2.1.1. This Section provides information on the need for the proposed Project and describes scenarios with and without the proposed Project. Several options and alternatives were considered in terms of engineering feasibility, site conditions, programme, environmental considerations, design and construction methodologies for refinement and selection of the preferred option of the proposed Project.
2.1.2. This Section is prepared in accordance with clause 3.3 of the EIA Study Brief.
2.2.3. The proposed Project will also resolve the shortage of laboratory accommodation faced by the GL and long-term need for permanent depot facility of the EMSD and centralised store for the HKPF’s case property.
2.2.4. The proposed Project aims to accommodate these facilities. The specific functions and needs for each of the future operators of the proposed Project are summarised below.
HKPF PVP&EC
2.2.5. The HKPF PVP&EC at the Quarry Bay temporary site currently handles around 1,500 vehicles per year. As this is the only PVP&EC on Hong Kong Island at present, re-provisioning is necessary upon the development of the extension of Quarry Bay Park Phase II. The size of the new PVP&EC will be similar to the existing one in Quarry Bay.
2.2.6. The re-provisioning of the HKPF PVP&EC in the proposed Project will enable the HKPF to continue with its examination and detention services on vehicles involving in accidents/traffic offences/crime cases on Hong Kong Island. It is one of the Core Policy Objectives to enhance road safety by reducing traffic accidents and maintaining a smooth and safe traffic flow in Hong Kong. No vehicle maintenance works will be carried out in the new PVP&EC.
HKPF Centralised Case Property Store
2.2.7. The establishment of a Centralised Case Property Store for the HKPF in the proposed Project will enable the HKPF to enhance the investigative capabilities of its Crime Wing headquarters units through a more efficient deployment of manpower in retrieval and deposit of case property from the current scattered locations to a single secured location.
2.2.8. A permanent and centralised case property store can also ensure case property items to be held for protracted periods of time and enhance operational efficiency by saving travelling time of officers handling case property.
FEHD Depot
2.2.9. One of the objectives of the FEHD is to maintain a clean and hygienic living environment for Hong Kong citizens. The FEHD Depot is essentially required for ensuring the provision of quality environmental hygiene services and facilities to safeguard public health. Adequate provision of parking spaces and operational facilities plays an important role in providing effective hygiene services to the public.
2.2.10. There is a genuine operational need for keeping the vehicle depot under the FEHD in Hong Kong East as these vehicles have to serve North Point, Quarry Bay, Shau Kei Wan and Chai Wan. Thus, the permanent depot is required to be located at a suitable site in Hong Kong East to minimise travelling distance within the district.
EMSD Depot
2.2.11. The proposed Project enables the provision of the Hong Kong Vehicle Depot in Hong Kong Island Region for essential and emergency vehicle repair and maintenance services to meet its service requirement on the Hong Kong Island.
2.2.12. Although the Lands Department approved in 2009 a Temporary Government Land Allocation at Sheung On Street, Chai Wan for relocating the EMSD Depot which is pending the accommodation of a permanent vehicle depot. A permanent site is more desirable to ensure prompt emergency support to clients.
GL Specialist Laboratory
2.2.13. In view of a number of requests for enhanced and extended scope of scientific services from other Government departments including the Customs and Excise Department, the Department of Health and the FEHD etc., approval has been given to the GL for creation of a number of new posts and procurement of scientific equipment in the past few Resources Allocation Exercises (RAEs). Additional accommodation was requested for installation of the procured equipment and service provision by the GL.
2.2.14. Currently, all the laboratory areas in the GL is fully utilised and suitable laboratory space is very limited despite continuous efforts in site searching in recent years. In addition, the annual expenditure for renting laboratory space from purpose-built laboratory premises is recorded to be substantial, the current proposal is regarded as the best long-term measure that settles the shortage of laboratory space faced by the GL and allows saving in rent.
2.3.1. A fundamental alternative of the proposed Project is the option not to construct the new vehicle depot-cum-office building in Chai Wan, which is referred to as the “do-nothing” option in environmental terms. As spelt out in Section 2.2 above, the site is earmarked for the development of the extension of Quarry Bay Park Phase II whilst services provided by the HKPF, FEHD and EMSD on Hong Kong Island is crucial to the public.
2.3.2. In the absence of the proposed Project, the services for the said region would have to depend upon other depot(s) in the other districts, which in turn demands longer travelling distance and time. It would lead to other environmental impacts including increase in traffic volume, and hence noise and vehicular emissions.
