Consultancy Agreement No. NEX/2213 EIA Study for Shatin to Central Link - to Admiralty Section MTR Corporation Limited Environmental Impact Assessment Report (Final)

2. CONSIDERATION OF ALTERNATIVES

Introduction

2.1 Various options and alternatives of project design and construction methods have been reviewed and considered in the course of the development and selection of preferred scheme for SCL (HUH- ADM), taking account of engineering feasibility, site constraints, programme and environmental aspects. This section presents the details of the options and alternatives considered, and the constraints and considerations assessed in adopting the preferred scheme and construction method.

Background Information

Purpose and Objective of the Project

2.2 The SCL is strategically important for connecting the existing railway lines into an integrated rail network. The east-west connection, will allow the creation of a 57km east-west corridor across the city connecting with via . The north-south connection will operate over a 41km north-south corridor with services originating in Lok Ma Chau or Lo Wo travelling via the existing to Admiralty Station (ADM). This will facilitate a direct link between Mainland and Island.

2.3 As part of the SCL, the objective of the SCL (HUH-ADM) (which is the Project being considered in this EIA Report) is to extend the existing East Rail Line from (HUH) to the north shore of and the Central Business District, providing convenient interchanges at HUH, Exhibition Station (EXH) and ADM.

Brief Description of the Project

2.4 The proposed SCL is an extension of the existing Line via East Kowloon and connect to at Hung Hom, and an extension of the existing East Rail Line from Hung Hom to Admiralty crossing . It comprises approximately 17 kilometres of rail line that will connect several existing railway lines, creating two distinct east-west and north-south railway corridors, and provide interchange opportunities, with six of its ten stations (, Diamond Hill, Homantin, Hung Hom, Exhibition and Admiralty). Figure No. NEX2213/C/331/ENS/M50/001 illustrates an overview of the SCL alignment.

2.5 The SCL (HUH-ADM) is an approximately 6km long East Rail Line extension from HUH across the harbour to new EXH and ADM, with provisions to facilitate a possible station at Central in the longer term. This section of SCL alignment will be entirely underground while the associated ventilation building, ventilation shafts, plant rooms and station entrances will form aboveground structures.

Scope of the Project

2.6 The Project comprises the following key elements:

 An approximately 6km extension of the East Rail Line including a rail harbour crossing from Hung Hom to Admiralty on Hong Kong Island;

 A new EXH located near the Hong Kong Convention and Exhibition Centre (HKCEC);

 An integrated ADM for the existing urban lines, the future SCL and (East) (SIL(E));

 Ventilation buildings, ventilation shafts, smoke extraction facilities and other associated works of the Project; and

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 Demolition of the existing Kowloon Freight Building at south of HUH to facilitate the construction of the Project.

2.7 Apart from the above key elements, barging facilities, supporting works areas and access roads will be required to support the construction of the Project.

2.8 It should be noted that the works at the HUH would be within the scope of SCL (MKK-HUH). The design and construction of the ADM including associated structures for the SCL (HUH-ADM) will be carried out by the SIL(E) whilst the construction of the overrun tunnel beyond ADM and minor building works will be carried out under SCL (HUH-ADM).

Benefits of the Project

2.9 The SCL is an important strategic rail corridor purposed for forming an expanded railway network in Hong Kong that will bring various benefits to the community in return:  Providing a fast, reliable and convenient mode of transport running through the northern , Kowloon and Hong Kong Island;  Redistributing railway passenger flows to relieve the existing railway lines in urban Kowloon and on Hong Kong Island;  Improving the coverage of the railway network by placing 70% of the population and 80% of the workforce within one km of a railway station, and also by crossing the Harbour to interchange with the the Tsuen Wan Lin, Island Lin and SIL(E) at ADM;  Stimulating the redevelopment of Hung Hom and Waterfront areas; and  Relieving reliance on road-based transport, resulting in significant reductions in roadside air pollutants, respirable suspended particulates and carbon dioxide, and providing a more environmentally-friendly public transport option in terms of energy conservation.

2.10 The Project provides Hong Kong with the fourth Rail Harbour Crossing which essentially relieves the existing congestion on the through redistributing railway passengers, and connects the new development areas in Kai Tak with Hong Kong Island. It is predicted that if the SCL is not built on time, the Tsuen Wan Line morning peak line flow in 2021 will exceed its desirable capacity, leading to intensified congestion on existing rail lines and causing huge inconvenience to the passengers.

2.11 More importantly, the expansion in railway network can gradually conduce a significant modal shift in passengers’ travel behaviours from road-based transport to railway system, and thereby soothing the burgeoning reliance on cross harbour road tunnels, especially the demand on the Hung Hom Cross Harbour Tunnel, as well as alleviating environmental nuisance from existing road networks.

2.12 From the environmental perspective, the rail will be powered electrically. Rail is widely recognized as a more sustainable form of transport than road transport in terms of carrying capacity and energy effectiveness, adverse environmental implications such as roadside air pollution associated with electrically-powered rail are far less in comparing to vehicle fleets. Having anticipated that the Project will increase public transport patronage and reduce the overall road traffic volumes through providing a more convenient and easily accessible transport option, the Project will bring improvements in air quality, noise pollution, on-road safety and the overall quality of the ambient environment. As the most of the rail line is underground, the visual quality, landscape character and land amenity can also be maintained whilst still providing convenient access to areas by the public.

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Scenario Without the Project

2.13 If the Project is not to be put forth, passengers will be forced to rely on road-based transport between areas along the SCL corridor, and there would be a significant increase in road traffic volumes and hence air and noise pollution as a result of the increased vehicles travelling similar distances. It is expected that the increased congestion would also be negatively impact Hong Kong’s competitive advantage.

2.14 In addition to the pivotal role of the Project in traffic congestion and environmental impacts relief, the Project will also improve accessibility to the harbour by providing a direct link between Hung Hom and Hong Kong Island. With this link, there will be increased opportunities for the public to access this area and enjoy the harbour and the promenade area of East, and thus produce more possibilities for the planning and development of leisure and tourism for this area.

2.15 The construction and operation of the SCL will also create numerous new employment opportunities within Hong Kong SAR. Construction of new stations and redevelopment of current stations will also create commercial opportunities within the stations and enhanced economic development of the areas they serve.

Considerations for Alternatives/Options

2.16 The following sections present the consideration of the alternatives for the following key elements of the Project: (a) Alignment; (b) Stations/platforms; (c) Ventilation buildings/ventilation shifts; (d) Entrances/exits; and (e) Train system.

Alignment

Criteria for Options Development

2.17 To assess the suitability of the alternative alignment options, a range of environmental, engineering, safety and general community disruption considerations were developed to help the decision making process. These considerations are presented in Table 2.1 below. Table 2.1 Considerations in Determining Preferred Alignment and Construction Method Considerations Description

Engineering Factors Minimisation of construction period. Shorter construction period is preferable in Implementation Programme order to minimise the disturbance to the community. The preferred railway alignment connecting the HUH and the new EXH should be a direct connection with minimal distance to reduce construction costs, maintain operational efficiency and minimise passenger travelling time between stations. Specific consideration in relation to HUH and EXH included: Interface with Existing  minimum impact on the operation of the existing stations; and Facilities  ensuring an efficient interchanges between the SCL and SIL(E). Other specific interfacing issues that were taken into account during selection of alignment options including: the need for the SCL crossing under the Hung Hom Bypass piers and the fender piles that have a depth of up to -20mPD; the need to minimise impacts to the existing freight pier and to avoid impacting on the Cross Harbour Tunnel and tension anchors.

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Considerations Description There are also important interfacing issues with the Central Wanchai Bypass (CWB) and Development Phase II (WDII) projects. Protection works to these projects are required to ensure construction works can be carried out more efficiently with fewer disturbances to the environment. The operational impacts to the CBTS including the existing breakwater and existing moorings/anchorages within the Typhoon Shelter are also required to be minimised. A number of safety, flexibility and maintenance requirements in the design and construction of railway lines constrain certain alignment options. Particular constraints identified within this Project included:  horizontal curve radius for a rail track; Construction/Operational  a maximum vertical gradient of 3% should be achieved, with minimum Safety, Flexibility and gradients for long lengths of track to improve energy efficiency; Maintenance Requirements  tunnel ventilation and emergency access points for a tunnel ; and  Factories and Industrial Undertakings Ordinance limits the maximum compressed air pressure at work to protect tunnel personnel from being unnecessarily exposed to unacceptable hazardous conditions to health and safety. Constructability is primarily related to concerns surrounding destabilising structures already present or to be built. Concerns identified in the SCL include:  allowing for practical construction under existing aboveground buildings; Constructability and  avoidance/minimisation of constructing soft ground tunnel due to Implication on Victoria safety and building settlement issues; and Harbour protection  avoidance/minimisation on construction risks due to uncertain ground condition and long tunnel. Reclamations within the boundaries of Victoria Harbour require Cogent and Convincing Materials be provided in order to support and justify the overriding public need and decision for reclamation. This issue is considered in order to minimise area of land that may need to be Land Acquisition acquired so as to minimise disruption to the local community. Environmental Factors Water Quality and The associated water quality and ecological/fishery implications when marine Ecology/Fishery works are required for the cross harbour section are considered. Dust generated during the construction of the SCL and its impact on human Air Quality health and the environment is considered. Ground-borne rail noise impact associated with the train pass-bys, together Noise with noise impact on nearby residents during the construction phase of the SCL are considered. Other environmental factors that are considered include:  the avoidance or minimisation of landscape and visual impacts Other Environmental associated with the above-ground structures; Considerations  preservation of mature trees;  C&D / Waste generation (e.g. contaminated soil/sediment); and  minimisation of fuel usage. Other Factors This includes minimisation of project areas encroaching into developed Avoidance/Minimisation of area, and interface issues with other projects currently being planned or Issues/Constraints constructed. Minimisation of disruption to the community, e.g. residential households, Disruption to the business operations and potential structural impacts along the alignment, Community are considered. 2.18 A preliminary design for the SCL was conducted from 2008 to 2009, in which comprehensive studies have been carried out to investigate various alignment options. The alignment options developed for the Project would need to meet the requirements of the Protection of the Harbour Ordinance (PHO), and the need to prepare Cogent and Convincing Material where reclamation is required to prove such reclamation can satisfy “overriding public need test”.

