CONTENTS

12. SUMMARY OF ENVIRONMENTAL OUTCOMES 12-2

12.1 Introduction 12-2

12.2 Environmental Benefits of the Project 12-2

12.3 Environmental Friendly Options Considered 12-3

12.4 Environmental Friendly Design Recommended 12-4

12.5 Estimated Population and Environmentally Sensitive Areas Protected 12-5

12.6 Key Environmental Problems Avoided and Compensation
Areas Included 12-6

12.7 Environmental Benefits of Environmental Protection Measures Recommended 12-7

12. SUMMARY OF ENVIRONMENTAL OUTCOMES

12.1 Introduction

12.1.1 This Section summarises the key environmental outcomes arising from the EIA Study in accordance with clause 3.6.1 of the EIA Study Brief (ESB-307-2018). The EIA (covering air quality, noise, water quality, waste management, land contamination, ecology, fisheries, cultural heritage and landscape & visual) has concluded that no unacceptable environmental impacts are envisaged due to the construction and operation of the Project with the implementation of the recommended mitigation measures. No long-term unacceptable impact on the environment is anticipated.

12.1.2 Chapter 2 of this EIA have presented the alternative options considered relating to the design, construction and operation of the Project.

12.2 Environmental Benefits of the Project

12.2.1 The implementation of YLBS embodies a comprehensive solution in providing adequate drainage performance & flood resilience to Yuen Long.

12.2.2 The tidal barrier, in conjunction with an integrated, proposed 300mm x 300mm ecological trench will be operated in accordance with the real-time tidal level and the observed water quality in Deep Bay. This is to maintain ecological connectivity and prevent sea water back flow to Yuen Long Town Centre to resolve the long-standing odour issues. After the construction of barrage, the tidal barrier and pumps will operate cohesively to replace the existing inflatable dam, whereby the existing inflatable dam will be decommissioned and removed.

12.2.3 Upon implementation of the YLBS, the existing inflatable dam at the Kau Hui Low Flow Pumping Station in YLN would no longer be necessary and would be decommissioned to achieve energy efficiency.

12.2.4 With reference to the 2019 Policy Address, the Chief Executive has proposed to develop and take forward the concept of ¡§Rivers in the City¡¨, emphasising the aim enhance public enjoyment of river facilities, experience the multiple values of water bodies, treasure water bodies and create a better living environment.

12.2.5 The increased flood protection provided by YLBS would facilitate the concept of ¡§Rivers in the City¡¨ via nullah revitalisation and aesthetic enhancement works. Subsequently retaining the ecological connectivity between Deep Bay and the YLN under non-critical operations.

12.2.6 The Project could also effectively mitigate the odour nuisance present at the downstream of YLN, fulfils the latest SDM standards and optimises the flood protection extent.

12.2.7 Vegetation & landscape components would be introduced to enhance the nullah¡¦s biodiversity and social connectivity for the revitalisation works within YLN.

12.2.8 In addition to proposed green roofs and vertical greening, the use of solar panels will be explored and adopted as far as possible. The applicability and extent of solar energy on the building façade or roof areas of the pumping stations and E&M control room will be evaluated during the detailed design stage.

12.3 Environmental Friendly Options Considered

Avoid Directly Impacting Important Habitats and Ecologically Sensitive Areas

12.3.1 YLN drains into Shan Pui River and ultimately into Inner Deep Bay where the Wetland Conservation Area, SSSI, and the Mai Po Inner Deep Bay Ramsar Site can be found. The nearby fishponds, mangroves, marshes, inter-tidal mudflats in Nam Sang Wai, Inner Deep Bay are also important habitats for a variety of waterbirds including overwintering birds. The proposed barrage has avoided direct impact to these habitats by locating all the facilities in disturbed site near Yuen Long Industrial Estate. The barrage will be located within the concrete lined section of YLN avoiding direct impact to the semi-natural Shan Pui River and Old Kam Tin River.

Avoid Noisy Construction Works during Winter Migratory Period of Waterbirds

12.3.2 Majority of Yuen Long including the proposed barrage site is located in Scheduled Area No. 2 which is defined as an area where the presence of marble containing cavities is possible at depth. Extensive foundation works including piling works will be required to ensure stability of the barrage structure. To minimize the potential noise disturbance, percussive piling works will be scheduled to avoid the overwintering periods of waterbirds. Further noise mitigation measures including use of quiet PME, noise barriers and good site practices will also be implemented. Alternative quiet foundation methods such as socketed H-piles will be explored in the Detailed Design Stage.

