1.1.1.1
The Government plans to develop
Hung Shiu Kiu / Ha Tsuen New Development Area (HSK/HT NDA) for providing land
to meet the medium and long-term housing, social and economic needs. The HSK/HT
NDA is proposed to accommodate a population of approximately 176,000 persons
and generate about 150,000 employment opportunities on full development.
1.1.1.2
The Civil Engineering and
Development Department (CEDD) commenced Agreement, namely the Agreement No. CE
2/2011 (CE) “Hung Shui Kiu New Development Area, Planning and Engineering –
Investigation” in 2011, to formulate the detailed development proposals for the
HSK/HT NDA. This Study recommends that the sewage generated from the HSK/HT NDA
will be discharged to separate new sewage treatment work, namely the Hung Shui
Kiu Effluent Polishing Plant (HSKEPP) which is located in the western side of
the HSK/HT NDA.
1.1.1.3
The above study recommended
preliminary treatment capacity, treatment level and discharge arrangement of
HSKEPP taking into account the constraints for discharge to North Western
Waters and Deep Bay. Further reviews of flow projection, treatment level, treated
effluent discharge and sludge treatment scheme shall be carried out to
formulate the preliminary design of HSKEPP to cater for the sewage collected
from the new developments within the HSK/HT NDA and other developments in the
North West New Territories (NWNT) to support the medium and long-term housing
and economic needs of the NWNT.
1.1.1.4
AECOM Asia Co Ltd. was
commissioned by Drainage Services Department (DSD) on 27 March 2020 to carry
out this Assignment for the investigation for HSKEPP. Site location plan
of the HSKEPP is shown in Figure
1.1.
1.2.1.1
A Project Profile (No. PP-575/2019)
was submitted to the Environmental Protection Department (EPD) on 1 February 2019 for application for
an Environmental Impact Assessment (EIA) Study Brief under section 5(1)(a) of
the Environmental Impact Assessment Ordinance (EIAO) and the EIA Study Brief No.
ESB-312/2019 for the Project was issued on 15 March 2019 under the EIAO.
1.2.1.2
The Project comprises the following
element which is classified as Designated Project (DP) under Schedule 2, Part I
of the EIAO. The DP of this Project is summarized in Table 1.1.
Table 1.1 Schedule 2 Designated Projects in this Project
|
Schedule 2 Designated Project
|
Designated
Project Element under the Project
|
|
Item
F.1
|
Sewage
treatment works with an installed capacity of more than 15,000 m3/day.
|
The
proposed treatment capacity of HSKEPP would
be 90,000 m3/day.
|
|
|
|
1.3.1.1
This Executive Summary (ES)
summarizes the findings, recommendations and conclusions of the EIA Report for
the Project.
2.1.1.1
The purpose of the Project is
to provide sewage treatment to the sewage collected from the HSK/HT NDA and
other developments in the NWNT, and to subsequently dispose the treated
effluent.
2.1.1.2
HSK/HT NDA has reserved about 5.2
hectares of land for the proposed HSKEPP, the location of which is shown in Figure 1.1. According to the HSK/HT
NDA’s Revised Recommended Outline Development Plan (RODP), HSKEPP is located at
the western part of HSK/HT NDA. It is bounded by Yuen Tau Shan and Kong Sham
Western Highway at its southwest side and surrounded by logistic facilities at
its north and west direction. HSKEPP is located within the Logistics,
Enterprise and Technology Quarter. There will be a green belt to its south
side.
2.1.1.3
The proposed rising main for
raw sewage and emergency bypass pipe to Tin Shui Wai Nullah, as shown in Figure 1.1, are not under the
scope of the Project. The site formation works for the HSKEPP site (except the
demolition of existing San Wai Preliminary Treatment Works (SWPTW)) is also not
under the scope of the Project.
2.1.1.4
The proposed works of the
Project comprise:
1)
Demolition of existing structures and buildings
within SWPTW for construction of HSKEPP facilities;
2)
Construction
of a sewage treatment plant with a maximum capacity of Average Dry Weather Flow
(ADWF) up to 90,000 m3/day;
3)
Construction
of sludge treatment facilities for treating sludge generated from HSKEPP and
additional sludge generated from the San Wai Sewage Treatment Works (STW) and
other nearby STWs;
4)
Construction of facilities for receiving and anaerobic co-digesting pre-treated
food waste;
5)
Construction of effluent discharge pipe connecting to the existing discharge
tunnel of San Wai STW; and
6)
Associated ancillary works.
