3.2 Northern Section in Tuen Mun. 3-2

3.4 Southern Section at HKBCF / North Lantau. 3-7

3.5 Works Areas. 3-9

3.6 Sewage and Drainage. 3-10

3.7 Project Programme. 3-11

3.8 Concurrent Projects. 3-12

3.9 Traffic Data and Assumptions. 3-13

3.10 Environmental Conditions in the Absence of the Project 3-14

3. PROJECT DESCRIPTION

3.1 Scope of the Project

3.1.1.1 Further to the recommendations of the Option Assessment and subsequent alignment developments detailed in Section 2 of this report, the preferred TM-CLKL scheme comprises Northern Connection Option N1, Main Connection Option M3 and Southern Connection Option S1. This preferred alignment is shown in Figure 3.1 and will comprise:

(a) construction of approximately 5.0km long dual 2-lane road tunnel between Tuen Mun Area 40 and the HZMB HKBCF at north-east of HKIA;

(b) construction of approximately 4.2km seawalls and approximately 35.6ha of reclamation to the Government foreshore and sea-bed at Tuen Mun Area 40 and Lantau for the tunnel portals and the associated roads, as shown in Figures 3.2a and 3.2b;

(c) construction of approximately 1.6km long dual 2-lane viaduct between HZMB HKBCF and NLH and the associated roads at Tai Ho;

(d) construction of a toll plaza at Tuen Mun Area 46 and the associated roads at Tuen Mun;

(e) construction of footpaths;

(f) construction of administration building, ventilation buildings and other ancillary buildings to facilitate ventilation and tunnel control operation serving the proposed road tunnel in (a) above and toll plaza in (d) above;

(g) modification and realignment of sections of Lung Fu Road and Lung Mun Road at Tuen Mun;

(h) modification and realignment of sections of North Lantau Highway and Cheung Tung Road at Tai Ho;

(i) permanent closure and demolition of sections of existing at-grade carriageways, footpaths and central median/refuge islands;

(j) temporary closure and reconstruction/modifications of sections of existing at-grade carriageways, footpaths and central median/refuge islands;

(k) reprovisioning of existing government berth and associated facilities at Tuen Mun River Trade Terminal; and

(l) ancillary works including site formation, slope, drainage, utilities, footbridge, noise barriers, retaining walls, berths and temporary pontoon.

3.1.1.2 Details of the various elements of the selected TM-CLKL alignment are detailed in the sections below.

3.2 Northern Section in Tuen Mun

3.2.1 Northern Reclamation

3.2.1.1 At the northern landfall in Tuen Mun, adjacent to the River Trade Terminal at Pillar Point, the construction of TM-CLKL requires a reclamation of about 16.5ha of land area when calculated to the cope line, or 21.1ha for the footprint area to the bottom of the seawall where it intersects the seabed. The general layout and typical sections of the proposed reclamation scheme in this location are shown in Figures 3.3a to 3.3c.

3.2.1.2 Unlike the southern landfall reclamation where sand fill is proposed below +2.5mPD, public fill will be used for the entire reclamation to maximize the use of public fill. Though this may result in worse impact to water quality during construction, in view of its relatively smaller scale in comparison with the HKBCF reclamation, the type of fill material is adopted to achieve an overall balance among environmental, technical and other aspects.

3.2.1.3 The northern landfall reclamation is essentially required to provide a land area for construction of the launching shaft for the tunnel boring machine (TBM) and ultimately, protection to the tunnel structure when constructed.

3.2.1.4 The construction of the portion of reclamation adjacent to the TBM launching shaft, Portion N-c, is critical to the overall programme, as the TBM is planned to be launched from the northern reclamation southward. Therefore, land is required to be formed earlier for the construction and operation of the launching shaft, as well as for the stockpile of tunnel lining segments, a slurry treatment plant to treat the extracted alluvium arising from the tunnel construction so that it would then be suitable as public fill and other operations. Sand Compaction Piles (SCP), in association with a non-dredged seawall foundation, have been considered for the construction in order to minimise the amount of marine sediment to be dredged, as described in Section 2. However, these techniques require a much longer construction time for the seawall which would not be quick enough to allow the land to be formed on time to allow the TBM to commence tunnel construction. Therefore, a fully dredged method is required for the seawall foundation construction. The southern tip of the reclamation will house the TBM tunnel shaft and the deeper portion of the cut-and-cover tunnel section. The marine deposits located above these deep structures would inevitably have been removed during excavation for the construction of these structures. Fully dredged method is therefore also proposed for this section of the reclamation in conjunction with the seawall construction.