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Compliance with the Protection of Harbour Ordinance (PHO)

2.19 The PHO Cap 531 recognizes the harbour as a special public asset and a natural heritage of Hong Kong to be protected and preserved. Judicial reviews on other projects have further clarified the legal principles behind the PHO and have established a presumption against reclamation within Victoria Harbour, irrespective if the reclamation is permanent or temporary.

2.20 The presumption against reclamation can only be rebutted by establishing an overriding public need for the reclamation work. Guidance for addressing the public need for reclamation (referred to as “the overriding public need test”) is provided in the Housing, Planning and Lands Bureau Technical Circular No. 1/04 (HPLB TC 1/04). This applies to all reclamations within the boundaries of Victoria Harbour and cogent and convincing materials are required to support and justify the overriding public need for reclamation.

2.21 The HPLB TC No. 1/04 states that a “no reclamation” scenario must be taken as the starting point in considering alternatives and that it is imperative to examine if an overriding public need can be met without reclamation through a reasonable alternative. It further states that all circumstances should be considered in determining whether there is a reasonable alternative to reclamation, including the economic, social and environmental implications, cost and time incurred, and other relevant considerations, including technical feasibility and safety considerations.

2.22 A thorough examination of the SCL needs and constraints, including an exhaustive investigation into the need for reclamation for the SCL (HUH-ADM) construction and of alternative schemes that might do away with reclamation or, at least, minimise reclamation, has been carried out. A “Cogent and Convincing Materials to Demonstrate Compliance with the Overriding Public Need Test” (CCM Report for SCL), which set out the findings of the investigations and the conclusions regarding the need for reclamation and the minimum extent of reclamation has been prepared. The CCM Report can be viewed at the website: http://www.mtr-shatincentrallink.hk/en/construction/work-in-victoria- harbour.html.

2.23 As detailed in the CCM Report, the three tests in rebutting the presumption against the reclamation as set out in the PHO have been satisfied:  In facilitating the construction of the SCL and therefore in meeting the overriding public need for the railway, there is consequently a compelling and present need for the reclamation in the CBTS and adjacent to Hung Hom landfalls. All of the reclamation is essentially temporary and will be removed upon completion of construction, with the seabed reinstated to the original level.  No reasonable alternative to temporary reclamation is found for constructing the SCL (HUH- ADM) (known as SCL Cross Harbour Section in the CCM Report).  The extent of reclamation has been determined to be the minimum required.

Alignment Options

2.24 In general, two broad groups of engineering design have been considered for the Project, namely the “No Reclamation Options” and “Alternative Options Requiring Reclamation” and are described in the sections below. Details of the options are described in the CCM Report.

“No Reclamation” Options

2.25 Three “no-reclamation” options have been investigated as a part of the engineering design of the Project, however each of these options are considered to be either not viable or not a reasonable alternative to reclamation. These options include:  Bridge Option;  Shallow Bored Tunnel Option; and  Deep Tunnel Option.

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Bridge Option 2.26 The Bridge Option would have huge impacts on existing infrastructure and buildings on both sides of the harbour as well as significant visual impact. The problems arise from the need to provide sufficient navigation clearance under the bridge deck and the limiting 3% gradient for the railway. The approach ramps on other side of the harbour would have to be 1km long for every 30m of clearance.

2.27 On the Kowloon side the approach ramps would impact on the East Rail Line, existing roads and other infrastructure. The would need to be demolished and the resulting HUH Station would provide for an unacceptable interchange due to significant level differences between the east-west and north-south corridors.

2.28 On the Hong Kong side the approach ramp would have to extend a significant distance along the north shore on Hong Kong Island, including sections at grade and in trough and would fail to provide acceptable interchange stations at EXH and ADM because of the significant level differences involved. This option is therefore not considered to be viable.

Shallow Bored Tunnel Option 2.29 The Shallow Bored Tunnel Option would have to be constructed by Tunnel Boring Machines (TBM) in view of the anticipated ground conditions along the alignment corridor (Figure 2.1 of Appendix 2.1). The alignment of these options is driven by the need to pass under the CWB tunnels with adequate clearance to avoid damaging the CWB tunnels during SCL tunnel construction and also to maintain adequate cover under the seabed, particularly below a large depression in the seabed near the HUH seawall in order to allow the TBM to operate.

2.30 In order to adopt the Shallow Bored Tunnel Option, sufficient ground cover is required over the TBM to enable ground control and steering so as to meet safety requirements. The absolute minimum ground cover above the tunnel is generally one TBM diameter and preferably two diameters. It is expected that an internal diameter of 9m would be required for a single track SCL tunnel with ventilation duct. The external diameter of the TBM would be about 10.35m. Accordingly, to allow for sufficient ground cover, the tunnel would require an absolute minimum depth below seabed of 10.35m and preferably more than 20m clearance from the top of the tunnel to the seabed.

2.31 Due to these constraints, this option involving twin bored TBM tunnel would require an invert level of approximately -50 mPD, at the lowest point under the CWB tunnel, and a general depth below -44 mPD within the remaining areas of the Harbour. At these levels the tunnel would pass in and out of rockhead several times and significantly increase both the likelihood of corestones being encountered and the general engineering difficulty of the alignment.

2.32 The particularly onerous tunnelling conditions demand the TBM to be capable of operating in mixed face conditions at deep tunnel depths. Based on previous experience, and in view of the expected high cutter wear and risk of damage to the cutterhead, daily interventions would be required at the tunnel face for inspection, maintenance and repair. These works would require workers to enter the pressurised cutterhead via air locks in the pressure bulkhead of the TBM, and would be undertaken in a small and confined space at deep tunnel depths under the harbour at pressures exceeding 50 pounds per square inch (psi) (approximately 3.45 bar) (Figure 2.2 of Appendix 2.1).

2.33 In Hong Kong any works using compressed air is regulated by the Factories and Industrial Undertakings Ordinance (Cap. 59) (F&IUO), which provides for the safety and health protection to workers in the industrial sector. According to the current regulations “no person shall be employed in compressed air at a pressure exceeding 50 psi without permission from the Commissioner, except in the case of an emergency.”

2.34 This limit is in place to protect tunnel personnel from being unnecessarily exposed to more hazardous conditions to health and safety than necessary. In all such cases the objective must be to keep the risk as low as reasonably practicable to these personnel. This, therefore, means that any

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requirement to exceed the current regulated level must be supported by an argument that there is no reasonable, safer way of carrying out the construction.

2.35 The deeper alignment across the harbour would mean that a cross platform interchange could not be provided at EXH resulting in a poorer level of service to passengers.

2.36 This TBM tunnel option also has significant disadvantages for connecting with stations and achieving operation requirements. Due to the tunnel depth requirements for the TBM, the platforms at HUH for the SCL (HUH-ADM) would need to be up to 15m lower than an option using immersed tube tunnel construction with the following implications:  Approximately 2km of the existing East Rail north of HUH would have to be lowered to tie into the deeper platforms at the station.  Impacts on the Hong Kong Coliseum may occur due to increased volumes of rock excavation adjacent to and under it.  Increased construction risks and costs associated with construction adjacent to the existing station foundations and under the Hong Kong Coliseum.  Increased interchange times, as the vertical separation between the east-west and north- south corridor platforms would be increased.

2.37 It is considered that the risks to health, life and the project associated with this Shallow Bored Tunnel Option cannot be justified. There are alternative ways of constructing the project which avoid these risks. It would also cost more, provide a considerably poorer level of service to rail users and has increased impacts on the community which extend over a wider area.

2.38 As such the Shallow Bored Tunnel Option is not considered to be a reasonable alternative to options which require reclamation.

Deep Tunnel Option 2.39 Stations are preferably kept as shallow as possible in order to make them as easily accessible as possible for passengers. This dictates that the tunnels between them generally be kept shallow. However, the problems with the Shallow Bored Tunnel Option listed above dictate that deeper tunnels in rock be considered.

2.40 Previous and currently planned drainage projects have deep tunnels under the harbour which are located in rock. These are aimed at avoiding the need for pressurized face interventions.

2.41 For the SCL (HUH-ADM), this would mean that the tunnels would have to be lowered to approximately 80m below sea level in bedrock. The problems are that the stations would also have to be deepened significantly, i.e. HUH would have to be approximately 50m deep and EXH 43m deep. Cross platform interchange would not be possible at EXH. This option has not been taken forward as it would provide an unacceptable level of service for passengers entering or leaving these stations and an impractical interchange due to the level difference. This does not satisfy the project objectives to provide efficient interchanges.