2.2.1.2
Upon the completion of HSKEPP, it
will provide sewage treatment to the sewage generation from the population and
development of HSK/HT NDA and other developments in the NWNT. With the planned treatment
capacity and high effluent quality, sewage from future developments within
HSKEPP catchment can be handled properly.
2.2.1.3
With secondary plus treatment
level at HSKEPP, the treated effluent will be normally discharged via the
existing NWNT Discharge Tunnel to Urmston Road submarine outfall, which avoids
any extra pollution loadings to the Deep Bay. With the secondary plus effluent
standard, the residual pollutants will be reduced and protect the water quality
of both North Western and Deep Bay Water Control Zones.
2.2.1.4
HSKEPP will give higher
treatment efficiency and cost effectiveness as well as improve the living
environment of its surrounding areas. With the enhancement of odour management
of the HSKEPP (covering all odorous facilities and installation of
deodorization units), odour nuisance to the surrounding area would be
effectively controlled and minimized.
2.2.1.5
As a sustainability
consideration, food waste/sewage sludge anaerobic co-digestion within HSKEPP will
be adopted to enhance energy recovery from the anaerobic digestion process.
Additional facilities for food waste/sewage sludge anaerobic co-digestion,
including reception facilities, digesters and dewatering facilities, will be
located within the HSKEPP’s footprint.
2.3.1.1
The treatment option evaluation
mainly focuses on the biological treatment processes as this is the critical
part in HSKEPP layouts.
2.3.1.2
A preliminary review of
potential biological treatment processes, including proven treatment processes,
market availability, overseas and local experiences and the emerging treatment
process, have been conducted. Two major options of biological treatment process
for the HSKEPP were considered, including:
·
Conventional Activated Sludge (CAS)
·
Compacted-type technologies
2.3.1.3
In considering the footprint
for various biological treatment options, CAS will produce considerably larger
volume of excavation materials and result in longer construction period. Thus,
compacted-type technologies were recommended.
2.3.2.1
Sludge cake generated from anaerobic
co-digestion of HSKEPP’s treatment of sewage sludge and food waste will be
delivered to the Sludge Treatment Facility (STF) in Tuen
Mun for incineration. Prior to conveyance to the STF, the following handling
options are considered:
·
Dewatering with prior anaerobic co-digestion of food
waste and sewage sludge
·
Direct dewatering without digestion
2.3.2.2
Anaerobic digestion is
recommended with the environmental benefits of reducing the volume of sludge
and food waste to be disposed of at STF, and allow energy recovery from biogas
generation for utilization within HSKEPP. Also, the organic contents in digested
sludge would be much lower so as to minimize the odour level in the downstream
dewatering and offsite disposal process.
2.3.3
Consideration of Layout Options
2.3.3.1
For developing of HSKEPP’s
internal layout, considerations of numerous engineering constraints and
environmental factors have been made as below:
·
The locations, size and arrangement on new treatment facility is bounded by
recommended treatment options. Thus, compacted size treatment facility is
provided in the layout.
·
In green building consideration, energy recovery from biogas is
recommended. Thus, chimneys from combined heat and power (CHP) is required in HSKEPP.
·
The required treatment capacity of 90,000 m3/day would determine
the size of treatment units and likewise would determine the amount of odour
emission and the requirement on deodorization units to cater the odour nuisance
due to sewage treatment process.
·
Odour emission to be treated by deodourization units are determined by
the surface area of the treatment facilities , the air exchange flow rate and
the odour emission strength according to odour generation sources such as
sewage and sludge tanks. Compacted treatment facilities would assist in
reducing the odour emissions with smaller tank sizes.
·
Odour extraction rates will be appropriately provided for man-access
areas with higher air exchange rates and for non-man-access odour enclosures
with lower air exchange rates to reduce the size of the deodourization units
necessary to treat the extracted foul air.
·
Foul air is treated as close to the emission source as possible with
decentralized deodourization units to reduce the footprint required for odour
extraction ductwork and to provide optimal deodourization treatment technology
for the various types of odour sources.
