1. Introduction

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. Figure A shows the location of the project site. The proposed structure will be located underground and no new ventilation shafts are proposed. It is anticipated that there will not be any adverse environmental impacts associated with the operation phase of this project.

1.2 The proposed modifications to TST Station is regarded as a “material change” to an exempted project under Section 9(4) of the EIA Ordinance (EIAO). MTRCL submitted a Project Profile to Director of Environmental Protection (DEP) on 13 November 2000 to apply for an EIA Study Brief, which was issued to MTRCL after public inspection of the Project Profile. The Objectives and Scope of the EIA Study are described in the EIA Study Brief.

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

2. Project Description

2.1 Implementation of the proposed Mody Road Link as part of the KCRC East Tsim Sha Tsui (ETS) Station requires the relocation of the plant rooms and station accommodation of the TST Station located near the Nathan Road – Mody Road junction. 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.

2.2 Besides, as identified by a pedestrian forecast study, provision of the Mody Road Link will not be sufficient to cope with the demand of the passengers using the MTR/ KRC railway interchange. The need to provide an additional pedestrian subway link at Nathan Road to complete the critical “missing” length of the subway network was identified. The proposed “Nathan Road Link” will serve the passengers as a direct and convenient route between the interchange stations in addition to the “Mody Road Link”. It was predicted in the pedestrian forecast study that the proposed Nathan Road Link would be especially attractive to the passengers using the front half of KCR trains.

2.3 Modifying the existing TST station in the form of an approximately 80m concourse extension to the south of the existing station will not only provide extra space required for accommodation of the plant rooms and back-of-house accommodation at the existing TST Station displaced by the “Mody Road Link”, but will also reduce the length of the pedestrian subway at Nathan Road linking the station with the Middle Road Link to approximately 30m only as illustrated in Figure B. No other alternative design options were identified that could provide such integrated design to connect the existing TST station with the planned Middle Road Link.

2.4 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 a “Preferred Option” as shown in Figure C, which involves an approximately 80m southern concourse extension and an associated 30m long subway link along Nathan Road. Figure D and E illustrates the relationship of the southern extension to the existing bored Tsuen Wan Line tunnels.

2.5 Use of bored tunnelling technique and cut-and-cover technique were identified to be the available methods for the construction works and were reviewed. Use of bored tunnelling technique in the construction project has not been identified to be technically feasible for the following main reasons:

§ shallow depth of the excavation works involved, taking into account the vertical alignment of the existing concourse which predetermines the level of the proposed station extension;

§ presence of the Tsuen Wan Line tunnels beneath the work area which must not be affected by the works; and

§ vary stratigraphy of the site area as identified from site investigation works which will create significant difficulty for bored tunnelling design.

2.6 Use of cut-and-cover technique is identified to be technically feasible due to its simplistic nature. The potential environmental dis-benefits associated with noise and dust emission can be avoided and mitigated by 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.

3. Preliminary construction Programme and sequence

3.1 The construction programme and construction sequence has been formulated with a target to minimise the impact from the construction works on the environment and traffic as a high project objective. A preliminary construction programme is presented in Figure F.

3.2 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 to minimise impact on traffic movement. Existing utilities lying under Nathan Road would be diverted only when necessary and would be hung above the underground excavation site instead if possible such the construction period and hence the associated temporary disturbance can be minimised.

3.3 Temporary piles will be installed for reinstating the traffic lanes and footpath with decking. As shown in the preliminary programme, a complete road deck flush with the existing road surface will be built ultimately to carry Nathan Road traffic while underground excavation works are carried out.

3.4 Excavation will be carried out beneath the deck proceeding layer by layer with regular monitoring of Tsuen Wan Line tunnels integrity. The deck will be removed after the completion of the underground works, and the road and utilities reinstated using again a lane-by-lane progressive approach.

3.5 The key environmental issues associated with the proposed TST Station modifications are identified to include:

i. Potential Construction Noise Impact;

ii. Potential Construction Dust Impact; and

iii. Construction Waste Management Implications.

3.6 The extent of the potential construction phase impact, through transient, has been identified through the EIA Study and sufficient environmental mitigation measures identified to alleviate the impact to acceptable levels. No key environmental issues were identified to be of concern during the operational phase of the proposed modifications.

4. Environmentally Sensitive Receivers

4.1 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 Shui Hing HousePrestige 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. All landuses in the vicinity of the work area are zoned as “Commercial” in the Outline Zoning Plan.

5. Construction Noise Impact Assessment

5.1 Given the location of the site and the need to maintain full traffic on Nathan Road, the construction works will only proceed on a lane-by-lane basis. Given the limited work area, the number of Powered Mechanical Equipment (PME) involved in each stage of construction activities will be limited. The construction phasing will in itself provide some noise mitigation.

5.2 Construction noise is controlled under the Noise Control Ordinance (NCO) which prohibits the use of 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 a permit are specified in the “Technical Memorandum on Noise from Construction Works Other than Percussive Piling”.

5.3 Noise generated the construction works other than percussive piling during the non-restricted hours (i.e. 7 a.m. to 7 p.m. on weekdays other than general holidays) was the focus of the study. The daytime noise assessment criteria are set out in Table 1B in Annex 5 of the Technical Memorandum issued under the EIAO (EIAO-TM).