Avoidance / Minimization of Construction Disturbance on Ardeid Night Roost

12.3.3 Ardeid night roost was recorded at a site along Kam Tin River. To avoid / minimise the disturbance to the ardeid night roost, no construction works should be undertaken within 100m from any night roost confirmed by the pre-construction survey after 17:00 from February to September and 16:30 from October to January.

12.4 Environmental Friendly Design Recommended

12.4.1 All the construction works and new facilities will be located within the existing concrete-lined YLN and disturbed land to avoid encroaching into the semi-natural Shan Pui River.

12.4.2 The Project will provide the opportunity to incorporate sustainable design and green features in the barrage facilities such as energy efficient pumps, photovoltaic systems, SuDS, green roof and vertical greening, etc.

12.4.3 The height of the pumping stations and tidal barrier has been optimised taken into consideration waterbirds flight path and building heights in the adjacent area.

12.4.4 During non-critical weather condition, the operation of the barrage will be optimised to allow opening of tidal barriers for ecological connectivity. In addition, the details of a 300mm x 300mm ecological trench will be explored in the detailed design stage to allow free passage of water and aquatic organisms, even when the tidal barriers are closed.

12.4.5 Low flow pump will be included in the design to optimise energy usage when minimal pumping is required. Fish friendly pumps will be adopted as far as possible.

12.4.6 All the pumps will be enclosed within reinforced concrete buildings and ventilated with acoustic louvers to keep fixed noise within acceptable level.

12.4.7 After implementation of YLBS, the hydraulic performance of YLN is enhanced. This facilitates the proposed revitalisation works under the Project along the existing concrete-lined YLN, which aims to promote water-friendliness, ecological enhancements, biodiversity and beautification. At nullah sections that are technically feasible (e.g. geotechnical, hydraulics, etc.), scope of revitalisation works may include: removal of sections of concrete nullah, provision of natural substrates and planting and provision of designated viewing points.

12.4.8 A holistic approach will be adopted to achieve the synergy in the planning of beautification works and ecological enhancement measures, as well as developing a water-friendly culture in the YLN area. The overall design will be further developed from on-going stakeholder engagement, co-creation workshops and detailed design.

12.4.9 As part of the nullah revitalisation, measures will be explored to retain the habitat between the existing inflatable dam and the proposed tidal barrier as far as practicable. Apart from periodic opening of the tidal barriers and provision of ecological trench as mentioned above, the proposed nullah deepening works for the pump intakes can also be deepened at a gradient to further enhance ecological connectivity. This would facilitate an exchange of water, similar to the existing tidal fluctuations.

12.4.10 With consideration of the gradual deepening, the water level to be maintained upstream of the YLBS is approximately +1.0mPD with a water depth range of between 0m to 2m. To cater for potential loss of watercourse habitat, the design could allow tidal water to flush 50m further upstream of the current inflatable dam. This will create a watercourse habitat area similar to existing conditions and be further enhanced by the revitalisation works.

12.4.11 The barrage will not increase the discharge flow rate as compare with existing condition. Practicable designs such as energy dissipator or orientation of the pump outlets will be considered to minimize sediment erosion to downstream Shan Pui River and Old Kam Tin River.

12.4.12 Offsite precast structures / modular integrated construction will be considered for the barrage structure as far as practicable to minimize environmental nuisance to nearby sensitive receivers during construction.

12.4.13 The Project will aim to obtain BEAM Plus Gold or higher accreditation, as far as practicable for the existing and new buildings/structures.

12.4.14 The Project will aim to minimize the generation of and maximize the reuse of surplus inert construction and demolition (C&D) materials, as far as practicable.

12.4.15 The proposed revitalisation works under this Project can potentially be integrated with the revitalisation at other upstream channels, e.g. revitalisation of another section of YLN under CEDD's Yuen Long South Development.

12.4.16 Through the proposed revitalisation works to be constructed under this Project, the Project will promote water-friendly culture by the provision of additional amenities, e.g. lookout platform, seating, etc. and blue-green infrastructural elements along the revitalised YLN.

