6.1.1 The EIA stipulated that ecological monitoring and audit is required during the construction and operation stages of the Project in order to ensure that adverse ecological impacts are no greater than predicted, that ecological mitigation measures are implemented satisfactorily and to permit remedial measures to be taken as quickly as possible.
6.1.2 Ecological monitoring is not required for works at MUP03, MUP04A or MUP04B where no significant adverse impacts are predicted. However, it is proposed that there be construction phase (water quality and ecological) monitoring and audit at LMH01 and construction (water quality) and post-construction monitoring and audit at MUP05.
6.1.3 The objectives of the ecology monitoring and audit are:
a) to verify the accuracy of the impact predictions;
b) to check if the recommended mitigation measures are implemented fully;
c) to examine the effectiveness of the recommended mitigation measures;
d) to check whether the residual impacts comply with relevant ecological requirements; and
e) to recommend timely action plans to rectify any unacceptable impacts.
6.2.1 Baseline ecological monitoring should essentially follow the methodologies listed below, but the ET Leader should submit the detailed baseline monitoring proposals and schedules for approval by EPD (and copied to AFCD for advisory comment) prior to their commencement. The monitoring should be undertaken by a suitably qualified ecologist(s), as part of the ET, with relevant experience in ecological monitoring. The baseline ecological monitoring should be undertaken at LMH01 and MUP05 prior to the commencement of construction works to:
a) confirm the pre-works ecological conditions with reference to the habitat maps in the EIA report; and
b) conduct a walk-through survey of the EIA assessment areas in order to identify changes which have taken place since the EIA survey which can be predicted to possibly or probably have had an impact on flora and fauna distribution or numbers. Special attention should be paid to the ecologically sensitive stream at LMH01.
6.2.2 Baseline water quality monitoring should also be conducted at LMH01 and MUP05 prior to commencement of construction works to provide reference water quality data. Details of the water quality monitoring programme are presented in Section 4 of this EM&A Manual.
6.2.3 In addition, survey of fish species at LMH01 should be conducted. Three surveys (once per week) should be carried out along the stream and within 100m upstream and downstream of the construction site.
6.2.4 Recommendations for the baseline ecological monitoring programme at LMH01 and MUP05 are summarized in Table 6.1.
Recommended Baseline Ecological
Monitoring Programme at LMH01 and MUP05
|
Baseline Monitoring Required |
Location of Monitoring |
Frequency of Monitoring |
Duration of Monitoring |
|
Walk-over survey to
update habitat maps, and identify any changes to the EIA assessment areas
since EIA surveys |
EIA assessment areas
at LMH01 and MUP05 |
One walk-over survey |
One off survey before
start of construction works |
|
Water quality of
stream (dissolved oxygen, suspended solids, turbidity and pH)* |
Upstream and
downstream of construction site at LMH01 and MUP05 |
Three times per week |
Four weeks before
start of construction works |
|
Surveys of fish species |
Along stream channel,
within 100 m upstream and downstream of construction site at LMH01 |
Once per week |
Three surveys before
start of construction works |
Notes:
* As part of the water quality monitoring programme
(see Chapter 4).
6.3
Impact Monitoring and Audit
Construction Phase Monitoring and Audit at LMH01
6.3.1 Construction phase monitoring and audit at LMH01 should cover the following:
·
Ensure
that excavation and other engineering works do not cause adverse ecological
impacts outside the proposed project area;
·
Ensure
that works do not result in significant siltation downstream of the works area;
and
·
Ensure
that the recommended mitigation measures are properly implemented by the
contractor.
6.3.2 Water quality monitoring should be conducted at LMH01 during construction phase to provide reference water quality data. Details of the water quality monitoring programme are presented in Section 4 of this EM&A Manual.
