducted on one pair of ponds at a time. Pond water will be drained to other neighbouring ponds for temporary storage.

6.9.15      The work sequence/ program given in Table 2‑2 show the time periods, start and completion dates for these actions. It is obvious from the program that the construction of the WNR will be carried out during the dry seasons. Draining of pond water would affect a handful of ponds for each Sector, the freeboard available in the neighbouring ponds should be able to accommodate this temporary transfer of pond water without the need for off-site discharge to nearby water bodies.

6.9.16      When the Marshland is worked on, water will have to drain from a number of ponds with a total area of about 14 ha. Together with 4 ha of ponds that have to be filled for the proposed residential development, there will be a total of 18 ha of ponds that have to be emptied.

6.9.17      A simple calculation can demonstrated that this amount of water will be accommodated in the rest of ponds to their north with a total pond area of 62 ha. This will translate into an increase of water depths in these ponds by 30% during the dry seasons. Given an average depth of 2m and 1m of freeboard, the increase would be in the order of 0.6m of water without overflowing.

6.9.18      Other than this issue, surface runoff will be minimal in the construction phase, as most of the works will be carried out during dry season. Moreover, temporary drains, sedimentation basin, sand trap and similar facilities will be provided to ensure that the finally discharge water quality will comply with relevant criteria.

Possible Impact during the Operation of the Project

6.9.19      Foul water will be discharged to the public sewers and should present no problem. The discharge requirement of the Project and the capacity of the existing sewerage system have been evaluated later chapter.

6.9.20      Surface runoff from the proposed residential development and the associated access roads will be drained to sand trap, oil interceptors and similar facilities to remove possible pollutants prior to discharge.

6.9.21      Fishponds in the WNR will be self-contained. During normal operation, under the management of conservation manager, pond water will only be transferred within the WNR and the likelihood of pond water discharge will be minimal. Pond water level will be regulated between 1.2m and 1.9m above the bottom level. Maintenance work will be carried out in a more frequent manner to remove pollutants in sediments so as to reduce the nutrient levels.

6.9.22      It has been estimated that the quality of pond water will be improved through the use of reed bed system in marshland and intrinsically better water quality of fishpond due to better management and less intensive fish culture.

Summary of Impact due to the Project

6.9.23      Through transferring the pond water within the subject site, the need of discharging pond water into the surrounding water bodies during the construction of the Project can be minimized. The operation of the Project shows a positive gain due to reduced outflow and improved water quality and can compensate for any loss in a long run.

6.9.24      Water will be discharged to the two rivers nearby and eventually to the Inner Deep Bay under the supervision of the conservation manager if considered necessary, for instance during or after rainstorm. Pollutants, if exist during discharge, will be diluted and settled before discharging to the marine environment.  There will be little influence to other areas such as the Hong Kong Wetland Park, SSSI and wetland.

6.9.25      In fact, it is believed that the quality of the discharge will be better than that of the baseline situation as well as the upstream water quality.

Possible Cumulative Impact

6.9.26      The construction of Hong Kong Wetland Park has been completed. Moreover, the preliminary environmental review for the Hong Kong Wetland Park has substantiated that no significant water quality impact is anticipated during the operational phase. There will be no cumulative impact contributed from the Hong Kong Wetland Park.

 

6.10          Recommendations of Mitigation Measures

Construction Phase

6.10.1      Control of potential water quality impact arising from the construction works shall be effected based on the following principles:

·        Minimisation of runoff;

·        Prevention or minimisation of the likelihood of the identified pollutants being in contact with rainfall or runoff; and

·        Measures to abate pollutants in the stormwater runoff.

6.10.2      One measure to minimise runoff and pollutant is to have the foundation and WNR construction works carried out during the dry seasons only (i.e. from December to April of the next year). During the dry seasons, the fishponds will have maximum spare capacity to allow temporary storage of pond water during re-profiling of the WNR so as to avoid the discharge of pond water. The Contractor should make best use of existing ponds for the purpose of temporary storage during bunds removal and realignment upon the construction of WNR. In addition, stormwater runoff will be reduced to minimum.

6.10.3      Besides, the Best Management Practices (BMPs) will be implemented in controlling water pollution during the construction phase. The guidelines for handling and disposal of construction site discharges as detailed in EPD’s ProPECC Note PN1/94 “Construction Site Drainage” will be followed. The water pollution control measures that are considered most relevant to this study are listed below which should be implemented by the contractor during the execution of the site formation and road works, where practicable:

Runoff from Construction Site

·        High loading of suspended solids (SS) in construction site runoff shall be prevented through proper site management by the contractor;

·        The boundary of critical work areas shall be surrounded by ditches or embankment.  Accidental release of soil or refuse into the adjoining land should be prevented by the provision of site hoarding or earth bunds, etc. at the site boundary.  These facilities should be constructed in advance of site formation works and roadworks;

·        Consideration should be given to plan construction activities to allow the use of natural topography of the site as a barrier to minimise uncontrolled non-point source discharge of construction site runoff;

·        Temporary ditches, earth bunds should be provided to facilitate directed and controlled discharge of runoff into storm drains via sand/ silt removal facilities such as sand traps, silt traps and sediment retention basin.  Oil and grease removal facilities should also be provided where appropriate, for example, in area near plant workshop/ maintenance areas;

·        Sand and silt removal facilities, channels and manholes should be maintained and the deposited silt and grit should be removed regularly by the contractor, and at the onset of and after each rainstorm to ensure that these facilities area functioning properly;

·        Slope exposure should be minimised where practicable especially during the wet season.  Exposed soil surfaces should be protected from rainfall through covering temporarily exposed slope surfaces or stockpiles with tarpaulin or the like;

·        Access roads should be protected by crushed rock, gravel or other granular materials to minimise discharge of contaminated runoff;

·        Slow down water run-off flowing across exposed soil surfaces;

·        Plant workshop/ maintenance areas should be bunded and constructed on a hard standing.  Sediment traps and oil interceptors should be provided at appropriate locations;

·        Manholes (including newly constructed ones) should be adequately covered or temporarily sealed so as to prevent silt, construction materials or debris from getting into the drainage system;

·        Construction works should be programmed to minimise soil excavation works where practicable during rainy conditions;

·        Chemical stores should be contained (bunded) to prevent any spills from contact with water bodies.  All fuel tanks and/ or storage areas should provided with locks and be sited on hard surface;

·        Chemical waste arising from the site should be properly stored, handled, treated and disposed of in compliance with the requirements stipulated under the Waste Disposal (Chemical Waste) (General) Regulation;

·        Drainage facilities must be adequate for the controlled release of storm flows.

·        Dredged materials requiring temporary storage on-site (for filling of marshland afterwards) should be securely stored and covered, if possible. Dried up mud materials can then be used for marshland formation.

Wastewater from Construction Site

·        Sewage generated from the construction workforce should be contained in chemical toilets before connection to public foul sewer can be provided.  Chemical toilets should be provided at a minimum rate of about 1 per 50 workers. The facility should be serviced and cleaned by a specialist contractor at regular intervals;

·        Foul water from canteens should also be contained by chemical toilets before connection to public foul sewer can be provided;

·        Vehicle wheel washing facilities should be provided at the site exit such that mud, debris, etc. deposited onto the vehicle wheels or body can be washed off before the vehicles are leaving the site area;

·        Section of the road between the wheel washing bay and the public road should be paved with backfill to reduce vehicle tracking of soil and to prevent site run-off from entering public road drains;

·        Bentonite slurries used in diaphragm wall and bore-pile construction, etc. should be reconditioned and reused as far as practicable.  Spent bentonite should be kept in a separate slurry collection system for disposal at a marine spoil grounds subject to obtaining a marine dumping licence from EPD.  If used bentonite slurry is to be disposed of through public drainage system, it should be treated to meet the respective applicable effluent standards for discharges into sewers, storm drains or the receiving waters.

Oils and Solvents

·        Spillage of fuel oils or other polluting fluids should be prevented at source.  It is recommended that all stocks should be stored inside proper containers and sited on sealed areas, preferably surrounded by bunds.

Draining of Fishpond Water

·        Through transferring the pond water within the subject site, the need of discharging pond water into the surrounding water bodies during the construction of the Project can be minimized.

·        Any draining of fishpond water should be handled with prudence. Through the implemenation of EM&A programme and supervision of the conservation manager, the water quality should be checked to ensure that relevant water quality criteria can be complied with and the water quality of the sensitive receivers nearby as identified in the Section 6.3 of this chapter would not be further deteriorated.

·        Sedimentation tanks should be set up at the construction site so that water to be discharged can be retained for sedimentation if any discharging activity is considered necessary.

6.10.4      Given the proposition of all the effective mitigation measures above, an environmental monitoring and audit programme should be devised in order to ensure the proper implementation of the recommended measures and provide a proactive system to rectify any problem at once before the situation gets worse.

Operational Phase

Residential Development and Access Road

6.10.5      All domestic sewage generated will be discharged to the public sewerage. The drainage system will be designed to avoid any case of flooding based on the 1 in 50 years scenario with provision of treatment facilities including sand traps and oil interceptors. Temporary buffer containers should be provided to retain wastewater in case emergency discharge from sewage pump houses and sewer bursting discharge occur as a contingency measure.

6.10.6      Regular cleaning and sweeping of the access road and other paved areas are suggested so as to minimise exposure of pollutants to stormwater. Stormwater gullies and ditches provided along the access road and among the residential development will be regularly inspected.

6.10.7      Planter strips are provided along the access road and around the residential development where practicable. In the event of emergency (e.g. car accident) where there is a major spillage of oil, chemical or fuel, dispersants or fire fighting foam, etc., a system of contaminant bunding is recommended as far as practicable.

Wetland Nature Reserve

6.10.8      Best management practice will be adopted for the maintenance of the wetland and fishpond areas. Regular maintenance of fishponds will be exercised to remove excessive nutrients. Fish species will be carefully selected and the quantity will be controlled to avoid excessive fish farming as usually happened before the development of the Project.

6.10.9      A Wetland Nature Reserve management plan has been devised. No application of herbicides, or pesticides is considered necessary. Re-circulation pumping system will be provided for circulation of water between ponds and in turn to reduce the likelihood of overflowing of ponds due to even distribution of water volume.

6.10.10   Fishponds in the WNR will be self-contained. During normal operation, under the management of conservation manager, pond water will only be transferred within the WNR and the likelihood of pond water discharge will be minimal.

6.10.11   The temporary storage of water at the storage pond can allow sedimentation and removal of pollutants before discharge. It is particularly useful prior to wet season as cleaner water will be discharged to allow spare capacity for rainstorm.

6.10.12   The way to avoid overflow by intentional discharge upon the water quality, for example, is also recommended. Reed bed and alike can be provided in the marshland area to reduce nutrient discharge.

 

6.11          Conclusion

6.11.1      It is considered that the provision of the best practicable measures recommended above during the construction and operational phases should be effective to reduce the water quality impacts on receiving water bodies.  Increase in pollutant load of Tai River, Shan Pui River and Deep Bay WCZ due to the discharges of runoff from the Subject Site including that arising from the residential development, the access road and the Wetland Nature Reserve is considered insignificant and alteration of the overall water quality is not anticipated.

6.11.2      There could however be non-point runoff during a heavy storm when all fishponds in the area overflow to the nearby water bodies. This is considered a natural process and occurred in the past even the Project was not developed. In such case, the diluted pond water that gets into the Inner Deep Bay should unlikely to present a pollution source exceeding the assimilation capacity of the water body as the water quality would meet the WQOs.

6.11.3      Given the remoteness of the Hong Kong Wetland Park, the SSSIs and wetland along the coast, they should unlikely be impacted during both construction and operation of the Project.


 


7.                  Potential Problem of Biogas

7.1              Introduction

7.1.1          This section presents an assessment on the potential problem of biogas in accordance with the requirements given in Clause 3.5.3 of the EIA Study Brief. 

7.1.2          To create solid ground for the proposed residential portion, ponds at the southwestern boundary of the Site will have to be reclaimed. Top soils will be dredged from each fishpond and filled with fill materials (e.g. marine sand or recycled C&D materials). The dredged topsoil will be re-used on-site for the establishment of WNR.

7.1.3          Biogas comprises mainly of methane and carbon dioxide and is generated as a result of anaerobic degradation of organic matters buried under reclaimed land. The potential risk would be migration of methane and carbon dioxide, which are flammable and asphyxiating.

 

7.2              Assessment Methodology

7.2.1          As it is impossible to measure the rates of biogas emission at this stage from the organic sediment within the reclaimed area, the biogas generation has therefore been estimated from the proposed reclaimed areas based on a stoichiometric analysis.

7.2.2          The Total Organic Carbon (TOC) and sediment oxygen demand (SOD) can be used to estimate the methane generating potential of the sediment at the reclaimed areas.

7.2.3          SOD values are therefore used to calculate the total biodegradable organic carbons in the sediment. SOD20days has been analysed to estimate the “ultimate SOD” for estimation of biogas generation.

 

7.3              Field Sampling and Laboratory Analysis

7.3.1          Ponds dredging and filling will be concentrated at the southwestern boundary of the Site where the residential development is planned.

7.3.2          To enable a biogas assessment be carried out, sediments were sampled at fishponds within the proposed residential area where some pond mud could be to be left in place. Sediment samples were collected at Pond no.19 and no. 62 as shown in Figure 7‑1 by a HOKLAS accredited laboratory in May 2002 for analysis of Total Organic Carbon (TOC), Sediment Oxygen Demand (SOD20days) and moisture content. 

7.3.3          As it is envisaged that the first 0.3m of topsoil at the proposed residential area will be dredged before any filling activities, sediments were therefore sampled at depths of 0.5m and 1m below pond water level to quantify the potential biogas generation problem through appreciation of the TOC and SOD levels at the surface layer.

7.3.4          Each sample weighs about 0.5g. The results of analysis are presented in Table 71 below. 

 

Table 71         Sampling Locations and Levels of Total Organic Carbon (TOC) and Sediment Oxygen Demand (SOD)

Location

Sample Depth (m)

Moisture
(% w/w)

TOC
(% dry wt)

SOD 20days
(mg/kg)

Pond 19-1

1.0

21.6

0.69

2644

Pond 19-2

1.0

34.9

0.69

3372

Pond 19-3

1.0

24.4

0.34

2826

Pond 19-4

0.5

32

0.76

3468

Pond 19-5

0.5

31.2

0.58

3021

Pond 19-6

0.5

21.7

0.46

1144

Pond 62-1

1.0

26.2

0.95

2955

Pond 62-2

1.0

34.4

1.13

4861

Pond 62-3

1.0

25.2

0.71

1862

Pond 62-4

0.5

44.3

1.11

1912

Pond 62-5

0.5

38.9

0.83

1197

Pond 62-6

0.5

35

1.06

2317

Average

-

30.8

0.78

2632

 

7.4              Risk Assessment Criterion

7.4.1          Though the issue of methane risk is not a requirement in the TM on EIA Process and there is no primary legislation in Hong Kong covering hazards to developments caused by methane gas, there is however certain relevant guidelines that can be referenced to assess its safe rates.

7.4.2          The process adopted for estimation of safe rates of biogas emission for filled land over sediment left in-situ is similar to estimating safe emission rates of landfill gas when deciding whether or not an old landfill site can be regarded as being sufficiently stabilised without poses any danger. The assessment of a safe rate of landfill gas emission is necessary for determining when a site no longer needs to be monitored and when it can be used for unrestricted development. The assumption made is that any type of building could be safely constructed on top of the landfill and therefore required the adoption of a universally applicable safe rate of methane emission.

EPD’s Landfill Gas Hazard Guidance Note

7.4.3          There is no primary legislation in Hong Kong covering hazards to development caused by landfill gas or methane gas generated from organic deposits. The most relevant guidance is the guideline, “Landfill Gas Hazard Guidance Note” issued by the Environmental Protection Department (EPD). The guidance note recommends that methane gas should be monitored periodically in all excavations, manholes and chambers and any confined spaces during construction. No works and no entry to the excavation areas or confined spaces should be allowed and the personnel on-site should be evacuated if the methane concentration measured during the monitoring exceeds 20% lower explosive limit (LEL) (or 1.0% gas).

Maximum “safe” rate of gas emission based on the UK Department of the Environment’s Waste Management Paper No. 26A: Landfill Completion

7.4.4          The UK Department of the Environment Waste Management Paper No. 26A on Landfill Completion recommends a maximum acceptable rate of methane ingress into a building constructed on a disused landfill site. It states that methane emission rates from monitoring boreholes should fall consistently below 0.015 m3 per hour. This criterion was developed to determine when monitoring of landfill gas emissions at a restored landfill can be discontinued and when the site can be used for unrestricted development. It is assumed that the most sensitive ‘at risk’ room or void has a height of 2.5 m and a very low rate of ventilation of 1 air change per week. 

7.4.5          For residential development at the built area of Fung Lok Wai, it is considered more conservative to adopt a height of 1 m to represent the void space (to allow for smaller void spaces such as utilities or services ducts) and a ventilation rate of 1 air change per day (this is in line with rates of natural ventilation for closed rooms). The maximum safe rate of methane ingress was then defined as that at which it would take 1 day for the methane concentration to reach 1% (v/v).  This is 20% of the lower explosive limit (LEL) for methane and provides a safety factor of 5 to allow for variations in, for instance, rates of gas emission across the area of the site or over time compared with those measured at particular places and during the evaluation period.

7.4.6          The corresponding daily maximum “safe” rate of methane gas emission per unit area is therefore calculated as follows:

  1.0 m x 0.01 d-1 (equivalent to m3 CH4 m-2d-1)

= 0.01 m3 CH4m-2d-1

= 10 litres CH4m-2 d-1

7.4.7          The criterion provides a reasonable general guide for determining whether the rates of methane emission pose an unacceptable risk to unrestricted development on a potential site.

 

7.5              Estimation of potential Gas Emissions

7.5.1          The generation rate of biogas depends on a number of parameters including concentrations and biodegradability of the organic matters in the sediment, age of the reclamation, redox potential, temperature, moisture content, presence of toxic matters which may inhibit biological activities. These parameters may vary at different depths and locations and their interactions are complex and difficult to predict.  For the purpose of this preliminary assessment, the potential methane risk will be assessed based on the theoretical biogas production rate.

7.5.2          As learnt from several anaerobic degradation projects, the formation of biogas under anaerobic conditions can be described as a first order degradation process.  This process is characterised by high gas generation rates at the early stage of the process, followed by an exponential decrease over the course of time. Although it is difficult to predict the extent of anaerobic conditions, the generation of biogas can be estimated theoretically based on the available data on TOC and the SOD.

7.5.3          At the residential development area, the depth of topsoil dredged from each fishpond which are going to be filled is about 0.3m. Consequently, the methane generation potential of the sediment (fish pond mud) to be left in place will be estimated based on the sediment layer in the depth of about 0.3m to 2m. As such, the estimated quantity of sediment at the built area is: -

Volume of sediment left in-situ at built area = 41,000m2 x (2 - 0.3) m = 69,700m3

7.5.4          SOD represents only a fraction of the organic carbon present in the sediment. The total methane generation potential calculated based on SOD results is usually much lower than that calculated based on the TOC results because TOC is a measure of the total organic carbon whereas some of it may not be biodegradable. SOD results, which measure the biodegradable portion of the organic matters in the sediment, provide a more realistic assessment comparing with those estimated using TOC results.

7.5.5          However, as a prudent approach, the estimation of methane generation potential for the proposed development would be based on both TOC and SOD in the Study. It is because TOC results represent the total organic content in the sediment, which in turn represent the worst-case scenario of biogas generation, i.e. the maximum amount of biogas that could be generated. On the other hand, SOD results may underestimate the biogas generation potential due to limited test time. As such, SOD20days is analysed instead of SOD5days to estimate the “ultimate SOD”.

Estimation of Methane Generation Potential Based on TOC

7.5.6          It is assumed that 50% of the gas produced from anaerobic degradation of organic matter of the sediment is methane and the remainder is carbon dioxide. The degradation process can be represented by the following equation:

2 C6H12O6  à 6 CH4 + 6 CO2

7.5.7          On this basis, the mass of the methane generated from unit mass of TOC can be calculated as follows:

12 C               à        6 CH4 + 6 CO2

                                                                                    12 x 12 = 144     6 x 16 = 96

7.5.8          The theoretical mass of methane generated will equal to 0.67 times of the mass of TOC in the sediment.

7.5.9          The half-lives of anaerobic degradation range from ½ to 5 years.  In considering that over 90% of the organic matter would have been degraded after the first two years of development construction based on a half-life of ½ year, this higher flux rate would not be significant for the future development.  Besides, the methane flux (with a half-life of ½ year) would also be reduced to a rate much lower than that of the peak annual methane potential based on a half-life of 5 years after the first two years of development construction.

7.5.10      Having said that, the decomposition rate of biodegradable organic matter would be higher for a shorter half-life cycle of decay.  So, in order to cover a reasonable range of half-life cycles, the half-life cycles of 2 years and 5 years were considered for estimation of total theoretical methane generation potential and daily methane flux from the built area of the proposed development.

Estimation of Methane Generation Potential Based on SOD

7.5.11      The amount of methane gas produced per kg of SOD can be estimated as follows:

7.5.12      Assume that the starting compound is glucose (C6H12O6), the conversation of glucose to carbon dioxide and methane under anaerobic conditions can be represented by the following balanced equation:

C6H12O6  à 3 CO2 + 3 CH4

180 g    132 g   48 g

 

7.5.13      It should be noted that although the glucose has been converted to carbon dioxide and methane, the methane generation potential might be estimated by the oxygen requirement for complete conversion of the glucose to carbon dioxide and water under aerobic conditions.

7.5.14      The amount of methane formed per kg of SOD can be represented in the following balanced equation for the oxidation of glucose to carbon dioxide and water.

 

C6H12O6 + 6 O2 à 6 CO2 + 6 H2O

180 g      192 g

 

7.5.15      The SOD of glucose is (192/180) kg, and 1 kg of glucose yields (48/180) kg of methane, so that the ratio of the amount of methane produced per kg of SOD is:

 

       (kg CH4/kg SOD) = {(48/180)/(192/180)} = 0.25

 

7.5.16      Therefore, for each kg of SOD, 0.25 kg of methane will be formed.

7.5.17      The volume equivalent of the 0.25 kg methane produced from the equivalent of 1 kg of SOD is:

 

Vol CH4 = (0.25 kg) * (103 g kg-1) * (1 mol/16 g) * (22.4 l mol-1) * (10-3 m3 l-1)

 

                   = 0.35 m3 CH4 (at standard conditions of temperature and pressure)

    Therefore, 0.35 m3 of methane will be generated per kg of SOD converted.

7.5.18      Regular interval measurement of dissolved oxygen up to 20 days would be done in the SOD test as such data can be used to estimate the “ultimate SOD” which in turn is useful for estimation of biogas generation. SOD will also include the nitrogenous oxygen demand (i.e. the oxidation of nitrogen and ammonia), but in the estimation of the methane generation potential it is assumed that the oxygen demand is entirely carbonaceous demand. This represents a conservative approach and the actual methane generation potential is expected to be lower.

7.5.19      With the average of SOD20days levels of the sediment samples analysed, the theoretical methane generation potential (in m3 CH4 /kg dry weight of sediment) will be:

=  Average SOD20days (in mg SOD kg-1 dry weight of sediment) x 10-6 kg mg-1

         x 0.35 m3CH4/kg SOD

7.5.20      The total theoretical methane generation potential (m3 CH4) can be calculated with the following information:

·        Volume of Sediment to be left in-situ;

·        Assumed density of sediment (i.e. 1500 kg m-3);

·        Average dry matter of the filled area;

·        Mass of dry matter;

·        Total dry matter of sediment;

·        SOD20days in mg O2 kg-1 dry weight of sediment;

·        Total SOD in sediment

7.5.21      For the SOD level in the filled pond is estimated to be 2,632 mg/kg, the total methane potential will be 658 mg/kg. On the other hand, under the assumption on sediment TOC of 0.78% of dry matter and half is converted to methane, methane potential would be 5,226mg/kg dry matter, which was obtained from the methane generation potential divided by the mass of dry matter. It implies that only 13% of TOC will be biodegraded. Therefore, use of TOC to estimate methane potential provides an overestimate of that potential. In addition, as some organic which are degradable aerobically (which contribute to SOD) will not be degraded in anaerobic conditions. As such, basing potential methane yield on SOD itself already has the possibility on providing an over-estimate of methane potential.

Calculation of potential gas emissions

7.5.22      To be conservative, the peak annual methane potential based on TOC with half-life cycle of 2 years and 5 years are therefore adopted for the calculations of potential methane gas emission. The methane concentration at the surface layer of the built area of Fung Lok Wai is estimated as illustrated in Table 72 below.  Upon completion of pond filling, construction activities including compaction, site investigation, and foundation construction will follow. Superstructure construction will only commence after completion of these activities at about 1.5 years after completion of pond filling.  Confined space, if any, will only exist after the commencement of the superstructure construction.  Peak methane generation potential is therefore estimated for the period after commencement of the superstructure construction at about 1.5 years after completion of pond filling.  The methane concentration and flux calculated based on this peak methane generation potential are then compared with the guideline value (1%v/v) as stipulated in EPD’s Landfill Gas Hazard Guidance Note and the UK methane hazard assessment criteria (10 L/m2/d).

 

Table 72         Calculation of Methane Flux from the Fung Lok Wai Development

 

Half-life cycle of 2 years

Half-life cycle of 5 years

Remarks

Area (m2)

41000

41000

Total pond filling area

Depth of sediment left in-situ

1.7

1.7

0.3 to 2m below ground (see S7.5.3)

Volume of sediment to be left
in-situ (m3)

69700

69700

= Area x Depth

Assumed density of sediment (kgm-3)

1500

1500

Assumed value

Moisture of sediment (% w/w)

30.8

30.8

Average value from Table 7-1

Dry matter (% w/w)

69.2

69.2

= 100% - moisture content

Mass of dry matter (kgm-3)

1038

1038

= Density of sediment x dry matter %

TOC (%)

0.78

0.78

Average value from Table 7-1

Mass of TOC (kgm-3)

8.10

8.10

= Mass of dry matter x TOC%

CH4 generation potential (kgm-3)

5.42

5.42

=0.67 x Mass of TOC (see S7.5.8)

Half life, t1/2 (yr)

2

5

Assumed value

Degradation constant, k

0.3466

0.1386

First-order degradation process:
ln[At]=-kt+ln[A0] and t1/2=ln[2]/k
where
A0 = total CH4 generation at t=0;
At = total CH4 generation at t=t;
k = degradation constant = ln(2)/t1/2;
t = time after commencement of degradation process;
t1/2 = half life in year

Total CH4 generation (kg) at year 0

(at completion of pond filling)

378094

378094

= CH4 generation potential x Volume of sediment = A0

Total CH4 generation (kg) at year 1.5

(at commencement of superstructure construction)

224816

307108

=e[(-k x 1.5) + ln(A0)] = A1.5

Total CH4 generation (kg) at year 2.5

(at 1 year after commencement of superstructure construction)

158969

267353

=e[(-k x 2.5) + ln(A0)] = A2.5

Total CH4 generation (kg) at year 3.5

(at 2 years after commencement of superstructure construction)

112408

232744

=e[(-k x 3.5) + ln(A0)] = A3.5

Peak annual CH4 potential after commencement of superstructure construction (kg)

65847

39755

= A1.5 - A2.5;
the CH4 generation rate is decreasing as indicated by the comparison that
(A2.5 - A3.5) < (A1.5 - A2.5)

Total potential CH4 flux (kgm-2 per year)

1.6060

0.9696

= Peak annual CH4 potential / Area

Total potential CH4 flux (L m-2 per year)

2248.4360

1357.4845

Unit conversion (=kgm-2 x 1000 / 16 x 22.4)

Total potential CH4 flux (L m-2 per day)
(assuming 13% of TOC biodegradable)

0.8008

0.4835

=L m-2 per year / 365 x 13%

Total potential CH4 flux (L m-2 per day)
(assuming 100% of TOC biodegradable)

6.1601

3.7191

=L m-2 per year / 365 x 100%

Potential CH4 concentration (% v/v) at the surface layer
(assuming 13% of TOC biodegradable)

0.0801

0.0483

For confined space as described in S7.4.5
= (L m-2 per day x 1m2) / (1000 L per day at 1 air change per day) x 100%

Potential CH4 concentration (% v/v) at the surface layer
(assuming 100% of TOC biodegradable)

0.6160

0.3719

For confined space as described in S7.4.5
= (L m-2 per day x 1m2) / (1000 L per day at 1 air change per day) x 100%

 

7.6              Evaluation of Significance of Potential Gas Emissions

7.6.1          Assuming 13% of TOC biodegradable, the predicted methane concentration based on a half-life cycle of 2 years and 5 years are 0.080%v/v and 0.048%v/v respectively. The concentrations are considered insignificant when comparing with the guideline value of 1%v/v stipulated in EPD’s Landfill Gas Hazard Guidance Note.

7.6.2          Considering the highly unlikely event of assuming 100% TOC biodegradable, the predicted methane concentration based on a half-life cycle of 2 years and 5 years are 0.62%v/v and 0.37%v/v respectively and are still within the guideline value of 1%v/v.

7.6.3          When taking the maximum “safe” rate of gas emission derived from the Department of the Environment (1993), Landfill Completion. Waste Management Paper No. 26A (10 L m-2 per day) as the standard, with half-life cycle of 2 years and 5 years, assuming 13% of TOC biodegradable, the predicted methane emission levels (0.80 and 0.48 L m-2 per day respectively) are only 8.0% and 4.8% of the guideline value respectively.  The provision of safety factor is up to about 12.

7.6.4          Even under the conservative estimation, the predicted methane emission based on half-life cycle of 2 years and 5 years, assumption of 100% TOC biodegradable, are 6.16 and 3.72 L m-2 per day respectively.  They are still found to be within the maximum “safe” rate.

7.6.5          It can be concluded that the predicted methane concentrations are well within the relevant risk assessment criterion and the leaving the pond mud in place is unlikely to generate any potential biogas problem.

 

7.7              Monitoring, Mitigation and Precautionary Measures

7.7.1          As it is unlikely that there would be significant potential biogas problem, the following generic precautionary measures are therefore recommended. No further monitoring and mitigation measures are considered necessary.

Ventilation within “at risk” rooms

7.7.2          Rooms located at the underground, such as utility (services) voids, transformer rooms and refuse collection rooms, if any, may be susceptible to ingress of any biogas generated on-site.

7.7.3          As an additional measure for the protection of these rooms, mechanical ventilation may be provided to ensure that if any gas enters the room it is dispersed and cannot accumulate to a dangerous level. For particularly sensitive rooms, such as below ground confined spaces which contain sources of ignition, forced ventilation may be used in addition to the use of a low permeability membrane.

7.7.4          The most sensitive “at risk” features of the proposed development is identified to be the car park located at the basement area. The basement car park of the proposed development may be susceptible to ingress and accumulation of biogas. It is therefore be necessary to ensure the car park has adequate ventilation to prevent the accumulation of any methane gas emissions to dangerous concentrations.

7.7.5          The basement car park ventilation system should be designed to ensure that the car park air quality guidelines given in ProPECC PN 2/96 Control of Air Pollution in Car Parks are achieved. The minimum ventilation rate for a basement car park is 5 to 6 air changes per hour in order to comply with the EPD requirement on carbon monoxide concentrations within car parks. This ventilation rate is considered adequate to disperse any biogas that might get into the car park.

7.7.6          Several ventilation systems should be installed and evenly distributed within the basement car park. It is also recommended that a back-up power supply shall be provided for the ventilation system, so that certain designated exhaust systems will still operate during power failure. Under normal circumstances, power failure should be rectified within hours.

Precautions During Construction

7.7.7          Precautions may be required to ensure that there is no risk due to the accumulation of gas within any temporary structures, such as site offices, during construction works on the filling area. It may be necessary, for example, to raise such structures slightly off the ground so that any gas emitted from the ground beneath the structure may disperse to atmosphere rather than entering the structure. A minimum clear separation distance of 500mm, as measured from the highest point on the ground surface to the underside of the lowest floor joist, is recommended in the Landfill Gas Hazard Assessment Guidance Note, EPD (1997).

Precautions Prior to Entry of Below Ground Services

7.7.8          Following construction, accumulation of gas within any below ground services can pose a risk to the staff of the utility companies. As a good working practice, prior to entry into any confined space within the filled area (such as manholes, underground culverts and utility casings), the gas atmosphere within the confined space should be monitored for oxygen, methane and carbon dioxide. Personnel should be made aware of the potential dangers and advised to take appropriate precautions.

Precautions Prior to Entry of Below Ground Services

7.7.9          The working practices should follow the Landfill Gas Hazard Assessment Guidance Note, EPD (1997) guidelines as follows:

·        Any chamber, manhole or culvert that is large enough to permit access to personnel should be subject to entry safety procedures. Such work in confined spaces is controlled by the Factories and Industrial Undertakings (Confined Spaces) Regulations of the Factories and Industrial Undertakings Ordinance. Following the Safety Guide to Working in Confined Spaces ensures compliance the above regulations.

·        The entry or access point should be clearly marked with a warning notice (in English and Chinese) which states that there is the possibility of flammable and asphyxiating gases accumulated within.

·        The warning notice should also give the telephone number of an appropriate competent person who can advise on the safety precautions to be followed before entry and during occupation of the manhole.

·        Personnel should be made aware of the dangers of entering confined spaces potentially containing hazardous gases and, where appropriate, should be trained in the use of gas detection equipment.

·        Prior to entry, the atmosphere within the chamber should be checked for oxygen, methane and carbon dioxide concentration. The chamber may then only be entered if oxygen is greater than 18% by volume, methane is less than 10% of the Lower Explosive Limit (LEL), which is equivalent to 0.5% by volume (approximately), and carbon dioxide is less than 0.5% by volume.

·        If either carbon dioxide or methane is higher, or oxygen lower than the values given above, then entry to the chamber should be prohibited and expert advice sought.

·        Even if conditions are safe for entry, no worker should be permitted to enter the chamber without having another worker present at the surface. The worker who enters the chamber should wear an appropriate safety/ recovery harness and, preferably, should carry a portable methane, carbon dioxide and oxygen meter. 

7.7.10      In general, sufficient approved resuscitation equipment, breathing apparatus and safety torches should be available when work is being undertaken in confined spaces. Persons involved in or supervising such work should be trained and practised in the use of such equipment. A permit-to-work system for entry into confined spaces should be developed by an appropriately qualified person and consistently employed.

 

7.8              Impacts Summary and Conclusion

7.8.1          As the residential footprint is planned to build on the existing fishpond area, under anaerobic conditions, the pond mud left in-situ may generate potential biogas risk.

7.8.2          With the TOC and SOD contents of the pond mud in-situ sampled, the potential methane flux from the Development based on half-life cycle of 2 years and 5 years are estimated. Even under the extreme worse case scenario (100% of TOC is biodegradable), the results are well below with the guideline value stipulated in EPD’s Landfill Gas Hazard Guidance Note and the maximum “safe” rate of gas emission derived from the Department of the Environment (1993), Landfill Completion. Waste Management Paper No. 26A.

7.8.3          Generic gas precautionary measures for the below ground structures of Development and precaution measures to be taken prior to entry into any below ground services or confined space within the Development are recommended.

7.8.4          With the incorporation and implementation of the recommended precautionary measures. The potential biogas hazard posed to the Development is considered to be minimal.


 


8.                  Sewerage and Sewage Treatment Implications

8.1              Introduction

8.1.1          This section addresses the sewerage and sewage treatment implications of the Project in accordance with the criteria and guidelines given in Section 6.5 in Annex 14 of the TM.

8.1.2          The Project is located in an area that is currently not sewered.  As per Section 6.5 in the Annex 14 of the TM, the collection of wastewater discharged to a public sewer is a preferred approach. A new sewerage system is therefore necessary for disposal of sewage generated by the Project during its operational phase, particularly when the Project is located within the boundary of Wetland Conservation Area and is close to the Deep Bay.

8.1.3          Connection with existing sewerage for centralised treatment is in line with the Deep Bay “No Net Increase Requirement” when compared to the option of establishing a separate on-site sewage treatment plant.  The feasibility, possible alignment, potential impacts, design and requirements of the proposed sewerage system are evaluated in this chapter.

 

8.2              Existing Sewage Disposal and Treatment Facilities

Yuen Long Sewage Treatment Works (YL STW)

8.2.1          The Project is not located in any existing or committed sewered area. The Yuen Long Sewage Treatment Works (YLSTW) is about 200m east of the Project and is close to the Yuen Long Industrial Estate (YLIE).

8.2.2          The YLSTW is a conventional activated sludge plant with removal of ammonia nitrogen. It provides primary and secondary treatment with effluent discharged into the Shan Pui River at its downstream end and eventually to Deep Bay. The present capacity of the plant is 70,000 m3/day DWF with a 4 DWF allowance for preliminary and primary treatment and 3 DWF for secondary treatment.

8.2.3          The current DSD design procedures give an equivalent capacity of 105,000 m3/day DWF for preliminary/ primary based on treatment of all incoming flows and a peak factor with some allowance for moderate storm water inflow of 2.67 DWF.

Ha Tsuen Pumping Station

8.2.4          The Ha Tsuen Pumping Station transfers all received flows to the San Wai Sewage Treatment Works. The Stage 1 modification to the pumping station has been completed to increase the capacity to 164,000 m3/day DWF. Provision of land has been allowed for the Stage 2 expansion to attain 1.5 times the existing capacity.

San Wai Sewage Treatment Works (SWSTW)

8.2.5          The San Wai Sewage Treatment Works (SWSTW) is located at about 5 km southwest of the Project site. Stage 1 of the SWSTW is designed for DWF of 164,000 m3/day with peak flow of 410,000m3/day @2.5 DWF. The Government plans to upgrade the treatment level of SWSTW from preliminary to Chemically Enhanced Primary Treatment plus disinfection with further expansion of capacity to 246,000 m3/d.

8.2.6          Sewage is fed from the Ha Tsuen Pumping Station, which serves the sub-regions in its locality. The SWSTW provides preliminary treatment using screens and grit removal. Treated effluent is discharged via a tunnel into the Urmston Road in the Pearl River Estuary.

8.2.7          The effluent tunnel which transfer treated effluent from SWSTW to Urmston Road is 3.0 m in diameter and 8.9 km long. Transfer is by gravity. The average flow of the tunnel is designed to be 400,000 m3/day. While the effluent outfall is 1.8 m in diameter and 2.6 km long discharging into the centre of the Urmston Road tidal channel in 22 metres of water. The outfall is designed for an average flow of 294,000 m3/day. Allowance has been made for a second outfall if required. The locations of the existing sewerage systems near the Subject Site are illustrated in Figure 8‑1.

 

8.3              Planned Sewage Disposal and Treatment Facilities in the Area

Tin Wah Road Sewage Pumping Station (TWRSPS)

8.3.1          The existing TWRSPS is constructed to serve the Tin Shui Wai Reserve Zone Development (TSWRZ). It is connected to the Ha Tsuen Pumping Station with a proposed twin rising main. The pumping station has an ultimate capacity for a peak flow of 1,284 l/s.

Upgrading and Expansion of San Wai Sewage Treatment Works and Expansion of Ha Tsuen Pumping Station

8.3.2          The “Upgrading and Expansion of San Wai Sewage Treatment Works and Expansion of Ha Tsuen Pumping Station” is a Designated Project under EIAO. The EIA report has been approved without conditions on 12 May 2003.

8.3.3          According to the latest design of DSD, the total sewage flow delivered by the Ha Tsuen Pumping Station will be some 231,000 m3/day DWF by 2016. After the Stage 2 expansion, there will be a spare capacity of 15,000 m3/day DWF by 2016.

YLSTW Effluent Export or Upgrading of YLSTW to Tertiary Treatment

8.3.4          As per the recommendations in the Review of Yuen Long and Kam Tin Sewerage and Sewage Treatment Requirements completed by EPD in 1999 (the Review), the YLSTW will maintain its secondary treatment. There will be a pumping station and rising mains to transfer effluent from the YLSTW to the disinfection system and effluent tunnel at San Wai for discharge together with the effluent from San Wai Sewage Treatment Works. It is estimated to have about 50,000 m3/d secondary effluent to be discharged via the effluent pipelines.

8.3.5          The YLSTW effluent pipelines form part of the “Yuen Long and Kam Tin Sewerage and Sewage Disposal (YLKTSSD) Stage 2” elements. It is named as Package 2A-1T in the YLKTSSD Stage 2 Project and is a Designated Project under EIAO. A Project Profile was submitted by the project proponent, Drainage Services Department (DSD), on 9 August 200 and a Study Brief (No. PP-138/2001) was issued by the Director of Environmental Protection on 21 September 2001. EIA report was prepared by DSD in accordance with the Study Brief and approved without condition on 17 June 2004.

8.3.6          Apart from the above effluent export scheme, the Government is exploring an alternative scheme for upgrading of YLSTW to tertriary treatment for the design flow of 50,000 m3/d and local disposal. Under such scheming, no expansion of the existing treatment works capacities of 70,000 m3/d is needed.

8.3.7          In the information provided in the Study Brief and Project Profile of the YLTSSD Stage 2, the items of Package 2A-1T include:

·        OP1-Pumping Station in the north of YLSTW

·        OS1- Twin rising mains from item OP1 to Tin Tze Road in Tin Shui Wai; with alternative items: -

o        AP1- Pumping Station in the north of YLSTW

o        AS1- Twin rising mains in the northwestern side of YLSTW.

8.3.8          The locations of Package 2A-1T and its alternative elements are shown in Figure 8‑2.

 

8.4              Planned Population and Sewerage Flows Projections

8.4.1          The Project has a design population of about 8,490. Other schedules of the development are tabulated in Table 8‑1 below.

Table 81         Development Schedule the Project

Total Site Area (approximate)

800,000 m2

Proposed Plot Ratio

0.185

Proposed Total GFA

148,000 m2

Design Population

8,490

No. of Flats

Not more than 2,860

8.4.2          As per the recommendations in the Sewerage Manual published by the Drainage Services Department in 1995, the volume of sewage that will be generated from the proposed development has been estimated at 3,153 m3/day (ADWF) based on a Global Unit Flow Factor of 0.370 and a maximum design population of 8,490. The sewage will be of domestic nature and no industrial wastewater discharges are expected.

 

8.5              Proposed Development, Sewerage Options and Projection

8.5.1          With reference to the recommendation and projection in the Review, different sewage disposal strategies as shown in Figure 8‑4 are proposed for the Project: -

·        Strategy A (Eastern Option) –        construct a new sewer to connect with the YLSTW, laid under Fuk Shun Street and other local roads, and joining with the existing sewerage;

·        Strategy B (Western Option) – construct a new sewer to connect with the existing Tin Wah Road Sewage Pumping Station. The sewage will then be conveyed to the Ha Tsuen Pumping Station and eventually to the San Wai STW.

8.5.2          For Strategy A, two alignment options are identified. The first option (herineafter referred to as Strategy A1) is to construct a new 375mm diameter sewer to connect with the YLSTW via Fuk Shun Street and local road next to Leon Court. The sewer will be about 1,356m long. Another option is to follow the same upstream routing of the proposed new sewerage for the above Strategy A1 from the subject site to Fuk Shun Street but connected to existing sewerage in Fuk Hi Street that would convey the sewage to YLSTW via the existing sewerage in Wang Lee Street and Wang Lok Street (hereinafter referred to as Strategy A2). The alignment of the two alternatives of Strategy A (i.e. Strategy A1 and A2) are presented in Figure 8‑4.

8.5.3          For Strategy B, it is proposed to provide a new 375 mm diameter sewer with approximate length of 940m connecting the sewerage of the subject site and the existing communal sewerage at junction of Tin Wah Road and Tin Tsz Road.  Together with the other sewage collected from Tin Shui Wai Reserve Zone and the Development Zone, the sewage from the subject site will be delivered to the existing TWRSPS, and then via Ha Tsuen Pumping Station to San Wai Sewage Treatment Works.

8.5.4          In view of the low-lying condition of the development site, discharging sewage by gravity flow to nearby pumping station or STW will not be feasible. Therefore the Project will be provided with a sewage tank and a pump house for either sewage disposal strategies outlined above. Details of the requirements of the proposed sewerage system including the sewage pump house are presented in the Section 8.9.

 

8.6              Adequacy of Existing and Planned Sewerage and Treatment Facilities to accept flows

Strategy A (Eastern Option)

8.6.1          The estimated sewage inflow to YLSTW may exceed the existing 70,000 m3/d by year 2011 under early planning. However, it will depend on the actual development in the catchment and the sewage flow build-up due to the Yuen Long Industrial Estate. The information provided by DSD illustrating the projected total flow to YLSTW from 2000 to 2016 is presented in Figure 8‑5.

8.6.2          Actually, only about 15,000 m3/d DWF of the raw sewage is discharged to YLSTW as at 2007. That is much less than the original estimated ADWF of about 43,000 m3/d as indicated in the above Figure 8-5. Such a phenomenon is caused by a sharp decline of wastewater generating industry over the last few years. Industrial wastewater flows from Yuen Long Industrial Estate (YLIE), which flows to the YLSTW will probably remain at their current magnitude or even decline.

8.6.3          As discussed in the above Section 8.3, different schemes proposed for the disposal of the treated effluent from YLSTW being reviewed by the Government are both designed for the DWF of just only 50,000 m3/db. It is thus found that the existing YLSTW with the DWF capacity of 70,000 m3/d would have spare capacity of about 20,000 m3/d that will be sufficient to cater for the flow discharging from the subject site.

8.6.4          Having considered such spare capacity, it is ascertained that the YLSTW is capable of catering for the estimated residential sewage of 3,153 m3/d from the Project.

8.6.5          There are existing sewers in Fuk Hi Street to receive sewage from the village huts along Fuk Shun Street. The existing sewers beneath Wang Lee Street and Wang Lok Street of the YLIE are built to divert the sewer generated from the YLIE and also the catchment from Fuk Shun Street to the YLSTW.

8.6.6          A Sewerage Impact Assessment (SIA) has been carried out for Strategy A2 to confirm the feasibility and possible impact of using the existing sewers under Fuk Hi Street, Wang Lee Street and Wang Lok Street for diverting sewage generated by the Project to the YLSTW. Details of the SIA are presented in Appendix 8-1.

Strategy B (Western Option)

8.6.7          The SIA presented in Appendix 8-1 has studied the feasibility of Strategy B and possible impact on existing sewerage system. .

8.6.8          The existing TWRSPS has an ultimate capacity for a peak flow of 1,284 l/s i.e. 110,937.6 m3/day. The projected flow to the TWRSPS is about 41,000 m3/day (ADWF) which would be within the normal design tolerance of the pumping station, as the additional flow is roughly equivalent to only 7.7% increase of the current projected flow of 41,000 m3/day. The pumping station is thus considered to have adequate capacity to absorb all of the sewage discharge from the Project.

8.6.9          As shown in Figure A8-7 in Appendix 8-1 Sewerage Impact Assessment, the pumping station with an ultimate capacity PWWF of 6.269 m3/s is considered to have enough spare capacity to absorb the ultimate flows from the Project and TSWRZ (i.e. PWWF 1.424 m3/s).

8.6.10      As Ha Tsuen Pumping Station and San Wai STW are designed to cope with the discharge from TWRSPS, they should have spare capacity to absorb the ultimate flows from the Project.

 

8.7              New & Upgrading Works of Sewerage Systems Required for Either Options

Strategy A

8.7.1          As a new sewer connecting the pump house of the Project and YLSTW is to be built for its entire length for Strategy A1, no upgrading of existing sewers are required for this sewerage option. The new sewer will be laid beneath existing local roads, viz. the Fuk Shun Street and the local road next to Leon Court. The approximate length will be about 1,356m. Wayleave from the Government is required.

8.7.2          For Strategy A2, a new sewer would have to be built to connect to the existing sewer under Fuk Hi Street for discharging the sewage from the subject site to YLSTW direct. As evaluated in the SIA presented in Appendix 8-1, no upgrading work on the downstream side of the existing sewers is considered necessary.

8.7.3          It is estimated that 4 months would be required for installing the new sewer under Strategy A. The installation works will be carried out during the improvement works of the access road.

8.7.4          By comparing size of the proposed works and relevant impact on the public, Strategy A2 is preferable to Strategy A1.

Strategy B

8.7.5          Strategy B requires laying of 940m new sewer beneath the planned/ existing road at the western side of the subject site. Way-leave from the Government is required.

8.7.6          It also requires to increase the pipe delivery capacities in Tin Wah Road by either upgrading the existing sewerage system or laying an additional sewer. Table 7.3 of the Appendix 8-1 SIA shows that all segments of sewage pipes under Tin Wah Road, except the section from manhole s11121 to s11125a, will not have enough capacity to cope with projected ultimate design flow even without the additional flows from the Project.

8.7.7          Upgrading of the sewage pipes from manhole s11102 to s11121 with length of 948.8m is considered necessary to convey the flow from the Project to TWR pumping station via the sewers under Tin Wah Road. The size diameter of the proposed upgraded pipes and the adequacy of sewerage network after upgrading the sewage pipes are given in Table 8‑2.

 

Table 82         Required Upgrading of the Sewerage Network Leading to the TWR pumping Station

 

Length (m)

Level (out) (m)

Level (in) (m)

Diameter (m)

Sewage Pipe (s11102>s11103)

42.0

5.98

5.77

0.600

Sewage Pipe (s11103>s11107)

161.0

2.92

1.65

0.600

Sewage Pipe (s11107>s10519)

235.2

1.57

-0.28

0.600

Sewage Pipe (s10519>s11117)

241.1

-1.29

-1.78

0.900

Sewage Pipe (s11117>s11121)

269.5

-1.95

-2.31

1.050

 

8.7.8          As an alternative to minimize interruption to the operation of the existing sewerage, it is also feasible to lay a new sewer alongside the existing one at Tin Wah Road to convey the flow.The proposed sewerage works at Tin Wah Road will be programmed in such a way as to maintain the normal function of the existing sewer and normal traffic on the road.

8.7.9          A period of 12 months would be required for Strategy B in constructing new sewers. The time for traffic diversion under each strategy has already been included. It will involve increasing the size of the proposed public sewer. No modification on the design of the TWR Pumping Station is necessary.

 

8.8              Environmental Impacts of Sewerage Systems

Construction Phase

8.8.1          The general possible environmental impacts generated from the construction of the sewerage systems and the proposed mitigation measures, regarding air, noise, water, waste aspects, are presented in the relevant chapters. With the proposed mitigation measures implemented, the environmental impacts posed by the construction activities of sewage systems are anticipated to be insignificant.

Operational Phase

8.8.2          During the operational phase, the on-site pump house required for either disposal strategies are expected to cause insignificant environmental impacts in terms of air, noise and water pollution during its operation. 

8.8.3          Odour - the main odour nuisances can be attributed to the wet wells/ retention tanks of the pump house. As such, the pump house will be enclosed inside building structure equipped with adequate odour control measures such as scrubber and activated charcoal filter at the exhaust of the ventilation system. The vent will be located away from air sensitive uses including the proposed development itself.

8.8.4          The noise level that could be caused by the pump house during its operation phase has been addressed in Section 5.7 about noise impact assessment and was found acceptable.

8.8.5          On the water pollution aspect, the pump house will be entirely enclosed with adequate odour and noise control measures. The on-site facilities will be provided with adequately sized raw sewage retention tanks and necessary redundancy in the pump sets and stanby generators to ensure uninterrupted operations in case of occasional failure.

8.8.6          In the unlikely event that all these measures fail, the fallback will be to tanker away the sewage to the nearest YLSTW so as to avoid overflowing and discharge of raw sewage to the nearby sensitive ecological environment, e.g. the WCA or WBA of Deep Bay. The discharge of untreated sewage will be prohibited and is likely to be part of the licencing requirements.

The Preferred Options

8.8.7          On technical feasibility, the Strategies A1, A2 and B discussed in the foregoing paragraphs are all feasible.

8.8.8          On land matter, comparing Strategies A1, A2 and B, Strategies A1 and A2 are better given its relatively shorter wayleave (1,356m and 581m for laying new sewers under Strategy A1 and A2 respectively) with no upgrading of existing sewers required. The required wayleave for Strategy B is about 2,266m (i.e. 940m for laying new sewers at the distance between the subject site and Tin Wah Road and  approximate 1,327 m for upgrading of existing sewer or new sewer in Tin Wah Road).

8.8.9          On construction complexity and programme, Strategies A1 and A2 can obviously be completed within the shortest period of time and with least disturbance to traffic.

8.8.10      The choice of sewage disposal strategy remains open at this stage, subject to the decision and approval from the Government in consideration of the sewerage proposals for the district. Whilst Strategy A2 is considered preferable from implementation point of view, Strategy A1, A2 and B are all environmentally acceptable and hence sewage disposal is not considered an issue in this EIA.

 

8.9              Preliminary Design, Operation and Maintenance Requirements of the Proposed Sewerage System for Either Options

Sewage Pump house

8.9.1          Design of the pump house will follow the recommendations in “The hydraulic design of pump sumps and intakes” by M. J. Prosser. The selection of equipment will comply with the followings:

·        Statutory ordinances or regulations;

·        Relevant British Standards of equivalent;

·        I.E.E. wiring regulations;

·        Local electricity supply authority requirements;

·        Hong Kong SAR Government Fire Services Department requirements; and

·        Hong Kong SAR Government security requirements.

8.9.2          The selection of the number of pump units for the pump house should be based on the following criteria:

·        Providing a standby capacity of 33% to 50%;

·        Maintaining a minimum velocity of 0.6 m/s under all pumping conditions; and

·        Keeping the retention time in the wet well to a minimum and be less than 30 minutes.

8.9.3          Standby sewage pump and generator will be provided in case of power failure. No emergency bypass will be allowed to the surrounding ecologically sensitive areas.

8.9.4          The sewage pump house will be located at the built area of the Development. Subject to the choice of sewerage option and the final design of the MLP and the pump house, the sewage pump house is tentatively proposed to be housed inside a concrete structure near the car-park area for the visitors with openings at the southern side facing away from any Noise Sensitive Receivers. It will be equipped with 2 duty and 1 standby sewage pump to raise the sewage head by about 9m. Given its proven reliability and ease of inspection and maintenance, electrically operated vertical spindle non-clog dry well sewage pump will be used.

8.9.5          The pump house will comprise a dry well, a divided wet sump, retention sumps and an intake channel. The loading bay for cart-away of sludge and grit will be located within the pump house building to facilitate odour control.

8.9.6          The pump house will be designed for unattended operation with appropriate instrumentation and control systems. Remote monitoring and alarms will be provided by a telemetry system if necessary.

8.9.7          In accordance with Table 3 of the Sewerage Manual, for the population of the development is less than 10,000, the flow peaking factor (including Stormwater Allowance on ADWF) for the sewage pump house is around 5.11. Based on the calculated sewage flows for the Development, the proposed pump house is designed to have an ultimate capacity for a peak flow 5.11 x ADWF i.e. 5.11 x 36.4 l/s = 186 l/s.

8.9.8          In order to minimise the chance and duration of failure incidence of the pump house which may result in emergency discharge, the following mitigation measures are proposed to be implemented: -

·        Twin rising mains will be provided for the pump house to ensure the proposed sewage rising mains are maintainable without the need to shut down and discharge untreated sewage into the natural stream/drainage directly.

·        Standby pump will be made available to facilitate the maintenance and repairing of equipments;

·        Back-up power supply will be provided in the format of either ring main or automatic-operated emergency generator with sufficient capacity to cope with the demand loading of the essential plant equipment;

·        Overflow should not be allowed to occur on a regular basis e.g. facilitating routine maintenance.  In the unlikely event that all the above measures fail, the fallback will be to tanker away the sewage to the nearest YLSTW so as to avoid overflowing and discharge of raw sewage to the nearby sensitive ecological environment

8.9.9          Piled foundation are recommended and considered technically viable for the pump house as it does not require removal of all relatively soft pond mud underneath which will result in less disposal of spoil.

8.9.10      The exact details of the pump house will be agreed with DSD, EPD and EMSD during the detailed design stage.

Sewers

8.9.11      All sewers will be sized for the ultimate development at Fung Lok Wai. The design criteria of sewers and manholes should follow the requirements in the Sewerage Manual published by Drainage Services Department and Civil Engineering Manual Volume VI where appropriate.

8.9.12      Manholes of depth will be constructed to standard details shown in DSD Standard Drawings.

8.9.13      In accordance to the requirements of the Sewerage Manual, manholes will be provided at:

·        Intersection of sewers;

·        Junction between different size/gradient of sewers;

·        Location where the sewer changes direction; and

·        On long straight lengths at the following intervals:

Diameter of pipe size (mm)

Maximum intervals (m)

Smaller than 600

40

Between 600 – 1050

80

Larger than 1050

120

 

8.9.14      The maintenance and operation requirements for the pump house, sewers and manholes will be the same as those for similar installations elsewhere in the Territory and should therefore follow normal procedures.

 

8.10          Conclusion

8.10.1      Taking into consideration the existing and committed sewerage facilities in the vicinity of the Project, the sewage disposal strategies A1, A2 and B have been investigated for the Project. In broad terms, these strategies involve installing an on-site sewage pump house within the Project site and providing a new sewer to discharge sewage to the nearby sewage treatment work or pumping stations.

8.10.2      The three proposed strategies are all considered technically feasible although this is subject to negotiation and agreement with the relevant Government departments.

8.10.3      The selection of sewerage options remains open at this stage, subject to the decision and approval from the Government in consideration of the sewerage proposals for the district. From implementation point of view, Strategy A2 is more preferable.

8.10.4      It is proposed that the project proponent will be responsible for the construction and the upgrading of the needed sewerage system and the connections with the agreement with DSD while the Government will take up the maintenance responsibility after the project proponent hands over the sewers to the Government upon completion.


9.                   Waste Management

9.1              Introduction

9.1.1          This section identifies the quantity, quality and timing of wastes arising as a result of construction and operation of the Project. The waste management implications are evaluated and assessed in accordance with the criteria and guidelines given in Annexes 7 and 15 of the EIAO TM. Clause 3.5.5 of the EIA Study Brief sets out the scope and requirement of the assessment.

9.1.2          The appropriate disposal method for each type of waste was identified. Opportunities for reducing construction waste generation and maximizing re-use on-site were evaluated. The potential impacts arising from handling, collection, and disposal of wastes and the environmental mitigation measures required to mitigate these environmental impacts were identified and recommended.

9.1.3          Due to the low-density nature of the proposed residential development, the operation of the development will generate limited amount of domestic wastes. The handling and disposal of this small quantity of waste during the operational phase will follow the usual approach of collection by refuse collection vehicles (RCV) as it is managed in other parts of Hong Kong. This will therefore unlikely to cause any significant environmental impact. The waste management implication during the operation of the residential development is therefore not evaluated in this EIA study.

 

9.2              Legislation and Guidelines

9.2.1          The principle legislation governing waste management in Hong Kong is the Waste Disposal Ordinance (Cap. 354) (WDO), and its subsidiary regulations. The Ordinance, enacted in 1980, generally encompasses all stages of waste management, from place of arising to final disposal point of waste.  The Waste Disposal (Chemical Waste) (General) Regulation, enacted under the WDO in 1992, provides controls on all aspects of chemical waste disposal, including storage, collection, transport, treatment and final disposal.

9.2.2          In addition to the WDO and its subsidiary regulation, the following legislation have some bearing on the handling, treatment and disposal of wastes in Hong Kong, viz.:

·        Dumping at Sea Ordinance (1995);

·        Crown Land Ordinance (Cap. 28);

·        Public Health and Municipal Services Ordinance (Cap. 132) Public Cleansing and Prevention of Nuisances (Urban Council) and (Regional Council) By-laws; and

·        Dangerous Goods Ordinance; and

·        Air Pollution Control (Open Burning) Regulation.

9.2.3          There are also various guidelines which are relevant to waste management in Hong Kong:

·        Waste Disposal Plan for Hong Kong (December 1989), Planning, Environmental and Lands Branch Government Secretariat;

·        New Disposal Arrangements for Construction Waste (1992), Environmental Protection Department & Civil Engineering Department;

·        Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes (1992), Environmental Protection Department;

·        Works Branch Technical Circular No. 12/2000, Fill Management;

·        Environment, Transport and Works Bureau Technical Circular (Works) No. 34/2002, Management of Dredged/Excavated Sediment;

·        Works Branch Technical Circular No. 2/93, Public Dumps;

·        Work Branch Technical circular No. 16/93, Wet Soil in Public Dumps;

·        Works Bureau Technical Circular No. 5/98, On Site Sorting of Construction Waste on Demolition Sites;

·        Environment, Transport and Works Bureau Technical Circular (Works) No. 31/2004, Trip-ticket System for Disposal of Construction and Demolition Material;

·        Works Bureau Technical Circular No. 25/99, Incorporation of Information on Construction and Demolition Material Management in Public Works Subcommittee Papers;

·        Works Bureau Technical Circular No. 4/98, Use of Public Fill in Reclamation & Earth Filling Projects;

·        Works Bureau Technical Circular No.19/2001, Metallic Site Hoardings and Signboards; and

 

9.3              Analysis of Activities and Waste Generation

9.3.1          With the waste generating activities identified, wastes generated during the construction phase of the project would likely comprise the following categories:

·        Construction and Demolition Material (C&DM) from excavation works, including fishponds sediment and bund materials from pond dredging activities;

·        Chemical waste from vehicle and equipment maintenance activities;

·        General refuse from workforce on-site.

9.3.2          The potential environmental impact arising from the handling, storage, transport and disposal of these different categories of waste and the recommended waste management and control measures are described below.

Construction and Demolition Material (C&DM)

General

9.3.3          The Fung Lok Wai site is topographically flat, rural in character, and primarily occupied by fishponds. Construction works required for the Project will unlikely result in generation of a large quantity of C&DM as extensive excavation activities will not be required.

9.3.4          Demolition material would be generated from clearance of a small number of huts on-site. A “selective demolition” approach should be adopted so that reusable material such as wood, metal, and steel can be segregated for reuse or recycling as far as practicable. Inert building debris such as concrete and brick can also be reused on-site as lining or fill material. The remaining part comprising of degradable waste should be properly disposed of at landfills.

9.3.5          Construction waste that could be directly generated from construction activities and from surplus construction material may include:

·        Surplus concrete or grouting mixes;

·        Wood from formwork and Materials and equipment wrappings, etc.

·        Damaged or contaminated construction materials; and

·        Equipment and vehicle maintenance parts;.

9.3.6          The generation of wastes from these materials should be minimised as far as practicable through recovery, reuse and/ or recycling.  Construction methods aim at minimizing construction and demolition waste will be used.  External walls pre-fabricated in factories and fitted with finishes, windows and glazings will be delivered to site and installed floor by floor.  This will substantially reduce the amount of concreting on site.  Metal formwork will also be used for all in-situ concreting where necessary. This method of construction will basically eliminate the use of timber formwork on site and thus reduce substantially timber and concrete waste.  Whenever practicable, the production of construction waste due to over-ordering or as “side-products” of construction activities should be minimised by the contractor through careful design, planning, good site management, control of ordering procedures, segregation and reuse of materials.  These measures will also assist the contractor in minimising costs associated with the construction works.

9.3.7          Should construction site hoarding be erected, metal fencing or building panels, which are more durable than wooden panels, are recommended to be used as far as practicable. Opportunity shall also be sought to re-use any wooden boards used in site fencing on-site or off-site.  Concrete and masonry can be crushed and used as fill material if practicable. On-site incineration of wooden waste is prohibited.

9.3.8          Cross contamination of inert C&DM by other waste categories shall be minimised as far as practicable through provision of storage facilities for different categories of waste. Inert material including soil, rock, concrete, brick, cement plaster/ mortar, inert building debris, aggregates and asphalt should be segregated from and stored separate from other waste categories to ensure proper handling and reuse. The on-site temporary facilities should be equipped with dust control measures where necessary.

9.3.9          By reducing the quantity of C&DM requiring off-site disposal through the reuse on-site, the potential for traffic impacts during the transportation of material will be reduced. The additional traffic flow due to the transportation of construction material from vehicle movements in and out of site is considered insignificant.

9.3.10      As described in Section 6.3.20 to 6.3.24, considering the nature of the historical uses of the site and the fishponds sediment quality sampled, contaminants such as heavy metal, metalloids and PAHs in the pond mud are well below the Lower Chemical Exceedance Level (LCEL) of the Sediment Quality Criteria as stipulated in the ETWB TCW No. 34/2002 - Management of Dredged/Excavated Sediment (i.e. Category L).

9.3.11      In order to avoid dust, odour and erosion impacts, all stockpile areas at the site should be covered with tarpaulin or impermeable sheets. Any vehicle carrying C&D waste should have their load covered when leaving the works area. Vehicles should be routed as far as possible to avoid sensitive receivers in the area. The potential air and runoff impacts caused by handling of excavated materials are presented in the Sections of Air Impact Assessment and Water Impact Assessment respectively.

Excavated Materials from Construction of WNR

9.3.12      Extensive excavation is not anticipated during the establishment of WNR, only minor earth works such as re-profiling and removal of unnecessary bunds will need to be performed.

9.3.13      Since the establishment of WNR requires substantial amount of soil, in order to minimize waste generation and reduce the amount of imported soil, all materials generated from earth moving activities, including dredged pond mud and inert demolition wastes from unwanted bunds, will be fully and immediately re-utilised on-site as filling material for the establishment of the WNR. It is estimated that bund removal and re-profiling will generate less than 100,000m3 of bund materials. This quantity is adequate for the re-profiling the submerged components of removed bunds and the formation of small islands. Surplus amount of the materials will be used for formation of the marshland.

9.3.14      Though unlikely, should marine disposal of any pond materials be considered, the materials will be subject to the recommendations of ETWB TCW No.34/2002.

9.3.15      Owing to the substantial amount of soil required, especially for the formation of the marshland, even when all dredged pond mud and inert C&D materials are re-used on-site, there is still a shortfall of materials. The estimated amount of soil needs to be imported for the establishment of WNR is about 132,700 m3.

9.3.16      For the construction of alternative egretry during the pre-construction phase, an estimated amount of 1,200 m3 fill materials will be gained on-site through removing unwanted bunds between existing Pond No. 38 and 40 and unwanted bunds between Pond No. 37, 39 and 41.

9.3.17      During 4th quarter 2010 to 2nd quarter 2011, there will be a surplus of 3,000 m3 of bund materials generated from site clearance and removal of unwanted bunds inside Section 1 and 2 of WNR. To maximize the opportunity for reducing waste generation, the bund materials can be temporarily stockpiled at the location of Storage Pond inside WNR and re-used for Marshland establishment at 4th quarter of 2011. The stockpile area will be covered with tarpaulin or impermeable sheets to avoid potential odour and erosion problems.

Excavated Materials from Construction Works at Built Area

9.3.18      At the built area, topsoil of the existing fishponds will be dredged during the site formation from 4th quarter 2011 to 1st quarter 2012. The volume of soil is estimated to be in the amount of 12,300 m3. Those topsoil will be moved to the marshland area for land formation once they are dredged, or they can be re-used on-site for the establishment of WNR, for instance re-profiling of pond bunds, partial filling of ponds, creation of shallow waters and muddy island during the same construction phase, if considered necessary.

9.3.19      During the piling works at the built area from 3rd quarter 2013 to 2nd quarter 2014, about 180 numbers of 2.5m-diameter bored piles will be used. The amount of excavated spoil generated will be about 3,530 m3. They can be retained and re-used as fill materials on site or for landscaping works at the built area, so to save costs for such works and reduce the transportation and environmental impacts of disposal.

9.3.20      With the basement car parks at the built area built on top of the ground level of those dredged ponds (about 2m mPD), the amount of soil need to be imported for pond filling can be greatly reduced. As the basement car parks will have site coverage of 70% of the built area, the estimated amount of soil needs to be imported for pond filling at the built area is estimated to be about 58,000 m3.

9.3.21      Table 91 summarizes the timing, estimated amount of excavated materials that could arise, and estimated amount of fill materials required during the construction of the Project.

9.3.22      As indicated in Table 91, the estimated amount of C&D materials to be reused on-site is 309,796m3. The estimated amount of C&D materials generated on-site is 122,861m3 which should be fully reused on-site. The C&D materials to be reused on-site also include the C&D materials imported from a public filling area, The amount of C&D materials imported from the public filling area and to be reused on-site is estimated to be 186,935m3.

Excavated Materials from Improvement Works of Access Road Leading to the Site

9.3.23      Since vehicular access to the Fung Lok Wai site will be via the Fuk Shun Street, which requires only road widening and improvement works to link up with the internal access road, this will generate minimal amount of waste.

9.3.24      Excavation is only required for the laying of stormwater drains, sewers and other utilities. As the “cut and fill” approach will be used, the amount of excavated material generated would be minimized.

 

Table 91         Sumamry Table of Estimate Quantity of Materials to be Generated or Imported during the Construction of the Fung Lok Wai Project

Key Construction Activities

Duration

Estimate Quantity of Material to be generated (m3)

Estimate Quantity of Material to be reused on site   (m3)

Estimate Quantity of Materials to be imported (m3)

Estimate Quantity of C&D Materials to be delivered to and reused in public filling areas (m3)

Estimate Quantity of C&D Materials to be disposed of at landfill areas (m3)

Remarks

Construction of potential alternative egretry

3rd quarter 2010

1,200

1200

-

-

-

Fill Materials will be gained on-site through removing unwanted bunds between existing Pond No. 38 & 40 and unwanted bunds between Pond No. 37,39 & 41

Site Clearance & Removal of unwanted bunds inside WNR (Section 1, 2)

4th quarter 2010 & 2nd quarter 2011

71,500

-

-

3000

-

For the 3000 m3 surplus of bund materials, they can be temporarily stockpiled on site at location of Storage Pond & used for Marshland establishment at 4th quarter of 2011

Re-profiling works for establishment of WNR

-

68,500

Topsoil dredging at built area

4th quarter 2011 to 1st quarter 2012

12,300

-

136,200

380

120

No pond filling activities is required to be performad at the area of storage pond

Site clearance & Removal of unwanted bunds at built area

5,000

-

Site Clearance of Removal of unwanted bunds at Marshland

27,000

-

Raise level and land formation for Marshland

-

180,000

 

 

 

 

 

 

 

 

Pond filling at built area

2nd quarter 2012 to 1st quarter 2013

-

58,000

58,000

-

-

 

Excavated spoil generated from piling works

3rd quarter 2013 to 2nd quarter 2014

3,530

 

1000

 

-

1770

760

The opportunity to re-use the excavated spoil on-site will be maximized e.g. as fill materials or for landscaping works at the built area

Other superstructure works

3rd quarter 2014 to 3rd quarter of 2016

975

-

-

750

225

The opportunity to re-use on-site will be maximized

Widening of Access Road (including Laying of drainage, sewerage & utilities)

4th quarter 2014 to 3rd quarter 2016

1356

1096

-

200

60

The opportunity to re-use on-site will be maximized

Total

 

122,861

309,796*

194,200

6,100

1,165

 

* The “Estimate Quantity of Material to be reused on site” is greater than the “Estimate Quantity of Material to be generated” because the former also included the “Estimate Quantity of Materials to be imported”, as those imported C&D materials from public fill area is anticipated to be reused onsite.

Chemical Waste

9.3.25      As defined under the Waste Disposal (Chemical Waste) (General) Regulation, chemical waste includes any substance being scrap material or unwanted substances specified under Schedule 1 of the Regulation. Chemical waste that could be generated from construction works would primarily arise from chemicals used in operation and maintenance of on-site equipment. These may include fuel, oil, lubricants, cleaning fluids, and solvents arising from leakage or maintenance of on-site equipment and vehicles.  Chemical generated from daily operation of the construction works shall be recycled/ reused on-site as far as practicable.

9.3.26      The amount of chemical waste that will be generated from the construction works will depend on the contractor’s on-site maintenance intention, age and number of plant and vehicles used.  Nevertheless, chemical wastes such as lubricating oil or solvent generated by workers are not expected to be in large quantity.  The likely chemical waste types are readily accepted at the chemical waste treatment centre at Tsing Yi or other licensed waste oil recycling facilities in Hong Kong.  The Centre for Environmental Technology operates a Waste Exchange Scheme, which can assist in finding potential buyers of chemical for reuse or recycling.

9.3.27      If off-site disposal of chemical waste is required, they should be collected and delivered by licensed contractors to Tsing Yi Chemical Waste Treatment Facility and be disposed of in strict accordance with the Waste Disposal (Chemical Waste) (General) Regulation. Contractors shall register with EPD as chemical waste producers when disposal of chemical waste is anticipated to be required.  Chemical waste materials have to be stored on-site with suitable containers and away from water bodies so that leakage or spillage is prevented during the handling, storage, and subsequent transportation.

9.3.28      Provided that the handling, storage and disposal of chemical wastes are in accordance with the Waste Disposal (Chemical Waste) (General) Regulation and the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, this will unlikely cause an unacceptable environmental impact.

9.3.29      Spent bentonite slurries, if any, will be handled and disposed of properly in accordance with the requirements set out in the Practice Note for Professional Persons (PN1/94) Construction Site Drainage. Fossil fuel and used lubricants for trucks and machinery are classified as chemical wastes.  The Contractor shall register with EPD as a chemical waste producer and observe all the requirements under the storage, labelling, transportation and disposal of chemical waste.

9.3.30      The Contractor shall prevent fuel and lubricating oil leakage from plant and storage sites from contaminating the construction site.  All compounds in work areas shall be positioned on areas with hard paving and served by drainage facility.  Sand/ silt traps and oil interceptors shall be provided at appropriate locations prior to the discharge points.

General Refuse

9.3.31      Throughout the construction phase, the workforce on the construction site will generate a variety of general refuse requiring disposal.  These refuse will mainly consist of food wastes, aluminium cans, and waste paper, etc.  No information regarding the number of workers on-site would be available at this early project stage.  Nevertheless, assuming that 50 workers are working together at any one site, and a waste generation rate of about 0.6 kg per person, it could be estimated that the amount of general refuse that would be generated is in the order of 30 kg per day.

9.3.32      General refuse generated at the construction site should be stored separate from construction and chemical wastes to avoid cross contamination.  A reliable waste collector shall be employed by the Contractor to remove general refuse from the construction site on a daily basis where appropriate to minimise the potential odour, pest and litter impacts. Open burning for the disposal of construction waste or the clearance of the site in preparation for construction work is prohibited under the Air Pollution Control (Open Burning) Regulation.

 

9.4              Proposal for Waste Management

9.4.1          To ensure the appropriate handling of the C&DM, it is recommended that a Waste Management Plan (WMP) shall be developed by the contractor at the commencement of the construction works. The WMP should be developed taking into account the recommended control measures given in this section where appropriate. The WMP shall be submitted to the Engineer at the commencement of the project for approval.

9.4.2          The following additional control/ mitigation measures are recommended to be followed by the Contractor:

·        Storage of different waste types - different types of waste should be segregated and stored in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal.  An on-site temporary storage area equipped with required control measures (e.g. dust) should be provided;

·        Trip-ticket system – in order to monitor the proper disposal of non-inert C&D waste to landfills and to control fly-tipping, a trip-ticket system should be included as one of the contractual requirements and audited by the Environmental Team;

·        Records of Wastes - a recording system for the amount of wastes generated, recycled and disposed (including the disposal sites) should be proposed;

·        Training - The contractor should provide his workers with proper training of appropriate waste management procedure to achieve waste reduction as far as practicable and cost-effective through recovery, reuse and recycling and avoid contamination of reusable C&DM. 

Construction Waste EM&A Requirements

9.4.3          In order to ensure that each construction waste stream generated from the construction phase of the Project are managed in accordance with the procedures recommended in this EIA, it is recommended that auditing by an Environmental Team be carried out as part of the overall construction phase EM&A programme. The regular audit should look at the key aspects of waste management including waste generation, storage, recycling, reuse, transport and disposal.

Operational Phase Assessment

9.4.4          The proposed residential development will accommodate a residential population around 5,980 after full occupation. With reference to the Data from Monitoring in Solid Waste in Hong Kong 1999, the capita generation rates of domestic waste will be 1.48 kg/day in 2016. Under such assumption, the estimated quantity of wastes generated from the Development will be 8,850 kg/day.

9.4.5          Refuse collection chambers (RCC) will be provided for the residential development.  In order to comply with Building Regulation, mechanical ventilation will be provided. The odour nuisance to the pubic can be minimized by incorporating the odour absorption system. With proper management and maintenance of the waste facilities, possible leachate impact from the RCC is not anticipated.

9.4.6          It is also recommended that collection bins for used aluminium cans, waste paper and glass bottles should be provided at strategic locations of the residential development area to promote and encourage recycling by residents during the operational phase.

 

9.5              Impacts Summary and Conclusion

9.5.1          The waste streams that would be generated during the construction and operational phase of the proposed Project at Fung Lok Wai were identified and evaluated in terms of their nature, type, quality, quantity, and associated environmental impacts. Opportunities for reduction in waste generation through recovery, reuse or recycling are identified.

9.5.2          The waste management implications and potential environmental impacts associated with the handling, transport, and disposal of the identified waste types are evaluated and addressed. An EM&A programme is recommended to be in place during the construction phase to check the waste generated from the construction site are being managed in the accordance with the recommended procedures.

9.5.3          Provided that the recommendations set out in this section are implemented, no waste related regulatory non-compliance and unacceptable environmental impacts are expected to arise from the handling, storage, transport and disposal of construction waste arising from the proposed residential and wetland nature reserve development.

9.5.4          The nature of the historical uses of the site and the findings of the sediment sampling results confirm that land contamination should not be a concern.

9.5.5           


10.             cultural heritage impact assessment

10.1          Introduction

10.1.1      This section evaluates and assesses the cultural heritage impact of the Development in accordance with the requirements stated in Clause 3.5.8 of the Study Brief and the criteria and guidelines stated in Section 2 of both Annexes 10 and 19 of the TM.

 

10.2          Objectives of the Cultural Heritage Impact Assessment (CHIA)

10.2.1      The objectives of the CHIA are the following:

·        To identify landscape features within the Study Area, including sites of historical events, historical field patterns, tracks and fishponds and cultural elements such as fung shui woodlands and clan grave sites which will be affected by the proposed development;

·        To identify direct and indirect impacts on the nearby historical buildings and structures in the following villages:

o        Ng Uk Tsuen, including the Tin Hau Temple and village houses;

o        Shing Uk Tsuen, village houses;

o        Tai Tseng Wai, village houses;

·        To assess potential impacts including visual impacts on fung shui/visual corridors of the historical buildings and structures;

·        To propose measures to mitigate against identified impacts.

 

10.3          CHIA Methodology

Desk-based Study

10.3.1      A desk-based review was undertaken to identify the known cultural heritage resources in the broader Study Area.  Research gleaned existing information and included the following sources: published and unpublished AMO reports and files, Public Records Office, GEO bore hole data, GEO aerial photograph library, Lands Department maps and photographs and other relevant resources.

Historical Buildings and Structures Survey

10.3.2      A systematic survey of the Study Areas and potentially indirectly impacted adjacent areas was carried out in order to record all buildings and structures and parts thereof which were constructed before the year 1950 and/or otherwise qualify as having heritage value according to the AMO criteria. Identified cultural heritage resources were recorded on detailed recording forms, for both their architectural features and cultural and historical associations. Photographs were taken and the resources located on 1:1000 maps. The Survey is described in further detail in Section 10.5.

Historical Landscape Features Survey

10.3.3      Field inspections were undertaken to assess the status, function and conditions of the ponds at present.  The results are presented in Section 10.6.  

Assessment of Impacts and Recommendation of Mitigation

10.3.4      Data collected from the previous tasks was examined in the light of previous alterations to the original landscape and the predicted impacts of the planned development on the identified and potential heritage resources. The summary of the results of this assessment and resulting recommendations for mitigation are presented below in Section 10.7.

 

10.4          The Study Area

Geology and Topography

10.4.1      The Study Area is characterised entirely by extensive, reclaimed mud flats lying at approximately 4 m PD. The Study Area comprises almost entirely of undivided, mainly dark grey marine mud and partly silty marine sands (both belong to the Hang Hau Formation).  These muds and thin stretches of sand are entirely Holocene in age and are evidence of rapid sedimentation in the Deep Bay area. Along the southern edge of the Study Area there is a strip of Holocene marine sands, which represent the earliest shoreline.

10.4.2      These sands in turn lie against Pleistocene terraced alluvium and debris flow deposits of the original landform, a north east pointing peninsula of Lok Ma Chau Formation metamorphosed sedimentary and volcanic rock. The peninsula rises to a height of 61.7 m. PD. Debris flow deposits and terraced alluvium (Pleistocene) form the lower parts of its slopes. The hills are gently sloping and consist of relatively fine grained deposits of cobbles and gravel in clayey silt. To the north west of Ng Uk Tsuen fine granite intrudes the main geology (Langford R.L., et al.1989).

Existing Impacts

10.4.3      The Study Area does not impact on the landmass and is thus entirely located in the ponds.  The following impacts have occurred in the Study Area:

·        Re-dividing of the ponds, changing of their shapes;

·        Temporary structures;

·        Surfacing of the roads (minimal).

Potential Impacts

10.4.4      The proposed works may have an adverse impact on the existing landscape.  The following potential impacts may arise from construction:

·        Destruction of sections of the existing ponds and bunds;

·        Irreversible change of historical landscape of ponds and bunds;

·        Visual impacts on the historical villages;

·        Indirect impacts on the graves, historical villages and/ or structures, etc.

·        Changes in water table levels and vibration caused by the development

 

10.5          Historical Buildings and Structures Survey

Introduction

10.5.1      The background, methodology and findings of the historical buildings survey will be presented in this section. The assessment of any impacts to the recorded resources will also be presented, as will recommendations for mitigation. It should be noted that the survey included the actual Study Area as well as three nearby villages, Ng Uk Tsuen, Shing Uk Tsuen and Tai Tseng Wai, which were highlighted in the study brief.

Potential for Cultural Heritage Resources in the Study Area

10.5.2      The village of Tai Tseng Wai was settled approximately 500 years ago.  There are five surnames associated with the village; Cheng, Leung, Shing, Lam and Tang. All of the families came from Tai Peng, Tung Kwun in Guangdong. The Leung and Cheng families arrived first. The Shing, Lam and Tang arrived about 300 years ago. The people here supported themselves through fishing and farming in the area. Farming was abandoned approximately 20 years ago.

10.5.3      The village of Shing Uk Tsuen was settled approximately 400 years ago. It is a single family surname village, i.e. Shing. The families came from Guangdong province. The area behind the village was used to grow crops such as sweet potatoes and peanuts. Many of the men from the villages, traditionally worked abroad.

10.5.4      The village of Ng Uk Tsuen is a single surname village, Ng. The 1st generation ancestor was called Ng Hung Lan, who came from Nam Tau. The current generation is the 29th. The Ng family of Ng Uk Tsuen is related to the Shing family of Shing Uk Tsuen by marriage. The villagers supported themselves through farming rice, in rented fields and through fishing and catching crabs in Deep Bay. 

10.5.5      The three villages all share the gods hall in Tai Tseng Wai and the Tin Hau temple near Ng Uk Tsuen.

10.5.6      The fishponds in the Study Area were owned by people from Shek Ha in mainland China and some Tanka families. The ponds were first used in the 1920’s for harvesting of shrimp, fish and crabs. The usage of the area as fishponds continues today. The aerial photographs did show evidence of a settlement that contained two structures in 1949, see Figure 10‑2, more than a dozen units in 1963, see Figure 10‑3 and no evidence of any units in 2000, see Figure 10‑4. It is possible that these were the homes of the Tanka people who worked in the ponds.

Background

10.5.7      The Study Area consists of a series of ponds, separated by bunds. The structures currently in place here were all found to be of recent construction and of a temporary nature, see Figure 10‑5. The three villages highlighted in the brief (as listed below) contained a total of 112 structures.

·        Ng Uk Tsuen

·        Shing Uk Tsuen

·        Tai Tseng Wai

10.5.8      The recorded features included domestic structures, village gates, a temple, shrines and a village well. The villages were all easily accessible and this allowed for relatively straightforward identification of the historical and cultural resources. The field survey also included identification of burial associated sites and fung shui features, see sections 10.5.15 and 10.5.16 respectively.

Historical Buildings and Structures Survey Methodology

10.5.9      The structures within the Study Area as well as those in the villages were surveyed and assessed on an individual basis. The survey consisted of a field evaluation incorporating the collection of photographic, oral and written information, on the architecture and history of all historical structures to be impacted by the proposed development. This information was recorded on specially designed forms, (either a full ten page form, or in cases where the structure could be adequately described in less space, a one page summary form). These forms were designed to provide a complete documentation of all identifiable pre-1950 structures, as well as any more recent structures of cultural/ historical significance. Architectural features and structural modifications, as well as historical attributes, such as previous uses and past associations with local families or prominent personages are documented on the forms. The design of the forms is based on AMO and ICOMOS (International Charter for the Conservation and Restoration of Monuments and Sites) standards for the recording of historical resources with modifications to suit architectural styles and situations encountered in Hong Kong. The recording forms also include general information about the structure, such as location, building type, usage and ownership. The forms have been compiled to create a catalogue, which is included in this report, see Appendix 10-1. As well, a synopsis of each structure is presented below and the locations of the historical/ cultural resources highlighted on 1:1000 scale maps (see Figure 10‑6, Figure 10‑7 and Figure 10‑8 and Figure 108a).

10.5.10   The data gathered from the field survey for the individual heritage resources along with the information from previous desk based research was used to prepare assessments of the historical resources and formulate mitigation recommendations.

Synopses of Recorded Structures and Village Summaries

10.5.11   All of the recorded structures were located in the three villages and are presented in synopsis form below. The actual Study Area was found to contain no cultural heritage resources of any kind.

Shing Uk Tsuen (Figure 10‑6)

10.5.12   This village contains a number of traditional structures. Many of the domestic structures were courtyard style terraces. The majority of these structures were either abandoned or closed up and not being used as houses. Many of the modern replacement structures date to the 1970’s and 1980’s. There is no current building activity going on in the village. There are still a number of cut stone pieces, taken from demolished buildings, in the village.

 

FLW-01-01      Kwong Ling Tong (Tse Tong). A 1971 structure built on the site of an older Study Hall. Two storey concrete building, flat roof, balcony on first floor façade. Parapet with red star and 1971 on façade.

FLW-01-02      Ruins of a single storey green brick shed. Front section partially intact, middle and rear destroyed. Pre-1950 in date.

FLW-01-03      Green brick, end terrace, courtyard style house. Decorative canopy over main entrance door. Frieze panels in poor condition on façade and right wall and gable. Approximately 100 years old.

FLW-01-04      Compound with Green brick house and attached structures. The house has traditional exterior maintained and tile and concrete roof.

FLW-01-05      Tree and shrine. Large Banyan tree with small shrine about 1 metre in front (by entrance gate to village). Shrine consists of small standing stone with concrete enclosure and incense holder.

FLW-01-06      Row of five green brick courtyard style terrace houses. Facades have been all been heavily modified, although interiors are relatively intact. The row is approximately 60 years old.

FLW-01-07      Two green brick, courtyard style, terrace houses, one end/ one mid terrace. Modern entranceways and canopies have been added. Frieze decorations in poor condition. Roof is entirely flat. Approximately 65 years old.

FLW-01-08      Green brick courtyard style house, end terrace (right end) structure on left hand side has been demolished. Decorative frieze and canopy intact. Pre-1950 in date.

FLW-01-09      Concrete over pounded earth courtyard style structure. Concrete roof. Pre-1950 in date.

FLW-01-10      Row of three green brick terrace houses (courtyard style).  Left hand pair are intact, right hand side unit is ruinous (façade only remaining). All facades retain decorative canopies and friezes.

FLW-01-11      A row of three green brick, courtyard style houses. Traditional facades (apart from modern gates on right hand two) with decorative features in poor condition. Pre-1950 in date.

FLW-01-12      Four green brick houses, intermediate terrace, courtyard style. Single course of granite at foundation on façade. Traditional features retained.

FLW-01-13      End terrace, green brick, courtyard style house. modern door. Decorative frieze and canopy in fair to poor condition. Pre-1950 in date.

FLW-01-14      Two green brick, courtyard style terrace houses. The right hand unit is a ruin. Left hand unit has traditional interior (altar in rear). The units are 1950 in date.

FLW-01-15      Small shed made of mixed colour bricks and pitched tile roof. No decorative features..

FLW-01-16      Row of three green brick, courtyard style terrace houses. Only left hand unit is occupied, other two are ruins. Attached structure on right hand unit is also ruinous, stone and pounded earth material.  Decorative canopies on above entranceways. Pre-1950 in date.

FLW-01-17      Mixed brick terrace house. Single pitched roof, (tile and concrete) . Roughly cut stone foundation. Pre-1950 in date.

FLW-01-18      Shing Ka Tse. Tse Tong. Two storey modern building. White pebble texture tiling on exterior.

FLW-01-19      Abandoned brick and stone building. Very overgrown with vegetation. No windows or doors. . Pre-1950 in date.

FLW-01-20      Row of three structures with two green brick courtyards style units with front section only remaining. Third structure almost completely collapsed.

FLW-01-21      Row of five courtyard style houses, green brick. Relatively unaltered (except right hand two have metal gates). Decorative canopies above entranceways. Pre-1950 in date.

FLW-01-22      Red and green brick two part structure. Arched doorway on right hand structure. Pre-1950 in date.

FLW-01-23      Row of brick and concrete animal pens. Possibly about 50 years old in portions.

FLW-01-24      Two green brick, courtyard style terrace houses. One end, one intermediate with adjoining unit demolished. Both units abandoned. Canopies and frieze on façade in poor condition.

FLW-01-25      Green brick and stone house ruins. Stones in left hand wall are uncut, except on corner. Remains of interior, overgrown. Pre-1950 in date.

Tai Tseng Wai (Figure 10‑7)

10.5.13   This village contained a number of older buildings. The majority of them were terrace houses, constructed of brick with no decorative features and a single pitched roof. The houses often had foundations of uncut or very roughly cut stones. A number of the houses were abandoned, used only for storage or housing family shrines. The traditional houses that were still being occupied often had alterations such as window additions, modern doors/gates and air conditioner units. As was seen in the village of Shing Uk Tsuen, most of the replacement village houses appear to have been constructed during the 1960’s and 1970’s.

 

FLW-01-26      Shrine, concrete with paint and stucco. Recent construction

FLW-01-27      Gate of village. Traditional and modern features. Incense holders and burners, exterior and interior. Shrine with village god figure to left of entryway.

FLW-01-28      Single storey brick house, pitched roof. In use, no decorative features remaining. Pre-1950 in date.

FLW-01-29      Gate within the village, leading to three houses. Mixed colour brick material with stone threshold. Small recess in interior wall with incense holder. The gate is attached to houses and appears to be of similar date, pre-1950.

FLW-01-30      Row of two green brick courtyard style houses.  Decorative canopy and frieze on façade. Tile and concrete roof. Pre-1950 in date.

FLW-01-31      Green brick courtyard style, end terrace house. Decorative canopy and frieze. Pre-1950 in date.

FLW-01-32      Courtyard  end terrace, green brick house. No decorative features remaining. Pre-1950 in date.

FLW-01-33      Green brick end terrace courtyard style house. Decorative canopy above door, molded frieze on façade. Pre-1950 in date.

FLW-01-34      Green brick courtyard style house. Canopy above door. Pre-1950 in date.

FLW-01-35      Pair of two-storey green brick terraces. Balcony over front section of structures. Pre-1950 in date.

FLW-01-36      Section of brick wall

FLW-01-37      Green brick courtyard unit. Parts of façade wall intact. Pre-1950 in date.

FLW-01-38      Two green brick courtyard style houses. Interior collapsed. Pre-1950 in date.

FLW-01-39      Modern Gods’ Hall.

FLW-01-40      Yee Hing Tong (Cheng Family Study Hall). one and a half stories (with loft). Entrance door off centre to left. Pre-1950 in date.

FLW-01-41      Brick house next to the Study Hall. Only decorative feature, molding under eaves on façade. Pre-1950 in date.

FLW-01-42      Three abandoned terrace houses, single pitched roofs, green brick and stone foundation. Houses date to pre 1900.

FLW-01-43      Mixed brick house. Single pitched roof. No decorative features. Pre-1950 in date.

FLW-01-44      Three mixed brick houses. Single pitched roof. No decorative features. Terrace. Pre-1950 in date.

FLW-01-45      Two intermediate green brick terrace houses, single pitched roofs. Pre-1950 in date.

FLW-01-46      Five abandoned terrace houses. Green brick and stone foundations. Pre-1950 in date.

FLW-01-47      Green brick and pounded earth house, with rough cut stone foundation. Pre-1950 in date.

FLW-01-48      Ruins of three structures, green brick wall portions remaining.

FLW-01-49      Green brick terrace house, single roof. Stone foundation. Pre-1950 in date.

FLW-01-50      Brick and pounded earth terrace house, single pitched roof, partially collapsed. Pre-1950 in date.

FLW-01-51      Ruin of two houses, green brick and mud stone walls with stone foundations. Pre-1950 in date.

FLW-01-52      Green brick structure, end terrace, concrete added around foundation. Single pitched roof. Pre-1950 in date.

FLW-01-53      Ruins of a house, mud brick walls and wooden beams in very poor condition. Pre-1950 in date.

FLW-01-54      Green brick, intermediate terrace, single pitched roof. Pre-1950 in date.

FLW-01-55      Green brick terrace house with stone foundation, in very poor condition.

FLW-01-56      Mixed brick terrace house, single pitched roof. Poor condition. Pre-1950 in date.

FLW-01-57      Green brick house, part of former terrace. Single pitched roof. Pre-1950 in date.

FLW-01-58      Mixed brick house, single pitched roof. Not in use. Pre-1950 in date.

FLW-01-59      Two terrace houses, end terrace and intermediate. Green brick with stone foundation, some sand stone pieces. Pre-1950 in date.

FLW-01-60      Row of three terrace houses. Green brick, single pitched roof. Pre-1950 in date.

FLW-01-61     Ruin of green brick house, portions of walls remaining. Pre-1950 in date.

FLW-01-62      Three green brick terrace houses. Single pitched roofs. Pre-1950 in date.

Ng Uk Tsuen  (Figure 10‑8a and Figure 10‑8b)

10.5.14   This village contained a number of traditional structures in various conditions, ranging from completely ruinous to inhabitable.

 

FLW-01-63      Tin Hau Temple, rebuilt in 1981. All modern features

FLW-01-64      Small earth god shrine consisting of wooden boards behind two stones, and brick incense holder

FLW-01-65      Courtyard terrace house. Decorative canopy and frieze on façade. Pre-1950 in date.

FLW-01-66      Two mixed brick terrace houses. Forecourts very overgrown. Single pitched roofs. Over 100 years in age.

FLW-01-67      Ruins of two courtyard terrace houses. Decorative canopies still intact, but poor condition. Over 100 years in age.

FLW-01-68      Courtyard style terrace house. mixed brick façade and rammed earth and render side walls. Collapsing roof. Pre-1950 in date.

FLW-01-69      Green brick and concrete (heavily altered) intermediate terrace. Canopy over doorway in fair condition. Portions of structure pre-1950 in date.

FLW-01-70      Section of brick wall and collapsed pounded earth section.

FLW-01-71      Green brick courtyard style unit with modern flat roof on front and added middle section on roof with access to front roof area.

FLW-01-72      Small single room pounded earth and render covered shed.  Pitched tile roof. Modern door and windows.

FLW-01-73      One mixed brick courtyard terrace house ruin Decorative canopy above door, very poor condition.   Pre-1950 in date.

FLW-01-74      Ruins of a green brick building, lower walls remaining in places.

FLW-01-75      Two courtyard style houses. Mixed brick and portions of walls covered in render. Approximately 100 years in age.

FLW-01-76      Modern Study Hall (Kwong Cheung Study Hall). Named after an ancestor.

FLW-01-77      Row of four courtyard style terrace houses. Green brick.  Over 100 years in age.

FLW-01-78      Three green brick courtyard style terrace houses. Stone foundations visible in two units. Decorative canopies, poor condition. Pre-1950 in date.

FLW-01-79      Modern Tse Tong (Wing Yick Tong). Two storey, tile exterior.

FLW-01-80      Row of four courtyard terrace houses. Green brick, decorative  canopies over the doorways. Pre-1950 in date.

FLW-01-81      Green brick, courtyard terrace style house, in ruins.  Façade intact with decorative canopy. Pre-1950 in date.

FLW-01-82      Well with shrine. Concrete platform. Granite blocks well lining.

FLW-01-83      Row of two green brick houses, courtyard terrace houses. Modern parapets 1965 and 1972 renovation dates. Original houses pre date 1950.

FLW-01-84      Row of two green brick terrace houses. Decorative canopies intact. Fung shui wall opposite. Pre-1950 in date.

FLW-01-85      Originally part of a row of eight terrace houses, two missing. green brick, mud brick, cement, modern materials. No decorative features. Built during the Japanese occupation according to local informant.

FLW-01-86      Originally a row of eight terrace houses. Two green brick, mud brick, cement, modern materials. No decorative features. Built during the Japanese occupation according to local informant.

FLW-01-87      Green brick terrace, no decorative features. Approximately 100 years old.

FLW-01-88      Village entrance gate. Pale green brick with tile and concrete roof. Wooden loft inside two shrines.

FLW-01-89      Earth god shrine in concrete area in front of rural committee building. Stones are set directly into the cement. Incense holder in ground.

FLW-01-90      Large Pak Kung shrine. Green brick, cut stone and cement.  Wok yee gable sides, recessed altar in rear wall, large platform for incense holder.

