13. Environmental Outcome and Conclusions
13.1 Summary of Mitigation Measures Proposed
13.2 Key Environmental Outcomes
13.3 Overall Conclusion
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.
13.2.1. 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.
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.