2.3.3. The absence of the proposed Project will also affect the future extension of Quarry Bay Park Phase II, as mentioned in Section 2.2.2 and sustain the shortage problem of GL laboratory, EMSD permanent depot facility and HKPF’s case property centralised store.
2.3.4. Taking the above reasons into account, the “do-nothing” option is not preferred and not considered to be an environmentally-preferred solution to cope with the current demand for vehicle repair / testing services from EMSD and operational services from the HKPF, FEHD, EMSD and GL in the region.
2.3.5. As discussed in Section 2.2 above, there is an urgent need for a vehicle depot-cum-office building on the Hong Kong Island, especially in the Eastern District. In the early planning stage of the proposed Project, two potential sites in the Chai Wan area were identified and shortlisted for evaluation. The locations of the two sites are indicated in Figure 2.1, which include:
· Site A: the Project site, which is a land piece located at the junction of Sheung Tat Street, Sheung On Street and Sheung Mau Street
· Site B: a nearby land piece which is located at the junction of Sheung Tat Street and Chong Fu Road
2.3.6. Site A is located farther away from nearby residential developments while being sandwiched by the existing New World First Bus Chong Fu Road Permanent Depot (hereinafter referred to as NWFB Depot) to the north and Citybus Chai Wan Bus Depot (hereinafter referred to as Citybus Depot) to the south. The adjacent industrial developments allow less flexibility to building type of future development at the site. Industrial development is therefore considered as one of the most appropriate development types at the aforementioned land piece.
2.3.7. Besides, locating the proposed Project at Site A can also shorten the travelling distance and time to access the major carriageway, the Island Eastern Corridor (IEC). Such arrangement is anticipated to ease the ingress/ egress traffic and also introduce less vehicular emission and noise nuisance to nearby sensitive receivers.
2.3.8. Site B, on the other hand, is located less than 20m from the Heng Fa Chuen Playground and 120m from Knight Court and Heng Fa Chuen Block (Block 50). It is considered as a less favourable site for the proposed Project due to its close proximity to the nearby sensitive receivers and thus would have greater potential of air quality, noise, visual and hazard to life impacts towards nearby residents and users of recreational facilities.
2.3.9. Overall, Site A is deemed to be a more environmentally-favourable option than Site B with a view to the type of adjacent land use, distance to major carriageway and separation from nearby sensitive developments. Site A is eventually selected as the Project site of the proposed Project.
(Selected location of the Project site)
2.3.10. The following design options were considered and reviewed in order to optimise the operational and environmental benefits of the facilities:
2.3.11. The proposed Project aims to re-provide the existing Government facilities, including offices, stores, workshop etc. in Chai Wan. The form and scale of proposed Project was reviewed to examine whether a vehicle depot-cum-office building or discrete facilities at different locations would be a preferred options.
2.3.12. The vehicle depot-cum-office building option enables various Government departments serving the Hong Kong Island to perform their duties in one single building relieving the pressure on land resources, reducing the quantity of building construction materials, giving rise to a more efficient transportation planning, and minimising the overall impacts on landscape resources and visual amenity by the avoidance of establishing multiple buildings or at multiple locations, etc.
2.3.13. The building footprint has been optimised to fit the intended use as described in Section 2.2 by all future operators. Floor-to-floor heights, and consequently the overall building height, of the building are minimised to reduce potential visual impact and at the same time provide sufficient space for vehicle maintenance works and parking of various types of vehicles in the building.
2.3.14. The use of underground basement floor has been considered. However, it would involve longer construction period and generate extensive amount of excavated materials and potential marine sediment. In order to reduce overall environmental impact, this option is not adopted.
Facilities Layout
2.3.15. Layout design was investigated in order to strike a balance between operational need and environmental considerations. Vehicle repair / testing activities that can have potential environmental implication will be fully covered and surrounded by spaces with uses that are relatively non-sensitive to noise impact, e.g. storerooms and staircases, for noise screening / buffering as far as possible.
2.3.16. Moreover, for the sake of enhancing the visual quality of the proposed Project, substantial greenery features were considered, including soft landscaping areas on Level 1 and roof, together with the use of non-reflective materials for building envelope.
Ventilation and Local Exhaust Design
2.3.17. The proposed Project will be fully covered, except the landscape area on Level 1 and the roof floor, with a vast amount of openings at the building façades to optimise the use of natural ventilation, supplemented with the mechanical ventilation system at the car parking areas. Due to the reduced number of mechanical ventilation system to be needed, potential nuisance, particularly the noise from the fixed plant systems, could be minimised.