FLW-01-91      Kam Yan public school. Not in current use. brick, concrete and chunam exterior.

                        of the main entrance that were taken from a boat that ran aground in the area about 100 years ago.

FLW-01-92      Shrine in a concrete open area, cut stone blocks and incense holder. Large whetstone also set into concrete.

FLW-01-93      Mixed brick shed attached to rear of modern structure. Tile and concrete roof. Traditional building materials, but age indeterminate.

Burial Associated Sites

10.5.15   The elevated area behind the village of Ng Uk Tsuen, including the fung shui wood contains a number of graves, kam tap and coffin slots. The location of the grave area is highlighted in Figure 10‑9. None of the graves lie within the Study Area.

Fung Shui Features

10.5.16   A large area of fung shui wood is located behind the village of Ng Uk Tsuen. There are a mixture of tree species and many mature specimens. It is forbidden to cut trees in the area (according to local informant. The location of the fung shui wood is illustrated in Figure 10‑9. The limit of the fung shui wood is entirely outside of the Study Area.

Impact Assessment

Resources within the Study Area

10.5.17   The following impacts were considered for any built heritage features within the Study Area; visual/ aesthetic, changes in water table and damage from vibration during construction.

10.5.18   No historical buildings or structures, archaeological deposits, fung shui features or burial features were recorded within the Study Area. The development will therefore have no direct impacts.

Resources outside the Study Area

Table 101       The impacts associated with cultural heritage resources outside the Study Area

Resource

Description

Orientation/ Distance

Impact

Ng Uk Tsuen Village (including the Tin Hau temple)

 

(FLW-01-63 to FLW-01-93)

·        An historical village containing 37recorded cultural heritage resources, including a Tin Hau temple

·        The land between the village and the Study Area is wooded

·        The land surrounding the Tin Hau temple contains working concrete fishponds and woodland

Away from/ 250 m

 

No discernible impacts

Shing Uk Tsuen Village

(FLW-01-01 to FLW-01-25)

·        An historical village containing 25 recorded cultural heritage resources

·        There are numerous modern structures in the vicinity of the village

Away from/ 200 m

No discernible impacts

Tai Tseng Wai Village

(FLW-01-26 to FLW-01-62)

·        An historical village containing 31 recorded cultural heritage resources

·        The village is situated in a lowlying area

·        There are numerous modern structures in the vicinity of the village

Away from/ 350 m

No discernible impacts

Burial Associated Sites

·        Graves and kam tap associated with the local villages

·        Graves are located along hillsides overlooking the Study Area. The graves overlook the proposed development site.

Varied/ 100 m

No discernible Impacts

Fung Shui Woods

·        Mixed species woodland located behind the village of Ng Uk Tsuen still regarded as having fung shui importance (according to local informants)

Not Applicable/ 150 m

No discernible impacts

 

Mitigation Recommendations

Resources within the Study Area

10.5.19   There were no recorded resources in the Study Area, therefore, none of the above-mentioned impacts are relevant and no mitigation measures are required.

Resources outside the Study Area

Table 102       Mitigation Recommendations for Cultural Heritage Resources Outside the Study Area

Resource

Assessment Factors

Mitigation Recommendation

Ng Uk Tsuen Village

·        The Study Area is not visible from the village because of woodland and modern buildings

·        The village is oriented away from the Study Area

·        No further mitigation measures are necessary

Shing Uk Tsuen Village

·        The Study Area is not clearly visible from the village, as it is located in an area containing many modern housing units

·        The village is oriented away from the Study Area

·        No further mitigation measures are necessary

Tai Tseng Wai Village

·        The Study Area is not clearly visible from the village as it is situated in a lowlying area and the area immediately surrounding the village contains numerous modern housing units

·        The village is oriented away from the Study Area

·        No further mitigation measures are necessary

Graves

·        the graves lie outside the boundaries of the proposed development

·        the graves overlook the Study Area

·        No further mitigation measures are necessary

Fung Shui Wood

·        The fung shui wood lies outside the boundaries of the proposed development

·        No further mitigation measures are necessary

 

10.6          Historical Landscape Features Survey

Changing Historical Land use Patterns within the Deep Bay Area

10.6.1      The earliest useful map of this portion of the New Territories is the cadastral survey carried out by Newland in 1903. This map shows the deeply indented coastline of the southern shores of Deep Bay, fringed by mangroves (Irving Richard T.A. and Leung Kai Wing 1987).  The area of Fung Lok Wai is shown as swamp and marsh in 1903. The situation remains unchanged at least until 1913 as can be established from a topographical map (GEO old maps section). 

10.6.2      By 1924 survey maps and an aerial photograph, see Figure 10‑10 (GEO Ref.# Y00159) show a major reworking of the mangrove environment. The process of reclaiming mangrove swamp for rice cultivation was arduous and time-consuming. It required the clearance of paths in the mangroves along which bunds were constructed. These were built of mud dug from the swamp and piled over stones to a height of up to 3m and a width of 20m at the base.  Sluice gates were built into the walls to control drainage.

10.6.3      After initial draining, several years passed before cultivation was possible, during which salinity levels were gradually lowered by flushing with fresh stream water (Irving and Leung 1987).   When sufficiently low, a variety of brackish water tolerant rice known locally as “haam moon” was planted. This tolerant strain was relatively high yielding with a long growing season, which allowed only one harvest per year. The quality of the rice was poor and it was used primarily for the production of rice wine.

 

10.6.4      During the period between 1938 and 1945 the Deep Bay area was transformed into gei wai.   The only known account of how gei wais are constructed can be found in Richard T. A. Irving and Leung Kai Wing’s publication (1987). The gei wai's are shallow intertidal ponds enclosed in earth dykes with sluice gates. Each of the gei wai had channels running around its perimeter and across the centre which acted as sheltering areas for the shrimps. Between the channels were stands of mangrove, which were maintained for fuel wood. The gates allowed water to flood the gei wai at high tide in autumn and flush shrimp larvae into the pond. In April, when the shrimp were mature, the pond was drained at low tide and the shrimp caught in a net across the sluice gate. Over 20 kg of shrimp could be harvested from a gei wai each time, and each pond could be harvested many times from April to October when the season ended. The increase in reclamation for gei wais during these years seems to be related to the large number of refugees who came to Hong Kong following the Japanese invasion of China. Many of these new arrivals came from mangrove areas of the Pearl River such as His-hsiang, with a long tradition of shrimp cultivation in shallow ponds. It would seem likely that much of the knowledge and techniques were brought by such immigrants during this period. 

10.6.5      By 1974 the land use of the area was converted to ponds for raising fresh water fish. These ponds are substantially deeper than gei wai, measuring about 2 m deep. They exhibit a different impact on the landscape being stripped of vegetation while the shrimp ponds have mangroves growing in them. Shrimps are introduced naturally into the gei wai; however, the fishponds are completely enclosed and are stocked by the introduction of selected species. 

10.6.6      The tradition of fresh water fish cultivation in ponds goes back centuries in the New Territories. However, it was not until after the World War II and the introduction of pumping and stocking technology that intensive conversion to fishponds took place. The ponds are stocked with fry and then fertilized regularly until the fish are of marketable size. The pond is then drained and the fish netted. 

Recording of Historical Landscape Features within the Study Area

10.6.7      Figure 10‑11 shows the evolution of the bunds in the Study Area from 1924 to 2000.

10.6.8      In 1924 the areas along the landmass are small plots as can be established from the aerial photograph, see Figure 10‑10 (GEO Ref.# Y00159) and according to local informants were used for brackish rice cultivation.  The villagers rented these plots from the people of Shek Ha. The date of 1924 correlates with the local knowledge of the start of ponds about 80 years ago.

10.6.9      Even at this stage the basic plan of the Study Area of two parallel zones can be established. The most northern zone at this stage consists of large shallow plains divided by bunds.  The southern zone has smaller divisions and was mainly for fish and shrimp production according to the villagers. 

10.6.10   The same inherent pattern is evident in the 1949 aerial photograph (LD Ref# 6102 and 6181) and the 1957 topographical map (GEO old maps section). The strip along the landmass in 1949 was used for smaller agricultural cultivation, while the southern zone still had the small divisions but was in use as fish and shrimp ponds. The northern zone remained unchanged and still consisted of large marshy plains bordered by bunds.

10.6.11   The 1957 topographical map does not show the smaller plots along the landmass, but the zones are basically the same. While the aerial photograph dating back to 1963 shows that the small cultivation plots along the landmass were still in use (GEO Ref.#Y09690). The southern zone in 1963 shows along its southern border some small agricultural cultivation plots with smaller bunds and on its western side three largish ponds. However, the larger part of the southern zone consisted of very large gei wai's with some visible drainage channels.

10.6.12   The 1975 aerial photograph of the Study Area (LD Ref# 10972) shows flooded ponds at the southern end of the southern zone, while the rest are dry gei wai’s. The strip along the landmass and around the small hill by this time had been converted to functioning ponds. An aerial photograph dating back to 1983 (GEO Ref.#48647) indicates that at this time the Study Area had been divided into small to medium size plots and these were functioning fish and shrimp ponds.  The basic division of strip along the landmass, southern and northern zone remains.

10.6.13   Field evaluation of the Study Area in early 2001 concluded that the strip along the landmass too has been largely converted into functioning ponds. The local informant and evidence in the field indicates that the ponds have a depth of a couple of meters only, while no great conversion to fresh water ponds ever occurred. At present activities have largely ceased and most of the sluices seem to be no longer functional. Some of the bunds have been hardened for transport reasons, other bunds are more modest in appearance. These features are illustrated in the photographs in Figure 10‑12. 

10.6.14   The terminology used above to describe the landscape is ponds or gei wai’s.  The term gei wai is used for a shallow pond which has channels running around its perimeter and across its centre. These channels act as shelter areas for the shrimp. When ponds with gei wai characteristics could be established from the aerial photograph the term gei wai was used. However, if the gei wai or pond was filled with water and the shape of the pond could not be seen the more general term pond is used.

10.6.15   The use of different terms in this report refers to the specific shape of the pond or gei wai where it could be established. The literature and local knowledge both refer to shrimp and fish production as the function of the ponds in the Study Area.

Historical Landscape Features Impact Assessment

10.6.16   The literary evidence, local knowledge, maps and aerial photographs indicate that the area had a landscape of marshland at the beginning of the 20th century. The area has been in use for shrimp and fish cultivation from as early as 1924 as can be established from the aerial photograph.  Although the basic pattern of bunds has been retained, the pond sizes and shapes have been extensively changed over time.

10.6.17   The proposed construction and associated works will have a direct impact on the bunds. Some of the larger bunds have more or less existed in their original pattern since the start of the shrimp and fish cultivation. They are indicated in red on Figure 10‑11.

10.6.18   Upon the completion of the project, a large portion of the Site will be preserved as fish ponds, the existing fish pond landscape features will therefore be largely conserved.  As the preserved fish ponds will be managed following traditional aquaculture management practices, the cultural heritage of traditional fish farming will also be conserved at the same time.

Mitigation Recommendations for Impacted Resources

10.6.19   Because of the lack of information concerning the materials and methods used to construct the oldest bunds. It is recommended that during site formation when a bund is cut or a ' section' is exposed, the section shall be recorded. It is recommended that this would be a requirement at the site formation stage.

 

10.7          Summary of the CHIA Findings and Recommendations

Historical Buildings and Structures Survey

Findings and Assessment

·        There were no cultural heritage resources located in the Study Area. All structures were identified as modern squatter structures with no cultural heritage features

·        The three villages highlighted in the study brief were found to contain 93 cultural heritage resources

·        A number of graves were identified on the hill behind the village of Ng Uk Tsuen (outside of the Study Area)

·        A fung shui wood was identified behind the village of Ng Uk Tsuen (outside of the Study Area)

Recommendations

·        The Study Area contained no cultural heritage resources, thus, no mitigation measures are required

·        The cultural heritage resources outside the Study Area were found to warrant no further mitigation measures based on the following factors:

o        Adequate screening from the development site through existing woodlands, topographical setting and modern structures

o        Sufficient distance from the development site

o        Orientation away from the development site

 

Historical Landscape Features

Findings and Assessment

10.7.1      The assessment has found that although the basic pattern of the bunds was retained, the bunds have been extensively changed in size and shape.

Recommendations

10.7.2      In order to retrieve information concerning the composition of the bunds it is recommended that a brief recording exercise with methodology agreed with the Antiquities and Monuments Office be carried out during site formation.

10.8          References

1.       AMO published and unpublished files

2.       GEO Aerial Photograph Library and Old Maps Section

3.       Lands Department Aerial Photographs

4.       Chan Wai Yung 1993. An Analysis of the Policy on Building in tin Shui Wai New Town. Master of Public Administration Dissertation.

5.       Irving Richard T.A. and Leung Kai Wing 1987. Land-use and land-use change in the reclaimed coastal areas of Deep Bay.

6.       Irving Richard and Brian Morton 1988. A Geography of the Mai Po Marshes. World Wide Fund for Nature Hong Kong.

7.       Langford R.L., K.W. Lai, R.S. Arthurton and R. Shaw 1989. Geology of the Western New Territories. ( Hong Kong Geological Survey Memoir, 3), Geotechnical Control Office (CESD).

8.       Lee Chi Ming, Ng Suk Wan and To Lap Kee 1987. City on heavenly waters. An Evaluation of tin Shui Wai New Town Development. MSc. Group workshop report.

9.       Leung Wai Hung 1996.The Conservation of coastal  wetlands, especially the mai Po Marshes, in Hong Kong: Problems and prospects. MSc Dissertation University of Hong Kong.

10.   Melville D.S. and Brian Morton 1983. Mai Po Marshes. World Wildlife Fund Hong Kong.

11.   Parish Faizal 1997. The Asian Region. An Overview of Asian Wetlands. Hails A.J. (Ed.) Wetlands, Biodiversity and the Ramsar Convention, Chapter 4.

12.   Poon Sau Man 1997. Dredging and Reclamation Impact on Marine Environment in Deep Bay. MSc. Environmental Management University of Hong Kong.

13.   da Silva Armando M. 1977. Native Management of Coastal Wetlands in Hong Kong: A Case Study of Wetland Change at Tin Shui Wai Agricultural Lot, New Territories. Geography PhD Dissertation University of Hawaii.

14.   World Wildlife Fund 1985.The fascinating water’s edge. Hong Kong.

15.   Young Lew 1997. Mai Po Marshes: Conserving Wetland Biodiversity through Shrimp Farming. Hails A.J. (Ed.) Wetlands, Biodiversity and the Ramsar Convention, Chapter 4.


11.             LANDSCAPE AND VISUAL IMPACT ASSESSMENT

11.1          Introduction

11.1.1      The aim of this section of the report is to describe legislation and guidelines that will be reviewed in the LVIA.  The landscape baseline reviews the condition of existing landscape resources (LRs) and landscape character areas (LCAs), planning and development control framework, and the visual amenity and visually sensitive receivers (VSRs).  The assessment identifies potential landscape and visual impacts that would occur during the construction and operational phases of the proposed development at Fung Lok Wai, recommends landscape mitigation measures to alleviate the impacts; and identifies residual effects apparent after mitigation. This section also outlines any cumulative impacts arising from the proposed development and concurrent projects.

11.2          Standards and Legislation

11.2.1      Legislation, Standards, Guidelines and Criteria relevant to the consideration of landscape and visual impacts in this report include the following:

·        Environmental Impact Assessment Ordinance;

·        Technical Memorandum on Environmental Impact Assessment Process;

·        EIAO Guidance Notes 8/2002 on Preparation of Landscape and Visual Impact Assessment under the EIAO.

·        WBTC No. 3/2006 on Management and Maintenance of Natural Vegetation and Landscape Works and Tree Preservation;

·        WBTC No. 7/2002 on Tree Planting in Public Places;

·        ETWB TCW No. 2/2004 Maintenance of Vegetation and Hard Landscape Features.

·        Final Report of Study on the Ecological Value of Fish Ponds in Deep Bay Area (Planning Department, September 1997)

11.2.2      These are described in detail below:

Environmental Impact Assessment Ordinance

11.2.3      The Environmental Impact Assessment Ordinance (EIAO) was implemented on 1 April 1998. Its purpose is to avoid, minimise and control the adverse impact on the environment of designated projects, through the application of the EIA process and the Environmental Permit (EP) system.

Technical Memorandum on Environmental Impact Assessment Process

11.2.4      The landscape and visual impact assessments have been carried out in accordance with the guidelines contained in Annexes 10 and 18 of the Technical Memorandum on EIA Process. 

EIAO Guidance Notes 8/2002 on Preparation of Landscape and Visual Impact Assessment under the EIAO

11.2.5      The guidance note (GN) advises on the requirements in vetting Landscape and Visual Impact Assessment (LVIA) of designated projects (DPs) under the Technical Memorandum on EIA Process (EIAO-TM) for the Environmental Impact Assessment (EIA) Ordinance. The main aim is to facilitate practitioners to prepare LVIA and to satisfy their own Quality Management System prior to making submissions under the EIA Ordinance.

WBTC No. 3/2002 on Management and Maintenance of Natural Vegetation and Landscape Works and Tree Preservation

11.2.6      This Circular defines the management and maintenance responsibilities for natural vegetation and landscape works, including both softworks and hardworks, and the authorities for tree preservation and felling.

WBTC No. 7/2002 on Tree Planting in Public Works

11.2.7      This Circular affirms the advocated policy on tree planting which adopts a flexible and balanced approach in the planning and design of public works.

ETWB TCW No. 3/2006 Tree Preservation

11.2.8      This Circular defines the management and maintenance responsibilities for natural vegetation and landscape works, including both softworks and hardworks, and the authorities for tree preservation and felling.

Final Report of Study on the Ecological Value of Fish Ponds in Deep Bay Area (Agreement No. CE 72/94, Planning Department, September 1997.

11.2.9      This Study reviews the past ecological and landuse changes in Deep Bay Area and assesses the cumulative impact on carrying capacity of changes of landuse within the Study Area. The Study also reviews the appropriateness of the Buffer Zone 1 and 2 boundaries and considers alternative beneficial uses apart from fish farming. The Study sets out guidelines for wetland creation, restoration and new development sites within the Study Area.

 

11.3          Landscape and Visual Impact Assessment Methodology

Landscape Impact Assessment Methodology

11.3.1      Preparation of LVIA is based on the EIAO GN 8/2002 “Preparation of Landscape and Visual Impact Assessment under the EIAO” for evaluation of the proposed development options at Fung Lok Wai including access road options.  The landscape and visual impact considerations concerning the selection of an access road alignment to the development site is discussed in Section 3.  The methodology for the LVIA and the selection of preferred development options is described in the following sections.

Selection of Preferred Development Option

11.3.2      The description of alternative development options provided in Section 3 of this report includes a consideration of the development constraints, the alternative master plan layouts with different building height for three master layout options and two access road options.

Landscape Planning Review

11.3.3      A review of the existing planning studies and documents will be undertaken as part of the baseline study to gain an insight into the planned role of the site, its surrounding areas, and its landscape context and to help determine the projects fit into the wider existing and future landscape context. This review considered Outline Zoning Plan numbers S/YL-LFS/7, Lau Fau Shan and Tsim Bei Tsui; S/TSW/11 Tin Shui Wai; S/YL-PS/11 Ping Shan and S/YL/17 Yuen Long. Compatibility of the proposed development to the planned developments either within or adjacent to the Study Area are also considered in terms of landscape and visual impacts.

Landscape Baseline Review and Impact Assessment

11.3.4      The assessment of the potential impacts of a proposed scheme on the existing landscape comprises two distinct sections namely the baseline survey and the landscape impact assessment. Landscape Impact Assessment (LIA) Study Area is taken to include all areas within 500m of the site boundary.

11.3.5      A baseline survey of the existing landscape resources and landscape character has been undertaken based on a combination of desktop studies and site surveys. The landscape elements which contribute to the landscape character include:

·        Local topography;

·        Woodland extent and type; 

·        Other vegetation types;

·        Built form;

·        Patterns of settlement;

·        Land use;

·        Scenic spots;

·        Details of local materials, styles, streetscapes, etc.;

·        Prominent watercourses; and

·        Cultural and religious identity

11.3.6      The process of landscape characterisation draws on the information gathered in the desk top and site survey and provides an analysis of the way in which the elements including the identified landscape resources (LRs) interact to create the character of the landscape. The Study Area is then divided into broadly homogenous units of similar character which are called Landscape Character Areas (LCAs). 

11.3.7      The sensitivity of the individual LRs and LCAs to change is rated using low, medium or high depending on the following factors:

·        Condition, quality and maturity of the LRs / LCAs ;

·        Importance and rarity of special landscape elements (rarity being of either local, regional, national or global importance);

·        Ability of the LRs / LCAs to accommodate change; and

·        Statutory or regulatory requirements relating to the landscape including its resources.

11.3.8      The next stage of the assessment process is the identification of the assessment of the magnitude of change (rated as negligible, small, intermediate or large) arising from the implementation of the proposals and the principal sources of impact based on the following factors:

·        Scale of the development and proposed access road;

·        Compatibility of the project with the surrounding landscape;

·        Duration of impacts (temporary or permanent) under construction and operational phases; and,

·        Reversibility of change.

11.3.9      The degree of significance of landscape impact is derived from the magnitude of change which the proposals will cause to the existing landscape context and its ability to tolerate the change, i.e. its condition / quality and sensitivity. This makes a comparison between the landscapes which would have existed in the absence of the proposals with that predicted as a result of the implementation of the proposals. The significance threshold for impacts to LRs and LCAs is rated as significant, moderate, slight or negligible. The impacts may be beneficial or adverse.

11.3.10   The significance threshold is derived from the following matrix:

Magnitude of Change caused by Proposals

Large

Moderate Impact

Moderate / Significant Impact

Significant Impact

Intermediate

Slight or Moderate Impact

Moderate Impact

Moderate or Significant Impact

Small

Slight Impact

Slight or Moderate Impact

Moderate Impact

Negligible

Negligible

Negligible

Negligible

 

Low

Medium

High

 

Sensitivity of Landscape to Change

 

11.3.11   The above matrix will apply in the assessment of the majority of situations, however, in certain cases a deviation from this may occur, e.g. the impact may be so major that a significant impact may occur to a LCA or LR with a low sensitivity to change.

Tree Survey Methodology

11.3.12   To minimise conflicts with existing vegetation a preliminary tree survey has been completed in broad accordance with ETWB TCW No. 3/2006 Management and Maintenance of Natural Vegetation and Landscape works and Tree Preservation. This ‘broad brush’ tree survey involves the identification of significant individual trees within the site boundary. In accordance with normal practice the tree survey has been confined to the site boundary as the trees beyond will not be affected by the proposed works. The assessment of the identified landscape character areas also includes a reference to the existence of trees within each area and their contribution to the establishment of that character. The existing trees are categorised into four tree groups according to their location and their potential conflict with different parts of the proposed scheme.  Tree groups include trees inside the development area, wetland nature reserve (at where bund to be removed), wet land reserve (at where bund to be retained) and the alternative egretry. The survey includes approximate numbers of trees, their species, sizes range, health condition, form, and amenity value inside each tree group. This will allow the fine tuning of the detail design for the proposed scheme and ensure that any significant trees, will where possible, be protected during both the construction and operational phases of the project.

Visual Baseline Review and Impact Assessment

11.3.13   The assessment of the potential visual impact of the scheme comprises two distinct parts:

·        Baseline survey; and,

·        Visual impact assessment which includes the identification of the sources of visual impact, and their magnitude, that would be generated during construction and operational phases of the proposed scheme; and, identification of the principal visual impacts primarily in consideration of the degree of change to the baseline conditions.

11.3.14   The assessment area for the Visual Impact Assessment (VIA) in accordance with the study brief, is defined by the 2-km Visual Envelope (VE) which includes all areas from which the scheme proposals can be seen, or the area forms the view shed formed by natural / manmade features such as existing ridgelines, built development and for example areas of woodland / large trees.  Within the VE a number of Zones of Visual Influence (ZVIs) are identified to demonstrate the visibility of various aspects of the scheme proposals.  This is achieved through a combination of detailed walkover surveys, and desk-top study of topographic maps and photographs, and preparation of cross-sections to determine visibility of the improvement works from various locations.

11.3.15   The baseline survey of all views towards the proposals is undertaken by identifying:

·        The VE and ZVIs as has been described above and may contain either wholly or partially within views. This must also include indirect effects such as offsite construction activities; and,

·        The visually sensitive receivers (VSRs) within the visual envelope whose views will be affected by the scheme.

11.3.16   The potential receivers are considered as four groups:

·        Views from residences – the most sensitive of receivers due to the high potential of intrusion on the visual amenity and quality of life;

·        View from workplaces – less sensitive than above due to visual amenity being less important within the work environment;

·        Views from recreational landscapes – including all areas apart from the above, e.g., public parks, recreation grounds, footpaths, cultural sites etc. Sensitivity of this group depends on the length of stay and nature of activity, e.g. sitting in a park as opposed to an active sporting pursuit; and

·        Views from public roads and railways – including vehicle travellers with transitory views.

11.3.17   The assessment of sensitivity is also based on the quality and extent of the existing view. Therefore a view from a residential property, which would normally be considered the most sensitive view, may be less so if for example it is degraded by existing development or partially screened by intervening visual obstacles such as existing vegetation. Factors affecting the sensitivity of receivers for evaluation of visual impacts:

·        Value and quality of existing views;

·        Availability and amenity of alternative views;

·        Type of receiver population and estimated number of affected receiver population;

·        Duration or frequency of view; and,

·        Degree of visibility.

11.3.18   The location and direction of its view relative to the scheme also influences the sensitivity of each group. Typical viewpoints from within each of the visually sensitive groups are identified and their views described. Both present and future (planned visually sensitive receivers (PVSRs) are considered.

11.3.19   The factors affecting the magnitude of change for assessing the visual impacts include the following:

·        Scale of the development and proposed access road;

·        Compatibility of the project with the surrounding landscape forming the view;

·        extent of visibility (level of potential blockage of the view described in the text);

·        Viewing distance;

·        Duration of impacts under construction and operational phases;

·        Reversibility of change ; and

·        Night glare effect.

11.3.20   Views available to the identified VSRs are rated according to their sensitivity to change using low, medium or high. The magnitude of change to the views will be classified as follows:

·        Large : e.g. the majority of viewers affected / major change in view;

·        Intermediate: e.g. many viewers affected / moderate change in view;

·        Small: e.g. few viewers affected / minor change in view; and

·        Negligible: e.g. very few viewers affected / no discernible change in view.

11.3.21   The significance threshold for visual impact is rated in a similar fashion to the landscape impact, i.e. significant, moderate, slight and negligible. The impacts may be beneficial or adverse.

11.3.22   Therefore the impact is derived from the magnitude of change which the proposals will cause to the existing landscape context and its ability to tolerate the change, i.e. its quality and sensitivity. The significance threshold is derived from the following matrix:

Magnitude of Change caused by Proposals

Large

Moderate Impact

Moderate / Significant Impact

Significant Impact

Intermediate

Slight / Moderate Impact

Moderate Impact

Moderate / Significant Impact

Small

Slight Impact

Slight / Moderate Impact

Moderate Impact

Negligible

Negligible

Negligible

Negligible

 

Low

Medium

High

 

Sensitivity of View to Change

 

11.3.23   The above matrix will apply in the assessment of the majority of situations, however, in certain cases a deviation from this may occur, e.g. the impact may be so major that a significant impact may occur to a view with a low sensitivity to change.

11.3.24   Table 111 below provides an explanation of the degree of impact for both landscape and visual aspects of the project.

Table 111       Degree of Impact

Impact

Description

Significant

Adverse / beneficial impact where the proposal would cause significant deterioration or improvement in existing landscape quality or visual amenity.

Moderate

Adverse / beneficial impact where the proposal would cause a noticeable deterioration or improvement in existing landscape quality or visual amenity.

Slight

Adverse / beneficial impact where the proposal would cause a barely perceptible deterioration or improvement in the existing landscape quality or visual amenity.

Negligible

No discernible change in the existing landscape quality or visual amenity.

Landscape Mitigation Measures

11.3.25   The purpose of mitigation is to avoid, reduce, and where possible remedy or offset any adverse effects on the environment arising from the proposed development. The ideal strategy for identifiable adverse impacts is avoidance. If this is not possible, alternative strategies of reduction, remediation and compensation should be explored.

11.3.26   Mitigation measures may be considered under two categories:

·        Primary mitigation measures that intrinsically comprise part of the development design through an iterative process. This form of mitigation is generally the most effective; and

·        Secondary mitigation measures designed to specifically address the remaining (residual) adverse effects of the final development process.

11.3.27   Primary mitigation measures form integrated mainstream components of the project design focusing on the adoption of alternative designs or revisions to the basic engineering and architectural design to prevent and/or minimise adverse impacts including siting, access, layout, buildings and structures etc. The design philosophy can also describe the benefits to the design of alternative solutions, introduced to reduce potential adverse impacts, and indicate how these have been addressed.

11.3.28   Secondary mitigation measures are specifically designed to mitigate the adverse impacts of the final development and are considered in the assessment of the landscape and visual impacts.  These may take the form of remedial measures such as colour and textural treatment of building features; and compensatory measures such as the implementation of landscape design measures (e.g. tree planting, creation of new open space etc) to compensate for unavoidable adverse impacts and to attempt to generate potentially beneficial long-term impacts. 

Residual Impacts

11.3.29   The Residual impacts are those, which remain after the proposed mitigation measures, have been implemented. This has been assessed both during the construction period and during the design year which is often taken to be 10 to 15 years after the proposed scheme has been opened to normal operation when the soft landscape mitigation measures are deemed to have reached a level of maturity which allows them to perform their original design objectives.

11.3.30   The level of impact is derived from the magnitude of change which the proposals will cause to the view which would have existed during this period if the proposed scheme had not been constructed and its ability to tolerate change, i.e. its quality and sensitivity taking into account the beneficial effects of the proposed mitigation. The significance threshold is derived from the matrices described separately above for the landscape and visual impacts.

11.3.31   In accordance with Annex 10 of the EIAO-TM a final conclusion is also made of the residual landscape and visual impacts attributable to the proposed scheme. The degree of residual impact is considered in accordance with the Residual Impact Significance Threshold Matrix in Table 112 below.

Table 112       Residual Impact Significance Threshold Matrix

Residual Impact

Description

Beneficial

The project will complement the landscape and visual character of its setting, will follow the relevant planning objectives and will improve overall and visual quality.

Acceptable

There will be no significant effects on the landscape and no significant visual effects caused by the appearance of the project, or no interference with key views.

Acceptable with mitigation

There will be some adverse effects, but these can be eliminated, reduced or offset to a large extent by specific measures.

Unacceptable

The adverse affects are considered too excessive and are would not be reduced to an acceptable level by mitigation.

Undetermined

Significant adverse effects are likely but the extent to which they may occur or may be mitigated cannot be determined from the study. Further detailed study will be required for the specific effects in question.

 

Graphic Presentation of Mitigation Measures

11.3.32   In order to illustrate these landscape and visual impacts and to demonstrate the effectiveness of the proposed landscape and visual mitigation measures, photomontages at selected representative viewpoints, agreed with Planning Department at the outset of the study, have been prepared to illustrate:

·        Existing conditions;

·        Year 1 of Operation Phase without Landscape Mitigation Measures;

·        Year 1 of Operation Phase with Landscape Mitigation Measures; and,

·        Year 10 of Operation Phase with Landscape Mitigation Measures.

 

11.4                Selection of the Preferred Option

Alternative Schemes

11.4.1      The process of selecting a preferred option for the development considered a number of alternative options and designs based on the initial findings of the various assessments not least the Ecological Impact Assessment (EcoIA). This process is described in greater detail in Section 3 of this report. These options included both alternative footprint locations and alternative building height scenarios as shown on Figures 3-3 A to C and Figure 11-1A,11-1B, 11-1C and 11-1D.            

Alternative Footprint Location

11.4.2      In order to avoid the flight path of birds to and from an egretry identified during the EcoIA the building footprint for the development was relocated approximately 150m to the east. This relocation of the building footprint also serves to increase the area of green buffer between the proposed residential development and the existing high-rise development associated with Tin Shui Wai when viewed from locations to the north.  This is important in maintaining the visual separation between the two developments reinforcing the effect of a patchwork of development separated by existing green features. It is also important to maintain as far as possible the green edge to the fishpond area emphasising the naturalistic transition between traditional fishpond and wooded hill slopes.

11.4.3      The development site is located on the southern periphery of the traditional fishponds which characterise the low lying coastal plain of the Deep Bay bisected by the Sham Chun and Shan Pui Rivers to the northwest of the New Territories. The landscape character of this area is formed by a largely undeveloped flat expanse of the fishponds bounded by the upright form of the surrounding hill sides. The visual relationship between the fishponds, the mud flats and the wooded hills sides is important to the landscape character of the area.

Alternative Building Height Profiles

11.4.4      In accordance to the requirements of Clause 3.5.9.5 (iv) under the Landscape and Visual Impact section of the Study Brief, alternative building heights for the preferred footprint location, ranging from 10 storeys to 25 storeys, were assessed to examine the Development’s visual compatibility with the surrounding rural setting. The three building height scenarios assessed were:

·         Option 1A – all buildings not more than 18 storeys (8 blocks of 14-18 storeys, 7 groups of low-rise buildings of 4-8 storeys including a 2 storey resident’s club house);

·         Option 1B – all buildings not more than 15 storeys (9 blocks of 15 storeys, 7 groups of low-rise buildings of 4-10 storey including a 2 storey resident’s club house); and

·         Option 1C – all buildings not more than 10 storeys (29 blocks of 7-10 storeys, 27 4-storey terrace houses and a two storey resident’s club house).

Option 1A

11.4.5      Option 1A (refer to Figure 111A) adopts a medium-rise form utilising a stepped building height profile (14 to 18 storeys) in response to the existing landform and maximises visual permeability through the creation of view corridors and voids within the building form allowing visual access to the hillsides beyond. Option 1A is the only one of the three options which is able to accommodate the voids within development façade of each of the blocks. The view corridors form the location for the low-rise buildings between the proposed medium-rise blocks. The proposed stepped edge to the eastern and western periphery of the development resonates with the form of the existing hills which rise from the flat plane of the Deep Bay and its estuarine / maritime landscape. This is evident in the descending form of the eastern and westernmost blocks from 18 to 14 storeys creating a stepped effect. The medium-rise building with stepped form and its development footprint allow the minimisation of potential impacts to the existing landscape and visual resources particularly in relation to the existing fishponds and hills which form the backdrop.

Option 1B

11.4.6      The medium-rise form of Option 1B (15 storeys) incorporates blocks of equal height (15 storeys) and will not incorporate the stepped building height profile adopted for Option 1A (refer to Figure 11-1A). Although the utilisation of a constant height (15 storeys) for the individual blocks will not create the same dynamic relationship in terms of the building form with the existing landscape context which exists with Option 1A. Similar to option 1A the creation of a permeable and responsive building form preserves, as far as possible, the visual relationship between the existing estuarine landscape and its setting of wooded hillsides. Sharing the same residential development site area as Option 1A the direct loss of landscape resources has been minimised as far as possible.

Option 1C

11.4.7      Option 1C (7 to 10 storeys) although when viewed from a distance more akin to the traditional vernacular village architecture of the region in terms of its form the proposed blocks are considerably higher than the traditional village houses (refer to Figure 11-1A). The development does not respond to the visual dynamics of the existing landscape context. In addition when viewed from the north the development visually coalesces to form a wall with no visual access to the landscape beyond. Of the three options this development uses the most extensive area to accommodate the built development and so has a corresponding smaller area available for soft landscape measures.

Selection of a Preferred Option

11.4.8      The selection of the preferred option requires a balanced view of the environmental factors particularly those relating to the ecology of the Study Area which is considered in Section 3 above. The ecological impact assessment determined the location of the footprint for the development however the building height profile for the preferred option also considered the potential landscape and visual impacts. A comparison of the three options is shown on Table 11-3.

11.4.9      Of the three development forms options 1A and 1B were considered preferable from a landscape and visual impact perspective. This was mainly due to the reduced number of medium-rise blocks providing view corridors to maximise the degree of visual access which these options allow to wooded hill sides to the south of the development site thus preserving the link between the fishponds and their landscape context. The building profile of option 1A also responds to the form of the existing topography to a greater degree than the other alternative option 1C creating a development which is both visually interesting and visually permeable. This includes the incorporation of voids within each of the blocks. The height profile of options 1A and 1B mirror the line of the ridgeline to the south looking from the site boundary in the north as illustrated on Figure 111A creating a dynamic relationship with the existing landscape context something which few other developments in the local area achieve.

11.4.10   In addition, for both Options 1A and 1B the smaller building clusters and their non-linear layout create intimate landscaped courtyards between buildings and minimise the wall effect which could potentially arise from the development proposals which form the basis of Option 1C in responding to the surrounding rural context.

11.4.11   The use of the varied building height and form of the overall development is also in tune with Planning Department’s guidance as detailed in the Urban Design Guidelines for Hong Kong (November 2002).  The height issue is less of a concern in terms of the buildings relationship to the existing ridgeline as for most views the proposals leave the ridgeline visually intact.

11.4.12   Following the selection of the preferred options 1A and 1B the design for each option was further refined in response to an iterative assessment process with the selection of the proposed southern development access in preference to the original western development access which skirted the fishpond area to the north of the development site. The western access road would have led to the further loss of the fishponds an important landscape resource, the loss of physical and visual integrity of the remaining fishpond area, and the loss of the tranquillity which forms an important characteristic of the landscape of the Study Area. Whereas the southern development access will follow the alignment of the existing Fuk Shun Street through Tai Tseng Wai minimising potential impacts to the existing landscape context of the Study Area.


Table 113       Alternative Schemes Comparison

Evaluation Criteria

Option 1A

Option 1B

Option 1C

Scheme Description

 

 

 

Residential Site Area

40,000m2

40,000m2

60,000m2

Site Coverage

32.8%

34.4%

34%

Number of Building Blocks

8 blocks with 14-18 storeys (each block adopting a stepped height profile), 7 groups of low-rise buildings of 4-8 storeys including a 2 storey resident’s club house (to maximise the size of the visual corridor between blocks).

9 blocks with 15 storeys, 7 groups of low-rise buildings of 4-10 storey including a two storey resident’s club house (to maximise the size of the visual corridor between blocks).

29 blocks with 7-10 storeys, 27 4-storey terrace houses and a 2 storey resident’s club

Number of Storeys

All buildings not more than 18 storeys

All buildings not more than 15 storeys

All buildings not more than 10 storeys

Building Orientation

Zigzag Layout

Medium-rise buildings distributed in a zigzag arrangement with low-rise building groups between the proposed medium-rise blocks.

 

Zigzag Layout

Medium-rise buildings distributed in a zigzag arrangement with low-rise building groups  between the proposed medium-rise blocks.

 

 

Linear Layout

7-10 storeys buildings evenly distributed along the eastern side of the boundary and low-rise terrace houses concentrated along the western edge.

 

View Corridors

8 blocks with 7 wider view corridors ranging in width from 29.4m to 31.3m.

9 blocks with 8 narrower view corridors ranging in width from 15.6m to 26.2m.

Continuous building form with no view corridors. The low-rise approach involves the use of an extensive, narrow site. The form of the site does not allow for the grouping of these low-rise buildings to create view corridors.

Visual Mass of Structure and Permeability

Maximises visual permeability through the creation of view corridors allowing visual access to the hillsides beyond. The view corridors are formed through the location of the low-rise building groups between the proposed medium-rise blocks. Option 1A also incorporates significant voids within the structure of each of the proposed blocks further enhancing visual permeability. These voids will contain sky gardens. Option IA is therefore more permeable than Options 1B and 1C due the size of the proposed view corridors.

Maximises visual permeability through the creation of view corridors allowing visual access to the hillsides beyond. The view corridors are formed through the location of the low-rise building groups between the proposed medium-rise blocks.

 

Although visually more akin to the traditional vernacular village architecture of the region in terms of its form when viewed from a distance, the proposed blocks are considerably higher than the traditional village houses. The eastern building cluster the blocks also forms a single visual entity negating the principle of adopting a permeable edge.

Building Profile

Each medium-rise block has a stepped height profile from 14 to 18 storeys in three steps. This stepped approach is designed to provide a better sense of integration with the surrounding landscape context and a more visually interesting built form. Due to the orientation of the blocks the stepping is apparent at the eastern and western ends of the development and in the interface with the pond area to the north of the development site. The proposed development will also incorporate seven groups of low-rise buildings with four clusters located along the south eastern boundary of the site to create a more subtle transition between the proposed development and the village houses to the south. The other three groups including the 2 storey resident’s club will be located adjacent to the noth west potion of the site boundary will have similar effect with the transition to the proposed marsh area.

 

The roofline is maintained at a consistent height of 15 storeys. This produces a flat roofline which appears visually incongruous when viewed against the organic form of the natural landscape backdrop. This development option will also incorporate five groups of low-rise buildings located along the south eastern boundary and two groups including the 2 storey resident’s club located adjacent to the noth west potion of the site boundary.

 

The height of the blocks range from 7 to 10 storeys with the lower blocks located to the east and west of the development to create less abrupt building edge and improve its integration within the landscape. However this stepped height profile is not readily apparent in many views due to the proximity of the blocks to one another and the viewing distances involved. This option will incorporate 4 storey high terraced housing and the 2 storey resident’s club along the north western boundary of the site adjacent to the proposed marshland area. Again these structures will create a limited stepped effect although when viewed from the majority of view points the blocks will visually merge with the terraced housing due largely to the viewing distance.

 

 

 

 

Landscape Impacts

 

 

 

Existing Trees

Total number of trees: 665

Retained trees: 238 (36%)

Transplanted trees: 28 (4%)

Felled trees: 399 (60%)

Total number of trees: 665

Retained trees: 238 (36%)

Transplanted trees: 28 (4%)

Felled trees: 399 (60%)

Total number of trees: 665

Retained trees: 231 (35%)

Transplanted trees: 28 (4%)

Felled trees: 406 (61%)

Landscape Resources

Main impacts:

LR 1 – Landform: approx. 4.6 ha

LR 8 – Fishponds: approx. 4 ha

LR 10 – Watercourses: 800m2

 

Main impacts:

LR 1 – Landform: approx. 4.6 ha

LR 8 – Fishponds: approx. 4 ha

LR 10 – Watercourses: 800m2

 

Main impacts:

LR 1 – Landform: approx. 4.6 ha

LR 8 – Fishponds: approx. 6 ha

LR 10 – Watercourses: 800m2

 

Landscape Character

Main direct impacts:

Fishponds (AGR 2): Moderate adverse impact

(Due to the loss of area and the indirect impacts on the character of the remaining fishponds).

Indirect impacts:

Kai Shan Range (NUA 1): Moderate adverse and the settlements of the Ng Uk Tsuen Village Cluster (V1): Slight Adverse.

Other impacts largely negligible due to the remoteness of the site from the identified character areas (Hong Kong Wetland Park (OS 1), Yuen Long Industrial Estate (ICA 1) and Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel (EL1)). 

 

Main direct impacts:

Fishponds (AGR 2): Moderate adverse impact

(Due to the loss of area and the indirect impacts on the character of the remaining fishponds).

Indirect impacts:

Kai Shan Range (NUA 1): Moderate adverse and the settlements of the Ng Uk Tsuen Village Cluster (V1): Slight Adverse.

Other impacts largely negligible due to the remoteness of the site from the identified character areas (Hong Kong Wetland Park (OS 1), Yuen Long Industrial Estate (ICA 1) and Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel (EL1)). 

 

Main direct impacts:

Fishponds (AGR 2): Significant adverse impact

(Due to the truncation of the fishponds from the wooded hill sides which form their setting, the loss of area and the indirect impacts on the character of the remaining fishponds).

Indirect impacts:

Kai Shan Range (NUA 1): Moderate adverse and the settlements of the Ng Uk Tsuen Village Cluster (V1): Slight Adverse..

Other impacts largely negligible due to the remoteness of the site from the identified character areas (Hong Kong Wetland Park (OS 1), Yuen Long Industrial Estate (ICA 1) and Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel (EL1)). 

 

 

 

 

Visual Impacts

Main impacts:

The residents of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) (approximately 10 houses in each case) living at the northern periphery of the villages with windows facing north towards the development site: Moderate to significant adverse.

For other residents of the villages, pedestrians within open spaces and vehicle travellers the impacts are likely to be slight to moderate adverse due to the screening effect of adjacent village houses, the angle and viewing distance, and the proximity of existing vegetation.

Slight / moderate adverse impact: Long Ping Estate (VSR 9) and Tin Tsz Estate (VSR 10), Whereas the other VSRs including Tin Shui Wai (VSR 1), Tsim Bei Tsui (VSR 2), Fairview Park (VSR 4), Tai Sang Wai (VSR 5), Kai Shan (VSR 8) Kenwood Court (VSR 11), Tin Yuet Estate (VSR 12), Vianni Cove (VSR 14) and Grandeur Terrace (VSR 15) would experience a moderate adverse impact mitigated to an extent by the expansive nature of the existing views, the viewing angle and distance, and the design and disposition of the proposed scheme. 

Slight adverse: Mong Tseng Wai (VSR 3), due to the low lying nature of these VSRs, the screening effect of the intervening landform and vegetation, and the viewing angle and distance.  

 

Main impacts:

The residents of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) (approximately 10 houses in each case) living at the northern periphery of the villages with windows facing north towards the development site: Moderate to significant adverse.

For other residents of the villages, pedestrians within open spaces and vehicle travellers the impacts are likely to be slight adverse due to the screening effect of adjacent village houses, the angle and viewing distance, and the proximity of existing vegetation.

Slight / moderate adverse impact: Long Ping Estate (VSR 9) and Tin Tsz Estate (VSR 10), Whereas the other VSRs including Tin Shui Wai (VSR 1), Tsim Bei Tsui (VSR 2), Fairview Park (VSR 4), Tai Sang Wai (VSR 5), Kai Shan (VSR 8) Kenwood Court (VSR 11), Tin Yuet Estate (VSR 12), Vianni Cove (VSR 14) and Grandeur Terrace (VSR 15) would experience a moderate adverse impact mitigated to an extent by the expansive nature of the existing views, the viewing angle and distance, and the design and disposition of the proposed scheme. 

Slight adverse: Mong Tseng Wai (VSR 3), due to the low lying nature of these VSRs, the screening effect of the intervening landform and vegetation, and the viewing angle and distance.

Main impacts:

The residents of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) (approximately 10 houses in each case) living at the northern periphery of the villages with windows facing north towards the development site: Moderate to significant adverse.

For other residents of the villages, pedestrians within open spaces and vehicle travellers the impacts are likely to be slight adverse to negligible due to the reduced height of the proposed development.

Slight / moderate adverse impact: Long Ping Estate (VSR 9) and Tin Tsz Estate (VSR 10),

Whereas the other VSRs including Tin Shui Wai (VSR 1), Tsim Bei Tsui (VSR 2), Fairview Park (VSR 4), Tai Sang Wai (VSR 5), Kai Shan (VSR 8) Kenwood Court (VSR 11), Tin Yuet Estate (VSR 12), Vianni Cove (VSR 14) and Grandeur Terrace (VSR 15) would experience a moderate adverse impact mitigated to an extent by the expansive nature of the existing views, the viewing angle and distance, and the design and disposition of the proposed scheme. The visual impacts for Tsim Bei Tsui (VSR 2) more pronounced due to the large site area. 

Slight adverse: Mong Tseng Wai (VSR 3), due to the low lying nature of these VSRs, the screening effect of the intervening landform and vegetation, and the viewing angle and distance.  

 

 

 

 

 

 

Description of Preferred Options 1A and 1B

11.4.13   Option 1A

11.4.14   The proposed scheme consists of eight blocks of maximum 18 storeys, and 7 groups of low-rise buildings (4-8 storeys) including a two storey club house. It involves a minimum landtake for residential development so as to reduce the disturbance to the preserved fish ponds.  The low-rise buildings are arranged in the space between the medium-rise building clusters creating a more subtle transition between the development and the surrounding landscape particularly the existing fishponds to the north.  These low-rise buildings are arranged to have irregular frontages creating visual interest. The medium-rise blocks are arranged with four on an east-west axis and four on a north-south axis designed to maximise the visual permeability of the development when viewed from the main concentrations of VSRs from the west (Tin Shui Wai) and from the east (developments such as the Fairview Park).   With the low-rise buildings located between these clusters and a clubhouse in the central portion of the site. With this arrangement seven view corridors are created between the medium-rise building blocks. The building height profile for the proposed medium-rise blocks is designed to rise from 14 to 18 floors in each block designed to create stepped building profile for each. The lower portion of each is arranged to face the wetland to the north and hence soften the transition from the existing fishponds to the proposed development.

11.4.15   The proposed view corridors bisect the medium-rise development to create seven distinct medium-rise building blocks with 7 groups of low-rise buildings sitting in between allowing visual access to the landscape of wooded hillsides to the south of the proposed development. These view corridors are orientated to provide maximum benefit in views from the main concentrations of visually sensitive receivers particularly when viewed from the northern part of Tin Shui Wai. In addition to containing the proposed low-rise buildings these view corridors also contain the key landscape features such as the proposed clubhouse, children’s playgrounds and gardens. The car park will be located in basement in order to minimise potential adverse landscape and visual impacts, and maximise the area available for landscaping.

11.4.16   Another innovative design feature of Option 1A is the incorporation of voids within each of the blocks which serve to further enhance the visual permeability of the scheme. These voids are arranged to create an architectural rhythm in the treatment of the facades and minimise the visual mass of the development. Each of the voids would accommodate a sky garden increasing the open space available to future residents and the area of visible greenery.

11.4.17   Access to the site is provided by the proposed Southern Development Access which utilises the alignment of an existing Fuk Shun Street passing through the villages of Tai Tseng Wai and Shing Uk Tsuen. Fuk Shun Street will be widened within the existing landtake to a standard 7.3m single 2-lane public road with 2m wide footpath on both sides of the carriageway. The Southern Development Access will also minimise the potential disturbance from a landscape and visual perspective preserving the tranquillity of the fishpond area to the north of the development site.

11.4.18   Option 1B

11.4.19   Option 1B shares many of the characteristics of Option 1A in terms of the design approach to the building disposition and architectural form. The proposed scheme consists of nine blocks of 15 storeys, 7 groups of low-rise buildings (4-10 storeys) including a residents’club house. This option shares the same landtake as Option 1A so as to reduce the disturbance to the preserved fish ponds.  Again the low-rise buildings are arranged in the space between the medium-rise buildings creating a more subtle transition between the development and the surrounding landscape particularly the existing fishponds to the north.  These low-rise buildings are arranged to have irregular frontages creating visual interest. The medium-rise blocks are arranged with four on an east-west axis and five on a north-south axis designed to maximise the visual permeability of the development when viewed from the main concentrations of VSRs from the west (Tin Shui Wai) and from the east (developments such as the Fairview Park).   With the low-rise buildings located between the medium-rise blocks and a clubhouse in the central portion of the site. With this arrangement eight view corridors are created between the medium-rise building blocks.  The proposed limitation of the building heights to 15 storeys serves to maximise the visual access to the landscape to the south of the development site including the wooded hillsides however the addition of an additional block compared to Option 1A serves to reduce the effective width of the view corridors and therefore slightly reduce the visual permeability of the development when viewed from the east and west. Option 1B would adopt the same proposals for the Southern Development Access as Option 1A.

 

11.5                Review of Planning and Development Control Framework

11.5.1      A review of the existing planning studies and documents has been undertaken to gain an insight into the planned role of the site, its context and to help determine the projects fit into the wider landscape context. The assessment does not consider all of the areas zoned on the OZP only those affected by the proposals, the location of these areas are shown on Figure 11-8. The predicted impacts arising from Options 1A and 1B are considered similar due to their similar architectural characteristics, shared footprint and location. This review for Options 1A and 1B considered the following aspects of the identified planning designations:

·        Zoning areas which would be physically affected by the proposals, that is where the implementation of the proposal works would lead to the actual loss of an area; 

·        The potential degradation of the landscape setting of an area which might effect the viability of it’s landscape planning designation but not result in a loss of zoning area;

·        The visual amenity enjoyed by future residents or users; and, 

·        The general fit of the proposals into this future landscape.

11.5.2      A review of the Final Report of Study on the Ecological Value of Fish Ponds in Deep Bay Area is contained in Section 11.6 formed part of the landscape planning control review to gain an insight into the guidelines for the formulation of master layout plan within the study area. The assessment covers areas shown on the following Outline Zoning Plans:

·        S/YL-LFS/7, Lau Fau Shan and Tsim Bei Tsui;

·        S/TSW/11 Tin Shui Wai; and

·        S/YL-PS/11 Ping Shan.

·        S/YL/17 Yuen Long.

11.5.3      This review has found that the following impacts on identified planning designations:

·        Areas that would be physically affected whereby the implementation of the development proposals would lead to the actual loss of area. These include approximately 4 hectares of the existing Comprehensive Development and Wetland Enhancement Area.  Although the proposals are in accordance with the planned use for this area there would be some loss of visual amenity and a slight degradation of landscape character as a result of the proposals. However the development proposals have sought to minimise the potential landscape and visual impact by locating the development on the southern periphery of the site. In addition some 76.1 hectares of fishponds would be transformed into a Wetland Nature Reserve thus ensuring that the area is both visually enhanced and safeguarded as a landscape resource.

·        The assessment found no areas where the proposed development would lead indirectly to a degradation of the landscape setting of an area thus affecting its viability in terms of being a landscape planning designation. 

·        There are two main areas where the proposed development would affect the visual amenity enjoyed by future residents or users. These are shown on Tin Shui Wai OZP, S/TSW/11, and include the proposed residential development for the north eastern side of Tin Shui Wai including the Area 104 designated as R(B)1 Zone. The residents of developments on the eastern periphery of these areas would be the only ones affected by the development proposals although low-level views would be largely screened by the existing vegetation on the existing fishpond bunds and the proposed Open Space located at Area 117 and 120. In addition more elevated views would be affected for the future residents at Area 103 which is designated as R(A) Zone intended to allow high density residential development, for residents on the eastern side of this development would overlook the proposed development site although at a viewing distance of some 1500m.  

·        The proposals will not have a direct impact on the existing Hong Kong Wetland Park (HKWP) where zoned “Other Specific Uses” in the OZP as presented in Table 11-4. The implementation of the proposed Wetland Nature Reserve (WNR) including the proposed marsh habitat will provide an extension of the HKWP.

·        The proposal will not have impact on the existing Yuen Long Industrial Estate where zoned as “Other Specific Uses” and other zoning area within Yuen Long OZP, S/YL/17, regarding to the locations of these zoning areas are separated by “Village Type Development” and “Green Belt” zones contained within Ping Shan OZP, S/YL-PS/11 from the proposed development.

11.5.4      Given the above summary of impact on planning control framework on and adjacent to the development site and detailed review in Table 11-4 below, the proposed development sited within the area zoned “Other Specific Uses (Comprehensive Development and Wetland Enhancement Area)”, “OU(CDWEA)”, contained within Lau Fau Shan and Tsim Bei Tsui OZP, S/YL-LFS/7, comply with the planning intention for this zoning through redevelopment of the site with conservation objectives and positive measures to enhance the ecological value and functions of the existing fish ponds and wetland and will generally fit within the future landscape planning framework as represented by the OZPs, hence no amendment to the published land use plans is required. Although the proposals would therefore not have an adverse impact being largely compatible with the planning intention for the area and the planned landuses in the adjourning areas and would fit into the outlook of the remaining rural landscape context in Deep Bay Area surrounding by Tin Siu Wai high-rise developments to the west, village and Yuen Long industrial developments to the south, Section 16 planning application is still required to permit the proposed development in accordance with the requirement under OZP at later stage.


Table 114       Review of Existing Planning and Development Control Framework

Land Use Zonings

Landscape Planning, Design and Conservation Intention of Zoning 

Approx. Area Affected by the Proposals

Potential Impact on Zoning Areas

 

Mitigation Measures and Future Outlook of the Area with the Development Proposal

Outline Zoning Plan number S/YL-LFS/7  Lau Fau Shan and Tsim Bei Tsui

 

1. Comprehensive Development and Wetland Enhancement Area (OU)

Land zoned for this purpose is to have no new development except development and/or redevelopment with conservation objectives and positive measures to enhance the ecological value and functions of the existing fish ponds and wetland. Development should be in the form of a comprehensive development scheme with minimum pond filling.

 

The whole designated site.

 

 

The proposed development will be in accordance with the planning intention of this zone with the potential impacts being minimised as far as possible through the siting and design of the development proposals required only 4 Ha. of the whole zoning area. The proposed WNR on the rest of the zoning area will also enhance the existing landscape to the north of the development area. 

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures the development proposals contained within this zone are compatible to the planning intention in principle and fairly integrated with the wetland and village landscape context.

 

 

2. Conservation Areas (CA)

The planning intention of this zone is to conserve the ecological value of the fishponds which form an integral part of the wetland ecosystem in the Deep Bay area.

No actual loss but indirect impacts.

The main areas indirectly affected by the proposed development are located to the south west, along the southern periphery of the OU (CDWEA) described above and to the east of the development site. However the design and siting of the proposed development including the access road has sought to avoid these areas and so any impacts will be indirect and based on impacts to their landscape context.

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given no direct impact on this zoning area, the full establishment of the above mitigation measures and providing a better integration between the development site and the conservation area, the development proposals are compatible to the planning intention of this zoning and fairly integrated with the wetland landscape context.

 

Outline Zoning Plan number S/YL-PS/11  Ping Shan

 

3. Village Type Development (V)

This area encompasses the villages of Ng Uk, Tai Tseng Wai and Shing Uk Tsuen and is located on the saddle between two summits of the Kai Shan range immediately to the south of the proposed development site. The planning intention of this zone is to designate both existing and recognised villages and areas of land considered suitable for village expansion.

 

No actual loss but indirect impacts.

The proposed development would not infringe upon this area and despite its proximity would not have a significant effect on the landscape setting of these settlements.

The Southern Development Access would utilise the existing footprint of Fok Shun Road and so would not cause any additional impacts on the village.

     

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures the development proposals are compatible to the planning intention of its adjacent village and fairly integrated with the village landscape context.

-

 

4. Green Belt (GB)

The planning intention of this zone is to define the limits of urban and suburban development areas by natural features, to contain urban sprawl as well as to provide passive recreational outlets. The two main area of Green Belt adjacent to the proposed development site are located to the north and northeast of Kai Shan.

No actual loss but indirect impacts.

The areas will not be physically affected by the proposals although there may be some indirect impacts on their landscape setting due to the proximity of the proposed development.   

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures the development proposals are compatible to the planning intention of its adjacent green belt and integrated with the adjacent woodland landscape context.

 

 

Outline Zoning Plan number S/TSW/10  Tin Shui Wai

 

5. Other Specified Uses (Hong Kong Wetland Park) (OU)

 

The Hong Kong Wetland Park (HKWP) is proposed as replacement habitat for the wetland lost from the engineering works for the residential zone and to act as a buffer to minimise human disturbance to the adjacent ecologically sensitive areas.

No actual loss but indirect impacts.

The development proposals will not have a direct impact upon this area. The implementation of the proposed WNR including the proposed marsh habitat will provide an extension of the Hong Kong Wetland Park particularly in views from the upper floors of the proposed high-rise residential development on the western periphery of Tin Shui Wai.

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures providing better integration with its adjacent zoning area reserved for park and wetland reserve, the development proposals are compatible to the planning intention of its adjacent zoning area and integrated with the adjacent wetland conservation landscape context.

 

 

6. Comprehensive Development Area (CDA)

Site 115 to the northwest of the proposed development area is intended for lower density development taking into account their proximity to the Hong Kong Wetland Park and the conservation areas to the northeast.

No actual loss but indirect impacts.

The development proposals would have no direct impact on this area the proposals would have an indirect impact on the visual amenity for residents on the eastern periphery of the area. 

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures the development proposals are compatible to the planning intention for lower density development within this zone, the provision of WNR enhance the visual amenity extending from HK wetland Park in the foreground of the local visual context, and hence making the proposal development integrated with the future low-rise residential landscape context.

 

 

7. Residential (B) 1 (R(B))

These areas (104) are zoned for medium-density private development

No actual loss but indirect impacts.

The development proposals would have no direct impact on this area the proposals would have an indirect impact on the visual amenity for residents on the eastern periphery of the area.  Visual amenity from future residents of the eastern periphery in this area towards the HK Wetland Park and fishpond area would be affected by the development proposals although low-level views would be largely screened by the existing vegetation on the existing fishpond bunds and that proposed Open Space for area 120.  

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures providing a better integration between the development and adjacent wetland areas, the development proposals are compatible to the planning intention for adjacent medium density residential development within this zoning area and integrated with the future residential landscape context.

 

 

8. Residential (A) (R(A))

This area on the north eastern side of the Tin Shui Wai New Town (Area 103) is intended as a high density development.

No actual loss but indirect impacts.

The development proposals would have no direct impact on this area the proposals would have an indirect impact on the visual amenity for residents of the area. Future residents are likely to have elevated views of the development proposals although it would form a relatively small component of the overall view available and at a viewing distance of some 1200m both factors which will minimise potential impacts.

Primary mitigation includes the responsive siting and extent of footprint for the proposed development. Secondary mitigation includes design of residential building, the provision of WNR, landscape buffer planting, compensatory and new amenity planting and restoration of access road landscape. Given the full establishment of the above mitigation measures providing a better integration between the development and adjacent wetland areas, the development proposals are compatible to the planning intention for adjacent high density residential development within this zoning area and integrated with the future residential landscape context.

 

 

Key:                                       

Sensitivity of Resource (Sens):               Low, Medium or High

Magnitude of Change (Mag): Negligible, Small, Intermediate or Large

Impact Significance Threshold:               Potential impacts on the existing and planned landscape planning and development control framework arising from the proposals

Significance Threshold:                           Negligible, Slight, Moderate and Significant (Adverse or Beneficial)

Con:                                                       Construction phase impacts                  

Oper:                                                      Operational phase impact

 


11.6                Review of Study on the Ecological Value of Fish Ponds in Deep Bay Area

11.6.1      A review of the Final Report of Study on the Ecological Value of Fish Ponds in Deep Bay Area has been undertaken to gain an insight into the guidelines for the formulation of master layout plan within the study area. Although these guidelines are indicative only and should not be taken as rigid requirement, they address specifically the interface treatment between the new wetland areas to be restored or created and the development area within the overall development site. Guidelines suggested in the study include the following:

·        Definition of the development site, the development area, and the wetland restoration /creation area;

·        Building Massing and Height

o        The overall site planning should reflect an increase in general height of buildings and structures away from the wetland restoration/creation area;

o        The maximum height of any building should be compatible with the character of the immediate surrounding area;

o        A cluster concept should be adopted as the overall site planning approach;

·        Vehicular circulation

o        If possible, all vehicular circulation and space should be located away from the wetland restoration /creation area;

·        Landscape Design

o        The landscape material to be used within the wetland restoration /creation area should follow the wetland restoration/creation proposals to be approved by the Town Planning Board with input from the Agriculture, Fisheries and Conservation Department;

o        Natives species should be widely used inside the wetland restoration/creation area, particularly along the interface with the adjourning wetland;

o        Landscape buffers should be considered to be established along the edge of the wetland to be restored or created;

·        Glare and Noise

o        The overall site planning should prevent unnecessary noise and glare impacting on the wetland. This could be achieved by building orientation, siting as well as the planning and design of exterior lighting; and

·        Drainage

o        Treatment of the drainage proposal will have significant impact on the wetland to be created. The planning and design concept for the new wetland, especially the hydrological regime should be incorporated in to the drainage proposal.

11.6.2      The preferred development schemes for Options 1A and 1B have taken into account of the above planning guidelines through the application of following measures:

 

l            A responsive site planning including the siting of the buildings at the southern edge of the boundary adjacent to the existing villages;

l            Maximising the visual permeability through the creation of view corridors allowing visual access to the hillsides beyond and the location of the low-rise buildings between the proposed medium-rise blocks;

l            Use of a stepped edge profile for the blocks in Option 1A designed to soften the transition between the flat coastal plain and the proposed scheme;

l            Minimising the proposed visual prominence of the proposed development through the minimisation of the proposed building height for both options (Option 1A maximum 18 storeys and Option 1B maximum 15 storeys); and

l            Creation of a new marsh habitat immediately adjacent to the proposed tree and shrub planting at northern edge of the development which together serve as a landscape buffer to the wetland enhancement area.

11.6.3      The preferred schemes (Options 1A and 1B) and their landscape proposals therefore fit into the wider landscape context and the landscape of the wetland enhancement scheme. The landscape design proposals for both options are further discussed in Section 11.10.

 

11.7                Existing Landscape Context

Baseline Conditions

11.7.1      The baseline review of the existing landscape establishes broad characteristics, identifies landscape resources, and then provides a characterisation and evaluation of the identified Landscape Character Areas (LCAs).

11.7.2      Figure 112 shows the existing LRs found within the Study Area and Figure 11-4 shows the extent of identified LCAs.  Figure 11-5A and B illustrate the LCAs with site photographs.

Topography

11.7.3      The topography of the Study Area is characterised by a series of interconnected river valleys leading to the flat coastal landscape of Deep Bay and the estuarine landscape of the Shan Pui and Shan Chun Rivers. This landscape is punctuated by the uplands associated with the Lau Fau Shan peninsular and the Kai Shan range. The valleys are contained by the steep sided uplands of the Lam Tsuen and Tai Lam Country Parks. To the north of the development site the landscape extends over traditional fishponds to the tidal mudflats of the mouth of the Shan Pui River and Deep Bay. To the east the traditional fishponds of the Lut Chau and Nam Sang Wai areas are bounded by a flat agricultural plain east of Castle Peak Road and the uplands of the Lam Tsuen Country Park rising to the summit of Kai Kung Leng at 585mPD. To the south of the development area the landscape is punctuated by the twin summits of the Kai Shan range on a north-south axis rising to a summit of approximately 121mPD backed by the uplands of the Tai Lam Country Park rising ultimately to approximately 507mPD. To the west of development site is situated the large reclaimed development platform for the Tin Shui Wai development leading to the agricultural area of Ha Tsuen and the summit of Yuen Tau Shan at approximately 375mPD.

Vegetation

11.7.4      The vegetation of the Study Area has for the large part been considerably modified by human activity and so the existing pattern of vegetation represents a variation from the natural regime or climax vegetation, which would naturally occur in this area. This reflects the historical development of the area particularly in agricultural practices including the extensive fish pond areas, village development and more recently the development of new urban areas such as Tin Shui Wai.  The main vegetation pattern is characterised by three main vegetation types associated with the traditional fishpond areas, agricultural fields and wooded hill slopes which punctuate the coastal plain. However the landscape of the tidal mudflats and its associated mangrove forests represents one of the few natural landscapes in Hong Kong. The main vegetation types are described in greater detail as part of the landscape resources section below.

11.7.5      Figure 112 gives a broad indication of the existing vegetative cover within the Study Area.  

Land Use

11.7.6      The Study Area is characterised by a combination of the following land uses:

·        Natural and undeveloped areas, particularly the upland areas including the Lam Tsuen Country Park although these areas are crossed in a number of places by walking trails;

·        High-rise residential development concentrated to the south (Yuen Long) and west (Tin Shui Wai) of the development site on the valley floor;

·        Extensive areas of low-rise development such as that of the Fairview Park development located to the east of the site;

·        Agricultural landscapes, both active and abandoned located, largely at the base of the surrounding uplands punctuated by low-rise traditional village settlements in areas such as Ng Uk Tsuen, Sha Kong Wai and Mong Tsuen Wai;

·        Large scale commercial and industrial development such as the Yuen Long Industrial Estate and the Yuen Long Sewage Treatment Works;

·        Recreational areas including sporting facilities and recreational facilities situated in the main urban areas of Yuen Long and Tin Shui Wai; and 

·        Hong Kong Wetland Park.

 

11.8          Landscape Impact Assessment

11.8.1      The following sections provide a landscape impact assessment for development Options 1A and 1B. The predicted impacts on the existing landscape resources arising from the implementation of both Options 1A and 1B are described together as they share the same footprint and so the direct impacts for each will be the same. Whereas the predicted impacts on the prevailing landscape character includes some indirect impacts which might arise from the slight variations in the two schemes and so are assessed separately.

11.8.2      Option 1A – buildings with a maximum height of 18 storeys (8 blocks of 14-18 storeys, 7 groups of 4-8 storey low-rise buildings including a 2 storey resident’s club house erected on 40,000m² residential site area i.e. 32.8% Site Coverage).

11.8.3      Option 1B – buildings with a maximum height of 15 storeys (9 blocks of 15 storeys, 7 groups of 4-10 storey low-rise buildings including a 2 storey resident’s club house erected on 40,000m² residential site area i.e. 34.4% Site Coverage).

Landscape Resources – Options 1A and 1B

11.8.4      An important determinant of the landscape character within a Study Area, which is a combination of traditional fishponds and village settlements bounded by small agricultural fields; major urban development and remnants of natural upland landscapes, is the type and extent of its landscape resources both natural and cultivated. These landscape resources are shown on Figure 11.2 and the LCAs, Figure 114, Figure 115A and Figure 115B. The following LRs have been identified within the Study Area:

·        LR1 Existing Land Form

·        LR2 Woodland

·        LR3 Plantation Woodland

·        LR4 Orchard

·        LR5 Shrub and Mosaic

·        LR6 Grassland

·        LR7 Agricultural Land

·        LR8 Fishponds

·        LR9 Watercourses – River and Streams

·        LR10 Watercourses – Ditches and Drainage Channels

·        LR11 Mangroves Forest/Mudflats

·        LR12 Wetlands

·        LR13 Existing Trees

11.8.5      For the purposes of this assessment the landscape resources are represented by the existing land cover. The condition of these landscape resources is also important in determining the landscape quality of the Study Area and its sensitivity to change. Therefore the preservation and enhancement of the existing landscape resources is important to the successful integration of the proposals into the landscape context of the Study Area. Table 115 below describes the impact on the prevailing landscape character of the Study Area due to the loss of landscape resources due to the development proposals.

Existing Trees – Options 1A and 1B

11.8.6      As part of the assessment of the impact on the existing landscape resources a broad brush tree survey was undertaken. These trees are located throughout the Study Area although are largely concentrated in the existing fishponds. They are formed by a combination of trees planted as part of the settlement of this area and tree species which have naturally colonised it. The approximate locations of the trees are presented as Figure 113 Preliminary Tree Survey Plan whilst the schedule contained in Appendix 11-1 provides details of the trees including the range of species, size and an assessment of their condition. The survey identified approximately 665 trees with 178 within the main development area and 487 within the area identified for the WNR including 28 within the Alternative Egretry. For the main part the tree species are non-native originating in Australia, India, Indonesia and Malaysia, and are fruit bearing being planted as part of the agricultural development of the area.  The main species within the Study Area include Annona squamosa, Artocarpus heterophyllus, Clausena lansium, Dimocarpus longan, Musa paradisiaca, Carica papaya, Litchi chinensis, Melia azedarach, Psidium guajava, Macaranga tanarius and Mangifera indica. The survey found no Old and Valuable Trees (ETWB TCW No, 29/2004 Registration of Old and Valuable Trees, and Guidelines for their Preservation), rare or protected tree species (based on Forests and Countryside Ordinance , Cap. 96) or Champion Trees (identified in the book ‘ Champion Trees in Urban Hong Kong’).

Tree Retention

11.8.7      Generally wherever possible existing trees will be retained in-situ, and where this is not possible the trees will be considered for transplantation and as a last resort considered for felling. Based on the findings of the preliminary tree survey it is estimated that approximately 15 trees can be retained on the fringes of the main development area and approximately 223 within the area forming the proposed WNR. Wherever possible the proposals for the WNR including the removal of pond bunds have been modified to preserve existing trees in-situ.

11.8.8      Therefore approximately 238 (36%) of the trees surveyed would be retained under the current proposals (Figure 113 Preliminary Tree Survey Plan refers).

Tree Transplantation Proposals

11.8.9      In terms of assessing the feasibility of transplanting the existing trees a number of factors were considered including their form, health and amenity value. Also considered was the existence of rare and native species, the accessibility for machinery required for transplantation; age; and the availability and technical feasibility of providing recipient sites for the transplanted trees.

11.8.10   Based on the preliminary tree survey and with consideration for the factors described above it is recommended that 28 (4%) of the existing trees are suitable for transplantation. This transplantation will be required due to the proposed removal of pond bunds as part of the site formation for the proposed development and the creation of the WNR. The trees identified for transplantation include those of good form and health which are accessible to machinery, and where possible native species such as Celtis sinensis which have ecological value.

11.8.11   These trees will be transplanted to the proposed landscape buffer to the north of the development as shown on Figure 11-11A and 11-12A.

Tree Felling Proposals

11.8.12   The Tree Survey Report concludes that it would not be feasible to retain or transplant approximately 399 (60%) (Figure 113 Preliminary Tree Survey Plan refers) of the existing trees for the following reasons:

·        The removal of some of the pond bunds, where this is unavoidable, as part of the creation of the proposed WNR and the requirement for the no net loss in fishpond area will require have an impact on the existing trees. Wherever possible these trees, particularly the larger groups, have been preserved through the creation of islands from the former pond bunds.

·        In some locations the scope of the proposed works and site formation precludes any opportunities to retain existing trees particularly in the main development area due to the construction of the development platform. However for a large part these trees are fruit trees many of which are non-native (including approximately 176 Musa paradisiaca (Banana), equating to 26% of the total number of trees).

·        Where the retention of the existing trees in-situ is not possible the trees have been considered for transplantation however in many locations the pond bunds are too narrow and steep sided to enable machinery access to facilitate the transplantation operations.

·        The necessary excavation required in order to construct the proposed basement car parking means it is technically unfeasible to retain the trees within the development area.

·        The trees are of poor health, condition and form. 

Tree Survey Report

11.8.13   The findings and recommendations of the preliminary tree impact assessment are subject to the completion of a detailed tree survey and felling application in accordance with ETWB TCW No. 03/2006, Tree Preservation. This will be conducted during the detailed design stage of the project.  The methodology and scope including the programme for the tree survey and felling application would be subject to the approval of the relevant authorities.

Impact on Existing Landscape Resources – Options 1A and 1B

11.8.14   The main impacts on the landscape resources of the Study Area for both options will result from the loss of the existing fishponds (LR 8) (approximately 4 ha) and pond bunds resulting from the modification of existing landform (LR 1 Existing Landform – approximately 4.6 ha) for the development, and the loss of existing ditches and drainage channels (LR 10 Watercourses - approximately 800m2) due to the proposed construction of the residential development platform and the creation of the WNR. Despite the loss of fishpond being a small part of the overall resource within the Study Area (approximately 2.5%) it is an important landscape resource and so this has shaped the locatin and extent of the building platform which has sought to minmise the impact on the integrity of the fish pond area as far as possible. Also the location of the residential development on the periphery of the fishpond area with its minimised landtake will reduce potential impacts on the existing landform (LR 1) by maintaining the physical integrity of the main area.

11.8.15   The impacts on LR 8 fish ponds will be further mitigated through the improvement of the fish pond area leading to a net gain of 0.1ha in the area of the water body. In addition it is considered that the proposed created marshland habitat which forms part of landscape buffer between the development area and the WNR will lead to a qualitative enhancement of the remaining area of this LR. Given this the residual impacts on the fishpond area are likely to be mitigated from moderate adverse to slight adverse when the mitigation measures are fully implemented. Whilst the predicted impact on the landform (LR1) due to the loss of pond bunds is likely to be slight adverse during construction phase as the loss represents a small part of the overall resource. 

11.8.16   There would be a predicted loss of 0.08 ha of existing ditches (LR 10) on the southern side of the residential development site due to the wetland enhancement works. These watercourses are manmade structures and make a relatively small contribution to the existing landscape character. The proposed enhancement works will improve the appearance of these structures and increase their contribution to the future landscape character.

11.8.17   Impacts on the remaining landscape resources in the Study Area will largely be negligible as the development will not cause a physical impact. This includes the proposed creation of the woodland landscape buffer along the periphery of the development site which will be contiguous with the existing landscape resource (LR 3 Plantation Woodland). However with the growth to maturity of the trees there would be a moderate beneficial residual impact on the overall landscape resource. In addition the planting of new trees will have a moderate beneficial residual impact on LR 13 Existing Trees due to the number of trees to be planted and the replacement of common fruit tree species with native species.

11.8.18   Table 115 Existing Landscape Resources and Predicted Impacts presents the predicted unmitigated and mitigated (residual) impacts resulting from the proposed works during the construction and operational phases of the project. These impacts also mapped on Figure 119. The mitigated (residual) impacts are assessed during the design year which for the purposes of this study is taken as being between 10 and 15 years after the schemes opening when the proposed mitigation planting is deemed to have reached a level of maturity, which is sufficient for it to perform the design objectives.

11.8.19   The assessment contained in Table 115 and mapped on Figure 119 concluded that despite the small to negligible impact on the existing LRs (with the exception of the loss of fish ponds which would have a moderate adverse impact), the establishment of the WNR together with landscape buffer provided at the boundary of the development will mitigate the loss in addition to providing an overall enhancement of the existing fishponds, watercourses and plantation woodland from an ecological perspective. The predicted residual impact on these LRs is further discussed in Section 11.14.


 

Table 115       Existing Landscape Resources and Predicted Impacts – Options 1A and 1B

Landscape Resource

Total Area of Resource (Ha) / Loss  (Ha) / % Loss

Sens

Mag of Change (Con / Oper Phase)

Impact on Landscape Character resulting from the loss of the Existing Landscape Resources.

Significance Threshold

(Unmitigated)

 

Mitigation Measures

Significance Threshold

(Mitigated)

 

Con

Oper

Con

Oper

LR 1

Existing Landform

350 (study area) / 4 (Loss resulting from Development site including fishponds)

1%

 

350 (study area) / 4.6 (bunds will be modified resulting from Wetland Nature Reserve enhancement)

1%

 

 

Medium

Condition, quality and maturity: High

Importance and rarity of special landscape elements: Regionally important

Ability of the LR to accommodate change: Medium

Statutory or regulatory requirements: Complies with requirements under OZP S/YL-LFS/7

Small / Small

Scale of the development and extent of impact compared to the total area of LR: Small

Duration of impacts: Construction stage – Temporary

Operation Stage – Permanent 

Reversibility of change: Medium within  future WNR

The proposals would not have a significant effect on the landform of the Study Area despite the reclamation of existing ponds to create the development platform. The location of the development platform along the northern base of the Kai Shan range would form an extension to the existing dry agricultural land which is characteristic of the landscape in the Study Area. There would also be some loss of existing fishpond bunds (approximately 4.47ha) however this loss would not have a significant impact on the landscape character of the area. 

Moderate Adverse

Moderate Adverse

OP1,OP2 and OP5

 

Slight Adverse

Slight Adverse

LR 2

Woodland

19.61 / 0.0 

0%

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements : Locally important

Ability of the LR to accommodate change: Low

Statutory or regulatory requirements: Complies with requirement under OZP S/YL-LFS/7

Nil/ Nil

Scale of the development and extent of impact compared to the total area of LR: Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: Medium

These resource including areas of Fung Shui woodlands are largely located on the lower hill slopes of the Kai Shan range forming a green back drop to views of the development site from the north. However the proposals being situated on the valley floor would not impact upon the existing woodland resource.

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area. This includes OP1, OP2 and OP3 which will contribute to the woodland resource within the study area.

Negligible

Negligible

LR 3

Plantation Woodland

3.03 / 0.0

<1%

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements : Locally important

 

Ability of the LR to accommodate change: Low

Statutory or regulatory requirements: Compiled with requirement under OZP S/YL-LFS/7

Small

Scale of the development and extent of impact compared to the total area of LR: Small

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Medium

This resource is largely situated in the centre of Hong Kong Wetland Park to the north west of the Study Area and would be untouched by the development proposals. New buffer planting proposed at the southern edge of the development in conjunction with the plantation woodland located at northern edge of Ng Uk Tsuen will enhance the local landscape context and benefit to this landscape resource.

Negligible

Moderate Beneficial

(due to provision of landscape buffer planting at the boundary of the development providing a net gain of this LR as discussed in Table 12 of this report)

CP1, CP3, OP2 and OP3 

Negligible

Moderate Beneficial

(due to fully establishment of the  planting proposal for the development provide a net gain of this LR as discussed in Table 12 of this report)

(Net gain of    3,750m2 woodland buffer within the development site.)

 

 

 

LR 4

Orchard

1.44 / 0.0

0%

Medium

Condition, quality and maturity: Medium

Importance and rarity of special landscape elements: Locally important

Ability of the LR to accommodate change: Medium

Statutory or regulatory requirements: Nil

Nil/ Nil

Scale of the development and extent of impact compared to the total area of LR: Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: Medium

There are three main areas of orchard located to the south of the Study Area adjacent to the existing village developments north of Ng Uk Tsuen. The orchards are also planted contiguous to woodland areas. There would be no impact on this resource.

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area. This includes OP1, OP2 and OP3 which will contribute to the woodland resource within the study area.

Negligible

Negligible

LR 5

Shrub Mosaic

20.46 / 0.0

 0%

Medium

Condition, quality and maturity: Low

Importance and rarity of special landscape elements : Low 

Ability of the LR to accommodate change: Medium

Statutory or regulatory requirements: Nil

Nil/ Nil

Scale of the development and extent of impact compared to the total area of LR: Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: Medium

 

 

The main areas of this resource are situated on the upper hill slopes and summits of the peaks forming the Kai Shan range and would not be affected by the development proposals.

 

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area.

Negligible

Negligible

LR 6

Grassland

4.19 / 0.0

0%

Low

Condition, quality and maturity: Low

Importance and rarity of special landscape elements : Low importance 

Ability of the LR to accommodate change: High

Statutory or regulatory requirements: Nil

Nil / Nil

Scale of the development and extent of impact compared to the total area of LR: Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: High

 

Small pockets of grassland are located throughout the Study Area although primarily located adjacent to the Closed Area Boundary road to the north of the existing fishpond areas. The existing grassland will not be affected by the development proposals.

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area.

Negligible

Negligible

LR 7

Agricultural Land

7.04 / 0.0

0%

Medium

Condition, quality and maturity: Low

Importance and rarity of special landscape elements : Low importance 

Ability of the LR to accommodate change: High

Statutory or regulatory requirements: Nil

Nil / Nil

Scale of the development and extent of impact compared to the total area of LR:  Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: High

 

 

The main areas of agricultural land are located to the south of the Study Area at the base of the Kai Shan hill range. This transition from fishpond to dry agricultural land to the wooded hillsides of the uplands is characteristic of the Study Area and the north west New Territories in general. The resource includes both active and inactive (5.17ha) agricultural land. The development proposals would not affect the extent of this resource within the Study Area.

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area.

Negligible

Negligible

LR 8

Fishponds

Loss resulting  from the residential development

170.29 / 4.07 / 2.4%

 

Area enhanced by the Wetland Nature Reserve

170.29 / 75.95 / 45%

 

No net loss of water body

 

 

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements: Regionally important 

Ability of the LR to accommodate change: Low

Statutory or regulatory requirements: Compiled with requirement under OZP S/YL-LFS/7

Small / Small

Scale of the development and extent of impact compared to the total area of LR: Small to Intermediate

Duration of impacts: Construction stage – Temporary

Operation Stage – Permanent

Reversibility of change: Low for area affected by the building footprint

 

The loss of approximately 2.4% out of a total area of approximately 170ha of fishponds is not considered significant in terms of the percentage of loss however in terms of the physical size of the area (4ha) this is an extensive area. This is an important regional landscape resource and so any loss is important. For this reason the location of the area affected by the proposals has been restricted to an area contiguous with existing hillsides and so would not affect the physical integrity of the remnant portion thus minimising the impact of this loss of LR on the landscape character of the area. The enhancement works proposed for the WNR will benefit the landscape context in long term following the completion of the works.

 

Moderate Adverse

(due to modification of existing fish pond bunds)

Moderate Adverse

(due to modification of existing fish pond bunds)

Primary mitigation through the location of the residential development on the southern periphery of the fishpond area minimising the disturbance to the remaining fishponds. Enhancement of the marshland (OP2). 

Moderate Adverse

 

Moderate Adverse

(due to proposed fish pond enhancement and introduction of active amendment ) (slight net gain in the area of the water body within proposed WNR)

 

LR 9

Watercourses - Rivers and  Streams

25.24 / 0.0

0%

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements : Locally important

Ability of the LR to accommodate change: Low

Statutory or regulatory requirements: Nil

Nil/ Nil

Scale of the development and extent of impact compared to the total area of LR: negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: High

 

 

Many of the larger existing watercourses within the Study Area which influence its perceived landscape character have been modified these include the retrained river channels to the west of Tin Shui Wai, and the Shan Pui and Shan Chun Rivers. Therefore these features have a low sensitivity to further change however there would be direct or indirect impacts on these resources.  

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area.

Negligible

Negligible

LR 10

Watercourses -  Ditches and Drainage Channels

0.47 / 0.08 /

17%

 

Low

Condition, quality and maturity: Low

Importance and rarity of special landscape elements : Low importance

Ability of the LR to accommodate change: High

Statutory or regulatory requirements: Nil

 

Small / Small

Scale of the development and extent of impact compared to the total area of LR: Small

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Low for area affected by the building footprint and high for other areas

 

 

Four drainage ditches were identified within the Study Area used for moving water between the fishponds. These have a low value in terms of their contribution to the existing landscape character.  Only 4% of this resource will be affected by the residential development, the other 13% affected area will be enhanced through the Wetland Nature Reserve proposals.    

Slight Adverse

Slight Adverse

OP2, OP4

 

Slight Adverse

 

Slight Adverse

 

LR11

Mangrove Forest / Mudflats

48.44 / 0.0

 0%

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements : Regionally important

Ability of the LR to accommodate change: Low

Statutory or regulatory requirements: Complies with requirement under OZP S/YL-LFS/7

 

Nil / Nil

Scale of the development and extent of impact compared to the total area of LR:  Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: High as LR not physically affected

Located in the northern part of the Study Area this resource includes naturally regenerating mangrove forest interspersed by mudflats forming the estuarine landscape of the Shan Pui, Sham Chun and Tai Rivers.   There would be no direct or indirect impacts to this landscape resource.

 

 

 

Negligible

Negligible

As there are no direct impacts to the LR no mitigation is required although it is considered that the overall landscape and visual mitigation approach will enhance the overall landscape character and quality of the local area.

Negligible

Negligible

LR 12

Wetlands including reed beds and permanent freshwater marsh and pools

3.14 / 0.0

<1%

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements: Regionally important

Ability of the LR to accommodate change: Low

Statutory or regulatory requirements: Complies with requirement under OZP S/YL-LFS/7

 

 

Nil / Small

Scale of the development and extent of impact compared to the total area of LR:  Small to Negligible

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: High

 

The wetlands including reed beds are restricted to a small area, probably an abandoned fishpond in the southern part of the Study Area characterised by Phragmites. Whilst areas of marsh occur in the southern part of the Study Area closely associated with various agricultural land-uses. It is likely that these areas of marsh have formed on land previously used for aquaculture or wet agriculture. The wetlands found within the Study Area do not represent a significant landscape resource in terms of its shaping landscape character.

 

Negligible

Negligible

OP2, OP4

Negligible

Negligible

LR 13

Existing Trees

665 trees in total with 178 trees within the main development area and 487  trees within the area identified for the WNR / 301 trees / 45%

High to medium

Condition, quality and maturity: Generally medium to low (although some good specimen trees)

Importance and rarity of special landscape elements: Locally  important

Ability of the LR to accommodate change: Medium

Statutory or regulatory requirements: Requiores formal felling application in accordance with WBTC No. 03/2006

 

Intermediate / Small

Scale of the development and extent of impact compared to the total area of LR:  Intermediate

Duration of impacts: Construction stage – Termporary

Operation Stage – Nil

Reversibility of change: High

 

The existing trees are largely located within LR8 Fishponds and are formed by a combination of trees planted as part of the settlement of this area and tree species which have naturally colonised it. The approximate locations of the trees are presented as Figure 11-3 Preliminary Tree Survey Plan whilst the schedule contained in Appendix 11-1 provides details of the trees including the range of species, size and an assessment of their condition. For the main part the tree species are non-native originating in Australia, India, Indonesia and Malaysia, and are fruit bearing being planted as part of the agricultural development of the area. This includes a large proportion of fruit trees including approximately 176 Musa paradisiaca (Banana), equating to 27% of the total number of trees). No rare or protected species were identified as part of the preliminary tree survey.

 

 

Moderate

Moderate beneficial

OP2, OP3 and OP4

Moderate

Moderate beneficial

Key

 

Landscape Sensitivity (Sens):  Low, Medium or High

Condition, quality and maturity; importance and rarity of special landscape elements; and ability of the LR to accommodate change: Nil, Low, Medium or High

 

Magnitude of Change (Mag):   Negligible, Small, Intermediate and Large

Scale of the development and extent of impact compared to the total area of LR; duration of impacts; and reversibility of change: Nil, Low, Medium or High

 

Significance Threshold:                                                            Negligible, Slight, Moderate and Significant (adverse or beneficial)

Residual Impacts:                                                                     Refer to matrix and table in methodology section

Con:                                                                                         Construction phase impacts

Oper:                                                                                       Operational phase impacts

 


Landscape Character

11.8.20   The landscape character of the Study Area, located adjacent to Deep Bay in the northwest New Territories, is strongly influenced by the traditional fishponds which characterise the low lying coastal plain. The area is bisected by the Tin Shui Wai Drainage Channel and Shan Pui River. The landscape character of this area is formed by a largely undeveloped flat expanse of the fishponds bounded by the upright form of the surrounding hill sides. The relationship between the fishponds, the mud flats and the wooded hills sides is important to the landscape character of the area. Figure 114 shows the location of the LCAs which form the Study Area, and Figure 115A and B demonstrate how these various characters fit together.  

11.8.21   Table 116 presents a description of the following LCAs which make up the Study Area, the predicted impacts and recommended mitigation measures.

·        NUA 1                                         Natural Upland Landscape Character Area - Kai Shan Range

·        V1   Village Landscape Character Area - Ng Uk Tsuen Village Cluster

·        AGR1     Agriculture Landscape Character Area – Fung Kai Wai – Ng Tung Uk Agricultural Fields

·        AGR2                                           Agriculture Landscape Character Area – Fishponds

·        ICA1                                            Industrial/Commercial Landscape Character Area – Yuen Long Industrial Estate

·        OS1 Open Space and Parks Landscape Character Area – Hong Kong Wetland Park

·        EL1  Estuarine Landscape Character Area – Kam Tin and Shan Pui River Estuaries,     and the Tin Shui Wai Drainage Channel 

Impacts on Landscape Character - Options 1A and 1B

11.8.22   The potential impacts arising from options 1A and 1B on the existing landscape charcter would be largely similar due to their shared development footprint and hence the same direct impact on the landscape character of the area. This is mirrored in the potential indirect impacts as the differences in the design of the two schemes would not result in an appreciable difference in the potential impacts.

11.8.23   The Kai Shan Range (NUA 1) and the settlements of the Ng Uk Tsuen Village Cluster (V1) situated in the saddle between the primary and secondary peaks would not experience any direct impacts as a result of the development proposals. However there will be some indirect moderate adverse impacts during the construction phase due to the proximity of the proposed development and the alignment of the proposed development access. These impacts would be alleviated to an extent through the proposed mitigation with a slight adverse impact during the operational phase.

11.8.24   The landscape character of the Fishponds (AGR 2) would be subject to direct impacts. The loss of the existing fishponds, albeit a small area on the southern periphery, would lead to a moderate to significant adverse impact during construction and operational phases in the absence of landscape mitigation measures. This is largely due to the openness of the landscape within this area, its intervisibility and the interruption of the transition from fishpond to agricultural fields and eventually wooded hill slope. This impact on this LCA will be alleviated to moderate adverse through the utilisation of the proposed responsive building design with view corridors, a stepped building height profile which seeks to alleviate the abrupt transition with the flat landscape to the north and the proposed marshland and woodland buffer area which enhance the integration of the proposals.

11.8.25   There would be no direct impact to the Hong Kong Wetland Park (OS 1) landscape character area during the construction phase of the project. It is remote to the development site and so there would be no physical loss of landscape features within this area. However with the establishment of the proposed marsh habitat and the fishpond enhancement forming part of the development, the southern periphery of the park will be enhanced and so result in a beneficial impact following full establishment. This is largely due to the beneficial effect of extending the buffer between the built environment and the traditional fishpond landscape.

11.8.26   The impact on the existing agricultural fields to the south west of the Study Area (AGR 1) would be negligible due largely to the screening effect of the vegetation at the periphery of the village settlements. This is also true of the Yuen Long Industrial Estate (ICA 1) which will be screened from the proposed development by the landform of the Kai Shan range and the woodland associated with the lower hill slopes. There would be a negligible impact on the landscape character of the Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel (EL1) due to their distance from the proposed development site.

11.8.27   Table 116 presents the unmitigated and mitigated (residual) impacts arising from the scheme proposals during the construction and operational phases of the project. The mitigated (residual) impacts are assessed during the design year which for the purposes of this study is taken as being between 10 and 15 years after the schemes opening when the proposed mitigation planting is deemed to have reached a level of maturity sufficient for it to perform the design objectives.


Table 116       Existing Landscape Character and Predicted Impacts – Options 1A and 1B

Landscape Character Area (LCA)

Sens

Mag of Change

(Con / Oper Phase)

Main Impacts on Landscape Character Area

Impact Significance Threshold

(Unmitigated)

Mitigation Measures

Impact Significance Threshold

(Mitigated)

 

Con

Oper

Con

Oper

Natural  Upland Landscape Character Area (NUA)

 

 

 

 

 

 

 

 

NUA 1: Kai Shan Range.

The Kai Shan Range forms the dominant landform within the Study Area being characterised by a range of minor peaks creating a ridgeline on a northeast – southwest axis. The primary peak (Kai Shan) rises to 121mPD with the main secondary peak to the north of Ng Uk Tsuen rising to 62mPD. The existing service reservoir to the north of Kai Shan forms is visually apparent in views from the fishponds to the south. The hillsides are clothed in dense woodland which gives way to shrubland and grassland towards the summits.  This feature in conjunction with the fishponds to Kai Shan is important in establishing the overall landscape character of the Study Area.   

High

Condition, quality and maturity: High

Importance and rarity of special landscape features: Locally important

Ability of the LCA to accommodate change: Medium

Statutory or regulatory requirements: Complies with requirements under OZP S/YL-LFS/7

Intermediate / Small

Scale of the development relative to baseline conditions:  Intermediate

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent 

Reversibility of change: Medium

There will be no direct impacts on the Kai Shan range however indirect impacts will include the impact on the landscape setting of the range particularly in the transition from the low-lying agricultural plain. 

Moderate Adverse

Moderate Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, CP4, OP1, OP2, and OP4.

Moderate Adverse

Slight Adverse

Village Landscape Character Area (V)

 

 

 

 

 

 

 

 

V1: Ng Uk Tsuen Village Cluster

The traditional villages of Ng Uk Tsuen, Shing Uk Tsuen and Tai Tseng Wai are located in the saddle between the two main peaks described above. The villages are characterised by largely typical village houses three storeys in height with tiled facades and flat roofs with shade structures. The three villages have coalesced into a single settlement although only the properties on the northern periphery of Shing Uk Tsuen have a view over the development area. The remaining houses are largely screened by the adjacent development, and the existing landform and mature vegetation to the south of the development site.

Medium

Condition, quality and maturity: Medium

Importance and rarity of special landscape elements : Low

Ability of the LCA to accommodate change: High

Statutory or regulatory requirements: Complies with requirement under OZP S/YL-LFS/7

Intermediate

Scale of the development relative to baseline conditions:  Intermediate

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent 

Reversibility of change: Medium

 

There will be no direct impacts on the village cluster however indirect impacts will include the impact on the landscape setting of the northern village houses of Shing Uk Tsuen. The other villages areas are screened by the existing landform and the woodland situated in the saddle between the two main peaks of the Kai Shan range. The proposed construction and operation of the Southern Development Access will be within existing land take and so no long term impacts are envisaged. 

Moderate Adverse

Moderate Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Moderate Adverse

Slight Adverse

(due to full establishment of landscape buffer at the southern boundary of the development  which enhances the local landscape character)

Agriculture Landscape Character Area (AGR)

 

 

 

 

 

 

 

 

AGR1: Fung Kai Wai – Ng Tung Uk Agricultural Fields 

This LCA to the south west of the Study Area is primarily characterised by a combination of active and inactive agricultural land. The characteristics of the landscape are the fine texture of agricultural fields punctuated by low-rise village type development and large individual specimen trees and small tree groups. The development site is located to the northern edge of this character area and is enclosed on the southern side by the wooded hillsides of the Kai Shan range. 

Medium

Condition, quality and maturity: Medium

Importance and rarity of special landscape elements : Low

Ability of the LCA to accommodate change: High

Statutory or regulatory requirements: Complies with requirement under OZP S/YL-LFS/7

Negligible / Negligible

Scale of the development relative to baseline conditions:  Negligible

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: Medium

There will be no direct or indirect impact on the character of this area as it is situated to the south of the residential development site and screened by existing trees and village development.   

Negligible

Negligible

No mitigation required.

Negligible

Negligible

AGR2: Fishponds

This LCA forms the landscape character for the Study Area north of the proposed development. The ponds are generally rectangular in shape separated by earth bunds which are clothed in grass with the occasional clumps of trees and shrubs or specimen mature trees. The ponds are generally active although several areas are used for agriculture. Within this area are several isolated single storey structures located on the bunds between the ponds and are often accompanied by groups of mature trees. The ponds provide an important component of the overall landscape character of the Study Area. The low level of existing disturbance and its open, expansive nature result in a high landscape quality and sensitivity to further change.