12.4.17 Based on the concept of ¡§Sponge City¡¨ and for the benefit of the revitalised YLN, the feasibility of utilising flow from the Wong Nai Tun Irrigation Reservoir and treated discharge from YLSEPP, as a form of an ecological flow, will be explored.

12.5 Estimated Population and Environmentally Sensitive Areas Protected

12.5.1 Built in the 1960s, YLN is concrete-lined and largely void of vegetation. Upon completion of the barrage, there exist opportunity to revitalise the nullah by removing some of the concrete channel bed and replacing with natural substrates, and planting of vegetation. The public living, working and travelling near YLN will experience a visually improved environment. The ecology of the YLN will also improve compared with existing condition.

12.5.2 During construction, mitigation measures as recommended in the EIA will be implemented to protect the identified sensitive receivers in the vicinity of the Project (i.e. Yuen Long town centre, downstream of Long Ping West Rail Station and Kam Tin River) from air quality and noise impacts.

12.5.3 The downstream ecological sensitive areas including Mai Po Inner Deep Bay Ramsar Site, Wetland Conservation Area, mudflats / mangrove at Kam Tin River and Shan Pui River, etc. will be protected from water quality impact during construction with the provision of mitigation measures, such as use of cofferdams, good site practices, provision of drainage systems and treatment of wastewater before discharge.

12.6 Key Environmental Problems Avoided and Compensation Areas Included

12.6.1 Apart from the Wetland Buffer Area where the barrage site is located, all recognized sites of conservation importance have been identified and avoided during the planning and design of the Project. All the construction and infrastructure works would be within the existing concrete-lined YLN and surrounding disturbed land. No works will encroach into any recognized sites of conservation importance or important habitats.

12.6.2 To minimize noise disturbance to over wintering migratory waterbirds, noisy construction activities such as demolition and percussive piling works will avoid the dry season.

12.6.3 Sections 12.3 and 12.4 have summarized the key approaches adopted in the current proposal to avoid, minimize and mitigate environmental impacts. Some of these approaches have contributed to avoid a number of environmental problems and to protect a number of environmental 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 ¡V Summary of Key Environmental Problems Avoided and Sensitive Areas Protected

Design Approach	Environmental Problems Avoided and Sensitive Areas Protected
Avoid work on the semi-natural Shan Pui River and Old Kam Tin River	¡P Adverse impacts on water quality and ecology would be avoided
Avoid excavation works in the channel during wet season	¡P Adverse impacts on water quality would be avoided
Avoid noisy construction works during winter migratory period of waterbirds	¡P Adverse impacts on ecology would be avoided
Avoidance / Minimization of Construction Disturbance on Ardeid Night Roost	¡P Adverse impacts on ecology would be avoided
Adopt environmentally friendly construction methods, e.g. offsite precast structures / modular integrated consturction	¡P Adverse impacts on air quality, noise, water quality, waste and ecology would be avoided
Implementation of environmental monitoring and auditing system during construction phase	¡P Ensure that all the recommended mitigation measures are properly implemented

12.7 Environmental Benefits of Environmental Protection Measures Recommended

12.7.1 Mitigation measures have been recommended to further reduce the environmental impacts during the construction and operational phases of the Project. Key recommended mitigation measures and associated benefits are summarized in Table 12.2 below.

Table 12. 2 ¡V Key Recommended Mitigation Measures and Associated Environmental Benefits