·
The layout of different treatment units is determined with due
considerations of not only the process requirements, but also environmental
factors, e.g. most of the air emission sources as well as deodourization units
are located with as much setback from the site boundary as possible to provide
maximum distance between the air emission sources and the sensitive receivers.
·
The scale and size of above-ground structures are determined by striking
a balance between the plant’s hydraulics and visual impacts to the surroundings.
Consideration
of Locations for the New Treatment Facilities
2.3.3.2
The locations of new treatment
facilities spread across two areas, with a larger section at the south of Ha
Tsuen Road (the South Section) and a smaller section at the north of Ha Tsuen
Road (the North Section), which is currently occupied by San Wai Sewage
Treatment Works. In order to minimize the scale of construction, sewage inlet
works would be located at the South Section near Ha Tsuen Road to minimise the
distance of the incoming sewage rising mains. The effluent discharge point will
be located at the North Section near the San Wai STW for connection to NWNT
Tunnel. As such, all the sewage treatment facilities (except disinfection
facility) and a part of the sludge treatment facility are located in the South
Section, while the North Section houses the remaining part of the sludge
treatment facility and the disinfection facility with effluent discharge pipe. In
addition, all the construction works and new facilities would be within the site
boundary to avoid additional project footprint. The new treatment facilities
arrangement is then designed under these boundary conditions.
Avoidance and
Reducing Environmental Impacts from Design and Layout
2.3.3.3
In order to avoid and minimize
environmental impacts in terms of air quality, noise, water quality,
ecological, landscape and visual aspect, the following major design and layout
will be adopted in HSKEPP:
·
All
the treatment units will be covered and ventilated via deodorization units.
Thus, odour impact would be minimized.
·
All
the treatment facilities and building will be ventilated with silencers at louvers.
Thus, fixed noise impact would then be minimized.
·
A
set of design measures will be installed to avoid and minimize the chance on
emergency discharge
·
All
the treatment units and buildings are designed with due considerations on
minimizing the building heights by such means as adopting equipment that requires
low headroom. This is to ensure all the
aboveground structures would not be excessively bulky so as to minimize the
visual impacts
2.4.1
Consideration of Site Formation
Works
2.4.1.1
The environmental implication
of site formation work for the southern portion of HSKEPP is covered in the EIA
report no. AEIAR-203/2016 – Hung Shui Kiu New Development Area. On the other
hand, the demolition of SWPTW (i.e. the northern portion of HSKEPP) and the
subsequent site formation works will be covered in the EIA report.
2.4.2
Consideration of Demolition
Methods
2.4.2.1
The existing
buildings/structures of SWPTW will be demolished for construction of new
treatment facilities of HSKEPP. With reference to the Code of Practice for
Demolition of Buildings (DCDB, Buildings Department 2004), several main methods
of techniques for the demolition works of the Project are identified,
including:
l
Implosion;
l
Breaker (excavator mounted);
l
Wrecking ball;
l
Cutting and drilling;
l
Non-explosive demolition agents;
l
Thermal lance; and
l Water jet.
2.4.2.2
Considering the use of breakers
(excavator mounted) is efficient and noise and dust impacts can potentially be
controlled by a range of practical mitigation measures (e.g. noise barriers, frequent
watering of construction area), the breakers (excavator mounted) will be
adopted as the preferred demolition method.
2.4.3
Consideration of Foundation
Methods
2.4.3.1
The foundation options are
highly dependent on the ground conditions. According to the available ground
information, the site is generally overlaid by fill, alluvium clay, completely
decomposed granite (CDG) and slightly/moderately decomposed granite (S/MDG). In
considering the geotechnical feasibility, the following foundation methods have
been considered:-
·
Pre-bored
socketed steel H piles (for heavy-duty structures only)
·
Percussive
piles
·
Shallow
foundation (for light-duty structures)
2.4.3.2
Since the proposed boundary of HSKEPP
is currently located within private land lots with numerous existing private
structures, the area accessible for ground investigation works is limited. As
such, the technical feasibility of different foundation options should be
further reviewed at a later project stage when more ground information can be
gathered.
Light-duty Structures
2.4.3.3
Piling foundation and shallow
foundation are both feasible foundation options for light-duty structures in HSKEPP.
