This section of the EIA report presents the findings of the ecological
impact assessment of the activities proposed for the Project as outlined in Section 2.4 of this report.
The operations of the Project will be located within
the existing site of the CPB with the exception of the construction and
operation of an additional berthing facility to handle process reagents and
by-products via marine transport.
The existing Heavy Load Berth along the north-western waterfront of the
Castle Peak Power Station will be extended to form a multi-purpose berth and to
provide the additional berthing facility required. An area of approximately 30,000 m2
to the west of the berth will be dredged to a depth of approximately –8.2 mPD
to allow the safe approach and berthing of marine vessels up to 10,000 dwt.
The marine environment may however be affected by the marine works of
the Project and will therefore be the main focus of this section. The chosen Study Area for this
ecological assessment is the same as that adopted in the water quality
assessment (Figure 5.1 in Section 5). Sensitive
marine habitats in the Study Area have been identified and the assessment of
potential direct and indirect impacts associated with the construction and
operation of the additional berthing facility discussed.
The area directly impacted by the construction and operation of the
additional berthing facility will be referred to as the Project Area which
delineates the permanent footprint of the Project and comprises the additional
berthing facility and the dredged area (Figure 2.2).
8.1
Evaluation
Criteria and Legislative Requirements
The main criteria for the evaluation of marine
ecological impacts adopted for the present assessment are the ones laid out in
the Technical Memorandum on Environmental
Impact Assessment Process under the Environmental Impact Assessment Ordinance (EIAO-TM). Annex
16 sets out the general approach and methodology for assessment of marine
ecological impacts arising from a project or proposal. This approach allows a complete and
objective identification, prediction and evaluation of the potential marine
ecological impacts associated with the Project. Annex
8 of the EIAO-TM recommends the
criteria that can be used for evaluating marine ecological impacts.
Legislative requirements and other evaluation criteria relevant to the
protection of species and habitats of marine ecological importance are listed
and summarised below.
·
Marine Parks Ordinance (Cap
476);
·
Wild Animals Protection Ordinance (Cap
170);
·
Animals and Plants (Protection of
Endangered Species) Ordinance (Cap 187);
·
Town Planning Ordinance (Cap
131);
·
·
Technical Memorandum on Environmental
Impact Assessment Process under the Environmental Impact Assessment Ordinance (EIAO-TM);
·
United Nations Convention on Biodiversity (1992);
·
Convention on Wetlands of International
Importance Especially as Waterfowl Habitat (the Ramsar Convention);
·
Wild Animal Protection Law of the PRC;
·
8.1.2
Marine Parks Ordinance (Cap 476)
The Marine
Parks Ordinance (Cap 476) provides for the designation, control and
management of marine parks and marine reserves. It also stipulates the Director of
Agriculture and Fisheries as the Country and Marine Parks Authority which is
advised by the Country and Marine Parks Board. The
8.1.3
Wild Animals Protection Ordinance (Cap
170)
Under the Wild Animals Protection Ordinance (Cap 170), designated wild
animals are protected from being hunted, whilst their nests and eggs are
protected from destruction and removal.
All birds and most mammals including all cetaceans are protected under
this Ordinance, as well as certain reptiles (including all sea turtles),
amphibians and invertebrates. The
Second Schedule of the Ordinance that lists all the animals protected was last
revised in June 1997.
8.1.4
Animals and Plants (Protection of
Endangered Species) Ordinance (Cap 187)
The purpose of the Animals and Plants (Protection of Endangered Species) Ordinance (Cap
187) is to restrict the import and export of scheduled species. The Ordinance is primarily related to
controlling trade in threatened and endangered species and restricting the
local possession of them. Certain
types of corals are listed in Schedule 1 and 2 of the Ordinance, including Blue
coral (Heliopora coerulea), Organ
pipe corals (family Tubiporidae),
Black corals (order Antipatharia),
Stony coral (order Scleractinia),
Fire corals (family Milleporidae) and
Lace corals (family Stylasteridae). The import, export and possession of
scheduled corals, no matter dead or living, is restricted.
8.1.5
Town Planning Ordinance (Cap 131)
The recently amended Town Planning Ordinance (Cap 131) provides for the designation of
areas such as “Coastal Protection Areas”, “Sites of Special Scientific Interest
(SSSIs)”, “Green Belt” and "Conservation Area” to promote conservation or
protection or protect significant habitat.
8.1.6
Chapter
10 of the HKPSG covers planning
considerations relevant to conservation.
This chapter details the principles of conservation, the conservation of
natural landscape and habitats, historic buildings, archaeological sites and
other antiquities. It also
addresses the issue of enforcement.
The appendices list the legislation and administrative controls for
conservation, other conservation related measures in
8.1.7
Technical Memorandum on Environmental
Impact Assessment Process under the Environmental Impact Assessment Ordinance
Annex
16 of the EIAO-TM sets out the general approach and methodology for
assessment of ecological impacts arising from a project or proposal, to allow a
complete and objective identification, prediction and evaluation of the
potential ecological impacts. Annex 8 recommends the criteria that can
be used for evaluating ecological impacts.
8.1.8
United Nations Convention on Biological
Diversity of 1992
The Peoples’ Republic of China (PRC) is a
Contracting Party to the United Nations
Convention on Biological Diversity of 1992. The Convention requires signatories to
make active efforts to protect and manage their biodiversity resources. The HKSARG has stated that it will be
“committed to meeting the environmental objectives” of the Convention ([1]).
8.1.9
Convention on Wetlands of International
Importance Especially as Waterfowl Habitat (the Ramsar Convention)
The Convention
on Wetlands of International Importance Especially as Waterfowl Habitat
(the Ramsar Convention) applies to the HKSAR. The Convention requires parties to
conserve and make wise use of wetland areas, particularly those supporting
waterfowl populations. Article 1 of
the Convention defines wetlands as ‘areas of marsh, fen, peatland or water, whether
natural or artificial, permanent or temporary, with water that is static or
flowing, fresh, brackish or salt, including areas of marine water the depth of
which at low tide does not exceed six meters.’ The Mai Po/Inner Deep Bay wetland was
declared a Wetland of International Importance (“Ramsar site”) under the
Convention in 1995.
8.1.10
Wild Animal Protection Law of the PRC
The PRC in 1988 ratified the Wild Animal Protection Law of the PRC,
which lays down basic principles for protecting wild animals. The Law prohibits killing of protected
animals, controls hunting, and protects the habitats of wild animals, both
protected and non-protected. The
Law also provides for the creation of lists of animals protected at the state
level, under Class I and Class II.
There are 96 animal species in Class I and 156 in Class II. Class I provides a higher level of
protection for animals considered to be more threatened.
8.1.11
This study provides fisheries and marine
ecological assessment criteria for eight key water quality parameters,
including dissolved oxygen (DO) and suspended materials (SS) for use in impact
assessments. The study involved
measuring the biological effects of changes in water quality on five local
species of great ecological significance, representing important nekton,
benthos, zooplankton and phytoplankton in the marine environment of
8.2
Existing
Terrestrial Ecological Resources
The northwest
The
proposed land-based works will be confined to within the existing industrial
site (Figure 8.1).
To the west of the existing industrial site, shrublands are found on the
hills and plantations are found along the road. Cratoxylum
cochinchinense, Scolopia saeva and
Litsea rotundifolia are commonly recorded in the shrubland([3]). Due to the thin soil profile and rocky
substrate of the steep slope, the sub-storey growth of the shrubland is simple
and poor (1).
