14. Summary of Environmental Outcomes

14.1 Overview

14.1.1.1 The details and benefit of the Project together with the consideration of alternatives are presented in Section 2. The technical assessments in Sections 3 to 11 have demonstrated that all the statutory requirements in EIA Study Brief (No. ESB-281/2014) and EIAO-TM have been compiled with.

14.1.1.2 This chapter summarises the key environmental outcomes arising from this EIA study, the approaches that have been adopted to either avoid or minimise various environmental impacts throughout the design process, and the associated environmental mitigation measures.

14.2 Environmental Benefits of the Project

14.2.1.1 At present, the sewage from the existing village houses in unsewered area at Sai Sha is preliminarily treated by private treatment facilities i.e. septic tanks and soakaway systems while the sewage from existing residential developments is treated by local private treatment plants. The proposed Sai O Trunk Sewer SPS, as part of “Public Works Programme Item 4125DS - Tolo Harbour Sewerage of Unsewered Areas, Stage II” that originated from the findings of the Study “Review of North District and Tolo Harbour Sewerage Master Plans” completed by Environmental Protection Department (EPD) in 2002, is a core component of the proposed trunk sewerage system in Ma On Shan along Sai Sha Road. The trunk sewerage system together with the proposed Sai O Trunk Sewer SPS is designed to serve the existing and planned developments in the Sai Sha area, by collecting and conveying the sewage generated from these developments to Shatin Sewage Treatment Works for proper treatment. The proposed trunk sewerage system is generally supported by the local communities. As an essential component for the operation of the proposed trunk sewerage system, the Project plays an important role in improving the environment and hygiene conditions of the area.

14.3 Environmentally Friendly Designs Recommended

14.3.1.1 Environmental aspects considered in the selection of preferred option, design and construction method of the Project are detailed in Section 2. The following environmentally friendly designs have been incorporated to minimise potential environmental impacts associated with the Project as far as practicable:

l Site footprint has been modified and compacted design of SPS has been adopted to allow the SPS to be sited away from the nearby sensitive uses to minimise the potential odour and noise impact arising from the SPS operation.

l Building bulk of the SPS has been reduced by about 16% with the adoption of submersible type pumping station together with the compacted design and thereby minimising the potential visual impact from the new superstructure.

l The proposed height of SPS had been minimized by lowering the ground level to match with the existing carriageway and slope. The height of SPS has also been designed with limited headroom by skipping double slab and allow minimum headroom for lifting operation etc.

l With the whole SPS building being moved to the northern part of the site (next to the northern boundary of the existing Sai O offtake and Pigging Station), the southern part of the site (next to Nin Ming Road) has been preserved for landscape planting to improve the existing landscape quality and provide screen planting to block the view of the SPS from the main road.

l All components of the proposed SPS with potential odour emissions will be located underground, covered and ventilated via deodorising unit to control and minimise odour impact.

l All components of the proposed SPS will be enclosed within reinforced concrete structure and soundproof door and ventilated with silencers installed at the outlet of the ventilation fans and exhaust fan of the deodorising unit or other acoustic treatment equipment at ventilation openings such that fixed noise impact can be kept within the acceptable level.

l The loading / unloading area will also be enclosed within the SPS to confine any potential environmental nuisances from the loading and unloading activities during the SPS operation.

l All components of the proposed SPS will be segregated from the public path with aesthetically designed fence wall, while their access and associated work zones would be maintained behind the fence walls treated with planters and vegetation and hidden from view from main road. Building façades and roof slab would also be treated with planters and vegetation while the surface of the SPS would be covered with timber pattern wall tiles to harmonise with the earthy landscape to echo with the surrounding natural environment.

l Implementation of environmental monitoring and auditing programme to ensure that all the necessary mitigation measures are implemented in a timely and orderly manner.

14.4 Key Environmental Problems Avoided and Compensation Area Included

Avoidance of Encroachment on Recognised Site of Conservation Importance and Natural Habitats with Higher Ecological Values

14.4.1.1 Recognised sites of conservation importance and natural habitats with higher ecological values, including Ma On Shan Country Park (CP), Nai Chung Coast Site of Special Scientific Interest (SSSI), Tseng Tau Coast SSSI, area zoned as “Coastal Protection Area” (“CPA”), mangrove, mudflat and woodland, have been identified and avoided during the planning and site selection process. The selected Project site will not encroach on any recognised sites of conservation importance or natural habitats with higher ecological values.

Avoidance and Minimisation of Emergency Discharges

14.4.1.2 The design layout would adopt measures to ensure the reliability and to avoid and minimise the risk of emergency discharges of Sai O Trunk Sewer SPS. The following design measures would be adopted:

l Provision of reliable power supply.

l Provision of adequate standby pumps.

l Provision of mechanically raked screen with standby unit to protect and secure the normal operation of downstream equipment.

l Provision of twin rising mains system to maintain normal operation of the proposed SPS during maintenance works.

l Regular maintenances and inspections.

l Provision of emergency storage.

l Provision of a remote monitoring system to allow close monitoring of the operation of the SPS.

l Mobilise sewage tankers to tank away the sewage from the SPS as much as possible.