In order to minimize the disturbance to adjacent environment in terms of noise
and vibration, shallow foundation is adopted for light-duty structure to reduce
the environmental impact of the Project during construction stage.
Heavy-duty Structures
2.4.3.4
Based on the existing drilling
record of ground investigation work, it is considered that both percussive pile
and bored pile are feasible foundation options for heavy-duty structures within
HSKEPP. However, since the stiffness of underground soil is undesirable for
percussive pile, it is not the preferable option due to anticipated long pile
length leading to low economic efficiency. Meanwhile, the tentative bed rock
level is at about 30m below ground level which allows the adoption of pre-bored
socketed steel H piles for heavy-duty buildings. Therefore, subject to the
detailed design of HSKEPP, bored pile would be the perferrable
foundation option for those heavy structures in HSKEPP.
2.4.3.5
In addition, since the
construction site of HSKEPP is located adjacent to the Kong Sham Western
Highway and Road 42755 (the road under Kong Sham Western Highway), the
vibration and noise induced by percussive piling is not desirable which may
affect the adjacent road traffic. Thus, pre-bored socketed steel H pile remains
the preferrable foundation option for heavy-duty structures in HSKEPP since it
would generate less vibration and disturbance to the adjacent area. However, it
should also be noted that pre-bored socketed steel H pile has its demerits of
requiring a comparatively longer construction period as well as generating much
larger volume of excavated materials to be disposed which would generate other
environmental impacts.
2.5.1.1
The Project construction works
are anticipated to commence in early 2027 with completion of the Project by 2031.
2.5.1.2
3.1.1.1
The potential air quality
impacts from the construction works of the HSKEPP would mainly be related to
the construction dust from the demolition of the existing SWPTW and
construction of superstructures and substructures (e.g. excavation, pilling, internal
roadworks). With the implementation of mitigation measures
specified in the Air Pollution Control (Construction Dust) Regulation, good
site practices, and EM&A programme, no adverse dust impact at ASRs is
anticipated due to the construction activities of the Project.
3.1.1.2
Flue gas emission would be
emitted from the stacks of CHP and boiler in the HSKEPP. Cumulative air quality impact arising from
the vehicular emissions from the open roads and other industrial emissions within the 500m
assessment area has also been assessed in the assessment. The assessment results conclude that the
predicted cumulative the 19th highest 1-hour and annual average NO2,
the 4th highest 10-min and the 4th highest daily average
SO2, the 10th highest daily and annual average RSP, the
19th highest daily (the number of allowable exceedance for
Government Projects) and annual average FSP concentrations at representative
ASRs would comply with the AQOs. No adverse air quality impact would
be anticipated arising from the flue gas emission associated with the operation
of HSKEPP.
3.1.1.3
All odour sources from sewage
treatment facilities and food waste/sewage sludge anaerobic co-digestion
facilities in HSKEPP would be fully enclosed.
The potential odour emission from these facilities would all be treated
in the deodourizers before discharge into atmosphere.
With implementation of effective deodourizers, the
assessment results showed that the predicted cumulative 5-second average odour
concentration at the representative ASRs within the Study Area would comply
with the criterion in EIAO-TM. No
adverse odour impact on identified ASRs would be anticipated during the
operation stage of proposed HSKEPP.
3.2.1.1
The assessment for the
potential construction noise impact from construction of the proposed HSKEPP has
been conducted. No existing/planned NSR
was identified within the 300m assessment boundary. No adverse construction noise impact due to
the construction of HSKEPP would be anticipated.
3.2.1.2
The assessment for the
potential fixed noise sources impact from operation of the proposed HSKEPP has
been conducted. No existing/planned NSR was
identified within the 300m assessment boundary.
No adverse operation phase fixed noise sources impact due to the
operation of HSKEPP would be anticipated.
3.3.1.1
Minor
water quality impact would be associated with land-based construction
works. Water quality impact may result
from wastewater generated from the general construction activities,
construction site runoff, construction works near inland watercourses, sewage
effluent from workforce and accidental chemical spillage. The potential impact could be mitigated and
controlled by implementing the recommended mitigation measures. No adverse water quality impact from
construction works for the HSKEPP would be anticipated.
