Agenda
Item 1 : Confirmation of Minutes of 65th Meeting held on 26
November 2001
2. The
minutes were confirmed without amendments.
Agenda
Item 2 : Matters Arising
Para.
25: Para. 27 of EIAO GN006/2001
3. The
Chairman informed Members that taking into account their
views on the Guidance Note on "Some observations on ecological
assessment from the EIA Ordinance perspective", the Note
was finalized and issued together with seven other Notes.
Copies had been circulated to Members.
Para.
28: Discussion with the Hong Kong Construction Association
4. The
Chairman reported that the Secretariat would liaise with
the Association to fix a date for meeting the Subcommittee.
Para.
32: Requests for more information about the KCRC on Spur Line
5. Members
noted that the information requested had been provided by
KCRC and sent to them on 12 December 2001.
Schedule
of Meetings of the Subcommittee in 2002
6. The
Chairman informed Members that the schedule had been revised
to tie in with the meeting schedule of the full Council endorsed
on 21 January 2002. Members endorsed the Subcommittee
meeting schedule for 2002.
7. The
Chairman informed Members that as he was one of the witnesses
of the appeal arising from the previous EIA on the Spur Line,
he preferred not to chair the discussion on agenda item 3.
He then handed over the chair to Mr. Otto Poon, the Deputy
Chairman, at that juncture.
Agenda
Item 3 : KCRC East Rail Extensions - Sheung Shui to Lok Ma
Chau Spur Line
(ACE-EIA Paper 1/2002)
8. The
Acting Chairman welcomed the presentation team to the
meeting. Mr. James Blake said that the EIA study which included
the work of the previous EIA was a new one for the project.
One of the major concerns of the current EIA was the hydrological
impact on Long Valley arising from the tunnel option. He then
asked Mr. Vic McNally to present the key issues and
findings of the EIA study.
Hydrological
impact assessment
9. A
Member queried the soundness of the SEEP/W model that
was adopted to study the impact of the tunnel on the groundwater
system of Long Valley and the adequacy of groundwater monitoring
by installing five peizometers at each of the four sections
within Long Valley. She pointed out that the allowable fluctuations
of the monitoring parameters had not been specified in the
report. She doubted the effectiveness of the action plan to
deal with possible changes in the groundwater regime. She
also pointed out the absence of trials to validate the predictions
of the hydrological models in groundwater movements and surface
settlement.
10. In
response, Mr. Richard Deacon said that the SEEP/W model
was a commonly used 2-Dimensional model to analyze groundwater
movement and pore-water pressure distribution within porous
materials. The groundwater movement in Long Valley was modeled
and compared. It was found that the underground water movement
was dominated by the main aquifer. As the tunnel would be
located in the much less permeable "Completely Decomposed
Tuff' layer underneath the aquifer, the construction of the
tunnel and the future operation of the railway would unlikely
affect the groundwater movement. The results of the analysis
showed that the groundwater table remained unchanged with
or without the tunnel except for a 10mm variation at a section
north of the tunnel alignment, but the variation was considered
negligible.
11. On
groundwater monitoring by piezometers, Mr. Deacon assured
Members that data obtained by the four suites of peizometers
at sections within Long Valley would be sufficient to characterize
the groundwater table along the tunnel alignment. As regards
the action plan, Mr. Deacon said that surface settlements
arising from the passage of the tunnel-boring machine would
unlikely affect the surface hydrology and in any case, the
contractor together with local farmers could readily recover
the situation. Ground water augmentation actions would be
taken to restore the normal water level when the piezometer
readings reached 300mm above the lowest level for Neap tide
dry season. If those actions could not achieve the minimum
groundwater level, a backup action would be to raise the downstream
fabridam operated by the Water Services Department to impound
the River Beas River Sutlej thereby flooding the alluvial
aquifer across the Long Valley floor.
12. On
the question of trials, Mr. McNally said that the best
trial was the Tsing Tsuen Tunnel which was constructed by
the same construction method and in soil conditions much more
difficult than those in Long Valley and which had proved to
be highly successful. 16mm of surface settlement was recorded
and the water table had not changed. In response to a follow-up
question by a Member, Mr. Jayananda Jesudason said
that the predicted settlement in the Tsing Tsuen Tunnel was
below 25mm.
13. In
reply to a Member's question about settlement markers, Mr.
Deacon assured Members that the number of markers would
be adequate to monitor any surface settlement.
