TABLE OF CONTENT

 

1.            INTRODUCTION. 1-1

Background to the Study. 1-1

Purpose and Scope of EIA. 1-5

EIA Study Area. 1-5

Structure of the Report 1-6

 

2.            Description of the Project. 2-1

Location of the Project 2-1

Need of the Project 2-1

Scope of the Project 2-2

Consideration of Alternative Drainage Options. 2-3

Recommendations on Preliminary Design of Drainage Improvement Works. 2-6

Consideration of Alternative Construction Method. 2-6

Project Implementation. 2-7

Interactions with Other Projects. 2-7

Summary. 2-7

 

3.            CONSTRUCTION NOISE IMPACT. 3-1

Introduction. 3-1

Environmental Legislation, Standards and Guidelines. 3-1

Description of the Environment 3-2

Noise Sensitive Receivers. 3-2

Assessment Methodology. 3-3

Identification of Impacts. 3-4

Prediction and Evaluation of Impacts. 3-4

Mitigation of Adverse Environmental Impacts. 3-5

Residual Environmental Impacts. 3-8

Cumulative Construction Noise Impact 3-8

Environmental Monitoring and Audit 3-9

Conclusion. 3-9

 

4.            AIR QUALITY IMPACT. 4-1

Introduction. 4-1

Environmental Legislation, Standards and Guidelines. 4-1

Description of the Environment 4-1

Air Sensitive Receivers. 4-2

Identification and Evaluation of Environmental Impacts. 4-2

Mitigation of Adverse Environmental Impacts. 4-3

Residual Environmental Impacts. 4-4

Environmental Monitoring and Audit 4-4

Conclusion. 4-4

 

5.            WATER QUALITY. 5-1

Introduction. 5-1

Environmental Legislation and Standards. 5-1

Baseline Conditions. 5-3

Water Sensitive Receivers. 5-4

Assessment Methodology. 5-4

Identification and Evaluation of Environmental Impacts. 5-5

Mitigation Measures. 5-7

Residual Environmental Impacts. 5-9

Environmental Monitoring and Audit Requirements. 5-9

Conclusion. 5-10

 

6.            WASTE MANAGEMENT implications. 6-1

Introduction. 6-1

Environmental Legislation and Standards. 6-1

Assessment Methodology. 6-2

Identification and Evaluation of Environmental Impacts. 6-2

Mitigation Measures. 6-4

Evaluation of Residual Impacts. 6-6

Environmental Audit 6-6

Conclusion. 6-6

 

7.            ECOLOGICAL IMPACT. 7-1

Introduction. 7-1

Environmental Legislation, Standards and Guidelines. 7-1

Assessment Methodology. 7-2

Baseline Conditions. 7-4

Ecological Value. 7-10

Identification of Ecological Impacts. 7-16

Impact Evaluation. 7-17

Mitigation of Adverse Environmental Impacts. 7-28

Residual Environmental Impacts. 7-30

Environmental Monitoring and Audit Requirements. 7-30

Conclusions. 7-31

References. 7-33

 

8.            LANDSCAPE AND VISUAL IMPACT ASSESSMENT. 8-1

Introduction. 8-1

Project Description. 8-1

Review of Planning and Development Control Framework. 8-1

Environmental Legislation and Standards. 8-1

Methodology of Assessment of Landscape Impacts. 8-2

Methodology of Assessment of Visual Impacts. 8-4

Baseline Study. 8-6

Landscape Resource. 8-6

Landscape Character Area. 8-8

Visually Sensitive Receiver 8-9

Landscape Impact Assessment (Before Mitigation) 8-11

Visual Impact Assessment (Before Mitigation) 8-13

Recommended Landscape and Visual Mitigation Measures. 8-17

Residual Impacts. 8-17

Photomontage of Residual Visual Impact 8-17

Conclusion. 8-17

 

9.            FISHERIES IMPACT. 9-1

Introduction. 9-1

Environmental Legislation, Standards and Guidelines. 9-1

Assessment Methodology. 9-1

Description of the Environment 9-1

Fisheries Importance. 9-3

Mitigation of Adverse Environmental Impacts. 9-4

Evaluation of Residual Impacts. 9-4

Environmental Monitoring and Audit 9-4

Conclusions. 9-4

References. 9-5

 

10.          ENVIRONMENTAL MONITORING AND AUDIT. 10-1

Introduction. 10-1

Construction Noise Impact 10-1

Construction Air Quality Impact 10-1

Water Quality Impact 10-1

Waste Management Implications. 10-2

Ecological Impact 10-2

Landscape and Visual Impact 10-2

Fisheries Impact 10-3

 

11.        OVERALL CONCLUSION. 11-1

 

12.        IMPLEMENTATION SCHEDULE AND RECOMMENDED MITIGATION MEASURES. 12-1

 

 

List of Tables

Table 1.1....... Designated Projects under the Assignment 1-7

Table 2.1....... Evaluation of Alternative for Drainage Improvement Works in Shuen Wan. 2-16

Table 2.2....... Comparison of Environmental Impacts from the Practicable Options. 2-17

Table 3.1....... Representative Noise Sensitive Receivers. 3-2

Table 3.2....... On-time Percentage Assumptions for Certain Items of PME. 3-3

Table 3.3....... Construction Tasks for the Proposed Drainage Improvement Works. 3-3

Table 3.4....... Ranges of Unmitigated Construction Noise Levels. 3-4

Table 3.5....... Quieter PME Recommended for Adoption during Construction Phase. 3-5

Table 3.6....... Plant Inventory for the Low Impact Method. 3-7

Table 3.7....... Mitigated Construction Noise Levels. 3-7

Table 4.1....... Hong Kong Air Quality Objectives. 4-1

Table 4.2....... Representative Air Sensitive Receivers. 4-2

Table 5.1....... Water Quality Objectives for Inland Waters. 5-1

Table 5.2....... Summary of Water Quality Monitoring Results for Tung Tze Stream in 2004. 5-3

Table 6.1....... Summary of C&D Material Volumes. 6-13

Table 7.1a...... Ecological Value of Rivers & Streams in the Assessment areas. 7-26

Table 7.1b...... Ecological Value of Secondary Woodland and Fung Shui Woodland in the Assessment Areas. 7-26

Table 7.1c...... Ecological Value of Cultivated/Abandoned Land and Village/Developed Area Habitats in the Assessment Areas  7-27

Table 7.1d ..... Ecological Value of Plantation/Landscape Planting and Fishponds in the Assessment Areas. 7-27

Table 7.1e ..... Ecological Value of Shrubland and Marshes in the Assessment Areas. 7-28

Table 7.1f ...... Ecological Value of Mangrove and Marine Habitats in the Assessment Areas. 7-29

Table 7.2a ..... Evaluation of Floral Species of Conservation Interest Recorded Within Assessment Areas. 7-31

Table 7.2b ..... Evaluation of Faunal Species of Conservation Interest Recorded Within Assessment Areas. 7-31

Table 7.3  ..... Habitats directly affected by proposed works. 7-32

Table 7.4a...... Overall Impact Evaluation of Secondary Woodland and Fung Shui Woodland. 7-34

Table 7.4b...... Overall Impact Evaluation of Cultivated/Abandoned Land and Village/Developed Area Habitats. 7-34

Table 7.4c...... Overall Impact Evaluation of Plantation/Landscape Planting and Fishpond Habitats. 7-35

Table 7.4d...... Overall Impact Evaluation of Shrubland and Marsh Habitats. 7-35

Table 7.4e...... Overall Impact Evaluation of Mangrove and Marine Habitats. 7-36

Table 7.4f....... Overall Impact Evaluation to Rivers and Streams. 7-38

Table 7.5....... Overall Impact Evaluations to Species of Conservation Interest 7-40

Table 8.1....... Matrix for Impact Significance Threshold Before Mitigation: Relationship between Sensitivity to Change and Magnitude of Change. 8-4

Table 8.2....... Significance of Landscape Impacts Before Mitigation. 8-15

Table 8.3....... Significance of Visual Impacts Before Mitigation. 8-16

Table 8.4....... Recommended Landscape and Visual Mitigation Measures. 8-18

Table 8.5....... Landscape Impacts After Mitigation. 8-21

Table 8.6....... Visual Impacts After Mitigation. 8-22

Table 11.1...... Summary of Key Environmental Outcomes / Benefits. 11-1

Table 12.1...... Project Implementation Schedule. i

 

 

List of Figures

 

Figure 1.1         Location Plan for the Project (Original Scope of Works)

Figure 1.2         Original Scheme for Drainage Improvement in She Shan Channel Reprofiling (Sheets 1 of 2)

Figure 1.2         Original Scheme for Drainage Improvement in She Shan Channel Reprofiling (Sheets 2 of 2)

Figure 1.3         Alternative Scheme for Drainage Improvement in She Shan Channel Reprofiling (Sheets 1 of 2)

Figure 1.3         Alternative Scheme for Drainage Improvement in She Shan Channel Reprofiling (Sheets 2 of 2)

Figure 1.4        Location Plan of Flood Protection in Tung Tsz Road and Drainage Diversion to Wa Ha River and Cross Road Drains Improvements

Figure 1.5         Provision of Box Culvert along Tung Tsz Road

Figure 1.6A       Location Plan for the Project (Revised Scope of Works)

Figure 1.6B       Drainage Improvement Works in She Shan River (Sheet 1 of 2)

Figure 1.6C       Drainage Improvement Works in She Shan River (Sheet 2 of 2)

