1. INTRODUCTION

1.1 Background

1.1.1 An Environmental Impact Assessment (EIA) Study Brief (No. ESB-220/2011) under Section 5(1)(a) of the EIA Ordinance (EIAO) was issued by the Environmental Protection Department (EPD) on 9 March 2011 to the Water Supplies Department (WSD), the Project Proponent to carry out an EIA study for the in-situ reprovisioning of Sha Tin Water Treatment Works (WTW) – South Works (hereinafter referred as the Project). The Project is to reprovision the South Works of the existing Sha Tin WTW which has been operated since 1964 with a proposed output of treatment capacity of 550,000 m³/day.

1.1.2 The major works for the Project include:

· Isolation and demolition of the existing facilities of the South Works in phases comprising clarifiers, filter beds with clearwater tank underneath, filtered water pumping station (South Works), as well as common facilities for both the South Works and the North Works including chemical house, alum saturation tanks, washwater recovery tanks, administration building and the dangerous goods (DGs) store;

· Construction of the new common facilities for both the South Works and the North Works including an Administration Building cum Mainland East Laboratory with visitor facilities, pre-treatment facilities, Water Treatment Works Logistics Centre, switchgears and power supply, South Works Pumping Station and washwater recovery facilities;

· Cut-back of the existing engineered slope located to the west of the existing clarifiers for reprovisioning of chemical house to Water Treatment Works Logistics Centre where Incense Tree (Aquilaria sinensis) as listed under the Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586) was identified;

· Construction of new access roads for both construction and normal operation of the plant;

· Reprovisioning of the South Works to the proposed output of 550,000 m³/day; and

· Provision of all other associated civil, geotechnical, mechanical and electrical works.

1.2 Purpose of this Executive Summary

1.2.1 The principal purpose of this EIA Executive Summary (ES) is to present the summary of covering all the main issues, findings of the assessment, conclusion and recommendations in the EIA report. This ES contains the following information.

· Section 2 presents purpose and nature of the Project.

· Section 3 outlines information over consideration of alternatives.

· Section 4 presents the key findings of environmental impacts.

· Section 5 describes environmental monitoring and audit.

· Section 6 presents the conclusion.

2. PROJECT DESCRIPTION

2.1 Brief Description of the Project

2.1.1 The Sha Tin WTW was first commissioned in 1964. At that time, it comprised the current South Works and the Administration Building with a treatment capacity of 364,000 m³/day. To cope with the rapid increase in the territory’s water demand, the Sha Tin WTW underwent three stages of expansion in 1973, 1976 and 1983 that are collectively called the North Works. The Sha Tin WTW is the largest WTW in Hong Kong with a treatment capacity of 1,227,000 m³/day.

2.1.2 Due to the aging of plant and equipment after more than 40 years of service, the present operation of Sha Tin WTW can only maintain about 1,060,000 m³/day average output. The plant therefore requires major renovation or replacement. In order to maintain water supply to the existing users, the operation of the existing North Works of the Sha Tin WTW would be undisturbed during construction of the Project.

2.1.3 Since the plant was first commissioned in 1964, the required treated water quality requirements have also been raised to meet the latest standards. The existing treated water quality standards as specified by WSD, the authority in Hong Kong, is based on the World Health Organization (WHO)’s Guidelines for Drinking-water Quality 2011, supplemented by additional parameters not included in the Guidelines. Access to safe drinking water is essential to public health. WSD is committed to providing a safe, clean and reliable water supply to customers in Hong Kong. Stringent water treatment combined with comprehensive monitoring control is essential steps in safeguarding public health.

2.1.4 The key objective of the Project is to reprovide the South Works of the existing Sha Tin WTW with a treatment process that can continue to meet the latest treated water quality standards and enable a more reliable water supply to the territory. The main benefits of the Project are to provide a safe and reliable water supply; and improve water supply reliability to the territory.

2.2 Project History

2.2.1 In 2002, WSD completed a Preliminary Project Feasibility Study (PPFS) following the recommendation made in the conceptual planning report for the in-situ reprovisioning of Sha Tin WTW. In 2004, WSD completed the investigation study entitled the in-situ reprovisioning of Sha Tin WTW which involved the development of a preliminary design. In 2010, WSD commissioned to carry out detailed design and construction for the in-situ reprovisioning of Sha Tin WTW – South Works.

2.2.2 Formal public consultation to the Sha Tin District Council was carried out in 2009. Subsequently, two meetings in 2011 were held with representatives from Hin Keng Estate and Sha Tin District Council members. The attendees had no objection to the Project.

2.3 Project Location and Scale

2.3.1 The Project is situated at the existing Sha Tin WTW. The Project location and the major works are shown in Figure 2.1. The site area comprises predominately the developed areas of the existing Sha Tin WTW in about 10 hectares. The setting of Sha Tin WTW is within the natural valley encompassed by mountains from three sides. Woodland is located on these hillsides. Lion Rock Ridgeline to the south is a significant feature. On the east of Sha Tin WTW are the developed residential areas of Hin Keng Estate and road network namely Keng Hau Road and Che Kung Miu Road.

2.4 Designated Projects under the EIAO

2.4.1 The Project is classified as a Designated Project (DP) under item E.2 in Schedule 2 [Part I] of the EIAO. A detailed EIA for approval by the Director of Environmental Protection (DEP) is therefore required. The Schedule 2 DP covered by the EIA report is listed in Table 2.1 below.

Table 2.1 Schedule 2 Designated Project in the EIA Study

Designated Project	EIAO Reference	Remarks
Water Extraction and Water Supply	E.2, Part I, Schedule 2	Water treatment works with a capacity of more than 100,000m³ per day

2.5 Project Need

2.5.1 With over 40 years in service, the aging plant and equipment are approaching the end of their service life. This is compounded by increasing fault occurrences and unavailability of the spare parts caused significant maintenance problems. In addition to this, it is perceived that the treated water from the plant based on a more than 40 years old design would not be able to cope with the possible tightening on the drinking water quality by WHO in the future. Replacement of the existing facilities is therefore the only solution to meet the anticipated future water needs and quality.

2.6 Works Programme and Implementation

2.6.1 The construction works of the Project are anticipated to commence in 2015, with completion of the Project by 2021. A construction programme is presented in Table 2.2 below. The EIA study is based on this programme, using reasonable worst-case scenarios.

Table 2.2 Construction Programme in Tabular Form

Construction Activity	Anticipated Timing
Retaining Wall and New Access Road	October 2015 – November 2016
Water Treatment Works Logistics Centre	August 2016 – July 2019
Demolition of Existing South Works	November 2016 – April 2018
Washwater Equalization Facilities (North Works)	February 2017 – March 2018
Demolition of Existing Chemical House	August 2019 – January 2020
Demolition of existing Washwater Recovery Tanks	April 2018 – June 2018
Administration Building cum Mainland East Laboratory with Visitor Facilities	July 2018 – February 2020
Construction of South Works	May 2018 – January 2021
Demolition of existing Administration Building	May 2020 – October 2020
Stage 2 Granular Media Filters	March 2020 – April 2021
Operation of haul Road	August 2015 – November 2016
Access Road Raving (for Stage 1 Haul Road)	November 2016
Operation of Haul Road	December 2016 – April 2021
Access Road Paving (for Stage 2 Haul Road)	April 2021

3. CONSIDERATION OF ALTERNATIVES

3.1 “Without the Project” Scenario

3.1.1 The Project has been conceived and designed to meet a need. If the Project were not to proceed, this need would not be met as the water treatment facilities would continue to age (i.e. currently > 40 years service and approaching end of service life), and this is likely to result in continued maintenance issues and faults which could ultimately impact the delivery and reliability of water supply. The opportunity to redesign the water treatment process using state-of-the-art treatment technologies to cope with the possible tightening on the drinking water quality by WHO and WSD in the future, would also not be achieved. This would also be compounded by the inability to improve water supply reliability and accommodate the future water demands of the territory.

