Environmental Impact Assessment

for

 

Proposed Headquarters and Bus Maintenance Depot in Chai Wan

 
 

Reference      :
 

R0178-3.01
 

Client             :
 

Date                :
 

June 2001
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Citybus Limited
 
 

 

 

 

Project Consultancy Team:

Ling Chan + Partners Limited

in association with

CH2M HILL (China) Limited

Wong Pak Lam & Associates Limited

Thomas Anderson & Partners Limited

LLA Consultancy Limited

MDA Hong Kong Limited

Edaw Earthasia Limited

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


TABLE OF CONTENTS

1.         Introduction

1.1       Project Need

1.2       Project Design & Technical Assessments

1.3       Objectives of the Assessment

1.4       Public Inputs

1.5       Structures of the EIA Report

2.         Site selection HistoRy

2.1       Identification of Alternative Development Sites

2.2       Selection of Preferred Site

2.3       Required Technical Assessments of Selected Site

3.         Project Description and key environmental issues identification

3.1       The Subject Site and its Environs

3.2       Bus Depot Design

3.3       Implementation Programme

3.4       Identification of Key Environmental Issues

4.         Air Quality Impact Assessment

4.1       Introduction

4.2       Assessment Criteria

4.3       Air Sensitive Receivers (ASRs)

4.4       Baseline Condition

4.5       Construction Dust Emission Impact Assessment

4.6       Vehicular Emission Impact Assessment

4.7       Environmental Monitoring & Audit (EM&A) Requirements

4.8       Assessment Conclusions

5.         Noise Impact Assessment

5.1       Introduction

5.2       Study Area and Noise Sensitive Receivers (NSRs)

5.3       Construction Noise Impact Assessment

5.4       Operational Fixed Noise Impact Assessment

5.5       Operational Off-site Traffic Noise Impact Assessment

5.6       Conclusion

6.         Waste Management

6.1       Introduction

6.2       Legislation and Guidelines

6.3       Construction Waste Impacts

6.4       Construction Waste EM&A Requirements

6.5       Operational Phase Waste Impact

6.6       Conclusion

7.         Land Contamination Prevention

7.1       Introduction

7.2       Baseline Condition

7.3       Potential Land Contamination Sources

7.4       Land Contamination Preventive Measures

7.5       Conclusion

8.         Hazard Impact

8.1       Introduction

8.2       Quantitative Risk Assessment

8.3       Population Data

8.4       Meteorology

8.5       Local Topography

8.6       Ignition Source

8.7       Hazard Events

8.8       Safety System and Fire Protection/Fighting System Failure

8.9       Summary of Frequency of Failure Cases Adopted

8.10     Hazard Occurrence

8.11     Consequence of Hazard Occurrence

8.12     Consequence Analysis

8.13     Risk Summation

8.14     Assessment Finding and Discussion

8.15     Conclusion

9.         Landscape and Visual Impact Assessment

9.1       Introduction

9.2       Landscape Impact Assessment

9.3       Visual Impact

10.       Wastewater Treatment and Disposal Facilities

10.1     Relevant Standards and Guidelines

10.2     Wastewater Treatment and Disposal

11.       sUMMARY OF eNVIRONMENTAL OUTCOMEs

11.1     Introduction

11.2     Environmental Benefits

12.       Overall Conclusion

12.1     Introduction

12.2     Key Environmental Issues

12.3     Air Quality Impact Assessment

12.4     Noise Impact Assessment

12.5     Waste Management

12.6     Land Contamination Prevention

12.7     Hazard Impact

12.8     Landscape and visual impacts

12.9     Wastewater Treatment and Disposal Facilities

12.10   Overall Conclusion


 LIST OF FIGURES

 

Figure 1‑1    Location of proposed Headquarters and Bus Maintenance Depot in Chai Wan. 1-5

Figure 2‑1    Locations the small patches of undeveloped sites (I, II and III) in A Kung Ngam Industrial Area. Error! Bookmark not defined.

Figure 2‑2    Locations of Sites A, B and C in Chai Wan East Industrial Area. Error! Bookmark not defined.

Figure 3‑1    Outline Zoning Plan No. S/H20/11 (Extract). Error! Bookmark not defined.

Figure 3‑2    Proposed Locations of Vehicular Access and Routing Plan. Error! Bookmark not defined.

Figure 3‑3    Preliminary Floor Layout Plan – Ground Floor and Upper Ground Floor Plan. Error! Bookmark not defined.

Figure 3‑4    Preliminary Floor Layout Plan – First Floor Plan. Error! Bookmark not defined.

Figure 3‑5    Preliminary Floor Layout Plan – Second Floor Plan. Error! Bookmark not defined.

Figure 3‑6    Preliminary Floor Layout Plan – Third Floor Plan. Error! Bookmark not defined.

Figure 3‑7    Preliminary Floor Layout Plan – Fourth & Fifth Floor Plan. Error! Bookmark not defined.

Figure 3‑8    Cross Section of the Proposed Headquarters and Bus Maintenance Depot Development Error! Bookmark not defined.

Figure 3‑9    Preliminary Construction Programme. Error! Bookmark not defined.

Figure 3‑10   Air Quality/ Noise Impact Assessments - Boundary of Study Area. Error! Bookmark not defined.

Figure 4‑1    Location of the Representative Assessment Points, Air Quality Impact Assessment Error! Bookmark not defined.

Figure 4‑2    Mitigated 1-hour TSP Concentrations predicted at 1.5m above Ground, Construction Dust Impact Assessment Error! Bookmark not defined.

Figure 4‑3    Mitigated 24-hour TSP Concentrations predicted at 1.5m above Ground, Construction Dust Impact Assessment Error! Bookmark not defined.

Figure 4‑4    Cumulative 1-hour NO2 Concentrations predicted at worst-affected height (10m above ground) resulted from open road & depots emission. Error! Bookmark not defined.

Figure 4‑5    Predicted 1-hour CO Concentrations predicted at worst-affected height (10m above ground) resulted from open road & depots emission. Error! Bookmark not defined.

Figure 4‑6    Predicted 24-hour RSP Concentrations predicted at worst-affected height (10m above ground) resulted from open road & depots emission. Error! Bookmark not defined.

Figure 4‑7    Predicted 24-hour NO2 Concentrations predicted at worst-affected height (10m above ground) resulted from open road & depots emission. Error! Bookmark not defined.

Figure 5‑1    Locations of Representative Assessment Points selected for Noise Impact Assessment Error! Bookmark not defined.

Figure 5‑2    Location of the 6m high noise barrier recommended during the construction phase at the western boundary of the site along Shing Tai Road. Error! Bookmark not defined.

Figure 5‑3    Preliminary Design of the Temporary Noise Barrier erected at the western site boundary along Shing Tai Road. Error! Bookmark not defined.

Figure 5‑4    Location of the recommended 3m High Solid Vertical Wall on the Roof Level of the Bus Depot Error! Bookmark not defined.

Figure 8‑1    The 150m Study Area surrounding the Petrol/LPG Filling Station. Error! Bookmark not defined.

Figure 8‑2    Layout of a typical Petrol Cum LPG Filling Station. Error! Bookmark not defined.

Figure 8‑3    Predicted Societal Risk in the vicinity of the LPG/Petrol Filling Station. Error! Bookmark not defined.

Figure 8‑4    Predicted Individual Risk in the vicinity of the LPG/Petrol Filling Station. Error! Bookmark not defined.

 

 

 

LIST OF TABLES

 

Table 2‑1     Nearest Distance of Site B and C from the nearby Sensitive Receivers

Table 4‑1     Hong Kong Air Quality Objectives

Table 4‑2     Representative Assessment Points

Table 4‑3      Background Air Pollutant Levels Adopted in the Assessment

Table 4‑4     Maximum 1-hour TSP Concentrations predicted at the ASRs

Table 4‑5     24-hour Average TSP Concentrations predicted at the ASRs

Table 4‑6     Maximum 1-hour TSP Concentrations predicted at the ASRs

Table 4‑7     24-hour Average TSP Concentrations predicted at the ASRs

Table 4‑8     Year 2018 Traffic Forecast during the early Morning Peak Leaving

Table 4‑9     Year 2018 Traffic Forecast during the Nighttime Peak Return

Table 4‑10    2003 Vehicular Emission Factors

Table 4‑11    Predicted Pollutant Concentrations from Open Road Vehicular Emission

Table 4‑12    Worst-case Bus Flow entering/ leaving the Depot Building

Table 4‑13    Emission Factor for Buses inside Depot

Table 4‑14    Bus Depot Air Pollutant Emission Rates

Table 4‑15    Predicted pollutant concentrations due to emissions from Citybus Depot and NWFB Depot

Table 4‑16    Cumulative Pollutant Concentrations from Open Road Traffic Emission & Depots Emission

Table 5‑1        Representative Assessment Points selected for Noise Impact Assessment

Table 5‑2     Noise Limits for Daytime Construction Activities

Table 5‑3     PME Inventory for Foundation Construction Works

Table 5‑4     Inventory of PMEs during Sheet Piling and Pile Cap Construction

Table 5‑5     Inventory of PMEs during Superstructure Construction

Table 5‑6      Unmitigated Noise Levels predicted at the RAPs, Leq(30min.)dB(A)

Table 5‑7     Mitigated Noise Level Predicted at the Representative NSRs (with silenced PMEs)

Table 5‑8     Predicted Noise Level at the Representative NSRs (with silenced PME, phasing of activities and reduction in number of PME operating simultaneously)

Table 5‑9     Mitigated Noise Levels at the RAPs (with silenced PME, phasing of activities and reduction in number of PME, fixed noise barrier and machinery enclosures)

Table 5‑10    Area Sensitivity Ratings of NSRs

Table 5‑11     Identified Noise Sources associated with the Depot Operation

Table 5‑12     Predicted Noise Levels at the NSRs due to Depot Operation

Table 5‑13     Year 2003 Traffic Forecast

Table 5‑14     Year2018 Traffic Forecast

Table 5‑15    Predicted Noise Levels for the “with bus depot” and “without bus depot”scenarios during early morning peak hour (0530 to 0630), L10(1-hr)

Table 5‑16    Predicted Noise Levels for the “with bus depot” and “without bus depot”scenarios during mid-night peak hour (2300 to 0000), L10(1-hr)

