This section of the EIA Report presents the findings of
the marine ecological impact assessment associated with the construction and
operation of the Gas Receiving Stations (GRSs) and
submarine gas pipelines in the Black Point area. It summarises baseline information
gathered from the literature review and ecological surveys on the marine
ecological resources at Black Point.
The methodologies and results of the literature review and baseline
surveys are presented in Annex 8A.
8.2
Relevant
Legislation & Assessment Criteria
The criteria for evaluating marine ecological impacts
are laid out in the EIAO TM and Study
Brief (ESB-208/2009). Annex
16 of the EIAO TM sets out the
general approach and methodology for the assessment of impacts to marine
ecological resources arising from a project or proposal. Annex
8 of the EIAO TM recommends the
criteria that can be used for evaluating such impacts.
Legislative requirements and evaluation criteria
relevant to this Study for the protection of species and habitats of marine
ecological importance are listed below.
The details on each are presented in Annex 8A.
·
Marine Parks Ordinance (Cap 476);
·
Wild Animals Protection Ordinance (Cap
170);
·
Protection of Endangered Species of Animals
and Plants Ordinance (Cap 586);
·
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);
·
PRC Regulations and Guidelines.
8.3
Summary of
Baseline Conditions
The site for the proposed GRS reclamation is adjacent
to the existing BPPS near the northern reaches of the
The marine ecological habitats in the immediate vicinity
of the proposed GRS reclamation site of BPPS and pipeline route in Black Point
have undergone anthropogenic disturbance through marine traffic via the
Comprehensive literature review was conducted to
examine the major habitats and species in the marine environment surrounding
the Project Site and to identify potential information gaps for the baseline
conditions of the habitats.
Focussed field surveys and additional comprehensive data review were
conducted to fill these information gaps.
The findings of the literature review, field surveys, data review and an
evaluation of the ecological importance of marine resources within the Study
Area are summarised in the following section. The details are presented in full in Annex
8A.
The key finding of the literature review was the
recorded presence of Indo-Pacific humpback dolphin Sousa chinensis in the waters of the
Study Area. The review highlighted that the waters
around Black Point did not report large numbers of sightings and are used as
marginal habitat by dolphins in
Field surveys were conducted in habitats within and
surrounding the reclamation site and pipeline route in the dry and wet seasons
of 2009 (Table 8.1), while the
additional data review for marine mammals utilised data from January 2005 to
June 2009. Details of the baseline
surveys are presented in Annex 8A.
Table 8.1 Marine
Ecology Baseline Surveys
|
Survey Type |
Methodology |
Season & Date |
|
Intertidal
Assemblages at BPPS |
Qualitative spot
checks and quantitative surveys of three 100 m belt transects (at high, mid
and low intertidal zones) at artificial seawall, covering both wet and dry
seasons |
Dry Season: 25
Mar 2009 Wet Season: 23
Jun 2009 |
|
Subtidal
Benthic Assemblages |
Quantitative
grab sampling surveys at four sites (six stations at each site). Sites surveyed represented the
reclamation site and pipeline alignment |
Wet Season: 10
Jun 2009 |
|
Subtidal Hard
Bottom Assemblages (Coral) |
Spot dives
within Study Area |
30 Sept and 2
Oct 2009 |
Intertidal Hard Bottom Assemblages
Seasonal quantitative transect surveys were conducted
on the artificial seawall of the Black Point Power Station. Rocky shore species at all survey transects
were common and widespread and no species of note were recorded.
Subtidal Soft Bottom Assemblages – Benthos
Systematic grab sampling was conducted within and in
proximity to the footprint of the reclamation site and pipeline alignment in
the wet season 2009. Infaunal assemblages at the surveyed sites were dominated
by polychaete worms, and the species recorded are
common and widespread with no particular conservation concern. In comparison with the
Subtidal Hard Bottom Assemblages – Coral
Spot dive surveys were conducted on the artificial
seawall of the Black Point Power Station, within the proposed reclamation site
and on hard substrate identified along the proposed pipeline route. No corals (hard, soft, gorgonians or
whips) were recorded during the spot dives within survey area and thus the
ecological importance of these habitats is considered as low.
Indo-Pacific Humpback Dolphins
A comprehensive data review was undertaken by the
Hong Kong Cetacean Research Project (HKCRP) using the long-term dolphin
monitoring data collected from
Findings of the data review showed that humpback
dolphins have been sighted along and adjacent to the proposed gas pipeline
alignment, and also near the proposed reclamation site at BPPS. Dolphin densities (DPSE values) were
considered as low to moderate for the proposed reclamation site and along the
pipeline alignment.
8.3.2
Ecological Importance
The ecological importance of the habitats was
determined through reference to the following:
·
Literature
review;
·
Findings
of the field surveys and additional data review;
·
Comparison
with other areas in
·
Annexes 8 and 16 of
the EIAO-TM.
None of the marine ecological resources and habitats
in the proposed Project Site is considered as of high ecological value. Key findings and outcomes of the
evaluation of ecological importance are summarised in Table 8.2 and presented in full in Annex 8A.
Table 8.2 Ecological
Importance of the Marine Habitats
|
Habitat |
Ecological Importance
within Project Area |
|
Intertidal Hard Bottom Habitat |
Low |
|
Subtidal Soft Bottom Habitats |
Low |
|
Subtidal Hard Bottom Habitat |
Low |
|
Marine Waters |
Low to Moderate for the Indo-Pacific humpback
dolphin Sousa chinensis |
8.3.3
Marine Ecological Sensitive Receivers
Based on the review of available information on
existing conditions in the Study Area and its immediate vicinity, marine
ecological sensitive receivers have been identified in accordance with the EIAO-TM criteria, and are consistent
with the ones identified in the Water
Quality Impact Assessment (Section 6). These sensitive receivers and their
distance from the project facilities are listed in Table 8.3 and presented in Figure 6.3.
Table 8.3 Approximate
Shortest Distance to Marine Ecological Sensitive Receivers (SRs)
around the Proposed GRS Reclamation and Submarine Pipelines from Black Point
|
Sensitive
Receiver |
Name |
Shortest Distance from SR to Proposed Project
Facilities |
|
Seagrass Beds |
Ha Pak Nai |
3.2 km |
|
Pak Nai |
4.5 km |
|
|
Marine
Parks |
Designated Sha Chau and Lung Kwu Chau |
3 km |
|
Intertidal
Mudflats |
Ha Pak Nai |
2.5 km |
|
Mangroves |
Sheung Pak Nai |
5 km |
|
Ngau Hom Shek |
6 km |
|
|
Horseshoe
Crab Nursery Grounds |
Ha Pak Nai |
3 km |
|
Pak Nai |
4.3 km |
|
|
|
Sheung Pak Nai |
5 km |
|
|
Ngau Hom Shek |
6 km |
Findings of the literature review suggest that the
natural shore at the Black Point headland, which is about 1 km from the Project
Site, is comprised of common and widespread rocky shore species with no species
of conservation interest (see Annexes 8A and 8B). In
comparison to records of other similar habitats in
A desktop literature review and supporting field
surveys and data review (summarised in Section
8.3 and presented in detail in Annex 8A) were conducted in
order to establish the ecological profile of the area within and surrounding
the Project. The importance of
potentially-impacted ecological resources identified within the Study Area was
evaluated using the methodology defined in the EIAO-TM. Potential
impacts to these resources due to the construction and operation of the GRSs and submarine gas pipelines were assessed (following
the EIAO-TM Annex 16 guidelines) and
the impacts evaluated (based on the criteria in EIAO-TM Annex 8).
Findings of water quality modelling (Section
6) are used, where appropriate, to assess potential impacts on the
identified marine ecological resources.
It is noted that the construction of the first
pipeline, and the construction of the second pipeline and the reclamation, will
involve two phases. First Phase construction
(Pipeline 1 and co-located GRS) is expected to commence in 2011 while Second
Phase construction (Pipeline 2, reclamation and associated GRS) could commence
within 24 months following commissioning of the First Phase. However in order to evaluate worse-case
project-specific impacts, the assessment presented in the following sections
has taken into consideration the overall impacts of the construction of both
pipelines and the reclamation.
