Table of Contents
9 Ecological
Impact Assessment (Terrestrial & Aquatic). 1
9.1 Introduction.. 1
9.2 Legislative Requirements &
Evaluation Criteria. 1
9.3 Baseline Conditions. 2
9.4 Impact Identification.. 4
9.5 Impact Assessment 4
9.6 Impact Evaluation.. 13
9.7 Mitigation Measures. 18
9.8 Cumulative Ecological Impact 21
9.9 Residual Impact 21
9.10 Environmental Monitoring &
Audit (EM&A). 22
9.11 Conclusions. 22
This Section
presents the findings of an assessment of the potential ecological impacts
associated with the construction and operation of the proposed Project in TKO
Area 137. It summarises baseline
information gathered from the literature review and baseline ecological surveys
on the terrestrial and marine ecological resources in the Study Area, and
describes the ecological importance of this area.
The local ordinances,
regulations and guidelines relevant to protection of species and habitats of
ecological importance include the following:
·
Environmental Impact Assessment Ordinance ("the
EIAO", Cap. 499) and the associated Technical Memorandum (EIAO-TM)
·
EIAO Guidance Note No. 6/2010
·
EIAO Guidance Note No. 7/2010
·
EIAO Guidance Note No. 10/2010
·
EIAO Guidance Note No. 11/2010
·
Hong Kong Planning Standards and Guidelines Chapter
10 (HKPSG)
·
Forests and Countryside Ordinance (Cap. 96) and its
subsidiary legislation, the Forestry Regulations
·
Wild Animals Protection Ordinance (Cap. 170)
·
Protection of Endangered Species of Animals and
Plants Ordinance (Cap. 586)
·
Country Parks Ordinance (Cap. 208) and its
subsidiary legislation
·
Town Planning Ordinance (Cap. 131)
·
PRC Regulations and Guidelines
·
China Red Data Book of Endangered Animals
·
IUCN Red List Categories and Criteria
·
United Nations Convention on Biological Diversity
(1992)
·
The Convention on International Trade in Endangered
Species of Wild Fauna and Flora (CITES)
These are described in
detail in Annex 9A.
The baseline conditions of
both terrestrial and marine ecological resources of the habitats in the Study
Area are reviewed by desktop literature review and dedicated field
surveys. The methodology and findings of
this review is presented in detail in Annex
9A.
In
summary, the proposed desalination plant (“Project Site”) lies on a reclamation
area at the southern end of existing TKO Area 137. The reclamation area for the Project Site is
located between Tit Cham Chau and a small unnamed hill to the west of Tin Ha
Shan, both of which lie within the Clear Water Bay Country Park. The Clear Water Bay Country Park is a
recognized site of conservation importance. The proposed slope mitigation works
will be implemented to stabilize the natural slopes and boulders within the
Clear Water Bay Country Park overlooking the northeast boundary of the new
desalination plant. In addition, the
Project will involve the provision of a freshwater main along existing roads of
Wan Po Road, Po Hong Road and Tsui Lam Road. Two submarine facilities will be installed on
the seabed 200-400m from the reclamation seawall. Considering the environmental setting of the
Project and the Project construction and operation activities, the key
ecologically sensitive areas are the Clear Water Bay Country Park where slope
mitigation works will be undertaken, and the subtidal
communities of Joss House Bay where species of conservation interest may be
found.
Findings
of the literature review (Annex 9A)
identified that data gaps exist for the ecological habitats and communities in
the areas within and surrounding the Project Site. These areas cover both land and sea and in
particular represent the areas where direct impacts (e.g. habitat loss) may
occur. In accordance with the
requirements of the EIA Study Brief, focused field surveys of six months
covering both wet and dry seasons were completed in 2014 to verify the
information from the desktop review, fill the above information gap, and
fulfill the objectives of this EIA. An
additional survey was also conducted in the wet season of 2015 to provide
supplementary ecological information on the specific locations where slope
mitigation works will be implemented inside the Clear Water Bay Country
Park. Detailed findings of the field
surveys are presented in Annexes 9A and 9B, and the ecological profiles and
existing wildlife uses of the various habitats of the Study Area and the
Project Site are also described therein.
The
field surveys confirmed that a majority (~90%) of the Project Site is man-made
habitats with very low to low ecological values. Patches of vegetation of some ecological
value were found near the uphill of the study area of slope mitigation works
which is located within natural habitats of the Clear Water Bay Country
Park. Since no slope mitigation works
would be undertaken at the uphill of the Study Area of slope mitigation works,
no direct impact is anticipated to vegetation of some ecological value at the
uphill natural habitats (Annex 9A). At the lower portion of the natural hill of
the Clear Water Bay Country Park, a flora species of conservation interest Marsdenia lachnostoma
was recorded in the shrubland/grassland habitat along
the proposed alignment of the flexible barriers within the country park area (Annex 9B). The mixed woodland and shrubland/
grassland habitats within slope mitigation works area are located at the edge
of Clear Water Bay Country Park with relatively low abundance and diversity of
fauna, and the trees were mostly native and common species of fair
condition. The mixed woodland and shrubland/ grassland habitats in the Study Area are
considered to be of low to moderate ecological value. Also the presence of recent hill fire and disturbed
vegetation were observed within the slope mitigation works area (Annex 9B)
as well as the Study Area. The watermain is located on existing roads which are of no
particular ecological value, and the submarine facilities are located on the
seabed with soft and hard bottom communities typical in other similar habitats
of Hong Kong.
The
ecological values of the habitats recorded within the Study Area have been
evaluated in accordance with the criteria stipulated in Table 2 of Annex 8 of EIAO-TM.
Details of the evaluation are provided in Annex 9A. The overall
ecological values of the habitats recorded in the Study Area are summarized in Table
9.1.
Table 9.1 Habitat Evaluation
|
Habitat
|
Overall Ecological Value
|
Habitat found in Project
Site?
|
|
Mixed Woodland
|
Low to moderate
|
ü
(Desalination Plant site
and slope mitigation works)
|
|
Plantation
|
Low
|
û
|
|
Shrubland/Grassland
|
Low to moderate
|
ü
(Desalination Plant site
and slope mitigation works)
|
|
Agricultural Land
|
Low
|
û
|
|
Wasteland
|
Low
|
ü
(Desalination Plant Site
only)
|
|
Watercourse
|
Low for man-made channel
and ditch
Low to moderate for the
natural section
|
ü
(Man-made channel and ditch within Desalination Plant Site)
|
|
Urbanised/disturbed
|
Very low
|
ü
(Desalination Plant Site
and water mains)
|
|
Natural Rocky Shore
|
Moderate
|
û
|
|
Sandy Shore
|
Low
|
û
|
|
Artificial Seawall
|
Very low
|
ü
(Desalination Plant Site
only)
|
|
Marine Waters
|
Low to moderate for subtidal hard bottom
Low to moderate for subtidal soft bottom
|
ü
(submarine facilities)
|
A
total of nine flora and twenty-three faunal taxa (including hard corals) of
conservation interest were recorded in the Study Area. The ecological values of species of
conservation interest were assessed in accordance with Table 3, Annex 8 of the EIAO-TM in terms of protection status (e.g.
fauna protected under WAPO (except
birds), and flora and fauna protected under regional/global
legislation/conventions), species distribution (e.g. endemism), and rarity
(e.g. rare or restricted). Details of
the evaluation are provided in Annexes 9A
and 9B. Among the recorded flora species of
conservation interest, Marsdenia lachnostoma
is the only flora species found within the area for slope mitigation works,
whilst the other flora species of conservation species were recorded outside
the proposed slope mitigation works area (i.e. outside the flexible barriers,
rock slope stabilization area and soil nailing area) and Project Site. It should also be noted that while five
terrestrial fauna species of conservation interest, all bird species, were
sighted within the proposed works areas, with their mobility they also make use
of other habitats of the Study Area and beyond. Some marine species of conservation interest
were recorded, but they are mostly common in Hong Kong and not unique to this
Study Area.
