Consultancy Agreement No.

 

EN002(C)-01

 

Modifications to MTRC TST Station

 

Environmental Impact Assessment

 

 
 

Reference      :
 

R0305-3.01
 

Client             :
 

Mass Transit Railway Corporation Limited

 
 

Date               :
 

May 2001

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


TABLE OF CONTENTS

1.        Introduction

1.1      Background

1.2      EIA Requirement

1.3      Objectives of the EIA Study

1.4      Use of Relevant Studies

1.5      Structure of the EIA Report

2.        Project Description

2.1      Identification of Project Need

2.2      Alternative Design Options Consideration

2.3      Evaluation on Alternative Construction Methods

2.4      Proposed Construction Programme and Sequence

2.5      Major Elements of the Surrounding Environment

3.        Construction Noise Impact Assessment

3.1      Introduction

3.2      Assessment Methodology

3.3      Legislation and Assessment Criteria

3.4      Proposed Construction Sequence

3.5      Noise Sources

3.6      Representative Assessment Points

3.7      Assessment Results

3.8      Recommended Construction Noise Mitigation Measures

3.9      Potential Cumulative Noise Impact

3.10     Operational Phase Impact

3.11     Conclusion

4.        Construction Dust Impact Assessment

4.1      Introduction

4.2      Legislation and Guidelines

4.3      Ambient Air Quality

4.4      Assessment Approach

4.5      Air Sensitive Receivers

4.6      Modelling Methodology

4.7      Modelling Results

4.8      Required Dust Control/ Mitigation Measures

4.9      Potential Cumulative Dust Impact

4.10     Operational Phase Impact

4.11     Environmental Monitoring and Audit Requirements

4.12     Conclusion

5.        wASTE mANAGEMENT

5.1      Introduction

5.2      Legislation and Guidelines

5.3      Construction Waste Management

5.4      Construction Waste EM&A Requirements

5.5      Conclusion

6.        Other Environmental Factors

6.1      Introduction

6.2      Water Quality Impact

6.3      Ecological and Archaeological/Cultural Heritage Impact

6.4      Landscape and Visual Impact

7.        Summary of Environmental Outcomes

7.1      Introduction

7.2      Environmental Benefits

8.        Overall Conclusion

 

LIST OF TABLES

Table 3‑1     Preliminary List on Construction Activities and Equipment Inventory

Table 3‑2     RAPs selected for the Construction Noise Impact Assessment

Table 3‑3     Unmitigated Construction Noise Levels predicted at the RAPs

Table 3‑4     Construction Noise Levels Predicted at the RAP N1 (with silenced PME & silencers)

Table 3‑5     Noise Levels predicted at the RAP N1 (with Silenced PME + Temporary Noise Barriers + Machinery Enclosure)

Table 3‑6     Noise Levels predicted at the RAP N1 (with Silenced PME + Temporary Noise Barriers + Machinery Enclosure + Noise Enclosure at Traffic Deck Opening)

Table 3‑7     Evaluation of Potential Cumulative Noise Impact

Table 4‑1     Hong Kong Air Quality Objectives

Table 4‑2     Air Quality Criteria Adopted in this Assessment

Table 4‑3     Annual Average Concentrations of TSP measured at EPD’s Air Quality Monitoring Station in Central/Western from 1997 to 1999

Table 4‑4     Unmitigated TSP Emission Factors for Site Activities

Table 4‑5     Dust Particulate Size Distribution

Table 4‑6     Representative ASRs for the Dust Emission Impact Assessment

Table 4‑7     TSP Levels predicted at the representative ASRs

Table 4‑8     Predicted Maximum Ground Level 1-Hour & 24-Hour TSP Concentration (Cumulative)

Table 7‑1     Environmentally Sensitive Receivers and Population Protected from Noise Impact

 

LIST OF FIGURES

Figure 1‑1       Location of the Project and Boundary of the Study Area

Figure 2‑1       Subway Arrangement of KCRC Mody Road Link, Middle Road Link and the Relationship with the Proposed Southern Extension and Pedestrian Subway

Figure 2‑2       Possible Extent of Affected Facilities at the MTR TST Station

Figure 2‑3       Preliminary Design of the MTRC TST Southern Extension and Pedestrian Subway

Figure 2‑4       Typical Cross Section of the Proposed Southern Concourse Extension

Figure 2‑5       Typical Cross Section of the Proposed Nathan Road Link

Figure 2‑6       Preliminary Construction Programme

Figure 2‑7       Tsim Sha Tsui – Outline Zoning Plan No. S/K1/12 (Extract)

Figure 3‑1       Selected Representative NSRs for Construction Noise Impact Assessment

Figure 3‑2       Schematic Diagram of the Proposed Cantilever Noise Barrier

Figure 3‑3       Typical Noise Enclosure Proposed at the Road Deck Opening

Figure 4‑1       Selected Representative ASRs for Dust Emission Impact Assessment

Figure 4‑2       Contour of Predicted 1-Hour Average TSP Concentration (mg/m3) at 5.6mPD (1.5m above ground level)

 

LIST OF APPENDICES

Appendix I                 Project Profile and Study Brief

Appendix II               Alternative Design Option of Subway – Peking Road Link

Appendix III              Typical Calculation Worksheet, Construction Noise Impact Assessment (Unmitigated & Mitigated Scenario: Table 1, 2, 3, 4, 5, 6, 7)

Appendix IV              Typical FDM Result File, Construction Dust Impact Assessment (Figure showing locations of individual workareas, Source Parameters, FDM for ASRs, FDM for Contour)

Appendix V               Waste Management Plan

 

1.                  Introduction

1.1              Background

1.1.1            MTR Corporation Limited (MTRCL) proposes to modify the existing MTRC Tsim Sha Tsui (TST) Station in the form of a southward extension, and provision of an associated pedestrian subway along Nathan Road.

1.1.2            The need to modify the existing MTRC TST Station was identified as a result of the planned construction of the new KCRC East Tsim Sha Tsui (ETS) Station and associated pedestrian subways.  The subway system is intended to facilitate interchange between the MTRC TST Station and KCRC ETS Station.  A pedestrian subway will be constructed under Mody Road to connect ETS Station to TST Station.  The implementation of this “Mody Road Link” will displace a significant area of the existing TST station currently occupied by plant rooms and Back of House accommodation. The extra passenger flows in TST resulting from the interchange will also result in increased demand on public area and space for larger plant rooms and station accommodation.

1.1.3            The southern extension was identified to be the best solution for accommodating the displaced plant rooms and Back of House accommodation.  It was identified through a passenger forecast study and station planning study that the provision of a direct pedestrian link from the TST southern extension to the planned KCRC pedestrian subway at Middle Road would give improved passenger flows between the two stations.  

1.1.4            CH2M HILL (China) Limited has been commissioned by MTRCL to carry out an Environmental Impact Assessment (EIA) for the proposed modifications to MTR TST Station.  The EIA Team is independent from MTRCL’s Engineering Design Consultants, with MTRCL’s Environmental Manager providing the necessary interface between them to ensure that appropriate designs and construction method taking into full account the potential environmental impact and sufficient mitigation measures are properly identified for inclusion into the construction documentation.

 

1.2              EIA Requirement

1.2.1            In accordance with A.2 under Part I, Schedule 2 of the EIA Ordinance, the construction of a railway and its associated stations is classified as a designated project.  However, the proposed project is regarded as modification works and does not fall within such category (i.e. exempted project). Instead, the proposed modification works at TST Station was identified as “material change” to the exempted project under Section 9(4) of the EIA Ordinance (EIAO).

1.2.2            “Material Change” is defined as a physical addition or alteration to a designated project, which results in an adverse environmental impact as defined in the technical memorandum (EIAO-TM) under the EIAO.  As a general rule, changes under the following circumstances are regarded as material changes to a designated project as stated in the EIAO-TM:

i)         a change to physical alignment, layout or design of the project causing an environmental impact likely to affect existing or planned community, ecologically important areas or sites of cultural heritage;

ii)        a physical change resulting in an increase in the extent of reclamation or dredging affecting water flow or quality likely to affect ecologically important areas, or disrupting sites of cultural heritage;

iii)       an increase in pollution emissions or discharges or waste generation likely to violate guidelines or criteria in the technical memorandum without mitigation measures in place;

iv)      an increase in throughput or scale of the project leading to physical additions or alterations that are likely to violate the guidelines or criteria in this technical memorandum without mitigation measures in place; or

v)        a change resulting in physical works that are likely to affect a rare, endangered or protected species, or an important ecological habitat, or a site of cultural heritage.

 

1.2.3            MTRCL submitted a Project Profile to Director of Environmental Protection (DEP) on 13 November 2000 to apply for an EIA Study Brief for the carrying of an EIA study for the proposed modification.  DEP issued a Study Brief (No. ESB-063/2000) after public inspection of the Project Profile.  This EIA Report was prepared in accordance with detailed requirements as stated in the EIA Study Brief. An Environmental Permit for the construction and operation of the project will only be issued after the approval of the EIA report by DEP.  The EIA Study Brief is presented in Appendix I. 

1.2.4            Potential construction phase impact arising from dust and noise emission and construction waste management was identified to be key environmental issues under the EIA Study Brief.  The extent of the impact, though transient, has been identified through the EIA study and sufficient environmental mitigation measures identified to alleviate the impact to acceptable levels.

1.2.5            Figure 1-1 shows the location of the project and the boundary of the study area for construction dust and noise impact assessment. 

 

1.3              Objectives of the EIA Study

1.3.1            As stated in Clause 1.4 of the EIA Study Brief, this EIA aims to provide information on the nature and extent of environmental impacts arising from the construction of the MTRC TST Station Southern Extension and related activities that take place concurrently. This EIA report will exemplify such information and will contribute to decision by the Director of Environmental Protection on:

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

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

iii)         the acceptability of residual impacts after the implementation of the proposed mitigation measures.

1.3.2            Clause 2.1 of the EIA Study Brief sets out the specific objectives of the EIA Study.  These include:

i)            to describe the Project and associated works together with the requirements for carrying out the Project;

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

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

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

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

vi)         to identify, assess and specify methods, measures and standards, to be included in the Project which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;

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

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

 

1.4              Use of Relevant Studies

1.4.1            The following previously approved EIA studies have been reviewed and made reference to in the EIA study:

i)            Environmental Impact Assessment, East Rail Extension – Hung Hom to Tsim Sha Tsui, Kowloon-Canton Railway Corporation (Feb., 2000) (EIAO Register No. AEIAR-033/2000) (referred to as ETS-EIA Report in later sections of this report); and

ii)           Environmental Impact Assessment for Salisbury Road Underpass and Associated Road Improvement Works including Middle Road Circulation System (Apr., 1999) (EIAO Register No.: AEIAR-013/1999) (referred to as Salisbury Underpass EIA in later sections of this report)

 

1.5              Structure of the EIA Report

1.5.1            The structure of this EIA Report is as follows:

Section 1 :                   Introduction;

Section 2 :                   Project Description;

Section 3 :                   Construction Noise Impact Assessment;

Section 4 :                   Construction Dust Impact Assessment;

Section 5 :                   Waste Management;

Section 6 :                   Other Environmental Factors;

Section 7 :                   Summary of Environmental Outcomes;

Section 8 :                   Overall Conclusion.

