6
Ecology
6.1
Introduction
6.1.1.1
The EIA Report
identified the construction of the proposed Sludge Treatment Facilities (STF)
would have minor impact on the potential breeding ground of Little Grebe in the
Assessment Area. Potential indirect construction and operation impacts to
the habitats and associated wildlife adjacent to the proposed STF would be
resulted from increased human disturbance/activities and noise due to vehicles
entering and exiting the site. Mitigation measures have been recommended
to minimize potential indirect impacts to wildlife.
6.1.1.2
With the implementation
of the recommended mitigation measures, it is anticipated that the construction
and operation for the proposed works would not result in unacceptable impacts
on ecological resources. This section describes the requirements for the
monitoring and audit of ecological impacts from the Project.
6.1.1.3
The ecological
monitoring and audit should be conducted by experienced ecologist(s) with over
seven year experience in relevant field.
6.2
Pre-construction Phase Monitoring
6.2.1.1
Pre-construction
ecological monitoring should be conducted prior to the commencement of any site
activities to investigate the current habitat condition of the Middle Lagoon
and report changes, if any, by providing an updated habitat map of the
area. The monitoring area should include the whole Middle Lagoon and area
extended 20 m from the boundary of the Lagoon. A walk through survey
should be conducted within the monitoring area to identify any changes which
have taken place since the EIA study which might have impact on the vegetation,
habitats and associated fauna.
6.3
Construction Phase Monitoring
6.3.1
Introduction
6.3.1.1
Ecological monitoring
is recommended during construction phase of the Project. The
implementation of the mitigation measures proposed under the EIA Report should
be audited as part of the EM&A procedures during the construction
period. Details of the recommended mitigation measures are listed below.
6.3.2
Measures to Avoid Mortality of Little Grebe
6.3.2.1
Breeding activities of
Little Grebe were observed within the East Lagoon. If unmitigated,
juvenile and chicks of Little Grebe with lower mobility could be killed due to
construction activities. As a precautionary measure, the whole Project
Area would be thoroughly inspected twice at the earliest two weeks before the
proposed start date of construction activities to confirm no breeding
activities of Little Grebe (including their eggs, chicks and juveniles) would
be affected by the construction activities. The inspection should be
carried out by experienced ecologist(s) with over seven year experience in the
relevant field. Agriculture, Fisheries and Conservation Department (AFCD)
should be informed in writing about the suitability of conducting construction
work in the Project Area before the commencement of any site activities.
6.3.2.2
In case breeding
activities (e.g. nests, chicks or juveniles) of Little Grebe are found during
site inspection, the programme and method of construction would be carefully
reviewed to investigate the practicable measures to minimise impact to the
breeding birds through:-
l
careful phasing of construction works,
reschedule to commence the works in the breeding area in a later stage;
l
minimisation of disturbance impact to the
breeding birds due to construction activities. As Little Grebe is very
sensitive to human movement, it is important to screen off construction works
and human activities by erection of hoarding around the breeding ground.
Sufficient buffer area should be provided between the breeding bird and hoarding
to allow for their feeding, foraging and roosting activities. The
fenced-off area would be inspected weekly to confirm the effectiveness of the
mitigation measure and allow adaptive measures to be made promptly; and
l
restriction of access to the breeding site.
No personnel should encroach the breeding area
without the written permission from the Resident Engineer.
6.3.2.3
The above mentioned
mitigation measures should be stipulated in contract documents to ensure the Contractors
are well aware of the requirement.
6.3.3
Measures to Minimize
Disturbance Impact to Wildlife
6.3.3.1
To minimize the
disturbance to wildlife due to human activities, where practicable, hoarding of
3 m high should be set up along the boundary of the works areas and associated
site access to shield the fauna in the Middle Lagoon and other natural habitats
from the disturbance impact of human activities. Fencing with climbers or
plantation would be provided, where appropriate, along the STF site boundary
and the two sides of access road to screen the surrounding habitats from the
STF operation.
6.3.3.2
The works boundaries
should not go beyond the proposed Project Area as shown in Figure 1.2. All work crews,
equipment and human activities should be confined within the designated works
area only. No personnel should encroach or wilfully disturb any wild
animals and their habitats. Traffic and human access from the western
side of the Project Area should be avoided.
6.3.3.3
To reduce noise
disturbance to habitats and wildlife adjacent to the works area, noise
mitigation measures including the use of quieter piling machinery and
construction plants should be implemented to lower the noise level due to
construction works.
6.3.3.4
The above measures
should be monitored at least twice per month during the construction
phase. Additional weekly audit should be conducted during the period of
piling. In case of non compliance, the Contractor would be informed to
implement the proposed measures properly.