Patches of plantation can also be recorded in the north of the
industrial site. The plantation is
simple in structure and the sub-storey and under-storey growth was found to be
poor with little vegetative growth (1).
The tree species recorded at the north of industrial site were dominated
by exotic fast growing trees including Acacia
confusa, Leucaena leucocephala, Casuarina equisetifolia, Albizia lebbeck and Pinus elliottii, and accompanied by a
few native tree species such as Ficus
virens, Ficus microcarpus, Hibiscus tiliaceus, Macaranga tanarius, Bridelia
tomentosa, Celtis chinensis and
Sapium sebiferum ([4]).
No
natural habitats will be affected by the Project and no adverse impacts are
foreseen on the surrounding natural terrestrial habitats, and therefore do not
need to be addressed further in this EIA.
8.3
Existing Marine
Ecological Resources
8.3.1
Introduction
A review of relevant scientific literature, reports and EIA’s has been
conducted in order to assess the baseline ecological conditions of the Study
Area including, but not limited to, the following:
·
New Airport Master Plan (Greiner-Maunsell,
1991);
·
Proposed Aviation Fuel Receiving Facility
at Sha Chau: Environmental Impact Assessment (ERM, 1995);
·
Feasibility Study & Environmental
Impact Assessment for Aviation Fuel Pipeline (Montgomery Watson, 1996);
·
EIA Study for Disposal of Contaminated Mud
in the
·
Feasibility Study for Additional
Cross-border Links Stage 2 (Mouchel, 1998);
·
EIA for the Proposed Sand Extraction from
The Brothers’ Marine Borrow Area (Hyder Consulting, 1998);
·
Population Biology of the Indo-Pacific
Hump-backed Dolphin (Sousa chinensis Osbeck 1765) in Hong Kong Waters.
AFCD-funded study conducted by
·
Improvement
to
·
EIA
for Permanent Aviation Fuel Facility for
·
EIA
Study for Construction of Lung Kwu Chau Jetty (Maunsell 2002);
·
Environmental Monitoring and Audit for
Contaminated Mud Pit IV at East of Sha Chau (ERM, 1999; Mouchel, 2001a; ERM
2006-ongoing);
·
EA Study for Backfilling of Marine Borrow
Pits at North of the Brothers (Mouchel, 2004);
·
Detailed Site Selection Study for a Proposed
Contaminated Mud Disposal Facility within the Airport East/East of Sha Chau
Area. EIA and Final Site Selection Report (ERM
2005)
·
Monitoring
of Chinese White Dolphins (Sousa chinensis) in
As mentioned in Section 8.1, no adverse impacts to the
terrestrial ecology of the area are expected to occur as a result of the
construction and operation activities of the Project as the works on land are
confined to existing modified habitats.
The baseline characterisation of the Study Area is therefore focused
solely on the marine environment.
8.3.2
Baseline Ecological Conditions
Castle Peak Power Station is located in the north-western waters of the
In terms of water quality, the Study Area experiences relatively dynamic
estuarine-influenced conditions.
The waters are a mixture of flows from
Within the Study Area, there is one site of
recognised conservation interest.
The Lung Kwu Chau and
Based on the literature review the following habitats and/or organisms
of ecological interest have been identified within the Study Area:
·
Hard
Bottom Habitats;
·
Intertidal Hard Bottom Habitats
·
Subtidal Hard Bottom Habitats (Coral
Community)
·
Soft
Bottom Habitats;
·
Subtidal Soft Bottom Habitats
-
Epifaunal
Assemblages
-
Infaunal
Assemblages
·
Horseshoe
Crabs;
·
Marine
Mammals;
·
Sha
Chau and
8.3.3
Hard Bottom Habitats
Approximately 80% of
The zonation, composition and abundance of the species are strictly
related to the morphology of the coastline and the type of rocky outcrop. In
general terms biodiversity increases with the complexity of the coastal
morphology and decreases with the simplification of the natural habitats.
Intertidal Hard Bottom Habitats
No recent intertidal surveys
have been conducted on the shoreline
at
Qualitative intertidal surveys have been conducted in June 2006. There were two types of coastal
habitats, including natural rocky shore and artificial shoreline, recorded
within the Study Area (Figure 8.2). The
littorinid snails, including Nodilittorina radiata and Littoraria
articulata, were the dominant species in the high intertidal zone on
the rocky shore and artificial shoreline.
The snails Monodonta labio,
Nerita albicilla and
predatory dogwhelk Thais clavigera were recorded in the mid and low
shore region. Sessile
filter-feeding organisms such as the rock oyster (Saccostrea cucullata)
and barnacles (Tetraclita squamosa, Balanus amphitrite) were also
recorded on the shores. The faunal
communities present on the artificial seashore and natural rocky shore were
very similar. All of the species
recorded are common and widespread in
Biological diversity within the intertidal hard bottom
habitat of the Study Area is not, therefore, considered to be high. The artificial nature of long sections of the
shoreline within the Project Area further reduces the ecological value of the
intertidal hard bottom habitats.
Subtidal Hard Bottom Habitats - Coral
The Agriculture, Fisheries and Conservation Department reports that
there are over 80 species of corals recorded in
As part of a study for the EIA of the Aviation Fuel Receiving Facility
at Sha Chau, dive surveys were undertaken in order to investigate the hard
bottom communities ([7]).
The surveys found that only a few hermatypic hard corals (Family
Faviidae) were present within the subtidal of the survey area. Solitary corals have also been reported
at Sham Tseng and Tsing Lung Tau adjacent to
The results of these surveys are deemed representative of the type and
quality of the subtidal hard bottom habitats of the Study Area. As such, coral communities of ecological
value are not predicted to occur within the Study Area. Whilst it is possible that solitary
gorgonians and sea pens may be present within the subtidal areas, large or
important communities of hermatypic hard corals are not expected due to the
unfavourable conditions imposed by the water quality.
Further to update the current conditions of the proposed additional berthing
facility and dredging area, dive survey along the potentially affected
artificial seashore and seismic survey within the potentially disturbed seabed
were undertaken in January 2006.
The dive survey indicated that the visibility of the site was very poor
and generally ranged between 0.1 m and 0.3 m and deteriorated with depth. The surface of the boulders was covered
by a thick layer of sediments.
Isolated gorgonians Echinomuricea,
which are considered to be common in
Taking into consideration the limited ecological resources, high
sediment loads and highly disturbed seabed, the proposed additional berthing
facility site and dredging area are considered to be of low ecological concern.
8.3.4
Soft Bottom Habitats
Soft bottom habitats can be subdivided in intertidal and subtidal
habitats. Intertidal soft bottom habitats in
Subtidal Soft Bottom Habitats
Soft bottom habitats support both infauna and epibenthic faunal marine
communities, which in turn play a role as a food source for the majority of
Epifaunal Assemblages
Subtidal soft bottom habitats, as well as supporting infaunal species,
commonly support macro-benthic epifauna.
These organisms are generally greater than 1mm in size and live either
on or within the surface sediments.
A review of 10-years of data on fisheries resources collected from demersal
trawls conducted as part of the ongoing marine monitoring of contaminated mud
disposal at the East of Sha Chau Contaminated Mud Pits provides representative
data on epifaunal assemblages of the Study Area (in the vicinity of the Lung
Kwu Chau and Sha Chau Marine Park) ([11]).
