12 SUMMARY of Environmental Outcome

12.1 Key Environmental Outcomes

12.1.1.1 The major sensitive areas within the study area include different type of residential development from village houses to high-rise residential buildings, commercial buildings, industrial premises, recreational areas and place of public worship located within north-west New Territories. A summary of the key environmental outcomes arising from this EIA study and environmental benefits of the environmental protection measures are presented in Table 12.1 below.

Table 12.1 Summary of Key Environmental Outcomes / Benefits

Issue	Environmental Outcome / Benefits
Major environmental benefits of the Project and key environmental problems avoided	Currently, the sludge produced after sewage treatment process is dewatered in the STWs and then delivered to landfills for disposal. Due to its high water content, the dewatered sludge has to be co-disposed with municipal solid waste (MSW) and construction waste in a ratio of 1:10 to maintain the stability of the landfills. However, this current practice is considered not sustainable due to the following reasons: · Sludge takes up precious space of the existing landfills, which are anticipated to reach their capacities in early to mid 2010. · Disposal of biodegradable waste to landfill is not in line with international trend. · The disposal ratio of dewatered sludge to MSW (1:10) would not be achieved due to the decrease in MSW with the implementation of various waste management measures in accordance with “A Policy Framework for the Management of Municipal Solid Waste (2005-2014)”, and increase in sludge production after the commissioning of Harbour Area Treatment Scheme Stage 2A and expansions of some existing STWs. There is an urgent need for an alternative sludge disposal mean and this Project provides a solution to this environmental problem. With the proposed STF, the amount of waste to be disposed of at landfills will substantially decrease as the volume of waste generated after the sludge treatment process would only be about 10% of the original volume. The landfill life can be extended. Besides, the production of greenhouse gases due to disposal of sewage sludge will be reduced.
Environmentally friendly designs recommended	A review of the findings of the previous studies on sludge treatment and the information of the latest sludge treatment technologies was carried out, and a comprehensive evaluation on the shortlisted options, including incineration and heat drying, was conducted in respect of environmental, engineering and financial considerations for selecting the preferred option for the STF. It was concluded that incineration was the most preferable option with the following merits: · Low total costs · Large reduction in volume of end product to be disposed to landfill · Reuse of energy from the incineration process
Population and Environmentally Sensitive Areas Protected	The major sensitive areas within the study area include different type of residential development, commercial buildings, industrial premises, recreational areas and place of public worship located within north-west New Territories. With the implementation of the proposed control and mitigation measures, the sensitive receivers for different environmental aspects would be protected from adverse impacts arising from the Project during both construction and operation phases. The environmental benefits of environmental protection measures recommended, compensation areas included, and the population and environmental sensitive receivers protected are summarized below.
Air Quality	Environmental benefits of environmental protection measures recommended: Those ASRs located near the construction sites are protected through implementation of practicable dust suppression measures. Air pollution control and stack monitoring system will be installed for the STF to ensure that the emissions from the STF stacks will meet the stringent target emission limits equivalent to those stipulated in Hong Kong and the European Commission for waste incineration. Besides, all the potential odour emissions associated with the operation of the STF will be collected and destroyed by the incineration process or ventilated to deodorizer before discharge to the atmosphere. No unacceptable residual impacts from the cumulative impacts of the STF emissions and other existing emissions from Black Point Power Station, Castle Peak Power Station, Green Island Cement Plant, existing WENT Landfill, proposed WENT Landfill Extension, EcoPark, Shui Wing Steel Mill etc are anticipated at the ASRs. Compensation areas included: N/A Population and environmental sensitive receivers protected: Existing ASRs & planned developments, including residential, commercial and recreational areas located within north-west New Territories.
Human Health Risk	Environmental benefits of environmental protection measures recommended: Control measures have been recommended to minimize the potential associated with microbes from dewatered sewage sludge during their transportation, storage and handling in the STF operation. Besides, design measures for radon, such as a soil cover beneath the buildings before construction works and sufficient ventilation would reduce radon influx; regular maintenance for floor slabs and walls shall make radon reduction techniques more effective and cost-efficient. Air pollution control and stack monitoring system will be installed for the STF to ensure that the emissions from the STF stacks will meet the stringent target emission limits equivalent to those stipulated in Hong Kong and the European Commission for waste incineration. In terms of lifetime individual excess cancer risks, the highest cancer risk associated with the STF emission is predicted to be 1.51 x 10^-5 which is considered to be at the level of “As Low As Reasonably Practicable”. For cumulative acute and long term non-carcinogenic health impact of the STF imposed to the worst impacted human receptors, the levels of non-carcinogenic chemicals were found to be insignificant when compared to the adopted/derived reference levels. Compensation areas included: N/A Population and environmental sensitive receivers protected: Construction and operation staff of the STF Project as well as the sensitive receivers in close proximity of the Project site.