Potential
sources of impacts to ecological resources can arise from both the construction
and operation phases. Each is discussed
in turn below.
9.4.1
Construction
Phase
Land-based
construction activities and minor marine dredging works of this Project have
the potential to affect ecological resources by:
·
Direct
loss of habitats and vegetation removal within the footprint of the land-based
works area, including reduction of species abundance/diversity, loss of feeding
grounds, reduction of ecological carrying capacity;
·
Direct
disturbances to benthic habitat within the marine works area;
·
Potential
disturbance to the recognized site of conservation importance at the Clear
Water Bay Country Park;
·
Potential
disturbance to species of conservation interest;
·
Habitat
fragmentation and isolation, including restriction of wildlife utilisation of
the area (i.e. transit, feeding and roosting) especially for those inactive/
less mobile/ habitat-specific wildlife nesting/inhabiting the habitats, and
degradation of habitat quality/ ecological function;
·
Physical
disturbance to the surrounding habitats and associated wildlife due to noise
and increased human activities, etc.; and,
·
Potential
indirect impact, potential changes in the water quality, hydrodynamics
properties, sedimentation hydrology.
9.4.2
Operation
Phase
The
potential impacts of the operational phase of the Project on the ecology of the
Study Area are mainly due to perturbations to key water quality parameters from
the discharge of hypersaline water from the Reverse Osmosis process.
Terrestrial
ecological resources are not expected to be impacted by the Project’s
operational activities.
9.5.1
Assessment
Methodology
Potential impacts that may arise
from the construction and operational phases for the development of the Project
are assessed following the EIAO-TM Annex
16 guidelines, and the impacts evaluated based on the criteria in EIAO-TM Annex 8.
9.5.2
Terrestrial
Ecology (Construction Phase Only)
a)
Habitat Loss/ Disturbance and Vegetation Removal
The
major impact on terrestrial ecological resources is the direct loss of habitats
and the associated vegetation and fauna.
The habitat composition and their areas at the desalination plant and
the slope mitigation works (i.e. habitat loss) are summarized in Table
9.2, ecological values and the total areas of the habitats within the
Study Area are provided as well.
Table 9.2 Habitat composition of the proposed desalination plant and
slope mitigation works area
|
Habitat
|
Ecological Value of
the Habitat
|
Desalination
Plant, with result of Habitat Loss (ha)
|
Anticipated
Slope Mitigation Works Area within Country Park Area (ha) (1)
|
Total
Affected Areas (ha)
|
|
Rock Slope
Stabilization Area
|
Soil Nailing Area
|
Flexible
Barrier with
Country
Park)
|
|
Mixed Woodland
|
Low to moderate
|
0.61
|
0.10
|
0.08
|
─
|
0.79
|
|
Shrubland/ Grassland
|
Low to moderate
|
0.38
|
0.10
|
0.14
|
0.07
|
0.69
|
|
Wasteland
|
Low
|
3.78
|
─
|
─
|
─
|
3.78
|
|
Watercourse – man-made channel and ditch
|
Low
|
0.18
(0.7 km)
|
─
|
─
|
─
|
0.18
(0.7 km)
|
|
Urbanised/ Disturbed Land
|
Very low
|
5.24
|
─
|
─
|
─
|
5.24
|
|
Subtidal hard and soft bottoms (marine waters)
|
Low to moderate
|
0.11
(submarine facilities)
|
─
|
─
|
─
|
0.11
(submarine facilities)
|
|
Seawall
|
Very low
|
0.28
|
─
|
─
|
─
|
0.28
|
|
Total:
|
10.58
|
0.20
|
0.22
|
0.07
|
11.07
|
|
Note
|
|
|
|
|
|
|
|
(1)
Total area of habitat
disturbance without tree felling in the Clear Water Bay Country Park due to
slope mitigation works = 0.2 + 0.22 + 0.07 = 0.49 ha
|
|
|
|
|
|
|
|
|
Habitat Loss due to Desalination Plant
A
total of 10.58 ha of habitat loss is anticipated for
the construction of desalination plant.
Site clearance will be undertaken prior to major civil works and all
existing vegetation (predominately grass, weedy plants and also with some
scattered shrubs and possibly some trees) within the affected habitats will be
removed. The habitat loss due to the desalination
plant are largely urbanized/ disturbed land and wasteland of very low to low
ecological value with no species of conservation interest relying on these
habitats. The affected vegetation is
confined to common and amenity planting.
No habitats of high ecological values will be affected. According to the findings of the baseline
surveys, all the plants found within the Project Site are common species, with
no flora species of conservation interest recorded. Also the diversity of and use by wildlife is
low, thus the potential impacts on fauna are minimal.
Habitat Disturbance due to Anticipated Slope
Mitigation Works Area
A
total of 0.49 ha of natural habitats would be disturbed due to the
implementation of slope mitigation works.
The localized soil and rock slope stabilization works will be optimized
as much as practicable to avoid impacts on existing habitats and vegetation,
and temporary access for the construction works would be limited to within the
works areas as far as practical to reduce the footprint of potential
disturbance. Localized clearance of
vegetation to allow construction of the slope mitigation works will be
minimized. Whilst the slope mitigation
works area is located within the Clear Water Bay Country Park with habitats of
low to moderate ecological value (shrubland/grassland
and mixed woodland), the habitats are expected to be disturbed temporarily
during the construction works only and will be reinstated by hydro-seeding and
planting of climbers and native shrub seedlings where practical upon completion
of the slope mitigation works. For
proper reinstatement, the selection of native shrub seedlings would take
original natural habitat into account.
Also,
the affected shrubland/grassland and mixed woodland
habitats are located at the edge of the country park area adjacent to the
disturbed land, typically subjected to higher levels of disturbance, and
therefore generally support faunal generalists that are adapted to human
disturbance and using a range of habitats.
Consequently, the ecological value/ significance of the affected shrubland/grassland and mixed woodland habitats are further
less than those at the inner part of the habitats. There are extensive similar habitats
available nearby for any fauna displaced due to the project. Therefore long-term impacts are not
anticipated. As the diversity of fauna and their
utilization of the habitat are low, the potential impacts on fauna in these
natural habitats are anticipated to be minimal.