3.2 “With the Project” Scenario

3.2.1 After completion of the Project, it is expected that the need for providing a reliable water supply and keeping pace with future water demand can be met. Treated water from the reprovisioned South Works will be able to cope with the possible tightening on the drinking water quality by WHO and WSD in the future. In addition, the visitor facilities, presenting illustrations and displays on modern treatment technologies and water conservation, will play a beneficial role in educating the public on water conservation.

3.3 Alternative Reprovisioning Sites

3.3.1 There are extensive raw water supply and treated water delivery systems connected to the plant. Relocating the South Works to another site would require further land acquisition and construction of the associated raw water supply and treated water delivery systems, resulting in a much greater costs and would no doubt increase environmental impacts.

3.3.2 The existing South Works once deteriorated to an irreparable extent would have to be demolished. Reproviding the treatment works in-situ would therefore have the added benefit of no additional requirements of exploiting other brownfield or greenfield sites which would otherwise have other beneficial societal uses, to serve the same purpose. In addition, as there are existing common facilities for both the South Works and the North Works, relocating the South Works to other sites would still require re-construction of the ancillary facilities. The in-situ reprovisioning would enable common facilities to the South Works and the North Works be continued to be shared, thereby resulting in a decreased environmental impact and would be more cost-effective than finding a new site for relocation. A comparison of the major environmental benefits and disbenefits of the in-situ reprovisioning option, and the appraisal, is provided in Table 3.1 below.

Table 3.1 Summary of Environmental Appraisal for In-situ Reprovisioning

Option

Environmental Benefits

Environmental Disbenefits

Appraisal

In-situ Reprovisioning

· Less environmental impact to the already developed site; and

· No major impact on the difficulty of acquiring the land.

· About 0.69ha of secondary woodland to be affected due to space constraints on the existing site.

This option is environmentally more favourable. Considering the size and value of woodland affected, the residual impact is considered to be acceptable with habitat compensation.

3.3.3 The Project has been derived with due consideration of all physical, operational, and other constraints, and has been subject to a comprehensive evaluation of planning, engineering, environmental, and cost considerations. The selected design is considered to be the most feasible and practicable. The proposed layout offers the most efficient and balanced land use arrangement. The refined layout is shown in Figure 3.1.

3.4 Alternative Construction Methods and Sequence of Works

3.4.1 Careful planning and sequence of reprovisioning for the South Works would be required in particular for the construction of WTW Logistics Centre, Administration Building, and washwater equalization tanks for the existing North Works before the area can be demolished to ensure unfettered operation of the existing North Works during that time. The slope stabilisation works at the northern boundary of the works area and the cut-back of the existing engineered slope are proposed to incorporate retaining walls so as to minimise the impact to woodland habitat.

3.4.2 Careful consideration has been made for constructing a new access road at the northern boundary of the works area to separate traffic to the works area and the North Works during the construction phase in order to maintain normal operation of chlorine transportation to the undisturbed Chlorination House.

3.5 Concurrent Projects Having Potential for Cumulative Effects

3.5.1 The following nearby project would undergo construction at the same time:

(i) Shatin to Central Link – Tai Wai to Hung Hom Section (SCL(TAW-HUH))

3.5.2 The cumulative impacts arising from above nearby project operating concurrently have been assessed and are described in the relevant technical section of the EIA report.

4. KEY FINDINGS OF THE ENVIRONMENTAL IMPACTS

4.1 Introduction

4.1.1 The EIA report has provided information on the nature and extent of environmental impacts arising from the demolition, construction and operation of the Project, and the nearby project operating concurrently which they are summarized below. A summary of the key findings for the impacts are illustrated in Table 4.1.

4.2 Air Quality

Construction Phase

4.2.1 The major dusty construction activities include cut-back of the existing engineered slope, site clearance, bore-piling works, excavation works, truck haulage, demolition and wind erosion of open active site. The potential dust impact associated with the proposed construction works would be limited. Reprovisioning of the South Works would also involve construction of new Administration Building cum Mainland East Laboratory, pre-treatment facilities, WTW Logistics Centre, switchgears and power supply, South Works Pumping Station, and washwater recovery facilities. However, these superstructure construction and concreting works are not dusty construction activities and would not cause adverse dust nuisance.

4.2.2 With the small volume of excavated materials to be generated daily and disposed off-site, the potential dust impact at the nearby Air Sensitive Receivers (ASRs) (Refer to Figure 4.1) would not be significant with the effective implementation of good site practices and dust suppression measures. Given the short duration and small scale of the demolition works, the potential dust impact would be minimal with implementation of the proposed mitigation measures.

Operation Phase

4.2.3 The operation of Sha Tin WTW does not involve any air polluting activities, air quality impact is therefore not anticipated during operation phase of the Project.

4.3 Noise

Construction Phase

4.3.1 Major construction works would include cut-back of the existing engineered slope, site clearance, bore-piling works, demolition of the existing South Works of the Sha Tin WTW, construction of superstructures and truck haulage. Representative Noise Sensitive Receivers (NSRs) (Refer to Figure 4.2) to be most likely affected were identified for the assessment. In the unmitigated scenario, exceedances by 1 to 3 dB(A) were predicted at most of the identified NSRs. Mitigation measures would therefore be required to reduce noise levels to the stipulated noise standards.

4.3.2 By implementing the recommended mitigation measures including good site practices, adoption of quieter PME, use of movable noise barriers to alleviate the noise impacts at the identified NSRs, the predicted construction noise levels would be reduced by up to 10 dB(A). The predicted construction noise levels due to the Project at all identified NSRs would comply with the EIAO-TM noise criteria.

Operation Phase

4.3.3 Based on the calculated maximum allowable sound power levels for the new equipments and the estimated sound power levels for the existing equipment, the predicted fixed plant noise levels at the representative NSRs would comply with the day-time, evening time and night time criteria based on the assessment.

4.4 Water Quality

Construction Phase

4.4.1 Water Sensitive Receivers (WSRs) (Refer to Figure 4.3) were identified for the water quality impact assessment. Potential water quality impact associated with land-based construction works for the Project would be generated from construction site run-off and drainage, wastewater from construction activities, and sewage from workforce.

4.4.2 The site practices outlined in ProPECC PN 1/94 “Construction Site Drainage” should be followed to minimise surface run-off and the chance of erosion. Effluent discharged from the construction site should comply with the standards stipulated in the TM-DSS. To minimize the potential water quality impacts from the construction works near any water courses, the practices outlined in ETWB TC (Works) No. 5/2005 “Protection of Natural Streams/rivers from Adverse Impacts arising from Construction Works” should be adopted where applicable. The Waste Disposal Ordinance (Cap 354) and its subsidiary regulations in particular the Waste Disposal (Chemical Waste) (General) Regulation should be observed and complied with for control of chemical wastes. It is recommended that all the sewage generated from the workforce should be properly treated by interim treatment facilities, such as chemical toilets, which are maintained and cleaned by licensed waste collector on a regular basis. All waste generated from the temporary facilities will be collected by the licensed waste collector for proper disposal offsite and will not be discharged to the public sewer.

4.4.3 Deep excavation would be required for construction of water tanks and the associated facilities, where potential land contamination were identified in the CAP, any groundwater pumping out or from dewatering process during excavation works could be potentially contaminated. Prior to the excavation works, the baseline groundwater quality in these potentially contaminated areas should be reviewed with reference to the relevant site investigation data and any additional groundwater quality measurement results. The review results should be submitted to EPD for examination. If the results indicate contamination for the groundwater to be generated from the excavation works, this contaminated groundwater would either be properly treated or properly recharged into the ground in compliance with the requirements of the TM-DSS. No direct discharge of contaminated groundwater would be allowed. Provided that all the mitigation measures and monitoring requirements as recommended are followed properly, no adverse water quality impact would be envisaged.

4.4.4 Provided that all the recommended mitigation measures are properly implemented, no adverse water quality impacts would be expected during the construction phase of the Project. Regular site inspections are recommended to ensure the proposed mitigation measures are properly implemented.

