5.2 EM&A Requirements during Construction Phase5-1
5.3 EM&A Requirements during Operational Phase5-5
5.4 Implementation Schedule5-6
List of Appendices
Appendix
1 Implementation Schedule of
Recommended Mitigation Measures
5.1.1 The potential ecological impact from
the proposed drainage improvement project at Yuen Long has been evaluated in
accordance with the applicable Technical Memorandum of the EIAO, and the works
in Ha Che and Lin Fa Tei will unavoidably affect the watercourse habitat and
potentially the local population of two endemic freshwater crab species Somanniathelphusa
zanklon and Cryptopotamon
anacoluthon in the
Kam Tin area.
5.1.2 A range of mitigation measures
including good site management, scheduling of the staged work program to avoid
breeding season of the sensitive ecological resources, as well as translocation
of two endemic freshwater crab species have been recommended to avoid or minimize
the identified impact within or in the vicinity of the work areas. The following section details the EM&A
requirements for the ecological mitigation measures.
Project Management and Site Practice
5.2.1 The section
of watercourse with construction activities should be hydrologically isolated
from the rest of the watercourse as far as practicable (except discharge of
treated runoff); and it should
be commenced from downstream and progresses toward the upstream area and the reinstatement
work especially the planting of riparian vegetation should also be undertaken
in stages and commenced as soon as the hardscape work completed in the working section
as such to fast track the reinstatement work, minimize the spatial disturbance
and shorten the temporal ecological impact
5.2.2 The following good site practice
should be implemented to avoid or minimize the potential disturbance to the
habitats and wildlife inhabited within or adjacent to the work sites, and they
should be audited regularly as part of the routine site inspection undertaken
by the ET:
· Effective implementation of an Environmental
Management Systems in accordance with the ISO 14001 for all work sites;
· Effective implementation of
mitigation measures recommended for dust suppression, noise reduction, as well
as water quality and waste management as detailed in other sections of this EIA
report
· Effective implementation of the Tree
Preservation Measures as detailed in the guidelines published by the Tree Management
Office
· Staff awareness training on the
ecological importance of the riverine habitats and inhabited wildlife, as well
as briefing on the mitigation measures recommended in this report
· Well defined and fenced Work Area to
prevent intentional or accidental encroachment or trespassing into the adjacent
habitats for access, parking and operation of plants/machineries, as well as stockpiling
of construction material or waste;
· Fence off any potentially
ecologically sensitive resources within the work area with warning signpost;
· Water diversion by means of
submerged water pump should be avoided as far as practicable to prevent
obstruction of wildlife movement along the channel
· Waste and refuse should be stored or
dumped in appropriate receptacles and on-site burning of waste should be
strictly prohibited;
· Excavated material should be properly
covered or promptly disposed, and opportunities to stockpile and backfill the
topsoil should be explored
· No chemical should be stockpiled on-site
until absolutely necessary
· On-site maintenance of
plant/machineries/vehicle should be avoided as far as practicable
· Silt/ Sediment/ Oil traps should be
installed to avoid direct discharge of effluent or site run-off
· Regular ecological checks
· Cut down of vegetation during site
clearance should be in stages before groundwork takes place as such to disperse
any wildlife that is sheltering in the immediate area; and
· Minimise vehicle access
Mitigation Measures to Avoid Potential Impact to Cheung Po EIS
5.2.3 The construction work in Tai Wo should
be scheduled in the dry season and sand bags or other similar facilities should
be placed along the southern boundary of the work site to prevent any
accidental discharge of untreated effluent into the buffered grassland and EIS
under adverse weather condition. in addition, discharge of any treated or untreated
effluent, either by means of soakaway or direct discharge to nearby waterways,
should be directed away from the grassland buffer and the EIS. The above measure should be audited regularly
as part of the routine site inspection undertaken by the ET.
Preservation of Faunal Species of Conservation Interest
5.2.4 Two freshwater crab species of
conservation concern were recorded within the work sites during the ecological
baseline survey, including the Somanniathelphusa zankloni recorded at Lin Fa Tei and Ha Che; as well as the Cryptopotamon anacoluthon recorded in the upstream area at Ha
Che. Both species are endemic to Hong
Kong and considered to be “Endangered” and “Vulnerable” by the IUCN respectively.
The construction activities of the project will unavoidably disturb their
natural habitats and potentially causing a direct loss of these two species
because of their limited mobility.