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements : Regionally important.

Ability of the LCA to accommodate change: Low

Statutory or regulatory requirements: Complies with requirement under OZP S/YL-LFS/7

 

Small to Intermediate / Small to Intermediate

Scale of the development relative to baseline conditions: Small to intermediate

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operation Stage – Permanent 

Reversibility of change: Medium

The proposed development will be located on a platform constructed from reclaimed fishponds and so there will be a direct impact on the character of this area. However, the development area is located on the southern periphery of the fishponds therefore minimising any loss of physical integrity. A precedent has been established for development in close proximity with the fishpond area due to the development associated with Tin Shui Wai.

Significant Adverse

Significant Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Significant Adverse

Moderate Adverse

(Due to fishpond improvement and the creation of marsh habitat)

Industrial / Commercial Landscape Character Area (ICA)

 

 

 

 

 

 

 

 

ICA1: Yuen Long Industrial Estate

This LCA to the south of the Study Area is characterised by the industrial and utilitarian nature of its land uses. The industrial estate extends from the southern periphery of Tai Tseng Wai south to the Shan Pui River. These main structures within the estate include a number of large factory and warehouse complexes set within a grid like street pattern.  There is little in terms of soft landscape within the estate with the exception of intermittent street tree planting along   Wang Lee, Wang Lok and Fuk Hi Streets. This disparate mix of industrial land uses provides an incoherent landscape which is further degraded by vehicle yards and parking at ground level. The combined development serves to degrade the character of the southern part of the Study Area although this development is screened from the proposed development area.

Low

Condition, quality and maturity: Low

Importance and rarity of special landscape elements : Low importance

Ability of the LCA to accommodate change: High

Statutory or regulatory requirements: Nil

Negligible / Negligible

Scale of the development relative to baseline conditions:  Negligible

Compatibility of the project with the surrounding landscape: High

Duration of impacts: Construction stage – Nil

Operation Stage – Nil 

Reversibility of change: High

 

There will be no direct or indirect impact on the character of this area as it is removed from the development site. 

Negligible

Negligible

No mitigation required.

Negligible

Negligible

Open Space and Park Landscape Character Area (OS)

 

 

 

 

 

 

 

 

OS1: Hong Kong Wetland Park

The Hong Kong Wetland Park (HKWP) is located to the west of the Study Area forms a transitional zone or buffer between the high-rise residential development associated with Tin Shui Wai and the horizontal low-lying form of the fishponds to the east.  The Hong Kong Wetland Park will be characterised by a combination of woodland structure planting, wetland areas and open water.

High

Condition, quality and maturity: High

Importance and rarity of special landscape elements : regional important

Ability of the LCA to accommodate change: Low

Statutory or regulatory requirements: Hong Kong Country Park Ordinance

Negligible / Small

Scale of the development relative to baseline conditions: small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operation Stage – Permanent 

Reversibility of change: Medium

There will be no direct impact on the character of this area as it is remote from the residential development site.  However the proposed marsh habitat to the north of the development site will be contiguous with the HKWP and so form a continuous band of marshland along the western periphery of the fishponds.

 

 

 

 

 

 

 

Negligible

(Remote from the site)

Negligible

(Remote from the site)

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Negligible

(Remote from the site)

Slight

Beneficial

(WNR proposals enhance southern edge of HKWP)

Estuarine Landscape Character Area (EL)

 

 

 

 

 

 

 

 

EL1: Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel 

The estuarine landscapes to the north and of the Study Area are characterised by extensive mangroves giving way to areas of mudflats in the inter-tidal areas. Although the dominant vegetation is mangroves. The area is contained by the high security fence of the Closed Area Boundary which is visible from the fishpond areas to the south. The mangroves form an important vegetative component of the estuarine landscapes particularly in elevated views of the Study Area.

 

Low

Condition, quality and maturity: Low

Importance and rarity of special landscape elements: Low

Ability of the LCA to accommodate change: High

Statutory or regulatory requirements: Nil

Negligible/ Negligible 

Scale of the development relative to baseline conditions:  Negligible

Compatibility of the project with the surrounding landscape: High

Duration of impacts: Construction stage – Nil

Operation Stage – Nil

Reversibility of change: Medium

There will be no direct or indirect impact on the character of this area as it is remoted from the development site. 

Negligible

Negligible

No mitigation required.

Negligible

Negligible

Key

Landscape Sensitivity (Sens):  Low, Medium or High

Condition, quality and maturity; importance and rarity of special landscape elements; and ability of the LCA to accommodate change: Nil, Low, Medium or High

 

Magnitude of Change (Mag):   Negligible, Small, Intermediate and Large

Scale of the development relative to baseline conditions; compatibility of the project with the surrounding landscape; duration of impacts; and reversibility of change: Nil, Low, Medium or High

 

Significance Threshold:                                                            Negligible, Slight, Moderate and Significant (adverse or beneficial)

Residual Impacts:                                                                     Refer to matrix and table in methodology section

Con:                                                                                         Construction phase impacts                  

Oper:                                                                                       Operational phase impacts


 

11.9          Existing Visual Context and Visual Impacts

Existing Visual Context

Visual Envelope and Zones of Visual Influence

11.9.1      The Visual Envelope (VE) for proposed development Options 1A and 1B extends north, east and northwest across the coastal plain and estuarine landscape to the surrounding natural uplands. It is not considered that the visual envelopes for the two options would be significantly different although the visual prominence of Option 1B would be reduced from within the central and southern parts of the villages to the south of the proposed development site. The development site is bounded by the Kai Shan range to the south which serves to largely contain views. Whilst to the west the VE is contained by the existing high-rise development associated with Tin Shui Wai.  In terms of the available viewing distances typically views extend some 2.0km north, 2.5km east, 0.50km south and 1.0km west. Within this VE the extent of the existing views is determined by factors such as the presence of intervening visual obstacles and so a number of Zones of Visual Influence (ZVI) can be discerned. The VE and ZVIs are mapped on Figure 11-6 and the photographs presented as Figure 11-7 demonstrates the components which make up the existing visual amenity.

Existing Visually Detracting Elements

11.9.2      A number of the existing elements within the landscape of the Study Area may be considered as visually detracting in that they are visually incompatible with the existing landscape and visual context. The position of these elements and their role within the visible landscape is shown on including:

·        The industrial, commercial and utility development located to the north of Yuen Long including the Yuen Long Sewage Treatment Works (STW). This complex particularly the STW is prominent in views from the north and east.

·        The high-rise development associated with Tin Shui Wai which is characterised by its uniform building height, the consistent appearance of the building facades; and the developments prominence in views from the fishpond area to the north of the development site and in views from the residential areas to the east of the Study Area.

·        The drainage channel works for the Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel which have replaced the natural meandering form of the original river courses with a more engineered form. These features are prominent in elevated views of the Study Area and in views from the east.

Existing Visual Amenity and Visually Sensitive Receivers

11.9.3      In broad terms for both Options 1A and 1B there are three zones of visual influence (ZVIs), named ZVI 1, ZVI 2 and ZVI3, within the visual envelope (VE) of the development having distinct visual amenity characters in the landscape context, these ZVIs are shown on Figure 116. VSRs identified within the ZVIs are grouped by development as many of the residents of these developments and visitors looking from surrounding hillside footpath or lookout point in the VE who will be subject to similar views. The existing view, predicted impacts and recommended mitigation measures for each of the identified VSRs are presented in Table 117 and Figure 1110.

11.9.4      The visual amenity observed by VSRs inside ZVI 1 is characterised by the views over the existing fishponds. This is an area of expansive low-level views extending to the wooded hillsides and views into Deep Bay. The views along the valley floor are generally interrupted beyond the area of fishponds due to the existing vegetation particularly trees on the pond bunds. Other components of these views include the vertical forms of the high-rise development, which visually encloses the Study Area. Views within this area are generally of high to medium quality. The sensitivity of these views to further change is generally high due to the unique nature of the landscape and the relative absence of built development in views to the north and east.

11.9.5      The visual amenity observed by VSRs inside ZVI 2 is that of the natural uplands which form the main landscape and visual context for the Study Area. These upland areas form a green back cloth to many of views from within the Study Area particularly those from low level within the coastal plain and estuarine landscape. These upland areas generally form the limit to the visual envelope and so form the visual horizon. However these views to the west and south of the Study Area are interrupted due to the intervening high-rise development and the ridgeline is breached by some of the existing development particularly that of Tin Shui Wai. This would indicate that views which are already characterised by high-rise development are not sensitive to further change.

11.9.6      The visual amenity observed by VSRs inside ZVI 3 is formed by the dense high-rise development which generally serve to enclose and foreshorten internal views although offering generally spectacular views for VSRs on the periphery of the developments particularly those adjacent to the fishponds. The internal views within the development areas are generally of poor quality and have a low sensitivity to further change due to the existing level of development. Views from the properties on the periphery of these development areas are generally of high quality, as has been described above, having views over the fishponds and the estuarine landscape of Deep Bay. These views have a medium to high sensitivity to further change depending on their location and the nature of the VSRs.

11.9.7      The next section assesses the potential visual impacts arising from development Options 1A and 1B.

11.9.8      Option 1A – buildings with a maximum height of 18 storeys (8 blocks of 14-18 storeys, 7 groups of low-rise buildings of 4-8 storey including a 2 storey resident’s club house erected on 40,000m² residential site area i.e. 32.8% Site Coverage).

11.9.9      Option 1B – buildings with a maximum height of 15 storeys (9 blocks of 15 storeys, 7 groups of 4-10 storey low-rise buildings including a 2 storey resident’s club house erected on 40,000m² residential site area i.e. 34.4% Site Coverage).

Visual Impacts: Option 1A

Views from Residences

11.9.10   Residents of the new development on the north western periphery of Tin Shui Wai (VSR 1) such as residents of Tin Heng Estate and the southern periphery of Mong Tseng Wai (VSR 3) will be subject to a moderate adverse impact in the absence of mitigation measures. This is largely due to the expansive nature of the existing views and the viewing distances involved (approximately 2000-2300m). The residents of Tin Shui Wai (VSR 1) would experience a similar level of impact although for some of the lower storeys the view would be blocked or interrupted after the completion of CDA development at Area 112 in the foreground of available views.  

11.9.11   Residents on the eastern periphery of Fairview Park (VSR 4) will be subject to a slight to moderate adverse impact and Tai Sang Wai (VSR 5) a slight adverse impact in the absence of mitigation measures. The level of predicted impact is determined by the viewing angle and distances involved (2300-2400m) and the availability of other views within an expansive panorama. In addition the visible part of the development will be along the shortest development facade and will be seen against the existing high-rise development of Tin Shui Wai.

11.9.12   The residents of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) (approximately 10 houses in each case) living at the northern periphery of the villages with windows facing north to the development site will experience significant to moderate adverse impacts in the absence of mitigation measures due to their proximity to the proposed development. However views from many of these villages houses are partially obstructed by the existing landform, vegetation and structures. For other residents of the villages, pedestrians within open spaces and vehicle travellers on the roads through the villages the impacts are likely to be slight to moderate adverse due to the screening effect of adjacent village houses, the angle and viewing distance, and the proximity of existing vegetation. For these VSRs the views will be glimpsed and limited to the upper floors of the proposed development.

11.9.13   Residents of Long Ping Estate (VSR 9) to the north of Yuen Long and Tin Tsz Estate (VSR 10) who have views across the development site will be subject to a slight to moderate adverse impact in the absence of landscape mitigation measures. This is due to the proposed development will be largely screened in these views by the Kai Shan range and the impacts mitigated to an extent by the existing development in the foreground of the views. 

11.9.14   The residents of the Kenwood Court (VSR 11) on the eastern edge of Tin Shui Wai would be subject to a moderate adverse impact in the absence of mitigation measures due to the proximity of the development although the residents would have alternative views across the fishponds towards Deep Bay. The visible part of the proposed development would again be the narrowest building facade.

11.9.15   The residents of the eastern peripheral of Tin Yuet Estate (VSR 12) on the western edge of Tin Shui Wai would be subject to a moderate adverse impact in the absence of mitigation measures due to the viewing distance. In addition there is likely to be a cumulative impact for these VSRs through the proposed CDA development in Areas 103 and 104. 

11.9.16   The residents of the east facing apartments of the Vianni Cove (VSR 14) and the Grandeur Terrace (VSR 15) on the eastern periphery of Tin Shui Wai will be subject to a moderate adverse impact. The impact of the proposed development on views for those residents will be mitigated to an extent by the relatively small proportion of the view affected and the viewing distances involved. There is also likely to be a cumultaive impact for these residents with the future CDA development in Areas 112 and 115.

11.9.17   Future residents on the eastern periphery of the proposed CDA in Area 115 located adjacent to Wetland Park Road (PVSR A1) will be subject to moderate adverse impacts in the absence of mitigation measures. The level of the predicted impact will be determined by a combination of the low level of this PVSR and the screening effect of the existing vegetation to the south east of the development area, the screening effect of the proposed development inside the settlement and the viewing distances involved. 

View from Workplaces

11.9.18   Site observation would suggest that most of fishponds and agricultural lands within the Study Area are inactive and so have not been identified as VSRs in category. 

Views from Recreational Landscapes

11.9.19   Visitors to the area and locals visiting the lookout point at Tsim Bei Tsui (VSR 2) will be subject to a moderate adverse impact arising from the implementation of the development proposals. The level of the predicted impact is largely determined a combination of the transient nature of potential viewers, the viewing distances involved, the relatively small scale of the proposed development and the panoramic nature of the existing view. Walkers using the footpath trails on Kai Shan (VSR 8) will be subject to a moderate adverse impact due to the proximity of the development, the elevated viewing position and the disruption of views across the existing fishponds to Deep Bay.

11.9.20   Views available to the visitors and staff of the Hong Kong Wetland Park (VSR 13) would be mitigated to an extent by the low-lying nature of the VSR and the screening effect of the intervening vegetation both within the park and along its southern boundary. However due to the relative sensitivity of the existing view and the nature of the VSR the visual impact is likely to be moderate adverse. Again views would be limited to the very upper floors of the proposed development which would be visually permeable to an extent due to the building orientation of the four westernmost residential blocks.

Views for travellers on Public Roads and Railways

11.9.21   The potential visual impacts for vehicle travellers on the roads which run through Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) are likely to be slight to moderate adverse due to their transient nature, the screening effect of adjacent village houses and vegetation, and the angle and viewing distance. For these VSRs the views would be limited to glimpsed views of the upper floors of the proposed development.

Night-time Glare

11.9.22   The visual impacts arising from the construction and operational phases of the proposed development also relates to the potential night-time glare effects arising from the proposed lighting apparent in views from selected VSRs. The construction activities will not extend to night time, the intensity, luminance and lighting levels of these activities will be low, the night glare impact is predicted to be temporarily slight adverse to negligible. The extent of the operational impact is dependent on the architectural design, the disposition of the main elements of the built environment and the type of lighting utilised particularly the lighting within the landscape. This operational impact may be separated into two key elements, the lighting from the residential blocks and the lighting associated with the surrounding landscape and internal access roads / EVA. 

11.9.23   The residential development landscape will not require 24 hour lighting except for the lighting of access roads and emergency access.  The intensity, luminance and lighting level generated from residential properties is predicted to be relatively low in the views available to the identified VSRs and in many cases the proposed development will be seen against existing development which is also lit at night. Impacts will also be mitigated to an extent by the viewing distances involved. The lighting of the landscape and the internal access roads / EVA will also be alleviated through the use of the proposed landscape buffer along the periphery of the development and roadside planting. The potential for glare at these lower levels can also further reduced through the use of full cut off lighting. Impacts can be further reduced through the programming of the lighting within the landscape in response to the proposed activities and adjusted according to the actual need of future users. Given the adoption of the measures described above including the focussing and shielding of light sources to reduce glare and the careful tailoring of luminance levels within the landscape, the night time glare impact even for the closest of the identified VSRs in Ng Uk Tsuen and Shing Uk Tsuen is predicted to be slight. Again these impacts will only be experienced by the residents of the village house at the edge of the settlement (areas already illuminated with street lighting).

11.9.24   Table 117A and Figure 1110A presents the predicted unmitigated and mitigated (residual) impacts for the proposed scheme during the construction and operational phases of the project. The mitigated residual impacts are assessed during the design year which for the purposes of this study is taken as being between 10 and 15 years after the schemes opening when the proposed mitigation planting is deemed to have reached a level of maturity sufficient for it to perform the design objectives. For the purposes of this assessment low-rise was taken as 1-10 floors, medium-rise as 11-20 floors and high-rise as 20+ floors.


Table 117A     Visually Sensitive Receivers and Predicted Impacts – Option 1A

VSR

Existing View

Sens

Mag of Change (Con / Oper Phase)

Primary Source of Impact

 

Impact Significance Threshold

(Unmitigated)

Mitigation Measures

 

Impact Significance Threshold

(Mitigated)

Con

Oper

Con

Oper

Visually Sensitive Receivers (VSRs)

VSR 1 - Tin Shui Wai (Tin Heng Estate)

 

 

 

 

 

Primary GV and PV for residents of the new developments with views to the east although the views are long distance and likely to be severely interrupted by future development to the north of Tin Shui Wai.  The existing view extends south east across the Hong Kong Wetland Park to the remnant fishpond areas, the hill slopes of Kai Shan and beyond to the hills of the Lam Tsuen Country Park.

 

High

Type of VSRs: High-rise residential, Residential, Permanent receivers

Population of viewers: Many

Degree of visibility: GV / PV

 

 

 

 

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 2000m

 

 

Filtered GV views of the proposed development viewed against the green backdrop of the Kai Shan Range. The building height profile has been designed to mirror the existing topography. The development will be seen in the context of the high-rise development of Yuen Long and Tin Shui Wai.

The proposed development, although it forms a minor component in views for these VSRs which are dominated by Tin Shui Wai residential development in the foreground and the existence of alternative views. Night-time glare mitigated by viewing distance and the existing lighting from the villages and Yuen Long in the background).

Moderate Adverse

 

Moderate Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1, OP2, and OP4.

Moderate Adverse

 

Moderate Adverse

 

VSR 2 - Tsim Bei Tsui

 

Photomontage refers to Figures 11-14A and B for Option 1A and 11-15A and B for Option 1B

Primary OV / PV for walkers at the lookout point south over a landscape characterised by the estuarine mudflats and the existing fishpond areas. Low level views are partially screened by the existing vegetation associated with the bunds within the fishpond area whilst high level views extend to the ridgeline to the south of the development site and beyond to the uplands associated with the Lam Tsuen Country Park.

 

Medium

Type of VSRs: Lookout point, Visitors/ hikers, Transient receivers

Population of viewers: Very few

Degree of visibility: OV / PV

 

 

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 2300m

 

The proposed development will form a small component of the overall expansive OV / PV across the estuarine landscape. Views towards the summits of the hills to the east and west of the proposed development site are maintained and the proposed view corridors allow continued framed visual access to the landscape beyond.  The western and southern sections of the view are characterised by existing high-rise development associated with Yuen Long and Tin Shui Wai. The development facade will lead to the loss of part of the green component of the view and disturb the relationship between the fishponds and the saddle between the two wooded hillsides of the Kai Shan range.

Night-time glare effect mitigated by viewing distance and the existing lighting from the villages and Yuen Long in the background).

 

Moderate Adverse

 

Moderate Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Moderate Adverse

 

Moderate Adverse

 

VSR 3 - Mong Tseng Wai

 

 

Primary GV and PV for residents on the southern periphery of the settlement. Views are interrupted by existing vegetation within the agricultural fields to the south of the village and on the bunds within the fishpond areas.

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

Degree of visibility: GV / PV

Small to negligible / Small to negligible

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 2200m

 

GV and PV of the proposed development viewed against the green backdrop of the Kai Shan range. The lower floors of the proposed development screened by the intervening development and vegetation. The development will form a small component of the overall view. The proposed view corridors through the western part of the development will be evident in these views allowing some visual permeability and visual access to the Yuen Long and framed by the existing wooded hill slopes.  Night-time glare effect mitigated by viewing distance and the existing lighting from the villages and Yuen Long in the background.

Slight Adverse

 

Slight Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Slight Adverse

Slight Adverse

 

VSR 4 - Fairview Park

 

 

Primary PV for residents on the western periphery of the existing settlement. Views west extend over the Kam Tin River Estuary and fishpond areas to the proposed development site. The high-rise development of Tin Shui Wai forms the background to views to the west. The structures associated with the Yuen Long Sewage Treatment Works form a visually detracting element within these views.

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

 

Degree of visibility: PV

Small to negligible / Small to negligible

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 2400m

 

PV and NV due to availability of other views, their orientation and the presence of intervening development associated with the Yuen Long Sewage Treatment Works. The development would also be seen at an acute angle and will be partially be screened by the existing landform Kai Shan range. The proposed visual corridors in the eastern part of the development would be evident in views from this direction. 

Due to its relatively low building profile, the proposed development will visually integrate with the Yuen Long industrial area. The development forms a minor component in distant views from this location. Affected VSRs are few in numbers confined to those living at the western boundary of Fairview Park. Alternative views are available from these VSRs as their major views are facing east. Night-time glare effect is mitigated by viewing distance and the existing lighting from the villages and Tin Shui Wai in the background)

Moderate to slight adverse

Moderate to slight adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Moderate to slight adverse

Moderate to slight adverse

VSR 5 - Tai Sang Wai

 

 

Primary GV / NV for residents on the western periphery of the existing settlement. Views west extend over the Kam Tin River Estuary and fishpond areas to the proposed development site. The high-rise development of Tin Shui Wai forms the background to views to the west. The structures associated with the Yuen Long Sewage Treatment Works form a visually detracting element within these views and also serve in combination with the existing landform to screen low level views of the development site.  

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

 

Degree of visibility: GV / NV

Small to negligible / Small to negligible

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 2300m

 

GV and NV due to the viewing angle and distances involved and the availability of other views. The Yuen Long Sewage Treatment Works will also form the middle ground of views towards the development site and this has degraded the quality of the existing view. In addition the background to any views will be formed by the high-rise development of Tin Shui Wai.

Due to the low building profile, majority of the proposed development is partially screened by the sewage treatment plant and existing landform. The development forms a minor component in distant views available for these VSRs. Night-time glare effect mitigated by viewing distance and the existing lighting from the villages and Tin Shui Wai in the background.

Slight Adverse

Slight Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Slight Adverse

Slight Adverse

 

VSR 6 - Ng Uk Tsuen

 

Photomontage refers to Figures11-14O and P for Option 1A and 11-15 O and P for Option 1B.

Primary OV and PV for residents on the northern periphery of the village although views are largely screened by the existing landform and intervening vegetation.

Primary NV / GV for residents within the village where views are largely screened by a combination of the existing village houses, landform and intervening vegetation. 

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

Degree of visibility: OV / PV

Intermediate / Intermediate

(Small / Small)

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Large to medium / 200m

 

OV and PV of the middle and upper storeys of the proposed development from properties on the northern periphery of the development.

NV and GV upper storeys of the proposed development from properties on the northern periphery of the development.

Impacts due to the proximity of the proposed development. Although many of the existing houses have views away from the proposed development or their views are already interrupted by vegetation and other village houses. Night-time glare effect mitigated to an extent by existing street lighting at the edge of the village and the screening effect of the intervening obstacles.

 

Significant to Moderate Adverse (houses on the northern edge of the village)

Moderate to slight adverse (houses within the centre of the village and the open spaces)

Significant to Moderate Adverse (houses on the northern edge of the village)

Moderate to slight adverse (houses within the centre of the village and the open spaces)

Primary mitigation including the architectural design and secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Significant to Moderate Adverse (houses on the northern edge of the village)

Moderate to slight adverse (houses within the centre of the village and the open spaces)

Significant to Moderate Adverse (houses on the northern edge of the village)

Moderate to slight adverse (houses within the centre of the village and the open spaces)

VSR 7 - Shing Uk Tsuen

Photomontage refers to Figures11-14K snd L; and  Figures11-14M and N for Option 1A. For Option 1B refer to Figures11-15K snd L; and  Figures11-15M and N

Primary PV / GV for residents on the northern periphery of the village although views are severely interrupted by the existing landform and vegetation particularly trees on the agricultural land at the base of the hill slope.

Primary NV / GV for residents within the village where views are largely screened by a combination of the existing village houses, landform and intervening vegetation.

 

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

 

Degree of visibility: PV / GV

Intermediate / Intermediate

(Small / Small)

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Large to medium / 175m

 

PV and GV of the middle and upper storeys of the proposed development from properties on the northern periphery of the development.

NV and GV upper storeys of the proposed development from properties on the northern periphery of the development.

Impacts due to the proximity of the proposed development. Although many of the existing houses have views away from the proposed development or their views are already interrupted by vegetation and other village houses. Night-time glare effect mitigated to an extent by existing street lighting at the edge of the village and the screening effect of the intervening obstacles.

 

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight / Moderate Adverse

(houses within the centre of the development and the open spaces)

 

 

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight / Moderate Adverse

(houses within the centre of the development and the open spaces)

 

 

Primary mitigation including the architectural design and secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight / Moderate Adverse

(houses within the centre of the development and the open spaces)

 

 

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight / Moderate Adverse

(houses within the centre of the development and the open spaces)

 

 

VSR 8 - Kai Shan

 

 

Primary PV / GV for walkers using the trail to the summit of Kai Shan. The available views are interrupted and screened in some locations by the existing woodland lining the hill slopes. Long distance views extend across the fishponds to the Lau Fau Shan peninsular and the mudflats associated with the estuary of the Kam Tin River. 

 

Medium

Type of VSRs: Footpath, Pedestrians, Transient receivers

Population of viewers: Very few

Degree of visibility: PV / GV

 

Intermediate / Intermediate

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Medium to small / 800m

 

PV and GV of the proposed development for walkers using the trail to the summit of Kai Shan. The development would partially screen views of the fishponds to the north although views to the north west are already dominated by the high-rise of Tin Shui Wai.   Some views interrupted by service reservoir in the foreground, small number of transient VSRs affected. Night-time glare effect mitigated to an extent by existing street lighting at the edge of the village, the viewing distance and the screening effect of the intervening landform and vegetation.

Moderate Adverse

Moderate Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Moderate Adverse

Moderate Adverse

 

VSR 9 - Long Ping Estate

 

 

Primary GV / NV of the existing development site for residents on the northern periphery of the estate north towards Kai Shan. Views beyond the ridgeline to the fishponds and the Lau Fau peninsular are framed by the existing landform.

 

High

Type of VSRs: High-rise residential, Permanent receivers

Population of viewers: Many

 

Degree of visibility: GV / NV

 

Small to negligible / Small to negligible

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 1700m

 

GV of the proposed upper storeys of the proposed building blocks.  Development will form a small component of the overall view available to residents with a north facing apartments. In addition the quality of the existing view has been degraded by the existing level of development particularly that associated with the Yuen Long Industrial Estate.

Night-time glare effect mitigated to an extent by existing street lighting within the intervening villages and the viewing distances.

Slight to Moderate Adverse

 

Slight to Moderate Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation OP1.

Slight to Moderate Adverse

 

Slight to Moderate Adverse

 

VSR 10 - Tin Tsz Estate

 

 

Primary PV / GV for residents on the north east periphery of the development although views are severely interrupted by the intervening landform. Higher-level views extend across the fishponds to the Lau Fau Shan peninsular and the mudflats associated with the estuary of the Kam Tin River. 

 

High

Type of VSRs: High-rise residential, Permanent receivers

Population of viewers: Intermediate

Degree of visibility: PV / GV

 

Small to negligible / Small to negligible

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 1500m

 

PV and GV of the upper storeys of the proposed development partially screened by the existing landform of the summit of Kai Shan. The existing view is degraded to an extent by the development associated with the northern part of Yuen Long and the modifications made to the hill slopes of Kai Shan during the construction of the service reservoir.

Therefore only VSRs living at the elevated floors will have GV of the upper floors of the development. Alternative views are available from these VSRs. Night-time glare effect is mitigated to an extent by existing street lighting in development s such as Fairview Park, the screening effect of the intervening obstacles and the viewing distances.

Slight to Moderate Adverse

Slight to Moderate Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation OP1.

Slight to Moderate Adverse

Slight to Moderate Adverse

VSR 11 – Kenswood Court

 

Photomontage refers to Figures11-14 I and J for Option 1A and 11-15 I and J for Option 1B.

Primary PV / GV for residents on the north east periphery of the development although views are severely interrupted by the intervening landform. Higher level views extend across the fishponds to the Lau Fau Shan peninsular and the mudflats associated with the estuary of the Kam Tin River. 

 

High

Type of VSRs: High-rise residential, Permanent receivers

Population of viewers: Intermediate

 

Degree of visibility: PV / GV

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 1000m

 

PV and GV of the proposed development partially screened by the existing landform of the Kai Shan range. In this view the narrowest elevation of the proposed development would be visible thus minimising its apparent scale within the landscape. In addition the proposed view corridors through the western portion of the proposed development would be evident in these views. Therefore the development forms a minor component in views looking towards Kai Shan and Pat Shi Leng. Affected VSRs limited to people living in Kenswood Court with views looking towards the Yuen Long industrial area. Their visual access looking towards the knoll adjacent to Ng Uk Tsuen will be partially screened by the development. However, views looking towards the knoll in the foreground and Pat Sin Leng in the background will not be affected by the development. Night-time glare effect mitigated to an extent by existing street lighting in developments such as Fairview Park, the screening effect of the intervening obstacles and the viewing distances.

Moderate Adverse

Moderate Adverse

 

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation OP1.

Moderate Adverse

Moderate Adverse

(Mitigation measures including building design and disposition plus landscape mitigation effective in partially mitigating impacts).

 

VSR 12 -

Tin Yuet Estate, Tin Shui Wai

 

 

Primary PV for residents on the eastern side of the development across the Hong Kong Wetland Park towards the proposed development site. Long distance views extend over the Kam Tin River estuary towards the uplands of the Lam Tsuen Country Park. 

High

Type of VSRs: High-rise residential, Permanent receivers

Population of viewers: Intermediate

 

Degree of visibility: PV

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 1500m

 

PV for residents in the elevated floors on the eastern side of the developments with views of the Study Area. As with 11 above the smallest elevation of the development and the view corridors in the western portion of the proposed development will be visible minimising the potential visual intrusion caused by the scheme.  In addition the proposals make up a small part of the overall view. Night-time glare effect mitigated to an extent by existing street lighting at the edge of the adjacent villages and the viewing distances.

Cumulative impacts due to the future planned residential development at Area 103 and 104 in their foreground, the cumulative impact are therefore not significant with landscape mitigation measures fully established.

Moderate Adverse

Moderate Adverse

Primary mitigation including the location and footprint of the proposed development Secondary mitigation OP1.

Moderate Adverse

Moderate Adverse

(Mitigation measures including building design and disposition plus landscape mitigation effective in partially mitigating impacts).

 

 

 

VSR 13 – Hong Kong Wetland Park

 

Photomontage refer to Figure 11-14E and F for Option 1A and 11-15E and F for Option 1B.

Primary GV and PV for visitors to the wetland south towards the development site. The views will be interrupted to an extent by the existing and proposed vegetation associated with the park and the fishpond bunds.  The ridgeline to the south of the development site forms a green back drop to the flat estuarine plain. The uplands of the Lam Tsuen Country Park form the background to longer distance views.

 

Medium

Type of VSRs: Visitor Centre and facilities, visitors and staff, Transient receivers

Population of viewers: Intermediate

 

Degree of visibility: GV / PV

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Medium to small / 1300m

 

GV and PV due to the proposed buffer woodland planting for HKWP. Low level views would also be partially screened by the existing trees located on the fishpond bunds. The proposed development would form a small component of the overall views available being visible just above the horizon formed by the vegetation.

Night-time glare effect mitigated to an extent by existing street lighting in the surrounding development particularly Tin Shiu Wai and the backdrop formed by Yuen Long , the viewing distance and a combination of the low lying nature of the VSR and the screening effect of intervening vegetation.

 

Moderate Adverse

Moderate Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Moderate Adverse

Moderate Adverse

VSR 14 – Vianni Cove, Tin Shui Wai North

 

Photomontage refer to Figures11-14G and H for Option 1A and 11-15G and H.

Primary PV / GV for residents on the north east periphery of the development although low level views are severely interrupted by the intervening landform and vegetation. Higher level views extend across the fishponds to the Lau Fau Shan peninsular and the mudflats associated with the estuary of the Kam Tin River.  The uplands of the Lam Tsuen Country Park form the background to longer distance views.

High

Type of VSRs: High-rise residential, Residential, Permanent receivers

Population of viewers: Intermediate

 

Degree of visibility: PV / GV

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Medium to small / 1200m

 

PV and GV of the eastern side of the development although low-level views would be largely screened by the existing vegetation on the existing fishpond bunds and the Open Space at Area 120. The proposed development forms a minor component of the wide panoramic views and will be seen against the backdrop of Ng Uk Tsuen and the Yuen Long industrial area. Although views looking towards the knoll adjacent to Ng Uk Tsuen will be partially screened, alternate views are available from these VSRs.

Night-time glare effect is mitigated to an extent by existing street lighting in villages / Yuen Long to the south of the proposed development and the viewing distance.

Potential cumulative impact due to the development of the CDA development at Area 115 which will form foreground to views.

Moderate Adverse

Moderate Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation OP1 and OP2.

Moderate Adverse

Moderate Adverse

(Mitigation measures including building design and disposition plus landscape mitigation effective in partially mitigating impacts).

 

VSR 15  - Grandeur Terrace, Tin Shui Wai North

 

 

Primary PV for residents on the eastern side of the development across the Hong Kong Wetland Park towards the proposed development site. Long distance views extend over the Kam Tin River estuary towards the uplands of the Lam Tsuen Country Park. 

 

 

High

Type of VSRs: High-rise residential, Residential, Permanent receivers

Population of viewers: Intermediate

Degree of visibility: PV

Small / Small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 1600m

 

PV for residents on the elevated floors on the eastern side of the developments with views of the Study Area. This area on the north-eastern side of the Tin Shui Wai New Town (Area 103) is intended as a high-density development. Residents are likely to have elevated views of the development proposals although it would form a relatively small component of the overall view available and at a viewing distance both factors which will minimise potential impacts.

The views looking towards the knoll adjacent to Ng Uk Tsuen will be partially screened in the visual context of Yuen Long industrial area.

Night-time glare effect mitigated to an extent by existing street lighting in villages to the south of the proposed development and the viewing distances.

Moderate Adverse

Moderate Adverse

 

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation OP1 and OP2.

Moderate Adverse

Moderate Adverse

(Mitigation measures including building design and disposition plus landscape mitigation effective in partially mitigating impacts).

 

Planned Visually Sensitive Receivers

PVSR A1 – Comprehensive Development Area

 

 

Primary NV and GV for future residents of site 115 to the northwest of the proposed development area. Low-level views of the development area would be screened by the existing intervening vegetation and the planting associated with the proposed open spaces and the Hong Kong Wetland Park on the eastern periphery of Tin Shui Wai.

 

High

Type of VSRs: Medium-rise residential, Residential, Permanent receivers

Population of viewers: Intermediate

Degree of visibility: NV and GV

Medium to small / Medium to small

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Small / 1000m

 

NV and GV for future residents with views from the upper storeys of the proposed development in properties on the eastern periphery of area 115. Due to viewing distance, the development forms a minor component in views and will be seen against Ng Uk Tsuen and the Yuen Long industrial area. This assessment is based on the assumption that this CDA will be completed before the proposed development. If the proposed development is in place first, negligible impact is expected from these VSRs as the baseline condition will have changed.

Night-time glare effect mitigated to an extent by existing street lighting in villages to the south of the proposed development and the viewing distances.

 

Moderate Adverse

Moderate Adverse

Primary mitigation including the location and footprint of the proposed development. Secondary mitigation CP1, OP1 and OP2.

Moderate Adverse

Moderate Adverse

Key

 

Landscape Sensitivity (Sens): Low, Medium or High

Population of viewers: Very Few, Few, Intermediate or High

Magnitude of Change (Mag): Negligible, Small, Intermediate and Large

Compatibility of the project with the surrounding landscape: Low, Medium or High

Reversibility of change: Irreversible or Reversable  (Changes may be reversed if the development were removed).

Scale and distance of the impact: Small, Medium or Large

The viewing distance is measured from the façade of the building or location that forms the Visually Sensitive Receiver to nearest visible part of the proposed scheme.

 

Degree of Visibility / Extent of the View Occupied by the Development:

NV           no view; (or difficult to perceive);

GV           glimpse: a transient view or distant view in the context of the wider landscape, or scope of the view;

PV           partial view: a clear view of part of the site; a partial view of most of it; or a distant view in which the site forms a relatively small section of a wider view; and

OV           open view: a panoramic view of most of the site, occupying most of the field of vision.

 

Significance Threshold:           Negligible, Slight, Moderate and Significant (adverse or beneficial)

Residual Impacts:                   Refer to matrix and table in methodology section

Con:                                        Construction phase impacts

Oper:                                      Operational phase impacts

 


Visual Impacts: Option 1B

Views from Residences

11.9.25   The potential visual impacts arising from Option 1B will be broadly similar to those identified for Option 1A. The main differences are likley to be for the residents of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) (approximately 10 houses in each case) living at the northern periphery of the villages with windows facing north to the development site will experience a similar level of impact (moderate to significant adverse) to that predicted for Option 1A. Again views from many of these village houses are partially obstructed by the existing landform, vegetation and structures. For other residents of the villages, pedestrians within open spaces and vehicle travellers the impacts are likely to be slight adverse due to the screening effect of adjacent village houses, the angle and viewing distance, and the proximity of existing vegetation. This is less significant than the impacts which are likely to accrue from Option 1A due largely to the reduced building height, although there will still be some glimpsed views of the upper floors of the proposed development.  

Views for travellers on Public Roads and Railways

11.9.26   The potential visual impacts for vehicle travellers on the roads which run through Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) are likely to be slight to moderate adverse due to their transient nature, the screening effect of adjacent village houses and vegetation, and the angle and viewing distance. For these VSRs the views would be limited to glimpsed views of the upper floors of the proposed development.

Night-time Glare

11.9.27   Due to the broadly similar characteristics of both development options 1A and 1B and the asdoption of the mitigation measures described in this report the potential glare impacts at night time will be the same as those described for Option 1A. 

11.9.1      Table 117B and Figure 1110B presents the predicted unmitigated and mitigated (residual) impacts for the proposed scheme during the construction and operational phases of the project. The mitigated residual impacts are assessed during the design year which for the purposes of this study is taken as being between 10 and 15 years after the schemes opening when the proposed mitigation planting is deemed to have reached a level of maturity sufficient for it to perform the design objectives. For the purposes of this assessment low-rise was taken as 0-10 floors, medium-rise as 11-20 floors and high-rise as 20+ floors. The table highlights the main differences in the potential impacts between Options 1A and 1B.


Table 117B     Visually Sensitive Receivers and Predicted Impacts – Option 1B

 

VSR

Existing View

Sens

Mag of Change (Con / Oper Phase)

Primary Source of Impact

 

Impact Significance Threshold

(Unmitigated)

Mitigation Measures

 

Impact Significance Threshold

(Mitigated)

Con

Oper

Con

Oper

Visually Sensitive Receivers (VSRs)

VSR 6 - Ng Uk Tsuen

 

Photomontage refers to Figures11-15O and P

 

Primary OV and PV for residents on the northern periphery of the village although views are largely screened by the existing landform and intervening vegetation.

Primary NV / GV for residents within the village where views are largely screened by a combination of the existing village houses, landform and intervening vegetation.

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

 

Degree of visibility: OV / PV

Intermediate / Intermediate

(Small / Small)

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Large to medium / 200m

 

OV and PV of the middle and upper storeys of the proposed development from properties on the northern periphery of the development.

NV and GV upper storeys of the proposed development from properties on the northern periphery of the development.

Impacts due to the proximity of the proposed development. Although many of the existing houses have views away from the proposed development or their views are already interrupted by vegetation and other village houses. Night-time glare effect mitigated to an extent by existing street lighting at the edge of the village and the screening effect of the intervening obstacles.

 

Significant to Moderate Adverse (houses on the northern edge of the village)

Slight adverse (houses within the centre of the village and the open spaces)

Significant to Moderate Adverse (houses on the northern edge of the village)

Slight adverse (houses within the centre of the village and the open spaces)

Primary mitigation including the architectural design and secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Significant to Moderate Adverse (houses on the northern edge of the village)

Slight adverse (houses within the centre of the village and the open spaces)

Significant to Moderate Adverse (houses on the northern edge of the village)

Slight adverse (houses within the centre of the village and the open spaces)

VSR 7 - Shing Uk Tsuen

Photomontage refers to Figures11-15K and L

Photomontage refers to Figures11-15M and N

Primary PV / GV for residents on the northern periphery of the village although views are severely interrupted by the existing landform and vegetation particularly trees on the agricultural land at the base of the hill slope.

Primary NV / GV for residents within the village where views are largely screened by a combination of the existing village houses, landform and intervening vegetation.

 

High

Type of VSRs: Low-rise residential, Residential, Permanent receivers

Population of viewers: Few

 

Degree of visibility: PV / GV

Intermediate / Intermediate

(Small / Small)

Compatibility of the project with the surrounding landscape: Medium

Duration of impacts: Construction stage – Temporary

Operational Stage – Permanent

Reversibility of change: Irreversible

Scale and distance of the impact: Large to medium / 175m

 

PV and GV of the middle and upper storeys of the proposed development from properties on the northern periphery of the development.

NV and GV upper storeys of the proposed development from properties on the northern periphery of the development.

Impacts due to the proximity of the proposed development. Although many of the existing houses have views away from the proposed development or their views are already interrupted by vegetation and other village houses.

Night-time glare effect mitigated to an extent by existing street lighting at the edge of the village and the screening effect of the intervening obstacles.

 

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight Adverse

(houses within the centre of the village and the open spaces)

 

 

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight Adverse

(houses within the centre of the village and the open spaces)

 

 

Primary mitigation including the architectural design and secondary mitigation CP1, CP3, CP4, OP1, OP2, and OP4.

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight Adverse

(houses within the centre of the village and the open spaces)

 

 

Significant to Moderate Adverse

(village houses at the northern edge of the village)

Slight Adverse

(houses within the centre of the village and the open spaces)

 

 

Key

 

Landscape Sensitivity (Sens): Low, Medium or High

Population of viewers: Very Few, Few, Intermediate or High

 

Magnitude of Change (Mag): Negligible, Small, Intermediate and Large

Compatibility of the project with the surrounding landscape: Low, Medium or High

Reversibility of change: Irreversible or Reversable (Changes may be reversed if the development were removed).

Scale and distance of the impact: Small, Medium or Large

The viewing distance is measured from the façade of the building or location that forms the Visually Sensitive Receiver to nearest visible part of the proposed scheme.

 

Degree of Visibility / Extent of the View Occupied by the Development:

NV           no view; (or difficult to perceive);

GV           glimpse: a transient view or distant view in the context of the wider landscape, or scope of the view;

PV           partial view: a clear view of part of the site; a partial view of most of it; or a distant view in which the site forms a relatively small section of a wider view; and

OV           open view: a panoramic view of most of the site, occupying most of the field of vision.

 

Significance Threshold:           Negligible, Slight, Moderate and Significant (adverse or beneficial)

Residual Impacts:                   Refer to matrix and table in methodology section

Con:                                        Construction phase impacts

Oper:                                      Operational phase impacts


 

11.10      Cumulative Impacts

11.10.1   A number of projects are planned within the Study Area, which will result in landscape and visual impacts including the degradation of landscape character and visual amenity, and the loss of landscape resources.

11.10.2   Mitigation measures to address landscape and visual impacts have been incorporated into the design of each of the approved projects. The resulting changes to the existing landscape character, landscape resources and visual amenity have been taken into account in the baseline assessment. Cumulative impacts from these projects are therefore taken into account through their inclusion in the baseline conditions for this EIA.   

11.10.3   Section 2.3 of the EIA Report lists the concurrent projects which would potential lead to cumulative impacts whilst Figure 2-12 shows their location. These concurrent projects include the Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2 particularly in respect of the proposed twin rising mains which will follow an alignment along the southern boundary of the proposed development site. As discussed in Section 2.3, there is likely to be negligible cumulative impact during the construction and operational phases. 

11.10.4   The development of the CDA sites to the northeast of Tin Shui Wai will also contribute to a cumulative impact in the local area with the transformation of largely rural views for the adjacent VSRs to something more urban in character. However it may be argued that the construction of medium and low-rise development along the urban edge will serve to provide a more subtle integration of the existing high-rise development into its landscape and visual setting.

11.10.5   The construction of the Hong Kong Wetland Park has been completed and therefore will not lead to cumulative landscape and visual impacts for the two projects. In terms of the operational phase cumulative impacts it is likely that the combined affect of the two projects will not significantly increase the impacts predicted for the development at Fung Lok Wai in isolation.

11.10.6   Therefore the cumulative impact of the concurrent proposals identified above will not lead to a further degradation of either the landscape character or visual amenity of the Study Area beyond that predicted for the development proposals.

 

11.11      Mitigation Measures

11.11.1   The landscape mitigation measures described in this report are at a level which both demonstrates their ability to alleviate the potential landscape and visual impacts identified in the assessment and also to allow the proposals to be carried forward during the detailed design stage. The measures proposed for Options 1A and 1B adopt the same approach. More detailed landscape proposals will be developed during the initial stages of the design and construction phase of this project following the completion of the detailed Tree Survey Report. The measures are designed to address both the construction and operational phases of the project.

11.11.2    The landscape and visual mitigation measures are described both in a generic sense for measures, which apply to all of the development site and in terms of the proposed landscape strategy for the amenity areas within the development. The aim of the mitigation measures is to:

·        Alleviate where possible those landscape and visual impacts which are unavoidable through the option selection process including the site planning for the footprint and height profiles;

·        Establish a coherent and integrated landscape framework for the development site drawing together the visually disparate components of the proposed development;

·        Enhance the existing landscape and visual context of the surrounding areas providing integration between the development and its context; and

·        Provide a co-ordinated approach between the ecological and landscape mitigation proposals where there is an interface.

11.11.3   The Design Concept Drawing presented as Figure 1111A and 11-12A demonstrates the main landscape and visual mitigation strategies while Figure 11-12B and 11-12B Landscape Master Plan and Figure 11- 13 A,B,C and D Sections show the proposed landscape treatment for both the proposed housing development.

11.11.4   It is recommended that the Environmental, Monitoring and Audit Requirements (EM&A) for landscape and visual resources described in Section 16 of this report is undertaken during both the construction and operational phases of the project.  

Primary Mitigation Measures

11.11.5   In accordance with the EIAO TM, the hierarchy for landscape and visual impact mitigation is first avoidance of impact, then minimisation of impact and finally compensation of impact. As has been described in Section 3 and Section 11.4 above the selection of the preferred scheme option has been undertaken to fulfil the following objectives:

·        Minimisation of the cumulative impact, as far as possible, to the landscape through for example the maintenance of the green buffer between the proposed development site and the existing and proposed high-rise development associated with the Tin Shui Wai development. In both options 1A and 1B the affectivity of the green buffer has been further enhanced through the movement of the development footprint a further 150m to the east; 

·        Protection of areas of high landscape quality including the green backdrop formed by the existing Kai Shan range which is an important component in existing and proposed views from the Tin Shui Wai development;

·        Maintenance of the unique landscape character of the Study Area as a resource for the HK SAR, this is apparent in the proposed mitigation measures for the proposed development whereby impacts to the large part of the existing fishpond area have been avoided through the location of the development on its southern periphery; and,

·        Rehabilitation and enhancement of existing landscapes following the completion of the construction phase of the project, this will be apparent in the enhancement of the fishpond areas to the north of the proposed development site.

11.11.6   In accordance with the EIAO TM, mitigation measures for the construction and operational phases of the development have been designed to minimise predicted landscape and visual impacts, and to compensate for lost landscape resources as far as is possible given the project constraints. 

Secondary Mitigation Measures

11.11.7   A series of mitigation measures designed to alleviate impact and where possible compensate for loss of landscape resources, change of landscape character and visual amenity for VSRs resulting from the construction and operational phases of the project are described in Table 115 to Table 117 and Table 118 to Table 119 below. The measures are common to both Options 1A and 1B. The implementation and funding of the amenity landscape areas associated with the proposed residential development will be undertaken by the project proponent, and the subsequent management and maintenance will be undertaken by the owners. The exception to this will be the improvements to the Southern Development Access., i.e. the existing Fuk Shun Street. These improvements will be funded and implemented by the project proponent although the management and maintenance of the soft landscape for the improved access will remain at the responsibility of the Leisure and Cultural Services Department and all hardworks at the responsibility of Highways Department. Both departments have agreed in principle to continue their responsibility for the management and maintenance of the improved access.  The management and maintenance of the proposed Wetland Nature Reserve will be undertaken by the project proponent or its designated successor e.g. an independent Foundation taking over the long term management of the WNR upon the Government’s approval.

Table 118       Proposed Construction Phase Mitigation Measures

Mit. Code

Mitigation Measure

CP1

 

Preservation of Existing Vegetation - The development proposals would avoid disturbance to the existing trees as far as practicable within the confines of both the development site, Southern Development Access and the proposed Wetland Nature Reserve (WNR). It is recommended that a full tree survey and felling application will be undertaken and submitted for approval by the relevant government departments in accordance with ETWB TCW No. 3/2006 Tree Preservation during the detailed design phase of the project. Where possible all trees which are not in conflict with the proposals would be retained and shall be protected by means of fencing where appropriate to prevent potential damage to tree canopies and root zones from vehicles and storage of materials. Specifications for the protection of existing trees will be circulated for approval by the relevant government authorities during the preparation of the detailed tree survey.

CP2

 

Preservation of Existing Topsoil  - Topsoil disturbed during the construction phase will be tested using a standard soil testing methodology and where it is found to be worthy of retention stored for re-use. The soil will be stockpiled to a maximum height of 2m and will be either temporarily vegetated with hydroseeded grass during construction or covered with a waterproof covering to prevent erosion. The stockpile should be turned over on a regular basis to avoid acidification and the degradation of the organic material, and reused after completion. Alternatively, if this is not practicable, it should be considered for use elsewhere, including other projects.

CP3

 

Development Site and Temporary Works Areas - The landscape of these works areas would be restored following the completion of the construction phase. Construction site controls shall be enforced, where possible, to ensure that the landscape and visual impacts arising from the construction phase activities are minimised including the storage of materials, the location and appearance of site accommodation and the careful design of site lighting to prevent light spillage. Screen hoarding may not be a practicable for this project due to the viewing distances involved and the elevated viewing position of the majority of VSRs.

CP4

 

Mitigation Planting - Replanting of disturbed vegetation should be undertaken at the earliest possible stage of the construction phase of the project and this should use predominantly native plant species. All imported plants should be quarantined in local nursery for a minimum of 1 month to check there are no symptoms of infection by pests or diseases prior to planting on site. It is proposed that the origin of the trees be established through site visits to the nursery. In addition, certain trees will be brought to a temporary holding nursery at a small size as early in the construction period as possible and grown to the semi-mature size required as part of the proposed mitigation planting. This nursery will be located either on site or within the local area.

CP5

 

Transplantation of Existing Trees - Existing trees to be transplanted as shown in the Landscape Master Plan (approximately 28 trees), final recipient site will subject to the findings of the detailed tree survey and felling application undertaken at the detailed design stage

 

Table 119       Proposed Operational Phase Mitigation Measures

Mit. Code

Mitigation Measure

OP1

 

Design of Built Development - the proposed residential development will incorporate design features including:

·          Stepped building height principle – The proposed residential blocks for Option 1A will range in height from 14 to 18 floors fronted by low-rise buildings in order to provide a greater sense of visual integration with the existing landscape context and mirror the form of the existing landform particularly the ridgeline to the south of the development site. The proposed built form will also provide a more visually interesting architectural form contrasting with the abrupt nature of the existing development associated with Tin Shui Wai. Whereas Option 1B will adopt a common height (15 storeys) for the blocks which will also be fronted by low-rise buildings which also serve to enhance the development’s visual integration.

·          Building massing and permeable development facade - the proposed use of slightly higher building blocks for Option 1A has allowed the incorporation of significant view corridors and the creation of voids in the façade of each of the blocks allowing views through the development to the green backdrop formed by the wooded hillsides to the south. These view corridors and viods within the façade of each block also allow the development to avoid the walling effect evident in the existing developments to the south and west particularly when viewed from locations such as the development in the northern part of Tin Shui Wai. The adoption of a slightly lower building height for Option 1B will require the introduction of one additional block and a subsequent reduction in the width of the proposed view corridors.

·          Maintenance of existing ridgeline and green backdrop – the proposed development form allows the maintenance of the existing ridgeline and green backdrop to the south of the development site even in relatively close views. This is achieved in Options 1A and 1B through a combination of the building heights and the creation of the view corridors.

·          Colour treatment of building facades - the architectural design for both Option 1A and 1B seeks to reduce the apparent visual mass of the development further through the use of colour blocking utilising range of visually recessive earth colours and tones on the facades of the different blocks.

·          Underground car parking - the proposed development for Options 1A and 1B  will utilise underground car parking in order to maximise the area available for landscaping and minimise potential impacts of extensive hard surfaced areas in elevated views both within and without the development site.

·          Responsive building finishes - In terms of the building finishes for Options 1A and 1B natural tones should be considered for the colour palette with non-reflective finishes are recommended on the outward facing building facades to reduce glare effect. 

·          Responsive lighting design – Aesthetic design of architectural and road lighting with following glare design measures:

o         Directional and full cut off lighting is recommended particularly for recreation and roadside areas to minimise light spillage to the surrounding areas.

o         Minimise geographical spread of lighting, only applied for safety at the key access points and staircases;

o         Limited lighting intensity to meet the minimum safety and operation requirement; and

o         High pressure sodium road lighting is recommended for more stringent light control reducing spillage and thus visual impacts.

 

OP2

 

Landscape Buffer Planting – According to the guidelines provided in the Final Report of the Fish Pond Study at Deep Bay Area, the buffer area will extend around the periphery of the development to the proposed marsh habitat in WNR providing screening of the development at low levels and creating a transitional structure, not less than 50m wide, between the low-lying fishponds of the WNR and the upright forms of the proposed built development. This planting in addition to the proposed bamboo planting proposed as part of the ecological mitigation measures will also serve to visually integrate the proposals into the existing landscape framework.  The buffer will utilise native tree species to link where possible to the existing wooded areas with the advantage of creating a more coherent landscape framework whilst also improving the ecological connectivity between existing woodland habitats. A woodland management programme will be employed during the operational phase of the project with the objective of conserving and enhancing the ecological interest (approximate area 3750 square metres equating to 750 trees at 2.5m planting centres).

Apart from the landscape buffer planting, some limited tree clusters will be planted on bunds within the WNR to facilitate the establishment of habitat for different bird species. The primary objective of the tree planting within the WNR will be ecological in the creation of a favourable habitat for birds rather than for amenity purposes. As such within the fishpond or freshwater marshland area, trees will be planted in small clusters in positions designed not to intrude upon the bird flight lines, create enclosure or shade the marshland and fishponds. Some fruit-bearing trees, such as Ficus hispida, Ficus microcarpa and Melia azedarach, are recommended from ecological perspectives to enhance foraging opportunities for some bird species.  Whilst wide canopied tree species such as Ficus microcarpa in combination with bamboo species such as Bambusa eutuldoides are recommended to be planted at the edge of the alternative egretry I in order to provide a favourable habitat for the egrets and screen the area from human activity.  

 

OP3

Landscape Strategy for the Design of Amenity Space - The proposals are described in detail below (approximate area 3.4 ha).

OP4

Compensatory Planting Proposals - the planting proposals for the residential amenity areas and landscape woodland buffer areas presented as Figure 11-12, Landscape Master Plan include some 300 new specimen trees in addition to the 3750 square metres of mass woodland planting described under OP2 above would be established within the project boundary. The proposed planting of some 1050 trees will result in a compensatory planting ratio of 2.6:1 (new tree planting: trees recommended for felling). This compares favourably with the report's assertion that some 399 trees would be felled due to the proposals in this area. Following the retention of existing trees, the successful establishment of newly planted trees and the transplantation of some of the existing trees, the project area will contain approximately 1316 trees. Trees forming part of the landscape buffer area will utilise species native to Hong Kong while the species selection for the areas within the development site will respond to the landscape concept for the area. These proposals will be subject to the detailed design stage of the project.

OP5

Southern Development Access – the landscape of the road corridor will be restored to its existing condition following the completion of the road enhancement works.

 

Landscape Strategy

11.11.8   The Landscape Master Plan (LMP) is for Option 1A presented as Figure 1111B and with supporting sections presented as Figure 1113 A and B; and Option 1B as Figure 1112B and Figure 1113C and D respectively. The design of the amenity landscape areas has the following landscape design objectives:

·        Provide a quality outdoor environment for the future residents providing for their future recreational needs including outdoor active and passive recreational facilities;

·        To maximise the area of vegetation particularly tree planting within the development site to enhance the environmental quality of the development. The use of extensive use of planting will also create shade serving to reduce the solar gain of the hard surfaces particularly the hard paved areas and building facades; and

·        Create a landscape buffer through the combination of the proposed woodland and marsh buffer planting, not less than 50m wide, providing a measure of landscape and visual integration in elevated views of the scheme proposals and providing screening and softening of the built form in low level views.

11.11.9   The Landscape Master Plan comprises a series of elements that respond to the future requirements of the users. The proposed landscape treatments that comprise the Landscape Master Plan have for the purposes of this description have been separated into treatments or approaches.

Landscape Design Concept

11.11.10                       The landscape design concept for both Options 1A and 1B is divided into two different components the landscape design for residential development and the buffer planting areas. The concept provides a synthesis between a contemporary design philosophy and sustainable development principles. The spatial hierarchy involves movement from the public areas to more intimate spaces. The proposed clubhouse, swimming pool and roundabout courtyard form the central focus for residents within the development. The roundabout courtyard acts as gateway to the development establishing a sense of arrival and setting the tone for the overall development. The clubhouse is the social focus of the development and hence is also the most public of the open spaces.  Moving away from the clubhouse the open space network incorporates a number distinct spaces created through the orientation of the built form and through the use of planting which create a series of outdoor rooms. These rooms accommodate both active informal recreation in the form of for example children’s play areas and more passive pursuits such as the proposed seating area within the Sculpture Garden. Option 1A also incorporates Sky Gardens within each of the proposed development blocks designed to create an additional level of open space for the future residents and maximise the amount of visible greenery. Each of these spaces will be imbued with an individual character through the use of for example distinctive paving and street furniture, and planting combinations.

11.11.11                       The landscape of both options will essentially be a vehicle free environment being designed for the pedestrian with the car parking being located in a basement below the landscape area. The layout of the space and interconnected footpaths is designed to be legible with visual access between nodes and distinct entrance courtyards to the individual development blocks. 

11.11.12                       The buffer planting is provided along the edge of the residential development extending to the north in association with the marsh habitat created under the WNR. Both woodland edge planting and the marsh habitat form part of the landscape design framework in associated with the orientation of open lawn and local open space designed under the development. The design of the landscape buffer follows the guidelines suggested in the Study as discussed in Section 11.6.

Planting Design – Main Residential Area

11.11.13                       The landscape of the proposed development area for both options will utilise ornamental tree species, flowering shrubs and foliage plants, which provide both, colour highlights and seasonal variation. These soft landscape measures will ensure that the hard lines of the built form are visually softened in views from without the development site and in elevated views from the proposed residential blocks. Trees are proposed along the edge of the development site to provide a soft planted edge and provide some visual integration with the surrounding landscape. In order to ensure that these planting proposals are feasible it is proposed that an adequate planting medium be incorporated into the design of the soft landscape areas. For example a minimum 1.5m depth of planting medium will be incorporated into the design proposals, facilitating the planting of trees and palms in this area and 0.65m will be required for shrub areas. The use of semi-mature tree planting would be encouraged to provide a more instant effect.  Species would be selected to provide visual and aesthetic interest throughout the year through foliage and flower form and colour.

11.11.14                       The plant species for the landscaped areas will provide colour throughout the year with seasonal variation. This is achieved through the selection of species with an interesting form, colour and texture of their foliage and through the use of flowering species to provide an architectural highlight including Bauhinia blakeana, Delonix regia, Crataeva religiosa, Lagerstroemia indica, Ficus microcarpa, Cassia surratensis, Archontophoenix alexandrae, Jacaranda acutifolia and Bombax malabaricum.

Planting Design – Landscape Buffer Area

11.11.15                       The landscape buffer serves as a major landscape mitigation measures as discussed in Table 11-9. The proposals shown on Figure 11-13 A,B,C and D, the landscape buffer will be effectively formed by a combination of continuous marsh habitat approaching the reserved fish ponds, bamboo planting adjacent to an approximately 2m high security fence, and mass woodland and shrub planting on a 2m high berm adjacent to the open spaces within the development. The extent of landscape buffer has been maximised with limited site formation associated with the development to avoid further disturbance to the fish pond area. This buffer is designed in accordance with the guidelines suggested in the Final Report of Fish Pond Study in Deep Bay Area.

11.11.16                       The planting proposals will enhance ecological value through the creation of marsh and woodland within the buffer area between the WNR and development. The species selection for the proposed landscape woodland buffer would centre on the use of largely native species which have an ecological benefit in addition to the proposed mitigation of the predicted landscape and visual impacts. The species choice will reflect the range of existing species disturbed on the existing valley floor including Celtis tetrandra subsp. Sinensis, Ficus hispida, Ficus microcarpa, Litsea glutinosa, Macaranga tanarius and Mallotus paniculatus.

11.11.17                       Apart from the woodland buffer planting, some tree clusters will be planted in a number of limited locations upon the bunds within the WNR to broaden the range of habitat for different bird species. The primary objective of the tree planting within the WNR will be ecological in the creation of a favourable habitat for birds rather than for amenity purposes. Following this approach trees will be planted in small clusters in positions designed not to intrude upon the bird flight lines, create enclosure or shade the marshland and fishponds. Some fruit-bearing trees, such as Ficus hispida, Ficus microcarpa and Melia azedarach, are recommended from an ecological perspective to enhance foraging opportunities for some bird species.  Whilst wide canopied tree species such as Ficus microcarpa in combination with bamboo species such as Bambusa eutuldoides are recommended to be planted at the edge of the alternative egretry I in order to provide a favourable habitat for the egrets and screen the area from human activity.

Feature Paving

11.11.18                       The paving will be an important element of the open space both in aesthetic terms and in terms of producing a hard wearing landscape. As has been described above the design of the proposed paving would highlight entrance areas and major pedestrian routes through the site providing a hierarchy for pedestrian movement. It would be constructed of quality materials in feature patterns creating a distinct identity to each of the proposed spaces identified on the LMP. Colour changes within the patterns would be used to establish themes across the development. Where possible, the surfaces of internal EVAs will be continuous with the patterns in order to reduce their intrusion and their delineation should be through the use of trees, bollards and kerbs rather than by use of a vehicular surface such as concrete.

Lighting

11.11.19                       The lighting design concept for the landscaped areas should be designed to contribute to the quality of the development within internal nocturnal views with the highlighting of focal points and key landscape elements. In general the residential development landscape will not require 24 hour lighting except for the lighting of access roads and emergency access.  The intensity, luminance and lighting level generated from residential properties is predicted to be relatively low in the views available from outside the development. Glare control measures should be considered for the aesthetic design of architectural and road lighting within the development to minimise the visual impact caused by light spillage and glare in views for identified VSRs. Light fittings and post should be of an attractive design suitable to the existing rural setting.

Street Furniture

11.11.20                       The landscape design would include the provision of street furniture including seating, which in addition to its functional attributes would also contribute to the perceived quality of the landscape.

Children’s Play Area

11.11.21                       Facilities such as shaded seating areas would be provided in the playground. Play equipment should conform to approved safety standards and include safety surfaces.  Children’s play areas would be provided for easy access and have shaded seating areas for adult supervision.

 

11.12      Programme for Landscape Works

11.12.1   The landscape works will closely follow the completion of the construction of the proposed development platform and the proposed built structures as is shown in Table 1110 below. The design year is for the purposes of this study taken as approximately 10 – 15 years after the scheme opening when the proposed soft landscape mitigation is mature.

Table 1110     Provisional Programme for Landscape Works

Construction Activities

Approximate Time Scale

Completion of the General Construction Works

Implementation of Landscape Works

Design Year

Improvements works to the Southern Development Access

3rd Quarter 2016

3rd Quarter 2016 to the 3rd Quarter 2017

2025

Construction Works of the Development Area

3rd Quarter 2016

3rd Quarter 2016 to the 3rd Quarter 2017

2025

Establishment of the Wetland Nature Reserve

1st Quarter 2013

1st Quarter 2012 to the 1st Quarter 2013

2021

 

11.12.2   For the purposes of this report the above programme has been simplified to give an indication of the proposed design year for the soft landscape mitigation measures. At this stage the programme is preliminary and subject to finalisation during the detail design stages of the project. The landscape works will be implemented at the earliest possible time in the planting season immediately following the sectional completion of the construction works. The implementation schedule of landscape works common to both options 1A and 1B are presented in Table 10-11 and in the EM&A Manual.


Table 1111     Landscape and Visual Mitigation Measures Implementation Schedules

EIA Ref.

Mit. Code

Recommended Mitigation Measures

Location

Funding

 

Implementation/ Maintenance Agent

Relevant Standard or Requirement

Implementation Stages

Timing of Implementation

Objectives of the Recommended Measure and Main Concern to address

 

D

 

C

 

O

Construction Phase Landscape and Visual Mitigation Measures

11.11

Table 11-8

CP1

Preservation of Existing Vegetation

 

 

 

 

 

 

 

 

 

 

CP1.1

To retain trees that have high amenity or ecology value and contribute most to the landscape and visual amenity of the site and its immediate environs.

Site

Project Proponent

Project Landscape Architect / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

ü

 

 

Throughout  design phase

To minimise the disturbance to the existing landscape resources.

 

 

CP1.2

Creation of precautionary area around trees to be retained equal to half of the trees canopy diameter. Precautionary area to be fenced.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Before

construction phase

commence

To ensure the success of the tree preservation proposals.

 

CP1.3

Prohibition of the storage of materials including fuel, the movement of construction vehicles, and the refuelling and washing of equipment including concrete mixers within the precautionary area.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Throughout construction phase

To ensure the success of the tree preservation proposals.

 

CP1.4

Phased segmental root pruning for trees to be retained and transplanted over a suitable period (determined by species and size) prior to lifting or site formation works which affect the existing rootball of trees identified for retention. The extent of the pruning will be based on the size and the species of the tree in each case.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Throughout construction phase

To ensure the success of the tree preservation proposals.

 

CP1.5

Pruning of the branches of existing trees identified for transplantation and retention to be based on the principle of crown thinning maintaining their form and amenity value.

 

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Throughout construction phase

To ensure the success of the tree preservation proposals.

 

CP1.6

The watering of existing vegetation particularly during periods of excavation when the water table beneath the existing vegetation is lowered.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Throughout construction phase

To ensure the success of the tree preservation proposals.

 

CP1.7

The rectification and repair of damaged vegetation following the construction phase to it’s original condition prior to the commencement of the works or replacement using specimens of the same species, size and form where appropriate to the design intention of the area affected

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Throughout construction phase

To ensure the success of the tree preservation proposals.

 

CP1.8

All works affecting the trees identified for retention and transplantation will be carefully monitored.  This includes the key stages in the preparation of the trees, the implementation of protection measures and health monitoring through out the construction period

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

Throughout construction phase

To ensure the success of the tree preservation proposals.

 

CP1.9

Detailed landscape and tree preservation proposals will be submitted to the relevant government departments for approval under the lease conditions and in accordance with ETWB TCW No. 2/2004 and WBTC No. 14/2002.

Site

Project Proponent

Project Landscape Architect / NA

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

ü

 

 

Throughout  design phase

To ensure the tree preservation and planting proposals are integrated with the existing landscape context and that the landscape resources are preserved where appropriate.

 

 

CP2.0

The tree preservation works should be implemented by approved Landscape Contractors and inspected and approved on site by a qualified Landscape Architect. A tree protection specification would be included within the contract documents.

Site

Project Proponent

Project Proponent / NA

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

ü

ü

 

Throughout design and construction phases

To ensure the tree preservation and planting proposals are integrated with the existing landscape context and that the landscape resources are preserved where appropriate.

 

11.11

Table 11-8

CP2

Preservation of Existing Topsoil

 

 

 

 

 

 

 

 

 

 

CP2.1

Topsoil disturbed during the construction phase should be tested using a standard soil testing methodology and where it is found to be worthy of retention stored for re-use..

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18

 

ü

 

Throughout construction phase

To provide a viable growing medium suited to the existing conditions and reduce the need for the importation of top soil.

 

CP2.2

The soil will be stockpiled to a maximum height of 2m and will be either temporarily vegetated with hydroseeded grass during construction or covered with a waterproof covering to prevent erosion.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18

 

ü

 

Throughout construction phase

To provide a viable growing medium suited to the existing conditions and reduce the need for the importation of top soil.

 

CP2.3

The stockpile should be turned over on a regular basis to avoid acidification and the degradation of the organic material, and reused after completion. Alternatively, if this is not practicable, it should be considered for use elsewhere, including other projects.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18

 

ü

 

Throughout construction phase

To provide a viable growing medium suited to the existing conditions and reduce the need for the importation of top soil.

11.11

Table 11-8

CP3

Development Site and Temporary Works Areas

 

 

 

 

 

 

 

 

 

 

CP3.1

Where appropriate to the final design the landscape of these works areas should be restored following the completion of the construction phase.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18

 

ü

 

Through out construction phase

To minimise the disturbance to existing landscape resources and change of visual amenity.

 

CP3.2

Construction site controls should be enforced including the storage of materials, the location and appearance of site accommodation and the careful design of site lighting to prevent light spillage.

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18

 

ü

 

Through out construction phase

To minimise the disturbance to existing landscape resources and change of visual amenity.

 

CP3.3

Screen the works area during the construction phase through the use of decorative hoarding along the site boundary facing adjacent VSRs

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18

 

ü

 

Through out construction phase

To minimise the disturbance to existing landscape resources and change of visual amenity.

11.11

Table 11-8

CP4

Mitigation Planting

 

 

 

 

 

 

 

 

 

 

CP4.1

Replanting of disturbed vegetation should be undertaken at the earliest possible stage of the construction phase

Site

Project Proponent

Contractor / Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

ü

 

After the site formation and on completion of planting area.

To minimise the disturbance to existing landscape resources and minimize the impacts on the visual amenity of the area.

 

CP4.2

Use of native plant species predominantly in the planting design for the buffer areas.

Site

Project Proponent

Project Landscape Architect/ NA

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

ü

ü

 

After the site formation and on completion of planting area.

To enhance the local landscape and ecological value.

 

CP4.3

The tree planting works should be implemented by approved Landscape Contractors and inspected and approved on site by a qualified Landscape Architect. A tree planting specification would be included within the contract documents.

Site

Project Proponent

Project Proponent / NA

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

ü

ü

 

Throughout design and construction phases

To ensure the tree preservation and planting proposals are integrated with the existing landscape context and that valuable landscape resources are preserved where appropriate to the final design.

 

 

CP4.4

All imported plants should be quarantined in local nursery for minimum 1 month.

Local Green Nursery

 

Project Proponent

Contractor

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

 

 

ü

 

Throughout construction phases

 

To check there are no symptoms of infection by pests or diseases prior to planting on site.

 

11.11

Table 11-8

CP5

Transplantation of Existing Trees

 

 

 

 

 

 

 

 

 

 

CP5.1

The tree transplanting works should be implemented by approved Landscape Contractors and inspected and approved on site by a qualified Landscape Architect. A tree protection / transplanting specification would be included within the contract documents.

 

 

 

Site

Project Proponent

Project Proponent / NA

TM-EIA

Annex 18, ETWB TCW No. 2/2004 & WBTC No. 14/2002

ü

ü

 

Throughout design and construction phases

To ensure the tree preservation and planting proposals are integrated with the existing landscape context and that valuable landscape resources are preserved where appropriate to the final design.

 

Operational Phase Landscape and Visual Mitigation Measures

11.11

Table 11-9

OP1

Design of Built Development

 

 

 

 

 

 

 

 

 

 

OP1.1

Adopt a non-linear building orientation and a stepped building height principle.

Site

Project Proponent

Project Architects / NA

TM-EIA

Annex 18 and BD

ü

 

 

Throughout design phase

To ensure the proposals are integrated with the existing landscape and visual context, and avoid walling effect.

 

 

OP1.2

Use of a layout and slightly higher building blocks to allow the incorporation of significant view corridors.

Site

Project Proponent

Project Architects / NA

TM-EIA

Annex 18 and BD

ü

 

 

Throughout design phase

Create visual access through the development to the green backdrop formed by the wooded hillsides to the south. These view corridors also allow the development to avoid the walling effect evident in the existing developments to the south and west particularly when viewed from locations such as the development in the northern part of Tin Shui Wai. The proposed view corridors are also important from an ecological perspective.

 

OP1.3

Use of colour blocking utilising range of visually recessive earth colours and tones on the building facades of the different blocks. Non-reflective finishes are recommended on the outward facing building facades. Utilisation of planting on building façade and balcony to soften the architectural form of the building.

Site

Project Proponent

Project Architects for design / contractor for implementation / Property Management Agent for maintenence

TM-EIA

Annex 18 and BD

ü

 

 

Throughout design phase

Responsive building façade treatment to reduce the apparent visual mass of the development and reduce the glare effect from the reflection of sunlight.

 

OP1.4

Utilise underground car parking and utilities so as to maximise the area of landscaping.

Site

Project Proponent

Project Architects / Property Management Agent

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

To maximise the area available for landscaping and minimise potential impacts of extensive hard surfaced areas in elevated views both within and without the development site.

 

OP1.5

Use of responsive aesthetic design of architectural and road lighting with glare containment design measures.

 

Site

Project Proponent

Project Architects / NA

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

To reduce the night-time glare effect to the surrounding environs.

 

OP1.6

Formulate lighting operation management programme to minimise potential light spillage and glare impacts. 

 

Site

Project Proponent

Property Management Agent/ Property Management Agent

TM-EIA

Annex 18

 

 

ü

Throughout operation phase

To reduce the night-time glare effect to the surrounding environs.

11.11

Table 11-9

OP2

Landscape Buffer Planting

 

 

 

 

 

 

 

 

 

 

OP2.1

Create a landscape buffer area  extending around the periphery of the development to the proposed marsh habitat in WNR providing screening of the development at low levels and creating a transitional structure, not less than 50m wide, between the low-lying fishponds of the WNR and the upright forms of the proposed built development.

Site

Project Proponent

Contractor / Property Management Agent for the area within the 4ha development footprint and a contractor for the area within the WNR

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

This planting in addition to the proposed bamboo planting proposed as part of the ecological mitigation measures will also serve to visually integrate the proposals within the existing landscape framework.

 

OP2.2

Utilise native tree species in the planting mix for the landscape buffer area.

 

 

Site

Project Proponent

Contractor / Property Management Agent for the area within the 4ha development footprint and a contractor for the area within the WNR

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

Provide a linkage with the existing wooded areas creating a more coherent landscape framework whilst also improving the ecological connectivity between existing and proposed woodland habitats.

 

OP2.3

Formulate a woodland management programme for implementation during the operational phase.

Site

Project Proponent

Project Landscape Architect / Property Management Agent for the area within the 4ha development footprint and a contractor for the area within the WNR

TM-EIA

Annex 18, HKPSG & BD

ü

 

 

Throughout design phase

Conserve and enhance the ecological interest.

11.11

Table 11-9

OP3

Landscape Strategy for the Design of Amenity Space

 

 

 

 

 

 

 

 

 

 

OP3.1

The concept should provide a synthesis between a contemporary design philosophy and sustainable development principles. The spatial hierarchy involves movement from the public areas to more intimate spaces. Each of these spaces will be imbued with an individual character through the use of for example distinctive paving and street furniture, and plant combinations.  The layout of the space and interconnected footpaths is designed to be legible with visual access between nodes and distinct entrance courtyards to the individual development blocks.

Site

Project Proponent

Project Landscape Architect / Property Management Agent

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

Serve to visually integrate the proposals into the existing landscape framework and provide visual amenity for the enjoyment of the future residents.

 

OP3.2

The buffer planting is provided along the edge of the residential development extending to the north in association with the marsh habitat created under the WNR.

 

Site

Project Proponent

Project Landscape Architect / Property Management Agent for the area within the 4ha development footprint and a contractor for the area within the WNR

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

Landscape buffer designed to create a transitional zone between the general landscape of the development and the ecological important landscape beyond. This buffer will also screen low level views of the proposed development.

 

11.11

Table 11-9

OP4

Compensatory Planting Proposals

 

 

 

 

 

 

 

 

 

 

OP4.1

Utilise ornamental species within the residential development area whilst species native to Hong Kong will be utilized within the buffer planting areas.

Site

Project Proponent

Project Landscape Architect /  Property Management Agent for the area within the 4ha development footprint and a contractor for the area within the WNR

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

The planting proposal seeks to compensate for the predicted tree loss resulting from the construction of the development, visually integrate the proposals within its existing landscape framework and provide an improved visual amenity for future residents.

 

OP4.2

A qualified or registered landscape architect will be involved in the design, construction supervision and monitoring, and maintenance period to oversee the implementation of the recommended landscape and visual mitigation measures including the tree preservation and landscape works on site.

 

Site

Project Proponent

Project Proponent / NA

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

The planting proposal seeks to compensate for the predicted tree loss resulting from the construction of the development, visually integrate the proposals within its existing landscape framework and provide an improved visual amenity for future residents.

11.11

Table 11-9

OP5

Southern Development Access

 

 

 

 

 

 

 

 

 

 

OP5.1

Adopt a responsive streetscape design with new street tree planting.

Site

Project Proponent

Project Landscape Architect / LCSD and HyD for public portion of the road and Property Management Agent for private areas.

TM-EIA

Annex 18, HKPSG and BD

ü

 

 

Throughout design phase

The design seeks to visually integrate the road proposals within the landscape of the existing village setting of Shing Uk Tsuen and Ng Uk Tsuen.

 

Legend:    D – Design, C – Construction, O - Operation

 

Note:       BD– Building Ordinance

ETWB TCW – Environmental and Transport Works Bureau Technical Circular

HKPSG – Hong Kong Planning Standards and Guidelines

TM-EIA – Technical Memorandum on Environmental Impact Assessment Process

TPO – Town Planning Ordinance

WBTC - Works Bureau Technical Circulars

 


11.13      Operational (Residual) Landscape and Visual Impacts

11.13.1   Overall, in terms of residual landscape and visual impacts for both Options 1A and 1B the main effects will primarily result from the interruption in the relationship between the fishponds and the uplands which surround them. However the proposed development in both options will occupy a small part of the overall fishpond area and cause a low-level of disturbance in terms of the visual amenity available to VSRs. The landscape character of the fishponds to the east of Tin Shui Wai will be largely unchanged by the development proposals. The mitigation measures have been developed to alleviate, where possible, the identified landscape and visual impacts, and to enhance the future landscape character of the Study Area.

11.13.2   A series of computer generated images or photomontages have been prepared for the proposed schemes for Options 1A and 1B and are presented as Figure 1114 A to P and 11-15A to P. The location of the vantage points used for these images has been identified on Figure 11-6 and 11-10A and 11-10B. The photomontages of the proposed scheme for both options show the existing conditions, after the completion of the construction phase when the primary mitigation measures have been implemented, and Year 1 and Year 10 of the Operational Phase with the implementation of the secondary mitigation measures. The final image Operation Phase is designed to demonstrate the predicted residual impacts, which would exist in the design year during the operational phase usually taken as between 10 and 15 years after the completion of the construction phase.

11.13.3   During the preparation of the photomontages the baseline photographs of the existing situation were taken with a 50mm lens (representing the actual situation as closely as possible) as a series of photographs. These photographs were stitched together to form a panoramic view utilising the central portion (approximately 50%) of each photograph (this is the area with the least distortion). These photographs were used to demonstrate the existing view.

Vantage Point A (View North from the Lookout Point at Tsim Bei Tsui (VSR 2))

11.13.4   The photomontage for Option 1A presented as Figure 11-14A and B shows the proposed scheme from an elevated viewing position above the estuarine plain to the north at a distance of 2300m. The image shows the comparatively small scale of the proposed development in relation to the existing panoramic view whilst also demonstrating the impact of visually detracting elements such as the existing Yuen Long Sewage Treatment Plant. The proposed development will also be seen in the context of the visually more massive high-rise development associated with Tin Shui Wai and the framed views of the low-rise industrial estate and high and medium-rise development on the northern periphery of Yuen Long.  Although Kai Shan Range will be partially screened by the proposed residential development, the Kai Shan Range is set within a developed context with the Yuen Long Sewage Treatment Plant, and Yuen Long and Tin Shui Wai new town. The use of a responsive building orientation, the creation of voids within each block containing sky gardens and stepped building design suggested as part of the landscape mitigation measures will maximise the visual access to the range. This combined with the full establishment of the WNR and buffer planting will result in relatively small visual changes for these VSRs.  Furthermore there are relatively few VSRs at this location, many are transient in nature and alternate views are available way from the development area.  Hence, a moderate adverse residual visual impact is predicted from this vantage point.

11.13.5   The photomontage for Option 1B presented as Figure 11-15A and B is similar to the view for Option 1A sharing many of the same characteristics. In this view the proposed height difference of three storeys is only apparent in the flatness of the combined roofline of the residential blocks and in the slightly greater visibility of the bottom of the hill to the west of the development site and of the high and medium-rise development of Yuen Long to the south of the development site. This is due to the elevated viewing position and the distance to the proposed development. In addition the view corridors which punctuate the development façade for Option 1B appear to be narrower than those within Option 1B. A moderate adverse residual visual impact is predicted from this vantage point.

Vantage Point B (View from the Existing Fishponds to the North of the Development Site (Vantage Point B))

11.13.6   The photomontage presented as Figures 11-14C and D shows the proposed Option 1A scheme from a viewing position from the estuarine plain at a distance of approximately 900m. Although not an identified VSR this view demonstrates the developments fit into its landscape context.  The view also demonstrates the affectivity of the proposed landscape mitigation, including responsive building orientation, sky gardens and stepped building height principles, combined with retained landscape resources. These mitigation measures maximise the visual access to Kai Kung Leng with minimised disturbance to the fishponds resulting from the site formation. It shows the relationship between the built form and the green backdrop to the south of the development site with the maintenance of the existing ridgeline; the incorporation of the stepped building height principle to create a more organic building profile responding to the form of the existing hillside; the use of view corridors to create a permeable development and allow visual access to the green backdrop; and the use of colour blocking to break up the visual mass of the development facades. The development therefore fits into Yuen Long urban and industrial; and Tin Shui Wai high-rise development landscape context on its east and west.

11.13.7   The photomontage for Option 1B (Figures 11-15C and D) is similar to the view for Option 1A sharing many of the same characteristics however in this view the slightly reduced building height allows a slightly greater degree of visibility to the hillside beyond. Again this is balanced to an extent by the reduced visual access to the hill slope due to the more narrow view corridors incorporated into the design for Option 1B compared to Option 1A.        

Vantage Point C (View Southeast from the Hong Kong Wetland Park Entry Forecourt (VSR 13))

11.13.8   The photomontage presented as Figures 11-14E and F shows the proposed Option 1A scheme from a public accessible viewing position at the entry forecourt to the Hong Kong Wetland Park to the north west of the proposed development at a distance of approximately 1300m. The image shows the uppermost portion of the proposed development in the central portion of the picture, and demonstrates the comparatively small scale of the proposed high-rise blocks within the overall view and the effect of viewing distance. It also demonstrates the ability of comparatively small objects, such as the boundary fence and vegetation in the foreground, in screening long distance views of the proposed development and therefore in mitigating the potential impacts. Although the proposed development will partially screen the Kai Shan Range it is not a major component within this visual context compared to Tin Shui Wai high-rise development in the foreground. Therefore a moderate adverse residual visual impact is predicted from this vantage point.

11.13.9    The photomontage for Option 1B (Figures 11-15E and F) is similar to the view for Option 1A although the proposed development is slightly less visible due to the proposed reduced building height of 15 storeys. Despite this reduced visibility the Option 1B proposals would also result in a moderate adverse residual visual impact from this vantage point.    

Vantage Point D (View East from the Vianni Cove at Tin Shui Wan North (VSR 14))

11.13.10                        The photomontage on Figures 11-14G and H shows the proposed Option 1A scheme from an elevated viewing position some 1200m to the west of the development site. The image demonstrates that the scheme proposals form a small component of the overall view available to residents in relation to the existing panoramic view of coastal plain, stretching to developments such as Fairview Park in the middle ground and the uplands forming the Lam Tsuen Country Park and Kai Kung Leng in the background. The proposed development will be partially seen in the context of the high and medium-rise of Yuen Long and the low -rise associated with Yuen Long Industrial Estate. The view also demonstrates the visibility of the green backdrop above the proposed blocks, the permeable development façade formed through the disposition and orientation of the proposed blocks, and the proposed sky gardens, and the preservation of views to Kai Shan to the west of the development site. This view also demonstrates that from a visual perspective the proposed development occupies a relatively small part of the fish pond area. Although the visual access to Kai Shan looking from these views will be partially screened by the proposed development, the implementation of responsive building orientation and stepped building design will maximise visual access to Kai Shan and serves to create a more subtle transition between the edge of the proposed development and its landscape context. This change of visual context will not be permanent as their view looking east will be interrupted although not screened after the completion of CDA development at Area 115 in the foreground. The implementation of the CDA proposals will change the character of views which overlook it to a more urban character and the presence of this development in the foreground of views will change the perception of the nature of the future views for residents of lower floors of this development. The impact of the CDA proposals will be less pronounced for residents of the upper floors. Given the above the proposals would lead to a moderate adverse residual visual impact and negligible impact after the completion of Area 115 development from this vantage point.

11.13.11                        The photomontage for Option 1B (Figures 11-15G and H) is similar to the view for Option 1A although the proposed development is characterised by its flat roofline which although allowing greater visual access to the wooded hill side beyond it may be argued that the flat roofline is visually more incongruous relative to the more organic forms of the surrounding landscape and therefore more visible. The proposed development would also give rise to a moderate adverse residual visual impact. Again the completion of the Area 115 development would change the nature of the existing views with a more urban character from this vantage point. The reason for this level of impact is that the construction of the CDA proposals will change the character of the views to a more urban feeling for VSRs on the lower floors although this effect will be less pronounced for residents of the upper floors.     

Vantage Point E (View Northeast from the Kenswood Court at Tin Shui Wan West (VSR 11))

11.13.12  The photomontage presented as Figures 11-14 I and J shows the proposed Option 1A scheme from an elevated viewing position to the northwest of the development site at a distance of some 1000m. Again the view demonstrates that the proposals would form a small component of future views in relation to the existing panoramic view of Kai Keng Leng within the Lam Tsuen Country Park in the background and Kai Shan Range in the middle ground, and the short eastern development façade. The proposed development will be seen in the context of the development associated with visually Yuen Long Industrial Estate. Although the proposals form a small component of the view there will be some partial screening of the knoll adjacent to Ng Uk Tsuen. However potential adverse impacts will be alleviated through the use of a responsive building orientation and stepped building design, the creation of a view corridor and development profile responding to the existing landform. Therefore the view may be considered to be visually integrated with its immediate context in views from this location. The development will lead to a moderate adverse residual visual impact from this vantage point.

11.13.13                       Again the photomontage for Option 1B (Figures 11-15I and J) shares many of the characteristics of the view for Option 1A. In both options the viewing angle directs the view towards the narrow western development façade reducing the visual prominence of the proposed development. However this same viewing angle also negates the effectiveness of the proposed view corridors in breaking up the visual mass of the development. In both photomontages the disruption to views of the wooded hill sides of the Kai Shan range has been minimised. The development will lead to a moderate adverse residual visual impact from this vantage point.   

Vantage Point F (View North from Fuk Shun Street Road Junction near the Site Entrance (VSR 7))

11.13.14 The photomontage presented as Figures 11-14 K and L shows the proposed scheme from a location adjacent to the site entrance at the pedestrian level 130m to the south of the development site.  The image demonstrates the effect of the existing landscape features including the village houses and open storage uses at Shing Uk Tsuen and existing roadside trees in partially screening views of the proposed development. From this location the edge of the village and its associated tree planting forms the limit to many of the existing views from within the settlement. Further it is only village houses on the northern edge of the settlement and those near open spaces which will have glimpsed views of the proposed development and these views will be limited to the upper floors of the proposed buildings. Beyond these areas a combination of the proximity of nearby houses and their orientation serve to screen views north. The use of measures such as the responsive building orientation, stepped building design and integration of vertical greening on the building facades serve to further mitigate any potential impacts.  The potential impacts will be further alleviated through the full establishment of the proposed buffer planting at the edge of the development and the visual context will be enhanced through the creation of WNR. Given the above the proposals would lead to a significant to moderate adverse residual visual impact from this vantage point.

11.13.15                       The photomontage for Option 1B (Figures 11-15K and L) demonstrates the affectivity of the proposed lower building height in reducing the visual prominence of the proposed development in views from the north of the village. Although this is balanced to extent by the increased width of the view corridors in Option 1A which results in a more visually permeable development. Given the above the proposals would lead to a significant to moderate adverse residual visual impact from this vantage point.  

Vantage Point G (View North from Vienna Villa at Fuk Shun Street (VSR 7)

11.13.16                        The photomontage presented as Figures 11-14 M and N shows the proposed scheme from a viewing position some 250m to the south of the development site from the car parking are adjacent to the Vienna Villa development. The image demonstrates the combined effect of the proposed view corridors and stepped building height concept and the existing features in mitigating the predicted impact of the development. As discussed in the description for Vantage Point F above the development will be viewed within the context of the existing village house on the edge of the settlement and its potential impact will be alleviated to an extent through the introduction of mitigation measures. VSRs at this location will have glimpsed views of the elevated floors of the proposed development. In low level views from this location the proposed development will be no more prominent than the adjacent village houses. Given this combination of factors the proposals would lead to a slight to moderate adverse residual visual impact from this vantage point.

11.13.17                        The photomontage for Option 1B (Figures 11-15M and N) demonstrates the affectivity of the proposed lower building height in reducing the visual prominence of the proposed development in views from the central parts of the village. The reduced height of the blocks for Option 1B and therefore the increased screening ability of the adjacent village houses and the intervening vegetation serve to reduce the potential impacts arising from the smaller view corridors.   Although this is balanced to extent by the increased width of the view corridors in Option 1A which results in a more visually permeable development. Given the above the proposals would lead to a slight adverse residual visual impact from this vantage point.  

Vantage Point H (View North from Northern Periphery of Jade Court at Ng Uk Tsuen

(VSR 6)

11.13.18                        This photomontage (Figures 11-14 O and P) shows the proposed scheme from a location at the northern periphery of the Jade Court adjacent to the Tin Hau Temple in Ng Uk Tsuen some 285m south of the proposed development site. It represents the view available to residents living in the northern portion of the village whom will potentially have glimpsed views of the upper floors of the proposed development. The areas from which the view is available are constrained to the north by an existing wetland area and village houses and Tin Hau Temple in the foreground. Therefore VSRs living at Jade Court and worshippers at the Tin Hau Temple will experience a small to intermediate change in their views. This image demonstrates that only elevated floors of the proposed development will be visible from this vantage point as the lower level view has been screened by the existing vegetation and village houses. The impacts will be further mitigated through the proposed orientation and disposition of the blocks and the creation of view corridors through the development and so a moderate to slight adverse visual impact is predicted.

11.13.19                        The photomontage for Option 1B (Figures 11-15O and P) again demonstrates the affectivity of the proposed lower building height in reducing the visual prominence of the proposed development in views from the north of the village. Given the above the proposals would lead to a slight adverse residual visual impact from this vantage point.  

 

11.14            Conclusion

Landscape Planning and Development Control Review – Options 1A and 1B

11.14.1   A review of the future proposals for the Study Area as represented in the Outline Zoning Plans reveals that the proposed schemes for both Options 1A and 1B will fit into the future landscape of the Study Area. Further the proposed marsh habitat planned for the area to the north of the development site will form a continuation of the existing Hong Kong Wetland Park contributing to a more coherent landscape framework. The proposals would therefore largely be compatible with the planning intention for the area and the planned landuses in the adjoining areas.  However the proposed development sited within the area zoned “Other Specific Uses (Comprehensive Development and Wetland Enhancement Area)”, “OU(CDWEA)” in the OZP No. S/YL-LFS/7 of Lau Fau Shan and Tsim Bei Tsui will require the submission of a Section 16 planning application.

Existing Trees – Options 1A and 1B

11.14.2   In terms of the loss of existing vegetation 238 (36%) of the existing trees can be retained in-situ and it is recommended that approximately 399 (60%) are felled out of a total of approximately 665. It is also recommended that approximately 28 (4%) of the existing trees are transplanted although this is subject to review during the detailed tree survey. The Master Landscape Plan demonstrates that some 300 new trees can potentially be established within the main development area in addition to the 3750 square metres of mass woodland planting established within the project boundary. This equates to some 1050 new trees with a compensatory planting ratio of approximately 2.6:1 (new planting: trees recommended for felling). With the retention of existing trees, the successful establishment of newly planted trees and the transplantation of some of the existing trees, the project area will contain approximately 1316 trees which compares favourably to the felling proposals particularly given that the relatively low value of the existing trees.

Construction Phase Landscape Impacts

11.14.3   The main residual impacts predicted for the construction phase of the both the Option 1A and 1B schemes with the incorporation of mitigation measures are as follows:

Landscape Resources – Options 1A and 1B

·        The main impacts on the landscape resources of the area are due to the loss of approximately 4 hectares of fishponds (LR 8) resulting from the construction of the proposed development. These will be minimised as far as possible through the containment of disturbance, enhancement of the remaining wetland areas and proper site management during construction. The impacts will range from moderate adverse impact to slight adverse residual impact with the implementation of the recommended landscape mitigation measures.

·        The loss or modification of the existing landform (LR 1) due to the proposed creation of the WNR which will result from the removal of some fishpond bunds and modification of others resulting in a slight/moderate adverse impact in the absence of mitigation measures. This impact will be alleviated to a slight adverse residual impact through responsive siting of the proposed development, creation of WNR and the fishpond enhancement.

·        The loss or modification of the existing ditches (LR 10) due to the proposed creation of the WNR resulting in a slight adverse residual impact.

·        The loss of existing trees during the construction phase of the project would lead to a moderate adverse impact on LR 13 Existing Trees.

·        The impact on the other landscape resources within the Study Area will be largely negligible.

Landscape Character – Options 1A and 1B

·        The Kai Shan Range (NUA 1) will not be subject to direct impacts however there will be some indirect impacts due to the proximity of the development and its effect on the landscape setting of the hills sides however the impact is assessed as being moderate adverse.

·        The Ng Uk Tsuen Village Cluster (V1) will not be subject to direct impact however there will be some moderate adverse indirect impact due to the proximity of the development and modification of Fuk Shun Street. Although the potential impact on the character of the villages will be largely limited to the northern portion of the settlement. 

·        The agricultural fields in the Fung Kai Wai – Ng Tung Uk area (AGR 1) will not be subject to impact due to the screening effect of the existing vegetation to the east of the fields resulting in a negligible level of residual impact.

·        The existing fishponds (AGR2) will be subject to limited direct impacts due to the loss of an area during the creation of the development platform resulting in a moderate to significant adverse residual impact. 

·        The Hong Kong Wetland Park (OS1) is remoted from the proposed site and so the residual impacts will be negligible. 

·        The Yuen Long Industrial Estate (ICA1) has a low sensitivity to change being characterised by large industrial buildings and is physically remoted from the development site. The Kam Tin and Shan Pui River Estuaries, and the Tin Shui Wai Drainage Channel (EL 1) are also remote from the development area and so both areas would not be subject to impacts resulting in a negligible level of residual impact.

Visual Impacts – Option 1A

·        Views available for the residents of northern Tin Shui Wai (VSR 1) and visitors to the lookout point at Tsim Bei Tsui (VSR 2) would be subject to a relatively low level of visual impact due to a combination of the scale of the development, the expansive nature of the existing views and the viewing distances involved and so there would be a moderate adverse residual impact.

·        The residents on the edge of settlements such as Mong Tseng Wai (VSR 3), and Tai Sang Wai (VSR 5) would have low level, long distance views of the proposed development site, and so residual impacts would be slight adverse.. Whereas the impacts for residents of Fairview Park (VSR 4)  would be slight to moderate adverse due to the viewing angle. Views for all three VSRs would be partially interrupted by intervening vegetation and built structures.

·        Views for residents of settlements to the south of the development area including Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) would be formed by two groups the first the residents on the northern periphery of the villages (approximately 10 houses in each settlement) whom have an open view of the development site and those within the settlement where adjacent buildings and intervening vegetation serve to screen or partially screen views of the development proposals. In the first instance the impacts would be moderate to significant adverse due to the proximity of the proposed development however even for the residents on the edge of the village some views are partially screened by the existing vegetation and structures. For residents within the settlements, users of the public open spaces and vehicle travellers the views are screened or partially screened by the adjacent village houses and the existing vegetation. Partial views of the proposed development are largely limited to areas on the edge of large spaces such as the view forming the basis of photomontage vantage point G. The VSRs on the northern periphery of the village would be subject to a moderate to significant adverse impacts while those within the village (the majority) would be subject to a moderate to slight adverse impact.    