Potential impacts to marine ecological resources, and
marine mammals, are discussed in Sections
8.5 and 8.6 respectively.
8.5
Potential Impacts
& Impact Assessment on Marine Ecological Resources
8.5.1
Construction Phase
Impacts associated with the proposed Project are
divided into those occurring during:
·
Submarine gas pipeline installation: the installation works will involve
dredging, jetting and pipe-laying works.
·
Dredging and reclamation for the GRS: along the line of the proposed seawalls the
existing marine sediments will be dredged to provide suitable foundations. After completion of the seawalls, the
reclamation area will be filled using sand and / or public fill. The proposed reclamation works are of
relatively small scale (about 0.5 ha).
Potential impacts to marine ecological resources and
sensitive receivers arising from these construction activities may be divided
into those due to direct disturbance to the habitat and those due to
perturbations to key water quality parameters. These potential impacts are summarised
in Table 8.4 and discussed in further
detail in the following sections.
Table 8.4 Summary
of Potential Construction Phase Impacts on Marine Ecological Resources
|
Nature of Impact |
Marine Habitat Affected |
Potential Impact |
|
Dredging and Reclamation of the GRSs
at BPPS |
||
|
Habitat Loss |
Subtidal Soft Bottom Habitat at the proposed reclamation
site |
Permanent loss of approximately 0.5 ha of seabed
with minor temporary loss at the seawall works footprint (about 0.85 ha) |
|
Subtidal and |
Permanent loss of approximately 100 m of existing subtidal and intertidal artificial shores, replaced by 200
m of new artificial shore |
|
|
Short-term Changes in Water Quality |
Subtidal Soft Bottom Habitat |
Potential burial of benthic organisms during
dredging |
|
Subtidal and Intertidal Artificial/ Natural Shores |
Potential water quality impacts on subtidal and intertidal organisms |
|
|
Submarine Gas Pipeline Installation |
||
|
Temporary Habitat Loss |
Subtidal Soft Bottom Habitat along the proposed pipeline
corridor |
Temporary loss of about 15.6 ha of seabed along the approximately
5 km route of the two pipelines (see Table
3.2 for calculation) |
|
Short-term Changes in Water Quality |
Subtidal Soft Bottom Habitat |
Potential deposition of sediment onto the seabed
affecting benthic organisms |
|
Subtidal and Intertidal Artificial/ Natural Shores |
Potential water quality impacts on subtidal and intertidal organisms |
|
As discussed in Section
6.7, only minor water quality impacts will be expected due to discharges
from hydrotesting and works vessels during
construction and, therefore, impacts on marine ecology including marine mammals
are not considered as a concern.
Permanent Habitat Loss
None of the marine ecological sensitive receivers
presented in Table 8.3 is found within
the Project Site and thus direct, permanent habitat disturbance will not occur
at these sensitive receivers.
Subtidal Soft Bottom Habitats at the Reclamation
Site
Within the reclamation footprint at BPPS, impacts will
be due to the burial of organisms during filling, or removal of organisms
during dredging. Dredging would
also directly affect the margins of seabed at the base of existing seawalls. These impacts are an unavoidable
consequence of the Project and would occur during dredging and backfilling
operations associated with the reclamation works for the GRS.
It is, therefore, important to determine whether the
works areas contain unique or otherwise noteworthy benthic assemblages which
will be lost. Findings from a
literature review and field surveys indicate that the benthic assemblages in
the vicinity of the reclamation were dominated by polychaetes
and characterised by similar species diversity (for both seasons) and dry
season biomass as found elsewhere in
The scale of the reclamation and extent of works area
have been reduced as far as practicable through modifications to the
engineering layout. Although the
proposed reclamation and dredging will result in permanent loss of about 0.5 ha
of subtidal soft benthic habitats due to the
reclamation, the severity of the impact is anticipated to be acceptable in
terms of loss of benthic assemblages, as the seabed areas to be reclaimed and
dredged are of low ecological value and support benthic species which are
common in Hong Kong waters.
Subtidal & Intertidal Artificial Shores at the
Reclamation Site
The proposed reclamation will result in the loss of subtidal and intertidal hard bottom assemblages along the ~
100 m existing sloping artificial shores, via burial of organisms.
Coral communities were not found along this stretch
of shoreline, and results from field surveys and literature review indicated
that the intertidal assemblages recorded on the artificial shores are typical
artificial shore species in
Given that a relatively short stretch of artificial
shores will be permanently lost (~ 100 m), the severity of the impact is
anticipated to be acceptable in terms of the loss of low ecological value
assemblages. This 100 m stretch of
seawall will be replaced by about 200 m of new artificial vertical seawalls
surrounding the GRS reclamation. It
is anticipated that assemblages of intertidal and subtidal
organisms will, over time, settle on and recolonise
the newly constructed seawalls, as environmental conditions of that area would
be similar to existing conditions that have allowed the growth of these
organisms.
Temporary Habitat Loss
None of the marine ecological sensitive receivers
presented in Table 8.3 is found
within the Project Site and thus direct, temporary habitat disturbance will not
occur at these sensitive receivers.
Subtidal Soft Bottom Habitats along the Pipeline
Corridor and at the Reclamation Seawall Trenches
No long-term direct impacts are expected to occur due
to the installation of the gas pipelines.
Short-term impacts on subtidal soft bottom
assemblages are predicted to occur as a result of the dredging/ jetting
operations associated with the burial of the pipelines.
The width of pipeline trenches has been reduced where
practical. The width of the trenches
is approximately 3 - 35 m wide, and about 15.6 ha of seabed is expected to be
temporarily affected for the installation of two pipelines. The pipelines (approximately 32” – 42 “
in diameter) will be laid in soft seabed habitats that are regarded to be of
generally low ecological value.
Once the installation operations have ceased, assemblages in the
affected areas are expected to return due to the recolonisation
of the seabed by benthic fauna.
Following installation, the pipelines will be
protected by rock armour. Rock
armour is necessary to achieve adequate protection against anchor drop and drag
for the gas pipeline. The expected
overall duration of rock armour placement on the gas pipelines is around four
months.
Natural backfilling of marine sediment over the rock
armour will occur and is expected to be quickly recolonised
by benthic organisms. Water quality
impacts from these works are not expected as the fines content of the armour
rock material is low.
Short-term impacts on subtidal
soft bottom assemblages are predicted to occur as a result of the dredging
operations at the seawall trenches of the reclamation site. The benthic assemblages within this
footprint are considered to be of low ecological value.
Overall, given the temporary nature of the potential
impacts and the low ecological value of the associated benthic assemblages, the
severity of the impact is anticipated to be acceptable and adverse impacts are
not predicted.
Short-term Changes in Water Quality
All sensitive receivers presented in Table 8.3 are considered to be of
sufficient distance from the Project Site and marine works areas and are
unlikely to be affected indirectly by the construction of the Project. This is supported by results of the
water quality modelling which suggest that unacceptable water quality impacts
are not predicted at these sensitive receivers (see Section 6.7).
Suspended Solids (SS)
Dredging/ Sand-filling of
the Reclamation
Dredging of sediments within the reclamation site and
along the line of the seawalls, and filling of the seawall trenches using sand
and/ or public fill, will generate suspended solids (SS) within the water
column and may result in increased sediment deposition in subtidal
and intertidal assemblages in close proximity of the works areas. Computational modelling has been
undertaken to analyse suspended sediment dispersion from dredging works (Section 6.7.1). Sediment may be deposited on the seabed
and other subtidal hard substrates outside the
reclamation sites during dredging and backfilling (through dispersion of
sediment plumes) and post-placement (through erosion and wave-induced resuspension).