Waste Management Implications	Environmental benefits of environmental protection measures recommended: Implementation of the proposed waste control and mitigation measures would avoid the potential water quality, dust, odour, and noise impacts associated with handling, transportation and disposal of the identified wastes arising from the construction phase of the Project. The incinerator ash and flue gas cleaning residue will be disposed of at the landfill after checked for compliance with the proposed incineration residue pollution control limits. Besides, with proper implementation of the recommended practices and response procedures for contamination prevention, the potential for contamination due to the STF operation would be minimal. No residual waste impact arising from the operation of the Project is expected. Compensation areas included: N/A Population and environmental sensitive receivers protected: Water quality, air, and noise sensitive receivers at or near the Project site, the waste transportation routes and the waste disposal site.
Water Pollution	Environmental benefits of environmental protection measures recommended: Potential water quality impacts generated from the construction of the Project would include construction site runoff and drainage, wastewater generated from general construction activities, and sewerage from construction workforce. During operational phase, waste water would be generated from sanitary facilities. Adverse water quality impacts would be caused if such waste water directly discharge into the nearby streams and coastal waters. With implementation of recommended mitigation measures and good practices as listed in ProPECC PN 1/94, as well as provision of on-site wastewater treatment during the operation of STF and recycling treated wastewater, unacceptable residual water quality impacts caused by construction and operation of the Project would not be anticipated at the nearby streams and coastal waters. Compensation areas included: N/A Population and environmental sensitive receivers protected: Two moderate sized streams and coastal waters
Ecology	Environmental benefits of environmental protection measures recommended: Direct impact to breeding activities of Little Grebe could be avoided by conducting thorough site inspection in the Project Area by experienced ecologist before the commencement of any site activities. Careful selection of location of abutments (permanent structure) and minimization of number and size of temporary supporting structures for the vehicular bridge would reduce impact to natural aquatic habitats. Water quality control measures would minimise indirect impact on aquatic habitats and associated wildlife due to deterioration of water quality. Indirect disturbance to wildlife in nearby habitat would be lowered by use of quieter piling machinery and construction plants, hoarding and standard good site practices during construction, as well as screen planting in the STF and along the associated access road during operation. Compensation areas included: Created habitats in form of shallow pond(s) would be provided in a less disturbed area within the STF for Little Grebe. Population and environmental sensitive receivers protected: Vegetation, wildlife and their associated habitats at and in the vicinity of the Project area.
Noise	Environmental benefits of environmental protection measures recommended: The residual noise exceedances at the representative NSRs are due to the existing off-site traffic flow. The overall road noise contribution due to the off-site traffic generated from the operation of the proposed STF would be less than 1dB(A). No adverse noise impacts arising from the operation of STF are predicted at any of the representative NSRs. Compensation areas included: N/A Population and environmental sensitive receivers protected: Existing NSRs located in close proximity along Lung Kwu Tan Road
Landscape and Visual	Environmental benefits of environmental protection measures recommended: Implementation of mitigation measures, such as careful protection of the existing trees to be retained, compensatory planting, control of night-time lighting, erection of decorative screen hoarding, would reduce the impacts to the visual sensitive receivers (VSRs) during the construction phase. The impacts to VSRs during the operation stage would be alleviated by implementation of the measures, including aesthetic design of the façade of the structures, shrub and climbing planting greening to soften proposed structures, tree planting to screen the STF. The proposed measures would also enhance the existing landscape of the ash lagoon area. Compensation areas included: Compensatory planting of heavy standard trees in a ratio not less than 1:1 for the loss of about 460 no. of trees will be provided. Population and environmental sensitive receivers protected: Existing and future VSRs identified with the Zone of Visual Influence of the Project.
Landfill Gas Hazard	Environmental benefits of environmental protection measures recommended: The recommended protection measures will reduce the landfill gas risk to the STF construction workers and operators. In particular, the landfill gas cut-off trench barrier would prevent landfill gas migrates into the STF site. Compensation areas included: N/A Population and environmental sensitive receivers protected: Construction workers (during construction phase) and STF staff (during operation phase)