Figure 1.6D       Drainage Channel Improvement to Upper Tai Po River

Figure 1.6E       Construction of Cross Road Drain at Kwun Hang River

Figure 1.6F        Stormwater Drainage Improvement at Tai Po Road – Yuen Chan Tsai (Sheet 1 of 2)

Figure 1.6G       Stormwater Drainage Improvement at Tai Po Road – Yuen Chan Tsai (Sheet 2 of 2)

Figure 1.6H       Stormwater Drainage Improvement at Tai Po Market (Sheet 1 of 2)

Figure 1.6I         Stormwater Drainage Improvement at Tai Po Market (Sheet 2 of 2)

Figure 1.6J        Construction of Floodwater Pumping Station at Tai Po Market

Figure 1.6K       Construction of Parapet Wall at Lam Tsuen River

Figure 1.6L        Construction of Flap Valves at Outfalls at Lam Tsuen River

Figure 1.6M       Construction of Cross Road Drain at Care Village

Figure 1.6N       Construction of Cross Road Drain at Po Sam Pai

Figure 3.1          Location of Noise Sensitive Receivers

Figure 3.2          Typical Section of Temporary Barrier for Site Clearance and Box Culvert Construction

Figure 3.3          Typical Design of Noise Enclosure

Figure 3.4          Typical Section of Temporary Noise Barrier for Pipe Laying at Wai Ha

Figure 3.5          Approximate Extent of Noise Mitigation Measure

Figure 4.1          Location of Air Sensitive Receivers

Figure 5.1          Identified Water Sensitive Receivers

Figure 5.2          Arrangement of Excavation Works

Figure 7.1          Habitat Map (Sheet 1 of 2)

Figure 7.1          Habitat Map (Sheet 2 of 2)

Figure 7.2        Proposed Location of Compensatory Habitat and Receptor Site for Transplantation of Hong Kong Pavetta

Figure 7.3          Sub-Tidal Survey Location

Figure 8.1          Location Plan for the project

Figure 8.2          Existing Aerial View of Study Area

Figure 8.3          Planning and Development Framework (OZP)

Figure 8.4          Landscape Resources

Figure 8.5          Photo of Landscape Resources

Figure 8.6          Photo of Landscape Resources

Figure 8.7          Photo of Landscape Resources

Figure 8.8          Photo of Landscape Resources

Figure 8.9          Photo of Landscape Resources

Figure 8.10        Landscape Character Area

Figure 8.11        Photo of Landscape Character Areas

Figure 8.12        Photo of Landscape Character Areas

Figure 8.13        Photo of Landscape Character Areas

Figure 8.14        Visually Sensitive Receivers

Figure 8.15        Photo of Visually Sensitive Receivers

Figure 8.16        Photo of Visually Sensitive Receivers

Figure 8.17        Photo of Visually Sensitive Receivers

Figure 8.18        Photo of Visually Sensitive Receivers

Figure 8.19        Photo of Visually Sensitive Receivers

Figure 8.20        Views from Visually Sensitive Receivers

Figure 8.21        Views from Visually Sensitive Receivers

Figure 8.22        Views from Visually Sensitive Receivers

Figure 8.23        Views from Visually Sensitive Receivers

Figure 8.24        Photomontage Locations

Figure 8.25        Photomontage – VSR 3 (Sheet 1 of 2)

Figure 8.26        Photomontage – VSR 3 (Sheet 2 of 2)

Figure 8.27        Photomontage – VSR 5 (Sheet 1 of 2)

Figure 8.28        Photomontage – VSR 5 (Sheet 2 of 2)

Figure 8.29        Conceptual Landscape Plan with Mitigation Measures

Figure 8.30        Residual Impacts on Landscape Resources in Construction Phase

Figure 8.31        Residual Impacts on Landscape Character Areas in Construction Phase

Figure 8.32        Residual Impacts on Landscape Resources in Operation Phase

Figure 8.33        Residual Impacts on Landscape Character Areas in Operation Phase

Figure 8.34        Photomontage – Compensatory Planting along Tung Tze Road

 

 

Appendices

 

Appendix 1.1     Measures Recommended for Works Items Not Classified as Designated Projects

Appendix 2.1     Layout Plans for Tolo Harbour Sewerage of Unsewered Areas Stage 1 Phase IIC

Appendix 3.1     Calculation of Construction Noise - Unmitigated Scenario

Appendix 3.2     Calculation of Construction Noise – Mitigated Scenario

Appendix 7.1     Representative Photographs of Habitats Recorded within the Assessment Area

Appendix 7.2     Photographs of Species of Conservation Interest Recorded within the Assessment Area

Appendix 7.3     Flora Recorded within the Assessment Area

Appendix 7.4     Fauna Recorded within the Assessment Area

Appendix 7.5     Intercept Point of Wai Ha River and the Proposed Twin Cell Box Culvert

Appendix 8.1     Broad Tree Survey Schedule and Survey Plan


1.                   INTRODUCTION

Background to the Study

1.1               The Sha Tin and Tai Po Drainage Master Plan (DMP) Study, completed in October 1999, indicated that certain stormwater drains and natural rivers/streamcourses in the Sha Tin and Tai Po areas did not have the required hydraulic capacity to meet the flow requirements.  To minimise the risks of flooding and to cope with future developments as identified in the DMP Study, construction of river channels, upgrading of existing stormwater drains, construction of flood pumping stations in the low-lying areas and other minor drainage facilities were recommended.

1.2               Upon completion of the DMP Study, the Drainage Services Department (DSD) of Hong Kong SAR Government commissioned Maunsell Consultants Asia Ltd. (MCAL) to undertake Agreement No. CE50/2001 (DS) Drainage Improvement in Sha Tin and Tai Po – Design and Construction (hereinafter referred to as “the Assignment”), for implementing the drainage improvement works at various locations as recommended by the DMP study to alleviate the potential flooding problems in Sha Tin and Tai Po districts. 

1.3               A Preliminary Environmental Review (PER) was conducted in conjunction with the Preliminary Project Feasibility Study (PPFS) for the DMP Study to identify the potential environmental issues, such as air quality, noise, water quality and ecology, arising from drainage improvement works and the likely mitigation measures required.  The PER completed in March 2000 identified 13 project items (i.e. DP-1 to DP-13 stated in Table 1.1 below) which should be regarded as designated projects (DPs) under the Environmental Impact Assessment Ordinance (EIAO) (Cap. 499).  A Project Profile was submitted by DSD in June 2001 for an Environmental Impact Assessment (EIA) study brief to proceed with an EIA study for these 13 DPs.  A study brief was issued in July 2001 (EIA Study Brief No. ESB-077/2001).  Figure 1.1 shows the locations of these DPs under the original scope of the works. 

 

Table 1.1          Designated Projects under the Assignment

 

Designated Project No.

Description of Designated Project

 

Drainage channel improvement to existing rivers

DP-1

Drainage channel improvement to She Shan River

DP-2

Drainage channel improvement to Tai Po River

DP-3

Drainage channel improvement to Kwun Hang River

 

Drainage improvement in Tai Po

DP-4

Stormwater drainage improvement at Tai Po Road – Yuen Chau Tsai

DP-5

Stormwater drainage improvement at Tai Po Market

DP-6

Construction of floodwater pumping station at Tai Po Market

DP-7

Construction of parapet wall at Lam Tsuen River

DP-8

Construction of flap valves at outfalls at Lam Tsuen River

DP-9

Construction of cross road drain at CARE village

 

Drainage improvement in Shuen Wan

DP-10

Construction of floodwall along Tung Tsz Road, Shuen Wan

DP-11

Construction of floodwater pumping station at Shuen Wan

DP-12

Construction of cross road drain at Po Sam Pai

DP-13

Construction of cross road drain at Shuen Wan

 

1.4               Following the review conducted under this Assignment, the scope of works for each DP has been reviewed and revised, with the extent of the proposed works been more clearly defined.

1.5               It is understood that a number of these project works items were being treated as DPs in the PER stage because the proposed works had been classified as “drainage channel or river training works” and fallen within the requirements as stated in Schedule 2 of the EIAO. 

1.6               Based on the revised scope and the more clearly defined extent of the proposed works, which may be different from those recommended under the DMP Study, together with the consideration of the definition of “drainage channel” and “rivers” provided in ETWB TCW No. 5/2005, a review has been carried out to assess whether these works items should still be regarded as DPs under the EIAO, and the assessment are explained below.  The latest scope of the different proposed works is shown in Figures 1.6A – 1.6N.

DP-1

1.7               The original proposed drainage improvement works at She Shan River is considered as a DP under Schedule 2 of the EIAO since the works would fall partly within a Conservation Area (CA).  A design review has been conducted under the Assignment, and changes in the design for the channel improvement works in She Shan River were recommended.  A by-pass channel of about 150m long is proposed to be built along an upstream section of the river so as to leave the natural river section in the CA untouched as well as to provide a buffer for the CA.  The alignment of the original proposed scheme and the alternative scheme are shown in Figure 1.2 and 1.3 respectively. Impacts on the more natural, upstream areas of She Shan River would also be avoided through the construction of the by-pass channel running alongside the existing stream channel.  Given that the revised proposed drainage improvement works are now outside the designated CA, it is considered that the proposed drainage improvement works at She Shan River, with the adoption of the alternative scheme, should not be considered as a DP under the EIAO.  Notwithstanding the above, measures are proposed to minimize the impact on She Shan River.  It is recommended that the excavation work carried out within water body should be restricted to enclosed dry section of the river with appropriate containment measure to minimize the potential sedimentation of downstream water body.  Besides, vegetated gabion channel wall is proposed for the restoration of riparian zone.  Details of the proposed measures are presented in Appendix 1.1. 