The data indicate that epifaunal assemblages are dominated by gastropods
(e.g. Turritella terebra), crabs and
mantis shrimps. Abundance and
species composition is considered to be relatively low in comparison to other
areas in Hong Kong (such as the eastern and southern
Based on the above, the epifaunal assemblages of the Study Area are
considered to be of low abundance, diversity and biomass in comparison to other
areas of
Infaunal Assemblages
Soft sediments consisting of silt, clay and sand dominate the seabed of
The waters around the proposed terminal site were surveyed as part of a
Hong Kong wide study conducted in 1976 ([12]), however, the findings of this study are
considered to be no longer applicable due to the extensive development in both
Hong Kong and the Pearl River Estuary that has since occurred.
The most up-to-date study on soft bottom assemblages
has revealed that the benthic communities in Hong Kong can be divided into the
following broad types: a relatively similar benthic community covering the
majority of Hong Kong waters; an impoverished community in the northeastern
waters; a coarser sediment benthic group in Victoria Harbour; and a distinct
benthic group in Deep Bay ([13]).
The results of the 2001 study also indicated that the species diversity
and abundance of the benthos adjacent to Castle Peak were low to moderate in
comparison to other areas in
A recent study in the Tuen Mun area found
that the benthic infauna near Lung Kwu Tan, in the vicinity of Project Area,
has a generally mid-range total biomass and relatively high total number of
individuals in comparison to other areas of Hong Kong ([14]).
The fauna was found to be primarily polychaetes, which is typical for
8.3.5
Horseshoe Crabs
Two species of Horseshoe Crabs (Tachypleus tridentatus and Carcinoscorpius
rotundicauda) have been recorded in
8.3.6
Marine Mammals
A total of 16 (and possibly up to 18) species of marine mammals, or
cetaceans, have been recorded in
Studies on the distribution, abundance, habitat use, and life history of
humpback dolphins within
Historically, marine mammal data have been presented in terms of
sightings ([22]).
Recent analysis adopted in the marine mammals monitoring study ([23])
([24])
([25]) has allowed data to be standardised to
reflect numbers of sightings in terms of survey effort. Such data are considered to be closer to
a direct indication of abundance and habitat usage than raw observational
data. In order to utilise the most
up-to-date data, yet still allow comparison with previous studies to be made,
both types of data will be discussed.
Abundance of humpback dolphins in
Humpback dolphins exhibit a seasonal shifting in abundance and density
and thus a seasonal variation of abundance in different locations (Figure 8.4). The variation is thought to be due to
the increased input of freshwater from the discharge of the Pearl River Estuary
and the subsequent movements of estuarine prey species ([26]) ([27]) ([28]) .
Recently published information indicates that the abundance of dolphins
in
The recent studies on marine mammals in
In contrast to humpback dolphins,
studies on the finless porpoise indicate that the majority of sightings have
been recorded in the southern and eastern waters of
Based on an examination of the standardised dolphin sightings density
data, the waters in and around the Project Area are characterised as an area of
low to moderate level use by dolphins and it must be noted that the lowest
dolphin sighting densities occur in waters close to shore.
8.4
Evaluation of Ecological
Importance
The ecological resources and importance of marine habitats have been
characterised with reference to the available literature, comparisons with
other similar habitats in Hong Kong and the criteria presented in Annexes 8 and 16 of the Technical
Memorandum on Environmental Impact Assessment Process under the Environmental
Impact Assessment Ordinance (EIAO-TM).
The ecological importance of habitats is determined according to the EIAO-TM Annex 8 criteria, as follows:
·
Naturalness
·
Size
·
Diversity
·
Rarity
·
Re-creatability
·
Fragmentation
·
Ecological
Linkage
·
Potential
Value
·
Nursery
Ground
·
Age
·
Abundance
8.4.1
Intertidal Hard Bottom Habitat
The criteria listed above have been applied to the information gathered
or reviewed on the marine ecology of the intertidal habitats. The evaluation is
presented in Table 8.1.
Table 8.1 Ecological
Importance of Intertidal Hard Bottom Habitat
|
Criteria |
Intertidal Artificial Shoreline |
Intertidal Rocky Shore |
|
Naturalness |
Low.
Intertidal habitat in the Project Area as well as the areas in the
vicinity primarily consists of constructed artificial rubble mound seawall. |
Medium. Nearby natural rocky shore appears to
be relatively unaffected by human disturbance, but small in size. |
|
Size |
Artificial
seawall is the predominant hard bottom habitat in the vicinity of the Project
Area due to Castle Peak Power Station being partially situated on reclaimed
land. |
The
extent of intertidal hard bottom habitat consisting natural rocky shore in
the vicinity of the Project Area is small. |
|
Diversity |
The intertidal communities are composed of typical
biota of semi-exposed rocky shores in |
The intertidal communities are composed of typical
biota of semi-exposed rocky shores in |
|
Rarity |
No species recorded are considered rare or of
recognised conservation interest. |
No species recorded are considered rare or of
recognised conservation interest. |
|
Re-creatability |
Habitat is re-creatable. Intertidal biota may recolonise
intertidal hard bottom shores. |
Habitat is
re-creatable. Intertidal biota
may recolonise intertidal hard bottom shores. |
|
Fragmentation |
Low.
Intertidal hard
bottom habitat form a high proportion of intertidal habitats along
neighbouring coasts. |
Low. Intertidal hard bottom habitat form a high proportion of
intertidal habitats along neighbouring coasts. |
|
Ecological
Linkage |
The habitat
is not functionally linked to any high value habitat in a significant way. |
The habitat is not functionally linked to any high
value habitat in a significant way. |
|
Potential
Value |
None identified. It is unlikely that this habitat in the vicinity of the
Project Area can develop conservation interest. |
None
identified. It is unlikely that
this habitat in the vicinity of the Project Area can develop conservation
interest. |
|
Nursery
Area |
No significant records identified in the literature
review or field survey. |
No
significant records identified in the literature review or field survey. |
|
Age |
Artificial rubble mound seawall was
constructed approximately 30 years ago. |
Artificial
rubble mound sloping seawall was constructed approximately 30 years ago. |
|
Abundance |
Survey findings indicate intertidal biota
occur in low abundance. |
Survey
findings indicate intertidal biota occur in low abundance. |
|
SUMMARY |
The intertidal hard bottom habitat
supports assemblages of relatively low diversity and abundance, consisting of
common and widespread intertidal species with no recognised conservation
interest. |
The
intertidal hard bottom habitat supports assemblages of relatively low diversity
and abundance, consisting of common and widespread intertidal species with no
recognised conservation interest. |
|
Ecological Importance |
Low |
Low |
The intertidal hard bottom habitat
at
8.4.2
Subtidal Hard Bottom Habitat – Coral
In accordance with the criteria listed above, an evaluation of subtidal
hard bottom habitat based on the gathered or reviewed baseline information is
presented in Table 8.2.