2.3.18. In addition, for those activities with potential environmental nuisance including vehicle repair / testing activities, controlled mechanical ventilation with sufficient forced air changes is desired, rather than merely rely on natural ventilation. Ventilation exhaust at laboratories of GL is to be treated prior to discharge to the atmosphere. Location and orientation of the local exhaust were carefully examined to ensure sufficient dispersion and to avoid direct impact to the nearby sensitive receivers. Various gas treatments were evaluated and the most appropriate technologies with proven removal efficiency (e.g. activated carbon filter, chemical scrubber, etc.) will be applied when considered necessary, and subjected to detailed design.
2.3.19. For the construction of the proposed Project, the major construction activities comprise the following:
· Site formation, excavation and filling;
· Foundation; and
· Main building construction.
2.3.20. The following factors have to be taken into account for the consideration of different feasible construction methods and sequence of works:
· Severity and duration of the construction impacts on nearby environmental sensitive receivers;
· Satisfaction to the design and functional requirements of the proposed Project, such as loading requirement and the space requirement for the proposed Project facilities;
· Site constraints, such as limited working space, potential impacts to adjacent facilities and ground profile.
· Coordination with concurrent interfacing projects and the future developments within and/or adjacent to the area.
2.3.21. There is no off-site work as part of the proposed Project.
Foundation Works
2.3.22. Foundation works are required for the construction of the proposed Project. The selection of foundation schemes are based on the following criteria:
· Type of structure to be supported;
· Load carrying capacity required;
· Availability of materials and plants;
· Local experience;
· Site constraints; and
· Construction schedule.
2.3.23. The piling options that were considered include:
· Option A – bored piles; and
· Option B – conventional steel H-piles.
2.3.24. Both of the technologies for bored piling and conventional steel-H piling are commonly found in Hong Kong. The advantages and disadvantages of these two piling methods are summarized in Table 2.1 below.
Table 2.1 Advantages and Disadvantages of Bored Piling and Conventional Steel-H Piling
|
|
Bored Piles |
Conventional Steel-H Piles |
|
Mechanism |
Non-percussive piling
method that replace existing
soil via drilling |
Percussive piling method
that displace soils laterally |
|
Applicability |
Suitable for medium to
high rise building due to its high pile capacity |
Suitable for low rise
building due to higher flexibility in the pile arrangement, enabling higher
load/ capacity |
|
Construction Period |
Relatively long in comparison
to other pile types (especially in rock) |
Shorter construction time
to minimize prolong adverse environmental impacts, e.g. fugitive dust, noise,
site effluent, visual, C&D waste, |
|
Noise Nuisance |
Less vibration and noise nuisance |
More perceptible impact
noise resultant from metal striking |
|
Waste Generation |
Pile borehole diameter is normally large in size; Prior excavation is normally required and hence
substantial excavation materials would be generated |
Minimal waste is
generated and fewer plants (e.g. sedimentation tank; grouting machines) are
required |
|
Visual Impact |
Greater visual disturbance due to the need of more plants and the
substantial amount of stockpiles of excavated materials |
Visual disturbance is relatively
less |
2.3.25. Although less noise and vibration would be generated from bored piling during construction, it usually requires longer construction period and more extensive excavation. In view of avoiding and minimising prolonged adverse environmental impact, conventional steel H-piling is considered to be more suitable for the proposed Project.
Site formation, excavation and filling
2.3.26. The construction methods to be adopted for site formation are all conventional methods which include site clearance, excavation and backfilling of topsoil, construction of haul road and utilities laying and finally the landscape works. For these works, the methods are well established and there are limited alternatives.
Main building construction
2.3.27. Main building construction will likely to take the form of one of the following:
· Conventional in-situ reinforced concrete construction;
· Precast concrete construction; or
· Steelwork construction much of which will be in the form of prefabricated steelwork elements.
2.3.28. In general, the aforementioned superstructure construction options will not present significant differences in terms of the environmental impacts to the nearby sensitive receivers. Specific construction method will be determined upon the development of the structural form of the building during later design phase.
2.3.29. With due considerations of alternatives, a preferred option has been selected for the proposed Project and as summarised below, based on which the detailed design phase will be proceeded and this EIA study was carried out:
· Optimum site selection;
· Optimum design for form, building design, facilities layout, ventilation and local exhaust design; and
· Optimum construction method
2.3.30. This preferred option by using conventional steel-H piling is determined upon the comparison of the feasibility in line with the environmental benefits and dis-benefits of the various options and alternatives. It was also selected on the principal of minimising the environmental impacts and optimising overall environmental benefits and acceptability over the other options.