DP-2

1.8               This project item was considered as a DP since the works are proposed at sections of the Upper Tai Po River with discharge into an area less than 300m from two sites of cultural heritage, namely the Wun Yiu Pottery Kilns and Fan Sin Temple, both of which are declared monuments under the Antiquities and Monuments Ordinance.  The extent of the works areas of the Project has been reviewed, revised and minimised as far as practicable to maximise the distance from the two sites of cultural heritage.  The potential indirect impacts on the recorded resources through noise/vibration, dust and/or site runoff from the proposed construction activities are also minimised and considered to be minor given the scale of works involved is small.  There is limited scope of vibratory plant for the construction works and adequate buffer zones will be provided between the works area and the recorded resources. 

1.9               Various measures have been proposed to minimise and mitigate the possible ecological impacts.  A more environmentally-friendly’ channel design instead of the standard, trapezoidal concrete lined channel used in many previous drainage improvement projects.  Furthermore, the existing large boulders will be maintained as much as possible or returned to form a potentially important microhabitat for fauna to the riverbed following excavation works.  In addition, a section of about 150m of the existing, natural riverbank on the western side of the river will also be maintained. 

1.10            With these changes along with the implementation of mitigation measures, it is considered that the proposed works would not incur insurmountable impact to the environment.  A project profile has been prepared to apply for permission to direct application of an environmental permit under Section 5(11) of the EIAO as the environmental impacts associated with the proposed works would fall within the guidelines and criteria laid down in the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) and the effectiveness of the mitigation measures has been demonstrated in practice.  The application was approved in July 2005 and an environmental permit No. EP-223/2005 was granted in August 2005. 

DP-3

1.11            According to the original proposal for DP-3 (i.e. drainage channel improvement to Kwun Hang River) as presented in the PPFS, about 0.5km of Kwun Hang River would be upgraded to a concrete engineered channel.  The original proposal has subsequently been reviewed and revised; the revised scope for the proposed drainage channel improvement works at Kwun Hang River has been significantly reduced.  In the revised design proposal, only the existing single-cell box culvert and the associated head walls under Sai Sha Road would be re-constructed to remove the bottleneck identified in Kwun Hang River.  With this revision to the proposed drainage improvement works, this works item is not considered to be a DP according to the EIAO.  Nevertheless, it is proposed that the excavation works within water body to be carried out by land-based plant and be restricted to enclosed dry section to minimize the potential water quality impacts to marine habitats downstream of proposed works.  Details of the proposed measures are presented in Appendix 1.1.

DP-4 and DP-5

1.12            Works Items (4) and (5) involves installation of underground drainage pipes along Tai Po Road – Yuen Chau Tsai and in Tai Po Market.  These project items were considered as DPs since they were considered as “drainage channels” or “rivers” with discharge into an area less than 300m from declared monuments namely “Island House”, “Man Mo Temple” and “Tai Po Market Railway Station”.  The revised proposed works only involve laying of underground drainage pipe which would not fall within the category of “drainage channel or river training and diversion works” as stipulated in Schedule 2 of the EIAO and hence they are not considered as DPs according to the EIAO.  In view that the works is proximate to the residential areas, the use of quieter PME, temporary noise barrier and acoustic shed is recommended to be adopted to mitigate the adverse noise impact.  Details of the proposed measures are presented in Appendix 1.1.

DP-6 and DP-8

1.13            DP-6 and DP-8 encompass the construction of a floodwater pumping station at Tai Po Market and installation of flap valves at outfall of Lam Tsuen River.  Since these two works were considered as “drainage channels” or “rivers” and with discharge within 300m from a declared monument – Man Mo Temple, they were designated as DPs previously. However, the revised proposed works under these two project works only involve construction of floodwater pumping station and flap valves at the river bank of Lam Tsuen River which do not fall within the description of “drainage channel or river training and diversion works” under Schedule 2 of the EIAO, and therefore they should not be considered as DPs according to the EIAO.  In view that the works is proximate to the public school, the use of quieter PME and temporary noise barrier is proposed to reduce the adverse noise impact.  Details of the proposed measures are presented in Appendix 1.1.

DP-7

1.14            The proposed drainage improvement works for DP-7 involves construction of parapet wall at the river bank of Lam Tsuen River.  The reason for classifying it as a DP was due to the proposed works were considered to be related to “drainage channels” or “rivers” with discharge less than 300m from a declared monument – Man Mo Temple.  However, after reviewing the necessity of this project works item, it has been concluded that the existing river bank is able to provide adequate flood protection to the areas and as a result this project works item is considered not necessary and have been deleted from the project. 

DP-9

1.15            DP-9 involves construction of a crossroad drain at CARE village across KCRC.  This works item was considered as to be related to “drainage channels” or “rivers” with discharge within 300m from the Island House at Yuen Chau Tsai, which is a declared monument, and was considered to be a DP.  The exact extent of this project item has been reviewed and revised which now only involves the construction of an underground pipe by trenchless method and does not fall in the category of “drainage channel or river training and diversion works” under Schedule 2 of EIAO.   As such this works item should not be considered to be a DP according to the EIAO.  In view that the works is proximate to the residential areas, the use of quieter PME, temporary noise barrier and noise enclosure is recommended to mitigate the adverse noise impact.  Details of the proposed measures are presented in Appendix 1.1.

DP-10, DP-11 and DP-13

1.16            DP-10, DP-11 and DP-13 were collectively undertaken for drainage improvement for the Shuen Wan area in Tai Po.  The flood protection works proposed under the original design included the construction of a floodwall along Tung Tsz Road, a floodwater pumping station at Shuen Wan and a cross road drain at Shuen Wan.  Layout of the original flood protection scheme is shown in Figure 1.4.  After a comprehensive design review and consultation with the local residents and the District Council have been conducted, the original proposed works have been revised accordingly.

1.17            During the course of public consultation, several alternative flood protection schemes, including doing nothing, raising of Tung Tsz Road, provision of invert siphon, construction of box culvert along Tung Tsz Road, were explored in addition to the original scheme.  Details of the alternative schemes are discussed in Section 2.  Having considered the practicality, reliability, cost effectiveness and environmental and social acceptability of alternatives and the comment given by the Environmental and Works Committee of Tai Po District Council, the scheme involving the construction of box culvert along Tung Tsz Road was adopted as the preferred scheme.  The latest scope of works for the drainage improvement in the Shuen Wan area (hereinafter referred to as “the Project”) is shown in Figure 1.5, the works comprise:

§          Construction of a twin-cell box-culvert along Tung Tsz Road (Alternative of DP-10)

§          Construction of a floodwater pumping station at Shuen Wan (DP-11)

§          Replacement of mechanical gate at Wai Ha River

§          Construction of about 280m of relief drain in Wai Ha Village

§          Construction of about 260m drainage pipe along Ting Kok Road

1.18            With the implementation of the proposed twin-cell box-culvert and the pumping station, the original proposed cross road drain at Shuen Wan, which was designated as DP-13, for the purpose of providing additional capacity for flood relief at the mouth of Wai Ha River is no longer required. 

1.19            The original proposed works involve the construction of a floodwall along Tung Tsz Road.  This has now been replaced by the construction of a twin cells box-culvert along Tung Tsz Road.  In accordance with Category Q.1 of Part 1, Schedule 2 of the EIAO, works partly or wholly in an existing Conservation Area are classified as a DP.  Since a section of the proposed box-culvert along Tung Tsz Road would be constructed within the CA, the Project should be considered to be a DP under the EIAO.  The cumulative effects of all works items in para 1.17 above to the respective sensitive receivers will be assessed and addressed in this EIA study.  Environmental permits are required before the construction and operation of the Project can commence. 

DP-12

1.20            The proposed drainage improvement works under DP-12 only involves the upgrading of the existing crossroad box culvert at Po Sam Pai.  It was considered as a DP since the proposed drainage works was considered as “drainage channels” or “rivers” with discharge within 300m from the coastal protection area and Site of Special Scientific Interest.  The exact extent of the project has critically be reviewed and the revised works on upgrading for the box-culvert now does not fall within the description of “drainage channel or river training and diversion works” under Schedule 2 of EIAO, this works item is not considered to be a DP according to EIAO.  Nevertheless, it is proposed that the excavation works within water body to be carried out by land-based plant and be restricted to enclosed dry section to minimize the potential water quality impacts to marine habitats downstream of proposed works.  Further, the works is proximate to the residential areas, the use of quieter PME, temporary noise barrier and noise enclosure is proposed to be adopted to mitigate the adverse noise impact.  Details of the proposed measures are presented in Appendix 1.1.

Purpose and Scope of EIA

1.21            According to section 3.2 of the EIA Study Brief No. ESB-077/2001, the scope of the EIA study should cover the designated projects (DP-1 to DP-13) listed in section 1.2 (i) to (xiii).  However, as explained above, only the construction of the box culvert is regarded as a DP under the EIAO and therefore, the scope of this EIA study covers this works item and its associated works for drainage improvement in the Shuen Wan area that are described in section 1.17 above. 

1.22            The purpose of the Environmental Impact Assessment Report is to provide information on the nature and extent of environmental impacts arising from the construction and operation of the proposed Project and related activities taking place concurrently.  The information will contribute to decisions on:-

§          overall environmental acceptability of any adverse environmental consequences of the proposed Project.

