1. introduction

1.1 Background of the Project

1.1.1.1 The existing Pillar Point Sewage Treatment Works (PPSTW), which is located at north of the Tuen Mun River Trade Terminal bounded by Lung Mun Road at the north, is a preliminary treatment works of 5.79 m³/s capacity. The operation of the existing PPSTW is to remove screenings followed by grit removal prior to discharging its effluent into the sea via twin submarine outfalls. Under the Review of the Tuen Mun and Tsing Yi Sewerage Master Plan (RTMTYSMP) commissioned in February 1999, the existing Pillar Point STW was recommended be upgraded from preliminary treatment to chemical treatment with disinfection. The aim of the recommended upgrading works is to improve the effluent quality, and to meet the demand of future population and pollutant loads at ultimate development scenario.

1.1.1.2 The RTMTYSMP recommended the viability of the upgrading works to the PPSTW, which comprised the following:

Ÿ expanding the treatment capacity of the existing PPSTW to cope with the increased peak wet weather sewage flow under the ultimate development scenario to cater for the increase in population arising from the planned development in Tuen Mun area;

Ÿ upgrading the sewage treatment level of the existing PPSTW to incorporate chemical treatment with disinfection at minimum removal rates of 70%, 55% and 99.9% for suspended solids (SS), biochemical oxygen demand (BOD) and E. coli respectively;

Ÿ upgrading existing septic waste reception facilities at PPSTW; and

Ÿ providing and upgrading ancillary facilities including the administration building, workshop, laboratory, odour control facilities, sludge handling and dewatering facilities, access roads and minor landscaping works within the STW for the operation and maintenance of the upgraded STW.

1.1.1.3 The construction of the upgrading works and the operation and maintenance of the upgraded PPSTW will be implemented under a design-build-operate (DBO) contract arrangement (hereinafter referred to as “the Project”). It is targeted to award the DBO contract in April 2009 for completion of the construction works by May 2012.

1.2 The Assignment

1.2.1.1 On 6 July 2005, Metcalf & Eddy Ltd. was commissioned by the Drainage Services Department of the Hong Kong SAR Government to undertake the investigation, preliminary design and construction of the Project (hereinafter referred to as “the Assignment”).

1.2.1.2 A preliminary design taking into account all the Project requirements is carried out. In the preparation of the preliminary design, the sewage flows and loads are to be estimated in order to determine the treatment capacity and effluent standards of the upgraded PPSTW. Moreover, an appropriate treatment process is to be selected for the upgraded PPSTW. The Environmental Impact Assessment (EIA) Study is conducted based on the preliminary design in order 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:

(a) the overall acceptability of any adverse environmental consequences that is likely to arise as a result of the Project;

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

1.2.1.3 The Project is a Designated Project under Item F.1 Part I Schedule 2 of the Environmental Impact Assessment Ordinance (EIAO) (i.e. sewage treatment works with an installed capacity of more than 15,000 m³ per day) and requires an environmental permit under the EIAO for the implementation of the Project. The EIA Study Brief (No. ESB-122/2004) for an EIA study for the Project under section 5(1) of the EIAO was issued by the Environmental Protection Department (EPD) on 23 December 2004.

1.3 Objectives of the Assignment

1.3.1.1 The main objective of the Assignment is to conduct an EIA Study for the Project in accordance with the EIAO. The EIA Report has been prepared so as to:

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

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

Ÿ consider alternatives where necessary, as detailed in Section 3.3 of the EIA Study Brief, with a view to avoiding and minimizing the potential environmental impacts to the ecological sensitivity areas in Sha Chau and Lung Kwu Chau Marine Park and other sensitive uses; 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;

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

Ÿ identify and quantify any potential losses or damage to flora, fauna and natural habitats and to propose measures to mitigate these impacts;

Ÿ identify and assess any potential landscape and visual impacts caused by the Project during construction and operation stages, in particular the potential landscape and visual impacts to users of Lung Mun Road and the proposed two sites on the hill slopes opposite Lung Mun Road earmarked for holiday camp development for the Tung Wah Group of Hospitals;

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

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

Ÿ identify, predict and evaluate the residual environmental impacts (i.e. after practicable mitigation) 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;

Ÿ 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;

Ÿ 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

Ÿ design and specify environmental monitoring and audit requirements to ensure the effective implementation of the recommended environmental protection and pollution control measures.

1.1 Assessment Area

1.1.1.1 The Assessment Area covered by the EIA Study is presented below.

Ÿ Air quality impact assessment – area within a distance of 500m from the boundary of the Project site.

Ÿ Water quality impact assessment – cover the Water Control Zones of North Western, Western Buffer and Deep Bay.

Ÿ Ecological impact assessment – the same as the assessment area for water quality impact assessment.

Ÿ Landscape impact assessment – the area within a 500m distance from the Project.

Ÿ Visual impact assessment - defined by visual envelope (also called zone of visual influence) of the Project

1.2 Organisation of the Report

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

Ÿ Section 2 provides a description of the Project and its need, and the selection of the preferred treatment processes.

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

Ÿ Section 4 identifies and assesses the potential water quality impacts associated with the construction and operation of the Project.

Ÿ Section 5 – Not Used

Ÿ Section 6 identifies and assesses the potential marine ecological impacts associated with the construction and operation of the Project.

Ÿ Section 7 identifies and assesses the potential waste management implications associated with the construction and operation of the Project.

Ÿ Section 8 presents the landscape and visual impact assessment of the construction and operation of the Project.

Ÿ Section 9 outlines the environmental monitoring and audit (EM&A) requirements for the Project. The scope and methodology are presented in detail in a stand-alone EM&A Manual.

Ÿ Section 10 summarises and concludes the findings of the EIA Study.

Ÿ Section 11 presents the Implementation Schedules for mitigation of the various environmental issues addressed in the EIA Study