The
above estimate represents the worst case assumption at the time of preparing
this report and currently the slope mitigation works are planned at the lower
portion of natural hill slope only. The
area for slope mitigation works will be reduced as far as practicable. This would significantly reduce the magnitude
of impacts of natural habitats and the core area in Clear Water Bay Country
Park. No habitats of high ecological
values will be affected.
No
trees will be felled for the implementation of slope mitigation works. To avoid tree felling, the exact locations of
the flexible barrier foundation plates, soil nails and rock dowels can be
adjusted during detailed design when detailed topographic data are
available. To further minimize potential
impacts on trees including the root system, a setback distance (e.g. 1-1.5m
from stem) from existing trees can be maintained as far as practical. For the flexible barriers which are 4-5m
tall, canopies of existing trees, if any, may be in conflict with the barriers
and pruning may be required. This will
be minimized as far as practicable and will be undertaken properly to reduce
damages to trees.
To
restore the naturalness of habitats within the Country Park and improve the
vegetation cover in the desalination plant, landscaping works will be provided
at the desalination plant and slope mitigation works area upon completion of
the construction. With the
implementation of these mitigation measures, the impact of habitat
loss/disturbance and vegetation removal arising from the construction is hence
considered to be within acceptable levels.
No unacceptable impact of reduction of species abundance/diversity, loss
of feeding grounds, and reduction of ecological carrying capacity is expected.
b)
Impact on Recognized Sites of Conservation
Importance
The
5.94 ha study area of slope mitigation works falls into the gazetted
area of Clear Water Bay Country Park which is a recognized site of conservation
importance. However, by considering the
different slope mitigation works method as discussed in Section 2, only a small lower portion of natural slope within the
Clear Water Bay Country Park (0.49 ha) would be unavoidably affected by the
slope mitigation works. Despite
encroachment onto the areas of planning/ conservation concern, the ecological
values of the affected habitats as mentioned above are low to moderate. Recent
site visits have suggested that the affected
area which is located at the fringe of the natural habitat of country parks
area has subjected to higher levels of disturbance, the vegetation is in fair
conditions with trees young in age.
The diversity of flora and fauna is low and most of the species
identified are common, widespread and typical of such habitat in Hong
Kong. In accordance with the findings
from the vegetation survey (Annex 9B), the direct footprint of slope mitigation works area was
dominated by native herb/climber with low diversity of tree species. All tree species recorded within the slope
mitigation works area are common in Hong Kong.
Although one flora of species conservation interest Marsdenia lachnostoma within the slope works in
the Country Park would be directly affected (Annex 9B), the slope mitigation works is planned to avoid trees as
far as practicable, thus potential tree felling works would be avoided. The potential impact on flora of species
conservation interest and corresponding mitigation measures are discussed in
the sections below. It is important to
note that the implementation of the slope mitigation works would result in loss
of naturalness of habitats in Clear Water Bay Country Park, but the naturalness
is partially reversible and permanent loss in the habitats of the Clear Water
Bay Country Park is not anticipated.
Given the small scale of the slope mitigation works and no slope cutting
will be involved, ecological impact on the overall country park area and its
associated wildlife is considered to be low.
The
method of slope mitigation works would be mixed use of flexible barrier, soil
nail and rock stabilization. This method
has been chosen to minimize the direct habitat loss and disturbance to the
natural habitats of low to moderate ecological values within the country park
area. By using such construction method
as well as the implementation of good practice to control site run-off (see Section 6 for detailed mitigation
measures to control construction site runoff and drainage), the potential
impact of land based construction activities on the habitats surrounding the
slope mitigation works is predicted to be minor.
c)
Impact on Species of Conservation Interest
For
terrestrial ecology, a total of nine flora and 21 fauna species of conservation
interest were recorded in the Study Area.
All flora species of conservation concern, except for Marsdenia lachnostoma,
are recorded outside the proposed slope mitigation works area and desalination
plant site, hence no impacts on these species is anticipated. Ten specimens of M. lachnostoma were identified along the
proposed alignment of flexible barriers in shrubland-grassland
habitat. M. lachnostoma is a very rare species
documented in the Rare and Precious
Plants of Hong Kong with status of Critically Endangered (CR) in mainland
China. Without mitigation, potential
impact to this species would be of moderate significance. To avoid direct conflict between the
construction of flexible barrier (including the temporary access) and
individuals of M. lachnostoma,
the exact alignment of flexible barriers can be further adjusted during
detailed design. Further mitigation
measures are discussed in Section 9.7 with
a view to preserving individuals of this species in its totality. With the proper implementation of the
proposed mitigation measures, no unacceptable adverse impact on M. lachnostoma
is anticipated.
Of
the 22 fauna species of conservation interest, only five species were recorded
within the proposed Project Site and works areas. These five species are birds, including
Black Kite, Black-crowned Night Heron, White-throated Kingfisher, Collared Scops Owl and Lesser Coucal. Only one individual of each species were
recorded. While these species were
sighted and/or their calls were heard within the proposed works areas, with
their mobility they are expected to make use of other similar habitats and
vegetation of the Study Area and beyond, and are therefore unlikely to rely
solely on the works areas.
An
empty bird nest was recorded on a tree in the northern edge of the slope
mitigation works area which is close to where the Collared Scops
Owl was recorded (by bird call) (Annexes
9A and 9B). It has been reported that Collared Scops Owl uses old Common Magpie nests and also hollow
trees for breeding [1].
The
baseline survey found that the nest was not occupied, and no recently fledged
individuals or Collared Scops Owl was sighted or
heard again in a recent survey (Annex 9B). Also, this species is a widespread and common
resident in lowland areas of closed canopy shrubland
and woodland habitats [2],[3].
Therefore,
this species is considered to be an occasional visitor to the slope mitigation
works area and does not rely solely on the works areas.
Furthermore,
it is important to note that trees within the area for slope mitigation works
in the Clear Water Bay Country Park, where the Collared Scops
Owl and other species of conservation interest were recorded, will be retained
and so these habitats remain to be available to the species. Disturbance to natural habitats will be
minimized where possible to reduce impact to these species. As such, no unacceptable impacts on the fauna
species of conservation interest in the Study Area is anticipated.
d)
Habitat Fragmentation and Isolation
Construction
phase activities could lead to a direct ‘barrier’ effect, where the movement of
animals (in particular terrestrial mammals and herpetofauna)
through an area would be obstructed. The division of the habitats may lead to
indirect fragmentation and isolation impacts.
Whilst fragmentation and isolation effects are often difficult to
quantify, potential impacts resulting from habitat fragmentation would include:
·
Decline
in species number and densities over and above that which would be expected
from habitat loss alone;
·
Loss
of ‘core’ or characteristic species dependant on large habitat patches, and
concomitant increases in ‘edge’ or more facultative species; and
·
Other changes in community composition.