·        Walkers using the trail on Kai Shan (VSR 8) would be subject to a moderate impact due to the proximity of the proposed development site although alternative views across the estuarine plain are available to VSRs in this location.

·        The residents of the Long Ping Estate (VSR 9) will have framed views of the upper storeys of the proposed development beyond the Kai Shan ridge line however potential impacts will be alleviated from moderate to slight adverse impact.

·        Views for the residents of the Tin Tsz Estate (VSR 10) will be largely screened by the landform of Kai Shan although there will be glimpsed views of the upper storeys of the proposed development resulting in a moderate to slight adverse impact for those VSRs with a view of the proposals. 

·        The residents on the eastern side of the Kenswood Court (VSR 11) will have open views of the development proposals although the visible part of the development will be along the smallest building façade. Therefore the residual impacts will be limited to moderate adverse.

·        The residents on the eastern side of the Tin Yuet Estate at Tin Shui Wai West (VSR 12) will have long distance views of the development proposals although the visible part of the development will again be along the smallest building façade. Therefore the residual impact will be moderate adverse.

·        Visitors to the Hong Kong Wetland Park (VSR 13) will have glimpsed views of the upper storeys of the proposed development with low level views being screened by the existing vegetation within the park and the intervening pond bunds resulting in a moderate adverse residual impact.

·        The upper level residents on the eastern side of the Vianni Cove (VSR 14) and the Grandeur Terrace (VSR 15) at Tin Shui Wai will have an overview to the proposed scheme, however due to the expansive nature of the existing view and the viewing angle the predicted impacts will be moderate adverse. 

·        Future residents of the CDA (PVSR A1) on the north eastern periphery of Tin Shui Wai will have low-level largely screened views of the development proposals. These views will be long distance with the proposed development forming only a small part of the future view resulting in a moderate adverse level of impact.  

·        Night-time glare impacts generated by the construction activities are predicted to be slight to negligible in view available to the identified VSRs and these impacts will be temporary in nature and largely limited to the working day.

Visual Impacts – Option 1B

·        The potential visual impacts arising from the implementation of Option 1B would be broadly similar to Option 1A. The main differences would be apparent in views from the villages to the south of the proposed development site. Views for residents of settlements to the south of the development area including Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR 7) would be formed by two groups the first the residents on the northern periphery of the villages (approximately 10 houses in each settlement) whom have an open view of the development site and those within the settlement where adjacent buildings and intervening vegetation serve to screen or partially screen views of the development proposals. Based on these locations the impacts for residents on the periphery of the village would be significant to moderate adverse due to the proximity of the proposed development however even for the residents on the edge of the village some views are partially screened by the existing vegetation. For residents within the villages  (the majority) would be subject to a moderate to slight adverse impact. Whilst this is less significant than the predicted impact for Option 1A the upper floors of the proposed scheme will still be visible from some locations within the villages.

Operational Phase Landscape Impacts

11.14.4   The main residual impacts predicted for the operational phase with mitigation measures are as follows:

Landscape Resources – Options 1A and 1B

·        In general the impact on LRs within the Study Area will be largely negligible. Further many will generally benefit from by the creation of WNR and fishpond enhancement as these works would improve the quality of the resource including their ecological value. 

·        The impacts predicted for the landscape resources of the Study Area during the construction phase will largely persist into the operational phase of the project with the exception of the plantation woodland (LR 3) which will be enhanced through the implementation of the woodland landscape buffer around the development site (resulting in a moderate to significant beneficial impact). The existing wetland resource (LR 12) will also significantly benefit by the creation of the WNR providing extension extending this valuable resource within the local context.  In addition the proposed created marsh habitat and fish pond enhancement under the WNR proposals will lead to a qualitative enhancement of the directly affected LRs such as the Existing Landform (LR1), the Fishponds (LR8), the Watercourses-Ditches and Drainage Channel (LR10) and improve the local landscape diversity. Given these enhancements the LR 3 will benefit from the full establishment of the proposed mitigation measures including the WNR and woodland edge planting around the development resulting in a moderate beneficial impact.

·        With the proposed planting of significant number of new trees there would be a moderate beneficial impact on LR 13 Existing Trees.  

Landscape Character – Options 1A and 1B

11.14.5   The impacts predicted for the landscape character of the Study Area during the construction phase of the project for both Options 1A and 1B will largely persist into the operational phase of the project although the growth to maturity of the tree and shrub planting proposed as part of the marsh habitat and the landscape buffer planting on the periphery of the development will serve to encourage greater sense of landscape and visual integration with the development’s context. This planting will also serve to soften the transition between the verticality of the proposed built environment and the surrounding coastal plain. The planting proposals will also alleviate some of the indirect impacts on the Ng Uk Tsuen Village Cluster (V1) and the Kai Shan Range (NUA 1) and provide some benefit to the local character with a slight adverse impact with full establishment of the proposed mitigation measures. The impact on the landscape character of the village cluster will be restricted to the northern periphery of the settlement. Impacts on the character of the existing Fishponds (AGR 2) will also be partially alleviated through the implementation of the proposed mitigation measures resulting in a slight adverse impact. The landscaping associated with the proposed landscape buffer and the establishment of the WNR would also have a slight beneficial impact on the adjacent areas of the Hong Kong Wetland Park (OS1).   

Visual Impacts – Option 1A

11.14.6   Many of the views for the identified VSRs share a number of common characteristics which include their expansive nature, the viewing distance and in many cases an elevated viewing position resulting in slight to moderate to significant adverse impact at operational stage in the absence of mitigation measures. In this situation the proposed primary mitigation measures such as the location of the development platform and form of the built structure including the adoption of a stepped building height, sky gardens and view corridors take precedence over the proposed soft landscape mitigation measures although these measures serve an important role in further mitigating the predicted adverse impacts.  There are however some exceptions with visitors to the Hong Kong Wetland Park (VSR 13), walkers on Kai Shan footpath (VSR8), residents on the eastern periphery of Tin Shui Wai such as Tin Tsz Estate (VSR10), Tin Yuet Estate (VSR12) and Grandeur Terrace (VSR15) and Long Ping Estate at Yuen Long realising a level of mitigation due to the proposed landscape buffer planting, the predicted level of residual visual impact for these VSRs although due to the assessment methodology the impacts will be maintained at moderate adverse. It should also be noted that for many of these VSRs the proposals will form a small component of the wide panoramic views of the coastal plain which is available to them. Whilst with the completion of the construction phase of the project and the implementation of the proposed mitigation measures the predicted visual impact experienced by the residents of Kenswood Court (VSR11), Tin Yuet Estate (VSR12) and Vianni Cove (VSR14) at Tin Shui Wai will be moderate adverse.  

11.14.7   Given that the majority of the identified VSRs are located at distances of 1000m or more from the proposed development and the fact that in many views the development will be seen against the backdrop of the existing street lighting in the adjacent villages and Yuen Long the predicted night time glare impacts will not be significant. The predicted impacts for the other VSRs in the construction phase will persist into the operational phase. The adoption of responsive site planning and lighting design with glare control measures as described in the previous section would serve to mitigate much of the potential impacts. In addition the proposed use of a vegetative landscape buffer and the screening effect of the existing vegetation will mitigate much of the potential night time impacts for VSRs at low elevations such as the Hong Kong Wetland Park. Overall the night-time glare impact resulting from the proposed architectural and road lighting would have a predicted slight adverse to negligible impact for the large part of the existing and planned VSRs.

Visual Impacts – Option 1B

11.14.8   The shared characteristics of many of the existing views including their expansive nature, the viewing distance and relative elevation mean that for many VSRs, Options 1A and 1B would appear similar. It may be argued that despite the Option 1B adopting a 15 storey maximum height the flat roofline (contrasting with the organic forms of the adjacent landscape), the introduction of an additional block and the reduced view corridors ensure that the proposals have a similar level of visual prominence. Given this the predicted visual impacts particular for the VSRs to the north, east and west of the application site are similar to those predicted for Option 1A. The main differences would be apparent in views from within the villages of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR7). The reduced height of Option 1B would reduce the visibility of the proposals in views from within the village however in many instances these views are largely interrupted by existing features such as the adjacent village houses and the intervening vegetation. In views from the northern periphery of the village it is considered that the reduced height of Option 1B is balanced to an extent by the wider view corridors of Option 1A which allow greater albeit framed visual access to the fishpond area to the north.  

11.14.9   Overall the visual impacts range from moderate adverse to slight adverse for the majority of VSRs due to the viewing distances involved (typically 1200 to 3000m) and the direction of view, the broad expanse of the existing views extending east over the coastal plain, and the presence of existing high-rise development on the northern periphery of Yuen Long and the eastern edge of Tin Shui Wai. In addition the proposed architectural schemes for Options 1A and 1B have been designed to respond to the existing landscape and visual context including measures such as the height and disposition of the proposed blocks, the use of stepped height profile, the creation of view corridors and the proposed treatment of the building facades.

Acceptability of Impacts

11.14.10                       In accordance with Annex 10, Paragraph 1.1(c) of the EIAO TM, the landscape and visual impacts of the project under the proposed development at Fung Lok Wai for both Options 1A and 1B would be ‘acceptable with mitigation’ that is to say `there would be some adverse effects, but these can be eliminated, reduced or offset to an extent by specific measures’.


12.             Fisheries impact assessment

12.1          Introduction

12.1.1      This assessment has been prepared in accordance with the requirements of the EIAO and the criteria and guidelines defined in Annex 9 (“Criteria for Evaluating Fisheries Impact”) and Annex 17 (“Guidelines for Fisheries Impact Assessment”) of the Technical Memorandum on Environmental Impact Assessment Process respectively. Specifically it includes:

·        A detailed description of the baseline physical environment;

·        Description and quantification of the existing pond aquaculture practices and associated resources;

·        Identification of associated socio and economic issues relating to fish pond management;

·        Identification of potential direct and indirect impacts to aquaculture practices during the construction and operation of the development, including the Wetland Nature Reserve;

·        Identification of potential mitigation measures that could be utilised to reduce or overcome the potential impacts of the construction and operation of the development, including the Wetland Nature Reserve; and

·        Review of the need for monitoring during the construction of the development, including the Wetland Nature Reserve.

Scope and aims of this Fisheries Impact Assessment

12.1.2      In accordance with Section 3.5.7.1 of the Study Brief (EPD 2000) the extent of this assessment comprises:

·        Aquaculture resources present within the “area of the boundary of the proposed development (including the access road)”; and,

·        “Its adjacent area of potential impact” which, for the purposes of this assessment is taken to mean any aquaculture or mariculture resources that may be affected by the construction or operation of the proposed development.

12.1.3      Figure 12‑1 illustrates the site boundary and extent of the FIA Assessment Area. For the purposes of this assessment the following areas were defined:

·        Proposed Development Area – the area directly affected by residential construction.

·        Wetland Nature Reserve – the area of fishpond enhancement and marshland creation.

·        Assessment Area – comprising the Proposed Development Area, the proposed Wetland Nature Reserve, the proposed Access Road and any adjacent aquaculture, mariculture or marine fisheries resources that may be affected by the construction or operation of the proposed development.

12.1.4      The aims of this assessment are to provide sufficient and relevant information to assist the Environmental Protection Department (EPD) and the Agriculture, Fisheries and Conservation Department (AFCD) to:

·        Identify, assess and evaluate the fisheries resource of the Assessment Area;

·        Identify, assess and evaluate any adverse impacts that will arise during the construction and operation of the proposed development, and evaluate the acceptability of these impacts;

·        Identify, assess and evaluate cumulative impacts within the North West New Territories; and,

·        Identify, assess and evaluate the effectiveness of proposed mitigation measures that will be adopted to minimize or eliminate the predicted impacts that will arise during the construction and operation of the proposed development.

Specific Objectives of This Assessment

12.1.5      The EIA study brief for this proposal (EPD, 2000) identifies specific objectives and requirements for the Fisheries Impact Assessment. These are listed below and the sub-section within which each is addressed is indicated:

·        Describe the physical environmental background (Section 12.3);

·        Describe and quantify as far as possible existing aquaculture activities, with special attention on Fung Lok Wai and around Mai Po (Section 12.3);

·        Describe and quantify as far as possible existing fisheries/aquaculture resources (Section 12.4);

·        Identify parameters (eg Water Quality Parameters) and area that are important to aquaculture activities (Section 12.3 and 12.4);

·        Identify and quantify as far as possible any direct/indirect and on-site/off-site impacts to aquaculture, including permanent loss and temporary occupation of fishponds and those impacts on aquaculture activities due to sewer bursting and emergency discharge from sewage pump house (Section 12.5);

·        Evaluate impacts on aquaculture activities during construction and operation stages in areas around Fung Lok Wai and Mai Po and other affected areas (Section 12.5);

·        Evaluate cumulative impacts of loss of fishponds in the North West New Territories (Section 12.5);

·        Identify practical mitigation measures to avoid/minimise the potential impacts on the aquaculture activities (Section 12.6);

·        Identify and present an adequate package of measures to fully compensate all the losses due to the project with details on justification, description of scope and programme feasibility as well as staff and financial implications including those related to subsequent management and maintenance requirements of the proposals. Among other measures, the need to reinstate affected fishponds and other aquaculture sites (Section 12.6); and,

·        Determine the need and, if necessary, make appropriate recommendations for a monitoring and audit programme (Section 12.7).

 

12.2          Methods

12.2.1      A habitat map of the site was produced in connection with the Ecological Impact Assessment (Figure 13‑9, Section 13.5). In collating this map the boundaries of existing fishponds were identified within the Assessment Area defined for this FIA (see above).

12.2.2      Baseline information regarding fisheries resources and activities within this area were identified on the basis of:

·        Review of existing published and unpublished literature, including ecological information collected in connection with the preparation of the Ecological Impact Assessment;

·        Site inspections;

·        Consultations with AFCD aquaculture specialists and reference to published government reports; and,

·        Liaison with the Hong Kong New Territories Fish Culture Association and aqua-culturists.

 

12.3          Description of the Physical Environment

12.3.1      This sub-section provides details of the geographical and physical context of Fung Lok Wai including past and present land-uses, superficial geology, topography, hydrology and water quality.

Location and Regional Context

12.3.2      The Assessment Area is located to the south of Inner Deep Bay in the North West New Territories of the Special Administrative Region of Hong Kong.  Figure 12‑1 illustrates the location of the proposed development site and assessment area in the context of the Deep Bay environs. To the west the site is bounded by mangroves along the tidal creeks of the Tai River outfall, beyond which are grasslands, reed beds, a plantation and fishponds. Further to the west of Fung Lok Wai is Tin Shui Wai New Town. To the northwest there is an area of tidal lagoons (near Tsim Bei Tsui) created by the construction of a causeway for the road and border security fence.

12.3.3      The site is bounded to the north and east by wetland habitats. A continuous band of one or two fishponds bound the site to the immediate north, beyond which lies a belt of mangroves which give way to the tidal mudflats and increasingly marine conditions of Inner Deep Bay. Further to the northeast, beyond the Shan Pui River, there is a large area of fishponds and the Mai Po Nature Reserve, a complex of mangrove, gei wai, reed bed and fishponds. Fishponds also bound the site to the east, beyond which is a strip of landscaped land either side of the closed area boundary road, which demarcates the eastern extent of land reclamation. Further east is the Main Drainage Channel for Yuen Long, Kam Tin and Ngau Tam Mei drainage from the Shan Pui River. To the southeast lies Yuen Long Sewage Treatment Works to the south of which lies Yuen Long Industrial Estate.  The south of site is bounded by undeveloped low hills. These are predominantly covered in semi-natural scrub and woodland vegetation with some grassland and orchards. Much of the lower lying areas have been developed for residential housing or cultivated for wet and dry agricultural uses, depending on drainage conditions. Tin Shui Wai new town lies to the southwest and in the western part of the site there are large areas currently under construction relating to the ongoing development of Tin Shui Wai and the operation of Hong Kong Wetland Park.

Geology and soils

12.3.4      The superficial geology of the site consists of estuarine deposits of marine and fluvial origin, predominantly silts and clays.  No borehole information is available from Fung Lok Wai itself, but investigations elsewhere indicate that lenses of sands and gravels of alluvial origin may occur underneath the surface estuarine deposits (see Townland et al. 1992).

12.3.5      The soils of Fung Lok Wai are derived from mangrove soils and ultimately have their origin as marine sediment and riverine alluvium. Texturally the soils are dominated by silt and clay fractions, the relative proportions of which produce soils that vary from clay through silty clay to silty clay loam (USDA texture classes).  Sand content is generally low. Very small amounts of gravel are present. The soils have been considerably reworked during reclamation and through management for fish farming.

12.3.6      Soil samples taken in January 1996 were slightly acidic, with a mean pH of 6.8. The soils are poorly drained and frequently highly saline, rendering them of little agricultural value.

Topography, Hydrology and Watercourses

12.3.7      The site has an open, flat and low-lying aspect. The major variation in site level is due to the excavation of the fishponds and creation of bunds. The level on top of the fishpond bunds varies from approximately +3.1 m to +3.3 m PD, at the north and east of the site, to about +4.2 m PD at the south.

12.3.8      Water for the fishponds comes from direct rainfall.  During winter and when ponds are drawn down, water is pumped from one pond to another to conserve resources. After heavy summer rainfall, ponds may fill and drain into adjacent channels. Channels may also occasionally be used for transferring water, by pump, between fishponds.

12.3.9      No flow data are currently available for the drainage channels, however, a site inspection on 10th January 1998 revealed that all channels contained shallow water (c. 10 cm) and that there were low flows from those draining catchments the adjacent catchments to the south.

12.3.10   The mangrove-lined channel (Tai River outfall) at the north-western perimeter of the site is intertidal.  The perimeter bunds are approximately +3.8 mPD and higher than the predicted mean high water in the channel (+2.4 m PD). Therefore in normal circumstances the interior of the site remains free of tidal influence. Overtopping of the perimeter might occur in an extreme combined high tide and storm event. However, this is likely to be extremely rare given the past extreme sea levels at nearby Tsim Bei Tsui, which peaked at +3.85 mPD with a return period of 100 years for records between 1974 and 1990. The predicted tidal range for 2002 at Tsim Bei Tsui is 0-3 mPD with an average peak tide of +2.4 mPD.

Water Quality

12.3.11   No data are currently available on the quality of water in the existing watercourses. However, all the catchments are dominated by dense semi-natural scrub and woodland vegetation and there are no apparent point sources of pollutants such as pig farms etc. It is therefore expected that the water entering the site is likely to be of relatively low nutrient status and with a low Biological Oxygen Demand (BOD). It is also anticipated that suspended silt in runoff during heavy rainfall periods is likely to be relatively low due to the existing dense vegetation cover in the catchments.

12.3.12   The results of water quality sampling in the fishponds at Fung Lok Wai undertaken in May 2002 are shown in Table 12‑1. These data suggest that water quality in the ponds is generally in accordance with AFCD (1995) recommendations for fishponds although some ponds appear slightly alkaline and BOD is high due to eutrophic status.

 

Table 121       Results of Fishpond/ River Water Quality Survey at Fung Lok Wai

 

Sampled Fishpond

River water Sampling Stations

Parameters

Pond 2

Pond 13

Pond 19

Pond 56

Pond 59

Pond 62

W1 (Shan Pui River)

W2 (Tai River)

pH

6.2

7.7

9.3

6.9

8.9

7.0

7.8

7.5

Conductivity (uS/cm)

2510

1860

635

1640

1100

1100

16500

21500

D.O. (mg/L)

5.4

4.4

7.2

2.6

8.2

2.4

3.1

2.1

% Saturation of D.O. (%)

72.5

62.2

98.1

38.5

108

28.1

41.7

28.7

Temp. (oC)

31.3

31.0

30.4

30.7

32.5

30.5

30.0

29.0

Salinity (g/L)

1.1

0.5

0.3

0.7

0.5

0.5

8.8

11.9

Turbidity (NTU)

45.2

30.7

23.1

63.3

23.5

42.4

12.7

20.0

SS (mg/L)

72.7

57.0

28.3

93.7

47.0

49.7

32.3

26.3

Ammonia as N (mg/L)

0.03

0.03

0.04

2.96

0.07

0.39

5.4

2.8

Nitrate as N (mg/L)

<0.01

<0.01

<0.01

0.04

0.04

0.23

0.6

0.7

Nitrite+Nitrate as N (mg/L)

0.02

0.02

0.02

0.16

0.17

0.31

0.9

1.2

Total Kjeldahl Nitrogen as N (mg/L)

3.2

2.9

3.9

4.6

3.3

3.6

7.3

3.1

Total Nitrogen (mg/L)

3.2

2.9

3.9

4.8

3.5

3.9

8.2

4.3

Total Phosphorus (mg/L)

0.2

0.2

0.2

0.2

0.2

0.3

0.7

0.5

Reactive Phosphorus as P (mg/L)

0.03

0.03

0.02

0.02

0.03

0.02

0.6

0.4

BOD (mg/L)

10.0

8.7

14.3

5.3

9.0

4.7

3.0

<2

Note: All measurements by ALS Technichem (HK) Pty Ltd. on 30 May 2002. See Figure 12‑1 for location of ponds.

Past and Current Land Use

12.3.13   Originally the Deep Bay area was dominated by brackish and freshwater marshland habitats. However, Deep Bay and its surrounding areas have undergone significant changes over the last century which have been discussed in a number of studies (Melville & Morton, 1983; Young, 1991, Aspinwall Clouston and Wetlands International 1997).

12.3.14   Reclamation of marshes and inter-tidal habitats took place predominantly from the last century until the middle of this century, with 1,200 ha of land being reclaimed between 1903 and 1945. This land was converted to agricultural use, mostly cultivation of brackish water rice and shrimp production in gei wais (tidal shrimp ponds).

12.3.15   Between the mid 1960’s and 80’s brackish and fresh water rice cultivation disappeared and almost all cultivated land and gei wais were converted to deep water fishponds.  By 1974, this had become the dominant land use and provided an extensive area of wetland habitat. However, by the same time, virtually all areas of natural and semi-natural freshwater habitat had been lost.

12.3.16   From the late 1970’s to the present urban development has taken over as the main pressure for change in the Deep Bay area, the main impact being the infilling of fishponds and the use of the land for housing, industrial estates and open industrial storage. Between 1985 and 1994, for example, the coverage of fishponds dropped from over 2,000 ha to 1,500 ha, representing a 25% decrease over 10 years.

12.3.17   Furthermore, many fishponds have been abandoned which reduces their ecological value to many important species, in particular herons and egrets. Of the fishponds remaining in the Deep Bay area in 1994 only 78% were still actively managed (Everitt and Cook 1997), with the majority located in the North West New Territories, mostly in or within the vicinity of the Mai Po Inner Deep Bay Ramsar Site.

12.3.18   The Fung Lok Wai site has shown similar changes in land use as the Deep Bay area as a whole. In 1924, it is understood that there was a number of large (presumably tidal) lagoons, within the northern half of the site which is now included within the Mai Po Inner Deep Bay Ramsar Site. Some areas of mangrove still appear to be present within the lagoons. The southern area of the site which currently falls outside the Mai Po Inner Deep Bay Ramsar site boundary but within the boundary of the Wetland Conservation Area (WCA) includes some mangrove but also small rectangular fields, which were probably brackish rice paddies.

12.3.19   An aerial photo dated November 1974 shows that most of the site was still tidal at this time; however a number of fishponds had been established in the south-western portion of the site. Since then, virtually the whole site has been converted to freshwater ponds, the majority of which are currently actively used for freshwater fish farming.

12.3.20   The Fish Pond Study (Aspinwall Clouston & Wetland International, 1997) documented the ecological value and function that aquaculture ponds have to wildlife, particularly waterbirds.  The Fish Pond Study identified that aquaculture ponds within the Deep Bay were managed, until 1995, following traditional aquaculture management practices (i.e. annual stocking, draining and harvesting of the ponds), were of particular ecological value to wetland birds (e.g. Ardeids, Black-faced Spoonbill) when the ponds were drained at harvest time.  The Fish Pond Study revealed that water birds feed on small fish (e.g. Tilapia (Oreochromis mossambicus), Mosquito fish (Gambusia affinis) and Prawns (Macrobrachium nipponense)) that are of no commercial value and which are bi-product of traditional aquaculture management practices.

12.3.21   The area of aquaculture ponds under active management in the Deep Bay area is now declining along with productivity (Table 12‑2).

 

Table 122       Area of Ponds and Inland Fresh Fish Production In Hong Kong. Source AFCD Annual Reports, 2002

Year

Area of ponds (ha.)

Production (tonnes)

1998

1370

4900

1999

1370

4500

2000

1280

2820

2001

1250

2550

 

12.3.22   Some of the key reasons for this decline include:

·        Reduction in market price of fish due to cheaper imports from mainland China;

·        Intensification of some operations; and,

·        Conversion of ponds to other uses.

 

Traditional aquaculture management practices

12.3.23   The following section summarises a five stage annual management cycle practiced by most aquaculturists.

Stage 1: Pond preparation

12.3.24   Drained down ponds are allowed to dry out. Desiccation and the action of sunlight assist breakdown of organic detritus and reduce levels of bacteria and other pathogenic organisms. Traditionally this process allowed take place over the winter months, however, many operators now continue production throughout the year and in these circumstances, following harvesting, eutrophic water from nearby ponds will be transferred to the pond before re-stocking.

12.3.25   When ponds are dried out, a layer of lime (Calcium oxide) is applied to the base of the pond.  The purpose of adding lime is:

·        to neutralise the pH of pond sediments and buffer acid formation. The marine based soils of the fishponds are prone to acidification if allowed to dry;

·        to accelerate the decomposition rate of organic matter that remains at the base of the pond; and

·        to sterilise the ponds of bacteria and other pathogens.

12.3.26   Some operators apply a layer of teaseed cake (Saponin) to the base and sides of the pond to kill carnivorous fish species (e.g. eel, snakehead, catfish) that may burrow into the soft mud of the pond base and emerge after re-filling to predate juvenile stock. 

12.3.27   Organic fertilizer such as poultry manure, peanut cake, decaying fish, etc is applied to the base of the pond to initiate prolific growth of phytoplankton and to provide an organic food supply for zooplankton and aquatic invertebrates, all of which provide a food resource for juvenile fish.

12.3.28   Once prepared, the pond is partially refilled with rain water or by pumped transfer from adjacent ponds.  If pumped, precautions, such as placing nets over inlet pipes, are taken to minimize introduction of predatory fish. The recommended water quality for initiation of fish culture is summarised in Table 123

 

Table 123       Optimum Water Quality Objectives for Initiating Fish Rearing

Variable

Parameters

Ammonia (as nitrogen)

<0.1 mg/l

BOD5

<10 mg/l

Chlorine

<0.1 mg/l

Chlorophyll-a

<1 mg/l

Dissolved oxygen

>1 mg/l

Oxidised nitrogen (as nitrogen)

<5mg/l

PH

6-8.5

Phosphate (as phosphorous)

<1 mg/l

Salinity

<2o/oo

Suspended solids

<20mg/l

 

Stage 2: Stocking

12.3.29   Approximately 95% of aquaculture ponds present within the Deep Bay are managed following a polyculture system i.e. several species of fish are reared simultaneously in the same pond.  Polyculture species of fish are stocked at density of 10,000-35,000 fingerlings per hectare.

12.3.30   A small number of ponds are managed under monoculture systems involving intensive rearing of single species such as catfish, seabass and snakehead.

12.3.31   Traditionally ponds were stocked during the period February to April, increasingly, however, ponds will be stocked at any time of the year reflecting a continuous production cycle.

12.3.32   Stock are now acquired from a variety of domestic and overseas sources including: Mainland China, Taiwan, Japan and Australia. The size of the stock purchased varies from fry (newly hatched fish) that are typically under 1cm in size, to juveniles up to 10 or 15cm. Typical species are indicated in Table 12‑4. The size and species of fish sourced depends on factors such as: personal preference, market availability, price and perceived demand for adult fish.

12.3.33   Once stocked the pond is enriched with nutrients (e.g. fine grains of wheat or soya) to promote phytoplankton growth.

 

Table 124       Summary Of Fish Species Typical Of Polyculture Practice In The Deep Bay Area And Examples Of The Sources Of Stock

Species

Source of Stock

Carp (including silver, grass, mud)

PRC, Taiwan

Grey Mullet

PRC, Hong Kong SAR, Japan, Taiwan

Sea Bass

USA

 

Stage 3: Rearing

12.3.34   Between February and October fish grow rapidly and are consequently fed once to twice a day.  Traditionally a variety of feed materials have been used including: biscuit, bread, brewery waste, corn meal, noodles, peanut cake, wheat bran, rice bran, sorgum, soya bean.  Some farmers now use specialised feed pellets, particularly within those ponds under more intensive rearing regimes. As fish grow the proportion of protein in the diet is increased. 

12.3.35   During the rearing stage fish behaviour is monitored daily.  Evidence of low oxygen concentrations (e.g. large numbers of fish observed close to the surface of the pond), excessive feeding (e.g. accumulations of feed at the pond base) or other problems associated with water quality and disease is corrected accordingly.

12.3.36   Fish appetites are governed by a number of factors including growth stage, temperature and dissolved oxygen concentration. Feed levels are monitored closely to avoid under or over-feeding and to optimise the nutritional content of feed.

12.3.37   During the summer months additional organic fertiliser in the form of, for example, pig and poultry manure or peanut cake, is added to supplement the nutrient status of the ponds and promote phytoplankton production.

Stage 4: Harvesting

12.3.38   Typically fish are harvested once they achieve marketable size (Table 125), although farmers will avoid harvesting when prices are low.

12.3.39   The market value for live fish harvested from aquaculture ponds in the Deep Bay area varies considerably.  For example the market value for Grey Mullet during the early 1980s was approximately $25/ cattie, by late 1998 this had declined to as little as $6/cattie in the face of cheaper mainland imports (Cheung, 1999).

12.3.40   Traditionally harvesting tended to take place between October to March, although continuous production cycles are now seeing fish sent to market throughout the year.

12.3.41   In preparation of harvesting the pond is drained over 2-4 weeks.  Water is pumped into adjacent ponds or watercourses.  Periodically a seine net is dragged across the corner of the pond in an arc shape.  The entrapped fish are removed and placed in tanks before transportation to market.

 

Table 125       Production Time And Acceptable Market Size Of Species Of Fish Raised In Aquaculture Ponds

Species

Number of months required to raise fish to market size (months)

Acceptable market size (kg)

Bighead

9-14

1.0 - 2.0

Common Carp

6-9

0.3 - 0.6

Grass Carp

20 – 24

1.0 - 2.5

Grey Mullet

7 – 12

0.2 - 0.6

Silver Carp

9 – 14

1.0 - 2.0

Tilapia

4 – 9

0.2 - 0.6

 

Stage 5: Pond maintenance

12.3.42   Following fish harvesting, the base and sides of the pond are allowed to dry out to aid removal and decomposition of accumulated organic material. Discontinuation of the practice of rearing ducks in association with fishponds has reduced the level of organic input and reduced the need for annual removal of detritus by bulldozer.  Consequently ponds are now only dredged once every three to five years. 

 

12.4          Baseline condition

Aquaculture

12.4.1      For the purpose of this report the rearing of fish in commercial fishponds is referred to as “aquaculture”. The personnel who undertake the daily management of the ponds are “aquaculturists”. “Actively managed ponds” refers to aquaculture ponds present within the Assessment Area” in which fish are actively reared for commercial purposes. These were identified during a site inspection conducted in January 2001 on the basis of the following criteria:

·        Evidence that the vegetation growing on adjacent pond bund is managed (i.e. cut back);

·        Commercial fish species present;

·        Evidence of recently used aquaculture equipment; or,

·        Presence of fish-rearing paraphernalia, such as, for example, fish feed and nutrients (e.g. manure).

12.4.2      Ponds that did not meet these criteria (ie for which there was no evidence of fish being reared for commercial purposes) were designated “unmanaged ponds”. It should be noted, however, that the status of ponds can change from time to time.

Status of Aquaculture Management of Ponds within the Assessment Area

12.4.3      The extent of aquaculture ponds within the Assessment Area is summarised in Table 12‑6.

12.4.4      The majority of these ponds are under active management with occasional ponds that appear to have fallen into disuse. Ponds range in size between from approximately 0.17 to 2.87 ha. with a mean size of approximately 1.5 ha.

 

Table 126       Extent of Habitats Identified Within the Fung Lok Wai Assessment Area

Habitat

1. Proposed Development Area

2. Wetland Nature Reserve

3. FIA Assessment Area (1 + 2)

Intertidal forested wetlands

0

0

0

Permanent rivers, streams and creeks

0

0

0

Ditches and drainage channels

0.02

0.38

0.40

Aquaculture pond (actively managed)

2.56

59.88

62.44

Aquaculture pond (unmanaged)

0.75

7.41

8.16

Pond bunds

0.67

8.44

9.11

Reedbed

0

0

0

Permanent freshwater marsh and pools

0

0

0

Seasonally flooded (wet) agricultural land

0

0

0

Dry agricultural land

0

0

0

Inactive agricultural land

0

0

0

Orchard

0

0

0

Fung-shui forest

0

0

0

Semi-natural secondary woodland

0

0

0

Plantation forest

0

0

0

Grassland

0

0

0

Grassland – shrubland mosaic

0

0

0

Landscaped area

0

0

0

Works in progress

0

0

0

Wasteland

0

0

0

Developed area

0

0

0

TOTAL

4.00

76.11

80.11

 

12.4.5      Discussions with operators reveal that the dominant approach to aquaculture at Fung Lok Wai is freshwater polyculture with most farmers stocking 6-7 species concurrently. The main species stocked are Grey Mullet, which tends to comprise approximately 70% of stock with the remaining 30% comprising: Tilapia species, Carp species (eg common carp) and Bighead.

12.4.6      Data on the total production (total weight) and market value of fish raised at Fung Lok Wai are not available. Furthermore, estimates for aquaculture productivity within Hong Kong vary. AFCD data for Hong Kong as a whole indicate that in 2001, within inland waters approximately 1,059 ha of fishponds produced 2,550 tonnes of fish at a combined market value of $41 million (AFCD 2002). This suggests an average productivity of approximately 2.4 tonnes per hectare per year. This figure includes, however, ponds in varying states of productive use and is unlikely to reflect practice in the Deep Bay where ponds are amongst the most intensively farmed within the territory.

12.4.7      In contrast, discussions with operators in the Deep Bay area undertaken by WWF (T. Lau pers. comm.) suggest an average annual productivity figure of over 9 tonnes per hectare is regularly achieved and discussions with some operators at Fung Lok Wai indicate productivity closer to 12.5 tonnes per hectare per year.

12.4.8      Profitability of fishfarming operations is clearly highly variable between operators. The industry has been facing competition from China. To maintain profitability some operators have sought to raise income by increasing the stocking proportion of higher value species such as Grey Mullet whilst at the same time limiting costs by, for example, reducing the frequency of maintenance activities and increasing the frequency of harvesting.

12.4.9      Previous investigations into fisheries operations in the Deep Bay area (e.g. BBV 2002) and discussion with WWF (T. Lau, pers comm.) suggest that a profit of between $40,000 - $50,000 per hectare per year is made. Discussions with the operators at Fung Lok Wai suggested even higher figures of $60,000 to $75,000 per hectare per annum.

12.4.10   It should be noted that many farmers operate small operations of 1 or 2 ponds and supplement their income from other sources. Some of these farmers will choose not to maximise the productivity of their ponds and be satisfied with both lower income and productivity than the figures presented here.

12.4.11   Traditionally managed aquaculture ponds also produce a non-commercial by-product in the form of small fish and crustaceans including: Small Tilapia (O. mossambicus), Mosquito fish (G. affinis) and Prawns (M. nipponense).  The availability of these species to feeding birds during pond drain down is a key feature of their ecological value and importance for conservation.

12.4.12   The combined mean weight of non-commercial by-product for ponds in Deep Bay is estimated at approximately 260 kg/ha (Aspinwall 1997, Primavera 2000).  On this basis, assuming that all actively managed ponds operated within the Assessment Area were managed according to traditional polyculture practice, the total annual yield of non-commercial species at Fung Lok Wai would be approximately 16.4 tonnes.

Other aquaculture activities

12.4.13   Deep Bay is the location for aquaculture practices including oyster culture.

12.4.14   Oysters have been cultured along the intertidal mud flat of Deep Bay for over 200 hundred years. Juvenile oysters are imported from the Mainland and grown out on rafts in the shallow coastal waters of Deep Bay.  Oysters are also cultured in inter-tidal areas on the seabed using concrete posts as clutches.  In 2001 oyster meat production was estimated at 115 tonnes worth about $5 million.

Marine and coastal fisheries

12.4.15   In 2001 AFCD (2002) indicate that the marine fishing fleet in Hong Kong produced an estimated 173,970 tonnes of fish valued at $1,730 million. 90% of this total catch comes from waters outside Hong Kong. The industry comprises approximately 4,500 fishing vessels employing 192,000 fishermen.

12.4.16   Within Hong Kong waters production is estimated at around 18,000 tonnes with most caught in north-eastern waters. Whilst Deep Bay is not considered a particularly important area for net fishing, it is an important area for crustaceans particularly Trachypenaeus curvirostris. Dominant species caught in Deep Bay included Panaeidae (prawns), Sciaenidae (croaker) and Squillidae (mantis shrimp).  Of the eighteen sites sampled in Hong Kong marine waters by shrimp trawlers during the AFCD baseline fisheries survey conducted in 1996 the highest diversity of species of were caught in Deep Bay.

 

12.5          Impact Identification and Assessment

Scoping

12.5.1      The nature of the proposal means that most direct and indirect impacts will be constrained to the Assessment Area, that is the proposed Development Area and the area proposed for the construction of the Wetland Nature Reserve.

12.5.2      The potential for off-site impact on adjacent fishponds and mariculture and marine and coastal fisheries resources within Deep Bay has been considered. The outcome of the water quality impact assessment, however, indicates that the probability of off-site impacts through discharge or surcharge of contaminated water is extremely low. Normal precautions will be undertaken to restrict discharge of sediment and waterborne pollutants during construction. During operation stormwater run-off will be diverted to the storage pond of the WNR. In the event that severe rainfall causes surcharging of fishponds and marsh habitats, is unlikely to cause impact to neighbouring ponds and estuarine and marine receiving waters because:

·        Only limited water will be discharged from the WNR to the surrounding (mostly flow through the Tai River with poor existing water quality). Water can be recirculated back into the storage pond when needed. In any event the predicted water flow of the WNR is very similar to existing situation, i.e. stormwater from catchments and water from fishponds already flow into the Tai River.

·        No pesticides and herbicides will be added and discharged during the construction and operation of the WNR.

·        Storage and settling of catchment water within the storage pond is likely to improve water quality, particular in relation to suspended solids.

·        The isolated fishponds in the WNR will only discharge water to the surrounding during flooding event. As average water depth of the fishponds will be maintained lower than those existing ponds, the threat of flooding will be reduced compared to the existing situation.

12.5.3      The preferred option for the disposal of sewage is Strategy A2 described in Chapter 8. New sewage pipes laid under this strategy (and Strategy A1) follow existing roads and avoid aquaculture ponds. In any event the use of twinned sewage pipes will enable the impacts of sewer bursts to be controlled. The risk of significant impact arising from pollution due to pipe failure is, therefore, considered to be extremely small.

12.5.4      Strategy B follows a western route and would involve the laying of pipes beneath the freshwater marsh and adjacent to three ponds located to the west of the Assessment Area. During the site assessment undertaken in January 2001, two of these ponds were found to be inactive, although the status of ponds can change. As in Strategy A, the use of twinned pipes will enable control of sewage in the event of a burst pipe. Whilst the risk is low, the magnitude of any impact arising because of a sewage leak along this route would be greater than for Strategy A2 (or A1) due to the proximity of the ponds.

12.5.5      All strategies, however, involve the construction of an on-site sewage pump house. In the event of an emergency or power failure, sewage may need to be diverted past this station. To avoid potential impact a by-pass pipe will be installed to direct sewage to the Tai River via Channel “X” thus avoiding the potential for contamination of aquaculture ponds.

12.5.6      The Assessment Area is not an important breeding or nursery ground for commercially important species of fish (ERM, 1998).

12.5.7      Consideration of potential impacts within the Assessment Area, therefore, indicates the following are likely to occur as a result of the proposal:

·        Construction phase

o        Permanent loss of aquaculture ponds; and,

o        Temporary loss of aquaculture ponds.

·        Operational phase

o        Modification of aquaculture ponds including reduced intensity of aquaculture operation.

Evaluation of the significance of impacts

Construction phase

Permanent loss of aquaculture ponds

12.5.8      The Project involves the construction of the Wetland Nature Reserve comprising enhanced and enlarged fishponds, rain fed ponds for water birds and a complex of freshwater marshlands and the construction of residential development. The design principles of no net loss of waterbody area and functional enhancement of wetland habitats are to be achieved through the reconfiguration of pond bunds to create larger and functionally enhanced ponds which are more preferred by birds and to create land for residential development. Through the pond bunds reconfiguration, there will be a slight increase in area of water body within the Site.

12.5.9      Construction of the proposed development, including the Wetland Nature Reserve will result in the permanent conversion of 19 complete ponds and about one third of an additional pond, a total area of approximately 18.4 ha, to residential development and freshwater marsh. Thirty-one of the remaining 37 ponds will be consolidated to 18 larger ponds which will continue to be managed as fishponds, although in modified form (see below). The remaining 6 ponds will be taken out of production (consolidated into 3 larger ponds) and managed as rain fed ponds for duck and other water birds.

12.5.10   In total, therefore, 25 whole ponds and approximately 1/3 of an additional pond (approximately 26.2 ha.) will be permanently converted to non-production uses. Of these, 6 (approximately 5.4 ha) were characterised as “unmanaged” at the time of the survey, so the loss of productive ponds equates to approximately 20.8 ha.

12.5.11   Based on an anticipated gross productivity in the range 9-12.5 tonnes of freshwater fish per hectare per annum, this removal equates to a loss in gross annual productivity of 187-260 tonnes of fish worth approximately $3-$4.2 million at an assumed average market price of $16 per kg (See Table 12‑7).

Table 127       Wholesale price range per kg of freshwater fish during the period January – December 2001. Source: AFCD, fax 11/9/02

Species

Price range ($)

Average ($)

Grey Mullet

12.20 – 16.70

14.30

Silver Carp

5.80 – 7.00

6.20

Big Head

11.60 – 14.00

12.80

Grass Carp

11.60 – 13.70

12.60

Tilapia

5.50 – 7.80

6.60

Common Carp

5.50 – 8.40

6.80

Mud Carp

15.60 – 18.40

16.80

 

Temporary loss

12.5.12   On acquisition of the site all ponds will be taken temporarily out of production and managed according to an interim management regime whilst the Wetland Nature Reserve is constructed. This management regime will focus on the production of “trash fish” for bird species of conservation importance, particularly herons and egrets, and involves:

·        Correcting the pH of the water

·        Stocking those ponds that are fish depleted with “trash fish” species

·        Periodically draining down designated ponds according to a pre-determined schedule

·        Re-correcting pH and re-stocking as required

12.5.13   The programme and methods of pond enhancement are detailed in the Fung Lok Wai Habitat Creation and Management Plan that accompanies this EIA report.

12.5.14   Briefly, however, it will involve the temporary drainage and reprofiling of 37 of these ponds. As indicated above six of these will be permanently taken out of production and consolidated into 3 larger ponds. Works on the remaining 31 ponds will be staged so at any point in time only two or three ponds (adjacent pairs or triplets) will be drawn down and re-profiled.

12.5.15   With respect to aquaculture operations, however, the key issue is the timing and sequencing of pond enhancement works. To reduce disturbance of valued ecological components associated with the use of heavy machinery, pond enhancement works will be staged. Three sectors of ponds have been defined (Figure 12‑2) within which works will be conducted sequentially according to the schedule identified in Table 128.

 

Table 128       Schedule for pond enhancement works. Bund numbers are illustrated in Figure 12‑2

Sector

Expected duration of works

Expected completion of enhancement works (indicative)

Time out of production

Expected time under interim management

Sector 1 pond bunds:

1, 2, 3, 4, 5, 6, 7

13 weeks

March 2011

Approx. 9 months

66 months

Sector 2 pond bunds:

9, 10, 29

6-7 weeks

September 2011

Approx. 15 months

60 months

Sector 3 pond bunds:

8, 11, 12, 14, 15, 16

14 weeks

September 2012

Approx. 21 months

54 months

 

 

12.5.16   After completion of enhancement works the ponds will be placed under interim management as part of the mitigation strategy for predicted ecological impacts arising from Residential Development construction as described in Section 13. Interim management will involve stocking ponds at artificially high densities and extending the draw down periods of the ponds to encourage higher piscivorous bird densities. The sequencing of works and the periods during which ponds will be under different management regimes in summarised in Figure 13-13. The length of time that ponds will be out of production or under interim management will vary (see Table 128). The maximum period that ponds will be completely out of production will be 21 months (in the case of Sector 3) and the maximum period that ponds will be under the interim management regime will be 66 months (Sector 1). On completion of the development works (duration about 75 months) all ponds will be returned to polyculture operation with some amendments (see below). It is anticipated that this will occur from October 2016 onwards.

Operational phase

Modified production within WNR

12.5.17   During the process of enhancement 31 ponds will be consolidated into 18 of total area of about 47.0 ha. average size 2.6 ha (the average size of existing ponds is about 1.5 ha.).

12.5.18   Following completion of enhancement works, these 18 ponds will be managed according to a modified traditional commercial aquaculture procedures involving stocking, rearing, harvesting and periodic set-aside for maintenance and recovery with several key differences:

·        The management of the 18 ponds in active production will be coordinated. Most farmers typically operate a handful of ponds at the same time. The management of such a large block of ponds en masse will allow for a coordinated approach to fish production, maintenance and monitoring activities. It will also facilitate a more effective approach to their adaptive management.

·        Ponds in production will be drained down annually for a fixed period of 20 days. Ponds are typically drawn down for shorter periods under normal management regimes.

·        Approximately 25% of ponds will be “set-aside” for production according to a 5 yearly schedule. This will provide opportunity for maintenance works and allow for control of diseases or presence of undesirable species. Set-aside is a more ad hoc process under normal management procedures.

·        Whilst most fish selected for farming will be those typical of commercial aquaculture operations, the composition and proportions of these species will be varied to benefit feeding wildlife to meet HCMP targets. This may result in a reduction of the productivity expected within purely commercial operations.

12.5.19   The introduction of measures to encourage increased wildlife usage are expected to reduce commercial productivity. The magnitude of reduction is not known precisely, but is expected to be in the region of 20%. For the purposes of this assessment, it is assumed, therefore, that productivity rates will be about 80% of the average for traditional commercial polyculture.

12.5.20   At assumed levels of production (between 9-12.5 tonnes per ha) 46.65 ha of ponds would be expected to produce between 420-583 tonnes of fish per annum. At the reduced levels of productivity envisaged this figure equates to 336-467 tonnes per annum, or a “loss” of productivity of between 84-116 tonnes per annum.

Summary of predicted impacts

12.5.21   The proposed development will result in the permanent loss of 20.8 ha. of active commercial fishpond and 5.38 ha. of inactive ponds. Associated lost productivity equates to approximately 187-260 tonnes of fish worth approximately $3-$4.2 million at an assumed average market price of $16 per kg.

12.5.22   During the first two years of construction all ponds will be taken out of production with some being converted to other uses and 46.65 ha. being progressively reprofiled. Following pond enhancement works the ponds will be placed under an interim management regime, designed to improve their attractiveness to wildlife, particularly birds, until completion of the Residential Development construction works. The total period that ponds will be take out of production to allow enhancement works or under the interim management regime will be approximately 75 months.

12.5.23   On completion of the Residential Development the ponds will be returned to a modified traditional management practice as part of the long-term management strategy for the WNR. Under this management regime, the ponds will operate at about 80% of the productivity of average commercial polyculture ponds.

12.5.24   As no significant off-site impacts associated with construction activities or operation are anticipated, the risk of impact to adjacent fishponds and Deep Bay mariculture, oyster farming and marine fishing activities is considered to be very low.

12.5.25   On the basis of the information in this chapter regarding fish pond management and associated socio-economic issues, an overall evaluation has been prepared in Table 12‑9 using the criteria listed in Annex 9 of the EIA Ordinance Technical Memorandum.

 

Table 129       Summary of importance of the fisheries resources within the Fung Lok Wai Assessment Area and evaluation of predicted impacts

 

Evaluation

Criteria

Aquaculture

Oyster farming

Marine & coastal fishing

Size

Active: 62.44 ha.

Inactive: 8.16 ha.

Small areas within Deep Bay

N/A

Typical resources/ production within the Assessment Area

Freshwater fish: 562-781 tonnes per annum

None within Assessment Area

None within Assessment Area

Typical production in Hong Kong

2,550 tonnes per annum

115 tonnes per annum

Marine fish: 18,000 tonnes per annum

Number of operators within the Assessment Area

21 known

None

None

Evaluation of importance of resource within the Assessment Area

Moderate

N/A

N/A

Nature of impacts

Conversion of some ponds to non-productive uses

Modification of management of remaining ponds to less productive operation

Potential for indirect impacts due to release or surcharge of poor quality water. Standard pollution control procedures are expected to mitigate these potential impacts

Potential for indirect impacts due to release or surcharge of poor quality water. Standard pollution control procedures are expected to mitigate these potential impacts

Destruction and disturbance of nursery and spawning grounds

None

None predicted

None predicted

Size of area affected

Permanent loss of 26.2 ha

Temporary loss of 46.65 ha for a period of 75 months (including during enhancement works and during interim management).

Reduced long-term production within 46.65 ha.

None predicted

None predicted

Loss of fisheries / resource production

Permanent loss: Estimated between 187-260 tonnes per annum productivity

Loss due to reduced productivity within Wetland Nature Reserve ponds: 84-116 tonnes per annum (assumes 80% of existing productivity)

Total loss: between 271-376 tonnes per annum

None predicted

None predicted

Overall impact

Moderate

None predicted

None predicted

 

Cumulative impacts

12.5.26   Other significant projects within Deep Bay that may also result in temporary or permanent loss or modification of fishponds include:

·        Improvements to San Tin Interchange (EIA093/2004) – An EIA report was approved under the EIAO on 3/5/2004.  The report concluded that the project would not caused direct loss of existing fish ponds.

·        KCRC Sheung Shui - Lok Ma Chau Spur Line (EIA-071/2001) – approved in April 2002, the EIA report for this project predicts the permanent loss of 0.4ha of active aquaculture ponds and a further 9.2 ha of inactive ponds. As compensation for predicted ecological impacts, at least 27.1 ha of disused fishponds will be re-established and managed in a traditional polyculture approach with enhancements to favour wildlife in the Lok Ma Chau area. Station construction and wetland compensation works has been completed.

·        The EIA report of Yuen Long and Kam Tin Sewerage and Sewerage Disposal Stage 2 (EIA-074/2002) – approved in August 2002 under EIAO stated that this project will result in a small loss of approximately 0.15 ha. of inactive ponds.

12.5.27   There are other concurrent projects but none of these are expected to result in significant loss of fishponds or result in impact to fisheries resources.

 

12.6          Fisheries Mitigation / Compensation Measures

12.6.1      Key mitigation measures to be incorporated into construction procedures to protect the water quality of fishponds within the Fung Lok Wai Assessment Area, adjacent fishponds and Deep Bay estuarine and marine environments are outlined in the section addressing Water Quality Impacts.

12.6.2      A key objective of the Wetland Nature Reserve is to continue traditional polyculture aquaculture, in modified form, within a substantial area of aquaculture ponds. These ponds will be run on commercial lines, in a way that is consistent with the conservation objectives of the Wetland Nature Reserve. Against the backdrop of a marked decline in fishpond activities within Hong Kong, the incorporation of these activities within the management framework of the Wetland Nature Reserve ensures a degree of security of operation that cannot now be guaranteed elsewhere.

 

12.7          Monitoring and Audit Programme

12.7.1      Consistent with the adaptive management framework proposed for the ongoing management of the Wetland Nature Reserve, a monitoring programme will be instituted to assess the success of fisheries production and to identify requirements or potential for modification. Whilst the primary objective of management is the achievement of conservation objectives, commercial fish production practices will continue to form a key element of the operation of the Wetland Nature Reserve.

12.7.2      Details of monitoring along with action levels and limits are included in the Habitat Creation and Management Plan.

 

12.8          Conclusion

12.8.1      Aquaculture in Hong Kong is declining because of increased competition from mainland suppliers and other poorly understood social processes. The result is increasing abandonment of fishponds and their conversion to other uses. Whilst there has been some move to intensive monoculture rearing, this still accounts for about 5% of productive ponds in Hong Kong. The same economic forces that are driving abandonment of polyculture ponds may also undermine the profitability of monoculture operations.

12.8.2      The proposed development at Fung Lok Wai will result in the loss of some ponds. Those ponds that remain, however, will be enhanced to increase their ecological values, primarily for bird Species of Conservation Importance. They will, however, continue to be managed in largely traditional manner within which fish production will still be a key objective. The establishment of the Wetland Nature Reserve will ensure that this enhanced management regime is implemented in the long-run. In this respect the fish production and fishponds will enjoy greater security than comparable ponds elsewhere within Deep Bay.

12.8.3      The long-term management of these ponds ensures the preservation of the cultural practice of aquaculture in-situ, which is consistent with concepts of “wise use” fore-shadowed in Article 3.1 of the Ramsar Convention. It also provides opportunities for ongoing research into sustainable fish production and wildlife conservation.

12.8.4      Off-site impacts are not predicted as the likelihood of adverse impacts on water quality of neighbouring ponds, estuarine and marine receiving environments is considered to be very low during either construction or operation phases.

 

12.9          References/ Bibliography

1.       (AFCD) Agriculture, Fisheries and Conservation Department (2002) Fisheries website. [URL] www.afcd.gov.hk

2.       Aspinwall (1997). Study on the Ecological Value of fish Ponds in Deep Bay Area: Executive Summary. Planning Department, Hong Kong SAR Government.

3.       Aspinwall Clouston & Wetlands International – Asia Pacific (1997). Development of a comprehensive conservation strategy and a management plan in relation to the listing of Mai Po and Inner Deep Bay as a Wetland of International Importance under the Ramsar Convention.  Agreement No. CE47/95.

4.       Binnie, Black & Veatch (2002). Sheung Shui To Lok Ma Chau Spur Line Environmental Impact Assessment Report. Kowloon Canton Railway Corporation, January 2002.

5.       Cheung, Y.M.J.  (1999) The socio-economics of pond-fish farming and its implications on future land use in and around Mai Po and Inner Deep Bay Ramsar Site.  Master of Science of Environmental Management dissertation.

6.       Environment Protection Department (2000). EAI Study Brief (ESB-055/2000) for Proposed Development at Fung Lok Wai, Yuen Long at lot 1457 RP in DD 123. EPD, Hong Kong.

7.       ERM (1998). Fisheries Resources and Fishing Operations in Hong Kong Waters. Report for Agricutlure, Fisheries and Conservation Department.

8.       Everitt, S. & Cook, J.  (1997) Regional Study and Workshops on Aquaculture: Sustainability and the Environment.  Hong Kong Study Report.  Asian Development Bank.

9.       Melville, D.S. & Morton, B. (1983). Mai Po Marshes.  World Wildlife Fund for Nature Hong Kong, Hong Kong.

10.   Primavera, J.H. (2000). Integrated Mangrove – Aquaculture Systems in Asia. Integrated Coastal Zone Management, Autumn edition, pp. 121-130.

11.   Townland Consultants Ltd, Wong Tung & Partners Ltd, Maunsell Consultants Asia Ltd, MVA Asia Ltd, CES Asia Ltd, Belt Collins & Associates HK ltd, Nelson and Wright (1992). Sunnyville Estate development at Nam Sang Wai, Engineering Assessment Report, Nam Sang Wai Development Co, Ltd & Kleener Investment Ltd.

12.   Young, L. (1991). Conservation of wildlife in the Deep Bay area: with particular reference to heron species. pp. 813-822. In: Boxall, J. (ed.) Polmet '91; Pollution in the metropolitan and urban environment. Hong Kong Institution of Engineers, Hong Kong.

 

13.             Ecological impact Assessment

13.1          Introduction

13.1.1      This section presents the findings of this assessment which includes consideration of the potential and predicted impacts associated with the construction and operation of: a residential development, an access road, sewerage facilities (including pump house and pipeline) and an on-site wetland nature reserve.

13.1.2      The Fung Lok Wai site comprises approximately 80.1 hectares of which about 4.0 hectares (5%) will be affected by the residential development and associated access roads. The remaining 76.1 hectares (excluding the access road) will form the Wetland Nature Reserve (WNR).  Figure 13‑1 illustrates the site boundary and extent of ecological assessment. For the purposes of this assessment the following areas were defined:

·        Proposed Development Area – the area directly affected by residential construction;

·        Wetland Nature Reserve – the area of fishpond enhancement and marshland creation;

·        Study Site – comprising the Proposed Development Area, the proposed Wetland Nature Reserve;

·        500m Buffer Zone – the buffer established around the Study Site including the access road for the purposes of the assessment impacts on terrestrial habitats in accordance with the EIA study brief;

·        Assessment Area – comprising the study site and the buffer zone.

Scope and aims of this Ecological Impact Assessment

13.1.3      In accordance with Section 3.5.6.2 of the Study Brief the spatial extent of this assessment comprises:

·        all terrestrial and freshwater aquatic habitats present within the boundary of the proposed development and surrounding 500m buffer zone; and

·        marine habitats within the entire extent of the Deep Bay Water Quality Inner and Outer sub-zones (DM3) (EPD, 2000).

13.1.4      The aims of this assessment are to provide sufficient and relevant information to assist the Environmental Protection Department (EPD) and the Agriculture, Fisheries and Conservation Department (AFCD) to:

·        Identify, assess and evaluate the ecological resources (i.e. Valued Ecological Components (VECs) and Species of Conservation Importance (SoCI)) that will be affected by construction and operation of the proposed development;

·        Identify, assess and evaluate any adverse ecological impacts that will arise during the construction and operation of the proposed development, and evaluate the acceptability of these impacts;

·        Identify, assess and evaluate the effectiveness of proposed mitigation measures that will be adopted to minimize or eliminate the predicted ecological impacts that will arise during the construction and operation of the proposed development;

·        Identify, assess and evaluate the predicted residual ecological impacts that will arise as a result of the construction and operation of the proposed development following implementation of the proposed mitigation measures;

·        Evaluate the acceptability of these residual impacts once the proposed mitigation measures are implemented; and,

·        Identify, assess and evaluate the effectiveness of proposed wetland compensation measures, in the form of an on site WNR.

Specific objectives of this assessment

13.1.5      The EIA study brief for this proposal (EPD, 2000) identifies specific objectives and requirements for the Ecological Impact Assessment. The relevant sub-section within which each of these objectives is addressed is indicated as follows:

·        review and incorporate the findings of relevant studies including the Tin Shui Wai Development Engineering Investigations for Development of Area 3, 30 & 31 of the Development Zone and the Reserve Zone and collate all the available information regarding the ecological characters of the ‘‘Assessment Area’’. Details of the literature review undertaken during the investigation are provided in Section 13.3 and Section 13.4.1 – 13.4.40;

·        identify any information gap relating to the assessment of potential ecological impacts to the terrestrial and aquatic environment. Key information gaps are summarised in Section 13.4.41 – 13.4.42;

·        carry out any necessary field surveys, the duration of which shall be at least 12 months and cover the winter migratory bird season, and investigations to fill in the information gap, if any, and to fulfil the objectives of the EIA study. Details of the baseline surveys undertaken over 12 months are described in Section 13.5;

·        establish the general ecological profile and describe the characteristics of each habitat found within the study boundary, committed ecological measures including those under the EIA Ordinance or the Town Planning Ordinance (such as reinstatement of fishponds) should be taken into consideration; major information to be provided shall include:

o        description of the physical environment (addressed in Section 13.2);

o        habitat maps of suitable scale (1:1000 to 1:5000) showing the types and locations of habitats in the ‘’Assessment Area’’ (provided in Figure 13‑9);

o        ecological characteristics of each habitat type such as size, vegetation type, species present, dominant species found, species diversity and abundance, community structure, inter-dependence of the habitats and species, and presence of any features of ecological importance (details provided in Section 13.6);

o        representative colour photographs of each habitat type and any important ecological features identified (included in Appendix 13-2);

o        species found that are rare, endangered and/or listed under local legislation, international conventions for conservation of wildlife/habitats or red data books (addressed in Section 13.6 and summarised in paragraphs 13.6.79 – 13.6.82);

·        investigate and describe the existing wildlife uses of various habitats with special attention to:

o        wetlands including fish ponds, wet agricultural land, marsh;

o        avifauna;

o        fung shui woodland;

o        natural stream courses and man made drainage channels; and

o        any other habitats and wildlife groups identified as having special conservation interests by this study (the habitats each species are associated with are described in Section 13.6).

·        describe all recognized sites of conservation importance in the proposed development site and its vicinity in particular the Deep Bay Wetland Conservation Area, Wetland Buffer Area, Mai Po Inner Deep Bay Ramsar Site and Tin Shui Wai Wetland Park (now called Hong Kong Wetland Park) and assess whether these sites will be affected by the proposed developments or not (recognised sites of conservation importance are described in Section 13.4 a description of the potential affects of the proposed development on these sites is included in Section 13.8.1 – 13.8.6);

·        investigate the impact of the high rise residential buildings in the project area on the bird’s flight path taking into account of diurnal and seasonal patterns (the effects of the construction of high rise buildings on the flightpaths of birds are analysed in detail in paragraphs 13.6.68 – 13.6.76 and under “Habitat Fragmentation” in Section 13.7);

·        using a suitable methodology, identify and quantify as far as possible any direct, indirect, onsite, primary, secondary and cumulative ecological impacts such as destruction of habitats, reduction of species abundance/diversity, loss of feeding grounds, reduction of ecological carrying capacity, loss in ecological linkage and function, habitat fragmentation and other possible disturbances caused by the development of the project and the activities of the residents (the potential effects of the development are assessed in Section 13.7);

·        evaluate the significance and acceptability of the ecological impacts identified using well-defined criteria (the significance of potential impacts are evaluated in Section 13.8);

·        recommend all possible alternatives (such as modifications of layout and design) and practicable mitigation measures to avoid, minimize and/or compensate for the adverse ecological impacts identified (mitigation options are described in Section 13.9);

·        evaluate the feasibility and effectiveness of the recommended mitigation measures and define the scope, type, location, implementation arrangement, subsequent management, resources requirement and maintenance of such measures (the feasibility and effectiveness of mitigation measures is discussed in Section 13.9);

·        determine and quantify as far as possible the residual ecological impacts after implementation of the proposed mitigation measures (residual impacts are described in Section 13.10);

·        evaluate the severity and acceptability of the residual ecological impacts using well-defined criteria.  If off-site mitigation measures are considered necessary to mitigate the residual impacts, the guidelines and requirements laid down in the TM shall be followed (residual impacts are described in Section 13.10);

·        review the need for and recommend any ecological monitoring programme required (see Section 13.11).

·        propose a management package for the 71.6 ha Wetland Nature Reserve in the project area with particular attention to (the design and management of the WNR is summarised in Section 13.9 and described in detail in Section 14. Financial and administrative details of the WNR are described in Section 15.):

o        the habitat management plan and specification of resources requirement for its implementation;

o        the long-term trust management system with management guidelines;

o        the financial arrangement to sustain the management of the wetland;

o        the management agents and their responsibility;

o        a contingency plan for the management of the WNR before the well establishment of trust management;

 

13.2          Description of the Physical Environment

13.2.1      This sub-section provides details of the geographical and physical context of Fung Lok Wai including past and present land-uses, superficial geology, topography, hydrology and water quality.

Location and Regional Context

13.2.2      The study site is located to the south of Inner Deep Bay in the North West New Territories of the Special Administrative Region of Hong Kong. Figure 13‑2 illustrates the location of the Assessment Area in the context of the Deep Bay environs. To the west the site is bounded by mangroves along the tidal creeks of the Tai River outfall, beyond which are grasslands, reedbeds, a plantation and fishponds. Further to the west of Fung Lok Wai is Tin Shui Wai New Town. To the north-west there is an area of tidal lagoons (near Tsim Bei Tsui) created by the construction of a causeway for the road and border security fence.

13.2.3      The site is bounded to the north and east by wetland habitats. There is a continuous band of one or two fishponds bound the site to the immediate north, beyond which lies a belt of mangroves which give way to the tidal mudflats and increasingly marine conditions of Inner Deep Bay. Further to the north-east, beyond the Shan Pui River, there is a large area of fishponds and the Mai Po Nature Reserve, a complex of mangrove, gei wai, reedbed and fishponds. Fishponds also bound the site to the east, beyond which is a strip of landscaped land either side of the closed area boundary road, which demarcates the eastern extent of land reclamation. Further east is the Main Drainage Channel for Yuen Long, Kam Tin and Ngau Tam Mei drainage from the Shan Pui River. To the south east lies Yuen Long Sewage Treatment Works to the south of which lies Yuen Long Industrial Estate.  The south of site is bounded by undeveloped low hills. These are predominantly covered in semi-natural scrub and woodland vegetation with some grassland and orchards. Much of the lower lying areas have been developed for residential housing or cultivated for wet and dry agricultural uses, depending on drainage conditions. Tin Shui Wai new town lies to the south-west and in the western part of the site there are large areas currently under construction relating to the ongoing development of Tin Shui Wai and the operation of Hong Kong Wetland Park.

Past and Current Land Use

13.2.4      Originally the Deep Bay area was dominated by brackish and freshwater marshland habitats. However, Deep Bay and its surrounding areas have undergone significant changes over the last century which have been discussed in a number of studies (Melville & Morton, 1983; Young, 1991, Aspinwall Clouston and Wetlands International 1997).

13.2.5      Reclamation of marshes and inter-tidal habitats took place predominantly from the last century until the middle of this century, with 1,200 ha of land being reclaimed between 1903 and 1945. This land was converted to agricultural use, mostly cultivation of brackish water rice and shrimp production in gei wais (tidal shrimp ponds).

13.2.6      Between the mid 1960’s and 80’s brackish and fresh water rice cultivation disappeared and almost all cultivated land and gei wais were converted to deep water fishponds.  By 1974, this had become the dominant land use and provided an extensive area of wetland habitat. However, by the same time, virtually all areas of natural and semi-natural freshwater habitat had been lost.

13.2.7      From the late 1970’s to the present urban development has taken over as the main pressure for change in the Deep Bay area, the main impact being the infilling of fishponds and the use of the land for housing, industrial estates and open industrial storage. Between 1985 and 1994, for example, the coverage of fishponds dropped from over 2,000 ha to 1,500 ha, representing a 25% decrease over 10 years.

13.2.8      Furthermore, many fishponds have been abandoned which reduces their ecological value to many important species, in particular herons and egrets. Of the fishponds remaining in the Deep Bay area in 1994 only 78% were still actively managed (Everitt and Cook in press, cited in Aspinwall Clouston and Wetlands International 1997), with the majority located in the North West New Territories, mostly in or within the vicinity of the Mai Po Inner Deep Bay Ramsar Site.

13.2.9      The Fung Lok Wai site has shown similar changes in land use as the Deep Bay area as a whole. In 1924, it is understood that there was a number of large (presumably tidal) lagoons, within the northern half of the site which is now included within the Mai Po Inner Deep Bay Ramsar Site. Some areas of mangrove still appear to be present within the lagoons. The southern area of the site which currently falls outside the Mai Po Inner Deep Bay Ramsar site boundary but within the boundary of the Wetland Conservation Area (WCA) includes some mangrove but also small rectangular fields, which were probably brackish rice paddies.

13.2.10   An aerial photo dated November 1974 shows that most of the site was still tidal at this time; however a number of fishponds had been established in the south-western portion of the site. Since then, virtually the whole site has been converted to freshwater ponds, the majority of which are currently actively used for freshwater fish farming.

Geology and Soils

13.2.11   The superficial geology of the site consists of estuarine deposits of marine and fluvial origin, predominantly silts and clays.  No borehole information is available from Fung Lok Wai itself, but investigations elsewhere indicate that lenses of sands and gravels of alluvial origin may occur underneath the surface estuarine deposits (see Townland et al. 1992).

13.2.12   The soils of Fung Lok Wai are derived from mangrove soils and ultimately have their origin as marine sediment and riverine alluvium. Texturally the soils are dominated by silt and clay fractions, the relative proportions of which produce soils that vary from clay through silty clay to silty clay loam (USDA texture classes).  Sand content is generally low. Very small amounts of gravel are present. The soils have been considerably reworked during reclamation and through management for fish-farming.

13.2.13   Soil samples taken in January 1996 were slightly acidic, with a mean pH of 6.8. The soils are poorly drained and frequently highly saline, rendering them of little agricultural value.

Topography, Hydrology and Watercourses

13.2.14   The site has an open, flat and low lying aspect. The major variation in site level is due to the excavation of the fishponds and creation of bunds. The level on top of the aquaculture pond bunds vary from approximately +3.1 m to +3.3 m PD, at the north and east of the site, to about +4.2 m PD at the south.

13.2.15   Water for the fishponds comes from direct rainfall. During winter and when ponds are drawn down, water is pumped from one pond to another to conserve resources. After heavy summer rainfall, ponds may fill and drain into adjacent channels. Channels may also occasionally be used for transferring water, by pump, between fishponds.

13.2.16   No flow data are currently available for the drainage channels. However, a site inspection on 10th January 1998 revealed that all channels contained shallow water (c. 10 cm) and that there were low flows from those draining catchments the adjacent catchments to the south.

13.2.17   The mangrove lined channel (Tai River outfall) at the north-western perimeter of the site is intertidal.  The perimeter bunds are approximately +3.8 mPD and higher than the predicted mean high water in the channel (+2.4 m PD). Therefore in normal circumstances the interior of the site remains free of tidal influence. Overtopping of the perimeter might occur in an extreme combined high tide and storm event. However, this is likely to be extremely rare given the past extreme sea levels at nearby Tsim Bei Tsui which peaked at +3.85 mPD with a return period of 100 years for records between 1974 and 1990. The predicted tidal range for 2002 at Tsim Bei Tsui is 0-3 mPD with an average peak tide of +2.4 mPD.

Water Quality

13.2.18   The results of water quality sampling in the fishponds at Fung Lok Wai undertaken in May 2002 (ALS Technichem (HK) Pty Ltd) are shown in Table 13‑1 below. These data suggest that water quality in the ponds is in accordance with the following AFCD (1995) recommendations for fishponds: pH 6 - 8.5; dissolved oxygen > 1 mg/l; salinity < 2 mg/l. 

13.2.19   Dissolved oxygen concentrations, often regarded as the most important measure of water quality, are high in all of the ponds measured, with the exception of Ponds 56 and 62 (see Figure 13‑1 for locations). High oxygen saturation levels are perhaps not surprising given the widespread use of pond aerators by the fish farmers.

13.2.20   No data are currently available on the quality of water in the existing watercourses. However, all the catchments are dominated by dense semi-natural scrub and woodland vegetation and there are no apparent point sources of pollutants such as pig farms etc. It is therefore expected that the water entering the site is likely to be of relatively low nutrient status and with a low Biological Oxygen Demand (BOD). It is also anticipated that suspended silt in runoff during heavy rainfall periods is likely to be relatively low due to the existing dense vegetation cover in the catchments. Further analysis of water quality survey results can be found within the Water Quality Impact Assessment chapter of this EIA report.

 

Table 131       Results of Water Quality Monitoring in Fishponds at Fung Lok Wai (May 2002)

 

Sampled Fish Pond

River water Sampling Stations

Parameters

Pond 2

Pond 13

Pond 19

Pond 56

Pond 59

Pond 62

W1 (Shan Pui River)

W2 (Tai River)

pH

6.2

7.7

9.3

6.9

8.9

7.0

7.8

7.5

Conductivity (uS/cm)

2510

1860

635

1640

1100

1100

16500

21500

D.O. (mg/L)

5.4

4.4

7.2

2.6

8.2

2.4

3.1

2.1

% Saturation of D.O. (%)

72.5

62.2

98.1

38.5

108

28.1

41.7

28.7

Temp. (oC)

31.3

31.0

30.4

30.7

32.5

30.5

30.0

29.0

Salinity (mg/L)

1.1

0.5

0.3

0.7

0.5

0.5

8.8

11.9

Turbidity (NTU)

45.2

30.7

23.1

63.3

23.5

42.4

12.7

20.0

SS (mg/L)

72.7

57.0

28.3

93.7

47.0

49.7

32.3

26.3

Ammonia as N (mg/L)

0.03

0.03

0.04

2.96

0.07

0.39

5.4

2.8

Nitrate as N (mg/L)

<0.01

<0.01

<0.01

0.04

0.04

0.23

0.6

0.7

Nitrite + Nitrate as N (mg/L)

0.02

0.02

0.02

0.16

0.17

0.31

0.9

1.2

Total Kjeldahl Nitrogen as N (mg/L)

3.2

2.9

3.9

4.6

3.3

3.6

7.3

3.1

Total Nitrogen (mg/L)

3.2

2.9

3.9

4.8

3.5

3.9

8.2

4.3

Total Phosphorus (mg/L)

0.2

0.2

0.2

0.2

0.2

0.3

0.7

0.5

Reactive Phosphorus as P (mg/L)

0.03

0.03

0.02

0.02

0.03

0.02

0.6

0.4

BOD (mg/L)

10.0

8.7

14.3

5.3

9.0

4.7

3.0

<2

 

13.3          Literature Review

13.3.1      In order to identify key ecological resources and issues, relevant reports and scientific papers have been reviewed below. A key objective of this review is to identify important information gaps and appropriate strategies for additional data gathering. In particular, the results of species and habitats surveys undertaken at Fung Lok Wai between 1994 and 1998 are drawn upon, (Mutual Luck Investment Limited 1998). 

13.3.2      A full list of documents referenced during the preparation of this EcIA is included in Section 13.12. However, the following documents are particularly relevant to this assessment:

·        Bats of Hong Kong. World Wide Fund for Nature, Hong Kong. Ades, (1990).

·        Classification system for wetland type, Ramsar Bureau. www.ramsar.org

·        Development of a comprehensive conservation strategy and a management plan in relation to the listing of Mai Po and Inner Deep Bay as a Wetland of International Importance under the Ramsar Convention.  Agreement No. CE47/95. Aspinwall Clouston & Wetlands International – Asia Pacific (1997).

·        Ecological impact study of proposed development at Pak Hok Chau, Mai Po. Unpublished report. Anon. (1993).

·        Ecological study on mangrove stands in Hong Kong. Report submitted to AFD, Hong Kong SAR. Tam, N.F.Y. & Wong Y. (1997).

·        Environmental Impact Assessment: Towards Guidelines of Adoption under the Ramsar Convention. Technical Session A of the 6th meeting of the conference if the contracting parties, Brisbane, March 1996. Pritchard, D. E. (1996)

·        Fish Ponds in the Ecology of the Inner Deep Bay Wetlands of Hong Kong. Asian Journal of Environmental Management. Vol 3, No. 1, pp13-36. Chu, W. H. (1995)

·        Guidelines for application for developments within Deep Bay Area under section 16 of the Town Planning Ordinance. TPB PG-No. 12B. Town Planning Board (1999)

·        Hong Kong International Wetland Park and Visitor Centre Feasibility Study – Preliminary Environmental Review.  Hong Kong Tourist Association. Binnie Black and Veatch (1999).

·        Objection to Draft Lau Fau Shan & Tsim Bei Tsui Outline Zoning Plan No. S/YL-LFS/1 – Alternative Proposal. Volume 1 and 2. Mutual Luck Investment Limited (1998).

·        Pilot project to develop a long-term strategy for the conservation of fish pond farming within the Mai Po and Inner Deep Bay Ramsar Site.  Funded by the Conservation Foundation Fund, Hong Kong. World Wide Fund for Nature (2003)

·        Ramsar Site Waterfowl Monitoring Programme, Hong Kong Bird Watching Society. Carey, G. (unpublished).

·        Reconnaissance survey of benthic and pelagic fish pond fauna at Fung Lok Wai.  Prepared for Mutual Luck Investment Limited. Binnie Consultants Limited (1997a).

·        Sheung Shui to Lok Ma Chau Spur Line Environmental Impact Assessment. Binnie Black and Veatch 2000.

·        Study on the Ecological Value of fish Ponds in Deep Bay Area: Executive Summary. Planning Department, Hong Kong SAR Government. Aspinwall & Company Hong Kong Limited (1997).

·        Sunnyville Estate development at Nam Sang Wai, Engineering Assessment Report, Nam Sang Wai Development Co, Ltd & Kleener Investment Ltd. Townland Consultants Ltd, Wong Tung & Partners Ltd, Maunsell Consultants Asia Ltd, MVA Asia Ltd, CES Asia Ltd, Belt Collins & Associates HK ltd, Nelson and Wright (1992).

·        The Avifauna of Hong Kong.  Hong Kong Bird Watching Society, Hong Kong. Carey, G.J. et al. (2001).

·        The importance to ardeids of the Deep Bay fishponds, Hong Kong. Biological Conservation. 84 (3): 293-300. Young, L.(1998).

·        The significance of drained fishponds for wintering waterbirds at the Mai Po Marshes, Hong Kong. IBIS, 139 (4): 694-698. Young, L. (1997).

·        Tin Shui Wai Development Engineering Investigations for Development of Area 3, 30 & 31 of the Development Zone and the Reserve Zone – Environmental Impact Assessment - Final Assessment Report.  Volumes 1 and 2, February 1997.  Territory Development Department, Agreement No. CE 10/95. Binnie Consultants Limited (1997b).

·        Various issues of Porcupine! Newsletter of the Department of Ecology and Biodiversity, Hong Kong University.

·        Wild Animals to Watch:  Terrestrial and freshwater fauna of conservation concern in Hong Kong.  Memoirs of the Hong Kong Natural History Society. Fellowes, J.R et al. (in 2002).

·        In formation about the wildlife of Mai Po Marshes available at http://www.wwf.org.hk/eng/maipo/wildlife/habitats.html

·        Yuen Long Bypass Floodway Feasibility Study Environmental Impact Assessment Binnie Consultants Limited (1998).

·        Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 1 Sewers, Rising Mains and Ancillary Pumping Stations: Environmental Impact Assessment and Traffic Impact Assessment Studies. Environmental Impact Assessment (Designated Elements) Final Report. ERM (May 2002).

 

13.4          Review of Recognised Sites of Conservation Importance in the Vicinity of Fung Lok Wai

13.4.1      The location of the proposed development in relation to existing protected areas of high ecological value is indicated in Figure 13‑2. The northern boundary of the Assessment Area adjoins the Inner Deep Bay Site of Special Scientific Interest (SSSI) and the northern half of the Assessment Area lies within the boundary of the Mai Po Inner Deep Bay Ramsar Site (a Wetland of International Importance under the Ramsar Convention).  The Deep Bay area comprises natural and man-made wetlands (rivers, freshwater marshes, fishponds, gei wais (tidal shrimp ponds), mangroves, inter-tidal mudflats and the bay) which provide a wide range of habitats that support a high diversity of biota (plants, insects, reptiles, amphibians, birds, fish and mammals). To the north east is Tsim Bei Tsui Egretry SSSI and to the west beyond the Shan Pui River is Mai Po Nature Reserve and Mai Po Marshes SSSI.

13.4.2      The Mai Po Inner Deep Bay Ramsar site is particularly important for waterbirds, including a number of globally threatened species (Collar et al. 1994), species which regularly have high proportions of their global or biogeographical wintering or passage populations within the site and species that are of regional or local conservation importance. Deep Bay is also important for a wide range of other migratory water birds, many of which are listed for protection under the Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention) of which the People’s Republic of China is a party.

13.4.3      The Town Planning Board has adopted a “precautionary approach” to development in the Deep Bay area in view of the known intrinsic value of fishponds in ecological terms, and the complex response of birds to future land use changes which has not been fully understood (Town Planning Board 1999). The intention is to protect and conserve the existing ecological function of fishponds in order to maintain the ecological integrity of the Deep Bay wetland ecosystem as a whole. This “precautionary approach” is formulated with the support of scientific surveys and analysis as provided in the Study on the Ecological Value of Fish Ponds in the Deep Bay Area (Aspinwall Clouston & Wetlands International - Asia Pacific, 1997).

13.4.4      The Wetland Conservation Area (WCA) forms the core wetland area of Inner Deep Bay between Tin Shui Wai in the west and the Lok Ma Chau Boundary Crossing in the east and has been designated for all continuous and adjoining fishponds within this area, including those within the study site.  The intention of the WCA designation is to conserve the ecological value of fishponds which form and integral part of the wetland ecosystem in the Deep Bay Area. A Wetland Buffer Area (WBA) of 500m to the landward side of the WCA has also been designated to protect the ecological integrity of the WCA.

13.4.5      In considering development proposals in the Deep Bay Area, the Town Planning Board adopts the Fish Pond Study’s recommended principle of “no-net-loss in wetland” which provides for the conservation of continuous and adjoining fishponds. The no-net-loss can refer to both loss in “area” and in “function”. Wetland compensation is required for any development requiring pond filling and mitigation measures against disturbance are also required.

13.4.6      Management zonation has been developed for the Mai Po Inner Deep Bay Ramsar Site as part of its Comprehensive Conservation Strategy and Management Plan (Aspinwall Clouston and Wetlands International 1997). The areas within the Ramsar boundary to the west, north and east of the site have been identified as Public Access Zones. According to the Strategy, “the purpose of the Public Access Zones is to enable people to have unrestricted (but managed) access to a part of the Ramsar site in order to appreciate its special value and enjoy contact with wildlife. In addition it provides opportunities for: public education, raising public awareness of the conservation values of the site, particularly as they relate to the Ramsar criteria values and biodiversity values; and quiet recreation relevant to the aforementioned values”. The area of the Fung Lok Wai site within the Ramsar boundary was not included in the Public Access Zone as the Strategy did not propose management zones for privately owned land.

Habitats

13.4.7      As described in Section 13.2 Deep Bay was originally dominated by a complex of natural wetland habitats, including inter-tidal mudflats, mangroves and brackish and freshwater marshland. This century large areas of these inter-tidal habitats have been reclaimed and other wetlands drained, infilled or converted to artificial gai wais or fish pond habitats. Consequently, only small areas of natural and semi-natural wetlands remain in the Deep Bay area, mainly around Ma Tso Lung.

13.4.8      These changes in habitats will have had profound impacts on the distribution and abundance of many species that were originally associated with these natural wetland habitats. Although data are not available to assess the longer-term impacts, it is generally accepted that many wetland species that are currently rare or no longer occur in Hong Kong formerly commonly occurred in the Deep Bay area.

13.4.9      The remaining areas of wetland habitats are of local and regional importance in their own right. The mangrove forests at Mai Po together with those in the other parts of Deep Bay cover an area of some 400 ha and are the sixth largest protected stand remaining in China. Mangroves provide important habitats for wildlife but in Hong Kong most other stands are relatively small and subject to frequent human disturbance (Tam & Wong 1997). Reedbeds at Mai Po represent greater than 80% of all reedbed habitat in Hong Kong are one of the largest remaining areas known in Guangdong Province and 240 ha of traditionally operated shrimp ponds represent one of the largest areas of this habitat left in southern China (WWF 2000).

13.4.10   Despite the loss of areas of natural and semi-natural wetlands to artificial habitats some of the more recent changes are likely to have had beneficial effects for some species. In particular, it is likely that the high productivity of the fish farming systems and the availability of abundant food during fish harvesting periods has maintained or increased populations of many water birds, including cormorants, herons and egrets.  The value of fishponds to some specific groups, in particular to birds, has been well studied (see below), although a comprehensive assessment of the importance of different habitat types in the area of Inner Deep Bay, to different species groups, has yet to be undertaken.

13.4.11   Chu (1995) undertook a review of the ecological surveys carried out for five planning applications within the Deep Bay area to assess the relative importance of fishponds and associated habitats for wildlife. The review demonstrates that fish pond areas can support a number of protected species and are an important habitat for resident ardeids and migrant birds. In addition, summaries of species known to be associated with fishponds have been produced (Ades et al. 1995). These summaries indicate that fishponds within the Deep Bay area, although artificial, are an integral part of the Deep Bay wetland ecosystem.

Vegetation

13.4.12   Approximately 120 terrestrial plant species have been recorded from the Deep Bay aquaculture pond bunds (Chau, unpublished data). However, most of these are common and widespread species (Ades et al. 1995).

13.4.13   Surveys of the vegetation around the fishponds at Fung Lok Wai were undertaken on 9th November 1994, 28th February 1995 and 16th May 1996. Additional species recorded during the course of other visits to the site were also added to the plant species list. All plant species encountered whilst walking the bunds were recorded, with an estimate made of their abundance within the site.

13.4.14   Areas of mangrove vegetation occurred immediately outside the site but none were found within its bounds. A small population of the mangrove fern Acrostichum aureum was, however, found in a drainage ditch in the western part of the site.

13.4.15   The bund vegetation at Fung Lok Wai during this survey consisted predominantly of coarse grassland, composed of common grasses and herbs. The vegetation is subject to frequent disturbance in the form of cutting, burning, rubbish dumping and, when the ponds are reformed, bulldozing.  As a result of this disturbance ruderal or 'weed' species are a prominent feature, some such as the alien climber Mikania micrantha having spread to form extensive patches. 

13.4.16   The most interesting vegetation community recorded within Fung Lok Wai during these surveys was that associated with the drainage ditches. Apart from supporting predominantly alien trees and shrubs on their banks, the drainage ditches also supported elements of wetland vegetation. This ranged from areas of dense reed Phragmites communis and low scrub of Marsh Fleabane Pluchea indica to open marsh vegetation of Cyperus sedge and other marginal/emergent species. The relatively undisturbed nature and dense vegetation found in many of these ditches provide cover for wildlife.

13.4.17   A total of 76 plants species were recorded during these surveys. No unusual or rare plant species were encountered.

Invertebrates

13.4.18   A survey of invertebrates present in seven fishponds exhibiting a range of conditions was carried out on 4th and 9th November and 21st December 1994. Invertebrate species richness was found to be very low in all of the surveyed ponds. The fauna of mature and recently drained ponds was typically dominated by freshwater shrimps, almost exclusively belonging to the genus Palaemon. Pelagic insects were very scarce, with only a few backswimmers (Notonecta sp.) being encountered in one of the ponds.

13.4.19   Shrimp were not detected in recently re-filled ponds. Some of these ponds did, however, support large numbers of non-biting midges (Chironomidae). Adult Chironomids were seen emerging in abundance from a recently re-profiled and filled pond.  Exuviae collected from this pond were identified by Dr M. Learner, University College, Cardiff, as belonging to three genera - Einfeldia, Chironomus and Nilodorum (Einfeldia being the most abundant).

13.4.20   Sieve sampling of bottom muds in a re-profiled and re-filled pond, revealed the presence of large numbers of benthic Chironomid larvae.  These were present in sediments c. 1 metre below the water surface. These were identified as Einfeldia and Chironomus, with the former again the most abundant. Densities of benthic larvae were estimated at approximately 1,800 m-2.  Gelatinous egg masses, also belonging to chironomids, were found around the margins of recently re-filled ponds, attached to clumps of clay just below the water surface. 

13.4.21   A further study of three ponds at Fung Lok Wai in March 1997 also confirmed that Chironomid larvae are the predominant benthic species present, followed by tubificid worms (Binnie Consultants Limited 1997b). In total only 14 benthic taxa were recorded.

13.4.22   Searches of micro-habitats around the margins of ponds revealed a number of crabs (Varuna litterata).

13.4.23   30% of all dragonfly species recorded in Hong Kong can commonly be encountered around managed fishponds. Most of these are generalists which prefer static conditions and, in comparison to natural ponds and lakes, managed fishponds support a reduced number of dragonfly species (Wilson 1995a & b).  Two species of dragonfly and damselfly of conservation interest have been recorded with the Deep Bay area though not within the Assessment Area of Fung Lok Wai, Orthetrum poecilops poecilops and Mortonagrion hirosei.  Orthetrum poecilops poecilops is normally associated with woodland.  Mortonagrion hirosei is usually confined to dense Phragmites reed beds, so both are unlikely to occur within the Study Site.

13.4.24   Invertebrate surveys of bund habitats were undertaken within three sampling areas of aquaculture ponds within the Deep Bay area as part of the Fishpond Study (Aspinwall Clouston & Wetlands International – Asia Pacific 1997). The results of the survey indicate that the ponds support an impoverished and very simple aquatic invertebrate community. Freshwater shrimps are the predominant group. Present in large numbers, they are an important food source for herons and egrets.

13.4.25   Aquatic insects are generally quite scarce, except for Chironomid midges that were found in some abundance in recently re-filled ponds. These insects are also important food sources for birds, including Chinese Pond Herons and migratory passerines such as Acrocephalus warblers. The results indicated that 46% of all invertebrates recorded were Chironomid midges, with Hemiptera, Arachnida and other Diptera making up a further 42% of all records. Total biomass peaked in spring. The greatest species group diversity occurred within the scrub areas, though only by small margin; grassland areas supported the greatest biomass and reedbeds the greatest density. All site surveys were dominated by Diptera.

13.4.26   These findings are in broad agreement with studies at Pak Hok Chau (fishponds near Mai Po Nature Reserve), which found a low diversity of species overall, but with large numbers of a few species (principally flying insects such as Chironomids) at certain periods, notably during spring and autumn (Anon. 1993). 

Fish

13.4.27   The fishponds are actively used for the polyculture of freshwater fish, and therefore contain high densities of various commercially stocked species (including Big Head Carp Aristichths nobilis, Grass Carp Ctenopharyngodon idellus, Common Carp Cyprinus carpio, Grey Mullet Mugil cephalus and Tilapia spp.). In addition high numbers of various non-commercial species are likely to occur, including Mosquito Fish Gambusia patruelis.

Amphibians

13.4.28   Eight species of amphibians, a third of the native Hong Kong amphibian fauna, have been recorded from fishponds in the Deep Bay area (Lau 1995). However, predation of tadpoles by fish and the slightly saline water make the fishponds at Fung Lok Wai unsuitable habitats for most amphibians and only Guenther's frog Rana guentheri are known to breed in the ponds.

13.4.29   Five species of amphibian were found off site at the nearby Tin Shui Wai Reserve Zone (Binnie Consultants Ltd 1997a). However, only Guenther’s frog and Asiatic toad Bufo asiatica, both common and widespread species, were recorded at Fung Lok Wai at this time.

Reptiles

13.4.30   In total 16 species of reptiles have been recorded from the fishponds in the Deep Bay area including five species of reptile of conservation importance which are known to occur within the north-west New Territories, Chinese Soft-shelled Turtle Pelodiscus sinensis, Chinese Three-keeled Pond Turtle Chinemys reevesii, Burmese Python Python molurus, Chinese Cobra (Naja atra) and Copperhead Racer Elaphe radiata. Of these Chinese Soft-shelled Turtle, Chinese Three-keeled Pond Turtle and Burmese Python are protected under Schedule 2 of the Hong Kong SAR Wild Animals Protection Ordinance. These three species are also recorded on the IUCN list of globally threatened species.  Chinese Soft-shelled Turtle and Chinese Three-keeled Pond Turtle prefer reservoir and pond habitats with soft sediments and so could occur within the habitats of Fung Lok Wai, however the distribution of Chinese Soft-shelled turtle is localised. Burmese Python is unlikely to utilise the fishpond habitats of the Study Area preferring instead scrubby and mangrove habitats.

13.4.31   Although a comprehensive reptile survey was not carried out at Fung Lok Wai as part of the original proposal, the following species were recorded: Chinese water snake Enhydris chinensis (juvenile found under sacking on edge of pond 7) and common rat snake Ptyas mucosus (discarded skin found on bund between pond 21 & 22). In addition, checkered keelback snake Xenochrophis piscator, Bowring's gecko Hemidactylus bowringii, many-banded krait Bungarus multicinctus, common rat snake Ptyas mucosus and three keeled pond turtle have been recorded nearby, and are therefore likely to occur on site. In general the regular disturbance to aquaculture ponds associated with the intensive fish farming at Fung Lok Wai is likely to limit opportunities for reptile populations to become well established.

Birds

13.4.32   Of all species groups, birds have been the subject of most studies and surveys of the fishponds of the Deep Bay area. These include feeding studies by Melville (1987), Wong (1991), Britton (1993) and Young (1993). Further ecological appraisals have been made on the use of fishponds by birds by Melville et al. (1994) and Chu (1995). A detailed assessment of the use of fishponds by birds was completed as part of a Fish Pond Study by the Planning Department in 1997 whose specific aim was to assess the ecological value of fishponds within the Deep Bay area.

13.4.33   Fish ponds are used by a wide range of waterbirds, land birds associated with bund vegetation and birds feeding aerially on insects above the water. These include a wide range of raptors, waders, gulls, terns and passerines. Ponds are used by different species at different times of the year, a large proportion of which occur in high numbers in the Deep Bay area. In fact the similarity in the bird community composition at Mai Po Nature Reserve and the fishponds suggests that they should be treated as an integrated unit because birds regularly move between the two. Overall, it is understood that the fishponds provide habitat for half the number of waterbirds found at Mai Po and 10% of the number of the entire Deep Bay area, though proportionately more egrets, herons and cormorants, use fishponds than the other habitats within Deep Bay (Aspinwall Clouston and Wetlands International 1997).

13.4.34   Wintering bird data collected by the Hong Kong Bird Watching Society (HKBWS) since 1979 indicate there has been a significant increase in total waterfowl using the Deep Bay Area in Hong Kong (Carey et al. 2001) and in total numbers of herons and egrets, ducks, waders and cormorants (Aspinwall Clouston and Wetlands International 1997). However, numbers at Mai Po and Futian (on the northern shore of Deep Bay, in mainland China) have remained relatively constant, suggesting that the current carrying capacity of these sites has been reached.

13.4.35   The increase in herons and egret populations in winter is due to birds using both Deep Bay itself and the wider fish pond habitats throughout the bird count areas. This increase in use is most likely due to a decrease in persecution of breeding individuals, an increase in food supplies in the breeding and wintering period, and the loss of habitats outside Deep Bay.

13.4.36   Winter population increases in ducks is most likely the result of increased prey biomass in the Deep Bay mudflats, due to organic enrichment, increases in total flyway populations and habitat loss elsewhere in the region. Similarly wader populations have probably benefited from the organic enrichment of the mudflats, as well as an increased provision of high tide roosts within Deep Bay and associated habitats at Mai Po. Increased observer coverage may also account to some extent for the increase in numbers counted.

13.4.37   Comprehensive surveys of the birds occurring at the Fung Lok Wai site were undertaken between 2nd December 1993 and 27th November 1997. A total of 100 species of birds were recorded at Fung Lok Wai over the course of the surveys. Although many of the birds recorded do not visit the site regularly; at least 33 regularly occur, including ubiquitous species like tree sparrow and Chinese Bulbul and those, like Chinese Pond Heron, Little Egret and Common Kingfisher, which regularly feed around ponds. Of the regular species, 19 (58%) could be reasonably described as wetland birds including some of conservation importance, such as Little Egret, Cattle Egret and Chinese Pond Heron. However, the number and diversity of several waterbird groups such as Snipe, rails, crakes and reedbed passerines appeared to be low, probably as a result of the intensive management of fishponds and consequent lack of emergent vegetation. 

13.4.38   A specific review of the effects developments may have on egretry sites has been completed as a separate report (AEC 2002). Evaluation of the current bird interest at the site is described in section 13.5 below.

Mammals

13.4.39   Eleven mammal species have been recorded from aquaculture ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds) and vegetation at the nearby Mai Po marshes (Ades et al. 1995). In particular the Chinese Otter which was considered extinct in Hong Kong until its rediscovery in 1990 at Mai Po. A detailed survey of mammals occurring at Fung Lok Wai was not undertaken during documented previous surveys and the only mammals noted during site visits were brown rat Rattus norvegicus and Japanese pipistrelle bat Pipistrellus abramus. In addition, house shrew Suncus murinus and house mouse Mus musculus would also be expected to occur.  Crab eating mongoose Herpestes urva has also been seen off site, in nearby mangrove and Melville (1991) has predicted that small Indian civet Vivericula indica and leopard cat Felis bengalensis could occur at nearby Nam Sang Wai.

13.4.40   Documents associated with EIAs prepared for previous development proposals in the Deep Bay Area were reviewed but provided little additional information on mammalian fauna of the area. In general though, the disturbance from the intensive fish pond management and lack of vegetation cover at Fung Lok Wai is likely to make the site unsuitable for most larger mammals.

Summary of Key Information Gaps

13.4.41   No habitat or species survey data reviewed were found to be up to date, comprehensive or covering the complete Assessment Area as required by the Study Brief. A comprehensive suite of surveys were therefore proposed for all habitats, aquatic invertebrates, terrestrial invertebrates known to have some association with the habitats occurring at the site, wild freshwater fish, amphibians, reptiles, birds and mammals.

13.4.42   The information gained from the review of existing information above will be utilised along with the data obtained from recent surveys to identify, predict and evaluate impacts and formulate appropriate mitigation measures and monitoring for the site.

 

13.5          Field Survey Methodology

13.5.1      The field survey methodology utilised for this EcIA follows the general principles outlined in Annex 16 of the Technical Memorandum to the EIA Ordinance and aims to provide adequate and accurate baseline survey information of the proposed development and its vicinity, with respect to the ecological importance of flora, fauna and habitats found. Section 6.8 of the Town Planning Board planning guidelines TPB PG-No. 12B (Town Planning Board 1999) stipulates that for development proposed within or encroaching either the WBA or WCA, baseline surveys should be undertaken over twelve consecutive months to establish the existing wildlife habitats and flora and fauna present and any seasonal changes.