Table 8.2 Ecological
Importance of Subtidal Hard Bottom Habitat - Coral
|
Criteria |
Subtidal Hard Bottom Habitat - Coral |
|
Naturalness |
Low. Subtidal hard bottom habitat in the
Project Area as well as the areas in the vicinity is mostly formed by
artificial sloping seawall. Hard
surfaces were covered by a thick layer of sediment. Dive surveys indicate
adjacent seabed is subject to a high degree of physical disturbance. |
|
Size |
Subtidal
hard bottom habitat in the vicinity of the Project Area is limited in extent
being confined to narrow strip at the base of the seawall. |
|
Diversity |
Low. Small isolated colonies of gorgonian
coral from the genus Echinomuricea were
recorded in the project area |
|
Rarity |
No corals
were identified which are considered rare. Echinomuricea
is among the most commonly occuring gorgonian corals in |
|
Re-creatability |
Habitat is re-creatable. Subtidal biota including corals may
recolonise subtidal hard bottom habitat. |
|
Fragmentation |
Low. Subtidal hard bottom habitat form
long continuous expanses along the margins of neighbouring rocky coasts. |
|
Ecological
Linkage |
The habitat
is not functionally linked to any high value habitat in a significant way. |
|
Potential
Value |
Low. It is unlikely that this habitat in the vicinity of the
Project Area can develop conservation interest. |
|
Nursery
Area |
No significant records identified in the
literature review or field survey. |
|
Age |
Artificial rubble mound seawall was
constructed approximately 30 years ago. |
|
Abundance |
Low. A sparse cover (<5%) of small isolated
gorgonians was recorded by dive surveys. |
|
SUMMARY |
The subtidal hard bottom habitat along
the potentially affected coast is characterised as a poor habitat for coral
growth owing to thick sediment layer on hard surfaces, estuarine conditions
and disturbance of adjacent seabed.
The potentially affected coast, which is artificial in origin,
supported sparse cover of small and isolated colonies of one type of
gorgonian coral, which is known to be commonly occurring across |
|
Ecological Importance |
Low |
The ecological importance of subtidal hard bottom habitat was classified
as low. Based on dive survey
observations, the subtidal hard bottom habitat is characterised as a poor
habitat for coral growth owing to the observed thick sediment layer on hard
surfaces. Prevailing estuarine
conditions and disturbance also restrict the potential for coral growth at this
site. Although gorgonian coral were
recorded on the potentially affected coast, which is artificial in origin, its
presence was not considered to be a significant record. The gorgonian Echinomuricea is a common species which occurs across
8.4.3
Subtidal Soft Bottom Habitat Epifaunal
Assemblages
The criteria listed above have been applied to the information reviewed
on the marine ecology of the subtidal soft bottom epifaunal assemblages habitat
within the Study Area. The
evaluation is presented in Table 8.3.
Table 8.3 Ecological
Importance of the Subtidal Soft Bottom Epifaunal Assemblages
|
Criteria |
Subtidal Soft Bottom Epifaunal
Assemblages |
|
Naturalness |
Habitat in the vicinity of the Project Area is
disturbed by fisheries activities and anchoring and may be affected by
regional water pollution to some extent. |
|
Size |
Large in
extent. Nearly all subtidal areas in the vicinity of the Project Area consist
of soft bottom habitat |
|
Diversity |
Assemblages
are considered to be of low diversity in comparison to other areas in |
|
Rarity |
No
organisms were recorded that are considered as rare or of recognised conservation interest. |
|
Re-creatability |
Subtidal
soft bottom habitats can be easily re-created. Benthic organisms may
recolonise the disturbed seabed area within a relatively short time. |
|
Fragmentation |
The habitat is not fragmented |
|
Ecological
Linkage |
Epibenthic fauna act as a food source for
demersal fisheries; however the habitat is not functionally linked to any
high value habitat. |
|
Potential
Value |
Low. Subtidal soft bottom epifaunal assemblages are
unlikely to develop conservation interest. |
|
Nursery
Area |
No significant records identified in the literature
review or field survey. |
|
Age |
The sediments in the habitat are
constantly accreting and eroding and the fauna present there are typically
short lived. |
|
Abundance |
In comparison to other parts of |
|
SUMMARY |
Subtidal soft bottom epifaunal
assemblages in the vicinity of the Project Area occur over a large
unfragmented area, are disturbed to some extent by fisheries activities and
pollution, and consist of epibenthic fauna in low abundance and diversity in
comparison to other areas in |
|
Ecological Importance |
Low - Medium |
Subtidal soft bottom epifaunal assemblages are large in extent and are
subject to frequent disturbance by fisheries activities. Although
the epifauna were recorded to have low abundance and diversity, epifauna serve
as a food source for demersal fisheries. The
ecological importance of this habitat was therefore considered to be low to
medium.
8.4.4
Subtidal Soft Bottom Habitat Infaunal
Assemblages
Information on the marine ecology of soft bottom infaunal assemablages
has been evaluated in accordance with the criteria listed above. The evaluation is presented in Table 8.4.
Table 8.4 Ecological
Importance of the Subtidal Soft Bottom Infaunal Assemblages
|
Criteria |
Subtidal Soft Bottom Infaunal
Assemblages |
|
Naturalness |
Habitat in the vicinity of the Project Area is
disturbed by fisheries activities and anchoring and may be affected by
regional water pollution to some extent. |
|
Size |
Large in
extent. Nearly all subtidal areas in the vicinity of the Project Area consist
of soft bottom habitat |
|
Diversity |
Low to
moderate in comparison to other areas in |
|
Rarity |
No
organisms were recorded that are considered as rare or of recognised conservation interest. |
|
Re-creatability |
Subtidal
soft bottom habitats can be easily re-created. Benthic organisms may
recolonise the disturbed seabed area within a relatively short time. |
|
Fragmentation |
The habitat is not fragmented. |
|
Ecological
Linkage |
The benthic infauna act as a food source
for epibenthic organisms, however the habitat is not functionally linked to
any high value habitat. |
|
Potential
Value |
Low. Subtidal soft bottom infaunal assemblages are
unlikely to develop conservation interest. |
|
Nursery
Area |
No significant records identified in the
literature review. |
|
Age |
The sediments in the habitat are
constantly accreting and eroding and the fauna present there are typically
short lived. |
|
Abundance |
Low to moderate in comparison to other
areas in |
|
SUMMARY |
Subtidal soft bottom infaunal assemblages
in the vicinity of the Project Area occur over a large unfragmented area, are
disturbed to some extent by fisheries activities and pollution, and consist
of infauna in low to moderate abundance and diversity in comparison to other
areas in |
|
Ecological Importance |
Low - Medium |
Subtidal soft bottom infaunal
assemblages also occur over large areas.
In comparison to other areas in Hong Kong, the soft bottom habitat in
the vicinity of
8.4.5
Horseshoe Crab Habitat
Based on the criteria listed above
the ecological importance of horseshoe crab habitat is evaluated in Table 8.5.