5.4 Based on the phased construction programme, a reasonable, preliminary PME inventory has been developed by the Project Engineering Design Consultant for the construction noise impact study. While it is expected that the future appointed Contractor may propose a different PME inventory, the quantitative assessment based on this feasible inventory will allow the potential noise problem be realised and that practicable and sufficient noise mitigation measures are derived and planned at this 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 to achieve the acceptable noise levels at the nearby NSRs.

5.5 The results from quantitative assessment demonstrated that with the progressive use of a combination of various practicable noise mitigation measures, the construction noise impact on the nearby NSRs can be mitigated to acceptable levels. The practicable noise mitigation measures recommended include:

Ø Use of quiet PME with lower Sound Power Level;

Ø Erect temporary noise barriers and machinery enclosure;

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

Ø Implement good site practice and noise management.

5.6 To mitigate the noise impact from the installation of piles, a cantilever noise barrier of sufficient height erected between the work area and Chungking Mansions was identified to be required. A schematic drawing showing the preliminary design of the cantilever noise barrier is shown in Figure G. On the other hand, when underground excavation works are carried out underneath the proposed road deck, an acoustic enclosure is recommended to be provided at the deck opening retained for the exportation of excavated material. Figure H shows the preliminary design of the noise enclosure at the deck opening. Potential cumulative noise impact on the same NSRs arising from concurrent construction activities for the TST Station modifications and KCRC East Rail Extension – Hung Hom to Tsim Sha Tsui was evaluated, and was not identified to be a concern.

5.7 MTRCL will require the appointed Contractor to implement sufficient direct noise mitigation measures. Implementation of the recommended noise mitigation measures by the Contractor will be checked by a regular environmental monitoring and audit programme.

6. Construction Dust Impact Assessment

6.1 The key air quality issue of interest during the construction phase of the project is fugitive dust emission. Dust emission will mainly occur during the initial construction period when construction activities are carried out before the road deck is constructed.

6.2 Potential dust impact associated with material handling and excavation has been assessed quantitatively using the air quality model “Fugitive Dust Model” (FDM). Hourly meteorological data for a whole year has been inputted into the air quality model to give the worst case maximum 1-hour and daily Total Suspended Particulate (TSP) concentrations at various representative assessment points. The modelled TSP concentrations were compared with the 1-hour and daily TSP limits of 500mg/m³ and 260mg/m³ respectively after the summation of the background TSP level. The assessment results indicated that the mitigated dust level at the nearby Air Sensitive Receivers (ASRs) will satisfy the air quality criteria.

6.3 In accordance with the requirements stipulated in the Air Pollution Control (Construction Dust) Regulation, sufficient dust mitigation measures shall be implemented to minimise the dust impact to within acceptable levels. Various forms of practicable dust control measures, including frequent watering and enclosure of dust emission sources as stated in the regulation have been highlighted in the EIA for implementation by the Contractor.

6.4 Implementation of sufficient dust control/ mitigation measures will be checked by an Environmental Monitoring and Audit (EM&A) Programme to be carried out by the Environmental Team. This will allow the Contractor to react immediately and take action to increase the level of dust mitigation measures should unacceptable TSP concentrations be monitored.

7. Construction Waste Management

7.1 Construction waste management impact from the execution of the proposed station modification has been assessed. Given the limited scale of the project, generation of a large quantity of construction waste is not expected.

7.2 It is preliminary estimated that a daily quantity of some 100m³ of excavated material on average would be generated from the construction site, giving an estimated total quantity of 12,000m³. The excavated material is expected to be the only major source of Construction and Demolition (C&D) Material, which will be inert and suitable for reuse in public filling areas or other reclamation sites. The amount of non-inert C&D waste is expected to be insignificant and will be disposed of to landfill as far as practicable. 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 but found impracticable given the very limited work area available, the potential environmental nuisance associated with the storage of excavated material for a significant period of time, and considering the quality of the excavated material in satisfying the required engineering requirement for the works. Nevertheless, the Contractor will be allowed and encouraged to consider offsite reuse opportunities of the excavated material before consideration should be given to disposal option at public filling areas.

7.3 To ensure the appropriate handling of construction material and waste, the Contractor shall implement a Waste Management Plan (WMP) as recommended and detailed in the EIA report.

8. cONCLUSION

8.1 The proposed TST Station Modifications will not only provide sufficient space for the accommodation of the plant rooms and station accommodation displaced by the KCRC Mody Road Link, but also complete a critical missing length of subway network to establish an effective interchange between the TST Station and ETS Station. Implementation of the project 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.

8.2 An Environmental Impact Assessment (EIA) has been conducted to address all key environmental issues associated with the proposed TST Station Southern Extension and associated pedestrian subway at Nathan Road. The assessments were carried out based on the requirements of the EIA Study Brief (Brief No. ESB-063/2000) issued by the Authority.

8.3 An appropriate design and alignment has been adopted such that upon completion of the permanent works, there will not be any new structures associated with the TST Station Modifications will may pose an environmental impact on the surrounding sensitive receivers. Adopting a southward concourse extension at Nathan Road will also minimise the length of the associated pedestrian subway leading to the Middle Road Link to serve the public.

8.4 The key environmental issues assessed include potential construction dust impact, construction noise impact and construction waste management. Mitigation measures have been identified and recommended, where necessary, to alleviate all identified environmental impact to acceptable levels. Implementation of sufficient environmental mitigation measures will be checked through a proposed Environmental Monitoring and Audit Programme.

8.5 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.

8.6 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.