§          the conditions and requirements for the detailed design and construction of the Project to mitigate against adverse environmental consequences wherever practicable.

§          the acceptability of residual impacts after the proposed mitigation measures.

EIA Study Area

1.23            The Assessment Area for the purpose of this EIA Report, as specified in the Study Brief, is presented below:

§          Noise impact assessment – include areas within 300m from the Project boundary.  (If the first layer of noise sensitive receivers provides acoustic shielding to those receivers further from the site, the assessment area could be reduced accordingly).

§          Air quality impact assessment - the assessment area should be a distance of 500m from the Project boundary.

§          Water quality impact assessment – include areas within 5km from the Project boundary. 

§          Ecological impact assessment – the assessment area for terrestrial ecological assessment should include areas within 500 m from the site boundary of the works areas, or the area likely to be impacted by the Project.  For aquatic ecology, the assessment area should be the same as for water quality assessment.

§          Landscape and visual impact assessment – the assessment area for landscape impact assessment should include areas within 300 m from the work limit of the proposed designated project, while the assessment area for the visual impact assessment should be defined by the visual envelope of the designated project.

§          Fisheries impact assessment – the assessment area should include the Fish Culture Zones at Yim Tin Tsai and Yim Tin Tsai (East).

Structure of the Report

1.24            The remainder of the report is organised as follows:

§          Section 2      describes the Project and its need, implementation programme, and addresses alternative considerations, designs and construction methods.

§          Section 3      identifies and assesses the potential noise impacts associated with the construction of the Project, and recommends mitigation measures to comply with the established noise standards, wherever necessary.

§          Section 4     identifies and assesses the potential air quality impacts associated with the construction of the Project, and recommends necessary mitigation measures.

§          Section 5      identifies and assesses the potential water quality impacts associated with the construction and operation of the Project, and recommends mitigation measures to minimize the impact.

§          Section 6      identifies and assesses the potential waste management implications associated with the construction of the Project and recommends appropriate waste handling, transportation and disposal practices.

§          Section 7      identifies and assesses the potential ecological impact associated with the construction and operation of the Project, and recommends mitigation measures to minimize the impact.

§          Section 8      identifies and assesses the potential landscape and visual impacts associated with the construction and operation of the Project.

§          Section 9      identifies and assesses the potential fisheries impact associated with the construction and operation of the Project.

§          Section 10     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 11     concludes the findings of the EIA Study.

§          Section 12     presents the Implementation Schedules of the various environmental issues addressed in the EIA Study.

2.                   Description of the Project

Location of the Project

2.1               The Shuen Wan area is a low-lying land situated to the south of Pat Sin Leng Country Park. It is a relatively undeveloped area, mainly served by Ting Kok Road along the coastline of Plover Cove, Tung Tsz Road and some informal village tracks.  Marshlands and ponds of ecological significance are found within this area.  An area of about 17.5ha to the south of Tung Tsz Road is designated as Conservation Area (CA).  Other than the ecological resources, this area also accommodates a number of village settlements including San Tau Kok Village, Wai Ha Village and Po Sam Pai Village located to the north of Tung Tsz Road, Shuen Wan Chim Uk Village and Shuen Wan Chan Uk Village to the south of Tung Tsz Road.

 

Need of the Project

2.2               The proposed works in Shuen Wan form part of the drainage improvement works under the recommendation made in the DMP Study.  At present, stormwater runoff within the catchment in Shuen Wan, which is of area about 313 ha, will go into the existing Wai Ha River, which runs through the centre of the CA, then via a box culvert underneath Ting Kok Road and finally discharge to Tolo Harbour. 

2.3               The water level at Wai Ha River is subject to tidal effects due to ingress of seawater from Tolo Harbour which may reach up to 4.25mPD.  According to the results of investigation, the low-lying land in the vicinity of Wai Ha River, particularly north of Tung Tsz Road such as Wai Ha village and San Tau Kok village, will be subject to high risk of flooding during severe storm event.  The results of the hydraulic analysis also indicate that the capacity of Wai Ha River is inadequate even under a 1-in-2 year high tide event. 

2.4               As mentioned above, the cause of flooding in the low-lying land in Shuen Wan area is a combined effect of extensive rainwater conveyed into Wai Ha River during severe storm event and ingress of seawater through the existing box culvert during high tide event.  Flooding is considered beneficial to the natural habitat in the CA; however, if the flood level kept increasing and the affected area extended beyond Tung Tsz Road, it would impose high risks to lives and properties of the neighbouring villages with a population over 2,000; thus, flooding in Wai Ha River would need to be controlled. 

2.5               Based on the past record, during the period from July 1999 to June 2003, 22 Nos. complaints about flooding at Shuen Wan area were received by the Drainage Complaints Information System.  The flooding in Shuen Wan area would disrupt the traffic along Tung Tsz Road, which is the only access to the villages located in the Tung Tsz and Wai Ha areas.  As a result, the villages would be isolated by the inundation and this incurs an unacceptable risk to life and may cause extensive damage to the properties.  

2.6               The potential consequences of such flooding include:-

§          Risk to life;

§          Damage to property ;

§          Nuisance to public;

§          Disruption to traffic; and

§          Psychological stress.

2.7               If the improvement works under this Project do not proceed, the high flooding risks to the villages would persist in this area.  Therefore, engineering works proposed in this Project are necessary to provide adequate flood relief. 

Scope of the Project

2.8               The objective of this project in Shuen Wan area is to develop an optimum solution to relieve the flooding problems there.  To provide a long-term solution, it has been proposed to divert a large portion of the stormwater from upstream away to avoid this excessive runoff getting into the low-lying area to further amplify the extent of flooding during extreme storm and tide events.  The scope of the proposed drainage improvement works in Shuen Wan includes:-

Ø           Construction of a 1000m long 3m x 2.5m twin-cell box culvert along Tung Tsz Road

Ø           Replacement of existing gates by automatic mechanical gates at the mouth of Wai Ha River

Ø           Construction of a drainage pipe of 280m long and 1200mm in diameter near Wai Ha Village

Ø           Construction of a flood relief drain of 260m long and 2100mm in diameter along Ting Kok Road

Ø           Construction of a floodwater pumping station of about 10m high at Shuen Wan

2.9               The design principle of the drainage improvement works in Shuen Wan is described in the following.

Ø                       Under normal situation and when the rainfall is not so severe, the existing river within the CA (Wai Ha River) will convey the entire runoff. 

Ø                       During severe storm and high tide events, the flow as well as the water depth in Wai Ha River will increase.  When the tide level has reached the specified level, the proposed automatic mechanical gates installed at the mouth of Wai Ha River will be closed to prevent the ingress of further seawater into the low-lying land in the vicinity of Wai Ha River.  The triggering level of the gate closure will be determined from the results of the hydraulic analysis of the whole Shuen Wan area, with the use of the hydraulic modeling, such that further increase in water level will jeopardize the safety of the nearby residents. 

Ø                       The water level in Wai Ha River will continue to rise due to the closure of the mechanical gate at the exit with the increasing runoff due to the heavy rainfall.  At its upstream near Tung Tsz Shan Road and Wai Ha Village, an overflow chamber will be constructed as the inlet of the box culvert.  When the water level raises above the weir which is constructed to a pre-determined level according to the hydraulic analysis as mentioned above, excessive stormwater will overflow into the chamber which will then be conveyed to the box culvert, which serve as a bypass, underneath Tung Tsz Road and Ting Kok Road and discharge to Tolo Harbour directly while the remaining flow will still be running along the existing Wai Ha River. 

Ø                       The box culvert will be designed with a capacity sufficient for conveying the overflow, which may be up to two-third of the entire runoff from the upper catchment of Wai Ha River under a 1 in 50 year storm event. 

Ø                       At the same time, the runoff water will accumulate behind the mechanical gate and the water level will build up.  When it reaches a pre-determined level it will be diverted through a flood relief pipe installed underneath Ting Kok Road to a floodwater pumping station at the east side of Ting Kok Road for discharging to the sea. 

Ø                       After the severe storm and tide events have passed and with the release by both the box culvert and the floodwater pumping station, the tide level as well as the water level in both sides of the mechanical gates at the mouth of Wai Ha River will drop and soon return to normal.  The mechanical gate will be opened and the runoff water will run through Wai Ha River as before and discharge into the Tolo Harbour.  Figure 1.5 shows the general layout of the proposed works. 

Ø                       As such, the runoff from the whole Shuen Wan catchment will still be conveyed by the existing Wai Ha River and the CA will not be dried up at all times, and the inter-tidal characteristics of the CA can still be maintained during normal situation when the rainfall is not severe and the tide level is not high.

 

Consideration of Alternative Drainage Options

2.10            The following drainage options have been considered for relieving flooding at Shuen Wan before concluding the current design. 

Option 1        Do Nothing – No engineering works to the existing drainage system will be implemented under this option. Regular maintenance including desilting will be carried out to Wai Ha River.

Option 2        Floodwall (or Protection Embankment) – Construction of a floodwall along south-east side of Tung Tsz Road or raising road level of Tung Tsz Road to retain floodwater from Wai Ha River during rainstorm event.  Runoff generated at  the northern side of Tung Tsz Road will be collected by a surface drain and convey to the proposed pumping station located to the east of Ting Kok Road and discharged to Tolo Harbour.

Option 3        Upgrading of Wai Ha River – Widening and raising embankment at downstream of Wai Ha River to retain floodwater and prevent its overflow during rainstorm event.