With reference to the water quality modelling results
(Section 6.7.1), elevations in SS
would be localised and confined to the works area. The area affected is expected to be
small as sediment will be deposited within a short distance of the dredging and
filling works (at a distance of ~ 1 km).
It should be noted that backfilling for the reclamation area will take
place behind completed seawalls which will prevent to a large degree the
dispersion of SS. Therefore
elevations in SS are not predicted to affect the marine ecological sensitive
receivers at levels of concern (as defined by the WQO and tolerance criterion)
given their separation distance from the reclamation works area. Consequently, unacceptable impacts on
marine ecological sensitive receivers are not expected.
Whilst subtidal and
intertidal assemblages immediately outside of the reclamation site and dredged areas
are predicted to experience elevations in SS levels, these are expected to
occur temporarily. These
assemblages in proximity to the proposed reclamation are considered to be of
low ecological value (Section 8.3). As the areas affected are often disturbed
by demersal trawling and SS laden discharges from the
Dredging of Pipeline
Trenches
Dredging of sediments along the proposed pipeline
corridors is expected to generate SS within the water column and may result in
increased sediment deposition on the seabed in close proximity to the works
areas. Computational modelling has
been undertaken to analyse suspended sediment dispersion from the dredging
works (Section 6.7.1).
Impacts to subtidal benthic
assemblages immediately outside of the pipeline trenches are expected to occur
temporarily as the modelling results indicate that the pipeline dredging works
would only result in short-term, localised elevations of SS in each particular
location. The habitats affected
along the route are expected to be small in size and generally confined to the
works corridor since suspended sediments entering the water column will not be
subject to a high degree of lateral dispersion (Section 6.7.1).
Subtidal assemblages in proximity to the proposed pipeline
alignment are considered to be of low ecological value (Section 8.3). As the
areas affected are often disturbed by demersal
trawling and SS laden discharges from the
As for potential impacts to the subtidal
and intertidal assemblages from the dredging works, they are predicted to occur
immediately outside of the dredged areas near the landing point only and are
expected to occur temporarily. Also
elevations in SS are not predicted to affect the marine ecological sensitive
receivers at levels of concern (as defined by the WQO and tolerance criterion)
given their separation distance from the works area and hence unacceptable impacts
on these sensitive receivers are not expected (see Section 6.7.1).
Jetting of Pipeline Trenches
As discussed in Section
3 of this EIA Report, jetting would be adopted as the chosen method for
installing the gas pipelines along certain sections of the alignment in both
Jetting works will generate SS within the water
column and result in the deposition of sediment onto the seabed affecting
benthic organisms adjacent to the utility trenches. With reference to the water quality
modelling results (Section 6.7.1),
suspended sediments entering the water column due to jetting are predominantly
confined to the bed layer and are not subject to a high degree of lateral
dispersion. Impacts to the benthic
organisms would be temporary and localised in extent. The area affected is expected to be
small as sediment will be deposited within a short distance of the jetting
works (at a distance of ~ 1 km).
For jetting works in
Whilst subtidal and
intertidal assemblages in the vicinity of the pipeline trenches are predicted
to experience elevations in SS levels as a result of jetting in
At this stage it has been assumed that the
installation of submarine gas pipelines in PRC waters will be conducted largely
using jetting. This assumption is
based on the feasibility study for the Mainland China segment of the pipeline
route. For the purpose of this
assessment potential impacts of jetting in PRC on marine ecological resources
and sensitive receivers in
With reference to the water quality modelling
results, jetting works in PRC waters are not predicted to result in SS
elevations that would affect the marine ecological sensitive receivers at
levels of concern (as defined by the WQO and tolerance criterion). Consequently, unacceptable impacts on
marine ecological sensitive receivers are not expected.
Dissolved Oxygen (DO)
The relationships between SS and dissolved oxygen
(DO) are complex, with increased SS in the water column combining with a number
of other factors to reduce DO concentrations in the water column. Elevated SS (and turbidity) reduces
light penetration, lowers the rate of photosynthesis by phytoplankton (primary
productivity) and thus lowers the rate of oxygen production in the water
column. This has a particularly
adverse effect on the eggs and larvae of fish, as at these stages of
development, high levels of oxygen in the water are required for growth due to
their high metabolic rate. DO
depletions are most likely to affect sessile organisms as they cannot move away
from areas where DO is low (unlike mobile species such as fish).
With reference to the water quality modelling results
(Section 6.7.3), the dredging/
jetting would only generate temporary and localised low level SS elevation and
not significant depletions of DO.
Depletions of DO as a result of the dredging/ jetting activities have
been predicted to be undetectable and compliant with the relevant WQOs. It is
thus expected that unacceptable impacts to the marine ecological assemblages
and sensitive receivers present in the vicinity of the reclamation site and
pipeline alignment are not expected to occur.
Nutrients
High levels of nutrients (total inorganic nitrogen -
TIN and ammonia) released from dredged sediments to seawater may potentially
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 water quality modelling results (Section 6.7.4) have indicated that
dredging would generate low level SS elevation in a localised area close to the
works. Consequently nutrient levels
are not expected to increase appreciably from background conditions during the
dredging operations. Algal blooms
and unacceptable impacts to the sensitive receivers and marine ecological
assemblages present in the vicinity of the reclamation area and pipeline route
are not expected to arise due to the works.
8.5.2
Operation Phase
No impacts are expected to occur during the operation
of the submarine pipelines. The
pipelines are unlikely to be damaged as they will be buried to approximately 1
m - 3 m within the seabed. The
pipelines are designed to be maintenance free but should it require inspection
this will be done using a remotely operated intelligent pipe inspection gauge
(PIG). This type of inspection
device will be within the pipelines.
Consequently, there will be no need to disturb the seabed during
inspection and therefore marine ecology will not be affected.
Potential impacts associated with the operation phase
are thus expected to be limited to potential changes to hydrodynamic regime due
to the physical presence of the GRS reclamation. Secondary impacts on water quality may
also arise from the reclamation in terms of limited dispersion of cooling water
discharged from the BPPS.
Hydrodynamic Regime
The reclamation for the GRSs
will create a minor change in the shape of the existing coastline. The effects of changes in coastal
configuration on the current velocities have been assessed (Section 6.8). Owing to the small scale of the
reclamation, no significant changes in the hydrodynamic regime and flushing
capacity around the BPPS area were predicted. Significant sedimentation is also not
predicted to occur along the new seawalls.
Consequently, no operation phase impacts on marine ecological resources
due to changes in the hydrodynamic regime are expected.
Secondary Water Quality Impacts
Cooling water will be discharged at the seawater
outfall of the BPPS and the maximum allowable increase in temperature is 10 ºC
above ambient. Results of the water
quality modelling have shown that in the presence of the GRS reclamation,
temperature of the cooling water is expected to dissipate rapidly upon
discharge. Whilst no non-compliance
with the WQO is predicted to occur at the marine ecological sensitive receivers
in either the dry or wet season (Section
6.8.4), the predicted temperature differences are confined to the discharge
location with a maximum of 2 °C difference from existing condition for a
distance of < 1 km from the point of discharge. This is considered as a potential
secondary impact on water quality as a result of this Project.
The temperature change is predicted to be confined to
the surface layer with reduced impact to the bottom layer. Impacts are thus expected to mainly
occur in the surface layer of the water column or in the shallower water of the
intertidal zone. Impacts on the
seabed will be less severe as temperature change is lower than the surface.
The potential impacts of this thermal discharge are
principally related to the physiological effects on marine biota in a zone of
elevated temperature near the point of discharge. Effects of ambient temperature elevation
will depend largely on an organism’s tolerance towards thermal stress and water
movement. Marine ecological
resources of the BPPS area are expected to be of low sensitivity as these
tropical species are expected to be able to tolerate slight elevations in
thermal stress. Thermal impacts to
these organisms are hence expected to be of low severity and hence unacceptable
impacts are not anticipated. No
effects on ecological carrying capacity of the assemblages are expected since
it is considered unlikely that population size of subtidal/
intertidal assemblages would be affected by the predicted temperature
difference.
