This
section of the EIA report presents the findings of the marine ecological impact
assessment associated with the construction and operation of a LNG terminal at
Black Point. It summarises baseline
information on the potentially affected marine ecological resources and also
presents the findings of a field survey programme. Detailed information on the baseline
conditions and results of the field surveys are presented in Annex 9.
9.2
Legislative Requirements and Evaluation Criteria
The
criteria for evaluating marine ecological impacts are laid out in the EIAO-TM and Study Brief (no. ESB-126/2005). Annex 16 sets out the general approach
and methodology for assessment of marine ecological impacts arising from a
project or proposal. This
assessment allows a complete and objective identification, prediction and
evaluation of the potential marine ecological impacts. Annex
8 of the EIAO-TM recommends the
criteria that can be used for evaluating marine ecological impacts.
Legislative
requirements and evaluation criteria relevant to the study for the protection
of species and habitats of marine ecological importance are summarised
below. The details on each are
presented in Annex 9.
1. Marine Parks Ordinance (Cap 476);
2. Wild Animals Protection Ordinance (Cap
170);
3. Protection of Endangered Species of
Animals and Plants Ordinance (Cap 586);
4. Town Planning Ordinance (Cap 131);
5.
6. The Technical Memorandum on
Environmental Impact Assessment Process under the Environmental Impact
Assessment Ordinance (EIAOTM);
7. United Nations Convention on
Biodiversity (1992);
8. Convention on Wetlands of International
Importance Especially as Waterfowl Habitat (the Ramsar
Convention);
9. PRC Regulations and Guidelines; and,
10.
The site for
the proposed LNG terminal at Black Point is in close proximity to the existing
Black Point Power Station (BPPS) near the northern reaches of the
In
terms of water quality, the Study Area experiences relatively dynamic
estuarine-influenced conditions.
The waters are a mixture of flows from the waters in
9.3.1
Summary
of Baseline Conditions
Detailed and comprehensive seasonal
surveys were conducted examining the major habitats and species in the marine
environment surrounding Black Point.
The baseline surveys have included both the dry and wet seasons. The findings of the field surveys are
presented in Annex 9.
Dolphins
The key finding of the literature
review was the recorded presence in the waters in
For this EIA, an extensive programme of
land and vessel-based surveys has been conducted to supplement data available
from ongoing long-term AFCD monitoring.
In accordance with the requirements of the Study Brief the surveys have
been conducted monthly covering the period October 2005 through May 2006. Since this EIA study commenced in July
2005 surveys were also conducted during July, August and September 2005. These surveys have provided a detailed
overview of dolphin utilisation of Hong Kong western waters including the
Northwest Lantau and Deep Bay areas. During the field surveys, dolphins were
observed throughout the surveyed areas.
The survey data gathered to date (July
2005 through May 2006) supported previous findings in the literature and
indicated that
Subtidal Hard Bottom Habitat
Surveys in Northwest waters ([2]) have found that only a few hermatypic hard corals (Family Faviidae)
were recorded within the subtidal of the survey
area. Although these surveys were
conducted at some distance from Black Point, the results of these surveys are
deemed applicable due to similar environmental conditions. As such, coral communities of ecological
value are not predicted to occur within the Study Area.
Subtidal Soft Bottom Habitats
Literature was reviewed as part of the
EIA which indicated that field sampling would be necessary due to the lack of
comprehensive data in the Project Area.
Consequently, for this EIA benthic surveys were conducted. A total of 18 grab samples were taken
from three sites off Black Point during both the wet and dry seasons. In both seasons, benthic assemblages
were dominated by polychaete worms except for the
Urmston Road during the wet season where bivalves had higher numbers. In terms of diversity, benthic
communities at the sites were similar to other locations reported in Hong
Kong. Owing to a generally higher
proportion of bivalves, the biomass of benthos off Black Point was relatively
high compared to the Hong Kong average reported in the literature.
Intertidal Hard Bottom Habitat
Quantitative transect surveys and spotchecks were conducted on natural rocky shore and
artificial seawalls on the west and south coasts of the Black Point
headland. Rocky shore species were
common and widespread and no species of conservation interest were
recorded. In comparison to records
of other shores in
The details of all of
the baseline surveys conducted for this EIA are summarised in Table
9.1.
Table 9.1 Marine
Ecology Baseline Surveys
|
Survey Type |
Methodology |
Date |
|
Intertidal Assemblages |
Quantitative
(belt transects at 4 locations) survey, three 100 m belt transects (at high,
mid and low intertidal zones) for each location,
covered both wet and dry seasons. |
22
& 23 March and 15 & 30 July 2004 |
|
Subtidal Benthic Assemblages |
Quantitative
grab sampling survey; covered both wet and dry seasons. Six stations sampled in each of 3
locations (reclamation area, approach channel and turning circle). |
25
& 26 February and 5 & 6 July 2004. |
|
Marine
Mammal |
Land-based
visual survey during daytime, 5 days per month and 6 hours per day, covered
four seasons and 12 months. |
16,
17, 18, 19 & 26 February, 19, 22, 23, 25 & 26 March, 6, 7, 13, 14
& 15 April, 11, 13, 17, 18 & 20 May, 11, 15, 24, 25 & 29 June
2004, 9, 14, 15, 20 & 25 July 2004, 25, 26, 27, 30 & 31 August, 15,
16, 17, 20 & 21 September 2004, 27, 28, 29, 30 & 31 October 2004, 24,
25, 27, 29 & 30 November 2004, 7, 8, 9, 13 & 14 December 2004, 21,
24, 25, 26 & 27 January 2005. |
|
|
Quantitative vessel based
survey using transect methods spanning Hong Kong western waters (Deep Bay,
Southwest Lantau, Northwest Lantau
and West Lantau) 3 days, 2 times per month |
18, 19, 20,,21, 22, 25, 26, 27
July 2005, 3, 4, 5,15,24 & 25 August 2005, 5,7,15, 16 & 20 September
2005, 5, 6, 7, 17, 18 & 19 October 2005, 22, 24, 25, 28, 29 & 30
November 2005, 6,7,8 & 22 December 2005, 13, 16, 17, 19, 20, 24 January
2006, 1, 2, 3, 7, 8, 9 February 2006, 17, 23, 28, 29, 31 March 2006, 3, 6,
18, 25, 26, 27 April 2006, 2, 4, 8, 9, 10, 11 May 2006. |
9.3.2
Ecological
Importance
The ecological importance of the habitats was determined with
reference to the following:
·
Literature review findings;
·
Findings of the field surveys;
·
Comparison with other areas in Hong
Kong; and,
·
Annexes
8 and 16 of the EIAO TM.
