12. conclusion
12.1 Introduction
12.2 Air Quality Impact
12.3 Noise Impact
12.4 Water Quality Impact
12.5 Waste Management
12.6 Ecological
12.7 Landscape and Visual Impact
12.8 Cultural Heritage
12.9 Environmental Monitoring and Audit (EM&A)
12.10 Overall Conclusion
Appendices
Appendix 12.1 Summary of Environmental Impact Associated with the Project
Appendix 12.2 Key Assessment
Assumptions and Limitations of Assessment Methodologies
12.
conclusion
12.1
Introduction
12.1.1
This Environmental Impact Assessment
(EIA) Report has been prepared for the proposed Drainage Improvement Works in
Mui Wo (the Project) in accordance with the requirements set out in the EIA
Study Brief (ESB-334/2020) and the Technical Memorandum on EIA Process
(EIAO-TM). Aspects that have been considered in this EIA Report include:
·
Air Quality;
·
Noise;
·
Water Quality;
·
Waste Management;
·
Ecology;
·
Cultural Heritage; and
·
Landscape and Visual.
12.1.2
A summary of environmental impacts
identified in this EIA is provided in Appendix 12.1. The conclusion of the technical chapters of this EIA is
described in the following sections.
12.1.3
The key assessment assumptions,
limitation of assessment methodologies and related prior agreements with EPD /
other authorities on assessment of different environmental aspects are given in
Appendix 12.2.
12.2
Air Quality Impact
12.2.1
During construction phase of the
Project, potential air quality impact from fugitive dust may arise from
excavation works and stockpiling of excavated material and piling works.
Potential air quality impact may also arise from the gaseous emission due to
the use of PMEs. Odour impact may also arise from the
excavation of river sediment However, adverse air quality impacts due to
fugitive dust, gaseous emission from PMEs and odour
impact arise from excavation of river sediment during the construction phase are not expected with the implementation of recommended
mitigation measures.
12.2.2
During operation phase of the
Project, regular maintenance desilting and debris clearance will be necessary.
Adverse air quality impacts due to fugitive dust gaseous emission from PMEs and
odour impact arise from maintenance works are not
anticipated with the implementation of recommended mitigation measures.
12.2.3
Site inspections and audits during construction
phase of the Project to ensure proper implementation of the mitigation measures
are recommended. Air quality monitoring is considered not necessary during the
construction and operation phases of the Project.
12.3
Noise Impact
12.3.1
Owing to the close proximity of some
of the NSRs to the works area of the Project, mitigation measures are required
to be implemented to mitigate the construction noise impacts. Practicable
mitigation measures, including good construction site practices, use of quiet
construction method/PME, temporary noise barriers / noise enclosures,
scheduling of PME / construction activities to avoid work during sensitive time
(e.g., school examination period) and reduce the concurrent operation of PMEs
are recommended. With the implementation of the recommended mitigation
measures, the mitigated construction noise levels at all representative NSRs
will comply with the daytime construction noise criteria throughout the
construction period. Noise monitoring during the construction stage is
recommended to ensure compliance with the relevant noise criteria.
12.3.2
No adverse noise impact is
anticipated during operation phase after implementation of noise mitigation
measures, such as acoustic lovers, and proper design of the proposed stormwater
pumping station. A commissioning test should be conducted prior to operation of
the Project to ensure compliance of the operation noise levels with the
stipulated noise standard.
12.4
Water Quality Impact
12.4.1
Potential water quality impact from
construction surface runoff, wastewater and sediment release from works into
water bodies, construction works within river channel and sewage from workforce
have been assessed. With the implementation of mitigation measures (in
particular to carry out excavation works for the Project in a confined and dry
condition) and proper good site practice proposed, no
adverse water quality impact is anticipated during the construction phase of
the Project.
12.4.2
The potential water quality impacts
arising associated with maintenance works of the drainage channels and change
in flow regime have been assessed. Regular maintenance works will be
undertaken in dry condition in confined areas. Unacceptable water quality
impacts are not expected with appropriate preventive and mitigation measures
proposed.