8.6
Potential Impacts
& Impact Assessment on Marine Mammals
In this Section,
the potential for impacts associated with various marine works and activities involved
in the proposed Project are examined in detail to provide an assessment of the
significance of potential effects on the Indo- Pacific humpback dolphin Sousa chinensis. The significance of a potential impact
from works or activities on marine mammals can be determined by examining the
consequences of the impact on the affected animals. This is related to the source, nature,
magnitude and duration of the impact, the level of exposure to the impact in
terms of the number (and age classes) of affected animals and their response to
an impact.
The consequences of an impact on these marine mammals
have the potential to range from behavioural changes of individual animals
through to population-level effects ([1])
([2])
([3]).
The potential consequences of impacts on marine mammals are as follows:
·
Behavioural changes: Affected individual animals may change
travelling speed, dive times, avoid areas, change travel direction to evade
vessels, change vocalisation due to acoustic interference, reduce resting, socialising
and mother-calf nursing. Provided
that disturbances leading to behavioural changes are temporary, localised and
outside areas of ecological importance to marine mammals, disturbances causing
behavioural changes would generally not be considered significant (i.e. effects would be of short duration,
normal activities will resume with no appreciable effect on fitness or vital
rates).
·
Life function immediately affected: Avoidance of affected areas may diminish
individual animals’ feeding activity.
Loss of a marine area to reclamation will permanently eliminate a
habitat area. Similarly,
disturbance/ loss of prey resources due to water quality impacts may diminish
available feeding opportunities in the vicinity of works. Interference with echolocation through
underwater noise could also affect feeding. Provided that disturbances are temporary
and localised, or permanent losses of habitat represent a small portion of
available habitat and are outside areas of ecological importance to marine
mammals, impacts would generally not be considered to have a significant effect
on marine mammals (i.e. effect would be short term and therefore have no
appreciable effect on fitness or vital rates).
·
Fitness and Vital Rate Impacts: If works cause widespread and prolonged
adverse impacts, with limited or no alternative habitat available for animals
to use, fitness and vital rates will be affected, including growth rates,
reproduction rates and survival rates (life-stage specific). In the same way, any works or activity
likely to result in injury or mortality of marine mammals would obviously
affect survival rates. Activities
causing impacts on fitness and vital rates would be considered significant
(i.e. if effects are long-term or inescapable, they will diminish the health
and survival of individuals).
·
Population effects: Impacts on the fitness and survival of
individuals have the potential to, for instance, affect population growth rates
and population structure. Impacts
resulting in population effects would be considered significant (i.e. if
effects are long term and detrimental to the population as a whole).
8.6.1
Construction Phase
As discussed previously, works for the proposed
Project will primarily involve the dredging and reclamation for the GRS and submarine
gas pipeline installation.
Potential impacts associated with these construction activities are
summarised in Table 8.5. Effects on Indo-Pacific humpback
dolphins have been assessed and are discussed in detail below.
Table 8.5 Summary
of Potential Construction Phase Impacts on Marine Mammals
|
Nature of Impact |
Potential Impact |
|
Permanent Habitat Loss |
Permanent loss of approximately 0.5 ha of marine waters
as potential marine mammal habitat due to the reclamation site |
|
Potential Disturbance from Submarine Pipeline
Installation Works |
Potential disturbance from submarine gas pipeline
installation operations |
|
Potential Disturbance from Marine Works Vessels |
Increased marine traffic and elevations in
underwater sound level due to marine construction activities |
|
Short-term Changes in Water Quality |
Potential water quality impacts associated with
marine construction activities |
|
Contaminant Release & Bioaccumulation |
Potential bioaccumulation of contaminants released
from dredging/ jetting operations |
Permanent Habitat Loss at the Reclamation Site
The proposed reclamation of about 0.5 ha at the BPPS
for the GRS would result in a permanent loss of sea area and hence the
permanent loss of nearshore marine mammal
habitat. The physical loss of
habitat during and after reclamation works may potentially affect some
individuals of Indo-Pacific humpback dolphin, Sousa chinensis, which utilise Black
Point waters as a part of their home range.
Based on findings of the literature review and
comprehensive data review (Sections
8A.3.7 and 8A.5 of Annex
8A), waters off Black Point are at the periphery of most dolphins’
ranges, and only 10 of the 99 identified dolphins have consistently utilized
the marine waters in this area (at 50% UD ranges). The nearshore
waters under the footprint of the proposed reclamation, which is adjacent to
artificial shoreline, are expected to be an area of low dolphin density and
abundance and have been evaluated to be of low to moderate ecological
importance.
It is also considered that the area of nearshore waters to be lost is very small and represents
only a very small portion of available habitat for this species. Photo-identification studies have shown
Indo-Pacific humpback dolphins have extensive home ranges often extending over
100 km2 and may forage and feed throughout ([4]) ([5]).
In the context of the size of the home ranges which may encompass
extensive areas across western
It should be noted that the habitat loss is not
likely to significantly impact the fitness or vital rates of affected
individual animals that currently utilise these waters. The permanent loss of marine habitat due
to reclamation is not predicted to adversely impact the fisheries resources
that would be available in the waters surrounding the reclaimed area (the fish
and marine invertebrates in the marine habitat serve as marine mammal’s food
prey), since existing fisheries production from the affected shoreline area is
very low.
Given that the potential impacts constitute a
permanent, irreversible loss of only a very small area of low-to-moderate
ecological importance marine mammal habitat with little, if any, secondary
impacts, the severity of the impact is anticipated to be acceptable and adverse
impacts are unlikely to be significant.
Potential Disturbance from Submarine Pipeline Installation Works
Direct impacts due to gas pipeline installation on
Indo-Pacific humpback dolphin habitats in
The proposed submarine gas pipelines will be
installed by a combination of grab dredging and jetting (consideration of
pipeline installation methods is presented in Section 2.3.4).
Dredging and jetting have been used extensively in
Marine mammal researchers have observed humpback
dolphins in Hong Kong around dredging activities a number of times, and there
is no evidence to suggest that areas in which dredging occurs (such as the
Contaminated Mud Pit areas at East of Sha Chau and around Lung Kwu Chau) have been permanently abandoned by dolphins, although
short-term decline in dolphin abundance may occur. The observations by the researchers
appear to suggest that the dolphins have short-term avoidance of the immediate
works areas of dredging / jetting activities (on the order of movements of
several hundreds or thousands of metres).
In
Table 8.6 Summary
of Previous Pipeline Projects in Areas of High Ecological Importance of
|
Pipeline Project |
Installation Method |
Date |
Length |
Passes Through/ Close to Sensitive Habitat |
||||
|
Marine Reserve |
|
Indo-Pacific Humpback Dolphin |
Finless Porpoise |
Corals |
||||
|
Towngas Shenzhen – Tai |
Dredging &
Jetting |
2005 |
~ 45 km |
|
Yes |
|
|
Yes |
|
Towngas Tai Lam – Lantau |
Dredging |
1996 |
~ 5 km |
|
|
Yes |
|
|
|
HEC Shenzhen – Lamma |
Dredging &
Jetting |
2005 |
~ 90 km |
Yes |
Yes |
|
Yes |
Yes |
|
AAHK PAFF – Sha Chau |
Dredging |
2006/ 2007 |
~ 8 km |
|
Yes |
Yes |
|
|
|
AAHK Sha Chau – Airport |
Dredging |
1996 |
~ 10 km |
|
Yes |
Yes |
|
|
|
CLP Yacheng –
Black Point |
Dredging |
1995 |
~ 75 km |
|
Yes |
Yes |
Yes |
|
The nature of works for the proposed pipelines for
this Project is similar to these previously-approved projects ([6]).
It is envisaged that the severity of potential impacts associated with
this Project is considerably lower than the above previously-approved pipeline
projects, given the shorter length of pipelines for this Project and the low to
moderate ecological importance of
There is a consensus among the leading local marine
mammal specialists that reducing the duration of marine works and the area of
marine concurrent anthropogenic activity is a highly-effective approach to
reduce impacts on marine mammals.