The
ecological importance of the marine habitats and their locations relative to the
LNG terminal layout are summarised in Table 9.2. The
key findings are presented below:
·
Areas
to be Reclaimed:
The information on marine ecological resources presented in this report
has not identified any habitats of high ecological value within the reclamation
area.
·
Inshore
Marine Waters off Black Point: The ecologically important marine
mammals, Sousa chinensis
have been sighted in the area.
Based on analysis of the density of dolphins sighted, marine waters
around the Black Point headland were regarded as medium importance to these
marine mammals.
The
ecological importance of the marine habitats and their locations relative to
the LNG terminal layout are summarised in Table 9.2.
Table 9.2 Ecological
Importance of the Marine Habitats
|
Habitat |
Ecological Importance |
|
Natural
Rocky Shore |
Low |
|
Artificial
Shoreline |
Low
|
|
Subtidal Soft Bottom Habitats at Black
Point |
Low
to Medium |
|
Subtidal Hard Surface Habitat along
Artificial shoreline |
Low |
|
Marine
Waters off the Black Point Headland |
Medium
for Sousa chinensis |
9.3.3
Marine
Ecological Sensitive Receivers
Based
on the results of the marine ecological surveys and a review of the available
information on existing conditions in the study area and its immediate
vicinity, the potential sensitive receivers that may be affected by the
proposed works associated with the Project are identified as follows:
·
Designated Sha
Chau & Lung Kwu Chau Marine Park; and
·
Seagrass
Beds, Mangroves, Intertidal Mudflats and Horseshoe
Crabs.
The
locations of the sensitive receivers identified are shown in Figure
6.4
(see Part 3 Section 6).
A
desktop literature review and supporting field surveys (summarised in Part 3 Section 9.3 and detailed in full in Part 3 Annex 9) were
conducted in order to establish the ecological profile of the area within and
surrounding the Study Area. The
Study Area for the marine ecology baseline include the boundary of 500m from
the proposed Project Area and incorporated the proposed approach channel and
turning circle as well as the reclamation area. The importance of potentially impacted
ecological resources identified within the Study Area was assessed using the
methodology defined in the EIAO-TM. The potential impacts due to the
construction and operation of the terminal and associated developments were
then assessed (following the EIAO-TM Annex 16 guidelines) and the impacts
evaluated (based on the criteria in EIAO-TM
Annex 8).
9.5
Potential Sources of Impact on Marine Ecological Resources
9.5.1
Construction
Phase
Potential
impacts to marine ecological resources arising from the construction works may
be divided into those due to direct disturbances to the habitat and those due
to perturbations to key water quality parameters. Potential impacts to marine mammals are
discussed in Part 3 Section 9.7. As discussed in Section 3, the construction of the proposed LNG terminal at Black
Point will involve dredging to construct a seawall and reclamation, backfilling
for reclamation and dredging for the turning circle and approach channel. Construction of the jetty may require
percussive piling. Impacts
associated with the proposed LNG terminal are thus divided into those occurring
during:
·
Dredging and reclamation for the
terminal, including dredging seawall trenches, filling with sand and suitable
fill etc;
·
Dredging for the approach channel and
turning basin; and
·
Construction of the jetty.
Dredging
and Reclamation for the Terminal
Along
the line of the seawalls the existing marine sediments will be dredged to
provide suitable foundations. After
completion of the seawall, the muds within the
reclamation sites will be partially dredged and then filled using sand and
public fill. Impacts to the marine
ecological resources potentially arising from dredging and reclamation at Black
Point are as follows and summarised in Table 9.3.
Table 9.3 Summary
of Potential Construction Phase Impacts associated with Dredging and Reclamation
for the LNG terminal at Black Point (including the intake and outfall)
|
Nature of Impact |
Marine Habitat
Affected |
Location |
Potential Impact |
|
Habitat Loss |
Subtidal Soft Bottom Habitat |
Black Point |
Permanent loss of approximately 16 ha
of seabed |
|
|
Subtidal Hard Bottom Habitat |
Black Point |
Permanent loss of approximately 600 m
of subtidal natural rocky coastline and
approximately 120 m of artificial shore |
|
|
Intertidal Natural Rocky Shore |
Black Point |
Permanent loss of approximately 600 m
natural rocky shore |
|
|
Intertidal Artificial Shore |
Black Point |
Permanent loss of approximately 120 m
of artificial shore |
|
Short term Changes
in Water Quality |
Subtidal Soft Bottom Habitat |
Black Point |
Potential smothering and burial of
benthic organisms during dredging |
|
|
Subtidal Hard Bottom Habitat |
Black Point |
Potential water quality impacts on subtidal organisms |
|
|
Intertidal Natural Rocky Shore |
Black Point |
Potential water quality impacts on intertidal organisms |
Habitat Loss
Subtidal Soft Bottom Habitats
Within
the reclamation site, primary impacts will be the smothering and burial of
organisms during filling, or removal of organisms during dredging. These impacts will be an unavoidable
consequence of the works during dredging and sandfilling
operations associated with the reclamation works for the terminal. It is important, therefore, to determine
whether the reclamation site contains unique or otherwise noteworthy benthic
assemblages which will be lost.