Table 5‑17    Predicted Noise Levels for the “with bus depot” and “without bus depot”scenarios during early morning peak hour (0530 to 0630), L10(1-hr)

Table 5‑18    Predicted Noise Levels for the “with bus depot” and “without bus depot”scenarios during mid-night peak hour (2300 to 0000), L10(1-hr)

Table 6‑1     Likely Types and Estimated Quantity of Chemical Wastes to be produced from Depot Operation

Table 8‑1        Safety Valves associated with Pipelines On-site

Table 8‑2        Design Capacity of the Local Road Carriageways adopted in the QRA study

Table 8‑3        Most Frequent Wind Speed-Stability Class Combination

Table 8‑4        Identified Failure case of the LPG Installation

Table 8‑5        Summary of Spontaneous Failure Cases and their Frequency of Occurrences

Table 8‑6        Underground Vessel Loading Failure Cases and their Frequency of Occurrences

Table 8‑7        Underground Vessel Loading Failure Cases and their Frequency of Occurrences

Table 8‑8        External Event and their Frequency of Occurrences

Table 8‑9        Failure Rates of Various Safety Systems

Table 8‑10     Fire Fighting System Failure Cases and their Frequency of Occurrences

Table 8‑11    Summary of Frequency of Failure Cases

Table 8‑12    Estimated Failure Rates for Identified Representative Release Outcomes

Table 8‑13    Release Rate Model Input and Output

Table 8‑14    Hazard Event Outcome for Representative Release Event

Table 8‑15     Hazard Consequence Outcome Frequency

Table 8‑16    Fatal Radiation Exposure Levels (From Probit)

Table 8‑17    Fireball/BLEVE Model Input and Output

Table 8‑18    Release Rate for Liquid Discharge

Table 8‑19    Jet Flame Model Input and Output

Table 8‑20    Dispersion Model Input and Output

Table 8‑21    Events contributed to PLL

Table 9‑1        Summary of the Implementation for the Transplanting Works

Table 11‑1     Environmentally Sensitive Areas and Population Protected

 

 

 

LIST OF APPENDICES

 

Appendix 1-1       EIA Study Brief

 

Appendix 4-1       Worksheet showing Calculation of Dust Emission Rates, Construction Dust Impact Assessment

 

Appendix 4-2       A typical FDM result file, Construction Dust Impact Assessment

 

Appendix 4-3       Locations of the Existing and Committed Road Carriageways near to the Proposed Bus Depot

 

Appendix 4-4       Typical CALINE4 result files, Vehicular Emission Impact Assessment

 

Appendix 4-5       Spreadsheet showing the Calculation of Depot Pollutant Emission Rates

 

Appendix 4-6       Typical ISCST3 Result Files, Depot Pollutant Emission (NO2, CO, RSP)

 

Appendix 5-1       Typical Calculation Worksheet – Unmitigated Scenario, Construction Noise Impact Assessment (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)

 

Appendix 5-2       Typical Calculation Worksheet – Mitigated Scenario 1, Construction Noise Impact Assessment (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)

 

Appendix 5-3       Typical Calculation Worksheet – Mitigated Scenario 2, Construction Noise Impact Assessment (1, 2, 3, 4, 5, 6, 7, 8)

 

Appendix 5-4       Typical Calculation Worksheet – Mitigated Scenario 3, Construction Noise Impact Assessment (1, 2, 3, 4, 5, 6)

 

Appendix 5-5       Typical Calculation Worksheet, Depot Noise Impact Assessment (1, 2, 3, 4, 5, 6, 7)

 

Appendix 5-6       Traffic Forecast Endorsement (1, 2, 3)

 

Appendix 5-7       Detailed Traffic Noise Modelling Results (1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16)

 

Appendix 8-1       Fault Tree Analysis

 

Appendix 8-2       Event Tree Analysis

 

Appendix 9-2       Drawings showing the landscape proposal and design concept to avoid potential visual impact (1, 2, 3, 4, 5, 6, 7)

 

 

 

 

 

1.               Introduction

1.1           Project Need

1.1.1       Citybus Limited (Citybus) is one of the major bus services operators in Hong Kong.  To date, it still does not have its own permanent bus depot. The reliance of the company’s engineering and maintenance services on temporary depots build on short term tenancy sites that need to be demolished after temporary use has proven over the past years not to be a preferable practice.  The need to decommission the temporary depot at Aldrich Bay in near future will create an immediate problem for the company.  It would be difficult for Citybus to maintain its quality bus services to the Hong Kong public in the lack of stable engineering and maintenance facilities.

1.1.2       Citybus currently operates about 90 routes with a fleet of about 790 buses on the Hong Kong Island.  While over 400 buses are serving routes in Southern District, some 300 buses are for routes running in the Eastern and Central Districts.  Besides, around 50 buses are running on cross-harbour routes.  The daily servicing of these buses requires depot facilities for refueling, maintenance, repairing, washing, coin collection and transfer of octopus databank data, etc.

1.1.3       Buses running in the Southern District are currently served by the bus depot at Ap Lei Chau.  A permanent depot facility is needed in the Eastern District to serve the other bus routes running on the Hong Kong Island.  With consideration of alternative sites as described in details in Section 2, a suitable development site of sufficient size was selected with the relevant Government departments for construction of the proposed bus depot. 

1.1.4       A Traffic Impact Assessment (TIA) was conducted for the proposed bus depot and approved by the Authority.   The TIA study assessed the potential traffic impact of the proposed bus depot on the adjacent road networks in terms of junction capacity and bus queue length.  Traffic generation from other future developments, including the New World First Bus (NWFB) Permanent Depot, was taken into account in the TIA study.  The Final TIA Report was accepted by Transport Department in May 2001. 

 

1.2           Project Design & Technical Assessments

1.2.1       A consultancy team led by Ling Chan + Partners Limited (LCP) was commissioned by Citybus in December 2000 to study the architectural design and engineering requirements of the proposed development. CH2M HILL (China) Limited (formerly known as EHS Consultants Limited) has been commissioned by Citybus as a sub-consultant of LCP to carry out an EIA Study for the proposed bus depot development.  Issues on Landscape and Visual Impacts were addressed by EDAW Earthasia Ltd. (EDAW) and LCP. 

1.2.2       Architectural, engineering and traffic design of the development were developed by LCP, Wong Pak Lam & Associates Ltd. (WPL), Thomas Anderson & Partners Ltd. (TAP), LLA Consultancy Ltd. (LLA), EDAW and MDA Hong Kong Ltd. through a series of design co-ordination meetings with Citybus.  The team also provided input to the EIA study in the relevant areas of their expertise.  Inputs on the traffic forecast aspect and engineering in the EIA study were provide by LLA, WPL and TAP.

 

1.2.3       According to Part 1 Schedule 2 Section A.6(Roads, railways and depot) of the EIA Ordinance (EIAO), a transport depot located in less than 200m from the nearest boundary of an existing or planned residential area and educational institution is classified as a Designated Project.  As the closest distance between the proposed bus depot and the Hong Kong Institute of Vocational Education (Chai Wan) and Tsui Wan Estate is about 80m and 165m respectively, the project is classified as a Designated Project.  An Environmental Permit issued by the Director of Environmental Protection (DEP) is required prior to the construction and operation of the proposed bus depot.

1.2.4       An application (No: ESB-065/2001) for an Environmental Impact Assessment (EIA) Study Brief under Section 5(1) of the EIAO was submitted to DEP on 19th January 2001 with a Project Profile. A Study Brief {No. ESB-065/2001} was issued by the Authority to the applicant (Citybus) under Section 5(7)(a) of the EIAO on 5th March 2001 for the preparation of the EIA report.  Appendix 1-1 presents the EIA Study Brief.

1.2.5       This EIA report is prepared in accordance with the requirements stated in the Study Brief. An Environmental Permit will only be issued by DEP for the construction and operational of the project after the approval of the EIA Report.

 

1.3           Objectives of the Assessment

1.3.1       The main objective of this EIA study is to provide information on the nature and extent of the potential environmental impacts arising from the construction and operation of the proposed bus depot and related activities taking place concurrently. The study will provide information for DEP’s decisions on:

(i)              the overall acceptability of any adverse environmental consequences that are likely to arise as a result of the proposed project;

(ii)            the conditions and requirements for the detailed design, construction and operation of the proposed project to mitigate adverse environmental consequences wherever practicable; and

(iii)          the acceptability of residual impacts after the proposed mitigation measures are implemented.

1.3.2       The objectives of this EIA study, as stated in Section 2.1 of the Study Brief, are as follows:

(i)              to describe the proposed project and associated works together with the requirements for carrying out the proposed project;

(ii)            to consider alternative site(s) and to compare the environmental benefits and dis-benefits of each of the site in selecting a preferred site;

(iii)          to identify and describe the elements of the community and environment likely to be affected by the proposed project, including both the natural and man-made environment;

(iv)          to identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;

(v)            to propose the provision of mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the project;

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

(vii)        to 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 environmental impacts and to reduce them to acceptable levels;

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

(ix)           to design and specify the environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted.

 

1.4           Public Inputs

1.4.1       During the public inspection period of the Project Profile, public inputs and comments were received on the project under the EIA Process.  The key concerns of some members of the Eastern District Board received were discussed during the Board meeting on 12 February 2001.  The key environmental issues of interest in relation to the EIA study are summarized below:

·       Potential air quality impact on nearby sensitive receivers, including Tsui Wan Estate during the operational phase;

·       Potential traffic noise impact on Heng Fa Chuen, Tsui Wan Estate and Yue Wan Estate from bus movement on the road carriageways in the vicinity of the bus depot, especially traffic noise from Wing Tai Road;

·       Potential water quality impact on the cargo handling basin;

·       Wastewater and waste management (including chemical waste) during the operational phase;

·       Potential cumulative environmental impact from the operation of two bus depots and other future developments in the area; and

·       Members agree with the project proponent that a permanent bus depot is needed but consider that the possibility to locate the bus depot at other district should be considered.

1.4.2       Potential concern on these environmental factors has been taken into account in the study.

 

1.5           Structures of the EIA Report

1.5.1       This section describes the background, project needs, and objectives of the EIA study.  The site selection history is described in Section 2.  Design of the proposed development and the identified key environmental issues are described in Section 3.  Sections 4 to 10 focus on each of the key environmental aspects, and present the assessment criteria, approach/ methodologies, findings, and recommended mitigation measures, if necessary. Section 11 presents a summary of environmental outcomes and the overall conclusion of the EIA study.