It is, therefore, important to reduce the total duration of marine works
to limit potential short-term behavioural disturbance and / or displacement of
dolphins.
In order to reduce the duration of works in different
works area, the following approach has been adopted:
·
Adopt
optimal pipeline installation methods: jetting is a comparatively faster way to
construct a pipeline trench than grab dredging, and is adopted for the majority
of the pipeline alignment (i.e. along Sections 2 and 4 with a total length of
about 3.15 km) to shorten the works programme ([7])
([8])
([9]).
·
Operate
a number of dredgers concurrently (see Section
6.7): it is assumed that for the installation of each pipeline, two
dredgers will be used.
At present, pipeline trenching and installation works
have been scheduled to take place within a period of about five months for each
construction phase. With a shorter
works programme, it is expected that marine mammals that have avoided the
vicinity of the works areas can return to the area sooner.
The majority of the pipeline trenches will be
excavated by dredgers/ jetting machine operating 12 hours per day. This scheduling measure has been adopted
as part of a marine mammal exclusion zone that will be implemented during
dredging/ jetting works along the gas pipeline route. Such exclusion zones are most
effectively enforced during daylight hours and hence dredging/ jetting works
along the pipeline route have been scheduled to take place for 12 hours during
daylight.
For safety reasons, dredgers will operate 24 hours on
the pipeline section that crosses the
The submarine pipelines will be laid from barges into
the trenches on the seabed, and therefore will not cause an underwater
obstruction to marine mammals. It
should also be noted that the duration of the various activities is short as
pipe-laying would be expected to occur for only one month.
Similarly, vessels involved in armour protection
placement will proceed along the pipelines in a specific area and their
activities are not expected to impact marine mammals. The placement of rock armour is not
expected to cause impacts to water quality or marine ecological resources, as
the vessel will comply with the speed limitations and the backfill material
will have a low fines content. As
the armour rocks will be placed directly on top of the pipe which is located at
the bottom of the dredged trench, it is not expected to pose a collision risk/
obstruction to dolphins.
It should be noted that many similar pipelines have
been installed or permitted in Hong Kong with similar post-construction
protection using armour rock, including HEC Shenzhen to Lamma
pipeline, AAHK PAFF pipeline and Towngas Shenzhen to
Tai Po pipeline, in which some of the pipeline sections pass through
Indo-Pacific humpback dolphin habitats, i.e. the Sha Chau Lung Kwu Chau
Marine Park. Consequently,
placement of rock armour on the gas pipelines is not expected to cause
significant impacts to marine mammals.
Potential Disturbance from Marine Works Vessels
Increased Marine Traffic
Construction of the proposed Project has the
potential to result in an increase in marine traffic associated with the
dredging/ jetting and reclamation works, which may affect Indo-Pacific humpback
dolphin. There are two key ways
increased vessel traffic has the potential to impact marine mammals. Firstly, vessel movements may
potentially increase physical risks to dolphins. Secondly, the physical presence of works
vessels due to construction may cause short-term avoidance of the area where
works vessels are operating.
In
The effect of the physical presence of
work vessels and other vessels on dolphins would be limited to temporary
behavioural disturbance of a number of animals, if and when encounters with
vessels occur. It would be expected
that these animals may avoid the vicinity of the works areas whilst works
vessels are in operation. These
disturbances would not be expected to have a biologically-significant impact on
the affected animals. As discussed
previously photo-identification of individual dolphins has shown these animals
have extensive home ranges often of more than 100 km2 and perform
their main functions (feeding, socialising, breeding) throughout their home
ranges. Therefore any works areas
avoided would constitute a very small portion of the waters they inhabit.
This assumption that the presence of work vessels
would not adversely impact marine mammals is consistent with other EIA and
environmental monitoring studies in
On the basis of the above, whole-scale changes to
dolphin’s behaviour are highly improbable during the pipeline installation
works. Mothers and calves are in
constant communication with each other, and it is extremely unlikely that there
will be a separation between the two arising from the proposed works. Other individual (including life
function [feeding, socialising and breeding] and fitness/ vital rate impacts)
and population effects are also not anticipated due to the short-term nature of
potential impacts.
Given that waters off Black Point are at the
periphery of most dolphins’ ranges and the inshore waters surrounding the
proposed pipelines are expected to be an area of low dolphin density and
abundance (Sections 8A.3.7 and 8A.5), unacceptable adverse impacts of
increased marine traffic on Indo-Pacific humpback dolphin are not anticipated.
Underwater Sound
Marine construction activities can result in a
short-term increase in underwater sound from marine vessels, which may
potentially affect Indo-Pacific humpback dolphin.
Small cetaceans are acoustically sensitive at certain
frequencies, and sound is important to their behavioural activities in terms of
intraspecific communication. Most dolphins can hear within the range
of 1 to 150 kHz, though the peak for a variety of species is between 8 and 90
kHz ([15]).
Indo-Pacific humpback dolphins have been reported to use five categories
of vocalisation associated with different activities ([16]).
These animals use high-frequency broad-band clicks in the range of 8 kHz
to > 22 kHz during foraging.
During both foraging and socialising, burst pulse sounds of barks and
quacks in the frequency range of 0.6 kHz to > 22 kHz are used. Low-frequency, narrow-band grunt
vocalisations in the range of 0.5 kHz to 2.6 kHz are also used during
socialising activity. Dolphins also
have whistle vocalisations in a wide frequency from 0.9 kHz to 22 kHz ([17]).
Dredging/ jetting and large vessel traffic generally
results in low-frequency noise, typically in the range of 0.02 to 1 kHz, which
is below the peak range of 8 - 90 kHz reported for dolphins. For this reason, underwater sound
generated by dredging/ jetting, pipe-laying operations and armour rock
placement is not expected to acoustically interfere significantly with
dolphins. Unacceptable adverse
impacts of increased marine traffic on Indo-Pacific humpback dolphin are not
anticipated.
Potential Water Quality Impacts
High SS levels do not appear to have a direct impact on
dolphins since these animals are air breathing and therefore SS in the water
column have no effect on their respiratory surfaces. Also Indo-Pacific humpback dolphins have
evolved to inhabit areas near river mouths and are therefore well-adapted for
hunting in turbid waters, owing to their use of echolocation, in addition to
visual information.
With reference to the water quality modelling results
(Section 6.7), fisheries resources
are not predicted to be adversely affected, as the SS elevations are localized
to the works areas. In addition,
the level of fisheries production from the works areas is known to be very low,
suggesting that these areas are unlikely to be important feeding grounds for
dolphins. The consequences of this
are that impacts to marine mammals through loss of localised feeding habitat
(fisheries resources) are not predicted to occur. It is thus expected that unacceptable
impacts to marine mammals arising from elevated SS levels will not occur. It should be noted that the Indo-Pacific
humpback dolphin and their prey species are naturally exposed to high levels of
suspended solids in the Pearl River Estuary.
In terms of the potential impacts of jetting on
marine mammal habitat inside the Sha Chau and Lung Kwu Chau Marine Park, results of the water quality modelling
show that SS elevations as a result of jetting operations for pipeline
installation in both the Hong Kong and PRC waters are predicted to be compliant
with the water quality objectives for both seasons at the northern boundary of
the Marine Park. These elevations
will be short-term, since the jetting operations will only last for a short
period of time (about 1 month).
With the implementation of effective mitigation
measures, such as the optimisation of jetting rates and water quality
monitoring, adverse impacts to marine mammal habitat within the Sha Chau and
Other EIA studies that have addressed impacts due to
elevated SS have drawn similar conclusions. For instance, a previously-approved EIA
study for the Permanent Aviation Fuel Facility (PAFF) (EIA-077/2002) ([18])
stated that: “There is no reason to assume that suspended
solid releases during pipeline construction will have an impact on dolphins”. Based on the assessment above and other
experience with the effects of suspended sediment on marine mammals, elevations
in SS associated with the marine works for this Project are not anticipated to
adversely impact dolphins.