6.3.3 Survey of fish species at LMH01 should be conducted once per week along the stream and within 100m upstream and downstream of the construction site throughout the construction phase. The survey should monitor the fish community as a whole to look for any signs of stress (e.g. dead fish, fish coming to the surface to gulp for air, reduce numbers of fish). It is not necessary to focus on particular species at this time, as any signs of stress would be expected to be observed in the fish community as a whole. On the weekly surveys, if a problem is identified (e.g. if any dead fish is noted in the stream, if behaviour of fish seems abnormal or if the number of fish observed is lower than the baseline survey results), actions in accordance with the Event/Action Plans should be implemented. The signs of stress in the fish community listed above are not exhaustive. The ET Leader should propose, in consultation with the ET ecologists, a more detailed interpretation after obtaining further survey results from the baseline monitoring. This should be verified by the IEC before submitting to EPD and copied to AFCD for their advisory comment and should be use for the impact monitoring and audit.
6.3.4 In addition, monthly fish surveys should be conducted focusing on the species of conservation importance e.g. Chinese Rasbora (Rasbora steineri) for which the Lin Ma Hang stream is important and the fish community as a whole. This would monitor the status of the important species, and look for any changes in the species composition as well as the fish community as a whole.
6.3.5
Monitoring and audit should be conducted by a suitably qualified
ecologist(s), as part of the ET, with relevant experience in ecological
monitoring. In the case of the monthly fish survey, a suitably qualified fish
ecologist should conduct the survey.
6.3.6 Recommendations for the ecological monitoring and audit programme during construction phase at LMH01 are summarized in Table 6.2.
Recommended Ecological Monitoring and
Audit Programme at LMH01
|
Potential Impacts |
Monitoring required |
Location of Monitoring |
Frequency of Monitoring |
Duration of Monitoring |
|
Construction phase impacts to stream conditions* |
||||
|
Soil runoff impacts
to stream bed |
Water quality of
stream (dissolved oxygen, suspended solids, turbidity and pH) |
Upstream and
downstream of construction site |
Three times per week |
Throughout
construction phase |
|
Construction phase impacts to fish and other ecological impacts |
||||
|
Impacts to important
fish community and other ecological impacts |
Surveys of fish
species and general site audit (with emphasis on ecological mitigation
measures) |
Along stream channel,
within 100 m upstream and downstream of construction site |
Once per week on fish
community as a whole and general site audit Monthly fish survey
focusing on the species of conservation importance and fish community as a
whole |
Throughout
construction phase |
Notes:
* As part of the water quality monitoring programme
(see Chapter 4).
Construction Phase
Monitoring and Audit at MUP05
6.3.7 Construction phase monitoring and audit at MUP05 should cover the following:
·
Ensure
that excavation and other engineering works do not cause adverse ecological
impacts outside the project area;
·
Ensure
that those areas where natural banks are to be retained are protected from
adverse effects of engineering works, including impacts to riparian vegetation
along these banks;
·
Ensure
that the existing natural stream channel is protected from adverse effects of
engineering works, including potential indirect impacts through increased
sedimentation;
·
Ensure
that rocks/fines used to form the bottom of the widened channel have the
appropriate physical characteristics to permit re-establishment of semi-natural
stream conditions; and
·
Ensure
that the recommended mitigation measures are properly implemented by the
contractor.
6.3.8 Water quality monitoring should be conducted at MUP05 during construction phase to provide reference water quality data. Details of the water quality monitoring programme are presented in Section 4 of this EM&A Manual.
6.3.9
Monitoring and audit should be conducted by a suitably
qualified ecologist(s), as part of the ET, with relevant experience in ecological
monitoring.
6.3.10 Recommendations for the ecological monitoring and audit programme during construction phase at MUP05 are summarized in Table 6.3.
Recommended Ecological Monitoring and
Audit Programme at MUP05
|
Potential Impacts |
Monitoring required |
Location of Monitoring |
Frequency of Monitoring |
Duration of Monitoring |
|
Construction phase impacts to stream conditions* |
||||
|
Soil runoff impacts
to stream bed |
Water quality of
stream (dissolved oxygen, suspended solids, turbidity and pH) |
Upstream and
downstream of construction site |
Three times per week |
Throughout
construction phase |
|
Construction phase ecological impacts |
||||
|
Potential ecological
impacts |
General site audit
(with emphasis on ecological mitigation measures) |
Along stream channel,
within 100 m upstream and downstream of construction site |
Once per week |
Throughout
construction phase |
Notes:
* As part of the water quality monitoring programme
(see Chapter 4).