1.5.2       The content in Sections 2 through 11 are listed below:

·       Section 2 Site Selection History – describes the site selection process that has gone through with the relevant Government departments in identifying the subject site for the bus depot development;

·       Section 3 Project Description and Key Environmental Issues Identification – the subject site and its environs, preliminary design of the bus depot, the planned implementation programme, and the key environmental issues identified are described under this section;

·       Section 4 Air Quality Impact Assessment – presents the construction phase air quality impact assessment, and operational phase vehicular emission impact assessment;

·       Section 5 Noise Impact Assessment – presents the construction noise impact assessment, traffic noise impact assessment and industrial noise impact assessment for the operational phase;

·       Section 6 Waste Management Implications – presents an analysis of waste generation and proposes management measures for the key waste types during the construction and operational phases of the project;

·       Section 7 Land Contamination Prevention – describes possible sources of contamination arising from the future operation of the bus depot, appropriate operational practices, waste management strategies and precautionary measures;

·       Section 8 LPG/ Petrol Filling Station Hazard Impact – assesses the potential hazard from the operation of the future LPG/ petrol filling station located to the north of the site on the proposed bus depot;

·       Section 9 Landscape and Visual Impacts – describes the landscape mitigation proposal and present the preliminary design of the bus depot building to achieve visual compatibility with its environmental context and avoid visual impact;

·       Section 10 Sewage Treatment and Disposal Facilities – describes the design measures to ensure proper sewage treatment and disposal;

·       Section 11 Summary of Environmental Outcomes;

·       Section 12 Overall Conclusion

 

2.               Site selection HistoRy

2.1           Identification of Alternative Development Sites

2.1.1       For maintaining of a quality service on the Hong Kong Island, provision of a permanent bus depot in the Eastern District for the refueling, maintenance and washing of Citybus’ buses running in the Eastern and Central Districts is needed.  The need to decommission the temporary depot at Aldrich Bay, which is not zoned for industrial use, aggregated the problem.  Citybus started the dialogue with the relevant Government departments in early 2000 to express the urgent need for a permanent depot.

2.1.2       Citybus currently operates about 90 routes with a fleet of about 790 buses on Hong Kong Island.  While over 400 buses are serving routes in Southern District, some 300 buses are for routes running in the Eastern and Central Districts.  Besides, around 50 buses are running on cross-harbour routes.  The daily servicing of these buses requires depot facilities for refueling, maintenance, repairing, washing, coin collection and transfer of octopus databank data, etc.

2.1.3       Operationally, Citybus needs two permanent bus depots.  Location-wise, it would be more efficient and environmental friendly to have one depot in the Eastern District and another in the Southern District.  As a significant portion of buses are heading towards the Central District from Eastern District when the bus service commences early in the morning, and returning from Central District to Eastern District for parking, establishment of a bus depot in the Eastern District will minimize the travelled routes, distance and time between the bus depot and the various bus terminuses.  The establishment of a new bus depot in other districts may affect Citybus’ existing operation in serving the public.  The operational needs of the buses running in the Southern District are currently met by the depot facility at Ap Lei Chau.  A permanent depot facility in the Eastern District is in demand after the decommissioning of the temporary bus depot in Aldrich Bay.

2.1.4       Taking into consideration the operational requirements of the multi-storey bus depot in terms of the driveway and ramp system with 15-m turning radius, and areas required for bus parking, maintenance bays, sunken pits, workshops, storage areas, staff changing rooms, etc., the minimum size of the site needed for the construction of a multi-storey bus depot was identified to be about 1ha.

2.1.5       Bus depots are preferably to be located within industrial areas to ensure that the landuses in its proximity are compatible.  Industrial area in the Eastern District is, however, extremely rare.  During the site selection process, Planning Department (PlanD) advised that in the Eastern District, undeveloped industrial areas were only available in Chai Wan East Industrial Area and A Kung Ngam Industrial Area in Shau Kei Wan. 

2.1.6       Most industrial sites in A Kung Ngam have already been developed, leaving only three small separate and unformed sites with a site area of about 920m2, 1800m2 and 1900m2.  Figure 2-1 presents the locations of these separate and undeveloped industrial sites (I, II and III) as shown in the Draft Shau Kei Wan Outline Zoning Plan (No. S/H9/10).

2.1.7       These unformed industrial sites in A Kung Ngam are too small for the construction of the proposed multi-storey bus depot. Even the total area of these undeveloped sites is only about 4,600m2 which cannot meet the minimum site area required for the design and construction of the bus depot.  Besides, development of the bus depot on these sites will require resumption of private properties which may not be feasible. 

2.1.8       The existing China Motor Bus (CMB) depot located at Chai Wan Road will be rented by Citybus for temporary use after decommissioning of its existing temporary bus depot at Aldrich Bay until the planned completion of the new depot in mid 2003.  The CMB depot site has been rezoned as a Comprehensive Development Area (CDA) for redevelopment.  Further use of the site as a bus depot is therefore not preferable.  Besides, there are numerous existing residential buildings located in close proximity to the existing bus depot at Chai Wan Road.  Longer-term use of the site as a permanent bus depot is not a preferred option from an environmental viewpoint given the close proximity of the existing bus depot to the nearby sensitive receivers.

2.1.9       The site selection process confirmed that there are no available industrial sites in the Eastern District other than the industrial sites in Chai Wan East Industrial Area.

2.1.10    A 0.78 hectare site located to the immediate south of New World First Bus Depot was initially identified for consideration. The site was rejected as the site area involved cannot satisfy the minimum site area requirement for a multi-storey bus depot.  Figure 2-2 shows the location of the site (Site A).

 

2.2           Selection of Preferred Site

2.2.1       Two candidate sites, Site B and Site C, located within the Chai Wan East Industrial Area were identified and considered with the Government departments during the site selection process.  Both sites have a similar site area of approximately 1 ha.  It was identified that these were the only available sites within the industrial area that could meet the site area requirement of the bus depot.  Figure 2-2 shows the locations of these alternative sites – B and C in the Draft Chai Wan Outline Zoning Plan (OZP) No. S/H20/11 (Extract).  The environmental benefits and dis-benefits of these alternative sites have been considered and compared in the selection of the preferred site in order to avoid potential environmental impact.

2.2.2       The key environmental factors that would have bearing on the location of the bus depot include air quality and noise associated with the operation of the bus depot.  Site C, the selected site, is preferred from an environmental viewpoint as it is located further away from the nearby sensitive receivers of interest.  Table 2‑1 presents a comparison of the nearest distance from the nearby sensitive receivers for the two alternative sites.

Table 2‑1         Nearest Distance of Site B and C from the nearby Sensitive Receivers

Location

Approximate Nearest Separation (m)

 

Site B

Site C

Heng Fa Chuen

115

390

Staff Quarters of Hong Kong Institute of Vocational Education (IVE) (Chai Wan)

110

135

IVE (Chai Wan)

130

80

Tsui Wan Estate

490

165

 

2.2.3       It can be noted that the distance separation between the nearest residential blocks from the bus depot is greater for Site C than for Site B.  Comparing the relative distance of Site B and Site C from the residential blocks, Site C was identified to be the preferred site in terms of avoiding potential environmental effects on air quality and noise associated with the operation of the bus depot. 

2.2.4       Although the Hong Kong Institute of Vocational Education (IVE) (Chai Wan) is located closer to Site C, it is not expected to be in operation during the hours in the early morning and near mid-night when the bus depot would be most active.

2.2.5       In addition, it can be noted that Site C is more directly linked to Island Eastern Corridor, Shun Tai Road, Sheung On Street when compared with Site B. Traveling distance on Shing Tai Road and the new roads within the Industrial Area and the associated vehicular emission can be reduced for buses heading towards Shau Kei Wan or Siu Sai Wan directions for site C than for Site B.

 

2.3           Required Technical Assessments of Selected Site

2.3.1       The selection of Site C was a Government departmental agreement taking into account, as illustrated above, the requirements on site area of the bus depot, availability of industrial sites in the Eastern District, the urgent programme of the project, and landuse compatibility including the environmental factors.

2.3.2       At the Hong Kong District Planning Conference in mid-June 2000, the site C, bounded by the future local road 20/4 to the East and Shing Tai Road to the West, was selected and agreed in-principle by the Government departments to be a suitable site for Citybus to further study the design of its permanent bus depot proposal.  Citybus was required to conduct a Traffic Impact Assessment (TIA) and an Environmental Impact Assessment (EIA) to assess and confirm the technical feasibility of the project at the subject site.

2.3.3       The Final TIA conducted by Citybus’ Traffic Consultant approved by TD in May 2001 confirms the acceptability of the site for the development of the bus depot from a traffic point-of-view.  Traffic generation from other future developments in the area, including the New World First Bus (NWFB) bus depot has been taken into account in the TIA study. The findings of this EIA Study will confirm the environmental acceptability of the project.  Potential cumulative environmental impact has been assessed as appropriate in accordance with the requirements and methodologies presented in the Technical Memorandum on EIA Process (EIAO-TM). Mitigation and/or control measures have been identified and recommended where necessary.

 

 

3.               Project Description and key environmental issues identification

3.1           The Subject Site and its Environs

3.1.1       The proposed bus depot is planned to be constructed on an approximately 1 hectare site located in the Chai Wan East Industrial Area.  The site selection process is described in Section 2.  Figure 1-1 shows the location of the site.

3.1.2       A major portion of the site is currently unoccupied.  Highways Department (HyD) is temporarily occupying a southern portion of the site for a work area until June 2001.  A small area at the northern part of the site falls within the boundary of the NWFB temporary bus depot.  Located at a minimum distance of about 80m to the North-west of the future bus depot is Hong Kong Institute of Vocational Education (IVE) (Chai Wan).  Lying between the college and the bus depot site are the MTR railway tracks leading to the Chai Wan Station to the south and Shing Tai Road. To the immediate North of IVE is its associated Staff Quarters.  Tsui Wan Estate is situated at more than 165m to the South-west of the site.  The nearest residential blocks at Heng Fa Chuen is located at approximately 390m to the north of the site.

