11. Landscape & Visual Impact

11.1 Introduction

11.1.1 This section assesses the potential landscape and visual impacts arising from the proposed construction and upgrading of the sewage collection, treatment and disposal facilities, together with the mitigation measures proposed to alleviate the impacts.

11.1.2 This assessment has based on the criteria and guidelines stated in Annexes 10 and 18 of the EIAO-TM and EIAO Guidance Note No. 8/2010 for evaluating and assessing landscape and visual impacts and has covered the scope outlined in Section 3.4.8 of the EIA Study Brief.

11.2 Project Summary

11.2.1 The proposed works under the Project comprises the following items and as shown in Layout Plan of Figure 2.1:

(a) Upgrading of the existing Cheung Chau Sewage Treatment Works (STW) to secondary treatment level with design capacity of 9,800 m³/day ;

(b) Upgrading of the existing Pak She Sewage Pumping Station (SPS) by increasing the pumping capacity of 42,336 m³/d (490 L/s);

(c) Sewers works in Cheung Chau including upgrading/rehabilitation of the existing sewers at Cheung Chau and provision of new sewers to unsewered areas/villages including Tai Kwai Wan San Tsuen, Pak She San Tsuen, Nam She Tong, Fa Peng, Chi Ma Hang, Round Table Villages, Tai Shek Hau and Sin Yan Tseng, Tai Tsoi Yuen Kui, Ko Shan Tsuen and Lung Tsai Tsuen.

11.2.2 Under Part I, Schedule 2 of the EIAO, the Project consists of the following designated projects:

(a) Upgrading of the existing Cheung Chau STW – under Item F.2 which is Sewage Treatment Works with an installed capacity of more than 5,000 m³/d and a boundary less than 200m from the boundary of a residential area (item 11.2.1(a));

(b) Upgrading of the existing Pak She SPS - under Item F.3 which is Sewage Pumping Station with an installed capacity of more than 2,000 m³/d and a boundary less than 150m from the boundary of a residential area (item 11.2.1(b)); and

(c) Upgrading of the existing Cheung Chau STW – under Item F.4 which includes an activity for the reuse of treated sewage effluent from a treatment plant (item 11.2.1(a)).

11.2.3 The proposed works at Cheung Chau and proposed general layout plan of the Cheung Chau STW are shown in Figure 2.1 and Figure 2.2.

Sewers Works

11.2.4 The proposed sewers works will be laid underground along the existing carriageway, footpaths and paved tracks. The construction works will be carried out section by section in a local area with a short period of time, in order to reduce the disturbance to the surrounding areas and nearby residents. The works area will be reinstated to its original conditions. Landscape and visual impact during construction and operation stage of the sewers is considered to be negligible.

Sewage Pumping Station

11.2.5 The proposed upgrading of the existing Pak She SPS will include replacement of pumps with higher pumping capacity and other E&M equipment, diversion of existing emergency bypass away from typhoon shelter and minor modification of existing pump troughs. All the works will be either constructed within the existing superstructure of Pak She SPS or would be reinstated to its original conditions. Landscape and visual impact during construction and operation stage is therefore considered to be negligible.

11.2.6 As discussed in Section 2 - Project Description, an alternative scheme with construction of a section of deep gravity sewer has been proposed. As such, the proposal of construction of Kwun Yam Wan SPS will no longer exist, landscape and visual impact arising from the SPS at the adjacent Kwun Yam Beach will be avoided.

Sewage Treatment Works

11.2.7 The proposed upgrading of the Cheung Chau STW will take place within the boundary of the existing Cheung Chau STW. Landscape and visual impact during construction and operation stage will be assessed in the following sections.

11.3 Review of Planning and Development Control Framework

11.3.1 A review of the existing and planned development framework for the proposed works and their surroundings has been considered, in order to identify any issues within the neighbouring planned land uses, and therefore to identify potential sensitive receivers, and to ensure a high compatibility between the proposed project and the surroundings.

11.3.2 According to approved Cheung Chau Outline Zoning Plan No. S/I-CC/5, the existing Cheung Chau STW is located in the area zoned as “Other Specified Uses (Sewage Treatment Works)”. Zones with “Government, Institution or Community (G/IC)”, Residential (Group A) (R(A))”, “Green Belt (GB)”, “Costal Protection Area (CPA)”, “Open Space (O)”, “Village Type Development (V)”, and “Other Specified Uses (OU)” are found within the assessment area.

11.3.3 The Cheung Chau STW is located in a zone which is intended to be designated land for sewage treatment works. According to the Schedule of Uses of the relevant OZP, any new development, or addition, alteration and/or modification to or redevelopment of an existing building shall be with a maximum building height of 2 storeys (10m), or the height of the existing building, whichever is the greater. Planning application to the Town Planning Board under section 16 of the Town Planning Ordinance may be required if the proposed STW cannot fulfil the specified requirements.

11.3.4 According to the Notes of the relevant OZP, the proposed sewerage works shall be always permitted. Thus no conflict to the relevant planning and development control framework.