14. The
Acting Chairman asked whether the vent holes of the ventilation
system of the twin tunnels would affect the groundwater table.
In response, Mr. Blake said that there were no ventilation
holes along the tunnels. Instead the ventilation structures
would be at the two ends of the tunnels.
15. A
Member noted in para. 3.4.10 on P.3-10 of the EIA report
that the baseline for groundwater level of a wet season Spring
tide event had been obtained but an additional definitive
dry-season record had yet to be run. He asked how the modeling
results would be affected by incomplete baseline data. In
response, Mr. Deacon said that the Neap and Spring
tide data was presented in the EIA report. Further, both the
wet season and dry season piezometric data showed a significant
tidal influence in the Long Valley groundwater regime. The
monitoring would continue during the project implementation
stage.
16. A
Member asked whether the tidal water would affect the
water quality of the groundwater in the valley. Mr. Deacon
replied that the salinity of the groundwater In Long Valley
was similar to tap water which would not have any adverse
impact on the habitats in that area.
17. A
Member asked whether there was any possibility that the
groundwater would be contaminated by the construction materials.
In response, Mr. Jesudason confirmed that the tunnel
boring machine would only use a biodegradable and non-toxic
foam to facilitate the breaking down of materials during the
tunneling operation. The foam had been tested and used in
the Tsing Tsuen Tunnel and would not contaminate the groundwater.
18. A
Member enquired about the worst-case scenario on the groundwater
table during the construction period. In response, Mr.
McNally said that the EIA was conducted based on the worst-case
scenario. In fact, the impacts on the groundwater table arising
from the operation of the railway were of greater concern
than during construction.
19. A
Member enquired about the rectification actions that would
be taken if the actual change in groundwater level was more
than 10mm. Mr. McNally said that the tidal effect was
in fact much greater than the impacts arising from the construction
works or the operation of the railway. The contractor would
ensure that the changes in the groundwater level would stay
within the normal groundwater regime.
20. The
Acting Chairman asked whether there would be sufficient
water in the rivers in all weather conditions to maintain
the ecological value and agricultural value of Long Valley.
In reply, Mr. Deacon said that the irrigation system
which was operated by AFCD would bring water to the rivers
all year round.
21. The
Acting Chairman asked about the contingency plan to repair
the tunnel and restore the hydrology of the area in case there
was a crack in the "tuff" layer. In response, Mr.
McNally said that they would repair it immediately as
the tunnel must be kept dry in order to operate safely.
Baseline
surveys of species of ecological importance
22. A
Member referred to Table 4.2 on P. 4-13 and 4-14 of the
report and queried why the butterflies identified in the ERM
report were not found in the baseline surveys for the project.
In reply,
Dr. Michael
Leven explained that though the ERM Report was published in
1999, the list of rare butterflies was derived from a review
of published and unpublished records. Those records were collected
over 20 years ago and the woodland habitat concerned had degraded
since that time. Hence those butterfly species were considered
to be no longer present. The current EIA had adopted the results
of the recent baseline survey as the basis.
Compensation
by area or function 23. A Member said that while
he realized that the ecological impacts arising from the construction
of the station in Lok Ma Chau could not be avoided, ideally
compensation should be made in terms of area as well as function.
He asked whether it was possible to get more land to compensate
for the loss of 9.1 hectares of fishponds. In response, Mr.
McNally said that they had explored the Lok Ma Chau area
to provide on-site mitigation. As the entire Lok Ma Chau area
comprised fish ponds, there was no more land available for
conversion to new fish ponds, and therefore the EIA report
recommended compensating the loss of fishponds by enhancing
the ecological functions of 27.1 hectares of existing fishponds
in the same area. In response to that Member's enquiry, Mr.
McNally said that the existing fishponds were granted by the
Government.
24. Noting
in the EIA report that there was problem in establishing a
reliable and realistic baseline for habitat monitoring programme
(ref. P.4-92 of the report), a Member expressed concern
about the effectiveness of the proposed mitigation measures.
Another Member asked whether off-site compensation
had been considered. In response, Mr. McNally said
that according to the Technical Memorandum (TM) on the EIA
process, "either the same kinds of species or habitats
of the same size shall be compensated, or the project proponent
shall demonstrate that the same kind of ecological function
and capacity can be achieved through the measures to compensate
for the ecological impacts off-site"; and ecological
mitigation measures shall be provided only if all practical
on-site ecological mitigation measures had been exhausted.