Post-construction (Operational)
Monitoring at MUP05
6.3.11
The proposed design for MUP05 channel follows the advice
contained in DSD TC No. 2/2004. This is a novel approach to channel widening in
·
Stream
characteristics at an appropriate interval after the completion of works to
include water depth, stream width, nature of substrate and a variety of water
quality parameters such as dissolved oxygen, turbidity and pH;
·
Vegetation
characteristics at an appropriate interval after the completion of works;
·
(Re-)
colonization of the widened channel by permanently aquatic species (fishes and
stream invertebrates); and
·
Use
of the widened channel by other wetland-dependent taxa (birds, herpetofauna and
dragonflies).
6.3.12 Monitoring should be conducted by a suitably qualified ecologist(s) with relevant experience in the various ecological parameters to be monitored. Detailed monitoring methodologies and proposals should be developed and agreed with EPD (and copied to AFCD for advisory comment) prior to commencement of the post-construction monitoring.
6.3.13 The recommended post-construction (operational) monitoring programme at MUP05 are summarised in Table 6.4.
Recommended Post-construction
(Operational) Ecological Monitoring Programme at MUP05
|
Potential
Impacts |
Monitoring
required |
Location
of Monitoring |
Frequency
of Monitoring |
Duration
of Monitoring |
|
Post-construction (operational) ecological impacts |
||||
|
Stream
characteristics |
Water depth, stream
width, nature of substrate and water quality parameters such as pH, DO and
turbidity |
At an appropriate
interval along the constructed channel |
To be undertaken
along with other post-construction ecological surveys |
One year following
completion of construction works |
|
Riparian vegetation |
Botanical survey |
Works area and
reinstated area |
Once during wet
season and once during dry season |
One year following
completion of construction works |
|
Birds |
Transect survey |
Within 100 m of
construction site |
Monthly |
One year following
completion of construction works |
|
Reptiles |
Transect survey
(daytime and night-time) |
Within 100 m of
construction site |
One day and one night
survey per month during March - October |
One year following
completion of construction works |
|
Amphibians |
Transect survey
(daytime and night-time) |
Within 100 m of
construction site |
One day and one night
survey per month during March - October |
One year following
completion of construction works |
|
Fish |
Fish survey |
Along stream channel,
within 100 m upstream and downstream of construction site |
Monthly |
One year following
completion of construction works |
|
Dragonflies |
Transect survey |
Within 100 m of
construction site |
Monthly during March
- October |
One year following
completion of construction works |
|
Butterflies |
Transect survey |
Within 100 m of
construction site |
Monthly during March
- October |
One year following
completion of construction works |
|
Stream invertebrates |
Kick sampling |
At upper and lower
end of construction site and 100 m downstream of construction site |
Monthly |
One year following
completion of construction works |
6.3.14 Results of the post-construction (operational) monitoring should be submitted to EPD (and copied to AFCD) each month. A final report summarizing the monitoring results over the entire operational monitoring period and its findings should be prepared to serve as a reference for future similar projects.
6.4
Event and Action Plans for Ecology
6.4.1 Water quality data for monitoring stations as proposed for this Project (see Chapter 4) should also be used for reference while undertaking ecological monitoring purposes. Should the monitoring results of water quality parameters at any designated monitoring stations exceed the criteria, the actions in accordance with the Event/Action Plan shall be carried out (see Chapter 4).
6.4.2
For this
project, its nature is such that it is unrealistic to expect wildlife to
continue to use the portions of the stream to be channelised during the construction
period. Monitoring during the construction period is, therefore, focussed on
safeguarding of the fish (and other aquatic) communities and stream habitat at
LMH01 as well as ensuring no adverse construction related impacts (e.g. silty
runoff) on LMH01 and MUP05.
6.4.3
The
recommended mitigation measures should be audited at least once every week as
part of the site audit programme.
6.4.4
In the
event of a non-compliance, the Event/Action Plans shown in Table 6.5 should be
followed by the relevant parties.
Event/Action Plans for Ecology
|
EVENT |
ACTION |
|||
|
ET
Leader |
IEC |
Engineer |
Contractor |
|
|
Non-conformity
on one occasion |
1.
Identify source 2.
Inform the IEC and the ER 3.