Findings from a literature review, supplemented by focussed field
surveys, indicate that the benthic assemblage within, and in the vicinity of
the reclamations were dominated by polychaetes and
characterised by similar species diversity and dry season biomass as found
elsewhere in Hong Kong. The wet
season biomass of the benthic assemblage at Black Point was comparatively
higher than other areas in Hong Kong Waters. However, all of the species recorded
occur frequently in Hong Kong and no rare species were observed. As a result, the assemblages were
regarded as being of low ecological value.
The
scale of the reclamation has been reduced as far as practicable through
modifications to the engineering layout.
Although the proposed reclamation and dredging will result in permanent
loss of approximate 16 ha (due to the reclamation) of subtidal
soft benthic habitats, 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 Hard Surface Habitats
The
construction of the reclamations for the Project will result in the permanent
loss of low ecological value subtidal hard surface
habitats (no coral communities expected to be found along the approximately 600 m of
natural rocky shore). The
assemblages within the Black Point reclamation areas will be lost through the burial
of organisms present there.
Rubble
mound and/or armour rock/concrete armour seawalls will be used along the
reclamation area and will provide approximately 1.1 km of habitat for subtidal organisms to colonise. It has been demonstrated that similar
marine organisms have recolonised such seawalls after
construction ([3]) ([4]). It is anticipated that assemblages of subtidal organisms will 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 subtidal organisms.
The potential habitat provided by the total surface area of the rubble
mound and/or armour rock/concrete armour seawalls on the reclamations is
expected to allow the recolonisation of the subtidal assemblages within the reclamation sites.
Intertidal Habitats - Rocky Shores and Artificial Shorelines
A
length of approximately 600 m of low ecological value natural rocky shore and approximately 120 m of low
ecological value artificial shore will be lost as a result of reclamation
activities for the terminal. The
results from field surveys indicated that the intertidal
assemblages recorded on the rocky shores are typical of semi-exposed rocky
shore communities observed in
Changes in Water Quality
Suspended Sediments
The
construction of the reclamation for the terminal will involve dredging of
sediments within the reclamation site and along the line of the seawalls to
provide suitable foundations, and filling of the reclamations using sand and
public fill. The modelling works
have analysed suspended sediment (SS) dispersion from dredging of the
reclamation site in the case that some marine muds
have to be removed (see Part 3 Section 3).
Subtidal Soft Benthos: The subtidal
soft benthos in and around the proposed terminal is considered to be of low
ecological value (Part 3 Annex 9); however, these sessile
organisms will be susceptible to the effects of increased sediment loads
through smothering and burial.
Sediment may be deposited on the seabed outside the reclamation sites
during backfilling (through dispersion of sediment plumes) and post-placement
(through erosion and wave-induced re-suspension), and outside the turning
circle and approach channel during dredging. Impacts to benthic assemblages
immediately outside of the reclamation site and dredged areas are expected to
occur temporarily. The area is
expected to be small as sediment will be deposited within a short distance of
the dredging and filling works.
With reference to the water quality modelling results, elevations in
suspended sediment levels would be localised and confined to the works
area. It should be noted that
dredging for the reclamation may take place behind constructed seawalls which
would greatly reduce the dispersion of SS.
As the area is often disturbed by demersal
trawling and SS laden discharges from the Pearl River, the organisms present
are thus assumed to be adapted to seabed disturbances. Based on the assumption that eventually
the affected areas will be recolonised by fauna
typical of the area, then the temporary loss of these low ecological value
assemblages is deemed acceptable.
Subtidal Hard Surface Habitats: Since there were no coral assemblages
(including soft corals, gorgonians, black corals and hard corals) of ecological
interest recorded within or in the vicinity of Black Point, adverse impacts to
corals are not predicted to occur.
Intertidal Habitats: Intertidal
habitats within the Study Area which may be affected by the reclamation and
dredging activities include the natural rocky shores located at Black
Point. With reference to the water
quality modelling results (Part 3 Section 6), elevations in SS levels are
predicted to be localised and confined to the works area. Furthermore, the dredging is expected to
be partially enclosed by newly constructed seawall which would further limit
the spread of SS in the water column. Due to the low quality of the intertidal habitats identified within the Study Area and
the intertidal assemblages being naturally exposed to
high levels of suspended solids in the Pearl River Estuary, adverse impacts to
the intertidal assemblages on the south side of the
Black Point headland arising from elevated SS levels are not anticipated.
Dissolved Oxygen
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 have indicated that low levels of SS elevations are expected
outside of the works areas.
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 vicinity of the terminal and dredging areas will not
occur.
Dredging
for the Approach Channel and Turning Basin
Dredging
for the approach channel and turning basin will be scheduled after the
completion of the dredging under the seawall and with similar timing as the filling
of the reclamations using sand and public fill. Impacts to the marine ecological
resources potentially arising from the dredging activities in the open water
near Black Point are as follows.
Table
9.4 Summary
of Potential Construction Phase Impacts associated with Dredging for the
Approach Channel and
|
Nature of Impact |
Marine Habitat
Affected |
Location |
Potential Impact |
|
Habitat Loss |
Subtidal Soft Bottom Habitat |
Off Black Point |
Temporary disturbance of
approximately 47 ha of seabed |
|
Change in Water
Quality |
Subtidal Soft Bottom Habitat |
Off Black Point |
Potential sediment deposition on
benthic organisms |
|
|
Subtidal Hard Bottom Habitat |
Off Black Point |
Potential water quality impacts on subtidal organisms |
|
|
Intertidal Natural Rocky Shore |
Off Black Point |
Potential water quality impacts on intertidal organisms |
Habitat Loss
The
areas within the boundary of the proposed turning basin and approach channel
are approximately 47 ha. Dredging
will be only required for those areas with a water depth less than 15 m. This direct impact on the subtidal soft bottom habitat will be temporary in nature
and the disturbed seabed will be available for recolonisation
by benthic fauna after the removal of sediment. For these reasons as well as the low
ecological value of this habitat, the severity of the impact is anticipated to
be acceptable. Intertidal
and subtidal hard surface habitats will not be
directly affected due to the dredging works.