For
the desalination plant with footprints extending to mixed woodland and shrubland/grassland, no habitat fragmentation and isolation
impacts is anticipated as the affected habitats are in close proximity to
disturbed area (e.g. Fill Bank at Tseung Kwan O Area
137), and the proposed freshwater mains will be laid along existing roads /
accesses. For the slope mitigation
works, the large continuous and undisturbed habitats such as shrubland-grassland in the Clear Water Bay Country Park are
of low to moderate ecological value and will remain largely untouched throughout
the construction of the Project. Also,
the affected mixed woodland and shrubland/grassland
habitats are located at the edge of the natural habitats within country park
area with relatively low diversity and abundance of fauna species. Hence, the reduction of wildlife utilisation of the areas (i.e. transit, feeding and
roosting) especially for those less mobile / habitat-specific species as a
result of habitat fragmentation/ isolation are unlikely to be significant. For the provision of flexible barriers,
whilst the baseline surveys suggest that wildlife use of the Clear Water Bay
Country Park appears to be minimal, gaps (post‐to‐post) will be
provided to allow passage for wildlife, hence reducing potential impacts on
fragmentation and isolation.
e)
Noises, Human Activities and Other Disturbances
Secondary
impacts to the surrounding habitats and associated wildlife may arise from
increased noise, human activities and other physical disturbances. These disturbances would in turn bring about
indirect impacts to nearby habitats and their associated fauna. Potential impacts to wildlife include
avoidance of areas in the vicinity of works area, and decline in density in
areas close to the source of disturbance.
The
construction works for desalination plant and slope mitigation works would be
temporary and for a duration of about 3.5 years. Moreover, the works areas, in particular the
slope mitigation works, will be reduced as far as practical to minimize
disturbance to the natural habitats. The
impacts are expected to be low owing to the existing human presence in nearby
areas (e.g. Fill Bank at Tseung Kwan O Area 137),
the temporary nature and relatively small scale of the construction works. Given the implementation of environmental
mitigation measures and regular checks on construction practices, the impacts
are not expected to be unacceptable.
9.5.3
Marine
Ecology
As
indicated by the findings of the water quality impact assessment and water
quality modeling results (Section 6 refers), the predicted zone of influence of
the Project is limited to the immediate vicinity of the submarine intake and
outfall. In this context, the marine
ecological impact assessment in this section focuses on the area around the
development footprint.
Construction Phase
Potential
impacts of the construction activities on marine ecological resources are
presented in Section 9.4.1.
Habitat Loss
The direct
impacts of the minor marine dredging activities will be the loss of subtidal soft bottom habitats for the installation of the
submarine intake and outfall pipelines and the removal of organisms associated
with the habitats. The marine dredging
area would be very small, i.e. 0.11 ha.
It is important to determine whether the area of disturbance contain
species of interest or noteworthy benthic assemblages, which will be lost
during the marine works. Findings from
the literature reviews and the baseline subtidal
benthos survey indicated that the benthic assemblages within and in the
vicinity of the works areas were dominated by polychaetes. All species recorded are found to be common
in Hong Kong and no rare species were observed, except for the individual of
Amphioxus Branchiostoma belcheri. The occurrence of the individual amphioxus in
the baseline survey is possibly due to random settlement via the planktonic
larval stage of B. belcheri. The very low occurrence of amphioxus
suggests that the conditions within Joss House Bay might not be suitable for
continual survival of amphioxus after settlement. As a result, the assemblages were
regarded as low to moderate ecological value.
Considering the very small extent and low to moderate ecological value
of the habitat of concern, no unacceptable impacts is
expected.
Changes
in Water Quality
Suspended Sediments
Subtidal Soft Bottom Habitat
The
subtidal soft benthos in and around the proposed
submarine facilities are considered to be of low to moderate ecological
value. Sessile organisms will be
susceptible to the effects of increased sediment loads through burial. Sediment may be deposited on the seabed
within and near the works areas during dredging due to the dispersion of
sediments. Temporary impacts are
expected to be the largest in the immediate vicinity of the dredging works
(i.e. in the mixing zone) when the works are underway, while impacts on the
wider marine environment (>1 km away from the works area) expected to be
very low due to gradual deposition of SS over a short distance.
Owing
to the small scale and the low level of sedimentation associated with the
marine dredging works, the indirect disturbance on benthic assemblages in the
vicinity if the works area are expected to be of low severity and
localized. With the assumption that the
temporarily affected subtidal soft bottom habitats
due to marine dredging works could be recolonised by
fauna which is typical to that area, the temporary disturbance to these low to
moderate ecological value assemblages is not considered to be unacceptable.
Subtidal Hard Bottom Habitat (including Corals)
No
rare species was found in the subtidal hard bottom
habitat in the vicinity of the submarine intake and outfall. The shallow subtidal
hard bottom habitat is regarded as low to moderate ecological value. The transient nature of any increase in
suspended sediment arising from marine dredging works will have no unacceptable
adverse impacts on this habitat and this is confirmed by results of the water
quality modelling (Section 6.8.1).
Intertidal
Habitats
Intertidal
habitats within the Study Area which can be affected by the marine dredging
works include natural rocky shore, sandy shore and artificial seawall. Sediment dispersion modeling results predicts
that the SS elevations due to marine dredging will be transient and will be
confined to the proposed works area.
Thus, it is expected that unacceptable impacts from elevated SS levels
to the intertidal assemblages.
Coastal
/ Marine Water Habitats
The
minor marine dredging works may cause deterioration to water quality, which may
potentially impact marine ecological resources.
Information from the water quality impact assessment (Section 6.8.1) indicates that indirect
impacts are not predicted to impact these resources adversely as the elevation
of suspended sediments due to sediment plume will be transient and localized to
the works area. As a result,
unacceptable impacts to open water habitats due to increased suspended sediment
levels will not occur.
Dissolved Oxygen
The
assessment examining potential impacts of elevated SS levels associated with the
proposed marine dredging works showed that the impacts are likely to be minor, localised to the mixing zone and transient. Consequently, DO depletion as a result of
dispersion of sediment plumes associated with marine works of the Project is
expected to be within acceptable levels and its effect on marine ecological
resources is also likely to be very limited.
Contaminant Release
Owing
to the unpolluted nature of the seabed sediment within the dredging area (see Section 8 of this EIA Report), unacceptable
water quality impacts due to the potential leaching of metals and micro-organic
pollutants from the disturbed sediments into the water column are not expected
to occur.
Vessel
Operational Discharges
As
discussed in Section 6, construction
vessels have the potential for the liquid discharges of uncontaminated deck
drainage, potentially contaminated drainage from machinery spaces, and
sewage/grey water. These waste streams
are all readily amenable to control as part of appropriate practice on
vessels. Possible impacts associated
with construction vessel discharges are therefore considered to be negligible.
Site
Runoff from Land-based Construction Activities
Discharges
and runoff from the land-based sites during the construction phase,
particularly during the site formation, excavation and backfilling works, will
contain suspended solids which could be a source of water pollution, causing
short-term degradation of habitat quality.
However, considering that the scale of the construction works and with
effective implementation of good site management practices as well as
mitigation measures mentioned in Section
6, site run-off is not predicted to have an adverse impact on the natural
coastline.
In
summary, unacceptable impacts (elevated SS, nutrient and contaminant levels and
DO depletion) on sensitive receivers from sediment release associated with
dredging works are not expected to occur.
Potential impacts arising from vessel operational discharges and
land-based site runoff during construction stage are also considered to be
negligible.