Table 8.5 Ecological
Importance of the Horseshoe Crab Habitat
|
Criteria |
Horseshoe Crab Habitat |
|
Naturalness |
Subtidal soft bottom habitat in the
vicinity of the Project Area is disturbed by fisheries activities and
anchoring. Horseshoe crab
breeding grounds recorded at sites along the Deep Bay and North Lantau
coasts, which are located far away from the Project Area (at least >2km),
may be affected by regional water pollution to some extent. |
|
Size |
There are
no records in the literature of Horseshoe crabs in the immediate vicinity of
the Project Area. The nearest
known breeding grounds occur along relatively short stretches of Deep Bay
coast at Lung Kwu Sheung Tan and Pak Nai, which are distant from the proposed
site. |
|
Diversity |
Two
species: Tachypleus tridentatus and
Carcinoscorpius rotundicauda |
|
Rarity |
Locally,
Horseshoe crabs are considered to be species of conservation interest. |
|
Re-creatability |
Horseshoe crab habitats are not easily re-created. |
|
Fragmentation |
Marine waters inhabited by Horseshoe
Crabs are not fragmented. Horseshoe crab breeding grounds are spread along
the |
|
Ecological
Linkage |
The habitat
is not functionally linked to any high value habitat in a significant way. |
|
Potential
Value |
The area in the vicinity of the proposed
project is unlikely to develop conservation interest. |
|
Nursery
Area |
The artificial rocky shore of the Project
Area is not suitable and cannot be used as a nursery grounds for Horseshoe
Crabs. There are no records of Horseshoe Crab nursery grounds in the vicinity
of the Project Area. |
|
Age |
The sediments in the habitat are
constantly accreting and eroding though Horseshoe Crabs can be long-lived. |
|
Abundance |
Populations of Horseshoe crab are known
to have declined drastically in recent years. |
|
SUMMARY |
There are no records of Horseshoe crabs
in the vicinity of the Project Area. This area, therefore does not appear to
be important habitat for Horseshoe Crabs. The subtidal soft bottom habitat in
the vicinity of the project area is disturbed, particularly by fisheries
activities and the potentially affected hard bottom coast is not amenable to
function as a Horseshoe Crab nursery. Nursery grounds for Horseshoe
Crabs, which are of high ecological importance are located at distant
locations from the proposed project area. |
|
Ecological Importance |
Low |
Based on a review of the relevant
literature, there are no records of Horseshoe crabs in the vicinity of the
Project Area in terms of captured or live sighting on the shore. It would appear that the area in the
vicinity of
8.4.6
Marine Mammal Habitat
The same assessment criteria have been applied to the marine waters
within the Study Area with regard to the usage of the area by marine
mammals. The evaluation is
presented in Table 8.6.
Table 8.6 Ecological
Importance of Marine Mammal Habitat
|
Criteria |
Marine Mammal Habitat |
|
Naturalness |
The marine
mammal habitat in the vicinity of the Project Area is disturbed by marine
traffic using the Urmston Road Channel as well as fisheries operations and
regional water pollution to some extent. |
|
Size |
Waters in
the vicinity of the project area comprise a small portion of the range of the
Indo-Pacific Humpback dolphin, which includes virtually all of |
|
Diversity |
The
resident species, Indo-Pacific Humpback dolphin, Sousa chinensis is the only species sighted in the vicinity of
the Project Area. |
|
Rarity |
There are
approximately 1,300 dolphins in the Pearl River Estuary of which about 360
are thought to include |
|
Re-creatability |
This habitat cannot be recreated. |
|
Fragmentation |
Marine mammal habitat is not fragmented. |
|
Ecological
Linkage |
Sightings of dolphins are more frequent
to the west and |
|
Potential
Value |
Owing to their location next to the busy |
|
Nursery
Area |
No sightings of unspotted calves and
unspotted juveniles have been recorded in the vicinity of the Project Area. |
|
Age |
Habitats provided by marine waters are
permanent. |
|
Abundance |
Waters around the project site are a low density
area for dolphins (SPSE 0.1 – 4).
Moderate dolphin densities (SPSE 15 – 19) occur in nearby waters (~1km
away), while high density areas (SPSE >20) are located off the east coast
of |
|
SUMMARY |
The waters in and around |
|
Ecological Importance |
Low for the Project Area Medium for the waters in the immediate
vicinity of |
Taken as a whole,
8.4.7
Species of Recognised or Potential
Conservation Interest Conservation Interest
In accordance
with EIAO-TM Annex 8 criteria,
species of recognised or potential conservation value and their conservation
and protection status, are presented in Table
8.7.
Table 8.7 Species
of Recognised or Potential Conservation Interest within the Study Area
|
Common
Name |
Scientific Name |
Protection Status |
Distribution,
Rarity and other Notes |
|
Indo-Pacific
Humpback Dolphin (also known as the Chinese White Dolphin) |
Sousa chinensis |
Wild
Animals Protection Ordinance, Animals and Plant Ordinance Class I Protected
Species in the PRC. CITES Appendix 1 |
Range
across Pearl River estuary and across Hong Kong western and Southern Waters
from |
|
Horseshoe
Crabs |
Tachypleus tridentatus and Carcinoscorpius rotundicauda |
Not
protected in |
Populations
have drastically declined in recent years. Distribution primarily known from
records on intertidal nursery grounds at locations across Hong Kong from |
8.4.8
Summary of the Ecological
Importance of Marine Habitats
According to the evaluation presented above, the ecological importance
of habitats in the vicinity of
Located about 5km to the west of
Table 8.8 Ecological
Importance of Marine Habitats
|
Habitat |
Ecological
Importance |
|
Intertidal Hard
Bottom |
Low |
|
Subtidal Hard
Bottom |
Low |
|
Subtidal Soft
Bottom-Epifauna |
Low-Medium |
|
Subtidal Soft
Bottom-Infauna |
Low-Medium |
|
Horseshoe Crab |
Low |
|
Marine Mammal |
Low for the Project Area Medium for the waters in the vicinity of |
A desk-top literature review presented in the previous sections was
conducted in order to establish the ecological profile of the Study Area. The importance of potentially impacted
marine ecological resources identified within the Study Area was assessed using
the methodology defined in the EIAO-TM. The potential impacts on the marine
environment due to the construction and operational phases of the Project were
then assessed (following the EIAO-TM Annex 16 guidelines) and the
significance of the impacts evaluated (based on the criteria in EIAO-TM Annex 8).
8.6
Potential Sources
of Impact
The Project’s construction and operation potential sources of impact to
the marine ecological resources of the Study Area have been identified in the
following sections.
8.6.1
Construction Phase
As discussed in Section 1, the
construction of the proposed additional berthing facility will involve the
following marine works:
·
Removal
and reinstatement of boulders on the existing seawall;
·
Dredging
of the foundations of the additional berthing facility;
·
Construction
of the additional berthing facility and seawall which will include percussive
piling and laying of armour rock;
·
Dredging
of a turning basin to a depth of approximately –8.2 mPD of an area of about 3
ha to the west of the existing Heavy Load Berth.
Impacts to marine ecological resources arising from the Project’s
construction works may be divided into direct and indirect impacts:
·
Direct Impacts are those attributable to direct disturbances to the
habitat such as the loss of habitat due to dredging or removal of existing
substrates (soft and hard). Direct
impacts have been identified only within the Project Area which delineates the
permanent footprint of the Project;
·
Indirect Impacts are those attributable to perturbations
to key physical and chemical water quality parameters such as suspended solids,
contaminants, dissolved oxygen, etc.
Other potential indirect impacts to the marine environment include:
underwater noise emissions from construction activities (construction vessels,
percussive piling, etc.) and increased marine traffic.
Direct Impacts
Habitat Loss
Intertidal
and Subtidal Hard Bottom Habitats
A total length of approximately 100 m of low ecological value artificial
shore will be temporarily lost as the materials of the existing seawall will
partially be removed to allow the construction of the additional berthing
facility.
The results of the literature review indicated that the intertidal and
subtidal assemblages recorded on the rocky shores within the Project Area are
typical of rocky shore communities observed in
It is anticipated that assemblages of intertidal and subtidal organisms,
which included marine snails, barnacles, oysters and gorgonians, will settle on
and recolonise the new structures as they rely primarily on larval settlement
for recruitment ([37])
([38]).
Assuming that there is a regular supply of larvae brought to the area,
regeneration of the existing habitat will occur in a relatively short time as
the environmental conditions of the area will remain similar to existing
conditions that have allowed the growth of intertidal and subtidal organisms.