2.42 There would also be a knock on effect to the alignment to the west of EXH to ADM and also particularly along East Rail Line north of Hung Hom. A significant length of East Rail Line would have to be lowered to suit this new level including East Station. Tunnelling at depths with intervention pressures greater than 50 psi would also be required along this section as the tunnel climbs above rockhead.

2.43 This is therefore not considered to be a viable option.

2.44 To conclude, there is no acceptable “no-reclamation” option for the Project. It must be accepted that some reclamation will be required to enable its construction.

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Alternative Options Requiring Reclamation

2.45 The Immersed Tube Tunnel (IMT) construction method has been adopted for all existing cross- harbour transport tunnels in Hong Kong, including the , and Central Harbour Crossing transport tunnels across Victoria Harbour. The construction process and technology for this method is well established with relatively little risk involved. Both local and overseas contractors have the skills to undertake this type of construction and the construction plant and materials are locally available.

2.46 The standard practice for IMT construction is to dredge a trench in the seabed to remove soft materials, provide a foundation base within the trench, float in precast tube tunnels in sections, sink the precast units into place within the seabed using a floating pontoon system or from a barge and finally connect and backfill the tunnel with a rock blanket or other suitable material to protect and anchor the tunnels. This approach would raise some sections of sea-bed but does not result in any dry surface or land formed. Nonetheless, the raising of the sea-bed level would not affect the use or access to that part of the harbour.

2.47 The maximum depth and portion of IMT extending above the seabed is generally dictated by marine clearance requirements. The top level of a short section of the IMT at the north of the CBTS will be slightly above the Cross Harbour Tunnel but the slightly reduced water depth should have no impact to the marine users and it will not affect the main fairway.

2.48 An envelope covering various alignment options of the Project is shown on Figure 2.4 of Appendix 2.1. This is bounded by the existing Cross Harbour Tunnel on the west and the need to identify a suitable landfall on Hong Kong Island which is not constrained by existing buildings or infrastructure. The IMT must be kept as shallow as possible and, therefore, must pass above the CWB tunnels.

2.49 As the SCL tunnels would clash with CWB Slip Road No. 8, which extends above the main CWB Tunnel Box, alignment options along the central part of the corridor on Hong Kong Island are not feasible. Two alternative alignment corridors are therefore considered, namely an Eastern Corridor and a Western Corridor which both pass through the CBTS.

Eastern and Western Corridor Options

2.50 For both the Eastern and Western Alignment Corridors, the requirements at the Hung Hom landfall are common. At the Hung Hom landfall, the SCL tunnels would need to pass under the Hung Hom Bypass. During construction of the SCL tunnels, some of the fender piles for protecting the Hung Hom Bypass would need to be removed and reprovisioned in a slightly different form. The reprovisioned fender piles are considered to be permanent reclamation but are not considered to affect the use or enjoyment of the Harbour.

Eastern Corridor Options

2.51 The Eastern Corridor options are shown on Figures 2.5 to 2.8 of Appendix 2.1 and the key characteristics are summarised below:

 Option 1A: Alignment runs under CWB tunnels along the same corridor as far as possible.

 Option 1B: Alignment runs partly under the CWB tunnels and then to the south of the tension anchor zone at the Cross Harbour Tunnel and then parallel to and just to the south of the CWB tunnels.

 Option 1C non-stacked: This is a similar alignment to Option 1B through the CBTS but then follows a non-stacked inland alignment to EXH. A similar alignment option to provide a cross platform at EXH was also considered but found to be unfeasible.

 Option 1D: Shallow alignment above the CWB tunnels.

2.52 Options 1A to 1C would require construction of the SCL tunnels beneath the CWB tunnels within the CBTS. These works would have to be carried out under the CWB contract. Due to the extra depth of

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construction and complexity, completion of the CWB tunnels is expected to be delayed for 3 years, which hence prolongs the period of disruption in the CBTS.

2.53 The assessment of Option 1D has shown that the currently proposed CWB tunnels would have to be lowered to avoid the SCL tunnels from either clashing with the CWB Slip Road No. 8 or protruding above the seabed at this location, and in the eastern part of CBTS as shown on Figure 2.8 of Appendix 2.1. The CWB project team has advised that deeper CWB alignment would result in the CWB tunnel portal being moved further east towards . This would increase the permanent reclamation in North Point from 3.3 hectares to approximately 10 hectares.

2.54 All options would require temporary reclamation of up to 2ha while Option 1B would also require additional permanent reclamation to allow the Project to be constructed parallel to the CWB tunnels adjacent to the Wanchai East Screening Plant and Hong Kong Electric Sub-station.

2.55 The Eastern Alignment Options are therefore not favoured because of a combination of the need for permanent reclamation and the prolonged period of construction required in CBTS. In addition, the route length for the alignment within the Eastern Corridor would be extended resulting in greater construction impacts and longer journey times during operation.

Western Corridor Option

2.56 The horizontal alignment of the Western Corridor Option is shown on Figure 2.9 of Appendix 2.1. At the location where the Project crosses the CWB, the SCL tunnels will pass over the CWB tunnels.

2.57 After passing through the Hung Hom landfall section, the alignment will run in a southerly direction towards the CBTS, to the east and generally parallel to the existing Cross Harbour Tunnel. South of the CBTS breakwater, the alignment will then run in a south westerly direction towards the Police Officers’ Club site where a ventilation building will be located.

2.58 The tunnel between the Hung Hom landfall and a point approximately 72m north of the breakwater will be constructed using the IMT method. South of the IMT section, the cut and cover construction method will be adopted. The cut-and-cover section requires temporary reclamation, with a total area of approximately 2.2ha, including the temporary reprovisioned jetty for the Royal Hong Kong Yacht Club.

2.59 The existing breakwater will be removed after the surrounding area has been temporarily reclaimed. The breakwater will be reinstated at the existing location and in a similar form after completion of the SCL tunnels below. The typhoon shelter will be protected at all times by the temporary seawalls and reclamation provided while the existing breakwater is removed for the SCL tunnel construction.

2.60 There are several challenges with constructing the Project through the CBTS section, these include:

 The need to reduce disturbance to the moorings and operations of the typhoon shelter as much as possible and ensure the works are undertaken as quickly as possible to avoid prolongation of any impacts.

 Ensuring the tunnels are placed at a sufficient depth to reduce the potential risk of damage from ship impact, anchors, etc. and are not exposed, whilst minimising the amount of materials to be dredged from within the typhoon shelter during construction, due to the expected high levels of contaminants in the sediment, and ensuring that contaminants are contained as best as possible when removed.

 Interfacing with the CWB project construction at this area which will commence earlier than the SCL.

2.61 The above requirements contribute to the need for temporary reclamation to be undertaken for construction works. In particular, the most significant implication to the Project is the interface requirements with CWB.

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Other Alternative Considerations

2.62 Other alternative alignment options to the west of the Cross Harbour Tunnel and to the east of CBTS were studied but considered not preferable for the reasons given below.

Alternative Alignment to West of Cross Harbour Tunnel

2.63 These options would require the SCL tunnels to pass under the Cross Harbour Tunnel on the Kowloon side of the tunnel and run along Salisbury Road before crossing to the ex-Public Cargo Working Area in Wanchai. The SCL tunnels would pass under the CWB tunnels before entering EXH located adjacent to the CWB tunnels to the north of the Harbour Road Sports Centre.

2.64 There are a number of major challenges with this alignment which renders it unfeasible. These include conflicts with the Hong Kong Coliseum foundations, retaining structures or footings for the East Rail Line tunnels and the adjacent flyover. Mined tunnelling under the existing Cross Harbour Tunnel on Kowloon side would be particularly risky as the existing structure is sensitive to movements.

2.65 The tunnel across the harbour would be particularly deep (approximately 40m below sea level) as it would have to pass below the CWB tunnels. This would lead to excessive dredging and significant areas of temporary reclamation. EXH Station would have to be much deeper and a cross platform interchange could not be provided.

2.66 The risks associated with this alignment, the impacts of construction and less favourable EXH Station interchange mean that this option is unacceptable.

Alternative Alignment to East of CBTS

2.67 This alignment option will shift towards eastern side of Hong Kong Island which terminate at North Point and Stations on the Island Line. However, there are a number of fundamental problems of taking the Project either to or .

2.68 The key destinations for rail users crossing the harbour through SCL would be Central, Admiralty Wanchai and . An alignment to North Point Station or Fortress Hill Station will therefore contradict to the intent of SCL passengers and reduce the quality of service.

2.69 In terms of station capacity, North Point Station is currently providing for interchange between the and the Island Line. The interchange capacity is already stretched as the original platform tunnels have limited width and thus there is limited flexibility to enhance this capacity. Fortress Hill station is configured as two platforms connected by a number of adits which in turn connect to a single principal bank of escalators connecting to the concourse level. The platforms are limited in width.

2.70 Due to the insufficient capacity at these existing stations, neither of them would be able to cope with the large numbers of passengers crossing the harbour, and having to interchange with the Island Line, and total reconstruction of the station would be necessary. The adjacent Island Line tunnels would also have to be realigned causing major disruption to the Island Line services and the community. There would be huge space, cost and programme implications.

2.71 As most people would eventually travel to central business district in the morning peak, a large number of passengers would be trying to board the Island Line. The Island Line would be overloaded by the number of SCL passengers.