3.1.3       The site was reclaimed and is zoned for industrial use (“I”) similar to some other landuses in its vicinity as shown in the latest Draft Outline Zoning Plan (OZP) No. S/H20/11 gazetted on 20 April 2001.  According to the Notes of the OZP, “Bus Depot” is a column 1 use that no planning permission from the Town Planning Board is required.  Figure 3-1 presents an Extract of the OZP.  Planning Department (PlanD) has advised that in addition to the proposed bus depot, the Chai Wan East Industrial Area is also planned to accommodate an Open Space, a Joint Government Departmental Depot, Lorry Park & Motor Vehicle Repair Workshop, New World First Bus Depot, LPG/ Petrol Filling Station and Hong Kong Post Super Centre.

3.1.4       The northern side of the site is planned by the Government for the provision of a LPG/ petrol filling station, while the Southern side of the site would be the HK Post Supercentre.  At this stage, only the NWFB depot situated near Chong Fu Road and located at about 135m from the proposed bus depot is under active construction.  The NWFB depot is expected to be completed by year 2002.  All other proposed developments in the area are still at a planning stage without a concrete development programme.

3.1.5       The proposed Citybus depot will be bound by a future local road – Road 20/4 to the East and Shing Tai Road to the west.  Other future new roads in the Chai Wan East Industrial Area include Road 20/6 and Road 20/10 as shown in Figure 1-1.  Highways Department (HyD) has advised that the three new roads – 20/4, 20/6 and 20/10 would be completed in December 2002.

3.1.6       The planned bus routing plan agreed with TD is illustrated in Figure 3-2.The ingress point of the bus depot is planned at Road 20/4, which is a local road lying away from nearby sensitive receivers. Buses approaching the depot from Island Eastern Corridor (IEC) will travel via Shing Tai Road northbound, Road 20/6 and Road 20/4.  There will only be one egress point each located at Shing Tai Road and Road 20/4 respectively.  The egress point on Shing Tai Road will serve IEC bound buses which will go via Shing Tai Road southbound and Shun Tai Road. Buses leaving or returning to the depot will not pass through the section of Shing Tai Road further north of the site leading to Heng Fa Chuen. 

3.1.7       The 20/4 Road egress point is planned for Siu Sai Wan bound buses.  It is understood that Wing Tai Road currently carries high traffic flows during the peak hours.  To avoid potential traffic noise impact attributed to the operation of the proposed bus depot, as agreed with the Authority, buses commuting between the bus depot and Siu Sai Wan area will be required to take the route through the future Sheung On Street Extension (connecting the existing Sheung On Street with the future Road 20/4) under normal operating conditions (i.e. except for emergency conditions), instead of allowed to use Wing Tai Road and Shing Tai Road at all time periods.  Citybus will require its employees to strictly follow this requirement when entering/ leaving the bus depot.

 

3.2           Bus Depot Design

3.2.1       The proposed bus depot will be constructed in form of a low-rise building occupying a site area of approximately 1 hectare.  The development will provide spaces for bus parking, maintenance and office areas.  Architectural design of the development has been developed by the Project Architect – LCP, with input on the engineering, traffic and environmental aspects provided by the sub-consultants. 

3.2.2       Figures 3-3 to 3-7 present the preliminary ground to fifth floor layout plans of the bus depot.  A cross section of the building is shown in Figure 3-8.  The bus depot will consist of three stories located at ground floor (G/F), first floor (1/F) and roof floor (3/F).  As shown on the preliminary plans, the G/F will house approximately 2 refuelling bays, 2 washing bays, 29 sunken pits, 4 brake testers and 5 maintenance bays. The 1/F will provide some 46 maintenance bays for annual maintenance works. The 3/F (roof) floor will provide about 100 bus parking areas.  The fourth floor (4/F) and fifth floor (5/F) that will be built at the southern portion of the site only will be used for office areas.  The upper ground floor (U/G) and second floor (2/F) is a mezzanine floor provided at the southern part of the site near Road 20/4.  Spare parts storage areas, chemical storage areas and scrap yards/ waste material stores will be provided on the G/F and 1/F.  Taking into account the interface with the future developments located in its immediate proximity, including the LPG/ Petrol Filling Station and the Hong Kong Post Super Centre, the northern and southern sides of the bus depot building are planned to be constructed with a solid concrete facade.

3.2.3       At the ingress point at Road 20/4, the incoming buses will enter bays 1 and 2 for refuelling, coin collection, transfer of octopus data to databank, and vehicle washing. The whole process of the refuelling/ servicing and washing would normally take about 3 to 5 minutes.  If maintenance is required, the buses will drive into one of the maintenance bays or sunken pits. 

3.2.4       To facilitate the buses entering directly to the maintenance area, a passing lane will be provided in parallel to the refuelling/ washing bay lanes.  The provision of a passing lane will also help to avoid the generation of a long queue length of buses waiting to be serviced and the associated potential traffic impact.  The holding area within the bus depot was assessed to be sufficient to accommodate the bus queue, as confirmed in the approved TIA. 

3.2.5       After the completion of washing procedure, buses will leave the depot for further servicing, or returning to parking areas located on 3/F of the bus depot or off-site. On the 1/F, normally a bus under annual maintenance check will have to station in a maintenance bay for about 5 to 7 days.  Bus movements on the 1/F will therefore be very limited.

3.2.6       The number of staff working in the bus depot/ maintenance area and offices is estimated to be about 319 and 201 respectively during daytime (approx. 08:00 to 18:00).  In the evening and night-time (approx. 18:00 to 08:00), some 50 workers are expected to be working at the bus depot.

 

3.3           Implementation Programme

3.3.1       Construction works are planned to start near end of 2001 to meet the urgent demand to have the depot ready for operation in mid-2003.  Figure 3-9 shows a preliminary construction programme.  The development is expected to be completed in mid-2003.

 

3.4           Identification of Key Environmental Issues

3.4.1       The key environmental issues during the construction and operational phases of the proposed development are identified to include the following:

During the Construction Phase

·       Potential construction dust impact on the nearby air sensitive receivers;

·       Potential construction noise impact from construction activities;

·       Construction waste management and implications

 

During the Operational Phase

·       Potential vehicular emission impact from buses moving within the depot and running at the adjacent roads;

·       Potential traffic noise impact from buses running on the road carriageways in the vicinity of the depot;

·       Potential fixed noise impact generated from activities at the bus depot;

·       Undertaking of land contamination preventive measures;

·       Proper chemical waste management;

·       Provision of sewage treatment and disposal 

 

3.4.2       The EIA Study Brief requires in general a study area of 300m and 500m from the boundary of the project site with respect to air quality impact assessment and noise impact assessment, respectively.  Figure 2-10 shows the study area boundary for air quality and noise impact assessments.

3.4.3       In addition to the above key environmental issues, the EIA Study Brief requires an evaluation on the potential hazard impact arising from the operation of the future LPG/ Petrol Filling Station located on the northern side of the site (Section 8), Landscape and Visual Impacts associated with the implementation of the project (Section 9), and an illustration on the Sewage Treatment and Disposal Facilities (Section 10).

 

 

4.               Air Quality Impact Assessment

4.1           Introduction

4.1.1       This section assesses the potential air quality impact associated with the construction and operational phase of the proposed bus depot. Air sensitive receivers (ASRs) have been identified and worst case impact on these receivers have been assessed quantitatively.

4.1.2       Dust generation from construction activities is identified to be of key interest during construction phase of the project.  During the operational phase, vehicular emission from buses running within the bus depot and on the adjacent roads is the key focus of the study.

4.1.3       The assessment covers a study area of 500m from the development site boundary in accordance with the requirements of the EIA Study Brief.  

 

4.2           Assessment Criteria

4.2.1       The principal legislation regulating air quality in Hong Kong is the Air Pollution Control Ordinance (APCO) (Cap. 311).  Air Quality Objectives (AQOs) are set for the whole territory which specify statutory concentration limits for various criteria pollutants and the maximum numbers of times allowed to exceed over a specified period of time.  The AQOs for Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Total Suspended Particulates (TSP) and Respirable Suspended Particulates (RSP), which are relevant to the assessments, are summarised in Table 4‑1.

Table 4‑1         Hong Kong Air Quality Objectives

Pollutant

Pollutants Concentration (mg/m3)

 

Averaging Time

 

1 hour (i)

8 hours (ii)

24 hours (ii)

1 year (iii)

CO

30,000

10,000

N.A.

N.A.

NO2

300

N.A.

150

80

TSP

N.A.

N.A.

260

80

RSP

N.A.

N.A.

180

55

   (i)            Not to be exceeded more than 3 times per year;

   (ii)           Not to be exceeded more than once per year;

   (iii)          Arithmetic means;

   N.B.        Concentrations measured at 298 K and 101.325 kPa (one atmospheric pressure).

 

4.2.2       In addition to the AQOs, EPD requires under Annex 4 in the Technical Memorandum on EIA Process (EIAO-TM) issued under the EIA Ordinance an hourly TSP limit of 500mg/m3 for construction dust impact assessment.

4.2.3       The Air Pollution Control (Construction Dust) Regulation came into effect since 16 June 1997.  Site formation, construction of the foundation and superstructure of buildings, road construction works, etc. are classified as “notifiable work” under the Regulation.  Any work which involves stockpiling of dusty materials, loading, unloading or transfer of dusty materials, transfer of dusty materials using a belt conveyor system, use of vehicles, debris handling, excavation or earth moving, site clearance, etc. are regarded as “regulatory work”.  A Schedule specifying the dust control requirements for a variety of construction activities is included in the Regulation.  The contractor responsible for a construction site where a notifiable work and/ or regulatory work is being carried out have to ensure that the work is carried out in accordance with the Schedule with regard to dust control.

 

4.3           Air Sensitive Receivers (ASRs)

4.3.1       As stated in Annex 12 of the EIAO-TM, domestic premises and schools are defined as Air Sensitive Receivers (ASRs).  The nearest ASRs situated in the vicinity of the proposed bus depot within the study area were identified for the air quality impact assessment.  These ASRs include the IVE (Chai Wan) and its auxiliary Staff Quarters located to the north-west of the development site, Tsui Wan Estate located to the south of the development and Heng Fat Chuen situated to the north of the site.