11.4 Relevant Legislations, Standards & Guidelines

11.4.1 The following Environmental Legislation and Standards are considered:

Ÿ Approved Cheung Chau Outline Zoning Plan (OZP) No. S/I-CC/5 and the Town Planning Ordinance;

Ÿ EIAO, Annexes 10 and 18 of EIAO Technical Memorandum and EIAO Guidance Note No. 8/2010 – Preparation of Landscape and Visual Impact Assessment under the Environmental Impact Assessment Ordinance;

Ÿ The Forests and Countryside Ordinance (Cap 96)

Ÿ The Forestry Regulations – made under Section 3 of The Forests and Countryside Ordinance (Cap 96), and Government General Regulation 740;

Ÿ ETWB TCW No. 3/2006 - Tree Preservation;

Ÿ ETWB TCW No. 5/2005 - Protection of natural streams/rivers from adverse impacts arising from construction works;

Ÿ ETWB TCW No. 29/2004 - Registration of Old and Valuable Trees, and Guidelines for their Preservation;

Ÿ ETWB TCW No. 14/2004 - Maintenance of Stormwater Drainage Systems and Natural Watercourses;

Ÿ ETWB TCW No. 2/2004 - Maintenance of Vegetation and Hard Landscape Features;

Ÿ ETWB TCW No. 7/2002 - Tree Planting in Public Works;

Ÿ DSD Technical Circular No. 9/2006 - Vetting Committee on Aesthetic Design of Pumping Station Buildings, and Guidelines on Aesthetic Design of Pumping Station Buildings; and

Ÿ Hong Kong Planning Standards and Guidelines, Chapter 4 - Recreation, Open Space & Greening, and Chapter 10 – Conservation.

11.5 Landscape and Visual Impact Assessment Methodology

11.5.1 The landscape and visual impacts are assessed separately for the construction phase and operation phase. The methodologies to assess landscape and visual impacts are described in the following sections.

Methodology of Assessment of Landscape Impacts

11.5.2 The assessment of landscape impacts involves the following procedures:

Ÿ Identification of Baseline Landscape Resource (LR) and Landscape Character Area (LCA): A desktop research study on aerial photos and topographical maps, followed by site visit and photo-taking, is conducted to identify the baseline LR and LCA found within the study boundary, which is within 500m from the proposed site as presented in Figure 11.1.

11.5.3 Landscape Resource (LR) considered including: natural and secondary woodland; amenity planting; scrubland and grassland; natural topography; significant planning designation, e.g. Country Park or Green Belt; and heritage or cultural features.

11.5.4 Physical components related to the visual amenity, cultural association and heritage value of the Landscape Character Area (LCA) are considered, elements including: land use; public use of land; extent of vegetation; age of landscape; cultural, heritage and religious elements; scale and type of buildings; pattern of settlement; location and topography; and extent of natural compare to man-made.

Ÿ Assessment of “Sensitivity” of LR and LCA: The “Sensitivity” of LR and LCA is assessed based on the factors including (i) whether the resource is common or rare; (ii) whether it is considered to be of local, regional, national or global importance; (iii) whether there are any statutory or regulatory limitations/requirements relating to the resource; (iv) the quality of the resource; (v) the maturity of the resource, and (vi) the ability of the resource to accommodate changes. The sensitivity of LR and LCA is rated as high, medium or low:

Ø High - Important components of landscape of particularly distinctive character susceptible to relatively small changes.

Ø Medium - A landscape of moderately valued characteristics reasonably tolerant of change.

Ø Low - A relatively unimportant landscape, the nature of which is largely tolerant to change.

Ÿ Assessment of “Magnitude of Change” for landscape impacts: The “Magnitude of Change” is assessed based on the factors including (i) the physical extent of impact; (ii) the landscape context of impact and (iii) the timescale of impact. The magnitude of change is rated as large, intermediate, small and negligible:

Ø Large – Notable permanent change in the landscape characteristics over an extensive area ranging to very intensive changes over a more limited area.

Ø Intermediate – Moderate change in a localised area.

Ø Small – Virtually imperceptible change or temporary change.

Ø Negligible – Virtually no change in the area.

11.5.5 Assessment of “Impact Significance Threshold before Mitigation” for landscape impacts: The degree of significance of the landscape impacts is determined based on the “Sensitivity” and “Magnitude of Change” for various LR and LCA, as shown in Table 11.1. The degree of significance is divided into four thresholds:

Ÿ Substantial – Adverse or beneficial and reversible or irreversible impact where the proposal would cause significant deterioration or improvement in existing landscape quality.

Ÿ Moderate – Adverse or beneficial and reversible or irreversible impact where the proposal would cause noticeable deterioration or improvement in existing landscape quality.

Ÿ Sight – Adverse or beneficial and reversible or irreversible impact where the proposal would cause a barely perceptible deterioration or improvement in existing landscape quality.

Ÿ Insubstantial – No discernible change in the existing landscape quality.

Table 11.1 : Matrix for Impact Significance Threshold before Mitigation

Magnitude of Change	Sensitivity
	High	Medium	Low
Large	Substantial	Substantial / Moderate	Moderate / Slight
Intermediate	Substantial / Moderate	Moderate	Moderate / Slight
Small	Moderate / Slight	Moderate / Slight	Slight / Insubstantial
Negligible	Insubstantial	Insubstantial	Insubstantial

11.5.6 Identification of Potential Mitigation Measures: The potential measures to be implemented during the construction and operation phases are proposed in order to minimize unavoidable adverse impacts and/or to generate beneficial long-term impacts.