3.2.1.5 Notwithstanding, a non-dredged reclamation is proposed for the inner portions of the reclamation denoted by Portions N-a and N-b (Figures 3.3a and 3.3b). In these sections of the alignment, the cut-and-cover tunnel and open ramp will lie above the marine deposits layer and, in order to minimise the sediment removal and disposal quantities, it is proposed that the marine deposits underneath the cut-and-cover tunnel and ramp be left in place, with the tunnel structures supported by deep foundation and diaphragm walls, where necessary. Band drains and sand blankets will be installed and surcharging will be applied to reduce the residual ground settlement associated with the non-dredged reclamation.

3.2.1.6 Construction of the northern reclamation, which partly abuts the existing seawall at Pillar Point, will affect the marine operations of the Government Berths at Tuen Mun River Trade Terminal, including Customs and Excise (C&E) and Immigration (ImmD) Departments and Fire Services Department’s (FSD) Fire Boat Station. Provisions have been made to relocate these facilities to the new reclamation alongside the eastern seawall (see Figure 3.2a).

3.2.2 Viaduct Connection and Slip Roads

3.2.2.1 An elevated viaduct at the northern section of TM-CLKL connects the submarine tunnel as it emerges on the northern landfall to the south of the TMWB alignment at the north. Commencing from the reclamation for the tunnel landfall, the viaduct curves up and over Lung Mun Road, crossing above two sawmill factories and then abuts to the retaining wall structures at the western side of the proposed toll plaza in Area 46, as described in Section 3.2.3 below. Layout of the viaduct is shown in Figure 3.4.

3.2.2.2 The structural form of the viaduct will consist of a pair of pre-stressed concrete box girders supported on reinforced concrete piers. Each box girder commences at around 14.6m wide at the reclamation to accommodate a 2-lane carriageway, before widening out to accommodate additional lanes for connection with the toll plaza. Span lengths will typically be 60m using a constant structural deck depth of 3.2m. In order to cross over Lung Mun Road and the existing fire station, slightly longer spans of around 75m are used with a haunched deck of a depth of around 6m at the piers. The piers supporting the viaducts will sit on bored piles founded on rock at some 20m below ground level, with pile caps below ground level.

3.2.3 Toll Plaza

3.2.3.1 A toll plaza at Tuen Mun Area 46 is proposed for the TM-CLKL, as shown in detail in Figure 3.4. The toll plaza is also considered as a co-location to accommodate the tolling provision for the interface project, TMWB. In order to facilitate the tunnel operator(s) applying different toll levels to TM-CLKL and TMWB road users, the following 3 separate groups of toll booths are proposed to be provided at the toll plaza:

l travelling from/to TM-CLKL only;

l travelling from/to TMWB only; and

l travelling from/to both TM-CLKL and TMWB.

3.2.3.2 The proposed toll plaza is approximately 190m x 680m in size, with tunnel operation facilities located at the northern side of the site. With reference to the latest traffic forecast at year 2031, the required number of tolling lanes for different travelling trips are summarised in Table 3.1 below:

Table 3.1 Proposed Tolling Arrangements at Toll Plaza

Travelling Trip	Northbound		Southbound		Sub-total
Travelling Trip	Auto-toll Lane	Manual-toll Lane	Auto-toll Lane	Manual-toll Lane	Sub-total
TM-CLKL only	2	2	2	2	8
TMWB only	2	2	2	2	8

Both TM-CLKL & TMWB	2	2	2	3	9
Total:					25

3.2.3.3 The nearside toll lane for each direction is proposed to be 6.2m wide, for the passage of exceptionally wide vehicles and special vehicles such as tunnel operator’s vehicles or other authorised vehicles. The other tolling lanes are proposed to be 3.65m wide in order to allow the flexibility of switching between manual-toll and auto-toll if necessary. A 1.6m wide physical island will be provided to accommodate the toll booth, the access staircase landing and the concrete median barriers.

3.2.3.4 The following facilities are required at the toll plaza area or the northern reclamation for tunnel operations:

l an administration building at the northern reclamation (including individual workshops, garage and maintenance buildings);

l a toll control building at the toll plaza;

l weigh stations;

l vehicle recovery areas;

l turnaround facilities;

l vehicle cross-over areas;

l a petrol filling station;

l bus lay-bys with footbridge links; and

l parking spaces for tunnel operators, visitors, recovery, operation and maintenance vehicles.