4.3.2       Representative assessment points (A1 to A6) have been selected for the air quality impact assessment.  The ASRs represented are described in  Table 4‑2.  Locations of the representative assessment points are shown in Figure 4-1.

 Table 4‑2        Representative Assessment Points

Ref. No.

Location of ASR

Closest distance of ASR from bus depot boundary (m)

A1

Heng Fa Chuen

390

A2

Staff Quarters of Hong Kong Institute of Vocational Education (IVE) (Chai Wan)

135

A3

IVE (Chai Wan)

80

A4

IVE (Chai Wan)

85

A5

Tsui Hong House, Tsui Wan Estate

185

A6

Tsui Sau House, Tsui Wan Estate

165

 

4.4           Baseline Condition

4.4.1       The existing major air pollution sources in the study area are expected to be open road traffic emission from major road carriageways (e.g. Island East Corridor).

4.4.2       Annual average concentrations of nitrogen dioxide (NO2) and respirable suspended particulate (RSP) recorded by EPD’s monitoring station in Eastern district for the year 1999 have been used as background pollutant concentrations in the study area. Although the number of monitoring records for NO2 for Eastern monitoring station is below the minimum data required within a quarter, the concentration of 66mg/m3 was found to be comparable with the concentration at Tsuen Wan which have similar landuses.

4.4.3       For carbon monoxide (CO) and total suspended particulate  (TSP) which has no published data available in the study area, EPD’s records from the Tsuen Wan monitoring station in 1999 has been adopted.  Table 4‑3 summarises the background concentrations of CO, NO2, and RSP adopted in the assessment for the purpose of evaluating the cumulative air quality impact.

Table 4‑3         Background Air Pollutant Levels Adopted in the Assessment

Air Pollutant

Annual Average Concentration (mg/m3)

CO

1177

NO2

66

TSP

79

RSP

47

Note : Background concentrations of CO, NO2 and RSP in the study area has been assumed based on reported data given in “Air Quality in Hong Kong, 1999” published by EPD.

 

4.5           Construction Dust Emission Impact Assessment

Introduction

4.5.1       The major air quality impact of concern during the construction phase will be potential dust emission impact on nearby ASRs. Unacceptable impacts from the criteria pollutants - nitrogen oxides (NOx), sulphur dioxide (SO2), and carbon monoxide (CO) are unlikely as significant emissions are not anticipated. Emission from diesel trucks for the haulage of materials and construction plants will contain high percentage of smoke particulate and unburned hydrocarbons in comparison with petrol driven vehicles. However, as the anticipated number of construction plants associated with the construction works will be limited, significant impact on the existing air quality is not envisaged.

 

Dust Emission Sources

4.5.2       Based on the nature of the construction, major dust emission sources associated with the construction activities are expected to arise from excavation, material handling and vehicle movement on unpaved haul roads during the foundation construction stage.  The corresponding dust emission rates associated with these activities have been worked out by making reference to the typical emission factors reported in the Compilation of Air Pollutant Emission Factors (AP-42) 5th Edition published by U.S. Environmental Protection Agency (USEPA).

à             Excavation activities - dust emission from excavation has been estimated by making reference to the emission factor given in Section 13.2.4 of USEPA AP-42.  Dust emissions have been estimated on a per excavator basis with consideration of typical excavation rate, number of excavator involved, etc. to simulate a representative scenario;

à             Material handling - potential dust emission from loading/ unloading activities of excavated material have also been predicted by making reference to Section 13.2.4 of USEPA AP-42.  Dust emissions from loading/ unloading have been estimated on a per truck basis with consideration of the capacity of each truck, and the estimated number of trucks to simulate a representative scenario. 


à             Vehicle movement on unpaved haul roads - dust emission from traffic movement on unpaved haul roads have been estimated by making reference to Section 13.2.2 of USEPA AP-42, with consideration of no. of trucks, typical vehicle speed, weight, number of wheels, etc.

4.5.3       A worksheet showing the calculation of dust emission rates from each activity is presented in Appendix 4-1 for reference.

4.5.4       Foundation works for the New World First Bus (NWFB) depot was completed. Concurrent superstructure construction activities at the NWFB depot is not expected to give rise to a significant cumulative dust impact.  There are no known major planned construction activities in the vicinity of the site that may pose a potential significant cumulative impact.  Besides, it is expected that even if there would be other construction activities planned in future, these works will also be required to implement sufficient dust control measures in accordance with the requirements of the Air Pollution Control (Construction Dust) Regulation.

 

Dust Emission Modelling

4.5.5       Construction dust impact arising from the key dust emission sources presented above during the foundation construction stage on the nearby existing ASRs has been predicted using the air quality model “Fugitive Dust Model” (FDM).  The model was particularly developed to model fugitive dust emissions and is well accepted by HKEPD and USEPA for this purpose.  The model was developed based on the widely used Gaussian plume formulae for estimation of pollutant concentrations but has been adapted to incorporate a gradient-transfer deposition algorithm which accounts for the settling out of dust particles, and to include the wind dependent factor on dust emission rates.  The model is designed to predict fugitive dust dispersion from point, line, area and volume sources.

4.5.6       Based on information on general size distribution as reported in Guide to Rock and Soil Descriptions issued by the Geotechnical Control Office, Civil Engineering Services Department, Hong Kong (1988), it has been assumed in the dust dispersion model that 80% of particulates have size equal to 30µm, with the remaining 20% assumed to be respirable with a size of 10µm.  An average dust density of 2,500 kg/m3 has been assumed in the study.

4.5.7       The following relevant meteorological data of the year 1998 were obtained from Hong Kong Observatory and used in the modeling study. Parameters used include:

à             Hourly wind direction and speed, air temperature together with atmospheric Pasquill stability class obtained at King’s Park;

à             Daily morning and maximum mixing heights based on the radiosonde ascent at King’s Park; and

à             Hourly total sky cover, cloud amount and cloud based height of the 1st - 4th layers observed at the Hong Kong Observatory Headquarters in Tsim Sha Tsui.

4.5.8       Given the stringent noise limits that need to be satisfied before construction activities within the restricted hours will be allowed, it is expected that there will only be construction activities during daytime from 0700 to 1900 hours.  Nevertheless, to be conservative in the study, dusty construction activities have been assumed to be in operation continuously over a 24-hour period to give a worst-case situation.

4.5.9       Maximum 1-hour and 24-hour TSP concentrations were predicted at each representative assessment points A1 through A6 identified above.  Given the limited height of the dust emission sources, TSP concentrations were predicted at 1.5m, 5m and 10m above ground at the representative assessment points to simulate the worst-case situations.  ASRs situated at higher levels are expected to be subject to lower dust impact.  With account of the background TSP levels, the maximum 1-hour and 24-hour average TSP concentrations predicted were compared with the 1-hour and 24-hour TSP limits of 500mg/m3 and 260mg/m3, respectively. A typical FDM result file for construction dust impact assessment is enclosed in Appendix 4-2 for reference.

 

Assessment Results (Unmitigated Scenario)

4.5.10    The unmitigated maximum 1-hour and 24-hour average TSP concentrations predicted at the representative assessment points, with background concentration included, are presented in Table 4‑4 and Table 4‑5 below.

Table 4‑4         Maximum 1-hour TSP Concentrations predicted at the ASRs

(without Mitigation Measures)

Ref. No.

Location

Predicted TSP concentrations

(mg/m3)

 

 

1.5m above ground

5m above ground

10m above ground

A1

Heng Fa Chuen

115

110

100

A2

Staff Quarters of the IVE (Chai Wan)

190

157

136

A3

IVE (Chai Wan)

279

216

157

A4

IVE (Chai Wan)

504

378

212

A5

Tsui Hong House, Tsui Wan Estate

180

173

151

A6

Tsui Sau House, Tsui Wan Estate

227

217

184

            Note: Background TSP concentration of 79mg/m3 has been included.

 

Table 4‑5         24-hour Average TSP Concentrations predicted at the ASRs

(without Mitigation Measures)

Ref. No.

Location

Predicted TSP concentration

(mg/m3)

 

 

1.5m above ground

5m above Ground

10m above Ground

A1

Heng Fa Chuen

89

89

88

A2

Staff Quarters of the IVE (Chai Wan)

112

108

100

A3

IVE (Chai Wan)

143

132

110

A4

IVE (Chai Wan)

352

247

147

A5

Tsui Hong House, Tsui Wan Estate

110

106

97

A6

Tsui Sau House, Tsui Wan Estate

150

144

126

            Note: Background concentration of 79mg/m3 has been included.

 

4.5.11    The modelling results for the unmitigated scenario revealed that the nearby Air Sensitive Receivers will be subject to dust level at acceptable levels, except at A4.  In accordance with the requirements set out in the Air Pollution Control (Construction Dust) Regulation, sufficient dust control/ mitigation measures shall be implemented to ensure full protection of the nearby ASRs. 

 

Control Measures for mitigating Fugitive Dust Emissions

4.5.12    The following measures are specifically recommended for implementation together with those presented in the Air Pollution Control (Construction Dust) Regulation:

 

General Site Management

4.5.13    Appropriate working methods should be devised and arranged to minimise dust emissions and to ensure any installed air pollution control system and measures are operated and/or implemented in accordance with their design merits.  In the event of malfunctioning of any control system or equipment, the relevant dusty activities shall stop until the relevant control system or equipment are restored to proper functioning.

4.5.14    Frequent mist spraying should be applied on dusty areas.  The frequency of spraying required will depend upon local meteorological conditions such as rainfall, temperature, wind speed and humidity.  The amount of mist spraying should be just enough to dampen the material without over-watering, which could result in unnecessary surface water runoff.

4.5.15    No free falling of construction debris shall be allowed at the site.

 

Vehicles and Site Haul Road

4.5.16    Dust emission from unpaved roads comes predominantly from travelling of vehicles. Areas within the site where there are regular vehicle movements should have an approved hard surface.  Speed controls at an upper limit of 10 to 15 kph should be imposed and their movements should be confined to designed roadways within the site.  All dusty vehicle loads should have side and tail boards and should be covered by tarpaulin extending at least 300 mm over the edges of the side and tail boards.  Wheel-wash troughs and hoses should be provided at exit points of the site.