Discuss remedial actions with the IEC, the ER and the
Contractor 4.
Monitor remedial actions until rectification has been
completed |
1.
Check monitoring results 2.
Check the Contractor’s working method 3.
Discuss with the ET and Contractor on possible remedial
measures 4.
Advise the ER on effectiveness of proposed remedial
measures 5.
Check the implementation of remedial measures |
1.
Notify Contractor 2.
Ensure remedial measures are properly implemented 3.
Consider and instruct, if necessary,
the Contractor to slow down or to stop all or part of the works in the case
of serious non-conformity until situation is rectified |
1.
Take immediate action to avoid further
problem 2.
Amend working methods if needed 3.
Submit proposals for remedial actions to ET, ER and IEC 4.
Rectify damage and implement the agreed remedial actions |
|
Repeated
Non-conformity |
1.
Identify source 2.
Inform the IEC, ER, EPD and AFCD 3.
Increase monitoring frequency 4.
Discuss remedial actions with the IEC, the ER and the
Contractor 5.
Monitor remedial actions until rectification has been
completed 6.
If exceedance stops, cease additional monitoring |
1.
Check monitoring results 2.
Check the Contractor’s working method 3.
Discuss with the ET and Contractor on possible remedial
measures 4.
Supervise the implementation of remedial measures 5.
Advise the ER on effectiveness of proposed remedial
measures and keep EPD and AFCD informed |
1.
Notify Contractor 2.
Ensure remedial measures are properly implemented 3.
Consider and instruct, if necessary,
the Contractor to slow down or to stop all or part of the works in the case
of serious non-conformity until situation is rectified |
1.
Take immediate action to avoid further
problem 2.
Amend working methods if needed 3.
Submit proposals for remedial actions to ET, ER and IEC 4.
Rectify damage and implement the agreed remedial actions |
6.5
Ecological Mitigation Measures
Proposed Measures to Minimise Adverse Ecological Impacts
LMH01
Construction
Stage
6.5.1 Evaluation of potential ecological impacts suggested that there could be a small adverse impact on stream fauna of conservation importance (specifically fish and dragonflies) as a consequence of construction works increasing the sediment load in the stream – sediment could smother eggs or larvae. While the small scale of the works should ensure that suitable refuges remain for these species during the period of construction works, the potential adverse impact can be minimised by restricting works in the stream to the dry season. This would be beneficial for the following reasons:
- most
fish and dragonflies have eggs and small larvae (the most vulnerable stages)
during the wet season;
- heavy
rain, washing soil exposed by construction activities into the stream is much
less likely during the dry season; and
- lower
stream levels during the dry season increase the proportion of the works area where activities are
not influenced by the flowing stream.
6.5.2 Given the ecological importance of Lin Ma Hang stream, it is proposed that construction works at LMH01 should be restricted to the dry season period from 1st November – 31st March. The small scale of works should allow all construction to be completed within dry season to ensure that the risk of erosion and sedimentation due to heavy rain on the works areas, as well as disturbance impacts to surrounding areas, will be minimised.
6.5.3 In addition, the breaking of existing shotcrete banks at LMH01 should be restricted to hand-held equipment. Concrete should not be used for construction of the gabion banks.
6.5.4 Potential disturbance impacts to surrounding habitats and pollution risks (water quality impacts) to the stream should be minimised by adoption of appropriate site management procedures, as detailed in ETWB TCW No. 5/2005; including among others the location of access to the site and storage of materials and treatment of construction site waste to prevent pollution of the stream. These site management measures are listed in the subsequent section.
Operational Stage
6.5.5 Very little or no management / maintenance of the completed sections of LMH01 are expected. Removal of obstruction should be undertaken only when flooding or safety issues have been identified.
6.5.6 Environmental considerations for maintenance of the proposed gabion channels (Section 5.8 of the EIA) should be adopted.
6.5.7 Vegetation management should be restricted to the removal of the exotic creeper Mikania micrantha which has previously been found to readily colonise gabion embankments. The establishment of this species would have a detrimental impact on the establishment of natural riparian vegetation. Control of Mikania and other invasive exotic species should be incorporated in the maintenance regime.
