1.1.1
In the Policy Address 2015, the
Government set out the intention to adopt the concept of revitalising water bodies in
large-scale drainage improvement works and planning drainage networks for the
new development areas. The concept of revitalising water bodies is aimed at promoting greening,
biodiversity, beautification and water friendliness in addition to achieving
efficient drainage, with a view to building sustainable drainage facilities and
providing a better living environment.
1.1.2
Fo Tan Nullah (FTN) and Tai Wai Nullah (TWN) were
identified as waterbodies of high revitalisation
potential and therefore were recommended for detailed investigation and
proposing revitalisation schemes for implementation,
taken into account its unique features and constraints in the feasibility study
on “Study on Revitalisation of Water Bodies” (“the
Study”) under Agreement No. CE 28/2015 (DS) commissioned by Drainage Services
Department (DSD) in December 2015.
1.1.3
In April 2020, AECOM Asia
Company Limited was commissioned by DSD to undertake Agreement
No. CE54/2019 (DS) – “Revitalisation of Tai
Wai Nullah and Fo Tan Nullah – Investigation” (hereafter referred to as
“the Assignment”) to revitalise the existing TWN and
FTN with an aim to enhance their ecological value, provide a greener
environment, promote water friendliness and improve the community
environment. The Assignment also
includes provision of dry weather flow interceptors to improve the water
quality. As part of the Assignment, an
Environmental Impact Assessment (EIA) study under the Environmental Impact
Assessment Ordinance (EIAO) is required for the proposed works to TWN and FTN,
respectively.
1.1.4
This EIA Report covers the EIA
study for Revitalisation of TWN (hereafter referred
to as “the Project”).
1.1.5
The proposed revitalisation of TWN is classified as designated project
(DP) by virtue of Item I.1(b)(ii), Part I, Schedule 2 of the EIAO – “a drainage
channel or river training and diversion works which discharges or discharge
into an area which is less than 300 m from the nearest boundary of an existing
or planned site of cultural heritage”.
1.1.6
Project Profile for Revitalisation of TWN (No. PP-586/2019) was submitted to
the Environmental Protection Department (EPD) on 31 July 2019 for application
for an EIA study brief under section 5(1)(a) of the EIAO. The EIA Study Brief for the Revitalisation of TWN (No. ESB-320/2019) was issued on 11
September 2019 under the EIAO.
1.2
Purpose of this Executive Summary
1.2.1
This Executive Summary (ES) summarises the key findings, recommendations and conclusions of the EIA Report for the Project. The ES contains the following information:
Ÿ
Section 2 presents purpose and nature of the
Project, consideration of alternative options and construction methods for the
Project;
Ÿ
Section 3 presents the key findings of the
environmental impact assessment;
Ÿ
Section 4 describes the proposed environmental
monitoring and audit programme for the Project; and
Ÿ
Section 5 presents the conclusions.
2.1
Purpose and Scope of Project
2.1.1
The purposes and objectives of
the Project are to revitalise the existing TWN
with the aim of enhancing the ecological value of TWN, providing a greener environment, promoting water
friendliness and improving the community environment. The Project also includes provision of dry
weather flow interceptors to improve the water quality. Location plan and general layout of the
Project are shown in Figure 2.1 and Figure 2.2 respectively.
2.1.2
The Project comprises the
following key components:
(a)
beautification of the existing nullah
(approximately 2
km long and 40 m wide) by re-surfacing, greening and modification of channel
bed;
(b)
provision of approximately 3 km
walkways along the nullah and associated stairs and access ramps ;
(c)
provision
of a Dry Weather Flow Interceptor
(DWFI) system;
(d)
provision of features for ecological
enhancement and sustainable drainage system, and two underground
water pumps installed near
mid-stream of TWN
and underground water pipes for associated water retention and supplement;
(e)
construction of viewing decks and revamp
of existing foorbridges/ bridges;
(f)
revamp/provision of footpaths, railings,
pavilions, amenity
areas and public open spaces
along the nullah and on the nullah bed, as well as the
associated UV disinfection system for water play features;
(g)
improvement / modification
of existing planters; and
(h)
associated works including landscaping,
utility works, etc.