3.2.3.5 The southwest end of the toll plaza will connect with both northbound and southbound of the TM-CLKL. In order to tie in with the lane configuration of TM-CLKL, both 3-lane and 2-lane carriageways will be provided at the toll plaza for TM-CLKL northbound and southbound traffic respectively. Roads connecting traffic heading to or coming from the TMWB will, also, be provided between the toll plaza and TMWB tunnel portal.

3.2.3.6 A dual single-lane carriageway linking the proposed enlarged roundabout at the junction of Lung Mun Road / Mong Tat Street and the TMWB mainline tunnel will be provided in between the northbound and southbound carriageways of the TM-CLKL.

3.2.3.7 Traffic from the Tuen Mun south road network destined for TM-CLKL will use the approach single carriageway slip road branching from the proposed roundabout at Lung Mun Road and Lung Fu Road. The traffic from TM-CLKL heading to the Tuen Mun south road network will use the exit slip road after leaving the toll booth. The slip road, which takes the form of a single carriageway tunnel, will connect with the proposed roundabout at Lung Mun Road and Lung Fu Road.

3.2.3.8 An internal 7.3m wide 2-way service road providing the turnaround service route around the portal area will also be provided, with a 2.0m wide footpath provided on one side of the road. An ingress/egress is proposed at both bounds of the toll plaza to allow for access of tunnel operation, recovery and emergency vehicles.

3.2.3.9 The toll plaza will be formed as a raised platform above the general existing ground. It will be partly constructed on fill supported by retaining walls, and partly constructed on elevated structures. Cut slopes will also be required, which will mostly be along the northern edge of the toll plaza, with some isolated ones associated with the formation of the various slip roads connecting the toll plaza to the local roads in Tuen Mun. The excavated materials from the cut slopes will be re-used for the filling as part of the earthwork balancing exercise.

3.2.3.10 In order to cope with the proposed layout of the toll plaza, the existing Lung Mun Road will have to be realigned sideway to the south by about 30m to suit. An alternative option of providing a decking support for the portion of the toll plaza overhanging the existing Lung Mun Road has also been considered as viable.

3.2.3.11 The current layout of the toll plaza, on the basis of co-locating the tolling provision for both the TM-CLKL and TMWB, represents the worst cases scenario for the EIA purposes in so far as the scale and extent of works are concerned, as the combined toll plaza requires a larger land take than a single, TM-CLKL only, toll plaza. The option remains, however, to separate the tolling facilities and/or to adopt “non tolling” for TMWB, which could result in a “single” toll plaza of a smaller scale.

3.2.3.12 As described in Sections 1 and 2, the EIA Study Brief (ESB 175/2007), was based upon a toll plaza being located on either the northern or southern landfall reclamation and, therefore, did not interface with the 250m Consultation Zone of the Pillar Point Valley Landfill and, therefore, no specific requirements for a landfill gas hazard assessment were included in the EIA Study Brief. However, as shown in Figure 13.21, the proposed location of the combined toll plaza will encroach upon the 250m consultation zone of the Pillar Point Valley Landfill and, as such, could be affected by the migration of landfill gas. Notwithstanding the scope of the EIA Study Brief, this issue should be assessed as part of the EIA and, therefore, a Landfill Gas Hazard Assessment has been undertaken as part of this Study.

3.2.4 Other Construction Works

3.2.4.1 Site formation and associated slopes and retaining walls will be required to form the toll plaza and associated road carriageways. In general, soil and rock cut slopes would be involved. All slopes will be formed in a stable slope angle with proper maintenance access and drainage surface channels. If necessary, soil nails will be installed to ensure adequate current safety standard. Fill slope formation will unlikely be required according to the current road alignment. The feasible retaining wall structures could be mass concrete, reinforced concrete L-shape or crib walls and reinforced earth for road embankment.

3.3 Submarine Tunnel

3.3.1 Alignment and Construction

3.3.1.1 The preferred horizontal alignment of the proposed submarine tunnel, shown in Figure 3.1, is 5km long and crosses the Urmston Road sea channel, connecting Tuen Mun to the TM-CLKL southern landfall at the HKBCF reclamation, east of the Airport island. As described in Section 2, the tunnel is proposed to be constructed using TBM method in order to avoid disturbance to the seabed and minimise the amount of dredged material to be removed.