Changes in Water Quality
Suspended Sediments
The
existing marine sediments along the section of turning basin and approach channel
of a depth less than 15 m will be dredged to allow navigation of the LNG
carrier. The dredging will only
affect the seabed for a short duration.
The modelling works have analysed SS dispersion from dredging of the
turning basin and approach channel.
Subtidal Soft Benthos: Water quality modelling results
indicated that the extent of the sediment plume is localised to the works areas
and would be compliant with WQO.
Mean depth averaged SS level of > 10 mg L-1 in the absence
of mitigation measures would be generally confined to the works area in both
the dry and wet seasons (see Part 3 Section 6). The impacts
are expected to be of short duration.
As the area is often disturbed by demersal
trawling, the organisms present are thus assumed to be adapted to seabed
disturbances. The affected areas
will be recolonised by fauna typical of the area and
hence the temporary loss of these low ecological value assemblages is deemed
acceptable.
Intertidal Habitats: Intertidal
habitats within the Study Area which may be affected by the dredging activities
include the natural rocky shores located at Black Point. Sediment dispersion results predict
that, elevations in SS levels are expected to be localised and confined to the
works area in the both dry season and wet seasons (Part 3 Section 3). The intertidal
assemblages at Black Point are naturally exposed to high levels of suspended
solids in the Pearl River Estuary.
Due to the low quality of the intertidal
habitats within the Study Area and the short duration of the dredging
activities, adverse impacts to the intertidal
assemblages arising from elevated SS levels are not anticipated.
Dissolved Oxygen
Depletions of
DO as a result of dredging activities are expected to be low and compliant with
the relevant WQOs (refer to Part 3 Section 6 for details).
It is, thus, expected that unacceptable impacts to the marine ecological
habitats and populations present in the vicinity of the dredging areas will not
occur.
Nutrients
The
levels of nutrients are not expected to increase appreciably from background
conditions during the reclamation and dredging operations (refer to Part 3 Section 6 for details). Algal blooms are not expected through
works and unacceptable impacts to the marine ecological habitats and populations
present in the vicinity of the terminal and dredging areas will not occur.
Construction
of the Jetty
Construction
of the jetty on the newly reclaimed land at Black Point is scheduled after
completion of dredging works for the approach channel and turning basin. The jetty would be constructed using
piling construction methods. Water
quality impacts associated with piling are negligible and would not impact
marine ecological resources.
Potential impacts that would arise due to the construction of the jetty
are introduced in Table 9.5 and
discussed below.
Table 9.5 Summary
of Potential Construction Phase Impacts associated with Jetty Construction at
Black Point
|
Nature of Impact |
Marine Habitat
Affected |
Location |
Potential Impact |
|
Habitat Loss |
Intertidal Hard Bottom Habitat |
Black Point |
Disturbance of approximate 20m of
newly constructed artificial shore |
|
|
Subtidal Soft Bottom Habitat |
Black Point |
Disturbance to small areas of seabed under
the jetty |
|
|
Subtidal Hard Bottom Habitat |
Black Point |
Permanent loss of approximate 20m of
newly constructed artificial coastline |
Habitat Loss
Intertidal Hard Bottom Habitat
Construction
of the jetty will result in minor disturbance to a small stretch of newly
constructed seawall. Being newly
constructed, it is expected that this stretch of seawall would be of low
ecological value and the impact would be acceptable.
Subtidal Hard Bottom Habitat
The
jetty would connect to the newly constructed reclamation area for the LNG
terminal. Being newly constructed,
it is expected that this stretch of seawall would be of low ecological value
and the impact would be acceptable.
Hydrotest Water
A
potential additive to the hydrotest water for the LNG
tanks will be low concentrations of chlorine (0.05 mgL-1). The impacts on marine ecology due to the
discharge of such hydrotest water are similar to the
cooled water discharge and were addressed in the following section (Part 3 Section 9.5.2).
9.5.2
Operation
Phase
Hydrodynamic
Regime
The
reclamation for the LNG terminal will bring about a change in the shape of the
existing coastline. If this causes significant
change in the hydrodynamic regime of the surrounding waters, there would be
potential for impacts on marine ecological resources to occur. 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 (DO), an increase in nutrient levels and
consequent impacts to marine ecological resources. The effect of changes in coastal
configuration on the current velocities have been assessed (see Part 3 Section 6). The
hydrodynamic modelling has indicated that the reclamation in Black Point 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.
Maintenance
Dredging
To
the extent practical, the selection of the fairway transit and approach channel
for the LNG carrier was based on the availability of the required charted water
depth. The intent is to reduce the
dredging quantities and hence potential impacts to water quality. The difference in water depth between
the dredged channel and areas in the vicinity is approximately 8 m, and
consequently the maintenance dredging will be approximately once every 4 - 5
years. Dredging works associated
with maintenance of the approach channel and turning basin are expected to be
of a lower magnitude than those associated with the construction phase dredging
requirements discussed above. As no
unacceptable adverse impacts to water quality have been predicted to occur as a
result of construction phase dredging, it can be expected that no unacceptable
adverse impacts to marine ecological resources would occur through maintenance
dredging.