Option 4        Inverted Siphon – Construction of inverted siphon by means of trenchless method passing underneath the CA to intercept the excessive runoff coming from upstream of Wai Ha River. The intercepted runoff will then be conveyed to a proposed medium scale pumping station located to the east of Ting Kok Road. In order to prevent building up of water level in Wai Ha area by ingress of tidal water, a mechanical gate is proposed at the outfall of Wai Ha River. At the same time a diversion drain is proposed along Ting Kok Road to convey the residual runoff to the proposed pumping station for discharge.

Option 5        Large Scale Pumping Station – Construction of a large scale pumping station, which pumping capacity is adequate to handle stormwater generated within Shuen Wan Catchment, to discharge the floodwater to Tolo Harbour.

Option 6        Box Culvert – The scope of works of this option is outlined in para. 2.8.

 

2.11            The above alternatives have been examined and evaluated from different perspectives.  The results of our evaluation in terms of technical practicality are presented in Table 2.1 below:-


 

Table 2.1  Evaluation of Alternative for Drainage Improvement Works in Shuen Wan

DRAINAGE OPTION

EVALUATION

PRACTICALITY OF THE OPTION

Do nothing

Flooding problems will persist in long run.  Regular maintenance including desilting works could not resolve the problem.

Not practicable

Floodwall

Floodwall will effectively prevent the residential areas to the north of Tung Tsz Road from flooding.  However, this option will reduce the freeboard of flood level for the residential area in the southern side of Wai Ha River.

Practicable

 

Upgrading of Wai Ha River

Shuen Wan area is a low lying area, it would be necessary to extend the width of existing Wai Ha River to about 20m in order to provide the necessary hydraulic capacity and resolve the flooding problems.  Wai Ha River is located in the middle of the CA and the proposed construction works within CA would induce severe adverse environmental impact, despite there is a need to resume substantial amount of private land within the CA for the widening works.

Not practicable

Inverted Siphon

Inverted siphon is able to serve the purpose by diverting the runoff collected in the upstream away from Wai Ha River.  However, there would be significant problems on sedimentation inside the inverted siphon and it will be very difficult to carry out maintenance works inside the inverted siphon during emergency situation.  Furthermore, there will be high risk of loss of ground water during construction of the tunnel, in the form of inverted siphon, which may seriously affect the habitat of the CA. 

Not practicable

Large Scale Pumping Station

With sufficient pumping capacity, a large scale pumping station at downstream of Wai Ha River will effectively solve the flooding problems.  However, such a huge pumping station would consume enormous amount of energy.  In addition, the risk of flooding is still high as the whole scheme relies solely on the functioning of the pumping station and the consequence of any failure, such as power supply, would be disastrous.

Not practicable

Box Culvert

Box culvert will effectively divert the runoff collected at upstream away from Wai Ha River.  This option will also provide extra protection to the residents at the southern side of Wai Ha River.

Practicable

 

2.12            In view of the above, only the floodwall and the box culvert options are considered practicable in solving the flooding problems in Shuen Wan. 

2.13            A comparison of environmental impacts between the box culvert and floodwall options are shown in Table 2.2 below.

 

Table 2.2       Comparison of Environmental Impacts from the Practicable Options

Drainage Options

Box Culvert

Floodwall

Total Area of Marshland

in Study Area

16.2ha

Area of Marshland to be affected / Percentage of Affected Area

0.3ha / 1.9%

0.28ha / 1.7%

Total Area of CA

in Study Area

17.5ha

Area of CA to be affected / Percentage of Affected Area

0.5ha / 2.9%

0.22ha / 1.3%

Ecological Impact

The works will encroach on the northern boundary of the CA which will impose direct ecological impacts on the habitat along the fringe of the CA. 

About 100m of the box culvert will be constructed adjacent to Wai Ha River. 

The works will encroach on the northern boundary of the CA which will impose direct ecological impacts on the habitat along the fringe of the CA.

Noise Impact

The works site is close to residential area, which will inevitably induce noise impact during construction stage.

The works site is close to residential area, which will inevitably induce noise impact during construction stage.

Visual Impact

This option will not create visual impact to the public.

The floodwall or the protection embankment acts like a barrier which imposes adverse visual impact to the local residents.

 

2.14            It can be seen that the scale of environment impacts (particularly in ecological aspect) arising from the two options are very similar.  For example, these two options both affect the fringe of the CA, and the works extents of both options only encroach on small percentages (1.3% to 2.9%) of the marshland and the CA in the study area. 

2.15            The floodwall option is the preferred scheme in the previous study because of economic reasons.  However, after lengthy consultations with the District Council members and local representatives, it is revealed that the construction of floodwall was strongly opposed because the floodwall would result in adverse visual impact and was alleged to affect the “Fung Shui” of the villages in the vicinity.  The strong opposition makes this floodwall option socially unfeasible.  The box culvert scheme is considered to be more favourable after taking social consideration into account as the adverse visual impacts incurred by the box culvert option are mostly temporary.  By implementation of appropriate mitigation measures, the impacts can be mitigated and the residual visual impact is considered acceptable.

2.16            Although the floodwall and box culvert options would involve construction works to be carried out along Tung Tsz Road, these two alternatives have different approaches in tackling the flooding problems in Shuen Wan.  The floodwall option would allow flooding to continue as before, but a physical barrier would be provided to prevent the extension of flooding area beyond the barrier.  On the other hand, the box culvert would also allow certain extent of flooding to happen, but a large portion of runoff would be diverted before getting into the low-lying area during heavy rainstorm which is considered to be a more sustainable solution in resolving the flooding problem.

2.17            Therefore, to improve the current flood protection standard of the drainage system in Shuen Wan, the preferred option is the box culvert option.  This option will increase the drainage capacity while retaining majority of the river ecology at Wai Ha River, minimizing disturbance to the CA, visual intrusion and environmental impacts overall. 

Recommendations on Preliminary Design of Drainage Improvement Works

2.18            The Project has been designed in accordance with DSD Stormwater Drainage Manual, DSD Technical Circular No. 2/2004 “Protection of natural rivers and streams from adverse impacts arising from construction works” and ETWB TC(W) No. 5/2005 “Protection of natural streams/rivers from adverse impacts arising from construction works”.  The proposed drainage system is classified as “Main Rural Drainage Channel” with a design return period of 1 in 50 years.

2.19            The design of the box culvert alignment has taken into account two key constraints: (1) Tung Tsz Road is the sole access to several villages located in the Shuen Wan area. Its traffic needs to be maintained in order to minimize the disruption to the local residents during construction stage of the Project; (2) its encroachment to the nearby marshland/Conservation Area should be minimised as far as possible.  To strike a balance between these two requirements, the proposed box-culvert will be constructed partially underneath Tung Tsz Road.  By doing so, its traffic can be maintained throughout the construction stage of the Project by maintaining a minimum road width of about 3.5m for the two way traffics.  However, part of the works would inevitably affect a small area of the marsh habitat adjoining Tung Tsz Road.  The ecological value of this part of the marsh to wildlife is reduced by disturbance from vehicular and pedestrian traffic on Tung Tsz Road.  Appropriate measures have been recommended (refer to Section 7) to mitigate the ecological impact.

2.20            Due to the low lying nature of the Wai Ha area (the level at Tung Tsz Road is around 3.3mPD), the residual runoff collected by the drainage system cannot be discharged to Tolo Harbour by gravity.  Therefore, a pumping station is proposed to pump the collected stormwater to Tolo Harbour. 

2.21            The proposed mechanical gate is necessary to provide effective control of the backflow of sea water to Wai Ha River during high tide condition.  At the same time, the diversion drain laid along Ting Kok Road is essential to divert the residual water to the proposed pumping station in order to maintain water level in the Wai Ha area within a certain level.  These works would not give rise to insurmountable environmental impacts during construction and operation phases of the Project.

2.22            The proposed relief drain pipe at the northern side of Wai Ha Village would run through the village in the previous design.  If this option was adopted, excessive construction noise impact at the village houses would be envisaged.  About 54 dwellings would be exposed to elevated construction noise levels even with extensive noise mitigation measures in place.  Under the chosen scheme, the relief drain pipe will be laid along the northeast side of the village and the affected dwellings will be reduced to about 4 with the use of alternative quieter construction method (refer to Section 3).

Consideration of Alternative Construction Method

2.23            A stretch of the proposed box culvert will interfere with the existing Wai Ha River.  Earthworks including excavation by powered mechanical equipment, disposal of excavated soil by dump trucks and compaction by mechanical plant will be required.  This is the commonly adopted construction method.  The impact to environment is generally localized and temporary.  The environmental impacts incurred by this conventional method can be mitigated by appropriated measures like restricting the excavation works to be carried out from October to April to minimize the adverse effects on the rivers.

2.24            Conventional construction method for box culvert involves formworks erection, reinforcement fixing and in-situ concreting.  Alternative method using precast units has also been explored, however, the size of box-culvert is large which means the precast units require a large plant to handle and install. Due to limitation of space, this option is not preferred since the installation of the precast units requires either occupying the remaining traffic lane or acquiring more space in the Conservation Area.

2.25            For the conventional open trench method, trench excavation supported by sheet piling is proposed so as to minimize the encroachment to the existing marshland.  In order to limit the construction noise generated, percussive piling method is restricted for the installation of the sheet pile of the trench support and the piling foundation of the pumping station.