3.3.1.2 The tunnel begins at the northern portal situated at the northern landfall where the ground level will be approximately +6.0mPD. The submarine tunnel then runs southward under Urmston Road, where the lowest tunnel bottom level will reach approximately -49mPD, towards the reclamation attached to the east of the proposed HKBCF where it ends at the southern portal. Reclamation works for the TM-CLKL southern landfall will bring the new ground level to around +6mPD. The vertical alignment of the tunnel is shown in Figures 3.5a to 3.5c. As shown in these figures, as the tunnel rises up to the portals, any seabed disturbance will be contained within the reclamation areas at either end of the tunnel and, as such, further seabed loss and disturbance with not occur from the tunnel itself. Construction of the TBM tunnel will commence at the northern landfall reclamation where a land area is required for construction of the launching shaft for the TBM. The TBM will start boring from the launching shaft towards the southern reclamation adjacent to HKBCF where a TBM retrieval shaft will be constructed for the removal of the TBM.

3.3.2 Ventilation Buildings

3.3.2.1 Two ventilation buildings have been proposed at either end of the submarine tunnel to discharge the polluted tunnel air. Location of the north and south ventilation buildings are shown in Figures 3.2a and 3.2b and described below.

3.3.2.2 The North Ventilation Building (NVB) will be located at the southern end of the northern landfall reclamation of the TM-CLKL tunnel, and will be used to extract polluted tunnel air from the northbound tunnel. The cross-sectional area of stack will be about 94m²,and the exit velocity of the emissions will be about 4m/s. The building has three storeys above ground and two levels of basement. The mid-discharge height from the stack is 16.15m above ground, which equates to between 14.15m and 18.15m high. The exhaust direction will be towards the sea and is proposed to be inclined at 45 degree upward.

3.3.2.3 The South Ventilation Building (SVB) will be located at the northern end of the southern landfall reclamation of the TM-CLKL tunnel, adjoining the HKBCF island. The ventilation system will be used to extract the tunnel’s southbound pollution. The cross-sectional area of stack is slightly larger that the NVB at about 102m², but the exit velocity is the same at 4m/s. The mid-discharge height, exhaust direction and inclination will be the same as the NVB.

3.4 Southern Section at HKBCF / North Lantau

3.4.1 Southern Reclamation

3.4.1.1 At the southern landfall, the construction of TM-CLKL requires the reclamation of about 19.1ha of land area when calculated to the cope line, or 25.4ha for the footprint area to the bottom of the seawall where it intersects the seabed. The southern landfall reclamation forms an integrated part of the HKBCF reclamation and interfaces with the latter at a temporary seawall along its eastern edge. Reclamation works sequence and programme have been planned to match those of the HKBCF for both its targeted Phase 1 commissioning at 2015 and ultimate commissioning at 2016. Consideration of options for the construction sequence of the reclamation works for HKBCF and their effect on this EIA study is discussed in Section 3.7. The general layout and typical sections of the proposed scheme of reclamation are shown in Figures 3.6a to 3.6c.

3.4.1.2 Public fill and sand fill are used above and below +2.5mPD (approx. sea level) respectively with the following consideration:

a) to control residual settlement to less than 500mm as stated in Port Works Design Manual (Part 3, P.45) published by CEDD;

b) to be consistent with the adjacent HKBCF reclamation, as the southern landfall reclamation is likely to be constructed together with the former under a single contract;

c) environmentally, use of public fill below +2.5mPD will adversely affect the water quality.

3.4.1.3 Notwithstanding, a maximum proportion of up to 30% of public fill will be used for reclamation below +2.5mPD in line with the current policy on earthwork balancing.

3.4.1.4 The use of SCP for the seawall foundations have been explored (see Section 2) but, again, has been deemed not to be applicable, in this case because of excessive upheaval of the existing seabed induced by SCP installation. The existing seabed at the location of the southern landfall is at approximately -4mPD to -11mPD and thickness of marine deposits is about 14m. The seabed would be expected to rise up by about 4m after installation of the SCP, and such heaving would adversely affect the operation of the barges for construction of the seawall. In addition, the “heaved” material would require to be dredged away to allow marine access during the operational phase, and this will increase the disposal quantities of marine sediment and cause more disturbance. Based upon this, the fully dredged method has also been proposed for the seawall foundation construction at the southern landfall.