Discharge
of Cooled Water
Cooled water with a decreased
temperature of approximately 12.5°C from ambient will be discharged at the
seawater outfall, which is located at the seabed off the proposed LNG terminal
at Black Point. The flow rate of
the discharge is equivalent to 18,000 m3 hr-1 (peak
flow). The potential impacts of this discharge are principally related to the
ecological effects of a zone of reduced temperature near the point of
discharge. The water quality model
has predicted the minimum temperature that would be experienced in waters
adjacent to the discharge point (see Part
3 Section 6 for details). The results show that water temperatures
between 2 to 5°C lower than ambient conditions would
occur in a localised area close to the outfall. Beyond the close vicinity of the outfall
point, temperatures would not be more than 2°C lower than ambient conditions. In this way, cooling water discharge
from the LNG terminal is not expected to cause any significant changes in water
temperature that would impact subtidal or intertidal habitats.
In terms of temperature differences, cooled water discharges are not
expected to cause adverse impacts on marine ecological resources of the area.
Cooled Water - Antifoulants
There are considerable operational and
ecological issues caused by organisms within, and passing through industrial
water systems and, these problems can be costly ([5]).
Mussels, oysters and other marine organisms growing within cooled water
circuits have resulted in losses in thermal efficiency and even total
shutdowns. To counteract settling
and actively growing fouling organisms, cooled water circuits are usually dosed
with antifoulants (typically chlorine in the form of
sodium hypochlorite). This causes
mortalities of both the fouling and non-fouling organisms in the circuit. The discharge of the resulting
chlorinated effluents may in turn have effects on the habitat beyond the
outfall.
The effluent from the cooled water
system will contain traces of antifoulant at a
concentration of 0.3 mg L-1, which is below EPD’s
([6]) statutory limit of 1.0 mg L-1. Values are available from the literature
on the physiological response to chlorine in water which can be used for
reference purposes (Table 9.6). For the majority of organisms the
toxicity of residual free chlorine depends on the concentration and exposure
time. Short exposure to high
concentrations often leads to lethal effects as do long term exposures to low
concentrations ([7]).
Table
9.6 Toxic
Responses of Marine Organisms to Residual Free Chlorine in Discharges
|
Organism |
Toxic Responses |
Cl (mg L-1) |
|
Phytoplankton |
Photosynthesis
of marine phytoplankton depressed by 70-80% |
0.02-0.04 |
|
Zooplankton |
Short
term exposure has led to rapid but temporary responses demonstrated through
depression in metabolic rate and reproductive activity. |
0.01 |
|
Oyster
Larvae (Ostrea edulis) |
Tolerant
of short term exposure with no demonstrated toxic response. |
0.2-0.5 |
|
Barnacle
Larvae (Elminius modestus) |
Tolerant
of short term exposure with no demonstrated toxic response. |
0.2-0.5 |
|
Lobster
Larvae (Homarus americanus) |
Respiration
rate increased after 60 minute exposure to 0.1 mg L-1 and after 30
minute exposure to 0.1 mg L-1. |
0.01 0.1 |
Note: Information
gathered from references contained in Langford TE (1983) Electricity generation
and the ecology of natural waters
Concentrations of residual chlorine
diminish rapidly with time and distance from the discharge point ([8]).
The modelling exercises conducted for the water quality assessment
(reported in Part 3 Section 6) indicate that residual
chlorine concentrations exceeding 0.01 mg L-1 are only likely to
occur within 300m of the outfall and are mainly confined to the bed layer of
the water column. These predicted increases
do not exceed tolerance thresholds established in the literature (0.02 mg L-1)
and are in accordance with those levels recommended in previous studies in Hong
Kong (0.01 mg L-1). As a
result, impacts to marine ecology as a result of potential concentrations of
residual chlorine are not expected to occur.
Impingement and Entrainment of Fauna in
the Seawater System
In order to provide water for regasification
of LNG, seawater will be extracted via a submarine intake in the seawall.
There is a potential for impingement
and subsequent entrainment of marine organisms in the intake system. This affects different groups of animals
to differing degrees. Smaller
pelagic species are the most vulnerable, while burrowing animals are rarely impinged,
and large pelagic species are usually strong enough to avoid the intake stream.
Not all animals that impinge on the
system will be entrained within it.
Screening of water intakes will prevent the entrainment of all but the
smallest organisms. Impinged
animals may suffer mechanical and physiological stress, but evidence from power
station cooling systems suggest that this is not a significant source of
mortality ([9]).
Entrained animals may be subject to
additional thermal stresses and mortality is relatively high. However, these will typically be
confined to plankton, which have an extremely high natural mortality. Extensive research shows that the
mortality of plankton in seawater systems does not give rise to a significant
impact ([10]) ([11]).
An assessment of impacts associated
with impingement and entrainment of marine organisms is presented in the Fisheries Impact Assessment (Part 3 Section 10). It was
concluded that impacts associated with operation of the water intake would not
cause unacceptable impacts on fisheries resources. In conclusion, operation of the water
intake would not be expected to result in unacceptable impacts on marine
ecological resources.
Accidental Spillage of LNG
An accidental LNG release would be
vaporized quickly into the atmosphere and would not be expected to impact
marine ecology. If spilled onto the
LNG terminal platform or into the ocean (LNG is less dense than water), LNG
would boil rapidly (due to exposure to higher ambient temperatures). Because of the material’s density and
turbulence created by the rapid boiling, an LNG spill would vaporize rapidly,
leaving no environmental residue.
Any accidental LNG spill would therefore be of short duration,
reversible and will occur within a limited and transient mixing zone. This issue is further discussed in Part 3 Section 6 – Water Quality and
Part 3 Section 13 Quantitative Risk Assessment (in particular the
consequential fire hazard).
Accidental
Spill of Fuel from LNG Carrier
It
is considered that a spillage of fuel is highly unlikely (for details refer to Part 3 Section 6.7.8), therefore
potential risk on Chinese White Dolphins due to accidental spill of fuel is
expected to be low.
9.6
Evaluation 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 impact associated with the construction and operation of the
LNG terminal has been evaluated in accordance with the EIAO-TM (Annex 8, Table 1)
as follows.