Contaminant Release & Bioaccumulation
Another potential impact on marine mammals associated
with disturbance of bottom sediment during dredging or jetting is the potential
bioaccumulation of released contaminants.
The potential for release of contaminants from sediments when disturbed
has been reviewed in Section 6,
whereas, a comprehensive set of data on the quality of marine sediment is
provided in Section 7. Within these Sections it is concluded that some of the samples from the
reclamation and dredging/ jetting area contained levels of arsenic in excess of
the Lower Chemical Exceedance Level (LCEL), but below
the Upper Chemical Exceedance Level (UCEL), i.e.
Category M. It is highly likely
that the elevated levels of arsenic are derived from natural sources, e.g.
local geology, and are not present as a result of human activity ([19]).
In terms of the potential for impacts to occur to
marine mammals, a recent EM&A conducted on the continuation of the disposal
of highly-contaminated marine muds into dedicated mud
pits in the East of Sha Chau
area provides the best available information on bioaccumulation in marine
mammals in Hong Kong ([20]).
The assessment, which was based on bio-concentration factors and metal
concentrations in local fish and shellfish species, provided a comparison
between the risks to dolphins in areas where Category H marine sediments would
be dredged / disposed and those areas considered as being uncontaminated. Exposure pathways were assumed to be
consumption of contaminated food by dolphins that utilise waters in the
vicinity of the disposal ground, and in an area representative of background
conditions. The result of this detailed
risk assessment, which has been approved under the EIAO, concluded that elevated levels of arsenic in dredged marine
sediments do not pose an adverse risk to the Indo-Pacific humpback dolphins of
Concentrations of arsenic are low (compared to
concentrations in potential prey) in liver and kidney of most cetaceans,
including Indo-Pacific humpback dolphins.
Concentrations of arsenic in cetacean tissues usually are lower than
those in their prey ([21])
([22]).
Most of the arsenic in dolphin prey is in organic forms, particularly arsenobetaine, which is excreted unmetabolized
in the urine by most mammals and poses little threat to their livelihood.
The aforementioned assessment was based on
highly-contaminated mud, i.e. Category H.
The suite of analytes analysed for sediments
collected off Black Point has included a range of organic compounds, including
polychlorinated organic compound, specified in the relevant Technical Circular
(PNAP 252). All samples reported concentrations of
these substances below the reporting limits.
As the release of heavy metals and micro-organic
pollutants from the sediment when disturbed are expected to be of short
duration and at low levels, impacts on marine mammals due to bioaccumulation of
released contaminants from dredged sediments are not expected to occur.
8.6.2
Operation Phase
No impacts are expected to occur during the operation
of the submarine pipelines and the GRSs. In addition, unacceptable adverse impacts
of changes in hydrodynamic regime and secondary water quality impacts on marine
ecological resources are not anticipated (Section
6.8), hence potential secondary, indirect effects on Indo-Pacific
humpback dolphins are not predicted to occur.
In the event of leakage or loss of containment in a
submarine pipeline, given its low solubility in seawater, the natural gas will
bubble to the sea surface.
Unacceptable impacts on Indo-Pacific humpback dolphins are thus not
expected to occur.
Based upon the information presented in Sections 8.5 and 8.6, the significance of the marine ecological impacts associated
with the construction and operation of the proposed Project has been evaluated
in accordance with the EIAO-TM (Annex 8, Table 1). The outcomes of this evaluation are
summarised in Table 8.7.
This impact assessment indicates that no unacceptable
impacts to marine ecology are expected to occur. Furthermore, any predicted changes to
water quality, and hence surrounding marine habitats, are as a result of
applying specific mitigation measures likely to be localised to the works area,
to be of short duration, to be reversible and will occur within a limited and
transient mixing zone.
Permanent loss of subtidal
benthic assemblages under the reclamation footprint is anticipated; however,
these assemblages are regarded as of low ecological value and given the small
affected area, such loss is deemed acceptable. Although soft bottom habitat within the
pipeline dredging / jetting works areas will also 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 ([23]).
As such, it is anticipated that subtidal
assemblages influenced by dredging/ jetting will settle on and recolonise the seabed, returning it to the former
conditions.
The loss of intertidal and subtidal
assemblages on existing seawalls due to reclamation is expected to be
compensated through the provision of seawalls that provide adequate surfaces
for colonisation, once reclamation works have been completed (200 m of concrete
armour vertical seawalls). It is
anticipated that intertidal and subtidal assemblages
similar to those recorded in the field surveys, will settle on and recolonise the newly-constructed seawalls of the
reclamation.
With appropriate mitigation measures, no
biologically-significant impacts to marine mammals are expected to occur. The ~ 0.5 ha reclamation will cause
permanent and irreversible loss of marine mammal habitat of low to moderate
ecological importance. Dolphins
that have short-term avoidance of the immediate works areas of marine
construction activities are expected to return to the areas upon completion of
the works. Consequently,
whole-scale changes to dolphin’s behaviour are highly improbable during the
marine construction works, and other individual (including life function
[feeding, socialising and breeding] and fitness/ vital rate impacts) and
population effects are also not anticipated due to the short-term nature of
potential impacts.
Potential impacts to marine ecological resources
including the Indo-Pacific humpback dolphins, during operation of the facilities
are not predicted to occur.
Table 8.7 Significance
of Marine Ecological Impacts Associated with the Construction and Operation of the
Proposed Project Evaluated in accordance with EIAO-TM
|
Criteria |
Marine Ecological Resources |
Marine Mammals |
|
Habitat Quality |
Impacts are
predicted to occur only to the low ecological value coastal habitats
(intertidal and subtidal) and benthic habitats
within the reclamation site and along the pipeline alignment. The selection of the reclamation site
and pipeline alignment has avoided natural shores, habitats of high
ecological value and the Sha Chau
and |
The reclamation
works will affect about 0.5 ha of marine waters off Black Point where low
densities of Indo-Pacific humpback dolphins may occur. The submarine pipelines also pass
through areas of low densities of dolphins. These waters, which are marine mammal
habitat of low to moderate ecological importance, represent a very minor
portion of extensive home ranges of affected animals. The marine waters at this location
have been disturbed through reclamation in the past and are not considered to
represent key habitat for dolphins.
These waters are also affected by high volumes of vessel traffic. |
|
Species |
Based on
literature and field surveys, no organisms of ecological interest were
identified in proximity to Black Point.
Marine ecological sensitive receivers including horseshoe crab, seagrass and mangrove habitats were situated at distant
locations from the proposed works.