12.2 Impact Summary

12.2.1 General

12.2.1.1 This EIA Report has provided an assessment of the potential environmental impacts associated with the construction and operation of the Project, with the consideration of the potential cumulative impact from other concurrent projects. Specific mitigation measures requirements for the Project, as well as an environmental monitoring and auditing programme, have been developed. A summary of the environmental impacts associated with the Project are presented below.

12.2.2 Air Quality

12.2.2.1 The potential air quality impacts from the construction of the Project would mainly be related to construction dust from excavation, materials handling, filling activities and wind erosion. With the implementation of mitigation measures specified in the Air Pollution Control (Construction Dust) Regulation, dust impact on nearby air sensitive receivers would be minimal.

12.2.2.2 During the operation of the STF, the potential sources of air quality impacts would be the air emissions from the stacks of incineration process and the odour nuisance from the on-site wastewater treatment plant and the sludge reception hall.

12.2.2.3 There would also be cumulative air quality impacts contributed from other existing and planned emission sources in Tuen Mun, including the Black Point Power Station, Castle Peak Power Station, Green Island Cement Plant, WENT landfill and the proposed WENT landfill extension, EcoPark, Shiu Wing Steel Mill, etc.

12.2.2.4 Air pollution control and stack monitoring system will be installed for the STF to ensure that the emissions from the STF stacks will meet the stringent target emission limits equivalent to those stipulated in Hong Kong and the European Commission for waste incineration. Besides, all the potential odour emissions associated with the operation of the STF will be collected and destroyed by the incineration process or ventilated to deodorizer before discharge to the atmosphere.

12.2.2.5 With the implementation of practicable air pollution control, the STF would not cause adverse cumulative air quality impact at all the air sensitive receivers in the vicinity of the Project site and those further away in the Tuen Mun new town area.

12.2.3 Human Health Risk Assessment

12.2.3.1 Apart from the general air quality impacts, the cancer risk arising from exposure to carcinogenic contaminants of concern (COCs) associated with the emissions of STF was also evaluated in the EIA. In terms of lifetime individual excess cancer risks, the highest cancer risk associated with the STF emission is predicted to be 1.51 x 10^-5 which is considered to be at the level of “As Low As Reasonably Practicable”.

12.2.3.2 Cumulative acute and long term non-carcinogenic health impact of the STF imposed to the worst impacted human receptors were assessed and compared with local and overseas guideline levels. It was concluded that the levels of non-carcinogenic chemicals were found to be insignificant when compared to the adopted/derived reference levels.

12.2.3.3 Microbes from dewatered sewage sludge during their transportation, storage and handling in the STF operation were assessed. Twenty-five hazards concerning microbial emissions associated with the STF operations were identified. With consideration of existing/expected safeguards, the risk levels of all the 25 hazards were found to be tolerable and were at the level of “As Low As Reasonably Practicable”.