·
Habitat
Quality: Impacts are
predicted to occur only to the low quality coastal habitats (inter-tidal and subtidal) and benthic habitats identified during the field
surveys within the reclamation site.
The selection of the reclamation site has avoided habitats of high
ecological value and the Sha Chau
and Lung Kwu Chau Marine
Park. Operational phase discharges
from the terminal are not expected to impact any habitats of high ecological
value.
·
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 habitat were situated at distant
locations from the proposed works. No construction phase impacts are expected
to these sensitive receivers. Operational phase discharges from the terminal
are not expected to impact these sensitive receivers.
·
Size:
The total size of the reclamation site is
16 ha, including 600 m of natural rocky shore and 120 m of artificial
shore. Low ecological value intertidal, subtidal hard surface
and benthic assemblages within the terminal footprint will be directly
impacted. The low ecological value
benthic assemblages within certain areas of the turning basin and approach
channel will be lost during dredging but are expected to become re-established
within a year (see Reversibility).
·
Duration:
The reclamation works are predicted to
last for 7 - 8 months and the dredging for the turning basin and approach
channel approximately 7 - 8 months.
Increases in SS levels in the vicinity of sensitive receivers are
expected to be low and temporary, and within environmentally acceptable limits. Operational phase discharges will
continue during the life of the LNG terminal but are not predicted to cause
adverse impacts to marine ecological resources as the discharges disperse
rapidly and do not affect high ecological value habitats.
·
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 and natural rocky shore can be expected to recolonise
the seawall once it is reinstated.
·
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 ([12]).
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
assemblages within the Study Area is expected to be compensated through the
provision of seawalls that provide adequate surfaces for colonisation once
reclamation works have been completed (1.1 km of rubble mound and/or concrete
armour seawalls). It has been
demonstrated that marine organisms have recolonised
these seawalls after construction ([13]).
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.
Impacts to marine ecological resources
during operation of the terminal are predicted to be within acceptable levels
in ecologically important areas through appropriate design of the seawater
outfall (as discussed in Part 3 Section 6 - Water Quality).
Hence no additional marine ecology
specific mitigation measures to control discharges are required during project
operation.
9.7
Potential Sources of Impact on Marine Mammals
In this section of the report, 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 the effects on the Indo-Pacific Humpback
Dolphin. 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 lifestage) 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([14]) ([15]) ([16]).
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 and localised,
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 foraging 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, 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 Rates: 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 self-evidently
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
effect: 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).
9.7.1
Construction
Phase
As discussed previously, works for the
proposed LNG terminal will involve:
·
Dredging and reclamation for the
terminal, including dredging seawall trenches, filling with sand and suitable
fill etc;
·
Dredging for the approach channel and
turning basin; and
·
Construction of the jetty.
The following sections provide an
assessment of potential impacts associated with these works and activities and
effects on dolphins.
Reclamation Works - Habitat Loss
The approximately
16
ha of proposed reclamation at Black Point for the LNG terminal would cause the
permanent loss of sea area and hence the permanent loss of marine mammal
habitat ([17]).
The physical loss of habitat during and after reclamation works, could
affect some individuals of Indo-Pacific Humpback Dolphin, Sousa chinensis, which utilise Black
Point waters as a part of their home range. Based on the vessel-based and land-based
survey findings as well as AFCD monitoring records, it is known that the inshore
waters affected by the proposed reclamation are an area of medium density
dolphin sightings and have been evaluated to be of medium ecological
importance. Although, the area is
subject to considerable disturbance by high volumes of vessel traffic, the loss
of this area of
Although the loss of these waters due
to reclamation is assessed to be an adverse consequence of the Project, it
should be noted that the loss is not likely
to significantly impact the fitness or vital rates of affected individual
animals that currently utilise these waters. Information from the fisheries impact
assessment (Part 3 Section 10)
indicates that 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 fisheries resources in the marine habitat
serve as marine mammal’s food prey).
Photo-identification studies have shown Indo-Pacific Humpback Dolphins
have extensive home ranges typically extending over 100 km2 (see Figures 9.28 and 9.29 of Part 3 Annex 9 for details) and may forage and feed
throughout. In the context of the size
of the home ranges which may encompass extensive areas across North Lantau waters and beyond, although sizeable, the 16 ha of
habitat would represent a relatively small portion of individual animal’s home
range.
Potential Impacts from Works Vessels (all
marine works)
Increased
marine traffic: Construction of the terminal has the
potential to result in an increase in marine traffic which may affect the
Indo-Pacific Humpback Dolphin. In
Hong Kong, there have been instances when dolphins in Hong Kong have been
killed or injured by vessel collisions ([18]) ([19]), and it is thought that this risk is
mainly associated with high-speed vessels such as ferries. In terms of potential impacts arising
due to increased vessel traffic associated with the dredging and reclamation
works for the LNG terminal, the risk of vessel collision is considered to be
very small as work vessels would be slow moving. Slow moving vessels would not pose a
significant risk to dolphins including young animals. To err on the side of caution, the risk
of vessel strike will also be managed through a series of precautionary
measures (see Part 2 – Sections 9.9.3 and 9.10 for details). It should be noted that waters off Black
Point have existing high levels of marine traffic using the Urmston Road
channel. In this context, vessel traffic associated with the proposed project
would represent a minor increase in marine traffic in this area.
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 detailed in Part 3 –Annex 9 – Baseline Marine Ecological
Resources, photo-identification of individual dolphins has shown these
animals have extensive home ranges typically 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 Hong Kong. Contaminated mud disposal facilities
have been in operation in the East of Sha Chau area for over ten years. Data available on the use of the waters
does not indicate that the operations of these facilities are resulting in
avoidance behaviours by the dolphins ([20]).
In addition, dolphins have returned and are using the waters near the Chek Lap Kok airport ([21]).