3.3.1.2
Mathematical
modelling was conducted under this EIA to study the water quality impacts
caused by the potential change in the effluent flow and qualities from the
proposed HSKEPP. The model results
indicated that the proposed HSKEPP would not impose adverse water quality
impact into the North Western and North Western Supplementary WCZ. The model results showed that the predicted
salinity levels at WSRs in North Western and North Western Supplementary WCZs would comply with the WQO of no more
than 10% change from the background levels.
No unacceptable water quality impact from normal operation of the
proposed HSKEPP upon the receiving marine water would therefore be expected.
3.3.1.3
During
the NWNT tunnel maintenance, it is unavoidable to result in worsen water
quality (DO, BOD, TIN, UIA, SS and E. coli) due to increase of pollution
loading discharging into the Deep Bay WCZ.
In order to minimize the water quality impact, it is recommended under
this Project to schedule the NWNT tunnel maintenance during dry season
(November to March). The water quality
model predicted that the pollution elevation in Deep Bay WCZ and the associated
water quality recovery period would be significantly reduced and minimized for
the HSKEPP maintenance discharge during dry season. An event and action plan and a water quality
monitoring programme (as presented in the standalone EM&A Manual) is also proposed
for the NWNT tunnel maintenance events during both construction and operational
phases to minimize the water quality impacts.
3.3.1.4
For
emergency discharge, the model results indicated that elevated levels of key
water quality parameters would be recovered within 0.5-2.0 days after
termination of the emergency discharge for Water Sensitive Receivers within
Inner Deep Bay. The more distant WSR
i.e. Oyster Culture Area was found not to be affected by emergency discharge
event. The occurrence of emergency
discharge from the proposed HSKEPP can be minimised
by the implementation of appropriate mitigation measures, including dual power
supply and provision of standby facilities. An Emergency Response Plan will be formulated
prior to commissioning of HSKEPP to minimize the impact of emergency discharges
and facilitate subsequent management of the emergency.
3.3.1.5
Other
water quality impacts associated with the operation phase are identified as
surface runoff from paved areas and accidental spillage. It is expected that these potential impacts
can be prevented by adopting recommended mitigation measures. No unacceptable residual water quality impact
would be expected.
3.4.1.1
Waste management implications
associated with the construction and operation of the Project were identified
and assessed. Waste types generated by the construction activities of the
Project would include construction and demolition (C&D) materials (from
excavation works, foundation / construction works and demolition of existing
structures/ buildings within SWPTW), general refuse (from construction
workforce) and chemical waste (from maintenance of construction plant and
equipment, as well as building demolition). Provided that these wastes are
handled, transported and reused/disposed of using approved methods and that the
recommended good site practices are strictly followed, adverse environmental
impacts during construction phase would not be anticipated.
3.4.1.2
Reduction measures have been
recommended to minimise the amount of C&D materials generated in the
Project. Approximately 324,000 m3
of inert C&D materials and 32,000 m3 of non-inert C&D
materials would be generated during the construction phase of the Project. 74,800 m3 of inert C&D
material would be reused on site while the remaining 249,200 m3 of
surplus inert C&D material would be recycled or transported to Public Fill
Reception Facilities for beneficial reuse in other projects. Non-inert C&D waste would be recycled as
far as possible before disposed to landfill.
Opportunities in minimisation of generation and maximisation of reuse
would be continually investigated during the detailed design and construction
phases. The other materials that cannot
be reused or recycled would be disposed to designated outlets (e.g. Chemical Waste Treatment Centre, landfills).
3.4.1.3
During operation, the main
waste types to be generated would be grit and screenings, dewatered sludge,
chemical waste and general refuse. The
grit and screenings would be compacted and properly stored in a covered container
prior to disposal at landfill on a daily basis.
The transportation and disposal of the grit and screenings would be
managed and controlled by a reputable waste collector. The dewatered sludge would be disposed of to
the Sludge Treatment Facility (STF).
Provided that proper handling procedures and disposal method are
adopted, adverse environmental impacts would not be anticipated during the
operation phase.