 

1.5.2            Figures are presented at the end of each section.

 

 

2.                  Project Description

2.1              Identification of Project Need

2.1.1            KCRC has planned to build an extension of East Rail from the existing Hung Hom Station to a new terminal at East Tsim Sha Tsui.  The new East Tsim Sha Tsui (ETS) Station is located below the Middle Road Children’s Playground.  Associated with the station construction works is the plan to build a pedestrian subway from ETS via Blenheim Avenue and Mody Road to MTRC TST Station (refer hereafter as the “Mody Road Link”).  Figure 2-1 shows the subway arrangement plan of KCRC “Mody Road Link” as presented in the ETS-EIA Report.

2.1.2            Implementation of the Mody Road Link will require the relocation of the existing plant rooms and station accommodation located underneath the Nathan Road – Mody Road junction.  Figure 2-2 highlights the possible extent of the affected existing facilities at MTRC TST Station.

2.1.3            Increased pedestrian flows as a result of the proposed interchange will also result in increased demand on public area within the station for passenger circulation, and additional space for station accommodation and larger plant rooms to cater for increased demand for electricity and other utilities. 

2.1.4            The effect on passenger flows associated with the implementation of the KCRC ETS Station including the Mody Road Link was studied in details by MTRCL’s Traffic Consultant in a pedestrian forecast study.  It was identified that due to the physical constraints associated with Mody Road subway width which is limited to 4.5m only, even if the Mody Road subway is controlled for one-way flows from ETS to TST only in the A.M. peak, under the worst-case situation, in the order of 10,000 persons per hour passengers who want to interchange between the two stations in the A.M. peak will be forced to find a route at street level.  The most likely route is predicted to be along Nathan Road between the existing MTR Entrance E and the future KCRC Middle Road Entrance.  The need and long-term benefits of providing a subway under Nathan Road (hereafter referred to as the “Nathan Road Link”) to link the existing MTRC TST Station concourse with the KCR Middle Road Link was identified.

2.1.5            In the absence of the project (i.e. the do-nothing scenario), there will be no room to cater for the relocated plant rooms and station accommodation.  Moreover, interchange between the KCRC ETS Station and MTRC TST Station will rely on Mody Road Link only, which is predicted to be insufficient to cater for peak passenger flows.  As a result, passengers would be forced to find a route at street level, which is environmentally unfavourable. Furthermore, it is not certain that the KCRC ETS Station could be operated safely without the completion of this interchange.

2.2              Alternative Design Options Consideration

Key Objectives

2.2.1            As described above, the two prime objectives to be achieved in the planning of the TST Station Modifications include:

i)            To provide a direct pedestrian subway link between the TST station and ETS Station;

ii)           To accommodate the plant rooms and back-of-house accommodation displaced by the Mody Road Link.

2.2.2            While there may be different alternative options for accommodating the displaced plant rooms and back-of-house accommodation, the selection on the preferred alignment of the concourse extension shall take into account the resultant effect on the length and alignment of the associated pedestrian subway for linking the TST Station and ETS Station.  The key objective is to minimise the walking distance as far as practicable. Obviously, if the alignment of the pedestrian subway is not attractive to the passengers, the purpose of building it will be defeated. 

2.2.3            The consideration of alternative alignment design options and selection of the preferred design – an approximately 80m southern concourse extension and an associated 30m long Nathan Road subway link have been arrived at taking into full account the above two objectives.

 

Pedestrian Subway Link Design

2.2.4            In identifying the preferred alignment of the pedestrian subway, the design objective is to provide the most convenient routing for the predicted passenger movements. 

2.2.5            From the passenger forecast study, the proposed “Nathan Road Link” was also identified to be the most direct and convenient alignment of the subway to serve the public especially during the A.M. peak as an alternative route to the Mody Road Link. It was predicted to be especially attractive to the passengers using the front half of KCR trains.

2.2.6            By referring to Figure 2-1, the proposed Nathan Road Link can be viewed as one that would complete a critical “missing” length of the subway network between the TST station and ETS station in future, which will function to:

§        Enhance and enlarge the walking catchment areas of both stations and provide more flexible route choice between the stations and the surrounding areas;

§        Provide direct and convenient interchange routes between the various parts of the two stations; and

§        Improve accessibility generally, by enhancing the convenience, capacity and environment of pedestrian facilities in the Tsim Sha Tsui area;

§        Minimise the time and opportunities of passengers being in direct exposure to vehicular emissions when walking along Nathan Road at street level

2.2.7            The proposed underground pedestrian subway along Nathan Road extending to Middle Road is identified to be the most direct connection to the Middle Road Link, especially when its design is considered in association with the proposed southern concourse extension.  Provision of an approximately 80m long TST Station southward extension as currently planned will reduce the length of the pedestrian subway along Nathan Road to about 30m only.  

2.2.8            No other routing has been identified that could provide a similar direct connection as the proposed Nathan Road Link to facilitate passenger interchange between the TST station and new ETS Station. The Nathan Road Link is identified to be the preferred alignment from the pedestrian forecast study.  A sketch showing a subway link from TST Station to KCR Middle Road Link via Peking Road, Hankow Road (Peking Road Link) is presented in Appendix II to illustrate the not preferred indirect link.  The total length of the subway is about 165m.  Provision of such subway would result in a long walking distance.  The result is that this may not be the mostly used route by the passengers as a more direct route is present above ground.

 

Concourse Extension Design

2.2.9            Consideration on possible options on the design of the concourse extension shall take into account its relationship with the design of the pedestrian subway planned between MTR and KCR.  The key would be to provide an integrated design that can achieve the two main objectives. The possible options are also constrained by the existing location of the station and the nearby buildings. 

2.2.10         In associated with the consideration of providing the Peking Road Link discussed above, the option of re-providing the station accommodation and plant rooms under Peking Road was reviewed and confirmed not be a preferred option after taking into consideration various factors.  The key is that this option will not have the benefits provided by the southern extension of significantly reducing the length of the planned pedestrian subway:

·               The long narrow strip area allowed for the construction of the station extensions will result in an inefficient design, where additional area of substantial extent will be displaced as corridor beside the areas used to accommodate the required plant rooms and station accommodation

·               The underground subway structure will need to be extended to the west of nearly 150m from the existing station box assuming that one level of the concourse extension is to be built.  It is considered that the long narrow layout is far from a satisfactory design from a station functioning and a safety point of view. 

·               This option is also not preferred from an environmental viewpoint due to the need to build an additional vent shaft at Peking Road, the long length of the construction work areas on a narrow road with residential developments located on both sides and extra amount of construction and demolition material generated. 

·               There will also be technical difficulties associated with severe headroom restrictions at the interface with the existing TST station (at Entrance E) and the relative inefficiency of running long lengths of cable and duct.

2.2.11         Similarly, reprovisioning of the plant rooms and station facilities under Haiphong Road, Humphrey Avenue or Carnavon Road, etc. or developing a northern extension cannot produce an integrated design to facilitate the development of a short, direct and effective subway link to facilitate passenger interchanges between the TST Station and ETS Station.  Besides, a number of capacity enhancement measures have already been proposed for the TST station which concentrate on the northern end of the station.  These capacity enhancement works and station improvement works, which have already been planned under the title of TST Essential Works, are anticipated to include the provision of a new escalator and lift from platform to concourse, new escalators between concourse and street level, a new Station Control Room and related back of house facilities, new kiosks and new ceilings at concourse and platform levels.

2.2.12         The alternative options for the concourse extension are therefore not preferred when compared with the integrated Southern Extension and Nathan Road subway link option in terms of achieving the two prime objectives stated above.

 

Development of the selected Integrated Design Option –Southern Concourse Extension and associated Nathan Road Link

2.2.13         Provision of a single floor southern concourse extension and an associated Nathan Road Link directly connected with the KCRC Middle Road Link was identified to be the preferred design/ alignment option. 

2.2.14         The basis for selecting the Southern Extension and the environmental factors considered are summarised below:

§        the extension of the station to the south will shorten the length of the direct Nathan Road Link identified to be required in connection with the KCRC Middle Road Link i.e. minimise walking distance between the two stations, minimize extent of construction work area and limit the work area to the section of Nathan Road that are mostly surrounded by hotels provided with central air conditioning systems and do not rely on openable windows for ventilation;

§        the option does not require construction of any additional vent shaft i.e. avoiding the generation of additional noise impact on the nearby noise sensitive receivers;

§        the new plant rooms can be located conveniently relative to the existing plant rooms i.e. minimize the impact on the passengers using the TST station during the construction phase

2.2.15         Preliminary options on the design of the Southern Extension and associated Nathan Road Link were developed by the Engineering Design Consultants and discussed with the Government since August 2000.  The preliminary design was further developed into the “Preferred Option” following the basis design to take into account the various site constraints.  Detailed design of the Southern Concourse Extension and Nathan Road Link is currently being considered by the Engineering Design Team in parallel with the EIA study.  Figure 2-3 presents the preferred option.  Figure 2-4 and 2-5 illustrate the relationship of the Southern Concourse Extension and Subway to the existing bored Tsuen Wan Line tunnels, respectively.   Sufficient clearance has been incorporated into the engineering design. 

 

2.3              Evaluation on Alternative Construction Methods

2.3.1            Construction of this extension is expected to be difficult, given the obvious need to minimise any effects on the traffic, existing bored Tsuen Wan Line tunnels and the nearby building structures.  Bored tunnelling and cut-and-cover method are the available techniques to select from.

2.3.2            Use of bored tunnelling, if practicable, has the environmental benefit of avoiding the associated airborne noise and dust impact on the nearby sensitive receivers when compared with the cut-and-cover option.  However, this construction technique is not identified to be a technically feasible option when a number of key site-specific engineering factors are taken into account.  The key engineering constraints which led to the conclusion that application of bored tunnelling in this project is not technically feasible are as follows:

§        The use of bored tunnelling techniques normally requires a two-diameter cover to achieve arching effect for safe bored tunnelling operations.  The vertical limits on the alignment of the extension is predetermined by the level of the existing TST station and limited by the presence of the existing tunnels below as illustrated in Figure 2-4 and Figure 2-5.  The width of the extension dose not suit bored tunnelling as there is insufficient cover to generate an arching effect;

§        The existing Tsuen Wan Line tunnel was constructed back in 1976 to 1980.  The tunnel lining was formed partly of bolted SGI segments and partly of precast concrete segment excavated in CDG and back grouted.  The tunnel linings are able to accommodate only limited movements and distortions.  It would be difficult to control and ensure that the ground and tunnel movements can be kept within acceptable limits if bored tunnelling technique is used;

§        Site investigation data from previous studies revealed the general ground conditions at the concourse extension.  The general stratigraphy involves fill, marine sand, alluvium, CDG down to some 12m below ground as expected for areas near the seawall.  Bored tunnelling technique normally requires a continuous ground condition for an infinite distance.  The vary stratigraphy would create difficulty in bored tunnelling design

2.3.3            The use of cut-and-cover method, however, is not constrained by the above key engineering factors and other site factors, given its simplistic nature which can accommodate the geotechnical requirements and clearance requirements (from the existing tunnels and nearby building foundation). 