Conclusions of Options Reviewed

2.72 A number of “no-reclamation” options have been investigated and are considered to be not viable or not a reasonable alternative to reclamation. These options include: (i) Bridge Option; (ii) Shallow Bored Tunnel Option; and (iii) Deep Tunnel Option.

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2.73 The Bridge Option would cause very significant adverse impacts on both sides of the Harbour. It is not possible to engineer a scheme which meets the SCL project objective. This option is therefore rejected.

2.74 The Deep Tunnel Option is not considered to be viable because of the impractical interchanges created and the need for tunnelling at pressures greater than 50 psi.

2.75 The Shallow Bored Tunnel Option would require working in high pressures exceeding the statutory limit of 50 psi. The MTR Corporation are not prepared to accept the risks to health, life and the project with this option when there is an acceptable alternative option available which avoids these risks. Also, the poor interchange arrangement would not meet the SCL project objective.

2.76 For the “Options Requiring Reclamation”, the Immersed Tube and Cut-and-Cover Tunnel option have been adopted as the approach for the construction of tunnels, thanks to the well established technology and construction process for this method and the relatively little risk involved.

2.77 Based on the analysis of the alignment options for the IMT, it has been concluded that the IMT alignment should follow the Western Corridor Option as it minimises interfaces with CBTS and is the most direct railway alignment. The Eastern Corridor Options have more significant adverse impacts on reclamation durations and greater construction risks.

2.78 Permanent reclamation would not be required under the Western Corridor option by the IMT and cut-and-cover tunnel, as all permanent works would be below seabed or lowest astronomic tide level, other than the reprovisioned fender piles for the Hung Hom Bypass. However, temporary reclamation will be required to construct the cut-and-cover tunnel to connect with the IMT and inside the CBTS.

2.79 In light of the above reasons, it is concluded that there is no reasonable alternative to the IMT tunnel option which requires temporary reclamation for construction at the Hung Hom landfall and adjacent to and in the CBTS and replacement of the fender piles for the Hung Hom Bypass. This option is the most appropriate option that can achieve the Project requirements and benefits to the public and be constructed safely with proven technology, lower costs and less risk to programme.

2.80 A comparison of the key aspects of each alignment is presented in Table 2.2 below.

2.81 Based on feedback from the public consultation process particularly from the Professional Forum and taking into account construction risks and programme, the Western Corridor Option is considered to be a better option than the Eastern Corridor Options.

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Table 2.2 Comparison of Alignment Design Options Construction alignments/ “No Reclamation” Options Alternative Options Requiring Reclamation Aspects Bridge Option Deep Tunnel Shallow Bored IMT Eastern Corridor IMT Western Option Tunnel Option Corridor Option 1A Option 1B Option 1C Option 1D (below CWB) (below (below (above CWB) CWB) CWB) Engineering Factors Implementation - + 2 further years + 2 further years Extended 3 Extended 3 Extended 3 Extended 3 Extended 1.5 Programme as compared to as compared to years of works years of years of years of works years of IMT. IMT. in CBTS & works in works in in CBTS & works in cause delay to CBTS & CBTS & cause delay to CBTS but no CWB cause delay cause delay CWB delay to CWB to CWB to CWB Interface with Existing Major impact - - Prolonged occupation of moorings at CBTS and major interaction Limited Facilities on the East with CWB. mooring Rail Line, affected. existing roads and other infrastructure on Kowloon side. Major resumption of land on Hong Kong Island would be required. The Hong Kong Coliseum would also have to be demolished. Construction/ Operation The approach Use of face interventions at greater Increased Increased construction complexity and risk, Much simpler Safety, Flexibility and ramps on than the maximum 50 psi pressure as construction particularly for the construction of the combined construction Maintainability either sides of currently set in the Factories and complexity CWB and SCL tunnels under the method. Size the harbour Industrial Undertakings Ordinance and risk, Cross Harbour Tunnel. and duration need to be (Cap 59) is not permitted. It is particularly for of temporary 1km long for considered that the Health & Safety the reclamation

AECOM Asia Company Ltd 2-12 Nov 2011 Sec 2_Final Consultancy Agreement No. NEX/2213 EIA Study for Shatin to Central Link - Hung Hom to Admiralty Section MTR Corporation Limited Environmental Impact Assessment Report (Final)

Construction alignments/ “No Reclamation” Options Alternative Options Requiring Reclamation Aspects Bridge Option Deep Tunnel Shallow Bored IMT Eastern Corridor IMT Western Option Tunnel Option Corridor Option 1A Option 1B Option 1C Option 1D (below CWB) (below (below (above CWB) CWB) CWB) every 30m of risks associated with these options construction would be clearance due cannot be justified. under the significantly to the limiting Cross reduced. All 3% gradient Harbour permanent for the railway. Tunnel, works would On the Adverse be below Kowloon side, impact on seabed or this would interchange at lowest impact on East EXH astronomic rail as well as tide level existing roads, and the Hong Kong Coliseum would need to be demolished. High risk High risk High risk Medium risk Low risk Temporary / Permanent Nil Nil Nil 0.6ha 2ha 2ha 0.6ha 2.2ha Reclamation Temporary Temporary Temporary Temporary Temporary Reclamation Reclamation Reclamation Reclamation Reclamation + + + + Required. Permanent Permanent Permanent Permanent + reclamation reclamation reclamation reclamation Permanent required for required for required for required for the Reclamation the the the reprovision of required for reprovision of reprovision reprovision of fender pier piles the fender pier of fender fender pier for Hung Hom reprovision of piles for Hung pier piles for piles for Bypass fender pier Hom Bypass Hung Hom Hung Hom (not considered piles for Hung (not Bypass Bypass to affect the Hom Bypass. considered to (not (not enjoyment of (not affect the considered considered to the Harbour) considered to enjoyment of to affect the affect the + affect the the Harbour) enjoyment enjoyment of additional enjoyment of AECOM Asia Company Ltd 2-13 Nov 2011 Sec 2_Final Consultancy Agreement No. NEX/2213 EIA Study for Shatin to Central Link - Hung Hom to Admiralty Section MTR Corporation Limited Environmental Impact Assessment Report (Final)

Construction alignments/ “No Reclamation” Options Alternative Options Requiring Reclamation Aspects Bridge Option Deep Tunnel Shallow Bored IMT Eastern Corridor IMT Western Option Tunnel Option Corridor Option 1A Option 1B Option 1C Option 1D (below CWB) (below (below (above CWB) CWB) CWB) of the the Harbour) 6.7ha the Harbour) Harbour) Permanent reclamation for CWB. Land Acquisition & Bridge extends 80m below sea Deep Station; Longer Longer Longer Longer tunnels; Min length; Railway Operation a significant level in bedrock; Cross-platform tunnels; tunnels; tunnels; Cross-platform Cross- distance along HUH Station at interchange not Cross- Cross- Cross- interchange at platform the north 50m deep and possible. platform platform platform EXH not interchange shore of Hong EXH at 43m deep interchange at interchange interchange possible. at EXH Kong Island Cross-platform EXH not at EXH not at EXH not possible. and Kowloon. interchange not possible. possible. possible. Cross-platform possible and interchange unacceptable level not engineered of service for practical at the passenger stations. entering or leaving stations. Environmental Factors Environmental  Significant  Much more sediment/C&D will be  Much more sediment/C&D will be generated due to a longer  Localised Considerations visual impact generated due to a longer alignment. alignment. construction  Water and  Construction noise and dust would be a concern at the cut-and- noise and ecology/fish cover section at the landing points. dust impact ery impacts  Water and ecology/fishery impacts would be concerns. at the cut- would be and-cover concerns. section at the landing points.  Water and ecology / fishery impacts would be concerns.

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Construction alignments/ “No Reclamation” Options Alternative Options Requiring Reclamation Aspects Bridge Option Deep Tunnel Shallow Bored IMT Eastern Corridor IMT Western Option Tunnel Option Corridor Option 1A Option 1B Option 1C Option 1D (below CWB) (below (below (above CWB) CWB) CWB) Other Factors Avoidance of Marine traffic Tunnelling for the Project would be a Engineering constraints cannot be resolved. Avoidance of Issues/Constraints would be a major concern on Health & Safety engineering major concern. risks. and environmental constraints has largely been investigated and resolved. Disruption to the Significant Significant traffic Significant traffic Long interfacing/ disruption at CBTS. Limited Community impacts on and other and other interfacing/ existing disruption to the disruption to the disruption at infrastructure north of HUH north of HUH CBTS. and buildings on both sides of the harbour

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Preferred Alignment Option

2.82 As discussed, the IMT along the Western Corridor option is considered as the most appropriate option that can both achieve the objective of the Project and benefit to the public while it will be constructed with proven technology, at lower costs and less risk to the programme. It minimises interfaces with CBTS and is the most direct railway alignment. The Eastern Corridor options have more significant adverse impacts on reclamation duration and much greater construction risks. Other alternative considerations have been deemed to be infeasible.

Stations/Platforms

Exhibition Station (EXH)

2.83 EXH will be an interchange station and is the first station after the harbour crossing section of the Project. EXH passengers can continue to Admiralty. Passengers will also be able to interchange with the Island Line via ADM, which will be extended by the West Island Line and SIL(E) via ADM.