Operation Phase

Washwater Effluent

4.4.5 During operational phase, cleansing of the treatment works components would be required. The washwater would firstly be captured by the washwater equalization tanks, the washwater would then be treated using dissolved air flotation (DAF) clarification at the DAF clarifiers or other high rate sedimentation process and finally flow to the Inlet Works to be blended with raw water. The treatment of sludge generated from the DAF clarification or other high rate sedimentation process is detailed in Section 4.5.4 to Section 4.5.5 below. A flow chart for the treatment of spent washwater is given below in Plate 1. No washwater would be discharged off-site and thus no adverse impacts upon the nearby watercourses arising from the washwater effluent would be anticipated.

Plate 1 Flow Chart for Spent Washwater

Overflow from Treatment Works Components

4.4.6 Possible failure of treatment works components or interruption of the electrical power supply could cause Sha Tin WTW operational failures, which could result in an overflow of water. If uncontrolled, overflow of water would be discharged to the surrounding area and adjacent water courses.

4.4.7 With the full implementation of the recommended mitigation measures for the construction and operation phases of the Project, no residual impacts on water quality are anticipated.

4.5 Waste Management

Construction Phase

4.5.1 Construction and demolition (C&D) materials would be generated from demolition works of the existing facilities of the South Works, construction of the new common facilities for the North and the South Works, the slope excavation works for the reprovision of the South Works and construction works of new access roads for both construction and operation of the plant. The Engineer has estimated the volume of surplus C&D materials to be approximately 242,050 m³ of inert material (i.e. public fill) and approximately 9,980 m³ of non-inert material (i.e. C&D waste). There would be no sediment requiring marine disposal.

4.5.2 The C&D material would be sorted on-site and the inert portion would be stored in different containers, skips or stockpiles to re-use on-site as far as possible to minimise the net amount of C&D material generated from the Project. Surplus excavated material would therefore require to be exported off-site. The potential environmental impacts arising from the handling and disposal of this inert C&D material, such as air and odour emissions, noise and potential hazard, would be negligible. Appropriate measures should be taken to minimise potential adverse impacts from dust during the transportation of C&D material. Non-inert C&D materials generated would be reused and recycled as much as possible before disposal of at landfills.

4.5.3 Other waste materials, including general refuse and chemical waste would also be generated throughout construction. Provided that these identified wastes would be handled, transported and disposed of using the recommended methods and that good site practices would be strictly followed, adverse environmental impacts are not expected.

Operation Phase

4.5.4 Sludge arising from the water treatment process would be the major waste during the operation of the Project. The monthly volumes of thickened sludge generated in the existing Sha Tin WTW was approximately 14,000 m³, and it should be subject to change with different raw water quality. The sludge would be thickened on–site and then transported through the twin sludge transfer pipeline underneath Shing Mun River to the Sha Tin Sewage Treatment Works (STW) for disposal.

4.5.5 The total volume of thickened sludge generated from the existing Sha Tin WTW was approximately 465 m³/day and relates to an average output of about 730 million litres per day (MLD). Taking into account the full capacity of the WTW after completion of the reprovisioning works, with total output of 1,227 MLD, a total volume of thickened sludge would be approximately 782 m³/day. It is expected that the amount of thickened sludge to be generated from the proposed water treatment process would not be significantly different from that produced under the current process. The routing of sludge disposal would also follow the existing approach that thickened sludge is transferred to Sha Tin STW for disposal based on the best available information at the time of writing this EIA report. It is anticipated that the handling and disposal of the sludge generated from the proposed water treatment process would not induce unacceptable impacts compared to the treatment process of the existing WTW.

4.6 Terrestrial Ecology

4.6.1 A literature review and ecological field surveys have been conducted. Ecological surveys were carried out in October 2010 to August 2011 covering both wet and dry seasons. A verification field visit was conducted in September 2014 to check the condition of the habitats within the study area and update the habitat conditions for assessment. The only known area of conservation importance identified within the study area is Lion Rock Country Park situated about 300 m south of the Project site.

4.6.2 Four terrestrial habitat types were identified, namely secondary woodland, plantation, watercourse and developed area (Refer to Figure 4.4 and Figure 4.5). The ecological value of secondary woodland was considered as generally high but the directly affected area at the peripheral of the habitat, which was more shrubby and disturbed, has reduced value; whereas the ecological values of plantation, watercourse and developed areas were considered to be low.

4.6.3 Major ecological impacts would include direct impact on the secondary woodland habitat and the floral species of conservation importance. The impacts to about 0.69 ha of secondary woodland habitat would be compensated by the creation of about 0.23 ha on-site and about 0.29 ha off-site (a total of about 0.52 ha) of woodland habitat within the Sha Tin WTW, at Sha Tin South Freshwater Service Reservoir nearby and northwest of Sha Tin West Service Reservoir respectively. The area of secondary woodland habitat would be reduced by about 0.17ha. Feasible woodland compensation locations have been exhaustively investigated and residual impact is minimised as far as practicable. Considering the size and value of the habitat affected, the residual impact is considered to be insignificant, with the implementation of the recommended habitat compensation.

4.6.4 Concerning the four flora species of conservation importance, prior to the commencement of the works being undertaken, a detailed vegetation survey would be conducted. Transplantation would be recommended as far as possible to minimize the direct impact of these important species. A transplantation proposal would be submitted for approval prior to transplantation.

4.6.5 The level of disturbance during the operation phase would be comparable to the existing condition. No significant adverse impact is therefore expected.

4.7 Landscape and Visual

4.7.1 Based on a preliminary tree survey, approximately 800 existing trees would be affected by the proposed works. Among these 800 trees, approximately 652 trees will be felled due to the Project. None of these are Registered Old and Valuable Trees. There are approximately 21 nos. of Aquilaria sinensis which is protected under Cap. 586 in Hong Kong and 1 no. of Ailanthus fordii under the Forest and Countryside Ordinance (Cap 96). Any affected Aquilaria sinensis and Ailanthus fordii including other trees of conservation importance are proposed to be transplanted where possible. Detailed tree survey and removal application will be submitted in accordance with DEVB TCW No. 10/2013 – Tree Preservation separately. Under the proposed scheme for the Project, opportunities for tree compensation within the project boundary have been fully explored and incorporated in the proposed mitigation measures as much as practicable. Due to limited available space for tree planting within the project boundary, approximately 200 nos. of heavy standard trees and 460 nos. of light standard trees are proposed on-site and off-site at Sha Tin South Freshwater Service Reservoir and Sha Tin West Service Reservoir at Po Fook Shan to compensate for the tree to be felled. It offers a compensation ratio greater than 1:1 (i.e. approximately 660 newly planted trees v.s. approximately 652 felled trees). Approximately 2,300m² of woodland mix planting are proposed on-site whereas about 2,900m² off-site to compensate for the affected woodland habitat.

4.7.2 There would be substantial residual landscape impact on LR1 – Natural Hillside Woodland and moderate residual landscape impact on - LR2 – Man-made Slope Areas, LR3 – Landscape Amenity Area at Shatin WTW, LR4 – Lawn Area and LCA2 – Tai Wai Urban Fringe Landscape Character Areas with the implementation of proposed mitigation measures during construction phase (Refer to Figures 4.6 and 4.7). The residual impact of LR1 would be moderate and LR2, LR3, LR4 and LCA2 would be slight in Day 1 operation phase and reduced to slight and insubstantial in Year 10 of operation phase when the proposed compensatory planting including woodland mix planting becomes mature. Because not all woodland/tree compensation will be provided on-site, some of the woodland/tree planting will be compensated off-site. There would still be some slight residual impact on LR1.

4.7.3 There would be moderate residual visual impact on Visual Sensitive Receivers (VSRs) R1 – Hin Tin Estate, R2 – Hin Keng Estate and Ka Tin Court, R3 – Low Rise Residential along Keng Hau Road: L Louey, Angelaville, The Blossom, Joyville, Jade Villa, Lisa Villa, R4 – Parc Royale, GIC1 – Union Hospital, O1 – Wilson Trail and O2 – Hikers on Amah Rock at Lion Rock Country Park and slight residual impact on VSRs T1 – Travellers on East Rail and T2 – Tai Po Road during the construction phase (Refer to Figure 4.8). The residual impact would be slight in Day 1 of Operation Phase and reduced gradually with the growth of trees and expected that the visual impact is insubstantial in Year 10 of Operation Phase (Refer to Figure 4.9).