Operation Phase
Impacts
due to operational effluent discharge from the desalination plant on marine
ecological resources are not expected as the discharge should satisfy the
relevant requirements of WPCO-TM effluent
discharge standards (details refer to Sections
6 and 7) and in compliance with
the relevant assessment criteria which are of relevance for the protection of
marine ecological resources (see Section
6). No unacceptable impacts
associated with the release of residue chemical constituents are thus
anticipated.
The major impacts during operation phase would be perturbations
to key water quality parameters from the discharge of hypersaline water from
reverse osmosis process. Changes in the
hydrodynamic regime and water quality due to the discharge of RO concentrate
from the Project are anticipated. A
maximum of 464,000 m3/day of saline water from the proposed
desalination plant would be discharged to the coastal water.
According to
the modelling results in Section 6, a
likely effect of the discharge of RO concentrate at outfall would be the
elevation in salinity. However, there
are only limited reports available indicating that brine discharges have led to
reductions in the abundance and diversity of marine ecological assemblages (). While larger, mobile biota such as fish would
be able to avoid the zone of influence, invertebrates and some fish species
inhabiting bottom sediments within the predicted near field mixing zone would
be impacted (). The brine solution discharged into the sea
from the desalination plant has the potential to alter marine assemblages in
the near field mixing zone as a results of the
influences on the following aspects () ():
·
Development of species and the propagation activity and faster
individual growth;
·
Survival of larval stages of animals and life expectancy (shorter
or longer generation time);
·
Population density of organisms (higher or lower population growth
rate); and,
·
Breeding of species and reproductive traits.
According to the water quality impact
assessment in Section 6, the salinity
would be approximately 2 times higher than the ambient condition. As per the modelling results in Section 6, the concentrated saline water
would be localized closely to the submarine outfall area with a small mixing
zone in approximately 0.09 ha (approximately 30 m x 30 m = 900 m2 =
0.09 ha). The baseline survey results
suggest that corals are recorded at all dive sites along the shoreline of Tit
Cham Chau, Kwun Tsai and Tung Lung Chau, whilst no
coral was recorded at the direct footprint of submarine intake and outfall
diffusers which are soft substrata.
Also, the plume of discharge is offshore and localized in nature and
will subsequently be diluted and dispersed to the level as the feedwater. Thus, the
impact would be localized and confined to close proximity of the submarine
outfall. Besides, marine
organisms recorded during field surveys are widely distributed in local waters
and could be recorded in the more saline eastern waters. It is expected that these species are able to
adapt to changes in salinity. Therefore, ecological impact on the identified
marine habitats and their associated fauna due to the intake of
seawater/discharge of saline water would be insignificant.
Apart from the
salinity change, anti-scalants in the RO concentrate
discharge, when discharged at high concentration, may be toxic to ecological
resources. Based on the acute
toxicity test of antiscalants on amphipods Gammarus pules and Gammarus roseli, the derived EC50 is
ranged between 4 – 8.7 mg/L (). Another toxicity test on sea urchin Arbacia punctulata
gametes and embryos found that abnormal embryo development was observed at
concentration > 100 mg/L (i.e. Lowest Observable Effect Concentration, LOEC)
() . With reference to the modelling results in Section 6, the maximum predicted level
of anti-scalants in the RO plume at Tit Cham Chau,
where the coral community was recorded, is below the assessment criteria (0.362
mg/L), which is also well below than the EC50 and LOEC derived in
the published literatures. Therefore, no
unacceptable adverse impact is anticipated on the coral communities and marine
ecological resources in the vicinity of this Project.
9.6.1
Terrestrial
Ecology (Construction Phase Only)
Habitat
Loss/Disturbance
From
the information presented in Section
9.5.2, overall ecological impact associated with habitat loss/disturbance
is considered to be low. An evaluation
of habitat loss for each affected habitat within the areas for desalination
plant and slope mitigation works is provided in Tables 9.3 to 9.7.
Mixed
Woodland
Approximately
0.61 ha and 0.18 ha of mixed woodland will be lost/disturbed due to the
construction works of the desalination plant and slope mitigation works,
respectively. However, the overall
unmitigated impact of habitat loss on mixed woodland is considered to be low
due to the small size of the affected area of low to moderate ecological value
and the fact that no unacceptable impacts on flora and fauna species of
conservation interest is anticipated
(see Table 9.3).
Table 9.3 Impact of Habitat Loss on Mixed Woodland during Construction
Phase
|
Evaluation Criteria
|
Mixed
Woodland – Desalination Plant
|
Mixed
Woodland – Slope mitigation works area*
|
|
Habitat Quality
|
The habitat quality
is low to moderate.
|
|
Species of
Conservation Interest
|
No plant or fauna
species of conservation interest
(Refer to Section 4 of Annex 9A for the flora and fauna species of conservation interest
recorded within the habitat of mixed woodland but outside the Project Site.)
|
|
Size/Abundance
|
Permanent loss
approximately 0.61 ha.
|
Affected areas of
approximately 0.18 ha.
|
|
Duration
|
The impact will
persist during construction and operation phases.
|
|
Reversibility
|
The loss of habitat
is permanent and not reversible.
|
The loss of
naturalness is partially reversible.
|
|
Magnitude
|
The scale of the
habitat loss/ disturbance and impact is small in the context of the
surrounding similar habitat, flora and fauna.
|
|
Overall Impact
Before Mitigation
|
Low
|
Low
|
*This refers to
the area to be subject to direct impact from slope mitigation works, including
rock slope stabilization area, soil nailing area and flexible barriers.
Shrubland/grassland
Approximately
0.38 ha and 0.31 ha of shrubland-grassland will be
lost/disturbed due to the construction works of desalination plant and slope
mitigation works, respectively. The
protected plant species Pachystoma pubescens and
Pectellis susannae were
recorded at the study area of slope mitigation works within the uphill area of
Clear Water Bay Country Park; however the works area for slope mitigation has
avoided the uphill area of the Clear Water Bay Country Park where the protected
plant species are recorded, thus there is no direct conflict of these plant
species (Figure 7e of Annex 9A). One flora species of conservation interest Marsdenia lachnostoma
was recorded along the proposed alignment of the flexible barriers within the
Clear Water Bay Country Park (Annex 9B). As such, the overall unmitigated impact of
habitat loss/disturbance on shrubland/grassland in
slope mitigation works area and desalination plant is considered to be low to
moderate and low, respectively, due to the small size of the affected area of
low to moderate ecological value (see Table 9.4).
Table 9.4 Impact of Habitat Loss on Shrubland-grassland
during Construction Phase
|
Evaluation Criteria
|
Shrubland/grassland – Desalination Plant
|
Shrubland/grassland – Slope mitigation works area*
|
|
Habitat Quality
|
The habitat quality
is low to moderate.
|
|
Species of
Conservation Interest
|
No plant and fauna
species of conservation interest
(Refer to Section 4 of Annex 9A)
|
Plant species of
conservation interest include Marsdenia lachnostoma (Refer to Annex 9B).
