Drainage Services Department

Consultants Management Division

42/F, Revenue Tower

5 Gloucester Road

Wanchai, Hong Kong

Agreement No. CE 80/2001(DS) Drainage Improvement in

Tsuen Wan and Kwai Chung –

Tsuen Wan Drainage Tunnel

Environmental Impact Assessment (Revised Final)

Document No. 204417/18/E

June 2005

Mott Connell Limited

40/F, Hopewell Centre

183 Queen’s Road East

Wan Chai, Hong Kong

This document has been prepared for the titled project or named part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Mott Connell Ltd being obtained. Mott Connell Ltd accepts no responsibility or liability for the consequence of this document being used for a purpose other than the purposes for which it was commissioned. Any person using or relying on the document for such other purpose agrees, and will by such use or reliance be taken to confirm his agreement to indemnify Mott Connell Ltd for all loss or damage resulting therefrom. Mott Connell Ltd accepts no responsibility or liability for this document to any party other than the person by whom it was commissioned.

List of Contents Page

Chapters

1. INTRODUCTION 1-1

1.1 Background

1.2 Project History

1.3 Environmental Impact Assessment Ordinance

1.4 Documents Reviewed

1.5 Inter-Relationship with Other EIA Studies

1.6 References

2. PROJECT DESCRIPTION 2-1

2.1 The Proposed Project

2.2 Option Selection

2.2.1 Background

2.2.2 Tunnel Options

2.2.3 Evaluation Results of the Tunnel Options

2.2.4 Recommendations

2.3 Construction Methodology

2.3.1 Rationale

2.3.2 Construction of tunnel and underground structures

2.3.3 Construction of surface structures

2.3.4 Intake I-1 (Figures 2.14 to 2.15 refers)

2.3.5 Intake I-2 (Figures 2.16 to 2.18 refers)

2.3.6 Intake I-3 (Figures 2.19 to 2.22 refers)

2.3.7 Outfall O-1 (Figures 2.23 to 2.25 refers)

2.4 Construction Programme

2.5 Mechanism of Intake Design

2.5.1 Intake I-1 (Figures 2.14 to 2.15 refers)

2.5.2 Intakes I-2 and I-3 (Figures 2.16 to 2.22 refers)

3. AIR QUALITY IMPACT ASSESSMENT 3-1

3.1 Introduction

3.2 Legislation, Standards, Guidelines and Criteria

3.3 Assessment Methodology

3.3.1 Construction

3.3.2 Operation

3.4 Baseline Conditions/ Sensitive Receivers

3.4.1 Baseline Conditions

3.4.2 Sensitive Receivers

3.5 Impact Assessment

3.5.1 Construction

3.5.2 Operation

3.6 Mitigation of Impacts

3.6.1 During Construction

3.6.2 During Operation

3.7 Residual Impacts

3.8 Environmental Monitoring and Audit

3.9 Conclusions and Recommendations

3.10 References

4. NOISE IMPACT ASSESSMENT 4-1

4.1 Introduction

4.2 Legislation, Standards, Guidelines and Criteria

4.3 Assessment Methodology

4.4 Baseline Conditions/ Sensitive Receivers

4.4.1 Baseline Conditions

4.4.2 Sensitive Receivers

4.5 Impact Assessment

4.5.1 Construction

4.5.2 Operation

4.6 Mitigation of Impacts

4.6.1 During Construction

4.6.2 During Operation

4.7 Residual Impacts

4.8 Environmental Monitoring and Audit

4.9 Conclusion

4.10 References

5. WATER QUALITY IMPACT ASSESSMENT 5-1

5.1 Introduction

5.2 Legislation, Standards, Guidelines and Criteria

5.3 Assessment Methodology

5.4 Baseline Conditions/ Sensitive Receivers

5.4.1 Baseline Conditions

5.4.2 Water Quality Modelling

5.4.3 Marine Water Quality