2.1.3
Subsequent
to the issue of the EIA Study Brief (No. ESB-320/2019), underground water pumps installed near
mid-stream of TWN (beneath Shing Mun Tunnel Road by the bankside) and
underground water pipes (mainly housed within the DWFI system) have been
proposed to support the provision of ecological enhancement features in the
nullah in view of the insufficient baseflow in TWN. Under the latest revitalisation design, an UV
disinfection system has also been proposed for water play features to be
provided in riparian amenity areas (fully separated from waterbody of TWN) to
promote water friendliness. Furthermore,
the Project boundary has been altered to cover modification of channel bed and
bank downstream of TWN’s broad-crested weir at its confluence with Shing Mun
River near Man Lai Court, with an aim to reduce the existing excessive
accumulation of silts brought by tidal influence due to unfavourable surface /
gradient of the existing channel (i.e. flat and uneven nullah bed in front of
the broad-crested weir); the areas near the cul-de-sac of Heung Fan Liu Road
due to construction site constrain; and mid-stream near Shing Mun Tunnel Road
for overall planning of the mid-stream riparian public open space. In accordance with Clause 6.2 of the EIA
Study Brief, confirmation had been sought in writing that the scope of issues
could still be covered by EIA Study Brief and hence no fresh EIA Study Brief
would be required.
2.1.5
The operation of the two
proposed underground water pumps near mid-stream of TWN southeast to Pok Ngar
Villa (one duty and one standby) will be controlled by a level detector
installed at the modified stilling basin (to be deepened and expanded) at
upstream of TWN. Water flowing from the
low flow channel will be collected in a wet well by gravity through a screened
inlet pipe installed at the low flow channel.
The water will then be pumped upstream to the modified stilling basin
through pressurised underground pipes. The on-duty pump will not operate during
night-time (i.e. 2300 – 0700 hours). The
stored water in the basin will be naturally discharged for recharging
environmental flow in the nullah.
2.2
Need and Benefits of the Project
Water Quality Improvement and Promotion of
Water Friendliness
2.2.2
After the revitalisation
works, similar to the existing condition, the nullah bed of the engineering
channel of TWN would be dry most of the time during non-rainy days, except for
the low flow channel in the middle.
While the main water body of TWN, i.e. the low flow channel, is not
suitable to be opened up for public access / physical contact due to safety
reasons, the improvement of water quality and riverside environment of the
nullah due to the Project would enhance user experience and hence promoting
water friendliness culture. In order to
allow public to better enjoy the view of the revitalised waterscape and
ecological enhancement features (e.g. treatment wetland), construction /
modification of footbridges / walkways and public open spaces is proposed along
the nullah. The
riparian areas (nullah bed of the engineering channel of TWN outside of the low
flow channel) of midstream TWN near Pok Ngar Villa would also be opened for
public access and be transformed into a public open space with accesses with
stepped seats, riparian walkways and other community
amenities [including water play features (fully separated from the water body
of TWN)] to promote water-friendliness. Associated visitor’s facilities, including toilet and management office, would also
be provided for the proposed riparian public open space.
Greening
Enhancement
2.2.5
The existing
concrete nullah of TWN will be resurfaced with layer of vegetation, which will
enhance both the aesthetic and ecological values of TWN. Greening of the nullah and along its
banksides, such as provision of emergent wetland planting (e.g. reed and other
aquatic herbs), mangroves, climbing plants, tree and / or grasscrete
etc, will be provided. The existing
mature trees growing by the bankside along the nullah will be retained, and
additional tree planting will be provided along the nullah. The existing planters will also be modified
to beautify the footpath along TWN.
