13.     Environmental Outcome and Conclusions

13.1          Summary of Mitigation Measures Proposed

13.2          Key Environmental Outcomes

13.3          Overall Conclusion

 

 

13.             Environmental Outcome and Conclusions

13.1          Summary of Mitigation Measures Proposed

13.1.1.    The mitigation measures proposed are listed below:

·             Air quality: Implementation of good house-keeping and dust suppression measures such as water spraying.

·             Noise: Implementation of quiet PMEs, temporary noise barrier and good site practices.

·             Water quality: Implementation of good site practices to avoid/minimize polluted site runoff from the Project.

·             Waste management: Implementation of waste reduction and good management control.

·             Ecology: The Project will involve drainage channel widening and will not encroach to any ecological sensitive areas. A range of mitigation measures related to good site management and construction practice, as well as scheduling of the staged work program have been recommended.

·             Landscape and visual: Landscape and visual impacts are acceptable with the implementation of mitigation measures.

·             Land contamination: Should suspected contamination be found during construction, the extent and nature of contamination within Project areas should be properly assessed and the contaminated soil/groundwater should be remediated in accordance with EPD issued publications.

·             Cultural Heritage and Archaeology: The alignments of drainage channel widening and new drainage culverts will avoid/minimize direct and indirect impact to historic building(s) and known archaeology.

13.2          Key Environmental Outcomes

13.2.1.    The key environmental outcomes of the Project are summarised below.

Estimated Population Protected from Various Environmental Impacts

13.2.2.    With the implementation of dust and noise mitigation measures, estimated population to be protected during construction phase is estimated as below:

·             Sung Shan New Village: Approximately 6000.

·             Tai Wo: Approximately 3500.

·             Lei Fa Tei: Approximately 11000.

·             Ha Che: Approximately 7500.

Environmentally Sensitive Areas Protected

13.2.3.    With the implementation of mitigation measures, estimated Conservation Area and area of country park protected is estimated as below:

·             Sung Shan New Village: Approximately 378,000 m2.

·             Tai Wo: Approximately 331,000 m2.

·             Lei Fa Tei: Approximately 177,000 m2.

·             Ha Che: Approximately: Approximately 426,000 m2.

Environmentally Friendly Options Considered and Incorporated in The Preferred Option

13.2.4.    Open-cut method and trenchless method has been considered in Section 2 of this EIA Report. For Open-cut method, Faster construction progress and hence the period of environmental disturbance is reduced. Meanwhile, for trenchless method, excavation is only required at launching and receiving pit locations. Hence localized construction nuisances is limited to the sensitive receivers near the working pits only.

Environmental Designs Recommended

13.2.5.    Major works will be conducted but open-cut method to minimize period of nuisance to nearby sensitive receiver.

Key Environmental Problems Avoided

13.2.6.    Key issues in terms of water quality would be related to excavation works for the construction phase of the proposed drainage improvement works. To minimize potential impacts on water quality during the channel construction, the excavation would be carried out in dry condition (even in wet season) by diverting the stream flow from upstream by a temporary drainage channel with a temporary sheet piles, earth bund or barrier, so that the works area will remain dry for later excavation and widening works

13.2.7.    Noise levels exceedance at the representative NSRs during construction phase is anticipated for unmitigated scenario. With adopting the quiet PMEs, temporary noise barrier and good site practices, no exceedance of the construction noise criteria is anticipated.

Environmental Benefits of the Environmental Protection Measures Recommended

13.2.8.    The anticipated environmental benefits are listed below:

·             Air quality: Implementation of good house-keeping and dust suppression measures such as water spraying would avoid/minimize dust emissions during construction phase.

·             Noise: Implementation of temporary noise barriers and quieter plant would reduce the construction noise impact to the neighbouring noise sensitive receivers.

·             Water quality: Implementation of good site practices to avoid/minimize polluted site runoff from the Project to neighbouring water sensitive receivers.

·             Waste management: Implementation of waste reduction and good management control could minimize environmental implication from on-site waste storage.

·             Ecology: The Project will involve drainage channel widening and will not encroach to any ecological sensitive areas. only a few natural or semi-natural habitats and species of conservation concern will be directly or indirectly affected by the project. Moreover, the permanent changes in the hydrological characteristics of the watercourses including the newly formed meanders orand narrowed water channels, as well as the community structure of the riparian vegetation, would have an influential effect on the aquatic faunal assemblage in the project’s watercourse.

·             Landscape and visual: Landscape and visual impacts are acceptable with the implementation of mitigation measures.

·             Land contamination: All identified potentially contaminated sites were located outside works area boundary. Therefore contamination potential arising from the Project works is not anticipated.