2.26            Majority of the pipe lying works will generally adopt the conventional open-trench method which involves trench excavation using powered mechanical equipment, installation of temporary trench supports and removal of existing pipes if required, followed by the laying of bedding and the proposed pipelines. The trench will then be backfilled, compacted and reinstated to the required standard.

2.27            Even with the adoption of alternative alignment, the pipe laying works would still lie in close proximity to the village houses and would induce unacceptable noise impacts. To minimize the noise impact, alternative construction method mainly involving manual operation and some small size equipment will be adopted for the section of pipe laying works near the village houses at Wai Ha Village.

Project Implementation

2.28            The selection of this scheme was completed in May 2005 and the detailed design will be completed by February 2007.

 

Task Description

Tentative/Actual Completion Date

Selection of the Scheme

May 2005

Detailed Design of Works

February 2007

Commencement of Works Contract

December 2007

Completion of the Contract

June 2010

 

Interactions with Other Projects

2.29            There will be another DSD Sewerage Project of title “Tolo Harbour Sewerage of Unsewered Areas Stage I Phase II” (hereinafter referred to as “the Sewerage Project”) will be carried out in San Tau Kok Village. This project is tentatively scheduled to start in November 2008 and complete in November 2010.  Appendix 2.1 shows the layout plans for the Sewerage Project. 

2.30            Another project which would possibly interface with this project would be the “Development of a Bathing Beach at Lung Mei, Tai Po”.  The construction phase is expected to start in end of 2008 and tentatively scheduled for completion by 2010.  Since its location is distant from (over 2km) the works proposed under this Project and the cumulative disturbance impact resulting from the two Projects is expected to be very minor. 

Summary

2.31            To control the flooding of the low-lying area in Shuen Wan and minimize the risks to lives and properties of the villages, it is necessary to improve the current flood protection standard of the drainage system in Shuen Wan.  Various options including (i) Do Nothing, (ii) Floodwall, (iii) Upgrading of Wai Ha River, (iv) Inverted Siphon, (v) Large Scale Pumping Station and (vi) Box culvert have been considered.  Although the box culvert option would involve construction works encroaching the boundary of the CA in order to maintain the existing accessibility along Tung Tsz Road to various villages in Shuen Wan areas, after carefully considered the practicality and reasonableness of these options as mentioned in Table 2.1 and the social feasibility as discussed in Section 2.15 with a view to fulfil the requirement in EIAO-TM Annex 16 Section 3.1(a), this option has been selected as the preferred option with the necessary mitigation measures to be further investigated and recommended in latter part of this EIA report. 


3.                   CONSTRUCTION NOISE IMPACT

Introduction

3.1               This section presents an assessment of the potential noise impact during the construction phase of the proposed drainage improvement works.

3.2               Noise impacts during the construction phase would mainly be associated with the construction activities and the use of powered mechanical equipment (PME) for construction works.  Appropriate mitigation measures have been recommended, where necessary, to alleviate the potential noise impacts to acceptable levels.

Environmental Legislation, Standards and Guidelines

3.3               The Noise Control Ordinance (NCO) and Environmental Impact Assessment Ordinance (EIAO) provide the statutory framework for noise control.  Assessment procedures and standards are set out in the five Technical Memoranda (TMs) listed below:

§         TM on Environmental Impact Assessment Process (EIAO-TM)

§         TM on Noise from Construction Work other than Percussive Piling (GW-TM)

§         TM on Noise from Percussive Piling (PP-TM)

§         TM on Noise form Construction Work in Designated Areas (DA-TM)

§         TM on Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM)

3.4               Daytime construction noise (excluding percussive piling) between the hours 0700 – 1900 on weekdays is controlled under the EIAO-TM.  Annex 5 of the EIAO-TM sets out the construction noise limits, which are Leq(30 min) 75dB(A) for domestic premises and Leq(30 min) 70dB(A) for schools during normal hours (65dB(A) during examination periods) and all other places where unaided voice communication is required.  Construction activities other than percussive piling using powered mechanical equipment (PME) undertaken at other times (i.e. during restricted hours) are under the control of the NCO.

3.5               According to the preliminary construction programme, no work would be carried out during restricted hours.  Hence, noise impacts associated with the construction of the proposed Project would primarily be assessed against the noise criteria set out in Annex 5 of the EIAO-TM. 

3.6               Based on the available design information for this Project, sheet pile would be driven by non-percussive means.  Therefore the criteria set out in the PP-TM would not be applicable to this Project.  

3.7               In case of any construction activities during restricted hours, or in future should the Contractor confirm the need for percussive piling, it is the Contractor’s responsibility to ensure compliance with the NCO and the relevant TMs. The Contractor will be required to submit CNP application to the Noise Control Authority and abide by any conditions stated in the CNP, should one be issued. 

Description of the Environment

3.8               The vicinity of the Shuen Wan Assessment Area is mostly rural in nature comprising village settlements (e.g. San Tau Kok Village, Po Sam Pai Village, Shuen Wan Chim Uk Village and Wai Ha Village), ponds and marsh areas.  The plant nursery run by the Leisure and Cultural Services Department is situated at the southern side of San Tau Kok Village south of Tung Tsz Road.  The existing noise climate in this area is dominated mostly by traffic noise along Tung Tsz Road and Ting Kok Road.  The ambient noise level is expected to be moderate.

Noise Sensitive Receivers

3.9               Representative noise sensitive receivers (NSRs) within 300m from the project site boundary were identified for noise assessment.  According to Annex 13 of the EIAO-TM, NSRs include the following:

§          Residential uses – all domestic premises including temporary housing

§          Institutional uses – including educational institutions

§          Other uses such as hostels and country parks

3.10            Table 3.1 summarises the selected NSRs for the noise impact assessment. Locations of representative NSRs are illustrated in Figure 3.1.

 

Table 3.1       Representative Noise Sensitive Receivers

NSR

Location

Use

SW1

14, Shuen Wan Chim Uk

Residential

SW2

2A, San Tau Kok

Residential

SW3

63, San Tau Kok

Residential

SW4

59, San Tau Kok

Residential

SW5

150, San Tau Kok

Residential

SW6

191, San Tau Kok

Residential

SW7

51, Wai Ha

Residential

SW8

Block 3A, Treasure Spot Garden

Residential

SW9

Block 15, Treasure Spot Garden

Residential

SW10

31, Wai Ha

Residential

*SWA1

Potential Future NSR at San Tau Kok Village

Residential

*SWA2

Potential Future NSR at Wai Ha

Residential

* denotes for potential future NSR

3.11            The areas adjacent to the proposed box culvert alignment are zoned as “Village” zone according to Outline Zoning Plan No. S/NE-TK/12.  According to the information from Lands Department, there is a possibility that new village houses would be built at land within this zone (see Figure 3.1).  An assessment point, namely SWA1, has been selected to represent the potentially worst affected future NSRs within this village zone for indicative construction noise assessment. The site visit conducted in April 2007 also revealed that several new village houses along Tung Tsz Road were under construction. Based on the location of these newly identified NSRs, an assessment point, namely SWA2 (between chainage 200m300m), has been added to the construction noise calculation. Several other new village houses were recorded near chainage 100m and between chainage 500m600m.  However they were not considered to be worst affected by noise impacts from the proposed works.  Hence noise impacts at those new village houses would be represented by adjacent assessment points which would be located closer to the works area.  The location of this assessment point is shown in Figure 3.1.

Assessment Methodology

3.12            The methodology outlined in the Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM) was adopted for the construction noise assessment, and is summarised below:

§          Locate the NSRs which will most likely be affected by noise from the construction work;

§          Determine the items of Powered Mechanical Equipment (PME) for each discrete construction activity, based on available information or agreed plant inventories;

§          Assign sound power levels (SWLs) to the proposed PME according to the GW-TM or other sources;

§          Calculate distance attenuation and screening effects to NSRs from notional noise source;

§          Predict construction noise levels at NSRs in the absence of any mitigation measures; and

§          Include a 3 dB(A) façade correction to the predicted noise levels in order to account for the façade effect at each NSR.

 

3.13            Sound Power Levels (SWLs) of the equipment have been derived from Table 3 of the GW-TM.  Where no Sound Power Level (SWL) is given in the GW-TM, reference has been made to BS 5228: Part 1:1997 Noise Control on Construction and Open Sites and previous similar studies or measurements taken at other sites in Hong Kong.

3.14            Correction due to distance attenuation was determined using the following standard formula:

 

Distance Attenuation in dB(A) = 20 log D + 8      where D is the distance in meters

 

3.15            All construction tasks undertaken within 300m of a given NSR at the same period were considered to contribute to cumulative noise impact at that NSR.  Impact of noise sources from areas greater than this distance would be considered minor, and would thus be excluded from the assessment.

3.16            The construction noise impact was assessed based on the worst case scenario where all PME proposed for each construction task would be in use concurrently at any given time unless otherwise stated.  The proposed construction plant lists for the unmitigated and mitigated scenarios are provided in Appendices 3.1 and 3.2 respectively.

3.17            In order to provide more realistic calculations of the construction noise levels, reasonable assumptions for on-time percentage of certain PME have been made, as shown below.

 

Table 3.2          On-time Percentage Assumptions for Certain Items of PME

PME

Assumed on–time Percentages

Excavator / Loader

70

Dump Truck

30

Concrete Lorry Mixer

50

Vibratory Poker

70

Bar Bender / Cutter

70

Power Rammer

70

Breaker, Excavator Mounted (Hydraulic)

70

Vibratory Roller

50

Air Compressor

50

Submersible Pump

100

Hand held breaker

30

 

3.18            The Project Proponent’s design engineer confirmed that the assumption of on-time percentage and number of PME are considered to be practical in completing the works within the schedule.