Ecological Enhancement
·
Reprofiling of the low flow
channel and construction of in-stream weirs to create a meandering alignment
along the nullah to mimic natural stream pattern where practicable, providing a
series of microhabitats for wildlife in surrounding areas;
·
Provision of DWFI system to improve water
quality and hence support ecological enhancement;
·
Greening of the nullah and along
its banksides, such as provision of emergent wetland planting (e.g. reed and other aquatic herbs), mangroves,
climbing plants, tree and / or grasscrete;
·
Incorporation of planting designed to attract wildlife species (e.g. native host plant species for butterflies) during revamp of public
open space along TWN;
·
Provision of nest boxes / hunting perch for wildlife (e.g. birds) along
TWN; and
·
Modification of channel bank
and existing vehicular access at downstream section of TWN into a mix of
stepped terrace and slope at water edge to enhance foraging / pre-roost
habitats for waterbirds (e.g. ardeids).
2.3
Consideration of
Design and Layout
2.3.1
Environmental implications
of various options in regard to the extent of DWFI system, water retention and
replenish methods and ecological enhancement designs, and minimisation of
siltation at downstream of TWN have been considered with a view to optimising
the revitalisation design of TWN in order to enhance the ecological value of
the nullah, provide a greener environment, promote water friendliness and
improve the community environment whilst avoiding, minimising and mitigating
any potential adverse environmental impacts of the Project.
Extent
of DWFI System
2.3.2
Drainage outlets with polluted
discharges were identified between Sections 1 to 5 of TWN (i.e. the majority of downstream portion of
TWN, see Figure 2.2 for details of the divided sections) through the pollution source identification survey. For the preferred extent of DWFI system, a
DWFI system with interception of the highly polluted
discharges and provision of
treatment wetland for polishing the remaining non-intercepted polluted
discharges is considered to be able to fully eliminate or polish the existing polluted
discharges to TWN and would improve the water quality and resolve the odour problem of TWN.
With the adoption of treatment wetland at
selected drainage outlets, it could also minimise the
addition of pollutant loads to the existing sewerage system and enhance the
ecological values of TWN by providing additional wetland habitats for wildlife,
hence it is selected as the preferred option.
Section 6 of TWN (i.e. the upstream portion of TWN, see Figure 2.2 for details) is
connected to WSD’s facilities that expedient connection/misconnection from industrial area or
significant polluted surface runoff due to the nature of the catchment area
would be unlikely for this section. Likewise, part of
Section 1 (south to Tsuen Nam Road) is also subject
to tidal influence with the outlets being submerged mostly in
water that the discharges cannot be intercepted by the instream DWFI
system. DWFI system is hence
not considered necessary
for the part of Section 1 (south to Tsuen Nam Road) and Section 6 of the nullah.
Water Retention and
Replenish Methods and Ecological Enhancement Designs
2.3.4
In-stream fixed weirs, which would not be washed away
in case of flood discharge, would be incorporated in
the nullah bed to retain water depth for aquatic habitats. By impounding floodwater or environmental
flows, weirs are particularly useful in the dry channels to retain water for a
longer period, which could promote plant growth and aquatic species survival in
such an otherwise dry environment.
Minimisation of Siltation in Downstream Tai Wai Nullah
2.3.6
Apart from
the environmental nuisance caused by polluted discharges from drainage outlets
along the nullah, excessive accumulation of silts brought by tidal influence
due to uneven surface
and flat gradient in front of the broad-crested weir at downstream
TWN near its confluence with Shing Mun River near Man Lai Court was observed to
cause environmental nuisance to nearby residents. In order to tackle this existing issue,
modification of channel bed downstream of TWN’s broad-crested weir has been
incorporated into the revitalisation design to minimise the deposition of
excessive silt and resolve the associated environmental nuisance.
2.3.7
Part of the existing concrete
vehicular access at the nullah bank would be reconstructed into a mix of
stepped terrace and slope with greenings (e.g. planter, grasscrete)
at water edge to create foraging / pre-roost habitats for waterbirds (e.g.
ardeids) and to enhance greening, whilst maintaining the necessary emergency access function
of the existing vehicular track.
2.4.1
The Project site will be
divided into six sections to be constructed in sequence starting
from downstream TWN (Figure 2.2 refers). The construction works along the nullah
within each section would last for approximately 1 year and will not be
undertaken at the entire section at the same time to avoid multiple
construction activities overlapping / concentrating in a certain area over any
period.
