12 Environmental Outcomes

12.1 Introduction

12.1.1 This chapter summarises the overall environmental outcomes due to the relocation of the DHSRs into Caverns. It can be seen from Sections 1 and 2 that environmental considerations have been the key consideration throughout the development of the Project. Alternative options for designs and construction methodologies have been duly considered. All the options considered have ensured that environmental impacts could be avoided or minimised where practicable and mitigated by implementing suitable mitigation measures to fulfil all the statutory requirements. The technical assessments conducted (see Section 3 to Section 10) have demonstrated that all the statutory requirements in EIA Study Brief (No. ESB-317/2019) and Technical Memorandum on Environmental Impact Assessment (EIAO-TM) have been complied with.

12.1.2 The following sections summarise the approaches that have been adopted to either avoid or minimise various environmental impacts throughout the design process, and the associated environmental enhancements.

12.2 Environmentally Friendly Options Considered and Incorporated to Avoid Environmental Impacts

12.2.1 Avoidance of environmental impacts has been one of the key considerations throughout the entire project development and design. The environmental impacts that have been avoided are listed and discussed below:

· Avoidance of the recognised site of conservation importance;

· Avoidance of the encroachment of semi-natural watercourse;

· Avoidance of the encroachment of secondary woodland; and

· Avoidance of direct impacts on species of conservation interest.

Avoidance of the Recognised Site of Conservation Importance

12.2.2 The encroachment of Lion Rock Country Park (LRCP) has been avoided by locating the proposed access portal away from the LRCP boundary and minimizing the above-ground works footprint.

Avoidance of the Encroachment of Semi-natural Watercourse

12.2.3 The preferred cavern option by accommodating the relocated DHSRs and DHPS closer to the access tunnel (i.e. shorten the required length access tunnel). With implementation of design, the emergency exit tunnel/portal as the safe passage where locates adjacent to Fat Jong Temple at Shatin Pass Road is not required. The elimination of emergency exit tunnel/portal could completely avoid the encroachment of watercourse habitat, which its ecological value of the watercourse is rated as low to moderate.

Avoidance of the Encroachment of Secondary Woodland

12.2.4 Due to the elimination of the emergency exit tunnel/portal adjacent to Fat Jong Temple at Shatin Pass Road, there is about 0.082 ha of woodland habitat, which is moderate to high in ecological value, could be retained.

12.2.5 For the access tunnel portal located near Lion Rock Park Transit Nursery, it is found that the rock cover of the initial tunnel section is shallow in depth which leads to drill and break/blast construction method infeasible. Therefore, cut and cover excavation method has been adopted. With the careful construction design, about 40m cut and cover tunnel section will be required to avoid the direct encroachment of secondary woodland near the entrance of Lion Rock Park.

Avoidance of Direct Impacts on Species of Conservation Interest

12.2.6 Floral species of conservation interest, Aquilaria sinensis, Pavetta hongkongensis and Gnetum luofuense were recorded in the vicinity of the proposed tunnel portal adjacent to Lion Rock Park. To avoid the removal and transplantation of these species, refinement has been made to the proposed access tunnel portal and ancillary facilities to locate further away from the concerned tree in the preferred tunnel option.

12.2.7 Due to the elimination of the emergency exit tunnel/portal adjacent to Fat Jong Temple at Shatin Pass Road, direct impact on the herpetofauna species of conservation interest, Lesser Spiny Frog was recorded in the watercourse behind Fat Jong Temple has been avoided.

12.3 Environmental Designs Recommended to Minimise and Mitigate Environmental Impacts

12.3.1 This Project for relocating the DHSRs and DHPS in the cavern and constructing the ancillary facilities and main-laying work achieving the following merits:

· Reinstatement and enhancement of temporarily affected habitats;

· Relocation of tunnel portal;

· Elimination of emergency exit tunnel and alternative of cavern interior design; and

· Elimination of ventilation shaft.

Reinstatement and Enhancement of Temporarily Affected Habitats

12.3.2 Minor ecological impacts may arise from the temporary loss of plantation and developed area during the construction of ancillary buildings, initial access tunnel section and portal, and associated mainlaying works. Replanting around the tunnel portal would be implemented upon the completion of the construction works to reinstate the temporarily affected areas to condition similar to original status.

Relocation of Tunnel Portal

12.3.3 In order to minimise the disturbance to the local residents in the vicinity of proposed access portal, the proposed tunnel portal is relocated adjacent to the Lion Rock Park Transit Nursery. In accordance with the latest layout and design, the improvement of access road to Ma Chai Hang FWSR and the watermains laying works at Chui Chuk Street are not required. Therefore, the potential noise impacts arising from the construction and operation of access road to Ma Chai Hang FWSR and the watermains laying works at Chui Chuk Street to the local residents could be minimised. On the other hand, the construction dust impact arising from the construction of access road and watermains laying works, and indirect disturbance impacts to habitats and associated fauna and flora which arise from construction works could also be minimised.