2.84 EXH is expected to handle passengers to and from the north , visitors to the HKCEC and related facilities, and also allows for interchange with the Public Transport Interchange (PTI) located directly above the station bounded by Fleming Road to the west, Convention Avenue to the north, and Tonnochy Road to the east.

2.85 Three location options have been identified for the EXH:

 EXH Option 1 – North of Great Eagle and Harbour Centre

 EXH Option 2 – Harbour Road Alignment Option

 EXH Option 3 – Gloucester Road Alignment Option

EXH Option 1 - North of Great Eagle and Harbour Centre

2.86 The EXH location in this option (as shown in Figure 2.10 of Appendix 2.1) is on the site occupied by the North Wan Chai PTI, Wan Chai Swimming Pool and Harbour Road Sports Centre.

2.87 This EXH is located next to the new WDII/CWB temporary reclamation area to the north, Harbour Road Sports Ground to the east, hotels to the west, and commercial/residential buildings to the south. A fair setback distance can be allowed between station and nearby buildings to minimise any environmental implication due to the construction works. Except the residential building to the south, other buildings are provided with centralised air-conditioning system with fresh air intake at high level which is not sensitive to noise and less sensitive to dust in general. With the provision of good site practices and mitigation measures, the environmental impacts can be kept to an acceptable level.

EXH Option 2 - Harbour Road Alignment Option

2.88 An alternative EXH location at Harbour Road (Figure 2.11 of Appendix 2.1) has been reviewed with an effort to integrate the station with possible redevelopment of the site occupied by Immigration Tower, Wan Chai Tower and Revenue Towers. Based on the engineering data, the station location and alignment is subject to a number of significant constraints and was not considered preferable for the reasons given below:  The unacceptable construction constraints imposed by the alignment across the critical Fleming Road / Harbour Road junction, which are deemed to be virtually unbuildable.  The insufficient width remaining for a station in Harbour Road once allowances have been made for working space.

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 The unfeasibility of constructing a launch chamber for a TBM at the junction of Fenwick Pier Street, Convention Avenue and Harbour Road.  The need for a major 1800mm diameter sewer to be diverted out of Harbour Road.  The unsatisfactory alignment that results in having a station at this location including curves with radii of 250m back to back on the approach to ADM.  The requirement to demolish part of the podium and basement structures of the Great Eagle and Harbour Centres.  The requirement for modifications to the foundations of Pedestrian Plaza.  The lack of available space to undertake support works to Fenwick Pier Street Flyover.  The severe disruption caused to traffic in Harbour Road as cut and cover construction would be required from adjacent to the Hong Kong Academy for Performing Arts (HKAPA) to Wan Chai Sports Ground.  Increased noise and vibration levels on the HKAPA.  Permanent resumption of part of Harbour Road Garden.

2.89 Under this option, the proposed EXH would be surrounded by hotels and commercial buildings on four sides. Owing to the site constraints, the setback distance to the nearby buildings are fairly close or even underneath existing building foundation. Ground-borne construction noise and dust would be key concerns. Extensive controlled measures shall be kept in place to minimise the environmental impacts.

EXH Option 3 - Gloucester Road Alignment Option

2.90 This option is similar to the Harbour Road alignment option except that the station would be located under Gloucester Road (Figure 2.12 of Appendix 2.1). Again connections would be required for the redevelopment of Revenue Tower, Immigration Tower and Wan Chai Tower. This alignment from ADM to Gloucester road results in curves with radii of 200m, which does not represent a feasible alignment given that MTR’s desirable minimum horizontal curve radius is 300m.

2.91 Under this option, the proposed EXH would be located at the middle of the Gloucester Road with a fair setback distance to nearby buildings. It is surrounded by commercial residential buildings to the north, and mainly commercial to the south. Air-borne construction noise and dust would be the key environmental concerns to the surroundings. In addition, the tunnel will pass immediately underneath the HKAPA which ground-borne noise during construction and operation phases would adversely impact on the users of HKAPA, especially during the performance and practicing period.

2.92 The tunnels would also clash with the foundations of the HKAPA and require major cut and cover construction under Gloucester Road. Given the above engineering constraints and environmental considerations, this option was rejected.

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Conclusion to review of Alternative Locations for EXH

2.93 Based on the constraints listed above and the aim to provide a direct connection with minimal distance to reduce construction costs, maintain operational efficiency and to minimise the passenger travelling time between HUH and EXH, it is proposed that the new EXH will be constructed at North of Great Eagle and Harbour Centre (Option 1). In adopting this location the EXH platforms can be connected at strategic positions.

2.94 In terms of environmental issues, a fair setback distance can be allowed for scheme at North of Great Eagle and Harbour Centre to nearby buildings so that environmental implication can be minimised. With the provision of good site practices and mitigation measures, the environmental impacts can be kept to the lowest as compared to other two schemes.

Admiralty Station (ADM)

2.95 The whole SCL will terminate at Admiralty in its southern end for the sake of convenient interchange between Tsuen Wan Line, Island Line and the proposed SIL(E). A modified ADM is proposed as an interchange station under Harcourt Garden and Queensway, not only because of its desirable location to connect the future SIL(E) and SCL with the existing ADM, but also to minimise any adverse effects on the operation of the existing Island Line and Tsuen Wan Line during construction stage.

2.96 The proposed ADM including station structures and protection works for interchange with SCL would be designed and constructed under the SIL(E) project with the aim to minimise disruption in the area especially Harcourt Garden.

Ventilation Buildings/Ventilation Shafts

Ventilation Buildings

Principal Functions

2.97 Ventilation buildings/Ventilation shafts will serve multiple purposes during the operation of the railway. In normal operation, they will be the air exchange route for the railway system; while under emergency circumstances, they will become essential components of the tunnel smoke control system. As no air pollutant emissions would be generated from the electrical trains, the ventilation shafts connecting to the ventilation system of the station would only emit carbon dioxide (CO2) generated from the breathing of the passengers and staff. The ventilation system will be designed for an air exchange rate of 5 litre/person/second in accordance with MTR Design Manual. As a result, all CO2 would be exhaled by normal air exchange. Similar to other electrical rail projects with substantial underground sections (e.g. ), air quality impact from the operations of ventilation shafts would not be a concern.

2.98 In addition, the ventilation building can serve as an Emergency Access Point (EAP) and Emergency Egress Point (EEP). EAPs will be activated in the event of train fire or incident inside tunnel and will serve as the access points for firemen and police to access into the rail tunnels, whereas EEP will be the assembly point for emergency evacuation. Parking areas are provided next to the ventilation buildings for parking of emergency vehicles. A permanent Emergency Vehicle Access (EVA) connecting the existing road networks together with the ventilation building will be used for access by Fire Services Department (FSD) and police vehicles in case of incident inside the rail tunnels. All these provisions are safety measures for protection of the SCL passengers. Design criteria developed for ventilation building are presented in Table 2.3.

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Table 2.3 Design Criteria for Ventilation Building Criteria Description

Functional requirements  Location and orientation within the site of the Tunnel Ventilation Fan (TVF) will be determined by the connection to the tunnels below the TVF shafts.  Allow vehicular access by relevant authorities, such as FSD, police in case of emergency; and MTR for maintenance of the railway related facilities to the building.  Allow access from the building into the rail tunnel underground. Accessibility  Suitable EVA for fire appliances with water supply and street fire hydrant. Access road should also be capable of allowing vehicular access and parking for relevant parties, such as FSD, ambulance, MTR. Constructability  Avoidance/minimization of constructing soft ground tunnel due to safety and building settlement issues.  Avoidance/minimization on construction risks due to uncertain ground condition and long tunnel. Land Acquisition  Minimization of affected areas to avoid disruption to local community.  Avoidance of incompatible land use in urban planning Site Formation Levels  Adequate site formation level to protect the building and rail tunnels underneath from flooding. Environmental  Minimization of visual and landscape impacts on built-up urban environment.  Sufficient setback distance away from sensitive receivers to minimise fixed source noise impact on nearby residential premises. Operational  Functional requirements include ventilation provision for the tunnel, power requirements provision for tunnels, telecom provision and fire service provision.  Adequate size of E&M and building services plantrooms to avoid overheating of mechanical equipment.  Provision of EAP and EEP.  Minimal impact to adjacent buildings during operation of tunnel ventilation system.  Easy maintenance with heavy plantrooms located on G/F.

Selection of Ventilation Buildings Location

2.99 Ventilation facilities are essential components of a railway providing the necessary air exchange for the stations and tunnels. However, heavy development in city areas has made suitable locations for ventilation building increasingly scarce, given that land selection for ventilation building shall avoid incompatible land use and private lands as much as possible to achieve minimum land requirement for ventilation building. Total footprint and height of the ventilation building should also be minimised as far as practicable. The form, finishing and plantation around ventilation building should be optimized to eliminate any landscape and visual impacts. Integrated form of design should be considered wherever feasible.

2.100 Due to the length of the cross harbour tunnel, two ventilation buildings are proposed at the northern and southern end of the harbour crossing tunnel to provide track ventilation. The ventilation building on Hong Kong side will also function as an EAP should accidents occur.

2.101 After determining the preferred alignment of the tunnel sections and locations of the stations, careful consideration has been given to the locations and design of the required ventilation facilities, cooling systems and other fixed plants to ensure that they are situated away from sensitive receivers as far as practicable and sufficient mitigation measures have been incorporated into the design.