2.3.4            Besides, the potential dis-benefits associated with the use of cut-and-cover technique in terms of dust and airborne noise emission can be mitigated through undertaking the bulk excavation activities under a road deck, phasing and sequence of construction activities associated with the site clearance and temporary deck construction, as well as implementation of sufficient dust and noise mitigation measures during the execution of the construction activities.      

 

2.4              Proposed Construction Programme and Sequence

2.4.1            The preliminary construction programme and sequence has been considered with target to minimise the impact from the construction works on the environment and traffic as a high project objective.

2.4.2            A preliminary construction programme is presented in Figure 2-6.  Site clearance is assumed to commence in early 2002 for completion in 2004.  This programme anticipated that the temporary decking would be constructed in 15 stages for the completion of the full road deck in early 2003.  Nathan Road will be reinstated to its original condition near mid 2004 after excavation works and the construction of the extended station box.

2.4.3            It is expected that the construction works will commence with removal of the existing median strip.  The existing concrete road pavement will be demolished in stages on a lane-by-lane basis such that impact on the traffic movement can be minimised.  Locations of the existing utilities lying under Nathan Road have been taken account of as far as practicable in the design of the preferred layout plan.  The objectives are to maximise the opportunities for the existing utilities to be hung above the underground excavation area, if possible, instead of having to be diverted such that the construction period and the associated environmental impact on the nearby sensitive receivers can be minimised.  It is expected that the area requiring significant utility diversion will be the footpath on the east side of Nathan Road.

2.4.4            Temporary piles will be installed at required locations in stages across the full width and length of Nathan Road within the project site area to support the temporary road deck and for control of settlements during excavation.  Sufficient dust and noise mitigation measures will be implemented through the construction period to control the potential environmental impact to acceptable levels, including the provision of noise barriers and machinery enclosures as detailed in Section 3.  The completed road deck will be flush with the existing road surface to carry Nathan Road traffic while underground excavation works are carried out. 

2.4.5            Excavation will be carried out beneath the deck proceeding layer by layer with regular monitoring of tunnel integrity.  Excavated materials will be removed by gantry and hoist to trucks parked within the proposed noise enclosure at the opening near the middle strip of Nathan Road (please refer to Section 3 and Error! Reference source not found.).  It is envisaged that the roof and base slabs of the concourse extension would be constructed using a Bottom-up construction method, involving the installation of pipe piles for supporting the road deck.

2.4.6            The bottom-up construction method is evaluated at this planning stage to be more preferable than the top-up approach.  Pipe pile wall method adopted in bottom-up construction can be installed with relatively compact machinery which is more suitable for the project, given the narrow works area involved and the headroom restrictions.  The use of smaller diameter, cased, and pre-drilled temporary works in pipe pile wall method also help to avoid potential impact on the existing rail tunnel.  Use of top-down construction could be difficult given the extensive corestones and buried structure in the area.  The working area for excavation would also be confined one the roof slab is cast in top-down construction approach, resulting in much longer period of confined working environment which is not preferable from a safety point-of-view.  Adopting the top-down construction method, nevertheless, will involve similar construction sequence with respect the site clearance and installation of the temporary road deck with the potential dust and noise impact mitigated by similar control techniques.  

2.4.7            The temporary road deck will be removed after the completion of the underground works and the road and utilities reinstated using, again, a lane-by-lane approach in order again to keep traffic movement on Nathan Road.  Sufficient noise mitigation measures will also be provided including use of noise barriers and machinery enclosures.

2.4.8            Construction of the TST Station southern extension is desired to commence in late 2001 – early 2002. 

 

2.5              Major Elements of the Surrounding Environment

2.5.1            Situated in the vicinity of the work area are mostly hotels that are provided with central air conditioning and do not rely on openable windows for ventilation.  These include, on the western side, Peninsula Hotel, Kowloon Hotel and Hyatt Regency Hong Kong Hotel and, on the eastern side, Sheraton Hotel, Imperial Hotel, and Holiday Inn Hotel.  Commercial buildings situated in the vicinity of the work area include Prestige Tower, Alpha House and Oterprise Square.  Chung King Mansions situated to the east of the work area is mostly occupied by commercial uses and hostels equipped with window-type air conditioners.  At ground level, there are shops along both sides of Nathan Road. In the following assessments, sensitive uses among these major elements have been taken account of in the study.

2.5.2            Figure 2-7 presents an extract of the Tsim Sha Tsui Outline Zoning Plan (No. S/K1/12) near the work area.  All landuses in the vicinity of the work area are zoned as “Commercial”.

 

 

 

3.                  Construction Noise Impact Assessment

3.1               Introduction

3.1.1            In this chapter, noise impact as generated during construction phase was evaluated. Relevant criteria for construction noise impact assessment were made referenced to. Details of construction activities and the possible noise impact arising from the use of Powered Mechanical Equipment (PME) were evaluated. Representative noise sensitive receivers (NSRs) were identified in the vicinity of the construction site. The degree of noise impact was predicted based on consideration of basic acoustic principles. Effective mitigation measures were recommended if necessary in order to attenuate noise impact to acceptable levels.  The study area covers an area within 300m from the construction worksite.

 

3.2               Assessment Methodology

3.2.1            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 in Para. 5.3 and 5.4 of Annex 13 of the “Technical Memorandum on Environmental Impact Assessment Process” (TM).

3.2.2            Noise impact derived from the construction activities has been predicted based on the following procedures:

(a)          Identify from the preliminary construction programme presented in Figure 2-5 the key construction phases involved that may generate a construction noise problem;

(b)          Identify an inventory on type and quantity of Powered Mechanical Equipment (PME) that would be required to achieve the works based on the time allowed under the programme;

(c)          Identify from “Technical Memorandum on Noise From Construction Works other than Percussive Piling” (TM1) the Sound Power Level (SWL) of each PME used in the construction works;

(d)          Refer to BS5228, “Noise and vibration control on construction and open sites – Part 1. Code of practice for basic information and procedures for noise and vibration control” if the SWL of individual equipment cannot be found in TM1;

(e)          Select representative NSRs in the vicinity of for the construction noise impact assessment as Representative Assessment Point (RAP);

(f)           Identify the notional source position for each RAP in accordance with the procedures as described in TM1;

(g)          Calculate the Predicted Noise Level (PNL) based on distance attenuation from notional source positions to the representative RAPs;

(h)          With consideration of the effect of facade reflection at the RAPs, predict the Corrected Noise Level (CNL);

(i)           Based on a comparison of the CNL with the noise assessment criteria, identify the required noise mitigation measures and predict the mitigated noise levels.

 

3.3               Legislation and Assessment Criteria

3.3.1            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 TM1.

3.3.2            For construction works other than percussive piling, although TM1 do not provide control over daytime construction activities, noise assessment criteria are set out in Table 1B of Annex 5 of the EIAO-TM.  For hotels and hostels which are the key NSRs in this study, the applicable noise assessment criteria is Leq(30min.) 75dB(A) for construction works during the non-restricted hours (i.e. 0700 to 1900 hours on any day not being a Sunday or general holiday). 

3.3.3            In the assessment, practicable direct noise mitigation measures have been identified and recommended to achieve the noise criteria as far as practicable.  Provision of indirect technical remedies in the form of noise insulation and air conditioning was regarded as last resort solution only upon exhaust of all practicable mitigation measures in the assessment.

 

3.4               Proposed Construction Sequence

3.4.1            The key construction activities are expected to include the following and in the sequence as described.  It can be noted that in order to minimise the potential environmental (noise) and traffic impact, the construction work area will be limited and with significant phasing and sequencing of construction activities build into the programme.

Site Preparation:

·        Demolish existing median strip;

·        Divert and narrow existing footpath and one traffic lane on east side of Nathan Road;

·        Divert utilities to create sufficient space for temporary wall installation;

 

Demolition of Road Pavement and Temporary Road Decking

·        Demolish existing concrete road pavement;

·        Install temporary works (cofferdam, piling and road decking) for carrying out of underground excavation activities subsequently;

·        Extend traffic deck for a second lane;

·        Proceed lane-by-lane across Nathan Road to divert utilities and construct concourse extension walls and traffic deck;

·        Reinstate Nathan Road traffic by the road deck and reserve sufficient area as construction site and for the opening leading to the underground work area;

 

Underground Works

·        Construct a noise enclosure to cover the opening planned near the middle strip of Nathan Road;

·        Excavate beneath the road deck and proceed layer by layer with regular monitoring of tunnel integrity and potential deformations. Ground treatment and controlled dewatering will proceed in parallel with excavation in order to balance loads on existing MTR running tunnels.  Excavated material to be removed by gantry and hoist to trucks parked within the noise enclosure;

·        Grouting below excavation level to stabilize existing running tunnels if required;

·        Construct roof and base slab of the concourse extension. Bottom up construction is currently planned to be used;

 

Backfilling and Reinstatement

·        Remove deck, backfill and reinstate utilities and road pavement using again a lane-by-lane progressive approach.

 

Works within the Completed Structure

·        Breakthrough existing station end wall;

·        E&M fitout and relocation of plant;

·        Demolish and make good existing areas in existing station;

·        Architectural fitout to new station accommodation and existing areas of plantrooms.

 

3.5               Noise Sources

3.5.1            Based on the sequence on construction activities involved as described above, the key construction activities and PME anticipated to be involved were identified through liaison with the MTRCL’s Engineering Design Consultant and are presented in Table 3‑1.  The plant inventory and utilisation rate adopted in the assessment are considered practicable in achieving the preliminary construction programme taking into account the phased lane-by-lane construction programme.

3.5.2            While it is expected that the future appointed Contractor may propose a different PME inventory, the carrying out a representative quantitative assessment at this planning stage will allow the potential noise problem be realised and that practicable and sufficient noise mitigation measures are derived and planned at an early stage.  The Contractor will be required by MTRCL through specific contract specification to provide and implement sufficient direct noise mitigation measures based on the recommendation in this EIA to achieve acceptable noise levels on the nearby NSRs.