11.5.7 Identification of “Residual Impact Significance Threshold after Mitigation” for landscape impacts: The accumulative influence to LR and LCA after full implementation of the proposed mitigation measures is reviewed.

Methodology of Assessment of Visual Impacts

11.5.8 The assessment of visual impacts involves the following procedures:

11.5.9 Identification of zone of visual influence/visual envelope and visually sensitive receivers groups (VSRs): Visual envelop is the viewshed formed by natural/man-made features such as ridgeline or building blocks. The VSRs are those within the visual envelope whose views will be affected by the proposed works. Figure 11.3 presents the extent of the visual envelop and the identified VSRs.

11.5.10 Assessment of “Sensitivity” of VSRs: The “Sensitivity” of VSRs is assessed based on the factors including (i) value and quality of existing views; (ii) availability and amenity of alternative views; (iii) type and estimated number of receiver population; (iv) duration or frequency of view; and (v) degree of visibility.

11.5.11 The sensitivity of VSRs is rated as high, medium or low:

Ÿ High – The VSR is highly sensitive to any change in their viewing experience.

Ÿ Medium – The VSR is moderately sensitive to any change in their viewing experience.

Ÿ Low – The VSR is only slightly sensitive to any change in their viewing experience.

11.5.12 Assessment of “Magnitude of Change” for visual impacts: The “Magnitude of Change” is assessed based on the factors including (i) compatibility of the proposed project with the surrounding landscape; (ii) duration of impacts during construction and operation stages; (iii) scale of impact and distance of the source of impact from the viewer; (iv) reversibility of impact; and (v) potential blockage of the view. The magnitude of change is rated as large, intermediate, small and negligible:

Ÿ Large – The VSR would suffer a major change in their viewing experience.

Ÿ Intermediate – The VSR would suffer a moderate change in their viewing experience.

Ÿ Small – The VSR would suffer a small change in their viewing experience.

Ÿ Negligible – The VSR would suffer no discernible change in their viewing experience.

11.5.13 Assessment of “Impact Significance Threshold before Mitigation” for visual impacts: The degree of significance of the visual impacts is determined based on the “Sensitivity” and “Magnitude of Change” for the VSRs, as shown in Table 11.1. The degree of significance is divided into four thresholds:

Ÿ Substantial – Adverse or beneficial and reversible or irreversible impact where the proposal would cause significant deterioration or improvement in existing visual quality.

Ÿ Moderate – Adverse or beneficial and reversible or irreversible impact where the proposal would cause noticeable deterioration or improvement in existing visual quality.

Ÿ Sight – Adverse or beneficial and reversible or irreversible impact where the proposal would cause a barely perceptible deterioration or improvement in existing visual quality.

Ÿ Insubstantial – No discernible change in the existing visual quality.

11.5.14 Identification of Potential Mitigation Measures: The potential measures to be implemented during the construction and operation phases are proposed in order to minimize unavoidable adverse impacts and/or to generate beneficial long-term impacts. The responsible agencies for the funding, implementation, management and maintenance of the mitigation measures have been identified.

11.5.15 Identification of “Residual Impact Significance Threshold after Mitigation” for visual impacts: The accumulative influence to VSRs after full implementation of the proposed mitigation measures is reviewed.

11.6 Existing Landscape and Visual Baseline

Landscape Baseline – Landscape Resources (LR)

11.6.1 Existing Landscape Resource (LR) are identified within the study boundary, which is within 500m from the proposed site. The locations of the LRs are shown in Figure 11.1 and are summarized in Table 11.2. Photographic records of LRs are shown in Figure 11.4 to 11.6.

11.6.2 During the Ecological Baseline Survey conducted in May - August 2011, no rare or protected plant species and no species of conservation interest was found. Only one tree listed in the Registered Old and Valuable Trees is found at Pak Tai Temple Sitting-out Area (LCSD Is/4), which is located within the 500m Study Area but far away from the proposed Cheung Chau STW upgrading works. Existing trees conditions and tree schedule for the trees at the development site (i.e. Cheung Chau STW) have been extracted from the Tree Survey Report under “Agreement No. CE31/2007(DS) Upgrading of Cheung Chau and Tai O Sewage Collection, Treatment and Disposal Facilities – Investigation” and appended in Appendix 11.1.

11.6.3 Sensitivity of LRs with relatively more important landscape character including coast, and marine (i.e. LR4, LR5) are considered as “High”. Sensitivity of LRs of landscaping nature including vegetation, shrubland, young woodland, vegetated slopes and residential area with plants/vegetations in common species (i.e. LR2, LR3, LR6) are considered as “Medium”. Since it is identified in the Tree Survey that an existing tree (T822) within LR1 is with over 1 criteria of Old and Valuable Trees requirements under ETWB Technical Circular 29/2004, the sensitive of LR1 is rated as high. The summary of sensitivity of each LRs is presented in Table 11.2.