Location of South Ventilation Shafts, Plant Rooms and Emergency Access (SOV)

2.102 The location of the SOV has been selected to address the following key issues:

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 In view of the court decisions relating to the PHO, it is considered not justifiable to locate the SOV in reclamation on the south west corner of the CBTS as envisaged in the “MergeCo SCL Project Proposal”. An alternative location for the SOV had to be found.  The SOV serves the cross harbour section of the SCL tunnels. It should be located as close as possible to the point where the tunnels cross the Hong Kong Island shoreline.  The SOV will accommodate a range of facilities including tunnel ventilation, emergency access, traction power and floodgates. The orientation of the floodgates will be perpendicular to the alignment of the SCL tunnels.

2.103 In order to meet the above criteria, the SOV is proposed to be located at the Police Officers’ Club (POC) site in Causeway Bay which is the only suitable option. This building will serve the SCL and the excavation for the underground portion of the SOV will also serve as a launch shaft for TBM tunnel construction towards EXH.

2.104 As the SOV is co-located with the POC on the existing POC site, the POC would be demolished and reinstated back on its present site after the completion of SCL. The design of the SOV should therefore be integrated with the re-provisioned POC.

2.105 Additionally, the proposed SOV will serve as an EAP/EEP area. Owing to the relatively large setback distance with the nearby residential premises, potential environmental concerns such as noise during construction and operational phases could be minimised.

Location of North Ventilation Building, Plant Rooms and Emergency Access (NOV)

2.106 The proposed NOV will be located at the southern end of the HUH, and just north of the existing Kowloon Freight Building. It would house two plants, namely the flood gate and the tunnel ventilation system for the SCL tracks. The flood gate will be capable of shutting off the cross harbour tunnel section in the event of water inundation from within that section or from within the approach tunnels in order to protect the tunnel system and stations beyond. The building is located to the south of the Hung Hom podium and right above the south approach tunnel for ease of connectivity and clear of the existing CLP tunnels.

2.107 Due to the simplicity of the NOV, there is only one proposed scheme which is described above.

Ventilation Shafts

2.108 Ventilation shafts are integral parts of the ventilation facilities providing for air exchange for the railway system. As mentioned earlier, alternative locations for ventilation facilities are subjected to significant site and technical constraints. Land resumption should be avoided yet the ventilation shafts could not be situated too far away from the stations and tunnel alignment, otherwise the efficiency of ventilation would be significantly affected and additional plants and conduits would be required. The footprint of the whole ventilation facility will need to be expanded as a consequence.

2.109 The general concerns for ventilation shafts are the operational noise, height and shape of the shaft and the effect it has on the surrounding areas. The following possibilities can be considered when rationalizing the shape and size of the ventilation shafts:  Direct noise mitigation measures including silencers, acoustic louvers and acoustic enclosure where necessary;  Use upward discharge louvers where possible so that louvers can be located 3 meters above ground level, reducing the overall height of the ventilation shafts;  Use architectural fins instead of louvers so that the required ventilation area can be further reduced;  Use top discharge ventilation shafts for ventilations with horizontal transfers with no direct connection to the plant rooms, hence possible omission of louvers;

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 Re-shape the ventilation shafts in order to maximize the louver area and minimizing the height of the ventilation shafts; and  Omit the louver separation requirement for intake ventilation shafts only.

Ventilation Shafts for EXH

2.110 The ventilation shafts design for EXH has taken into consideration the urban setting and the sensitive receivers surrounding the station. Since the ventilation shafts will be visible from across the harbour, careful consideration and studies have been conducted to achieve a sculptural form and shape that would be both functional and aesthetically pleasing.

2.111 Having considered the above concerns, all the ventilation shafts for the EXH would be located to stand back from the Great Eagle and Harbour Centre. Amongst them, four top discharge ventilation shafts would be sited on the west of Fleming Road and decorated as a landscape garden to minimise visual impact. The plant building with ventilation shafts and emergency access would sit on the east of Fleming Road. There would be another plant building with ventilation shafts placed in the east end of the station next to Tonnochy Road.

Ventilation Shafts for ADM

2.112 Since the new ADM to be designed and constructed under SIL(E) would contain the interchange for SCL as well, the associated structures such as ventilation shafts for SCL would also be provided in the station prior to the commencement of the SCL tunnel construction. These ventilation shafts would be located at the north part of the station adjacent to the Harcourt Road. Furthermore, the ventilation or emergency adits connecting the SCL tunnels would be stacked in the Hong Kong Park Ventilation Shaft which would be constructed under the SIL(E) in advance.

Conclusion to the selection of Ventilation Buildings/Vent Shafts Location

2.113 The site selection for both the NOV and SOV has avoided incompatible land use and minimised the use of private lands. Total footprint and height of the ventilation buildings have also been downsized as far as practicable to prune visual impacts, whereas the form, finishing and plantation around ventilation buildings and ventilation shafts have been optimized to enrich aesthetic pleasing. Figure Nos NEX2213/C/331/ENS/M50/21 and NEX2213/C/331/ENS/M50/23 shows the locations of the NOV and SOV, respectively.

2.114 All the ancillary ventilation shafts of the EXH and ADM would be situated within the station footprints where disturbance to nearby sensitive receivers can be reduced to the greatest extent with the implementation of suitable mitigation measures.

Entrances/Exits

2.115 The new EXH to be constructed under the Project is anticipated to handle a huge amount of passengers both to and from streets and interchanging. Passenger movement modelling has been carried out to test the layout of the station to ensure that localized congestion areas are avoided.

2.116 Since the EXH would be situated within a densely developed urban area, the selection of entrance locations would thus be heavily constrained by the availability of land given that avoiding resumption of private land shall also be prioritized. Two principal entrances are developed accordingly for the station given the site constraints and modelling results of the passenger movement:  Entrance A is located on the south western side of the station box.  Entrance B is located at the eastern end of the station.

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2.117 These two entrances (see Appendix 3.2), both with exits at street level, are also planned for the onward connections to the WDII landscape deck across Convention Avenue at the podium level of the station through an elevated walkway system.

Train System

2.118 Currently, a mixed fleet of MLR and SP1900 trains are running on the East Rail Line. After the completion of SCL (HUH-ADM), 9-car SP1900 or equivalent will be adopted. With the shorter train length, length of platforms and stations can be reduced accordingly. In general, this will reduce the potential environmental impact (in terms of extent and/or duration) that would be generated from the Project during both the construction and operation phases.

2.119 The selection of trackform types will be based on environmental, operational and maintenance considerations. Special trackform will be required as mitigation measure along sections where sensitive receivers of ground-borne noise are present. These areas include the Harbourfront Horizon in Kowloon Side, Hoi King Court, Elizabeth House Block C, Renaissance Harbour View Hotel, Grand Hyatt Hotel, HKAPA and Island Shangri-La Hotel in Hong Kong Island side. Special trackforms including high attenuation baseplate or Floating Slab Track (FST) would be adopted subject to the results of ground-borne noise assessment.

Construction Methodologies

2.120 This section describes the planning of the construction of the project, covering the key aspects including the envisaged methods of tunnel construction, works site requirements and locations, requirements on barging points for handling excavated materials, and the sequence of works.

Construction Method for Land-based Section

2.121 There are several tunnel construction methods that have been undertaken in Hong Kong, with the five main techniques undertaken on land including:  bored tunnelling construction;  cut-and-cover construction;  drill and blast construction;  sequential excavation method; and  mini and Micro-tunnelling

Bored Tunnelling Construction Method

2.122 Tunnel boring machines (TBM) can be utilised for the soft and mixed ground tunnels with adequate ground cover. The construction methodology eliminates the need for surface access except at launching and retrieval shafts thus minimising surface disruption. The machine can be utilised for short rock sections in the tunnels but is not as efficient or flexible as traditional drill and blast techniques.

2.123 The selection of the appropriate tunnelling machine will depend on many issues, including the ground conditions, contractor’s experience, tunnel size and tunnel alignment. Given the ground conditions anticipated, a shielded TBM erecting an un-drained (i.e. sealed) segmental lining would be specified to ensure the stability of the tunnel face, safety of the workers, minimising the impact to the groundwater regime and limit surface settlement.

Cut-and-Cover (C&C) Construction Method

2.124 Cut-and-cover construction is a proven and common method of excavation and construction for stations, ventilation shafts and ventilation buildings. This construction method can accommodate

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different shapes of works areas. It typically requires several overlapping stages of work to be conducted in sequence, including removal of obstruction and diversion of existing utilities, installation of pipe pile wall/diaphragm wall, grouting, installation of decking, soil excavation, construction, backfilling and reinstatement.

2.125 In urban areas, the trench can be covered with a temporary deck following excavation to maintain traffic management, if required.

Drill and Blast Construction Method

2.126 Drill and blast methods are the conventional method of excavation for large face area hard rock tunnels within Hong Kong. It involves using a specialized rock drilling rig to drill holes in the rock which will then be charged with explosives, and detonated.

2.127 The use of explosive for the bulk excavation of hard rock is the most efficient method available in the market. As compared to the cut-and-cover method, drill and blast construction will involve less construction plant items and reduce the duration of overall long term noise from the works, thus reduce impacts on residents living adjacent to the tunnel route, whilst minimising spoil.