Underwater
sound: Construction of the terminal has the potential to result in
a minor and short term increase in underwater sound from marine vessels, which
may affect the Indo-Pacific Humpback Dolphin. Effects from pile driving are considered
in a later section. Small cetaceans
are acoustically sensitive at certain frequencies, and sound is important to
their behavioural activities. 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 ([22]).
Indo-Pacific Humpback dolphins have been reported to use five categories
of vocalisation associated with different activities([23]).
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.
Dredging and large vessel traffic generally results in low frequency
noise, typically in the range of 0.02 to 1 kHz ([24]), which is below the peak range of 8 -
90 kHz reported for dolphins. For
this reason, noise generated by dredging operations is not expected to
acoustically interfere significantly with dolphins.
Water Quality Impacts
High SS levels do not appear to have a
direct impact on dolphins. 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 rather than visual information. In addition, dolphins are air breathing
and therefore SS in the water column has no effect on their respiratory
surfaces. Impacts may occur to
these mammals as an indirect result of increased SS levels. The construction of the terminal and
dredging may cause perturbations to water quality which have the potential to
impact the fisheries resources of the Northwestern
Waters. The Indo-Pacific Humpback
Dolphin is thought to be an opportunistic feeder with the most important prey
species being demersal fish (such as croakers, Sciaenidae) as well as several pelagic groups (engraulids, clupeids and trichiurids). They are thus likely to be affected by
any significant changes in key water quality parameters (such as SS and DO)
arising from the development. A
deterioration in water quality would cause these mobile fish to move out of the
area thus interfering with the dolphin normal feeding patterns.
Information from the fisheries
impact assessment (Part
3 Section 10) indicates that indirect impacts
are not predicted to adversely impact fisheries resources as the SS elevation
are localized to the works areas.
The consequences of this are that impacts to marine mammals through loss
of localised habitat access food supply (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 the Indo-Pacific Humpback Dolphin,
and their prey species are naturally exposed to high levels of suspended solids
in the Pearl River Estuary (see Part 3
Section 6 for a discussion of how SS
levels fluctuate greatly in this part of Hong Kong) ([25]).
The basis for this assessment are water
quality modelling predictions presented in Part
3 – Section 6. While contour
plots of water quality parameters were used to determine the extent and
severity of impacts close to the works areas, which is the most important
information for determining impacts on marine mammal habitat, in addition
reference was made to a variety of assessment points for various water sensitive
receivers that are distributed at various points across marine mammal habitat
including SR1, SR4, SR5a-b, SR6a-e and SR8 (see Figure 6.4 in Part 2 – Section 6).
Other EIA Studies which 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) ([26]) stated that: “There is no reason to
assume that suspended solid releases during pipeline construction will have an
impact on dolphins.” Similarly, construction of a blockwork
jetty and dredging at Lung Kwu Chau
inside Lung Kwu Chau and Sha Chau Marine Park have not
significantly affected dolphin utilisation in this area. Dolphins were observed in proximity to
major reclamation works at Penny’s Bay ([27]).
Based on the assessment above and other
experience of the effect of suspended sediment on marine mammals, elevations in
SS associated with the reclamation works for the LNG terminal are not
anticipated to adversely impact dolphins.
The above analysis is supported by
experience with ongoing projects in Hong Kong. Contaminated mud disposal facilities
have been in operation in the East of Sha Chau area for over ten years. Data available on the use of the waters
do not appear to indicate that the operations of these facilities are resulting
in avoidance behaviour by dolphins.
Contaminant Release
Another potential impact on marine mammals
associated with disturbance of bottom sediment that require assessment in
accordance with Clause 3.7.5.5 of the
Study Brief, is the potential bioaccumulation of released contaminants. The potential for release of
contaminants from dredged sediments has been assessed in Part 3 Section 6,
whereas, a comprehensive set of data on the quality of marine sediment is
provided in Part 3 Section 7 – Waste Management.
Within these sections it is concluded
that some of the samples from the reclamation and dredging area contained
levels of arsenic in excess of the Lower Chemical Exceedance
Level (LCEL) but below the Upper Chemical Exceedance
Level (UCEL), ie Category M. It is highly likely that the elevated
levels of arsenic are derived from natural sources and are not present as a
result of human activity.
In terms of the potential for impacts
to occur to marine mammals, a recent EIA 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 ([28]).
The assessment, which was based on bio-concentration factors and metal
concentrations in local fish and shellfish species, determined that the
bioaccumulation potential from contaminant concentrations in marine water and
sediments presented no unacceptable risk to marine mammals associated with
consuming prey items in the vicinity of the contaminated mud pits as elevations
in body burden levels were expected to be minor.
The aforementioned assessment was based
on highly contaminated mud, ie Category H. As mentioned, extensive monitoring of
sediment quality in the West Lantau area has been
documented in Part 3 Section 7 – Waste Management. The suite of analytes
has included a range of organic compounds specified in the relevant Technical
Circular (ETWBTC No. 34/2002) and 12 chlorinated pesticides. All samples reported concentrations of
these substances below the reporting limits.
Therefore, as unacceptable water
quality impacts due to the potential release of heavy metals and micro-organic
pollutants from the dredged sediment are not expected to occur, impacts on
marine mammals due to bioaccumulation of released contaminants from dredged
sediments are also not expected to occur.
Potential Impacts from Piling Works
Underwater
sound: Marine piling works will be required to construct the jetty
off the newly constructed reclamation area for the LNG terminal. Certain piling activities are known to generate
high intensity underwater sound, which due to the potential presence of
dolphins in the vicinity of works, requires assessment. Based on engineering conditions of the
jetty site, it is proposed that the jetty would be constructed using large diameter
bored piles with pre-bored H-piles.
For the construction of the approximately 100 m long trestle which
connects to the jetty, it is proposed that percussive piling would be used. No underwater blasting is required. Details on the differences between bored
and percussive piling are presented below.