5.4.4 Bathing Beach Water Quality

5.4.5 River Water Quality

5.4.6 Sediment Quality

5.5 Sensitive Receivers

5.5.1 Definitions

5.5.2 Bathing Beaches

5.5.3 Fish Culture Zone

5.5.4 Water Recreational Areas

5.5.5 Water Gathering Grounds

5.5.6 Future Planned Water Sensitive Receivers

5.6 Impact Assessment

5.6.1 During Construction

5.6.2 During Operation

5.7 Mitigation of Impacts

5.7.1 During Construction

5.7.2 Emergency Responses to Spillages

5.7.3 During Operation

5.8 Residual Impacts

5.9 Cumulative Impacts

5.10 Environmental Monitoring and Audit

5.11 Conclusions

5.12 References

6. WASTE IMPACT ASSESSMENT 6-1

6.1 Introduction

6.2 Legislation, Standards, Guidelines and Criteria

6.3 Assessment Methodology

6.4 Waste Arising

6.4.1 Construction

6.4.2 Operation

6.5 Management/ Mitigation of Impacts

6.5.1 During Construction

6.5.2 During Operation

6.6 Environmental Monitoring and Audit

6.7 Conclusions and Recommendations

6.8 References

7. ECOLOGICAL IMPACT ASSESSMENT 7-1

7.1 Introduction

7.2 Relevant Legislation and Guidelines

7.3 Assessment Methodology

7.4 Results of Baseline Field Surveys

7.5 Potential Impacts

7.5.1 Construction Phase

7.5.2 Operational Phase

7.6 Impact Assessment

7.6.1 Construction Phase

7.6.2 Operational Phase

7.6.3 Cumulative Impact

7.6.4 Impact Evaluation

7.7 Mitigation Measures

7.7.1 Avoidance

7.7.2 Minimisation

7.7.3 Compensation

7.8 Residual Impacts

7.9 Environmental Monitoring and Audit

7.10 Conclusion

8 CULTURAL HERITAGE IMPACT ASSESSMENT 8-1

8.1 Introduction

8.2 Relevant Legislation & Guidelines

8.3 Assessment Methodology

8.3.1 Assessment Scope

8.3.2 Identification of Baseline Cultural Heritage Conditions

8.3.3 Archaeological Survey

8.3.4 Historical Buildings and Structures Survey

8.3.5 Impact Assessment

8.4 Baseline Conditions and Sensitive Receivers

8.4.1 Archaeological Resources

8.4.2 Historical Buildings and Structures

8.5 Impact Assessment

8.5.1 Construction Phase

8.5.2 Operational Phase

8.6 Mitigation Measures

8.7 Residual Impacts

8.8 Environmental Monitoring and Audit

8.9 Conclusion

9. HAZARD TO LIFE 9-1

9.1 Introduction

9.2 Technical Requirement for Hazard to Life Assessment

9.3 Hazard Identification

9.4 Conclusion

10. FISHERIES IMPACT ASSESSMENT 10-1

10.1 Introduction

10.2 Fisheries Impact Assessment Methodology

10.3 Baseline Conditions & Sensitive Receivers

10.3.1 Capture Fisheries

10.3.2 Culture Fisheries

10.3.3 Fisheries Importance

10.3.4 Sensitive Receivers

10.4 Identification of Fisheries Impacts

10.5 Assessment of environmental Impacts

10.6 Mitigation of Adverse Environmental Impacts

10.7 Residual Fisheries Impacts

10.8 Environmental Monitoring & Audit

10.9 Conclusions

11. ENVIRONMENTAL MONITORING AND AUDIT (EM&A) REQUIREMENTS 11-1

11.1 Air Quality Impact Assessment

11.2 Noise Impact Assessment

11.3 Water Quality Impact Assessment

11.4 Waste Impact Assessment

11.5 Ecological Impact Assessment

11.6 Cultural Heritage Impact Assessment

11.7 Hazard to Life

11.8 Fisheries Impact Assessment

12 CONCLUSIONS AND RECOMMENDATIONS 12-1

12.1 Air Quality Impact Assessment

12.2 Noise Impact Assessment

12.3 Water Quality Impact Assessment

12.4 Waste Impact Assessment

12.5 Ecological Impact Assessment