13.5.2      The baseline habitat and ecological surveys for the study site commenced on the 10/1/2001 and were completed on 3/1/2002. The surveys were conducted by qualified, professional ecologists with at least three years relevant expertise in surveying their respective taxa groups in Hong Kong and South China.

13.5.3      Since completion of the surveys there has been no change in wetland area, there has been no in-filling of fish ponds, for example. There has, however, been a change in management of fish ponds. Site visits undertaken in recent years, including by WWF staff in October 2006 and May 2008, indicate that relatively few ponds (about one quarter) are now in active production (Janet Lee, Pers. Comm.). For abandoned ponds, grass has encroached into the open water from the side of the ponds and Water Hyacinth (Eichhornia crassipes) is abundant in some cases. In the absence of active management, bunds have become covered by long grass which reduces their attractiveness as roosting sites for waterbirds.

13.5.4      As the extent of wetland has not changed it is considered that the importance of the site for most species, including birds that are not dependent on the active fishpond management (eg Red-billed Starling) and non-avian fauna (such as reptiles) will be unchanged. For those birds that are dependent on the active management of fish ponds (including egrets and Black-faced Spoonbill) it is expected that the importance of the site will have declined.

13.5.5      To determine whether there have been changes within the wider north-west New Territories in the abundance of key bird Species of Conservation Importance, an analysis of bird records within the Deep Bay area has been undertaken (Appendix 13-12). This analysis includes a comparison of recent records within a recording area that includes Fung Lok Wai with data for the wider Deep Bay area. It indicates that there is no significant change in the importance of Fung Lok Wai for Species of Conservation Importance since the conclusion of the baseline surveys and that, for key species (egrets and Black-faced Spoonbill) there appears to be a loss of value.

13.5.6      It is considered that the results of these surveys remain applicable to the assessment. Any changes taking in place in the intervening period involving a reduction in ecological value due to a reduction in fish farming activity. There is evidence that this had most effect on key bird species of interest such as egrets and Black-faced Spoonbill that typically benefit most from aquaculture activities that periodically provide access to food resources.

Habitats

13.5.7      Aerial photograph of the study site supplied by the Lands Department (CN27931, 10/8/2000) was used to delineate the boundaries of the different natural and artificial habitats present within the Assessment Area.  The boundaries of each habitat type were transcribed onto a 1:5000 scaled map and ground-truthed on subsequent site visits. Representative colour photographs were taken of each habitat. Wetland habitat types were classified according to the ‘Ramsar Classification System for Wetlands’ (Appendix 13.1) and terrestrial habitats were classified on the basis of the structural characteristics of the dominant vegetation present. The completed habitat map was digitised into MapInfo V.6.

13.5.8      The total area in hectares (ha) and percentage coverage of each habitat type present within the Assessment Area was calculated using a Lands Department digital topographic base map of the site which was ground-truthed and geocoded.

Vegetation

13.5.9      Following production of the habitat map habitat surveys were undertaken by a suitably qualified botanist.

13.5.10   Each habitat within the Assessment Area was inspected and a species list and a semi-quantitative estimate of abundance recorded.

13.5.11   More detailed quantitative surveys to determine species composition were undertaken within those habitats present within the Study Site during both wet and dry seasons. Within each of these habitats, ten randomly distributed 1m2 fixed quadrats were surveyed. Quadrat locations were permanently marked to enable resurvey and hence direct comparison between seasons. The data were recorded as percentage cover of each species identified within three growth layers. In addition, notes were made of:

·        Vegetation structure

·        Dominant plant species

·        Condition

·        Presence of any specific features of ecological significance

13.5.12   Quadrat locations are identified in Figure 13‑3.

Invertebrates

Aquatic Invertebrates

13.5.13   The aquatic invertebrate community was sampled at a total of nine locations across the site using a combination of three survey techniques to enable all major aquatic biomes to be sampled. Aquatic sampling locations are shown in Figure 13‑4. 

13.5.14   Permanent watercourses were surveyed using pond net and kick sampling during the wet season in August 2001 and repeated again during the dry season in December 2001, using the same sampling locations in both seasons to gain a representative sample of the aquatic invertebrate community during both periods. 

13.5.15   Fishponds were surveyed using pond net and benthic core sampling again during both the wet and dry seasons.

13.5.16   Pond net – Sweep net sampling was conducted within the study site to assess the species composition and abundance of aquatic species that inhabit the water column and cling to submerged vegetation present in the permanent streams.  A D-shaped sampling net 30 cm in diameter comprising 1 mm mesh was used. Each sample comprised two 2-metre sweeps of the net.  The first sweep was conducted through the mid water column, whilst the second sweep was passed over the bed of the watercourse.  For each sample site the replicate samples were combined, preserved and stored. 

13.5.17   Three permanent watercourses present within the study site were surveyed. Three random samples were being taken at each sampling location.

13.5.18   Six fishponds were sampled across the study site with five random samples being taken within each pond along the water/bund interface. A larger sample size was used during the survey of aquatic invertebrates in the fishponds, as these represent a significantly larger area of the study site.

13.5.19   Kick net – Kick net sampling was used to sample the macro-invertebrates that inhabit the soft substrate of the streambed.  A kick net of the following dimensions: height = 0.25m, width = 0.3m, length = 0.5m and a mesh size of 1mm was used.  The flat base of the kick net was placed on the stream bed and held securely. The open mouth of the net was placed facing upstream. A surveyor kicked a 1m2 area of substrate on the stream bed, directly upstream of the net, ten times to dislodge macro-invertebrates inhabiting the sediment. Any invertebrates caught in the net were removed and preserved in 70% alcohol for later identification.

13.5.20   In the laboratory each sample was rinsed onto a 500 micron fine mesh sieve to remove sediment particles. The washed samples were sorted into species groups. Specimens of target taxonomic groups were identified to family level using a binocular microscope, and the number and biomass (dry weight, including shell in the case of molluscs) of each family represented was quantified. The target species groups include: Coleoptera: beetles, Crustaceans: crabs, shrimps, Diptera: chironomids, psychodids, Ephemeroptera: mayflies, Heteroptera: water bugs, Hirundinea: leeches, Mollusca: shellfish, Tipulids: craneflies, Trichoptera: caddisflies. Species for other taxa groups were recorded and counted, but not weighed. The number and species of any fish incidentally captured during the sampling was also recorded.

13.5.21   Two permanent watercourses were sampled using kick netting. This method is inappropriate for sampling closed waterbodies with no flow current, so a different method, benthic core sampling, was used to survey the benthic invertebrate community within the fishponds.

13.5.22   Cylindrical benthic cores – Benthic cores were taken from six fishponds within the study site to identify the species composition and abundance of freshwater invertebrates that inhabit the soft substrate along the shallow aquatic margins of the ponds. This sampling method was used to assess the value of the current fishpond margins to waterbirds.  The fishponds were sampled once during the wet season in August 2001 and resurveyed during the dry season in December 2001.

13.5.23   Cylindrical benthic cores 10cm in diameter and 20cm in length were inserted into the submerged sediment to a depth of 10cm, rotated and gently removed.  Six randomly located replicate cores were collected from each pond.

13.5.24   The contents of each core were immediately removed and preserved in 70% ethanol. Back in the laboratory each core was washed on a 500 micron fine mesh sieve to remove all sediment particles.  Invertebrates were identified to family level under a binocular microscope.  The number and biomass (dry weight, including shells in the case of gastropods) of individuals in each target taxonomic group was quantified, as for the kick-net sampling. Species from other taxa groups were recorded and counted, but not weighed.

Dragonflies

13.5.25   Dragonflies were surveyed by a suitable qualified ecologist along the set transect routes T1-T10 (Figure 13‑5). Dragonflies were surveyed twice per month during May, June, September and October 2001, and once per month in April, July, August and November 2001.

13.5.26   Each survey commenced at the beginning of transect T1. The surveyor walked along the entire length of each of the transects T1 to T10 in sequential order at a uniform pace.  All butterflies and dragonflies identified in front of and within 5 metres either the side of each transverse (but not behind) the surveyor were recorded. Where feasible the number of male and female dragonflies observed were recorded for each species. Where large swarms of dragonflies were encountered an estimate was made of the approximate number of dragonflies present.

13.5.27   Counts were conducted between 10:00 and 16:00 hours during optimum weather conditions that comprise dry weather with an air temperature of above 17oC in the shade, with at least 50% sunshine and light wind conditions.

Butterflies

13.5.28   Butterflies were surveyed concurrently with dragonflies, following the transect survey methodology and schedule detailed above (refer to Figure 13‑5 for transect routes). The survey schedule takes advantage of peak butterfly activity that occurs in Hong Kong during May to June and September to October. 

Fish

13.5.29   The irrigation ditches present within the study site were surveyed for fish during May 2001. The sampling locations are shown in Figure 13‑6.  A 1cm mesh net was placed across the narrowest section of the drainage ditch.  The surveyor subsequently walked downstream with exaggerated movements to direct the fish into the net. Fish disturbed were collected using hand nets and identified on site.

13.5.30   Bankside observations were also carried out at locations along the drainage ditch where the water was too deep to carry out efficient sampling.  This survey method was also used in shallow, slow-flowing waters with limited instream or backside vegetation where fish could easily be seen.

13.5.31   The species of fish and their abundance were recorded. All individuals collected for identification were released at the place of capture as soon as possible. Specimens for which identification was uncertain were kept temporarily in fish tanks pending taxonomic verification; once identified, the specimens were released at their point of capture. 

Amphibians

13.5.32   Amphibians were surveyed along set transects T1 – T10 within the study site (Figure 13‑5). Monthly amphibian surveys were undertaken at dusk over two consecutive days between April and October 2001. Incidental sightings of amphibians were also recorded during the daytime surveys for insects and reptiles.

13.5.33   Surveys were conducted for a fixed period from 18:30 to 20:30. The surveyor used a torch light to scan the aquaculture ponds, permanent streams, agriculture fields, reedbed, marsh and pools, and vegetation therein to spot amphibians.  Day light surveys that were conducted along transects T1 to T10 to record reptile, butterflies and dragonflies were conducted for a set time duration from 10:00 to 16:00hrs. 

13.5.34   All amphibians recorded were identified to species level, counted and where possible sexed.

Reptiles

13.5.35   Reptile surveys were undertaken monthly between April and November 2001. The reptile population was surveyed along the same transect route as that used for the dragonfly and butterfly surveys (Figure 13‑5).  Reptiles were surveyed during daytime for a fixed time period of 10:00 – 16:00, during warm sunny weather, which are the optimum climatic conditions for reptiles.  Opportunistic sightings of reptiles were also recorded during the amphibian surveys conducted at the site. 

13.5.36   The surveyor walked along transects at a standard pace and actively searched out reptiles in likely basking spots and retreats (e.g. exposed sunny open patches of ground, abandoned materials, habitat edges, or areas shaded from direct sunlight such as under bushes or shrubs etc) and as far ahead along the transect as possible.  For each reptile seen, the individual was identified to species level and the number of individuals counted recorded for each transect. The surveyor used close focusing binoculars to spot and identify reptiles to species level that were observed in the distance. 

Birds

Transect surveys

13.5.37   The Mai Po Inner Deep Bay Ramsar Site is an important site for migrating and wintering wetland dependent birds. Furthermore, aquaculture ponds are known to be of considerable value as foraging habitat for birds, particularly when they are drained down (Aspinwall, 1997). Consequently significant survey effort was applied to surveying birds within the Assessment Area and a particular focus was placed on gathering information about the usage of specific ponds by birds throughout the year.

13.5.38   The bird survey methodology and data recording format duplicate those adopted by the Ramsar Site Waterfowl Monitoring Programme (Carey, G.J., undated). Each aquaculture pond present within the study site was allocated a unique reference number 1-103 (see Figure 13‑1). Seven set transect routes (T1 – T7) were established to enable surveyors to visit and observe birds within each of the habitat types present (see Figure 13‑7).

13.5.39   Transects T1-T5 which are located within wetland areas and transect T6 which is located in the scrubland, agricultural land, orchard and grassland located within the 500m buffer zone adjacent to the southern part of the study site were surveyed on foot. Transect T7, which encompasses a large area of habitats within the 500m buffer zone was surveyed from a slow moving vehicle that made frequent stops to allow accurate counts to be made. To coincide with peak bird activity, each survey was commenced one hour after dawn. 

Transects T1-T5 and T7

13.5.40   During surveys of these transects all birds were identified to species and associated information, such as weather conditions, habitat type and site condition were recorded on standard survey forms.  Pond management practices and the status of vegetation growing on the bunds were also recorded. The species and abundance of birds observed flying over the study were also recorded if the surveyor was certain that these individuals had not previously been recorded during that particular visit.

13.5.41   Bird surveys were undertaken 2 to 3 times per month from January to December 2001. Aspinwall (1997) identified that waterbirds congregate at drained aquaculture ponds to feed on ‘trash fish’ exposed in shallow water.  To assess the species and abundance of waterbirds that utilise drained ponds transects T1-T5 and T7 were surveyed three times per month during those months when aquaculture ponds were drained down (ie January, February, September, October and November). For the remainder of the year (i.e. March to August) transects T1-T5 and T7 were surveyed twice per month.

Transect 6

13.5.42   Surveys of Transect 6 were particularly focused on passerine species associated with the complex mosaic of habitats present within this southern part of the assessment area. In addition to presence or absence of species, resident status in Hong Kong was assigned according to the following categories (Carey et al., 2001):

·        Breeding resident (R)

·        Passage migrant (M)

·        Spring migrant (SpM)

·        Summer breeding visitor (Su)

·        Autumn migrant (AM)

·        Winter visitor (W)

·        Possible winter visitor (?W)

Flight line surveys

13.5.43   A survey of the flight lines of birds over the Assessment Area was undertaken as a separate exercise during the period January – December 2001.  The specific objectives of the study were to identify any likely adverse ecological impacts that the proposed residential complex may have on bird flight paths, particularly in relation to species of conservation importance within three key groups of birds, listed below, and to identify any measures that could be taken to minimise impact on these bird groups, particularly in relation to building height and location. The key bird groups surveyed were:

·        “ardeids” – herons and egrets,

·        “raptors” – birds of prey,

·        “waterbirds” – ducks, cormorants and spoonbills.

13.5.44   During the twelve month period between January – December 2001, bird flight over the proposed development site was surveyed twice a month by a professional ornithologist from fixed vantage points situated on a hillside north of Ng Uk Tsuen (Figure 13‑8). These vantage points were selected because they provide an unobstructed view over the entire Study Site and surrounding area.

13.5.45   Bird flight activity is known to be related to time of day so surveys were conducted during the periods immediately after sunrise and immediately before sunset, when activity is greatest and when there is sufficient light to allow identification. Morning and evening surveys were conducted on separate days during each month.

13.5.46   The duration of each survey was four (4) hours subdivided into eight (8) equal half-hour segments. A relative system was employed for the timing of surveys to compensate for changes in the time of sunrise and sunset through the seasons (see Table 13‑2).

 

Table 132       Survey Time Segments for Bird Flight Line Surveys

Time period code

Time segments

Evening

 

1

Sunset minus 30-0 mins

2

Sunset minus 60-30 mins

3

Sunset minus 90-60 mins

4

Sunset minus 120-90 mins

5

Sunset minus 150-120 mins

6

Sunset minus 180-150 mins

7

Sunset minus 210-180 mins

8

Sunset minus 240-210 mins

Morning

 

9

Sunrise plus 0-30 mins

10

Sunrise plus 30-60 mins

11

Sunrise plus 60-90 mins

12

Sunrise plus 90-120 mins

13

Sunrise plus 120-150 mins

14

Sunrise plus 150-180 mins

15

Sunrise plus 180-210 mins

16

Sunrise plus 210-240 mins

 

13.5.47   During surveys all birds flying over the site were identified to species level. The individual flight lines of target species (defined in Table 13-3) were recorded on standard survey maps, uniquely referenced, and the following information recorded on cross-referenced data sheets:

·                     Reference number

·                     Survey date

·                     Survey period

·                     Species code

·                     Number of birds in the group (flocks of two or more birds often follow a similar route)

·                     Approximate altitude estimated by the observeer

 

Table 133       Target Species for Flightline Surveys and Their Species Codes used on Recording Sheets

Species

Species code

Ardeids

Cattle Egret (Bubulcus ibis)

CE

Chinese Pond Heron (Ardeola bacchus)

CPH

Great Egret (Egretta alba)

GE

Grey Heron (Arda cinerea)

GH

Little Egret (Egretta garzetta)

LE

Black-crowned Night Heron (Nycticorax nycticorax)

NH

Waterbirds

Black-faced Spoonbill (Platalea minor)

BFS

Eurasian Spoonbill (Platalea leucorodia)

ES

Great Cormorant (Phalacrocorax carbo)

GC

Northern Pintail (Anas acuta)

NP

Spot-billed Duck (Anas poecilorhyncha)

SD

Raptors

Black Kite (Milvus migrans)

BK

Common Buzzard (Buteo buteo)

CB

Common Kestrel (Falco tinnunculus)

CK

Crested Serpent Eagle (Spilornis cheela)

CSE

Greater Spotted Eagle (Aquila clanga)

GSE

Imperial Eagle (Aquila heliaca)

IE

Osprey (Pandion haliaetus)

OS

 

13.5.48   The observation locations are approximately 40m above ground level thus enabling the observer to gauge altitude. Nevertheless it was not considered feasible to estimate altitude accurately to less than 20m and so height categories of 20m interval were employed (Table 134Error! Reference source not found.). Landmarks along the horizon were also used to estimate the height at which the birds were flying across the Study Site.

Table 134       Altitude Categories Adopted to Record the Bird Flight Line Data

Altitude category

Altitude

1

<20m

2

20-40m

3

40-60m

4

>60m

13.5.49   The survey data were manually geo-coded into a GIS (MapInfo Ver. 6) and the following attributes input for each individual flightline:

·        Species 

·        Altitude category (except for data collected during January 2001) 

·        Date and time period code 

·        Number of birds in the group 

13.5.50   For analytical purposes, the survey data were aggregated into months (Jan, February, March etc.).

13.5.51   Flight line data were geo-coded and overlaid onto digitised base maps of the Study Site.

13.5.52   The GIS package was interrogated to identify the species composition and abundance of birds flying over any sector (or all) of the Study Site for any (or all) altitude categories and for any (or all) months. On the basis of these data it was possible to compare the species composition and abundance of birds flying through the sector occupied by the Proposed Development Area and to compare these to similar data for the entire study area or any other sector of the study area.

13.5.53   Specific analyses focused on a describing the absolute and relative abundance of target species flying across, within, into or out of the Study Site and, in particular, the specific sector of the Study Site that would be occupied by the proposed residential development

Mammals

13.5.54   Mammals were surveyed concurrently during reptile and amphibian surveys along the set transect routes shown in Figure 13‑5.

13.5.55   Mammals were surveyed monthly during the day and at dusk from April to November. As they are elusive species any evidence of their presence including the presence of scats, tracks and feeding were also recorded. Relevant data of sightings of mammals were recorded on standard survey forms.

 

13.6          General Ecological Profile and Evaluation of Valued ecological Components

Habitats

13.6.1      On the basis of the literature review, interpretation of aerial photographs, site inspections and flora and fauna surveys, the ecological resources and receivers that may be affected by the development were identified. Amongst these the Valued Ecological Components (VECs) (Treweek 1999), both habitats and Species of Conservation Importance, have been determined following the guidelines for the evaluation of ecological importance of habitats and species given in the Technical Memorandum on Environmental Impact Assessment Process (EPD).

Introductory Overview of Broad Habitat Types

13.6.2      The Study Site (as defined in Section 13.1.2) is composed almost entirely of aquaculture ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds). The 500m buffer zone around the Study Site contains a greater variety of habitat types including, Feng Shui woodland, permanent natural freshwater habitats and mangrove stands, although aquaculture ponds remain the dominant habitat type. 

13.6.3      Based on interpretation of recent aerial photographs, existing data and site inspections 19 distinct habitat types were categorised on the basis of their botanical composition and physical and structural characteristics:

·        Intertidal forested wetlands – mangrove stands

·        Permanent rivers, streams and creeks – natural flowing freshwater habitats

·        Ditches and drainage channels – artificial ditches, drainage channels and nullahs

·        Aquaculture pond  – fishponds bound by vegetated bunds; some managed for commercial aqua-culture production, others where no management facilities were observed in the immediate vicinity of the pond

·        Reedbed

·        Permanent freshwater marsh and pools – flooded areas comprising a mix of water‑dependent plants

·        Seasonally flooded agricultural land – includes intensively managed wet agricultural land

·        Dry agricultural land – agricultural land on which a range of food crops and flowers are cultivated

·        Inactive agricultural land – fallow or abandoned agricultural land which is un‑managed and has been invaded by herbaceous or shrubby vegetation

·        Orchard – patches of fruit trees mainly found scattered among rural village areas

·        Fung-shui forest – forest found around rural villages comprising native species or a mix of native species and fruit trees

·        Semi-natural secondary woodland – woodland formed from a mixture of planted and native species, moderately disturbed by human activity

·        Plantation forest – landscaping or ornamental plantations mainly found along roads and on cut-slopes

·        Grassland – habitats dominated by grass and herbaceous species

·        Grassland-shrubland mosaic – undisturbed areas with grassland comprising 80% of cover

·        Landscaped area – areas managed intensively for landscape or amenity purposes

·        Works in progress

·        Wasteland – secondary vegetative colonisation (mainly grasses and ruderals) on areas opened by human activities (excluding those grown on inactive agricultural land)

·        Developed area – areas highly developed with no visible vegetation cover except road-side weeds and includes a wastewater treatment works and associated water storage area

13.6.4      The distribution of these habitat types within the Assessment Area is illustrated in Figure 13‑9. Representative photographs of each habitat type are included in Appendix 13-2. Their respective coverage within the different sectors of the study area is quantified in Table 13‑5 below.

 

Table 135     Extent of Habitat Types within the Assessment Area (ha.)

Habitat

1. Proposed Development Area

2. Wetland Nature Reserve

3. Study site (1 + 2)

4. 500m buffer zone

5. Assessment Area (3 + 4)

Intertidal forested wetlands

0

0

0

45.3

45.3

Permanent rivers, streams and creeks

0

0

0

25.2

25.2

Ditches and drainage channels

0

0.4

0.4

0.4

0.8

Aquaculture pond

4.0

75.7

79.7

90.1

169.8

Reedbed

0

0

0

0.4

0.4

Permanent freshwater marsh and pools

0

0

0

2.8

2.8

Seasonally flooded (wet) agricultural land

0

0

0

1.7

1.7

Dry agricultural land

0

0

0

0.2

0.2

Inactive agricultural land

0

0

0

5.2

5.2

Orchard

0

0

0

1.4

1.4

Fung-shui woodland

0

0

0

1.3

1.3

Semi-natural secondary woodland

0

0

0

18.4

18.4

Plantation  woodland

0

0

0

3.0

3.0

Grassland

0

0

0

4.2

4.2

Grassland – shrubland mosaic

0

0

0

20.5

20.5

Landscaped area

0

0

0

8.8

8.8

Works in progress

0

0

0

37.1

37.1

Wasteland

0

0

0

13.5

13.5

Developed area

0

0

0

61.9

61.9

TOTAL

4.0

76.1

80.1

341.4

421.5

13.6.5      The Proposed Development Area and the area of the proposed Wetland Nature Reserve are dominated by Aquaculture Ponds.  The bunds associated with these ponds have an infrastructure associated with fishpond operation (houses, sheds, power lines, unmade tracks, duck shelters etc.). There are also a limited network of Ditches and Drainage Channels.

13.6.6      The habitats surrounding this central core of fishponds (ie within the 500m Buffer Zone) are more diverse. In the southern part of the Buffer Zone there is a mosaic of wet and dry agricultural land (Seasonally Flooded Agricultural Land, Dry Agricultural Land and Inactive Agricultural Land) interspersed with naturally regenerating Freshwater Marsh and Reedbed that is functionally linked to the aquaculture ponds to the north. Also within this southern area, particularly on higher ground, there are semi-natural habitats of Grassland and Grassland-Shrubland Mosaic. Habitats dominated by woody species include Plantation Woodland, Orchard and Fung-shui Woodland. The remainder of the southern part of the buffer zone is occupied by highly disturbed habitats such as Wasteland and Developed Area associated with residential and industrial land-uses.

13.6.7      The northern part of the 500m Buffer Zone is dominated by Aquaculture Ponds, which beyond the limit of reclamation, give way to extensive Inter-Tidal Forested Wetlands (mangroves) and beyond the Assessment Area boundary, inter-tidal mudflat.

13.6.8      The eastern and western parts of the Assessment Area are bounded by permanent watercourses (Permanent Rivers, Streams and Creeks) which potentially provide opportunity for linkage to habitats over a wider geographical area. This capacity is severely limited, however, due to their highly degraded state.

13.6.9      Following the guidelines in Appendix 8 of the Technical Memorandum on Environmental Impact Assessment Process (EPD), the habitats of the Assessment Area are individually evaluated below with specific reference to their conservation value.

Habitat Evaluations

Intertidal Forested Wetlands

13.6.10   The northern part of the Assessment Area (500m Buffer Zone) is marine in character and extensive mangroves have developed in inter-tidal areas. Although patches of intertidal mudflat remain, the dominant vegetation is mangroves and for the purposes of this assessment this habitat has been considered collectively as mangrove. The ecological value of this habitat is evaluated in Table 13‑6.

 

Table 136       Ecological Evaluation Of Intertidal Forested Wetlands

Criteria

Intertidal forested wetlands

Naturalness

This habitat comprises naturally regenerating mangrove forest interspersed with uncolonised mudflat, mangroves are expected to colonise remaining mud-flat areas in coming years

Size (ha)

Relatively large; 45.3ha within the Assessment Area, none within the proposed Development Area or proposed WNR area

Diversity

Mangroves possess a diverse range of micro-habitats and species

Rarity

Common feature of inter-tidal zones in Hong Kong

Re-creatability

Low re-creatability

Fragmentation

Not fragmented (probably expanding in area)

Ecological linkage

Linked to other areas of mangroves in the Deep Bay area

Potential value

Unlikely to achieve significantly greater value

Nursery and breeding ground

High, breeding ground for many marine invertebrate species

Age

Unknown

Abundance/ Richness of wildlife

High

Conclusion*

Moderate to high

* Low, moderate or of high ecological value

Permanent Rivers, Streams And Creeks

13.6.11   This habitat type is restricted to two relatively large and very disturbed water courses. The Eastern main Drainage Channel in the eastern part of the Assessment Area and Tai River outfall in the west. The ecological value of these water courses is diminished due to extensive modifications to their banks and the very poor quality of the water flowing within them. The ecological value of this habitat is evaluated in Table 13‑7.

 

Table 137     Ecological Evaluation of Permanent Rivers, Streams and Creeks

Criteria

Permanent rivers, streams and creeks

Naturalness

Highly disturbed: water quality is poor and there have been extensive modifications to banks and riparian zone

Size (ha)

Approx. 25 ha. Within the Assessment Area, 0 ha within the Proposed Development Area or proposed WNR area

Diversity

Considered low in both habitat and species diversity

Rarity

This habitat is not considered to be rare and no rare species were recorded

Re-creatability

Readily re-creatable

Fragmentation

Not fragmented

Ecological linkage

Although watercourses can act as corridors for the dispersal of plant and animal species the ecological linkage of this habitat is considered to be low because of its highly modified and disturbed condition

Potential value

Could be higher subject to water quality improvements. Potential value is limited, however, due to bank modifications

Nursery and breeding ground

Not considered significant

Age

No information but considered irrelevant

Abundance/ Richness of wildlife

Poor

Conclusion*

Low

* Low, moderate or of high ecological value

 

Ditches and Drainage Channels

13.6.12   Four drainage ditches were identified within the Assessment Area. Used for translocating water between fishpond areas, these ditches have low intrinsic value for flora and fauna, but do provide some linkage between habitats. The ecological value of this habitat is evaluated in Table 13‑8.

 

Table 138       Ecological Evaluation of Ditches and Drainage Channels

Criteria

Ditches

Naturalness

Artificial habitat

Size (ha)

Approx. 0.8 ha. Within the Assessment Area, 0.4 ha within the Proposed Development Area and proposed WNR area

Diversity

Considered low in both habitat and species diversity

Rarity

This habitat is not considered to be rare and no rare species were recorded

Re-creatability

Readily re-creatable

Fragmentation

Not fragmented

Ecological linkage

Very limited but does provide some linkage between some ponds in the western part of the proposed Wetland Nature Reserve and the Tai River outfall.

Potential value

Could be higher subject to water quality improvements

Nursery and breeding ground

Not considered significant

Age

No information but considered irrelevant

Abundance/ Richness of wildlife

Poor

Conclusion*

Low

* Low, moderate or of high ecological value

 

Aquaculture Ponds

13.6.13    The dominant land-use within the Assessment Area is aquaculture. This area consists of a matrix of fishponds bounded by vegetated bunds, which is considered in this assessment as a complex of functionally related habitats. The man-made bunds link fishponds to one another and to adjacent terrestrial habitats. Bunds are a disturbed habitat type but provide roosting areas and refuge for some bird species that forage in fishponds. Actively managed aquaculture ponds are of higher ecological value than unmanaged aquaculture ponds because they support more abundant prey and periodic draw-down allow birds to access prey.

 

Table 139       Ecological Evaluation of Aquaculture Ponds

Criteria

Aquaculture ponds

Naturalness

Man-made habitat; Actively managed for fish production are the least natural but tend to support a higher diversity and abundance of birds

Size (ha)

169.8 ha in Assessment Area of which 79.7 ha is within the Study Site. Of this 4 ha is found within the Development Area.

Forms part of an extensive, contiguous block of aquaculture ponds within the Fung Lok Wai Assessment Area that is itself closely linked to fishpond areas in the Deep Bay Area, including Mai Po;

Active aquaculture is more dominant within the Assessment Area

Diversity

Low habitat diversity but very high in terms of the diversity of wildlife supported; Unmanaged ponds tend to support fewer individuals

Rarity

The habitat itself is not rare but some of the species supported are rare locally or globally, notably some avifauna

Re-creatability

Readily re-creatable

Fragmentation

Not fragmented

Ecological linkage

Part of the large contiguous area of fishpond habitat in the Deep Bay area and serves similar function to those located at Mai Po Nature Reserve

Potential value

High ecological potential if managed to enhance wildlife use

Nursery and breeding ground

Actively managed ponds are a highly productive system that are particularly important for the high densities of important food resources provided for birds during draw-down for harvest periods.

Inactive ponds tend to be less valuable than active, but they do provide an important breeding/nursery ground for the prey of bird and other mammals, notably Tilapia and chironomids;

Bunds provide a breeding ground for some passerines and numerous terrestrial invertebrates

Age

Probably less than 40 years. This issue is, in any event, considered irrelevant to the ecological value of this habitat type

Abundance/ Richness of wildlife

High

Conclusion*

High

* Low, moderate or of high ecological value

 

Reedbed

13.6.14   Reedbed habitat is restricted to a small area, probably an abandoned fishpond in the southern part of the assessment area. The area is small and densely occupied by Phragmites. Whilst this area may provide cover for some species (eg birds) its small size and dense growth limits its overall value. Small stands of reeds associated with ditches are considered under Ditches and drainage channel as they form part of the characteristic vegetation of that habitat type (see Table 13‑10)

 

Table 1310     Ecological Evaluation of Reedbed

Criteria

Reedbed

Naturalness

This is naturally regenerating habitat within an artificial fishpond

Size (ha)

Total of 0.4 ha within the Assessment Area in several small blocks.

Diversity

Both species and habitat diversity are considered low

Rarity

Neither the habitat nor the species found are considered rare

Re-creatability

Highly re-creatable

Fragmentation

Highly fragmented, only one small area recorded within the Assessment Area

Ecological linkage

Links ponds in the Fung Lok Wai Study Site and wet habitats in the southern part of the Assessment Area.

Potential value

Moderate potential value - would be higher if actively managed as wildlife habitat

Nursery and breeding ground

Part of the Fung Lok Wai wetland system and probably providing habitat for breeding invertebrates that form the foods source of larger animals such as birds and amphibians

Age

No information is available but the size and density of reed growth (at the time of the survey) suggests that it was more than 5 years old

Abundance/ Richness of wildlife

Low

Conclusion*

Low

* Low, moderate or of high ecological value

 

Permanent Freshwater Marsh and Pools

13.6.15   Areas of marsh occur in the southern part of the Assessment Area in close association with various agricultural land-uses. It is likely that these areas of marsh have formed on land previously used for aquaculture or wet agriculture (see Table 13‑11).

 

Table 1311     Ecological Evaluation of Permanent Freshwater Marsh and Pools

 Criteria

Permanent freshwater marsh and pools

Naturalness

The marsh community appears natural but has probably developed on agricultural fields or ponds that have become inactive

Size (ha)

Total of 2.8 ha within the Assessment Area in several small to moderate sized blocks

Diversity

Species and habitat diversity are considered moderate and low respectively

Rarity

Neither the habitat nor the species found are considered rare

Re-creatability

This habitat is readily re-creatable provided land is available

Fragmentation

Fragmented

Ecological linkage

Part of the wetland systems of the Fung Lok Wai and the Deep Bay area as a whole

Potential value

Moderate potential value - would be higher if actively managed as wildlife habitat

Nursery and breeding ground

Likely to provide a nursery/breeding ground for the invertebrates which serve as an important food item to insectivorous fauna

Age

No information is available, but species diversity and plant age (at the time of the survey) suggests that this marsh was over 5 years old.

Abundance/ Richness of wildlife

Moderate

Conclusion*

Low to Moderate

* Low, moderate or of high ecological value

 

Agricultural Land

13.6.16   Agricultural land is found within the southern part of the Assessment Area within the 500m Buffer Zone. Various type of agricultural land are present and these have been distinguished on the type and intensity of management in Table 1312 - Table 1314.

 

Table 1312     Ecological Evaluation of Seasonally Flooded (wet) Agricultural Land

Criteria

Wet agriculture

Naturalness

Man-made habitat actively managed for crop production

Size (ha)

Total of 1.7 ha within the Assessment Area in several moderate sized blocks

Diversity

Habitat diversity is low but diverse invertebrate and vertebrate fauna are supported

Rarity

The habitat type is not rare in Hong Kong, but is declining rapidly, with few large areas remaining. A number of rare bird species are known to utilise this habitat type as feeding/roosting sites, including Northern Hobby

Re-creatability

It is readily re-creatable provided that land is available

Fragmentation

The areas of this habitat are slightly fragmented but lie in close proximity in the southern part of the Assessment Area

Ecological linkage

Forms part of a mosaic of wet and dry land-uses in the southern part of the Assessment Area. Functionally linked to the broader Fung Lok Wai area

Potential value

High potential if ecologically sensitive management practices are retained or adopted

Nursery and breeding ground

Likely to provide a nursery/breeding ground for the invertebrates which serve as an important food item to insectivorous fauna

Age

No information is available and this criteria is considered irrelevant to the ecological value of active wet agricultural land

Abundance/ Richness of wildlife

Moderate

Conclusion*

Moderate

* Low, moderate or of high ecological value

 

Table 1313     Ecological Evaluation of Dry Agricultural Land

Criteria

Dry agricultural land

Naturalness

Man-made habitat actively management for crop production

Size (ha)

Total of 0.2 ha within the Assessment Area in several small blocks

Diversity

Low to moderate in habitat diversity and species diversity due to the diversity of food crops planted.

Rarity

The habitat type is not rare in Hong Kong, but a number of rare birds are known to use this type of habitat for feeding and/or roosting.

Re-creatability

Readily re-creatable provided that land is available

Fragmentation

Highly fragmented

Ecological linkage

Forms part of a mosaic of wet and dry land-uses in the southern part of the Assessment Area. Functionally linked to the broader Fung Lok Wai area

Potential value

Dry agricultural land could be managed to promote wildlife use by adopting management practices that enhance habitat heterogeneity; however, this may conflict with commercially driven crop production

Nursery and breeding ground

Likely to provide a nursery/breeding ground for the invertebrates which serve as an important food item to insectivorous fauna

Age

No information is available and this criteria is considered irrelevant to the ecological value of active dry agricultural land

Abundance/ Richness of wildlife

Low

Conclusion*

Low to Moderate

* Low, moderate or of high ecological value

 

Table 1314     Ecological Evaluation of Inactive Agricultural Land

Criteria

Inactive agricultural land

Naturalness

Man-made habitat

Size (ha)

Total of 5.2 ha within the Assessment Area in several small to moderate sized blocks

Diversity

Habitat diversity is moderate but supports diverse species

Rarity

The habitat type is not rare in Hong Kong, but a number of rare avifauna species have been reported from these areas

Re-creatability

Readily re-creatable

Fragmentation

Highly fragmented

Ecological linkage

Forms part of a mosaic of wet and dry land-uses in the southern part of the Assessment Area. Functionally linked to the broader Fung Lok Wai area

Potential value

Abandoned agricultural land could be managed to promote wildlife use by adopting management that aims to enhance habitat heterogeneity

Nursery and breeding ground

Likely to provide a nursery/breeding ground for the invertebrates which serve as an important food item to insectivorous fauna

Age

No information is available

Abundance/ Richness of wildlife

Low

Conclusion*

Low to Moderate 

* Low, moderate or of high ecological value

 

Orchards

13.6.17   Orchards are found within the southern part of the Assessment Area and comprise a variety of fruiting tree species often planted in association with other native and introduced tree and shrub species (see Table 13‑15).

 

Table 1315     Ecological Evaluation of Orchards

Criteria

Orchards

Naturalness

Man-made habitats

Size (ha)

Total of 1.4 ha within the Assessment Area in several small to moderate sized blocks

Diversity

Both the habitat diversity and species diversity are low

Rarity

Neither the habitat nor the species found are rare

Re-creatability

This habitat type is readily re-creatable

Fragmentation

Heavily fragmented

Ecological linkage

May provide movement corridor for wildlife using the surrounding area

Potential value

Poor in potential value as they are close to settlements and subject to high levels of disturbance

Nursery and breeding ground

No wildlife of conservation importance is expected

Age

Age varies depending on how recently planted. Presence of mature tress suggests significant age in some cases

Abundance/ Richness of wildlife

Low

Conclusion*

Low

* Low, moderate or of high ecological value

 

Fung Shui Woodland

13.6.18   A single Fung shui woodland has been identified in the southern part of the Assessment Area. The occupation by breeding egrets during the four seasons ecological survey had increased the conservation value of this small woodland area, however, recent observation indicates that this egretry is now abandoned (eg. Anon 2005) (see Table 13‑16).

 

Table 1316     Ecological Evaluation of Fung Shui Woodland

Criteria

Fung shui Woodland

Naturalness

Natural habitat but typical modifications by villagers limit value

Size (ha)

Total of 1.3 ha within the Assessment Area in a small block

Diversity

Structurally simple and species poor

Rarity

Fung shui woodlands are common, traditional feature of village areas in the New Territories. This example is rare because during the baseline surveys it supported an active egretry (now abandoned)

Re-creatability

Habitat characteristics are difficult to recreate

Fragmentation

Small isolated example although linked to other habitats

Ecological linkage

Connected to other woody habitats and adjacent to aquaculture ponds where ardeid species forage

Potential value

Limited due to village development in the surrounding area

Nursery and breeding ground

Breeding egrets

Age

The size of the trees indicates an age of over 50 years

Abundance/ Richness of wildlife

Low-Moderate

Conclusion*

With Egretry this habitats has High Ecological Value without the Egretry its value is considered to be of Low to Moderate Ecological Value

* Low, moderate or of high ecological value

 

Semi-natural Secondary Woodland

13.6.19   Secondary woodland areas are concentrated on the lower hillsides in the southern part of the Assessment Area. These areas are semi-natural and fragmented (see Table 13‑17).

 

Table 1317     Ecological Evaluation of Semi-natural Secondary Woodland

Criteria

Semi-natural secondary woodland

Naturalness

Semi-natural but with some modification and planting of non-native species

Size (ha)

Total of 18.4 ha within the Assessment Area in several moderate sized blocks

Diversity

Low in habitat diversity, moderate in species diversity

Rarity

Neither the habitat nor associated species are rare

Re-creatability

This habitat type is readily re-creatable

Fragmentation

Slightly fragmented

Ecological linkage

May provide movement corridors for wildlife

Potential value

High, if disturbance factors were removed.

Nursery and breeding ground

No wildlife of conservation importance

Age

Young to moderate

Abundance/ Richness of wildlife

Low to moderate

Conclusion*

Low to moderate

* Low, moderate or of high ecological value

 

Plantation woodland

13.6.20   Two small areas of plantation woodland were recorded within the Assessment Area, both are dominated buy non-native and exotic species (Table 13‑18).

 

Table 1318     Ecological Evaluation of Plantation Woodland

Criteria

Plantation woodland

Naturalness

Planted with predominantly non-native and exotic species

Size (ha)

Total of 3.0 ha within the Assessment Area in several small to moderate sized blocks

Diversity

Low in habitat diversity, moderate in species diversity

Rarity

Neither the habitat nor associated species are rare

Re-creatability

This habitat type is readily re-creatable

Fragmentation

Not fragmented

Ecological linkage

Low

Potential value

Low due to non-native species planted but succession could increase value

Nursery and breeding ground

No wildlife of conservation importance

Age

Young to moderate

Abundance/ Richness of wildlife

Low to moderate

Conclusion*

Low

 

Grassland

13.6.21   Small pockets of grassland were recorded across the Assessment site, primarily adjacent to the closed area boundary road (Table 13‑19).

 

Table 1319     Ecological Evaluation of Grassland

Criteria

Grassland

Naturalness

Natural regeneration, probably on disturbed areas. Subject to ongoing disturbance, including fire

Size (ha)

Total of 4.2 ha within the Assessment Area in several small blocks

Diversity

Low habitat and species diversity

Rarity

Neither habitat nor species recorded are rare

Re-creatability

Highly re-creatable

Fragmentation

Highly fragmented

Ecological linkage

Serves limited function as a link between other habitats, however, proximity to developed and disturbed habitats limits this function

Potential value

Low due to ongoing disturbance effects

Nursery and breeding ground

May contribute to invertebrate food resource for larger animals of the Assessment Area

Age

Not known but likely to be recent regeneration on previously disturbed land

Abundance/ Richness of wildlife

Low

Conclusion*

Low

* Low, moderate or of high ecological value

 

Grassland-shrubland mosaic

13.6.22   Grassland-shrubland mosaic habitat is associated with the hills in the southern part of the Assessment Area. Although it forms a linked habitat with areas of woody habitat, this habitat is subject to occasional burning through hill fires and hence its diversity and value are limited (Table 1320).

 

Table 1320   Ecological Evaluation of Grassland-Shrubland Mosaic

Criteria

Grassland-shrubland mosaic

Naturalness

Natural habitat but subject to hill-fire

Size (ha)

Total of 20.5 ha within the Assessment Area in several moderately sized blocks

Diversity

Low habitat and species diversity is found in this habitat

Rarity

Neither the habitat nor the species known to be present are considered rare

Re-creatability

Readily re-creatability

Fragmentation

Not fragmented within the Assessment Area

Ecological linkage

Linked to other woody habitats within the Assessment Area and may provide cover for animal movements

Potential value

Moderate ecological potential if hill-fires can be controlled

Nursery and breeding ground

None known

Age

Unknown. Fire disturbance tends to maintain the habitat in early successional stages and prevents establishment of woodland

Abundance/ Richness of wildlife

Poor

Conclusion*

Low

* Low, moderate or of high ecological value

 

Landscaped area

13.6.23   The main section of landscaped vegetation occurs in the eastern part of the Assessment Area adjacent to the closed area boundary road. The major vegetation associated with this habitat is intensively managed grass turf (Table 13‑21).

 

Table 1321     Ecological Evaluation of Landscaped Area

Criteria

Landscaped area

Naturalness

Man made and intensively managed

Size (ha)

Total of 8.8 ha within in the Assessment Area in a relatively large block

Diversity

Very low

Rarity

No rare habitats or species

Re-creatability

Highly re-creatable

Fragmentation

Not fragmented

Ecological linkage

Creates a barrier between the wetland habitats of the Assessment Area and the potential corridor of the Eastern Drainage Channel

Potential value

None

Nursery and breeding ground

None known

Age

Young, created during the drainage works conducted on the Eastern Main Drainage Channel.

Abundance/ Richness of wildlife

Very low

Conclusion*

Low

* Low, moderate or of high ecological value

 

Wasteland habitats

13.6.24   Several categories of land that has been highly disturbed including areas of wasteland and where ponds have been in-filled. Due to the nature of the disturbance, including clearance and compaction, vegetation may be absent or in the form of poorly developed communities dominated by ruderal species (Table 13‑22).

 

Table 1322   Ecological Evaluation of Wasteland Habitats

Criteria

Wasteland

Aquaculture ponds (infilled)

Naturalness

This is a man made habitat with little or no intrinsic ecological value

This is a man made habitat with little or no intrinsic ecological value

Size (ha)

Moderate; 13.5 ha

Small

Diversity

Not relevant

Not relevant

Rarity

Not relevant

Not relevant

Re-creatability

Readily re-creatable

Readily re-creatable

Fragmentation

Not relevant

Not relevant

Ecological linkage

Not relevant

Not relevant

Potential value

None

None

Nursery and breeding ground

Not considered significant

Not considered significant

Age

No information but considered irrelevant

No information but considered irrelevant

Abundance/ Richness of wildlife

Poor

Poor

Conclusion*

Low

Low

* Low, moderate or of high ecological value

 

Recreated Wetland (Hong Kong Wetland Park)

13.6.25   During the assessment period there was an area of land in the western part of the assessment area that was identified as Recreated Wetland. This area comprises wetlands and other habitats forming part of the Hong Kong Wetland Park. The Hong Kong Wetland Park is a man-made wetland consisting of 60 hectares of re-created habitats specially designed for waterfowls and other wildlife.  Located on the western side of the Assessment Area, the Wetland Park was originally intended to be an ecological mitigation area (EMA) to compensate for the wetlands lost due to Tin Shui Wai New Town development. The original EMA has now been expanded to become a conservation, education and tourism facility. During the assessment period these habitats were under construction, followed by a period of establishment, and their ecological value was, therefore, at the time of the baseline surveys considered to be low. The works have now been completed and the site has been in operation since May 2006. The value of the wetland habitats at the Wetland Park will increase with time and it is anticipated they will become High in the lifetime of the Fung Lok Wai project. As indicated in Table 13‑23 these habitats have been evaluated as Moderate – High.

 

Table 1323   Ecological Evaluation of Recreated Wetland

Criteria

Hong Kong Wetland Park

Naturalness

Man made natural habitat, subject to human disturbance through tourism

Size (ha)

60 ha Wetland area, 1 ha Visitor Centre

Diversity

High

Rarity

High

Re-creatability

Re-creatable

Fragmentation

Not fragmented

Ecological linkage

Potentially high as this area is close to the proposed Fung Lok Wai WNR

Potential value

High

Nursery and breeding ground

Not significant record 

Age

Young

Abundance/ Richness of wildlife

High

Conclusion*

Moderate - High

* Low, moderate or of high ecological value

 

Developed areas

13.6.26   The southern part of the Assessment Area includes a variety of heavily developed land-uses, including Proposed Development Areas, and industrial estate, wastewater treatment and water storage areas. Typically these have very low intrinsic ecological value. Those species that do occur tend to be very common, introduced species or pests (Table 13‑24).

 

Table 1324     Ecological Evaluation of Developed Areas

Criteria

Developed area

Wastewater treatment area

Water storage area

Naturalness

This is a man made habitat with little or no intrinsic ecological value

This is a man made habitat with little or no intrinsic ecological value

This is a man made habitat with little or no intrinsic ecological value

Size (ha)

Large

Moderate

Small

Diversity

Not relevant

Not relevant

Not relevant

Rarity

Not relevant

Not relevant

Not relevant

Re-creatability

Readily re-creatable

Readily re-creatable

Readily re-creatable

Fragmentation

Not relevant

Not relevant

Not relevant

Ecological linkage

Not relevant

Not relevant

Not relevant

Potential value

None

None

None

Nursery and breeding ground

Not considered significant

Not considered significant

Not considered significant

Age

No information but considered irrelevant

No information but considered irrelevant

No information but considered irrelevant

Abundance/ Richness of wildlife

Poor

Poor

Poor

Conclusion*

Low

Low

Low

* Low, moderate or of high ecological value

Conclusions

13.6.27   The outcomes of the individual habitat evaluations are summarised in Table 13‑25. It can be seen that the most valuable habitat components of the Assessment Area are wetland habitats. In particular the extensive block of Aquaculture Ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds) that form a large contiguous area embedded within the broader Deep Bay Area that includes Mai Po. Adjacent to this central fish pond area there is, in the southern part of the Assessment Area, a mosaic of other wetland habitats including wet agriculture, marshland and reedbeds. Whilst these areas are of less intrinsic ecological value, their close proximity and functional linkage with the main fish pond area enhances their overall status.

13.6.28   The egretry in the small Fung-shui Woodland also in the southern part of the Assessment Area was also a feature of high ecological value due to the scarcity of active egretries in the New Territories. However, recent evidence suggests that it is abandoned (see Anon 2005); it is of a low to moderate ecological value.

13.6.29   The key ecological value of the Assessment Area is, therefore, the habitat it provides for breeding and foraging birds, particular wetland birds such as herons and egrets. Traditional aquaculture and agricultural management practices have, to a large extent, engendered this value. At the same time, however, these practices also limit the potential value of these habitats. Aquaculture ponds are for example small and steep sided which restricts bird access and pond bunds are cleared to maintain access to ponds. With more sympathetic management the value of the wetland habitats at Fung Lok Wai could be significantly higher.

13.6.30   The extensive area of inter-tidal habitat in the northern part of the Assessment Area is also of moderate to high ecological value due to the high biological diversity of mangal systems. There is no direct link between these habitats and the Proposed Development Area, however, and the potential for impact is very low.

13.6.31   All other habitats within the Assessment Area are considered to have low ecological value due, primarily to previous and current levels of disturbance.

 

Table 1325     Summary of habitat evaluations in order of ecological value.

Habitat

Overall evaluation

Aquaculture ponds

High

Fung-shui woodland

                With egretry

                Without egretry

 

High

Low to Moderate

Recreated Wetland (Hong Kong Wetland Park)

Intertidal forested wetlands

Moderate to high

Moderate to high

Agricultural land

                Seasonally flooded agricultural land

                Dry agricultural land

                Inactive agricultural land

 

Moderate

Low to moderate

Low to moderate

Permanent freshwater marsh and pools

Low to moderate

Semi-natural secondary woodland

Low to moderate

Permanent rivers, streams and creeks

Low

Reedbed

Low

Ditches and drainage channels

Low

Wasteland

                Wasteland

                Aquaculture ponds (infilled)

 

Low

Low

Grassland

Low

Grassland-shrubland mosaic

Low

Orchard

Low

Plantation forest

Low

Landscaped area

Low

Developed areas

                Developed area

                Wastewater treatment area

                Water storage area

 

Low

Low

Low

 

Species of Conservation Importance

13.6.32   Following guidance given in Annex 16 (Note 3) of the EPD's Technical Memorandum on Environmental Impact Assessment, species have been identified that are considered to be Species of Conservation Importance. These are defined as species that occurred within the Study Site in significant numbers and are:

·        Globally threatened (IUCN 2000, Collar et al. 1994) or threatened in China (Endangered Species Scientific Commission 1998).

·        Internationally Protected Species, i.e. protected by international conventions: (1) The Convention on the Conservation of Migratory Species of Wild Animals (the Bonn Convention), (2) listed under an agreement between the Government of Australia and the Government of the People’s Republic of China for the Protection of Migratory Birds and their Environment, (3) listed under an agreement on the Protection of Migratory Birds and their Habitats between the Government of Japan and the Government of the People’s Republic of China.

·        Protected by Hong Kong legislation and guidelines: (1) The Forests and Countryside Ordinance (Cap. 96), (2) The Forestry Regulations (subsidiary legislation of Cap. 96), (3) The Wild Animals Protection Ordinance (Cap. 170), (4) Protection of Endangered Species of Endangered Species of Animals and Plants Ordinance (Cap. 586), (5) The Fisheries Protection Ordinance (Cap. 171), (6) The Fisheries Protection Regulations (subsidiary legislation of Cap. 171).

·        Protected by Chinese laws and regulations: (1) The Wildlife Protection Law of the PRC, (2) The Wildlife Protection Implementation Regulation of the PRC.

·        Note: All birds and bats are listed in the Wild Animals Protection Ordinance primarily as protection from hunting, persecution and trade etc. Therefore, only those that meet other criteria listed here or are Locally Important Species according to criteria listed below are considered to be Species of Conservation Importance.

·        Endemic to Hong Kong or south China; if they are rare in the territory or have special conservation importance according to other scientific studies, e.g. for birds if they are of international importance (i.e. >1% of the biogeographical population) or regional importance (as listed in the Deep Bay Ramsar Conservation Strategy (Aspinwall Clouston & Wetlands International - Asia Pacific, 1997).

·        Based on the above criteria and Fellowes et al. (2002), species that occurred within the Assessment Area identified as being of conservation importance are further subdivided into categories of global, regional or local conservation importance. Although these species include some that are reasonably widespread in Hong Kong they are considered important in sustaining the long-term biodiversity of the territory.

Plants

13.6.33   For each habitat type surveys were conducted to determine species composition and relative abundance. The results of these surveys are included in Appendix 13-3.

A total of 326 plant species were recorded within all habitats of the assessment area. Off these 206 are native to Hong Kong, and most are common and widespread. No plant Species of Conservation Importance were recorded in significant numbers at the site.  However, four plant species of conservation interest were recorded, within five different habitats (Table 13‑26).

 

Table 1326     Plant Species of Potential Conservation Interest Recorded within the Assessment Area

Plant species

Status within Hong Kong1

Regional distribution and protected status

Recorded abundance

Habitat

Ammannia auriculata

Very rare

Regionally widespread

Occasional

Watercourse

Aquilaria sinensis

Common

Class 2 in China

Occasional

Woodland and orchard

Phymatodes scolopendria*

Rare

 

Scarce

Aquaculture Pond (bunds)

Sphenoclea zeylanica

Rare

 

Scarce

Wet Agriculture

1 Based on Corlett et al. (2000).

* Previously Microsorium scolopendrium

13.6.34   None of these species is common within the assessment area, with two (Phymatodes scolopendria and Sphenoclea zeylanica) recorded only from single specimens. Ammannia auriculata is locally rare but regionally widespread in south China and a known pan-tropical weed. It was located within Ditches and drainage channels habitat which is typical habitat for this species. Aquilaria sinensis is protected (Category III) in China and listed as VU on IUCN red data list. It is, however, a common tree in Hong Kong where its natural status is difficult to determine as it is widely cultivated. Phymatodes scolopendria is usually a species of rocky shores. At Fung Lok Wai it was recorded at the edge of a pond which was no longer actively managed and is likely to be a remnant of previously cultivated plants. Sphenoclea zeylanica is rare in Hong Kong and typically found in abandoned paddy fields and wasteland. Within this survey it was located in a wet agricultural area in the southern part of the Assessment Area outside the Proposed Development Area.

13.6.35   None of the above species are protected under Hong Kong legislation.  Only one Aquilaria sinensis could be considered a species of Conservation Importance under the criteria outlined in the EIAO –TM. However, this species is common in Hong Kong and likely to be a cultivated variety.

Aquatic Invertebrates

13.6.36   Surveys of aquatic invertebrates reveal a highly depauperate fauna (Appendix 13-4). Commonly sampled aquatic invertebrates include Dipteran species such as the ubiquitous Chironominae spp. and crustaceans such as Palaemonid shrimps. Infrequent gastropods were also sampled, particularly in watercourses. The dominant species are typical of disturbed aquatic habitats, such as fishponds and drainage ditches.

13.6.37   The absence of water of high quality and the lack of flowing habitats clearly limits the value of the site for aquatic invertebrates. Although diversity is low, the abundance of Chironomids and Palaemonid shrimps is significant, however, because they form a valuable source of food for other fauna, particularly birds.

13.6.38   Analysis of the variance of sampled populations (sweep and core) of these groups throughout the site and during wet and dry seasons, indicates that although there is significant variability between locations, these invertebrates collectively provide a reliable food source around the year.

Odonata

13.6.39   Twenty-six species of dragonflies and damselflies were recorded during surveys within the Fung Lok Wai EIA Assessment Area (see Appendix 13-5), approximately 23% of the known dragonfly fauna of Hong Kong (Wilson 1997). These species are all common and widespread. Two species previously considered to be of Local Conservation Concern (Fellowes et al. 2002),  Potamarcha congener and Urothemis signata signata, are known to be widespread in Hong Kong (Wilson et al. 2004).

13.6.40   Brachythemis contaminata, Ischnura senegalensis, Orthetrum sabina sabina, Pantala flavescens and Rhyothemis variegata aria are the most frequently recorded species collectively accounting for over 60% of all dragonflies recorded during the surveys.

13.6.41   Potamarcha congeneri was recorded on only one occasion in the vicinity of the access track (Transect 3) in the western part of the Buffer Zone. Urothemis signata signata was recorded regularly along Transect 1 and less frequently along Transect 6 and on a single occasion along Transect 2. Records of these species accounted for only 1.2% of all dragonflies and damselflies recorded during the surveys.

13.6.42   Whilst dragonflies and damselflies are common throughout the Assessment Area, analysis of the transect surveys indicate that the highest species richness is recorded in the southern part of the site, within the Buffer Zone, where there is greater diversity of habitats including wetland habitats.

13.6.43   Overall species diversity for this group is limited. Regular surveys carried out throughout the year revealed a fauna that is dominated by a few, common species.

Butterflies

13.6.44   Fifty-eight species of butterfly were recorded within the Assessment Area, see Appendix 13-6. The majority of these are common and widespread although, nine species are considered to be uncommon, including Ampittia dioscorides, Eurema laeta, Graphium doson, Heliophorus epicles, Polyura athamas, Udaspes folus, Junonia orithya, Eurema brigitta and Hypolimnas misippus.

13.6.45   Of these species Eurema brigitta and Hypolimnas misippus are considered to be of local concern on the grounds that they are only known from 16 or less localities within Hong Kong (Fellowes et al. 2002). However no species recorded at the site are protected under Hong Kong SAR legislation nor are they considered to be Species of Conservation Importance according to the criteria stated in Annex 16 of the EPD's Technical Memorandum on Environmental Impact Assessment.

13.6.46   Analysis of the transect data indicates that whilst butterfly species were recorded throughout the site, species richness was greatest in the southern part of the Assessment Area, within the Buffer Zone where there is more diversity of both wet and dry habitats. Both species of local concern were recorded rarely with only 3 individuals of Eurema brigitta recorded along Transect 3 and a single individual of Hypolimnas misippus recorded along Transect 4.

13.6.47   The value of the Assessment Area for this fauna group is limited due to the limited range and extent of terrestrial habitats within the Assessment Area. The species present are largely common species that feed (in larval and adult stages) on the common and depauperate flora that typifies the disturbed habitats of much of the site. Species richness is greater in the southern part of the Assessment Area because of the presence of a greater range of habitats and hence food plants. Disturbance and unsympathetic management, however, still limit the value of these areas for terrestrial invertebrate fauna, including butterflies.

Fish

13.6.48   During the course of this survey five species of freshwater fishes, including two native species and three alien species were recorded (see Appendix 13-7). The species recorded were Carassius auratus (Goldfish), Monopterus albus (Oriental swamp eel), Gambusia affinis (Mosquito fish), Oreochromis niloticus (Nile Tilapia) and Channa striata (Striped snakehead).  In addition to the species found during this survey, Clarias gariepinus, the introduced African catfish is known from similar areas with disturbed habitats in the northern New Territories, and is likely to be found in the ditches and ponds of FLW. This is an alien species of no conservation value.

13.6.49   Carassius auratus is native to Hong Kong and uncommon. All individuals seen during the survey were dead specimens, probably discarded by fish farmers. Monopterus albus is a lowland species favouring slow-flowing streams and wet agricultural areas. Although still widespread, this species is on the decline due to the destruction of suitable habitat in rural areas of the New Territories (Chong and Dudgeon 1992). As all individuals seen were young, breeding is confirmed in the study area. Gambusia affinis is an alien species of no conservation value that it is widespread and common in Hong Kong. Individuals seen included young of the year, and breeding is thus confirmed in the study area. Oreochromis niloticus is an alien species of no conservation value. Individuals seen included shoals of young of the year, and breeding is thus confirmed in the study area. Channa striata is an alien species known to have recently established in Hong Kong (Cheung 1999). All specimens seen were fry or young fish indicating the species is breeding in this drainage system. It is widespread and common in the northern New Territories, especially the northwest. This species is a fierce invasive predator and is of no conservation value.

13.6.50   All waterways sampled were polluted and many were disturbed and/or choked with aquatic plants (such as the exotic and highly invasive Water Hyacinth (Eichhornia crassipes)), which clearly limits the diversity of lowland freshwater fish.

13.6.51   Most species found or expected to occur are alien species. No fish species of conservation value were found during the study period and although surveying in highly turbid waters limits fish detection, none are expected. Although Monopterus albus, a species thought to be in decline in Hong Kong (Chong and Dudgeon 1992), is of some interest it is not considered to be a Species of Conservation Importance.

Amphibians

13.6.52   Eight species of frog were recorded during the surveys of the Assessment Area (see Appendix 13-8). With the exception of Two-Striped Grass Frog (Rana taipehensis), these are all common species that are widespread within Hong Kong. Two-Striped Grass Frog has a limited distribution in the New Territories and as it is known from 16 or less locations in Hong Kong it is considered to be of local conservation concern by Fellowes et al. (2002). However no amphibian species recorded at the site are protected under Hong Kong SAR legislation nor are they considered to be Species of Conservation Importance according the criteria stated in Annex 16 of the EPD's Technical Memorandum on Environmental Impact Assessment.

13.6.53    Although frogs were recorded throughout the site, Transect 1 in the southern part of the Assessment Area, within the Buffer Zone, yielded the most species richness and individual abundance. This transect was the only location where Two-Striped Grass Frog was recorded.

Reptiles

13.6.54   Twelve species of reptiles were recorded during the surveys of the Assessment Area, including five species of lizards and seven species of snake (see Appendix 13-9). The lizard species recorded are all widespread within Hong Kong, however, all the snakes, with the exception of Checkered Keelback and White-spotted Slug Snake are considered to be of some conservation value (Table 13‑27).

 

Table 1327   Reptile Species of Some Conservation Value, Their Habitat Preferences and Observed Relative abundance within the Assessment Area at Fung Lok Wai

Species

Conservation concern and distribution*

Recorded abundance

Habitat preference*

 

Banded Krait

Bungarus fasciatus

Regional concern

D

Rare

Low lying areas near marshes, cultivated fields and shrub land

Common Rat Snake Ptyas mucosus

Potential regional concern

China Red Data Book species

 N/A

Rare

Varied including agricultural areas, shrub land and around ponds and reservoirs

Indo-Chinese Rat Snake

Ptyas korros

Potential regional concern

China Red Data Book species

N/A

Rare

Open habitats, including banks of streams and reservoirs, cultivated fields, ponds and shrub land

Many-banded Krait Bungarus multicinctus

Potential regional concern

N/A

Rare

Varied, including forest, agricultural areas and the edges of mangroves

Mangrove Water Snake Enhydris bennettii

Local concern

C

China Red Data Book species

Rare

Muddy coastal habitats

Local Distribution: A = known in this locality alone; B = known to occur in two localities; C = known to occur in three to four localities; D = known to occur in five to eight localities; E = known to occur in nine to 16 localities; F = known to occur in 17 to 32 localities; N/A – no local rating. * Levels of conservation concern and habitat preferences based on Fellowes et al. (2002) and Karsen et al. (1998).

13.6.55   Although reptile species were recorded throughout the Assessment Area, they were not abundant. Most were recorded only on one occasion throughout the survey period.

13.6.56   Banded Krait is typically found in low-lying areas particularly near marshes, areas under cultivation and in shrub land. During the baseline surveys it was only recorded within the Transects 1 and 2 which are centred on agricultural habitats in the southern part of the assessment area. Common Rat Snake is found in a variety of habitats, including agricultural land and shrubs, particularly close to water. During the baseline surveys the only record of this species was from Transect 5 which is located to the west of the Tai River. Indo-Chinese Rat Snake is also typically found in Hong Kong in a variety of habitats, including banks of streams and reservoirs, cultivated fields, ponds and shrub land. During the baseline surveys it was only recorded from Transect 10 which is located in hill-side woodland and scrub mosaic habitats. Many-banded Krait is found in Hong Kong in varied habitats including forest, agricultural areas and the edges of mangroves. During the baseline surveys it was recorded in Transect 1 which is focused on agricultural land uses in the southern part of the assessment site and Transect 6 which runs adjacent to mangroves and fish ponds. Mangrove Water Snake is associated with muddy coastal habitats although in the baseline surveys it was only recorded from Transect 7 which is in the central fishpond area.

13.6.57   Although there was no consistent pattern in snake distribution, the key area was found to be the southern section of the Buffer Zone which is composed of a range of wetland, agricultural, grassy and woody habitats is, therefore, considered to be of moderate to high value for snake species, including Species of Conservation Importance.

Birds

Transect Surveys

13.6.58   A total of 142 species of bird were recorded during surveys of the Assessment Area. Of these 116 species were recorded within fishpond and associated wetland habitats and 68 species from the hillside transects in the south of the site (see Appendices 13-10 and 13-11). Aquaculture ponds 63, 77 to 87 were not surveyed on 17 September 2001 due to severe flooding at the site preventing access to these ponds.

13.6.59   All bird species are currently protected under the Wild Animals Protection Ordinance (Cap. 170). However, there are considerable differences between species in relation to their distribution, rarity, threat and overall conservation status.

13.6.60   Twenty-four bird species, considered to be Species of Conservation Importance based on a range of criteria, were regularly recorded in significant numbers at the site (see Table 13‑28). Most are strongly associated with wetland habitats, including aquaculture ponds, permanent water courses, marsh, reed bed, wet agriculture intertidal habitats. Due to the limited distribution of these habitats in Hong Kong many of these species are largely restricted to the Deep Bay area. In addition, bird of prey species (which were recorded rarely foraging/flying over the site) were also included due to their large home ranges and their sensitivity to disturbance.


Table 1328     Bird Species of Conservation Importance Recorded in Significant Numbers within the Assessment Area of Fung Lok Wai

Common name

Scientific name

Protection status

IUCN Redlist Status

Hong Kong Fauna of conservation concern

Habitat preference in Hong Kong

Global conservation concern

 

 

 

 

Black-faced Spoonbill

Platalea minor

C, HK

EN

PGC

Mudflat, drained Gei wais and aquaculture ponds

Greater Spotted Eagle

Aquila clanga

B1, B2, C, HK

VU

GC

Brackish and freshwater marsh areas and fishponds

Imperial Eagle

Aquila heliaca

B1, B2, C, HK

VU

GC

Marshes, aquaculture ponds and adjacent hillsides in Deep Bay area.  Also recorded in the NW, NE & central New Territories

Red-billed Starling

Sturnus sericeus

HK

LC

GC

Aquaculture ponds, wet agricultural areas, perimeter of reedbeds; and natural and artificial drainage channels.

Regional conservation concern

 

 

 

 

Black Kite

Milvus migrans

HK

LC

RC

Sea, coast, intertidal mudflat, aquaculture ponds, grassy and shrubby hillsides and harbours.

Common Teal

Anas crecca

B2, HK

LC

RC

Shallow wetlands including aquaculture ponds

Eurasian Wigeon

Anas penelope

B2, HK

LC

RC

Intertidal areas, marsh and fishponds

Osprey

Pandion haliaetus

B2, C, HK

LC

RC

Bays, coastal areas, gei wais, aquaculture ponds, reservoirs

Potential regional conservation concern

 

 

 

 

Chinese Pond Heron

Ardeola bacchus

HK

LC

PRC

Freshwater marsh, aquaculture ponds and bunds, wet agriculture, rivers and drainage channels.

Great Cormorant

Phalacrocorax carbo

HK

LC

PRC

Coastal areas, aquaculture ponds

Great Egret

Egretta alba

A, J, HK

LC

PRC

Wetlands, particularly shallow intertidal bays, aquaculture ponds and marshes.

Grey Heron

Ardea cinerea

HK

LC

PRC

Abundant winter visito to Deep Bay associated with freshwater marsh, aquaculture ponds and bunds, wet agriculture, rivers and drainage channels.

Little Egret

Egretta garzetta

HK

LC

PRC

Wetlands including intertidal mudflats, gei wai, also aquaculture ponds, wet agriculture, marsh and banks of rivers and streams

Local conservation concern

 

 

 

 

Black-crowned Night Heron

Nycticorax nycticorax

HK

LC

LC

 

Coastal and sub-coastal wetlands, including aquaculture ponds, marsh, mangrove, intertidal mudflats, riverine wetlands

Cattle Egret

Bubulcus ibis

A, HK

LC

LC

Freshwater marsh, aquaculture pond bunds, wet agriculture.

Collared Crow

Corvus torquatus

HK

 

 

Primarily in Deep Bay, including rocky and sandy shores, intertidal mudflats, gei wai, aquaculture ponds

Crested Serpent Eagle

Spilornis cheela

C, HK

LC

LC

Hillside, woodland, rocky hilltops, undisturbed small marshes, abandoned wet paddies

Little Grebe

Tachybaptus ruficollis

HK

LC

LC

Gei wai, aquaculture ponds particularly those with emergent and submerged vegetation

Little Ringed Plover

Charadrius dubius

A, HK

LC

LC

Low-lying land close to freshwater: wet agriculture, reclaimed land, freshwater marsh, aquaculture ponds (particularly when drawn down) & coastal areas adjacent to freshwater streams

Pied Kingfisher

Ceryle rudis

HK

LC

LC

Fresh, brackish and saltwater wetlands including aquaculture ponds, gei wai, sheltered bays.

Striated Heron

Butorides striatus

HK

LC

LC

Mangroves and inter-tidal mudflats

Temminck's Stint

Calidris temminckii

B2, HK

LC

LC

Feeds and roosts in drawn down aquaculture ponds. Also forages in freshwater marsh.

White-throated Kingfisher

Halcyon smyrnensis

HK

LC

LC

Golf courses, gardens, aquaculture ponds. 

Wood Sandpiper

Tringa glareola

A, B2, HK

LC

LC

Low lying areas of freshwater marsh, wet agricultural land and aquaculture ponds in the New Territories particularly Long Valley. During spring passage observed on the intertidal mudflats. 

 

Protection Status: B1 = listed on Appendix I of the Bonn Convention; B2 = listed on Appendix II of the Bonn Convention; A = listed under an agreement between the Government of Australia and the Government of the People’s Republic of China for the Protection of Migratory Birds and their Environment; J = listed under an agreement on the Protection of Migratory Birds and their Habitats between the Government of Japan and the Government of the People’s Republic of China; C = protected in the People’s Republic of China; HK = protected in the Hong Kong SAR;

IUCN Red List: Source: www.iucnredlist.org              EN = Endangered; VU = Vulnerable; LC = Least Concern

Hong Kong Fauna of conservation concern: Source: Fellowes et al. (2002)           GC = Global Concern; RC = Regional Concern; PGC = Potential Global Concern; PRC = Potential Regional Concern; LC = Local Concern.


13.6.61   Four species were recorded that are considered to be of global conservation importance and these are described in more detail in the paragraphs below.

13.6.62   Black-faced Spoonbill - Breeds on the west coast of the Korean peninsula and in Liaoning, northeast China. Over winters in northern Vietnam, southern and eastern China including Deep Bay, Taiwan and Japan. It is a winter visitor to Hong Kong and possibly a passage migrant.  Highest counts occur during autumn commencing in the third week of October.  The species typically departs Hong Kong during the second week of April, although small numbers have been recorded in Deep Bay during the summer since 1984. BirdLife International estimates the world population of this species to be 1,480 individuals. The over-wintering population has increased since 1987-88 when peak winter counts were low (about 35 individuals) to a peak of 346 individuals in January 2006 (Anon 2006). Deep Bay is a critically important to the survival of this species and, during winter, has regularly supported about 20-25% of the world population.  During these surveys Black-faced Spoonbill was recorded within actively managed aquaculture ponds, particularly when ponds were drawn-down.

13.6.63   Greater Spotted Eagle – This species is a scarce and local winter visitor to the northern New Territories primarily between the end of October and end of March. The winter population appears to have declined probably due to at least in part to the disappearance of domestic duck-farming in Deep Bay area. This species was observed very rarely during baseline surveys only once (during February) overflying the assessment area from the hillside survey transect (Transect 6). The scarcity of this species is reflected in the counts for both the Deep Bay area (where a maximum of 4 individuals were recorded in winter 2004/05) and the DBF recording area where there were no records reported during monitoring surveys undertaken by the HKBWS (see Appendix 13-12). Greater Spotted Eagle will forage for prey over aquaculture ponds and brackish and freshwater marshes so the wetland habitats at Fung Lok Wai could comprise potential habitat, although the rarity of observations in this area imply that the Hong Kong population of this species has very little reliance upon it.

13.6.64   Imperial Eagle – This species is a common winter visitor, possibly a passage migrant through Hong Kong in February. Mainly observed during November to March, with numbers peaking in mid-winter. The distribution of this species is closely associated with the distribution of ducks, although is not often seen over intertidal areas. During these surveys Imperial Eagle was observed rarely over-flying the assessment area foraging for prey. This species was observed rarely (although more frequently than Greater Spotted Eagle) during baseline surveys with a maximum count of 2 individuals overflying the assessment area seen in January.  The scarcity of this species is reflected in the counts for both the Deep Bay area (where a maximum of 5 individuals were recorded in winter 2003/04 and 2004/05) and the DBF recording area where a maximum of 1 individual was recorded in winter 2004/05 (see Appendix 13-12). Imperial Eagle will forage for prey over aquaculture ponds, marshes and adjacent hillsides in Deep Bay area so the wetland habitats at Fung Lok Wai could comprise potential habitat, although the rarity of observations in this area imply that the Hong Kong population of this species has very little reliance upon it.

13.6.65   Red-billed Starling - Breeds only in China, however, it is a winter visitor in northern Indochina and an abundant but localised winter visitor to Hong Kong, where it forms large flocks that are considered to be of international significance. Recorded from the third week in October, numbers peak during the first two weeks of November. Typically departs Hong Kong during the second half of March. It tends to occur in large flocks and is primarily recorded in Deep Bay, as well as Long Valley, Kam Tin, Starling Inlet and Shuen Wan. The protection of roost sites in inter-tidal forest habitats and the intensification of aquaculture in the Deep Bay area (which may have created increased feeding opportunities) possibly accounts for the significant increase in the over-wintering population since the 1980s. During these surveys Red-billed Starling was frequently recorded around aquaculture ponds and adjacent to permanent watercourses during winter.

13.6.66   Of the 24 bird species of conservation importance recorded within the Assessment Area, 20 species were recorded within the Study Site (see Table 1329). Four additional species were recorded from the 500m buffer zone surveyed. No bird species of conservation importance were recorded solely from the Proposed Development Area. However, 11 species were recorded using the habitats within the Proposed Development Area but all of these species were recorded in significant numbers elsewhere on the site. The figures suggest that the aquaculture ponds of the Proposed Development Area are similar to those found elsewhere within the Study Site, they are of similar character and support a similar range of species.

 

Table 1329     List of Bird Species of Conservation Importance Recorded in Each Section of the Assessment Area at Fung Lok Wai.

Common name

Scientific name

Proposed Development Area

Study Site

Buffer Zone

Global conservation concern

 

 

 

Black-faced Spoonbill

Platalea minor

 

*

*

Greater Spotted Eagle

Aquila clanga

 

 

*

Imperial Eagle

Aquila heliaca

 

*

*

Red-billed Starling

Sturnus sericeus

*

*

*

Regional conservation concern

 

 

 

Common Teal

Anas crecca

 

*

*

Eurasian Wigeon

Anas penelope

 

*

*

Osprey

Pandion haliaetus

 

 

*

Potential regional conservation concern

 

 

 

Black Kite

Milvus migrans

*

*

*

Chinese Pond Heron

Ardeola bacchus

*

*

*

Great Cormorant

Phalacrocorax carbo

*

*

*

Great Egret

Egretta alba

*

*

*

Grey Heron

Arda cinerea

 

*

*

Little Egret

Egretta garzetta

*

*

*

Local conservation concern

 

 

 

Black-crowned Night Heron

Nycticorax nycticorax

 

*

*

Cattle Egret

Bubulcus ibis

*

*

*

Collared Crow

Corvus torquatus

 

*

*

Crested Serpent Eagle

Spilornis cheela

 

 

*

Little Grebe

Tachybaptus ruficollis

*

*

*

Little Ringed Plover

Charadrius dubius

 

*

*

Pied Kingfisher

Ceryle rudis

*

*

*

Striated Heron

Butorides striatus

 

*

*

Temminck's Stint

Calidris temminckii

 

 

*

White-throated Kingfisher

Halcyon smyrnensis

*

*

*

Wood Sandpiper

Tringa glareola

*

*

*

* Indicates presence

 

Flightline surveys

13.6.67   To understand patterns of bird movement within the site the flight line data collected during bird flight line surveys were collated and aggregated.

13.6.68   During the survey period 4052 individual birds were observed flying over some sector of the Study Site (Figure 13‑10). These flightline data recorded are summarised by bird group and altitude category in Table 13‑30.

 

Table 1330     Abundance and Proportion of Birds Observed Within the Study Site by Altitude Category (February-December 2001)

 

Height

 

Group

<20m

20-40m

40-60m

>60m

 All

 

No.

%

No

%

No.

%

No.

%

No.

%

Ardeid

1,391

94.5

1,010

76.6

134

12.8

40

18.8

2,575

64

Waterbird

46

3.1

263

19.9

843

80.4

52

24.4

1,204

30

Raptor

35

2.4

46

3.5

71

6.8

121

56.8

273

6

Total

1,472

 

1,319

 

1,048

 

213

 

4,052

100

 

13.6.69   Ardeids (2575, 64%) are clearly the most abundant group overall (Table 1330) and comprise, with other waterbirds (1204, 30%), 94% of all individuals recorded. As would be expected raptors, overall account for a small proportion of individuals observed (273, 6%). At lower altitudes ardeids are clearly dominant, with Little Egret the most abundant species recorded below 40m (Table 13‑31). Above 60m Black Kite accounts for the majority of records. Great Cormorant are abundant upwards of 20m and dominant in the 40-60m altitude category.

 

Table 1331     Dominant Species by Altitude Category

Altitude category

Dominant species (number recorded)

<20m

Little Egret (848), Great Egret (291), Chinese Pond Heron (137)

20-40m

Little Egret (743), Great Cormorant (245)

40-60m

Great Cormorant (740)

60m+

Black Kite (113), Great Cormorant (52)

 

13.6.70   These data reflect the observed behaviour of birds, with herons and egrets moving between ponds, often in short hops at relatively low altitudes, as they forage. Raptors, such as Black Kites, however, tend to forage at higher altitude, circling over ponds in search of food.

13.6.71   A total of 529 birds, 13% of all records for the site (4052), were observed flying through the sector of the Assessment Area occupied by the Proposed Development Area. Whilst, initially, this proportion seems high (the Proposed Development Area is only 5% of the area of the Study Site) it must be recognised that the records for this sector are not exclusive. That is, as birds fly through the site they intersect with many different sectors. On the basis of the distribution of flightlines revealed by the surveys, it is expected that any equivalent 4 ha sector located any where within the site would intersect with a similar proportion of flightlines.

13.6.72   Data for all individuals at each altitude category (Table 1332) indicates, however, that a disproportionately large number of birds are flying below 40m within the entire site (68.8%) and that for the proposed development sector this proportion is even higher (93.9%).

 

Table 1332     Comparison of Total Individuals for Each Altitude Category within the Study Site and the Proposed Development Area

Altitude category

Total individuals for

Study Site

Total individuals for Proposed Development Area

<20m

                     1,472 (36.3%)

                             255 (48.3%)

20-40m

                     1,320 (32.5%)

                             241 (45.6%)

40-60m

                     1,048 (25.9%)

                             15 (2.8%)

>60m

                     2,13 (5.3%)

                             17 (3.2%)

Total

                     4,052

                             528

 

Species composition

13.6.73   Analysis of the species composition of those flights occurring within the sector of the site occupied by the proposed development (Table 1333 and Table 1334 reveals a broadly similar pattern to those for the entire site with the following exceptions:

·        A higher proportion of ardeid species 92.4% (488 individuals) were observed within the footprint of the proposed development compared to the Study Site as a whole where ardeids comprised 64% of all individuals observed.

·        A much lower proportion of waterbird species 1.5% (8 individuals) were observed within the Proposed Development Area compared to the Study Site as a whole where waterbirds comprised 23% of all individuals observed.

 

Table 1333     Abundance and Proportion of Birds Observed within the Proposed Development Area by Altitude Category (February-December 2001)

 

Height

Totals

Group

<20m

20-40m

40-60m

>60m

 

 

No.

%

No.

%

No.

%

No.

%

Total

%

Ardeid

250

98.0

228

94.6

9

60.0

1

5.9

488

92.4

Waterbird

3

1.2

2

0.8

2

13.3

1

5.9

8

1.5

Raptor

2

0.8

11

4.6

4

26.7

15

88.2

32

6.1

Total

255

 

241

 

15

 

17

 

528

100

 

13.6.74   The most abundant species observed within the Proposed Development Area were Little Egret and Chinese Pond Heron (Table 1334), although the abundance of these species is expected to have declined following the abandonment of the egretry (see below). The vast majority of flightline activity for both Little Egret and Chinese Pond Heron observed within the area of the proposed development were below 40m and occurred during the breeding season, April to July.

 

Table 1334     Dominant Species Recorded at Each Altitude Category within the Proposed Development Area

Altitude category

Dominant species

<20m

Little Egret (191), Chinese Pond Heron (51)

20-40m

Little Egret (182), Chinese Pond Heron (35)

40-60m

Cattle Egret (5), Black Kite (4), Little Egret (4)

>60m

Black Kite (14)

 

Egretry

13.6.75   The relatively high proportion of Little Egret and Chinese Pond Heron individuals recorded within the Proposed Development Area can be largely explained by the establishment of an egretry on the south-west perimeter of the Assessment Area during March 2001, the Shing Uk Tsuen egretry. The flightlines of birds to and from this egretry tend to track across the south west corner of the study site, particularly at lower altitudes (<40m) (Figure 13.11). More recently it appears that this egretry has now been abandoned (see Anon 2005). It is anticipated that the continued abandonment of this egretry will have two consequences for the analyses presented above:

·        The overall levels of flight activity for ardeids will be less than that shown above.

·        There will be substantially fewer flightlines within the Proposed Development Area, there being less reason for birds to move between Fung Lok Wai and the South-western part of the Assessment Area.

13.6.76   Another egretry has recently been found at Ha Mei San Tsuen. This egretry is outside the Assessment Area and is located so far away that the development would unlikely to have material impact on the flight lines of this egretry. As far as foraging areas are concerned, it is unlikely that birds from this egretry utilise ponds in the development footprint more than was the case in Shing Uk Tsuen egretry.

Mammals

13.6.77   The mammal fauna of Hong Kong is poorly known compared to other fauna groups and there is limited information about the occurrence of mammal species in the Fung Lok Wai area. Opportunistic sightings of tracks, marks and scats indicate, however, that at least two species are likely to utilise the Assessment Area: Seven-banded Civet (Vivericcula indica) and Small Asian Mongoose (Herpestes javanicus). Neither of these species is threatened or restricted in area and are not considered species of conservation importance.

13.6.78   There are a number of mammal Species of Conservation Importance that were not recorded during the twelve months of survey but are known to occur within similar habitats in the Deep Bay area. These include: Eurasian Otter (Lutra lutra) and Crab-eating Mongoose (Herpestes urva). The large numbers of flying insects associated with fishponds and agricultural land are also likely to support bat populations, including, potentially, Noctule Bat (Nyctalus noctula), Leschenault's Fruit Bat (Rousettus leshenaulti) Lesser Yellow-house Bat (Scotophilis kuhlii), though no bat roosts were observed during the survey period.

Conclusions

13.6.79   The Fung Lok Wai Assessment Area supports a number of Species of Conservation Importance. In particular, it is of significance for bird species.

13.6.80   Two species of Global Conservation Concern, Black-faced Spoonbill and Red-billed Starling, are directly reliant on the wetland areas of the Assessment Area. Two eagle species of Global Conservation Concern have been recorded over the Assessment Area and are known to predate upon wetland bird species (such as ducks) that are themselves dependent upon the site. There are 20 other bird species of Regional or Local Conservation Concern. With the exception of Crested Serpent Eagle these are all waterbirds or raptors with a close association with the Aquaculture Ponds habitat.

13.6.81   Other than birds the only other Species of Conservation Importance identified during the baseline surveys are 5 species of reptile: Banded Krait, Common Rat Snake, Indo-Chinese Rat Snake, Many-banded Krait and Mangrove Water Snake.

13.6.82   In addition there are other species of amphibian, reptile, mammal, invertebrates and plant that are considered to be of some conservation value.  For these species the wetland habitats of the southern part of the Assessment Area, within the 500m Buffer Zone, including wet agriculture and freshwater marsh are particularly important.

13.6.83   Surveys were completed in January 2002 when most aquaculture ponds were under active management. Since completion of the surveys there has been no change in wetland area, there has been no in-filling of fish ponds, for example. There has, however, been a change in management of fish ponds. Site visits undertaken in recent years, including by WWF staff, indicate that relatively few ponds (about one quarter) are now in active production (Janet Lee, Pers. Comm.). For abandoned ponds, grass has encroached into the open water from the side of the ponds and Water Hyacinth (Eichhornia crassipes) is abundant in some these. In the absence of active management, bunds have become covered by long grass which reduces their attractiveness as roosting sites for waterbirds.

13.6.84   As the extent of wetland has not changed it is considered that the importance of the site for most species, including birds that are not dependent on the active fishpond management (eg Red-billed Starling) and non-avian fauna (such as reptiles) will be unchanged. For those birds that are dependent on the active management of fish ponds (including egrets and Black-faced Spoonbill) it is expected that the importance of the site will have declined.

13.6.85   Since the completion of the surveys the egretry at Shing Uk Tsuen has now been abandoned (Anon 2005) and this is expected to reduce the activity of herons and egrets within Fung Lok Wai.

13.6.86   It is considered that the results of these surveys remain applicable to the assessment. Any changes taking in place in the intervening period are expected to involve a reduction in ecological value due to a reduction in management activity. This is likely to effect bird species most as these tend to benefit from aquaculture activities that periodically provide access to food resources.

 

13.7          Identification of Potential Impacts

Summary of proposed development

13.7.1      The proposed development involves the conversion of approximately 4ha of aquaculture pond, located on the southern boundary of the Fung Lok Wai study site, to residential development. The proposal involves the construction of residential apartments, landscaping, car-parking and other ancillary structures.

13.7.2      The proposed vehicular access of the site, viz. the Southern Development Access, will be via the existing Fuk Shun Street and Yuen Long Industrial Estate to Yuen Long.

13.7.3      The construction and operation of the residential development will result in direct habitat loss and short and long-term disturbance to species of conservation importance (see below) as a consequence mitigation is proposed in the form of a Wetland Nature Reserve (WNR). This WNR will be constructed on the remaining, approximately 76.1 ha of the study site unaffected directly by the residential development. The WNR will comprise a large expanse of enhanced fishponds and re-recreated marshland habitat.

13.7.4      To minimise the impact of the residential construction on sensitive species it has been decided that the WNR will be constructed in advance of the residential development. This sequence of development has the advantage of minimising the negative effects (particularly disturbance) of residential construction, however, it also means that the effects of the mitigation works themselves, including temporary habitat loss and disturbance, on Species of Conservation Importance must also be considered in the impact assessment.

13.7.5      The construction of the WNR is divided into Sectors as described in Section 13.9. At each stage the maximum area of pond unavailable due to construction works is shown along with the remaining area unaffected by construction works.

Potential impacts

13.7.6      Initial analysis of baseline data indicated three constraints on the proposed development:

·        The location of the egretry in the southern part of the assessment area could result in flight line interference of birds attempting to access food resources within Fung Lok Wai. The preferred option, therefore, is to construct the residential development at a location approximately 150m eastwards of the original proposed location. This location remains the preferred option even though the egretry is now abandoned;

·        Accessing the site from the west adjacent to the Hong Kong Wetland Park, as originally proposed, will require additional construction work and, potentially, disturbance to the egretry. The preferred option, therefore, is to provide access to the residential development from the south through existing roads; and,

·        It is desirable to conserve existing wetland habitat and maintain linkages between all the wetland habitats within the Fung Lok Wai assessment area, including the mosaic of wetlands in the southern part of the Assessment Area. The WNR design has, therefore, been modified to accommodate the relocated development area. The preferred design for the WNR maintains connectivity with adjacent wetlands including those in the southern part of the assessment area.

13.7.7      Section 3 describes, in more detail, the development of the preferred options. Options 1A and 1B are considered to be broadly similar in ecological terms. They occupy the same area, hence habitat loss will be the same in each option nor is there considered to be a significant difference between the two options in terms of disturbance, pollution, soil compaction or hydrological disruption. The only slight difference between the options is potential with respect to fragmentation and this is considered in more detail below.

13.7.8      The following potential impacts arising from the construction and operation of these preferred development options are considered in more detail below:

·        Habitat loss;

·        Habitat fragmentation;

·        Disturbance;

·        Pollution;

·        Soil compaction; and,

·        Hydrological disruption.

Habitat loss

13.7.9      There will be no permanent habitat loss to ecologically valuable habitats in the WCA or WBA. The actual operation phase footprint (i.e. land directly and permanently lost by the project) will be approximately 4.0 hectares (primarily Aquaculture Ponds with a very small area of drainage channel). This change in habitat use will occur within the WCA as a result of the land used for the construction of residential blocks, associated structures and access roads and storage areas for materials and equipment etc. However the loss of water body is compensated by re-profiling the ponds in the WNR area. This creates ecologically enhanced and enlarged ponds, and recreated marshland habitat. The construction and ongoing management of these habitats (as outlined in the HCMP) is anticipated to fully compensate any potential loss of wetland ecological function arising from the effects of the residential development. In particular management will be focused on maintaining the population levels of key Species of Conservation Importance, including waterbirds. Consequently under the proposal there is no net loss of water body area or ecological function. No additional habitat loss is anticipated as a result of the construction of either sewerage strategy or the preferred (southern) access route.

13.7.10   No habitats will be lost in their entirety or in any significant proportion.

13.7.11   An integral component of the proposal is the development of a Wetland Nature Reserve (WNR) on the remaining 76.1 hectares of the site. The creation of the WNR will involve the transformation of approximately 14.4 hectares of aquaculture ponds to freshwater marsh and the enhancement (through enlargement) of 61.7 hectares of aquaculture ponds. Whilst intended to compensate for impacts arising from the construction of the residential component of the development and, therefore, expected to have overall positive benefit, the WNR works will involve permanent and temporary habitat loss of aquaculture ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds) and ditches and drainage channels.

Habitat Fragmentation

13.7.12   Construction of the proposed development along the southern edge of the study site is not likely to result in significant fragmentation of habitat areas either within the study site or from other wetland areas in the WCA, the WBA and Ramsar site or other identified sensitive ecological receivers. Construction may create a temporary barrier to dispersal particularly for small vertebrate species such as amphibians and small mammals utilising the mosaic of habitats in the southwest. This area consists of a mosaic of small ponds, drainage channels, wet agriculture and reedbed. No additional habitat fragmentation is anticipated as a result of the construction of either sewerage strategy or the preferred (southern) access route.

13.7.13   The egretry at Shing Uk Tsuen was located to the south west of the Proposed Development Area within an area of Fung-shui woodland. Construction of the development at this originally proposed location would have directly obstructed flightlines and reduced sightlines between the egretry and fishpond foraging areas. The preferred development options (1A and 1B) have been relocated to reduce this effect. The dramatic reduction in flightline obstruction achieved through this relocation is illustrated in Table 1335. Several conservative assumptions made in this analysis probably, however, result in an over-estimate of flightline obstruction including:

·        All flightlines intersecting with the footprint of the proposed Development Area will be completely obstructed. In practice it is anticipated that open space within the development will provide opportunities for passage, although this effect is expected to be small; and,

·        Birds will not modify their flightlines to pass around the development to forage in the ponds beyond. In practice it is expected that birds may take a more circuitous route to access food resources. The magnitude of this effect is not known.

 

Table 1335     Comparison of Potential Affect on Egretry Flightlines of Alternative Development Scenarios

 

Original location

Preferred option

(Relocated 150m eastwards)

Number (percentage) of flightlines from egretry intersecting with Proposed Development Area

330 (65%)

120 (24%)

 

13.7.14   The abandonment of the egretry (see Anon 2005) is expected to significantly reduce the number of flightlines passing through the proposed development area, there being less reason for birds to move between Fung Lok Wai and the South-western part of the Assessment Area. There is no indication that the flightlines of other species are likely to be significantly affected by the construction or operation of the residential development as the numbers of other (non-ardeid) species observed during flightline surveys was relatively very low (see Tables 13-33 and 13-34), this includes Great Spotted Eagle, Imperial Eagle, Crested Serpent Eagle and Osprey.

13.7.15   Options 1A and 1B are similar in many respects, the only slight difference between these two options arising from the larger number of buildings in Option 1B. The buildings in Option 1A will be slightly higher (14-18 stories) than those proposed in Option 1B (all 15 stories). It is considered that the effects of reducing the spacing of buildings will reduce sightlines to a greater extent than the slight differences in building height proposed. On this basis it is concluded that Option 1B will have a slightly greater impact, with respect to this effect, than Option 1A.. It is emphasised that the difference between these options is slight, particularly in light of the abandonment of the egretry, as it was the potential blockage of flights to and from this feature that was the principal source of concern with respect to habitat fragmentation, and neither are expected to cause significant barrier effects to ardeids or any other species, including raptors.

Disturbance

13.7.16   General disturbance effects are widely recognized and have been documented in the past (e.g. Hockin et al. 1992). Such effects may include the complete avoidance of an area (which is therefore comparable to habitat loss) and reduced densities (e.g. where only certain less-sensitive or accustomed individuals use the area). Other less-obvious disturbance effects may include reduced habitat quality through reduced feeding efficiency (e.g. because of a need for increased vigilance), which may in turn lower survival rates or breeding output. Care must therefore be taken in interpreting the observation of a species close to a disturbance source as being evidence that there is no disturbance effect. On the other hand, the observation that there is a disturbance effect, may not necessarily mean that this results in a population impact, as animals may, for example, move to alternative areas if suitable habitat is in excess (i.e. populations are not at carrying capacity).

13.7.17   According to Hill et al. (1997) the severity and overall impact of disturbance (at least on birds) is likely to depend on the following factors:

·        Intensity of disturbance;

·        Duration and frequency of disturbance (continuous, infrequent, regular, variable);

·        Proximity of source;

·        Seasonal variation in sensitivity of affected species;

·        Presence of people associated with the source;

·        Whether animals move away, but return after disturbance ceases;

·        Whether important numbers are affected;

·        Whether there are alternative habitats available nearby;

·        Whether rare, scarce or especially shy species are affected.

13.7.18   In particular, disturbance impacts are normally greatest when they are close and frequent. Although, some species can adapt to regular disturbances from noise and moving machinery, the close proximity of people is rarely adapted to. Thus, species tend to show increasing responses across a gradient of severity, from passive-low-level and continuous to active-high-level continuous (Hockin et al. 1992).

13.7.19   Although the long-term aim of the design of the WNR is to enhance the area for wildlife, the construction of the development and the proposed enhancement works will cause both permanent and temporary disturbance impacts to Species of Conservation Importance utilising the assessment area. Potential disturbance impacts will include:

·        Permanent disturbance from normal residential activities such as noise and visual disturbance from people, vehicles and pets.

·        Permanent disturbance from fishpond management activities, however this level of disturbance activity will be lower than currently exists on site, due to a reduction in fishpond operation recommended under the proposed management strategy, though this may be offset by an increase in visitors to the reserve.

·        Permanent disruption of a proportion of flightlines to and from the egretry (now abandoned) due to the location of the residential units and access road.

·        Disruption of flightlines and temporary noise and visual disturbance to birds during construction of residential units.

·        Temporary direct disturbance to individual ponds during the improvement of fishponds within the WCA.

·        Temporary noise and visual disturbance to the fishpond area from site traffic during construction of the development and Wetland Nature Reserve.

13.7.20   Noise level measurements carried out as part of this assessment indicate that predicted unmitigated noise levels during construction of the residential area may exceed noise limits for daytime construction activities as set out in Annex 5 of the EIAO-TM. Predicted noise levels can be brought within the noise limits through appropriate mitigation. However, it is predicted that some noise levels may reach 71-75dB at noise sensitive receivers on the south west boundary (see Section 4). These levels, although within acceptable noise limits, are likely to have some impact on sensitive species.

13.7.21   No additional disturbance is anticipated as a result of the construction or operation of sewerage strategy “A” which will follow existing roads. Sewerage strategy “B” will require some additional construction works to the west of the proposed development area and WNR, however, these works are not expected to create significant additional disturbance because they are: limited in extent; confined to areas that are already disturbed; and, of relatively short duration compared to construction work on the main development.

13.7.22   Construction and operation of the preferred (southern) access route is not expected to cause significant additional disturbance as it will follow existing roads and is remote from the fishpond areas that are considered to be most sensitive to disturbance effects.