Table 11.2 : Description of Identified Landscape Resource (LR)

ID	Landscape Feature	Dominant Tree Species	Sensitivity
LR1	Vegetation within existing Cheung Chau STW	There are currently 18 nos. of existing trees in overall height from 2.5m to 8m, trunk diameter from 90mm to 1,100mm and average crown spread from 2.5m to 13m. They are mainly Ficus elastic, Ficus microcarpa, Macaranga tanarius and Psidium guajava, which are common species. Existing tree T822 (Ficus microcarpa) with trunk diameter of 1,100mm satisfies at least one of the Old and Valuable Trees requirements under ETWB Technical Circular 29/2004.	High
LR2	Shrubland	Patches of shrubland were found bordering the young woodland as a temporary stage in the natural succession towards the latter. These shrublands have a moderate level of structural complexity and were mainly covered by native species with an average height ranging from 1.5 to 3 m. The understorey species were highly variable, from ferns (e.g. Cyclosorus parasiticus and Lygodium japonicum), herbs (e.g. Wedelia trilobata, Rhynchelytrum repens, Peperomia pellucidaI and Dactyloctenium aegyptium) to climbers (e.g. Cassytha filiformis, Cocculus orbiculatus and Morinda umbellata), whilst woody climbers (e.g. Desmos chinensis), shrubs (e.g. Ilex asprella, Psychotria asiatica, Phyllanthus cochinchinensis and Sageretia thea) and small scattered trees (e.g. Rhus succedanea and Sterculia lanceolata) formed the canopy.	Medium
LR3	Young Woodland	Large patches of young woodland, where a total of 100 plant species were recorded, is dominated by native trees including Mallotus paniculatus, Microcos paniculata and Sterculia lanceolata. They are estimated to be an age of 15 to 20 years, with an average canopy height of 4m to 10m.	Medium
LR4	Coast	Common coastal plant species such as Clerodendrum inerme, Pandanus tectorius and Portulaca sp., and some landscaping trees, including Erythrina speciosa and Terminalia catappa, were found planted along the periphery where the coastal area meets the inland developed area. Coastal rock/boulders were also found.	High
LR5	Marine	Seawater body and waterfront character such as breakwaters at the west of the island.	High
LR6	Vegetated Slope and Vegetation within Residential Development	Vegetated slope with planted trees and shrubs in close proximity of the residential buildings of Cheung Kwai Estate and along Cheung Kwai Road.	Medium

Landscape Baseline – Landscape Character Area (LCA)

11.6.4 Existing Landscape Character Area (LCA) are identified within the study boundary, which is within 500m from the proposed site. The locations of the LCAs are shown in Figure 11.2 and are summarized in Table 11.3. Photographic records of LCAs are shown in Figure 11.4 to 11.6.

11.6.5 Sensitivity of LCAs with relatively more important landscape character including natural coastal area and marine (i.e. LCA8, LCA9) are considered as “High”. Sensitivity of LCAs of landscaping nature and natural character including shrubland, hillside, medium-rise residential and village with plants/vegetations in common species (i.e. LCA2, LCA4, LCA5, LCA6) are considered as “Medium”. Other LCAs with relatively unimportant landscape character and the nature of which is largely tolerant to change, including institutional, transportation corridor, industrial and artificial coastal area (i.e. LCA1, LCA3, LCA7, LCA10) are considered as “Low”. The sensitivity of each LCAs is presented in Table 11.3.

Table 11.3 : Description of Identified Landscape Character Area (LCA)

ID	Landscape Character Area	Description	Sensitivity
LCA1	Institutional	Government institutions and public utilities such as Cheung Chau STW, Cheung Chau Slaughter House, Pak She SPS, Cheung Chau Fire Station and Cheung Chau North Sub-station. Common plant species were found in the open spaces, private and public gardens.	Low
LCA2	Shrubland	Shrubland at the south of Cheung Chau STW.	Medium
LCA3	Transportation Corridor	Footpath and paved access road such as Cheung Kwai Road, Pai Chong Road, Ping Chong Road, Pak She Praya Road etc.	Low
LCA4	Medium-rise Residential	Medium-rise residential zone with commercial and retail uses as well as public open space, such as Cheung Kwai Estate. Vegetation includes amenity planting alongside carriageways and footpath.	Medium
LCA5	Village	Village areas including Tai Kwai Wan San Tsuen, Siu Kwai Wan, Pak She San Tsuen, along Pak She Street and Pak She Praya Road. They consist typically grouped village houses, separated by narrow footpaths at hillside/upland. At the periphery of the villages there are sitting areas, and sometimes scattered vegetation, woodland or shrubs, which typically consists of scattered mature trees, e.g. Acacia confusa, Murraya paniculata, Macaranga tanarius and Casuarina equisetifolia. Pak Tai Temple is also located within the village area.	Medium
LCA6	Hillside	They are mainly hillside plantation area, which located around the village areas of Tai Kwai Wan San Tsuen and Pak She San Tsuen. They are essentially natural areas comprising of wooded and grassland slopes. The uplands form scenic backdrop surrounding the village areas and are important visual resources.	Medium
LCA7	Industrial	Industrial zone along Pai Chong Road and Ping Chong Road, which are mainly shipyard, ice factory and open storage area.	Low
LCA8	Marine	Seawater body and waterfront character such as breakwaters at the west of the island.	High
LCA9	Natural Coastal Area	Natural coastal area along Cheung Kwai Road.	High
LCA10	Artificial Coastal Area	Artificial coastal area adjacent to Cheung Chau STW.	Low