2.128 With careful control of the quantity of explosives, the generated vibration levels on existing structures (buildings, roads, utilities etc) can be well controlled. In addition, the duration of a blast is very short (less than 6 seconds) and infrequent (every 12 to 16 hours). With sufficient depth of rock head between the blasting section and the above ground/hill structure, both airborne and ground- borne noise impact induced by blasting would not be a concern as compared to the use of power mechanical plant. Drill and blast is well proven technology for tunnel construction in hard rock.

Sequential Mining Construction

2.129 Sequential Excavation Method, also known as the New Austrian Tunnelling Method (NATM), entails dividing the space to be excavated into segments, then mining the segments sequentially, one portion at a time, using supports. Mining equipment, such as backhoes and roadheaders, are used to excavate the tunnels. This method is slow, but it is especially effective in certain areas, for example, around a subway or a sewer that cannot be relocated where special care is required to protect it.

2.130 Whereas TBMs can excavate only a fixed, generally circular shape, the sequential excavation method allows a tunnel of any shape to be excavated. The method is especially applicable for areas, such as cross-over and bifurcation, in which the tunnel shape or size needs to change.

2.131 To use the sequential excavation method, the ground must be completely dry and it will be generally necessary to dewater the ground prior to excavation. Ground modifications, to strengthen and prepare the soil for tunnelling, are also common with this method. These include various types of grouting (injection of chemical or cementing agent into the soil), ground freezing, and other such treatment. Potential environmental impacts of ground treatment would mainly relate to construction noise impacts arising from the use of powered mechanical equipment such as drill rig, grout pump and grout mixer.

Mini and Micro-tunnelling

2.132 This method is usually adopted in small scale tunnelling works that would not cause major disturbance to any above ground operation. As such, it is usually applied by drainage, sewerage and utility works along or across busy roads, where Temporary Traffic Management (TTM) is very difficult.

2.133 Nonetheless, this construction method is very slow and can only be applicable under small tunnel diameter limited to 2 to 3 metres only. In general, it is usually adopted with soft ground condition. Given that the size of the rail tunnel would be more than 5m in diameter, mini and micro-tunnelling is considered not applicable to the Project.

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Construction Methods for Marine-based Section

Immersed Tube Tunnel

2.134 The construction of tunnels using Immersed Tube Tunnel (IMT) method has been the approach used for all existing cross-harbour transport tunnels in Hong Kong, including the Eastern Harbour Crossing, Western Harbour Crossing, Airport Railway and the Cross Harbour Tunnel across Victoria Harbour. The construction process and technology for this method is well established with relatively little risk involved. Both local and overseas Contractors have the skills to undertake this type of construction and the construction plant and materials are locally available.

2.135 The standard practice for IMT construction is to dredge a trench in the seabed to remove soft materials, provide a foundation base within the trench, float in precast tunnel units, sink the precast units into the trench and backfill the trench with a rock blanket or other suitable material for protection and anchoring the tunnels. Neither permanent nor temporary reclamation would be required in this method.

Deep/Shallow Bored Tunnel by TBM

2.136 As mentioned in the Bored Tunnelling Method by TBM for land-based section, selection of TBM depends largely upon the ground conditions, size and depth of tunnel required. Due to the particularly onerous tunnelling conditions in the harbour area, the type of TBM would generally be limited to either an Earth Pressure Balance or a slurry type shielded TBM, which can be applied to the mixed face conditions that are present along the cross harbour alignment.

2.137 Based on previous experiences, high cutter wearing and damage to cutterhead of the TBM would be expected during the tunnelling works. Daily interventions would thus be required at the tunnel face for inspection, maintenance and repair, which could only be performed manually through entering into the pressurized cutterhead by worker via air locks in the pressure bulkhead of the TBM. The pressure inside this small and confined space at deep tunnel depths is anticipated to exceed the safety threshold of 50 psi as stipulated in the Factories and Industrial Undertakings Ordinance (Cap. 59). Workers working under a pressure exceeding this limit would be exposed to more hazardous conditions to health and safety.

2.138 Both the Deep and Shallow Bored Tunnel approach would bear these similar risks to health, life and the Project. Hence this is an approach that employers, tunnel designers and contractors try to avoid.

Cut-and-Cover Construction Method

2.139 Slightly differing from the land-based approach, the C&C method for harbour section would involve construction of a temporary reclamation area to provide a dry working platform and the installation of temporary walls propped by steel struts. The soil between the temporary walls would then be excavated and a reinforced concrete tunnel box would be constructed to form the permanent structure. Backfilling would then be undertaken on top of the tunnel and the temporary reclamation materials would then be removed.

2.140 The width of temporary reclamation is driven by a few factors, including but not limited to, width of tunnels plus ventilation ducts, working space for construction of tunnels, temporary walls and the need to minimise conflicts between the seawall foundation and temporary wall construction.

Environmental Considerations of Construction Methods

2.141 Potential environmental issues associated with each construction method have been reviewed and a summary of the benefits and dis-benefits of construction methods is presented in Table 2.4.

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Table 2.4 Benefits and Dis-benefits of Construction Methods Construction Benefits Dis-benefits Method Land-Based Section Cut-and-cover  Accommodation of different sizes of  More construction plants will be construction (C & works areas involved working at-grade such C) method  Can undertake both shallow and that this is likely to generate relatively deep tunnelling relatively more noise and dust impacts  Sensitive receivers will be affected over a longer construction period  Require recycling of bentonite for diaphragm wall construction  Larger amount of spoil required to be disposed of. Possibility for spoil reuse, subject to availability of stockpiling space and site conditions Bored tunnelling  All works underground to minimise the  Requires additional land for the construction disturbance to land, wildlife and public handling of slurry that needs method activities at ground level throughout the processing before disposal period of construction  Potential adverse ground-borne  Less spoil to be disposed of, as noise impact when excavating in compared to C&C method rock below existing buildings  Noise impact could be minimised by  Higher engineering difficulties provision of temporary decks over the  Complex interface with existing portal building foundation /structures  Above-ground works only required for construction of retrieval and launching shafts  Comparatively lower vibration impact  Less impact on groundwater level with the installation of water tight concrete tunnel lining in pre-cast segments Drill and blast  All works underground to minimise the  Vibration might be a concern if construction disturbance to land and public activities sensitive receivers located in method at ground level throughout the period of close proximity of the source. It construction; especially when there is a could be mitigated through blast great rock head depth design and careful monitoring  Duration of blasting would be short (less  Provision of site explosives than 6 seconds) and infrequent magazines for storage of  Lesser spoil to be disposed of, as explosives may be required compared with C&C method  Transportation of explosives on  Above-ground works only required for public roads portal construction  Noise impact could be minimised with the provision of temporary doors and barriers at the portals and shafts Sequential Mining  Applicable for cross-over and bifurcation,  Slow Construction in which the tunnel shape or size needs  The ground must be completely to change dry and it will be generally necessary to dewater the ground prior to excavation  Ground modifications, to strengthen and prepare the soil for tunnelling, are also common with this method  Potential environmental impacts of ground treatment would mainly relate to construction noise impacts arising from the use of powered mechanical equipment

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Construction Benefits Dis-benefits Method such as drill rig, grout pump and grout mixer Mini and Micro-  Small scale tunnelling that would not  Slow tunnelling affect any above ground operation  Only applicable to very small  No need to apply TTM; especially for scale utility projects, with tunnel works along/across busy roads diameter usually limited to 2 to 3 metres only  Usually adopted at soft ground  Tunnelling from two ends might be required. If there is any failure in the system, construction of rescue pit might be required at the middle section of the alignment Marine-based Section Immersed Tube  No permanent / temporary reclamation  Larger extent of dredging might Tunnel (IMT) would be required be required to ensure sufficient  Well established techniques and less depth for marine traffic engineering risks compared to Bored Tunnelling Deep/Shallow  No permanent / temporary reclamation  Higher engineering difficulties. Bored Tunnel by would be required  Working in high pressures TBM  Less spoil to be disposed of, as exceeding the statutory limit of compared to IMT and C&C method 50psi would be required  Severe risks to health and safety of workers and project Cut-and-cover  Accommodation of different sizes of  Temporary reclamation would be construction (C & works areas required in the Victoria Harbour C) method  Can undertake both shallow and  Larger amount of spoil required to relatively deep tunnelling be disposed of

Selection of Preferred Construction Methods

2.142 Different approaches would be selected for different sections of the tunnel alignment with respect to the site-specific geological conditions and constraints such as the type of soil, rock and the presence of water, as well as the cost-effectiveness of the tunnelling methods.

2.143 For the land-based tunnel sections, sections at Hung Hom Landfall and the west of EXH along with the new EXH would be constructed by the C&C method. Due to site constraints for instance significant interfacing with other utilities and structures, choices of construction method are largely limited by the corresponding engineering difficulties. In this fashion, C&C method is considered to be the most feasible option that can allow adequate flexibility to accommodate works area of various sizes and tunnelling of different depths. Besides, this conventional method will be suitable for some areas to construct ventilation buildings, ventilation shafts and station boxes. As land-based excavation as well as the associated dewatering works may result in the potential drawdown in soil and aquifer layers, preventive measures, such as installation of groundwater recharge well, use of closed face boring machine with sealed cutter head, etc, would be taken to minimise the drawdown of groundwater during the land-based excavation.

2.144 Starting from south of the IMT section (ie, breakwater of the CBTS) all the way to the SOV cutting across the CBTS, C&C method will be adopted. This section will interface heavily with the CWB project which will commence earlier. In this connection, the two projects would be integrated with the aims to reduce disturbance to the moorings and operations of the CBTS as much as possible and minimise impacts on its users. Use of the temporary reclamation provided by CWB contractor could be optimized such that repeated dredging and temporary reclamation activities could be avoided.