EIA Aspects	Key Recommended Mitigation Measures	Associated Environmental Benefits
Air Quality	Construction Phase ¡P Implement relevant dust control measures stipulated in the Air Pollution Control (Construction Dust) Regulation, and good site practices. ¡P Regular maintenance of construction equipment deployed on-site should be conducted to prevent black smoke emission. ¡P Connect construction plant and equipment to mains electricity supply and avoid use of diesel generators and diesel-powered equipment as far as practicable to minimize the emission impact from these machineries on nearby residents. ¡P Proper storage, handling and timely disposal of odorous excavated materials. Operation Phase ¡P Proper storage, handling and timely disposal of odorous screening materials. ¡P Regular inspection at inlet chamber of existing pumping facilities to prevent accumulation of debris/materials at the inlet screens causing odour nuisance.	¡P Protect air sensitive receivers by reducing construction dust emission and odour nuisance
Noise	Construction Phase ¡P Good construction site practice; ¡P Use of quiet PME; ¡P Adoption of movable noise barriers; ¡P Use of noise insulation sheet; ¡P Adoption of fixed temporary noise barriers; and ¡P Scheduling of PME / construction activities. Operation Phase ¡P Quieter plant should be chosen as far as practical; ¡P Include noise levels specification when ordering new plant items; ¡P All openings, including louvres for ventilation and machine room doors should be oriented away from the NSRs as far as practicable; ¡P Silencers, acoustic louvres or acoustic doors should be used where necessary; and ¡P Develop and implement a regularly scheduled plant maintenance programme so that plant items are properly operated and serviced. The programme should be implemented by properly trained personnel.	¡P Protect noise sensitive receivers by reducing construction and operational noise impacts
Water Quality	Construction Phase ¡P Adopt good site practices. ¡P Implementing proper site management measures to control site runoff and drainage following the guidelines provided in ProPECC PN 1/94. ¡P Use of containment structures and diversion channels to facilitate a dry or at least confined excavation within the nullah. ¡P Proper treatment of wastewater before discharge in accordance with WPCO. ¡P Proper storage, handling and disposal of chemicals. ¡P Response procedures for accidental spillage or leakage of chemicals ¡P Water quality monitoring during construction. Operation Phase ¡P Good site practice for removal of excessive silt, vegetation, debris and obstruction.	¡P Protect the downstream water sensitive receivers
Waste and Land Contamination	Construction Phase ¡P Avoidance, minimization, recycling, treatment and safe disposal of waste. ¡P Good waste management and control practices to avoid generation of excessive amount of waste. ¡P Sediment should be excavated, transported and disposed of in a manner to minimize adverse environmental impacts. ¡P Proper storage, handling and disposal of chemicals. ¡P Proper storage, recycling and disposal of general refuse. Operation Phase ¡P The screenings, silt materials and debris collected during operation and maintenance should be properly packed and transported to the designated landfill for disposal as soon as possible. ¡P All chemical waste should be properly stored, labelled and removed by licensed waste collectors in accordance with Waste Disposal (Chemical Waste) (General) Regulation.	¡P Minimize waste generation ¡P Ensure proper handling and disposal of contaminated sediment ¡P Ensure proper handling of chemical waste
Ecology	Construction Phase ¡P Avoid impact to recognized sites of conservation importance. ¡P Consideration of alternative construction method to minimize ecological impact. ¡P Careful phasing of construction activities. ¡P Use of noise barriers / acoustic screens. ¡P Use of quality powered mechanical equipment. ¡P Translocation of fish species of conservation importance Gobiopterus macrolepis prior to commencement of construction works. ¡P Avoid noisy construction works during winter migratory period of waterbirds ¡P Conduct pre-construction survey after 17:00 from February to September and 16:30 from October to January to confirm any night roost locations and schedule the construction works, within a 100m radius, accordingly to avoid impact on Ardeid Night Roost along Kam Tin River Operation Phase ¡P Operation of tidal barrier to allow brackish waters flushing in. ¡P Discharge design to minimize souring effect to tidal mudflat. ¡P Revitalisation of YLN. ¡P Greening opportunity on building structure. ¡P Reducing glare / lighting of building structure.	¡P Avoid impact to recognized sites of conservation importance ¡P Minimize ecological impact ¡P Mitigate ecological impact ¡P Ecological enhancement opportunity
Fisheries	Construction Phase ¡P Implement water quality mitigation measures. Operation Phase ¡P No mitigation measures would be required.	¡P Protect fisheries resources
Cultural Heritage	Construction Phase ¡P Implement mitigation measures such as condition survey, vibration monitoring, provision of buffer zones and provision of safe public access. Operation Phase ¡P No mitigation measures would be required.	¡P Protect close proximity graded historic buildings and nil-grade structures during construction
Landscape and Visual	Construction Phase ¡P Implement good site practices. ¡P Erection of decorative mesh screen or construction hoarding. ¡P Avoidance of excessive height and bulk of site buildings and structures. ¡P Control of night time lighting. ¡P Tree preservation, tree transplantation and compensatory tree planting. Operation Phase ¡P Enhanced design to nullah sides / bed, streetscape, nullah crossing. ¡P Sensitive design of barrage and structures in terms of scale, height and bulk. ¡P Additional viewpoints, seating areas and open space. ¡P Barrage lightings to minimize light spill and glare. ¡P Green roof and vertical greening on buildings.	¡P Enhance the landscape quality and visual appearance of the project