12.2.3.4 The potential health risk induced by radon emissions associated with PFA arising from the construction and operation was also evaluated. The estimation indicated that there would be no significant radiological hazard to workers working outdoors in the STF or in the restored/operating ash lagoon area adjacent to the STF. The annual effective dose equivalent to a worker spending 2000 hours outdoors on an ash filled lagoon would be about 0.19mSv, which is insignificant comparing to annual limit of 1 mSv for general public suggested by the International Commission on Radiological Protection (ICRP). Since the risk imposed on workers with direct radon exposure is not significant and that there will be no off-site disposal of PFA under this Project, the risk on off-site air sensitive receivers will also be insignificant as well. From various literature researches, the radon health risk for construction and operation of the proposed STF would be negligible.

12.2.4 Waste Management Implications

12.2.4.1 The types of waste would be generated during the construction phase of the Project include construction and demolition (C&D) materials from the construction activities, general refuse from the workforce and chemical wastes from the construction plant and equipment. Adverse environmental impact is not be expected during the construction phase with the approved methods to handle, transport and dispose the waste and the recommended good site practices being strictly followed.

12.2.4.2 The end product from the incineration process would include incinerator ash (bottom ash and fly ash) and flue gas cleaning residue. The incinerator ash and flue gas cleaning residue will be disposed of at the landfill after checked for compliance with the proposed incineration residue pollution control limits. Pre-treatment may be required for flue gas cleaning residue prior to disposal.

12.2.4.3 Limited amount of chemicals or chemical wastes would be used or generated for the operation of the STF. With proper implementation of the recommended practices and response procedures for contamination prevention, the potential for contamination due to the STF operation would be minimal.

12.2.5 Water Pollution

12.2.5.1 The potential sources of water quality impact arising during the construction phase of the Project include construction site runoff and drainage, wastewater generated from general construction activities, and sewerage from the workforce. With implementation of the recommended mitigation measures and site practices outlined in ProPECC PN 1/94, no unacceptable residual impacts on water quality are expected.

12.2.5.2 During the operation phase of the Project, wastewater will be generated from sanitary facilities used by plant personnel, commercial activities and sludge treatment activities in the STF. An on-site wastewater treatment plant will be provided. All generated wastewater will be discharged to the on-site wastewater treatment plant and treated by the process of Membrane Bioreactor (MBR). The treated effluent from the wastewater treatment plant will be reused in the STF and there would be no wastewater effluent discharged to the coastal waters of Deep Bay.

12.2.5.3 Saline water would be discharged from the proposed desalination plant in a low discharge rate. The saline water discharged from the desalination plant will comply with the standards for effluents discharging into the coastal waters of Deep Bay Water Control Zone. Adverse impacts on water quality would not be expected.

12.2.5.4 To prevent potential emission of microbes during transportation, storage and handling of dewatered sewage sludge into surrounding waterbodies, proper design of the STF will be conducted and the recommended “risk control measures” will be implemented. No unacceptable water quality impacts are expected.

12.2.6 Ecology

12.2.6.1 A literature review supplemented by comprehensive ecological survey covering dry and wet seasons was undertaken to establish the ecological profile of the Assessment Area. Nine habitat types were identified within the Assessment Area including ash lagoons, secondary woodland, grassland / shrubland, plantation, watercourse, developed area / disturbed area, seawall, orchard and coastal waters. Three species of flora and 27 fauna of conservation interest were recorded in the Assessment Area.

12.2.6.2 Most of the identified habitats in the Assessment Area have low ecological value, except the Middle Lagoon which was ranked as moderate, and the East Lagoon, secondary woodland, the watercourse W1 and W2 were ranked low to moderate.

12.2.6.3 A total of approximately 7.8 ha of habitats would be permanently lost under this Project. Over 79% of the affected habitats are man-made habitats including approximately 6 ha ash lagoon, 0.1 ha developed area/disturbed area, 0.02 ha plantation and 1.6 ha grassland/shrubland. A very small area of an estuary would probably be affected during the construction of vehicular bridge temporarily. As the proposed Project is a land based project, no marine ecological habitats would be affected.

12.2.6.4 The construction of the STF would affect the potential breeding ground of Little Grebe in the East Lagoon. The impact is considered minor as alternative similar habitat for Little Grebe is available in the adjacent Middle Lagoon.