2.4.4
The major
parts of the DWFI system are u-channel and pipe system cast-in with the
concrete blocks at nullah wall for stabilisation. Taking the inconsistent shapes and sizes of
nullah wall / drainage outlets and limited accessibility to the nullah bed into
consideration, the more flexible construction method of in-situ construction of
DWFI system is considered more suitable and practical than the off-site
pre-cast construction. Hence, it is
adopted to avoid prolonged construction duration and repeated construction
activities from trial installations or on-site adjustment of pre-cast concrete
mass to reduce potential disturbance/nuisance to the environment and local
residents.
2.6
Concurrent Projects
2.6.1
The potential cumulative
environmental impacts during construction and/ or operational phase from the
below interfacing projects within 500 m from the Project boundary and the
designated project "Revitalisation of Fo Tan Nullah" which is under the same Assignment that
involves construction works within or near Shing Mun River and its tributaries have been reviewed.
·
Revised Trunk Road T4 in Sha Tin;
·
Proposed box culverts in Chui Tin Street under Drainage Improvement
Works in Sha Tin and Sai Kung; and
·
Proposed
joint-user complex at Tsuen Nam Road, Tai Wai.
2.6.2
No adverse cumulative
environmental impacts from the above potentially interfacing projects were
predicted during the construction and operational phases of the Project. Nonetheless, it is recommended that during
the detailed design stage, the contractor of this Project should be requested
to closely liaise with the contractors of these potential concurrent projects
in planning the interfacing works properly to avoid/ minimise
repeated and concurrent construction works as far as practicable to further minimise any potential cumulative impacts and to enhance
overall environmental performance of the Project.
2.7.1
Consultation exercise carried
out include:
·
Meeting with Sha Tin District Council in June and July 2018, March 2021
·
Meeting with Mei
Lam Estate in August 2018;
·
Meeting with Sha Tin District Council Health and Environmental
Committee in March 2019;
·
Meeting with Green Groups in July 2020 and July
2022;
·
A series of public engagement exercises (e.g. interviews, workshops and
surveys) through the use of Design Thinking Approach between December 2020 to
August 2021.
2.7.2
During the public inspection period of the Project Profile submitted
for the Application of EIA Study Brief (No. PP-586/2019) in 2019, comments received were largely in favour
of the Project, in particular, the proposed DWFI system and ecological
enhancement are considered to be beneficial to the community. Members of the Sha Tin District Council,
general public and green groups are supportive of the Project.
2.7.1
Their
following key concerns and comments on the Project have been incorporated into
the design of the Project:
Ÿ
Water quality issues and odour nuisance;
Ÿ
Promotion of water friendliness, access to
nullah and public safety;
Ÿ
Insufficient baseflow to support proposed
ecological enhancement; and
Ÿ
Avoidance and minimisation of impacts to
roosting ardeids.
3
Key Findings of the environmental impact
Assessment
3.1
Air Quality Impact
3.1.1
Potential air quality impacts
associated with the construction and operational phases of the Project have
been assessed in accordance with the criteria and guidelines as stated in the
requirements given in Section 3.4.4 and Appendix B of the EIA Study Brief, as
well as Annexes 4 and 12 of EIAO-TM. The
assessment area for air quality impact assessment is defined by a distance of
500m from the Project boundary of the Project.
3.2
Noise
Impact
3.2.1
Potential noise impacts
associated with the construction and operational phases of the Project have
been assessed in accordance with the criteria and guidelines as stated in the
requirements given in Section 3.4.5 and Appendix C of the EIA Study Brief, as
well as Annexes 5 and 13 of the EIAO-TM.
The assessment area for noise impact assessment is defined by a distance
of 300m from the Project boundary of the Project.
3.2.2
Construction noise is expected
from the use of powered mechanical equipment (PME) during various construction
activities. No marine transportation of
construction materials and waste is required.