They had demonstrated in the EIA report that compensation
could be achieved by enhancing the ecological function and
capacity of the fishponds. Mr. Blake said that they
had already complied with the requirements set out in the
EIA Ordinance and the TM and it was beyond their remit to
obtain more land for compensation. The second Member
noted that since the TM stipulated that "...the project
proponent shall demonstrate", the onus would be on KCRC
to provide sufficient evidence that "demonstrated"
the effectiveness of the proposed measures. Further since
this was the first EIA report to be submitted under the EIAO
that proposed mitigation by functional enhancement, she urged
the Subcommittee to carefully scrutinize the mitigation proposals
as the standard used would be precedent-setting.
Definitions
of ecological function and capacity
25. A
Member exchanged views with the project proponent regarding
the definition of "ecological function and capacity".
Dr. Leven said that in the current project the ecological
function of the habitat concerned laid in its being used as
commercial fishponds and the ecological capacity was assessed
in terms of the wildlife that the habitat supported, i.e.
the species of ecological importance as identified in the
EIA.
26. A
Member considered the definitions adopted by the proponent
too narrow. She quoted that the Ramsar Convention defined
ecological function as "activities or actions which occur
naturally in wetlands as a project of the interactions between
the ecosystem structure and processes" and wetland function
as "processes among and within the various biological,
chemical and physical components of a wetland, such as nutrient
cycling, biological productivity, etc.". She said that
the Canadian Government, European Union and Conservation International
had their own definitions. In the local context, the Fish
Pond Study stated that "the ecological value of a habitat
is defined as its contribution in sustaining wildlife communities
and essential ecological processes of a wider eco-system."
Also the Oxford Concise Dictionary of Ecology defined "carrying
capacity" as "the saturation value for species population
showing the sigmoid shape population growth curve."
27. Dr.
Leven said that the ecological value of the commercial
fishponds laid in its being a source of food to certain species
of water birds and an important foraging habitat for those
birds. "Carrying capacity" was regarded as the maximum
number of individuals that could be supported on a given area
of habitat. To this end, the proposed compensation measures
were to enhance the existing 27.1 hectares of fishponds by
raising their carrying capacity for target species and hence
their ecological value. The objective was to achieve an increase
in bird usage by enhancing the ecological functions of the
fishponds concerned during construction and after the completion
of the project on a long-term basis.
28. A
Member said that at present the ecological value of the
commercial fishponds varied with the changes in fish farming
activities which were affected by market demand. He asked
whether the proponent had a detailed plan to ensure the productivity
of fish in the fishponds concerned so as to achieve the target
value. In response, Dr. Leven said that they had a
detailed management plan for the enhanced fishponds to ensure
that the birds affected would continue to use the area.
Adequacy
and effectiveness of enhancement measures
29. The
Acting Chairman asked why the proponent had adopted an
enhancement factor of two for compensating the fishponds.
A Member followed up on the Acting Chairman's question
and pointed out that the usual enhancement factor in overseas
countries was three. He asked for the justification for adopting
a factor of two. In reply, Mr. McNally said that the factor
was chosen in order to achieve a one to one compensation of
the overall functional value of the fishponds. Dr. Leven
supplemented that fishponds were easy to manipulate when compared
to other habitats because they were artificial wetlands. In
the present case, the input would include providing fish stock,
maintaining shallow water, the pH value and water quality,
and ensuring that the edges of the bunds would provide the
right mixture of covered and open area for roosting of target
bird species, etc.
30. In
reply to a Member's enquiry, Dr. Leven replied that
in calculating the carrying capacity of the fishponds, they
had adopted the number of bird-days per pond as the unit.
For example, based on observations conducted during the study,
the average number of Black-faced Spoonbills supported by
a typical fish pond at Pak Hok Chau Fishpond in winter was
17 bird-days.
31. Disregarding
theoretical calculations, the Acting Chairman asked
how the proponent could ensure the effectiveness of the proposed
enhancement measures. In response, Mr. McNally informed
Members that in the last two and a half months, they were
carrying out experiments in the fishponds at Lok Ma Chau by
controlling the water level and stocking of fish. According
to the findings, the enhancement ratio was more than two (Annex
I). As satisfactory results were obtained by carrying out
only some of the proposed enhancement measures in the experiment,
he was confident that the full enhancement programme would
achieve, if not exceed, the intended results.
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