12.6 Cultural Heritage Impact Assessment

12.7 Hazard to Life

12.8 Fisheries Impact Assessment

12.9 Environmental Outcomes

12.9.1 Population and Environmental Sensitive Areas Protected

12.9.2 Environmental Friendly Designs and Problems Avoided

12.9.3 Environmental Benefits of the Project

13 IMPLEMENTATION SCHEDULE 13-1

Tables

Table 2.1 Data Summary of Tunnel Options

Table 2.2 Evaluation Criteria and their Weightings

Table 2.3 Summary of Evaluation

Table 2.4 Interception of Flow at Intake I-1

Table 2.5 Interception of Flow at Intake I-2

Table 2.6 Interception of Flow at Intake I-3

Table 3.1 Hong Kong Air Quality Objectives

Table 3.2 Emission Factors for Construction Activities

Table 3.3 Air Quality at Kwai Chung and Tsuen Wan Monitoring Stations (5-year annual averages)

Table 3.4 Representative Air Sensitive Receivers (ASRs)

Table 3.5 Predicted Cumulative Hourly and Daily TSP Levels (mgm-3) at 1.5m above local ground level – Unmitigated

Table 3.6 Predicted Cumulative Hourly and Daily TSP Levels (mgm-3) at 1.5m above local ground level – Mitigated

Table 4.1 Acceptable Noise Levels (ANL, L_{eq, 5 min} dB(A))

Table 4.2 Groundborne Noise Criteria (ANL, (ANL, L_{eq, 5 min} dB(A))

Table 4.3 Noise Sensitive Receivers

Table 4.4 Plant Inventory (for Tunnel Construction) (No Mitigation Measures)

Table 4.5 Cumulative Noise Impacts (No mitigation Measures) - (L_eq,30min dB(A))

Table 4.6 Cumulative Noise Impacts (Mitigation Measures – Quiet Plant)

Table 4.7 Cumulative Noise Impacts (Mitigation Measures – Noise Barrier)

Table 5.1 Different Groups of Inland Water Specified in the TM

Table 5.2 Standards for Effluents Discharged into Group A Inland Waters

Table 5.3 Standards for Effluents Discharged into Group D Inland Waters

Table 5.4 Marine Water Quality Objectives Relevant to the Western Buffer Water Control Zone

Table 5.5 Potential Activities which could generate Water Quality Issues during Construction

Table 5.6 Water Quality at Intake Structures

Table 5.7 Baseline Marine Water Quality Data 2003

Table 5.8 Baseline River Water Quality Data 2003

Table 5.9 Summary of Construction Activities and Potential Impacts

Table 5.10 No. of Days Rainfall Exceeds 30mm/hr 1999 – 2001

Table 5.11 Streamflow Maintained to the Downstream Rivers/ Channels

Table 5.12 Range of Streamflow under Normal Conditions

Table 5.13 Estimated Average Pollution Loads

Table 5.14 Estimated Pollution Concentration

Table 5.15 Estimated E. coli Concentration

Table 5.16 Annual Geometric Mean E. coli Level at Approach Beach 1995-2004

Table 5.17 Spill Control and Response Plan

Table 6.1 Volumes of Waste Generated from Construction of Surface Structures/Site Formation

Table 7.1 Habitat Types recorded within the Study Area

Table 7.2 Overall Habitat Loss due to the Drainage Improvement Works

Table 7.3 Habitats to be Affected during Construction of Intake I-2

Table 7.4 Habitats to be Affected during Construction of Intake I-3

Table 7.5 Impacts on the Species of Conservation Interest

Table 7.6 Overall Impact Evaluation for Stream/Channel

Table 7.7 Overall Impact Evaluation for Plantation and Village-Orchard

Table 7.8 Overall Impact Evaluation for Intertidal Habitat (Artificial Disturbed Seashore) and Urbanized/Disturbed Area