6.3.3.5
To evaluate the
effectiveness of the above measures, monthly monitoring of avifauna and their
notable behaviour, such as breeding activities, in the Middle Lagoon would be
carried out during construction phase. The monitoring area should include the
whole Middle Lagoon and area extended 20 m from the boundary of the Middle Lagoon.
All birds seen and heard in the Middle Lagoon would be identified and counted.
Signs of breeding (e.g. nests, recently fledged juveniles) of birds (e.g.
Little Grebe) would also be recorded. The coverage of water and PFA
filling activities in the Middle Lagoon as well as construction activities in
project site would be recorded as reference information. Subject to the
findings of avifauna record and habitat condition of Middle Lagoon, the
effectiveness of the proposed mitigation measure would be reviewed as
necessary.
6.3.4
Measures to Minimize Impact to Habitats
6.3.4.1
Where practicable, all
proposed works should be conducted in existing built up area to minimize impact
to natural habitats. All temporarily affected natural habitats, including
streambed, should be reinstated after the completion of works.
6.3.4.2
To minimize loss to
aquatic environment, the abutment (permanent structure) for the vehicular
bridge should not be constructed at streambed. The number and size of the
temporary supporting structures to be installed during construction should be
minimized as far as practicable. For natural stream, placement of
substrates of similar size and composition to those of original streambed
should be considered to encourage colonization. Measures to control
potential water quality impacts to the nearby watercourse and marine
environment during construction phase would be implemented and audited as
mentioned in Section 5 of this EM&A Manual.
6.3.4.3
To minimize the
potential water quality impacts from the construction works located at any
river channels, natural streams or seafront, the practices outlined in ETWB TC
(Works) No. 5/2005 “Protection of natural streams/rivers from adverse impacts
arising from construction works” should be adopted where applicable.
Relevant mitigation measures are listed below:-
· The proposed works
should preferably be carried out within the dry season where the flow in the
storm culvert/river channel/stream is low;
· The use of less or
smaller construction plants may be specified to reduce the disturbance to the
riverbed;
· Any works site inside the storm water courses should be temporarily
isolated, such as by placing of sandbags or silt curtains with lead edge at
bottom and properly supported props to prevent adverse impact on the water
quality;
· Temporary sewerage system should be designed to prevent wastewater
from entering the river, streams and sea;
· Temporary storage of materials (e.g. equipment, filling materials,
chemicals and fuel) and temporary stockpile of construction materials should be
located well away from any water courses during carrying out of the
construction works;
· Stockpiling of
construction materials and dusty materials should be covered and located away
from any water courses;
· Construction debris and spoil should be covered up and/or disposed
of as soon as possible to avoid being washed into the nearby water receivers;
· Construction activities, which generate large amount of wastewater,
should be carried out in a distance away from the waterfront, where
practicable;
· Mitigation measures to control site runoff from entering the nearby
water environment should be implemented to minimize water quality
impacts. Surface channels should be provided along the edge of the
waterfront within the work sites to intercept the runoff;
· Construction effluent, site run-off and sewage should be properly
collected and/or treated;
· Proper shoring may need to be erected in order to prevent soil/mud
from slipping into the storm culvert/river/stream/sea; and
· Supervisory staff should be assigned to station on site to closely
supervise and monitor the works.
6.3.4.4
Standard good site
practices should be implemented during the construction phase include the
followings:-
· Placement of equipment or stockpile in designated works areas and
access routes selected on existing disturbed land to minimize disturbance to
natural or moderate ecological valued habitat;
· Construction activities should be restricted to works areas that
would be clearly demarcated;
· The works areas
should be reinstated immediately after completion of the works;
· Waste skips should be provided to collect general refuse and
construction wastes. The wastes should be disposed of timely and properly
off-site;
· Drainage arrangements should include sediment traps to collect and
control construction run-off;
· Open burning on
works sites is illegal, and should be strictly prohibited;
· Temporary fire fighting equipment in the works areas should be
provided to prevent any open fire;
· Erect fences along the boundary of the works areas before the
commencement of works to prevent tipping, vehicle movements and encroachment of
personnel into adjacent areas;
· Only
well-maintained plant should be operated on-site and plant should be serviced
regularly during the construction programme;
· Machines and plant which may be in intermittent use should be shut
down between work periods or should be throttled down to a minimum;
· Plant known to emit noise strongly in one direction, should, where
possible, be orientated so that the noise is directed away from the Middle
Lagoon;
· Silencers or mufflers on construction equipment should be utilized
and should be properly maintained during the construction period;
· Mobile plant
(such as generator) should be sited as far away from the Middle Lagoon as
possible; and
· Material stockpiles and other structures should be effectively
utilized, where practicable, to screen noise from on-site construction
activities.