MUP05 (natural stream section)
Construction
Stage
Streambed
6.5.8 One of the main benefits of the proposed stream widening measures is that the existing natural stream bed is left undisturbed. Accordingly, works should be carried out in such a way that as much as possible of the natural stream bed should be left undisturbed and that where disturbance is essential this should be minimised in terms of area, magnitude and duration to minimise potential impacts to stream fauna and to ensure refuges for these species during the period of the works. Avoidance of the stream bed can be achieved by conducting the earthworks to widen the stream from the landward side, by not lowering the widened channel to the same level as, or below, the existing channel, and by leaving the existing stream untouched except during the final stage, when the newly formed widened stream bed is joined to the existing stream.
6.5.9 In addition, the widened stream bottom should be floored with natural materials (natural rock and fines of varying sizes) to approximate as closely as possible to the rocky components of a natural stream bottom. Natural materials of a smaller particle size (sand and silt grains) will soon be deposited naturally.
6.5.10 In order to minimise potential impacts to stream fauna during excavation of the widened “two-stage” channel, this work should be limited to the dry season as far as possible, between 1st October and 31st March. As rainfall is low at this time, erosion is less likely and deposition of sediment downstream of the works should be minimised. This also avoids the time when stream fauna are at the most vulnerable stage in their life cycle (eggs and young larvae). Any essential works outside the dry season should be temporarily isolated from the stream to prevent the risk of pollution or sedimentation affecting the ecological integrity of the stream.
6.5.11 As required to minmize potential water quality impacts (Section 5.6), excavation works at the stream section of MUP05 should be restricted to 300m length at any one time. No restriction is considered necessary for the first 300m upstream concrete drains section. Excavation works at MUP04A should be restricted to 100m to cater for potential cumulative impact on MUP05.
6.5.12 Appropriate site management procedures during the construction phase should be adopted, as recommended in ETWB TCW No. 5/2005, to minimise potential disturbance impacts and pollution risks (water quality impacts) to the stream. This should include the location of access to the site and storage of materials, and treatment of construction site waste to prevent pollution of the stream. These site management measures are listed in the subsequent section.
Stream Banks and Riparian
Vegetation
6.5.13 Although 20% of the natural stream banks will not be impacted under the revised design, the nature of the works (including widening of the stream channel) limits the extent to which minimization of adverse impacts to the stream banks and riparian zone during the construction stage is feasible. Disturbance impacts to the riparian zone will be minimised by suitable location of works areas and by adoption of appropriate site management protocols during construction. Where possible, native riparian trees which would be impacted during construction works should be transplanted to suitable sites within the project area (see below).
Operational Stage
Streambed, Gabion Banks and Other Areas within the Operational
Limits of the Channel
6.5.14 Management and maintenance of the streambed and channel sides should be limited to the minimum required to prevent flooding and ensure safety. Accordingly, the stream should be permitted to find (and adjust) its own low flow channel and natural changes in the deposition of silt, sand and rock should be tolerated except where a specific flooding or safety issue is identified (in accordance with the DSD Technical Circular.
6.5.15 Environmental considerations for maintenance of the proposed gabion channels (Section 5.8 of the EIA) should be adopted.
6.5.16 The provision of natural rock and fines in the widened streambed, and the use of stepped gabion banks, will permit recolonisation of the channel by riparian vegetation following completion of the works, thus mitigating for the loss of natural riparian vegetation. Vegetation management within the channel should therefore be restricted to removing obstructions and preventing tree establishment, while the presence of herbaceous vegetation should be tolerated as much as possible. If clearance of herbaceous vegetation is required to prevent obstruction of water flow, where specific flooding or safety issues have been identified, this should not be undertaken during March – August (the main period during which this vegetation would be used as a breeding/nursery area by fauna). Control of invasive plant species, especially the creeper Mikania micrantha, which has previously been found to readily colonise gabion embankments, should be carried out where necessary to permit the establishment of a native floral community.
6.5.17 It is considered that if the above measures to minimise adverse ecological impacts are instituted, all significant ecological impacts which cannot be avoided would be minimised or reduced to acceptable levels with the exception of the loss of the existing diversity of flora and fauna in the riparian zone, resulting primarily from the loss of many riparian trees along the MUP05 stream. This remaining potential adverse impact will require mitigation (see below).