No impacts are expected to these sensitive receivers. |
Organisms of
ecological interest reported from the literature include the Indo-Pacific
humpback dolphin. Significant
impacts are not predicted to occur to this species, due to the marine works,
as water quality perturbations are predicted to be transient and compliant
with the WQO. Only indirect,
temporary disturbance to marine mammals due to disturbance and underwater
sound from increased marine traffic are expected. |
|
Size |
The total size
of the reclamation site is about 0.5 ha, including about 200 m of artificial
shore. Low ecological value
intertidal, subtidal hard surface and benthic assemblages
within the GRS footprint will be directly impacted. The low ecological value benthic
assemblages within the approximately 15.6 ha pipeline alignment (~ 5 km in
HKSAR waters, trench wide is 3 - 35 m wide) will be lost during dredging/
jetting but are expected to become re-established within a year (see Reversibility). Low ecological value artificial shore
assemblages are expected to recolonise. |
The reclamation
works will affect about 0.5 ha of marine waters where low levels of
Indo-Pacific humpback dolphin density have been reported. The marine waters have been disturbed
through reclamation in the past and are not considered to represent key
habitat for dolphins. The loss of
~ 0.5 ha of marine waters would be an unavoidable consequence of the proposed
Project, but the reclamation engineering required for the GRS has been
reduced in size to the greatest extent practicable. The total length of the gas pipelines
is about 5 km in HKSAR waters with the dredged trench width of 3 – 35 m. The nature and scale of pipeline
installation works is comparable to other pipeline projects in Hong Kong that
were deemed acceptable to construct in habitats of Indo-Pacific humpback
dolphins inside the Sha Chau
and |
|
Duration |
The reclamation
works are predicted to last for 6 - 7 months and the pipeline trenching and
installation works for approximately 5 months. Increases in SS levels in the vicinity
of sensitive receivers are expected to be low and temporary, and within
environmentally acceptable limits as defined by the relevant assessment
criteria. |
The reclamation
works are predicted to last for 6 - 7 months and the pipeline trenching and
installation works for approximately 5 months. Increases in SS levels in the vicinity
of sensitive receivers are expected to be low and temporary, and within environmentally-acceptable
limits as defined by the WQO. |
|
Reversibility |
Impacts to the
benthic assemblages inhabiting the soft bottom habitats along the pipeline
alignment 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 once it is reinstated. |
The only
permanent impacts at Black Point to dolphins are likely to be from the
reclamation works, which will affect about 0.5 ha of marine waters where
Indo-Pacific humpback dolphin have been recorded in low densities. |
|
Magnitude |
No unacceptable
impacts to the ecologically sensitive habitats have been predicted to occur. Operation phase impacts are not
expected to occur. |
No unacceptable
impacts to affected individual dolphins have been predicted to occur. Operation phase impacts are not
expected to occur. |
8.8.1
General
In accordance with the guidelines in the EIAO-TM on marine ecology impact
assessment, the general policy for mitigating impacts to marine ecological
resources, in order of priority, are:
·
Avoidance: Potential impacts should be avoided to the maximum
extent practicable by adopting suitable alternatives;
·
Minimisation: Unavoidable impacts should be minimised by taking
appropriate and practicable measures such as constraints on the intensity of works
operations (e.g. dredging/ jetting rates) or timing of works operations; and
·
Compensation: The loss of important species and habitats may be
provided for elsewhere as compensation.
Enhancement and other conservation measures should always be considered
whenever possible.
To summarise, this initial assessment of impacts
demonstrates that impacts will largely be avoided during the construction and
operation of the proposed Project, particularly to the key ecological sensitive
receivers (marine mammals), through the following measures:
·
Avoid Direct and Indirect Impacts to
Ecologically Sensitive Habitats: The site for the GRS reclamation has avoided the key habitats for
Indo-Pacific humpback dolphin (including Sha Chau and
·
Pipeline Alignment: The preferred alignment of the two
submarine pipelines is at a sufficient distance from key ecological sensitive
habitats, such as the Sha Chau
and Lung Kwu Chau Marine
Park, so that the transient ([24])
elevation of suspended
sediment concentrations from the installation works does not affect the
receivers at levels of concern.
·
Installation Equipment: The installation of the pipelines has
been shown to be environmentally acceptable and compliant with the water
quality assessment criteria.
·
Adoption of Acceptable Working Rates: The modelling work has demonstrated that
the selected working rates for dredging/ jetting will not cause unacceptable
impacts to the receiving water quality ([25]).
Consequently, unacceptable indirect impacts to marine ecological
sensitive receivers and resources have been avoided.
8.8.2
General Measures for Marine Ecological
Resources
The following measures to mitigate the impact of the
construction and operation of the marine ecological resources, including marine
mammals, are recommended:
·
The
vessel operators will be required to control and manage all effluent from
vessels to prevent avoidable water quality impacts;
·
A
policy of no dumping of rubbish, food, oil, or chemicals will be strictly
enforced. This will also be covered
in the contractor briefings; and
·
The
effects of construction of the Project on the water quality of the area will be
reduced as described in the Water Quality
Impact Assessment (Section 6). These measures will serve to ensure
water quality impacts are compliant with the relevant water quality standards,
as set out in statutory Water Quality Objectives.
8.8.3
Specific Measures for Marine Mammals
Measures to mitigate the impact of the construction
and operation of the Project have been developed in consultation with an
internationally-recognised marine mammal expert. The following recommendations may be
considered to reduce potential construction and operation impacts on
Indo-Pacific humpback dolphins:
·
All
vessel operators working on the Project construction will be given a briefing,
alerting them to the possible presence of dolphins in the marine works area,
and the guidelines for safe vessel operation in the presence of cetaceans. If high-speed vessels are used in this
Project, they will be required to slow to 10 knots when passing through the
Project’s marine works area. With
implementation of this measure, the chance of boat strike resulting in physical
injury or mortality of marine mammals will be extremely unlikely. Similarly, by observing the guidelines,
vessels will be operated in an appropriate manner so that marine mammals will
not be subject to undue disturbance or harassment; and
·
The
vessel operators of this Project will be required to use predefined and regular
routes, as these will become known to dolphins using these waters. This measure will further serve to
minimise disturbance to marine mammals due to vessel movements.
In line with current practice in areas where
Indo-Pacific humpback dolphins are present in
·
A
marine mammal exclusion zone within a radius of 250 m from dredgers / jetting laybarge will be implemented during the construction
phase. Qualified observer(s) will
scan an exclusion zone of 250 m radius around the work area for at least 30
minutes prior to the start of dredging / jetting. If cetaceans are observed in the
exclusion zone, dredging / jetting will be delayed until they have left the
area. This measure will ensure the
area in the vicinity of the dredging / jetting work is clear of marine mammals
prior to the commencement of works and will serve to reduce any disturbance to
marine mammals. As per previous
practice in Hong Kong, should cetaceans move into the dredging / jetting area
during dredging, it is considered that cetaceans will have acclimatised
themselves to the works, therefore cessation of dredging / jetting is not
required ([26]).
8.9
Residual Environmental Impacts
Taking into consideration the ecological value of the
habitats discussed in the previous sections and the resultant mitigation and
precautionary measures, residual impacts occurring as a result of the proposed
terminal have been determined and are as follows:
·
The
loss of approximately 100 m of artificial shoreline which is 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 approximately 200 m of vertical seawalls that are expected
to become recolonised by intertidal and subtidal assemblages of a similar nature after
construction;
·
The
loss of about 0.5 ha of subtidal soft bottom
assemblages within the reclamation sites.
The residual impact is considered to be acceptable as the habitat is of
low ecological concern and very small in size in the context of surrounding
similar habitat.
·
The
loss of about 0.5 ha of marine waters within the reclamation sites. Although the habitat loss would be an
inevitable and adverse consequence of the Project, the residual impact is
assessed to be acceptable after taking into consideration a number of
factors. The loss of marine mammal
habitat is very small in the context of the size of habitat available to
dolphins. Taking account of the
sizable home ranges and mobility of affected animals, it is expected that the
loss would not give rise to biologically significant adverse impacts on
individual dolphins or the dolphin population as a whole. Additionally, low densities of dolphins are
expected to occur in these waters, and the habitat which would be lost would
not be considered key marine mammal habitat in particular due to considerable
disturbance by heavy marine traffic.
·
Approximately
7.8 ha of benthic habitats (Table 8.5)
along each pipeline route will be physically disturbed during dredging/
jetting, but similar subtidal benthos will recolonise over time.
The residual impacts are considered to be acceptable as the habitats are
of low ecological value and because infaunal organisms
and epibenthic fauna are expected to recolonise the sediments after the pipelines have been
laid.
·
Given
that the daylight operations have been specified for dredging/ jetting
activities (except for 24-hour dredging across Urmston Road pipeline section) it
is expected that potential disturbance and displacement of dolphins from the
works area are expected to be temporary and of relatively short duration,
making them acceptable.
8.10.1
Project-Specific Cumulative Impacts
The assessment presented herein has already addressed
the cumulative effects of different activities of this Project on marine
ecological resources. The Water Quality Assessment (Section 6) was based on the worst-case scenario
of concurrent construction of all Project facilities and thus has also
incorporated the cumulative impacts of this specific Project. The cumulative impacts of the various
project-specific construction activities have been demonstrated in Section 6 as not causing unacceptable
impacts to water quality.