Elimination of Emergency Exit Tunnel and Alternative of Cavern Interior Design

12.3.4 In order to minimise the excavation volume of granitic rocks for the construction of access tunnel while meeting the requirements for pipes, ventilation, fire engineering and traffic, the current design of the access tunnel has adopted the following approaches in the preferred option,

· to integrate the MOE inside the access tunnel (i.e. emergency exit tunnel can be eliminated);

· to shorten the length of the access tunnel by 250 metre, where the length of tunnel is about 1,000m under original caverns location and about 750m under preferred cavern location;

· to utilise the space of roof arch of access tunnel to accommodate the ventilation ducts in order to minimise the excavation volume of access tunnel; and

· to adopt drained cavern and tunnel lining so as to reduce the thickness of the structural lining.

12.3.5 By adopting the above approaches, it is estimated that the excavation volume of C&D material from the construction of access tunnel will be reduced by about 25%.

Elimination of Ventilation Shaft

12.3.6 Under the original design in Feasibility Study, it was proposed to construct ventilation shaft, which would be about 2m tall above-ground structure and might induce potential ecological and visual impact during construction and operation phases. In the latest design, a ventilation system with inlet/exhaust are locating within and immediate outside of the access tunnel portal has been proposed. With the elimination of the ventilation shaft, the potential ecological and visual impacts can be avoided.

12.4 Summary of Key Environmental Problems Avoided, Protection of Sensitive Areas and Provision of Compensatory Tree Planting

12.4.1 Sections 12.2 and 12.3 summarise the key approaches adopted in the current proposed layout to avoid, minimise and mitigate environmental impacts. Some of these approaches have contributed to avoid a number of environmental issues and to protect a number of environmentally sensitive areas. Table 12.1 presents the key environmental problems that have been avoided and any sensitive areas protected by these approaches.

Table 12.1 Key Environmental Problems Avoided and Sensitive Areas Protected

Designed Approaches	Key Environmental Problems Avoided and Sensitive Areas Protected
Avoidance of works in Country Park	· Adverse impacts on natural resources would be avoided.
Avoidance of the encroachment of semi-natural watercourses, woodland and species of conservation interests	· Adverse impacts on natural resources would be avoided.
Reinstatement and enhancement of temporarily affected habitats	· Adverse impacts on natural resources would be minimised.
Relocation of Tunnel Portal	· Adverse impacts on air quality and noise to the local residents would be minimised and avoided. · Indirect disturbance impacts to habitats and associated fauna and flora which arise from construction works could be minimised.
Elimination of Emergency Exit Tunnel and Alternative of Cavern Interior Design	· Generation of waste during construction phase would be minimised.
Elimination of Ventilation Shaft	· Adverse visual impact would be minimised.

12.4.2 The project is estimated to involve removal of approximately 260-300 no. of trees. The project proponent is committed to compensate for the loss of trees in not less than 1:1 ratio in terms of quantity. Onsite compensation of trees within Project Site is restricted to the area of formed slope beyond the first 20m of tunnel portal. The area is estimated to accommodate around less than 40 no. of trees. Rest of the compensatory trees will be planted around Ma Chai Hang Fresh Water Service Reservoir. Compensatory trees of whip trees or seedlings are recommended for slope planting.

12.5 Estimated Population Protected from Various Environmental Impacts

12.5.1 The Project has been carefully designed to protect the populations from various environmental impacts. The protected populations include the following:

· Existing air and noise sensitive receivers at Tin Ma Court, Tin Wang Court, Tsui Chuk Garden, Chuk Yuen North Estate, Tsz Lok Estate, Chuk Yuen South Estate, Pang Ching Court, schools, hospital and institutional uses in the vicinity of Project Site would be protected from air quality and noise impact assessment by the implementation of good site practices during construction phase of the Project.

12.6 Environmental Benefits of Environmental Protection Measures Recommended

12.6.1 Mitigation measures have been recommended to further reduce the environmental impacts during the construction and operation phases of the project. Key recommended mitigation measures and the associated benefits are summarised in Table 12.2.