3.5.1.1
A site appraisal, including the review of the HSK NDA EIA Study,
desktop review and site walkover, was conducted from August 2020 to September
2021 to identify any potentially contaminating land uses within the proposed
HSKEPP site. Based on the site appraisal
findings, 4 facilities / areas with land contamination
concern within the northern portion of HSKEPP (existing SWPTW) and 6
potentially contaminated sites within the southern portion of HSKEPP were
identified.
3.5.1.2
Similar
to the HSK NDA EIA Study, the identified concerned
areas were inaccessible for detailed site walkover or SI works and still in
operation. In addition, there might be change in land use prior to development
which could result in further land contamination issues. Therefore, site
re-appraisal should be conducted for the identified concerned areas prior to
development of the sites in order to update findings of the site appraisal
(e.g. locations of hotspots) and the sampling and testing requirements for SI
works. In addition, re-appraisal would
be required for the other remaining areas of the proposed HSKEPP site in order
to assess the latest land uses and site conditions. The further works including site re-appraisal
for the whole proposed HSKEPP site, associated SI works, any necessary
remediation works and submission of supplementary Contamination Assessment Plan
/ Contamination Assessment Report / Remediation Action Plan / Remediation
Report are recommended to be carried out
prior to commencement of any construction or development works, and would
follow the relevant Guidance Manual, Guidance Note and Practice Guide.
3.5.1.3
With
the implementation of the recommended further works for the Project, any soil /
groundwater contamination would be identified and properly treated prior to the
construction works. No insurmountable
land contamination impacts to the Project are therefore anticipated.
3.6.1.1
A
literature review and ecological field surveys have been conducted. A total of
thirteen habitat types, including developed
area/wasteland, plantation, grassland/shrubland, shrubland, mixed woodland,
woodland, orchard, dry agricultural land, wet agricultural land, marsh, pond,
modified watercourse and natural watercourse were recorded within the 500 m assessment area
from recent surveys, with developed area/wasteland, and a small area and
section of shrubland, dry agricultural land and modified watercourse recorded
within the Project site. The ecological values of habitats within the Project
site are very low and low, as they are highly modified and disturbed habitats
which support limited flora and fauna.
Similarly, due to the extent of existing development in the area, most
of the other habitats recorded within the assessment area are of low ecological
value, with the exception of the shrubland and mixed woodland on the terrain of
Yuen Tau Shan, which are considered to be of low to moderate ecological
value. In general, the assessment area
supported limited wildlife, most wildlife were observed within the agricultural
land-pond-marsh matrix to the west of KSWH.
3.6.1.2
No potential direct impact on
recognised sites of conservation importance and natural habitats is expected to
arise from the Project as all site formation works would be completed under a
separate agreement for HSK/HT NDA, prior to the commencement of construction
works for this Project. Indirect
impacts, in the form of construction disturbance and water quality
deterioration, are anticipated, though the ecological impact from these
indirect impacts is expected to be minor and low, and no mitigation measures
are required. Precautionary measures and
enhancement opportunities to further minimize any potential environmental
impacts and promote the ecological value of the Project are recommended. No adverse residual indirect impacts are
expected arising from the Project.
3.6.1.3
Ecological monitoring and
auditing are not required as no significant construction and operational phase
ecological impact is anticipated; nor is any residual ecological impact.
3.7.1.1
Landscape and visual impacts
assessment has been assessed in accordance with the criteria and guidelines as
stated in Annexes 10 and 18 of the EIAO-TM and the Environmental Impact
Assessment Ordinance (EIAO) Guidance Note No. 8/2010 on “Preparation of
Landscape and Visual Impact Assessment under the Environmental Impact
Assessment Ordinance”, as well as Section 3.4.9 and Appendix G of the EIA study
brief.
3.7.1.2
The Project will inevitably
result in some landscape and visual impacts during construction and operation
phases. These impacts have been
minimized through minimization of works areas, and incorporation of sensitive
and aesthetically pleasing design of aboveground structures and appropriate
landscape and visual treatments for the project.
Landscape
Impacts
3.7.1.3
Within the assessment area, 13
Landscape Resources (LRs) and 4 Landscape Character Areas (LCAs) are
identified.
3.7.1.4
Based on the broad-brush tree
survey, approximately 224 nos. of trees were surveyed within the project site
boundary. A total of 224 trees in 4 tree groups (no trees of particular
interests and potential tree of particular interest) within the project
boundary and would be potentially affected were surveyed. There is no OVT in
accordance with DEVB TC(W) No. 5/2020 identified within the project boundary.