14.4.1.3 As the Project would not cause any loss of habitat of conservation importance, no compensation is recommended.

14.5 Population and Environmentally Sensitive Areas Protected

14.5.1.1 The Project is located at the north of Sai O and within “Government, Institution or Community” (G/IC) zone on the draft Ma On Shan OZP No. S/MOS/23. Population and environmental sensitive areas in the vicinity of the Project site have been protected through the avoidance and / or minimisation of environmental impacts from the construction and operation the Project. Population protected from air quality and noise impacts due to the construction and operation of the Project comprise the nearby Hong Kong Baptist Theological Seminary, Symphony Bay and Zessa Vista as well as the proposed school with recreational area located to the north of the Project site. Environmental sensitive areas protected from adverse water quality impacts include nearby inland watercourses, mangroves along the coastlines of Tolo Harbour and area zoned as “Coastal Protection Area”(“CPA”) at Nai Chung on the Approved Shap Sz Heung Outline Zoning Plan No. S/NE-SSH/11.

14.6 Environmental Protection Measures Recommended

14.6.1.1 Mitigation measures have been recommended to further reduce the potential environmental impacts due to construction and operation of the Project. Key recommended mitigation measures and any associated benefits are summarised in Table 14.1 below.

Table 14.1 Key Recommended Mitigation Measures

Environmental Aspect	Mitigation Measure and any Associated Benefit
Air Quality Impact	· Implementation of relevant control measures as required in the Air Pollution Control (Construction Dust) Regulation to minimise dust generation. · Treatment of air ventilated from the enclosed structure of the proposed SPS by deodorising unit with odour removal efficiency of at least 99.5% in terms of target odour species, i.e. H₂S, before discharging to the atmosphere. · Positioning of the exhaust outlet of the deodorising unit away from the nearby air sensitive receivers as far as practicable, i.e. facing east of the Sai O Trunk Sewer SPS.
Noise Impact	· Adoption of quiet powered mechanical equipment (PME) and movable noise barriers / acoustic mats as well as implementation of good site practices to minimise the construction noise impact. · Liaison with the operator of HKBTS to obtain the examination schedule so as to avoid noisy construction activities during school examination period. · Provision of silencers or other acoustic treatment at the outlet of the ventilation fans and exhaust fan of the deodorizing unit of the proposed Sai O Trunk Sewer SPS to alleviate the fixed plant noise impact.
Water Quality Impact	· Implementation of mitigation measures as detailed in the ProPECCPN 1/94 “Construction Site Drainage” and ETWB TC (Works) No. 5/2005 “Protection of Natural Streams / Rivers from Adverse Impacts arising from Construction Works”, as well as other good site practices to minimise the potential water quality impacts from the construction activities. · Any unlikely incident of emergency bypass shall follow EPD’s “A Guide on Reporting Sewage Bypass Incidents in Sewage Pumping Stations and Sewers” and DSD’s “Contingency Plan for Incidents Possibly Encountered in Sewage Treatment Facilities having a Potential of Generating an Environmental Nuisance” to minimise the associated impacts. · Implementation of Best Management Practices (BMPs), e.g. good housekeeping practices to ensure that the operation of the SPS would not pollute the runoff.
Waste Management Implications	· Implementation of good site practices and waste reduction measures (e.g. reuse of construction and demolition (C&D) materials before off-site disposal) to achieve avoidance and minimisation of waste generation in the waste management hierarchy. · Preparation of an Environmental Management Plan (EMP), which includes the Waste Management Plan (WMP) in accordance with the ETWB TC(W) No. 19/2005 “Environmental Management on Construction Site”. · Implementation of trip-ticket system following DevB TC(W) No. 6/2010 “Trip Ticket System for Disposal of C&D Materials” during construction phase to ensure proper documentation and verification of the disposal of C&D materials. · Proper handling of chemical waste following the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, and disposal of chemical waste at licensed chemical waste recycling / treatment facilities during construction and operational phases. · Proper collection and removal of screenings from the SPS in covered container or sealed plastic bag at regular time intervals by reputable waste collector to minimise odour, pest and litter impacts.
Land Contamination	· Since land contamination issue is not anticipated, no further land contamination assessment or mitigation measure is considered necessary for the Project.
Ecology (Terrestrial and Aquatic)	· Confinement of all construction works and stockpile areas to the Project area to protect adjacent vegetation, natural habitats and fauna. · Implementation of the good site practice and general mitigation measures to minimise construction disturbance such as dust and noise.
Hazard to Life	· Since hazard to life issue is not anticipated from the Project, no mitigation measure is considered necessary.
Landscape and Visual Impact	· CM1 – Preservation of Trees · CM2 – Compensatory tree planting · CM3 – Control of night-time lighting / glare · CM4 – Erection of decorative screen hoarding · CM5 – Careful management of height, deposition and arrangement to construction activities and facilities · CM6 - Reinstatement of temporarily disturbed landscape areas · OM1 - Tree and shrub planting to soften the proposed SPS · OM2 - Aesthetically pleasing design of the SPS · OM3 - Provision of green roof · OM4 - Provision of vertical greening
Cultural Heritage	· Since cultural heritage impact is not anticipated from the Project, no mitigation measure is considered necessary.