6.3.4.5
The above measures
should be monitored at least twice per month during the construction
phase. In case of non compliance, the Contractor would be informed to
implement the proposed measures properly.
6.3.5
Measures to Mitigate and Compensate for the
Loss of Vegetation
6.3.5.1
All vegetation located
within the works area should be preserved as far as practicable. To
compensate for the loss of the vegetation and habitats, tree planting should be
provided in the site area at where possible. Species chosen for planting
would be similar to the species identified in the survey and be native to Hong
Kong or the Southern China. The
condition of the retained vegetation on site should be monitored once a month
throughout the construction phase.
6.3.6
Measures to Create Additional Habitat for
Little Grebe
6.3.6.1
An additional pond
habitat for Little Grebe would be created in a less disturbed area located at
the northeastern part of the proposed STF. The created habitat would be
provided in the form of shallow pond(s) incorporating suitable habitat characteristics
for Little Grebe. The water level of the created pond would be kept
between 1.5 m to 2 m. Emergent vegetation would be planted and fish
population would be controlled to allow development of aquatic invertebrate
populations as prey of Little Grebe. To screen the created habitat from
disturbance due to nearby landfill traffic, planting of native vegetation would
be provided on the boundary of the pond(s) as appropriate. Prior to
construction of the pond(s), the detailed Habitat Creation and Management Plan
(HCMP) of the created habitat prepared by experienced ecologist(s) with over
seven year experience in relevant field should be circulated to relevant
departments including AFCD for comment.
6.4
Post-construction Phase Monitoring
6.4.1
Introduction
6.4.1.1
Post-construction phase
ecological monitoring should be conducted within the monitoring areas for a
period of one year upon completion of construction.
6.4.2
Site Condition and Bird Monitoring
6.4.2.1
Bi-monthly monitoring
of avifauna and their notable behaviour, such as breeding activities would be
carried out during post-construction phase. The monitoring area should
include the whole Middle Lagoon and area extended 20 m from the boundary of the
Lagoon. All birds seen and heard would be identified and counted.
Signs of breeding (e.g. nests, recently fledged juveniles) of birds (e.g.
Little Grebe) would also be recorded. The coverage of water and PFA
filling activities in the Middle Lagoon as well as post-construction phase
activities of the STF and associated facilities would be recorded as reference
information. Subject to the findings of avifauna record and habitat condition
of Middle Lagoon, the effectiveness of the proposed mitigation measures would
be reviewed as necessary.
6.5
Event and Action Plan
6.5.1.1
Potential indirect
impacts to the habitats and associated wildlife adjacent to the proposed STF
would be resulted from increased human disturbance during construction and
operation. The effectiveness of mitigation measures to minimize potential
impacts to habitat and wildlife is assessed through ecological monitoring
programme. However, it is recognised that the habitat conditions of ash
lagoons were governed by various factors such as CLP’s pulverised fuel ash
(PFA) filling activities and rainfall. Due to the volatile and unstable
nature of the ash lagoon habitat, it is considered inappropriate to expect the
wildlife would utilise the habitat in an invariable manner. Monitoring
results collected during the construction and post-construction phase should be
evaluated against the Event and Action Plan. Evaluation should be based
on recorded changes in:
· Relative Abundance and species diversity of birds recorded in the
monitoring area of Middle Lagoon
· CLP’s pulverised fuel ash (PFA) filling activities in the Middle
Lagoon
· Coverage of water in the Middle Lagoon
· The construction
phase activities under the Project (for Construction Phase Monitoring only)
· The
post-construction phase activities of the STF and associated facilities (for
Post-construction Phase Monitoring only)
6.5.1.2
The Event and Action
Plan is discussed in Table 6.1.
Table
6.1
Event and Action Plan
Parameter
|
Event
|
Action
|
Construction
Phase
|
Relative abundance and species diversity of birds recorded
in the monitoring area of Middle Lagoon
|
Relative abundance and species diversity of birds
decreased in any three successive monitoring events
|
Step 1- Review site condition
Step 2 - Check the implementation of mitigation
measures
Step 3- Review and adjust the mitigation measures as
appropriate
|
Post-construction Phase
|
Relative abundance and species diversity of birds
recorded in the monitoring area of Middle Lagoon
|
Relative abundance and species diversity of birds
decreased in any two successive monitoring events
|
Step 1- Review site condition
Step 2 - Check the implementation of mitigation
measures
Step 3- Review and adjust the mitigation measures as
appropriate
|
6.5.1.3
The proposed ponds
created inside the STF is expected to support a small population of Little
Grebe associated with the affected lagoon habitat. No specific event and
action plan are recommended. The effectiveness of the created pond will
be reviewed and adaptive management measures will be proposed as appropriate
and details of these review and management protocols will be included in the
HCMP.