4.7.4 Although there is slight residual impact on LR1, as a whole, the residual landscape and visual impacts of the Project is considered acceptable with the implementation of the recommended mitigation measures during construction and operation phases.

4.8 Cultural heritage

4.8.1 Direct impact on three existing graded historic buildings at Hin Tin village and the Ex KCR Beacon Hill Tunnel during construction phase is not anticipated. Considering sufficient buffer distances between the built heritages at Hin Tin village (approximately 270 m) and the proposed works areas, there would be insignificant visual and vibration impact during construction phase.

4.8.2 Four existing staff quarters would be refurbished to be used as construction site office located in close proximity to the west of Ex KCR Beacon Hill Tunnel portal, and the new administration building would also be built to the northwest of the portal. Due to the proposed work design and distance between these buildings and the tunnel portal, vibration impact on the facade wall of portal is considered to be insignificant. As precautionary measure, peak particle velocity (ppv) limit of 7.5mm/s is recommended, including measuring at the facade wall of tunnel portal and inside the tunnel where it is nearest to any construction works within the Works Area.

4.8.3 No historic building or grave is situated within the Project Area, no direct impact is anticipated during the operation. The three graded historic buildings would remain as the existing conditions during the operation phase, as the water treatment facilities will continue to operate in situ. As the facilities have imposed no impact up on these buildings, no impact is anticipated during the operation phase. The most of Ex KCR Beacon Hill Tunnel portal would remain in existing condition, the tunnel will continue to be run through by gas pipeline and as the water treatment facilities will continue to operate in-situ. As the facilities have imposed no impact up on the tunnel, no impact is anticipated during the operation phase.

4.9 Land Contamination

4.9.1 Potentially contaminated land within the Site has been identified in the Contamination Assessment Plan (CAP) through the site appraisal exercise. Twelve potential contamination hotspots for soil and groundwater were identified. A total of 44 boreholes were proposed at the Site as scheduled in the CAP. As all the SI works are proposed underneath the equipment and processing tanks which might cause process interruption and potential contamination of drinking water, it would not be possible to be conducted during the operational period of the Site. Therefore, SI will be conducted upon decommissioning and prior to the commencement of construction works at the potentially contaminated hotspots. In terms of the potential soil and groundwater contamination detected in SI, options of remediation methods proposed will be reviewed and implemented so that contaminants will be removed to achieve the remediation targets. After completion of remediation for any identified contaminated areas, no residual impact in respect of land contamination on the future users is anticipated.

4.10 Hazard to Life

4.10.1 A Hazard Assessment of the risks associated with the transport, storage and use of chlorine at Sha Tin WTW and off-site transport of chlorine within the Consultation Zone has been conducted for the Construction and Operational Phases of the Project. To obtain the total chlorine risks, risks from the on-site Sha Tin WTW chlorine transport, storage and use were combined with the off-site chlorine transport risks.

4.10.2 The Sha Tin WTW Reprovisioning is an improvement project. Due to the introduction of the new treatment technologies, the reprovisioning works will lead to a permanent reduction in chlorine storage and usage at the WTW. As a result, the chlorine-related risks for the surrounding population will be reduced in comparison with current levels.

4.10.3 The assessment results show that for both Construction and Operational Phases, the Individual Risk complies with the Hong Kong Risk Guidelines.

4.10.4 The Societal Risk lies within the As Low As Reasonably Practicable (ALARP) region of the Hong Kong Risk Guideline (HKRG). An ALARP assessment has been carried out to identify feasible mitigation measures and assess the cost effectiveness of each measure in terms of risk reduction achieved and the cost of implementing the measures, a number of recommendations have been made. The residual risks remain in the ALARP region.

4.10.5 Cumulative Individual Risks within the Consultation zone were also presented by combining risks from the on-site transport, storage and use of chlorine, off-site chlorine transport, Beacon Hill North Offtake Station, the 750mm and 500mm gas pipelines that run through the Old Beacon Hill Tunnel, and the explosives transport and use for SCL construction. The cumulative Individual Risk values are low and in the maximum order of 10^-6 per year which complies with the Hong Kong Risk Guidelines.

4.10.6 The Cumulative Societal Risk lies within the “ALARP” region of the Hong Kong Risk Guidelines.

Table 4.1 Summary of the Key Findings for the Impacts

	Construction Phase	Operation Phase
Air Quality
Assessment Scope and Key Criteria	· 500m from the boundary of the project site · Hong Kong Air Quality Objectives - 24-hour average TSP level: 260µg/m³ - Annual average TSP level: 80µg/m³ · Annexes 4 and 12 of the EIAO-TM - Hourly average TSP level: 500µg/m³ · Air Pollution Control (Construction Dust) Regulation	Not anticipated
Representative Sensitive Receivers	ASR-1: The Blossom Phase 4 ASR-2: The L Louey ASR-3: Hin Keng Estate – Hin Yau House ASR-4: Hin Keng Estate – Hin Wan House ASR-5: Hin Keng Estate – Hin Kwai House ASR-6: Sha Tin Heights Tunnel Administration Building
Evaluation of Major Impacts	· Excavation works would be carried out over a reasonable period to minimize the daily excavated volume. With the small volume of excavated materials generated daily and disposed off-site, the potential dust impact at the nearby ASRs would not be significant with the effective implementation of mitigation measures. · Given the short duration (3-18 months) and small scale of the demolition works, the potential dust impact would be minimal with the implementation of dust suppression measures.
Cumulative Impacts	No adverse cumulative impact is anticipated due to minimal scale of the Project comparing to SCL(TAW-HUH) in which no adverse air quality impact upon receivers was predicted.
Key Mitigation Measures	The major dust suppression measures include: · Use of regular watering · Use of frequent watering · Side enclosure and covering · Tarpaulin covering of all dusty vehicle loads · Establishment and use of vehicle wheel and body washing facilities · Provision of not less than 2.4m high hoarding · Imposition of speed controls for vehicles on site haul roads · Routing of vehicles and positioning of construction plant at the maximum possible distance from ASRs · Instigation of an environmental monitoring and auditing program
Residual Impact	No adverse impact

	Construction Phase	Operation Phase
Noise
Assessment Scope and Key Criteria	· 300 m from the boundary of the project site · EIAO-TM daytime construction noise limit - Domestic premises: 75 dB(A) - Educational institutions (during normal teaching periods): 70dB(A) - Educational institutions (during examination periods): 65dB(A) · Annexes 5 and 13 of the EIAO-TM · Noise Control Ordinance (Cap. 400)	· 300 m from the boundary of the project site · IND-TM Acceptable Noise Level - Daytime and Evening: 65 dB(A) - Night: 55dB(A) · NCO and IND-TM
Representative Sensitive Receivers	HK1: The L Louey ( East) HK2: The L Louey (South) HK3: Hin Keng Estate – Hin Yau House (North) HK4 :Hin Keng Estate – Hin Yau House (South) HK5: Hin Keng Estate – Hin Wan House HK6: Hin Keng Estate – Hin Kwai House HK7: C.U.H.K.F.A.A Thomas Cheung School *HK8: Sha Tin WTW Staff Quarters	Receivers same as Construction Phase
Evaluation of Major Impacts	· Unmitigated scenario: exceedances by 1 to 3 dB(A) at some NSRs · Mitigated scenario: full compliance with the noise criteria	Full compliance with the noise criteria
Cumulative Impacts	No overall increase of cumulative noise level due to the Project.	No exceedance
Key Mitigation Measures	· Good site practice · Adoption of quiet PME · Use of movable noise barrier All practicable mitigation measures have been exhaustively investigated and residual impact is minimized as far as possible.	· Choose quieter plant · Include noise levels specification when ordering new plant · Locate fixed plant/louver away from any NSRs · Locate fixed plant in walled plant rooms or in specially designed enclosures; · Locate noisy machines in a basement · Install direct noise mitigation measures · Develop and implement a regularly scheduled plant maintenance programme
Residual Impact	No adverse impact due to the Project itself.	No adverse impact