Fauna species of conservation interest
included Collared Scops Owl (Refer to Section
4 of Annex 9A for the fauna
species of conservation interest recorded within the habitat of shrubland/grassland but outside the Project Site)
|
|
Size/Abundance
|
Permanent loss
approximately 0.38 ha.
|
Affected area of
approximately 0.31 ha.
|
|
Duration
|
The impact will
persist during construction and operation phases.
|
|
Reversibility
|
The habitat loss is
permanent and not reversible.
|
The loss of
naturalness is partly reversible.
|
|
Magnitude
|
The scale of the
habitat loss and impact is small in the context of the surrounding similar
habitat, flora and fauna.
|
|
Overall Impact
Before Mitigation
|
Low
|
Low to moderate
|
|
|
|
|
*This refers to the
area to be subject to direct impact from slope mitigation works, including rock
slope stabilization area, soil nailing area and flexible barriers
Urbanised/ Disturbed Area
The
habitat loss of urbanised/ disturbed area of 5.24 ha
is anticipated for the development of desalination plant. No plant
species of conservation interest was recorded within the affected area. In view of its negligible ecological value
and artificial nature that results in a high recreatability,
it is considered that the habitat loss of urbanised/
disturbed area would be of negligible significance (see Table
9.5).
Table 9.5 Impact of Habitat Loss on Urbanised/Disturbed Area during
Construction Phase
|
Evaluation Criteria
|
Urbanised/
Disturbed Area
|
|
Habitat Quality
|
The habitat quality
is very low.
|
|
Species of
Conservation Interest
|
No plant species of
conservation interest was recorded within the affected area. Black kite was recorded within the affected
area.
(Refer to Section 4 of Annex 9A for the flora and fauna species of conservation interest
recorded within the habitat of urbanised/ disturbed
area but outside the Project Site.)
|
|
Size/Abundance
|
Loss of
approximately 5.24 ha for the desalination plant
|
|
Duration
|
The impact will
persist during construction and operation phases.
|
|
Reversibility
|
The loss of this
habitat is considered reversible since the desalination plant is also part of
urbanised/disturbed area.
|
|
Magnitude
|
The scale of the habitat
loss and impact is moderate in the context of the surrounding similar
habitat, flora and fauna.
|
|
Overall Impact
Before Mitigation
|
Negligible
|
Wasteland
Approximately
3.78 ha of wasteland will be lost due to the construction works. The overall unmitigated impact of habitat
loss on wasteland is considered to be negligible due to the size of the
affected area, low ecological value and high recreatibility of the habitat, and the fact that no flora
species of conservation interest was recorded during the surveys (see Table
9.6).
Table 9.6 Impact of Habitat Loss on Wasteland during Construction Phase
|
Evaluation Criteria
|
Wasteland
|
|
Habitat Quality
|
The habitat quality
is low.
|
|
Species of
Conservation Interest
|
No plant species of conservation interest
was recorded within the affected area.
Fauna species of conservation interest, White-throated Kingfisher,
Black-crowned Night Heron and Lesser Coucal, were
recorded (Annexes 9A and 9B).
(Refer to Section 4 of Annex 9A for the flora and fauna species of conservation interest
recorded within the habitat of wasteland but outside the Project Site.)
|
|
Size/Abundance
|
Loss of
approximately 3.78 ha for the desalination plant
|
|
Duration
|
The impact will
persist during construction and operation phases.
|
|
Reversibility
|
The loss of this
habitat is considered reversible since the desalination plant is also part of
urbanised/disturbed area.
|
|
Magnitude
|
The scale of the habitat
loss and impact is moderate in the context of the surrounding similar
habitat, flora and fauna.
|
|
Overall Impact
Before Mitigation
|
Negligible
|
Man-made
Watercourse
Approximately
0.18 ha of 0.7 km man-made watercourse will be lost due to the construction
works of desalination plant. The overall
unmitigated impact of habitat loss on watercourse is considered to be low due
to the small size of the affected area, low ecological value and high recreatability of the habitat, and the fact that no flora
and fauna species of conservation interest was recorded during the surveys
(see Table 9.7).
Table 9.7 Impact of Habitat Loss on Man-made Watercourse during
Construction Phase
|
Evaluation Criteria
|
Man-made Watercourse
|
|
Habitat Quality
|
The habitat quality
is low.
|
|
Species of
Conservation Interest
|
No species of
conservation interest was recorded within the affected area. (Refer to Section 4 of Annex 9A
for the flora and fauna species of conservation interest recorded within the
habitat of Man-made Watercourse but outside the Project Site.)
|
|
Size/Abundance
|
Loss of
approximately 0.18 ha (0.7 km) for the desalination plant.
|
|
Duration
|
The impact will
persist during construction and operation phases.
|
|
Reversibility
|
The loss of this
habitat is considered reversible since the watercourse is artificial in
nature.
|
|
Magnitude
|
The scale of the habitat
loss and impact is small in the context of the surrounding similar habitat,
flora and fauna.
|
|
Overall Impact
Before Mitigation
|
Low
|
9.6.2
Impact on Recognized Sites of Conservation
Importance
The
desalination plant site is outside of the boundary of the Clear Water Bay
Country Park. The slope mitigation works
of the Project will be undertaken in the woodland and shurbland/grassland
habitats within the Clear Water Bay Country Park. Given the relatively low to moderate ecological value of most of the affected
area and the small scale of the Project within Clear Water Bay Country Park,
potential impact on the Sites of Conservation Importance is considered to be
low to moderate.
9.6.3
Impact on Species of Conservation Interest
One flora and
five bird species of conservation interest were recorded within the footprints
of the desalination plant and slope mitigation works. Considering the mobility of bird species and
the availability of similar habitats in the surrounding environment, the potential
impact on bird species is considered to be minimal. However, the construction of flexible
barriers has the potential to directly affect the flora species of conservation
interest Marsdenia lachnostoma
recorded along the indicative alignment of the flexible barriers. Avoidance and mitigation is required.
9.6.4
Habitat Fragmentation and Isolation
The
construction works of the desalination plant will mainly be conducted along
existing roads and within reclamation area, no habitat fragmentation and isolation
impact is therefore expected. For the
slope mitigation works, the affected mixed woodland and shrubland/grassland
habitats are located at the edge of the natural habitats within country park
area with relatively low diversity and abundance of fauna species. In view of the small scale (0.49 ha) of the
slope mitigation works area and the availability of surrounding similar
habitats, the potential impact of habitat fragmentation and isolation on
associated wildlife utilising the affected habitats is considered to be
minimal.
9.6.5
Noise, Human Activities and Other Disturbances
Increased
human activities and disturbances due to the Project construction have the
potential to affect the surrounding natural habitats and the associated
wildlife. These potential impacts are expected to be low given that
regular checks on construction practices and boundaries will be conducted.
9.6.6
Marine
Ecology
The
following section discusses and evaluates the impacts to marine ecological
resources as a result of the resources identified in the previous
sections. Based upon the information
presented above, the significance of the marine ecological impact associated
with the construction and operation of the submarine outfall has been evaluated
in accordance with the EIAO-TM (Annex 8, Table 1) as follows.
Habitat Quality: Direct
impacts are only predicted to occur to habitat of low to moderate
ecological value (i.e. subtidal soft bottom habitats)
at the footprint of minor marine dredging site.
The selection of trenchless method will avoid direct impacts to
artificial seawall and subtidal hard bottom habitats
which are of low and low to moderate ecological values, respectively. Operation phase impacts are not expected to
impact habitats of high ecological value.