Noise impact arising from construction activities of the Project has
been assessed. With
proper implementation of the proposed mitigation measures, including
adoption of good site practices, use of quality PME / quieter
construction method including
use of road ripper for concrete breaking, silent piling by press-in method and use of hydraulic crusher for demolition
of footbridge, adoption of movable noise barriers/ noise insulation fabric/ noise
enclosure and proper
scheduling construction activities during examination period of schools (including TWGHs
Tsoi Wing Sing Primary School, Buddhist Wong Wan Tin College and TWGHs Sin Chu
Wan Primary School), the mitigated cumulative
construction noise levels from the Project and nearby concurrent project at all
representative noise sensitive receivers (NSRs) in the vicinity of the Project
work site would range from 63 to 75 dB(A), complying with the relevant noise criteria set out in
the EIAO-TM.
A construction noise management plan (CNMP), which to verify the
inventory of noise sources, and to assess the effectiveness and practicality of
all identified measures for mitigating the construction noise impact of the
Project, would be prepared before commencement of construction works. Noise monitoring is recommended as part of
the environmental monitoring and audit (EM&A) programme
for the construction phase of the Project to check compliance with the daytime
construction noise criteria. Weekly site
audit is also recommended to audit the proper implementation of the recommended
mitigation measures for daytime construction activities as part of the EM&A
programme.
3.3
Water Quality Impact
3.3.4
Upon
completion of revitalisation for TWN, water quality of TWN is anticipated to be
improved with the implementation of the proposed DWFI system and treatment
wetlands. A post-revitalisation water
quality monitoring programme, covering the water quality of the revitalised TWN
and the disinfected water for the proposed water play features, would be
established and implemented by the DSD, with an aim to assess the compliance
with the Water Quality Goals (WQGs) stipulated in DSD PN No. 3/2021 -
Guidelines on Design for Revitalisation of River Channel; to monitor long-term
water quality trend; to facilitate the emergency response plans for failing to
achieve WQGs; and to facilitate the development and implementation of operation
and maintenance plan. Maintenance and management requirements for TWN
would be adjusted accordingly based on the monitoring results following the
operation and maintenance considerations / guidelines stipulated in DSD PN No.
3/2021.
3.4
Waste Management Implications
3.4.1
The waste impact assessment was conducted in accordance with the criteria and
guidelines as stated in the requirements given in Section 3.4.7 and Appendix E
of the EIA Study Brief, as well as Annexes 7 and 15 of the EIAO-TM.
3.4.2
Construction and Demolition
(C&D) materials will be generated from channel bed modification,
improvement of existing walkways and riparian public open space, landscaping
and miscellaneous works, construction of DWFI system and mid-stream underground
water pumping facilities for ecological enhancement-associated water retention
and supplement. Based on the latest
layout, it is estimated that approximately 120,000 m³ of inert C&D
materials and 2,000 m³ of non-inert C&D materials would be generated.
3.4.3
Inert
C&D materials from the above construction works will be sorted and reused
as fill material as much as possible. It
is estimated that that approximately 116,000 m³ of inert C&D materials
(mainly soil) could be reused on-site as backfill materials whilst
approximately 4,000 m³ of surplus inert C&D materials would be delivered to
public fill reception facility (PFRF) for beneficial reuse in other
projects. Non-inert C&D materials
will be recycled as far as possible before disposed to landfill. Opportunities in minimisation of generation
and maximisation of reuse of C&D materials would be continually
investigated during the detailed design and construction phases. With the implementation of the recommended
good site practices and waste management measures for the handling,
transportation and disposal of the identified waste arising, no adverse
environmental impacts would be anticipated.
3.4.5
The main waste types generated
from the operation of the Project would be silt, debris, screening and limited
amount of chemical waste from the routine maintenance of the DWFI system and
nullah as well as desilted materials from maintenance desilting works. With implementation of the relevant
legislative requirements and the recommended best waste management practices,
adverse environmental impacts (including potential hazard, air and odour emissions, noise and wastewater discharges) and
public transport impact would not be anticipated during operational phase. Provided that sufficient number of trash bins and recycling bins would be provided / retained for the collection of general
refuse generated by visitors along the revitalised
TWN, no unacceptable environmental impact and public transport impact would be
anticipated.