* The Sha Tin WTW Staff Quarters would be used as site office during the construction of the project. It is only considered as representative noise sensitive receivers during operational phase

	Construction Phase	Operation Phase
Water Quality
Assessment Scope and Key Criteria	· 500m from the boundary of the project site · Water Quality Objectives for the Tolo Harbour and Channel Water Control Zone · Annexes 6 and 14 of the EIAO-TM	Scope and criteria same as Construction Phase
Representative Sensitive Receivers	Two natural streams/nullah flow along the Project site boundary with low ecological value - one located to the northwest of the Project boundary - one named Tin Sum Nullah located along the southeast of the Project boundary	Receivers same as Construction Phase
Evaluation of Major Impacts	· Minimal impacts from wastewater generated and water pollution caused by land-based construction activities · Unacceptable impacts not expected from construction site run-off and drainage · Impacts could be mitigated for accidental spillage of engine oil and lubricants when in use and storage · Significant impact not expected for sewage effluent from construction workforce with provision of proper interim sewage treatment facilities, such as chemical toilets · Any groundwater pumping out or from dewatering process during deep excavation works could be potentially contaminated. No direct discharge of contaminated groundwater would be allowed · No adverse impact envisaged for potential contaminated groundwater if any during deep excavation with mitigation measures put in place and monitoring requirements followed properly	· No adverse impact from the washwater effluent and no washwater to be discharged off-site · No adverse impact for overflow from treatment works components and avoidance of overflow discharge by provision of standby units and dual power supply
Cumulative Impacts	No cumulative impact expected provided that all recommended mitigation measures are implemented properly	Not anticipated
Key Mitigation Measures	· Site practices outlined in ProPECC PN 1/94 “Construction Site Drainage” to follow so as to minimise surface run-off and the chance of erosion · Waste Disposal (Chemical Waste) (General) Regulation to comply with for controlling chemical wastes · Interim treatment facilities, such as chemical toilets, should be properly maintained to avoid adverse impact upon the nearby water environment · Practices outlined in ETWB TC (Works) No. 5/2005 “Protection of Natural Streams/Rivers from Adverse Impacts Arising from Construction Works” to adopt · Contaminated groundwater, if any, should either be properly treated or recharged into the ground in compliance with the requirements of the TM-DSS	· Provision of standby treatment facilities and dual power supply to prevent occurrence of overflow
Residual Impact	No adverse impact	No adverse impact

	Construction Phase	Operation Phase
Waste Management
Assessment Scope and Key Criteria	· Areas within the boundary of the project site · Annexes 7 and 15 of the EIAO-TM · Waste Disposal Ordinance (Cap. 354)	Scope and criteria same as Construction Phase
Representative Sensitive Receivers	Sha Tin WTW	Receiver same as Construction Phase
Evaluation of Major Impacts	· The Engineer has estimated the volume of surplus C&D materials to be approximately 242,050 m3 of inert material (i.e. public fill) and 9,980 m3 of non-inert material. No sediment requiring marine disposal · Building demolition may generate possible asbestos waste · Quantity of chemical waste would be small and in the order of a few cubic metres per month · It is also estimated that about 128.7 kg per day of general refuse would be generated by the construction workers	· It is estimated that the total volume of thickened sludge after reprovisioning would be approximately 782 m3/day. · Existing approach for thickened sludge transport to Sha Tin STW for disposal after reprovisioning would remain unchanged · No unacceptable impact for sludge handling and disposal from the proposed treatment process comparing to the existing one · No adverse or minimal impact for chemical waste, general refuse
Cumulative Impacts	No adverse impact	Not anticipated
Key Mitigation Measures	· C&D materials would be sorted on-site and the inert portion would be stored in different containers, skips or stockpiles to re-use. Surplus excavated material would therefore be exported off-site · The Project Proponent should conduct an asbestos investigation prior to building structure demolition. All storage of asbestos waste should be carried out properly in a secure place isolated from other substance and bear warning panels to alert people of the presence of asbestos waste · Amount of chemical waste generated would be quantified in the site waste management plan to be prepared by the Contractor	· Chemical waste store in compatible containers in designated areas on site · Chemical waste to be collected and recycled by licensed collectors · Provision of on-site general refuse collection points together with recycling bins · General refuse to be collected by licensed collectors
Residual Impact	No adverse impact	No adverse impact

	Construction Phase	Operation Phase
Ecology
Assessment Scope and Key Criteria	· 500m from the boundary of the project site · Annex 16 of the EIAO-TM · Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586) · EIAO Guidance Note No. 6/2010, 7/2010, 10/2010, DEVB TCW No. 10/2013	No significant adverse impact as the level of disturbance would be comparable to the existing condition
Representative Sensitive Receivers	· Secondary woodland habitat occupies about half of the study area · Small, scattered patches of plantation habitat within the study area · Watercourse 1, north-west of the Sha Tin WTW. Upstream is natural, downstream is man-made and channelized · Watercourse 2, south-east of the Sha Tin WTW. Man-made and channelized · Watercourse 3, south-east of the Sha Tin WTW. Channelized · Developed area including the Sha Tin WTW, residential areas and transportation infrastructure
Evaluation of Major Impacts	· Approximately 9.04 ha of habitats would be directly impacted. Of which, about 90% of the affected habitats are within developed area and plantation of low ecological value. These habitats are subjected to frequent human disturbance and therefore direct impact is considered to be low. · Approximately 0.69 ha of secondary woodland affected permanently with high ecological value due to cutting back of the existing engineered slope for accommodation of WTW Logistics Centre. Direct impact is considered to be moderate as the affected woodland portion is small in size and located at the woodland/developed area edge · Four flora species of conservation importance (Incense Tree, Ailanthus, Lamb of Tartary, and Hong Kong Eagle’s Claw) would be directly affected
Cumulative Impacts	Potential cumulative impact is associated with disturbance of secondary woodland and, plantation habitat arising from the SCL’s Hin Keng tunnel portal work sites. Cumulative increase in disturbance is considered minor and acceptable
Key Mitigation Measures	Measures to Avoid/Minimize Impact to Woodland · By retaining wall instead of soil nails for slope stabilization work adjacent to the proposed access road at the northern boundary of works area to reduce the amount of vegetation removal and minimize the footprint of the slope at the woodland habitat. · Retaining wall behind the future WTW Logistics Centre has been adopted under the current design to minimize impact to woodland. Measures to Avoid/Minimize Impact to Flora Species of Conservation Importance · Four flora species of conservation importance include Incense Tree, Ailanthus, Lamb of Tartary and Hong Kong Eagle’s Claw · Prior to the construction, a detailed vegetation survey would be conducted to confirm its location and health condition · Transplantation would be recommended as far as possible to minimize the direct impact and a transplantation proposal with location plan, details of the transplantation methodologies and programme along with post-transplantation monitoring would be submitted for approval prior to transplantation Woodland Compensation · About 0.23 ha on-site woodland compensation considering the site constraint of limited space · Approximately 0.29 ha off-site woodland compensation at Sha Tin South Freshwater Service Reservoir nearby and northwest of Sha Tin West Service Reservoir. · Woodland Compensation Plan would be submitted for approval prior to commencement of works
Residual Impact	Considering the size and value of the woodland habitat affected, the residual impact is considered to be insignificant, with the implementation of the recommended habitat compensation.