Table 7.9 Overall Habitat Loss due to the Drainage Improvement Works

Table 8.1 Grading of Historical Buildings

Table 8.2 Archaeological Fieldwork Requirements

Table 8.3 Potential Historical Buildings and Features Identified within the Study Area

Table 8.4 Separation Distances of Historical Buildings and Structures from Construction Activities at Sam Dip Tam

Table 8.5 Separation Distances of Historical Buildings and Structures from Construction Activities at Yau Kom Tau

Table 10.1 Area (ha) and Number of Vessels Operating During 1996 - 1997 in Each AFCD Fishing Zone within the Study Area

Table 10.2 Fisheries Production Values from each AFCD Fishing Zone within the Study Area (1996 – 1997 Port Survey)

Table 10.3 Top Five Adult Fish (by weight) Caught in Each AFCD Fishing Zone within the waters of the Study Area (1996 - 1997 Port Survey)

Appendices

Appendix A Construction Programme

Appendix B Detailed Calculations of Construction Dust Emission Factors

Appendix C Sample of Output File of the FDM Model Run

Appendix D Detailed Noise Calculations

Appendix E Baseline Water Quality Monitoring Report

Appendix F Baseline Ecological Survey Report

Appendix G Archaeological Survey Report

Appendix H Built Heritage Impact Assessment Report

Figures

Figure 1.1 Tunnel Alignment and Surrounding Area

Figure 1.2 Alternative Locations Considered for Intake I-2

Figure 1.3 Alternative Locations Considered for Intake I-3

Figure 2.1 Tunnel General Layout

Figure 2.2 Typical Tunnel Section

Figure 2.3 Tunnel Alignment (Sheet 1 of 10)

Figure 2.4 Tunnel Alignment (Sheet 2 of 10)

Figure 2.5 Tunnel Alignment (Sheet 3 of 10)

Figure 2.6 Tunnel Alignment (Sheet 4 of 10)

Figure 2.7 Tunnel Alignment (Sheet 5 of 10)

Figure 2.8 Tunnel Alignment (Sheet 6 of 10)

Figure 2.9 Tunnel Alignment (Sheet 7 of 10)

Figure 2.10 Tunnel Alignment (Sheet 8 of 10)

Figure 2.11 Tunnel Alignment (Sheet 9 of 10)

Figure 2.12 Tunnel Alignment (Sheet 10 of 10)

Figure 2.13 Tunnel Longitudinal Profile

Figure 2.14 Intake I-1 - General Layout

Figure 2.15 Intake I-1 - Sections and Details

Figure 2.16 Intake I-2 - General Layout

Figure 2.17 Intake I-2 - Revised Intake Arrangement

Figure 2.18 Intake I-2 - Revised Sections

Figure 2.19 Intake I-3 - General Layout

Figure 2.20 Intake I-3 - Sections (Sheet 1 of 3)

Figure 2.21 Intake I-3 - Sections (Sheet 2 of 3)

Figure 2.22 Intake I-3 - Sections (Sheet 3 of 3)

Figure 2.23 Outfall O-1 - General Layout

Figure 2.24 Outfall O-1 - Sections

Figure 2.25 Outfall O-1 - Plan and Sections

Figure 2.26 General Arrangement of Tunnel Options 1-4

Figure 2.27 Construction Work Site at Boundary at Intake I-1

Figure 2.28 Construction Work Site at Boundary at Intake I-2

Figure 2.29 Construction Work Site at Boundary at Intake I-3

Figure 2.30 Construction Work Site at Boundary at Outfall O-1

Figure 2.31 PPFS Maintenance Access Arrangement

Figure 2.32 Alternative Maintenance Access to Outfall Structure

Figure 3.1 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Intake I-1

Figure 3.2 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Intake I-2

Figure 3.3 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Intake I-3

Figure 3.4 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Outfall O-1

Figure 3.5 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Intake I-1

Figure 3.6 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Intake I-2

Figure 3.7 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Intake I-3

Figure 3.8 Predicted Daily Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Outfall O-1