3.19            Based on the above assumptions, the total SWL for each construction activity has been calculated, and is presented in Appendix 3.1.

Identification of Impacts

3.20            The construction tasks and sub-tasks for the proposed drainage improvement works at various sites together with the envisaged duration of each task are presented in Table 3.3.

 

Table 3.3     Construction Tasks for the Proposed Drainage Improvement Works

Construction Tasks

Construction Sub-tasks

Duration (Month)

Site Clearance

--

0 – 3

Box Culvert

·      Excavation and Concreting

·      Backfilling and Road Restatement

4 – 12 (Ch 0 – 350)

13 – 21 (Ch 350 – 700)

22 – 30 (Ch 700 – 1013)

Pumping Station

·      Excavation

·      Construction of Pumping Station

·      Backfilling

4 – 22

Pipe Laying at Wai Ha

·      Excavation

·      Laying Pipe

·      Backfilling

4 – 14

Pipe Laying at Ting Kok Road

·      Excavation

·      Laying Pipe

·      Backfilling

4 – 14

Installation of Mechanical Gate

--

15 - 20

 

3.21            The potential source of noise impact during the construction phase of the Project would be the use of PME for various construction activities as indicated in Table 3.3.  The SWLs of PME for various construction activities are given in Appendix 3.1.

3.22            In general, the proposed construction activities would be small in scale.  However, since NSRs were identified in close proximity to the proposed work areas, adverse noise impacts due to the use of PME would likely be expected at these receivers if no noise control measures are implemented.

Prediction and Evaluation of Impacts

3.23            Based on the proposed plant inventory as shown in Appendix 3.1, cumulative noise impacts arising from various construction activities were predicted.

3.24            Ranges of unmitigated construction noise levels at representative NSRs are presented in Table 3.4.  Predicted construction noise levels and detailed calculation of construction noise level for the unmitigated scenario are provided in Appendix 3.1.

 

Table 3.4       Ranges of Unmitigated Construction Noise Levels

NSR ID

Range of Predicted Noise Levels, dB(A)

EIAO-TM Normal Daytime Construction Noise Criteria, dB(A)

SW1

60 – 88

75

SW2

65 – 78

75

SW3

66 – 81

75

SW4

65 – 84

75

SW5

65 – 89

75

SW6

62 – 89

75

SW7

66 – 86

75

SW8

65 – 101

75

SW9

63105

75

SW10

5996

75

*SWA1

66 – 93

75

*SWA2

68 – 91

75

* denotes for potential future NSRs

3.25            The assessment results showed that predicted cumulative noise levels at representative NSRs would range from 59 to 105dB(A).  The maximum level of exceedance predicted would be about 30dB(A).  Mitigation measures would be considered necessary in order to abate the construction noise impacts.

Mitigation of Adverse Environmental Impacts

3.26            The need for minimizing potential construction noise impacts on the NSRs in the vicinity of the works area for this Project has been considered during the design of the project, with the following key features included:

§          Minimise the number of PME

§          Works would be implemented in phases, which could also help to reduce the number of PME required to be sit on-site

3.27            The adopted scheme as shown in Figure 1.5 has been developed by striking a balance on the need for undertaking the drainage improvement works to alleviate the risk of flooding in the concerned area, for minimising the impacts to the Conservation Area nearby, as well as for addressing concerns from locals. 

3.28            Although the construction noise impacts would be expected to be localised and temporary, alternative design options have been developed to address the construction noise issues.  The discussion on alternative design consideration is presented in Section 2.

3.29            The construction noise assessment showed that, in the absence of any mitigation measures, there would be exceedance of the construction noise criteria at some of the NSRs.  Various mitigation options have thus been considered, as per guidelines laid down in the Environmental Impact Assessment Ordinance, Guidance Note No. 9/2004 “Preparation of Construction Noise Impact Assessment under the Environmental Impact Assessment Ordinance” (GN 9/2004).  Mitigation measures considered are discussed below.

Good Site Practice

3.30            Although the noise mitigation effects are easily quantifiable and the benefits may vary with site conditions and operating conditions, good site practices are easy to implement and do not impact upon the works schedule.  The site practices listed below should be followed during each phase of construction:

§          Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program;

§          Silencers or mufflers on construction equipment should be utilized and should be properly maintained during the construction program;

§          Mobile plant, if any, should be sited as far from NSRs as possible;

§          Machines and plant (such as trucks) that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;

§          Plant known to emit noise strongly in one direction should, wherever possible, be orientated so that the noise is directed away from the nearby NSRs; and

§          Material stockpiles and other structures should be effectively utilised, wherever practicable, in screening noise from on-site construction activities.

Adoption of Quieter PME

3.31            In order to alleviate the construction impacts on the NSRs, the adoption of quieter PME is recommended.  The type of quieter PME adopted in this assessment is not a must that the Contractors have to use specific items of plant for the construction operations.  The Contractors are allowed to use other type of quiet PME, which have the same total SWL, to meet their needs.

3.32            Noise data of the quieter PME adopted in the assessment were taken from the BS5228: Part 1:1997 (Appendix 3.2) and from the EPD website.  A list of quieter PME recommended for adoption during the construction phase is presented in Table 3.5.

Table 3.5         Quieter PME Recommended for Adoption during Construction Phase

PME

Reference

SWL

Excavator / Loader

BS C3/97

105

Dump Truck

BS C9/39

103

Concrete Lorry Mixer

BS C6/23

100

Vibratory Poker

BS C6/32

100

Breaker, Excavator Mounted (Hydraulic)

BS C8/12

106

Vibratory Roller

Noise data of Quality PME from EPD Website

101

 

Use of Temporary Noise Barrier

3.33            Temporary noise barriers of about 3.5m high would be used mainly for screening of noise from the PME used for the construction of box culvert and site clearance. The Project Proponent’s design engineer has taken into account the space requirement for barrier erection and confirmed the practicality of the use of temporary noise barrier.

3.34            In general, the use of temporary noise barriers can achieve a 5dB(A) reduction for movable plant, 10dB(A) for stationary plant, depending on the line of sight that could be blocked by the barriers when viewed from the NSR.  The noise screening effects of temporary noise barriers considered in this assessment are shown in Appendix 3.2.  Figure 3.2 shows the typical section of the proposed temporary noise barriers used for site clearance and box culvert construction.  Barrier material of surface mass in excess of 7kg/m2 is recommended to achieve the predicted screening effect. 


Further Mitigation Measures

Use of Quieter Alternative Construction Method

3.35            In view of the high noise exceedance level resulted from the proposed pipe laying works at Wai Ha Village, quieter alternative construction method (hereinafter referred to as “the Low Impact Method”) has been proposed.  For this method, PME with lower impact would generally be used (e.g. mini backhoe).  Also the PME would be of smaller in size rendering it possible to be enclosed by noise enclosure to further reduce its noise emission level (see below).  Table 3.6 presents the proposed PME for the Low Impact Method.  The extent of pipe laying works where the Low Impact Method and conventional method would apply is shown in Figure 3.5.

Table 3.6         Plant Inventory for the Low Impact Method

Construction Sub-task

PME

Reference

SWL

Pipe laying at Wai Ha

Excavation

Hand-held breaker

CNP024

108

 

Air compressor

CNP002

102

 

Mini backhoe

CNP082

94

Pipe Laying

Mini backhoe

CNP082

94

 

Vibratory poker

BSC6/32

100

Backfilling

Vibratory poker

BSC6/32

100

 

Vibratory roller

EPD Website: Quality PME

101

 

Noise Enclosures and Temporary Noise Barriers

3.36            To further alleviate the construction noise impact associated from the pipe laying works at Wai Ha, noise enclosure would be used for enclosing the PME as listed in Table 3.6 except the mini backhoe.  The roof panels of the noise enclosure would be removed when the mini backhoe is used and the side panels would form a temporary noise barrier along the periphery of the works area.  The conceptual design of the noise enclosure and the typical section of temporary noise barrier are shown in Figures 3.3 and 3.4 respectively. 

3.37            The noise enclosure can be made of materials with a surface mass of not less than 7kg/m2 to achieve the maximum screening effect.  For ventilation purpose, openings could be provided at the side of the enclosure facing towards the natural hillside and away from the NSRs.  The noise enclosure should be designed to achieve at least 15dB(A) noise reduction for PME.

3.38            The materials for the temporary noise barriers would be the same as that for the noise enclosure as they would be the side panels of the enclosure.  However, should alternative materials be used for the temporary noise barriers, the material should have a surface mass of not less than 7kg/m2.  The barrier should also be designed to achieve at least 5dB (A) noise reduction for the mini backhoe at 1-2/F of NSR SW8-9. 

Mitigated Construction Noise Impacts

3.39            Mitigated construction noise levels were predicted at various NSRs (Appendix 3.2 refers) taking into account the noise reduction provided by the above-mentioned mitigation measures.  Calculation of construction noise for the mitigated scenario is provided in Appendix 3.2.  The approximate extent of the proposed noise mitigation measures is illustrated in Figure 3.5. Ranges of mitigated construction noise levels predicted at representative NSRs are presented in Table 3.7.