Proposed
Measures to Mitigate for Adverse Ecological Impacts
6.5.18 As discussed above, it is considered that the only remaining adverse ecological impact of significance once avoidance and minimisation measures are taken, is the loss of shaded stream sections at MUP05 due to the loss of bankside trees. Shaded stream sections are ecologically important – for example, buffering stream temperatures, providing habitat for a number of fish and dragonfly species of conservation importance or providing roosting or nesting sites for wetland birds.
6.5.19 The loss of bankside trees, and associated riparian habitats, should be mitigated through transplanting existing trees to suitable locations wherever possible, and through supplemental planting of native trees and bamboos in locations where the project area includes sufficient space adjacent to the stream but outside the channel itself (in addition to retaining in-situ as much trees as possible). Table 6.6 details appropriate species of trees and bamboos. Species selected are characteristic native species present in the area and which are known to be of high value to wildlife.
6.5.20
The proposed landscape compensatory planting of about 740
trees (approximately 1,100 m2) along the MUP channels (see Section 8.11
of the EIA) will serve dual purpose of landscape impact mitigation as well as mitigating
the loss of riparian trees.
6.5.21
The Landscape Plan to be submitted prior to commencement of
planting or landscaping works should take into account the recommended plant
species listed in Table 6.6.
Recommended Tree and Bamboo Species
for Planting at MUP05
|
Species |
Reasons/Benefits |
|
Celtis tetranda (sinensis) |
Characteristic |
|
Ficus hispida |
Characteristic |
|
Ficus microcarpa |
Characteristic |
|
Litsea glutinosa |
Widespread small tree
species common in the area. Flowers attractive to insects and fruits to
birds. |
|
Sapium discolor |
Characteristic |
|
Schefflera octophylla |
Widespread lowland
species occurring along streams (and elsewhere); common in the area. Form
provides good cover, flowers very attractive to insects and fruit to birds. |
|
Trema tomentosa |
Common in the area.
Supports diverse bird community and produces abundant small fleshy fruit
favoured by birds. |
|
Bambusa eutuldoides |
Common bamboo species
in |
Proposed Site Management
Measures during Construction
6.5.22 The recommended site management measures are generally good site practices and proper water quality control / waste management measures to be implemented by the contractor for all works near stream courses. These measures include:
§ Construction activities should be restricted to works area that should be clearly demarcated.
§ Excavation works should be carried out during the dry season where stream flow is low. Where adequate space is available, works should be carefully phased such that only one side of the channel is constructed. Temporary diversion should be provided to ensure continuous water flow to the downstream section.
§ The proposed works site inside or in the proximity of natural streams should be temporarily isolated, such as using bunds or sandbag barriers (wrapped with geotextile fabric) or other similar techniques, to prevent adverse impacts on the stream water quality.
§ For the stream section where the existing natural stream bed and bank will be left untouched, no disturbance to the stream bed and bank should be allowed from construction works, equipment or workers. If temporary access track on streambed is unavoidable, this should be kept to the minimum width and length. Temporary stream crossings should be supported on stilts above the stream bed.
§ Adequate temporary drainage measures including sediment and oil/grease traps should be provided to prevent contaminated site run-off entering the water bodies.
§ Stockpiling of construction materials, spoils and waste should be properly covered and located away from water bodies to prevent silty runoff and other pollutants from entering the water bodies during rain storms.
§ Construction effluent, site run-off and sewage should be properly collected, treated and disposed.
§ Supervisory staff of the contractor should be assigned to station on site to closely supervise and monitor the construction works. All workers should be regularly briefed to avoid disturbing the flora and fauna near the works area.
6.5.23 The Contractor should provide details of the mitigation measures to be implemented during construction stage as part of their working method statement to the Engineer for approval. This should be reviewed by the ET Leader.
6.5.24
The
implementation schedule for the recommended mitigation measures is presented in
Appendix A.
6.5.25
If
the above measures are not sufficient to restore the impacts to acceptable
levels upon the advice of ET Leader, the Contractor shall liaise with the ET
Leader on some other mitigation measures, endorsed by IEC and propose to ER for
approval, and implement the mitigation measures.