3.4.1.5 Similar to the northern landfall, the southern landfall is an elongated shape and can be subdivided into three portions from north to south, namely portions S-a, S-b and S-c, as shown in Figure 3.6a, and accommodating the TBM tunnel and shaft, cut-and-cover tunnel and the open ramp as well as the connecting above ground road system, respectively. In order to minimise the quantities of marine sediment removal and, therefore, disposal, construction methods which minimise the dredging for the reclamation have been considered where possible. At Portion S-a and part of Portion S-b where deep excavation will be required for constructing the TBM shaft and the deeper section of the cut-and-cover tunnel, which would inevitably have removed the marine deposits located above the proposed structures, the fully dredged method is required in conjunction with the seawall construction for the same reasons detailed for the northern landfall above. However, for the remaining portions where marine deposits are expected to be located underneath the cut-and-cover tunnel and ramp, in line with the principle of minimising the sediment disposal quantities, it is proposed that the marine deposits shall be left in place, with the tunnel structures supported by deep foundation and diaphragm wall, where necessary. Similar to the northern reclamation, band drains and sand blankets will also be installed, and the surcharge will, again, be applied to reduce the residual ground settlement associated with the non-dredged reclamation.

3.4.2 Viaduct Connection and Slip Roads

Marine Viaduct

3.4.2.1 The marine viaduct comprises a dual 2-lane carriageway with a straight alignment connecting the TM-CLKL southern landfall to North Lantau, connecting at Tai Ho Wan, as shown in Figure 3.7. The structural form will consist of a pair of prestressed concrete box girders supported on reinforced concrete piers. Each box girder will be around 14.6m wide. The vertical profile will involve rising gradients from both ends of the viaduct to a high point above the navigation channel.

3.4.2.2 Span lengths will typically be 60m using a constant structural deck depth of 3.2m. At the navigation channel off the south-east corner of the southern landfall, a 160m span with a haunched deck will be used to achieve the minimum navigation clearance of 100m horizontally and a minimum of +26.25mPD vertically. The haunched segment at pier will be about 11m deep. The spans adjacent to the navigation span will be 100m long to provide a transition to the typical 60m spans. In total about 50 piers will be constructed in the marine environment, with a predicted loss of seabed of about 0.2ha. The piers supporting the viaduct will sit on bored piles founded on rock at some 40m below seabed level. Pile caps will be positioned above the high water level for marine safety.

Land Connections and Slip Roads

3.4.2.3 There are four slip roads connecting the marine viaduct to the North Lantau Highway (NLH) for eastbound and westbound traffic on the highway connecting to and from the marine crossing. The slip roads comprise four viaducts curving out from the marine viaduct and crossing over the MTR Airport Express Railway before ramping down to connect with the North Lantau Highway. The two viaducts on the west provide for a 1-lane carriageway and the two viaducts on the east provide for 2-lane carriageways.

3.4.2.4 The viaducts are all prestressed concrete box girders supported on reinforced concrete piers. The viaducts for a 1-lane carriageway will each be around 11.3m wide, and the viaducts for the 2-lane carriageways, around 14.6m wide. Span lengths will typically be 60m using a constant structural deck depth of 3.2m, while for crossings over the MTR Airport Express Railway and the North Lantau Highway, larger spans of 90m are required, together with a haunched deck of a depth of around 6m at piers.

3.4.2.5 The piers supporting the viaducts will all be constructed within the disturbed area of the NLH transport corridor, and sit on bored piles founded on rock at some 20m below ground level, or deeper if underground cavities are encountered (as the site falls within the Designated Area of Northshore Lantau with regards to foundation works). In order to accommodate the viaduct connections to the North Lantau Highway, diversion of Cheung Tung Road including some of the existing utilities below this road will be required, with associated slope cutting works at the west.

3.4.3 Slope Works

3.4.3.1 Diversion of the existing Cheung Tung Road will require cutting back the road side slope features 9SE-B/C8 and 9SE-B/C9. The features comprise soil and rock cut slopes, and a similar cut slope profile to the existing would be proposed. If necessary, soil nails will be installed to ensure adequate current safety standard. Some streams pass through the existing slopes works in the form of U shaped channels, and these existing channels will need to be extended up hill to accommodate the new slope extent and profile.

3.5 Works Areas

3.5.1.1 Six works areas have been identified for use during the construction period of TM-CLKL, and will be used for locating site offices and for storage of materials and viaduct segments, etc. The locations of the works areas are shown in Figures 3.8a and 3.8b and described in Table 3.2 below.