	Construction Phase		Operation Phase
Landscape and Visual
Assessment Scope and Key Criteria	· 500m from the boundary of the project site · Annexes 10 and 18 of the EIAO-TM		Scope and criteria same as Construction Phase
Representative Sensitive Receivers	Landscape Resources LR1 - Natural Hillside Woodland LR2 - Man-made Slope Areas LR3 - Landscape Amenity Area at Shatin WTW LR4 - Lawn Area LR5 - Landscape Areas at Hin Keng Estate LR6 - Hin Tin Playground and Football field LR7 - Roadside Planting along Che Kung Mu Rd LR8 - Walking Trail LR9 - Watercourse Landscape Character Areas (LCA) LCA1 - Tai Wai Urban Residential LCA LCA2 - Tai Wai Urban Fringe LCA LCA3 - Tai Wai Urban Upland and Hillside LCA	Visual Sensitive Receivers R1 - Hin Tin Estate R2 - Hin Keng Estate and Ka Tin Court R3 - Low Rise Residential along Keng Hau Road: L Louey, Angelaville, The Blossom, Joyville, Jade Villa, Lisa Villa R4 - Parc Royale GIC1 - Union Hospital O1 - Wilson Trail O2 - Hikers on Amah Rock at Lion Rock Country Park T1 - Travellers on East Rail T2 - Tai Po Road	Receivers same as Construction Phase
Evaluation of Major Impacts	· Approximately 800 existing trees would be affected. Among these 800 trees, approximately 652 trees will be felled due to the Project. About 21 nos. of Aquilaria sinensis which is protected under Cap. 586 in Hong Kong and 1 no. of Ailanthus fordii under the Forest and Countryside Ordinance.		· All permanent works are considered irreversible · No potential blockage of view
Cumulative Impacts	· No insurmountable cumulative impact with the implementation of mitigation measures		Not anticipated
Key Mitigation Measures	· Approximately 200 nos. of heavy standard trees and 460 nos. of light standard trees on-site and off-site to compensate for the tree to be felled. · It offers a compensation ratio greater than 1:1 (i.e. approximately 660 newly planted trees v.s. approximately 652 felled trees). · Approximately 2,300m2 of woodland mix planting on-site whereas about 2,900m2 off-site to compensate for the affected woodland habitat.		· Buffer tree and shrub planting to screen the proposed structures · Green roof to enhance landscape quality
Residual Impact	· Substantial residual landscape impact on LR1 and moderate residual landscape impact on LR2, LR3, LR4 and LCA2 with the implementation of proposed mitigation measures · Moderate residual visual impact on R1, R2, R3, R4, GIC1, O1 and O2 and slight residual impact on T1 and T2		· Moderate on LR1 and slight on LR2, LR3, LR4 and LCA2 in Day 1 and reduce to slight and insubstantial in Year 10 when the proposed trees become mature for residual landscape impact · Slight in Day 1 and reduce to insubstantial in Year 10 for residual visual impact

	Construction Phase	Operation Phase
Cultural Heritage
Assessment Scope and Key Criteria	· 300m from the boundary of the project site · Annexes 10 and 19 of the EIAO-TM · Antiquities and Monuments Ordinance (Cap. 53)	Not anticipated
Representative Sensitive Receivers	Graded Historical Buildings · BH01 - Yeung Ancestral Hall, No. 7 Hin Tin, Shatin (Grade 3) · BH02 - Law Ancestral Hall, No. 8 Hin Tin, Shatin (Grade 3) · BH03 - So Ancestral Hall, No. 9 Hin Tin, Shatin (Grade 3) Government Historic Site · BH04 - Ex Kowloon-Canton Railway Beacon Hill Tunnel
Evaluation of Major Impacts	· Insignificant indirect vibration impact due to drilling activities on the three graded historical buildings situated at approximately 270m from the works area · No significant vibration impact for the Ex KCR Beacon Hill Tunnel located in close proximity to the refurbishment works for four existing staff quarters as construction site office · Ground-borne vibration not anticipated to be significant for the tunnel portal given a consideration distance (about 120m in plan) from the possible piling and drilling activities where new administration building would take place
Cumulative Impacts	Not anticipated
Key Mitigation Measures	· As a precautionary measure, a peak particle velocity (ppv) limit of 7.5mm/s is recommended to measure at the facade wall of tunnel portal and inside the tunnel, the closest to the works area during piling and drilling works
Residual Impact	Residual impact for the Ex KCR Beacon Hill Tunnel is considered to be acceptable with proper implementation of mitigation measures

	Construction Phase	Operation Phase
Land Contamination
Assessment Scope and Key Criteria	· Areas within the boundary of the project site · Section 3 of Annex 19 of the EIAO-TM · Practice Guide for Investigation and Remediation of Contaminated Land	Not anticipated
Representative Sensitive Receivers	Onsite construction workers
Evaluation of Major Impacts	· A total of 44 sampling locations proposed at the potentially contaminated hotspots for the SI works upon decommissioning and prior to the commencement of construction works
Cumulative Impacts	· No cumulative impact is anticipated
Key Mitigation Measures	· Based on SI findings, if contamination found, appropriate remediation methods should be investigated · For any contamination found, in-situ remediation measures and possible recycling and reuse of remediated materials should be considered as the preferred remediation option whereas ex-situ remediation the second
Residual Impact	No adverse impact after completion of remediation for any identified contaminated areas

	Construction Phase	Operation Phase
Hazard to Life
Assessment Scope and Key Criteria	· Consultation Zone of Sha Tin WTW and other areas within hazard range of the potential chlorine releases at Sha Tin WTW and along the off-site chlorine transport route. · Annex 4 of the EIAO-TM	· Scope and criteria same as Construction Phase
Representative Sensitive Receivers	· All population within the Consultation Zone and within hazard range of the potential chlorine releases at Sha Tin WTW and along the off-site chlorine transport route.	· All population within the Consultation Zone and within hazard range of the potential chlorine releases at Sha Tin WTW and along the off-site chlorine transport route.
Evaluation of Major Impacts	· Individual Risk complies with the Hong Kong Risk Guidelines. · Societal Risk associated with the on-site transport, storage and handling of chlorine at Sha Tin WTW and off-site transport of chlorine within the Consultation Zone, expressed in the form of FN curves, lies within the “ALARP” region of the Hong Kong Risk Guidelines	· Individual Risk complies with the Hong Kong Risk Guidelines · Similar to Construction Phase Societal Risk lies within the “ALARP” region of the Hong Kong Risk Guidelines
Cumulative Impacts	· Cumulative Individual Risk within the Consultation Zone, combining risks from the on-site transport, storage and use of chlorine, off-site chlorine transport, Beacon Hill North Offtake Station, the 750mm and 500mm gas pipelines that run through the Old Beacon Hill Tunnel, and the explosives transport and use for SCL construction have been found in the maximum order of 10-6 per year which complies with the Hong Kong Risk Guidelines. · The Cumulative Societal Risk lies within the “ALARP” region of the Hong Kong Risk Guidelines.	· Cumulative Individual Risk within the Consultation Zone, combining risks from the on-site transport, storage and use of chlorine, off-site chlorine transport, Beacon Hill North Offtake Station, the 750mm and 500mm gas pipelines that run through the Old Beacon Hill Tunnel, and the explosives transport and use for SCL construction have been found in the maximum order of 10-6 per year which complies with the Hong Kong Risk Guidelines. · The Cumulative Societal Risk lies within the “ALARP” region of the Hong Kong Risk Guidelines.
Key Mitigation Measures	· A number of mitigation and good practice measures were considered and recommended to minimise the chlorine risks during Construction Phase. · A number of mitigation measures, mostly related to the chlorine truck design have also been recommended for the off-site chlorine transport.	· No risk mitigation measures for on-site operations were found to be practicable for Sha Tin WTW. · A number of mitigation measures, mostly related to the chlorine truck design have been recommended for the off-site chlorine transport
Residual Impact	· The residual risks remain in the ALARP region · The Sha Tin WTW Reprovisioning is an improvement project. As a result, the chlorine-related risks for the surrounding population will be reduced in comparison with current levels.	· The residual risks remain in the ALARP region · The Sha Tin WTW Reprovisioning is an improvement project. Due to the introduction of the new treatment technologies, the reprovisioning works will lead to a permanent reduction in chlorine storage and usage at the WTW. As a result, the chlorine-related risks for the surrounding population will be reduced in comparison with current levels.

