· Air Quality
· Hazard to Life
· Water Quality
· Waste Management Implications
· Landscape and Visual
· Noise
Construction Phase
10.2 Air quality impacts from the construction works of the Project would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion. With the implementation of mitigation measures specified in the Air Pollution Control (Construction Dust) Regulation, proposed dust suppression measures and good site practices checked by regular site environmental audits, no adverse dust impact on the ASRs would be anticipated.
Operation Phase
10.3
During the operation of the
OWTF, a centralized air pollution control unit would be used to remove air
pollutants, dust and odorous gas in the air extracted from the main buildings
of OWTF and the wastewater treatment unit.
The potential major sources of air quality impacts arising from the OWTF
would be the air emissions from the stacks of centralized air pollution control
unit and cogeneration units. Flaring emissions may be emitted if there is a
failure in the cogeneration units.
10.4 The air quality background level for the operation year of the OWTF has been predicted using the PATH model and has taken into account key pollution sources such as power stations, aviation, marine traffic, vehicular traffic, industrial chimneys within HKSAR as well as emissions within Pearl River Delta Economic Zone. Modelling for air emissions from the stacks of centralized air pollution control unit and cogeneration units or standby flaring gas unit of OWTF, as well as vehicular emissions and marine emissions within the study area has been undertaken and the results have been combined with the air quality background levels. Results indicate that the predicted cumulative air pollutants levels would comply with Air Quality Objectives.
10.5 Assessment has also been conducted for potential odour impacts arising from the OWTF, taking into account of cumulative odour impacts from North Lantau Refuse Transfer Station and Siu Ho Wan Sewage Treatment Works. The predicted cumulative odour concentrations at the representative ASRs would comply with the EIAO-TM criteria (i.e. 5 odour units based on an averaging time of 5 seconds).
10.6 Commissioning tests would be conducted for emissions from the stacks of the centralized air pollution control unit, cogeneration units and standby flaring gas unit. During operation phase, stack monitoring would be installed for the OWTF to ensure that the air emissions from the OWTF will meet the design emission limits as well as EPD criteria. Odour patrol at the plant boundary is also proposed to monitor any odour impact arising from the operation of the OWTF. The predicted air quality impact from the operation of the OWTF would be insignificant.
10.7 A hazard assessment has been carried out to evaluate the risk to construction workers and operational staff of the OWTF due to the transport, storage and use of chlorine associated with the operations at Siu Ho Wan Water Treatment Works (SHWWTW).
10.8 Hazardous scenarios associated with the operations at SHWWTW have been identified and assessed in this study. Hazardous events for biogas storage have been investigated through consequence analysis. These hazardous events would not escalate to additional chlorine release scenario at SHWWTW. Thus, no hazardous scenario associated with the operations at SHWWTW due to impact from biogas storage is found.
10.9 A quantitative risk assessment has been conducted to determine the impact of the identified hazardous scenarios on the surrounding population during construction and operation phases of the OWTF in terms of individual and societal risks. Both individual and societal risks comply with the risk guidelines stipulated in Annexes 4 and 22 of the Environmental Impact Assessment Ordinance Technical Memorandum (EIAO-TM).
10.10 An As Low As Reasonably Practicable (ALARP) assessment has been carried out by identifying all practicable mitigation measures and assessing the cost effectiveness of each measure in terms of the risk reduction achieved and the cost of implementing the measures. The results show compliance with the ALARP principles and Risk Guidelines (EIAO-TM Annex 4) provided recommendations are implemented.
Construction Phase
10.11 During construction phase of the Project, potential water quality impact would be generated from site run-off, sewage from workforce, and discharge of wastewater from various construction activities. Provided that all the recommended mitigation measures are properly implemented, no adverse water quality impacts would be expected. To avoid any potential water quality impact, the nullah decking work would be carried out during the dry season, between October and March.
Operation Phase
10.12 The operation of the OWTF is to convert organic waste into compost and biogas. All sewage or wastewater generated from the operation of the Project will be adequately treated in the on-site wastewater treatment plant before reused on-site or discharged to the sewerage system. No residual water quality impacts would be anticipated.
Construction Phase
10.13 Waste types to be generated during the construction of OWTF would likely to include excavated materials (from site formation and foundation works), C&D materials (from building and road construction works), chemical waste (from maintenance of construction plant and equipment) and general refuse (from construction workforce). Provided that waste is handled, transported and disposed of using approved methods and that the recommended good site practices are strictly followed, adverse environmental impacts would not be expected during the construction phase.
Operation Phase
10.14 During the operation of OWTF, waste types to be generated would likely include wastes generated from pre-treatment processes (from pre-treatment sorting of organic waste feedstock), chemical wastes (from maintenance of mechanical equipment) and general refuse (from visitors and on-site staff). Provided that waste is also handled, transported and disposed of using approved methods and that the recommended good site practices are strictly followed, adverse environmental impacts would not be anticipated during the operation phase.
10.15 Potential sources of contamination in OWTF operation have been identified. It is estimated that limited amount of chemicals or chemical wastes would be used / produced during the operation. Good practices and response procedures for contamination prevention have been recommended. With proper implementation of the recommended practices and procedures, the potential for contamination due to OWTF operation is expected to be minimal.
10.16
Three landscape
resources and seven landscape character areas were identified within
10.17
Fifteen visual
sensitive receivers (VSRs) are identified within the Zone of Visual Influence
(ZVI. Most of these VSRs have low sensitivity, and the magnitude of impact
to them would be negligible or small. Only the visual impact to the site
staff in Siu Ho Wan Water Treatment Works, passengers on North Lantau Highway
and hikers in Lantau North (Extension) Country Park would be moderate. Mitigation measures would be implemented
during the construction and operation phase to reduce the potential visual
impacts to these VSRs. After the implementation of the mitigation
measures, the long-term residual impact to these VSRs would be reduced to
insubstantial or slight.
10.18
Overall, it
is considered that the residual landscape and visual impacts of the proposed
development would be acceptable with mitigation measures during Construction Phase
and beneficial during the Operation Phase.
10.19
It has been revealed that there would be no planned and committed noise
sensitive development within the study area, and it is
noted that the nearest noise sensitive receiver to Siu
Ho Wan is the
10.20 Since the nearest noise sensitive receiver is located considerably distant from the Project site and is substantially screened by natural terrain, the noise impact caused by the Project itself and any cumulative noise impact associated with the Project is thus considered insignificant.
10.21 The findings of this EIA Study have determined the likely nature and extent of environmental impacts predicted to arise from the construction and operation of the Project. Where appropriate, the EIA has identified mitigation measures to ensure compliance with environmental legislation and standards. The feasibility, practicability, programming and effectiveness of the mitigation measures have been assessed and determined.
10.22 Overall, the EIA Study for the proposed OWTF Phase I has predicted that the Project, with the implementation of the proposed mitigation measures for construction and operation phases, would comply with all applicable environmental standards and legislation. This EIA has also demonstrated the acceptability of the residual impacts from the Project and the protection of the population and environmentally sensitive resources.
10.23 A summary of the key environmental outcomes arising from the EIA study, including the population and environmentally sensitive areas protected, environmentally friendly designs recommended, key environmental problems avoided, compensation areas included and the environmental benefits of environmental protection measures recommended are presented in Table 10.1 below.
Table 10.1 Summary
of Key Environmental Outcomes / Benefits