 

Material Stockpiling and Handling

4.5.17    The amount of stockpiling should be minimised as far as practicable. The surface of the stockpile should be kept wet by spraying with water.  Dust emission during loading of fill material to dump trucks should be mitigated by spraying to sufficiently damp the material prior to any loading or unloading operation. Dusty construction debris should be covered or stored inside enclosed areas where practicable to avoid dust generation. 

4.5.18    Watering is an effective dust control measure commonly employed in storage piles and handling operations and should be implemented where appropriate. Other control measures such as enclosed or semi-enclosed windboard should be used, where applicable, to minimise dust emission.

4.5.19    With the implementation of the above-mentioned dust mitigation measures together with those required in the Air Pollution Control (Construction Dust) Regulation, it is expected that a minimum dust control efficiency of at least 50% is achievable.  Table 4-6 and 4-7 present the mitigated dust levels predicted at the ASRs based on 50% dust control efficiency.  Implementation of dust control measures in accordance with the requirements under the Air Pollution Control (Construction Dust) Regulation will therefore ensure that unacceptable dust impact will not be generated.

Table 4‑6         Maximum 1-hour TSP Concentrations predicted at the ASRs

(with Mitigation Measures)

Ref. No.

Location

Predicted maximum 1-hr TSP concentrations (mg/m3)

 

 

1.5m above ground

5m above ground

10m above ground

A1

Heng Fa Chuen

97

94

89

A2

Staff Quarters of the IVE (Chai Wan)

134

118

107

A3

IVE (Chai Wan)

179

147

118

A4

IVE (Chai Wan)

292

228

146

A5

Tsui Hong House, Tsui Wan Estate

130

126

115

A6

Tsui Sau House, Tsui Wan Estate

153

148

132

            Note: Background TSP concentration of 79mg/m3 has been included.

 

Table 4‑7         24-hour Average TSP Concentrations predicted at the ASRs

(with Mitigation Measures)

Ref. No.

Location

Predicted 24-hour average TSP concentration (mg/m3)

 

 

1.5m above ground

5m above Ground

10m above Ground

A1

Heng Fa Chuen

84

84

83

A2

Staff Quarters of the IVE (Chai Wan)

95

94

90

A3

IVE (Chai Wan)

111

105

95

A4

IVE (Chai Wan)

216

163

113

A5

Tsui Hong House, Tsui Wan Estate

94

93

88

A6

Tsui Sau House, Tsui Wan Estate

115

111

103

            Note: Background concentration of 79mg/m3 has been included.

 

4.5.20    Contour maps presenting the predicted mitigated maximum 1-hour and 24-hour average TSP concentrations at 1.5m above ground are given in Figure 4-2 and Figure 4-3. Background TSP level has been included in the results.  The results show that the fugitive dust impact arising from the construction works when dust mitigation measures required under the Air Pollution Control (Construction Dust) Regulation are implemented will be within the relevant dust assessment criteria.  Implementation of the recommended Environmental Monitoring and Audit Program (EM&A) will further ensure full protection of the nearby ASRs.  Details of the EM&A Programme are presented in the Environmental Management Plan (EMP).

 

 

4.6           Vehicular Emission Impact Assessment

4.6.1       During the operational phase of the bus depot, vehicular emission from buses running within the depot and commuting to and from the depot is the focus of the assessment.  Emissions of the key criteria pollutants associated with vehicular traffic, including nitrogen dioxide (NO2), carbon monoxide (CO), and respirable suspended particulate (RSP) have been studied. 

4.6.2       Potential cumulative air quality impact from the concurrent operation of the NWFB depot in the area, as well as traffic emissions from the nearby road carriageways have been taken account of quantitatively in the study.  Traffics generated from the future landuses within the Chai Wan East Industrial Area have been considered in the traffic forecast provided by the Project Traffic Consultant – LLA Consultancy Limited.

4.6.3       Air pollutants may also be generated from other depot operations including engine testing, brake testing and painting.  However, the emission quantity and associated air pollution is expected to be insignificant. 

 

Open Road Vehicular Emission

Traffic Forecast

4.6.4       Similar to other future developments, operation of the proposed bus depot will inevitably results in generation of some traffic flows on the nearby road carriageways.  This section assesses the potential air quality impact associated with traffic movement in the study area, taking into account the additional traffic flows generated from the proposed bus depot.  Effects of other possible future developments in the study area have also been taken into account through incorporation of traffic generation into the traffic forecast. 

4.6.5       Traffic forecast for the year 2018 during the early morning (0530 to 0630) and mid-night (2300 to 0000) peak hour, when the highest traffic flow contribution is expected to be generated from the proposed bus depot, has been adopted in the study.  Traffic generation from other possible future developments in the area, including the NWFB depot has been taken into consideration in the preparation of the traffic forecast.  The traffic forecast data prepared by the Project Traffic Consultant has been endorsed by Transport Department for use in the EIA study (see Appendix 5-6).  In the preparation of the traffic forecast, the Traffic Consultant has taken into account the data presented in the approved EIA reported carried out for NWFB Permanent Depot in Chai Wan to ensure that a consistent and conservative approach is being followed. Table 4-8 and Table 4‑9 present the 2018 Traffic Forecast during the early morning and nighttime peak hours when the highest bus flows will be generated from the bus depot.  Alignment of the road carriageways studied is presented in Appendix 4-3.

 

Table 4‑8         Year 2018 Traffic Forecast during the early Morning Peak Leaving

Label

Traffic Volume (veh/hr)

% of Passenger Car

% of HGV

% of Bus

A

332

21.5

56.6

22.0

B

171

47.1

50.0

2.9

C

160

25.8

74.2

0.0

D

306

39.3

38.5

22.2

E

565

54.5

45.5

0.0

F

835

57.0

43.0

0.0

G

249

14.0

58.7

27.3

H

3086

71.1

26.6

2.4

I

114

15.0

85.0

0.0

J

162

24.2

72.7

3.1

K

47

25.0

28.2

46.8

L

212

24.3

75.7

0.0

M

232

24.3

75.7

0.0

N

3086

71.1

26.6

2.4

O

284

37.7

62.3

0.0

P

2694

70.1

29.9

0.0

Q

20

90.0

10.0

0.0

R

20

90.0

10.0

0.0

Table 4‑9         Year 2018 Traffic Forecast during the Nighttime Peak Return

Label

Traffic Volume (veh/hr)

% of Passenger Car

% of HGV

% of Bus

A

734

40.9

42.7

16.3

B

346

40.7

42.0

17.3

C

50

93.8

6.2

0.0

D

368

57.8

25.9

16.3

E

889

86.3

13.7

0.0

F

1325

77.6

22.4

0.0

G

368

44.9

38.8

16.3

H

2564

58.8

36.5

4.7

I

68

18.0

82.0

0.0

J

647

25.4

65.3

9.3

K

85

38.6

14.3

47.1

L

477

44.6

55.4

0.0

M

481

44.6

55.4

0.0

N

2564

58.8

36.5

4.7

O

433

55.8

44.2

0.0

P

1654

59.8

40.2

0.0

Q

20

90.0

10.0

0.0

R

20

90.0

10.0

0.0

 

Air Quality Modelling

4.6.6       Potential vehicular emission from open road traffic has been assessed with the air quality model CALINE4.  The model is a line source model developed by the California Department of Transport.  It was developed based on the Gaussian diffusion formulae and a mixing zone concept in predicting dispersion of pollutants emitted from road carriageways.

4.6.7       As the bus depot will commence operation in 2003, to be conservative in the assessment, emission factors for vehicular pollutants recommended by DEP in air quality study have been used with 2018 traffic forecast data in the modeling study.  As pollutant emission factors are expected to be reduced as technology advance in reducing vehicular emissions, this approach to the study is considered very conservative.  Table 4-10 presents the 2003 vehicular emission factors of CO, NOx and RSP for passenger cars, buses and heavy diesel vehicles.

Table 4‑10       2003 Vehicular Emission Factors

Vehicle Type

Emission Factor (mg/km)

 

CO

NOx

RSP

Passenger Car (Petrol)

2.34

0.90

0.03

Franchised Bus Double Deck (FBDD)

9.22

10.53

1.17

Heavy Diesel Vehicle

8.53

6.21

1.05

The following assumptions were adopted throughout the study :

i.        NOx is a mixture of NO and NO2;

ii.       20% of NOx is assumed to be NO2;

iii.      NO was modelled as “Inert Gas”; with a molecular weight of 46g;

iv.      The proportion of RSP in the vehicular emission is assumed to be 100% of the particulate matter which is, in general, less than 10 mm in the aerodynamic diameter.

4.6.8       Pasquill Stability Class F with a wind speed of 1m/s has been adopted in the CALINE4 modelling to simulate the worst-case meteorological conditions.  The ambient temperature was assumed to be 25 degree Celsius.  The average mixing height was taken as 500m according to monitoring data obtained from Kai Tak Weather Station.  Wind direction standard deviation of 6 degree.  The aerodynamic roughness coefficient was set at 100cm.

4.6.9       Concentrations of maximum 1-hour CO, NO2 and RSP at the representative assessment points A1 through A6 presented in Figure 4-1 were predicted from the model.  As there is currently no hourly AQO for RSP, the modeled peak hour RSP concentrations were converted to daily average concentration for checking compliance with the daily criteria of 180mg/m3.  24-hour NO2 concentrations at the assessment points were also predicted using the same approach.  Assuming that the predicted maximum peak hour traffic flow would last for 10 hours and the wind would be blowing at the worst direction for 24 hours, a conversion factor of 0.4 has been applied to convert maximum 1-hour RSP and NO2 concentrations to maximum 24-hour average for comparison with the relevant Air Quality Objectives.

 

Assessment Results

4.6.10    Table 4-11 presents the modeled maximum 1-hour NO2, 1-hour CO and 24-hour average RSP and NO2 concentrations at the representative assessment points for open road vehicular emission.  Background pollutant concentrations have been added to the results. Typical CALINE4 result files are presented in Appendix 4-4.

4.6.11    It can be noted that all modeling results are falling well within the relevant AQOs.

Table 4‑11       Predicted Pollutant Concentrations from Open Road Vehicular Emission

Ref. No.