Table 12.2 Key Recommended Mitigation Measures and Associated Benefits

EIA Aspects	Key Recommended Mitigation Measures	Associated Benefits
Air Quality	Construction Dust · Dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation. · Implement specific dust mitigation measures for excavation, drilling and blasting activities during the construction of tunnel portal. These include the use of blast nets / canvas covers and ensure portal door is properly closed.	To minimise the dust nuisance on ASRs during construction phase.
Noise Impact	Design Phase · The location and setting of the access portal are taken into account of the design, which is away from the local residents and façade with angle of view facing the main carriageways (Lung Cheung Road). Construction Phase · The NSRs, which are in close proximity of project site, will be protected by limiting the pipe section to be constructed by open cut method in a length of no more than 30 m at any one time. · A majority of the residential NSRs and educational NSRs are protected with implementation of quiet PME, moveable noise barriers & noise enclosure, except occasional exceedance of noise criterion at the following NSRs: o Grace Methodist Church Kindergarten, Our Lady’s College, and St. Bonaventure College and High School, Ho Lap Primary School; and o Our Lady of Maryknoll Hospital, Wu York Yu Health Centre, and Proposed Departmental Quarters for Customs & Excise Department · Those educational NSRs could comply the required noise criteria by carrying out the works during school holidays; and placing the concrete lorry mixer 10m away from Our Lady of Maryknoll Hospital, Wu York Yu Health Centre, and Proposed Departmental Quarters for Customs & Excise Department. Operation Phase · With the fixed plant properly designed to meet the maximum permissible SWLs, no adverse operational noise impact is envisaged.	To minimise the construction noise on NSRs during construction phase. During the operation phase, the fixed noise impact to the nearby NSRs could be protected.
Water Quality	Construction Phase · The key issue from the land-based construction activities would be the potential release of construction site run-off and wastewater from general construction activities, accidental spillage, sewage from on-site construction workers, construction works in close proximity of inland watercourses, cleansing effluent generated from washing of interior of structures and groundwater infiltration. Impacts could be controlled by implementing the site practices as outlined in the ProPECC PN 1/94 “Construction Site Drainage” and the ETWB TC(W) No. 5/2005 “Protection of natural streams/rivers from adverse impacts arising from construction works” and the mitigation measures such as provision of drainage system and sand/silt removal facilities, groundwater control measures, and proper treatment and discharge of cleansing effluent etc. · The Contractor shall apply for a discharge licence to discharge the effluent from the construction site under the WPCO. The discharge quality must meet the requirements specified in the discharge licence. All the runoff and wastewater generated from the works areas should be treated so that it satisfies all the standards listed in the Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters (TM-DSS). Operation Phase · The main operation impact from the Project would come from the treatment and disposal of cleansing water during cleaning and maintenance of the service reservoirs. Impacts could be minimised by following the WSD’s current standard practice and complying with Water Pollution Control Ordinance (WPCO). Best Management Practices (BMPs) including design measures and administration measures are proposed to reduce non-point source surface water pollution. No adverse residual water quality impact is anticipated during the operation of the Project.	To minimise the potential water pollution to the nearby water sensitive receivers (WSRs), thus, the WSRs could be protected in construction and operation phases.
Waste Management Implications	· Implementation of the proposed waste control and mitigation measures would avoid the potential water quality, dust and noise impacts associated with handling, transportation and disposal of the identified wastes arising from the construction phase of the Project. · Implementation of a trip-ticket system promulgated under DEVB TC(W) No. 6/2010 to monitor off-site delivery of surplus inert and non-inert construction and demolition (C&D) materials. · Handling of chemical wastes in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, and disposal of chemical wastes at licensed chemical waste recycling/ treatment facilities. · Employ reputable waste collectors for disposal of general refuse. · A C&DMMP will be prepared and submitted to Public Fill Committee for approval in accordance with Project Administration Handbook for Civil Engineering Works. · EMP shall be submitted to the Architect/Engineer for approval before construction works in accordance with ETWB TC(W) No. 19/2005.	Implementation of good waste management to avoid, reuse and recycle the waste materials as far as practical and fully utilise the waste resources during the construction and operation.
Ecology	· The preferred option could minimise encroachment into adjacent woodland and watercourse habitats, as well as avoid the direct impacts on floral species of conservation interest (Aquilaria sinensis). · Shorten the access tunnel could eliminate the emergency exit portal, which avoid the direct impact of Herpetofauna species of conservation interest, Lesser Spiny Frog, as well as butterfly species of conservation interest, Common Archduke. · Replanting would be implemented upon the completion of the construction works to reinstate the temporarily affected areas to condition similar to original status. · The indirect disturbance impacts to habitat and associated fauna and flora could be minimised by the use of quieter piling machinery and construction plants, hoarding and standard good site practices during construction, as well as screen planting around the portal during operation.	To avoid the disturbance of ecologically sensitive areas, floral and faunal species of conservation interest.
Landscape and Visual Impacts	· Site layout and works area including temporary access road(s), stockpiling area(s), temporary construction storage shall be carefully planned to preserve existing landscape resources and trees as far as practicable. · Existing vegetation shall be retained on site as far as practicable. Trees unavoidably affected by the Project shall be transplanted as far as practicable. Affected trees that are not suitable for transplantation and to be felled shall be compensated in not less than 1:1 in quantity and in accordance with DEVB TC (W) No.4/2020 – Tree Preservation or its latest version. · Landscape planting shall be provided in accordance with DEVB TCW No.3/2012. Planting species shall be compatible with the nearby existing vegetation cover as far as practicable. · Rooftop greening and vertical greening shall be implemented. The orientation and location of the ancillary facilities shall be carefully designed. Its finish shall be non-reflective and dull in colour.	To provide a disguising effect that merge proposed building to surrounding context visually; while the overall greenery coverage shall be increased.
Hazard to Life	· No overnight storage of explosive on site. The delivery of the explosive will be once per day.	To minimise the risk to the sensitive receivers (i.e. residents and wildlife, etc.) nearby during construction phase.

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