Visual Baseline

11.6.6 Five VSRs are identified within the visual envelop as presented in Figures 11.3 to 11.6 with description as below:

VSR1 - Cheung Kwai Road

11.6.7 These VSRs comprise mainly transient passers including residents living in the northern part of Cheung Chau, including Cheung Kwai Estate, Tai Kwai Wan San Tsuen and Scenic Garden, and occasional travellers from elsewhere. The views of Cheung Chau STW from Cheung Kwai Road are occasionally blocked by trees in particular at the northern part of the Cheung Kwai Road. These VSRs are easily distracted by the sea view along the beach which is considered of high amenity value, the sensitivity of these VSRs is considered to be Medium.

VSR2 - Cheung Kwai Estate

11.6.8 Cheung Kwai Estate is located at hillside, with approximately 12m above the Cheung Chau STW. Due to the level difference resulted from the sloped topography and the screening of the existing vegetation, the expanded Cheung Chau STW would not likely to block the views from VSR2. These VSRs are also easily distracted by the sea view which is considered of high amenity value, the sensitivity of these VSRs is considered to be Medium.

VSR3 - Adamasta Channel

11.6.9 Residents/travellers/visitors travelling to Cheung Chau by ferry will be able to see the Cheung Chau STW from a far distance. The duration of view is considered short and these VSRs can have alternative views on other features of the Cheung Chau Island. The sensitivity of these VSRs is considered to be Medium.

VSR4 - Shrine

11.6.10 A shrine is found located near the intersection of Pak Kok Tsui Road and Cheung Kwai Road, which is set in a wooded area beside a small boulder and close to the edge of the road. The shrine is probably worshipped by the villagers of Cheung Kwai Estate, and the number of worshiper is expected to be small. The worshipper may experience glimpses through the gaps between heavily planted trees. While worshiping, the worshipers normally stand in front of the shine where the Cheung Chau STW would be at the back of these VSRs. The sensitivity of these VSRs is considered to be Low.

VSR5 – Beach adjacent to Siu Kwai Wan

11.6.11 These VSRs could have a clear view of the Cheung Chau STW. Alternative sea views along the beach (which is not a gazetted beach) and on the northern side of the Cheung Chau Island are available. Since the degree of visibility of the Cheung Chau STW to these VSRs is high, the sensitivity of these VSRs is considered to be High.

11.6.12 Table 11.4 summarizes the identified VSRs and their sensitivity to change.

Table 11.4: Assessment of Sensitivity of identified VSRs

VSR	Value and quality of existing views	Availability and amenity of alternative views	Type and estimated number of receiver population	Duration or frequency of view	Degree of visibility	Sensitivity
						(Low, Medium, High)
VSR1	Low quality of view along the existing Cheung Chau STW with little visual mitigation measures	High amenity sea view and tree view available	Many	Short term views that change as the VSR moves along the path	Medium	Medium
VSR2	Low quality of view along the existing Cheung Chau STW with little visual mitigation measures	High amenity sea view and tree view available	Many	Long term views	Medium	Medium
VSR3	Low quality of view of the existing Cheung Chau STW with little visual mitigation measures	High availability of alternative views along Cheung Chau coastal	Many	Very short term views as the VSR moves around the area by ferry	Medium	Medium
VSR4	Medium quality of view of the existing Cheung Chau STW with heavy trees screenings	Medium alternative views on the adjacent trees and the Shrine	Very Few	Short term views that change as the VSR moves around the area	Low	Low
VSR5	Medium quality of view across the existing Cheung Chau STW with less structures that enable views to the mountains behind	High amenity sea view and coastal view available	Few	Medium term views	High	High

11.7 Landscape and Visual Impact Assessment

Landscape Impacts - Construction Phase

11.7.1 The potential sources of landscape impacts in the construction phase include:

Ÿ Removal of existing vegetation and tree transplanting;

Ÿ Construction of site access;

Ÿ Demolition of existing treatment units;

Ÿ Excavation and construction of the new treatment units and plant rooms;

Ÿ Temporary stockpiling of excavated materials and construction materials; and

Ÿ Temporary storage of construction plants and equipment.

11.7.2 The upgrading of the Cheung Chau STW will take place within the boundary of the existing Cheung Chau STW. There would be impact on the vegetation within the existing STW (LR1 and LCA1) due to the construction works as listed out in Section 11.7.1 within the construction period (approximately 4.5 years). As the treatment plants will be arranged to minimize disturbance to existing trees, e.g. treatment units designed to be outside the spread of existing tree T822, the magnitude of change on topography and landform as a landscape resource for LR1 and LCA1 during construction is considered to be “Intermediate”.