Consequently, unacceptable cumulative impacts to marine ecological
resources are not predicted to occur.
8.10.2
Cumulative Impacts with Other Developments
As for the cumulative impacts with other developments
in northwestern or western Hong Kong waters,
information from publicly available sources suggested that the construction/
implementation programmes of the following major projects would coincide with
the construction of this Project ([27]):
·
Hong
Kong Link Road (HKLR) of the Hong Kong – Zhuhai –
Macao Bridge (HZMB), which is about 15 km south of the pipeline corridor;
·
Hong
Kong Boundary Crossing Facilities (HKBCF) of the HZMB, which is about 12 km
south of the pipeline corridor;
·
Tuen Mun – Chek Lap Kok Link (TMCLKL), which is about 10 km from the pipeline
corridor; and
·
Contaminated
Mud Pits (CMPs) at East Sha
Chau and South Brothers, which are at least 10 km
from the pipeline corridor.
Results of water quality modelling undertaken as part
of this EIA Study (see Section 6 for
details) showed that sediment plumes from the construction of this Project were
limited to within about 3 km of the marine works areas. Sediment plumes of similar sizes were
also reported in the EIA of the CMPs ([28]).
Water quality modelling and assessment conducted as part of ARUP
(2009a,b) ([29])
([30])
suggested that the sediment
plumes from the construction of the HKLR, HKBCF and TMCLKL were generally
confined to within the sheltered East Tung Chung Bay and do not merge with
sediment plumes from the other concurrent projects, although the plumes could,
under certain tidal conditions, slightly mix with the plumes from the
(unmitigated) Lantau Logistic Park. Since the water quality mixing zone of
this Project is unlikely to overlap with those of other concurrent projects in
this part of
Project-specific adverse operation phase impacts on
marine ecological resources are not expected to occur (Sections 8.5.2 and 8.6.2),
thus operation phase cumulative impacts with other developments in and around
Black Point are not predicted.
Indo-Pacific Humpback Dolphins
Impacts presented in Section 8.6.1 were examined to evaluate potential cumulative
impacts with other developments in northwestern or
western
·
Permanent
Habitat Loss: Permanent
habitat loss as a result of this Project is considered to be very small (0.5
ha), is focussed on a disturbed areas that was reclaimed in the past and is
unlikely to exert an unacceptable cumulative effect. Major development projects in this part
of Hong Kong are expected to result in a loss of about 487 ha of potential
dolphin habitats in HKSAR waters and 80 ha in adjacent PRC waters, of which
about 319 ha were considered as habitats regularly used by humpback dolphins ([31])
([32]).
The severity of such cumulative habitat loss is expected to be
significantly reduced to acceptable levels by mitigation measures proposed as
part of the HKBCF EIA study.
·
Underwater
Sound: this Project does
not involve any noisy construction methods such as underwater piling, hence it
is not anticipated to aggravate potential underwater sound impacts arising from
other projects in the vicinity.
This Project is located at sufficient distance (> 10 km) from other
projects, and given the similarity in underwater acoustic profiles generated by
works vessels of this Project and other projects (by the use of large vessels
generating low-frequency sound), cumulative effects of works vessels
operational sound, if any, are anticipated to be negligible.
·
Marine
Traffic from Dredging Activities & Other Marine Works: this Project is located at sufficient
distance (> 10 km) from other projects in the vicinity such that the
cumulative effects of marine traffic disturbance and dolphin collision risk, if
any, are anticipated to be negligible.
It is expected that similar, slow-moving works vessels would be used in
this Project and other projects, and similar mitigation measures, e.g. vessel
speed limit and regular routes (Section
8.8.3) would be adopted in different project to minimise the magnitude of
potential cumulative impacts.
On the basis of the above, cumulative impacts on
Indo-Pacific humpback dolphins are not predicted to occur.
Intertidal & Subtidal Assemblages
Intertidal and subtidal
assemblages within the Study Area are considered as of low ecological
value. Given the small extent of
this Project, temporary or permanent loss of these assemblages as a result of
this Project are not anticipated to contribute to unacceptable cumulative impacts
with other developments in northwestern and western
Hong Kong waters.
8.11
Environmental
Monitoring & Audit
The following presents a summary of the Environmental
Monitoring and Audit (EM&A) measures focussed on ecology during the
construction and operation phases of the proposed Project.
8.11.1
Construction Phase
During the construction phase, the following EM&A
measures will be undertaken to verify the predictions in the impact assessment
and ensure the environmental acceptability of the construction works:
·
Water
quality impacts will be monitored and checked through the implementation of a
Water Quality EM&A programme (refer to Section
6 for details). The monitoring
and control of water quality impacts will also serve to avoid unacceptable
impacts to marine ecological resources.
·
An exclusion
zone will also be monitored for the presence of marine mammals around the
dredging / jetting barges during construction of the GRS reclamation and
submarine pipelines, as described in Section
8.8.4. Through implementation
of the recommended EM&A measures, unacceptable impacts on marine mammals
will likely be avoided. Details of
the marine mammal exclusion zone monitoring components are presented in full in
the EM&A Manual presented separately.
In addition, CAPCO will conduct additional monitoring
of the distribution and abundance of dolphins during the pre-construction,
construction and post-construction phases of the Project to document potential
changes in the dolphin distribution pattern with regard to this Project and
recovery of dolphin habitat use in the vicinity of the works area. Details of the monitoring programme will
be developed at a later stage (e.g. during Environmental Monitoring &
Audit).
8.11.2
Operation Phase
The assessment presented above has indicated that
significant operational phase impacts are not expected to occur to marine
ecological resources. Consequently,
no marine ecology-specific operation phase EM&A measures are considered
necessary.
The present Project has selected a preferred location
for the GRS reclamation and submarine pipelines alignment that avoids, to the
extent practical, adverse impacts to habitats or species of high ecological
value, e.g. intertidal mudflat and horseshoe crab nursery ground in Ha Pak Nai and the Sha Chau and Lung Kwu Chau Marine Park, both of which are located at least 3 km
from the Project and are considered to be too remote to be affected. Marine ecological resources in close
proximity to the proposed Project are regarded as of low to low-to-moderate
ecological values (Table 8.2).
Although the permanent loss of about 0.5 ha of marine
mammal habitat would be an inevitable consequence of the project, the residual
impact is assessed to be acceptable after taking into consideration a number of
factors. The loss of marine mammal
habitat is very small in the context of the size of habitat available to
dolphins. Taking account of the
sizable home ranges and mobility of affected animals, it is expected that the
loss would not give rise to biologically-significant impacts on individual
dolphins or the dolphin population as a whole. Also, only low densities of dolphins are
expected to occur in these waters, thus the habitat that would be lost would
not be considered key marine mammal habitat.
Likewise, the loss of about 0.5 ha of subtidal soft-bottom habitats due to the reclamation is
considered as environmentally acceptable since the area affected is relatively
small in the context of the extent of similar habitat available in the vicinity
and the low ecological value of the affected assemblages.
As impacts arising from the proposed dredging and
jetting works are predicted to be largely confined to the specific works areas
and the predicted elevations of suspended sediment, due to the Project, are not
predicted to cause exceedances of the relevant
assessment criteria, adverse impacts to water quality, and hence marine
ecological resources or marine mammals, are not anticipated.
Measures designed to reduce impacts to the population
of marine mammals that use the area include restrictions on vessel speed. The mitigation measures designed to
reduce impacts to water quality to acceptable levels (compliance with WQOs) are also expected to mitigate impacts to marine
ecological resources.
Specific measures have been identified for marine
works taking place in areas where marine mammals are sighted and these include
monitored-exclusion zones during marine dredging and jetting works.
Operation phase adverse impacts to marine ecological
resources are not expected to occur.