3.5
Land Contamination
3.5.1
The land contamination
assessment is conducted in accordance with the criteria and guidelines as
stated in the requirements given in Section 3.4.8 and Appendix F of the EIA
Study Brief, as well as Sections 3.1 and 3.2 of Annex 19 of the EIAO-TM.
3.5.2
Based on the site appraisal,
the Project area has been occupied by non-contaminating land uses and no
potentially contaminating activities were observed. No adverse land contamination impact arising
from the Project is therefore anticipated and mitigation measures are
considered not necessary. No further
site investigation works at the Project area is required.
3.6
Sewerage and Sewage Treatment Implications
3.6.1
The assessment on potential
sewerage and sewage treatment impacts on the downstream public sewerage, sewage
treatment and disposal facilities arising from the Project has been conducted
in accordance with the criteria and guidelines as stated in the requirements
given in Section 3.4.9 and Appendix G of the EIA Study Brief, as well as
Section 6.5 of Annex 14 of the EIAO-TM.
3.6.2
A DWFI system is proposed to
improve the water quality in the Tai Wai Nullah with intercepted dry weather
flow estimated to be at 2,850 m3/day. The sewerage impact assessment indicated that
existing sewerage system has sufficient capacity to take up the additional dry
weather flow intercepted by the DWFI system and
proposed toilet facility. Thus, no
mitigation measures are required. No
adverse sewerage impact arising from the Project is anticipated.
3.7
Ecological Impact
(Terrestrial and Marine)
3.7.2
A literature review and
ecological field surveys covering both dry and wet seasons between May 2020 and
January 2021 have been conducted. A total of nine habitat types were recorded
within the 500 m assessment area from recent surveys, including woodland, mixed
woodland, plantation, grassland, reservoir, village / orchard, developed area /
wasteland, natural watercourse and modified watercourse.
Dominant habitat types recorded within the Project site included developed
area and modified watercourse, which are of low ecological values, except for
limited sections of the TWN that supported some wetland vegetation and / or
pre-roosting congregation of ardeids and other wetland birds and are hence
considered of low to moderate ecological value.
3.7.3
For habitats outside the
Project site, woodland and mixed woodland are of moderate or moderate to high
ecological value; natural watercourse is of low to moderate ecological value
whilst other habitats (plantation, grassland, reservoir, village/ orchard,
developed area/ wasteland and modified watercourse) are considered of low ecological
value. Species of conservation
importance recorded within the assessment area included eight flora, twelve
avifauna, eight mammals, four herpetofauna, five butterflies, two odonates and two freshwater species. Among these species, only eight avifauna, two
mammal, four butterfly species of conservation importance were recorded within
the Project site.
3.7.4
Marine habitats within the
assessment area included subtidal hard substrata, soft bottom, and intertidal
habitats, which are all of low ecological value. As the Project site is located far from
marine habitats (>5.55 km), no direct impacts to marine habitats are
anticipated, and indirect impacts are considered negligible.
3.7.5
No direct
impacts to natural habitats within the assessment area are anticipated for the
Project. Direct impacts arising from the
proposed works would be limited to the temporary loss (about 11.1ha) of
modified watercourse and developed area.
Given the relatively low to moderate ecological value of affected
habitats, the small area affected, and the temporary nature of the impact,
direct impacts are expected to be Minor
except for minor-moderate scale impacts to two small stretches of the TWN
supporting some wetland vegetation and ardeid pre-roosting site. All affected areas will be reinstated and
enhanced in terms of ecological value as part of the Project. Avoidance measures (e.g. restriction of construction
hours, protection of mature trees along the nullah and avoidance of encroachment
of ardeids night roosting sites) would be implemented to preserve the day
roosting and night roosting habitats for bats and ardeids respectively. Floating platforms would be installed
downstream of the Project site in Shing Mun River Channel, during construction
phase, to compensate for temporary loss of the pre-roosting site.
3.7.6
Indirect
impacts during the construction phase would comprise of human disturbance,
construction noise, dust and site run-off.