5.2.5
Although
measures such as undertaking the site clearance and ground work in stages to
disperse the wildlife inhabited in the immediate area have been proposed,
because of the ecological significance of these two species, it is recommended
to conduct pre-construction survey to check any freshwater crab species
of conservation concern within the site boundary and the cut-off section of the
project’s watercourse at Lin Fa Tei and Ha Che. Should any be found, these
species should be captured and translocated to suitable habitat free from any
development pressure and in close
proximity to the project sites wherever feasible, and the post-translocation
monitoring of the translocated freshwater crabs should cover at least 12
months.
5.2.6 An Ecologist with relevant experience
in freshwater habitats should prepare a “Freshwater Crab Translocation Plan”
for the approval of AFCD. The Plan
should detail the methodology and logistics of the capture and translocation program, including the
frequency and timing of field survey, details of the receptor site(s), logistics,
equipment and measures to be deployed during the process, as well as the requirements
for the post- translocation monitoring. In addition, since
the drainage work will be undertaken section-by-section, it is also recommended
that, before the commencement of construction work in a new section, the site
should be inspected by the ecologist to confirm no inhabitation of these two
freshwater crab species, and if found they should be promptly captured and translocated
in accordance with the approved translocation plan.
5.2.7 The selected receptor site(s) should
match with the habitat requirements of these two freshwater crab species and
free of any development pressure to ensure their long term survivorship after translocation. Despite published information of the natural
habitat of these two species is very limited (Ng and Dudgeon, 1992; Dudgeon,
1999; Stanton and Leven, 2016 and Stanton et al., 2017), according to the
former two references, Somanniathelphusa zanklon inhabited in a
variety of lotic and lentic lowland habitats and would prefers unpolluted
riverine habitats with slow-flowing low-gradient streams, where it burrows in
mud and clay banks, as well as the roots of floating plants or the trailing
roots and stems of the riparian grasses and other vegetation. In addition, this species is omnivorous with strongly carnivorous
tendency, and prefer gastropod prey with light and fragile shells. For Cryptopotamon anacoluthon, it is most numerous in upland area where the stream
is shallow with clear, fast-flowing water, rocky substratum, as well as
accumulations of leaf-litter, in which the latter is functioned as shelter and
food source of this species.
Preservation of Plant Species of Conservation Interest
5.2.8
A
protected tree species, Aquilaria sinensis, has been recorded in the riparian
woodland within the site boundary of Sung Shan New Village. As there is no direct conflict
between Aquilaria sinensis (seedling) and the proposed works within the
site boundary of the works, this plant will be protected in accordance with
DEVB TCW No. 4/2020 Tree preservation and retained during construction.
5.2.9 Before the commencement of
construction work including site clearance within the site boundary of at Sung
Shan New Village, Lin Fa Tei and Ha Che, a baseline vegetation survey with the
aims to ascertain the location and/or the presence of any floral species of
conservation concern - including but not limited to the recorded Aquilaria
sinensis should be undertaken by an Ecologist with relevant experience in conducting
vegetation survey in Hong Kong.
Habitat Compensation for the affected Riverine Habitat
5.2.10
Minor to moderate or moderate impact from the
temporary and long term loss of certain sections of the riverine habitats at
Sung Shan New Village, Lin Fa Tei and Ha Che has been predicted and such impact should be mitigated by habitat
restoration during the reinstatement and greening of the channel bed and embankment. The EIA report recommended that the wildlife habitat lost to the Project
should be restored during the reinstatement of the widened channel, in particularly
the riverine habitats of the two endemic freshwater crabs lost to the project
in Lin Fa Tei and Ha Che, and a Habitat Creation and Management Plan prepared
by a collaboration of the Engineer, an Ecologist, as well as a Landscape Architect
should be prepared to detail the
approach and design features that could facilitate and promote the establishment
of riparian vegetation and colonization of the freshwater crab and other
wildlife.
5.2.11
In order to ensure the reinstated habitat could
compensate the loss of the important riverine habitat, a Habitat Creation and Management
Plan, detailed with the approach and design features that could facilitate and promote
the colonization of the freshwater crab and other wildlife after the reinstatement
work, should be prepared with a collaboration of a drainage engineer, an ecologist,
as well as a landscape architect, and submitted to the AFCD for review and
approval before the commencement of the construction works. In addition, the Habitat Creation and Management
Plan should also detail the monitoring program to monitor the physical
environment of the restored habitat including the water quality, water current,
as well as the establishment of riparian vegetation and the biota assemblage
recolonize in the reinstated channel.