Location

Predicted pollutant concentrations (mg/m3) at discrete receptor

 

 Height above ground (m)

1-hr NO2

24-hr NO2

1-hr CO

24-hr RSP

 

 

1.5

5

10

15

20

1.5

5

10

15

20

1.5

5

10

15

20

1.5

5

10

15

20

A1

Heng Fa Chuen

104

104

104

104

104

81

81

81

81

81

1635

1520

1520

1406

1406

63

62

59

56

55

A2

Staff Quarters of the IVE (Chai Wan)

179

141

141

141

141

111

96

96

96

96

1864

1864

1864

1749

1749

74

73

71

69

66

A3

IVE (Chai Wan)

179

179

179

141

141

111

111

111

96

96

1978

1978

1864

1864

1749

77

76

74

71

68

A4

IVE (Chai Wan)

141

141

141

141

141

96

96

96

96

96

1864

1864

1749

1749

1635

71

70

68

66

64

A5

Tsui Hong House, Tsui Wan Estate

141

141

141

104

104

96

96

96

81

81

1749

1749

1635

1520

1520

69

67

64

62

60

A6

Tsui Sau House, Tsui Wan Estate

141

141

141

104

104

96

96

96

81

81

1864

1749

1635

1635

1520

70

68

64

62

60

 

Air Quality Objectives (AQO)

300

150

30,000

180

         Note: Background pollutant concentrations are included in the results.

 

Depot Emissions

4.6.12    In addition to the off-site bus traffic, operation of the bus depot would also result in generation of some air pollutants directly from the depot.

Pollutant Emission Rates

4.6.13    Exhaust emission from buses moving and idling inside the proposed bus depot building was studied.  As discussed before, maximum bus flows leaving or returning to the bus depot are expected to occur during early morning (0530 to 0630) and at mid-night (2300 to 0000).  Bus flow information, in terms of worst-case number of buses entering and leaving each floor of the proposed depot building during the peak hours, was estimated by the project traffic consultant and are summarised in Table 4‑12.

Table 4‑12       Worst-case Bus Flow entering/ leaving the Depot Building

 

Number of Buses/Hour1

 

During mid-night

During Early Morning

Floor Level

Entering

Leaving

Entering

Leaving

G/F

80

80

5

90

1/F2

80

80

0

85

Roof floor3

70

70

0

85

Notes:

1.             Bus flow data for each floor includes the accumulated flow passing each floor level;

2.             1/F maintenance bay is for annual maintenance activities which occur outside the above peak hours. Nevertheless, to be conservative, the maximum hourly bus flows which are expected to occur during daytime have been assumed for the mid-night scenario;

3.             Maximum numbers of buses are expected to return to the depot for parking at approximately 19:30 to 20:30.  Again, as a conservative approach, the peak hourly flows have also been assumed to occur during the mid-night scenario for the vehicular emission impact study.

4.6.14    Vehicular emission within the bus depot would be generated from bus movement within the depot, as well as from bus idling.  Emission factors for these two activities were referenced to the Fleet Average Emission Factors calculated by the “FAEF” Model, and EPD recommended idling factors.  These are summarised in Table 4‑13.

Table 4‑13       Emission Factor for Buses inside Depot

 

Emission Factors

Bus activity

NOx

CO

RSP

Traveling (g/km)

11.71

8.89

1.38

Idling (g/min/vehicle)

2.0

2.0

0.042

 

4.6.15    Worst-case average emission rates of NO2, CO and RSP from bus movement and idling within the bus depot were calculated from the estimated maximum hourly bus flows and bus traveling distance and are summarised in Table 4‑14.  A spreadsheet showing the calculation of these emission rates are set out in Appendix 4-5.  These highest pollutant emission rates will only occur during the peak hour.  Applying these emission rates in the model for testing of pollutant dispersion under different worst-case meteorological conditions at different hours of the days will therefore generate conservative results.  Taking into account the worst-case maximum number of buses, multiple point sources were assumed to be present concurrently as a conservative approach in the air quality modelling. 

 

Table 4‑14       Bus Depot Air Pollutant Emission Rates

 

 

Pollutant Emission Rate (g/s) Per Source

Floor

No. of Sources

NO2

CO

RSP

G/F

80

0.00130

0.00032

0.000164

1/F

80

0.00062

0.00015

0.000059

Roof floor

70

0.00069

0.00016

0.000069

 

4.6.16    In addition to the proposed Bus Depot, New World First Bus (NWFB) Services Limited will also operate a similar bus depot facility located at about 135m to the north of the development site.  Similar pollutant emission rates estimated from bus movement and idling within the NWFB depot were identified from the NWFB EIA report (EIAO registration no.: EIA-034/1999) and inputted to the ISCST3 for studying the potential cumulative air quality impact due to emissions from the two depots.

 

Air Quality Modelling

4.6.17    The dispersion of air pollutants released from the proposed bus depot and NWFB depot was studied quantitatively using the air quality model “Industrial Source Complex Short Term Version 3 (ISCST3)” released by Trinity Consultants Incorporated. This model was developed based on the principle of Gaussian dispersion and is widely acceptable by authorities worldwide including the United States Environmental Protection Agency (USEPA) and the Hong Kong Environmental Protection Department (EPD).  Pollutant emissions from each floor of the bus depot were modeled. The emission heights were taken at 0.5m above the floor slabs, which is the approximate height of the bus exhaust pipes.

4.6.18    The same set of meteorological data as presented in Section 4.5.7 has been adopted in the air quality modeling.  Background pollutant concentrations as presented in Table 4‑3 were adopted.

 

Modelling Results

4.6.19    Table 4-15 presents the predicted maximum 1-hour NO2, CO and 24-hour average RSP and NO2 concentrations at the representative assessment points A1 through A6 due to emission from the two depots.  Typical ISCST3 result files can be found in Appendix 4-6.  All modeling results are found to be well within the AQOs.

 

Cumulative Impact from Open Road Traffic and Depot Emissions

4.6.20    Cumulative pollutant concentrations at the representative assessment points due to operations of the two bus depots, off-site road vehicular emissions and background pollutant concentrations were conservatively estimated from summation of the ISCST3 and CALINE4 results and are presented in Table 4-16.

 

Table 4‑15        Predicted pollutant concentrations due to emissions from Citybus Depot and NWFB Depot

Ref. No.

Location

Predicted pollutant concentrations (mg/m3) at discrete receptor

 

 Height above ground (m)

1-hr NO2

24-hr NO2

1-hr CO

24-hr RSP

 

 

1.5

5

10

15

20

1.5

5

10

15

20

1.5

5

10

15

20

1.5

5

10

15

20

A1

Heng Fa Chuen

74

74

74

73

74

68

68

68

68

68

1211

1210

1209

1208

1210

48

48

48

49

48

A2

Staff Quarters of the IVE (Chai Wan)

82

82

81

80

79

70

70

70

70

70

1242

1242

1240

1236

1230

49

49

49

51

49

A3

IVE (Chai Wan)

82

82

83

82

80

71

71

71

71

71

1242

1243

1245

1243

1236

49

49

49

52

49

A4

IVE (Chai Wan)

81

81

83

83

81

75

75

75

75

75

1237

1240

1245

1245

1240

51

51

51

56

51

A5

Tsui Hong House, Tsui Wan Estate

85

85

85

84

83

72

72

72

72

72

1258

1258

1256

1252

1247

50

50

50

53

50

A6

Tsui Sau House, Tsui Wan Estate

83

83

82

82

80

71

71

71

71

71

1247

1247

1245

1242

1236

49

49

49

52

49

 

Air Quality Objectives (AQO)

300

150

30,000

180

Note: Background pollutant concentrations are included.

 

 

 

Table 4‑16       Cumulative Pollutant Concentrations from Open Road Traffic Emission & Depots Emission

Ref. No.

Location

Predicted pollutant concentrations (mg/m3) at discrete receptor

 

 Height above ground (m)

1-hr NO2

24-Hr NO2

1-hr CO

24-hr RSP

 

 

1.5

5

10

15

20

1.5

5

10

15

20

1.5

5

10

15

20

1.5

5

10

15

20

A1

Heng Fa Chuen

112

112

111

111

111

83

83

84

84

84

1668

1554

1553

1437

1439

64

63

60

59

56

A2

Staff Quarters of the IVE (Chai Wan)

195

157

157

156

154

115

100

100

100

100

1929

1929

1927

1809

1803

76

75

73

73

68

A3

IVE (Chai Wan)

195

195

195

157

156

116

116

116

101

101

2043

2044

1931

1930

1809

79

78

76

76

71

A4

IVE (Chai Wan)

156

157

158

158

157

105

105

105

105

105

1924

1927

1818

1817

1698

75

75

73

75

68

A5

Tsui Hong House, Tsui Wan Estate

161

161

160

122

120

102

102

102

87

87

1830

1830

1713

1595

1590

72

70

67

68

62

A6

Tsui Sau House, Tsui Wan Estate

158

158

158

119

118

101

101

101

86

86

1934

1819

1703

1699

1580

72

70

67

68

63

 

Air Quality Objectives (AQO)

300

150

30,000

180

Note: Background pollutant concentrations are included.

 

 

4.6.21    The maximum 1-hour NO2 concentration was predicted at A3 at 10m above ground from the modelling. In addition to the discrete representative assessment points, assessment points were selected based on a 50m x 50m grid covering the key air sensitive areas of interest, viz. Heng Fa Chuen, IVE (Chai Wan) and its associated Staff Quarters, and Tsui Wan Estate.  Pollutant isopleths of maximum 1-hour NO2, 1-hour CO and 24-hour RSP and NO2 were generated from the ISCST3 and CALINE4 modelling results obtained at the worst affected level at 10m above ground.  Background pollutant concentrations set out in Table 4‑3 were added to the modelling results for comparison with the relevant AQOs.  The contour maps are presented in Figure 4-4 to Figure 4-7.

4.6.22    All predicted air pollutant concentrations at various levels of the ASRs are well within the AQOs.  The assessment results reveal that vehicular emissions from open road traffic and emission from the two bus depots will unlikely pose an unacceptable air quality impact on the surrounding ASRs.

 

4.7           Environmental Monitoring & Audit (EM&A) Requirements

4.7.1       The quantitative construction dust impact assessment confirms that no unacceptable air quality impact affecting the nearby ASRs is anticipated when the required dust control/ mitigation measures required under the Air Pollution Control (Construction Dust) Regulation are implemented.  Nevertheless, for checking the implementation of the dust mitigation measures required under the Air Pollution Control (Construction Dust) Regulation, implementation of a dust monitoring programme is recommended as part of the environmental monitoring and audit (EM&A) programme. 