With proper implementation of the recommended mitigation measures and
good site practices, no significant adverse ecological impact is
anticipated. With ecological enhancement
measures incorporated into the revitalisation design of TWN and with
restriction of public access in Section 1 (i.e. downstream of TWN), nature of
disturbance during operational phase would be minimal compared to existing
baseline condition. Net positive
ecological outcome would be resulted from the created and enhanced wetland
habitats. No unacceptable adverse
residual impacts would therefore be expected during both construction and
operational phases.
3.7.7
A pre-construction ardeid
survey for
areas within 100m from the Project site should be conducted to ascertain the status
and location of the ardeid night roost before the commencement of construction
works. Monthly monitoring of the area
within 100m from the Project boundary should be conducted during the
construction phase to check the status and location of any active ardeid
pre-roosting and night roosting site, as well as the ardeid’s usage of the
proposed temporary floating pontoons.
Remedial actions can then be recommended, where appropriate, based on
the impact monitoring results. Monthly site
audit should also be carried out throughout the construction phase to ensure
recommended measures are properly implemented.
No EM&A programme is required during
operational phase.
3.7.8
Ecological enhancement designs
have been incorporated into the revitalisation plan
to promote ecological value of the Project, as well as enhancement measures and
good site practices to further minimise any potential
environmental impacts. The proposed revitalisation plan for TWN should seek to find a balance
between design for local communities’ requirements (e.g. aesthetics,
recreation/leisure and access) and ecological enhancement. Ecological enhancement could be achieved by
incorporating habitat creation within and along the TWN to improve the overall
ecological value of the Project site.
The design should not result in disturbance impacts on surrounding
habitats and fauna utilising the nullah. Upon completion of revitalisation
for TWN, ecological value of the Project site is anticipated to be improved by
ecological enhancement measures incorporated into the design. A post-enhancement ecological monitoring programme would be developed and implemented by the DSD to
review effectiveness of these enhancement measures (e.g. creation of wetland
habitats, vegetation planting and specific enhancement measures for identified
species). The programme
shall aim to record the overall ecological condition of the Project site,
including but not limited to the followings: quality of the created habitats
and enhancement elements, usage by targeted fauna species and vegetation
conditions. Maintenance and management
requirements for TWN would be adjusted accordingly based on the monitoring
results.
3.8.1
Potential impacts on fisheries
have been assessed in accordance with Section 3.4.11 and Appendix I of the EIA
Study Brief as well as Annexes 9 and 17 of the EIAO-TM.
3.8.2
The Project would only involve
construction works within the Project area (existing TWN and developed area
alongside). No loss of fishing grounds and mariculture areas are anticipated
within the assessment area. With the implementation of the recommended water
pollution control measures, the Project is not anticipated to cause impacts to
fishing grounds and mariculture areas within the assessment area during both
construction and operational phases. Thus, no further mitigation measures and environmental
monitoring and audit programme specific to fisheries
impact are required.
3.9
Cultural Heritage
Impact
3.9.2
A Declared Monument, Old House,
Wong Uk Village, is located within 300m of the
discharge area from the revitalised TWN,
and located at about 1.8km from the nearest Project boundary. As the proposed works are mostly situated
within the TWN and there is substantial separation distance between the Old
House and the proposed works, no direct and indirect impacts on the Old House
would be anticipated during the construction and operation phases of the
Project.
3.9.3
Ten built
heritage resources are located within 300 m assessment area from the Project
site. Direct impacts from damages
through contacting with construction machineries and site negligence might be
anticipated for Gatehouse of Pok Ngar
Villa (new item pending for grading assessment) within the Project site while
indirect impacts of ground-borne vibration would also be anticipated the built
heritages located within 100m from the Project site, namely Gatehouse of Pok Ngar Villa (New Item Pending
for Grading Assessment), Li Cottage (Grade 1), Nos. 1-3 First Street, Tai Wai
(Grade 3) and Entrance Gate, Chik Chuen
Wai (Grade 2) during construction phase.