Pollution

13.7.23   Fugitive dust emissions from construction activities could result in significant ecological impacts primarily through deposited on nearby vegetation. This can cause vegetation damage, which can have secondary impacts on associated fauna (such as insects and birds).

13.7.24   Dust and exposed earth from construction operations may also enter watercourses through run-off, particularly during heavy rainfall periods. This can lead to high turbidity from soil particles and eutrophication as a result of nutrient enrichment (as phosphates, which are normally the limiting nutrient in freshwater systems, are bound to soil particles). Aquatic macrophytes may be reduced or lost completely as a result of reduced light penetration due to the increased turbidity from soil particles and increased free-floating algae populations following eutrophication. Severe eutrophication can also lead to oxygen depletion and the impoverishment of aquatic animal communities and, in turn, other animals, such as waterbirds, that feed on them. However, as reported under the water quality impact assessment chapter, the water quality in existing watercourses is poor and their ecological quality is low. Ecological degradation of these habitats may not, therefore, occur if pollutant levels in site run-off are not significantly above those of the watercourses, or if the run-off volume is relatively low. Additional sediment inputs, and potential associated additional nutrients loads may, however, have off-site impacts on the Deep Bay mudflats and coastal waters. Mitigation measures must be put in place to prevent adverse impacts on the ecological resources of Deep Bay.

13.7.25   Mitigation measures are designed to strive towards minimal pollution of watercourses from the construction and ongoing operation of the residential development and Wetland Nature Reserve are dealt with in more detail in the water quality chapter of this report.

13.7.26   Spills and run-off from construction sites can sometimes contain high levels of toxic pollutants (such as oil) which can cause direct mortality of plants and animals (in severe cases), sub-lethal impacts (e.g. by reduced breeding success) or indirect effects through impacts on food resources etc. Contamination of watercourses may have off-site effects on ditches, rivers and the valuable estuarine waters and mudflats of Deep Bay.

13.7.27   Bioaccumulation may also occur where toxic substances are passed up the food chain in increasing concentrations. As a result top level predators such as some reptiles, mammals and birds of prey can be particularly susceptible. Again, measures which should be put in place to prevent this impact are described in the water quality chapter of this report.

13.7.28   Mitigation measures, including the provision of twin pipelines will ensure that the impacts of emergency discharge from sewer bursting are controllable and that the need to shut down the pump house or to discharge untreated sewage into natural streams or channels is minimised.

Soil Compaction

13.7.29   During construction, areas of land will be cleared for use as works areas. In addition, during fishpond enhancement work heavy machinery will be required to access areas of the site by tracking along bund ridges of the aquaculture ponds. During this period, some areas of ground, which are currently undisturbed, will be compacted for use as storage areas, vehicle movement or other purposes. Wetland areas into which rain quickly infiltrates, will become hardened and rainfall will wash off, taking sediment with it, to be deposited on land adjacent to the compacted site, or in watercourses. The wetland function of these areas may therefore be lost temporarily. Although the impact is temporary, extensive compaction over a long period will make habitat restoration more difficult because of the need to re-establish the soil base for a wetland area.

Hydrological Disruption

13.7.30   The change in function of 14.4 hectares of aquaculture ponds to freshwater marsh will result in the necessary diversion of a small catchment runoff southwest of the study site to the southeast. The altered route of the catchment runoff should have no negative impact on the hydrology of the site.

13.7.31   Stormwater run-off from the development area will be directed into the fresh water marsh storage through appropriate silt and oil filters and is not expected to adversely affect water quality within this habitat.

Summary

13.7.32   Various types of habitats (those considered to be of moderate value and above) affected by the potential impacts of the proposed development identified above are summarised in Table 1336The significance of these potential impacts are assessed individually in Section 13.8.

13.7.33   The potential impacts under Options 1A and 1B on habitats are similar, although, as indicated above the effects of habitat fragmentation are expected to be slightly greater under Option 1B than 1A.

 

Table 1336     Summary Matrix of Potential Impacts on Various Types of Habitats

Habitat

Habitat loss

Habitat fragmentation

Disturbance

Pollution

Soil compaction

Hydrological disruption

Intertidal forested wetlands

 

 

X

X

 

 

Permanent rivers, streams and creeks

 

 

 

 

 

 

Ditches and drainage channels

X

 

 

 

 

X

Aquaculture pond

X

 

X

X

X

 

Reedbed

 

X

X

X

 

 

Permanent freshwater marsh and pools

 

X

X

X

 

 

Seasonally flooded (wet) agricultural land

 

X

X

X

 

 

Dry agricultural land

 

 

X

X

 

 

Inactive agricultural land

 

 

X

X

 

 

Orchard

 

 

 

 

 

 

Fung-shui woodland

 

(X)*

X

X

 

 

Semi-natural secondary woodland

 

 

X

X

 

 

Plantation woodland

 

 

 

 

 

 

Grassland

 

 

 

 

 

 

Grassland – shrubland mosaic

 

 

 

 

 

 

Landscaped area

 

 

 

 

 

 

Works in progress

 

 

 

 

 

 

Wasteland

 

 

 

 

 

 

Developed area

 

 

 

 

 

 

Note: * only if egretry present

 

13.8          Evaluation of impacts

13.8.1      Options 1A and 1B are considered to be broadly similar in ecological terms. They occupy the same area, hence habitat loss will be the same in each option nor is there considered to be a significant difference between the two options in terms of their potential impacts on sites of conseration importance or the effects of disturbance, pollution, soil compaction or hydrological disruption on habitats. The only slight difference between the options is potential with respect to habitat fragmentation, particularly with respect to the obstruction of the flightlines of birds, and this is considered in more detail below.

Impacts on Site of Conservation Importance

13.8.2      In Section 13.4 the following sites of conservation importance were identified within the north-west New Territories:

·        Inner Deep Bay SSSI

·        Mai Po Inner Deep Bay Ramsar Site

·        Tsim Bei Tsui SSSI and egretry

·        Mai Po Nature Reserve and Mai Po Marshes SSSI

13.8.3      In addition the Study Site is located within the Deep Bay WCA. The Assessment Area is also adjacent to the Hong Kong Wetland Park.

13.8.4      Fung Lok Wai is sufficiently distant from the four key sites of conservation importance in the region that the risk of adverse effects arising from either the construction or operation of the Residential Development is considered to be very low. Disturbance effects caused during construction and operation are not, for example, expected to cause impact even to the most sensitive species beyond 500m from the Proposed Development Area. In Section 12 it was also concluded that there was a very low likelihood of impacts to marine habitats and hence marine components of the Mai Po Inner Deep Bay Ramsar Site and the Inner Deep Bay SSSI.

13.8.5      There will be no permanent habitat loss to ecologically valuable habitats in the WCA or WBA. The actual operation phase footprint (i.e. land directly and permanently lost by the project) will be approximately 4.0 hectares (primarily Aquaculture Ponds with a very small area of drainage channel). This change in habitat use will occur within the WCA as a result of the land used for the construction of residential blocks, associated structures and access roads and storage areas for materials and equipment etc. However the loss of water body is compensated by re-profiling the ponds in the WNR area. This creates ecologically enhanced and enlarged ponds, and recreated marshland habitat. The construction and ongoing management of these habitats (as outlined in the HCMP) is anticipated to fully compensate any potential loss of wetland ecological function arising from the effects of the residential development. In particular management will be focused on maintaining the population levels of key Species of Conservation Importance, including waterbirds. Consequently under the proposal there is no net loss of water body area or ecological function. No additional habitat loss is anticipated as a result of the construction of either sewerage strategy or the preferred (southern) access route.

13.8.6      The construction of the WNR adjacent to the Hong Kong Wetland Park is considered to be a positive feature as these two sites will collectively increase the availability of wetland habitat managed explicitly for conservation purposes in this part of the north-west New Territories.

13.8.7      Overall the proposed development is expected not to have an impact on sites of conservation importance.

Habitat Impacts

13.8.8      The project will transform approximately 80.1 hectares of fishponds into a Residential Development and a Wetland Nature Reserve with, overall, a greater variety of wetland habitats and associated flora and fauna than that which currently exists. The WNR will be actively managed in the short and long term, for the benefit of Species of Conservation Importance identified utilising the site as well as other species associated with the Deep Bay environment.

13.8.9      The improvement of these habitats will inevitably result is some short-term disturbance while habitats are modified, restored and created. The impacts on habitats identified in the previous section that will be partially lost/changed or fragmented during this process, and those habitats that support Species of Conservation Importance that may be lost, changed or fragmented, are assessed in Table 1337 to Table 54. In addition, all other habitats of moderate or high value have been assessed according to the criteria outlined in Annex 8 of the EIAO – TM.

Habitat Loss

13.8.10   Construction and operation of the proposed development will result in temporary loss of habitats in the WCA due to the operational phase footprint. This will impact aquaculture ponds (a habitat that incorporates fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds) and a small area of Ditches and Drainage Channels. However there is no net loss of water body due to pond re-profiling and enhancement works. The impacts to these habitats are assessed below.

 

Table 1337     Summary of Impacts to Aquaculture Ponds from Habitat Loss

Criteria

Remarks

Habitat Quality

High

Species

Numerous Species of Conservation Importance (particularly waterbirds) are associated with fishponds

Size/abundance

Approximately 4.0 hectares lost to the development. Within the proposed WNR approximately 14.4 hectares will be permanently converted to freshwater marsh and approximately 61.7 hectares subject to pond enhancement resulting in temporary loss during the construction phase

Duration

Aquaculture ponds within development area will be permanently lost. Those ponds converted to freshwater marsh will be permanently lost (considered to be of higher ecological value) and those subject to enhancement works will be temporarily lost during the construction phase, however there is no net loss of water body due re-profiling of ponds creating enlarged ponds (of higher ecological value)

Reversibility

Impact is irreversible for those ponds lost to development and converted to freshwater marsh. Impact is reversible for those ponds subject to enhancement works

Magnitude

High

 

Table 1338     Summary of Impacts to Ditches and Drainage Channel from Habitat Loss

Criteria

Remarks

Habitat Quality

Low

Species

The drainage channels on site are of low water quality and support no Species of Conservation Importance

Size/abundance

There are approximately 0.4 hectares of ditches and drainage channels within the WNR, of these approximately 0.02 hectares will be lost. Other sections will be modified to facilitate drainage within the WNR

Duration

Permanent loss of approximately 0.02 hectares, temporary disturbance to remaining sections during WNR construction phase

Reversibility

Impact is irreversible

Magnitude

Low.

 

Habitat Fragmentation

13.8.11   Some habitats located in the south-western part of the assessment area form a mosaic of wetlands that are of value to some fauna groups including invertebrates, amphibians and reptiles. With regard to habitat fragmentation, this mosaic of habitats is assessed as a single block (Table 13‑39). In addition the construction of the residential development will cause some fragmentation of the linkage between the egretry at Shing Uk Tsuen and the Fung Lok Wai fishponds through flightline interference, although it is now apparent that this egretry has been abandoned. This impact is assessed in Table 13‑40 in light of the decision to relocate the development eastwards specifically to avoid flightlines.

13.8.12   Prior to construction fencing will be erected around the perimeter of the site. Within construction areas, works area hoarding will also be erected. Perimeter fencing will comprise a chain link fence to prevent unauthorised access to the site. The fence will not be a completely impervious barrier to wildlife, there will be gaps associated with access routes and small animals, such as reptiles and amphibians are expected to pass through the fence unhindered. Birds will be able to pass over the fence and, as it is chain link, it will not obstruct site lines. There is potential, however, for the fence to obstruct the movement of medium and large mammals, such as Eurasian Otter (Lutra lutra) and Crab-eating Mongoose (Herpestes urva). These impacts are considered separately below under Impact on Species of Conservation Importance.

 

Table 1339     Summary of Impacts to Wetland Mosaic Habitats (Including Wet Agriculture, Reedbed, and Freshwater Marsh) from Habitat Fragmentation

Criteria

Remarks

Habitat Quality

Mixed:Reedbed – low

                Seasonally flooded agricultural land – moderate

                Permanent freshwater marsh and pools – low to moderate

Species

The mosaic of wetland habitats is of value to fauna groups such as invertebrates, amphibians and reptiles. For the majority of this mosaic the existing direct linkage to Fung Lok Wai fishponds will be retained.

Size/abundance

The area of this wetland mosaic is approximately 4.9 hectares. This area will remain intact and most of it will retain direct linkage to the proposed WNR. The eastern-most part of the mosaic will loose direct connection to the Fung Lok Wai fishponds following construction of the residential development. This area will, however, still retain linkage to other parts of the mosaic.

Duration

Permanent

Reversibility

Impact is irreversible

Magnitude

Low due to maintenance of links with proposed freshwater marsh.

 

Table 1340     Summary of Impacts to Fung-shui Woodland from Habitat Fragmentation

Criteria

Remarks

Habitat Quality

Low to Moderate (but high if egretry is present)

Species

Woodland comprises mixture of native and planted tree and shrub species. The value of this woodland derives, however, from its use as a nesting site (egretry) by species such as, for example, Little Egret and Chinese Pond Heron. This egretry is now abandoned.

Size/abundance

1.3 hectares of woodland. A survey undertaken in June 2001 indicated that the egretry possessed up to 74 nests located within approximately 0.2 ha of the woodland. More recent inspections indicate that the egretry has  been abandoned

Construction and operation of the proposed development and WNR will not result in further isolation of the Fung-shui Woodland. Potential impacts on the egretry are considered separately below under Impact on Species of Conservation Importance

Duration

None

Reversibility

No impact

Magnitude

No Impact

Impact on herons and egrets using egretry is considered below under Impact on Species of Conservation Importance.

 

13.8.13   In this section Options 1A and 1B are considered to be similar in many respects, the only slight difference between these two options arising from the larger number of buildings in Option 1B. The gaps between buildings will be smaller in this option creating a slightly greater blockage of sightlines for birds. It is predicted, therefore, that Option 1B will result in slightly greater habitat fragmentation than Option 1A. It is emphasised that the difference between these options is slight, particularly in light of the abandonment of the egretry, as it was the potential blockage of flights to and from this feature that was the principal source of concern with respect to habitat fragmentation. Flight line surveys undertaken at the proposed development area did not indicate significant levels of flight for any other bird species and so there is no indication that either option would significantly impact the flightlines of any bird species.

Disturbance

13.8.14   Disturbance can be caused during construction and operation phases. Disturbance primarily affects animal species and these impacts are considered in more detail below. For some habitats, however, their importance is largely derived from the species they support. At Fung Lok Wai this includes Aquaculture Ponds and Fung-shui Woodland. The impact of disturbance on these habitats could be significant if it resulted in their supporting reduced populations of Species of Conservation Importance. Disturbance effects arising from glare (sunlight reflecting from glass surfaces during the daytime) and night-time lighting are included in this section. It is expected that light disturbance will only potentially affect bird species. Effects on other species are not expected to be significant.

13.8.15   With respect to glare, as discussed in Chapter 11, construction activities will not extend into the night so night glare during this phase will be very limited. During the operational phase, night-time lighting levels are also expected to be low. The residential development landscape will not require 24 hour lighting except for the lighting of access roads and emergency access.  Any potential effects of lighting at low levels will be reduced through the use of the proposed landscape buffer along the periphery of the development and roadside planting. The effect of glare at these lower levels can also further reduced through the use of full cut off lighting.

13.8.16   The intensity, luminance and lighting level generated from residential properties is also predicted to be relatively low. The effects of glare (during the day and at night, at all building levels) are considered to be part of the disturbance that will result in the exclusion and disturbance distances identified for individual bird species (see below). It is not predicted that the effects of lighting at night at higher levels of buildings would cause disturbance beyond these disturbance distances.

 

Table 1341     Summary of Impacts to Aquaculture Ponds from Disturbance

Criteria

Remarks

Habitat Quality

High

Species

Disturbance during construction and operation of the residential development will cause impact to Species of Conservation Importance utilising this habitat, in particular wetland bird species and large birds of prey.

Size/abundance

Assessments of the sensitivity of bird species to disturbance including analysis of disturbance effects (see below) indicates that, during construction, the effects of disturbance on the most sensitive species may be detectable up to 500m from source with exclusion expected within 200m. For most species, however, these distances will be lower.

 

During operation, levels of disturbance are expected to be lower and hence disturbance effects for most species will be more limited in their extent.

 

In evaluating the magnitude of disturbance effects, consideration has been given to noise, human presence, daytime glare(from reflective surfaces which may increase the visibility of the residential development during the daytime) and nightime glare (it is assumed that lighting will increase the visibility of buildings at night). The magnitude of glare effects is not expected to be large, the development is located in the south-eastern part of the assessment area, consequently the periods when sunlight will be reflected onto fishpond areas will be limited. Nightime glare is not expected to affect large areas of fishponds as the intensity of lighting used in residential developments is relatively low.

Duration

The total construction period for the proposed development is approximately 6 years. During this period the level of disturbance is expected to be discontinuous depending on the specific activities being undertaken (see Chapter 5 for details of noise assessment). The most significant noise generating activities include site formation and foundation works (including piling). The greatest noise levels will, therefore, tend to be experienced in the early stages of construction.

 

Light pollution, to the exent that it will affect fauna, will persist for the lifetime of the development.

Reversibility

Reversible

Magnitude

High

 

Table 1342     Summary of Impacts to Fung Shui Woodland (Including Egretry) from Disturbance

Criteria

Remarks

Habitat Quality

Low to Moderate (High if egretry present)

Species

The egretry within the Fung-shui Woodland is used by some bird species, including Little Egret and Chinese Pond Heron, for nesting

Size/abundance

A survey undertaken in June 2001 indicated that the egretry possessed up to 74 nests located within approximately 0.2 ha of the woodland. More recent inspections indicate that the egretry has been abandoned.

Duration

The total construction period for the proposed development is approximately 6 years. During this period the level of disturbance is expected to be discontinuous depending on the specific activities being undertaken (see Chapter 5 for details of noise assessment). The most significant noise generating activities include site formation and foundation works (including piling). The greatest noise levels will, therefore, tend to be experienced in the early stages of construction.

 

Any disturbance during the breeding season (March to August) will be most significant

Reversibility

It is not known to what extent any potential abandonment of the egretry (if present) could be reversed

Magnitude

Low (The potential impact of disturbance on the egretry (if present) could be high).

 

The relocated development now lies, at its closest point, 200m from the previous location of the egretry. If the egretry were to re-establish it is possible, considering the sensitivity of the likely nesting species, that noise and vibration created during construction could cause some disturbance. It is unlikely, however, that the operation of the development will cause significant disturbance to any nesting birds. The development has been relocated eastwards to minimise potential flight barrier effects

 

Table 1343     Summary of Impacts to Intertidal Forested Wetland from Disturbance

Criteria

Remarks

Habitat Quality

Moderate to high

Species

No Species of Conservation Importance are likely to be affected

Size/abundance

The majority of this habitat is considered too remote from the construction site to be adversely affected by disturbance effects

Duration

A small area of this habitat (<1 ha.) is located within 400m of the western part of the proposed construction site. During the early phases of construction it is possible that some disturbance could be experienced within this habitat although the impact is considered to be low

Reversibility

Reversible

Magnitude

Low

 

Table 1344     Summary of Impacts to Wetland Mosaic Habitats (including Wet Agriculture, Reedbed, and Freshwater Marsh) from Disturbance

Criteria

Remarks

Habitat Quality

Low to moderate

Species

The mosaic of wetland habitats is of value to fauna groups such as invertebrates, amphibians and reptiles. These species are not considered to be sensitive to disturbance effects

Size/abundance

Approximately 4.9 ha.

Duration

Construction and operation phase

Reversibility

Reversible

Magnitude

Low

 

Table 1345     Summary of Impacts to Dry/Inactive Agricultural Land from Disturbance

Criteria

Remarks

Habitat Quality

Low to moderate

Species

No Species of Conservation Importance are likely to be affected

Size/abundance

Small

Duration

Construction and operation phase

Reversibility

Reversible

Magnitude

Low

 

Table 1346     Summary of impacts to Semi-natural Secondary Woodland from Disturbance

Criteria

Remarks

Habitat Quality

Low to moderate

Species

No Species of Conservation Importance are likely to be affected

Size/abundance

Small

Duration

During construction phase

Reversibility

Reversible

Magnitude

Low

 

Pollution

13.8.17   The impacts of potential pollution events arising from the construction and operation of the development on habitats are considered below. The magnitude of the impact pollution events will depend on the nature of the pollutant, its source and the duration of the event.

13.8.18   During construction the main potential source of pollution is from fugitive dust, accidental release of fuel, accidental release of other chemicals associated with construction activities and sediment dispersal from exposed ground.

13.8.19   During operation, the main potential source of pollution impact will arise if a sewage pipe bursts or an emergency by-pass of the sewage pump house is required. The preferred option for the disposal of sewage is Strategy A2 described in Chapter 8. New sewage pipes laid under this strategy (and Strategy A1) follow existing roads and avoid sensitive habitats. In any event the use of twinned sewage pipes will enable the impacts of sewer bursts to be controlled. The risk of significant impact arising from pollution due to pipe failure is, therefore, considered to be extremely small.

13.8.20   Strategy B follows a western route and would involve the laying of pipes beneath the freshwater marsh and adjacent to several Aquaculture ponds to the west of the WNR. As in Strategy A, the use of twinned pipes will enable control of sewage in the event of a burst pipe. Whilst the risk is low, the magnitude of any impact arising because of a sewage leak along this route would be greater than for Strategy A2 (or A1) due to the proximity of sensitive habitats. On ecological grounds, therefore, Strategy A2 is preferred.

13.8.21   All strategies, however, involve the construction of an on-site sewage pump house. In the event of an emergency or power failure, sewage may need to be diverted past this station. To avoid potential impact a by-pass pipe will be installed to direct sewage to the Tai River via Channel “X” thus avoiding the potential for contamination of sensitive freshwater marsh and Fish Pond habitats of the WNR.

13.8.22   There is also potential for light pollution during operation. Sunlight reflecting from glass surfaces during the daytime and from lighting at night could disturb birds. This affect has already been considered under potential disturbance impacts above.

 

Table 1347     Summary of Impacts to Aquaculture Ponds from Pollution

Criteria

Remarks

Habitat Quality

High

Species

Pollution caused by release of toxic chemicals could have a direct impact on bird Species of Conservation Importance that use this habitat.

Size/abundance

Although there are about 170.6 ha. of Aquaculture ponds within the assessment area, a relatively small proportion of these lie adjacent to the development area or in areas that could be affected by residential development construction activities. Construction activities within the WNR primarily involve pond re-profiling and are unlikely to pose a significant pollution risk.

 

The main pollution risk to bund vegetation is from fugitive dust during construction works. If dust is released it is likely to affect a large area depending on its source and prevailing wind directions.

 

No Aquaculture Ponds lie adjacent to the route of sewage strategy A2 (or A1). Three Aquaculture Ponds lie adjacent to Strategy B in the western part of the assessment area.

Duration

Construction and operation phase

The effects of pollution are likely to be persistent, particularly if toxic chemicals are involved or if the pollutant has a tendency to bioaccumulate

Reversibility

Generally reversible although duration of recovery will depend on the nature of the pollutant and the magnitude of the event. No highly toxic pollution events are anticipated however

Magnitude

Low under preferred sewage strategy (A2)

Potentially moderate to large under sewage strategy B, in the event of a sewer pipe burst

 

Table 1348     Summary of Impacts to Fung-shui Woodland (including Egretry) from Pollution

Criteria

Remarks

Habitat Quality

Low (High if egretry present)

Species

Species of Conservation Importance, including nesting herons and egrets, could potentially be affected

Size/abundance

A survey undertaken in June 2001 indicated that the egretry possessed up to 74 nests located within approximately 0.2 ha of the woodland. More recent inspections indicate that the egretry has been abandoned.

 

The main pollution risk to the Fung-shui Woodland (and egretry if present) is from fugitive dust during construction works. Potentially all of the 1.25 hectares of Fung-shui woodland is at risk from dust pollution, although the magnitude of this risk will depend on the dust source and prevailing wind directions.

Duration

Construction phase only. Impacts that occur during the egret breeding season (if egretry present) would be of greater magnitude

Reversibility

Largely reversible – any impacts to egretry (if present) may be irreversible

Magnitude

Low (High if egretry present)

 

Table 1349     Summary of Impacts to Intertidal Forested Wetland from Pollution

Criteria

Remarks

Habitat Quality

Moderate to high

Species

Species of Conservation Importance could potentially be affected

Size/abundance

45.3 ha. present within the Assessment Area.

The risk of chemical pollution to this habitat is low due to its remote location from the construction site and proposed sewer strategies.

The main pollution risk, therefore, is fugitive dust during construction works. If dust is released it is likely to affect a large area depending on its source and prevailing wind directions.

Duration

Construction phase only

Reversibility

Reversible

Magnitude

Moderate

 

Table 1350     Summary of Impacts Wetland Mosaic Habitats (including Wet Agriculture, Reedbed, and Freshwater Marsh) from Pollution

Criteria

Remarks

Habitat Quality

Low to moderate

Species

Species of Conservation importance could potentially be affected

Size/abundance

The small wetland mosaic in the south-western part of the assessment area is located close to the proposed construction site of the residential development. All of this mosaic is potentially at risk from accidental pollution events during construction

During operation there is a small risk of pollution arising from contamination by sewage in the event of a pipe burst. Neither of the strategies considered, however, involve placing pipes in close proximity to these habitats and, in any event the use of twinned sewage pipes ensures that any burst is controllable

Duration

Construction and operation phase

The effects of pollution are likely to be persistent, particularly if toxic chemicals are involved or if the pollutant has a tendency to bio-accumulate

Reversibility

Generally reversible although duration of recovery will depend on the nature of the pollutant and the magnitude of the event. No highly toxic pollution events are anticipated however and the risk of large scale pollution events due to dust or sediment dispersal is considered low

Magnitude

Moderate

 

Table 1351     Summary of Impacts to Dry/Inactive Agricultural Land from Pollution

Criteria

Remarks

Habitat Quality

Low to moderate

Species

No Species of Conservation Importance are likely to be affected

Size/abundance

The main pollution risk to the small areas of this habitat within the assessment area is from fugitive dust during construction works. The magnitude of this risk will depend on the dust source and prevailing wind directions

Duration

Construction phase only

Reversibility

Reversible

Magnitude

Moderate

 

Table 1352     Summary of Impacts to Semi-natural Secondary Woodland from Pollution

Criteria

Remarks

Habitat Quality

Low to moderate

Species

No Species of Conservation Importance are likely to be affected

Size/abundance

The main pollution risk to this habitat is fugitive dust during construction works. If dust is released it is likely to affect a large area depending on its source and prevailing wind directions

Duration

Construction phase only

Reversibility

Reversible

Magnitude

Moderate

 

Soil Compaction

13.8.23   The use of heavy machinery during construction works could result in the compaction of soils on the bunds associated with the existing aquaculture pond bunds.

 

Table 1353     Summary of Impacts to Aquaculture Ponds from Soil Compaction

Criteria

Remarks

Habitat Quality

High

Species

No Species of Conservation Importance likely to be affected

Size/abundance

Potentially affects those pond bunds that will not be removed during construction within the development area and conversion of aquaculture ponds to freshwater marsh.

 

A large proportion of the remaining pond bunds could be affected by soil compaction associated with the use of heavy machinery during the removal and modification of pond bunds associated with pond enhancement works

Duration

Construction phase only

Reversibility

Reversible

Magnitude

Low

 

Hydrological disruption

13.8.24   The proposed development will involve the diversion of some existing Ditches and Drainage Channels. As these habitats were found to be of low quality and the extent of habitat affected is low, the impact of hydrological diversion to this habitat is also considered to be low.

 

Table 1354     Summary of Impacts to Ditches and Drainage Channels from Hydrological Disruption

Criteria

Remarks

Habitat Quality

Low

Species

The drainage channels on site are of low water quality and support no Species of Conservation Importance

Size/abundance

Approximately 0.02 hectares will be removed and a short stretch will be diverted. Remaining stretches will be used to manage water levels within the proposed WNR

Duration

Permanent

Reversibility

Impact is irreversible

Magnitude

Low

 

Summary of Potential Impacts on Habitats During Construction

13.8.25   There will be no net loss of water body in the WCA or WBA. Permanent habitat loss of aquaculture ponds due to the development footprint will be compensated by re-profiling aquaculture ponds, thus creating enlarged ponds of higher ecological value, and freshwater marsh, also of higher ecological value. The pond enhancement works are likely to cause some compaction of bunds during construction activities, particularly in relation to the removal and modification of bunds during the WNR development. The significance of this impact is, however, considered to be low in light of the low intrinsic value of bunds within the aquaculture pond habitat.

13.8.26   No significant habitat fragmentation is anticipated as a consequence of the proposed development. The potential for obstruction of flightlines of any herons and egrets that may nest at the egretry at Shing Uk Tsuen (now apparently abandoned) is considered under Impacts on Species of Conservation Importance below

13.8.27   The major effect of disturbance caused by construction of the proposed development will be on sensitive bird species. During construction, areas of Aquaculture Pond habitat close to the Proposed Development Area are expected to support significantly reduced populations of wetland Species of Conservation Importance, this potential impact is considered in more detail under Impacts on Species of Conservation Importance below.

13.8.28   There is a potential risk of pollution to some habitats through, for example, accidental releases of chemicals or dust during construction. The habitats most at risk from accidental release of pollutants such as fuel or chemicals are those in the immediate vicinity of the development area or that are linked to the development area hydrologically. These include Aquaculture Ponds, Drainage Ditches and Channels and Wetland Mosaic Habitats (including Wet Agriculture, Reedbed, and Freshwater Marsh).

13.8.29   Most habitats within the assessment areas are at some risk from the effects of fugitive dust created during construction activities, including, potentially, Aquaculture Ponds, Intertidal Forested Wetland and Fung-shui Woodland. The potential impacts of smothering from dust are considered to be moderate because, whilst they may be locally intense, they are also temporary in nature and reversible.

13.8.30   During construction the potential effects of Options 1A and 1B are considered to be the same.

Summary of Potential Impacts on Habitats During Operation

13.8.31   The key potential impacts associated with the operational phase of the development include disturbance, habitat fragmentation and pollution arising from operation of the sewerage system.

13.8.32   During operation areas of Aquaculture Pond habitat close to the Proposed Development Area are expected to support significantly reduced populations of wetland Species of Conservation Importance, due to disturbance caused by human presence, noise and lighting. This potential impact is considered in more detail under Impacts on Species of Conservation Importance below.

13.8.33   The presence of tall built structures could obstruct flightlines of birds, particularly herons and egrets and reduce accessibility to important feeding areas. This potential impact is considered in more detail under Impacts on Species of Conservation Importance below.

13.8.34   The risk of pollution from the operation of the sewerage system is considered to be low. Under the preferred strategy (A2) new sewer pipes will follow existing roads, furthermore the use of twinned pipes will ensure that the possibility of significant leakage is minimised in the event of a pipe burst. Under strategy B the same precautions would be taken but the proximity of the pipe route to sensitive Aquaculture Pond habitat means that the consequences of a leak, although unlikely, would be more significant.

13.8.35   In the event of an emergency by-pass of the sewage pump house, sewage would be directed to the Tai River via a pipe to Channel X. Although this would avoid disposing of untreated sewage to sensitive habitats within the WNR, there would be short-term intensive impact to a short stretch of Ditches and Drainage Channel habitat, a habitat of low intrinsic value. There would also be a temporary impact to the Tai River (Permanent Rivers, Streams and Creeks habitat). Dilution effects, the existing poor water quality of the Tai River and the expected short duration of by-pass events ensure, however, that long-term significant impact to this habitat is unlikely.

13.8.36   The potential effects of Options 1A and 1B during the operational phase are considered to be similar in many respects, the only slight difference between these two options arising from the larger number of buildings in Option 1B. The gaps between buildings will be smaller in this option creating a slightly greater blockage of sightlines for birds. It is predicted, therefore, that Option 1B will result in slightly greater habitat fragmentation than Option 1A. It is emphasised that the difference between these options is slight, particularly in light of the abandonment of the egretry, as it was the potential blockage of flights to and from this feature that was the principal source of concern with respect to habitat fragmentation.

Assessment of Potential Impacts on Species of Conservation Importance

13.8.37   The assessment of impacts on habitats above indicates that there are effects arising from the construction and operation of the proposed development that will have an impact on animal species, in particular:

·        Habitat loss;

·        Disturbance caused by the construction and operation of the proposed development, including mitigation associated with the construction of the Wetland Nature Reserve (WNR). In order to minimise the effects of habitat loss and disturbance key works associated with the WNR will be undertaken before the commencement of construction of the residential development. The potential disturbance associated with these works is also considered in this section; and,

·        Fragmentation – in particular the obstruction of flightlines of birds moving to and from the egretry.

Habitat Loss

13.8.38   It is anticipated that the key habitat likely to be directly affected by the proposed residential development is Aquaculture Ponds. It is predicted that approximately 4.0 ha of aquaculture ponds will be permanently lost within the Development Area. In addition there will be temporary habitat loss during the construction of the WNR arising from:

·        Construction of the Marsh Habitat and the approximately 1 year of establishment required for this habitat (approximately 14.4 ha).

·        Enlargement of ponds, which will involve the simultaneous temporary drainage of 2 or 3 ponds to enable bund removal and re-profiling.

13.8.39   The relative timing of the construction of the key elements of the WNR and the residential development is shown in Figure 13‑13. The construction of the WNR is divided into Sectors as described in Section 13.9. At each stage the maximum area of pond unavailable due to construction works is shown along with the remaining area unaffected by construction works. During construction the period during which the most area is unavailable (approximately 22.2 ha) is between April 2011 and October 2011  when the Development Area, the Marshland (which will be establishing) and some Sector 3 ponds will be concurrently unavailable. This represents a maximum temporary loss of approximately 28% of the total wetland habitat present within the Study Site.

13.8.40   The species most likely to be affected by permanent and temporary habitat loss are birds, particularly waterbirds. It is envisaged that there will be adequate remaining wetland within the Study Area, and adjacent areas, to accommodate birds permanently displaced from the Development Area (which represent approximately 5% of the total wetland area within the Study Site) and temporarily displaced from the Aquaculture Ponds and WNR construction areas. To ensure that the carrying capacity of the remaining wetland areas is sufficient for these species an interim management programme will be implemented intended to significantly improve feeding opportunities for waterbirds, particularly ardeids (see below).

13.8.41   It is anticipated that permanent and temporary habitat loss will reduce the availability of foraging habitat for Imperial Eagle, Great Spotted Eagle and Osprey. The significance of this impact is considered to be low due to the scarcity of these species at Fung Lok Wai and their large foraging ranges. This conclusion is reached on the basis of the following:

1)      During the 12 months baseline survey there were very few records of these species within the survey area. In fact there were no records of Great Spotted Eagle or Osprey utilising habitats within the proposed areas for the Residential Development nor the WNR. These species were either observed overflying the general Fung Lok Wai area or were observed within the wider assessment area (ie within the 500m buffer around the EIA study area WNR). It is clear, therefore, that the 12 months survey did not find any evidence that these species have any particular reliance upon the ponds potentially affected by the proposed Residential Development or WNR. As indicated for other species there is no indication that the importance of these ponds would have increased in importance during the period since the 12 months survey was undertaken (see Appendix 13-12).

2)      To the extent that Imperial Eagle, Great Spotted Eagle and Osprey are likely to forage within the study area, then it has been assumed in the EIA report that noise and human presence will cause disturbance during construction and operation. The magnitude of the displacement effect arsing from this disturbance is evaluated in Table 1356 (construction) and Table 1357(operation) (see below). For the purpose of these evaluations it has been assumed that raptors are amongst the most sensitive species present and that any effect would detectible upto 500m from the source of disturbance. These tables, in summary, indicate that the maximum area of habitat affected would be 51.4 ha during construction and operation for each of the three species. As indicated above though this represents displacement from an area upon which these species show little reliance.

3)      The effect of this displacement on Imperial Eagle, Great Spotted Eagle and Osprey is not considered to be of anything other than low significance because:

·         None of these species shows great reliance upon the habitats potentially affected

·         There is extensive alternative habitat for these species within the New Territories – all three species forage over large areas. EPD indicate that the extent of freshwater wetland in Hong Kong is approximately 10,000ha and the area affected by this development, therefore, represents about 0.5%. This does not take account of inter-tidal habitats that these species may also rely upon.

·         The mitigation proposed for the construction and operational phases aims, in any case, to increase the numbers of wetland birds within those areas that are not affected by operational disturbance. This will include waterfowl that comprise prey for the eagle species and fish, that are preyed upon by Osprey.

13.8.42   Crested Serpent Eagle is less dependent on wetland habitats than the other raptor species recorded.  The significance of permanent and temporary habitat loss for Crested Serpent Eagle is, therefore, considered to be very low.

13.8.43   It is considered that the impacts of both Options 1A and 1 B will be similar with respect to habitat loss for these raptor species.

13.8.44   There are several Species of Conservation Importance that are dependent on bund habitats, the most important of which are, Red-billed Starling, Collared Crow and Cattle Egret. The development of the WNR will result in the removal of some bunds (as indicated in Figure 14‑6). The potential impact of bund removal on these species is considered to be of low magnitude, however, for the following reasons:

·        Red-billed Starling and Collared Crowe were recorded in relatively low numbers within the study site. Extent of bund habitat is unlikely to be the key limitiation on the population size of these species.

·        Cattle Egret were recorded in highest numbers in the north-western part of the study site on ponds that are adjacent to the Tai River, the location where there would be no bund removal works (see Figure 14‑6).

13.8.45   The other Species of Conservation Importance potentially affected by the construction of the Residential Development and the WNR are reptiles. The effects on these species are considered to be of low magnitude because:

·        The works will be undertaken progressively ensuring that the area affected at any one time is relatively small.

·        There are abundant areas of alternative habitat for these species.

·        The baseline surveys established that the key areas of importance for these species tended to be located in the buffer zone (ie outside the Development Area and location of the WNR).

13.8.46   It is considered that the impacts of both Options 1A and 1 B will be similar with respect to habitat loss for all Species of Conservation Importance.

Disturbance

13.8.47   Disturbance can arise from works associated with the construction of the Residential Development and the WNR. In addition it is anticipated that there will be disturbance arising from the ongoing operation of the Residential Development, although this is expected to be of a lesser magnitude than that arising from construction activities. The operation of the WNR is expected to be beneficial for Species of Conservation Importance

13.8.48   The species most likely to be affected by disturbance impacts are Species of Conservation Importance birds (particularly flock feeding waterbirds, larger herons and birds of prey), and to less of an extent, reptiles. Such species are likely to be disturbed by loud noises, moving objects, the presence of people, glare from reflective surfaces and night-time lighting. Stationary objects such as buildings are also sources of disturbance as these may obscure flight lines and views of potentially approaching predators. Other species that could be affected are mammals. However, no large mammals were recorded during the field surveys and therefore particular attention will be focussed on bird Species of Conservation Importance recorded on site.

13.8.49   An assessment of the predicted impacts of disturbance on each Species of Conservation Importance that regularly occurs in significant numbers has been carried out. The assessment is based on a combination of literature review, analysis of field survey data and experience of the study team and previously accepted assessment criteria. The magnitude of disturbance effects, including night-time glare, has been evaluated on the basis of disturbance distances. It has been assumed that disturbance effects (including night-time glare) will result in a zone around the residential development where sensitive species will: a) be excluded; and b) occur in reduced densities. The effects of night glare are integrated into the assessment because it is assumed that the extent of the exclusion or reduced density zones will be maintained through the day and night (24hrs). During the day noise and human presence are expected to be the main disturbance factors, at night light will be a factor. As light will not be directed into the WNR, there is no reason to believe that the magnitude of light glare would exceed that of day-time disturbance effects. In fact, there is evidence that artificial light can benefit some birds, including waders. Wading birds that feed by sight, for example, use artificial illumination of foraging habitats to extend the period within which they able to forage. Disturbance impacts have been calculated by defining distance from the edge of the disturbance source to the furthest point of:

·        An exclusion zone – the area adjacent to the source of disturbance and from which a species are expected to be completely excluded; and

·        A zone of reduced density – Where the numbers of a species are lower than they would be in the absence of disturbance either because it occurs in lower numbers (more tolerant individuals) and/or for a shorter period of time (for example during periods of reduced human activity).

13.8.50   The distances at which these effects occur vary from species to species, depending on their sensitivity as indicated in Table 1353.

13.8.51   Subsequent assessments of disturbance effects on Species of Conservation Importance are based on the extent of habitat loss, or functional habitat loss, arising because species are excluded from, or occur in reduced densities within, habitats that would be otherwise suitable for them. The extent functional habitat loss will be greater for more sensitive species than it is for species that are considered to disturbance tolerant. The extent of functional habitat loss has been calculated by assuming that the utilisation of habitats within the exclusion zone is 0%. In other words the functional habitat loss in this zone is 100%. Beyond this, in the zone of reduced density, utilisation is considered to be 50% of that within undisturbed areas (based on the assumption that there will be 0% utilisation at the border with the avoidance zone rising to 100% utilisation at the border with the undisturbed areas). The overall extent of functional habitat loss is, therefore, calculated by adding 100% of the area within the exclusion zone + 50% of the area within the zone of reduced density. The extent of habitats affected in this way have been calculated using GIS.

13.8.52   This approach is used because it provides an integrated way of considering all disturbance effects, including, for example, noise, human presence, day-time glare and night-time lighting effects. The approach is conservative because the disturbance distances are considered to be cautious.

13.8.53   The predicted disturbance distance for regularly occurring Species of Conservation Importance are shown in Table 1355 and presented in Figure 13‑12.

 

Table 1355     Predicted Disturbance Impacts from the Construction and Operation of the Residential Development on Regularly Occurring Species of Conservation Importance at Fung Lok Wai

 

Construction phase

Operation phase

 

Sensitivity to disturbance

 

Exclusion distance (m)

Max distance of reduced density (m)

Exclusion distance (m)

Max distance of reduced density (m)

Black-faced Spoonbill

200

400

100

200

High

Greater Spotted Eagle

200

500

200

500

Very High

Imperial Eagle

200

500

200

500

Very High

Red-billed Starling

100

200

50

100

Moderate

Common Teal

100

300

50

100

Moderate-High

Eurasian Wigeon

100

300

50

100

Moderate-High

Osprey

200

500

200

500

Very High

Black Kite

50

100

20

30

Low

Chinese Pond Heron

100

300

20

30

Moderate

Great Cormorant

200

400

100

150

High

Great Egret

200

400

100

200

High

Little Egret

100

400

20

100

Moderate-High

Black-crowned Night Heron

50

100

20

30

Low

Cattle Egret

50

100

20

30

Low

Grey Heron

100

300

20

30

Moderate

Striated Heron

100

300

20

30

Moderate

Collared Crow

50

100

20

30

Low

Crested Serpent Eagle

200

500

200

500

Very High

Little Grebe

100

200

50

50

Moderate-High

Little Ringed Plover

100

200

50

50

Moderate-High

Pied Kingfisher

50

100

20

30

Low

Temminck’s Stint

100

200

50

50

Moderate-High

White-throated Kingfisher

50

100

20

30

Low

Wood Sandpiper

100

200

50

50

Moderate-High

 

13.8.54   Analysis of the susceptibility of Species of Conservation Importance to disturbance above indicates that four species of raptor Imperial Eagle, Greater Spotted Eagle, Osprey and Crested Serpent Eagle and three species of large waterbird, Black-faced Spoonbill, Great Cormorant and Great Egret are most susceptible. 

13.8.55   Of these species, the four birds of prey range widely in the Deep Bay area and are known to exhibit marked avoidance of man-made structures. Single individuals of Imperial Eagle, Greater Spotted Eagle, Crested Serpent Eagle and Osprey were recorded flying over Fung Lok Wai on a maximum of three occasions throughout the twelve months of survey and hence are not considered likely to have a significant dependence on the site. In addition results of a recent survey of Imperial and Greater Spotted Eagle (KCRC & BBVHK 2002) indicate that these species have a significant preference for managed wetland (e.g. Mai Po) and neither showed a significant preference for fishpond habitat.

13.8.56   The key habitat for the remaining species within the assessment area are Aquaculture Ponds.

13.8.57   Construction activity associated with the Residential Development will commence during the second half of 2013. The construction of the residential development will result in the permanent loss of approximately 4.0 ha of aquaculture ponds. During the early stages of construction the created Freshwater Marsh habitat will not be fully established and this area (approximately 14.4 ha) is also assumed to be temporarily unavailable.

13.8.58   In addition, it is anticipated that disturbance caused, primarily by human presence, noise and vibration during the construction of the residential development will result in a reduced density of birds adjacent to the development. The maximum distance of reduced density (as indicated in Table 1355) is expected to be 500m for the most sensitive Species of Conservation Importance (for example, Osprey) and 100m for the least sensitive (including, for example, White-throated Kingfisher). The additional temporary habitat loss caused by construction activities associated with the construction of the residential development will range, therefore, between approximately 33.0 ha and 2.0 ha depending on the sensitivity of the species. Taking into account the loss of approximately 4.0ha due to the construction of the Residential Development and the temporary unavailability of approximately 14.4 ha during construction of the Freshwater Marsh area, this amounts to between 51.4 ha and 20.4 ha, respectively. It should be noted, however, that these figures are considered to be over-estimates. It is unlikely that development will proceed in all parts of the development area simultaneously reducing the area affected by disturbance at any one time.

13.8.59   Table 13‑56 identifies the permanent and temporary habitat loss during the construction phase for each of the regularly occurring Species of Conservation Importance. These impacts have been calculated on the assumption that there will be low level visual human disturbance and that basic mitigation measures, including the creation of wetland habitats with reedbeds and the planting of trees and bamboo as screening will be implemented.

 

Table 1356     Habitat Loss During the Construction Phase on Regularly Occurring Species of Conservation Importance at Fung Lok Wai

Species

Maximum distance of reduced density during construction (m)

Permanent habitat loss (ha)

Temporary habitat loss due to marsh construction (ha)

Temporary habitat loss due to construction disturbance (ha)

Maximum area of habitat affected (ha)

Black-faced Spoonbill

400

4.0

14.4

23.4

41.8

Greater Spotted Eagle

500

4.0

14.4

33.0

51.4

Imperial Eagle

500

4.0

14.4

33.0

51.4

Red-billed Starling

200

4.0

14.4

6.4

24.8

Common Teal

300

4.0

14.4

12.0

30.4

Eurasian Wigeon

300

4.0

14.4

12.0

30.4

Osprey

500

4.0

14.4

33.0

51.4

Black Kite

100

4.0

14.4

2.0

20.4

Chinese Pond Heron

300

4.0

14.4

12.0

30.4

Great Cormorant

400

4.0

14.4

23.4

41.8

Great Egret

400

4.0

14.4

23.4

41.8

Little Egret

400

4.0

14.4

19.9

38.3

Black-crowned Night Heron

100

4.0

14.4

2.0

20.4

Cattle Egret

100

4.0

14.4

2.0

20.4

Grey Heron

300

4.0

14.4

12.0

30.4

Striated Heron

300

4.0

14.4

12.0

30.4

Collared Crow

100

4.0

14.4

2.0

20.4

Crested Serpent Eagle

500

4.0

14.4

33.0

51.4

Little Grebe

200

4.0

14.4

6.4

24.8

Little Ringed Plover

200

4.0

14.4

6.4

24.8

Pied Kingfisher

100

4.0

14.4

2.0

20.4

Temminck’s Stint

200

4.0

14.4

6.4

24.8

White-throated Kingfisher

100

4.0

14.4

2.0

20.4

Wood Sandpiper

200

4.0

14.4

6.4

24.8

 

13.8.60   Once construction of the residential development is complete it is anticipated that there will be ongoing disturbance, at a significantly reduced level, associated with the operation of the site.

13.8.61   For the purposes of this assessment the operational phase disturbance impact has been estimated on the basis of the disturbance distances (operation phase) in Table 1353 The distances of reduced density are considered to be lower for the key species listed than during the construction phase. This is because:

·        The intensity of noise and vibration during ongoing use are expected to be much lower than during construction which requires the use of heavy machinery;

·        Noise and vibration tend to be more continuous than during construction and some level of habituation is expected; and,

·        There will be screening at ground level reducing the visibility of residents to birds within the WNR.

13.8.62   In addition it has been assumed that the area of the residential development (4.0 ha) is unavailable and that the created marsh habitat (c. 14.4 ha) will continue to be unavailable. In practice though it is expected that the marsh habitat will be fully established by the time that the development is occupied and will provide additional habitat for the Species of Conservation Concern potentially affected by disturbance effects. Consequently the following assessment of disturbance impacts during operation is highly precautionary. The expected habitat loss predicted during the operation phase is indicated in Table 1357.

 

Table 1357     Habitat Loss during the Operation Phase on Regularly Occurring Species of Conservation Importance at Fung Lok Wai

Species

Operation phase max distance of reduced density (m)

Permanent habitat loss (ha)

Temporary habitat loss during marsh establishment (ha)

Functional habitat loss due to operational disturbance (ha)

Total (ha)

Black-faced Spoonbill

200

4.0

14.4

6.4

24.8

Greater Spotted Eagle

500

4.0

14.4

33.0

51.4

Imperial Eagle

500

4.0

14.4

33.0

51.4

Red-billed Starling

100

4.0

14.4

2.0

20.4

Common Teal

100

4.0

14.4

2.0

20.4

Eurasian Wigeon

100

4.0

14.4

2.0

20.4

Osprey

500

4.0

14.4

33.0

51.4

Black Kite

30

4.0

14.4

0.8

19.2

Chinese Pond Heron

30

4.0

14.4

0.8

19.2

Great Cormorant

150

4.0

14.4

4.5

22.9

Great Egret

200

4.0

14.4

6.4

24.8

Little Egret

100

4.0

14.4

1.8

20.2

Black-crowned Night Heron

30

4.0

14.4

0.8

19.2

Cattle Egret

30

4.0

14.4

0.8

19.2

Grey Heron

30

4.0

14.4

0.8

19.2

Striated Heron

30

4.0

14.4

0.8

19.2

Collared Crow

30

4.0

14.4

0.8

19.2

Crested Serpent Eagle

500

4.0

14.4

33.0

51.4

Little Grebe

50

4.0

14.4

1.1

19.5

Little Ringed Plover

50

4.0

14.4

1.1

19.5

Pied Kingfisher

30

4.0

14.4

0.8

19.2

Temminck’s Stint

50

4.0

14.4

1.1

19.5

White-throated Kingfisher

30

4.0

14.4

0.8

19.2

Wood Sandpiper

50

4.0

14.4

1.1

19.5

13.8.63   In the absence of mitigation, the potential impacts of the proposed development on Species of Conservation Importance due to habitat loss and disturbance are likely to be significant. The magnitude of these impacts is greatest during construction but the effects will be temporary. During operation the magnitude of impacts on Species of Conservation Importance is less but the effects will be permanent, although over time it is expected that bird populations will habituate to disturbance to some extent.

13.8.64   A key aspect of this proposal is the construction of a WNR to compensate for impacts associated with habitat loss and disturbance. The strategy, programme and specific actions associated with the construction and operation of the WNR are addressed in detail in Section 13.9 (Mitigation). That section also identifies likely disturbance effects that potentially arise from the construction of the WNR itself.

13.8.65   It is considered that the disturbance impacts on birds (including raptors) and other wildlife arising from both Options 1A and 1 B will be the same.

Habitat Fragmentation

13.8.66   The impact of any development on bird flight lines is unclear. Birds are extremely mobile and will undoubtedly seek to avoid obstructions. Furthermore, the construction time for a high rise development is typically in the order of months to years providing opportunity for birds, even those that may have habituated to flying certain routes, to find alternative flight lines to foraging or roosting sites.

13.8.67   Surveys of bird flightlines undertaken during the baseline study indicated that the proposed development was in-line with a small proportion of flight paths of birds moving to and from the egretry at Shing Uk Tsuen (located to the south-west of the Study Site). More recent observations now indicate that this egretry has been abandoned (Anon 2005) eliminating potential impacts on this feature. In addition the in-filling of ponds required to enable the construction will reduce flight activity in the area of the proposed Residential Development due to the removal of foraging opportunities in that area (see impacts associated with habitat loss and disturbance).

13.8.68   Analysis of data collected when the egretry was occupied indicated that approximately 24% of observed flightlines originating from, or terminating at, the egretry passed through the zone occupied by the current Proposed Development Area (Figure 13‑11).

13.8.69   Comparison of alternative development options (see section 13.6 above) indicated that it was possible to reduce the potential impact of the residential development on these flightlines by shifting the Development Area eastwards. As a consequence a decision was taken to move the development 150m eastwards of its original location, leading to a reduction in flightline intersection from 65% to 24%. The relocated development area is at the periphery of the study site and does not now, in the absence of the egretry, lie between areas of habitat that are important for waterbirds.

13.8.70   Additionally the following mitigation is also intrinsic to the design of the development:

·        Adoption of a building design that emphasises fewer taller buildings (consistent with height constraints) rather than many smaller buildings. This enables gaps to be maintained between buildings preserving sight lines for birds moving within the site.

·        Construction of a potential alternative egretry within the WNR. The provision of this feature will encourage any nesting birds to occupy a site that is within the central part of the fishpond area, thus potentially eliminating the need for flights through the development area. It should be noted that there is no precedent for the re-establishment of egretries that have been abandoned in Hong Kong (G. Carey, pers comm.).

13.8.71   The results of the flightline surveys (see Table 1333 and Table 1334) indicate that, other than ardeids, there were few flightlines arising from other species passing through the proposed area of the Residential Development. On this basis it is considered that there is no indication that there would be a significant fragmentation effect on any bird species arising from the construction and operation of the Residential Development.

13.8.72   A potential additional effect of the construction of mid-rise buildings relates to the obstruction of sight lines. This would occur if buildings prevented birds seeing habitats that might otherwise seek to forage within. This is primarily likely to affect Greater Spotted Eagle and Imperial Eagle which are likely to perch on higher ground (as found to the south of Fung Lok Wai) prior to foraging over wetland areas. This effect is likely to be of lesser importance for Crested Serpent Eagle which is less reliant on wetland habitats than Greater Spotted Eagle and Imperial Eagle. It is of least importance to Osprey which does not typically seek out higher ground for any purpose.

13.8.73   The significance of the potential impact arising from the blockage of sight lines is considered to be low for Greater Spotted Eagle and Imperial Eagle due to their demonstrated low reliance upon the wetland habitats at Fung Lok Wai. It should be noted that baseline ornithological surveys included hillside habitats (Transect 6) and raptors (including the eagle species) were rarely recorded in this area.

13.8.74   With respect to Crested Serpent Eagle and Osprey the potential effect is considered to be insignificant due to the behaviour of these species which implies that sightline blockage will be negligible.

13.8.75   Although both Option 1A and 1B involve the construction of mid-rise buildings, there will be a greater number of more closely spaced buildings in Option 1B than in Option 1A. Conversely the buildings in Option 1A will be slightly higher (14-18 stories) than those proposed in Option 1B (all 15 stories). It is considered that the effects of reducing the spacing of buildings will reduce sightlines to a greater extent than the slight differences in building height proposed. On this basis it is concluded that Option 1B will have a slightly greater impact, with respect to this effect, than Option 1A. It should be noted, however, that the potential impact of both options is considered to be low for Greater Spotted Eagle and Imperial Eagle and insignificant for Osprey and Crested Serpent Eagle.

13.8.76   In light of the relocation of the development, the abandonment of the Shing Uk Tsuen egretry, the proposed mitigation and the likely reduction in flight activity within the proposed Residential Development Area once the existing ponds have been in-filled (to enable construction), it is anticipated that the effect of flightline obstruction will be minor. In Option 1B the gaps between buildings will be smaller than in Option 1A creating a slightly greater blockage of sightlines for birds. It is predicted, therefore, that flightline obstruction (and hence habitat fragmentation) in Option 1B will be slightly greater than in Option 1A. It is emphasised, however, that the difference between these options is slight, particularly in light of the abandonment of the egretry, as it was the potential blockage of flights to and from this feature that was the principal source of concern.

13.8.77   There is no indication that the construction of the residential development would result in the fragmentation of the habitat for any animal species (other than birds). The location of the development, at the periphery of the wetland area, will not create a barrier to the movement of wildlife associated with wetland habitats (or any other habitat type). In this resect there is no difference between Options 1A or 1B and both are considered to have an insignificant impact with respect to habitat fragementation for non-avian species.

13.8.78   Another potential source of fragmentation that could affect Species of Conservation Importance is the erection of fencing around the perimeter of the site and the erection of works area hoarding around construction areas.

13.8.79   Perimeter fencing will comprise a chain link fence to prevent unauthorised access to the site. The fence will not be a completely impervious barrier to wildlife, there will be gaps associated with access routes and small animals, such as reptiles and amphibians are expected to pass through the fence unhindered. Birds will be able to pass over the fence and, as it is chain link, it will not obstruct site lines. There is potential, however, for the fence to obstruct the movement of medium and large mammals, such as Eurasian Otter (Lutra lutra) and Crab-eating Mongoose (Herpestes urva).

13.8.80   Neither species was observed during the baseline surveys, but they are known to be present in similar habitats in the Deep Bay area. Whilst there is potential for fencing around the site to obstruct the movement of species such as these, the magnitude of this impact is not expected to be high as existing security fencing to the north-west and north-east of the site (along the banks of the Shan Pui River) has already effectively isolated Fung Lok Wai from potential adjacent habitats for these species. Nevertheless some reduced movement of medium to large mammal species is anticipated between Fung Lok Wai and adjacent habitats due to perimeter fencing.

13.8.81   The erection of works area hoarding is not anticipated to cause impact to wildlife by obstructing movement as it will be located around areas within which construction is taking place and which are not expected (once works commence) to provide habitat for any Species of Conservation Importance.

Other Species

13.8.82   Five non-bird Species of Conservation Importance were identified in low numbers within the Assessment Area, Banded Krait, Common Rat Snake, Indo-Chinese Rat Snake, Many-banded Krait and Mangrove Water Snake (see section 13.6). Of these Common Rat Snake (Ptyas mucosus), Indo-Chinese Rat Snake (Ptyas korros) and Mangrove Water Snake are expected, on the basis of their habitat preferences and baseline survey data, to have the greatest reliance on the area of fishponds that will be enhanced during construction of the Wetland Nature Reserve. The other snake Species of Conservation Importance tended to show a greater preference for mangrove, hillside and agricultural habitats that will be unaffected by the proposed development.

13.8.83   The sensitivity of reptile Species of Conservation Importance is not known. It is expected that these species will avoid areas close to the development area where there is increased human presence and the effects of noise and vibration are likely to be greatest. Given the low observed abundance of these species it is expected, however, that individuals affected by disturbance can readily relocate to other parts of Fung Lok Wai and adjacent suitable habitat that is also present within the 500m Buffer Zone.

Summary of Potential Impacts on Species of Conservation Importance

13.8.84   The key potential impacts on Species of Conservation Importance arising from construction and operation of the Residential Development are permanent and temporary habitat loss. These impacts arise from the permanent conversion of ponds within the Proposed Development Area and disturbance caused by noise and vibration created during construction activities in the first instance and then noise and increased human presence during the occupation (operation) of the development in the long-term. The Species of Conservation Importance most affected by these impacts are expected to be birds. Reptiles, observed to be present only in low numbers, are unlikely to be significantly affected. A summary of the significance of potential impacts on Species of Conservation Importance are presented in Table 13‑58.

 

Table 1358     Significance of impacts on Species of Conservation Importance at Fung Lok Wai

Species of Conservation Interest

Evaluation

Common Name

Scientific Name

Construction Phase Impacts

Operation Phase Impacts

Avifauna

Black-faced Spoonbill

Platalea minor

High

Moderate

Greater Spotted Eagle*

Aquila clanga

Low

Low

Imperial Eagle*

Aquila heliaca

Low

Low

Red-billed Starling

Sturnus sericeus

Low

Low

Common Teal

Anas crecca

Low

Very Low

Eurasian Wigeon

Anas Penelope

Moderate

Low

Osprey*

Pandion haliaetus

Low

Low

Black Kite

Milvus migrans

Low

Low

Chinese Pond Heron

Ardeola bacchus

Moderate

Moderate

Great Cormorant

Phalacrocorax carbo

High

Low to moderate

Great Egret

Egretta alba

High

Moderate

Little Egret

Egretta garzetta

High

Moderate

Black-crowned Night Heron

Nycticorax nycticorax

Low

Low

Cattle Egret

Bubulcus ibis

Low to moderate

Low to moderate

Grey Heron

Ardea cinerea

Moderate

Moderate

Striated Heron

Butorides striatus

Very Low

Very Low

Collared Crow

Corvus torquatus

Very low

Low

Crested Serpent Eagle*

Spilornis cheela

Low

Low

Little Grebe

Tachybaptus ruficollis

Low

Low

Little Ringed Plover

Charadrius dubius

Low

Low

Pied Kingfisher

Ceryle rudis

Very Low

Very Low

Temminck’s Stint

Calidris temminckii

Low

Low

White-throated Kingfisher

Halcyon smyrnensis

Low

Low

Wood Sandpiper

Tringa glareola

Very Low

Very Low

Herpetofauna

Common Rat Snake

Ptys mucosus

Low

Low

Indo-Chinese Rat Snake

Ptys korros

Low

Low

Mangrove Water Snake

Enhydris bennettii

Low

Low

* Survey data indicate that these species only occur in the area occasionally and are unlikely to depend on the site.

 

13.8.85   During baseline surveys the presence of an egrety resulted in concerns about the potential for the construction of the Residential Development to form a barrier to egret flight lines. To address this potential impact a design decision was made to relocate the development to minimise intersection with observed flightlines. In addition the construction of a potential alternative egretry is proposed within the WNR. Recently the egretry has been abandoned and whilst there is little prospect of it becoming re-established it has been decided to retain these mitigation measures.

13.8.86   Fragmentation caused by the erection of site fencing is not expected to cause a significant impact to Species of Conservation of Importance recorded within the site, although it could restrict the movement of species such as Eurasian Otter and Crab-eating Mongoose which, whilst not recorded within the Assessment Area, might be expected to be present.

13.8.87   Options 1A and 1B are similar in many respects, the slight difference between these two options arising from the larger number of buildings in Option 1B. The gaps between buildings will be smaller in this option creating a slightly greater blockage of sightlines for birds. It is predicted, therefore, that Option 1B will result in slightly greater habitat fragmentation than Option 1A. It is emphasised that the difference between these options is slight, particularly in light of the abandonment of the egretry, as it was the potential blockage of flights to and from this feature that was the principal source of concern with respect to habitat fragmentation.

 

13.9          Mitigation Measures

13.9.1      In Section 13.8 five main categories of potential ecological impacts were identified on habitats and Species of Conservation Importance:

·        Temporary habitat loss resulting from construction phase disturbance (particularly noise and vibration).

·        Permanent habitat loss associated with the construction of the residential development. In addition disturbance associated with the operation of the site is expected create an area around the development within which density of sensitive species (primarily birds) will be permanently reduced.

·        Habitat fragmentation arising from the construction of the residential development and erection of fencing.

·        Pollution events arising from construction activities.

·        Pollution events arising from sewerage leaks during site operation.

13.9.2      Of these the permanent habitat loss associated the construction and operation of the residential development is the most significant because it will potentially have a high impact on habitats of high conservation value (aquaculture ponds) and Species of Conservation Importance (including the globally important species Black-faced Spoonbill).

Mitigation of Construction Phase Habitat Loss and Disturbance

13.9.3      The key strategy for mitigating permanent and temporary habitat loss arising from the construction of the Residential Development is the construction and appropriate management of a Wetland Nature Reserve (WNR) within that component of the site (approximately 76.1 ha) not occupied by the proposed residential development. The aim of the WNR is to compensate permanent habitat loss and to mitigate disturbance effects through the creation of approximately 14.4 ha. of freshwater marsh habitat. In addition approximately 61.7 ha of remaining fishponds will be enhanced and managed to increase their carrying capacity for bird Species of Conservation Importance.

13.9.4      The strategy for constructing the WNR has been carefully considered and incorporates the following (strategic) elements:

·        Advance construction. Construction works associated with the WNR will be completed in advance of the commencement of construction at the Residential Development – this minimises concurrent disturbance associated with construction works in these two areas.

·        Staged construction. The construction of the WNR will be staged to minimise the areas affected at any one time. This minimises disturbance effects and ensures that there is always sufficient habitat for birds, and other species, considered to be of Conservation Importance within Fung Lok Wai.

·        Interim management. To ensure that carrying capacity of areas unaffected by construction at any one time are sufficient to maintain populations of bird (and other) Species of Conservation Importance, interim management will be undertaken during WNR and Residential Development construction phases.

·        Long-term management. Once construction works are completed and the Residential Development enters its operational phase, long-term management within the WNR will commence.

13.9.5      The construction programme for the WNR and Residential Development is indicated in Figure 13‑13. The timeframe for these works has been divided into series of Phases, including:

·        Pre-construction Phases I-VI – when WNR works and proposed Development Area site clearance and forming will be undertaken.

·        Construction Phase – when work on the Residential Development foundations and superstructure will take place.

·        Operation Phase – when the Residential Development is occupied and the WNR enters long-term management.

13.9.6      The activities involved in each stage are briefly described below (dates shown are indicative).

Pre-Construction Phase I (Jul ‘10– Sep ‘10)

13.9.7      During this phase the developer will take occupation of the site and make preliminary preparations including erection of site fencing. No specific habitat management is envisaged at this stage and all ponds will remain under their current aquaculture regime. All ponds will potentially be available as habitat that is no ponds will be directly affected by construction activities.

Pre-Construction Phase II (Oct ’10 – Mar ’11)

13.9.8      During this phase pond enhancement works will commence. Enhancement is aimed at improving the quality of ponds as waterbird habitat (as described more fully in Section 14) and involves re-profiling and enlarging the ponds. To minimise disturbance and to maximise the extent of available habitat these works will be undertaken progressively within Sector 1. The works involved in enhancement include the draining of adjacent ponds and the excavation of the intervening bund. This will be done according to the construction plan of the Wetland Nature Reserve (see Section 14). These works are similar to normal pond management activities and are not in themselves expected to cause undue disturbance to birds, nevertheless to minimise potential disturbance impacts, pond enhancement works will be phased.

13.9.9      The maximum area of pond affected by these enhancement activities during this Phase will be 4.2 ha (representing the largest ponds that will be concurrently drained and re-profiled). Prior to, and following enhancement works, the ponds will be filled with water and are considered to be available as habitat for birds and other Species of Conservation Importance.

13.9.10   During these works the ponds located within Sectors 2 and 3, the area proposed for marshland (14.4 ha) and development area (4.0 ha) will remain under their existing management regime ensuring that, throughout this Phase, at least 76.0 ha of pond will remain as available.

Pre-Construction Phase III (Apr ’11 – Sep ’11)

13.9.11   During this Phase enhancement works will commence in Sector 2 and site clearance will commence in the Development Area. The enhancement works in Sector 2 will follow the same pattern as described above, however, the maximum area affected at any one time will be slightly larger at approximately 6.1 ha. Once the Development Area clearance is complete a further, approximately, 4.0 ha of pond habitat will become unavailable. During this Phase, therefore, the minimum pond area available as habitat will be approximately 70.0 ha.

13.9.12   To compensate for this reduction in habitat area it is proposed to commence interim management in the Sector 1 ponds (all of which were enhanced in Phase II). The interim management strategy is to increase the carrying capacity of ponds by drawing them down for longer periods than is normal under traditional management and to artificially increase the availability of prey species for wetland birds through stocking of trash fish species. The key elements of the interim management plan include:

·        Management of water quality, specifically pH to ensure appropriate conditions for fish survival. Although trash fish species are relatively hardy compared to many commercial fish, they can be affected by low pH conditions. If pH drops below 4.5 then peanut residue will be added to raise pH;

·        Rotational, partial drain down of pair ponds. Once drained down each pair of ponds will be maintained with shallow water < 30 cm deep for a period of 4 weeks;

·        Stocking of trash fish as required to ensure that target carrying capacities are met; and,

·        Minimising human presence to limit disturbance.

Pre-Construction Phase IV (Oct ’11 – Mar ’12)

13.9.13   Interim management will continue at Sector 1 (20.4 ha) and commence at Sector 2 ponds (21.3 ha). In addition interim management will also be implemented in Sector 3 ponds (20.1 ha, although these are yet to be enhanced). No pond enhancement works will be undertaken during this Phase. Creation works will commence within the marshland area, while site clearance continues in the development area, making approximately 14.4 ha and 4.0 ha, of pond area unavailable, respectively. Consequently a minimum of 61.8 ha of pond area will be available, all of which will be under interim management.

13.9.14   During this phase the physical activities associated with marsh creation works will be completed with planting taking place in the following Phase.

Pre-Construction Phase V (Apr ’12 – Sep ’12)

13.9.15   Interim management will continue at Sector 1 (20.4 ha) and 2 ponds (21.3 ha).  Ponds in Sector 3 will undergo enhancement occupying a maximum of 3.82 ha at any one time while the remaining 16.2 ha of pond area will be kept under interim management. Planting of marshland habitats will take place followed by approximately 12 months of establishment. For the purposes of this assessment it is assumed during this period that all the marshland habitat (14.4 ha) will be unavailable as habitat (although it is actually likely that some species will begin to make use of it). Site clearance and preparation works will continue in the development area (4.0 ha). Thus a minimum of 58.0 ha of pond area will be available, all of which will be under interim management.

Pre-Construction Phase VI (Oct ’12 – Jun ’13)

13.9.16   Marsh establishment will continue (and hence assumed to be unavailable). Interim management will continue at Sector 1 (20.4 ha), 2 (21.3 ha) and 3 ponds (20.06 ha) resulting in a total area of available pond area of 61.8 ha, all of which is under interim management.

Construction Phase (Jul ’13 – Sep ’16)

13.9.17   Construction works are programmed to commence in July 2013. During this phase all pond enhancement works will be completed and a total area of 61.8 ha of ponds will be under interim management in Sectors 1, 2 and 3.  Marsh establishment is expected to be substantially complete (although maturation will continue over several additional years). Consequently there will be an additional 14.4 ha of marshland habitat available.

13.9.18   The commencement of construction works will result, however, in the generation of substantially higher levels of noise and vibration and hence disturbance than was experienced during Pre-Construction Phases. It is assumed, therefore, that sections of wetland habitat adjacent to the construction area will be functionally unavailable to species that are sensitive to disturbance. The extent of these areas was assessed in Section 13.8 and are summarised in Figure 13‑12 and Table 1355.

13.9.19   The key strategy for mitigating these disturbance effects is to maintain interim management in all of the enhanced Sector 1, 2 and 3 ponds. It is anticipated that interim management will increase the carrying capacity of these ponds sufficiently to off-set temporary functional habitat loss associated with the displacement of birds from areas affected by construction phase disturbance.

13.9.20   The objective, therefore, during this Phase is to provide habitat of sufficient quality to maintain the numbers of birds observed during the baseline. To gain an indication of the existing carrying capacity of the Fung Lok Wai wetlands, the survey data obtained during the baseline survey were analysed to identify the maximum number of birds recorded. These data were then converted to densities by dividing the maximum number of individuals observed within the within the Study Site by the extent of wetland in the Study Site (approximately 80.1 ha). The Study Site sits within a larger area of wetland habitat, for comparison this table also shows the maximum and mean number of individuals of Species of Conservation Importance observed within the total Assessment Area. These are also shown as densities achieved by dividing the counts by the extent of wetland within the Assessment Area (approximately 170.6 ha of wetland). These data are shown in Table 13‑59.

 

Table 1359     Observed maximum, mean (counts and densities) of wetland bird species using the wetland in the Study Site and Assessment Area during 2001

Species

Mean and maximum counts and densities (individuals per ha of wetland habitat) of sensitive species using the wetland in the Study Site and Assessment Area during baseline surveys

Study site

Assessment area

Max

Mean

Max

Mean

Count

Density

Count

Density

Count

Density

Count

Density

Black-faced Spoonbill

38

0.47

2.77

0.03

39

0.23

4.53

0.03

Greater Spotted Eagle

0

-

-

-

2

N/A

N/A

N/A

Imperial Eagle

1

N/A

N/A

N/A

1

N/A

N/A

N/A

Red-billed Starling

12

0.15

1.10

0.01

182

1.07

24.67

0.15

Common Teal

3

0.04

0.20

<0.01

643

3.77

35.47

0.21

Eurasian Wigeon

11

0.14

1.47

0.02

74

0.43

7.73

0.05

Osprey

0

-

-

-

3

N/A

N/A

N/A

Black Kite

18

0.22

1.90

0.02

29

0.17

10.37

0.06

Chinese Pond Heron

42

0.52

11.17

0.14

80

0.47

13.00

0.08

Great Cormorant

24

0.30

4.60

0.06

92

0.54

13.20

0.08

Great Egret

128

1.60

20.87

0.26

132

0.77

24.50

0.14

Little Egret

480

5.99

59.53

0.74

506

2.97

122.73

0.72

Black-crowned Night Heron

40

0.50

6.60

0.08

46

0.27

9.60

0.06

Cattle Egret

68

0.85

16.80

0.21

72

0.42

29.83

0.18

Grey Heron

67

0.84

13.27

0.17

151

1.89

41.73

0.25

Striated Heron

3

0.04

0.37

<0.01

7

0.09

1.03

0.01

Collared Crow

10

0.12

1.10

0.01

18

0.11

8.50

0.05

Crested Serpent Eagle

0

-

-

-

1

N/A

N/A

N/A

Little Grebe

12

0.15

4.17

0.05

42

0.25

21.27

0.13

Little Ringed Plover

30

0.37

2.57

0.03

38

0.22

8.87

0.05

Pied Kingfisher

2

0.02

0.17

<0.01

6

0.04

1.30

0.01

Temminck’s Stint

9

0.11

0.37

<0.01

20

0.12

3.13

0.02

White-throated Kingfisher

6

0.07

1.57

0.02

15

0.09

3.47

0.02

Wood Sandpiper

3

0.04

0.30

<0.01

12

0.07

2.17

0.01

N/A - Indicates that whilst this species was observed during surveys it was seen only in flight over Fung Lok Wai in very low numbers. It was not appropriate to calculate densities for these species

13.9.21   To understand the magnitude of increase of carrying capacity required under the interim management regime the extent of habitat loss has been estimated by calculating the proportion of habitat lost through construction and disturbance during the construction phase (see Table 1360). For these calculations it is assumed that the marsh area is unavailable (hence permanent habitat loss is shown as 18.4 ha, equivalent to the development area, 4.0 ha, and the constructed marsh habitat, 14.4 combined). In practice it is actually assumed that the marsh will be sufficiently mature during this Phase to provide habitat for some of Species of Conservation Importance. Habitat loss is calculated on the basis of the reduced density distances shown in Table 13‑56.

 

Table 1360     Extent and proportion of direct and indirect (due to disturbance) habitat loss during construction for sensitive wetland bird species.

Species

Habitat loss (ha)

Extent of wetland habitat (ha)

Proportion of wetland habitat  affected (ha)

Permanent

Due to disturbance

Max area affected

Study Site

Assessment Area

Study Site

Assessment Area

Black-faced Spoonbill

18.4

23.4

41.8

80.1

170.6

52%

24%

Greater Spotted Eagle

18.4

33.0

51.4

80.1

170.6

64%

30%

Imperial Eagle

18.4

33.0

51.4

80.1

170.6

64%

30%

Red-billed Starling

18.4

6.4

24.8

80.1

170.6

31%

15%

Common Teal

18.4

12.0

30.4

80.1

170.6

38%

18%

Eurasian Wigeon

18.4

12.0

30.4

80.1

170.6

38%

18%

Osprey

18.4

33.0

51.4

80.1

170.6

64%

30%

Black Kite

18.4

2.0

20.4

80.1

170.6

25%

12%

Chinese Pond Heron

18.4

12.0

30.4

80.1

170.6

38%

18%

Great Cormorant

18.4

23.4

41.8

80.1

170.6

52%

24%

Great Egret

18.4

23.4

41.8

80.1

170.6

52%

24%

Little Egret

18.4

19.9

38.3

80.1

170.6

48%

22%

Black-crowned Night Heron

18.4

2.0

20.4

80.1

170.6

25%

12%

Cattle Egret

18.4

2.0

20.4

80.1

170.6

25%

12%

Grey Heron

18.4

12.0

30.4

80.1

170.6

38%

18%

Striated Heron

18.4

12.0

30.4

80.1

170.6

38%

18%

Collared Crow

18.4

2.0

20.4

80.1

170.6

25%

12%

Crested Serpent Eagle

18.4

33.0

51.4

80.1

170.6

64%

30%

Little Grebe

18.4

6.4

24.8

80.1

170.6

31%

15%

Little Ringed Plover

18.4

6.4

24.8

80.1

170.6

31%

15%

Pied Kingfisher

18.4

2.0

20.4

80.1

170.6

25%

12%

Temminck’s Stint

18.4

6.4

24.8

80.1

170.6

31%

15%

White-throated Kingfisher

18.4

2.0

20.4

80.1

170.6

25%

12%

Wood Sandpiper

18.4

6.4

24.8

80.1

170.6

31%

15%

 

13.9.22   It can be seen from Table 1360 that the extent of habitat loss within the study site for the wetland species during construction varies between 25% (for disturbance tolerant species such as Cattle Egret) and 64% for Greater Spotted Eagle, Imperial Eagle, Osprey and Crested Serpent Eagle. These species were observed infrequently, over-head and consequently the reliance of these raptors on Fung Lok Wai is considered low and that the mitigation proposed below for sensitive waterbirds will adequately safeguard habitat for this species, particularly in light of the wider availability of suitable habitat for these species in the North-west New Territories.

13.9.23   The most important conclusion from Table 1360, therefore, is that, habitat availability within the Study Site for the most sensitive waterbirds (Black-faced Spoonbill, Great Cormorant and Great Egret) will be approximately halved during the construction phase.

13.9.24   It should be noted that the figures presented in Table 1360 are highly conservative, they are based on construction activity occurring within the whole of the development area simultaneously, which is unlikely to occur. Rather, construction is expected to proceed in stages with disturbance limited to specific areas of the development area and a significantly smaller area of surrounding wetland. As mentioned above it is also assumed that the constructed marsh does not contribute to available habitat, although in practice it is likely to support some Species of Conservation Importance. It can also be seen from Table 1360 that when the availability of wetland habitat in neighbouring areas (taken as wetland habitat present in the Assessment Area ie Study Site plus 500m buffer) is taken into consideration the extent of habitat loss is significantly less due to the greater availability of habitat within this larger area.

13.9.25   To mitigate the impact of direct habitat loss and disturbance effects, temporary management will be required to increase the carrying capacity within remaining habitat. This management will take place on-site (ie within the Study Site). The mitigation targets for key bird Species of Conservation Importance are indicated in Table 1361 This table shows the increase in the population required to mitigate habitat loss and temporary disturbance effects during the construction phase. Using the results of the baseline surveys the densities (ie birds per hectare of wetland) implied by these mitigation targets are shown. Species with low target densities (including Greater Spotted Eagle, Imperial Eagle, Osprey and Crested Serpent Eagle which recorded very infrequently and have a limited dependence on the site) have not been included in this table. It should be noted that these targets are intended as a reference point to inform the implementation and evaluation of mitigation, which will need to be undertaken using an adaptive management approach.

13.9.26   Targets are shown only for key species in Table 1361. These species have been selected because they are considered to be the most sensitive and abundant waterbird species and hence most susceptible to impacts arising from habitat loss and disturbance. It is expected that habitat management undertaken to achieve the mitigation targets defined for these species will be more than sufficient to mitigate impacts on other species that are less sensitive to disturbance and which occur in lower numbers.

 

Table 1361     Mitigation targets for key wetland bird species of conservation importance within remaining wetland areas of the Study Site required to fully compensate for habitat loss and disturbance impacts during construction

Species

Mitigation target (species population increase)

Implied target densities (birds/ha) using existing baseline data1

Black-faced Spoonbill

Double

0.07

Chinese Pond Heron

Increase by 61%

0.22

Great Cormorant2

Double

0.12

Great Egret

Double

0.54

Grey Heron

Increase by 61%

0.27

Little Egret

Increase by 92%

1.41

Cattle Egret

Increase by 33%

0.28

Notes:

1               The figures included for reference only. The actual mechanism for identifying specific population targets is to be agreed with AFCD prior to the commencement of the construction.

2               If Great Cormorant numbers exceed mitigation targets it may be necessary to implement controls on the size of the population. The implementation of such controls will be determined in the context of the Adaptive Management framework and in discussion with AFCD

13.9.27   In practice, because the populations of these species will fluctuate within the North-west New Territories due to a range of external factors beyond the developers control, the targets densities will be calculated using information obtained from control site locations. These control sites will be established in appropriate locations to be agreed with AFCD prior to the construction of the proposed development. Appropriate locations would include places that are known to support similar communities and populations of birds to those found at Fung Lok Wai. As such, Lut Chau and Nam Sang Wai are the suggested potential control sites. The actual locations of the control sites would be confirmed prior to the construction of the proposed development.

13.9.28   The magnitude of the increase in carrying capacity required is considered to be achievable on a temporary basis because:

·        Existing densities (particularly mean densities) are considered to be low for most of the species listed (see Table 1359), which provides considerable scope for increasing the carrying capacity of ponds within the Study Site through management.

·        Reference to recent monitoring reports from monitoring associated with KCRC East Rail extensions at Lok Ma Chau (AEC 2003, 2004, 2006a, 2006b) indicate that the densities implied for key species (Black-faced Spoonbill, Great Cormorant and Great Egret) are readily achievable (and have been frequently exceeded).

·        Although monitoring at Lok Ma Chau has indicated that numbers of Little Egret and Chinese Pond Heron have tended to fall short of their target numbers for that site (AEC 2006a), the actual densities achieved, particularly for Chinese Pond Heron have often exceeded the specific mitigation target densities at Fung Lok Wai for both construction and operational phases. With respect to Little Egret densities achieved have, in the past, been lower than construction phase mitigation targets at Fung Lok Wai. Within the adaptive management programme for Lok Ma Chau, however, various management actions have been identified to increase numbers and these have had positive results for Little Egret (AEC 2006a). AEC (2006b) further indicates that a density of 2.45 birds/ha has been achieved in Aug-Dec 2005, a considerably higher density than that required to fully compensate construction phase disturbance effects at Fung Lok Wai. The results of monitoring at Lok Ma Chau, and the management required to achieve targets, will continue to be reviewed. Relevant lessons from Lok Ma Chau will be incorporated, where appropriate, within the adaptive management programme for the WNR at Fung Lok Wai.

13.9.29   Under traditional management the production of non-commercial by-product, including prawns and fish, such as Tilapia, that are below marketable weight is in the order of 260 kg/ha/year (See Section 12.4, Aspinwall 1997 and Primavera, 2000). To achieve the mitigation targets the availability of small fish and prawns will need to be increased to provide enhanced feeding opportunities. Experience from the implementation of a similar approach by KCRC at Lok Ma Chau indicates that optimal stocking densities are likely to be in the range 2-5 times the expected ‘normal’ biomass of trash fish, ie up to 1,300 kg/ha/year. Imported fish will comprise small Tilapia (target weight approximately 50g / individual). A key reason for the relatively large increase in stocking density is due to the fact increased prey availability benefits a wide variety of piscivorous birds, including cormorants and ardeids, all of which can be expected to increase in numbers within the mitigation area.

13.9.30   The experience at Lok Ma Chau (eg AEC 2006a, 2006b) also indicates that a flexible (adaptive management) approach is required. The effectiveness of mitigation requires careful attention to water quality, adjustment to stocking densities, periodic review of the timing and duration of draw-down and continuous monitoring.

13.9.31   Not of all of the Species of Conservation Importance recorded within or close to the Study Site are piscivorous birds. It is expected, however, that the programme of pond enhancement and interim management proposed during pre-construction and construction phases will also benefit these species.

13.9.32   Red-billed Starling and Collared Crow tend to be closely associated with bund habitats and adjacent agricultural land-uses. Whilst some bunds will be removed during pond enhancement a substantial proportion will remain intact, sufficient to maintain the low observed densities of these birds. Staging the enhancement works will ensure that the area disturbed during enhancement of the fishponds and the construction of the marsh habitats will be limited.

13.9.33   With respect to raptors, it is considered that the actions taken to maintain waterbird densities during the construction phase, including stocking of ponds with fish species, will off-set potential disturbance effects. The maintenance of waterbird numbers will benefit those species that forage on these (Greater Spotted Eagle and Imperial Eagle) and stocking of fish species will benefit Osprey which is piscivorous. Black Kite is an opportunistic scavenger utilising a wide range of habitats. It is highly tolerant of human presence and is expected to continue to forage within the pond enhancement areas

13.9.34   Waterfowl (Common Teal and Eurasian Wigeon) will forage on vegetation and other food items found at the margins of ponds. It is expected that these species will continue to utilise ponds during the construction phase. If any individuals are displaced from the Study Site due to disturbance it is anticipated that there will be abundant ponds in adjacent areas (ie within the Buffer Zone to the Study Site) to accommodate these birds.

13.9.35   Waders (Little Ringed Plover, Temminck’s Stint and Wood Sandpiper) will forage on invertebrates associated with pond margins, the creation of additional shallows and lengthening of draw-down periods is expected to significantly benefit these species.

13.9.36   Few non-avian Species of Conservation Importance were considered likely to be directly dependent on the ponds within the Study Site, although some reptile species are expected to occur including:

13.9.37   Common Rat Snake (Ptyas mucosus) and Indo-Chinese Rat Snake (Ptyas korros) – are both likely to be found in varied habitats including agricultural areas, shrub land, banks of streams, around aquaculture ponds and reservoirs. Mangrove Water Snake (Enhydris bennettii) is typically found in muddy coastal habitats, although in the baseline surveys for this study it was recorded only once but near fish ponds. It is expected that the staged approach to the enhancement of the ponds and constructed marsh areas within the WNR will ensure that sufficient habitat remains for these species throughout the construction phase.

13.9.38   Banded Krait (Bungarus fasciatus) and Many-banded Krait (B. multicinctus) have little reliance on fishpond habitats are not expected to be adversely affected by construction works.

Mitigation of Operational Phase Habitat Loss and Disturbance

13.9.39   The disturbance generated during operational phase (ie once the Residential Development is occupied and all construction works have ceased) is considered to be significantly lower than during the construction phase.

13.9.40   Table 13‑62 indicates the extent and proportion of direct and indirect (due to disturbance) habitat loss during operation. Habitat low is calculated on the basis of the reduced dernsity distances shown in Table 1353.

 

Table 1362     Extent and proportion of direct and indirect (due to disturbance) habitat loss during operation for wetland bird species

Species

Habitat loss (ha)

Extent of wetland habitat (ha)

Proportion of wetland habitat affected (ha)

Permanent

Due to disturbance

Max area affected

Study Site

Assessment Area

Study Site

Assessment Area

Black-faced Spoonbill

18.4

6.4

24.8

80.1

170.6

31%

15%

Greater Spotted Eagle

18.4

33.0

51.4

80.1

170.6

64%

30%

Imperial Eagle

18.4

33.0

51.4

80.1

170.6

64%

30%

Red-billed Starling

18.4

2.0

20.4

80.1

170.6

25%

12%

Common Teal

18.4

2.0

20.4

80.1

170.6

25%

12%

Eurasian Wigeon

18.4

2.0

20.4

80.1

170.6

25%

12%

Osprey

18.4

33.0

51.4

80.1

170.6

64%

30%

Black Kite

18.4

0.8

19.1

80.1

170.6

24%

11%

Chinese Pond Heron

18.4

0.8

19.1

80.1

170.6

24%

11%

Great Cormorant

18.4

4.5

22.9

80.1

170.6

29%

13%

Great Egret

18.4

6.4

24.8

80.1

170.6

31%

15%

Little Egret

18.4

1.8

20.2

80.1

170.6

25%

12%

Black-crowned Night Heron

18.4

0.8

19.1

80.1

170.6

24%

11%

Cattle Egret

18.4

0.8

19.1

80.1

170.6

24%

11%

Grey Heron

18.4

0.8

19.1

80.1

170.6

24%

11%

Striated Heron*

18.4

0.8

19.1

80.1

170.6

24%

11%

Collared Crow

18.4

0.8

19.1

80.1

170.6

24%

11%

Crested Serpent Eagle

18.4

33.0

51.4

80.1

170.6

64%

30%

Little Grebe

18.4

1.1

19.5

80.1

170.6

24%

11%

Little Ringed Plover

18.4

1.1

19.5

80.1

170.6

24%

11%

Pied Kingfisher

18.4

0.8

19.1

80.1

170.6

24%

11%

Temminck’s Stint

18.4

1.1

19.5

80.1

170.6

24%

11%

White-throated Kingfisher

18.4

0.8

19.1

80.1

170.6

24%

11%

Wood Sandpiper

18.4

1.1

19.5

80.1

170.6

24%

11%

* Habitat loss for Striated Heron will be over-estimated here because this is a species primarily of mangroves and inter-tidal habitats (although it was also recorded in small numbers within the study site)

13.9.41   As for the construction phase the largest exclusion areas predicted are for four raptor species that are considered to have a low dependence on the site. It is assumed that the mitigation proposed for this phase for waterbirds will be more than adequate to compensate habitat loss for these species.

13.9.42   The most important conclusion from Table 13‑62, therefore, is that, habitat availability within the Study Site for the most sensitive waterbirds (Black-faced Spoonbill, Great Cormorant and Great Egret) will be reduced by approximately 30% during the operation phase.

13.9.43   It is anticipated that sympathetic long-term management of the WNR will be more than sufficient to mitigate permanent habitat loss and ongoing disturbance caused by operation of the Residential Development. As a precaution it is assumed that the constructed marsh habitat within the WNR will be unavailable (although in practice it is expected to be fully established after several years). Consequently mitigation has been approached on the basis that mitigation targets will be achieved through enhancement of the carrying capacity of those fishponds unaffected by disturbance effects. The managed carrying capacities required within these fishponds are indicated in Table 1363. Species with low target densities (including Greater Spotted Eagle, Imperial Eagle, Osprey and Crested Serpent Eagle which were recorded very infrequently and have a limited dependence on the site) have not been included in this table. It is considered that the establishment of the WNR will provide, in the long-term, enhanced and secure foraging opportunities for Greater Spotted Eagle, Imperial Eagle and Crested Serpent Eagle and that this will off-set any impacts arising from habitat loss and disturbance due to the construction and operation of either Option 1A or 1B. The area of fish ponds within the WNR will be less than that which currently exists (as approximately 14.4 ha will be converted into freshwater marsh habitats), although those fishponds retained will be enhanced through enlargement and more sympathetic management. Nevertheless, it is considered that there will be a slight reduction in the extent of foraging habitat available for Osprey, although this loss is not considered to be significant in light of the low reliance that this species has on the existing habitats within Fung Lok Wai.

 

Table 1363     Mitigation targets for wetland bird species of conservation importance within remaining wetland areas of the Study Site required to fully compensate for habitat loss and disturbance impacts during operation

Species

Mitigation target (species population increase)1

Implied target densities (birds/ha) using existing baseline data2

Black-faced Spoonbill

Increase by 45%

0.05

Chinese Pond Heron

Increase by 32%

0.18

Great Cormorant3

Increase by 41%

0.08

Great Egret

Increase by 45%

0.37

Grey Heron

Increase by 32%

0.22

Little Egret

Increase by 33%

0.98

Cattle Egret

Increase by 32%

0.27

Notes:

             1               For these calculations it is assumed that mitigation will be achieved only through management to increase the carrying capacity of those fishponds unaffected by operational disturbance

2                      The figures included for reference only. The actual mechanism for identifying specific population targets is to be agreed with AFCD prior to the commencement of construction.

3               If Great Cormorant numbers exceed mitigation targets it may be necessary to implement controls on the size of the population. The implementation of such controls will be determined in the context of the Adaptive Management framework and in discussion with AFCD

 

13.9.44   The key strategy for compensating the functional loss of wetland arising from the ongoing operation of the residential development is the appropriate management of the WNR.

13.9.45   A detailed draft Habitat Creation and Management Plan for the proposed Wetland Nature Reserve (WNR) is provided in Section 14. In summary, though the WNR will comprise two key elements:

·        A large expanse of retained, but ecologically enhanced, fishponds; and,

·        An area of re-created ‘natural’ marshland.

13.9.46   Fishponds that are actively managed for commercial aquaculture in the Deep Bay area are currently full for most of the year and their use by birds is severely limited due to their relatively steep sides, deep water and their frequent lack of marginal vegetation. These characteristics also limit their use by other species and hence fishponds tend to have relatively low biodiversity compared to many wetland habitats.

13.9.47   The management of fishponds for commercial aquaculture, however, creates a key by-product in the form of abundant “trash fish” – small, non-commercial fish and invertebrates.  When ponds are drained down during the winter months for harvesting, large concentrations of birds can be observed foraging in the shallow water for trash fish. As only a small proportion of fishponds are drained at any one time, and only for short periods, the spatial distribution of feeding birds is highly dynamic and variable as birds seek out ponds as they are drained. ‘Feeding bottlenecks’ may occur if there are insufficient ponds to support foraging bird populations.

13.9.48   Although much of the Assessment Area is composed of wetland habitats in the form of aquaculture ponds, poor water quality and unsympathetic pond design severely limit its value for most faunal groups. Furthermore, there is inadequate vegetation cover on the site to support breeding populations of most wetland birds.

13.9.49   The main objectives of enhancing fishponds are, therefore, to:

·        Increase the value of fishponds to herons and egrets outside harvesting periods (i.e. draw-down), by increasing food resources and food availability and by reducing disturbance effects. Enhancement of the value of fishponds to such birds outside harvest periods could reduce the potential for ‘feeding bottlenecks’ thereby possibly reducing the area of fishponds needed to support the population.

·        Increase their overall biodiversity value and suitability for non-piscivorous bird Species of Conservation Importance, non-bird Species of Conservation Importance (e.g. snakes), and other species such as some mammals (e.g. Eurasian Otter), amphibians and reptiles, whilst maintaining their current important functions for herons, egrets and other water birds.

13.9.50   The enhanced fishponds will be located away from the development area to minimise disturbance impacts. They will also be contiguous with the main area of fishponds in the WCA and Ramsar site as a whole. Maintaining a contiguous area for compensation, which is linked, with an existing area of recognised conservation importance is of significant ecological value.

13.9.51   The natural wetland area will consist of a marshland complex, including areas of shallow open mesotrophic water (i.e. of moderate nutrient status), with adjoining reedbeds and other emergent vegetation, shallow margins, islands, irregular shorelines, and an area of seasonally inundated grazed marsh and pools. Such fresh water marshes are a scare habitat in Hong Kong and would develop rich and abundant aquatic and emergent plant communities. This in turn may support rich invertebrate, amphibian and reptile communities.

13.9.52   There are three key features of this proposed layout:

·        The majority of the fishponds on the site are maintained, including all those within the Mai Po Inner Deep Bay Ramsar site boundary. This avoids the loss or detrimental modification of any wetland area within the Ramsar site and maintains the large open contiguous block of fishpond habitat in the area.

·        The location of the proposed area for the re-creation of natural wetlands will maximise the potential for ecological links with the following complementary adjacent habitats:

o        scrub and woodland habitats on the hillsides to the south of the site;

o        inter-tidal mangrove habitats along the former Tai River outfall; and,

o        the wetland creation at Hong Kong Wetland Park (HKWP).

o        These habitats may provide sources for the natural spread and establishment of some plants and animals within the wetland area. In addition they will provide additional shelter, food or breeding sites for wetland species and ecological ‘corridors’, which may facilitate dispersal.

·        As the re-created wetland will contain abundant tall reedbeds, as well as other tall wetland vegetation and scattered trees, this will serve as a buffer between the residential development and the fishponds. This will reduce disturbance of birds feeding within the fishponds.

13.9.53   The specific aquaculture pond habitat targets for the mitigation area are indicated in Table 13‑64.

 

Table 1364     Mitigation Targets for Enhanced Aquaculture Ponds

Mitigation issue

Target

Enhancement of aquaculture pond area

61.7 ha. (Including, control structures and alternative egretry)

Shallow fish pond area (i.e. < 10cm depth)

More than 20% (excluding aquaculture ponds that are dry for maintenance)

Cover of undesirable invasive species and exotic species

Less than 10% of vegetation cover

Plant cover on aquaculture pond bunds and islands

Vegetation of height >10cm to comprise less than 5% plant cover on more than 75% of the area of aquaculture pond bunds and islands

Area under traditional polyculture fish pond management systems

70-90% of the aquaculture pond area

(Excluding aquaculture ponds that are dry for maintenance)

Area set-aside from fish farming and under specific conservation management

10 - 30% of the aquaculture pond area

(Excluding aquaculture ponds that are dry for maintenance)

 

13.9.54   Planting of trees on bunds will be avoided where such planting would interfere with bird flightlines. In addition continuous planting that would enclose or overshadow fishpond or freshwater marsh habitats will also be avoided. To improve foraging opportunities for some bird species (notably passerines such as Red-billed Starling) fruit-bearing trees, including, for example, China-berry (Melia azedarach) will be planted in small clumps.

13.9.55   The specific targets for the Marsh Habitat mitigation area are indicated in Table 13‑65.

 

Table 1365     Mitigation Targets for Marsh Habitat

Mitigation issue

Target

Creation and maintenance of a total of marshland habitat in Favourable Condition

14.4 ha. (including essential structures, e.g. water control structures)

Freshwater marsh habitats are defined as areas where wetland hydrological conditions, or wetland soils are present or where wetland plants are dominant, with shallow water (average < 1m) and wetland plant species cover greater than 30% of the area.