Figure 3.9 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Intake I-1

Figure 3.10 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Intake I-2

Figure 3.11 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Intake I-3

Figure 3.12 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Mitigated Case Around Outfall O-1

Figure 3.13 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Intake I-1

Figure 3.14 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Intake I-2

Figure 3.15 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Intake I-3

Figure 3.16 Predicted Hourly Average TSP Concentration Contours at 1.5m above Ground for Unmitigated Case Around Outfall O-1

Figure 4.1 Locations of Noise Sensitive Receivers around Intake I-1

Figure 4.2 Locations of Noise Sensitive Receivers around Intake I-2

Figure 4.3 Locations of Noise Sensitive Receivers around Intake I-3

Figure 4.4 Locations of Noise Sensitive Receivers around Outfall O-1

Figure 4.5 Illustrations of the Proposed Blasting at Intakes I-2 and I-3

Figure 4.6 Indicative Locations of the Temporary Barrier for Construction Around Intake I-2

Figure 5.1 Locations of Water Quality Sensitive Receivers and EPD Water Quality Monitoring Station

Figure 5.2 Cascade at Outfall O-1

Figure 5.3 Sequencing of Works at Intake I-1

Figure 5.4 Sequencing of Works at Intake I-2

Figure 5.5 Sequencing of Works at Intake I-3

Figure 5.6 Sequencing of Works at Outfall O-1

Figure 5.7 Proposed Locations of Stockpiling at Intakes

Figure 5.8 Stockpiling Area and Sediment Tank at Outfall O-1

Figure 5.9 Bathing Beach Water Quality in Tsuen Wan District

Figure 5.10 Water Quality Index (WQI) of Sam Dip Tam Stream and its tributaries

Figure 5.11 Agricultural Activities near Intake Structure I-2

Figure 5.12 Agricultural Activities near Intake Structure I-3

Figure 5.13 Trash Grill Detail

Figure 7.1 Habitats to be affected by the Construction of Intake I-1

Figure 7.2 Habitats to be affected (Permanently) by the Construction of Intake I-2

Figure 7.3 Habitats to be affected (Temporary) by the Construction of Intake I-2

Figure 7.4 Habitats to be affected (Permanently) by the Construction of Intake I-3

Figure 7.5 Habitats to be affected (Temporary) by the Construction of Intake I-3

Figure 7.6 Habitats to be affected by the Construction of Outfall O-1

Figure 7.7 Extent of Different Types of Works of Intake I-2

Figure 7.8 Extent of Different Types of Works of Intake I-3

Figure 7.9 Habitats Map Near Intake I-2

Figure 7.10 Proposed Master Planting Scheme for I-1

Figure 7.11 Proposed Master Planting Scheme for I-2

Figure 7.12 Proposed Master Planting Scheme for I-3

Figure 7.13 Proposed Master Planting Scheme for O-1

Figure 7.14 Proposed Master Planting Scheme for O-1

Figure 8.1 Cultural Heritage Resources in the Vicinity of the Drainage Tunnel System

Figure 8.2 Potentially impacted sites at Sam Dip Tam

Figure 8.3 Potentially impacted sites at Yau Kom Tau

Figure 9.1 Location of nearby Potentially Hazardous Installations (PHI)

Figure 10.1 Location of Ma Wan Fish Culture Zone and Distribution of AFCD Fishing Zones in the Vicinity of the Outfall O-1

Plates

Plate 2.1 The Conditions around the Intake I-1 Structures

Plate 2.2 The Conditions around the Intake I-2 Structures

Plate 2.3 The Conditions around the Intake I-3 Structures

Plate 2.4 The Conditions around the Outfall O-1 Structures