The dominant tree species include Acacia confusa,
Artocarpus heterohpyllus, Celtis sinensis,
Dimocarpus longan, Ficus benjamina, Ficus hispida,
Leucaena leucocephala, Litchi chinensis,
Schefflera heptaphylla, Mangifera indica and Macaranga tanarius . They are generally of heavy-standard to
mature size. All tree species in tree
groups surveyed are common in Hong Kong and without specific conservation
interest, in which 89 nos. of the surveyed trees are undesirable tree species Leucaena
leucocephala.
3.7.1.5
Under the proposed scheme for
the Project, opportunities for tree compensation within the Project boundary
has been fully explored and incorporated in the proposed mitigation measures as
much as practicable. Within the project boundary, a minimum of 250 heavy
standard trees will be proposed on-site and along roadside flat areas as
compensatory tree planting. Mix of native tree species will be proposed with
reference to Guiding Principles on Use of Native Plant Species in Public Works
Projects promulgated by DEVB to improve the vegetation diversity, enhance
ecological value and re-creation of vegetation habitat particular for areas
adjoining the hillside area.
Visual Impacts
3.7.1.6
There are 7 types of Key
Visually Sensitive Receiver (VSR) types identified in the Visual Envelopes of
the Project, which are Residential VSRs, Recreational VSRs, Religious VSR, Occupational
VSR, Travelling VSR, Planned Recreational VSR and Planned Occupational VSR.
3.7.1.7
Appropriate landscape and
visual mitigation measures are proposed during construction phase, including preservation
of existing vegetation, minimize disturbance on watercourses, management of
construction activities and facilities, reinstatement of temporarily disturbed
landscape areas, control of night-time lighting glare and erection of
decorative screen hoarding, and during operation phase, including compensatory
tree planting for loss of existing trees, roadside and amenity planting,
sensitive and aesthetically pleasing design of aboveground structures,
provision of buffer planting, provision of green roof and control of night-time
lighting glare, to alleviate the potential impacts. Regarding mitigated visual
impact, it is predicted that there would be slight to moderate residual impact on
all the VSRs during construction, and would be
insubstantial to moderate on day 1 of operation and be further reduced to
insubstantial to slight when the proposed tree planting becomes mature in year
10 of operation.
3.7.1.8
As a whole, the residual
landscape and visual impacts of the proposed Project is considered acceptable
with the proposed mitigation measures implemented during construction and
operation phases.
3.8.1.1
A quantitative hazard assessment
was conducted to evaluate the biogas risk to existing, committed and planned
off-site population due to operation of the food waste/sewage sludge anaerobic
co-digestion facility at the proposed HSKEPP. Both the individual and societal
risk levels were found to meet relevant requirements stipulated in the HKRG,
i.e. the off-site individual risk level is far below 1×10-5 per
year and the societal risk falls into the “Acceptable” region. No
mitigation measure is required. Therefore, the biogas risk associated
with the operation of the proposed HSKEPP is considered acceptable.
4.1.1.1
Environmental Monitoring and
Audit (EM&A) requirements for air quality, noise, water quality, waste
management, land contamination, and landscape and visual impacts as well as
hazard to life have been recommended, with regular site inspection and audits
during construction phase to ensure that the recommended mitigation measures
are properly implemented. The environmental
monitoring to be conducted include construction dust monitoring during
construction, commissioning test at the exhaust of CHP and boiler, odour
monitoring at the inlet and outlet of deodourizing
unit, odour patrol during regular and ad hoc maintenance or cleaning of the deodouring unit, water monitoring during construction and
operation phases. The EM&A requirements are specified and detailed in the
EM&A Manual.
5.1.1.1
The
findings of the EIA provided information on the nature and extent of the
environmental impacts likely to arise from the construction and operation of
the Project. The EIA has, where
appropriate, identified mitigation measures to ensure compliance with
environmental legislation and standards.
5.1.1.2
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 mitigation
measures during construction and operational phases of the Project. The schedule of implementation of the
proposed mitigation measures has been provided in the EIA Report. An EM&A programme has also been recommended
to check the effectiveness of the proposed mitigation measures.