11.7.3 The proposed STW works would have no direct impact on all other landscape resources and landscape character areas located outside of the existing STW site, on the consideration that the construction works will be confined within the existing boundary of STW, and of temporary nature. Therefore, the magnitude of change for LR2 to LR6 and LCA2 to LCA10 during construction is considered to be “Negligible”.

Landscape Impacts - Operation Phase

11.7.4 The potential sources of landscape impact during the operation phase would be related to the following visible above-ground structures:

Ÿ Existing administration building;

Ÿ Existing sludge dewatering house;

Ÿ New preliminary treatment units, odour control room and pump house;

Ÿ Plant room above MBR tanks;

Ÿ New sludge digesters, sludge holding tanks and air blower room; and

Ÿ New transformer room, switch room and standby generator room.

11.7.5 During operation, the magnitude of impact to the vegetation within the STW (i.e. LR1) is considered as small. As the upgrading of the STW would be operated within the existing STW site, which the treatment facilities are already exist, no direct impact would be expected on all other landscape resources and landscape character areas located outside of the existing STW site. Therefore the magnitude of impact to all the LRs and LCAs other than the existing site (i.e. LR2 to LR6 and LCA1 to LCA10) during operation is considered to be “Negligible”.

11.7.6 The sensitivity, the magnitude of change before mitigation, impact significant threshold before mitigation, recommended mitigation measures and residual impact significance threshold after mitigation (Day 1 and Year 10) for the LRs and LCAs on landscape impacts are shown in Table 11.5.

Table 11.5: Significance of the Landscape Impacts in the Construction and Operation Phases

Landscape Resources / Landscape Character Areas		Sensitivity (Low, Medium or High)	Magnitude of Change before Mitigation (Negligible, Small, Intermediate or Large)		Impact Significance Threshold before Mitigation (Insubstantial, Slight, Moderate or Substantial)^(3)		Recommended Mitigation Measures^(1)	Residual Impact Significance Threshold after Mitigation (Insubstantial, Slight, Moderate or Substantial)^(2,3)
			Construction	Operation	Construction	Operation		Construction	Operation (Day 1)	Operation (Year 10)
LR1	Vegetation within existing CCSTW	High	Intermediate	Small	Moderate	Moderate	CM-2, CM-3, OM-1, OM-2	Slight	Insubstantial (beneficial as there will be more trees than existing)	Insubstantial (beneficial as there will be more trees than existing)
LR2	Shrubland	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LR3	Young Woodland	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LR4	Coast	High	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LR5	Marine	High	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LR6	Vegetated Slope and Vegetation within Residential Development	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA1	Institutional	Low	Intermediate	Negligible	Moderate	Insubstantial	CM-2, CM-3, OM-1, OM-2	Slight	N/A	N/A
LCA2	Shrubland	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA3	Transportation Corridor	Low	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA4	Medium-rise Residential	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA5	Village	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA6	Hillside	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA7	Industrial	Low	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA8	Marine	High	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA9	Natural Coastal Area	High	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A
LCA10	Artificial Coastal Area	Low	Negligible	Negligible	Insubstantial	Insubstantial	N/A	N/A	N/A	N/A

Notes:

(1) Recommendation on landscape and visual mitigation measures are described in Section 11.8.

(2) Residual impacts are discussed in Section 11.9.

(3) All impacts are adverse and irreversible unless otherwise stated.

Visual Impacts

11.7.7 The visual impacts to the VSRs during construction and operation phases of the Cheung Chau STW are generally due to the sources as described in Section 11.7.1 and 11.7.4.

11.7.8 The magnitude of change for each of the VSRs is shown in Table 11.6.

11.7.9 Based on the “Sensitivity of VSRs” as listed in Table 11.4 and “Magnitude of Change” as listed in Table 11.6, the impact significant threshold before mitigation, recommended mitigation measures and residual impact significance threshold after mitigation (Day 1 and Year 10) for the VSRs are shown in Table 11.7.

Table 11.6: Magnitude of Change of VSRs in the Construction and Operation Phases

VSR	Compatibility of the proposed development with the surrounding landscape	Scale of the development	Reversibility of change	Viewing distance (m)	Potential blockage of view	Duration of Impact		Magnitude of Change BEFORE Mitigation
								(Negligible, Small, Intermediate, Large)
						Construction	Operation	Construction	Operation
VSR1	Low, the view of the site is generally open sea	Small, the development located within the existing Cheung Chau STW site	Irreversible	25 - 600	Slight blockage of view to the mountains behind	Temporary	Permanent	Small	Small
VSR2	Low, the view of the site is generally open sea	Small, the development located within the existing Cheung Chau STW site	Irreversible	50 - 250	Negligible blockage of view due to the high level of the VSRs	Temporary	Permanent	Negligible	Negligible
VSR3	Medium, the view of the site is generally coastal area with developments adjacent	Small, the development located within the existing Cheung Chau STW site	Irreversible	over 350	Negligible blockage of view due to far distant viewing	Temporary	Permanent	Negligible	Negligible
VSR4	Low, the view of the site is generally green landscape	Negligible, only minimal developments within the viewing angles	Irreversible	20	No blockage of view due to negligible developments from the view angle	Temporary	Permanent	Negligible	Negligible
VSR5	Low, the view of the site is generally open sea	Small, the development located within the existing Cheung Chau STW site	Irreversible	130 - 300	Slight blockage of view to the mountains behind	Temporary	Permanent	Small	Small