Table 3.2 Details of TM-CLKL Proposed Works Areas

Works Area	Location	Proposed Use
Lantau
WA4	At the existing reclaimed land near Tai Ho Offtake and Pigging Station at Cheung Tung Road in Lantau	Works area for storage of materials and viaduct segment and site office
WA5	At the existing site offices for Yam O Road Watermains near Yam O Wan at Cheung Tung Road in Lantau	Works area for storage of materials and viaduct segment and site office
WA6	At the existing site offices and storage yard for Penny’s bay Reclamation near Yam O Wan at Cheung Tung Road in Lantau	Works area for storage of materials and viaduct segment and site office
WA23	At the existing reclaimed land at Wok Tai Wan in Tsing Yi	Casting yard for fabrication of precast units, storage of work boats, materials and site office
Tuen Mun
WA18	At the existing River Trade Golf at Pillar Point in Tuen Mun	Works area for storage of materials and viaduct segment and site office
WA19	At the existing closed Pillar Point Valley Landfill at Pillar Point in Tuen Mun	Works area for storage of materials and viaduct segment and site office

3.5.1.2 All the works areas are currently formed on developed land, with some already being used as works areas for on-going construction projects. The exception to this is WA19 which is within the Pillar Point landfill area, and the site as a whole is largely covered with vegetation with only a relatively small portion formed and utilised. However, the terms for use of this site during the TM-CLKL construction requires that no trees will be removed and therefore, only the already formed areas will be utilised. In addition, all the sites are located away from any residential areas.

3.6 Sewage and Drainage

3.6.1.1 Stormwater drainage systems will be provided to collect stormwater from the carriageway surfaces. The stormwater will enter into gullies along the kerb lines. The gullies will be fitted with sumps to trap silt and grit prior to discharging the stormwater into the stormwater drainage systems. The drainage systems will eventually discharge the stormwater into the sea at discrete locations. Similar systems will be provided along the marine viaduct. Sump traps will be built into the deck structure, and the collected stormwater will discharge into the sea at the column locations.

3.6.1.2 Operational sewage will be generated but, again, in relatively small quantities as summarised in Table 3.3 below, based upon the staffing estimates required for the TM-CLKL project.

Table 3.3 Estimated Sewage Generation

Location	Staff	Average Dry Weather Flow (m³/day)
Southern Landfall	10	3.5 m³/day
Northern Landfall	400	140 m³/day
Toll Plaza	110	38.5 m³/day

3.6.1.3 In Tuen Mun, the sewage (Average Dry Weather Flow (ADWF)) from the toll plaza and northern ventilation building is estimated to be about 178m³ per day and with about 510 personnel on site in total. The sewage will be discharged to the existing sewerage system and it is expected that adequate capacity in the local system to accommodate this amount is available

3.6.1.4 For the southern landfall ventilation building, the estimated sewage generation is very small at 3.5m³ per day (ADWF). As the quantity is so small, the sewage will be collected and pumped to the on-site HKBCF sewage treatment works located in the south-east corner of the HKBCF reclamation. The sewage treatment works will have a daily capacity of 1300m³ and an estimated throughput from the HKBCF of 700m³/day ADWF As such, it has been confirmed that there is adequate spare capacity for the limited amount of sewage generated by the TM-CLKL to be treated at this plant. The HKBCF sewage treatment plant will treat the sewage to a secondary level before discharge via a box culvert into the marine environment.

3.7 Project Programme

3.7.1.1 It is anticipated that construction for the TM-CLKL will commence in late 2011, with a target opening date for the entire road link at the end of 2016. However, the part of the southern reclamation may be carried out in conjunction with the reclamation for HKBCF which will commence earlier and in 2010. An indicative construction programme showing the key activities in different major construction areas is shown in Figures 3.9a and 3.9b. Locations of the construction areas referenced in the construction programme are shown in Figures 3.9c and 3.9d. This is based upon working 12 hours per day for all land works and 16 hours per day for the marine works, although piling works for the marine sheet piled wall will, also, be restricted to 12 hours per day.

3.7.1.2 Notwithstanding the above, critical slip road links of the southern viaduct section are planned to be completed at end 2015, in advance of the overall project completion date, in order to match the targeted Phase 1 commissioning of the HKBCF in 2015. The southern viaduct will serve as an alternative route to connect the HKBCF via North Lantau Highway to urban areas and the rest of the New Territories when the HKBCF is opened at that time.

3.7.1.3 The following activity sequences are critical to the determination of the overall construction programme:

(a) the southern most portion (Portion N-c) of the northern reclamation must be formed first to allow for the TBM tunnel launching pit to be built and subsequently tunnel boring to commence southward from that end;

(b) viaduct connection and slip roads of the Northern Section are planned to commence in early 2014 after the completion of the northern reclamation; and

(c) construction of the southern landfall reclamation will commence in late 2011 as now shown in the programme in Figure 3.9a and 3.9b (but as mentioned in Section 3.7.1.1, the reclamation may be advanced to be carried out in conjunction with the reclamation for the HKBCF in 2010) and be scheduled for completion in early 2014, to match the reclamation programme of the HKBCF for targeted Phase 1 commissioning in 2015.