Table 3‑1     Preliminary List on Construction Activities and Equipment Inventory

Phase  ID

Construction Activities

No. of Equipment

Percentage of Utilisation

Equipment

1

Site establishment phase

4

80%

Concrete breakers (20kg hammer)

 

 

2

100%

Compressors

 

 

1

10%

Lorry

 

 

1

50%

Mini excavator

 

 

 

 

 

2

Traffic deck piling

1

60%

500mm dia. piling auger

 

 

1

100%

Compressors

 

 

2

100%

Water pumps

 

 

1

20%

Concrete lorry

 

 

 

 

 

3

Road demolition

2

80%

Concrete breakers (20kg hammer)

 

 

1

50%

Mini excavator

 

 

1

20%

Lorry

 

 

1

100%

Compressor

 

 

 

 

 

4

Underground excavation works

2

100%

Vent fans

 

 

1

100%

Compressors (1200 cfm)

 

 

1

100%

Water pump with hydrocyclone

 

 

2

80%

Mini excavators

 

 

2

80%

Concrete breakers

 

 

1

50%

Gantry crane

 

 

 

 

 

5

Underground concrete works

1

100%

Concrete pump

 

 

2

100%

Vent fans

 

 

2

100%

Vibrating pokers

 

3.5.3            It is noted that the implementation of KCRC Hung Hom to Tsim Sha Tsui East Rail Extension will involve construction works at Mody Road and Middle Road, including a section on Nathan Road, in the pedestrian interchange subway construction.  KCRC has advised that there is currently no firm detailed programme with the respect to the timing for construction works at different work segment.  In order to assess the potential cumulative noise impact associated with the possible event (though unlikely or of limited duration), relevant findings contained in the ETS-EIA Report have been considered in parallel with findings from the assessment to ascertain if there would be any potential cumulative noise impact so that appropriate control measures can be implemented if necessary.

 

3.6               Representative Assessment Points

3.6.1            Existing noise sensitive receivers situated within the study area, which are noise sensitive uses that rely on opened windows for ventilation, have been identified.  Representative Assessment Points (RAPs) were selected and presented in Table 3‑2 and Figure 3-1.  Noise levels were predicted at the lowest, worst affected noise sensitive floors at the selected RAPs for the unmitigated and mitigated scenarios.

Table 3‑2     RAPs selected for the Construction Noise Impact Assessment

RAP

Name of Building

Noise Sensitive Use

N1

Chungking Mansions

Hostels

N2

Mirador Mansion

Residential

N3

Harilela Mansion

Residential

N4

Wing Lok House

Residential

N5

Mohan’s Building

Residential

3.7               Assessment Results

3.7.1            Table 3‑3 presents the unmitigated noise levels predicted at the RAPs for each of the 5 construction phases.  Those predicted noise levels exceeding the noise criteria are shown in bold. Worksheets showing the calculation are provided in Appendix II for reference.  The worksheets also cover an assessment of potential noise impact from the road reinstatement at the conclusion of the civil works. 

3.7.2            Noise shielding effect due to the road decking structure in construction group 4 – underground excavation works has been accounted for.  It was assumed that once the traffic deck is built, noise associated with construction activities carried out beneath the deck will be greatly attenuated.  The road decking shall have a sufficient thickness (at least 25mm) to be noise insulating and shall not be allowed to have noise leaks such as any sizeable openings.  The deck shall be able to achieve a transmission noise of at least 15dB(A) for underground construction activities carried out under the deck. 

3.7.3            Results of the calculation revealed that in the absence of additional mitigation, N1 and N2 situated in the vicinity of the site would be affected by the construction noise impact under the worst-case scenarios.  Cumulative noise impact as high as 85dB(A) could occur at the worst affected NSR N1. 

3.7.4            It must be pointed out that the assessment results only represent the worst-case scenarios when all equipment involved in each construction phase are assumed to be in concurrent operation within a 30 minute period.  In reality, this worst-case scenario is expected to be rare.  Yet, results obtained have shown exceedance in the daytime noise criteria under the worst-case scenario mainly at N1.  Implementation of sufficient noise mitigation measures especially when construction works are carried out near N1 is necessary to alleviate the noise impact to acceptable levels.

Table 3‑3     Unmitigated Construction Noise Levels predicted at the RAPs

 

Predicted Noise Levels in Different Phases, Leq(30min.) dB(A)

NSR

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

N1

85

83

84

84

83

N2

74

73

73

73

72

N3

70

68

68

69

68

N4

73

71

71

72

71

N5

71

69

69

70

69

*Bold and shaded cell denotes exceedance

 

3.8               Recommended Construction Noise Mitigation Measures

3.8.1            In addition to phasing and sequencing of construction activities for the site clearance and temporary road deck construction, as well as keeping the PME to be used concurrently in each phase to a minimum which have been seriously considered and built into the construction programme, noise generation from the construction activities can be further minimised, where necessary, by adopting a number of noise mitigation measures as far as practicable, including:

à       Use of quiet PME with lower Sound Power Level;

à       Erect temporary noise barriers and machinery enclosure;

à       Provide Noise Enclosure at the Traffic Deck Opening retained as entrance to the underground work area and for exporting of excavated material;

à       Implement good site practice and noise management;

3.8.2            A mitigation package has been developed progressively from consideration of the noise reduction effect of each of these mitigation measures.

 

Use of Silenced PME

3.8.3            Silenced types of equipment for use in construction activities are available in Hong Kong.  For each item of PME proposed for the construction works, the corresponding SWL of quieter plant were identified from TM1 or BS5228 Part I:1984 and are presented in Appendix II. Silencers are also recommended to be used in fan ventilation system to attenuate noise generated during fan operation to achieve a noise reduction of 15dB(A).

3.8.4            Table 3‑4 shows the mitigated noise levels when silenced PME are in use at N1 where there is predicted noise exceedance under the unmitigated scenario.  The predicted noise levels that still exceed the noise criteria are shown in bold for ease of reference. Predicted noise levels at other NSRs (N2 to N5) are not shown as the relevant assessment criteria are already met under the unmitigated scenario.

3.8.5            By adopting silenced type of PME, it is identified that due to its close proximity to the worksite, N1 would inevitably still be affected with the maximum noise level of 84dB(A) at the worst affected floor, reaching a maximum noise level of 84dB(A) in Phase 1.

 

Table 3‑4     Construction Noise Levels Predicted at the RAP N1 (with silenced PME & silencers)

 

Predicted Noise Levels in Different Phases, Leq(30min.) dB(A)

NSR

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

N1

84

82

81

80

79

*Bold and shaded cell denotes exceedance

 

Use of Temporary Noise Barriers & Machinery Enclosures

3.8.6            The erection of noise barriers between noise sources and NSRs represented by N1 will be effective in reducing the noise impact.  Temporary barriers of sufficient height with skid footing and a cantilevered upper portion can be erected within a short distance from stationary plants, and at practicable distance from mobile plants operating over a small work area under a well-defined route, to alleviate the potential construction noise impact.

3.8.7            The minimum effective height of the noise barriers should be as such that no part of the noise sources associated with the operation of the PME should be visible from the target NSRs to be protected. The guidelines given in the Booklet entitled “A Practical Guide for the Reduction of Noise from Construction Works” issued by EPD is recommended to be followed by the appointed contractor in the design of the temporary acoustic barriers.  Barriers should have no openings or gaps, and preferably have a superficial surface density of at least 10 kg/m2.  The locations of the temporary noise barriers shall be adjusted where and when necessary taking into consideration the locations and type of PME involved and the NSRs intended to be protected.

3.8.8            Temporary noise barriers shall be provided during the execution of construction phases 1 to 3 and during road reinstatement to be carried out at the conclusion of the underground works.  To mitigate the noise impact from the installation of piles in Phase 2, it is planned to erect a cantilever noise barrier of sufficient height (approx. 7m subject to the exact height of the auger).  Such direct noise mitigation measure has been successfully applied in previous MTRCL’s project - Contract 506B in Mei Foo during the installation of pipe piles and were demonstrated by an Environmental Monitoring and Audit programme to be effective in keeping the noise levels at the nearby NSRs in the proximity to within Leq(30min.) 75dB(A).  The barriers can be made movable to fit the locations of the work areas.  A schematic sectional diagram for the barrier structure is provided in Error! Reference source not found..  In addition to temporary noise barriers, certain types of PME such as compressors can be totally shielded by machine enclosures provided with ventilation, giving a noise reduction of 10 dB(A) or more.  It is expected that proper use of barriers and machinery enclosures for PME can achieve a noise reduction of 10 dB(A) for stationary sources and 5 dB(A) for mobile sources. 

3.8.9            Table 3‑5 presents the further mitigated noise levels predicted at N1 when temporary noise barriers of sufficient effective height and machinery enclosures are used on-site.

3.8.10         Results of the calculation showed that with the combined use of silenced PME, noise barriers and machinery enclosures, construction noise levels at N1 can be mitigated to a maximum of 74dB(A) except in Phase 4. where a maximum noise level of 80dB(A) is predicted.  It is identified that the dominant noise sources associated with the construction works in Phase 4 can be mitigated to acceptable levels, as presented blow, when the opening retained for the road deck is provided with acoustic enclosure.  

 

Table 3‑5     Noise Levels predicted at the RAP N1 (with Silenced PME + Temporary Noise Barriers + Machinery Enclosure)

 

Predicted Noise Levels in Different Phases, Leq(30min.) dB(A)

NSR

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

N1

74

72

72

80

71

 

3.8.11         As shown in the calculations presented in Appendix III, the use of silenced PME and provision of temporary noise barriers and machinery enclosures during the road instatement will also control the potential noise impact to acceptable levels.   

 

Use of Noise Enclosure at the Traffic Deck Opening

3.8.12         Due to the execution of underground excavation works below the road deck, an opening will be retained at a fixed location near the middle of Nathan Road for site access and exporting of excavated material. The erection of a noise enclosure at the opening of the traffic deck in Phase 4 will further reduce the noise impact from the relevant PME.  With the road deck and noise enclosure, all noise generated from construction activities such as loading and unloading of construction and demolition materials carried out will be effectively shielded so that the noise impact on the nearby NSRs will be further reduced to acceptable levels.

3.8.13         Table 3‑6 presents the further mitigated noise levels predicted at N1 when noise enclosure is planned at the traffic deck opening is also considered in the assessment. Worksheet showing the calculation at the RAPs is provided in Appendix III for reference.

3.8.14         Results of the calculation presented in Table 3-4 to Table 3-6 demonstrated that with the combined use of silenced PME, noise barriers, machinery enclosures and deck opening noise enclosure, residential noise impact at N1 can also be mitigated to acceptable levels as other nearby NSRs.

 

Table 3‑6     Noise Levels predicted at the RAP N1 (with Silenced PME + Temporary Noise Barriers + Machinery Enclosure + Noise Enclosure at Traffic Deck Opening)

 

Predicted Noise Levels in Different Phases, Leq(30min.) dB(A)

NSR

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

N1

74

72

72

74

71

 

3.8.15         Use of the proposed noise barriers and noise enclosure, as other construction site equipment and structures onsite, should take into account the following standard requirements of Fire Services Departments:

i)            A minimum of 4.5m wide thoroughfare with not less than 4.5 headroom to be maintained at all times for the free passage of fire appliances;

ii)           Normal operation of nearby street fire hydrants shall not be impeded in that a minimum all round clearance of 1.5m shall be maintained at each hydrant outlet and its controlling ground valve;

iii)         Such enclosure shall not cause obstruction to the movement of the aerial ladder during rescue operation at adjacent buildings;

iv)         A minimum width of 6.5m for the carriageways shall be provided at all times in front of the major facades of the buildings along Nathan Road in order to maintain adequate area and space for fire fighting and rescue operation; and

v)          The total length of the construction area for a noise barrier or enclosure shall be limited to not more than 20m, taking into account the plan that the noise barrier and noise enclosure will not co-exist in the construction works.