Instream
5.2.12
The
channel bed should be laid with natural substrate composed of a mix of particles
of different grain size, i.e., ranged from sand to boulder as far as the site
condition and hydraulic capacity allowed, and the original natural substrates
found within the watercourses should be retained and reintroduced to the
reinstated channels after the construction works as far as practicable. If those areas could only be created intermittently within the channel
bed, they should be physically connected by corridor fringed with vegetation,
such as low flow channel lined with natural substrate or area along the toe
zone of embankment where riparian vegetation would be established as such to minimize
the effect of habitat fragmentation and potential obstruction of wildlife movement
along the channel.
5.2.13 Elements that create roughness in
the channel, such as a sinuous channel, channel deflector and constrictor
(including gabion, boulder clusters or small vegetated island), weir, and rock
vane should be strategically installed in the channel bed to create pools, riffles
and water turbulence, trap suspended sediment as well as allow organic debris
deposition, and hence increase the complexity of the flow pattern and availability
of different types of micro-habitats and ecological niche available for aquatic
wildlife.
5.2.14 In addition, in order to enhance
fine materials holding capacity of any pools or riffles and facilitate the
colonization of the aquatic fauna, round shapes rock would be more preferable,
and the cervices formed should also be filled with a mixture of pebbles, gravel
and sand to facilitate the establishment of aquatic plants and colonization of
wildlife. Moreover, large rocks or boulders will be placed randomly on the top
layer of natural bedding to prevent the natural substrate and riparian
vegetation in the green channel from being washed away. The ground beams within
the natural bedding will also help to hold the natural bedding material in
position at the channel base, while the channel bed would not be lined with
concrete in green channel. The minimum depth of filling natural gravels/pebbles/stone/sand
is 500mm, with width equaling to full width of the channel.
Riparian Zone
5.2.15 Riparian vegetation along the toe
zone of the embankment is an important habitat for aquatic fauna, especially
the freshwater crabs recorded within the project areas where the animal is
known to dwell among the submerged vegetative part of the riparian vegetation.
Therefore, it is recommended to incorporate constantly-submerged vegetated ledge/aquatic planting
bay along the toe zone of the channel for the establishment of riparian vegetation
band, in which the
emerged or submerged parts of the latter would provide shelter and refuge for
the habitation of the Somanniathelphusa zanklon and other aquatic wildlife. Those planting area should be filled either
with geobag or a mix of fine particles, and should also be allowed trapping and
settlement of silt particle to create a muddy habitat as favored by the freshwater
crab Somanniathelphusa zanklon.
5.2.16 The upper section of the embankment
should also be vegetated with a mix of woody and herbaceous plants wherever
suitable and adequate planting space available to promote the diversity
of riparian vegetation and detritus input to the aquatic system for the aquatic
fauna colonized in the channel.
5.2.17
In
addition, in order to restore the habitat for the freshwater crab Cryptopotamon
anacoluthon which prefer shallow water accumulated with dense leaf-litter,
opportunity for tree planting within the embankment by planting bay should be
explored, and inclusion of deciduous tree species in the greening design along
the channel side, especially in the upstream section at Ha Che where the animal
was recorded, should also be included to ensure adequate leaf litter input
would be presented for the use of this species.
5.2.18
The
plant species selected for the reinstatement and restoration of the riparian
habitat should make reference to those existing species recorded in-situ and
avoid any exotic or invasive species as far as possible, and comprised with a
mix of different growth forms to increase the habitat heterogeneity and hence
the ecological niche provided by the riparian vegetation.
5.3.1 In order to minimize the potential
ecological impact associated with maintenance activities, the following
mitigation measures should be implemented during the operational phase of the
Project:
· Any maintenance activities within
the channel bed should be scheduled in the dry season and beyond the breeding
season of the freshwater crab, which normally spawning in the wet season;
· Staff awareness training on the
ecological importance of the riverine habitats and inhabited wildlife and remind
the team to minimize unnecessary disturbance to the channel;
· Vegetation maintenance of the embankment
should avoid trespassing into the channel bed as far as practicable, and should
focus on those plant species found to be too invasive or exotic in origin;
· The use of powered equipment should be
with cautions to avoid accidental spillage of oil or fuel into the water body
· If
dredging or desilting is required, it should be undertaken in dry season and
section-by-section to disperse
any wildlife that may be sheltering in the immediate area, and vehicle access
and the use of powered equipment should be minimized