5. ENVIRONMENTAL MONITORING AND AUDIT

5.1 An environmental monitoring and audit (EM&A) programme was recommended for dust and noise during construction phase. Site inspection/audit was also recommended to check the implementation of the water quality, waste management, ecology, landscape and visual, cultural heritage, land contamination and hazard to life mitigation measures during the construction phase. A summary of the EM&A requirements by each of the environmental parameters is presented in Table 5.1 below.

Table 5.1 Summary of EM&A Requirements

	Prior to Construction	Construction Phase	Operation Phase
Air Quality	O	ü	O
Noise	O	ü	O
Water Quality	O	ü	O
Waste	O	ü	O
Ecology	O	ü	O
Landscape and Visual	O	ü	O
Cultural Heritage	O	ü	O
Land Contamination	ü	O	O
Hazard to Life	O	ü	O

Air Quality

5.2 Environmental monitoring and audit for potential dust impacts should be conducted during the construction phase of the Project so as to check compliance with legislative requirements.

Noise

5.3 An Environmental Monitoring and Audit programme is recommended to be established according to the predicted occurrence of noisy activities. The recommended mitigation measures should be implemented during construction stage.

Water Quality

5.4 Minimisation of water quality deterioration from land-based construction activities could be achieved through implementing adequate mitigation measures. To ensure no adverse water quality impact to the nearby water courses due to the discharge of surface runoff and drainage from the works areas, water quality monitoring of the two water courses along the Project boundary is recommended during construction stage. Operation phase water quality monitoring is considered not necessary.

Waste Management

5.5 It will be the contractor’s responsibility to ensure that any wastes produced during the construction of the Project are handled, stored and disposed of in accordance with good waste management practices and relevant regulations and other legislative requirements.

Terrestrial Ecology

5.6 Implementation of the recommended mitigation measures would be regularly audited.

Landscape and Visual

5.7 Implementation of the recommended mitigation measures would be regularly audited.

Cultural Heritage

5.8 Given the considerable separation distance (approximately 270m) between the three graded historic buildings at Hin Tin village and the Works Area, there would be neither adverse vibration nor visual impacts on the Hin Tin village built heritages, and thus no specific EM&A requirements would be required.

5.9 Given that distance between the Ex KCR Beacon Hill Tunnel and the proposed new administration building in about 120m, vibration impact is anticipated to be insignificant. However, as a precautionary measure, a ppv limit of 7.5mm/s is recommended, including measuring the façade wall of tunnel portal and inside the tunnel where it is closest to any construction works during the piling and drilling works. Measurements should be made by properly calibrated device and under the supervision of the Registered Structural Engineers (RSE) or his representatives.

Land Contamination

5.10 After SI, CAR and if contamination is found, RAP should be prepared and submitted to EPD for endorsement. A RR should be prepared and submitted to EPD to demonstrate that the decontamination work is adequate and is carried out in accordance with the endorsed CAR and RAP. No construction works should be carried out prior to the completion of remediation.

Hazard to Life

5.11 Implementation of the recommended mitigation measures would be regularly audited. No specific Environmental Monitoring would be required.

6. CONCLUSION

6.1 The EIA Study has concluded that the Project would comply with all environmental legislation and standards, with no adverse residual impacts, after the implementation of the recommended mitigation measures during the construction and operation phases. An environmental monitoring and audit programme has been recommended to monitor the implementation of the mitigation measures and to ensure compliance with environmental standards.

6.2 Overall, the EIA study for the In-situ Reprovisioning of Sha Tin WTW (South Works) has predicted that the Project, with the implementation of the mitigation measures, would be environmentally acceptable with no adverse residual impacts on the population and environmentally sensitive resources. Table 6.1 below summarises the environmental outcomes/benefits that have accrued from the environmental considerations and analysis during the EIA process and the implementation of environmental control measures of the Project.