Appropriate mitigation measures including pre- and post-condition
surveys, buffer zone and monitoring of vibration, settlement and tilting
incorporated with AAA system for the concerned buildings have been recommended
for these built heritages to avoid and minimise any potential direct impacts
(e.g. damage through contacting with construction machineries and site
negligence) or indirect impacts of ground-borne vibration. With the provision of
the proposed measures, no adverse impact would be anticipated for built heritage during the
construction phase. Likewise, no
significant alteration of the current landscape which might affect the built
heritage would be expected. Therefore,
no adverse impact would be anticipated for built heritage during the
operational phase.
3.10.1
A
landscape and visual impacts assessment has been carried out in accordance with
Section 3.4.12 and Appendix J of the EIA Study Brief, Annexes 10 and 18 of the
EIAO-TM, and EIAO Guidance Note No.8/2010.
The assessment area for the landscape impact assessment include areas
within 100m from the boundary of the Project while the
assessment area for the visual impact assessment is defined by the visual
envelope of the Project.
3.10.2
The
construction works for the proposed revitalisation will mainly be carried out
within the Tai Wai Nullah. Certain
proposed architectural structures constructed at the roadside may impose visual
impact to adjacent visual sensitive receivers (VSRs). Amongst the 254 nos. of surveyed trees, 202
nos. are proposed to be retained, including all
existing mature trees growing along the nullah. According to the
latest tree treatment proposal, 1 no. of tree of common species (i.e. Sterculia lanceolata) will be
transplanted on-site, and 13 nos. of common species of trees (i.e. Ficus elastica,
Ficus subpisocarpa and Sterculia lanceolata)
and 38 nos. of undesirable species (i.e. Leucaena
leucocephala) are proposed to be removed. As stipulated in DEVB TC(W) No. 4/2020, “…the
number of compensatory trees onsite and offsite shall not be lower than that of
number of trees removed including dead trees, but excluding trees of
undesirable species...”, therefore, compensation
of the undesirable Leucaena leucocephala would not be required and
only 13 nos. of trees would need to be compensated. Nonetheless, to compensate the loss of
existing trees and to further enhance greening and the amenity value to
vicinity of site, approximately 28 nos. of heavy standard compensatory trees
are proposed to be planted at available planting area on-site. With the implementation of mitigation measures including preservation of
trees, compensatory tree planting, tree transplantation, control of night-time
lighting glare, erection of decorative screening hoarding, careful management
of construction activities and facilities, as well as reinstatement of
temporarily disturbed landscape areas and watercourses, no unacceptable
residual landscape and visual impacts from the construction of the Project
would be anticipated. The
provision of new landscaping works and recreational facilities along the nullah
proposed in this Project can have beneficial impact to the VSRs throughout the
operational phase.
3.10.3
Tai Wai Nullah will be revitalised with architectural and
landscape features aimed at promoting water friendliness and providing an
enhanced green and ecological environment.
The proposed architectural and landscape
features
and modified channel bed would be the key sources of visual /
landscape changes during operation. With
the proposed greening enhancement along channel bed and embankment, provision
of recreational opportunity along nullah, sensitive and aesthetically pleasing
design, re-provision of affected open space, the overall impacts are considered as acceptable in accordance to Annexes 10 and 18 of the EIAO-TM and the Project would be beneficial to
the landscape and visual aspects.
4
Environmental
monitoring and audit
5.1.2
The EIA study provided
information on the nature and extent of the environmental impacts likely to
arise from the revitalisation of TWN during
construction and operational phases. The EIA study has, where appropriate,
recommended pollution control measures as well as mitigation measures to ensure
compliance with the relevant environmental legislation, standards and
guidelines.
5.1.3
Overall, the EIA concluded that
the Project would comply with the requirements of the EIA Study Brief and EIAO-TM
with the implementation of the proposed measures during the construction and
operational phases of revitalisation of Tai Wai Nullah. The schedule of implementation of the
proposed measures has been provided in the EIA Report. An EM&A programme
has also been recommended to ensure the effectiveness of the proposed measures.