Table 11.7: Significance of the Visual Impacts in the Construction and Operation Phases

Visual Sensitive Receivers	Sensitivity (Low, Medium, High)	Magnitude of Change before Mitigation (Negligible, Small, Intermediate, Large)		Impact Significance Threshold before Mitigation (Insubstantial, Sight, Moderate, Substantial)		Recommended Mitigation Measures^(1)	Residual Impact Significance Threshold after Mitigation (Insubstantial, Sight, Moderate, Substantial)^(2,3)
		Construction	Operation	Construction	Operation		Construction	Operation (Day 1)	Operation (Year 10)
VSR1	Medium	Small	Small	Slight	Slight	CM-1, CM-4, CM-5, CM-6, OM-1, OM-2	Slight	Slight	Slight
VSR2	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	Insubstantial	Insubstantial	Insubstantial
VSR3	Medium	Negligible	Negligible	Insubstantial	Insubstantial	N/A	Insubstantial	Insubstantial	Insubstantial
VSR4	Low	Negligible	Negligible	Insubstantial	Insubstantial	N/A	Insubstantial	Insubstantial	Insubstantial
VSR5	High	Small	Small	Moderate	Moderate	CM-1, CM-4, CM-5, CM-6, OM-1, OM-2	Slight	Slight	Slight

Notes:

(1) Recommendation on landscape and visual mitigation measures are described in Section 11.8.

(2) Residual impacts are discussed in Section 11.9.

(3) All impacts are adverse and irreversible unless otherwise stated.

11.8 Recommended Mitigation Measures

11.8.1 The proposed mitigation measure for landscape and visual impacts in both the construction and operation phases are listed in Table 11.8 and Table 11.9, respectively. Implementation agents and management/maintenance agents of the proposed mitigation measures are also identified.

11.8.2 The mitigation measures during construction will be implemented from the commencement of the works and shall be applied for the entire duration of the construction period. The mitigation measures during operation will be constructed or built up during the construction stage. Management and maintenance for all mitigation measures will follow ETWB TCW No. 2/2004 Maintenance of Vegetation and Hard Landscape Features.

11.8.3 The existing trees would be preserved as far as possible. Existing trees conditions were recorded by the Tree Survey carried out under “Agreement No. CE 31/2007 (DS) Upgrading of Cheung Chau and Tai O Sewage Collection, Treatment and Disposal Facilities – Investigation” in March and April 2009. There are totally 18 nos. of existing trees in the site of Cheung Chau STW. During the course of preliminary design under the Project, effort had been made to adjust the location, layout and dimensions of treatment facilities in order to avoid affecting to the existing trees. With the updated proposed STW layout developed, 6 nos. of trees are in direct conflict with the proposed STW upgrading works, and are proposed to be transplanted within the area of the STW boundary or to be fell with compensatory planting. The other 12 nos. of trees will be retained. The tree conditions and tree schedule is shown in Appendix 11.1. Preliminary landscape design plan is shown in Appendix 11.2 for reference. However, this preliminary landscape design plan may be subject to change during detailed design stage when updated tree survey data is obtained for the preparation of tree removal application. The technical feasibility of tree transplanting such as machinery, logistic, tree nursery etc. would also be further considered. As a general principle, compensatory planting would be implemented to fully compensate for the tree and vegetation loss if transplanting of trees is not feasible or not preferable. The total number of compensatory tree planted in the project area shall not be less than 1:1 ratios by new trees in terms of quality and quantity, i.e. the total numbers and the aggregated girth size of compensatory trees within the site and off-site should not be less than that of the tree(s) to be felled. The required numbers and locations of compensatory trees would be determined and agreed with Government during the tree removal application process under ETWB TCW 3/2006 - Tree Preservation.