4.7.2       The detailed vehicular emission impact assessment indicates that vehicular emission from buses will not be a concern during the operational phase.  The carrying out of air quality EM&A works in relation to air quality during the operational phase is not considered necessary.

 

4.8           Assessment Conclusions

Construction Phase

4.8.1       The dust impact assessment concluded that the dust impact during the construction phase of the development will be in compliance with the air quality criteria when dust control measures required under the Air Pollution Control (Construction Dust) Regulation are in place.  Construction air quality impact should be minor and effective dust control can be achieved by implementation of the dust control measures required under the Air Pollution Control (Construction Dust) Regulation.

 

Operational Phase

4.8.2       Potential air quality impact arising from the operation of the proposed bus depot, including emission directly from the bus depot and from open road vehicular emission, has been assessed.  Direct emission from the NWFB depot, as well as vehicular emission from traffic generated by the planned landuses including the NWFB depot in the area, has been considered.  The cumulative pollutant concentrations predicted are all satisfying the relevant AQOs.  The assessment results obtained with a conservative assessment approach indicate that the operation of the bus depot will not cause any unacceptable air quality impact on the surrounding air sensitive receivers.

 

5.               Noise Impact Assessment

5.1           Introduction

5.1.1       This section presents an assessment of noise impact associated with the construction and operation of the project.  During the construction phase, potential noise impact arising from the operation of powered mechanical equipment (PME) at the work sites is the key interest.  Potential traffic noise impact from buses running on the road carriageways in the vicinity of the bus depot and that generated from fixed noise sources are the focus of the operational phase impact study.  Where necessary, mitigation measures will be recommended to reduce the noise impact down to meet acceptable levels.

 

5.2           Study Area and Noise Sensitive Receivers (NSRs)

5.2.1       A study area of 300m from the boundary of the project site has been adopted in the study in accordance with the requirement stated in the EIA Study Brief.

5.2.2       As defined in Annex 13 of the EIAO-TM, domestic premises and schools are defined as noise sensitive receivers.  In the current study, the nearest NSRs identified in the proximity of the proposed Bus depot are the residential developments to the north and south of the Bus Depot, namely Heng Fa Chuen and Tsui Wan Estate respectively, and the IVE (Chai Wan) and its associated Staff Quarters.  Representative assessment points (RAPs) have been selected for each of these NSRs and their locations are shown in Figure 4-1.  These RAPs are described in Table 5‑1.  The separation distance between the RAPs and the bus depot is also shown in Table 5-1.

Table 5‑1 Representative Assessment Points selected for Noise Impact Assessment

RAPs

Description

Floors

Separation (Approx.) (m)

HF-1

Block 50, Heng Fa Chuen

G/F to 20/F

390

HF-2

Block 16, Heng Fa Chuen

G/F to 20/F

658

SH-1

Staff Quarters of the IVE (Chai Wan)

G/F to 25/F

200

SH-2

Staff Quarters of the IVE (Chai Wan)

G/F to 25/F

160

IV-1

IVE (Chai Wan)

G/F to 5/F

175

IV-2

IVE (Chai Wan)

G/F to 5/F

85

TW-1

Tsui Sau House, Tsui Wan Estate

G/F to 30/F

165

TW-2

Tsui Fuk House, Tsui Wan Estate

G/F to 30/F

235

TW-3

Tsui Ling House, Tsui Wan Estate

G/F to 30/F

305

TW-4

Tsui Hong House, Tsui Wan Estate

G/F to 30/F

205

 

5.2.3       Eastern facade of IVE (Chai Wan) Staff Quarters (SH-3 and SH-4 in Figure 4-1) is installed with fixed windows (i.e. does not rely on opened windows for ventilation) such that the relevant noise standards are not applicable.  Therefore, RAPs were only selected on the western façade of the Staff Quarters for the assessment. Besides, it is identified that IVE (Chai Wan) is installed with air-conditioners such that the occupants in the teaching classrooms and laboratories will not rely on openable windows as the primary means for ventilation.

5.2.4       No planned NSRs are identified in the proximity of the bus depot that could be subject to a noise impact resulting from the project.

5.2.5       The existing dominant noise sources identified in the vicinity of these NSRs include traffic noise from the nearby major road carriageways (e.g. Island Eastern Corridor) and railway noise from the MTR tracks.

 

5.3           Construction Noise Impact Assessment

Legislation and Assessment Criteria

5.3.1       Construction noise is controlled under the Noise Control Ordinance (NCO) which prohibits the use of powered mechanical equipment (PME) during the restricted hours (7 p.m. to 7 a.m. on normal weekdays and any time on a public holiday, including Sunday) without a valid Construction Noise Permit (CNP) granted by the Authority.  The criteria and procedures for issuing such a permit are specified in the “Technical Memorandum on Noise From Construction Works Other than Percussive Piling” (TM1).

5.3.2       For construction works other than percussive piling, although TM1 do not provide control over daytime construction activities, noise limits are set out in Table 1B of Annex 5 of the EIAO TM which have been adopted as the assessment criteria in this study.  These noise standards are summarised in Table 5‑2 below:

Table 5‑2         Noise Limits for Daytime Construction Activities

NSR

0700 to 1900 hours on any day not being a Sunday or general holiday Leq (30min.) dB (A)

All domestic premises including temporary housing accommodation

75

Educational institutions including kindergartens, nurseries.

70

65 (during examination)

N.B.    (i) The above standards apply to uses which rely on opened windows for ventilation;

(ii) The above standards shall be viewed as the maximum permissible noise levels assessed at 1m from the external facade.

 

5.3.3       Construction works during the restricted hours are not required.  However, if the Contractor finds that works during restricted hours are required, then, he should apply for a Construction Noise Permit (CNP).  Despite any description or assessment made in this EIA Report on construction noise aspects, there is no guarantee that a CNP will be issued for the project construction.  The Noise Control Authority will consider a well-justified CNP application, once filed, for construction works within restricted hours as guided by the relevant Technical Memoranda issued under the Noise Control Ordinance.  The Noise Control Authority will take into account of contemporary conditions/ situations of adjoining land uses and ay previous complaints against construction activities at the site before making his decision in granting a CNP.  Nothing in this EIA Report shall bind the Noise Control Authority in making his decision.  If a CNP is to be issued, the Noise Control Authority shall include in it any condition he thinks fit.  Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution action under the NCO.

5.3.4       With effect from 1 November 96, the use of specified powered mechanical equipment (SPME) for carrying out construction work other than percussive piling and/ or the carrying out of prescribed construction work (PCW) within a designated area are also brought under control. The relevant technical details are provided in the “Technical Memorandum on Noise from Construction Work in Designated Areas” (TM2).

5.3.5       Percussive piling is controlled similarly by a noise permit system and described in the NCO and the “Technical Memorandum On Noise From Percussive Piling” (TM3) which restrict the number of hours during which piling can be conducted.  No percussive piling may be carried out in the territory without a valid CNP issued by the Authority.  Besides, a CNP will only be granted for percussive piling which is scheduled during normal working hours between 7 a.m. to 7 p.m. from Monday to Saturday.  The carrying out percussive piling is prohibited at any time on Sundays and public holidays as well as during the weekday from 7 p.m. to 7 a.m. the next day.

 

Assessment Methodology

5.3.6       The approach used in the assessment of noise from construction works other than percussive piling is based on standard acoustic principles, and the guidelines given Para. 5.3 and 5.4 of Annex 13 of the EIAO TM.  The methodology adopted is the same as that presented in TM1.

5.3.7       The methodology for assessing construction noise impact arising from the project has been developed based on the standard acoustic principles in TM1. In brief, this includes the following steps:

(i)          based on the preliminary construction programme given in Figure 3-9, identify the most likely powered mechanical equipment (PME) to be used during foundation construction and superstructure construction;

(ii)        identify the nearest representative assessment points of the NSRs to the work sites;

(iii)      calculate the total Sound Power Level (SWL) of the equipment that would likely be used simultaneously at the notional source location of the site;

(iv)       calculate the Predicted Noise Level (PNL) based on distance attenuation from the notional source positions to the NSRs;

(v)         with consideration of the effect of façade reflection at the NSRs, calculate the Corrected Noise Level (CNL) at the NSRs; and

(vi)       compare the CNL with the relevant daytime noise limits and identify situations and locations where the implementation of construction noise mitigation measures would be necessary.

 

Noise Sources

5.3.8       Exact details on the PME to be used during the construction phase would not be available before the appointment of the Contractor in future.  Nevertheless, based on previous experience in similar construction projects, the Project Engineer, Wong Pak Lam & Associates Limited, has developed a preliminary PME inventory for the purpose of quantitative assessments in the study.  Table 5-3 through Table 5-5 present the PME inventories for the foundation construction works; sheet piling and pile cap construction, and superstructure construction, respectively.  The plant inventories listed in these tables have been confirmed by the Project Architect based on his experience in similar projects to be practical and practicable for completing the works within the planed construction programme, and demonstrated in practices through similar projects undertaken by contractors.  Potential cumulative noise impact from concurrent use of different groups of PMEs has been assessed in the study for identification of the mitigation measures required under these situations.   

5.3.9       The carrying out of a quantitative construction noise assessment based on the preliminary PME inventories established at this planning stage will allow the identification of potential construction noise problem and location of the potentially affected NSRs such that practicable and sufficient noise mitigation measures can be derived accordingly at this early stage and incorporated as contract requirements for the future Contractor to follow.  Implementation of sufficient noise mitigation can be checked through Environmental Monitoring and Audit requirements.

Table 5‑3         PME Inventory for Foundation Construction Works

PME

No. of Equipment

SWL, dB(A)

Piling, large diameter bored, oscillator

10

115

Piling, large diameter bored, reverse circulation drill

7

100

Generator

4

108

Excavator

4

112

Lorry

2

112

Crawler crane

13

112

Concrete lorry mixer

4

109

Dump Truck

3

117

 

Table 5‑4         Inventory of PMEs during Sheet Piling and Pile Cap Construction

Equipment Group

PME

No. of Equipment

SWL, dB(A)

1

Compressor <10m3 /min

2

100

 

Concrete pump

1

109

 

Gen