3.7.1.4 Notwithstanding the targeted Phase 1 commissioning of HKBCF in 2015 described in Section 3.7.1.2 above, two options, referred to as Sequence A and Sequence B, have been formulated for the construction sequence of the reclamation works for HKBCF. Sequence A, adopting a series of interim/temporary seawalls and the full-dredging around local programme critical areas, will enable Phase 1 to be completed by 2014. Sequence B involves no interim seawalls and adopts the non-dredge method for reclamation together with more extensive surcharging. The corresponding target commissioning date for Phase 1 will be 2015. From environmental considerations, Sequence A involves more dredging and more reclamation filling, and will result in larger water quality impacts. Sequence B, in comparison, involves less dredging and reclamation filling, and will result in less water quality impacts.

3.7.1.5 In view of the above, Sequence B should have been adopted, as it is environmentally more advantageous and as it can still meet the vital programming target for HKBCF. Nevertheless, for such a complicated project as HKBCF, there may be a possibility to change to Sequence A, for example in the case of unforeseen delays in the earlier tasks, the change from Sequence B to Sequence A will enable the project to gain back time to compensate for any programme delays. On this basis, although the planning of HKBCF will be based on Sequence B, the assessment of water quality impacts (and, therefore, the associated marine ecology and fisheries assessments), together with the generation of traffic figures for the air and noise assessments, in this EIA study have been based on Sequence A, which is on the conservative side as explained above.

3.8 Concurrent Projects

3.8.1 Interface with HKBCF and HZMB HKLR

3.8.1.1 The southern landfall reclamation of the TM-CLKL forms an integrated part of the HKBCF reclamation and interfaces with the latter at a temporary seawall along its eastern edge. Reclamation works sequencing and programme have been planned to match those of the HKBCF in order to achieve its Phase 1 commissioning date target in 2015. HKLR is also scheduled to open in 2015 in matching the Phase 1 commissioning date of HKBCF. Detailed coordination of the interfacing construction activities will be required, including construction access, layout of mitigation measures to control water quality during the construction stage, joint water quality monitoring system, and engineering and construction details at the interface. The layout of the TM-CLKL, HKBCF and HKLR in relation to each other is shown in Figure 3.1.

3.8.1.2 As the projects are proposed to be constructed concurrently and will be operational at the same time, cumulative impacts are possible and have been assessed.

3.8.2 Interface with Tuen Mun Western By-pass

3.8.2.1 The construction of the TMWB is tentatively planned to commence in late 2011 and be completed by late 2016. The TMWB southern tunnel and its portal will abut with the toll plaza and will interface with the TM-CLKL (see Figure 3.4). Interface of construction activities, including construction access, temporary stockpile area within the toll plaza site for processing, sorting, stockpiling of excavated material from the TMWB tunnel, and any blasting impacts from the drill and blast tunnelling method of the TMWB southern tunnel, will require detailed coordination during the construction phase. As the projects are proposed to be constructed concurrently and will be operational at the same time, cumulative impacts are possible and have been assessed.

3.8.3 Other Concurrent Projects

3.8.3.1 In addition to the interface with the major concurrent projects described above, details of other concurrent projects during either the construction and/or the operational phases, together with details of how these are assessed in the EIA, are described in the summary table of concurrent projects included as Appendix A2.

3.9 Traffic Data and Assumptions

3.9.1.1 A Local Area Model was developed to provide traffic forecasts for EIA purposes. The EIA requires cumulative traffic forecasts and, hence, EIA flows were produced assuming the HZMB, HKLR, HKBCF, TMWB and TM-CLKL were all in place. In order to achieve consistency, a consistent set of model input assumptions have been adopted for the interfacing studies of TM-CLKL, HKBCF, HKLR and TMWB.

3.9.1.2 The TMWB was assumed to be “non tolled” for the purposes of the TM-CLKL EIA forecasts. This would make a marginal difference to the predicted TM-CLKL traffic forecasts, increasing the traffic flows slightly and, therefore, would represent a potentially worst case for assessing the environmental impacts. The traffic flows have been divided into the 16 vehicle classes required to determine the emissions of the traffic.