12.4.3
The proposed drainage improvement
works is effective in stormwater diversion. The flow across the different
channels will remain mostly unchanged under normal circumstances and thus
limited change in flow regime would be expected from Project operation.
Since there will be no new pollution source under this Project, there will be
no unacceptable adverse change in water quality. Sedimentation/ erosion
pattern is not expected to be significantly affected given the limited change
in flow regime, and any excessive accumulation in the affected rivers after
heavy rainstorm will be handled by DSD staff. Appropriate preventive and
mitigation measures such as real time monitoring of water quality are
recommended to minimise the potential water quality
impact from the proposed drainage improvement works. No unacceptable
water quality impact from the proposed drainage improvement works has been
predicted.
12.5
Waste Management
12.5.1
With the implementation of good site
practices, adverse environmental impact (potential air and odour
emissions, noise and wastewater discharge) arising from the management and
disposal of waste during the construction and operation phases of the Project
are not anticipated.
12.5.2
It is recommended that regular site
inspections of the waste management practices would be carried out during the
construction phase to determine if wastes are being managed in accordance with
the recommended good site practices and Waste Management Plan. The site
inspections will investigate all aspects of waste management including waste
generation, storage, handling, recycling, transportation and disposal.
12.6
Ecological
12.6.1
The ecological impact assessment has
been carried out based on literature reviews and the focused field surveys of
twelve months covering both wet and dry seasons completed in 2022. According to
the Project alignment, the Project will cause potential temporary and permanent
habitat loss to marsh (~0.7ha; including ~0.5ha temporary works area),
semi-natural watercourse (~0.7km; including ~0.7km temporary works area), channelised watercourses (~0.4km; including ~0.4km
temporary works area), agricultural land (~1.1ha; including ~0.8ha of temporary
works area) and village/developed area (~0.5ha; including ~0.5ha temporary
works area).
12.6.2
Majority of the identified impacts
are considered to be low in the absence of mitigation measures. However, the
potential impact on direct loss (i.e., permanent and temporary losses) of
marsh, watercourses and agricultural land, ecological impact on fauna species
of conservation importance, and ecological impact to watercourses due to river reprofiling,
temporary stream diversion and the associated change in water flow/ level are
considered as low to moderate. Necessary mitigation measures and
ecological monitoring programme were proposed for the
above potential impacts.
12.6.3
It is predicted that the impacts
will mainly arise during the construction phase, as no major activities would
be conducted during the operation phase. The routine maintenance and the
operation of the completed drainage channel and pumping station would not cause
any significant ecological impact. Good site practice and mitigation measures
are recommended to minimise potential impacts
resulting from operational phase activities.
12.6.4
With the implementation of
mitigation measures and precautionary measures, no adverse residual ecological
impacts from the Project within and in the vicinity of the works area during
construction and operation phases would be anticipated. Off-site mitigation
measures are therefore not considered necessary to mitigate the residual
impacts any further.
12.7
Landscape and Visual Impact
12.7.1
Residual landscape impacts are slight
on LCA3 (Rural Inland Plains of Mui Wo and Surrounding Villages), LR5
(Agricultural Land) and LR9 (Semi Natural Water Course) during construction and
Operation at Day 1, and insignificant on all other LRs and LCAs with proper implement of the
recommended mitigation measures.
12.7.2
Residual visual impacts on VSRs are slight
to insignificant during construction and Operation at Day 1 with proper
implement of the recommended mitigation measures.
12.7.3
Approximately 87 nos. of trees will be
affected and proposed to be felled by this Project, but these will be
adequately compensated for with compensatory planting of not less than 1:1
ratio within the Works Area. Therefore, the estimated nos. of compensatory tree
planting will be 87 nos. subjected to the detail design.
12.7.4
By operation, construction equipment
will have been removed and earthworks completed. Therefore, with sensitive
architectural design of the structures, tree planting and careful design of
lighting, residual visual impacts would further reduce landscape and visual
impact at Day 1 of operation. The new structures are expected to blend into the
surrounding environment, with denser vegetation at Year 10 of operation. The
residual impact on LCAs, LRs and VSRs will become slight
to insignificant during Operation at Year 10.