Species:
Based on literature and supplementary baseline surveys, some isolated
coral colonies are found on subtidal hard bottom
habitats. However, due to their location
is not under the footprint of marine dredging site, no significant construction
or operation phase impacts are expected to these sensitive receivers. Thus, no significant construction or
operation phase impacts are expected.
Size:
The maximum size of loss of subtidal soft
bottom habitats due to the marine dredging activity is approximately 0.11
ha. The impact to such a small area of
low to moderate ecological value of benthic assemblages is expected to be
acceptable.
Duration: The marine works will
approximately continue for a period of 18 months. Increases in suspended sediments are expected
to be low and transient, and within acceptable environmental limits. The operation phase of the submarine outfall
diffuser will be long-term but the impacts to marine ecological resources would
be acceptable.
Reversibility: Impacts to the benthic
assemblages on the subtidal soft bottom habitats
which are regarded as low to moderate ecological value within the marine
dredged areas are irreversible.
Disturbance from marine construction activities and associated water
quality changes are expected to be relatively short term and recolonisation of the disturbed areas is expected to occur.
Magnitude: No unacceptable impacts to
marine ecological resources are predicted to occur. Operation phase impacts are not expected to
cause any adverse impacts and are considered to be of low magnitude.
The
impact assessment presented above indicates that no unacceptable impacts to
various marine ecological resources mentioned in the above sections would be
expected.
General
In
accordance with the guidelines in the EIAO-TM
Annex 16 on ecological impact assessment, the policy adopted in this EIA for
mitigating significant impacts to ecology, in order of priority, is:
·
Avoidance:
Potential impacts should be avoided to the maximum extent practicable by
adopting suitable alternatives;
·
Minimisation:
Unavoidable impacts should be minimised by taking appropriate and
practicable measures such as constraints on intensity of works operations or
timing of works operations; and
·
Compensation:
The loss of important species and habitats may be provided for elsewhere
as compensation. Enhancement and other conservation measures should always be
considered whenever possible.
Avoidance
The
above impact assessment demonstrates that the Project will minimize
encroachment onto any habitat of low to moderate ecological value during its
construction, particularly to those key ecological sensitive receivers such as
the Clear Water Bay Country Park. Direct
impacts on plant and wildlife species of conservation interest will also be
avoided.
For
slope mitigation works within the Clear Water Bay Country Park, to avoid tree
felling and damages to trees, the exact locations of the flexible barrier
foundation plates, soil nails and rock dowels can be adjusted during detailed
design, and a setback distance from existing trees is recommended to be
maintained as far as practical. Pruning
of tree canopies along the alignment of the flexible barriers shall be limited
to a minimum.
In
addition, the alignment of flexible barriers shall be optimized to preserve all
flora species of conservation interest and minimize potential impact to
existing vegetation as far as practicable.
All individuals of Marsdenia lachnostoma within the slope mitigation areas shall be
retained in-situ, by positioning the
alignment of flexible barriers at a minimum 1.5m in a radius away from these
individuals. The implementation of this
mitigation measures is presented in Figure 9.1 as an illustration. The
following practices shall be implemented as far as practicable for the
protection of flora species of conservation interest:
·
Temporary
fencing will be installed to fence off the concerned species either in groups or
individually within the works area and in its close proximity to prevent from
being damaged and disturbed during construction. A sign identifying the site shall be attached
to the fence and flagging tape shall be attached to the individuals to visualize
their locations.
·
Induction
training shall also be provided to all site personnel in order to brief them on
this flora of conservation interest including the locations and their
importance.
·
The
resident site supervisory staff will closely monitor the conditions of
concerned individuals during construction of flexible barriers in the close
proximity.
Construction
impacts to marine ecological resources have largely been avoided by optimizing
the length and alignment of the submarine facilities to avoid key ecologically
sensitive areas, and by applying the trenchless method for installing submarine
intake and outfall and through proper planning design and execution of the
works (i.e. optimisation of project construction
schedule/ sequence, using good engineering/ industry practice, timely
completion of construction works to reduce impact duration, etc.).
Indirect
impacts on marine sensitive receivers due to the dispersion of sediment plume
can be avoided as the dredging works will be designed to confirm compliance
with the assessment criteria at sensitive receivers and control water quality
impacts to within acceptable levels, and water quality mitigation measures will
be developed and implemented when required to further avoid/ reduce potential
impacts (See Section 6).
To
summarise, this initial assessment of impacts
demonstrates that impacts will largely be avoided during the construction and
operation of the proposed Project, particularly to the key terrestrial and
marine ecological sensitive receivers through the avoidance of direct and
indirect impacts to ecological sensitive habitats and wildlife/ species of
conservation interest.
Minimisation
As
part of the site selection process, mixed use of flexible barrier, soil nail
and rock slope stabilization have been adopted for slope mitigation works. This would minimise
the overall footprint and hence habitat loss and vegetation removal associated
with the landslide mitigation works.
Affected habitats within the Clear Water Bay
Country Park will be reinstated by hydro-seeding and planting of climbers and
native shrub seedlings where practicable upon completion of the slope
mitigation works. The detailed design of
the soil nailing works and alignment of flexible barrier should take into consideration
to provide the best opportunities for planting success such as spacing of soil
nails. The selection of native shrub
seedlings should match the original natural habitat for proper reinstatement.
Trenchless
construction method will be considered wherever necessary for laying the
proposed water mains. The present
alignment of freshwater water mains overlaps with the main roads and accesses
at Tseung Kwan O.
The sites of the proposed desalination plant and freshwater main will be
located within disturbed area as much as practicable. Only the lands in close vicinity to developed
area will be taken to minimise the habitat
fragmentation and isolation arising from the construction of Project.
The
use of trenchless method is particularly suitable for the construction of the
proposed submarine intake and outfall from the desalination plant because
marine dredging would be minimal (the total dredging extent at intake and
outfall is estimated to be 0.11 ha) compared with conventional submarine outfall
pipeline installation methods (total dredging extent is about 1.2 ha), during
which a trench in seabed is needed to be formed along the entire alignment and
backfilling is required after pipe laying.
The trenchless method will minimise the
potential impacts on water quality and marine ecological resources.
To
minimize the other disturbances of the construction works to the surrounding
habitats and associated wildlife, the following appropriate construction
practices should be implemented as far as practicable.
·
Erect
fences along the boundary of the works area before the commencement of works to
prevent vehicle movements and encroachment of personnel onto adjacent
areas;
·
Regularly
check the work site boundaries to ensure that they are not breached and that
damage does not occur to surrounding areas;
·
Avoid
any damage and disturbance, particularly those caused by filling and illegal
dumping, to the surrounding habitats through proper management of waste
disposal;
·
Reinstate
temporarily affected areas, particularly the habitats of mixed woodland and shrubland-grassland immediately after completion of
construction works, through on-site hydro-seeding and tree/shrub seedling
planting. The tree/shrub species will be chosen with reference to
those in the surrounding area (See Annex 9A); and
·
Closed
grab dredger will be used to dredge down about -11mPD which is approximately 6m
below the current seabed and there will be no excessive dredging.