·             Cultural Heritage and Archaeology: The alignments of drainage channel widening and new drainage culverts will avoid/minimize direct and indirect impact to sites of historic building and known archaeology.

13.3          Overall Conclusion

Air Quality

13.3.1.    Potential impacts arising from the construction of the Project are expected to be related to the dust nuisance from construction works and gaseous emissions from the construction plant and vehicles. The air quality impacts are expected to be localized because it is anticipated that the scale of the proposed drainage improvement works would be small and the number of construction equipment employed would be limited given the small work space available. With proper implementation of good site practices stipulated in the Air Pollution Control (Construction Dust) Regulation and with the adoption of construction machineries and non-road vehicles meeting the prescribed emission standards and requirements specified in the Air Pollution Control (Non-road Mobile Machinery) (Emission) Regulation, no adverse air quality associated with the proposed drainage improvement works is anticipated. It is also anticipated that there would be no adverse impact during the operation phase.

Noise

13.3.2.    The potential noise impacts due to the proposed drainage improvement works at Sung Shan New Village, Tai Wo, Lin Fa Tei and Ha Che have been evaluated. Whilst the Contractor may prefer to use different construction methods, types and numbers of PMEs, the assumed tentative construction schedule and plant inventory are representative and provide a conservative noise assessment of reference value.

13.3.3.    With adopting the quiet PMEs, temporary noise barrier and good site practices as stipulated in the Code of Practice on Good Management Practice to Prevent Violation of the NCO (Cap. 400) (for Construction Industry) to minimize the construction noise impacts, construction noise levels at the representative NSRs will fully comply with the relevant noise criteria.

Ecology

13.3.4.    The potential ecological impact from the proposed drainage improvement project at Yuen Long has been evaluated in accordance with the applicable Technical Memorandum of the EIAO.  The project will cover four village areas, namely Sung Shan New Village, Tai Wo, Lin Fa Tei and Ha Che, and a total no. of 14 habitat types and 33 species of local or global conservation concern has been delineated and identified within the 500m Study Area of each work site. Because most of the work site is adjacent to populated village and hence bordered by man-made or heavily disturbed habitats, only a few natural or semi-natural habitats and species of conservation concern will be directly or indirectly affected by the project, including the riverine habitats, one protected plant species (Aquilaria sinensis), as well as two species of endemic freshwater crab which has been categorised as “endangered” (Somanniathelphusa zanklon) and “vulnerable” to extinction (Cryptopotamon anacoluthon) by the IUCN.  The drainage improvement work which involve widening and deepening of the existing watercourses in Ha Che and Lin Fa Tei will unavoidably destroy their habitat and potentially affect the local population of this two species in the Kam Tin area, at least on a temporal basis during the construction period.

13.3.5.    A range of mitigation measures related to good site management and construction practice, as well as scheduling of the staged work program have been recommended to avoid or minimize the ecological impact to the valuable ecological resources within or in the vicinity of the work areas. Translocation of the two endemic crab species to area protected from anthropogenic disturbance or development pressure within the Kam Tin Valley has been recommended before the commencement of the construction work. Implementation principle and guidelines has been suggested in this assessment and the detail processes including any monitoring requirement will be detailed in a “Freshwater Crab Translocation Plan” to be prepared by an Ecologist for AFCD approval.

13.3.6.    Furthermore, the reinstatement of the widened channels has provided an opportunity to restore the ecological functions provided by the disturbed riverine habitat, and a range of hardscapes and greening approach have been suggested to enhance the ecological quality of the restored habitat, including those suitable for the recolonization of the two endemic crab species.  A HCMP collaborated by an engineer, ecologist and landscape architect has been recommended to detail the restoration process and monitoring strategy of the reinstate riverine habitat.

13.3.7.    Nevertheless, it should be noted that the widened channels are open habitat and its riparian zone and the flora and fauna that could be established or colonised within the work site is subject to the habitat quality of the adjacent areas including the water quality in the watercourse upstream and downstream of the widened channels, and the potential anthropogenic disturbance nearby.  Accordingly, the effectiveness of the habitat restoration should be evaluated on the spectrum and breadth of the ecological functions performed by the restored habitat.

13.3.8.    Finally, with the implementation of the mitigation measures recommended in this assessment, no significant residual ecological impact would be envisaged from the project.  Moreover, the permanent changes in the hydrological characteristics of the watercourses including the newly formed meander or narrowed water channel, as well as the community structure of the riparian vegetation, would have an influential effect on the aquatic faunal assemblage in the project’s watercourse, and this changes of the riverine habitat at Sung Shan New Village, Lin Fa Tei and Ha Che, would be residual to the project.