3.8.16         The above requirements have been evaluated with the Project Engineering Design Team. It is considered that these requirements, which are common for construction activities of similar nature with the erection of site structures and use of equipment in the territory, can be satisfied without affecting the feasibility to erect the proposed noise barriers and noise enclosure.

3.8.17         The detailed design of the noise barriers and noise enclosure shall take into account the above FSD requirements and other safety issues, while observing the required acoustic effectiveness of the barriers/ enclosure to achieve the acceptable levels at the nearby NSRs.  To illustrate the importance of appropriate barrier design and erection by the Contractor, a sensitivity test based on assuming a noise reduction of 5dB(A) only for both stationary sources and mobile sources when a vertical noise barrier of insufficient height is in use is conducted and the findings are presented in a spreadsheet also given in Appendix III for future reference.

3.8.18         Other practicable noise mitigation measures in form of good site practices and noise management are also recommended below to achieve the acceptable noise levels at the nearby NSRs.

 

 

 

Good Site Practices and Noise Management

3.8.19         Based on the findings of the assessment presented above, it is demonstrated that the potential noise impact arising from the construction of the Southern Concourse Extension together with the pedestrian subway can be alleviated to acceptable levels when the noise mitigation measures recommended above are in place.  To be prudent in the construction noise management, the following additional noise management measures and good site practices are recommended for implementation:

à       the Contractor shall comply with and observe the Noise Control Ordinance (NCO) and its current subsidiary regulations;

à       before the commencement of any work, the Contractor shall submit to the Engineer for approval the method of working, equipment and sound-reducing measures intended to be used at the site;

à       only well-maintained plants should be operated on-site;

à       plants should be serviced regularly during the construction programme;

à       machines that may be in intermittent use should be shut down or throttled down to a minimum between work periods;

à       silencer and mufflers on construction equipment should be utilised and should be properly maintained during the construction programme;

à       noisy activities can be scheduled to minimise exposure of nearby NSRs to high levels of construction noise.  For example, noisy activities can be scheduled for midday or at times coinciding with periods of high background noise (such as during peak traffic hours);

à       noisy equipment such as emergency generators shall always be sited as far away as possible from noise sensitive receivers;

à       mobile plants should be sited as far away from NSRs as possible; and

à       material stockpiles and other structures should be effectively utilised as noise barrier, where practicable.

 

3.9               Potential Cumulative Noise Impact

3.9.1            With reference to the approved EIA report carried out for KCRC East Rail Extension – Hung Hom to Tsim Sha Tsui (ETS-EIA), consideration has been given to evaluation of potential cumulative construction noise impact.  The NSRs that could be subject to cumulative noise impact from construction activities at separate worksites of two projects - “East Rail Extension Hung Hom to Tsim Sha Tsui” and “Salisbury Road Underpass and Associated Road Improvement Works including Middle Road Circulation System” were identified from the ETS-EIA Report to include the representative assessment points N10 ETS-EIA (Mirador Mansion) and N4 ETS-EIA (Far East Mansion) (Table 5.1 and Figure 5-1 in ETS-EIA refers).   

3.9.2            KCRC has advised that a firm programme for construction activities at the western end of Mody Road for the Mody Road Link is currently not available.  In the absence of such information, the worst-case scenario has been assessed in the analysis of the possible cumulative noise impact on N1 (Chungking Mansions) and N2 (Mirador Mansion) which are the NSRs located closest to the KCRC Mody Road worksite and Middle Road worksite studied in the assessment.  Since the noise level at N1 has not been predicted in the ETS-EIA report, the maximum noise level of 79dB(A) predicted at N4ETS-EIA Far East Mansion in ETS-EIA (Table 5.5b in ETS-EIA for Far East Mansion), which will also be affected by the Middle Road Link construction, has been made reference to and corrected for distance to predict the corresponding noise level at N1.

3.9.3            Table 3‑7 below presents the assessment on potential cumulative noise impact associated with the event of concurrent construction activities associated with the TST Station modifications and KCRC Mody Road Link and Middle Road Link construction.  In reality, it expected that the concurrent operation representing the worst-case situation would be a rare event.

Table 3‑7     Evaluation of Potential Cumulative Noise Impact

NSR

Worst-case mitigated noise levels, Leq(30min.) dB(A)

 

MTRC TST Station Modifications

KCRC East Rail Extension

Concurrent construction activities

N1

74 (Table 3-6 refers)(i)

61(iii)

74

N2

74 (Table 3-3 refers)(ii)

84

84(iv)

(i) Mitigated noise levels;

(ii) Worst-case unmitigated noise level;

(iii) Calculated noise level at N1 based on the maximum noise level of 79dB(A) predicted at Far East Mansion (Table 5.5b in ETS-EIA for Far East Mansion refers);

(iv) Indirect technical remedies in the form of upgraded glazing and air-conditioners will be provided at Mirador Mansion at Mody Road in accordance with the permit condition issued for East Rail Extension – Hung Hom and Tsim Sha Tsui

 

3.9.4            The assessment results indicated that due to the significant distance separation of N1 from Middle Road, the potential cumulative construction noise impact is not a concern.  On the other hand, the noise level predicted at N2 due to the TST Station modifications is at least 10dB(A) below the noise impact generated from the Mody Road Link constrution works.  Therefore, the noise generated from the TST Station modifications will not give any noticeable contribution to the overall noise impact at N2 when the Mody Road Link construction works are taking place.  Besides, with reference to the ETS-EIA Report and the environmental permit issued for the KCRC Hung Hum to Tsim Sha Tsui Extension, indirect technical remedies in the form of upgraded glazing and air-conditioners will be provided for the protection of Mirador Mansion at Mody Road. 

 

     

3.10          Operational Phase Impact

3.10.1         The proposed TST Station southern extension and pedestrian subway will operate underground. Provision of additional vent shaft was not identified to be required.  Operation of the project is not expected to give rise to any unacceptable noise impact during the operational phase.

 

EM&A Requirements

3.10.2         In order to protect the nearby NSRs from unacceptable construction noise impact, the implementation of the recommended construction noise mitigation measures should be checked through by a regular construction noise monitoring and audit programme.  Details on the noise monitoring requirements, methodology and action plans are described in the EM&A Manual issued as a stand-alone document.

3.10.3         Since implementation of sufficient direct noise mitigation measures will reduce the potential noise impact to acceptable level, the carrying out of weekly monitoring of noise levels with increase in monitoring frequency triggered by the action/ limit level is considered sufficient to check the adequacy of direct noise mitigation measures in place from time to time.

3.11          Conclusion

3.11.1         The potential impact of construction noise has been conservatively predicted with assumptions of a typical construction schedule and combinations of different powered mechanical equipment likely to be in use.  Whilst the contractor may prefer to use different types and numbers of plant, the above assessment will give information on the individual and combined SWLs of the PME that could be used given the locations of the nearby existing NSRs such that the overall noise levels at the NSRs will be within the daytime construction noise limits.

3.11.2         The assessment has predicted that the unmitigated noise impact at the nearest NSRs could reach a maximum noise level up to Leq(30min.) 85dB(A).  Sufficient practicable direct mitigation measures have been recommended, in addition to the measures- including the phasing and sequencing of construction activities and minimise the number of PME working together in each phase- which have been built into the construction work method.  These additional noise control measures include the use of silenced PME, temporary noise barriers, machinery enclosure, noise enclosure for the road deck opening, and good site practice as well as noise management.

3.11.3         Quantitative assessments indicated that the combined use of the recommended noise mitigation measures can alleviate the construction noise impacts at all potentially affected NSRs to levels satisfying the noise assessment criteria for daytime construction activities. 

3.11.4         Potential cumulative noise impact arising from possible concurrent activities for the TST Station modifications and the East Rail Extension – Hung Hom to Tsim Sha Tsui (Mody Road Link and Middle Road Link) has been assessed.  The noise assessment results revealed that potential cumulative noise impact is not a concern.

3.11.5         Construction activities during the restricted hours are under statutory control and would require a valid construction noise permit issued by the Authority before construction works, if needed, can take place within the restricted hours.

3.11.6         The contractor shall be, from time to time, aware of the noise impact on the surrounding NSRs through active liaison with the Environmental Team who shall undertake regular noise monitoring weekly during the whole course of the project when civil works are carried out so that adjustments could be made in modifying or increasing the level of direct noise mitigation measures.  The proposed mitigation measures will have an effect to mitigate any unacceptable noise impact once these measures are properly provided and maintained. These monitoring requirements shall be triggered by an Event Contingency Plan (ECP) as part of the EM&A which should be incorporated into the works contract so as to make it enforceable.

3.11.7         Implementation of the construction noise mitigation measures, procedures and protocols as recommended shall be ensured through incorporation into the works contract to ensure their enforceability.  The carrying out of weekly monitoring of the noise levels, with increase in monitoring frequency triggered by the action/ limit level, is considered sufficient to check the implementation and adequacy of direct noise mitigation measures in place from time to time. 

 

4.                  Construction Dust Impact Assessment

4.1              Introduction

4.1.1            This section presents an air quality impact assessment for the construction of the Project.  The key air quality issues of interest will be fugitive dust emissions during the construction phase.

4.1.2            The criteria and guidelines as laid down in Annexes 4 and 12 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO TM) have been followed in the assessment. The study area for the air quality assessment covers an area within 500m from the construction worksite.

 

4.2              Legislation and Guidelines

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 the 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 Total Suspended Particulates (TSP) 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)

TSP

N.A.

N.A.

260

80

     (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            On the other hand, Annex 4 Clause 1.1(b) in EIAO TM requires consideration of the hourly TSP limit of 500mg/m3 as assessment criteria in construction dust impact assessment.  Table 4‑2 summarises the dust assessment criteria used in the study.

 

Table 4‑2     Air Quality Criteria Adopted in this Assessment

 

Average Concentration (mg/m3)

Air Pollutant

1-hour

24-hour

TSP

500

260

 

4.2.3            The Air Pollution Control (Construction Dust) Regulation came into effect since 16 June 1997. Contractors and site agents are required to inform EPD and adopt the required dust control measures to cut down dust emissions to an acceptable level while carrying out construction works.

 

4.3              Ambient Air Quality

4.3.1            It is considered not necessary to carry out on-site ambient air quality monitoring for the purpose of the air quality impact assessment because short-term monitoring is not able to give representative background air pollutant levels.  Rather, the background air pollutant levels can be assumed to be in line with the available data obtained at EPD’s Air Quality Monitoring Station in Central/Western.  Table 4‑3 summarises the annual average concentrations of TSP monitored at EPD’s Station in years 1997 to 1999.

