1                     INTRODUCTION

Project Background

1.1               The Harbour Area Treatment Scheme (HATS, formerly known as Strategic Sewage Disposal Scheme) is to improve water quality in Victoria Harbour by intercepting and treating sewage from developments on both sides of the harbour.  The HATS comprises two stages: 1 and 2, as illustrated diagrammatically in Exhibit 1.1.

Exhibit 1.1        Overall HATS Schematic Layout

 

1.2               Stage 1 involved the construction of a chemically enhanced primary treatment (CEPT) works at Stonecutters Island, building of a deep tunnel system to convey sewage from the Kowloon Peninsula, Tseung Kwan O, Kwai Tsing, and Hong Kong Island East to the Stonecutters Island Sewage Treatment Works (SCISTW), and the construction of an effluent outfall into the western harbour.  HATS Stage 1 was completed and commissioned in December 2001.  Since then, water quality of the harbour has generally improved due to interception of sewage from the Stage 1 catchment.  This also has prevented about 600 tonnes of sewage solids (sludge) from entering Victoria Harbour each day. 

 

1.3               Yet, sewage from the densely populated parts of Hong Kong Island (i.e., northern and southwestern districts), which currently account for about 450,000 m3/d of sewage flow from the planned catchment of HATS, is only subject to preliminary treatment (i.e., screening and de-gritting) before discharging into the harbour.  This preliminary treated sewage, coupled with the un-disinfected effluent from the SCISTW, is a source of the current water quality problems, particularly in the western part of the harbour including bathing beaches in the Tsuen Wan area.  Moreover, with the anticipated growth in population and business activities in the harbour area, water quality would resume a deteriorating trend in future unless the remainder of untreated sewage from Hong Kong Island is intercepted and treated.

Phased Implementation

1.4               Based on recommendations of an earlier international review[1] and subsequent environmental and engineering feasibility studies[2], and after taking into account the public’s views collected through a five-month long consultation in 2004, the Government announced on 22nd April 2005 the implementation of HATS Stage 2 in two phases, namely Stage 2A and Stage 2B:

 

1.5               Under Stage 2A (hereinafter referred to as the Project), the scope of work includes:

 

·         Upgrading of eight existing preliminary treatment works (PTW) at North Point, Wan Chai East, Central, Sandy Bay, Cyberport, Wah Fu, Aberdeen, and Ap Lei Chau on Hong Kong Island

·         Extension of the deep tunnel network to collect and transfer sewage from the above preliminary treatment works to SCISTW for treatment and disposal

·         Augmentation of the existing CEPT capacity at SCISTW from the present design capacity of 1.7million m3/day to the ultimate design capacity (which is estimated at about 2.45million m3/day based on latest available information)  

·         Provision of disinfection to all HATS effluent before discharging into the harbour

1.6               Under Stage 2B, a new secondary level (biological) treatment plant on a site adjacent to SCISTW is proposed to treat all HATS flow.  Planning for Stage 2B is in hand, with a view to completing it in time to suit actual sewage flow build up and water quality conditions. 

 

1.7               The target for completing Stage 2A is set at 2014.  This Environmental Impact Assessment (EIA) Study is concerned with HATS Stage 2A (the Project).

 

1.8               Noting that the discharge of un-disinfected sewage effluent from SCISTW is contributing to unsatisfactory beach water quality at the Tsuen Wan beaches, the Government has also proposed to advance the provision of part of the permanent disinfection facilities under HATS Stage 2A for completion in 2009.  This proposal is hereafter referred to as the “Advance Disinfection Facilities” (or ADF), and is covered in a separate EIA study[3].  

 

The Assignment

Overview

 

1.9               The purpose of the EIA Study is to provide information on the nature and extent of environmental impacts arising from the construction and operation of the Project and related activities that take place concurrently.  This information will contribute to decisions on:

·         the overall acceptability of any adverse environmental consequences that are likely to  arise as a result of the Project;

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

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

 

1.10            The Project involves several types of Designated Projects under the Environmental Impact Assessment Ordinance (EIAO) described in Table 1.1 and an Environmental Permit is required for its construction and operation.  On 17th August 2005, the Environmental Protection Department (EPD) issued EIA Study Brief No.ESB-129/2005 for the Project under section 5(1) of the EIAO.

Table 1.1          Designated Projects under the Environmental Impact Assessment Ordinance 

Descriptions of Key Project Components

Item of the EIAO

Proposed Preliminary Treatment Works (PTWs) upgrading at North Point, Wan Chai East, Central, Sandy Bay, Cyberport, Aberdeen, Wah Fu and Ap Lei Chau with an installed capacity of more than 15,000m3 per day

 

Item F1 Part I Schedule 2 of the EIAO

Proposed Stonecutters Island Sewage Treatment Works upgrading with an installed capacity of more than 15,000m3 per day

 

Item F1 Part I Schedule 2 of the EIAO

A deep tunnel from Central to Stonecutters Island which has a diameter more than 1,200mm and a length more than 1km

 

Item F5 Part I Schedule 2 of the EIAO

Proposed pumping stations at Cyberport, Sandy Bay, Wan Chai East, Ap Lei Chau, North Point and Aberdeen with an installed capacity more than 2,000m3 per day and a boundary of which are less than 150m from an existing or planned residential area, educational institution and/or health care institution

 

Item F3(b)(i) Part I Schedule 2 of the EIAO

 

Objectives of the Assignment

 

1.11           The main objective of the Assignment is to complete the EIA Study for the Project as required by the Study Brief in accordance with the EIAO.  The EIA Report has been prepared to:

·         describe the Project and associated works together with the requirements for carrying out the Project;

·         identify and describe elements of community and environment to be affected by the Project and/or to cause adverse impacts to the Project, including both the natural and man-made environment and the associated environmental constraints;