3.9.1.3 The opening year for the whole TM-CLKL, i.e. both northern and southern sections, is 2016. Design year peak hour traffic forecasts have, therefore, been prepared for the years 2016, 2021 and 2031 which reflect the full operation of the TM-CLKL. In addition, to assess the environmental impacts at the interim year of 2015, when the southern section will be opened to form part of the new road network servicing the HKBCF Phase 1 commissioning, the relevant traffic forecasts for this year should have also been prepared. However, owing to the late formulation of the Sequence B option after the commencement of air and noise assessments, the later were based on the 2014 forecast year, which had been prepared. Nevertheless, the difference in traffic forecast between 2014 and 2015 has been reviewed and considered as insignificant to the assessments, or on the conservative side as explained in Section 3.7.1.5. A summary of the traffic data for the prevailing year of 2007 and the future years of 2014, 2016, 2021 and 2031 and the road links included in the EIA are presented in Appendix A3.

3.9.1.4 The relevant traffic forecasts for EIA purposes have been presented in Technical Notes No. TN2 and TN3, and submitted to Transport Department for review. Letters from Transport Department confirming no adverse comments are also included in Appendix A3.

3.10 Environmental Conditions in the Absence of the Project

3.10.1.1 The TM-CLKL project will be located largely in the north-western waters, an area already subject to large scale development and disturbance. The proposed alignment will also make landing in developed areas, namely the Pillar Point area in Tuen Mun, next to the River Trade Terminal and other industrial and commercial land uses, and in the North Lantau transport corridor at Tai Ho Wan. Overall, the proposed alignment is some distance from residential developments and will, therefore, cause minimal disturbance to the local community.

3.10.1.2 Notwithstanding, in respect of the ecology of the area, pockets of habitats on the land have ecology value, particularly at Tai Ho, although these would not be directly affected. From a marine ecology perspective, the proposed Project will be constructed in waters, which are known to be a habitat for the important Chinese White Dolphins, fisheries and also contain other key species including corals, horseshoe crabs, mangroves and seagrasses. This is an area already subject to considerable disturbance because of other development projects and existing uses. The area is not known to give rise to notable benthos of significant abundance and diversity.

3.10.1.3 Reducing the potential for impacts and maintaining the existing environmental conditions as far a possible has been a major objective of the assessment and in the selection of the preferred TM-CLKL alignment. The selected alignment has minimised the scale of seabed loss and disturbance resulting from reclamation and dredging activities through combining the southern landfall with the BCF to reduce the area of reclamation needed, moving the southern landfall reclamation from the Tai Mo To area, a key habitat for corals, horseshoe crabs and the Chinese White Dolphins, and adopting tunnel boring machine (TBM) and non-dredged methods for the tunnel and reclamations respectively. In addition, as TBM is not possible for the southern connection from the southern landfall Lantau, a viaduct, as opposed to the immersed tube tunnel, has been selected to, also, minimise seabed disturbance and loss.

3.10.1.4 While seabed loss, and the associated habitat loss for benthos and corals and other sub-tidal species, will occur as a result of the project, the construction of 4.2km of sloping seawall will go some way to compensating for this and a series of mitigation measures have been recommended to ameliorate any impacts predicted. However, there will be some loss of fishing grounds and dolphin habitat loss which will be permanent.

3.10.1.5 The primary function of Tuen Mun – Chek Lap Kok Link (TM-CLKL) is to form a new strategic corridor between NWNT and Lantau in order to relieve anticipated future congestion on the Lantau Link. It provides the most direct routing from Shenzhen Bay Port (SBP) and Tuen Mun River Trade Terminal (TMRTT) in the north to the Hong Kong International Airport (Airport) and Hong Kong-Zhuhai-Macao Bridge (HZMB) in the south.

3.10.1.6 Should the TM-CLKL project not be implemented, traffic between NWNT and Lantau will travel via the existing Tuen Mun Road (TMR) – Ting Kau Bridge (TKB) – Lantau Link (LL) – North Lantau Highway (NLH) corridor. With the introduction of HZMB and the proposed Lantau Logistics Park, traffic on NLH and LL, as well as TMR, are all forecast to operate above capacity after 2016.

3.10.1.7 Apart from relieving the traffic congestion on NLH and LL, the TM-CLKL will also provide an alternative access to the Airport and future Hong Kong Boundary Crossing Facilities (HKBCF). Without TM-CLKL, traffic from the Airport north developments and HKBCF will route via the Airport Island to NLH leading to significant increase in internal Airport traffic circulation. While there will be no adverse effects to the marine environment, the environmental consequences of not implementing the TM-CLKL would potentially increase traffic pollution at sensitive receivers adjacent to roads that would be expected to be more utilised and congested. This is particularly an issue for roads which are bordered by residential developments along it length.