 

Table 4‑3     Annual Average Concentrations of TSP measured at EPD’s Air Quality Monitoring Station in Central/Western from 1997 to 1999

Air Pollutant

Concentration (mg/m3)

 

1997

1998

1999

Average

TSP

84

77

81

81

 

4.3.2            For purpose of the air quality impact assessment, the average value of the air pollutant concentrations obtained from 1997 to 1999 has been adopted i.e. 81 mg/m3 for TSP.

 

4.4              Assessment Approach

4.4.1            The primary source of potential air quality impact is expected to be attributable to fugitive dust emissions generated from excavation activities and material handling before the construction of the road deck and noise enclosure.  Significant impact from emissions of the other criteria pollutants such as nitrogen oxides (NOx), sulphur dioxide (SO2), and carbon monoxide (CO) is not anticipated, as emission of these pollutants in large quantity from on-site machinery is considered unlikely.

4.4.2            Dust levels at representative assessment points situated nearest to the site have been predicted quantitatively using a Gaussian dispersion model - “Fugitive Dust Emission” (FDM). Potential cumulative dust impact due to possible concurrent construction activities at nearby worksites including construction works for the Mody Road Link and Middle Road Link has also been assessed, taking into account the background dust levels in the study area to simulate the worst-case scenario.

4.4.3            In order to maintain traffic flows on Nathan Road and to minimise the environmental impact associated with the construction works, construction activities for site clearance and the road deck construction will be carried out on a lane-by-lane basis.  Once the road deck is completed, all bulk excavation works will be effectively enclosed underground.  The opening retained for site access and exporting of excavated material will also be provided with a noise enclosure.  It is expected that based on the proposed construction phasing and sequencing, only limited dust emission will be generated and will arise from excavation activities associated with the initial site clearance  for the subsequent temporary road deck construction. 

 

 

4.4.4            Dust emissions associated with material handling and excavation during the site clearance phase representing the worst-case situation has been modelled quantitatively using the “Fugitive Dust Model” (FDM). The unmitigated dust emission rates (Table 4‑4) have been referenced to the EIA carried out for the Hung Hom to Tsim Sha Tsui East Rail Extension. Given the progressive nature of the construction works, the dust emission sources have been assumed to be located at different work positions in turn within the project site boundary.  Separate air quality models were then developed and the worst-case maximum TSP levels for each assessment points based on the models were determined and reported.  A table and a figure showing the dust emission source locations (W1 to W26) are presented in Appendix IV.  Dust particle size distribution adopted is presented in Table 4‑5.

 

Table 4‑4     Unmitigated TSP Emission Factors for Site Activities

Activities

Emission Factors (g/m2/s)

Material Handling

1.96 x 10-7

Excavation

1.89 x 10-7

 

Table 4‑5     Dust Particulate Size Distribution

Dust Size (mm)

Fraction

10

0.2

30

0.8

 

 

4.5              Air Sensitive Receivers

4.5.1            To capture the worst-case situations, representative air sensitive receivers located in close proximity to the worksite at different directions were selected.  Figure 4-1 shows the locations of the selected representative Air Sensitive Receivers (ASRs). These representative ASRs are described in Table 4‑6.  Given their closest position, it is expected that should the dust impact on these worst affected representative ASRs be identified to be within acceptable levels, dust impact on other ASRs located at further distance away from the project site will also be within acceptable levels.  Particulate levels were predicted at the representative ASRs at 5.6mPD (i.e. 1.5m above ground level).

 

Table 4‑6     Representative ASRs for the Dust Emission Impact Assessment

ASR

Type of ASRs

Description

Horizontal Distance from Worksite Boundary (m)

A1

Residential + Shop

Mirador Mansion

41.8

A2

Hotel + Shop

Holiday Inn Hotel

0.7

A3

Hostel + Shop

Chungking Mansion

0.6

A4

Hostel + Shop

Chungking Mansion

0.4

A5

Hostel + Shop

Chungking Mansion

0.5

A6

Hotel + Shop

Imperial Hotel

0.6

A7

Shop

Oterprise Square

8.5

A8

Hotel + Shop

Kowloon Hotel

9.4

A9

Shop

Prestige Tower

10.3

A10

Office + Shop

Alpha House

6.1

A11

Office + Shop

Alpha House

6.0

A12

Hotel + Shop

Hyatt Regency Hotel

19.4

A13

Hotel + Shop

Hyatt Regency Hotel

8.6

A14

Hotel + Shop

Hyatt Regency Hotel

10.2

 

 

4.6              Modelling Methodology

4.6.1            Construction dust impact arising from site formation works 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 and area sources.

4.6.2            The following meteorological data of the year 1998 relevant to the study have been obtained from Hong Kong Observatory and used in the modelling study of the dust emission impact assessment:

à             Hourly wind direction and speed, air temperature together with atmospheric Pasquill stability class at the Hong Kong Observatory Headquarters in Tsim Sha Tsui;

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.

4.6.3             The worst-case situations were assumed in the air quality model.  Given the stringent noise limits that need to be satisfied for construction works within the restricted hours, it has been assumed in the dust model that the working hours for construction activities will be restricted to 0700 to 1900 hours only. Maximum 1-hour average and 24-hour average TSP concentrations were predicted at the representative ASRs and compared with the 1-hour and daily TSP limits of 500mg/m3 and 260mg/m3, respectively after summation with a background TSP level of 81mg/m3.

 

4.7              Modelling Results

4.7.1            The predicted highest 1-hour and daily average TSP concentrations at the representative ASRs at the modelled heights are shown in Table 4‑7.  Appendix III presents a typical FDM data and result file for reference.  The modelling results showed that the unmitigated cumulative dust levels under the worst-case situations including all dust sources plus the background dust level will be within the relevant assessment criteria presented in Table 4‑2. 

4.7.2            Error! Reference source not found. shows the contours of predicted 1-hour average TSP concentration at 5.6mPD (1.5m above ground) with background TSP concentration included. The modelling results revealed that the construction activities will unlikely generate any unacceptable air quality impact on the nearby ASRs.

 

Table 4‑7     TSP Levels predicted at the representative ASRs

 

Predicted TSP Concentration (mg/m3)

ASR

1-Hour Results (at various heights, mPD)

24-Hour Results (at various heights, mPD)

 

5.6

10.6

15.6

20.6

5.6

10.6

15.6

20.6

A1

82

81

81

81

81

81

81

81

A2

109

81

81

81

88

81

81

81

A3

95

81

81

81

86

81

81

81

A4

115

81

81

81

87

81

81

81

A5

95

81

81

81

85

81

81

81

A6

91

81

81

81

85

81

81

81

A7

84

81

81

81

82

81

81

81

A8

86

81

81

81

83

81

81

81

A9

85

81

81

81

83

81

81

81

A10

87

81

81

81

84

81

81

81

A11

89

81

81

81

85

81

81

81

A12

83

81

81

81

82

81

81

81

A13

86

81

81

81

83

81

81

81

A14

84

81

81

81

82

81

81

81

N.B. : A background TSP level of 81 mg/m3 has been included in the results.

 

4.8               Required Dust Control/ Mitigation Measures

4.8.1            The modelling results confirm that the project will unlikely generate a significant construction dust impact.  Dust control measures stipulated in the Air Pollution Control (Construction Dust) Regulation should be incorporated into the Contract Specifications and be implemented to control dust generation to acceptable levels.  A number of practicable dust mitigation measures are summarised below:

(i)         dusty vehicle loads transported to and from the work location should be covered by tarpaulin sheets and should not be overloaded;

 

(ii)        dusty material should be sprayed with water immediately prior to any loading, unloading or transfer operation to minimise dust emission;

 

(iii)       routing of vehicles and positioning of dust generating construction plant at maximum possible separation distances from ASRs;

 

(iv)      watering of all dust emission sources when necessary;

 

(v)        side enclosure and covering, by impervious sheeting where practicable, of any aggregate or other dusty material storage piles, placing of stockpiles in an area sheltered on the top and the three sides, and/or sprayed with water or a dust suppression chemical so as to maintain the entire surface wet.

 

(vi)      drop height of excavated materials should be controlled to a minimum to limit fugitive dust generation from unloading as far as practicable;

 

(vii)     demolished items shall be covered by impervious sheeting or placed in area sheltered on the top and the three sides within a day of demolition.

 

(viii)    instigation of a programme to monitor the construction process in order to enforce controls and modify methods of work if dusty conditions arise.

 

4.9              Potential Cumulative Dust Impact

4.9.1            KCRC has advised that a detailed construction programme showing the timing of construction activities at different site locations is currently not available.  To simulate the worst case scenario in the air quality study, possible cumulative impacts arising from concurrent construction works for the KCRC East Rail Extension, as well as the Salisbury Road Underpass and Associated Road Improvement Works in the study area have been assessed. 

4.9.2            The cumulative TSP concentrations presented in the ETS-EIA, as reported, represents the cumulative effect resulting from concurrent construction activities for KCRC East Rail Extension as well as Sailisbury Road underpass and Associated Road Improvement Works.

4.9.3            Given that the exact dust levels at the various assessment points selected in the study due to construction activities associated with the KCRC East Rail Extension and Salisbury Road Underpass and Associated Road Improvement Works are not available, the findings on worst-case maximum 1-hour and 24-hour average TSP levels predicted at a number of worst-affected ASRs have been made referenced to for the purpose of the evaluation.  These ASRs include Titus Square, Kowloon Hotel, Mirador Mansion and Holiday Inn Hotel (A22, A24, A37 and A38 as shown in Table 6.1, ETS-EIA).  A simple summation of the predicted TSP concentrations represents a conservative approach in the prediction.

 

Table 4‑8     Predicted Maximum Ground Level 1-Hour & 24-Hour TSP Concentration (Cumulative)

 

Predicted 1-Hour and 24-Hour TSP Concentration (mg/m3)

 

 

MTRC TST Station Southern Concourse Extension

(excluding background concentration)

Salisbury Road Underpass and Haul Roads

(excluding background concentration)

East Rail Extension

(excluding background concentration)

Cumulative Impact*

(including background concentration)

ASR reference in ETS-EIA#

ASR

1-Hour Average

24-Hour Average

1-Hour Average

24-Hour Average

1-Hour Average

24-Hour Average

1-Hour Average

24-Hour Average

 

A1

1

0

30

5

4

2

116

88

A37

A2

28

7

30

6

4

2

143

96

A38

A3

14

5

30

6

4

2

129

94

A38

A4

34

6

30

6

4

2

149

95

A38

A5

14

4

30

6

4

2

129

93

A38

A6

10

4

62

7

142

71

295

163

A22

A7

3

1

62

7

142

71

288

160

A22

A8

5

2

43

4

186

93

315

180

A24

A9

4

2

43

4

186

93

314

180

A24

A10

6

3

43

4

186

93

316

181

A24

A11

8

4

43

4

186

93

318

182

A24

A12

2

1

43

4

186

93

312

179

A24

A13

5

2

43

4

186

93

315

180

A24

A14

3

1

43

4

186

93

313

179

A24

*A background TSP level of 81 mg/m3 has been included in the cumulative results.