Cover of wetland plant species

More than 90% established vegetation (excluding open water marsh area)

Cover of undesirable invasive species and exotic species

Less than 10% of vegetation cover

The average depth of water

30 – 50 cm (outside drawn down periods for maintenance)

Area of open water (i.e. unvegetated water)

20-30%.

 

13.9.56   As the Marsh Habitat will be new habitat there are no existing animal populations associated with marsh habitats upon which to base mitigation targets. In addition it is anticipated that the Marsh Habitat will be subject to disturbance arising during the operation phase due its proximity to the residential development. Nevertheless there are a range of bird species that would be expected to use the Marsh Habitat. Management of the marsh habitats will focus on ensuring that that these “primary” species (see Table 13‑66) are present. In addition there are a range of other species that are associated with marsh habitats. Whilst it is desirable that these species are present, they will not form the primary focus of management effort. In addition it is expected that the marsh habitat will support a range of amphibian, reptile and invertebrate species.

 

Table 1366   Bird SpeciesExpected to Use the Marsh Habitat

Primary Species

(Presence expected)

Secondary Species

(Presence desirable)

Birds

Little Egret (R)

Chinese Pond Heron (R)

Great Egret (W)

Grey Heron (W)

Eurasian Teal (W)

Black-winged Stilt (W)

Pintail / Swinhoe’s Snipe (P / W)

Common Snipe (W)

Zitting Cisticola (W)

 

Japanese Quail (P / W)

Eurasian Coot (W)

Pheasant-tailed Jacana (P)

Greater Painted Snipe (R)

Black-winged Stilt (B)

Richard’s Pipit (P / W)

Bluethroat (P / W)

Pallas’s Grasshopper Warbler (P)

 

Key: R – resident; W – winter; P – passage; B - breeding

 

Residual Disturbance during Operation of Wetland Nature Reserve

13.9.57   Lockable gates will also be placed on vehicle access points to the site. A 2 m high wall between the development area and the wetland will also prevent direct access except via the designated footpaths.

13.9.58   Fish farming activities within the Wetland Nature Reserve are also a potential source of disturbance within the fishpond areas. These will therefore be reviewed, as part of the development of a management plan for the site, and modified where possible to avoid disturbance impacts.

13.9.59   Human activities along the margins of the site, such as walking along tracks and roads and aquaculture activities on adjacent fishponds may also cause significant disturbance. These would be reduced to acceptable levels by: 

·        Provision of a 2 m high wall between the residential development and wetland area, which itself would be screened from the wetland by tall trees (c. 10 m high);

·        Screening on the perimeter bunds (in aquaculture ponds) through tree and shrub establishment;

·        Additional screening in the wetland itself and on the margins of open water through planting and establishment of wetland species of tree and shrub, bamboo and reed; and,

·        Incorporation of design features such as islands, promontories and inlets of emergent vegetation to provide further security and areas free of disturbance for birds.

13.9.60   Screening of the wetland will, however, be avoided where possible in order to provide clear flight lines and views across to existing surrounding fishponds and hence maintain connection with the wider Deep Bay area.

13.9.61   The long-term management of the WNR is expected to provide benefit to other species in addition to birds. The wider range of habitats that will present within the WNR, particularly with respect to the constructed marsh area is expected to provide improved habitat (over baseline conditions) for species such as:

·        Dragonflies.

·        Amphibians, including, for example: Two-striped Grass Frog (Rana taipehensis).

·        Reptiles, including, for example: Common Rat Snake (Ptyas mucosus) and Indo-Chinese Rat Snake (Ptyas korros).

13.9.62   These species were all recorded in relatively low abundance during the baseline and it is reasonable to expect that the abundance of populations of species in these groups will increase.

Mitigation for Disturbance to Egretry

13.9.63   Habitat fragmentation impacts were anticipated largely in relation to the potential obstruction of heron and egret flightlines originating from an egretry at Shing Uk Tsuen by the proposed residential development. Subsequent to the completion of the baseline surveys, the egretry has been abandoned. In the absence of an egretry it is considered unlikely that the residential development will obstruct flightlines as it is located on the periphery of the wetland area. There is no precedent in Hong Kong for the re-establishment of abandoned egretries, nevertheless several measures will be implemented that will reduce the likelihood that flightlines will be obstructed in the event that herons and egrets resume breeding at Shing Uk Tsuen.

13.9.64   A decision has been made, for example, to relocate the proposed development area. Following relocation the development area is, at its closest point, situated approximately 200m from the previous location of the egretry.

13.9.65   The factors influencing choice of egretry location are not clearly understood. The literature review of the impacts of developments on egretries undertaken as part of the impact assessment process for this site (AEC 2002) indicates some degree of tolerance to existing built structures. Investigations of other egretries located within Hong Kong e.g. the Tai Po Market, indicate that the species nesting therein can tolerate disturbance and adapt to modifications to the existing landscape, although the extent of this tolerance has yet to be quantified.

13.9.66   Whilst no specific information is available on the direct impacts of construction close to egretries, a buffer zone of 200m is considered to be sufficient because:

·        The area immediately adjacent to the egretry is already subject to disturbance. Existing, ongoing human activity close to the egretry, includes housing, roads, tracks, actively managed fishpond and actively managed agricultural land;

·        Construction works will be phased. Construction works in the western most 200m of the Proposed Development Area being undertaken preferentially within periods of egretry inactivity (ie. September to February).

13.9.67   There are also options for reducing potential impact on birds associated with the egretry through the management of habitats within the proposed Wetland Nature Reserve (WNR). It is known, for example, that is possible to artificially create egretries through the planting of appropriate tree, shrub and tall grass species. The successful, early establishment of a potential alternative egretry location within the proposed WNR would compensate for any potential impact caused by construction and subsequent interference with flightlines.

13.9.68   The egretry occupied about 2,000 sq. m of woodland (Figure 13‑8) and it is recommended that any potential alternative egretry be of approximately the same size. The literature review found that the species most commonly associated with egretries in the New Territories include Celtis sinensis, Ficus macrocarpa and Bambusa eutuldoides and it is recommended that planting focus on the establishment of mature specimens of these three species.  It is proposed that the potential alternative egretry be located in the north eastern section of the Study Site which will be subject to minimal disturbance from both the construction and operational stages of the development.

13.9.69   Analysis of GIS data also indicates that, during the breeding season, Little Egret and Chinese Pond Heron are selectively foraging in ponds that have been drained. This observation supports observations made elsewhere (eg Lok Ma Chau and Mai Po) that drawn-down ponds, particularly those which are supplemented with “trash fish” stocks, are sought out by wetland species, particularly ardeids.

13.9.70   Within the proposed management plan for the WNR, therefore, ponds will be deliberately drawn down to provide foraging habitat and to direct birds away from areas that are subject to disturbance or obstruction.

Mitigation for Non-disturbance Impacts

Minimisation of Dust Deposition

13.9.71   Dust deposition is a potential adverse impact in all locations. Dust creation should be minimised using standard procedures, including the damping down through water spraying during periods of dry weather. Details of mitigation measures to be used for minimising dust deposition are included in the Air Quality Impact Assessment.

Minimisation of Increased Sediment Load

13.9.72   The potentially increased sediment load during construction will be controlled and minimised through implementation of good site management practices such as the provision of means for the sediment to settle before discharge of the clear supernatant. During operation, sediment loads are likely to be minimal and any solids will settle in oil interceptors and sediment traps that are incorporated within the drainage system. Effective management and maintenance programmes are expected to adequately control potential impacts from this source.

Minimisation of Pollution

13.9.73   Good storage practices and handling of the chemicals used during the construction period will minimise the opportunity for impact on the terrestrial and aquatic environments. Spillage impacts can be minimised by storing chemicals in appropriate bunkers. Regular maintenance of interceptors will maximise their efficiency in trapping chemicals before release into the environment.

Soil Compaction

13.9.74   Where works is being carried out, there is potential for compaction of the ground surface. The extent of the area to be compacted for works during construction should be minimised to reduce damage to habitats. Unless immediately required as a part of the managed mitigation area or for landscape impact mitigation purposes, each area should be re-instated when the works on that area are complete, to re-establish an environment as similar as possible to the original habitat. This may require excavation, removal of compacted (and polluted) material, and replacement with suitable material for re-creation, particularly in the areas of wetland creation and along bunds (in aquaculture ponds), which are not to be used for vehicle access in the long term.

Bird Strikes with Glazed Blocks

13.9.75   Collisions of birds with built structures are most frequent where buildings or structures are transparent or reflective (i.e. glass) or otherwise difficult to see (e.g. wires). If such structures are avoided then collisions are likely to be infrequent and have minor ecological significance. This issue is taken into consideration in the mitigation of landscape and visual impacts and through the design of the residential blocks and the use of non-reflective glass.

Mitigation for non-bird Species

13.9.76   On the basis of the report section above, it is clear that the principal aim of the mitigation must be the provision of suitable habitats for target species, rather than the restoration of specific habitats of intrinsic value.  The Study Site currently has a low diversity of habitats and non-bird taxa. However, the mitigation proposed has been designed to provide additional habitat and management for non-target species.

13.9.77   The value of the Assessment Area for Odonata is currently limited because of the lack of high quality habitat in the form of fast running freshwater streams and undisturbed marshy areas. With appropriate management however, it is likely that the wetland habitats of the site could sustain a much more diverse odonate fauna and include further species of conservation concern. For example, the rare damselfly Mortonagrion hirosei will be encouraged through the creation of Phragmites reedbed as part of the wetland marsh design.

13.9.78   Several ponds will not be stocked with carnivorous or omnivorous fish which predate Odonata and mayfly larvae. The depth of bunds (in aquaculture ponds) will be reprofiled to create shallow margins that slope gently down to the base of the ponds. This will encourage the establishment of floating and emergent plants which dragonfly larvae are dependent upon. Along the aquatic margin of the ponds a matrix of short and taller emergent vegetation, bare substrate comprising soft mud and marshy area will be created.

13.9.79   The enhanced ponds will include shallow gently sloping areas and deeper steeper areas. This will encourage breeding of amphibians and the lack of predatory fish in some ponds will also benefit amphibians whose larvae are also predated by fish.

13.9.80   Poor water quality and highly modified freshwater habitats severely limit the ecological value of the Assessment Area for native freshwater fish. The sole running water habitat at Fung Lok Wai comprises lowland waterways with a muddy substrate. The value of the area for freshwater fish will be significantly enhanced through design of the freshwater marsh, improvement of water quality, removal of choking aquatic weeds, planting of native species and reduction in the abundance of exotic species.

13.9.81   Mangrove Water Snake was recorded within the area of fishponds that will be enhanced as part of the proposed mitigation for the site. The bunds where this species was recorded will remain intact during the enhancement works.  In addition, earthworks within this area will be undertaken during the fourth quarter to ensure that breeding individuals are not disturbed. Other reptiles will be encourage to use the site through provision of the freshwater marsh which will provide more suitable habitat with the Study Site particular for species of conservation importance only otherwise recorded within the buffer zone of the Assessment Area.

13.9.82   The fishpond areas provide foraging habitat for bat species such as Japanese Pipistrelle and potentially other species including Noctule. Studies have shown that a colony of 100 pipistrelles may need as much as 3km2 of habitat in which to forage (Ades 1990). The proposals for management of the fishponds and the design of the freshwater marsh will increase the diversity of habitats on site for bats and could increase the carrying capacity of the site for small invertebrates, and hence increase the value of the available foraging habitat for these species.

13.9.83   Two other mammal Species of Conservation Importance, Eurasian Otter (Lutra lutra) and Crab-eating Mongoose (Herpestes urva) were not recorded during the twelve months of survey but are known to occur within similar habitats in the Deep Bay area. These species will benefit from the extra cover provided within the freshwater marsh, a reduction in on-site disturbance as a result of the reduction in fishpond operators managing the reserve, and more stringent guidelines on sympathetic management practices.

Summary of compensation levels

13.9.84   Overall levels of compensation predicted from the above proposed compensation measures for Species of Conservation Importance that were recorded during the required survey period are summarised in Table 1367Table 1367

 

Table 1367     The Overall Levels Of Compensation Predicted From Compensation Measures For Species Of Conservation Importance That Were Recorded During The Baseline Surveys At Fung Lok Wai

Species

Sensitivity to disturbance

Compensation achieved

Birds

 

 

Globally Threatened Species

 

 

Black-faced Spoonbill

High

Feeding habitat fully compensated and provided over a longer period; additional secure roosting habitat provided

Greater Spotted Eagle*

Very High

Habitat maintained, enhanced and secured in the long-term

Minor level of habitat fragmentation arising from reduction in sightlines, however, this impact is not considered to be significant in light of the low reliance of this species on this habitat and the availability of suitable habitat elsewhere within Hong Kong

Imperial Eagle*

Very High

Habitat maintained, enhanced and secured in the long-term

Minor level of habitat fragmentation arising from reduction in sightlines, however, this impact is not considered to be significant in light of the low reliance of this species on this habitat and the availability of suitable habitat elsewhere within Hong Kong

Red-billed Starling

Moderate

Habitat maintained and secured in the long-term

Regionally Important Species

 

 

Common Teal

Moderate-High

Key habitat improved foraging opportunities provided and secured in the long-term

Eurasian Wigeon

Moderate-High

Key habitat improved foraging opportunities provided and secured in the long-term

Osprey*

Very High

Partial compensation through provision of larger open areas of managed fishpond a maximum possible distance from the proposed development. Whilst there will be some loss of habitat this is not considered to be significant in light of the low reliance of this species on this habitat and the availability of suitable habitat elsewhere within Hong Kong

Potential Regional concern

 

 

Black Kite

Low

Key habitat improved foraging opportunities provided and secured in the long-term

Chinese Pond Heron

Moderate

Feeding habitat fully compensated and provided over a longer period; additional loafing habitat provided; potential roosting and nesting habitat provided

Great Cormorant

High

Feeding habitat fully compensated; additional loafing habitat provided

Great Egret

High

Feeding habitat fully compensated and provided over a longer period; additional loafing habitat provided

Grey Heron

Moderate

Feeding habitat fully compensated and provided over a longer period; additional loafing habitat provided; potential roosting and nesting habitat provided

Little Egret

Intermediate-High

Feeding habitat fully compensated and provided over a longer period; additional loafing habitat provided; potential roosting and nesting habitat provided

Local conservation concern

 

 

Black-crowned Night Heron

Low

Feeding habitat fully compensated; additional loafing habitat provided

Cattle Egret

Low

Feeding habitat fully compensated; additional loafing habitat provided

Collared Crow

Low

Key habitat improved foraging opportunities provided and secured in the long-term

Crested Serpent Eagle*

Very High

Habitat maintained, enhanced and secured in the long-term

Little Grebe

Moderate-High

Feeding habitat fully compensated; additional loafing habitat provided

Little Ringed Plover

Moderate-High

Key habitat improved foraging opportunities provided and secured in the long-term

Pied Kingfisher

Low

Key habitat improved foraging opportunities provided and secured in the long-term

Striated Heron

Moderate

Primarily a species of mangroves and inter-tidal mudflats. Minimal direct on habitat. in addition additional loafing habitat provided; potential roosting and nesting habitat provided

Temminck’s Stint

Moderate-High

Key habitat improved foraging opportunities provided and secured in the long-term

White-throated Kingfisher

Low

Key habitat improved foraging opportunities provided and secured in the long-term

Wood Sandpiper

Moderate-High

Key habitat improved foraging opportunities provided and secured in the long-term

Reptiles

 

 

Banded Krait

Low

Key habitat unaffected by construction works and operation

Common Rat Snake

Low

Key habitat improved foraging opportunities provided and secured in the long-term

Indo-Chinese Rat Snake

Low

Key habitat improved foraging opportunities provided and secured in the long-term

Many-banded Krait

Low

Key habitat unaffected by construction works and operation

Mangrove Water Snake

Low

Key habitat improved foraging opportunities provided and secured in the long-term

* Survey data indicate that these species only occur in the area occasionally and are unlikely to depend on the site.

 

13.10      Identification and evaluation of residual ecological impacts

13.10.1   An estimate of residual impacts on habitats and species, taking into account the proposed avoidance, minimisation and compensation measures proposed above are summarised in Table 13‑68. The residual effects of Options 1A and 1B are predicted to be similar except in relation to habitat fragmentation.

 

Table 1368     Proposed Mitigation Measures and Predicted Residual Impacts

Potential Impact

Predicted Residual Impact

Habitat loss

The construction of the Residential Development will result in the permanent loss of approximately 4 ha of aquaculture ponds. Enhancement works of remaining ponds within the WNR will ensure, however, that there will be no net loss of either water body area or wetland function. Advance construction of the WNR will ensure that there is sufficient alternative habitat for birds displaced by construction activities.

Interim management of the WNR is expected to fully compensate functional habitat loss caused by the construction of the Residential Development and the WNR itself.

Long-term management of the WNR is expected to fully compensate functional habitat loss caused by the operation of the Residential Development.

No significant residual impacts from direct loss of other habitats are predicted.

Habitat fragmentation

No significant fragmentation of habitats is anticipated through construction or operation of the proposed development.

Some obstruction of flightlines between an egretry at Shing Uk Tsuen and the Fung Lok Wai wetlands was anticipated, although the significance of this impact was not predicted to be high. Following the abandonment of the egretry, however, no impact is now predicted.

Option 1B will result in slightly greater habitat fragmentation than Option 1A. The larger number of buildings in Option 1B is expected to restrict the sightlines of birds to a slightly higher degree than would be the case in Option 1A in either case the impact is not considered to be significant for any species..

Disturbance of wildlife by noise and visual movement

The construction and operation of the residential development and WNR have the potential to disturb sensitive bird Species of Conservation Importance.  Enhancement works of remaining ponds within the WNR will ensure, however, that there will be no net loss of either water body area or wetland function. Advance construction of the WNR will ensure that there is sufficient alternative habitat for birds displaced by construction activities.

Phasing of works will ensure that the area affected by pond enhancement works associated with the construction of the WNR will be small at any one time.

Interim management of the WNR is expected to fully mitigate disturbance effects caused by the construction of the Residential Development and the WNR itself.

Long-term management of the WNR is expected to fully mitigate disturbance effects caused by the operation of the Residential Development.

No significant residual impact from disturbance of other habitats or species other than birds is predicted.

Dust deposition on surrounding habitats

Minimal residual impact is anticipated.

Increased sediment load and pollution of watercourses

Minimal residual impact is anticipated.

Soil compaction

Minimal residual impact is anticipated.

Hydrological disruption

No residual impact is anticipated.

 

13.11      Ecological Monitoring and Audit

13.11.1   The key objective of mitigation is to maintain the functional capacity of the Fung Lok Wai wetlands during construction and operation. This will be achieved during the construction phase through interim management of ponds that are not directly affected by construction activities. The carrying capacity of these ponds will be temporarily increased through management activities known to improve habitat value for these species, primarily this will involve increasing food availability for key piscivorous waterbird Species of Conservation Importance. Mitigation targets have been specified in terms of the proportional increase in the density of Bird Species of Conservation Importance present within the mitigation area required to maintain overall population levels of these species within the Fung Lok Wai Study Area. During the operational phase of the development, disturbance is predicted to be lower and mitigation will be achieved through the long-term management of the WNR. Mitigation targets have also been identified for the same species during this phase. The mitigation targets are summarised in Table 1369. Bird species with low target densities have not been included in this table as the mitigation targets proposed should accommodate these species when accommodating key species which are sensitive and/or have high densities. Banded Krait and Many-banded Krait have been excluded from this table because they have little reliance on fishpond habitats.

 

Table 1369     Mitigation targets for Key Bird Species and other Species of Conservation Importance

Species

Mitigation target (population increase)

Construction phase

Operation phase1

Birds

Black-faced Spoonbill

Double

Increase by 45%

Chinese Pond Heron

Increase by 61%

Increase by 32%

Great Cormorant

Double

Increase by 41%

Great Egret

Double

Increase by 45%

Grey Heron

Increase by 61%

Increase by 32%

Little Egret

Increase by 92%

Increase by 33%

Cattle Egret

Increase by 33%

Increase by 32%

Other species

Common Rat Snake

Present

Present

Indo-Chinese Rat Snake

Present

Present

Mangrove Water Snake

Present

Present

 Note: 1   For these calculations it is assumed that mitigation will be achieved only through management to increase the carrying capacity of those fishponds unaffected by operational disturbance

 

13.11.2   In addition monitoring will seek to establish the presence or absence of the marsh species listed     in Table 13‑66 above.

13.11.3   As indicated previously it is considered that in the period since completion of the baseline surveys that bird activity at Fung Lok Wai is likely to have declined (due to a reduction in management activity and the abandonment of the Shing Uk Tsuen egretry). Pre-construction surveys of bird populations at Fung Lok Wai will be undertaken after obtaining the planning approval and application of the lease modification / land exchange. These surveys will involve monthly counts of each pond within the Study Site for one year prior to the commencement of construction activities. The extent and timing of these surveys will, however, be agreed with AFCD prior to their commencement. All bird species observed within each pond will be recorded. Particular attention will be given to key bird Species of Conservation Importance that are specifically identified in the mitigation targets outlined above. Once these surveys are completed specific mitigation targets will be agreed with AFCD.

13.11.4   During the construction and operation phase monitoring of bird populations (along with other species, habitats and physical parameters) will be undertaken as indicated in the EM & A Manual (see also Section 14.5 below).

13.11.5   The EM&A Manual will be updated periodically to reflect ongoing discussions with AFCD and the need to revise targets in light of fluctuations to bird populations within the wider area. The selection of control sites, details of the monitoring survey methodology and arrangements for reporting on the outcomes of monitoring shall be agreed with AFCD prior to commencement of construction activities.

13.11.6   It is recommended that monitoring of the appropriate implementation of mitigation measures intended to reduce potential impacts on wildlife from, noise and vibration, dust and other forms of pollution is undertaken during construction.

 

13.12      References

1.       Ades, (1990). Bats of Hong Kong. World Wide Fund for Nature, Hong Kong.

2.       Ades, G., Anon., Cornish, A., Walthew, G. & Young, L. (1995).  Focus on fishponds. Porcupine! Newsletter of the Department of Ecology & Biodiversity, University of Hong Kong. No.13.

3.       Anon. (1993). Ecological impact study of proposed development at Pak Hok Chau, Mai Po. Unpublished report.

4.       Anon. (2005). Summer 2005 Report: Egretry Counts in Hong Kongwith particular reference to the Mai Po Inner Deep Bay Ramsar Site. Report by Hong Kong Bird Watching Society to the Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

5.       Anon. (2006). Winter 2005-06 Report on Waterbird Monitoring at the Mai Po Inner Deep Bay Ramsar Site. Report by Hong Kong Bird Watching Society to the Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

6.       Asia Ecological Consultants Ltd (AEC) (2002) Preliminary study on the potential impact of the proposed residential development at Fung Lok Wai on the egretry at Shing Uk Tsuen, and on the potential for colony relocation. Unpublished AEC report.

7.       Asia Ecological Consultants Ltd (AEC) (2003). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. Annual Report, November 2003.

8.       Asia Ecological Consultants Ltd (AEC) (2004). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. Annual Report, October 2004.

9.       Asia Ecological Consultants Ltd (AEC) (2006a). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. 2004 – 2005 Annual Report, March 2006.

10.   Asia Ecological Consultants Ltd (AEC) (2006b). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. Supplementary Report for August – December 2005. March 2006.

11.   Aspinwall (1997). Study on the Ecological Value of fish Ponds in Deep Bay Area: Executive Summary. Planning Department, Hong Kong SAR Government.

12.   Aspinwall Clouston & Wetlands International – Asia Pacific (1997). Development of a comprehensive conservation strategy and a management plan in relation to the listing of Mai Po and Inner Deep Bay as a Wetland of International Importance under the Ramsar Convention.  Agreement No. CE47/95.

13.   Binnie, Black & Vetch HK Ltd (2000) Sheung Shui to Lok Ma Chau Spur Line Environmental Impact Assessment.  Agreement No. EA990008

14.   Binnie Consultants Limited (1997a). Reconnaissance survey of benthic and pelagic fishpond fauna at Fung Lok Wai. Unpublished report.

15.   Binnie Consultants Limited (1997b) Tin Shui Wai Development Engineering Investigations for Development of Area 3, 30 & 31 of the Development Zone and the Reserve Zone – Environmental Impact Assessment - Final Assessment Report.  Volumes 1 and 2, February 1997.  Territory Development Department, Agreement No. CE 10/95.

16.   Britton, A.R.C. (1993). Feeding behaviour of the Little Egret at Mai Po, Hong Kong. Hong Kong Bird Report 1992: 176-184

17.   Carey, G.J., Chalmers, M.L., Diskin, D.A., Kennerley, P.R., Leader, P.J., Leven, M.R., Lewthwaite, R.W., Melville, D.S., Turnbull, M. and Young, L. (2001)  The Avifauna of Hong Kong.  Hong Kong Bird Watching Society, Hong Kong.

18.   Carey, G. (unpublished) Ramsar Site Waterfowl Monitoring Programme, Hong Kong Bird Watching Society.

19.   Cheung, K. W. 1999. Further Notes on Freshwater Fish of Hong Kong. Porcupine! 20: 10.

20.   Chong, D. and Dudgeon, D. 1992. Hong Kong stream fishes: an annotated checklist with remarks on conservation status. Memoirs of the Hong Kong Natural History Society 19: 79-112.

21.   Chu, W. H. (1995) Fish Ponds in the Ecology of the Inner Deep Bay Wetlands of Hong Kong. Asian Journal of Environmental Management. Vol  3, No. 1, pp13-36.

22.   Collar, N. J., Crosby, M. J. and Strattersfield, A. J. (1994). Birds to Watch 2. The World List of Threatened Species. BirdLife Conservation Series No. 4. BirdLife International, Cambridge, UK.

23.   Corlett, R.T. et al. (2000) Hong Kong Vascular Plants: Distribution and Status.  Memoirs of the Hong Kong Natural History Society. pp1-3.

24.   Endangered Species Scientific Commission (1998). China Red Data Book of Endangered Animals. Endangered Species Scientific Commission., PRC.

25.   Fellowes, J.R., Lau, M., Dudgeon, D. Reels, G.T., Ades, G.W.J., Carey, G.J., Chan, B.P.L., Kendrick, R.C., Lee, K.S., Leven, M.R., Wilson, K.D.P., Yu, Y.T. (2002) Wild Animals to Watch:  Terrestrial and freshwater fauna of conservation concern in Hong Kong.  Memoirs of the Hong Kong Natural History Society.

26.   Groombridge, B. (1993) (ed). 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

27.   Hill, D., Hockin, D, Price, D., Tucker, G., Morris, R., and Treweek, J. (1997). Bird disturbance: improving the quality and utility of disturbance research. Journal of Applied Ecology 34: 275-288.

28.   Hockin, D., Ounsted, M., Gorman, M., Hill, D., Keller, V. and Baker, M. (1992). Examination of the effects of disturbance on birds with reference to the role of environmental impact assessments. J. Environ. Mgmt 36: 253-286.

29.   Holling, C. S. (ed) (1978). Adaptive environmental assessment and management. John Wiley, Chichester.

30.   IUCN (2000) The 2000 IUCN Red List of Threatened Species http://www.redlist.org/

31.   KCRC & BBVHK (2002) Sheung Shui to Lok Ma Chau Spur Line Environmental Impact Assessment Environmental:  Impact Assessment Report

32.   Melville, D.S. (1987). Chinese Pond Herons Ardeola bacchus eating flies. Hong Kong Bird Report 1987: 58-68

33.   Melville, D.S, Young, L. and Leader, P.J. (1994). The importance of fish ponds around Deep Bay to widlilfe especially waterbirds, together with a review of potential impacts of wetland loss and mitigation measures. WWF Hong Kong.

34.   Mutual Luck Investment Limited (1998) Objection to Draft Lau Fau Shan & Tsim Bei Tsui Outline Zoning Plan No. S/YL-LFS/1 – Alternative Proposal.  Volume 1 and 2.

35.   Primavera, J.H. (2000). Integrated Mangrove – Aquaculture Systems in Asia. Integrated Coastal Zone Management, Autumn edition, pp. 121-130.

36.   Pritchard, D. E. (1996) Environmental Impact Assessment: Towards Guidelines of Adoption under the Ramsar Convention. Technical Session A of the 6th meeting of the conference if the contracting parties, Brisbane, March 1996.

37.   Ramsar Bureau (no date) Classification system for wetland type. www.ramsar.org

38.   Tam, N.F.Y. & Wong Y.S. (1997) Ecological study on mangrove stands in Hong Kong. Report submitted to AFD, Hong Kong SAR.

39.   Townland Consultants Ltd, Wong Tung & Partners Ltd, Maunsell Consultants Asia Ltd, MVA Asia Ltd, CES Asia Ltd, Belt Collins & Associates HK ltd, Nelson and Wright (1992). Sunnyville Estate development at Nam Sang Wai, Engineering Assessment Report, Nam Sang Wai Development Co, Ltd & Kleener Investment Ltd.

40.   Town Planning Board (1999). Guidelines for application for developments within Deep Bay Area under section 16 of the Town Planning Ordinance. TPB PG-No. 12B.

41.   Treweek, J. (1999). Ecological Impact Assessment. Blackwell, London, UK.

42.   US Army Corps of Engineers (USACE) (1987) USACE Wetlands delineation manual.  Environmental Laboratory, US Army Engineers.  Waterway Experimental Station Technical Report. Y-87-1.

43.   Walters, C. J. (1986). Adaptive management of renewable resources. Macmillan, New York.

44.   WWF (2000). http://www.wwf.org.hk/eng/maipo/wildlife/habitats.html

45.   Wilson, K.D.P. (1995a). Dragonflies, diversity and fishponds. Porcupine! Newsletter of the Department of Ecology & Biodiversity, University of Hong Kong. No.12.

46.   Wilson, K.D.P. (1995b). Hong Kong Dragonflies, Urban Council of Hong Kong, Hong Kong.

47.   Wilson, K.D.P. (1997). An annotated checklist of the Hong Kong dragonflies with recommendations for their conservation. Memoirs of the Hong Kong Natural History Society, 21: 1-68.

48.   Wilson, K.D.P., T.W. Tam, B.S.P. Kwan, K.K.Y. Wu, B.S.F. Wong and J.K. Wong. (2004). Field Guide to the Dragonflies of Hong Kong. 2nd Eds. AFCD, Friends of Country Park and Cosmos Books Ltd. Hong Kong.

49.   Wong, F.K.O. (1991) Habitat utilisation by little egrets breeding at Mai Po. Hong Kong Bird Report. 1990: 185-190.

50.   Young, L. (1991). Conservation of wildlife in the Deep Bay area: with particular reference to heron species. pp. 813-822. In: Boxall, J. (ed.) Polmet '91; Pollution in the metropolitan and urban environment. Hong Kong Institution of Engineers, Hong Kong.

51.   Young, L. (1993). Habitat use by herons and egrets (Ardeidae) at the Mai Po Marshes Nature Reserve, Hong Kong. Unpub. Ph.D. thesis, University of Hong Kong.


 


14.             Draft Habitat creation and Management PLan FOR the Wetland NaTure Reserve

14.1          Study background and objectives

14.1.1      This draft Habitat Creation and Management Plan (HCMP) presents the details for the design and management of the on-site Wetland Nature Reserve (WNR) that was identified as appropriate mitigation and compensation for the construction of the residential development as detailed in Section 13. This is a draft document and key details presented here, including, for example, stocking densities and monitoring requirements are to be finalised subject to the endorsement of AFCD or other appropriate authority. If changes are required in light of the changing environment/baseline, such changes would need to be agreed with AFCD or the relevant authorities.

14.1.2      The proposed WNR has been designed to achieve sufficient functional enhancement to compensate for long-term operational phase disturbance. Section 3.5.6.4 xiv and xv of the Study Brief also specifically states that the Ecological Impact Assessment should:

A.          Identify any constraints associated with the finalized mitigation measures.

B.         Propose a management package for the proposed on-site WNR with particular attention to:

i.          The habitat management plan and specification of resources requirement for its implementation.

ii.          The long-term foundation management system with management guidelines.

iii.         The financial arrangements to sustain the management of the wetland.

iv.         The management agents and their responsibility.

v.          A contingency plan for the management of the WNR before the establishment of the foundation management.

C.        Formulate an ecological monitoring and audit programme for the periods of construction and subsequent site operation, including the development and operation of the WNR.

14.1.3      Objectives A, Bi and C are covered within this management plan. The structure and financial arrangements of an independent management foundation to be established for the long-term management of the WNR (Bii – Bv) are outlined within a separate chapter of the EIA (Section 15).

Description of development impacts and proposed mitigation

14.1.4      The EIA carried out on the project found that there are potential ecological impacts on ecologically valuable habitats that require mitigation measures. These are:

·        Habitat loss                                  

·        Habitat fragmentation                   

·        Disturbance                                 

·        Pollution                                       

·        Soil compaction                            

·        Hydrological disruption

 

14.1.5      The key strategy for mitigating permanent and temporary habitat loss arising from the construction of the Residential Development is the construction and appropriate management of a Wetland Nature Reserve (WNR) within that component of the site (approximately 76.1 hectares) not occupied by the proposed residential development. The aim of the WNR is to compensate permanent habitat loss and to mitigate disturbance effects through the creation of approximately 14.4 ha. of freshwater marsh habitat. In addition approximately 61.7 ha of remaining fishponds will be enhanced and managed to increase their carrying capacity for bird Species of Conservation Importance.

14.1.6      The strategy for constructing the WNR has been carefully considered and incorporates the following (strategic) elements:

·        Advance construction. Construction works associated with the WNR will be completed in advance of the commencement of construction at the Residential Development – this minimises concurrent disturbance associated with construction works in these two areas.

·        Staged construction. The construction of the WNR will be staged to minimise the areas affected at any one time. This minimises disturbance effects and ensures that there is always sufficient habitat for birds, and other species, considered to be of Conservation Importance within Fung Lok Wai.

·        Interim management. To ensure that carrying capacity of areas unaffected by construction at any one time are sufficient to maintain populations of bird (and other) Species of Conservation Importance, interim management will be undertaken during WNR and Residential Development construction phases.

·        Long-term management. Once construction works are completed and the Residential Development enters its operational phase, long-term management within the WNR will commence.

14.1.7      Although Option 1A is relatively more superior than Option 1B in respect of ecological impacts due to less building blocks and wider building gaps, it is considered that for both options the impacts from disturbance, habitat loss and fragmentation, hydrological disruption and soil compaction can be fully mitigated for through the following habitat compensation measures:

·        Structural and functional enhancement of existing aquaculture ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds)

·        Design and creation of a naturalistic wetland

·        Establishment of disturbance buffers

·        Design and construction of a potential alternative egretry

·        Design and implementation of a management programme for long-term management of the wetland reserve

14.1.8      Standard avoidance and minimisation measures, as described within the mitigation measures section of the EcIA, are considered to be adequate to eliminate other residual impacts, such as pollution, from other potential impact sources.

14.1.9      The project proponent will be responsible for the creation, enhancement and management of the WNR during the construction phase and shall provide an undertaking to take sole responsibility for management until a designated successor such as an independent Foundation is identified to the satisfaction of EPD or its agents. Subject to the necessary agreements from relevant government authorities, an independent, non-profit Foundation will be established to take over the long-term management of the WNR. The proponent or its designated successor will implement the Habitat Creation and Management Plan (HCMP) submitted with the EIA report. Experienced ecologists will be employed as the Reserve Manager for the day-to-day management of the WNR and experienced fish farmers will be employed for the operation of the fish ponds under the supervision and guidance of the Reserve Manager.

Purpose of the Habitat Creation and Management Plan

14.1.10   This Habitat Creation and Management Plan (HCMP) aims to provide the detailed specifications for the habitat and other ecological mitigation measures to be provided within the Fung Lok Wai WNR. The content of this management plan aims to compliment the management goals of the Mai Po Inner Deep Bay Ramsar Site management plan in accordance with Ramsar Convention obligations. The recommendations and specifications given in this document and the accompanying appendices will be incorporated as appropriate into forthcoming contract documentation.

14.1.11   Thus the document includes:

·        a summary of the current ecological importance and condition of the site, including physico-chemical conditions that may affect habitat restoration and enhancement measures;

·        definition of the target species requiring mitigation at the site and target habitats to be restored, created or enhanced;

·        a summary of specific habitat requirements and associated management measures required by target species;

·        detailed design drawings and specifications for the habitats (e.g. vegetation composition and structure and water regimes) and associated structures (e.g. water courses for water supply and drainage and water control structures),

·        management prescriptions and required actions to maintain the long-term ecological value and functions of the WNR;

·        a detailed monitoring programme for habitat attributes and target species; and

·        an outline programme for the implementation of the HCMP.

 

Description of the site

Site location and boundaries

14.1.12   The proposed WNR is located to the south of Inner Deep Bay in the North West New Territories of the Special Administrative Region of Hong Kong.  Figure 14‑1 illustrates the proposed location of the WNR in the context of the Deep Bay environs.

14.1.13   To the west the site is bounded by mangroves along the tidal creeks of the Tai River outfall, beyond which are grasslands, reedbeds, a plantation and aquaculture ponds. Further to the west of Fung Lok Wai is Tin Shui Wai New Town. To the north-west there is an area of tidal lagoons (near Tsim Bei Tsui) created by the construction of a causeway for the road and border security fence. The site is surrounded to the north and east by wetland habitats. A continuous band of one or two fishponds bound the site to the immediate north, beyond which lies a belt of mangroves and then the tidal mudflats of Inner Deep Bay. Further to the north-east, beyond the Shan Pui River, there is a large area of aquaculture ponds (fishponds that are actively manages, those that are currently unmanaged, and the intervening bunds) and the Mai Po Nature Reserve, a complex of mangrove, gei wai, reedbed and aquaculture ponds. Aquaculture ponds also bound the site to the east, beyond which is the Main Drainage Channel for Yuen Long, Kam Tin and Ngau Tam Mei drainage from the Shan Pui River. This currently consists of a large area of open water. To the south east lies Yuen Long Sewage Treatment Works to the south of which lies Yuen Long Industrial Estate.  The south of site is bounded by undeveloped low hills. These are predominantly covered in semi-natural scrub and woodland vegetation with some grassland and orchards.

Topography and watercourses

14.1.14   The site has an open, flat and low lying aspect. The major variation in site level is due to the excavation of the aquaculture ponds. The level on top of the bunds varies from approximately +3.1 m to +3.3 m PD, at the north and east of the site, to about +4.2 m PD at the south.

14.1.15   Water for the fishponds come from direct rainfall.  In the normal course of aquaculture pond management ponds are periodically drawn-down and water pumped from one pond to another to conserve resources. After heavy summer rainfall, ponds may fill and drain into adjacent channels. Channels may also occasionally be used for transferring water, by pump, between fishponds.

14.1.16   No flow data are currently available for the drainage channels. However, a site inspection on 10th January 1998 revealed that all channels contained shallow water (c. 10 cm) and that there were low flows from those draining catchments the adjacent catchments to the south. These observations have been confirmed on subsequent site inspections.

14.1.17   The mangrove lined channel (Tai River outfall) at the north-western perimeter of the site is intertidal.  The perimeter bunds are approximately +3.8 mPD and higher than the predicted mean high water in the channel (+2.4 m PD). Therefore in normal circumstances the interior of the site remains free of tidal influence. Overtopping of the perimeter might occur in an extreme combined high tide and storm event. However, this is likely to be extremely rare given the past extreme sea levels at nearby Tsim Bei Tsui which peaked at +3.85 mPD with a return period of 100 years for records between 1974 and 1990. The predicted tidal range for 2002 at Tsim Bei Tsui is 0-3 mPD with an average peak tide of +2.4 mPD.

Soils

14.1.18   The superficial geology of the site consists of estuarine deposits of marine and fluvial origin, predominantly silts and clays.  No borehole information is available from Fung Lok Wai itself, but investigations elsewhere indicate that lenses of sands and gravels of alluvial origin may occur underneath the surface estuarine deposits (see Townland et al. 1992).

14.1.19   The soils of Fung Lok Wai are derived from mangrove soils and ultimately have their origin as marine sediment and riverine alluvium. Texturally the soils are dominated by silt and clay fractions, the relative proportions of which produce soils that vary from clay through silty clay to silty clay loam (USDA texture classes).  Sand content is generally low. Very small amounts of gravel are present. The soils have been considerably reworked during reclamation and through management for fish-farming. The soils are poorly drained and frequently highly saline, rendering them of little agricultural value.

Existing ecological interest

Habitat evaluation

14.1.20   The ecological values of the current habitats are evaluated in the Fung Lok Wai EIA. The most valuable habitat components of the Assessment Area are wetland habitats. In particular the extensive block of Aquaculture Ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds) that form a large contiguous area embedded within the broader Deep Bay Area that includes Mai Po. Adjacent to this central aquaculture pond area there is, in the southern part of the Assessment Area, a mosaic of other wetland habitats including wet agriculture, freshwater marsh and reedbeds. Whilst these areas are of less intrinsic ecological value, their close proximity and functional linkage with the main aquaculture pond area enhances their overall status.

14.1.21   The egretry in the small Fung Shui Woodland also in the southern part of the Assessment Area is also a feature of high ecological value due to the scarcity of active egretries in the New Territories.  Recent information indicates that this egretry has now been abandoned (see Anon 2005).

14.1.22   The key ecological value of the Assessment Area is, therefore, the habitat it provides for breeding and foraging birds, in particular wetland birds such as herons and egrets, ducks and waders. In addition the Assessment Area also supports reptile Species of Conservation Importance. Traditional aquaculture and agricultural management practices have, to a large extent, engendered the value of the site for birds. At the same time, however, these practices also limit the potential value of these habitats. Aquaculture ponds are for example small and steep sided which restricts bird access and pond bunds are cleared to maintain access to ponds. With more sympathetic management the value of the wetland habitats at Fung Lok Wai could be significantly higher.

14.1.23   The extensive area of inter-tidal habitat in the northern part of the Assessment Area is also of moderate to high ecological value due to the high biological diversity of mangal systems. There is no direct link between these habitats and the proposed Development Area, however, and the potential for impact is very low.

14.1.24   All other habitats within the Assessment Area are considered to have low ecological value due, primarily to previous and current levels of disturbance (Table 141).

 

Table 141       Ecological evaluation of habitats within the Fung Lok Wai Assessment Area

Habitat

Overall evaluation

Aquaculture ponds            

High

 

Fung-shui forest

                 With egretry

                Without egretry

 

High

Low to moderate

Intertidal forested wetlands

Moderate to high

Agricultural land

                Seasonally flooded agricultural land

                Dry agricultural land

                Inactive agricultural land

 

Moderate

Low to moderate

Low to moderate

Permanent freshwater marsh and pools

Low to moderate

Secondary woodland

Low to moderate

Permanent rivers, streams and creeks

Low

Reedbed

Low

Ditches and drainage channels

Low

Wasteland

                Wasteland

                Aquaculture ponds (infilled)

                Works in progress

 

Low

Low

Low

Grassland

Low

Grassland-shrubland mosaic

Low

Orchard

Low

Plantation forest

Low

Landscaped area

Low

Developed areas

                Developed area

                Wastewater treatment area

                Water storage area

 

Low

Low

Low

 

Species of Conservation Importance

14.1.25   A list of Species of Conservation Importance that occur within the development site and 500m buffer zone are listed in Table 14‑2 below.

 

Table 142       Species of Conservation Importance that occur within the Fung Lok Wai Assessment Area

Common name

Scientific name

Habitat preference in Hong Kong

Reptiles

 

 

Banded Krait*

Bungarus fasciatus

Low lying areas near marshes, cultivated fields and shrub land

Common Rat Snake

Ptyas mucosus

Varied including agricultural areas, shrub land and around aquaculture ponds (fishponds that are managed, currently unmanaged, and the intervening bunds) and reservoirs

Indo-Chinese Rat Snake

 

Ptyas korros

Open habitats, including banks of streams and reservoirs, cultivated fields, aquaculture ponds and shrub land

Many-banded Krait*

Bungarus multicinctus

Varied, including forest, agricultural areas and the edges of mangroves

Mangrove Water Snake

Enhydris bennettii

Muddy coastal habitats

Birds

 

 

Global conservation concern

 

Black-faced Spoonbill

Platalea minor

Mudflat, drained Gei Wai and aquaculture ponds

Greater Spotted Eagle*

Aquila clanga

Brackish and freshwater marsh areas and aquaculture ponds

Imperial Eagle*

Aquila heliaca

Marshes, aquaculture ponds and adjacent hillsides in Deep Bay area.  Also recorded in the NW, NE & central New Territories

Red-billed Starling

Sturnus sericeus

Aquaculture ponds, wet agricultural areas, perimeter of reedbeds; and natural and artificial drainage channels.

Regional conservation concern

 

Common Teal

Anas crecca

Shallow wetlands including aquaculture ponds

Eurasian Wigeon

Anas penelope

Intertidal areas, marsh and aquaculture ponds

Osprey*

Pandion haliaetus

Bays, coastal areas, gei wais, aquaculture ponds, reservoirs

Potential regional conservation concern

 

Black Kite

Milvus migrans

Sea, coast, intertidal mudflat, aquaculture ponds, grassy and shrubby hillsides and harbours.

Chinese Pond Heron

Ardeola bacchus

Freshwater marsh, aquaculture ponds, wet agriculture, rivers and drainage channels.

Great Cormorant

Phalacrocorax carbo

Coastal areas, aquaculture ponds

Great Egret

Egretta alba

Wetlands, particularly shallow intertidal bays, aquaculture ponds and marshes.

Grey Heron

Ardea cinerea

Abundant winter visito to Deep Bay associated with freshwater marsh, aquaculture ponds and bunds, wet agriculture, rivers and drainage channels.

Little Egret

Egretta garzetta

Wetlands including intertidal mudflats, gei wai, also aquaculture ponds, wet agriculture, marsh and banks of rivers and streams

Local conservation concern

 

Black-crowned Night Heron

Nycticorax nycticorax

Coastal and subcoastal wetlands, including aquaculture ponds, marsh, mangrove, intertidal mudflats, riverine wetlands

Cattle Egret

Bubulcus ibis

Freshwater marsh, aquaculture pond, wet agriculture.

Collared Crow

Corvus torquatus

Primarily in Deep Bay, including rocky and sandy shores, intertidal mudflats, gei wai, aquaculture ponds

Crested Serpent Eagle*

Spilornis cheela

Hillside, woodland, rocky hilltops, undisturbed small marshes, abandoned wet paddies

Little Grebe

Tachybaptus ruficollis

Gei wai, aquaculture ponds particularly those with emergent and submerged vegetation

Little Ringed Plover

Charadrius dubius

Low lying land close to freshwater: wet agriculture, reclaimed land, freshwater marsh, aquaculture ponds (particularly when drawn down) & coastal areas adjacent to freshwater streams

Pied Kingfisher

Ceryle rudis

Fresh, brackish and saltwater wetlands including aquaculture ponds, gei wai, sheltered bays.

Striated Heron

Butorides striatus

Mangroves and inter-tidal mudflats

Temminck's Stint

Calidris temminckii

Feeds and roosts in drawn down aquaculture ponds. Also forages in freshwater marsh.

White-throated Kingfisher

Halcyon smyrnensis

Golf courses, gardens, aquaculture ponds. 

Wood Sandpiper

Tringa glareola

Low lying areas of freshwater marsh, wet agricultural land and aquaculture ponds in the New Territories particularly Long Valley. During spring passage observed on the intertidal mudflats. 

* Survey data indicate that these species only occur in the area occasionally and are unlikely to depend on the site.

 

Summary of predicted ecological impacts

Habitats

14.1.26   Ecologically valuable habitats (ie of moderate value and above) affected by the potential impacts of the proposed development identified above are summarised in Table 143. The potential impacts under Options 1A and 1B on habitats are similar, although the effects of habitat fragmentation are expected to be slightly greater under Option 1B than 1A.

 

Table 143       Summary matrix of potential impacts on habitats

Habitat

Habitat loss

Habitat fragmentation

Disturbance

Pollution

Soil compaction

Hydrological disruption

Intertidal forested wetlands

 

 

X

X

 

 

Permanent rivers, streams and creeks

 

 

 

 

 

 

Ditches and drainage channels

X

 

 

 

 

X

Aquaculture pond (actively managed)

X

 

X

X

X

 

Reedbed

 

X

X

X

 

 

Permanent freshwater marsh and pools

 

X

X

X

 

 

Seasonally flooded (wet) agricultural land

 

X

X

X

 

 

Dry agricultural land

 

 

X

X

 

 

Inactive agricultural land

 

 

X

X

 

 

Orchard

 

 

 

 

 

 

Fung-shui woodland

 

 (X)*

X

X

 

 

Semi-natural secondary woodland

 

 

X

X

 

 

Note: * only if egret present

 

14.1.27   The habitats affected the most directly are aquaculture ponds, however, the establishment of the WNR will compensate for habitat loss and disturbance caused by the proposed development. The Fung-shui woodland to the south west of the Proposed Development Area was initially considered to be highly sensitive due to the presence of an egretry. The potential effect of flightline obstruction was analysed and a decision was made to relocate the development to minimise flightlines obstruction. Subsequent surveys have now demonstrated that this egretry has been abandoned (see for example Anon 2005) significantly reducing the likelihood of flightline obstruction the potential effects.

Species

14.1.28   The major potential species impacts associated with the proposed development relate to:

·        Disturbance to birds caused by the construction and operation of the proposed development, including the WNR; and,

·        Fragmentation – in particular the obstruction of flightlines of birds moving to and from the egretry (although this impact will be of lesser significance if the egretry remains abandoned).

Constraints on design

14.1.29   The ecological impacts summarised above and described in the EIA Report may potentially be mitigated for through the enhancement or re-creation of a number of wetland habitat types.  There may, however be constraints affecting the restoration and management of wetland habitats at Fung Lok Wai and consequently the potential for impact mitigation. Potential constraints are therefore reviewed on the basis of the site description above and summarised in Table 14‑4 below.

 

Table 144       Potential physical constraints on the creation of a Wetland Nature Reserve at Fung Lok Wai.

Key factors

Assessment of constraint

Size and location of the site

The site is relatively large (approximately 80.1 ha) and dominated by aquaculture ponds (fishponds that are managed, currently unmanaged, and the intervening bunds), which are contiguous with others in the Mai Po Inner Deep Bay Ramsar site and wider Deep Bay area. It is therefore essential that the habitats within the proposed WNR remain ecologically linked and compatible with the surrounding habitats.

Water quantity

Although Hong Kong has a high level of rainfall there is a long period of dry weather in winter when evaporation and transpiration exceeds rainfall. Therefore freshwater marsh, reedbeds and shallow ponds are susceptible to drying out. Fishponds currently rely on direct rainfall, but the creation of other shallow wetlands may require additional inputs during the dry season. Water is available from run-off from the residential site and two adjacent catchments.

Topography, water depth and water level control

There is little variation in ground levels over the site. Although this is principally advantageous for the creation of ponds and freshwater marsh, it reduces the potential for moving water between water bodies by gravity alone. Although the land is low lying flooding with saltwater due to storm surges is likely to be a rare.

Water quality

Data on water quality in the existing courses entering the site are not available. However, visual inspection of the catchments indicates that these are dominated by semi-natural vegetated habitats with no obvious sources of pollution. It is therefore anticipated that water quality from these catchments will be adequate for most wetland habitats. Run-off from the residential development will require screening and removal of litter, oil and similar pollutants and excessive silt loads during high rainfall events.

Substrate

The clay soils over the site are impermeable and therefore suitable for the creation of permanent waterbodies. The soils hold high levels of sulphide which may cause acidification problems in aerobic conditions. High salinity, aluminium and iron levels may also limit the establishment and growth of some plant species.

Vegetation establishment

Many wetland plants are already present on the site and may provide source populations. Commercial sources of wetland plants (e.g. reed seedlings) are readily available. Opportunistic sources may also become available through the development of other wetlands in Hong Kong.

Vegetation growth

Plant growth is rapid in Hong Kong due to the warm and wet climate. Vegetation management measures (such as mowing or grazing) may therefore be necessary to maintain low growing, open and varied plants communities within freshwater marsh habitats. Soil conditions (see above) may, however, retard plant establishment and growth. There are a number of exotic species that cause problems to native wetland vegetation and considerable management will be required to control them.

Disturbance

There are numerous sources of disturbance to birds and other sensitive fauna on the site, including fish-farming operations, scattered dwellings and the proposed residential development itself. Disturbance reducing measures will be required to enhance the use of the site by many species of waterbird.

 

Engineering

14.1.30   Weak structural integrity of bunds (in aquaculture ponds) is a potential constraint on the access and operation of heavy construction machinery, such as excavators. Fish farmers, however, currently routinely use heavy machines such as bulldozers in pond management (as it is existing practice to periodically re-profile fishponds). Furthermore the site is criss-crossed by a network of tracks and roads. This suggests that, in practice, there should be no significant constraint on access for machines such as excavators and bulldozers required for the pond enhancement works proposed.

14.1.31   The pond enlargement process will result in the creation of longer bunds than currently exist. Bund re-formation works will need to be undertaken in a controlled manner to ensure that bund strength is retained.

Hydrology / Drainage

14.1.32   The main constraint on the design of the wetland mitigation scheme is the highly seasonal rainfall in Hong Kong. Typically there is a period of water deficit (i.e. rainfall is exceeded by evapotranspiration) from September to March. Without an additional source of water it is not normally possible, to maintain permanent shallow wetlands, such as those required in the proposed freshwater marsh complex mitigation area. Permanent wetlands may be retained by storing sufficient water to overcome the deficit period, but such wetlands are then inundated by water which is too deep for many of the wetland target species over the much of the annual cycle. Average monthly rainfall evaporation and deficits are indicated in Figure 14‑2.

14.1.33   Potential water sources include run-off from the residential development roofs and hard standing and stream flow from small hillside catchments to the south of the site (Catchments A and B, Figure 14‑3).

14.1.34   The outfall to the Tai River, which provides drainage for the area, is tidal. An outfall is required, therefore, that is resistant to tidal erosion and which, by means of a tidal flap, allows one way flow and prevents saline water intrusion.

Soils

14.1.35   The soils present at the site consist of poorly drained marine clays. These are sufficiently impermeable to maintain wetland conditions or aquaculture ponds (fishponds that are managed, currently unmanaged, and the intervening bunds) over the site as demonstrated by the current presence of such habitats, which are in the main solely maintained by direct rainfall inputs.

14.1.36   They are, however, acid sulphate soils which can lead to highly acidic conditions when these are disturbed and dried. Nevertheless vegetation such as Phragmites does spontaneously recover on bunds and therefore the maintenance of basic vegetation cover is unlikely to be constrained. However, care with soil handling or remedial measures (e.g. application of lime) may be needed to establish more sensitive and diverse wetland vegetation of high ecological value within the marsh areas of the site.

Water Quality

14.1.37   The sources of water for the WNR are direct rainfall and run-off from the proposed Development Area and existing catchments immediately to the south of the proposed Development Area.

14.1.38   Using run-off from developed catchments can lead to eutrophication and toxic metal pollution problems. Studies of the water quality characteristics of urban run-off in the United States (USEPA, 1983), for example, indicated that average total phosphorous concentrations in run-off from residential and commercial sites tend to exceed targets for shallow non-eutrophic wetlands. Guidelines for total phosphorus in freshwater wetlands tend to be in the region of 10-60 micrograms l-1 (eg ANZECC 2000).

14.1.39   The study of residential and commercial sites in the United States also found copper concentrations of 53 micrograms l-1, lead at 238 micrograms l-1 and zinc at 353 micrograms l-1. In comparison recommended maximum levels for the protection of aquatic life for these metals are 19 micrograms l-1, 9 micrograms l-1 and 241 micrograms l-1 respectively (Missouri Department of Natural Resources 1996).

14.1.40   In Hong Kong Binnie Consultants Ltd (1997) also found that total phosphorus in run-off from developed catchments tends to exceed guidelines for wetlands (average TP >420 micrograms l-1) although heavy metals were below the guidelines proposed by the Clean Water Commission above. Furthermore, published river water quality data for Hong Kong (eg EPD 2002) also indicates that levels of heavy metals in rivers in the Deep Bay area tend, on average, to be below these recommended levels.

14.1.41   The existing catchments that will supply water to the WNR are dominated by dense semi-natural scrub and woodland vegetation, are only partially developed and, like the proposed development, contain only housing with no commercial use. There are no apparent point sources of pollutants, such as pig farms etc. Water from catchment flow is likely to be of relatively low nutrient content and Biological Oxygen Demand (BOD). It is also anticipated that suspended solids (mainly silt) in runoff during heavy rainfall periods is relatively low due to the existing dense vegetation cover in the catchments. In addition, it is likely that the concentrations of toxic heavy metals in the run-off will be below levels that could prove problematic for aquatic ecosystems.

14.1.42   As most run-off will be associated with heavy rainfall, it is anticipated that any pollutants from the residential site will be sufficiently diluted to ensure that a suitable water quality standard is achieved for the wetland. Nevertheless, as an initial precaution, run-off water from the residential site will be passed through traps to remove oil and grease and sand and gravel filters to reduce silt loads and particulate organic matter prior to discharging into the ditch and the storage pond. A high proportion of heavy metals and phosphates are normally bound to sediments and organic matter, the removal of silt will therefore considerably reduce the levels of these pollutants.

14.1.43   Run-off water from the catchments and development area will be stored for long periods before entering the wetland area any remaining silt that is present will be able to settle out of the water. This will further significantly reduce pollutant levels (from the residential run-off and catchments A and B). Periodic silt removal from the storage pond will therefore be required.

14.1.44   In summary, although there are no major obstacles to the creation of a WNR at Fung Lok Wai, possible constraining factors may be the low level of the site, soil salinity and pH, disturbance and the need for active and long-term management of the vegetation and water-bodies.

 

14.2          Mitigation objectives

Management goals and objectives of the Wetland Nature Reserve

14.2.1      The key goal of the WNR is the conservation of Species of Conservation Importance, specifically to mitigate habitat loss and disturbance during the construction and operation of the Residential Development. It is intended that the WNR will maintain populations of Species of Conservation Importance at better than baseline levels (as established through ongoing monitoring). In the long-term it is anticipated that the WNR will sustainably support a more diverse flora and fauna than that currently found at Fung Lok Wai.

14.2.2      As described above the key strategies for achieving this are:

·        Completion of construction works associated with the WNR in advance of commencement of the noisiest works associated with the construction of the Residential Development.

·        Staged construction (to minimise impacts caused by the WNR works themselves).

·        Intensive interim management of ponds during the construction phase of the Residential Development.

·        Long-term sympathetic management of ponds during the operation phase of the Residential Development.

14.2.3      The importance of the wetland habitats at Fung Lok Wai derives primarily from the resources they provide for Species of Conservation Importance and in particular wetland birds such as herons and egrets. Some aspects of traditional aquaculture practice on site, such as periodic draining of ponds, have increased the attractiveness of aquaculture ponds to birds. On the other hand the small and uniformly steep sided form of the ponds limits (those that are managed, currently unmanaged, and the intervening bunds) their potential. With more sympathetic management the value of aquaculture ponds at Fung Lok Wai could be significantly higher.

14.2.4      A key objective is to improve the overall attractiveness of the aquaculture ponds at Fung Lok Wai for species dependent on wetland habitats. This will be achieved through a reconfiguration of the ponds to create fewer, larger ponds and the creation of a complex of freshwater marsh habitats. Increasing fishpond size is expected to benefit wetland birds as there is evidence many species prefer larger, less enclosed waterbodies to the small ponds which typify most aquaculture practices. The removal of some bunds is predicted to have low or negligible impact on flora or fauna as their intrinsic ecological value is low and no Species of Conservation Importance were found to be reliant on them. The complex of freshwater marsh habitats proposed will provide a range of additional habitats for birds and other flora and fauna, including dragonflies.

14.2.5      Apart from the site formation works of the marsh and residential developments (which will be carried out concurrently to shorten the disturbance), pond enhancement works and marsh construction will be completed before construction of the Residential Development commences. This will ensure that compensation is achieved during both construction and operation phases of the Residential Development. To minimise disturbance caused by WNR construction itself, these works will be staged. The sequence of construction is outlined in Figure 13-13.

14.2.6      Functional enhancement will be achieved through enhancement of both the ponds and the approach to aquaculture management. The management approach during the construction phase will be more intensive as a greater degree of functional enhancement is required to compensate for the high level of disturbance anticipated during this period. Disturbance levels during the operation phase are predicted to be lower and hence the focus of long-term management within the WNR will be focused on sustainably maintaining populations of Species of Conservation Importance and increasing overall biodiversity.

Interim management (Construction Phase)

14.2.7      As indicated within Section 13 a total of 4 hectares of wetland will be lost under the footprint of the Proposed Development Area. In addition to this, functional habitat loss has been identified through quantification of impacts of disturbance on Species of Conservation Importance.  To achieve full compensation for the most sensitive wetland species (see Section 13.9) it will be necessary, during the construction phase to approximately double the carrying capacity of ponds unaffected by disturbance. If the requirement to compensate for the disturbance to these most sensitive species is met, full compensation for the impacts of direct habitat loss and disturbance to less-sensitive Species of Conservation Importance is likely to be achieved, as long as appropriate habitat is provided. Mitigation for other impacts on both birds and other Species of Conservation Importance are addressed later in this section. Wetland management principles established previously indicate that such enhancement is readily achievable for waterbirds (BBV 2002, M. Leven pers. comm., AEC 2004, 2006a, 2006b).

14.2.8      It is anticipated that if wetland functionality is maintained there should be no significant decrease in species numbers within the Study Site despite impacts of disturbance in some areas of the site. So the targets for species of conservation importance are to maintain at least the baseline levels within the Study Site.

Long-term Management (Operation Phase)

14.2.9      Once construction is completed the WNR will be placed under a long-term management designed to compensate for the lower levels of disturbance caused by the operation of the Residential Development. Based on traditional aquaculture practices the management during this period is intended to both maintain populations of Species of Conservation Importance and to increase overall biodiversity.

14.2.10   Under normal conditions bird population numbers fluctuate readily between seasons and years as a result of a variety of factors, including temperature, migratory patterns, food availability and human disturbance. Changes resulting from such factors cannot easily be accounted for.  Hence the importance of the Fung Lok Wai site for wetland birds should be taken in the context of the Mai Po Inner Deep Bay Ramsar site as a whole, so that monitoring takes yearly fluctuations in bird activity within Deep Bay into account.

14.2.11   Significant changes will be used to guide appropriate management within an adaptive management framework.

Habitat condition targets

14.2.12   The EcIA Report identifies the habitat requirements of each Species of Conservation Importance identified and concludes that the most appropriate form of wetland mitigation in the Fung Lok Wai area is the enhancement of aquaculture ponds (fishponds that are managed, those that are currently unmanaged, and the intervening bunds) over the majority of the mitigation area combined with the establishment of shallow freshwater marsh.

14.2.13   Ponds managed for commercial aquaculture in the Deep Bay area are full for most of the time and their use by birds is severely limited due to their relatively steep sides, deep water and their frequent lack of marginal vegetation. These characteristics also limit their use by other species and hence aquaculture ponds tend to have relatively low biodiversity compared to many wetland habitats.

14.2.14   The management of fish ponds for commercial aquaculture, however, creates a key by-product in the form of abundant “trash fish” – small, non-commercial fish and invertebrates including Gambusia affinis (Mosquito Fish), Macrobrachium nipponense (a prawn) and Oreochromis mossambicus (a species of Tilapia).

14.2.15   When ponds are drained down during the winter months for harvesting, large concentrations of birds can be observed foraging in the shallow water for trash fish. As only a small proportion of fishponds are drained at any one time, and only for short periods, the spatial distribution of feeding birds is highly dynamic and variable as birds seek out ponds as they are drained. ‘Feeding bottlenecks’ may occur if there are insufficient ponds to support foraging bird populations.

14.2.16   The main objectives of enhancing aquaculture ponds are, therefore, to:

·        Increase the value of aquaculture ponds to herons and egrets outside harvesting periods (i.e. draw-down), by increasing food resources and food availability and by reducing disturbance effects. Enhancement of the value of ponds to such birds outside harvest periods could reduce the potential for ‘feeding bottlenecks’ thereby possibly reducing the area of aquaculture ponds needed to support the population.

·        Increase their overall biodiversity value and suitability for other non-bird Species of Conservation Importance, such as some mammals (eg Eurasian Otter), amphibians and reptiles, whilst maintaining their current important functions for herons, egrets and other water birds.

14.2.17   Figure 14‑4 indicates the location of the proposed area of enhanced aquaculture ponds. These will be placed away from the development area to minimise disturbance impacts. They would also be contiguous with the main area of ponds in the WCA and Mai Po Inner Deep Bay Ramsar site as a whole. Maintaining a contiguous area for compensation, which is linked, with an existing area of recognised conservation importance is of significant ecological value.

14.2.18   The design of the wetland habitats of the WNR and the mitigation targets defined below are informed by best practice in wetland design and are consistent with principles and guidance established in key publications including, Hawke & José (1996), Benstead et al. (1997, 1999) and McMullon & Collins (2004). With respect to fishponds these targets are designed to maximise the area available for birds that feed by wading into shallows by specifying targets for shallow water (defined as water less than 10cm in depth). To maximise accessibility and to minimise the “enclosure” of the ponds, targets have been included to maintain open bund and island habitats through the maintenance of bare ground and / or short vegetation. An undesirable feature of fishponds, particularly those that are not actively managed, is their tendency to become infested with undesirable weed species. Once established such infestations can be costly and time-consuming to remove. A specific target is included, therefore, to ensure that any infestations are kept to a minimum and to prompt early action on control.

14.2.19   The specific aquaculture pond habitat targets for the mitigation area are indicated in Table 14-5.

 

Table 145       Mitigation targets for enhanced fishponds

Mitigation issue

Target

Enhancement of aquaculture pond area

61.7 ha. (including bunds, control structures and potential alternative egretry)

Shallow fish pond area (i.e. < 10cm depth)

More than 20% (excluding aquaculture ponds that are dry for maintenance)

Cover of undesirable invasive species and exotic species

Less than 10% of vegetation cover (excluding open water marsh area)

Plant cover on bunds and islands (in aquaculture ponds)

Vegetation of height >10cm to comprise less than 5% plant cover on more than 75% of the area of aquaculture pond bunds and islands

Area under traditional polyculture fish pond management systems

70-90% of the fish pond area

(Excluding bunds and ponds that are dry for maintenance)

Area set-aside from fish farming and under specific conservation management

10 - 30% of the fish pond area

(Excluding bunds and ponds that are dry for maintenance)

 

14.2.20   The targets for the marsh habitat reflect the desire to create a habitat that is dominated by a diverse mosaic of wetland microhabitats and plant species. Open water is desirable within certain sections but should be limited to allow the growth and establishment of communities associated with permanently wet habitats. It is anticipated that the area of open water will fluctuate seasonally (greater extent during the wet season) thus promoting the growth of communities associated seasonally inundated wetlands. As with fishponds there is potential for establishment of undesirable and exotic weed species and a specific target is included to prompt early and effect control of any infestations. The specific targets for the Marsh Habitat mitigation area are indicated in Table 14‑6

.

Table 146     Mitigation targets for Marsh Habitat

Mitigation issue

Target

Creation and maintenance of a total of freshwater marsh habitat in Favourable Condition

14.4 ha. (including essential structures, e.g. water control structures, and other habitats e.g. bunds)

Freshwater marsh habitats are defined as areas where wetland hydrological conditions, or wetland soils are present or where wetland plants are dominant, with shallow water (average < 1m) and wetland plant species cover greater than 30% of the area.

Cover of wetland plant species

More than 90% established vegetation

Cover of undesirable invasive species and exotic species

Less than 10% of vegetation cover

The average depth of water

30 – 50 cm (outside drawn down periods for maintenance)

Area of open water (i.e. unvegetated water)

20-30%.

 

Species population targets

14.2.21   The mitigation targets for Species of Conservation Importance associated with fishpond habitats are summarised in

14.2.22   Table 14‑7 (see Section 13.9 for the derivation of these) Banded Krait and Many-banded Krait have been excluded from this table because they have little reliance on fishpond habitats.

 

Table 147       Mitigation targets for Species of Conservation Importance associated with fishpond habitats

Species

Mitigation target (population increase)

Construction phase

Operation phase

Birds

Black-faced Spoonbill

Double

Increase by 45%

Chinese Pond Heron

Increase by 61%

Increase by 32%

Great Cormorant1

Double

Increase by 41%

Great Egret

Double

Increase by 45%

Grey Heron

Increase by 61%

Increase by 32%

Little Egret

Increase by 92%

Increase by 33%

Cattle Egret

Increase by 33%

Increase by 32%

Other species

Common Rat Snake

Present

Present

Indo-Chinese Rat Snake

Present

Present

Mangrove Water Snake

Present

Present

Notes:

1         If Great Cormorant numbers exceed mitigation targets it may be necessary to implement controls on the size of the population. The implementation of such controls will be determined in the context of the Adaptive Management framework and in discussion with AFCD

14.2.23   As the Marsh Habitat will be new habitat there are no existing animal populations associated with marsh habitats upon which to base mitigation targets. In addition it is anticipated that the Marsh Habitat will be subject to disturbance arising during the operation phase due its proximity to the residential development. Nevertheless there are a range of bird species that would be expected to use the Marsh Habitat. Management of the marsh habitats will focus on ensuring that these “primary” species (see

14.2.24   Table 14‑8) are present. In addition there are a range of other species that are associated with marsh habitats. Whilst it is desirable that these species are present, they will not form the primary focus of management effort. In addition it is expected that the marsh habitat will support a range of amphibian, reptile and invertebrate species.

 

Table 148       Species Expected to Use the Marsh Habitat

Primary Species

(Presence expected)

Secondary Species

(Presence desirable)

Birds

Little Egret (R)

Chinese Pond Heron (R)

Great Egret (W)

Grey Heron (W)

Eurasian Teal (W)

Black-winged Stilt (W)

Pintail / Swinhoe’s Snipe (P / W)

Common Snipe (W)

Zitting Cisticola (W)

 

Japanese Quail (P / W)

Eurasian Coot (W)

Pheasant-tailed Jacana (P)

Greater Painted Snipe (R)

Black-winged Stilt (B)

Richard’s Pipit (P / W)

Bluethroat (P / W)

Pallas’s Grasshopper Warbler (P)

 

Reptiles

Common Rat Snake

Checkered Keelback

 

Chinese Soft-shelled Turtle

Burmese Python

Amphibians

Asian Common Toad

Günther’s Frog

Paddy Frog

Brown Tree Frog

Marbled Pygmy Frog

 

Chinese Bullfrog

Three-striped Grass Frog

Spotted Narrow-mouthed Frog

 

Dragonflies

At least 20 species

 

Species typically associated with marsh or reedbed habitats:

Marsh Dancer (Onchyargia atrocyana)

Scarlet Dwarf (Nannophya pygmea)

Marsh Skimmer (Orthetrum luzonicum)

Sapphire Flutterer (Rhyothemis triangularis)

Four-spot Midget (Mortonagrion hirosei)

Key: R – resident; W – winter; P – passage; B - breeding

 

Public access objectives

14.2.25   Under the management zoning of the Comprehensive Conservation strategy and Management Plan (Aspinwall Clouston and Wetlands International 1997) the adjacent areas within the Ramsar site have been designated as Public Access Zones (PAZ).  The broad aim of these is to facilitate public access to the site for educational and appropriate recreational purposes.

14.2.26   There will be no public visitation to the site during the construction phase, when the site is under the interim management regime.

14.2.27   During the operational phase it is proposed that public access to the WNR will only be allowed on a restricted basis at a level that will not conflict with the over-riding objectives of nature conservation. The primary objective of visitation will be education. To facilite access a small number of marked footpaths and hides for viewing birds and other wildlife in a variety of habitats will be provided. Interpretive materials including information boards and leaflets etc. will also be provided.

 

14.3          Detailed design and construction methods

Overview of design and relationship with surrounding habitats

14.3.1      The proposed WNR will comprise two key elements (Figure 14‑4):

·        a large expanse of retained, but ecologically enhanced, aquaculture ponds, including a potential alternative egretry; and,

·        an area of created ‘natural’ freshwater marsh.

14.3.2      There are three key features of this proposed layout:

14.3.3      First, the majority of the aquaculture ponds (fishponds that are managed, those currently unmanaged, and the intervening bunds) on the site are maintained, including all those within the Ramsar site boundary. This avoids the loss or detrimental modification of any wetland area within the Mai Po Inner Deep Bay Ramsar site and maintains the large open contiguous block of aquaculture pond habitat in the area.

14.3.4      Second, the location of the proposed area for the creation of natural wetlands will maximise the potential for ecological links with the following complementary adjacent habitats:

·        Scrub, woodland and particularly wetland habitats to the south of the site;

·        inter-tidal mangrove habitats along the former Tai River outfall; and,

·        the wetland creation at Hong Kong Wetland Park (HKWP).

14.3.5      These habitats may provide sources for the natural spread and establishment of some plants and animals within the wetland area. In addition they will provide additional shelter, food or breeding sites for wetland species and ecological ‘corridors’ which may facilitate dispersal.

14.3.6      Third, as the created wetland will contain abundant tall reedbeds, as well as other tall wetland vegetation and scattered trees, this will serve as a buffer between the residential development and the fishponds. This will reduce disturbance of birds feeding within the fish ponds.

14.3.7      Figure 14‑5 indicates the location and layout of habitats within the proposed WNR. The total area of the various habitats is summarised in Table 14‑9. The total area of wetland within the site will be approximately 76.1 ha. This represents a slight net increase in area of water body, from the current situation, through enlargement of most fishponds and the consequent loss of dividing bunds.

 

Table 149       The area of habitats in the proposed WNR

Habitat type

Area (ha)

Percentage of site

Fish pond area*

61.7

77.0%

Marsh complex

14.4

18.0%

Total wetland

76.1

95.0%

Residential development site

4.0

5.0%

SITE TOTAL

80.1

 

NOTE:           *Including potential alternative egretry.  All figures are approximate

Aquaculture pond area

Rationale

14.3.8      As acknowledged in the Comprehensive Conservation Strategy and Management Plan for the Mai Po Inner Deep Bay Ramsar Site (Aspinwall Clouston & Wetlands International – Asia Pacific, 1997) and discussed previously in this proposal, fish ponds are particularly important habitats in the Deep Bay area for resident and migratory herons and egrets.

14.3.9      Under typical management, however, fish ponds do not provide optimal habitat conditions for herons and egrets and are particularly poor for many other water birds. In particular, they have relatively steep and uniform banks which limits the abilities of herons, egrets and waders to reach food sources. The lack of aquatic plants (due to the presence of plant eating fish and their high nutrient status and associated turbidity) also reduces their suitability for many aquatic macro-invertebrates. The lack of aquatic plants and invertebrates in turn limits their use by duck species.

14.3.10   Reeds and other tall emergent and bund (in aquaculture pond) vegetation can provide good habitats for insects and other invertebrates that, in turn, provide food for other animals including passerine birds. Existing reeds at Fung Lok Wai, however, occur in scattered patches and relatively narrow strips, probably because bund and emergent vegetation is frequently cleared by pond operators to maintain access. These are of limited value as breeding habitat and provide little cover for larger species.

Objectives

14.3.11   In order to increase their value for Species of Conservation Importance and to enhance their overall biodiversity it is proposed that the ecological functions of most of the aquaculture ponds (fishponds that are managed, those currently unmanaged and the intervening bunds) will be maintained and the following enhancements made:

·           The size of some ponds will be increased (Figure 14‑6). This will increase their suitability for herons and egrets, which tend to avoid smaller ponds, particularly where these are enclosed by vegetation. It will also facilitate reprofiling works.

·           Selected bunds will be reprofiled to provide shallow sloping and irregular margins to increase feeding opportunities and efficiency for herons, egrets, waders, rails and crakes etc.

·           Emergent vegetation will be allowed to develop (and where necessary established by planting) on some pond margins, to provide increased cover and feeding habitats for insects and other invertebrates, amphibians, reptiles, birds (e.g. bitterns, smaller herons, rails, crakes and some passerines) and mammals. Vegetation will be encouraged to develop in areas that require screening from disturbance (e.g. along footpaths and near dwellings and roads etc) and where exposure of ponds to prevailing trade winds may cause significant erosion problems. Bands of emergent vegetation will also be linked across the site to provide continuous ecological corridors linking similar and complimentary habitats within and off the site (see Figure 14‑7 for illustrative layout).

·           Unvegetated muddy shallows that will be intermittently exposed as muddy islands will be created in some of the larger ponds, from the part removal of existing bunds, to provide enhanced feeding and roosting opportunities for herons, egrets and waders. These shallows will be exposed as muddy islands by slightly reducing water levels, as and when required (e.g. during heron breeding periods and peak wader migration).

14.3.12   Three ponds (2, 3 and 11) will be permanently taken out of fish production. Two of these (3 and 11) will be drained and then allowed to partially refilled with rain water to provide shallow ‘natural’ lakes of high value to waterfowl (as occurred at Mai Po Nature Reserve).  The other small pond (2) will be used to establish a reedbed to provide cover and nesting sites for the birds in the aquaculture pond area.

Works

14.3.13   As indicated in Figure 14‑6, 31 ponds (approximately 47.0 ha.) will be consolidated to 18 larger pond, which will continue to be managed as aquaculture ponds and 6 (approximately 10.27 ha.) will be taken out of production (consolidated into 3 larger ponds) and managed as rain fed ponds for duck and other water birds.

14.3.14   Where indicated in Figure 14‑6, bund material currently separating ponds will be lowered and side cast to create shallow sloping margins to islands and / or shoals. Actual levels to be attained on each modified bund are based on generic designs indicated in Appendix 14-1. The generic designs to be used for each modified bund are as follows (according to bund numbers given in Figure 14‑6):

·        Design Type A- 4, 12, 14, 15

·        Design Type B- 7, 11, 16

·        Design Type C- 6

14.3.15   Remaining bunds to be modified will be used to create unvegetated muddy shallows as indicated in Figure 14‑6. Each area of shallows will rise at a slope 1:20 from the indicated waterline, based on Initial Operating Levels. The below water level slope will be as shallow as feasible.

14.3.16   Each pond will drained, dried and reprofiled on a three-year to five cycle as typically currently carried out on aquaculture ponds. During this process each pond bund will be reprofiled to create as shallow a slope as feasible according to the properties of the bund material. 

14.3.17   In addition, following reprofiling, further works will be undertaken under the direction of the WNR Reserve Manager to provide variation in the shoreline profile along the typical waterline. This will be carried out by using a backhoe to create indentations along the water line (at the Initial operating Level) by small-scale excavations and pressing down with the back of the excavator bucket on the bund. Approximately 30% of the margins of each pond should be worked in this way to create a ‘scalloped edge’ with shallow shelves just below the Initial Operating Level (10 –30 cm depth).

14.3.18   To facilitate vehicle access to all parts of the site, for water level management and other activities, some works on the remaining bunds will be necessary.  The tops of the bunds may require some vegetation clearance and strengthening with a geofabric to enable them to be used as access-ways. Current practice is to use some stone fill to form the running surface and it is proposed to extend this where necessary.

14.3.19   An earth covered floating platform seeded with Paspalum distichum will be placed in each operating aquaculture pond to provide additional foraging areas for herons and egrets etc and potential breeding sites for some water birds (such as Little Grebe) as well as shelter for fish and aquatic invertebrates.

14.3.20   The engineering requirements for the construction of the ponds will only consist of installation of a series of adjustable sluices or similar water control devices to interconnect the ponds (Figure 14‑7). Ponds 2, 3 and 11 will be connected to the central drainage watercourse with adjustable sluices or similar water control devices set at low levels to maintain shallow water by allowing excess water to flow over the sluice and by gravity to the watercourse (Channel Y).

14.3.21   Other sluices will be installed to facilitate general water management on the site and allow storm water run-off, where necessary, via Channel Y. A drainage pipe will be installed to connect Ponds 12 and 18 (and interconnected ponds) to Channel Y.

14.3.22   All fishpond water will be obtained by direct rainfall and will be retained and re-circulated during drain-down periods as necessary. In any one year two ponds will be used as reservoir ponds as a contingency measure to ensure that pond water levels are kept within tolerance levels. No surface or groundwater water supplies will be used for aquaculture pond operations. Note: the reservoir ponds referred to here are not the same as the Storage Pond which will hold water for use in Freshwater Marsh habitats.

Pond enhancement works

14.3.23   Enhancements will be staged to reduce disturbance. To facilitate this, the existing aquaculture ponds have been divided into 3 Sectors (Figure 14‑13). Reprofiling works will be conducted sequentially and systematically within these sectors to avoid concurrent activity within the WNR. The sequence of construction works is summarised in Figure 13-13 and the management strategy for these ponds, including during construction, is outlined in Section 14.4 below. The purpose of this management strategy is to mitigate disturbance effects at all stages of the construction programme.

14.3.24   On acquisition of the site, the ponds in Sector 1 will be enlarged and reprofiled as indicated in Table 14‑10.

 

Table 1410     Pond enhancement schedule.

(Bund numbers are indicated in Figure 14‑6. Estimated duration includes pond drain down and construction works but excludes filling time.)

Bund removal sequence

Estimated duration

Sector 1

 

1

2,3

4

5

6

7

 

TOTAL

2 weeks

3 weeks

2 weeks

2 weeks

2 weeks

2 weeks

 

13 weeks

Sector 2

 

9

10, 29

 

TOTAL

2 weeks

4 – 5 weeks

 

6 – 7 weeks

Sector 3

 

New bund creation

8

12

11, 14

15, 16

 

TOTAL

4 weeks

2 weeks

2 weeks

3 weeks

3 weeks

 

14 weeks

TOTAL DURATION

34 weeks

 

14.3.25   As indicated above construction of the marsh area is programmed to coincide with site formation works associated with the residential development. To avoid excessive disturbance due to construction activities, pond enhancements in Sector 3 will be delayed until completion of works on the constructed marsh. Construction of the marsh is expected to take 9 months (refer to Figure 13-13 for the timing of these activities).

14.3.26   Once constructed, Ponds 2, 3 and 11 will be managed under a different regime involving partial drainage to a specified depth (depending on the time of year) and then maintained at prescribed levels.

Vegetation establishment

14.3.27   There are no areas of vegetation or individual plant species or specimens which should be conserved in situ or transplanted. No protection of existing vegetation is, therefore, necessary in the aquaculture pond (fishponds that are managed, those currently unmanaged and the intervening bunds) or freshwater marsh area (described below). Indeed in many instances the deliberate removal of existing vegetation of limited ecological value will be required.

14.3.28   A list of the species to be established on the islands and along the aquaculture pond margins and bunds is provided in Table 14‑11 below.

14.3.29   Areas to be planted with these species are indicated in Figure 14‑7. On the remaining bunds natural regeneration of vegetation will be allowed, but with 25% of these kept as largely bare banks to provide foraging and/or loafing areas. The areas kept bare will be rotated on an annual basis at the discretion of the WNR Reserve Manager.

 

Table 1411     Wetland species to be established in the aquaculture pond mitigation area

Species

Approx. density (no. m-2)

 % cover

Growth form

Approx. height for planting (cm)

Phragmites australis

4

100

Monostands

>20 cm

Paspalum distichum

 Broadcast seed

0 – 100*

Monostands

N.A.

                Notes:      * Paspalum distichum seed to be broadcast on permanently dry and seasonally wet areas.  Overall percentage of cover along bunds to be 25 – 75% around each pond.

 

14.3.30   Trees and shrubs will be planted on some bunds to provide cover and to screen sensitive areas of the wetland from disturbance sources, such as the residential development and vehicle use. However, care will be taken to ensure that planting does not impede flight lines for birds or fragment the contiguous areas of open aquaculture pond habitat.

14.3.31   Only species that are native to the area will be planted on the bunds, including fruit bearing tress such as China-berry (Melia azadarach) (a species considered to be naturalised in Hong Kong) which are known to be attractive to Red-billed Starlings and other passerines.

Potential alternative egretry

14.3.32   To compensate for potential disturbance to the the previous Shing Uk Tsuen egretry which was located to the south-west of the proposed Development Area, a potential alternative egretry will be constructed within the aquaculture pond area (Figure 14‑6). The potential alternative egretry will duplicate in size the Shing Uk Tsuen egretry (approximately 2,000 m2).

14.3.33   To minimise potential disturbance, this alternative site has been constructed as far as possible from the proposed development area but also away from the perimeter of the WNR. Furthermore a location has been selected where the base of the egretry can be constructed around existing bunds which possess mature trees.

14.3.34   Upon the base mature or semi-mature specimens of Bambusa eutuloides will be planted as a central core around which mature or semi-mature Celtis sinensis and Ficus macrocarpa will be planted to provide cover and structure. These trees will be raised off-site.

14.3.35   The egretry will be planted as early as possible in the construction programme to provide sufficient time for maturation of vegetation and establishment.

Freshwater Marsh Complex

Rationale

14.3.36   Although aquaculture ponds are habitat for species of conservation importance they are less attractive for other species and tend to have low overall diversity. The enhancement measures identified above will go some way toward increasing the diversity of wetland habitats and species within Fung Lok Wai.

14.3.37   Although largely lost from Hong Kong, freshwater marsh habitat potentially provides a much more diverse environment and can support a wider range of species.

14.3.38   Marsh habitat that is varied and composed of a mixture of permanent open lakes of various depths, reedbed and seasonally inundated areas dominated by grass, sedge and other freshwater marsh species provides breeding habitat for amphibians, reptiles and invertebrates such as dragonflies. Such habitat is botanically diverse (compared to aquaculture ponds) and also provides good year round foraging habitat for herons and egrets as well as, potentially, globally threatened species such as grey headed lapwing. It can also provide suitable breeding habitat for a number of locally rare freshwater marsh birds, including, for example, painted snipe, watercock and chestnut bittern.

14.3.39   Increased aquatic fauna will also provide more predictable and sustainable food resources for herons and egrets and other waterbirds throughout the year. Aquatic vegetation is also more likely to be abundant in such lakes which in turn provides favourable habitat for winter populations of wildfowl. Seasonal exposure of mud, through small reductions in water levels would also provide feeding areas for wading birds.

Objectives

14.3.40   A freshwater marsh complex composed of three distinct regions is proposed (Figure 14‑8):

·        A relatively large area of permanent marsh comprising a series of interconnected lakes and reedbeds;

·        Seasonal marsh dominated by tussocky grasses and sedges and temporary pools; and,

·        A storage pond.

14.3.41   The practical design of the proposed freshwater marsh complex incorporates the following principles:

·        The water supply will be from direct rainfall supplemented by run-off from the residential development and catchments A and B (see Figure 14‑3).

·        Treated effluent will not be discharged into the wetland and there will be no reliance on groundwater.

·        The marsh area will not flood surrounding land and residential developments.

·        The lakes within the marsh area will eventually discharge via Channel X or, during storm events, via Channel Y (see Figure 14‑3) into the Tai River outfall.

14.3.42   Water control structures will be installed at the locations indicated in Figure 14‑8 to facilitate water management within the marsh complex.

Permanent marsh area

14.3.43   The majority of the constructed marsh area will comprise a series of interlocking shallow (mostly < 0.5m) and deep lakes, the latter acting as refuges for fish and other species requiring greater depths (see Figure 14‑9). Reeds and other emergent associated vegetation will be established on the margins of these lakes.

14.3.44   The reedbeds will provide screening from disturbance for herons and egrets, and fingers of reed will create further seclusion. The vegetation will also provide an important habitat for invertebrates, especially dragonflies, potentially including the rare damselfly Mortonagrion hirosei, which is confined to reedbeds (Wilson 1995). Reedbeds are also important feeding, nesting and roosting habitats for a wide range of passerine birds, e.g. migrant warblers.

14.3.45   Water levels will be allowed to fluctuate with seasonal patterns in rainfall but will be kept within defined limits to prevent drying out or flooding of susceptible vegetation through controlled release of water from the storage pond. Water will also be released judiciously to reduce the rate at which levels drop during the transition between wet and dry seasons.

14.3.46   Varying ground levels in the reedbed will provide a variety of water depths; allowing some areas of reed to dry out during the dry season and others to remain inundated all year round.

14.3.47   A small number of islands would also be incorporated to maximise shoreline length and provide areas that are subject to less disturbance for further secure feeding and roosting sites for herons and egrets.

Seasonal marsh area

14.3.48   A segment of the western part of the marsh complex will be managed as seasonal wetland receiving water from direct rainfall, and, during wet months, from the permanent marsh area. When water exceeds a pre-determined depth within the permanent marsh area water will flow into the seasonal marsh area via a sluice placed between the two areas.

14.3.49   The seasonal freshwater marsh area will include a number of temporary pools and a greater range of plant species than the reed fringes of the permanent marsh area. These habitats hold different communities of plants and animals to permanent wetland bodies and so its inclusion as a distinct habitat will further enhance biodiversity within the proposed WNR.

14.3.50   Temporary pools are not able to sustain populations of fish and other predators and are therefore particularly valuable for certain aquatic invertebrates and as breeding sites for various amphibia, such as, potentially, the narrow-mouthed frog.  As water levels naturally drop in temporary ponds then muddy shorelines are exposed. These provide particularly good feeding areas for a range of waterbirds, including herons and egrets, as well as various crakes, rails and waders.  There is a potential to provide additional habitat for species not previously recorded at Fung Lok Wai. For example, the presence of seasonally wet grazed areas interspersed with deeper pools may attract Greater Painted Snipe. Similarly the presence of seasonal marsh adjacent to the deeper pools with emergent and floating vegetation of the permanent marsh area, including lotus Nelumbo nucifera, may also attract Pheasant-tailed Jacana.

14.3.51   Excess water with the seasonal marsh area will gather at the northern end and exit via channel Y into the Tai River outflow.

Storage pond

14.3.52   To maximise capacity, the storage pond will not have shallow margins or contain islands, but will have reed fringes to provide shelter and disturbance free-zones. Its proposed area will be approximately 3 ha with an average depth of approximately 3 m (maximum water level 3.7 m PD, bund level 4.0 m PD) and thus will have a storage capacity of approximately 90,000 m3.

14.3.53   Run-off from the residential site and catchments A and B will be transported to the storage pond via a pipe or channel system integrated into the residential development area.

Security of water supply

14.3.54   The long-term sustainability of the proposed natural wetland system is dependent on adequate year-round water supplies.

14.3.55   Although the north-west New Territories receives a high average annual rainfall, during the dry winter period evaporation exceeds rainfall and wetland areas start to loose water. There is a risk, therefore, that water levels may drop and shallow wetlands may dry out. It is essential, therefore, to establish that there will be sufficient water available to maintain the desired water depths for the wetland habitats during the winter. A monthly water quantity budget has been developed and from this feasible water levels predicted. This is provided in detail in Appendix 14-2.

14.3.56   From this water budget it is predicted that the capacity of the storage pond will be sufficient to maintain water levels within the target levels. Currently, the water budget predicts that the water level in the storage pond will not drop below approximately 29 megalitres in the dry season, leaving a reserve of approximately 33% capacity even during the driest scenario tested Figure 14‑10. This is considered to be sufficient to cope with the typical variation in rainfall levels observed in Hong Kong, especially as there is predicted to be a substantial surplus of water available to fill the storage pond in summer.

14.3.57   The maximum water demand to meet target levels would peak at about 250,000 litres per day during November.

14.3.58   A number of structures are proposed to enable manipulations of the water levels across the site (see Figure 14‑8). The storage pond will be connected to the lakes within the natural wetland area by adjustable sluices. This will allow transfer of water to the lakes either by flow over the sluice, or, when water levels in the storage pond fall below those of the lakes, by means of a pump. A sluice on the storage pond connected via drain Y will allow rapid discharge of surplus run-off water from the catchments and residential area (e.g. during storms) without affecting the other ponds.

14.3.59   The lakes will also allow discharge of water via an adjustable sluice into drainage channel X if required. The western end of the lakes will also have an adjustable sluice to provide water to the freshwater marsh area which will then exit via channel Y into the Tai River outflow.

14.3.60   Water can be re-circulated through the site, if water stagnation becomes a problem, via a pipe linking the south-west corner of the site and the storage pond (see Figure 14‑8).

Details of Marsh Habitat creation works

14.3.61   The successful establishment of freshwater marsh habitat will require a carefully structured approach to the key wetland construction stages outlined below.

Major earthworks

14.3.62   Major earth works will be required to achieve the broad profile of the freshwater marsh hydrological unit. These works can only be conducted during the dry season when the substrate is sufficiently firm for heavy equipment to enter onto the site.  Once the underlying profile of the hydrological unit has been achieved waterproof clay linings/curtains may be required at appropriate locations to prevent water leakage (it is possible that the clay based bund material (from aquaculture ponds) upon which the marsh will be created may be sufficiently impermeable that clay lining is not required, however, this will need to be confirmed at the time of construction).

Water control structures

14.3.63   Water control structures should be installed before the top soiling and fine profiling is conducted.

Top soiling and fine profiling

14.3.64   Top soiling and fine profiling of the soil can only be conducted during the dry season when the soil is sufficiently dry for the fine contouring to be implemented. The topsoil should only be applied if there is sufficient time to implement planting thereafter, otherwise it may be washed away by heavy monsoonal rain.

14.3.65   A typical composition for topsoil would be 55% aquaculture pond bund material, 30% CDG, and 15% river sand, although the exact specification should be considered further at the detailed design stage and light of the specific qualities of the material sourced. Experience in other wetland contexts indicates that pond material needs to be augmented with Calcium Oxide at a rate of 0.68kg/m3 to neutralise pH. However, the precise rate of augmentation will need to be determined at the time of construction.

14.3.66   A typical sequence for top soiling and profiling could be as follows:

·        Establish basic land formation, with (if required) clay or water proof curtains in place (and tested).

·        Carry out detailed levelling survey, with marker posts placed throughout the hydrological unit showing:

o        operational water levels and invert level of outlet control structures; and,

o        100mm increments from top water level to invert level of outlet control structure.

·        The profiling is entirely dependent on the range of water level control offered by the outlet control structure(s) and all levelling must be carried out in relation to this. Hence the need to have all control structures in place before earthworks can commence. There may also need to be some calculations made in relation to hydraulic heads (the rise in water level generated by restricting flows over a weir).

·        Carry out rough ground marking showing significant areas of any shallow (emergent) underwater spoil benches roughly in line with the design drawings.

·        Fill areas with specified soil mix.

·        As appropriate to the desired land form, carry out fine level soil manipulation with an aim of creating a random surface profile with local ridges and furrows on level shallow benches and carry out local profile detailing (small pools and hummocks) on the marginal slopes but with a general overall fall as specified.

·        The top 300mm of soil needs to be placed very carefully and compaction minimised. A settlement factor of at least 15% must be allowed for.

·        All levels to be checked prior to machinery leaving each working area to avoid the need for further movement of machinery.

Flooding and checking integrity of the hydrological unit

14.3.67   Prior to planting, each hydrological unit should be flooded with water and left for at least one week.  The water level should be checked and monitored regularly using a gauge board to determine whether the levels drop more rapidly between rainfall events than would be expected from evaporation alone. This would indicate whether waterproofing is incomplete or faulty.  The water level can be expected to drop slightly initially since the clay will absorb water.

14.3.68   To avoid time consuming and costly abortive works, the hydrological unit should be checked before soiling works are undertaken. If the hydrological unit is not intact, then the clay curtain should be removed, re-laid and the flooding exercise implemented again to confirm whether the unit is water tight.

Planting

14.3.69   To facilitate successful establishment of the plants in the newly constructed marshes, planting should commence in April and May prior to the onset of the monsoon rains to coincide with the plant growing season.  Sufficient resources should be provided for in the programme to ensure that planting can be completed within one growing season. Planting will include the following stages:

·        Ensure that the marsh is an intact hydrological unit ie. any clay curtains and control structures are sealed, intact and functional.

·        Ensure that all earthworks are complete and levels checked.

·        Set outlet control structures to an appropriate level (eg c. 100mm) below operational (final) water levels to expose most of the bed of the shallow wetland margins where emergent plants are to be placed. Each plant to be introduced should have a depth/hydrology assessment made of it (ie. the maximum, minimum and optimal depth tolerances and the ability/requirement of the plant to withstand seasonal variation in water levels). It is assumed that planting plans have been formulated on the basis that species capable of the deeper tolerance ranges are located in the deeper parts of the marsh and surface wet or seasonally inundated species are at the higher levels.

·        The general planting procedure would then be to plant species according to the layout in the planting plans (e.g. in mono-specific blocks (circles) of 5m diameter, or smaller depending on available suitable water depth/profile, with gaps of c 1-2 metre between to allow natural expansion of the species blocks or some natural colonisation). Colour coded markers would be placed prior to planting with each colour representing a species and each marker the centre of the planting block. Plants would then be planted according to the specified planting density, which should depend on the size/growth form of species and planted material. In this way the site botanist and ecologists can plan the very specific layout prior to planting.

·        In handling the plant material, the following is essential:

o        Plants, particularly rhizomes, need to be kept moist and out of direct sunlight at all times;

o        In planting rhizomatous species, damage to the rhizome can be made during firming in with tools or boots. If the substrate is soft enough plants can be pushed gently into the wet ground. Otherwise the rhizomes will be planted in dug holes and soil replaced with only gentle firming. Plug plants can be simply placed into a whole made by a suitable-sized dibber. Submerged plants must be planted underwater and are normally just pushed into the bottom sediments. In some case it may be necessary to weigh down the plant with an attached stone/weight prior to the plant developing established roots;

o        Many aquatic plants will not survive if dug from wet nursery soils and left standing in water at the planting site, prior to re-planting. Wherever possible, plants should be lifted, transported and re-planted within 24 hours. Where this is not possible, plants should be dug into holding areas of wet soil, not just stacked in shallow water alone. The soil will need to be kept wet or covered in some way to reduce water loss;

o        Soils/pots must be checked for non-target species and unhealthy, or otherwise substandard plants, and these must be appropriately discarded prior to transplanting.