2.145 Bored tunnelling method by TBM would be selected from sections between SOV to EXH and west- end of HKCEC Phase I to ADM. The advantages of excavation by TBM in rock tunnelling include

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relatively higher daily production rates, a more controlled excavation profile and lower vibration and noise generation as compared with drill and blast method. However, the TBM tunnelling would generally involve continuous operation, which would often be the main source of ground-borne construction noise impact. On the other hand, due to limited number of suppliers, shortage of manufacturing capability and overall global demand within the buoyant tunnelling market, procurement of TBM is expected to take 18 months. In comparison, the daily production rate of TBM will be relatively higher than that of blasting but the overall production rate will be lower for short tunnel sections.

2.146 The rock tunnels at the ADM overrun section would be constructed by drill and blasting method. This method is not a continuous operation and in general has lower daily production rates than TBM tunnelling, yet it requires less lead time and is thus more flexible in terms of programme management. Excavation by this method in rock face is better in managing ground risk issues but ventilation adits will be required for supporting the blasting activity.

2.147 For the marine-based tunnel, the cross harbour section between southern boundary of the Hung Hom landfall and a point approximately 70m north of the breakwater of CBTS will be constructed using the IMT method. The reinstated seabed above the IMT would be at a similar but generally lower level than the adjacent Cross Harbour Tunnel to ensure that sufficient water depth for marine traffic is achieved whilst reducing the amount of dredging for installation of the IMT units. Permanent or temporary reclamation could be avoided along this section.

2.148 The construction methods for different sections have therefore been selected, based on engineering, site constraints and environmental considerations. The preferred construction are summarised in Table 2.5 below and illustrated in Figure No. NEX2213/C/331/ENS/M50/011. More detailed descriptions on the construction methods for the alignment from HUH to ADM are presented in Section 3 of this Report.

Table 2.5 Preferred Construction methods Construction Sections Selection Reasons Method Cut-and-Cover  From Hung Hom NOV to Hung  Engineering constraints; in particular Construction Method Hom Landfall interfacing with existing  From the breakwater of CBTS to buildings/structures closed to the SOV alignment  EXH Station to West End of  Interfacing with CWB project in the HKCEC Phase I CBTS where the CWB tunnel would be constructed by C&C method such that environmental impacts and disturbances to the existing facilities, users and sensitive receivers could be minimised  Protection to the moorings in CBTS can be maintained Bored Tunnelling  From SOV to EXH  Geological and engineering Construction Method Station/Wanchai Sports Ground considerations  From West End of HKCEC Phase  Comparatively shorter construction I to ADM Station period  Minimization of works areas so as to minimise potential disturbance to the environment  Minimization of potential environmental impacts to the public such as construction dust, airborne noise, and landscape and visual impacts Drill and Blast  ADM Overrun  Great Rock Head Depth - Geological Construction Method and engineering considerations  Minimisation of works areas  Minimisation of potential environmental impacts to the public such as construction dust, airborne noise, and

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Construction Sections Selection Reasons Method landscape and visual impacts Immersed Tube  From southern boundary of the  Permanent / Temporary reclamation can Tunnel Method Hung Hom Landfall to be avoided approximately 70m north of the  Comparatively well-established method breakwater of the CBTS with less engineering risks  Minimization of potential disturbance to the public

Works Area(s) / Site Requirements and Locations

2.149 Generally, works areas/ sites will be required for the construction and operation of:  Stations and entrances;  Cut-and-Cover tunnel;  IMT tunnel fabrication and mobilisation;  Ventilation buildings and ventilation shafts;  Spoil Disposal Systems;  Tunnel Launch / Reception Shafts;  Reprovisioning works;  Diversion of affected utilities;  Underpinning and removal of the foundations of affected buildings and infrastructure;  Temporary traffic management schemes;  Temporary site accommodation and facilities.

2.150 Since the SCL (HUH - ADM) will pass along the condensed northern shore of Hong Kong Island, the lack of space available at the surface for locating entrances and railway facilities and for working space poses great constraints to the planning, design and construction of the railway. Identification of available works areas/sites hence represents a significant challenge to the Project.

2.151 The proposed location and size of works areas/sites are wherever possible confined to the site of permanent works, and are selected based on their accessibility and suitability for construction works and future permanent structures. The above-ground works areas/sites have been minimised to reduce land take as far as practicable and avoid the potential environmentally sensitive areas, such as green belt, coastal protection area, Shek O Country Park. Sites of ventilation building/vent shaft will be used as works areas/sites during construction phase to minimise the works areas/sites as well as disturbance to the public and surrounding environment.

2.152 To support the construction of the Project, additional temporary works areas/sites would be required for the provision of site office, storage of materials, utility, traffic diversion and barging points for efficient removal of spoil. With a view to minimising road-based traffic and stress on existing road networks, barging points have to be set up at waterfront sites to remove the excavated materials generated from tunnelling and earth works by sea. This will significantly reduce the impact on road traffic in particular the burden on routes in Wan Chai, Causeway Bay as well as in the Kowloon side, and hence the impact on nearby environment.

2.153 Details of the works areas/sites requirements and locations for the Project are presented in Section 3.

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Sequence of works

2.154 It should be understood that the sequence of construction works carried out under this Project is largely defined by the need to meet the constraints of the overall programme as well as engineering requirements. In brief, two approaches are usually adopted for arranging the sequences of works, namely the concurrent construction sequence and phased construction sequence.

2.155 Concurrent construction sequence involves various construction activities occurring at the same time. The environmental benefit of this approach would result in a shorter construction period and hence the duration of impact due to the construction activities. However, the magnitude of the overall environmental impact could be intensified. Whereas the phased construction sequence involves construction activities being carried out one followed by another. This would help reduce the magnitude of the overall impacts, yet at the expense of prolonged construction period.

2.156 As the two approaches have their environmental benefits and drawbacks, a balancing approach with a combination of both will be adopted in different stages of the construction period to alleviate the potential environmental impact and to meet the target commissioning date.

2.157 Amidst the multiple construction activities to be undertaken, the sequence of the tunnelling works in the CBTS are particularly critical, not only to the determination of the overall construction programme, but also to the cumulative environmental impacts on surrounding receivers due to its interfacing with the CWB project in the region.

Sequence of Works at CBTS

2.158 It has been concluded in Section 2.82 above that the IMT along the Western Corridor option, which passes through the CBTS and lands on Hong Kong Island at the SOV, would be the most preferable alignment option for the SCL (HUH – ADM) based on all-round considerations. One of the key aspects under this scheme would be the coordination of interfaces between the SCL tunnel works and the CWB project in the CBTS area.

2.159 In determining the sequence of SCL tunnelling works adjacent to and within the CBTS, due consideration has been taken of views expressed in consultation with the District Councils, the public and affected stakeholders. The principal concerns were:

 The SCL works should be integrated with the CWB works where possible with a view to minimizing the duration of construction.

 Stakeholders do not want to have any more moorings reprovisioned out of the CBTS (i.e. over what CWB has already proposed).

 Adequate separation should be provided between moorings and construction equipment for the required marine works. The level of protection provided by the existing breakwater should be maintained.

2.160 The construction of the SCL tunnels through the CBTS would be carried out in stages, using the same approach to dealing with the moorings as developed under the CWB project. Whilst it is envisaged that the SCL works within the CBTS can be completed within 18 months of completion of the CWB works within the CBTS, the full area of temporary reclamation would not be in place up until that time. Illustrative construction staging plans for the works through the CBTS are shown in Appendix 2.2.

2.161 Key aspects of the staging are:

 The section of SCL tunnels which run above the CWB tunnel and to the south of the CWB tunnel within the CBTS will be constructed under the CWB construction contract.

 Construction of the SCL tunnels immediately to the north of the existing breakwater will commence during Stage 3 of the CWB construction to allow the connection between the immersed tube tunnel and the cut-and cover-tunnel to be completed.

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 Construction of the SCL tunnels through the breakwater and into the northern part of the CBTS would commence once the CWB Stage 3 works are completed. These works will extend as far as possible into the CBTS without affecting CWB construction or requiring additional moorings to be relocated out of CBTS. Earlier commencement of these works is not possible without additional moorings being relocated out of CBTS.

 The final stage of SCL construction would commence once all of the CWB works within the CBTS are completed. These would take a further 18 months to complete.

2.162 The durations of the temporary reclamation staging for SCL works from the time of starting seawall construction and filling above the seabed to the time when the temporary reclamation is removed and the seabed reinstated will vary from 15 months to 28 months, except for a small area near the shoreline (Area SCL 1.4 in Appendix 2.2) which will stay for a longer period.

2.163 Upon completion of each stage, the temporary reclamation would be removed and the seabed reinstated. There would be some overlapping of temporary reclamation between stages. At any one time the maximum area of temporary reclamation for SCL would be around 1.6ha (excluding temporary reclamation for CWB).

2.164 Therefore, whilst the overall area of temporary reclamation required for SCL construction at the CBTS is approximately 2.2ha, the additional affected area of the harbour in respect of temporary reclamation in the CBTS will only be around 1.6ha for approximately 8 months. This would be reduced to approximately 0.8ha for the final 10 months of SCL construction after completion of the CWB.

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