# Worst-case 1-hour and 24-hour average TSP levels at the assessment points A1 through A14 were assumed based on the predicted dust levels predicted at the relevant ASRs considered in the ETS-EIA. These ASRs include A22-Titus Square; A24-Kowloon Hotel; A37-Mirador Mansion; A38-Holiday Inn. 

 

4.9.4            The modelling results presented in Table 4‑8 above demonstrated that potential cumulative dust impact on the nearby ASRs should not be a concern, especially when each of the individual construction site are required to implement sufficient dust control measures in accordance with the requirements under the Air Pollution Control (Construction Dust) Regulation. 

 

4.10          Operational Phase Impact

4.10.1         The proposed southern concourse extension and pedestrian subway design will operate underground. No additional vent shaft was identified to be required. It is not expected that operation of the project will result in any air quality impact on the surroundings during operational phase.

 

4.11          Environmental Monitoring and Audit Requirements

4.11.1         It is recommended that an Environmental Monitoring and Audit (EM&A) Programme be implemented during the construction phase of the development to check the implementation of the recommended dust mitigation measures. This will enable the contractor to identify the potential dust emission problem, and react immediately when the dust criteria are approached by increasing the level of dust mitigation measures.  Details of the recommended EM&A are presented in the EM&A Manual.

 

4.12          Conclusion

4.12.1         Fugitive dust emission due to construction activities associated with the proposed TST Station concourse extension and Nathan Road subway link has been assessed.  Potential cumulative dust impact due to concurrent construction activities for other projects in the vicinity have also been assessed.

4.12.2         The assessment results demonstrated that implementation of the project will unlikely pose any unacceptable air quality impact on the nearby sensitive receivers.  Taking into account the background TSP level and dust emission generated from other nearby construction sites under the worst-case situation when there are concurrent construction activities, the predicted dust levels at the ASRs are satisfying the relevant Air Quality Objectives.

4.12.3         Implementation of sufficient mitigation measures in accordance with the requirements under the Air Pollution Control (Construction Dust) Regulation will ensure that, as predicted, the dust impact at the ASRs be alleviated to acceptable levels.  An EM&A programme is recommended to be in place during the construction phase of the project to check for the implementation and adequacy of dust mitigation measures to protect the nearby Air Sensitive Receivers (ASRs).

 

5.                  wASTE mANAGEMENT

5.1              Introduction

5.1.1            This section identifies the types of waste likely to be generated during the construction of the Project, and assesses the waste management implications in accordance with the criteria and guidelines given in Annex 7 and Annex 15 of the EIAO TM.  Clause 3.5.4 of the EIA Study Brief sets out the scope and requirements of the assessment.

5.1.2            It is recognised that the quantity of waste associated with the construction works is relatively small and will mainly involve excavated material. Besides, given the progressive nature of the construction works, the quantity of excavated material generated daily would be limited. Nevertheless, given that density of the built-up area surrounding the project site, proper waste management is considered necessary to avoid generation of any significant environmental impact associated with the handling, collection and disposal of construction waste. Environmental mitigation measures required to mitigate these environmental impacts were identified and recommended. 

5.1.3            Waste management during the operational phase would be similar to the existing operation in TST Station and other MTR Stations and is not expected to be key issue in the EIA study.

 

5.2              Legislation and Guidelines

5.2.1            The principle legislation governing waste management in Hong Kong is the Waste Disposal Ordinance (Cap. 354) (WDO), and its subsidiary regulations.  The Ordinance, enacted in 1980, generally encompasses all stages of waste management, from place of arising to final disposal point of waste.  The Waste Disposal (Chemical Waste) (General) Regulation, enacted under the WDO in 1992, provides controls on all aspects of chemical waste disposal, including storage, collection, transport, treatment and final disposal.

5.2.2            In addition to the WDO and its subsidiary regulation, the following legislation have some bearing on the handling, treatment and disposal of wastes in Hong Kong, viz.,:

·        Dumping at Sea Ordinance (1995);

·        Crown Land Ordinance (Cap. 28);

·        Public Health and Municipal Services Ordinance (Cap. 132) Public Cleansing and Prevention of Nuisances (Urban Council) and (Regional Council) By-laws; and

·        Dangerous Goods Ordinance.

5.2.3            There are also various guidelines which are relevant to waste management in Hong Kong. Technical Circulars issued for Government projects are also stated below for reference:

·        Waste Disposal Plan for Hong Kong (December 1989), Planning, Environmental and Lands Branch Government Secretariat;

·        New Disposal Arrangements for Construction Waste (1992), Environmental Protection Department & Civil Engineering Department;

·        Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes (1992), Environmental Protection Department;

·        Works Branch Technical Circular No. 6/92, Fill Management;

·        Works Branch Technical Circular 22/92, Hong Kong Government;

·        Works Branch Technical Circular No. 2/93, Public Dumps;

·        Work Branch Technical circular No. 16/93, Wet Soil in Public Dumps;

·        Works Bureau Technical Circular No. 5/98, On Site Sorting of Construction Waste on Demolition Sites;

·        Works Bureau Technical Circular No. 5/99, Trip-ticket System for Disposal of Construction and Demolition Material;

·        Works Bureau Technical Circular No. 25/99, Incorporation of Information on Construction and Demolition Material Management in Public Works Subcommittee Papers;

·        Technical Circular No. 11/92 Classification of Dredging Sediments for Marine Disposal, Environmental Protection Department;

 

5.3              Construction Waste Management

General

5.3.1            The key construction activities are stated below.  The quantity of waste generated from each construction stage is also evaluated:

·        Site clearance - waste generation expected is minimal;

·        Road and pavement demolishing and deck installation - the amount of works expected is minimal;

·        Underground excavation – quantity of excavated material is estimated to be in the order of 100m3 per day;

·        Concourse extension and underground subway construction – quantity of waste is expected to be minimal;

·        Reinstatement of road and pavement – minimal waste generation is expected

5.3.2            The waste categories that would be generated are identified to include the following:

·        Construction and demolition material (C&D material) – will form the major portion of waste generated and will involve mainly inert excavated material;

·        Chemical waste – quantity is expected to be limited;

·        General refuse - quantity is expected to be insignificant given the build-up nature of the area surrounding the worksite.

5.3.3            The nature and quantity of each of these waste types arising from the construction phase of the Project are evaluated below.  The potential environmental impacts, which may arise from the handling, storage, transport and disposal of each waste type, are then assessed.  Prior to consideration of disposal options for each waste type, opportunities for waste reduction, reuse, or recycling were identified.

 

Construction and Demolition (C&D) Material

5.3.4            The construction phase when the highest quantity of excavated material would be generated will arise when underground excavation works are carried out.  It is preliminary estimated that a total quantity in the order of 100m3 per day of excavated material would be generated, giving a total quantity in the order of 12,000m3.  The excavated material is expected to be the only major source of C&D material, which will be inert suitable for reuse in public filling areas or other reclamation sites.  The amount of non-inert C&D waste will be insignificant and shall be disposed of at landfills when encountered.  

5.3.5            Based on the preliminary design of the modification, an estimated total quantity of approximately 2,600m3 imported general fill is required for backfilling the top of the extended station box and subway.  The possibility to retain some of the excavated material generated onsite for subsequent reuse as backfill material after the completion of the station box and subway construction was evaluated with the Project Engineers but not considered practicable, considering the quality of the excavated material in meeting the necessary engineering function.  Given the necessary lane-by lane-progressive approach to the construction activities in order to maintain the traffic on Nathan Road, the work area available for the construction works will be very limited.  Storage of excavated material onsite is not considered practicable as the site is small and could become a source of nuisance to the public.  Possible offsite reuse of the excavated material at other MTRCL’s project sites will be subject to the meeting of the necessary engineering requirements depending of the functions of the fill material required and is a function of the actual relative timing of other projects.  The offsite reuse opportunities can be reviewed during the detailed design stage and by the appointed Contractor.

5.3.6            The excavated material generated daily onsite during the excavation work period should be immediately delivered to a truck parked within the noise enclosure and delivered to another MTRC project site, a public filling area or other reclamation sites as appropriate.  Assuming a 10 hours working day and a truck capacity of 7.5m3, it can be calculated that the average number of trucks involved is 1.3 per hour.

5.3.7            The excavated material is expected to be inert waste and is not expected to give rise to any potential hazard during the handling, collection and disposal. 

5.3.8            Air and noise emissions would also be limited as the activities will be carried out below the road deck and within the noise enclosure. The excavation activities will be land based and are not expected to generate any significant water quality impact.

 

Chemical Waste

5.3.9            As defined under the Waste Disposal (Chemical Waste) (General) Regulation, chemical waste includes any substance being scrap material or unwanted substances specified under Schedule 1 of the Regulation.  The rate of chemical waste generation from the construction work is anticipated to be limited but would arise from time to time associated with the operation and maintenance of on-site equipment.  These may include fuel, oil, lubricants, cleaning fluids and other solvents.  Chemical generated from daily operation of the construction works shall be recycled/ reused on-site as far as practicable before the disposal option should be considered.  If off-site disposal of chemical waste is required, they should be collected and delivered by licensed contractors to Tsing Yi Chemical Waste Treatment Facility and be disposed of in strict accordance with the Waste Disposal (Chemical Waste) (General) Regulation. Contractors shall register with EPD as chemical waste producers when disposal of chemical waste is anticipated to be required.  Chemical waste materials have to be stored within suitable containers so that leakage or spillage is prevented during the handling, storage, and subsequent transportation.

5.3.10         Provided that the handling, storage, reuse and disposal of chemical wastes are in accordance with the Waste Disposal (Chemical Waste) (General) Regulation and the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, it will not cause an unacceptable environmental impact and the issue is not discussed further.  

 

General Refuse

5.3.11         Throughout the construction phase, the workforce on the construction site would generate a variety of general refuse requiring disposal.  It is expected that these refuse will mainly consist on food wastes, aluminium cans, and waste paper, etc.  The above ground work area is very limited so that only a few workers can work together. Activities such as eating and smoking are expected to be prohibited and not preferred by the workers below the road deck.  Given the limited work area, and the presence of existing general refuse disposal facilities in the vicinity of the work area that can be made use of by the workers, it is expected that the quantity of general refuse generated within the construction work site requiring disposal would be very limited.  Nevertheless, a reliable waste collector shall be assigned by the Contractor to collect general refuse generated from the construction site on a daily basis to minimise the potential odour, pest and litter impacts.