Table 6.1 Summary of Key Environmental Outcomes and Benefits

The Project Need	· aging of plant and equipment after more than 40 years of service requiring major renovation or replacement; and · reprovision of the South Works of the existing Sha Tin WTW with a treatment process that can continue to meet the latest treated water quality standards and future water demands.
Environmental/Social Benefits of the Project	· provision of a safe and reliable water supply; · Improvement in water supply reliability to the territory; · development of environmentally sustainable design by applying low-carbon concept; · Provision of visitor facilities to the public on modern water treatment technologies and water conservation.
Environmentally Friendly Design and Benefit	· In-situ reprovisioning of the WTW promotes re-use of land, thereby minimising the environmental impacts and costs of developing a new site; · About 90% of the works area is situated within the existing Sha Tin WTW is of low ecological value. The impact to natural habitat is minimized; · Impacts to ecological sensitive areas have been minimized through the design process (e.g. use of retaining wall instead of soil nails); · The adoption of new treatment processes will reduce the use of chlorine, which presents a significant risk to adjacent communities; · Engineering design for fixed plant complies with the day-time, evening time and night time noise criteria; · Lighting/glare control; · Green roof, sensitive landscaping, other sustainability features. · Due to the introduction of the new treatment technologies, the reprovisioning works will lead to a permanent reduction in chlorine storage and usage at the WTW. As a result, the chlorine-related risks for the surrounding population will be reduced in comparison with current levels.
Air Quality	Potential air quality impacts from the construction works of the Project would mainly be related to construction dust from excavation, materials handling, spoil removal, demolition and wind erosion. In view of the nature of works, adverse dust impact at the ASRs would not be expected from the Project. Nevertheless, appropriate dust suppression measures as stipulated in the Air Pollution Control (Construction Dust) Regulation should be implemented to minimize any potential dust impact.
Noise Impact	Construction Noise This assessment has presented the construction noise impacts of the Project during normal daytime working hours. The predicted unmitigated noise levels at representative NSRs would range from 46 to 78 dB(A). With the adoption of quiet PME and use of movable noise barrier, the noise levels due to the Project itself at all representative NSRs would comply with the EIAO-TM criteria. The overall increase of cumulative noise level and adverse residual impact, due to the Project itself, are not anticipated. Fixed Plant Noise The noise impact associated with the operation of the Project has been assessed. The predicted fixed plant noise levels at the representative NSRs would be expected to comply with the day-time, evening time and night time criteria based on the assessment using a set of specified maximum SWLs for the newly proposed fixed plant. If there is any change in engineering design information during detailed design stage or fitting-out stage, the fixed source noise design should be reviewed by the Engineer/Contractor to ensure that both the NCO and EIAO-TM criteria at NSR can be met in the future.
Water Quality	Potential water quality impact associated with land-based construction works for the Project would be generated from site run-off, wastewater from construction activities, and sewage from workforce. Provided that all the recommended mitigation measures are properly implemented, no adverse water quality impacts would be expected during the construction phase of the Project. Water quality monitoring of the two water courses along the Project boundary is recommended during site clearance and foundation works to ensure no adverse water quality impacts to these water courses. Regular site inspection is also recommended to ensure the recommended mitigation measures are properly implemented. During operation phase of the Project, major sources of water quality impact would be washwater effluent and overflow from treatment works components. Proper mitigation measures will be implemented to avoid discharge of washwater effluent and overflow into the nearby water environment and hence no adverse water quality would be expected.
Waste Management	Waste types generated by the construction activities are likely to include inert and non-inert C&D materials from demolition works of existing facilities of the South Works, construction works of new facilities for the South Works and common facilities for the North and the South Works, slope excavation works and construction works of new access roads, general refuse from the workforce and chemical wastes from the maintenance of construction vehicles and equipment. Provided that these identified wastes would be handled, transported and disposed of using the recommended methods and that good site practices would be strictly followed, adverse environmental impacts are not expected. The waste management assessment has recommended good waste management practices to ensure that adverse environmental impacts are prevented. The assessment concluded that no unacceptable environmental impacts would result from the storage, handling, collection, transport and disposal of wastes arising from the construction and operation of the project.
Terrestrial Ecology	A literature review and ecological field surveys have been conducted. Four habitat types were identified within the study area including secondary woodland, plantation, watercourse and developed area. The secondary woodland habitat is considered to have high ecological value. The other habitat was regarded as of low value. Six flora and 30 fauna species of conservation importance were recorded from the study area during surveys. Major ecological impacts would include direct impact on the secondary woodland habitat and the floral species of conservation importance. The impacts to about 0.69 ha of secondary woodland habitat would be compensated by the creation of about 0.23 ha on-site of woodland habitat within the Sha Tin WTW and about 0.29 ha off-site of woodland habitat at Sha Tin South Freshwater Service Reservoir nearby and northwest of Sha Tin West Service Reservoir (a total of about 0.52 ha). The area of secondary woodland habitat would be reduced by about 0.17ha. Feasible woodland compensation locations have been exhaustively investigated and residual impact is minimised as far as practicable. Considering the size and value of the habitat affected, the residual impact is considered to be insignificant, with the implementation of the recommended habitat compensation. Four flora species of conservation importance (Incense Tree, Ailanthus, Lamb of Tartary, and Hong Kong Eagle’s Claw) would be directly affected by the Project. Detailed vegetation surveys should be conducted to identify the affected individuals within the proposed works area. Transplantation is recommended as far as possible to minimize the direct impact of these important species. The implementation of a mitigation strategy for Short-nosed Fruit Bat will avoid impacts to this species, thereby resulting in no adverse impact. Indirect impacts during the construction phase would comprise noise and human disturbance, construction dust, and construction site runoff. With proper implementation of good site practices and noise mitigation measures, no significant adverse ecological impact is anticipated. The level of disturbance during the operation phase would be comparable to the existing condition. No significant adverse impact is therefore expected. With the implementation of the recommended mitigation measures, no unacceptable residual indirect impact due to the construction and operation of the proposed Project would be expected. The implementation of mitigation measures would be subject to regular audit as part of the EM&A programme.
Landscape and Visual	The proposed works of the Project at Sha Tin WTW would inevitably result in some landscape and visual impacts during the construction and operation phases. These impacts have been minimized through careful consideration of alternatives, minimization of works areas, incorporation of aesthetic external designs and landscape treatments of proposed structures. The proposed works will be mainly located within the existing Sha Tin WTW Compound under the Other Specified Uses (OU) of the Approved Sha Tin Outline Zoning Plan No. S/ST/30. It is considered that the proposed Project is permitted development under the OZP and would fit in with the current and future planning settings and would not be in conflict with the statutory town plan. Based on a preliminary tree survey, approximately 800 existing trees will be affected by the proposed works. Among these 800 trees, approximately 652 trees will be felled due to the Project. None of these are Registered Old and Valuable Trees. There are approximately 21 nos. of Aquilaria sinensis which is protected under Cap. 586 in Hong Kong and 1 no. of Ailanthus fordii under the Forest and Countryside Ordinance (Cap 96). Any affected Aquilaria sinensis and Ailanthus fordii including other trees of conservation importance are proposed to be transplanted where possible. Detailed tree survey and removal application will be submitted in accordance with DEVB TCW No. 10/2013 - Tree Preservation separately. Under the proposed scheme for the Project, opportunities for tree compensation within the project boundary have been fully explored and incorporated in the proposed mitigation measures as much as practicable. Due to limited available space for tree planting within the project boundary, approximately 200 nos. of heavy standard trees and 460 nos. of light standard trees are proposed on-site and off-site at Sha Tin South Freshwater Service Reservoir and Sha Tin West Service Reservoir at Po Fook Shan to compensate for the tree to be felled. It offers a compensation ratio greater than 1:1 (i.e. approximately 660 newly planted trees v.s. approximately 652 felled trees). Approximately 2,300m² of woodland mix planting are proposed on-site whereas about 2,900m² off-site to compensate for the affected woodland habitat. There would be substantial residual landscape impact on LR1 and moderate residual landscape impact on LR2, LR3, LR4 and LCA2 with the implementation of proposed mitigation measures during construction phase. The residual impact of LR1 would be moderate and LR2, LR3, LR4 and LCA2 would be slight in Day 1 operation phase and reduced to slight and insubstantial in Year 10 of operation phase when the proposed compensatory planting including woodland mix planting becomes mature. Because not all woodland/tree compensation will be provided on-site, some of the woodland/tree planting will be compensated off-site. There would still be some slight residual impact on LR1. There would be moderate residual visual impact on VSRs R1, R2, R3, R4, GIC1, O1 and O2 and slight residual impact on VSRs T1 and T2 during the construction phase. The residual impact would be slight in Day 1 of Operation Phase and reduced to insubstantial in Year 10 of Operation Phase. Although there is slight residual impact on LR1, as a whole, it is considered that the residual landscape and visual impacts of the proposed project is considered acceptable with mitigation measures implemented during construction and operation phases.
Cultural Heritage	Cultural heritage resources within the study area have been identified and reviewed through site surveys and literature review. No archaeological potential is present within the study area. Therefore no impact to archaeology is anticipated. Direct impact on three existing graded historic buildings at Hin Tin village and the Ex KCR Beacon Hill Tunnel during construction phase is not anticipated. Considering sufficient buffer distances between the built heritages at Hin Tin village (approximately 270 m) and the proposed works areas, there would be insignificant visual and vibration impact during construction and operation phases. Four existing staff quarters would be refurbished to be used as construction site office located in close proximity to the west of Ex KCR Beacon Hill Tunnel portal, and the proposed Administration Building cum Mainland East Laboratory would also be built at about 120 m to the northwest of the portal. Due to the proposed work design and distance between these buildings and the tunnel portal, vibration impact on the facade wall of portal is considered to be insignificant. As precautionary measure, ppv limit of 7.5mm/s is recommended, including measuring at the facade wall of tunnel portal and inside the tunnel where it is nearest to any construction works within the Works Area. In conclusion, the construction and operation of the Project would not cause unacceptable impacts on cultural heritage resources, with implementation of the recommended mitigation measures.
Land Contamination	This assessment has examined the potential contaminating land uses within the Project site. It also covers potential impacts of the contamination on future use. The assessment involved site appraisal and preparation of CAP. Site investigation will be carried out at the decommission stage of the Project site due to site access and sensitive nature of the water works. Based on the findings in the site investigation, if any contamination is found, appropriate remediation measures shall be identified and carried out before construction commences, so as to clean up the Project site to the relevant Risk-based Remediation Goals (RBRGs). With the remediation and mitigation measures in place, the potential land contamination impacts to the sensitive receptors and future use as water treatment facilities are thus not considered to be insurmountable. As a precaution, mitigation measures are proposed for the excavation of soil, treatment of soil and general environmental, health and safety on site during the construction stage.
Hazard to Life	A Hazard Assessment of the risks associated with the transport, storage and use of chlorine at Sha Tin WTW and off-site transport of chlorine within the Consultation Zone has been conducted for the Construction and Operational Phases of the Project. To obtain the total chlorine risks, risks from the on-site Sha Tin WTW chlorine transport, storage and use were combined with the off-site chlorine transport risks. The Sha Tin WTW Reprovisioning is an improvement project. Due to the introduction of the new treatment technologies, the reprovisioning works will lead to a permanent reduction in chlorine storage and usage at the WTW. As a result, the chlorine-related risks for the surrounding population will be reduced in comparison with current levels. The assessment results show that for both Construction and Operational Phases, the Individual Risk complies with the Hong Kong Risk Guidelines. The Societal Risk lies within the As Low As Reasonably Practicable (ALARP) region of the Hong Kong Risk Guideline (HKRG). An ALARP assessment has been carried out to identify feasible mitigation measures and assess the cost effectiveness of each measure in terms of risk reduction achieved and the cost of implementing the measures, a number of recommendations have been made. The residual risks remain in the ALARP region. Cumulative Individual Risks within the Consultation zone were also presented by combining risks from the on-site transport, storage and use of chlorine, off-site chlorine transport, Beacon Hill North Offtake Station, the 750mm and 500mm gas pipelines that run through the Old Beacon Hill Tunnel, and the explosives transport and use for SCL construction. The cumulative Individual Risk values are low and in the maximum order of 10^-6 per year which complies with the Hong Kong Risk Guidelines. The Cumulative Societal Risk lies within the “ALARP” region of the Hong Kong Risk Guidelines.