·         consider alternatives where necessary, with a view to avoiding and minimizing the potential environmental and ecological impacts, in particular, on sensitive receivers within the receiving water bodies; to compare the environmental benefits and dis-benefits of each of the different options; to provide reasons for selecting the preferred option(s) and to describe the part environmental factors played in the selection;

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

·         identify and assess the level of disinfection required in order to protect the beneficial uses of the sensitive receivers identified, including the Tsuen Wan beaches;

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

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

·         identify the negative impacts on any historical and archaeological resources and to propose measures to mitigate these impact;

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

·         investigate the feasibility, practicability, effectiveness and implications of the proposed mitigation measures;

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

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

·         investigate the extent of the secondary environmental impacts that may arise from the proposed mitigation measures and to identify constraints associated with the mitigation measures recommended in the EIA study, as well as the provision of any necessary modification; and

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

 

Assessment Area

 

1.12            The Assessment Area for the EIA Study, as specified in the Brief, includes:

 

·         Air quality impact assessment – area within a distance of 500m from the boundary of each of the Project sites, and it shall be extended to include areas where the air quality may be potentially affected by the Project especially areas close to the nearby access road(s) affected by construction vehicles moving to and from the construction sites.  For odour impact assessment, the study area shall be extended to include all affected sensitive receivers at distances over 500m from the Project, who would be affected by the construction and operation of the Project, including those who have in the past years complained about the odour nuisance from the existing facilities and operation of HATS.

·         Noise impact assessment – area within a distance of 300m from the project boundary, and it shall be extended to include areas that may be potentially affected by the Project especially areas close to the nearby access road(s) affected by construction vehicles moving to and from the construction sites.  Subject to EPD agreement, the assessment area could be reduced accordingly if the first layer of noise sensitive receivers, closer than 300m from the outer project limit, provides acoustic shielding to those receivers at further distance behind.

·         Water quality impact assessment – cover the Water Control Zones of North Western, Western Buffer, Victoria Harbour, Eastern Buffer, Junk Bay and Southern, and it shall be extended to include major emission sources that may have a bearing on the environmental acceptability of the Project.

·         Ecological impact assessment – area of terrestrial ecological assessment include all areas within 500m distance from the site boundary of the land-based works area of which the flora, fauna and other components of the ecological habitats are likely impacted by the Project such as the works at Sandy Bay, Cyberport, and Aberdeen.  The assessment area of marine ecological assessment shall be the same as the assessment area for water-quality impact assessment, or the area likely to be impacted by the Project, including areas in the vicinity of the outfalls.

·         Fisheries Impact assessment – generally the same as for water quality impact assessment, and any areas likely to be impacted by the Project, including the Ma Wan, Sok Kwu Wan, Lo Tik Wan, Cheung Sha Wan, Po Toi, and Tung Lung Chau fish culture zones.

·         Landscape impact assessment – area within the sites and works areas due to the Project.

·         Visual impact assessment – area within the Zone of Visual Influence (ZVIs) at construction and operation stages. These are the people who would reside within, work within, play within, or travel through, the ZVIs.

Organisation of the Report

1.13            The structure of the EIA Report is set out below:

·         Section 2 illustrates the Project locations, and provides a description of the Project highlighting the key elements and operation activities.

·         Section 3 identifies and assesses the potential air quality impacts associated with the construction and operation of the Project.

·         Section 4 identifies and assesses the potential air-borne noise impacts associated with the construction and operation of the Project.

·         Section 5 identifies and assesses the potential ground-borne noise impacts associated with the construction of the Project.

·         Section 6 identifies and assesses the potential water quality impacts associated with the construction and operation of the Project.

·         Section 7 presents the human health risk assessment conducted for the operation of the Project.

·         Section 8 presents the ecological risk assessment conducted for the operation of the Project.

·         Section 9 evaluates and assesses the waste management implications associated with the construction and operation of the Project.

·         Section 10 identifies and assesses the potential terrestrial ecological impacts associated with the construction and operation of the Project.

·         Section 11 identifies and assesses the potential marine ecological impacts associated with the construction and operation of the Project.

·         Section 12 identifies and assesses the potential impacts on fisheries resources associated with the construction and operation of the Project.

·         Section 13 identifies and assesses the potential impacts on landscape and visual associated with construction and operation of the Project.

·         Section 14 presents the hazard to life assessment conducted for the construction and operation of the Project.

·         Section 15 identifies and assesses the potential impacts on cultural heritage associated with the construction and operation of the Project.

·         Section 16 highlights the environmental monitoring and audit (EM&A) requirements for the Project.  The scope and approach are presented in detail in a stand-alone EM&A Manual.

·         Section 17 summarizes and concludes the findings of the EIA Study.

·         Section 18 presents the Implementation Schedules for mitigation of the various environmental issues addressed in the EIA Study.

 


[1] In 2000, the Government commissioned an International Review Panel (IRP) to review the future of HATS.  See http://www.cleanharbour.gov.hk/english/g3_2_1.html for details.

[2] The Environmental and Engineering Feasibility Assessment Studies for Further Stages of HATS (EEFS) was conducted over 2002 and 2003 to investigate and further conceptualise the IRP’s recommendations on implementing further stages of HATS.  See http://www.cleanharbour.gov.hk/english/g3_2_1.html for details.

[3] The objective of the ADF is to reduce the E. coli level in the CEPT effluent at SCISTW prior to discharge and hence facilitate early improvement to beach water quality.  A separate EIA study - Agreement No. CE 7/2005 (EP) HATS EIA Study for the Provision of Disinfection Facilities at Stonecutters Island STW - Investigation has been approved by EPD on 8 November 2007(Approved EIA Register No.: AEIAR-113/2007).