 

Table 3.7          Mitigated Construction Noise Levels

NSR ID

Range of Predicted Noise Levels, dB(A)

EIAO-TM Normal Daytime Construction Noise Criteria, dB(A)

SW1

46-74

75

SW2

50-66

75

SW3

57-60

75

SW4

56-63

75

SW5

50-67

75

SW6

47-68

75

SW7

51-65

75

SW8-1/F

50-71

75

SW8-2/F

50-70

75

SW8-3/F

50-69

75

SW8-1-3/F (Conventional Method)

50-71

75

SW9-1/F

48-75

75

SW9-2/F

48-73

75

SW9-3/F

48-71

75

SW9-1-3/F (Conventional Method)

48-66

75

SW10

44-74

75

*SWA1

56-71

75

*SWA2

53-70

75

* denotes for potential future NSRs

3.40            As shown in Table 3.7, with the adoption of the above noise mitigation measures, construction noise levels at all representative NSRs would comply with the EIAO-TM daytime construction noise criteria of 75dB(A).  It was envisaged that there would be no adverse residual impact at all NSRs.

Residual Environmental Impacts

3.41            After implementation of the above-mentioned noise mitigation measures, including the use of alternative quieter PME, construction method (the Low Impact Method), temporary noise barriers and noise enclosure, construction noise levels at all the identified NSRs would comply with the EIAO-TM daytime construction noise criteria and no adverse residual impact would be expected.

3.42            To ensure that the construction noise impacts would be well controlled, good site practices and noise management measures should be strictly implemented within all construction sites.

Cumulative Construction Noise Impact

3.43            A sewerage project, namely “Tolo Harbour Sewerage of Unsewered Areas Stage 1 Phase IIC” (hereinafter referred to as “the Sewerage Project”), was in design review stage.  The construction works associated with this project were planned to start in November 2008 and for completion in November 2010, and would likely coincide with this Project.  Minor excavation and pipe laying works would be carried out at San Tau Kok and Po Sam Pai (which is located to the north of San Tau Kok) for this sewerage project.   Layout plans for the Sewerage Project are provided in Appendix 2.1. 

3.44            As shown in Appendix 2.1, the Sewerage Project in San Tau Kok and Po Sam Pai which would likely be carried out concurrently with the proposed Project would give rise to cumulative construction noise impacts on NSRs.  In particular, NSRs SW2 – SW6 at San Tau Kok Village located to the south of the works area of the Sewerage Project could be subject to cumulative construction noise impacts. 

3.45            Details of the construction programme as well as plant inventory for the Sewerage Project were not available at the time of reporting.  However, having reviewed the layout plan for the Sewerage Project, it is expected that construction activities associated with this Sewerage Project would be similar to those for the proposed Project but in a smaller scale.  The Sewerage Project would be unlikely to result in insurmountable construction noise impacts at the NSRs identified for this Project. 

3.46            With the recommended mitigation measures in place, the maximum construction noise levels at NSRs SW2-SW6 would be 68dB(A), which would be well below the EIAO-TM construction noise criteria for non-restricted hours.  Having regard to this, it would be unlikely that the two projects would give rise to adverse cumulative construction noise impacts at the concerned NSRs. 

3.47            Assuming that the maximum construction noise level due to the Sewerage Project would be similar to that predicted for the proposed Project (i.e. 68dB(A)) given their nature of works would be similar, the maximum predicted cumulative construction noise levels at NSRs could be calculated by the following equation in accordance with standard acoustic principle:

Cumulative construction noise levels from the two projects, dB(A)

= 10 log [10 (N1/10) + 10 (N2/10) ]

Where

N1 =  maximum predicted construction noise level due to the proposed Project

= 68dB(A)

 

N2 =  assumed maximum construction noise level due to the Sewerage Project

=  N1 = 68dB(A)

Cumulative construction noise levels from the two projects, dB(A)

= 10 log [10 (68/10) + 10 (68/10) ]

= 71dB(A)

3.48            As shown above, predicted cumulative construction noise levels would be about 71dB(A), which would comply with the EIAO-TM noise criteria for normal daytime construction activities.  Early planning of the works schedule between Contractors for the two projects is recommended to minimize potential cumulative construction noise impact at the NSRs at San Tau Kok Village (SW2 – SW6).  No exceedance of cumulative noise level of 75dB(A) would be resulted from the two projects.

Environmental Monitoring and Audit

3.49            Due to the potential construction noise impact to the nearby NSRs, it is recommended that EM&A for construction noise be carried out throughout the construction period of the Project.  To ensure implementation of construction phase mitigation measures with consideration of practicability in local levels, the noise mitigation measures should be reviewed during the construction phase.  The changes or alternative proposals should be reviewed and verified by the Environmental Team (ET) and Independent Environmental Checker (IEC).

Conclusion

3.50            Noise arising from the construction activities of the proposed Project would have potential impacts on the NSRs located in the vicinity of the proposed work areas.  Unmitigated construction noise levels at the representative NSRs were predicted to be in the range of 59–105 dB(A), exceeding the EIAO-TM daytime construction noise limit of 75dB(A).

3.51            To mitigate the noise impacts due to the construction activities, mitigation measures including good site practices, quieter PME, temporary noise barriers, quieter alternative construction method (the Low Impact Method), noise enclosure and careful programming of noisy activities were considered. After implementing these mitigation measures, there would not be any exceedance of the EIAO-TM daytime construction noise limit of 75dB(A). Thus, no adverse residual impact was predicted.

3.52            The Sewerage Project at San Tau Kok and Po Sam Pai would be conducted concurrently with the proposed Project.  With the implementation of mitigation measures, the two projects would unlikely have adverse cumulative construction noise impacts at the concerned NSRs at San Tau Kok Village given the scale of works of the Sewerage Project would be small and predicted construction noise levels due to the proposed Project would be well below the EIAO-TM daytime construction noise criteria.   To minimize the cumulative noise impact, early planning of the works schedule between Contractors for the two projects is recommended to minimize potential cumulative construction noise impact at the NSRs at San Tau Kok Village (SW2 – SW6).  It is expected that no exceedance of cumulative noise level of 75dB(A) at the concerned NSRs at San Tau Kok Village would be resulted from these two projects.


4.                   AIR QUALITY IMPACT 

Introduction

4.1               This Section presents an assessment of the potential air quality impacts pertinent to the construction phase of the Project, and recommends appropriate mitigation measures, where necessary.

4.2               Air quality impacts during construction phase would be mainly associated with dust and vehicle emissions from various construction activities.  Appropriate mitigation measures have been recommended, where necessary, to alleviate the potential construction dust impacts to acceptable levels.

Environmental Legislation, Standards and Guidelines

4.3               The criteria for evaluating air quality impacts and the guidelines for air quality assessment are laid down in Annexes 4 and 12 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM), respectively.

4.4               The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of sources.  The Ordinance includes a number of Air Quality Objectives (AQOs) which stipulate maximum concentrations for a range of pollutants, of which total suspended particulates (TSP) are relevant to this study.  The relevant AQOs are listed in Table 4.1.

 

Table 4.1         Hong Kong Air Quality Objectives

Parameter

Maximum Average Concentration (µgm-3)1

 

24-Hour2

Annual3

TSP

260

80

1.  Measured at 298 K and 101.325 kPa.

2   Not to be exceeded more than once per year.

3.   Arithmetic mean.

 

4.5               The EIAO-TM also stipulates that the hourly TSP level at sensitive receivers should not exceed 500 µgm-3 TSP (measured at 25°C and one atmosphere) for construction dust impact assessment.  Mitigation measures from construction sites have been specified in the Air Pollution Control (Construction Dust) Regulations.

Description of the Environment

4.6               The Project is located in the Shuen Wan Area in Tai Po.   According to the site survey conducted in November, 2005, the Project site was found to be mostly rural in nature comprising village settlements, ponds and marsh areas. 

4.7               The existing air quality near the Project site would mainly be affected by emissions from vehicular traffic on nearby road networks, including Ting Kok Road and Tung Tsz Road.  In the absence of in-situ monitoring data, reference is made to the annual average concentrations of major air pollutants measured at EPD’s nearest monitoring stations (Tai Po) for the last 5 years.  The 5-year annual averages TSP levels at Tai Po station are 65µgm-3 according to Air Quality in Hong Kong 2000-2003 and 2005[1].

Air Sensitive Receivers

4.8               According to Annex 12 of the EIAO-TM, domestic premises, hotel, hostel, hospital, clinic, nursery, temporary housing accommodation, school, educational institution, office, factory, shop, shopping center, place of public worship, library, court of law, sports stadium or performing arts center are considered as air sensitive receivers (ASRs).  Any other premises or places having similar sensitivity (in terms of duration or number of people affected) to the air pollutants may also be considered to be sensitive receivers.

4.9               Based on the criteria set out in the EIAO-TM, representative ASRs have been identified close to the Project site.  A brief description of the representative ASRs is presented in Table 4.2 and the corresponding locations are shown on Figure 4.1.

 

Table 4.2       Representative Air Sensitive Receivers

ASR

Location

Nearest distance between ASR and the works boundary (m)

Land Use

ASW1

14, Shuen Wan Chim Uk

10

Residential

ASW2

2A, San Tau Kok

90

Residential

ASW3

63, San Tau Kok

40

Residential

ASW4

59, San Tau Kok

30

Residential

ASW5

150, San Tau Kok

15

Residential

ASW6

191, San Tau Kok

15

Residential

ASW7

51, Wai Ha

25

Residential

ASW8

Block 3A, Treasure Spot Garden

2

Residential

ASW9

Block 15, Treasure Spot Garden

2

Residential

ASW10

31, Wai Ha

5

Residential

*SWA1

Potential Future NSR at San Tau Kok Village