Water Quality

13.3.9.    Key issues in terms of water quality would be related to excavation works for the construction phase of the proposed drainage improvement works. To minimize potential impacts on water quality during the channel construction, the excavation would be carried out in dry condition (even in wet season) by diverting the stream flow from upstream by a temporary drainage channel with a temporary sheet piles, earth bund or barrier, so that the works area will remain dry for later excavation and widening works.

13.3.10.  With implementation of recommended appropriate mitigation measures, the construction works for the proposed drainage improvement works would not be anticipated to result in unacceptable impacts on water quality.

13.3.11.  Water quality monitoring and audit should be carried out to detect any deterioration of water quality during the construction phase

13.3.12.  During operation of the Project, the drainage improvement works would not produce extra point sources or non-point source pollution loading. The new alignments of the drainage would provide widened sections to alleviate flooding during heavy rainfalls.

13.3.13.  In order to avoid adverse pollution from first flush during rainstorm, regular maintenance debris clearances are recommended, perfectly before rainstorm events. Maintenance desilting may be necessary for the proposed channel to remove excessive silts, vegetation, debris and obstruction. Desilting should be carried out during period of low flow.

Waste Management

13.3.14.  The construction activities associated with the proposed works will mainly generate a variety of wastes including C&D materials, chemical waste and general refuse. With the implementation of good site practice and recommended mitigation measures, there would be no adverse environmental impacts.

Land Contamination

13.3.15.  According to review in historical land use, relevant spillage accident records of EPD and FSD and site appraisal, all identified potentially contaminated sites were located outside works area boundary and no sign of migration of contaminant was observed. Therefore, contamination potential arising from the Project works is not anticipated. Further site investigation for this Project is considered not necessary

Landscape & Visual

13.3.16.  The proposed drainage works at the locations studied will see some change in the landscape and visual amenity of the project sites, although since the works generally involve upgrading of existing channels rather than constructing totally new drainage elements within the landscape the assessed impacts are referenced to this existing context.

13.3.17.  The design of the drainage proposals have sought to be as sensitive as possible, given the functional requirements, to the existing landscape setting. The landscape and visual mitigation proposals are centred on the use of natural watercourse bedding in wider channels in coordination with channel and embankment greening as well as the provision of tree and shrub planting along the channel edges to integrate with groups of retained trees to form a narrow landscape buffer. Since the development proposals are low in height this planting will screen low-level views (the majority of the existing VSRs are low-level) and integrate the proposals within the existing landscape framework.

13.3.18.  Given the proposed design of the proposals, the likely impacts on landscape resources and Landscape Character areas during the design year (Year 10) will range from slight adverse to insubstantial. Although the visual impact assessment suggest a slight /moderate adverse impact at year 10 for one VSR (VSR-9 at Lin Fa Tei) the majority are within the range Slight to Insubstantial. However, owing to the rural nature of the existing setting, the more significant impacts to views are only available to a relatively few people. It should also be noted that the works are an opportunity to make visual improvements and that slight and slight / moderate beneficial impacts are also predicted at locations where aesthetic treatments to structures and the introduction of greenery to areas currently lacking managed vegetation can provide improvements to the visual resources in the longer term.

13.3.19.  In accordance with the criteria and guidelines for evaluating and assessing impacts as state in Annex 10, Clause 1.1(c) of the EIAO-TM, overall, it is considered that the residual landscape and visual impacts of the proposed works are acceptable with mitigation at all four villages during the construction and operation phases.

Cultural Heritage

13.3.20.  The proposed drainage works are generally not expected to impact on archaeology during the construction and operational phases with the exception of an identified area within Lin Fa Tei Site of Archaeological Interest near the previous findings of wooden archaeological remains.  It is recommended that an archaeological survey be undertaken for proposed intercept drain works near the previous findings (area marked on Figure 10.16) prior to the construction phase by a qualified archaeologist who obtains a licence under the Antiquities and Monuments Ordinance (Cap. 53).   Methodology and scope is to be agreed with AMO prior to implementation.

13.3.21.  Furthermore, and as a precautionary measure, the Antiquities and Monuments Office (AMO) should be informed immediately in case of discovery of antiquities or supposed antiquities in the course of excavation for any of the proposed drainage improvement works at Tai Wo Project Area, Ha Che River Project Area, Lin Fa Tei Project Area (outside the area identified for archaeological survey) and Sung Shan New Village Project Area, so that appropriate action if needed can be timely formulated and implemented in agreement with AMO.

13.3.22.  Three graded historic buildings are located in proximity of the proposed works, while Lan Fong Study Hall in Chuk Hang and St. John’s Chapel in Cheung Po lie at a sufficient distance, Lee Tat Bridge in Shui Tsan Tin requires mitigation.