Table 11.8: Proposed Mitigation Measures during Construction Phase

Landscape and Visual Impact Mitigation Measures		Implementation Agent	Management/ Maintenance Agent
CM-1	Visual Screen/Hoarding Decorative hoarding or boundary fence for construction sites shall be considered, and designed to be compatible to the surroundings.	Contractors	Contractors
CM-2	Protection to Existing Trees within Works Areas All existing trees which are not in direct conflict with the proposed works will be retained. The existing trees proposed to be retained shall be properly maintained and protected by means of fencing to prevent vehicular or pedestrian intrusion that may potentially damage tree canopies, trunks and root zones. Detailed tree protection specifications shall be allowed and included in the Contract Specification, which specifying the tree protection requirement, submission and approval system, and tree monitoring system. For trees with high preservation value, individual tree assessments and continuous tree monitoring reports shall be provided by a certified Arborist, Landscape Architect or related professional during construction. All retained trees shall be recorded photographically at the commencement of contract. Root pruning to the retained trees should be prohibited. Retained trees should be well-preserved by setting up a tree protection zone throughout the construction period for protecting the retained trees from damages. To maximize protection to existing trees and ground vegetation, construction contracts may designate “No-intrusion Zone” to various areas within the site boundary with rigid and durable fencing for each individual no-intrusion zone. The contractor should close monitor and restrict the site working staff not to enter the “no-intrusion zone”, even for non-direct construction activities and storage of equipment.	DSD and Contractors	DSD and Contractors
CM-3	Tree Transplanting Existing trees to be affected shall be directly transplanted to the proposed tree receiving sites, or to temporary tree nurseries alternatively. Temporary tree nurseries may be set up for the transplanted tree and proposed trees at an early stage to allow small trees to grow during the construction stage. By the time when planting area becomes available, trees have been mature and required minimal pruning and suffer much less damage during transplanting. The construction programme should also allow sufficient time for root pruning and root ball preparation prior to transplanting, if necessary, and transplanting operations to be carried out in planting season. Tree pruning such as topping, lion tailing would be prohibited as far as possible. Also, frequent keep watering would be necessary for transplanting trees. The proposed tree preservation measures during construction would be carried out and approved by the competent persons.	Contractors	Contractors
CM-4	Construction Light Security floodlight for construction areas shall be controlled, such as equipped with adjustable shield, frosted diffusers and reflective covers, at night to avoid excessive glare to the nearby areas and residents. Other security measures shall also be considered to minimize the visual impacts by construction light.	Contractors	Contractors
CM-5	Dust and Erosion Control for Exposed Soil Excavation works and demolition of existing building blocks shall be well planned with precautions to suppress dust. Exposed soil shall be covered or watered often. Areas that are expected to be left with bare soul for a long period of time after excavation shall be properly covered with suitable protective fabric. Suitable drainage shall be provided around construction sites to avoid discharge of contaminants and sediments into sensitive water-based habitats.	Contractors	Contractors
CM-6	Reinstatement of Works Areas The affected works areas shall be properly reinstated to the satisfaction of relevant government departments.	Contractors	Contractors

Table 11.9: Proposed Mitigation Measures during Operation Phase

Landscape and Visual Impact Mitigation Measures		Implementation Agent	Management/Maintenance Agent
OM-1	Architectural and Landscape Design The appearance of the proposed structures shall be properly designed, including a careful selection of material, colour and texture, so as to fit into the existing suburban, natural to semi-natural surroundings. The aesthetic design of the proposed structures will follow the requirements in the Guidelines on Aesthetic Design of Pumping Station Buildings and submitted to Vetting Committee on Aesthetic Design of Pumping Station Buildings (VCAB) for approval in accordance with DSD TC No. 9/2006, and circulated to ASD for comment in accordance with ETWB TCW No. 8/2005. Sufficient planting shall be considered and provided around the boundary fence of the proposed buildings for screening. Buffer planting will also be considered during the detailed design.	DSD	DSD
OM-2	Establishment Period A 12-month establishment period for the soft landscape works shall be allowed in the main contract for contractor to carry out routine horticultural operations, including watering, pruning, weeding, pest control, replacement of dead plants etc. to ensure healthy establishment of new planting during a 12 month establishment period. This period can also serves as a kind of warranty/guarantee on the quality of the plants supplied and installed by the contractor. Monthly monitoring during the first year of establishment period is recommended.	DSD and Contractors	DSD and Contractors

11.9 Residual Impacts

11.9.1 Before applying any mitigation measures, the landscape and visual impact during construction and operation to the identified LRs, LCAs and VSRs are generally ranged as “Insubstantial”, “Slight” and “Moderate” as shown in Table 11.5 and Table 11.7.

11.9.2 Impact of “Slight” and “Moderate” is considered as non-ideal situations, and mitigation measures are recommended. The potential residual landscape and visual impacts during construction and operation after mitigation are also provided in Table 11.5 and Table 11.7.

11.9.3 By introducing mitigation measures, the residual landscape and visual impact levels will be lowered down to “Slight” and “Insubstantial” during construction stage and operation stage.

11.9.4 Existing and planned setting in four stages (existing condition, proposed development without mitigation, proposed development with mitigation on Day 1 and proposed development with mitigation in Year 10) from VSR 1 to VSR 5 are shown in Figure 11.7 to Figure 11.11 respectively.

11.10 Conclusion

11.10.1 Landscape and visual impact assessment has been carried out for the proposed upgrading of the Cheung Chau STW to be carried out within the boundary of the existing Cheung Chau STW.

11.10.2 The proposed new and upgrading of sewers will mainly be laid underground along the existing carriageway, footpaths and paved tracks. The construction works will be carried out section by section in a local area with a short period of time, in order to reduce the disturbance to the surrounding areas and nearby residents. The works area will be reinstated to its original conditions. Landscape and visual impact during construction and operation stage of the sewers is considered to be negligible.

11.10.3 LRs, LCAs and VSRs are identified within the study area to assess the landscape and visual impacts arising from the proposed upgrading of the Cheung Chau STW. Impact significance and mitigation measures are recommended and discussed. After mitigation, residual landscape and visual impacts are considered to be “Slight” and “Insubstantial”. With reference to the criteria defined in Annex 10 of the EIAO-TM, landscape and visual impacts in the construction and operation phases arising from the proposed works will be considered as acceptable.