In view of the low ecological value of the existing hard bottom habitats
within the Project Area, the short term duration of the works and the overall
increase in artificial hard bottom habitats, which will provide suitable
substrata for recolonisation by similar assemblages, the impacts associated
with the temporary loss of intertidal and subtidal hard bottom habitats within
the Project Area would be minor.
Subtidal
Soft Bottom Habitats
To allow access to the proposed additional
berthing facility, there is a requirement for dredging of a turning basin. Dredging will involve the removal of the
upper strata of sediments (an average thickness of approximately 2.5 m) to a
depth of approximately -8.2 mPD which will lead to the loss of the benthic
assemblages present. This dredging
will lead to the temporary loss of approximately 3 ha of subtidal soft bottom
habitat. According to the proposed
construction schedule, these works will be conducted by one grab dredger and
will take about 6 weeks to complete.
A review of the baseline ecological
conditions of the Study Area indicates subtidal soft bottom assemblages
comprise typical species in low or moderate abundance and diversity and are of
no particular conservation interest.
It was noted that these assemblage are subjected to disturbance from
sources, particularly bottom trawling activities by fishing vessels and water
pollution. The marked contribution of pollution tolerant species to infaunal
assemblages reflects the effects of water pollution on these assemblages.
The size of the proposed dredging area
(about 3 ha) is considered to be relatively small in the context of large
expanse of contiguous subtidal soft bottom habitat of the Study Area. Subtidal soft bottom habitat is the
predominant type of bottom substrata throughout the marine study area.
The loss of subtidal soft bottom habitat in the turning basin is
considered to be temporary in nature.
Following the completion of the dredging works, the newly exposed bottom
sediment will be available for recolonisation by benthic fauna.
The speed of recovery of the benthic community, through an influx of
colonising organisms, is dependent on the timing of the dredging in relation to
the timing of reproduction and or migration. While this may only be on a few
occasions during the year for the macrobenthic organisms, studies of meiofaunal
recolonisation after sediment disturbance indicate that partial recovery occurs
within a few tidal cycles ([39]).
Furthermore it must be noted that benthic
species that live in dynamic estuarine conditions such as those present within
the Project Area will be naturally tolerant to disturbances of the substrate
and sediment movement and will most probably have high recolonisation ability.
Indirect Impacts
Changes in Water Quality
Construction activities will involve dredging of the existing marine
sediments within the Project Area to provide suitable foundations for the
additional berthing facility and sufficient depth to allow the safe approach
and manoeuvre of the bulk carriers.
Dredging works will involve one grab dredger for a duration of 6 weeks. As assessed in the Water Quality Assessment (Section
5), these dredging activities will lead to a localised increase in the
concentration of suspended solids (SS) in the water column.
Several potential impacts to the water quality parameters and in turn
the marine environment are associated with an increase in SS concentration,
namely:
·
Physical
Damage or Disturbance: Physical damage or disturbance (displacement from the
natural habitat) of organisms may occur as a result of the deposition of SS which
will smother or bury the substrates within and around the Project Area. SS have
the potential to harm filter-feeding sessile organisms (e.g. bivalves) or
damage gill membranes potentially leading to suffocation;
·
Reduction
in Dissolved Oxygen (DO): Increase in natural turbidity and reduction of
incident solar radiation may impair photosynthesis and ultimately reduce the
concentration of DO. Additionally SS may contain organic matter which is
subject to oxidation and may
aggravate oxygen depletion;
·
Increase
in Nutrients concentration: due to the re-suspension of nutrients “trapped”
within the sediments potentially leading to eutrophication and algal blooms;
·
Increase
the concentrations of polluting agents or contaminants potentially present in
the re-suspended solids.
It should be noted, that owing to seasonal inputs
from the Pearl and Shenzhen Rivers, suspended solids in the North-western
waters of Hong Kong vary over a wide range occasionally exceeding levels of 100
mg L-1 in the dry season ([40]) and it is likely that the organisms
present are adapted to short-term elevated suspended solid inputs.
In addition, the water quality assessment in Section 5 predicted that the elevations
in suspended solids due to the dredging would be localised and mostly confined
to the bed layer and well within the range of natural variability for
north-western waters. According to
the model, elevations in SS due to the dredging would not exceed 50 mg L-1
and WQO levels (see Annex C2 - Figures C1 & C2). The model also predicted that there
would not be any substantial accumulation of re-deposited sediments likely to
adversely affect benthic or pelagic organisms. Moreover, in line with common local
construction practice, the dredging vessel will be equipped with a silt curtain
which will serve to limit sediment dispersion away from the dredger.
The following sections outline the potential impacts of the SS deriving
from the construction activities of the Project on the marine habitats
identified within the Study Area.
Physical Damage or Disturbance:
·
Intertidal and Subtidal
Hard Bottom Habitats: Due to the low quality of the hard bottom habitats
identified within the Study Area and their natural exposure to high levels of
suspended solids in the Pearl River Estuary, adverse impacts to the intertidal
assemblages arising from elevated SS levels are not anticipated. Furthermore,
no subtidal hard bottom habitats (including hard and soft coral assemblages) of
ecological interest have been recorded within or in the vicinity of Project
Area. Gorgonians observed during
dive surveys are known to be highly tolerant of high turbidity conditions. Owing to their flexible branches and
erect growth form, gorgonians are not prone to sediment accumulation. No adverse impacts to corals are
predicted to occur.
·
Subtidal Soft Bottom Habitats:
The subtidal soft bottom habitat within the Study Area is considered to
be of low to medium ecological value. However, the benthic organisms within and
around the Project Area will be susceptible to the effects of increased
sediment loads through smothering and burial. Although sediment may be deposited on
the seabed outside the Project Area during dredging activities, the dispersion
of sediment plumes is expected to be confined to a small area as sediment will
be deposited within a short distance of the dredging works (Section 5). As the area is characterised by SS laden
discharges from the
·
Horseshoe Crab Habitat: The extent of the horseshoe crab habitat
identified within the Study Area is very limited and overall of low ecological
value. Furthermore, levels of SS identified in Section 5 for the areas identified in the literature review as
horseshoe crab nursery grounds (ie
·
Marine Mammals: High SS
levels do not have a direct impact on dolphins. Indo-Pacific Humpback Dolphins are
well-adapted for hunting in turbid waters owing to their use of echolocation
rather than visual information. In
addition, dolphins are air breathing and therefore SS in the water column has
no effect on their respiratory surfaces.
However it must be noted that the proposed dredging may cause
perturbations to the fisheries resources on which the Indo-pacific humpback
dolphin feeds (especially Sciaenidae, Engraulids, Clupeids and Trichiurids). A deterioration in water quality has the
potential to displace these fish from the affected area thus interfering with
the dolphin normal feeding patterns.
From a review of the Water Quality
Assessment results (Section 5) it
emerges that indirect adverse impacts on fisheries are not expected to occur due to
the localized nature of the impact on the water quality parameters. Furthermore, in line with common local
construction practice, the dredger will be equipped with a silt curtain which
will serve to limit sediment dispersion away from the dredger. Furthermore, it should be noted that the the dolphin, and their prey species are
naturally exposed to high levels of suspended solids in the Pearl River
Estuary, further reducing any potential impacts associated with SS. For instance, ambient SS levels off of
Castle Peak range up to 210 mg L -1 (refer to Table 5.5). In
comparison, elevations in SS levels due to the dredging works (<50 mg L -1)
are relatively small and within the range of natural variability.