Management of water levels

14.3.70   Following planting, water levels should be maintained at initial target levels.  The water level should be gradually raised to the operational level as the plants grow, this approach will also effectively control the establishment and spread of weeds.  Throughout this time water levels should be carefully controlled to protect plants from drying out (i.e. a source of water to counter evapotranspiration) or from being flooding (i.e. sporadic heavy rainfall).

Vegetation

14.3.71   A list of the species to be established in the freshwater marsh mitigation areas is provided in

14.3.72   Table 14‑12. The planting list is derived from those native species known from remaining fresh water marshes in Hong Kong (e.g. Luk Keng Marsh, Liu Pok Marsh). However, all such wetlands are highly modified by man and/or domestic animals and therefore ‘true natural’ wetland plant communities in Hong Kong cannot be easily identified. A variety of potential mix options are shown for seasonally inundated habitats and a more detailed planting plan will be produced indicating the locations of these mixes prior to commencement of marsh construction.

14.3.73   The proposed planting therefore includes a relatively long list of native species to accommodate the likelihood that not all planted species will necessarily thrive in the particular conditions to be created. Thus the approach is to facilitate natural selection as far as possible.

 

Table 1412     Species to be established in the Marsh Habitat area

                       (planting zones are shown in Appendix 14-3)

Mix / species

Total area (m2)

Shoots (number)

Density  (m-2)

% Cover

Minimum height (mm)

 

 

 

 

 

 

1. Floating plants (permanently inundated)

Nymphaea spp.

30

5

15

<1

 

Nelumbo nucifera

30

5

15

<1

 

2. Permanently inundated mix

Vallisneria natans

5210

5

12

45

500

Ottelia alismoides

5210

5

12

45

500

Hydrilla verticillata

1160

5

20

10

500

3. Reed bed

Phragmites australis

16475

3

10

100

800

4. Seasonally inundated mix A

Bacopa monnieri

690

5

20

25

150

Sagittaria trifolia

690

5

20

25

500

Polygonum barbatum

550

5

20

20

500

Eleocharis equisetina

827

5

20

30

300

5. Seasonally inundated mix B

Eleocharis dulcis

550

5

20

20

300

Polygonum glabrum

680

5

20

25

300

Schoenoplectus mucronatus

827

5

20

30

600

Cyperus malaccensis

680

5

20

25

600

6. Seasonally inundated mix C

Sagittaria guyanensis

827

5

16

30

500

Saururus chinensis

550

5

16

20

500

Eleocharis tetraquetra

690

5

16

25

500

Cyperus malaccensis var. brevifolius

690

5

16

25

500

7. Seasonally inundated mix D

Ludwigia ascendens

960

5

16

35

500

Polygonum hydropiper

550

5

16

20

500

Polygonum juncundum

550

5

16

20

500

Colocasia esculenta

690

5

16

25

500

8. Seasonal / grazed marsh mix E

Fimbristylis complanata

1810

5

12

20

400

Fimbristylis subbispicata

2270

5

12

25

400

Cyperus halpan

1810

5

12

20

400

Scirpus juncoides

1810

5

12

20

400

Fimbristylis nutans

1360

5

12

15

400

9. Seasonal / grazed marsh mix F

Fimbristylis miliacea

1360

5

12

15

300

Fimbristylis ferruginea

1360

5

12

15

300

Fuirena umbellata

1810

5

12

20

300

Rumex japonicus

1810

5

12

20

300

Cyperus falbelliformis

1360

5

12

15

300

Scirpus littoralis

1360

5

12

15

300

10. Mixed herbaceous

Fimbristylis ferruginea

1070

3

12

10

300

Scirpus juncoides

1600

3

12

15

300

Cyperus halpan

1600

3

12

15

300

Saururus chinensis

1600

3

12

15

300

Polygonum barbatum

1600

3

12

15

300

Eleocharis equisetina

1070

3

12

10

300

Nepenthes mirabilis

2140

3

12

20

200

11. Herbaceous plants on aquaculture pond bund area

Leersia hexandra

TBC

5

12

30

500

Eragrostis unioloides

TBC

5

12

30

500

Lepironia articulata

TBC

5

12

40

500

12. Bamboo clumps (planted at 50 cm centres).

Bambusa vulgaris cv. Vittata

620

100

2000

Bambusa vulgaris cv. Wamin

620

100

2000

Note: At least 5% of the areas need to be bare mud and water.

 

Access and Fencing

14.3.74   The Wetland Nature Reserve is designated as “Private Land Zone” under the Ramsar Conservation Strategy and Management Plan as it is under private ownership.  Adjacent to it is a band of Public Access Zone”. The proposed Wetland Nature Reserve can be integrated with the “Public Access Zone” forming a logical extension of this zone.  Whilst conservation is the prime objective of the Wetland Nature Reserve, limited public access will be allowed on a restricted basis (prior booking will need to be made with the reserve manager) so as not to create disturbance to birds. Residents of the development will not have privileged use of the WNR.

14.3.75   It is proposed that footpaths and hides will be provided in part of the site.  A plan of the indicative footpath network subject to detailed design of the WNP is included Figure 14‑12.  This shows that the footpaths will be limited to the southwest and west of the site, in order to:

·        avoid high levels of disturbance in the core area of aquaculture ponds;

·        provide easy access to the footpaths from the Site access; and,

·        include the full range of habitats types within the site.

14.3.76   To further avoid disturbance to wildlife within the site, the footpaths will be screened by tall vegetation or artificial screens where necessary. Footpaths will be raised on board walks (an indicative design is included in Appendix 14-4) in the wetter and more sensitive habitats or follow existing bunds.

14.3.77   Hides will be built at a number of locations to provide view points over the main habitat types on the site (lakes and reedbeds, freshwater marsh and aquaculture ponds). A design for a hide is provided in Appendix 14-5.

14.3.78   Occasional guided tours (prior booking with the reserve manager will be required) can also be provided.  Some educational facilities can be provided, including information boards at the site entrance, inside hides and at appropriate locations alongside the footpaths. These will provide basic information on the ecology and conservation importance of the wetland habitats, information on the management and cultural aspects of fish farming and its importance for wildlife.

14.3.79   The emphasis on access would be to provide simple 'low-key' facilities that would primarily be used by people with an interest in natural history. Picnicking and similar activities will not be allowed within the WNR. The maximum number of visitors that can be accommodated without causing unacceptable levels of disturbance could be limited to the number of seats / space available in the hides. Discussions with the Reserve Manager at Mai Po indicate that a cautious approach is appropriate and that, during the initial stages of WNR management, visitor numbers are kept low. Numbers of visitors can be increased at the discretion of the reserve manager as experience in the management of the WNR grows.

14.3.80   Facilities for visitors will be kept to a minimum, but will include toilets, a shelter with drinks machine and a small car park. The location of these facilities is indicated in Figure 14‑12.

14.3.81   Vehicular access to the wetland mitigation areas will be restricted by means of lockable gates to be located at appropriate positions.

14.3.82   The residential development works area will be screened off from the rest of the site before the start of any works, to reduce disturbance to wildlife in the surrounding area. Similarly the freshwater marsh area will be screened off from the surrounding wetland areas during the wetland construction works.

14.3.83   Screening will consist of solid hoarding of at least 2 m height.

Management facilities

14.3.84   A small office, storage, workshop area and quarters will be constructed for the WNR Reserve Manager and his / her staff. These facilities will take the form of small prefabricated buildings that can be placed in a convenient location. The site for these facilities will be determined once the construction of the WNR is completed. During construction the WNR Reserve Manager will occupy a temporary facility the location of which will be determined during planning for the construction works.

 

14.4          Management Strategy

Management regime stages and programme

Interim Management

14.4.1      To compensate for disturbance caused during the construction phase of the residential development and the marsh habitat interim management will be implemented to increase the attractiveness of unaffected ponds to wetland bird Species of Conservation Importance.

14.4.2      Essentially interim management will involve artificially increasing the carrying capacity of ponds for these species through works designed to significantly increase the availability of prey species (trash fish). The following specific actions, which have been implemented as appropriate mitigation at similar sites elsewhere in Hong Kong (eg Binnie, Black & Veatch 2002):

·        The fish populations within ponds will vary greatly depending on previous management. A rapid assessment of remaining populations will be carried out and ponds re-stocked, as required, with trash fish species;

·        Initial and ongoing correction of water quality, specifically pH to ensure appropriate conditions for fish survival. Although trash fish species are relatively hardy compared to many commercial fish, they can be affected by low pH conditions. If pH drops below 4.5 then peanut residue will be added to raise pH; and,

·        Rotational, partial drain down of pairs ponds (excluding Ponds 2, 3 and 11). Once drained down each pair of ponds will be maintained with shallow water < 30 cm deep for a period of 4 weeks.

14.4.3      Under traditional management the production of non-commercial by-product, including prawns and fish, such as Tilapia, that are below marketable weight is in the order of 260 kg/ha/year (See Section 12.4, Aspinwall, 1997 and Primavera, 2000). To achieve the mitigation targets the availability of small fish and prawns will need to be increased to provide enhanced feeding opportunities. Experience from the implementation of a similar approach by KCRC at Lok Ma Chau indicates that optimal stocking densities are likely to be in the range 2-5 times the expected ‘normal’ biomass of trash fish, ie up to 1,300 kg/ha/year. Imported fish will comprise small Tilapia (target weight approximately 50g / individual). A key reason for the relatively large increase in stocking density is due to the fact increased prey availability benefits a wide variety of piscivorous birds, including cormorants and ardeids, all of which can be expected to increase in numbers within the mitigation area.

14.4.4      Reference to recent monitoring reports from monitoring of the Lok Ma Chau mitigation works (AEC 2003, 2004, 2006a, 2006b) indicates that the densities implied for key species (Black-faced Spoonbill, Chinese Pond Heron, Great Cormorant, Great Egret and Little Egret) are readily achievable (and have been frequently exceeded). The experience at Lok Ma Chau also indicates that a flexible (adaptive management) approach is required. The effectiveness of mitigation requires careful attention to water quality, adjustment to stocking densities, periodic review of the timing and duration of draw-down and continuous monitoring.

14.4.5      Prior to the commencement of interim management a plan for pond draw-down will be confirmed. This plan will specify the sequence of draw-down ensuring that no pond is drawn-down more frequently than once per calendar year. Particular attention will be given to the stability of re-profiling works (some settling and adjustment is inevitable), the status of fish stocks and water quality. The condition of newly planted Phragmites reeds and Paspalum will also be monitored and remedial action taken as required to ensure they fully establish.

14.4.6      Interim management will commence at an early stage of the construction of the Residential Development and WNR as described in Section 13.9. In summary, however, the key stages are briefly described below, these stages are shown graphically in Figure 1313 (dates shown are indicative):

Pre-Construction Phase I (Jul ‘10– Sep ‘10)

14.4.7      During this phase the developer will take occupation of the site and make preliminary preparations including erection of site fencing. No specific habitat management is envisaged at this stage and all ponds will remain under their current aquaculture regime. All ponds will potentially be available as habitat, that is no ponds will be directly affected by construction activities.

Pre-Construction Phase II (Oct ’10 – Mar ’11)

14.4.8      During this phase pond enhancement works will commence (see above). To minimise disturbance and to maximise the extent of available habitat these works will be undertaken progressively within Sector 1 (the extent of Sector I is approximately 20.4 ha). The works involved in enhancement include the draining of adjacent ponds and the excavation of the intervening bund. This will be done according to the construction plan of the Wetland Nature Reserve. These works are similar to normal pond management activities and are not in themselves expected to cause undue disturbance to birds, nevertheless to minimise potential disturbance impacts, pond enhancement works will be phased.

14.4.9      The maximum area of pond affected by these enhancement activities during this Phase will be 4.2 ha (representing the largest ponds that will be concurrently drained and re-profiled). Prior to, and following enhancement works, the ponds will be filled with water and are considered to be available as habitat for birds and other Species of Conservation Importance.

14.4.10   During these works the ponds located within Sectors 2 (21.3 ha) and 3 (20.1 ha), the area proposed for marshland (14.4 ha) and development area (4.0 ha) will remain under their existing management regime ensuring that, throughout this Phase, at least 76.0 ha of pond will remain as available.

Pre-Construction Phase III (Apr ’11 – Sep ’11)

14.4.11   During this Phase enhancement works will commence in Sector 2 and site clearance will commence in the Development Area. The enhancement works in Sector 2 will follow the same pattern as described above, however, the maximum area affected at any one time will be slightly larger at approximately 6.1 ha. Once the Development Area clearance is complete a further, approximately, 4.0 ha of pond habitat will become unavailable. During this Phase, therefore, the minimum pond area available as habitat will be approximately 70.0 ha.

14.4.12   To compensate for this reduction in habitat area it is proposed to commence interim management in the Sector 1 ponds (all of which were enhanced in Phase II). The interim management strategy is to increase the carrying capacity of ponds by drawing them down for longer periods than is normal under traditional management and to artificially increase the availability of prey species for wetland birds through stocking of trash fish species. The key elements of the interim management plan include:

·        Management of water quality, specifically pH to ensure appropriate conditions for fish survival. Although trash fish species are relatively hardy compared to many commercial fish, they can be affected by low pH conditions. If pH drops below 4.5 then the cause will be investigated and appropriate steps taken to return pH to an appropriate level;

·        Rotational, partial drain down of pair ponds. Once drained down each pair of ponds will be maintained with shallow water < 30 cm deep for a period of 4weeks;

·        Stocking of trash fish as required to ensure that target carrying capacities are met; and,

·        Minimising human presence to limit disturbance.

Pre-Construction Phase IV (Oct ’11 – Mar ’12)

14.4.13   Interim management will continue at Sector 1 (20.4 ha) and commence at Sector 2 ponds (21.3 ha). In addition interim management will also be implemented in Sector 3 ponds (20.1 ha, although these are yet to be enhanced). No pond enhancement works will be undertaken during this Phase. Creation works will commence within the marshland area, while site clearance continues in the development area, making approximately 14.4 ha and 4.0 ha, of pond area unavailable, respectively. Consequently a minimum of 61.8 ha of pond area will be available, all of which will be under interim management.

14.4.14   During this phase the physical activities associated with marsh creation works will be completed with planting taking place in the following Phase. 

Pre-Construction Phase V (Apr ’12 – Sep ’12)

14.4.15   Interim management will continue at Sector 1 (20.4 ha) and 2 ponds (21.3 ha).  Ponds in Sector 3 will undergo enhancement occupying a maximum of 3.8 ha at any one time while the remaining 16.2 ha of pond area will be kept under interim management.  Planting of marshland habitats will take place followed by approximately 12 months of establishment. For the purposes of this assessment it is assumed during this period that all the marshland habitat (14.4 ha) will be unavailable as habitat (although it is actually likely that some species will begin to make use of it). Site clearance and preparation works will continue in the development area (4.0 ha). Thus a minimum of 57.9 ha of pond area will be available, all of which will be under interim management.

Pre-Construction Phase VI (Oct ’12 – Jun ’13)

14.4.16   Marsh establishment will continue (and hence assumed to be unavailable). Interim management will continue at Sector 1 (20.4 ha), 2 (21.3 ha) and 3 ponds (20.1 ha) resulting in a total area of available pond area of 61.71 ha, all of which is under interim management.

Construction Phase (Jul ’13 – Sep ’16)

14.4.17   Construction works are programmed to commence in July 2013. During this phase all pond enhancement works will be completed and a total area of 61.8 ha of ponds will be under interim management in Sectors 1, 2 and 3.  Marsh establishment is expected to be substantially complete (although maturation will continue over several additional years). Consequently there will be an additional 14.4 ha of marshland habitat available.

14.4.18   The commencement of construction works will result, however, in the generation of substantially higher levels of noise and vibration and hence disturbance than was experienced during Pre-Construction Phases. It is assumed, therefore, that sections of wetland habitat adjacent to the construction area will be functionally unavailable to species that are sensitive to disturbance. The extent of these areas was assessed in Section 13.8 and are summarised in Figure 13‑12 and Table 1355.

14.4.19   The key strategy for mitigating these disturbance effects is to maintain interim management in all of the enhanced Sector 1, 2 and 3 ponds. It is anticipated that interim management will increase the carrying capacity of these ponds sufficiently to off-set temporary functional habitat loss associated with the displacement of birds from areas affected by construction phase disturbance.

14.4.20   The objective, therefore, during this Phase is to provide habitat of sufficient quality to maintain the numbers of birds observed during the baseline. To gain an indication of the existing carrying capacity of the Fung Lok Wai wetlands, the survey data obtained during the baseline survey were analysed to identify the maximum number of birds recorded. These data were then converted to densities by dividing the maximum number of individuals observed within the within the Study Site by the extent of wetland in the Study Site (approximately 80.1 ha). The Study Site sits within a larger area of wetland habitat, for comparison this table also shows the maximum and mean number of individuals of Species of Conservation Importance observed within the total Assessment Area. These are also shown as densities achieved by dividing the counts by the extent of wetland within the Assessment Area (approximately 170.6 ha of wetland). These data are shown in Table 13‑59.

Marsh construction and establishment

14.4.21   The Constructed Marsh Area and the Development Area are adjacent to each other. This provides an opportunity for reducing disturbance associated with construction by combining activities involved in heavy earthworks, such as pond removal and site formation. These activities have, therefore, been programmed to occur at the same time.

14.4.22   An additional advantage of the concurrence of these activities is the ability to immediately relocate soil removed from the development area to the marsh area where it can be used for site formation. This process obviates the need for temporary storage areas for this material.

14.4.23   Once site formation works for the constructed marsh area have been completed it is anticipated that top-soiling and ground shaping can be completed within the same dry season. Planting works are programmed to commence with the on-set of the wet season when the ground is moist, increasing the likelihood of plant survival.

14.4.24   During the first twelve months after planting, the condition of plants must be closely monitored. Any plants that die or fail to thrive should be replaced. Any emerging weeds should be removed as soon as they are detected, preferably by hand, but if they become established or otherwise difficult to remove then limited application of appropriate herbicides should be considered as a last resort. During the establishment period water levels must also be closely monitored as these will have a significant bearing on the performance of young plants.

14.4.25   Establishment management actions should be reviewed after the first year.

Long-term management

Aquaculture pond management

14.4.26   During this phase all of the enhanced aquaculture ponds will be managed according to the long-term management plan outlined below and their performance monitored.

14.4.27   As described above the majority of the target species of conservation occurring within the site benefit from traditional fish farming activities. The enhancement of the aquaculture ponds within the mitigation area will therefore include the continuation of active traditional fish farming management in each on most of them. 

14.4.28   In most respects aquaculture pond management will represent a continuation of existing fish polyculture practices, which can be briefly characterised as a three stage process:

·        Stocking – introduction of fish as fingerlings or juveniles (as determined by availability) at a density of about 14,000 fingerlings per hectare (lower for juveniles). The species stocked also tend to be determined by market availability and price but typically include carp (such as, for example, bighead, common carp, grass carp), mullet (eg grey mullet) and Tilapia;

·        Rearing – Through the year fish farmers typically add food to promote fish growth. The type of food added depends on price, availability, stage of growth and the personal preferences of the fish farmer, but could include, for example, corn meal, peanut cake, wheat bran, rice bran, biscuit, brewery waste, soya bean and vegetation clippings. If the pH of the pond drops then farmers will adjust water back to normal levels through the addition of lime or peanut residue. The timing and quantity of such additions is dependent entirely on water quality conditions. Aeration devices may also be employed if oxygen levels fall below critical levels for fish survival.

·        Harvesting – when fish are ready for harvesting pond levels are dropped and fish captured. Commercial fish are removed and sold, however, trash species will be left in the shallow water of the pond and these form an excellent food source for birds such as herons and egrets.

14.4.29   The main long-term management enhancement of the ponds will be to regulate and extend the period of draw-down for harvesting. Under current fish-farming practices harvesting is carried out in winter by reducing the water depth of the pond (by pumping water to another pond for storage) and the gradual netting of the stock over a couple of weeks. However, the precise dates of harvesting are dependent on market prices and this can result in food-resource ‘bottle-necks’ if no or few ponds are drained at any one time. Draw down of the ponds will therefore be carried out on a regular basis irrespective of the market value of fish.

14.4.30   Draw-down periods will also be for a fixed time of 20 days. This is longer than normal and will thus further increase feeding opportunities thereby further reducing potential feeding bottle-necks.

14.4.31   It is also proposed that at any one time approximately 25% of the aquaculture pond area will be taken out of production (on a rotational basis) for one season. This will provide additional shallow water habitats that will be used by targets species such as herons and egrets.

14.4.32   The operating water levels for each pond will be specified once survey and re-profiling works have been completed. The following levels are to be specified for each pond which are illustrated schematically in Figure 14‑14:

·        Initial Operating Level (IOL) level for ponds when filled / refilled during the winter after drain-down or harvesting. IOL is set so that water level is coincident with any shelves in the bund such that created shallows are created. Typical IOLs for fish ponds would be in the range 1.2 to 1.9m above base.

·        Maximum Operating Level (MOL) indicate the level above which water must be removed from the pond by sluice drainage or pumping (off-site or to other ponds as appropriate). In practice the MOL will be determined for each based on its the height and structural integrity. Typically MOL would be in the range of IOL + 0.3m (+/- 0.1m).

·        The MOL for the rain fed ponds will be more specific. Pond 2 will be set a max of 1.0m. Pond 3 will be set to a max depth of 0.5m from May to July, raised to 0.8m between August and April. Pond 11 will be set to a max depth of 0.3m from May to July, raised to 0.6m between August and April.

·        Low Operating Level (LOL) is expressed as a range within which pond level is maintained during periods of set-aside. LOL range is typically 0.1-0.3 m in order to maintain sufficient depth to prevent acid soil problems. Soil exposed to air may become acidic. If water quality (and productivity) is affected by acidic leachate being flushed into the pond by run-off then appropriate measures may be required to neutralise the affects (such as, for example, application of lime or fertilizers).

14.4.33   If water levels exceed target levels, then water will be pumped to other ponds for storage. Decisions on the use of excess water will be made by the WNR Reserve Manager according to site conditions and requirements at the time.

14.4.34   Water levels will be monitored (via a permanent gauge board in each pond) at least weekly from the start of the trial, or within one day of heavy rainfall events (i.e. > 100 mm of rain in the NW Territories over 24 hours).

14.4.35   Ponds will be used in a 5 year rotational sequence of fish farming / shallow set-aside ponds (with no fish stocking). Thus approximately six of ponds will be set-aside from production in any one year, two of which will be used as a contingency reservoir pond. The long-term management programme for the aquaculture ponds (other than those ponds that are to be retained as Rain-Fed ponds) is described below in Table 14‑13. The sequence of use of each pond is based on a start in January of each year (with stocking) and assumes that all ponds have been joined where intended and all water control structures have been installed.

14.4.36   The sequence of drain-down, harvesting and refilling for each set of ponds is not of critical conservation management importance. This can therefore be carried out as required to reduce pumping and water loss from the system.

14.4.37   When ponds are drained down for harvesting, water levels must be maintained at or below Low Operating Levels for at least 20 days. No more than two ponds may be drained-down for harvesting at any one time.

14.4.38   After year 5 it is likely that the sequence will be repeated, but modifications may be made, as part of ongoing revisions of the Operational Management Plan (see below), as a result of lessons learnt from the monitoring of use of the ponds by target Species of Conservation Importance and their prey populations.


Table 1413     Long-term pond management (5 year cycle)

Pond

Year 1

Year 2

Year 3

Year 4

Year 5

1

Set-aside

Fish production (Fill from 7)

Fish production

Set-aside (Move to 6)

Fish production (Fill from 7)

4

Fish production

Set-aside (Move to 5)
Fish production (Fill from 5)
Fish production
Fish production

5

Set-aside

Reservoir (Fill from 4)

Fish production (Move to 4)
Fish production
Set-aside (Move to 9)

6

Fish production

Fish production

Set-aside (Move to 7)
Fish production (Fill from 1)
Fish production

7

Fish production

Set-aside (Move to 1)
Fish production (Fill from 6)
Fish production
Set-aside (Move to 1)

8

Reservoir

Set-aside (Move to 12)

Fish production (Fill from 12)
Fish production
Fish production

9

Fish production

Fish production
Reservoir (Fill from 13)
Set-aside (Move to 12,13)
Fish production (Fill from 5)

10

Fish production

Fish production

Fish production

Reservoir (Fill from 14)

Fish production (Move to 14)

12

Set-aside

Fish production (Fill from 8)

Set-aside (Move to 8)

Fish production (Fill from 9)

Fish production

13

Fish production

Fish production

Set-aside(Move to 9)

Fish production (Fill from 9)

Fish production

14

Fish production

Fish production

Fish production

Set-aside (Move to 10)

Fish production (Fill from 10)

15

Set-aside

Fish production (Fill from 16)

Fish production

Fish production

Reservoir (Fill from 17)

16

Reservoir

Fish production (Move to 15)
Set-aside (Move to 18)
Fish production (Fill from 18)
Fish production

17

Fish production

Reservoir (Fill from 18)

Fish production (Move to 18)
Fish production
Set-aside (Move to 15)

18

Fish production

Set-aside (Move to 17)

Reservoir (Fill from 16, 17)

Fish production (Move to 16)

Set-aside (Move to 19)

19

Fish production

Fish production

Fish production

Fish production

Reservoir (Fill from 18)

20

Fish production

Fish production

Fish production

Reservoir (Fill from 21)

Fish production (Move to 21)

21

Fish production

Fish production

Fish production

Set-aside (Move to 20)

Fish production (Fill from 20)

Note: Refer to Fig 14-1 for the location of ponds

Set-aside

Maintain within LOL limits. Empty and allow to dry for 30 days between 1 October and 15 December.

Fish production

Stock between 1 January and 1 March.  Drain down to LOL for at least 20 days and harvest 1 November – 14 February (of subsequent year).

Reservoir

Maintain water levels up to Max Level through year. Use as storage pond and for maintaining target levels in other ponds if necessary


Table 1414     General management actions for the Fung Lok Wai WNR

 

Action

A. Construction Phase

B. Long-term Management Phase

Notes

 

Water Control

 

 

 

W1

Measure water levels and adjust sluice heights or pump accordingly to meet target levels (see Figure 14‑14).

Inspect and adjust as necessary every 48 hrs (April – September) every week at other times

Inspect and adjust as necessary every 48 hrs (April – September) every week at other times

 

W2

Inspect condition of water control structures and water courses and repair / maintain as necessary

Weekly

Weekly

 

W3

Inspect condition of pumps and water supply structures and repair / maintain as necessary

Weekly

Weekly

 

W4

Clear catchpits / sluices

Weekly

Weekly

Also after flooding / heavy rainfall

W5

Remove sediment

Not required

As required

WNR Reserve Manager to determine requirement

 

Structural maintenance

 

 

 

S1

Inspect condition of paths / bunds and repair / maintain as necessary

Weekly

Weekly

Also after any flood events

S2

Inspect condition of fences and gates and repair / maintain as necessary

Weekly

Weekly

Also after any flood events

S3

Inspect condition of hides / signs / visitor facilities and  repair / maintain as necessary

Weekly

Monthly

Also after any storm events

 

Vegetation management

 

 

 

V1

Replacement of dead or poorly growing plant material

Weekly or on the advice of the WNR Reserve Manager

When Action Level exceeded

Carry out during the late dry season / early wet season (February – May)

V2

Removal / substitution of exotic / undesirable invasive plants (weeding)

Weekly

Removal when Action Level exceeded

 

V3

Pest control

 

On the advice of the WNR Reserve Manager

On the advice of the WNR Reserve Manager

According to methods approved by the WNR Reserve Manager

V4

Selective cutting or pruning and removal

On the advice of the WNR Reserve Manager

On the advice of the WNR Reserve Manager

 

V5

Ditch clearance

Not required

Remove all reed rhizomes from 25% of ditch length annually

Remove by hand in 3 m sections on alternating banks

V6

Grazing by water buffalo or manual grass cutting as appropriate

Not required

Light grazing after one year, under supervision of the WNR Reserve Manager

Leave 20% ungrazed in any one year on 5–year rotation.

 

Other actions

 

 

 

O1

Inspect for dumping / rubbish and remove

On all visits

On all visits

Consult management team regarding water pollution or toxic materials

O2

Inspect and maintain signs

Monthly

Monthly

 

Other management actions

14.4.39   Other management actions to be taken over the WNR area are outlined in Table 14‑14.

14.4.40   Water levels will be adjusted within the freshwater marsh according to year to year site conditions and ecological requirements for target species. These target water levels will be set by a suitably qualified ecologist within the site management team after inspection of the site and water monitoring data.

14.4.41   Water levels may be allowed to drop to below ground level to allow access for maintenance when necessary.

14.4.42   In addition to the management of the fish farming system, some management of the aquaculture pond bund vegetation will also be undertaken. This will mainly involve the control of tall vegetation such as reeds. Although some patches of reed should be encouraged to develop for cover and screening purposes these must be controlled as ponds that are enclosed by tall vegetation tend to be avoided by many of the larger herons and egrets.

14.4.43   Management will also be carried out of undesirable invasive weeds if necessary.

14.4.44   Vegetation shall only be removed by cutting and removal of roots / rhizomes by hand or machine (e.g. backhoe). The use of herbicides will not be allowed, unless deemed to be necessary (e.g. for treating some invasive species) by the WNR Reserve Manager in consultation with an appropriately qualified ecologist.

14.4.45   Grass clippings can be placed in fish ponds as a feed supplement for herbivorous fish such as carp, however, more substantial vegetation will be disposed of off-site in an appropriate manner.

14.4.46   Great Cormorant are known to predate upon fish within aquaculture ponds. The level of predation predicted in the EIA was not considered to be significant in terms of the ability of the WNR to achieve its conservation targets, primarily because the mitigation targets for this species are relatively low. During the operational phase the target density is 0.08 birds ha-1. Nevertheless, the level of predation will be monitored and appropriate (non-lethal) measures implemented to limit predation if it reaches unsustainable levels. Non-lethal measures could include, for example, wires spaced at between 5m and 7.5m. This is known to be effective at deterring cormorants, and has been used successfully at carp ponds of up to 4ha in size. Wires would be used selectively within ponds to balance the need for fish production and to maintain population levels for the purposes of achieving mitigation targets.

Responsibilities

14.4.47   The management arrangements for the WNR are addressed in more detail at Section 15.

14.4.48   Upon the completion of the construction of the WNR, the Development Site will be sub-divided into two portions:  the WNR portion and the residential portion.  The operation and management of the WNR will be independent from the management of the residential development.  The WNR will be managed by the proponent until a designated successor such as an independent Foundation is identified to the satisfaction of EPD or its agents..  The residential development, which will be under strata-titled ownership will be independently managed by the property manager appointed by the owners of the residential development.  The residents in the residential development will neither have privilege over the general public for access to the WNR nor the liability of its maintenance.

Operational Management Plan

14.4.49   Once the WNR is operational the HCMP will be replaced by an Operational Management Plan (OMP) with detailed specifications and timings for management actions during long-term management. The OMP will take into account any modifications that were found to be necessary in the design and establishment methods used for creating the habitats, the degree of success in establishing the habitats and any changes in the factors affecting them. Management actions will also need to respond appropriately to the outcome of monitoring where it is found that Action Levels and Limits as defined in Section 14.5 are exceeded.

14.4.50   The OMP will be a working document and reviewed annually, so that proposed actions are modified according to progress, monitoring results and other relevant events. The OMP will be thoroughly revised every five years. The five-year revision will include a through analysis of all monitoring data and a review of the vegetation communities that have established, with an identification of areas to be cleared and replanted.

14.4.51   Reviews of the OMP and monitoring results will be signed off by the relevant authority under the EIAO.

Contingency measures

14.4.52   Measures have been included in the design, construction methods, management and monitoring proposals that aim to ensure the successful establishment and long-term sustainability of the wetland as effective compensation habitat for key target species.

14.4.53   The wetland designs also have in built contingency measures for key factors affecting wetland establishment, especially regarding water supply, water retention and plant establishment. These include:

·        The collection and storage of water from the surrounding catchment and site run-off to supplement direct rainfall supplies to the freshwater marsh area.

·        The use of fishponds as reservoirs (on a rotational basis) to maintain water levels within target tolerances if required (a practice not normally deemed necessary by fish pond operators)

·        The use of a clay base liner if tests indicate that water losses from the freshwater marsh wetland are outside tolerable limits. Further potential contingency actions if required could include placement of impermeable membranes in specific problem areas or insertion of vertical plates (or membranes) at the edge of the wetland to reduce lateral seepage.

·        High planting densities to accommodate poor plant survival (and reduce potential weed growth).

14.4.54   Routine construction and establishment phase and long-term management actions, such as weed clearance, replanting, thinning and water level control will also be undertaken. These also aim to ensure the successful establishment and long-term sustainability of the wetland cells.

14.4.55   In addition, specific contingency actions will be defined in a Contingency Action Plan (to be prepared by the Contractor prior to the development of the wetland construction Method Statement) and agreed before commencement of works. As a minimum, contingency measures will be prepared for potential:

·        inadequate water supply;

·        failure of water pumping system;

·        damage to sluices and drainage structures;

·        pollution of water supply;

·        direct pollution of wetland cells by toxic substances (e.g. from spillage’s / dumping);

·        unacceptable plant survival rate or growth during the 2 year establishment phase;

·        invasion by exotic or other undesirable plant species;

·        flooding of the site and other potential effects from storm events.

14.4.56   Intensive monitoring will be carried out of the physical and ecological performance of the wetland mitigation area during the construction and establishment phases and in the long-term. The monitoring will be carried out in relation to defined “Action Levels” and “Limits” (see Section 14.5) which trigger appropriate actions to rectify problems. Where necessary these will include actions defined in the Contingency Action Plan.

 

14.5          Monitoring and action plans

General requirements

14.5.1      The following sections outline the monitoring requirements to ensure that the WNR is achieving its objectives during the various phases of its operation.

14.5.2      The start of the construction phase is dependent on the approval of the EIA and the preparation of a detailed project timetable. Detailed ecological monitoring will be undertaken from the commencement of works subject to the preparation of a detailed Environmental Monitoring and Audit Manual.It is intended that the data obtained from monitoring will inform the adaptive management of the WNR, consequently it is important that there is flexibility in the variables that are measured, the frequency and timing of survey and the methods used. The monitoring programme will, therefore, be reviewed periodically to ensure that it is achieving its aims.

14.5.3      After completion of the lease modification/land exchange, an environmental committee will be set up to advise on and monitor the effectiveness of the proposed mitigation measures of the construction of the Project according to the HCMP and the EIA report.  The function and membership of the environmental committee shall be in line with those of the Lok Ma Chau Spur Line project.  A list of members and terms of reference of the environmental committee shall be submitted to the Director of Environmental Protection for prior approval.

14.5.4      The key criteria by which the success of mitigation will be assessed are the provision of appropriate habitats and the maintenance of populations of Species of Conservation Importance. The specific targets for habitats and species are summarised in Section 14.2 above.

14.5.5      During the construction and operation phase a monitoring programme will be carried out of the ecological attributes proposed in Table 1415 according to the EM & A Manual The schedule shall be reviewed, updated and revised prior to construction and operation of the WNR for the approval of the relevant authorities.  Once construction is completed monitoring will also be undertaken during the long-term operation of the WNR. Prior to the implementation of long-term monitoring, survey methods and frequency will be reviewed in light of the outcomes of construction phase monitoring.

 

Table 1415   Ecological monitoring programme for Fung Lok Wai WNR

Ecological attribute

Number of measurements

Timing

Frequency of measurement

 

 

 

Construction phase

Long-term management phase

Habitats

 

 

 

 

Vegetation map

All of WNR

Wet and dry season

On completion of construction works

After completion of construction works survey every 6 months  (wet and dry season) for first 5 years at which point frequency of survey will be reviewed

 

 

 

 

 

Plant species

 

 

 

 

Survival, health and growth of plant species planted

Aquaculture ponds:

Visual assessment of all areas

 

Monthly for one year on completion of enhancement works

Annually thereafter

Constructed marsh habitat:

100 randomly marked plants in each planting zone

 

Weekly for first 2 months after planting, then monthly for remainder of the first year

Quarterly in second year after planting then annually thereafter

Plant species richness, relative abundance and cover

 

Frequency and cover of alien and invasive plant species

Aquaculture ponds:

Continuous visual assessment

 

Continuous

Continuous

Constructed marsh habitats:

Ten 1m x 1m quadrats per planting zone

 

Continual visual assessment of alien and invasive species abundance will also be conducted by the WNR management staff

Wet and dry season

6 monthly during establishment

6 monthly (wet and dry season) for first 5 years at which point frequency of survey will be reviewed

Dragonflies: species richness and abundance

Establish representative transects throughout WNR

March – November

During interim management period: Monthly during March, September, October and November. Twice monthly during April – August

During long-term management period: Monthly during March, September, October and November. Twice monthly during April – August. Frequency of monitoring to be reviewed after 5 years.

Aquatic invertebrates: species richness and abundance

Aquaculture ponds:

Five benthic cores and dip nets within 5 fish ponds

End of wet season (Aug / Sept)

Annually during interim management period

Annually

Constructed marsh habitat:

Five benthic cores and dip nets at five locations

Wet and dry seasons

During establishment: 6 monthly during wet and dry season

Thereafter 6 monthly during wet and dry seasons.

 

Frequency of monitoring to be reviewed after 5 years.

Freshwater fish: species richness and abundance

Aquaculture ponds:

Record species, abundance, average length and average mass of all species removed at harvesting

 

Every two months (throw and drag netting) during interim management period

Annually at harvesting and every two months (throw and drag netting).

 

Frequency of monitoring to be reviewed after 5 years.

 

Constructed marsh habitat:

Netting within representative areas of the permanent marsh

 

Every two months (throw and drag netting) during establishment

Thereafter every two months (throw and drag netting).

 

Frequency of monitoring to be reviewed after 5 years.

Amphibians: species richness and abundance

Establish representative transects throughout WNR

April – November

During interim management period: monthly during period April - November

Thereafter monthly during period April – November.

 

Frequency of monitoring to be reviewed after 5 years.

Reptiles: species richness and abundance

Establish representative transects throughout WNR

April – November–

During interim management period: monthly during period April - November

Thereafter monthly during period April – November.

 

Frequency of monitoring to be reviewed after 5 years.

Birds: species richness and abundance

(see above for specific details on bird monitoring)

Aquaculture ponds:

Each pond

 

Weekly during interim management period

Weekly monitoring supplemented by opportunistic records at other times. More frequent monitoring may be required during specific mamagement activities (eg pond draw down)

Constructed marsh habitat:

Each marsh type (ie seasonal marsh and permanent marsh)

 

Weekly during interim management period

Weekly monitoring supplemented by opportunistic records at other times

Hydrology

 

 

 

 

Water surface level

Aquaculture ponds:

One gauge board per pond

 

Daily during interim management period

Weekly and after heavy rain

Constructed marsh habitat:

Two gauge boards per marsh type

 

Daily during establishment

Weekly and after heavy rain

Water chemistry

 

 

 

 

Water quality variables:

pH

BOD

DO

Ammonia concentration

Conductivity

Turbidity

Temperature

Suspended solids

Salinity

Aquaculture ponds

 

 

Monthly during interim management period

Monthly

Constructed marsh habitat:

At representative locations within each marsh habitat

 

Monthly during establishment

Monthly

Water quality variables:

Total oxidised nitrogen

Total phosphorus concentration

Orthophosphate concentration

 

Aquaculture ponds

 

 

Once on completion of enhancement works

Monthly for first year at which point frequency will be reviewed

Constructed marsh habitat:

At representative locations within each marsh habitat

 

Once on completion of construction works

Monthly for first year at which point frequency will be reviewed

Heavy metals (Cadmium, Copper, Nickel, Lead, Zinc, Mercury)

Aquaculture ponds:

Representative aquaculture ponds adjacent to the active construction area

 

 

Once on completion of works

Annually thereafter

Constructed marsh habitat:

At representative locations within each marsh habitat

 

Once on completion of works

Annually thereafter

 

Reporting

14.5.6      All data recorded during monitoring will be recorded on standardised pro formas. Each year a summary report will be produced by the WNR Reserve Manager detailing the outcomes of monitoring and indicating any remedial actions taken or required.

Event and action plan for ecological attributes

14.5.7      The results of the ecological monitoring shall be compared with Action Levels and Limits detailed in Table 14‑16 and corrective actions taken accordingly.

14.6          HCMP Reporting and Review process

14.6.1      This is a draft document and key details presented here, including, for example, stocking densities and monitoring requirements are to be finalised subject to the endorsement of AFCD or other appropriate authority. The frameworks for such details are given in this section below and if changes are required in light of the changing environment / baseline, such changes would need to be agreed with AFCD or relevant authorities. This draft HCMP shall, therefore, be reviewed, updated and revised prior to the construction of the WNR and submitted for the approval of the relevant authorities.

14.6.2      The regime documented in the HCMP (and during the operational phase, the OMP) will be reviewed on an ongoing basis, for example, every 5 years (or as otherwise required) and submitted for approval by the relevant authorities.

14.6.3      An annual monitoring report detailing the results of monitoring undertaken as outlined in Section 14.5, the achievement of objectives and any adaptive modifications to the HCMP (or OMP) and its objectives will be reviewed and submitted for approval by the appropriate authorities.

 


Table 1416     Key Action Levels and Limits and their associated management actions

 

Action level

Action

Limit

Action

Plant species

 

 

 

 

Survival, health and growth of plant species planted

<75% survival of any planted species

Check soil and water conditions; replace dead material. If survival rate does not increase implement contingency plan

<30% survival of any planted species

Implement contingency plan

> 10% fungal or pest infestation of any species with >50% loss of vegetative growth

Remove dead and infected material, identify pest / infection

> 30% fungal or pest infestation of any species with >50% loss of vegetative growth

Plant species richness, relative abundance and cover

<75% species survival within planted areas

Within first 2 years of establishment: Replace plants and check soil and water conditions

After 2 years: on direction of WNR Reserve Manager implement contingency plan

<50% species survival

Plant community composition

Wetland plant species comprise <95% of vegetation

Review observed water levels against targets

Wetland plant species comprise <90% of vegetation

Frequency or cover of any individual species is <50% or >200% of proportion allocated in planting plan

Replace or remove plants as necessary

Frequency or cover of any individual species is <10% or >1000% of proportion allocated in planting plan

Frequency and cover of alien and invasive plant species

Alien species >5% of total cover

Remove plants as necessary

Alien species >10% of total cover

Remove or utilise limited spot spraying of appropriate herbicide on direction of WNR Reserve Manager

Animal species

 

 

 

 

Dragonflies: species richness and abundance

No increase from baseline over 2 consecutive years

Review management actions

Decline from baseline over 2 consecutive years

Investigate causes and review management actions

Aquatic invertebrates: species richness and abundance

Establish action levels after 2 years of monitoring*

Establish actions after 2 years of monitoring*

Establish action levels after 2 years of monitoring*

Establish actions after 2 years of monitoring*

Freshwater fish: species richness and abundance

Establish action levels after 2 years of monitoring*

Establish actions after 2 years of monitoring*

Establish action levels after 2 years of monitoring*

Establish actions after 2 years of monitoring*

Amphibians: species richness and abundance

No increase from baseline over 2 consecutive years

Review management actions

Decline from baseline over 2 consecutive years

Investigate causes and review management actions

Reptiles: species richness and abundance

No increase from baseline over 2 consecutive years

Review management actions

Decline from baseline over 2 consecutive years

Investigate causes and review management actions

Birds: species richness and abundance

Provisional: These actions and levels to be agreed with AFCD

Aquaculture ponds:

<50% baseline richness and / or abundance in one year

OR

<80% baseline richness and / or abundance for 3 consecutive years

Construction phase

Investigate causes of decline eg reference to monitoring data from other locations within HK and overseas. Review construction practices

Operation phase

Investigate causes of decline eg reference to monitoring data from other locations within HK and overseas. Review management practices

 

<50% baseline richness and / or abundance for 3 consecutive years

Construction phase

Undertake detailed investigation of causes. Reduce disturbance effects caused by construction (eg noise) until causes identified

Operation phase

Undertake detailed investigation of causes. Implement short-term management actions aimed at increasing numbers

Constructed marsh habitat:

Establish action levels after 2 years of monitoring*

 

Establish action levels after 2 years of monitoring*

 

Establish action levels after 2 years of monitoring*

 

Establish action levels after 2 years of monitoring*

Hydrology

 

 

 

 

Water surface level

Aquaculture pond:

Level >100mm above or below target

Adjust as required

Aquaculture pond:

Level >200mm above or below target

Review levels, implement contingency plan

Constructed marsh habitat:

Level > 25mm above or below target

Constructed marsh habitat:

Level > 100mm above or below target

Water chemistry

 

 

 

 

pH

Outside range 5.5 – 7.5

Double water quality and vegetation survival rate monitoring, identify problem and implement plan to rectify

Outside range 4 – 8

Identify alternative water source until problem is rectified

BOD

>6.0mg/l

>9mg/l

DO

Within the ranges 51-70% or 121-130% saturation

<50% or >130% saturation

Ammonia concentration

>2mg/l

>5mg/l

Salinity

>1ppt

>3ppt

Total oxidised nitrogen

>3mg/l

>10mg/l

Total phosphorus concentration

>1mg/l

>3mg/l

Orthophosphate concentration

>0.1mg/l

1mg/l

Note: * - The action levels and actions will be established after 2 years for the communities of those species groups (ie aquatic invertebrates, freshwater fish and marsh bird species) which are currently not features of the existing FLW fauna. That is action levels and actions can only be established once the communities have become established and it becomes clear what their composition and relative abundance is.

 


14.7          References

1.             Anon. (2005). Summer 2005 Report: Egretry Counts in Hong Kongwith particular reference to the Mai Po Inner Deep Bay Ramsar Site. Report by Hong Kong Bird Watching Society to the Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

2.             Asia Ecological Consultants Ltd (AEC) (2003). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. Annual Report, November 2003.

3.             Asia Ecological Consultants Ltd (AEC) (2004). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. Annual Report, October 2004.

4.             Asia Ecological Consultants Ltd (AEC) (2006a). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. 2004 – 2005 Annual Report, March 2006.

5.             Asia Ecological Consultants Ltd (AEC) (2006b). Wetland Compensation Area Ecological Monitoring and Adaptive Management Advice. Supplementary Report for August – December 2005. March 2006.

6.             Aspinwall (1997). Study on the Ecological Value of fish Ponds in Deep Bay Area: Executive Summary. Planning Department, Hong Kong SAR Government.

7.             Aspinwall Clouston & Wetlands International – Asia Pacific (1997). Development of a comprehensive conservation strategy and a management plan in relation to the listing of Mai Po and Inner Deep Bay as a Wetland of International Importance under the Ramsar Convention.  Agreement No. CE47/95.

8.             Australian and New Zealand Environment and Conservation Council, State of the Environment Reporting Task Force (ANZECC) (2000). Core environmental indicators for reporting on the state of the environment, Environment Australia, Canberra.

9.             Benstead P., Drake M., José P., Mountford O., Newbold C., and Treweek J. (1997). The wet grassland guide: managing floodplain and coastal wet grasslands for wildlife. RSPB, Sandy.

10.          Benstead P., José P., Joyce C. and Wade M. (1999). European wet grassland: guidelines for management and restoration. RSPB, Sandy.

11.          Binnie, Black & Veatch (BBV) (2002). Sheung Shui To Lok Ma Chau Spur Line Environmental Impact Assessment Report. Kowloon Canton Railway Corporation, January 2002.

12.          Binnie Consultants Limited (1997). Reconnaissance survey of benthic and pelagic fishpond fauna at Fung Lok Wai. Unpublished report.

13.          Environment Protection Department (2002). River Water Quality in Hong Kong in 2000. Water Policy and Planning Group, Environmental Protection Department. Hong Kong Special Administrative Region Government. Feb 2002.

14.          Hawke C. J. and José P. V. (1996). Reedbed management for commercial and wildlife interests. RSPB, Sandy.

15.          Holling, C. S. (ed) (1978). Adaptive environmental assessment and management. John Wiley, Chichester.

16.          McMullon C. and Collins T. (2004). Habitat compensation and flood management: criteria and issues to be addressed in the design and delivery of compensation packages. Proceedings of the 39th Flood and Coastal Management Conference, July 2004. DEFRA, UK Government, London.

17.          Missouri Department of Natural Resources (1996). Water quality standards. Missouri Department of Natural Resources, Clean Water Commission, Jefferson City, MO.

18.          Primavera, J.H. (2000). Integrated Mangrove – Aquaculture Systems in Asia. Integrated Coastal Zone Management, Autumn edition, pp. 121-130.

19.          Townland Consultants Ltd, Wong Tung & Partners Ltd, Maunsell Consultants Asia Ltd, MVA Asia Ltd, CES Asia Ltd, Belt Collins & Associates HK ltd, Nelson and Wright (1992). Sunnyville Estate development at Nam Sang Wai, Engineering Assessment Report, Nam Sang Wai Development Co, Ltd & Kleener Investment Ltd.

20.          USEPA (1983). Water Planning Division. Results of the Nationwide Urban Runoff Program - Volume 1, Final Report. [Washington, DC], USEPA P1384-185552.

21.          Walters, C. J. (1986). Adaptive management of renewable resources. Macmillan, New York.

22.          Wilson, K.D.P. (1995). Hong Kong Dragonflies, Urban Council of Hong Kong,

 


 


15.             The Long-term Management OF the Wetland NAture Reserve

15.1          Introduction

15.1.1      The Fung Lok Wai site comprises approximately 80.1 hectares of which approximately 4.0 hectares (5%) will be affected by the residential development and associated access roads. The remaining approximately 76.1 hectares (excluding the access road) will form the Wetland Nature Reserve (WNR).

15.1.2      The project proponent shall be responsible for the creation, enhancementand management of the WNR during the construction phase and shall provide an undertaking to take sole responsibility for management until a successor can be found to the satisfaction of EPD or its agents. Section 3.5.6.4 (xv) of the EIA study brief for this proposal (EPD, 2000) requires the project proponent to propose a management package for the WNR with particular attention to:

·        The habitat management plan and specification of resources requirement for its implementation (this is addressed separately within the Fung Lok Wai Wetland Nature Reserve Habitat Creation and Management Plan [HCMP]);

·        The long-term trust management system with management guidelines;

·        The financial arrangements to sustain the management of the wetland;

·        The management agents and their responsibility; and,

·        A contingency plan for the management of the WNR before the establishment of foundation management.

 

15.2          Overview of Wetland Nature Reserve Management Arrangements

15.2.1      The design of the WNR, construction methods and programme and its long-term management plan are detailed in Section 14 of this report. The following is a brief summary of key design, construction and management arrangements proposed.

15.2.2      Approximately 61.7 ha of the existing fish ponds at Fung Lok Wai will be modified and enhanced to increase their value for Species of Conservation Importance, particularly birds recorded regularly on the site.

15.2.3      Out of these modified and enhanced fish ponds, five (10.3 ha) of the existing fish ponds will be consolidated into three and permanently set aside and planted, to varying degrees, with reeds (Phragmites australis) to provide attractive habitat for water birds, particularly duck and reedbed passerines. These ponds will be fed by rain water and their level allowed to fluctuate seasonally.

15.2.4      The remaining fishponds will be consolidated through bund removal to create 18 ponds with an average size of about 2.6 ha. These ponds will undergo a series of enhancement to improve their attractiveness to wildlife, particularly birds including: creation of shallows and muddy islands through re-distribution of bund material; and, cut back of vegetation.

15.2.5      A potential alternative egretry will be constructed in a part of the WNR that is as remote as possible to minimise disturbance. The design of this egretry draws on information gathered about the key features of egretries within the New Territories which indicates, for example, that it should be constructed with mature specimens of species such as Figs (Ficus spp.), Celtis sinensis and bamboo (Bambusa spp.).

15.2.6      Whilst the WNR is being constructed most of the fishponds will be managed according to an interim management regime which is intended to boost their immediate value to feeding birds. Construction of the WNR will be undertaken in stages to minimise disturbance to bird populations.

15.2.7      Following completion of the construction of the Residential Development the enlarged ponds will be managed according to traditional commercial aquaculture procedures involving stocking, rearing, harvesting and periodic set-aside for maintenance and recovery with several key differences:

·        The management of the 18 enlarged and enhanced ponds for active production will be coordinated. Most farmers typically operate a handful of ponds at the same time. The management of such a large block of ponds en masse will allow for a coordinated approach to fish production, maintenance and monitoring activities. It will also facilitate a more effective approach to their adaptive management.

·        Ponds in production will be drained down annually for a fixed period of 20 days. Ponds are typically drawn down for shorter periods under normal management regimes.

·        Approximately 25% of ponds will be “set-aside” for production according to a 5 yearly schedule. This will provide opportunity for maintenance works and allow for control of diseases or presence of undesirable species. Set-aside is a more ad hoc process under normal management procedures.

·        Whilst most fish selected for farming will be those typical of commercial aquaculture operations, the composition and proportions of these species will be varied to benefit feeding wildlife.

15.2.8      An area of approximately 14.4 ha adjacent to the development area will be converted into a complex of freshwater marsh habitats. This area will comprise:

·        Permanent marsh composed of a series of shallow inter-locking lakes with occasional deep areas and islands. Fringe vegetation in the form of reeds and other emergent plants will create cover for birds and other fauna.

·        Seasonal marsh composed of vegetation that is inundated only during the wet season. Annual grazing by water buffalo will maintain vegetation height and provide small scale habitat disturbance.

·        Storage pond. The water deficit usually experienced every dry season is a constraint on the design and management of marsh habitats. To ensure a supply of freshwater of suitable quality for the permanent marsh throughout the year an existing fishpond will be enlarged to provide storage. The optimum size of this storage has been established through modelling of typical and extreme rainfall patterns.

15.2.9      Water levels within the marsh complex will be managed according to broad habitat requirements – ie permanent or seasonal inundation. Within the permanently inundated marsh areas, levels will still be allowed to fluctuate (within bounds) to facilitate the periodic exposure of muddy areas.

15.2.10   Native plant species mixes have been selected on the basis of the specific hydrological conditions envisaged for each area of the marsh complex. It is anticipated that, on completion of construction and planting works, it will take 12 months to establish the marsh habitats.

15.2.11   The WNR shall not be used for any other purposes except for those specified in the HCMP.

 

15.3          Management of the Wetland Nature Reserve

15.3.1      The WNR area will be managed by the project proponent and suitably qualified consultants will be appointed to oversee construction works.

15.3.2      Upon the completion of the construction of the WNR, the Development Site will be sub-divided into two portions:  the WNR portion and the residential portion.  The operation and management of the WNR will be independent from the management of the residential development.  The WNR will be managed by the proponent until a designated successor such as an independent Foundation is identified to the satisfaction of EPD or its agents..  The residential development, which will be under strata-titled ownership will be independently managed by the property manager appointed by the owners of the residential development.  The residents in the residential development will neither have privilege over the general public for access to the WNR nor the liability of its maintenance.

15.3.3      An appropriately trained ecologist or a reputable organisation with a significant level of experience in the management of wetland habitats will be employed as the Reserve Manager for the day-to-day management of the WNR. Experienced fish farmers will be employed for the operation of the fish ponds under the supervision and guidance of the Reserve Manager. The Reserve Manager will oversee and advise on construction and enhancement works to ensure that they meet conservation objectives. The Reserve Manager will also coordinate monitoring and implement actions as detailed in the HCMP during this time.

15.3.4      The Reserve Manager will coordinate fish pond management in line with the interim and enhanced management protocols established in the HCMP.

15.3.5      Once the WNR is fully operational the HCMP will be replaced by an Operational Management Plan (OMP, see Section 14.4.49) and it will be the responsibility of the Reserve Manager to implement the management and monitoring protocols detailed in that document.

15.3.6      The project proponent shall provide an undertaking to take sole responsibility for the management of the WNR until a designated successor is identified to the satisfaction of EPD or its agents. Subject to the necessary agreements from relevant Government authorties outside the EIA Ordinance which shall be obtained by the proponent separately, an independent, non-profit Foundation will be established to take over the long-term management of the WNR and the Environmetnal Permit will be transferred to the Foundation. Similar in form to a Conservation Trust, the Foundation will provide guidance and resoures on strategic and day-to-day management of the reserve. Until such time the Foundation takes over responsibility for the long term management and maintenance of the WNR. A proposal of the structure, operation and financing of the Foundation is set out at the Annex of this report. It is recognized that approval of the EIA report would not represent Government’s endorsement or agreement of the Foundation proposal. Upon receipt of the necessary agreement from government, the WNR will be assigned to the Foundation. 

 

15.4          Conclusions

15.4.1      The project proponent will be responsible for the proper management and operation of the WNR until a designated successor such as an independent Foundation is identified to the satisfaction of EPD or its agents. In the long run, an independent Foundation will provide a sound mechanism for overseeing the management of the WNR. The Foundation will:

·        Provide an effective management framework for the implementation of the WNR Habitat Creation and Management Plan including update in light of new understanding of the ecology of the wetland habitats of the reserve (adaptive management);

·        Provide resources in the form of personnel and financial support to ensure that conservation targets are met; and,

·        Coordinate a rigorous monitoring programme to ensure that Conservation Targets are being met and to improve understanding of the wetland ecology of the reserve.

15.4.2      The Foundation represents a practical step toward, and a model for, sustainable development in Hong Kong.

 


16.             Environmental monitoring and audit (EM&A) requirements

16.1          Introduction

16.1.1      An Environmental Monitoring and Audit (EM&A) Manual has been prepared under a separate cover as part of the EIA study.  The recommended EM&A programme is only discussed in brief here.  For further details on the EM&A, the Manual should be referred to.

16.1.2      In accordance with the requirements in Section 3.5.12 of the EIA Study Brief, an Implementation Schedule of the environmental mitigation measures recommended in the EIA study has been prepared in form of a checklist.  The Implementation Schedule is given in the EM&A Manual under a separate cover.

 

16.2          Objectives of Environmental Monitoring and Audit

16.2.1      The objectives of the implementation of EM&A for the Project are to:

·        Provide an early indication should any of the environmental control measures or practices fail to achieve acceptable standards;

·        Determine project compliance with regulatory requirements and standards;

·        Verify the environmental impacts predicted in the EIA Study;

·        Monitor the performance of the Project and the effectiveness of mitigation measures;

·        Take remedial action if unexpected problems or unacceptable impacts arise; and

·        Provide data to enable an environmental audit.

 

16.3          Summary of Areas Requiring EM&A

16.3.1      The EIA study has recommended a number of environmental control and mitigation measures. The recommended EM&A programme will allow the implementation and environmental performance of the environmental control/ mitigation measures to be checked. 

16.3.2      Monitoring can be defined, in brief, as the systematic collection of data through a series of repetitive measurements.  It will involve the measurement of specified environmental parameters before the commencement of the Project, and subsequent impact monitoring during the operational phase of the Project.  Environmental audit involves verification of practice and certification of data.  As detailed in the EM&A Manual, the EM&A works shall be undertaken by a project Environmental Team (ET) and audited by an Independent Checker (Environment) (IC(E)).

16.3.3      The following areas, identified in the EIA for this Project, will require EM&A during the construction or operational phase:

·        Air Quality: construction dust

·        Noise Impact: construction noise

·        Water Quality

·        Waste Management

·        Ecology

·        Landscape and Visual

·        Cultural Heritage

 

16.4          Air Quality

Construction Dust Monitoring

16.4.1      Potential dust impacts could be caused by the construction activities during the construction phase of this Project. Dust mitigation measures with reference to the Air Pollution Control (Construction Dust) Regulation have been highlighted in Section 4 of this report.

16.4.2      Furthermore, a construction dust monitoring programme is recommended to carry out to ensure that dust emissions generated from the Project are effectively mitigated to minimise the associated impacts at nearby sensitive receivers.

16.4.3      Baseline monitoring should be completed before the construction work commences. Impact monitoring should be conducted whenever there is an ongoing construction work in the vicinity of the proposed dust monitoring location. Event/ Action Plan should be triggered by exceedance of action/ limit levels.  Regular site audits shall also be carried out by the ET and independent audits carried out by the IC(E) to check for the implementation of the recommended air quality mitigation measures.

16.4.4      Details of the monitoring and audit requirements for construction dust are presented in the EM&A Manual.

 

16.5          Noise Monitoring

Construction Noise Monitoring

16.5.1      Potential noise impacts could be caused by the construction activities during the construction phase of this Project. As noise mitigation measures have been proposed and formulated in the EIA Study, EM&A is recommended to ensure that the mitigation measures are timely implemented and that the noise sensitive receivers are protected effectively by the proposed measures.

16.5.2      Baseline monitoring should be completed before the construction work commences. Impact monitoring should be conducted whenever there is an ongoing construction work in the vicinity of the proposed noise monitoring location.

16.5.3      Details of the monitoring and audit requirements for construction noise are presented in the EM&A Manual.

 

16.6          Water Quality

16.6.1      Water quality monitoring at the relevant sensitive receivers near the Project during the construction phase is recommended to ensure that the water quality is within acceptable levels and is not significantly affected by the construction activities e.g. ponds dredging and filling.

16.6.2      It is proposed to set up upstream control stations and downstream impact monitoring stations to monitor the water quality impact during the construction period. Release of sediment particles and pollutants would be carried by the tidal flows downstream from the Subject Site, the upstream monitoring station would not be affected by the construction activities. However, the stations at the downstream location are likely to be directly affected by the release of sediment particles and pollutants from the site. This approach can minimise the influence from any seasonal and local variations of water quality conditions in the region where monitoring is carried out.

16.6.3      Upstream control and downstream impact monitoring station are proposed to be set up at the upstream and down stream of tidal river respectively.

16.6.4      Monitoring of effluents discharging from the construction site is recommended during the construction phase of the Project. The Contractor is responsible for application of a discharge licence from EPD. The discharged effluents should be treated and the effluent quality should comply with the licence conditions.

16.6.5      Details of the monitoring and audit requirements for water quality are presented in the EM&A Manual.

 

16.7          Waste Management

Construction Waste Auditing

16.7.1      Auditing of each waste stream is recommended to be carried out periodically to determine if wastes are being managed in accordance with approved procedures and the Waste Management Plan (WMP). The audits should cover all aspects of waste management including waste generation, storage, recycling, treatment, transport, and disposal.

16.7.2      The general site inspections including waste management issues is recommended to be undertaken weekly by Environmental Team to check all construction activities for compliance with all appropriate environmental protection and pollution control measures, including those set up in the WMP. Meanwhile, waste management audit will be carried out monthly basis by the Independent Environmental Checker (IEC).

 

16.8          Ecology

16.8.1      Ecological monitoring is recommended during construction and operational phase of the Project. The mitigation measures should be included into contract clauses for construcion and operation of the Projcet. The implementation of the measures should be audited as part of the EM&A procedures during the construction and operational period. Details of the monitoring programme, including the key limit and action levels and their associated management actions are presented in Section 14-5 and the EM&A Manual.

 

16.9          Landscape and Visual

16.9.1      EM&A for landscape and visual resources is proposed to be undertaken during both the construction and operational phases of the Project.

16.9.2      The implementation and maintenance of the landscape compensatory planting measures is a key aspect of this and should be checked to ensure that the proposals are fully realised and that potential conflicts between the proposed landscape measures and any other project works and operational requirements are resolved at the earliest possible date and without compromise to the intention of the mitigation measures. In addition, implementation of the mitigation measures recommended by the EIA will be monitored through the construction phase site audit programme.

16.9.3      Details of the monitoring and audit requirements during the construction and operational phases are presented in the EM&A Manual.

 

16.10      Cultural Heritage

16.10.1   In order to retrieve information concerning the composition of the bunds it is recommended that a brief recording exercise with methodology agreed with the Antiquities and Monuments Office be carried out during site formation.

 

16.11      Implementation Schedule of Environmental Mitigation Measures

16.11.1   An Implementation Schedule has been prepared for the environmental mitigation measures recommended in the EIA study in the form of a checklist.  The Implementation Schedule is as shown in Appendix 16-1.

 


17.       Summary of environmental outcomes and overall conclusion

17.1          Introduction

17.1.1      An Environmental Impact Assessment (EIA) has been conducted to address all key environmental issues associated with the Project. The assessments were carried out based on the requirements of the EIA Study Brief (Brief No.: ESB-055/2000) issued by the Director of Environmental Protection (DEP).

17.1.2      This section summarises and concludes the key environmental outcomes associated with the Project in accordance with the requirement as specified in Section 3.5.11 of the EIA Study Brief.

17.1.3      In respect of air quality impact, noise impacts, water quality impacts, sewerage and sewage treatment implications, waste management implications, fisheries impact and cultural heritage impact the impacts are considered similar and acceptable for Preferred Options 1A and 1B However, in respect of ecological impacts Option 1A is slightly superior to option 1B whereas in respect of landscape and visual impacts Option 1B is considered slightly superior to Option 1A.  In general terms though these differences are slight and the environmental impacts of both Options 1A and 1B are found to be acceptable. 

 

17.2          Key Environmental Issues

17.2.1      The key environmental issues studied in the EIA include air quality, noise, water quality, potential problem of biogas, sewerage and sewage treatment implications, waste, cultural heritage, landscape/ visual, fisheries and ecological impact.  Quantitative assessments, and where appropriate semi-quantitative or qualitative assessments have been carried out to assess the extent of potential impact.  Mitigation measures have been recommended, where necessary, to alleviate all identified environmental impacts associated with the Project to acceptable levels. The conclusions for each of the assessed environmental aspects are summarised below.

 

17.3          Air Quality Impact

Construction Phase

17.3.1      The main concern for air pollution during the construction phase of Development is fugitive dust (TSP) emissions associated with unloading of fill materials from dump trucks for pond filling, vehicle movements on unpaved haul roads, wind erosion on exposed ground and stockpiling areas, and handling of excavated material and construction debris.

17.3.2      As the topsoil beneath the ponds are of high moisture content and dredging works will be carried out at a few fish ponds each time, dust emission is not considered a problem during pond dredging at residential portion, and re-profiling of pond bunds, partial filling of ponds during the establishment of WNR if mitigation measures are properly implemented.

17.3.3      As the access road of the Development will rely on existing Fuk Shun Street, the limited site clearance works and junction improvement works to widen the road will be constructed section by section. The volumes of excavated spoil are expected to be low.  The number of vehicle trips during construction is expected to be very small and vehicle movements will be on existing paved roadways. The construction works for access road is anticipated to cause insignificant dust emission impacts when the construction mitigation measures are implemented and through the Environmental Monitoring & Audit programme.

17.3.4      As the sewers will be constructed section by section and together with with the access road if the alignment of the sewers follows the access road, the volumes of excavated spoil are expected to be low. For the two sewerage options of the Project, the number of vehicle trips during construction are both expected to be very small and for most areas, vehicle movements will be on paved roadways.  Only minimal movement of vehicles on unpaved roads will be required.

17.3.5      Critical periods of fugitive dust emissions will be during land formation for the marshland (Stage A) (i.e. between 4th quarter of 2011 and 1st quarter of 2012) and site formation for the residential portion of the Project when fill material have to be imported and handled for ponds filling, spreading and compaction (Stage B) (i.e. between 2nd quarter of 2012 and 4th quarter of 2012). For the prediction of the worst-case dust impact, all the major activities in each of the 2 aforesaid scenarios have been modelled in the EIA study and were assumed to be in concurrent operation.

17.3.6      Those existing village huts scattered around the Project, mostly at the southern side of the Site, are identified as Air Sensitive Receivers (ASRs).

17.3.7      With the implementation of a series of practicable dust control measures such as frequent watering, enclosure of dust emission sources and establishment and use of vehicle wheel and body washing station at exit points, etc., a minimum dust control efficiency of 75% is achievable. The mitigated results revealed that the dust levels would be within the hourly and daily TSP limits of 500mg/m3 and 260mg/m3 respectively. Assuming that the dust generating activities are taking place concurrently, the predicted highest hourly and daily average dust concentration will be 256mg/m3 and 152mg/m3 at the identified ASRs respectively.

17.3.8      It is also an obligation of the Contractor(s) to comply with the Air Pollution Control (Construction Dust) Regulation during the construction phase to mitigate dust emissions by use of practicable measures as suggested in the EIA report.

17.3.9      Implementation of these measures can be enforced by incorporating as contractual clauses. An Environmental Monitoring and Audit (EM&A) program is also recommended to further check the implementation the dust mitigation measures and compliance with the dust criteria.

17.3.10   As dredging works will be carried out at only a few fish ponds each time and any exposed surface and stockpiled material will be covered by impervious sheet or immediately filled by filling materials during the construction phase, the potential odour nuisance pose by the exposed pond sediment during dredging and pond filling is considered to be minimal.

Operational Phase

17.3.11   There are no air and odour emission sources within the Development, except potential odour nuisance from a proposed pump house. However, with implementation of proper enclosure and ventilation system to divert the odour emission to odour scrubbing device (e.g. enclosed concrete structure and activated carbon filter at the air vent of the pump house), no insurmountable odour impact is anticipated. Further discussions are presented in Section 8.8.6.

17.3.12   A minimum setback distance of 125m is provided between the closest existing local distributor Fuk Shun Street and the proposed development.  Referring to the Hong Kong Planning Standard and Guidelines (HKPSG), a buffer distance of not less than 5m shall be provided between a local distributor and an open space site for active and passive recreational uses.  In this regard, sufficient buffer distance will be provided and the buffer requirements as recommended in the HKPSG could be met. The operational air quality impact arising from the vehicular emission is considered insignificant.

17.3.13   Given the remoteness of the chimneys located in the YLIE and the YLSTW from the Development (about 400m and 500m away from the Subject Site respectively), the operational air quality impact arising from the chimney emissions from the YLIE and the odour from the YLSTW are also considered to be insignificant.”

 

17.4          Noise Impacts

Construction Phase

17.4.1      Construction works of the Project could be a cause for construction noise impact on nearby noise sensitive receivers.  Hence the potential cumulative noise impacts of the construction of the access road, the residential portion and the WNR have been assessed in accordance with general acoustic principles and guidelines given in Para. 5.3 and 5.4, Annex 13 of the EIAO TM.

17.4.2      Construction noise is controlled under the Noise Control Ordinance (NCO), which prohibits the use of powered mechanical equipment (PME) during the restricted hours (7 p.m. to 7 a.m. on normal weekdays and any time on a public holiday, including Sunday) without a valid Construction Noise Permit (CNP) granted by the Authority.

17.4.3      Percussive piling is controlled similarly by a noise permit system and described in the NCO and the “Technical Memorandum On Noise From Percussive Piling” (TM3) which restrict the number of hours during which piling can be conducted.  No percussive piling may be carried out in the territory without a valid CNP issued by the Authority.  Besides, a CNP will only be granted for percussive piling, which is scheduled during normal working hours between 7 a.m. to 7 p.m. from Monday to Saturday.

17.4.4      The future Contractor undertaking the construction work will be subject to this statutory requirement and hence the impact was not predicted in this restricted period. Rather, the impact during the non-restricted periods (i.e. between 07:00 to 19:00 on Monday to Saturday) has been the focus of the assessment.

17.4.5      Based on a tentative construction programme and a reasonably developed set of equipment inventory, cumulative construction noise impacts have been conservatively predicted.

17.4.6      Results indicated that the unmitigated cumulative noise impact could exceed the relevant noise limit of Leq(30min.) 75 dB(A) by 3 - 15 dB(A) at sensitive receivers situated in close proximity to the site. In view of this, a series of progressive mitigation measures have been recommended to alleviate the impact. These include: -

·        Use of quiet/silenced equipment and working method;

·        Use of temporary noise barriers and machinery enclosures;

·        Good site practice and noise management, etc.

17.4.7      A further prediction based on the assumption of use of these mitigation measures has revealed that the noise impact could be mitigated to acceptable levels at all sensitive receivers. Required noise mitigation measures can be incorporated as contractual obligations for the contractor in carrying the works. An EM&A programme has also been recommended for checking the implementation of the recommended noise control measures and compliance with the statutory noise criteria.

Operational Phase

17.4.8      Sewage pump house at the residential portion of the Project is the only major noise source identified to be of concern to the future noise sensitive receivers. Based on conservative assumptions of the possible noise power levels for the sewage pump house, the noise impact was evaluated and has been found to be acceptable if a minimum setback of 15m (or less for smaller pumps) is observed. The pumps should be housed inside a concrete structure with openings facing away from any NSRs.

17.4.9      Subject to the selected sewerage option and the final design of the MLP and the pump house, the sewerage pump house is tentatively proposed to be housed inside a concrete structure near the car-park area for the visitors with openings at the southern side facing away from any NSRs. As such, the pump house will have a setback distance of more than 150m from the residential block and nearby NSRs.

 

17.5          Water Quality

17.5.1      The assessment has been conducted in accordance with the requirements given in Clause 3.5.2 of the EIA Study Brief.  The criteria and guidelines as presented in Annexes 6 and 14 of the EIAO TM have been adhered to in the study.

Construction Phase

17.5.2      The establishment of the WNR will involve creation of marshland and re-profiling and landscaping of the ponds.

17.5.3      The construction of the residential portion of the Project requires ponds draining, dredging and filling at 6 fish ponds at the southern boundary of the site.

17.5.4      The key concern in water pollution during the construction phase of the project relates to the possible discharge of surface runoff contaminated by suspended solids released as a result of the site formation and pond filling works. Control in water pollution shall be achieved though implementation of the Best Management Practices (BMPs) to avoid contact of pollutants with rainfall or runoff and measures to abate pollutants in the stormwater runoff.  The guidelines for handling and disposal of construction site discharges as detailed in EPD’s ProPECC Note PN1/94 “Construction Site Drainage” should be followed.  Mitigation clauses targeted to minimise water pollution arising from construction site runoff, construction site wastewater, oils and solvents etc. are recommended for implementation through inclusion as contract clauses. 

17.5.5      Through transferring the pond water within the subject site, the need of discharging pond water into the surrounding water bodies during the construction of the Project can be avoided.

Operational Phase

17.5.6      Water for use in the WNR will be provided by direct rainfall supplemented by run-off from the residential development and catchments A and B via a ditch running along the southern border of the development area. Water will drain into the storage pond at the eastern end of the proposed WNR.

17.5.7      The run-off from residential site will pass through traps to remove oil and grease, and sand and gravel filters to reduce silt loads and particulate organic matter prior to discharge into the ditch and the storage pond. As runoff water from the catchments and development area will be stored for long periods before entering the wetland area any remaining silt that is present will be able to settle out in the water. This will further significantly reduce pollutant levels (from the residential runoff and catchments A and B). Regular maintenance, e.g. periodic de-silting will be required. It is believed that the quality of the water discharge will be better than that of the baseline situation as well as the upstream water quality.

17.5.8      Foul water, on the other hand, will be discharged to the public sewer.

17.5.9      The water levels of the fishponds inside the wetland nature reserve will be managed and controlled by the conservation manager. During normal operation, the wetland nature reserve will be self-contained and pond water will not be discharged to the surrounding. Water will only be discharged when there is overflow.

17.5.10   The fishponds comprising the WNR will be interconnected with adjustable sluices to allow the circulation of water to reduce the likelihood of overflow upon heavy storm. In wet season, though unlikely, excess water will be drained and discharged to the Tai River under the management of conservation manager.

 

17.6          Potential Problem of Biogas

17.6.1      As the residential footprint is planned to build on the existing fishpond area, under anaerobic conditions, the pond mud left in-situ can generate potential biogas risk.

17.6.2      With the TOC and SOD contents of the pond mud in-situ sampled, the potential methane flux from the Development based on half-lives of 5 is estimated. Even under the extreme worse case scenario (100% of TOC is biodegradable), the results are well below with the guide value stipulated in EPD’s Landfill Gas Hazard Guidance Note and the maximum “safe” rate of gas emission derived from the Department of the Environment (1993), Landfill Completion. Waste Management Paper No. 26A.

17.6.3      Generic gas precautionary measures for the below ground structures of Development and precaution measures to be taken prior to entry into any below ground services or confined space within the Development are recommended.

17.6.4      With the incorporation and implementation of the recommended precautionary measures, the potential biogas hazard posed to the Development is considered to be minimal.

 

17.7          Sewerage and Sewerage Treatment Implications

17.7.1      With reference to the recommendation and projection in the Review of Yuen Long and Kam Tin Sewerage and Sewage Treatment Requirements and taking into consideration the existing and committed sewerage facilities in the vicinity of the proposed Development, the 2 sewage disposal strategies for the Project have been investigated:

Strategy A (Eastern Option) – provide a new sewer to discharge sewage to YLSTW via local roads e.g. Fuk Shun Street.

Strategy B (Western Option) – provide a new sewer to discharge sewage to the proposed Tin Shui Wai Pumping Station at Area 101 via Tin Wah Road. The sewage at TSW Pumping Station passes through Ha Tsuen Pumping Station and eventually transfers the flow to San Wai STW.

17.7.2      The 2 proposed strategies are all considered technically feasible although they will be subject to negotiation and agreement with the relevant Government department.

17.7.3      Two alternative alignments are proposed for Strategy A. For Strategy A1, new sewers connecting between the new pump house on-site and YLSTW are proposed to be built. No upgrading works of sewers are required for this sewerage option. A new sewer will be laid beneath existing local road, Fuk Shun Street and the local next to Leon Court. Strategy A2 is to build a new sewer connecting to existing sewer (through manhole HK19369006) under Fuk Shun Street. As supported by the SIA presented in Appendix 8-1, no upgrading works on existing sewers are considered necessary.

17.7.4      For Strategy A, YLSTW will have adequate spare capacity to cope with the estimated additional resentitial sewage from the FLW Project.  Feasibility for Strategy A1 and Strategy A2 has been studied in the SIA as presented in Appendix 8-1.

17.7.5      Strategy B involves laying an approximate 940m new sewer beneath planned/existing carriageway at the western side of the subject site. Wayleave from the Government is required. The Sewerage Impact Assessment conducted has found that upgrading of the existing sewage pipes with length of 948.8m at Tin Wah Road is considered necessary to convey the flow from the FLW Development to TSW pumping station.

17.7.6      In broad terms, these strategies involve installing an on-site sewage pump house within the Development and providing a new sewer to discharge sewage to the nearby sewage treatment work or pumping stations.

17.7.7      Subject to the selected sewerage option and the final design of the MLP and the pump house, the sewerage pump house is tentatively proposed to be housed inside a concrete structure near the car-park area for the visitors with openings at the southern side facing away from any Noise Sensitive Receivers. It will be equipped with 2 duty and 1 standby sewage pump to raise the sewage head by about 9m. Given its proven reliability and ease of inspection and maintenance, electrically operated vertical spindle non-clog dry well sewage pump will be used and the total designed capacity of the pump house is 182 l/s. The feasible discharge point of overflow bypass is either through Tai River to the West or Shan Pui River to the East.

17.7.8      The selection of sewerage options remains open at this stage. Strategy A is preferred option, however, it will be subject to the spare capacity of YLSTW and the completion program for the Yuen Long Effluent Pipeline.

 

17.8          Waste Management

17.8.1      The waste streams that will be generated during the construction and operational phase of the proposed Project at Fung Lok Wai are identified and evaluated in terms of their nature, type, quality, quantity, and associated environmental impacts. Opportunities for reduction in waste generation through recovery, reuse or recycling are identified.

17.8.2      The waste management implications and potential environmental impacts associated with the handling, transport, and disposal of the identified waste types are evaluated and addressed.  An EM&A programme is recommended to be in place during the construction phase to check the waste generated from the construction site are being managed in the accordance with the recommended procedures.

17.8.3      With the recommendations implemented, no waste related regulatory non-compliance and unacceptable environmental impacts are expected to arise from the handling, storage, transport and disposal of construction waste arising from the proposed residential and wetland nature reserve development.

17.8.4      The nature of the historical uses of the site and the findings of the sediment sampling results confirm that land contamination should not be a concern.

 

17.9          Ecological Impact Assessment

17.9.1      This assessment was conducted in accordance with the requirements given in section 3.5.6 of the EIA study brief. All ecological impacts have been assessed according to criteria outlined in annexes 8 and 16 of the EIAO Technical Memorandum.

Evaluation of impacts

Habitat loss

17.9.2      The proposed development at Fung Lok Wai will result in no permanent habitat loss to ecologically valuable habitats in the WCA. The actual operation phase footprint (i.e. land directly and permanently lost by the project) will be approximately 4.0 hectares (primarily aquaculture ponds and a very small area of drainage ditch. This change in habitat use will occur as a result of the land used for the construction of residential blocks, associated structures and access roads and storage areas for materials and equipment etc. However the loss of water body is compensated by re-profiling the ponds in the Wetland Nature Reserve (WNR) area. This creates ecologically enhanced and enlarged ponds, and recreated marshland habitat. Consequently there is no net loss of water body area or ecological function. No additional habitat loss is anticipated as a result of the construction of either sewerage strategy or the preferred (southern) access route.

17.9.3      An integral component of the proposal is the development of a WNR on the remaining 76.1 hectares of the site. The creation of the WNR will involve the transformation of approximately 14.4 hectares of aquaculture ponds to freshwater marsh and the enhancement (through enlargement) of 61.7 hectares of aquaculture ponds. Whilst intended to compensate for impacts arising from the construction of the residential component of the development and, therefore, expected to have overall positive benefit, the WNR works will involve permanent and temporary habitat loss of aquaculture ponds (fishponds that are actively managed, those that are currently unmanaged, and the intervening bunds) and ditches and drainage channels.

17.9.4      The major potential species impacts associated with the proposed development relate to:

·        Disturbance caused by the construction and operation of the proposed development, including the WNR; and,

·        Fragmentation – in particular the obstruction of flightlines of birds moving to and from the Shing Uk Tsuen egretry (now abandoned).

Disturbance

17.9.5      Species most likely to be affected by disturbance impacts are birds, particularly flock feeding waterbirds, larger herons and birds of prey, and mammals, particularly larger species. Such species are likely to be disturbed by loud noises, moving objects and the presence of people. Stationery objects such as buildings, are also sources of disturbance as these may obscure flight lines and views of potentially approaching predators. As no large mammal Species of Conservation Importance were recorded during the field surveys, particular attention is therefore focused on assessing the impacts of disturbance on bird Species of Conservation Importance recorded at the site.

17.9.6      An assessment of the predicted impacts of disturbance on each Species of Conservation Importance that regular occurs in significant numbers has been carried out.  The assessment is based on a combination of literature review, analysis of field survey data and experience of the study team and previously accepted assessment criteria. Disturbance impacts have been calculated by defining distance from the edge of the disturbance source to the furthest point of:

·        An avoidance zone –Where a particular species is precluded from using the area; and

·        A zone of reduced density – Where the numbers of a species are lower than they would be in the absence of disturbance either because it occurs in lower numbers (more tolerant individuals) and/or for a shorter period of time (for example during periods of reduced human activity). In this analysis, it is assumed that the overall utilisation of the zone of reduced density is 50% of that in undisturbed areas (0% utilisation at the border with the avoidance zone rising to 100% utilisation at the border with the undisturbed areas).

17.9.7      These distances have been estimated for construction and operation phase impacts and for disturbance impacts, particularly within the fishpond area and proposed freshwater marsh, which are considered to be of greatest value to the identified Species of Conservation Importance. The predicted disturbance impacts have been calculated on the assumption that there will be low-level visual human disturbance and that basic mitigation measures, including the creation of wetland habitats with reedbeds and the planting of trees and bamboo, as screening will be implemented.

Fragmentation – flight line obstruction

17.9.8      Comparison of alternative development options indicated that it was possible to reduce the potential impact of the residential development on flightlines associated with the egrety existed at the time of survey (now abandoned) by shifting the Development Area eastwards. In anticipation of potential impacts of the development on flightline activity and to mitigate for these impacts the Proposed Development Area was moved eastwards by about 150m to increase distance from the egretry location, leading to a reduction in flightline intersection. In addition to this, further mitigation is proposed in the form of the creation of a potential alternative egretry site.

17.9.9      Although the ecological effects of Options 1A and 1B are considered to be similar in most respects, it is predicted that Option 1B will result in slightly greater habitat fragmentation than Option 1A. The larger number of buildings in Option 1B is expected to restrict the sightlines of birds to a slightly higher degree than would be the case in Option 1A. The difference is, however, slight, particular in light of the abandonment of the egretry which will result in reduced levels of flight activity.

Habitat Compensation

17.9.10   The aim of habitat compensation will be to replace habitats of intrinsic ecological value that will be lost or degraded. Compensation may be carried out through replacement of important habitats to be lost or the enhancement of existing habitats (i.e. by raising the ecological value of the habitat and thereby its carrying capacity for target species).

Compensation for Direct Habitat Loss

17.9.11   No net loss of water body will be ensured through the removal of terrestrial bund habitats of low ecological value and replacement with further wetland area and shallow incorporated into to the design of the WNR. It is predicted that pond enlargement and marsh habitat creation will result in the removal of approximately 4.4 ha of pond bund which will more than compensate for the area of fishpond lost under the development footprint.

Compensation for Functional Habitat Loss

17.9.12   Calculations of the overall land requirements to compensate for disturbance effects for species considered to be most sensitive to disturbance impacts have been derived within the EcIA. If the requirement to compensate for the disturbance to these species is met, full compensation for the impacts of direct habitat loss and disturbance to less-sensitive species Species of Conservation Importance is likely to be achieved, as long as appropriate habitat is provided. Mitigation for other impacts on both birds and other Species of Conservation Importance are addressed later in this section.

17.9.13   The level of functional improvement of remaining wetland habitat is calculated by quantifying the area of the proposed development, plus the wetland area lost within the disturbance exclusion zone for each species, plus the wetland area lost through reduced density disturbance.  This total is divided by the area of undisturbed wetland habitat remaining, to obtain the functional improvement factor.

Objectives of the Wetland Nature Reserve

17.9.14   The WNR will be established on the remaining 95% (approximately 76.1 ha.) of the site unaffected by the residential development.

17.9.15   The goal of the WNR is to provide compensation for loss of habitat and disturbance associated with the construction and operation of the residential development. The result will be no net loss of either function of wetland habitat or area of water body.

17.9.16   No net loss of water body area will be achieved through reconfiguration of fish ponds to create fewer, larger ponds and the creation of a complex of freshwater marsh habitats. Increasing fish pond size has an additional benefit as there is evidence that many wetland birds prefer larger, less enclosed waterbodies to the small ponds which typify most aquaculture practices. The removal of some bunds is predicted to have low or negligible impact as their intrinsic ecological value is low. The complex of freshwater marsh habitats proposed will provide a range of additional habitats for birds and other flora and fauna, including dragonflies.

17.9.17   Functional enhancement will be achieved through enhancement of both the ponds and the approach to aquaculture management. The carrying capacity of fishponds is limited by the uniform design of ponds and management that is not specifically targeted at conservation. Modifications to both will significantly improve foraging opportunities for birds and other fauna. To ensure ongoing functional replacement, key ecological indicators, including birds, will be monitored to guide management of the reserve.

17.9.18   Detailed design principles of the WNR are provided within the EcIA and WNR construction works will be staged to minimise the disturbance of the site.

17.9.19   Responsibility for the management of the WNR rests with the project proponent who will be responsible for the proper management and operation of the WNR until a designated successor such as an independent Foundation is identified to the satisfaction of EPD or its agents.. Subject to the necessary agreements from relevant government authorities, an independent, non-profit Foundation will be established to take over the long-term management of the WNR. Similar in form to a Conservation Trust, the Foundation will provide guidance and resources on strategic and day-to-day management of the reserve.

 

17.10      Fisheries Impact Assessment

17.10.1   This assessment is prepared in accordance with the requirements of the EIAO and the criteria and guidelines defined in Annex 9 and 17 of the EIAO TM.

17.10.2   The Project involves the construction of the Wetland Nature Reserve comprising enhanced and enlarged fishponds, rain fed ponds for water birds and a complex of freshwater marshlands and the construction of residential development. The design principles of no net loss of area and functional enhancement of wetland habitats are to be achieved through the reconfiguration of pond bunds to create larger and functionally enhanced ponds which are more preferred by birds and to create land for residential development. Through the pond bunds reconfiguration, there will be a slight increase in the area of water body within the Site. As the WNR is designated for more diversified ecology and only a portion of the WNR is proposed as fishpond habitat, there will be a loss of fishponds for fish production (permanent loss of 20.8 ha of active commercial fishponds and approximately 5.4 ha of inactive ponds). Those ponds that remain, however, will be enhanced to increase their ecological values, primarily for bird Species of Conservation Importance. They will, however, continue to be managed in largely traditional manner within which fish production will still be a key objective. The establishment of the Wetland Nature Reserve will ensure that this enhanced management regime is implemented in the long term. In this respect the fish production and fishponds will be more sustainable than comparable ponds elsewhere within Deep Bay.

17.10.3   The long-term management of these ponds ensures the preservation of the cultural practice of aquaculture in-situ, which is consistent with concepts of “wise use” fore-shadowed in Article 3.1 of the Ramsar Convention. It also provides opportunities for ongoing research into sustainable fish production and wildlife conservation.

17.10.4   Off-site impacts are not anticipated as the likelihood of adverse impacts on water quality of neighbouring ponds, estuarine and marine receiving environments is considered to be very low during either construction or operation phases.

 

17.11      Cultural Heritage Impact Assessment

17.11.1   The cultural heritage impact of the Project are evaluated and assessed in accordance with the requirements stated in Clause 3.5.8 of the Study Brief and the criteria and guidelines stated in Section 2 of both Annexes 10 and 19 of the TM.

17.11.2   The findings and recommendations of the Cultural Heritage Impact Assessment include:

Historical Buildings and Structures Survey

Findings and Assessment

·        There were no cultural heritage resources located in the Study Area. All structures were identified as modern squatter structures with no cultural heritage features

·        The three villages highlighted in the study brief were found to contain 112 cultural heritage resources

·        A number of graves were identified on the hill behind the village of Ng Uk Tsuen (outside of the Study Area)

·        A fung shui wood was identified behind the village of Ng Uk Tsuen (outside of the Study Area)

 

Recommendations

·        The Study Area contained no cultural heritage resources, thus, no mitigation measures are required

·        The cultural heritage resources outside the Study Area were found to warrant no further mitigation measures based on the following factors:

o        Adequate screening from the development site through existing woodlands, topographical setting and modern structures

o        Sufficient distance from the development site

o        Orientation away from the development site

 

Historical Landscape Features

Findings and Assessment

17.11.3   The assessment has found that although the basic pattern of the bunds was retained, the bunds have been extensively changed in size and shape.

Recommendations

17.11.4   In order to retrieve information concerning the composition of the bunds it is recommended that a brief recording exercise be carried out during site formation.

 

17.12      Landscape and Visual Impact Assessment

17.12.1   The potential impacts to the landscape resources and character, and visually sensitive receivers arising from the proposed development has been assessed in accordance with Clause 3.5.9 of the EIA Study Brief, Annexes 10 and 18 of the EIAO – TM. The methodology stated in Section 11.3 for undertaking the landscape and visual impact assessment follows the provisions of EIAO Guidance Note No.8/2002 - Preparation of Landscape and Visual Impact Assessment under the EIAO. During the selection of the preferred option it was found that two options, 1A and 1B, were equally acceptable from a landscape and visual impact perspective, and so both options were taken forward in to the detailed assessment. The findings and conclusions from this dual assessment are described below.

Landscape Planning and Development Control Review

17.12.2   A review of the future proposals for the Study Area as represented in the Outline Zoning Plans reveals that the proposed schemes for both Options 1A and 1B will fit into the future landscape of the Study Area. Further the proposed marsh habitat planned for the area to the north of the development site will form a continuation of the existing Hong Kong Wetland Park contributing to a more coherent landscape framework. The proposals would therefore largely be compatible with the planning intention for the area and the planned landuses in the adjoining areas.  

Existing Trees – Options 1A and 1B

17.12.3   Generally trees or tree groups will be maintained where possible.  It is estimated that approximately 238 (36%) of the trees would be retained.  The proposed compensatory planting of a combination of native and amenity tree species will mitigate the potential impacts on the existing trees within the development site. This includes the planting of some 300 new trees within the main development area in addition to the 3750 square metres of mass woodland planting established within the project boundary. This equates to some 1050 new trees with a compensatory planting ratio of approximately 2.6:1 (new planting: trees recommended for felling).

Landscape Resources – Options 1A and 1B

17.12.4   In general the impact on LRs within the Study Area will be largely negligible. Further many will generally benefit from by the creation of WNR and fishpond enhancement as these works would improve the quality of the resource including their ecological value. This enhancement includes the establishment of plantation woodland with a moderate beneficial impact. The main impacts on the landscape resources of the area are due to the loss of approximately 4 hectares of fishponds (LR 8) and a lesser extent the loss or modification of the existing landform (LR 1) due to the proposed creation of the WNR which will result from the removal of some fishpond bunds. Despite these losses being relatively small compared to the overall area of the resource the fish ponds are important to the landscape area of the region and so this has informed the design of the proposals leaving the largest possible area intact. The impacts to these resources will range from moderate to slight adverse with the impact on the other landscape resources within the Study Area being largely negligible.

Landscape Character – Options 1A and 1B

17.12.5   The growth to maturity of the tree and shrub planting proposed as part of the marsh habitat and the landscape buffer planting on the periphery of the development will serve to encourage a greater sense of landscape and visual integration with the development’s context. This planting will also serve to soften the transition between the verticality of the proposed built environment and the surrounding coastal plain. The planting proposals will also alleviate some indirect impacts on the Ng Uk Tsuen Village Cluster (V1) and the Kai Shan Range (NUA 1) and benefit the local character ranging from slight to moderate adverse impact with full establishment of the proposed mitigation measures. The impact on the landscape character of the village cluster will be restricted to the northern periphery of the settlement. Impacts on the character of the existing Fishponds (AGR 2) will also be partially alleviated through the implementation of the proposed mitigation measures resulting in a moderate adverse impact. The landscaping associated with the proposed landscape buffer and the establishment of the WNR would also have a slight beneficial impact on the adjacent areas of the Hong Kong Wetland Park (OS1).

Visual Amenity – Options 1A and 1B

17.12.6   Many of the views for the identified VSRs share a number of common characteristics which include their expansive nature, the viewing distance and in many cases an elevated viewing position resulting in slight to moderate/significant adverse impact. In this situation the proposed primary mitigation measures such as the location of the development platform and form of the built structure including the adoption of a stepped building height, incorporation of sky gardens (Option 1A) and view corridors take precedence over the proposed soft landscape mitigation measures although these measures serve an important role in further mitigating the predicted adverse impacts. 

17.12.7   The shared characteristics of the existing views mean that for many VSRs Options 1A and 1B would appear similar. It may be argued that despite the Option 1B adopting a 15 storey maximum height the flat roofline (contrasting with the organic forms of the adjacent landscape), the introduction of an additional block, the omission of sky gardens and the reduced view corridors ensure that the proposals have a similar level of visual prominence. Given this the predicted visual impacts particular for the VSRs to the north, east and west of the application site are similar to those predicted for Option 1A.

17.12.8   The main differences between Options 1A and 1B would be apparent in views from within the villages of Ng Uk Tsuen (VSR 6) and Shing Uk Tsuen (VSR7). The reduced height of Option 1B would reduce the visibility of the proposals in views from within the village however in many instances these views are largely interrupted by existing features such as the adjacent village houses and the intervening vegetation. In views from the northern periphery of the village it is considered that the reduced height of Option 1B is balanced to an extent by the wider view corridors of Option 1A which allow greater albeit framed visual access to the fishpond area to the north. The predicted visual impacts for Options 1A and 1B when viewed from the edge of the villages (approximately 10 houses would be affected) would be significant to moderate advesre although these impacts would affect a relatively small number of VSRs. Whilst the predicted visual impacts for VSRs with a view of the proposals for Option 1A would be slight to moderate adverse and Option 1B slight adverse. Again due to the characteristics of the existing views from within the villages these impacts are limited to a relatively few VSRs.

Potential Night Time Glare – Options 1A and 1B

17.12.9   Given that the majority of the identified VSRs are located at distances of 1000m or more from the proposed development and the fact that in many views the development will be seen against the backdrop of the existing street lighting in the adjacent villages and Yuen Long the predicted night time glare impacts will not be significant. The adoption of responsive lighting design with glare control measures would serve to mitigate much of the potential impacts. In addition the proposed use of a vegetative landscape buffer and the screening effect of the existing vegetation will mitigate much of the potential night time impacts for VSRs at low elevations such as the Hong Kong Wetland Park. Overall the night-time glare impact resulting from the proposed architectural and road lighting would have a predicted slight adverse to negligible impact for the large part of the existing and planned VSRs.

Acceptability of Impacts

17.12.10                       In accordance with Annex 10, Paragraph 1.1(c) of the EIAO TM, the landscape and visual impacts of the project under the proposed development at Fung Lok Wai for both Options 1A and 1B would be ‘acceptable with mitigation’ that is to say `there would be some adverse effects, but these can be eliminated, reduced or offset to an extent by specific measures’..

 

17.13      Overall Conclusion

17.13.1   All key environmental issues related to the construction and operation of the Project are identified and assessed in accordance with the requirements of the EIA Study Brief. Practicable and cost-effective mitigation measures have been recommended where necessary to minimise the identified impacts to acceptable levels. An EM&A programme is also recommended for checking the implementation of sufficient mitigation measures with respect to key environmental concerns identified for the construction phase.

17.13.2   In conclusion, with the implementation of the recommended environmental mitigation measures, the construction and operation of Project in the form of either Option 1A or Option 1B should not cause any unacceptable environmental impact on the surrounding sensitive uses.