Overall Waste Management

5.3.12         A Preliminary Waste Management Plan (WMP) is presented in Appendix V.  To ensure the appropriate handing of the C&DM, the contractor will be required to prepare a WMP for submission to EPD.  Apart from those conditions listed out in Appendix V, this WMP shall also contain:

(i)         details of the construction wastes such as location of the stockpile sites, breakdown of different categories of waste, disposal routings and the timing for peak disposal, etc; and

(ii)        a trip-ticket system, or equivalent, to monitor waste disposal arising from the project.

5.3.13         The following additional control/ mitigation measures are recommended to be followed by the Contractor:

(i)          Storage of different waste types - different types of waste should be segregated and stored in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal.  A temporary storage area equipped with required control measures (e.g. dust) should be provided onsite or off-site for temporary storage of chemical waste;

(ii)         Monitoring waste disposal – the Contractor shall propose the means by which he will monitor and record waste produced for agreement with MTRCL and on the advice of EPD;

(iii)       Records of Wastes - a recording system for the amount of wastes generated, recycled and disposed (including the disposal sites) should be proposed;

(iv)       Training - training should be provided by the Contractor to workers in respect of site cleanliness and appropriate waste management procedure, including waste reduction, reuse and recycling, and avoid contamination of reusable C&DM.

 

5.4              Construction Waste EM&A Requirements

5.4.1            In order to ensure that each construction waste stream generated from the construction phase of the Project are managed in accordance with the procedures recommended in this EIA, it is recommended that regular auditing by an Environmental Team be carried out.  The regular audit should look at all aspects of waste management including waste generation, storage, recycling, reuse, transport and disposal, though recognising that the waste generation from this site is not significant.

 

5.5              Conclusion

5.5.1            The waste streams that would be generated during the construction phase of the roadwork project were identified and evaluated in terms of their quantity, type and nature.  Opportunities for reduction in waste generation through reuse or recycling are identified.  The waste management implications and potential environmental impacts associated with the handling, transport, and disposal of the identified waste types are addressed.  Mitigation measures based on good practices have been recommended for each waste type to address any potential environmental impacts. 

5.5.2            A Waste Management Plan (WMP) is defined and will be implemented by the appointed Contractor.  In addition, an audit programme is recommended to be in place during the construction phase to check that the waste generated from the construction site are being managed in accordance with the recommended procedures.  Handling and disposal of waste generated during construction is not expected to give rise to any significant dust, noise or water quality impact.

5.5.3            Provided that the recommendations set out in this section are implemented, no waste related regulatory non-compliance and unacceptable environmental impacts is expected to arise from the handling, storage, transport and disposal of wastes during the construction and operation phases of the Project.

6.                  Other Environmental Factors

6.1              Introduction

6.1.1            This chapter includes a review of other environmental factors to confirm that these are not key environmental issues associated with the project and are therefore not required to be assessed in the EIA Study Brief.

 

6.2              Water Quality Impact

Potential Sources of Water Pollution

6.2.1            The proposed construction work may pose a water quality impact mainly due to the discharge of surface runoff contaminated by suspended solids, which would be particularly generated as a result of excavation activities and implementation of dust suppression measures. The construction activities will all be land-based.  Direct impact on water in Victoria Harbour WCZ is therefore not anticipated.  Based on the nature of the construction works, major sources of water pollution are identified to include:

à             runoff and erosion from exposed soil surface;

à             drainage from dust suppression sprays;

à             runoff from stockpiles;

à             fuels and lubricants from machinery and trucks;

à             liquid spillage such as chemical, oil, diesel, and solvent;

à             general waste material;

à             wastewater generated from dewatering activities.

 

Suspended Solid arising from the Project

6.2.2            Implementation of the southern extension and Nathan Road Link will require the excavation and disposal of excavated material.  Practicable mitigation measures shall be implemented to prevent, as far as practicable, the direct contact of excavated spoil with runoff and measures to abate pollutants in the stormwater runoff through appropriate design of the noise enclosure and road deck.

6.2.3            Additional impacts on water could arise from runoff that is contaminated by chemical, oil, diesel, lubricant, and solvent, etc. due to spillage or improper disposal. Implementation of Best Management Practices (BMPs) by the contractor during the project period will ensure the control on the release of these waste types.  In addition to excavation activities, wastewater could also be generated from other phases of works such as site clearance and road reinstatement.

 

Recommended Mitigation Measures

6.2.4            Control of potential water quality impact arising from the construction phase shall be effected based on the following principles:

(i)      prevention or minimisation of the likelihood of the above identified pollutants being in contact with rainfall or runoff; and

(ii)     measures to abate pollutants in the stormwater runoff.

6.2.5            These principles shall be achieved through the implementation of the Best Management Practices (BMPs) in controlling water pollution during the construction phase.  The guidelines for handling and disposal of construction site discharges as detailed in EPD’s ProPECC Note PN1/94 “Construction Site Drainage” should be followed.

 

6.3              Ecological and Archaeological/Cultural Heritage Impact

6.3.1            The construction site is located on an existing road in a built-up area with high-rise development nearby. Potentially affected receivers are restricted to the nearby landuses in terms of construction noise and dust impact.  No ecological and cultural heritage impacts are identified to be associated with the project.

 

6.4              Landscape and Visual Impact

6.4.1            Both the Southern Extension and pedestrian links are located underground. No significant landscape and visual impacts are expected to be of concern during the operational phase.  There may be some short-term effect during the execution of the lane-by-lane construction works, though the worksite would be surrounded by traffic on Nathan Road.  Once the road deck is constructed, the bulk excavation activities and the subsequent station and subway construction would be carried out under the deck and will not pose any landscape and visual impact on the surrounding sensitive receivers.  Significant visual and landscape impacts are not anticipated.

 

7.                  Summary of Environmental Outcomes

7.1              Introduction

7.1.1            This chapter of the report summarises key environmental outcomes associated with the MTRCL TST Station Modifications as assessed in the preceding sections.

 

7.2              Environmental Benefits

Encouraging use of Environmentally Friendly Mode of Transportation

7.2.1            Implementation of the proposed Modifications to TST Station and the Nathan Road Subway Link will not only provide sufficient space for the relocation of the displaced plant rooms and station back-of-house accommodation, but also complete a critical “missing” length of subway network to establish an effective interchange between the TST Station and ETS station. 

7.2.2            The establishment of an efficient MTR/ TST interchange at the busy district - Tsim Sha Tsui will provide an attractive interchange facility alternative to the MTR/ KCR interchange at Kowloon Tong. 

7.2.3            The overall scheme will encourage the increased use of the railway system by the public which is an environmentally preferred mode of transportation in terms of air quality resulting in less exposure of the public to road traffic emissions.

 

Environmental Friendly Design Adopted & Problems Avoided

7.2.4            An appropriate alignment and design has been adopted such that upon completion of the permanent works, all new structures associated with the TST Station modifications will not be visible above ground and the erection of a new vent shaft will not be required.

7.2.5            The construction work site is located on the southern side of Nathan Road where most nearby noise sensitive receivers do not rely on opened windows for ventilation. 

7.2.6            The construction works will also be carried out in a progressive approach on a lane-by-lane basis to keep the through traffic on Nathan Road, and control the extent of works. Associated construction noise and dust levels can be mitigated to acceptable levels. 

7.2.7            After the complete installation of the road deck and noise enclosure, all construction activities will be effectively shielded from the nearby sensitive receivers.

 

Benefits of Recommended Environmental Protection Measures

7.2.8            Sufficient dust and noise control/ mitigation measures have been recommended to ensure that the construction impact, though transient, can also be alleviated to acceptable levels. 

7.2.9            The road deck and noise enclosure will also facilitate proper waste management such that the handling, collection and disposal of waste will not result in any unacceptable secondary environmental impact and hazard.  Waste management measures and a Waste Management Plan (WMP) have been developed for implementation by the Contractor.

7.2.10         An EM&A programme has been recommended to check for the implementation, adequacy and improve environmental mitigation implemented by the contractor, if needed. 

 

Population/ Environmentally Sensitive Receivers Protected

7.2.11         All environmental mitigations for this Project are proposed at sources to protect all sensitive receivers in the vicinity. The major sensitive receivers identified above are representative and possible environmental impacts among these receivers have been assessed.

7.2.12         Based on the location of the construction worksite for the proposed modifications to TST Station, the environmental sensitive areas, and population protected from noise impact by the recommended mitigation measures that can be quantified have been estimated.  These are summarised in Table 7‑1.

Table 7‑1     Environmentally Sensitive Receivers and Population Protected from Noise Impact

Uses

Building Areas

Estimated Population Protected from Noise Impact (Approx.)

Hostel

Chungking Mansions along Nathan Road

900

Residential Development

Harilela Mansion and Mirador Mansion facing Nathan Road, Wing Lock House and Mohan’s Building facing Peking Road

1,200

Hotel & Commercial Building

Holiday Inn Hotel, Imperial Hotel, Oterprise Square, Kowloon Hotel, Prestige Tower, Alpha House, Hyatt Regency Hotel

N/A

 

7.2.13         On the air quality side, the implementation of the dust control measures in accordance with the requirements of the Air Pollution Control (Construction Dust) Regulation will protect an estimated population of over 10,000 working or residing in the area.  Proper waste management will avoid the creation of any unacceptable nuisance on the public.

 

8.                  Overall Conclusion

8.1.1            MTR Corporation Limited (MTRCL) proposes to modify the existing MTRC Tsim Sha Tsui (TST) Station in the form of a southward extension, and provision of an associated pedestrian subway along Nathan Road.  Alternative options on alignments and construction methods have been evaluated and justified before arriving at the preferred design scenario. 

8.1.2            The assessments were carried out based on the requirements of the EIA Study Brief (Brief No. ESB-063/2000) issued by the Authority.  The key environmental issues assessed include:

à       Potential dust emission impact during the construction phase;

à       Potential construction noise impact generation; and

à       Construction phase waste management implications

8.1.3            Mitigation measures have been recommended, where necessary, to alleviate all identified environmental impacts/ constraints associated with the project to acceptable levels.  Other environmental factors including water quality, ecological and archaeological/ cultural heritage, landscape and visual issues have also been reviewed and confirmed not to be key concern.

8.1.4            Environmental control measures have been incorporated into the design of the construction works.  Construction activities will be carried out on a lane-by-lane basis only with restricted number of equipment for the construction of a temporary road deck.  Once the road deck is fully completed, all subsequent construction activities will be effectively enclosed.  A noise enclosure is also planned at the deck opening retained for site access and exporting of excavated material.  Though the construction phase impact would be of transient nature, additional control/ mitigation measures have been recommended to address the potential dust and noise impact arising from the construction activities on the nearby sensitive receivers to acceptable levels.  Proper construction waste management measures have also been recommended and the future appointed Contractor will implement the recommended Waste Management Plan.

8.1.5            In the presence of the proposed mitigation measures, implementation of the proposed TST Station southern extension and associated pedestrian subway link on Nathan Road is considered feasible from an environmental perspective and will unlikely pose any unacceptable environmental impact on the nearby sensitive receivers.