·
Sha Chau and
Dissolved Oxygen:
The results of the Water Quality Assessment (Section
5) examining the dispersion of sediment plumes associated with all marine
works has shown that the predicted maximum levels are localised. Concentrations within the Study Area as
a whole will remain compliant with the Water Quality Objectives (WQOs). The subsequent effect on dissolved
oxygen within the surrounding waters is, therefore, predicted to be minimal and
unacceptable impacts to marine ecological resources are not expected to occur.
Nutrients:
High levels of nutrients (total inorganic nitrogen - TIN and ammonia) in
seawater can cause rapid increases in phytoplankton to the point where an algal
bloom may occur. An intense bloom
of algae can lead to sharp increases in DO levels in surface water. However, at night and when these algae
die there is usually a sharp decrease in the levels of dissolved oxygen in the
water, as dead algae fall through the water column and decompose on the
bottom. Anoxic conditions may
result if DO concentrations are already low or are not replenished. This may result in mortality to marine
organisms due to oxygen deprivation.
The results of the Water Quality
Assessment (Section 5) have
indicated that low levels of SS elevations are expected outside of the Project
Area. Consequently, elevations in
nutrients desorbed from the sediment particles are expected to be in low
concentrations. Algal blooms are
therefore not expected through works and unacceptable impacts to the marine
ecological habitats and populations present in the Study Area will not occur.
Contaminants:
As outlined in Sections 5 and 6, the sediments within the Study Area
are not heavily contaminated therefore an increase in polluting agents or
contaminants released by the sediment particles during dredging activities is
not expected to occur and no unacceptable impacts to the marine ecological
resources of the Study Area are estimated.
Underwater Noise
Overview
Cetaceans use two functional classes of sound: echolocation and
communication. Echolocation is used
for orientation, navigation, prey detection and learning about the surrounding
environment, whilst communication is primarily used for intraspecies signalling
([41]). Indo-Pacific Humpback Dolphin vocalise
through the production of clicks, rapid click sequences (screams) and whistles ([42]).
Noise is transmitted efficiently through water and cetaceans are known
to be able to detect submarine noise created by activities such as shipping
over several kilometres from the source ([43]).
Sounds introduced into the marine environment have the potential to
interfere with the dolphins’ ability to detect calls from other individuals,
echolocation pulses or other natural sounds ([44]).
Noise can also lead to a disruption of dolphin behaviour. Disruption of feeding, resting and
social interactions have all been attributed to elevated sounds. Elevated noise of sufficient intensity
can also damage the hearing sensitivity and loud impulsive sounds from
activities such as percussive piling not only have the potential to cause
disturbance, but also cause physical damage. The organs used in hearing and air-filled
cavities such as the lungs are particularly susceptible to physical injury from
extremely loud impulsive sounds.
Elevated noise levels are potentially the most important impact to the
dolphin population in the Study Area. The main underwater noise sources
attributable to the Project’s construction activities are:
·
Piling
works;
·
Construction/Dredging
Vessels.
Both sources and their potential impacts on the Indo-pacific humpback
dolphin have been addressed in the following sections.
Percussive Piling
Piling works will be required to construct the proposed additional
berthing facility and based on the engineering conditions of the proposed
construction site, percussive piling techniques will be utilised. The estimated duration of the piling
works to complete the 140 m long structure is 6 weeks.
Noise from percussive piling activities will be transmitted to the water
via both structure-borne and air-borne noise pathways. Structure-borne vibrations from the
percussive hammer will be re-radiated as sound into the water via the piles,
the substrata and the piling rig to the barge. The air-borne noise pathway consists of
sound propagation from the percussive hammer and the piles through the air and
into the water. The noise
transmitted to the water via the air-borne noise path is not expected to be
significant as a large proportion of this noise will be reflected at the water
and air interface and therefore not penetrate the water.
Dolphins, in general have acute hearing above 500Hz and have been found
to communicate within the 400 to 800 Hz range ([45]).
Activities such as percussive piling have their highest energy at lower
frequencies from about 20Hz to 1kHz and, whilst smaller cetaceans (about 3 to 4m in length) are not known to be
highly sensitive to sounds below 1kHz, they can hear in much of this range and
sounds in their vicinity could induce changes in behaviour and interfere with
communication.
Experience of percussive piling in marine waters of
Finally, in line with current common local practice, the percussive
piling equipment used in
It is apparent from the above that the underwater construction noise
will not have any detrimental effect on the populations of the cetaceans. The extent to which dolphins would be
affected is expected to be low.
Construction Vessels
Construction activities will result in an increase in marine traffic and
underwater noise. Dredging and
large vessels traffic generally results in mostly low frequency noise typically
in the range of 0.02 to 1 kHz ([48]) which are below the peak range of 8 to 90
kHz reported for dolphins. For this
reason, noise generated by dredging operations is not expected to acoustically
interfere with dolphins.
This prediction is consistent with other EIA and environmental
monitoring studies in
It should also be noted that, due to the heavy marine traffic that
characterises the waters of the Study Area (particularly Urmston Road), the
existing background noise level are comparatively high, further reducing any
potential impacts to the dolphins due to the underwater noise generated by the
dredging or construction vessels.
Marine Traffic
Increased vessel movements during construction activities may increase
physical risks to the Indo-pacific humpback dolphins or cause changes in
behaviour if dolphins are harassed.
In
8.6.2
Operational Phase
Hydrodynamic Regime
The construction of the proposed additional berthing facility will bring
about a change in the shape of the existing coastline. This may potentially lead to a change in
the hydrodynamic regime of the surrounding waters and adversely affect the
marine ecological resources within the Study Area. Impacts of this nature could lead to
increased seabed current velocities which may cause seabed scour thus impacting
subtidal assemblages, or conversely the current speeds may drop, affecting
flushing and water exchange of an area.
Inadequate flushing could lead to a reduction in dissolved oxygen, an
increase in nutrient levels and consequent impacts to marine ecological
resources.
The effects of changes in coastal configuration on the current
velocities have been assessed (see Section
5). The hydrodynamic modelling
has indicated that the construction of the proposed additional berthing
facility will have little effect on current velocity. Consequently, no operational phase
impacts on marine ecological resources due to changes in the hydrodynamic
regime are expected.
Vessel Traffic
The daily maximum number of Dry Bulk Carrier movements at the proposed
additional berthing facility is not anticipated to be more than 1 per day ([52]).
Owing to the low frequency of the loading and unloading activities of
the bulk carriers, no adverse impacts on the marine resources of the Study Area
are expected. Moreover the slow
approach/manoeuvring speed of the vessels further reduces the risk of collisions
or strikes to Indo-Pacific Humpback Dolphins.
Discharge Water
As
discussed in Section 1, the treated
effluent from the FGD process may have a small chemical oxygen demand (COD)
and/or reduced dissolved oxygen (DO) concentrations. A residual portion of the ash in the
flue gas will likely be entrained within the limestone slurry and retained in
the treated effluent.
The treated effluent will be added to the
cooling water flows and discharged via the cooling water outfall, resulting in
a small increase in the total flows from the outfall. The treated effluent is not expected to
increase the temperature or the residual chlorine levels of the cooling water
discharge.
The potential impacts of the discharge are
principally related to the ecological effects associated with the COD increase
and DO reduction. The water quality
model (Section 5) has however
predicted that the changes in the water quality parameters of the Project Area
will be minimal and the effected zone confined to the immediate surroundings of
the outfall. No adverse impacts on
the marine ecological resources of the Study Area are therefore expected to
occur.