12.7.5
According to Annex 10 of the
EIAO-TM, following the introduction of landscape and visual mitigation
measures, the Landscape and Visual Impacts of this Project, are considered
acceptable with mitigation measures.
12.8
Cultural Heritage
12.8.1
Chung Hau
SAI is found within the CHAA, at a distance of about 20m within the works area
of the Project. No excavation works of the project will exist in or adjacent to
the SAI, therefore no adverse archaeological impact due to the proposed
development is anticipated and thus, no mitigation measure is required.
12.8.2
No archaeological potential area has
been identified within the works area. No archaeological impact is anticipated
and thus no mitigation measures is required.
12.8.3
As a precautionary measure, the
project proponent and his/her contractor are required to inform AMO immediately
when any antiquities or supposed antiquities under the A&M Ordinance (Cap.
53) are discovered during the course of works.
12.8.4
Desktop review supplemented by built
heritage survey identified no declared or proposed monuments and Government
historic sites identified by AMO in the CHAA. No impact to these items is
anticipated and thus no mitigation measures is required for these items.
12.8.5
Seven (7) graded historic
sites/buildings/structures identified in the CHAA are located over 70m from the
Project Boundary. Due to adequate separate distance between the proposed works
and graded historic sites/buildings/structures, no impact is anticipated.
However, special attention should be paid to avoid adverse physical impact
arising from the proposed works to them. Design proposal, method of works and
choice of machinery should be targeted to minimize adverse impacts to
them. Any vibration and building movement induced from the proposed works
should be strictly monitored to ensure no disturbance and physical damages made
to them during the course of works. Monitoring proposal for them, including
checkpoint locations, installation details, response actions for each of the
Alert/ Alarm/ Action (3As) levels and frequency of monitoring should be
submitted for AMO's consideration.
12.8.6
Potential direct impact to the built
heritage items identified and listed in Table 9.2 except HB-22 and HB-76 (two
agricultural weirs) is not anticipated due to adequate separate distance
between the proposed works and the built heritage items.
12.8.7
Two agricultural weirs, HB- 22 and
HB-76, are located within works area of the river reprofiling work and proposed
fish ladder works in Tai Tei Tong River. Modification
of the agricultural weirs and construction of fish ladder are proposed on site
in order to achieve beneficial ecological impact like improvement of the river
hydraulic performance and fish movement. The agricultural weirs (HB-22 and
HB-76) are constructed with concrete and have already undergone various
modification and repair works. For instance, HB-22 was modified with wide steps
at downstream in 1960s and a further modification in 1970s; while HB-76
underwent significant modification in the early of 1990s, only two concrete
block and floor steps remained on site. Hence, their cultural heritage
significance is relatively low due to high level of modifications underwent.
Therefore, although the modification of the agricultural weir and construction
of fish ladder of this project will bring direct impact to the weirs, the
impact would be acceptable with mitigation measures. It is recommended that
cartographic and photographic records be conducted to record the weirs prior to
commencement of modification works.
12.8.8
The operational phase of the Project
involves no excavation works, no cultural heritage impact is anticipated and
thus, no mitigation measure is required.
12.9
Environmental Monitoring and Audit (EM&A)
12.9.1
An EM&A programme
has been developed to ascertain and verify the assumptions implicit to, and
accuracy of, EIA study predictions. EM&A requirements have been
recommended, where necessary, to check on project compliance of environmental
legislation and standards. These are presented in a separate stand-alone
EM&A manual.
12.10
Overall Conclusion
12.10.1 The EIA has
identified and assessed the potential environmental impacts during the
construction and operation of the Project in accordance with the requirements
set out in the EIA Study Brief (ESB-334/2020) and EIAO-TM. The
EIA has concluded that with the implementation of the recommended mitigation
measures, no unacceptable environmental impacts are envisaged as a result of
the construction and operation of the Project.
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