12.2.6.5 Potential indirect construction and operation impacts to the habitats and associated wildlife adjacent to the proposed STF would be resulted from increased human disturbance / activities and noise due to vehicles entering and exiting the site.

12.2.6.6 Mitigation measures such as provision of 3m high hoarding along the boundary of the works areas, screening (i.e. fencing with climbers or plantation) along the STF site boundary and the two sides of access road, good site practices, use of quiet construction methods and machinery, measures to control potential sedimentation / water quality impacts as well as habitat enhancement (i.e. tree planting and creation of pond(s) for Little Grebe) have been recommended to minimize potential indirect impacts to wildlife. As a precautionary measure, the works area will be thoroughly inspected by experience ecologist(s) to confirm no breeding activities of Little Grebe would be affected by the construction activities before commencement of any site works.

12.2.6.7 With the implementation of the recommended mitigation measures, it is anticipated that the construction and operation for the proposed works would not result in unacceptable impacts on ecological resources. The implementation of all mitigation measures would be subject to regular audit as part of the EM&A programme.

12.2.7 Noise Impact

12.2.7.1 No existing or planned noise sensitive receivers (NSRs) were identified within 300m from the site boundary of the Project. Potential impacts due to noise generated from the construction of the Project and fixed plant noise from the operation of STF are not expected.

12.2.7.2 With regards to the potential traffic noise impact due to the off-site traffic generated from the operation of the proposed STF, a traffic noise impact assessment was carried out for the prevailing scenario (Year 2012 before commencement of the proposed STF) and scenarios with and without the operation of the STF in 2027.

12.2.7.3 The assessment results indicated that the predicted traffic noise due to the off-site traffic generated from the proposed STF would not result in significant increase in traffic noise impact on the NSRs along Lung Kwu Tan Road.

12.2.8 Landscape and Visual Impact Assessment

12.2.8.1 Seven landscape resources and five landscape character areas were identified within 500m from the site area. The impact to these landscape resources and landscape character areas would be insubstantial, except for the ash-lagoon and seashore. Mitigation measures, such as greening along the site boundary to provide screening, and aesthetic design of the proposed STF matching with adjacent landscape setting of the site, would be implemented. After the implementation of the mitigation measures, the residual impact to the ash-lagoon and seashore during the construction phase and on day 1 of the operation phase would be reduced to moderate, and the long-term residual impact to the ash-lagoon and seashore would be reduced to slight. Considering the fact that the affected trees in the site area are of low to medium amenity value and landscape value of the existing “man-made” ash-lagoon is not high, the impact during the construction and operation phase are considered acceptable.

12.2.8.2 Ten visual sensitive receivers (VSRs) were identified within the zone of visual influence. Most of these VSRs have low sensitivity to change, and the magnitude of impact to them would be negligible or small. Therefore, the visual impact to seven VSRs would be insubstantial or slight during construction and operation phase. However, the visual impact to the residents in Shekou and the travelers of the future access road adjacent to the STF would be moderate, while that to the residents in Pak Nai would be substantial. Mitigation measures would be implemented during the construction and operation phase to reduce the potential visual impacts to the VSRs. After the implementation of the mitigation measures, the residual impact to these VSRs during the construction phase and on day 1 of the operation phase would be reduced to slight or moderate, and the long-term residual impact to these VSRs would be reduced to insubstantial or slight.

12.2.8.3 Overall, it is considered that the residual landscape and visual impacts of the proposed development would be acceptable with mitigation measures during construction and operation phases.

12.2.9 Landfill Gas Hazard

12.2.9.1 A source-pathway-target analysis was conducted to assess the risk of landfill gas hazard from the existing WENT Landfill and the proposed WENT Landfill Extensions to this Project. The overall risk level for both construction and operation phase of the Project associated with the existing WENT Landfill was assessed to be low, while the risk level associated with the WENT Landfill Extensions was assessed to be medium.

12.2.9.2 A number of protection measures have been recommended for the Project to safeguard the safety of the site workers and all personnel presence at the Project site. No adverse impact of landfill gas hazard on this Project is anticipated.