Two
projects are identified which may occur concurrently with the marine works of
this proposed project. One of these,
The Permanent Aviation Fuel Receiving Facility for
8.7
Evaluation and
Significance of The Marine Ecological Impacts
The following section discusses and evaluates the
impacts to marine ecological habitats as a result of the resources identified
in the previous Sections. Based
upon the information presented above, the significance of the marine ecological
impacts associated with the construction and operation of the proposed
additional berthing facility have been evaluated in accordance with the EIAO-TM (Annex 8, Table 1) as follows:
·
Habitat Quality:
Direct and indirect impacts are predicted to occur only to the low
quality coastal habitats (intertidal and subtidal) and benthic habitats
identified within the Project Area.
The construction and operation activities will not affect habitats of
high ecological value such as the Sha Chau and
·
Species: Organisms
of ecological interest reported from the literature include the Indo-Pacific
Humpback Dolphin (Sousa chinensis). Significant impacts are not predicted to
occur to this species due to planned marine works as water quality
perturbations are predicted to be transient and compliant with the marine
ecological assessment criterion([53]).
The percussive piling works and its underwater noise disturbance may
result in avoidance of areas in the vicinity of the works by dolphins. However, any avoidance of the area would
be temporary and individuals are expected to return to the affected area after
the marine works are finished. It
is anticipated that indirect, temporary disturbance to dolphins are not
expected during marine piling works as construction methodologies have been
designed to reduce underwater noise.
Operational phase discharges or marine vessel movements are not expected
to impact the dolphins present in the Study Area.
·
Size: The total
size of the proposed dredged area will be approximately 3 ha. Low ecological value intertidal,
subtidal hard surface and waters within the Project Area, and low-medium
ecological value benthic assemblages within the Project’s footprint will be
directly impacted. The low-medium
ecological value benthic assemblages within certain areas of the dredged areas
will be affected during construction but are expected to become re-established
with time.
·
Duration: The
duration of the construction activities is expected to be approximately 10
months. The duration for the
percussive piling will last approximately six weeks. The underwater noise impact is unlikely
to adversely affect the dolphin assuming provision of proper mitigation
measures. Operational phase discharges
will continue during the life of power station but are not predicted to cause
adverse impacts to marine ecological resources as the alterations to the water
quality parameters are minimal.
·
Reversibility: Impacts to the benthic assemblages inhabiting the
soft bottom habitats within the dredged areas are expected to be relatively
short term and recolonisation of the sediments is expected to occur. Similarly the low ecological value
assemblages present on the artificial seawall can be expected to recolonise the
seawall and berthing structure once it is constructed.
·
Magnitude: No unacceptable impacts to the ecologically sensitive
habitats have been predicted to occur.
Operational phase impacts are not expected to cause adverse impacts and
are considered to be of low magnitude.
The
impact assessment presented above indicates that no unacceptable impacts to
marine ecology are expected to occur.
Although soft bottom habitat will be temporarily lost, it has been
demonstrated through long-term monitoring of previously dredged areas and
existing Contaminated Mud Pits in the East of Sha Chau area that marine
organisms have recolonised the areas following the completion of the works ([54]). As such, it is anticipated that subtidal
assemblages influenced by dredging will settle on and recolonise the seabed
returning it to the former conditions.
The previous discussion has indicated that
the loss of intertidal and subtidal hard bottom assemblages within the Project
Area is expected to be compensated through the recolonisation of the new
seawall and berthing structure once construction has been completed. It is anticipated that intertidal and
subtidal assemblages similar to the existing ones, will settle on and recolonise
the new surfaces.
Finally, it is anticipated that the
underwater construction noise arising from construction activities may result
in temporary avoidance of areas in the vicinity of the works by dolphins. However, individuals are expected to
return to the affected area after the marine works are finished. Local construction practice such as
bubble curtains/jackets will be used during piling works
8.8
Summary of
Mitigation Measures
Measures to mitigate the
impact of the construction and operation activities have been developed. The following recommendations should be
considered to minimize potential construction and operational impacts on
dolphins and porpoises:
·
All vessel operators working on the Project
construction or operation should be given a briefing, alerting them to the
possible presence of dolphins in the area, and the guidelines for safe vessel
operation in the presence of cetaceans.
If high speed vessels are used, they should be required to slow to 10
knots when passing through a high density dolphin area (west Lantau, Sha Chau
and Lung Kwu Chau);
·
The vessel operators should be required to use predefined and
regular routes, as these will become known to dolphins using these waters;
·
The vessel operators should be required to control and manage all effluent from
vessels;
·
A policy of no dumping of rubbish, food, oil, or
chemicals should be strictly enforced.
This should also be covered in the contractor briefings;
·
Every attempt should be made to minimize the effects
of construction of the Project on the water quality of the area;
To limit potential impacts to cetaceans from
underwater percussive piling, the following steps should be taken:
·
Quieter hydraulic hammers should be used
instead of the noisier diesel hammers;
·
An exclusion zone of 500 m radius should be scanned around the work area
for at least 30 minutes prior to the start of piling. If cetaceans are observed in the
exclusion zone, piling should be delayed until they have left the area; and,
·
Acoustic decoupling of noisy equipment on work barges should be
undertaken. These techniques
include the use of a soft sling to retain the pile driving hammer, rubber tyred
air compressor for bubble jacket/curtain, rubber pads on barge leaders and
guides, and an air curtain around the pile barge.
Periodic
re-assessment of mitigation measures for marine mammals and their effectiveness
should be undertaken. The cetaceans monitoring should be conducted by a
qualified team during the underwater percussive piling.
8.9
Residual Environmental
Impacts
Taking into consideration the ecological value of the habitats discussed
in the previous sections and the resultant mitigation requirements, residual
impacts occurring as a result of the proposed construction and operation
activities have been determined and are as follows.
·
The
loss of approximately 100 m of artificial intertidal and subtidal hard bottom
habitat of low ecological value.
The residual impact is considered to be acceptable, as the loss of these
habitats will be compensated by the provision of a new seawall and
approximately 140 m of the additional berthing facility that have been
demonstrated to become recolonised by assemblages of a similar nature after
construction;
·
Approximately
3 ha of subtidal soft bottom assemblages within the dredged area will be
temporarily disturbed. The residual
impact is considered to be acceptable as the habitat of low ecological concern
will be reinstated shortly after construction and no residual impact will be
expected.
8.10
Environmental
Monitoring and Audit
The implementation of the ecological
mitigation measures described in Section
8.9 should be checked as part of the environmental monitoring and audit
(EM&A) procedures during the construction period. No other ecology specific measures are
considered necessary.
Visual cetaceans monitoring
should be conducted during the underwater percussive piling
works to evaluate whether there have been any effects on
the animals
and the details are presented in the Section
10.
Following a detailed literature review of the existing marine ecological
resources of the Study Area, two key sensitive receivers have been identified:
the Sha Chau and
The predicted alterations of the water quality parameters attributable
to construction and operation activities are not expected to cause exceedances
of the WQO, and hence no significant impacts to the marine ecological resources
or marine mammals, are anticipated.
Local construction practice of using bubble curtains/jacket during percussive piling work will be
adopted for the construction of the additional berthing facility. Mitigation measures designed to minimise
impacts to the population of Indo-pacific humpback dolphins that use the area
include restrictions on vessel speed.
Other mitigation measures designed to mitigate impacts to water quality
to acceptable levels (compliance with WQOs) are also expected to mitigate
impacts to marine ecological resources.