Compensation
Since
habitat loss due to other land-based construction and marine dredging works for
laying the submarine intake and outfall of the Project only occurs on the
habitats of low or low to moderate ecological value where no species of
conservation interest will be lost, ecological compensation is not required.
Information from publicly available
sources suggested that the construction/ implementation programmes of the major
projects identified in Section 3.8
would coincide with the construction of this Project. These projects either do not have a
marine element or are at large separation distances (> 3 km) from this
Project. It is noted from the approved
EIA reports of these projects that their impacts are not expected to be
significant for ecological resources in this part of Hong Kong. Consequently,
no unacceptable cumulative impacts is
anticipated. In addition, a discussion
of potential cumulative water quality impacts arising from concurrent projects
is provided in Section 6. Since it is unlikely for water quality mixing
zone of this Project to overlap with those of other concurrent projects in this
part of Hong Kong, it is thus concluded that cumulative impacts on water
quality impacts and consequently on fisheries are not predicted to occur.
Given
that the no operational impacts on ecological resources are anticipated from
the concurrent projects, operational cumulative impacts with other development
in and around Tseung Kwan O Area 137 are not
predicted to occur.
As
a result of land-based construction activities, up to 0.61 ha mixed woodland,
0.38 ha of shrubland/grassland, 3.78 ha of wasteland,
0.18 ha (0.7km) ha of man-made watercourse and 5.24 ha of urbanised/disturbed
area would be permanently lost due to the construction of the desalination
plant. Within the slope mitigation works
area, approximately 0.18 ha mixed woodland and 0.31 ha of shrubland-grassland
would be affected. The affected habitats
are considered to be of very low, low or low to moderate ecological
values. With the implementation of the recommended mitigation
measures discussed in Section 9.7, it
is anticipated that all potential ecological impacts will
be reduced to an acceptable level.
Therefore, no adverse residual impact due to the construction of
proposed desalination plant, freshwater rising main and slope mitigation works
is expected from the aspect of terrestrial ecology.
In
terms of marine-based construction works, approximately 0.11 ha of subtidal soft bottom habitats of low to moderate ecological
value will be lost due to the marine dredging activity. Since the loss of subtidal
soft bottom habitats is very small in size in the context of surrounding
similar habitat, therefore no unacceptable residual impacts are anticipated
from the aspect of marine ecology.
9.10
Environmental Monitoring &
Audit (EM&A)
Terrestrial
Ecology
The
assessment presented above indicates that unacceptable construction and
operation phase impacts are not expected to occur to terrestrial ecological
resources. The implementation of the
ecological mitigation measures described in Section
9.7 will be inspected regularly as part of the EM&A procedures during
the construction period.
At
the detailed design stage prior to the commencement of the slope mitigation
works, a vegetation survey shall be carried out at the slope mitigation areas
within the Clear Water Bay Country Park to assess the condition and identify
the location of each individual of Marsdenia lachnostoma and other flora species of conservation
interest that may be directly affected by the construction works. A specification for fencing and demarcating
individuals of Marsdenai lachnostoma
(or other flora species of conservation interest, if found) adjacent to the
proposed alignment of the flexible barriers will be prepared to protect the
species, and a detailed specification describing the exact locations of the
flexible barrier foundation plates, soil nails and rock dowels will be prepared
to illustrate how the setback distance from existing trees would be implemented
for tree avoidance.
No
terrestrial ecology specific operational phase monitoring is considered
necessary.
Marine
Ecology
Construction Phase
During
the construction phase, the following EM&A measures will be undertaken to
verify the predictions in the EIA and ensure the environmental acceptability of
the construction works. Water quality
impacts will be monitored and checked through the implementation of a Water
Quality EM&A programme (refer to Section 6 for details). The monitoring and control of water quality
impacts will also serve to avoid unacceptable impacts to marine ecological
resources.
Operation Phase
To
ensure compliance to the effluent standard specified in Section 6(or other standard stipulated in the WPCO Discharge
Permit), regular monitoring of effluent quality is recommended during normal
operation. The monitoring and control of
water quality impacts will also serve to avoid unacceptable impacts to marine
ecological resources.
Details
environmental monitoring procedures and audit requirements are provided in the
standalone EM&A manual.
This
Section of the EIA has described the potential terrestrial and marine
ecological impacts associated with the construction and operation of the
Project in Tseung Kwan O Area 137. The purpose of the assessment is to evaluate
the acceptability of predicted impacts to terrestrial and marine ecological
resources and sensitive receivers.
Findings of literature review and dedicated baseline field surveys have
provided information for the evaluation of species of conservation interest and
ecological importance of various habitats within the Study Area as well as in
the Project Site.
A
total of 11 habitat types were identified within the Study Area. They are terrestrial habitats (i.e. mixed
woodland, plantation, shrubland-grassland,
agricultural land, wasteland, watercourse and urbanised/disturbed
area) and coastal habitats (i.e. rocky shore, sandy shore, subtidal
hard and soft bottom habitats and artificial seawall habitat). All of the habitats are of very low or low
ecological value, except for mixed woodland, shrubland/grassland,
watercourse (natural section) and subtidal hard and
soft bottoms (marine water) of low to moderate ecological value. Apart from this, the Clear Water Bay Country
Park is the recognized ecologically important / sensitive sites are located
within the Study Area.
Regarding
to species of conservation interest, nine flora species, one mammal species, 14
bird species, 5 butterfly species, one aquatic fauna, amphioxus from subtidal soft bottom habitat and hard corals from the subtidal hard bottom habitat were recorded during the field
baseline surveys. Except for the flora
species Marsdenia lachnostoma
was recorded within the slope mitigation works area, none of the other species
were found residing within the Project Site.
Mitigation measures are recommended to avoid and minimize potential
impact on the aforementioned flora species of conservation interest in the
slope mitigation works area. Although
bird species of conservation interest and an unoccupied bird nest were recorded
within the Project Site and slope mitigation works area, these species have
high level of mobility and no sign of nursery or breeding activities of these
species were found within the Project Site area, thus no direct impact on these
species of conservation interest is anticipated.
During the construction phase,
construction activities may cause direct ecological impacts including habitat
loss and vegetation removal, whereas indirect impacts on wildlife include disturbances and changes in water
quality. Potential impacts of increased human activities and other disturbances
due to the Project construction would not be significant provided that regular
checks on construction site practices and boundaries will be conducted. In addition, in the view of the availability of surrounding similar habitats, the potential
impact on wildlife especially on the species of conservation interest as a
result of habitat fragmentation and isolation is considered to be minimal.
For
marine ecological impact, habitat loss of subtidal
soft bottom habitat which is of low to moderate ecological value (within the
Project footprint) will also arise from minor marine dredging activity for
installing the submarine facilities and there will be potential burial of
benthic organisms. Intertidal and subtidal habitat (including corals) will be impacted
temporarily due to the deterioration of water quality arising from minor marine
dredging works.
With
the implementation of the proposed mitigation measures, no adverse residual
impact due to the land-based and marine-based construction of proposed
desalination plant, slope mitigation works, freshwater rising main and
submarine intake and outfall pipelines is anticipated.