Bored
piling:
The pile installation of the main jetty will be carried out by bored
piling works. This involves the
sinking of a casing down to almost the rock head level with underwater
excavation of the soil by grab and the top layer of rock using a reverse
circulation drilling rig (RCD).
Noise created by the bored piling method tends to be a less intensive
continuous noise, rather than the pulsed high power sounds emitted through
percussive piling and is expected to be similar to that associated with
dredging.
Bored piling usually creates a steady
sound that is less disruptive to dolphins than the pulsed or burst sounds
associated with activity such as percussive piling ([29]).
Dolphins are known to habituate to low-level sounds such as those
produced through bored piling ([30]).
Percussive
piling: The trestle
foundations will consist of circular piles installed by the percussive method
using piling barge with hydraulic hammer. As detailed in Part 3 Section 3, the
equipment for percussive piling works used in Hong Kong is typically fitted
with a bubble jacket for reducing underwater sound propagation. Although percussive piling will produce
high-intensity underwater sound, the progress of piling works is quicker than
bored piling. It is expected it
would take approximately 4 months to complete the piling for the 100 m long
trestle. Sound from percussive
piling activities will be transmitted to the water via both structure-borne and
air-borne sound pathways.
Structure-borne vibrations from the percussive hammer will be
re-radiated as sound into the water via the piles, the rock substrata and the
piling rig to the barge. The
air-borne sound pathway consists of sound propagation from the percussive
hammer and the piles through the air and into the water. The sound transmitted to the water via
the air-borne path is not expected to be significant as a large proportion of
this sound 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 ([31]).
Activities such as percussive piling have their highest energy at lower
frequencies from about 20Hz to 1kHz, and whilst smaller cetaceans (~ 3 - 4m in
length) are not known to be highly sensitive to sounds below 1kHz they can hear
in some of this range (peak range of 8 - 90 kHz reported for dolphins). Cetaceans are animals that rely on
acoustic information to communicate and to explore their environment. Therefore, sound that disrupts
communication or echolocation channels could have a potential impact. The reactions from impacted cetaceans
can range from brief interruption of normal activities to short- or long-term
displacement from noisy areas.
As noted previously, in line with
common local practice, the percussive piling equipment used in Hong Kong is
typically fitted with bubble jacket or bubble curtains to reduce underwater
sound. This feature of the
percussive piling equipment is beneficial in reducing underwater sound
propagation from the works site.
Bubble curtains have been reported to be effective at reducing
transmission of underwater sound generated during pile driving. A study ([32]) conducted during the construction of
the Aviation Fuel Receiving Facility on Sha Chau reported sound level reduction by 3 to 5 dB in the
overall broadband range. The
largest sound attenuation was between 1.6 to 6.4 KHz where a reduction of 15 to
20 dB was recorded ([33]) .
The size of the disturbed area will be
small in the context of the size of the range of these animals. With a bubble jacket/curtain in place to
reduce the generation of high-intensity impulsive sounds, and taking account
previous experience of reaction of marine mammals to marine works, underwater
sound associated with the piling works is not expected to give rise to
unacceptable adverse impacts. Any
effect of underwater sound caused by piling works would be limited to behavioural
disturbance impacts on affected dolphins, and there may be some avoidance of
the waters in close proximity to the works. These impacts are not likely to cause
biologically significant impacts on affected animals.
9.7.2
Operation
Phase
Vessel Traffic
Tugs will be used to manoeuvre the LNG
carrier to until moored along side the jetty. Owing to the slow approach speed and
slow manoeuvring of the LNG carrier under tug control, it is not expected that
there would be a significant risk of carrier/ tug collision (boat strike) with
dolphins. Consequently, operational
phase vessel traffic is not expected to cause unacceptable risk of impacts to
this species.
9.8
Evaluation of The Impacts to Marine Mammals
The following section discusses and
evaluates the impacts to marine mammals identified in the previous
section. Based upon the information
presented above, the significance of the marine ecological impact associated
with the construction and operation of the LNG terminal has been evaluated in
accordance with the EIAO-TM (Annex 8,
Table 1) as follows.
·
Habitat
Quality:
o Reclamation
Area: The reclamation
works will affect approximately 16 ha of marine waters at Black Point where
analysis of sightings data indicates medium densities of Indo-Pacific Humpback
Dolphins may occur. These waters,
which are marine mammal habitat of medium ecological importance, represent a
small 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 disturbed by high volumes of vessel traffic.
o Approach
Channel and Turning Circle:
The approach channel and turning circle are located off Black Point an area
where Indo-Pacific Humpback Dolphins occur at medium density. Significant impacts due to the dredging
works are not predicted to occur to these species, as water quality
perturbations are predicted to be transient, localised and generally compliant
with the WQO.
o LNG
Receiving Jetty:
The jetty is located at Black Point in an area where medium density of
Indo-Pacific Humpback Dolphins was found to occur.
o Operational
Phase Discharges:
The outfall is located in an area where sightings of Indo-Pacific
Humpback Dolphin are generally low.
·
Species:
Organisms of ecological interest reported
from the literature and field surveys 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 are expected during marine piling works, as construction methodologies
have been designed to reduce underwater sound transmission. Operational phase discharges from the
terminal or marine vessel movements are not expected to impact marine mammals
present in the area of the LNG terminal.
·
Size:
The reclamation works will affect
approximately 16 ha of marine waters where medium levels of Indo-Pacific
Humpback Dolphin density have been recorded. The marine waters have been disturbed
through reclamation in the past and are not considered to represent key habitat
for dolphins. The loss of 16 ha of
marine waters would be an unavoidable consequence of the proposed project since
the reclamation engineering required for the LNG terminal has been reduced in
size to the greatest extent practicable.
·
Duration:
The reclamation works are predicted to
last for 7 - 8 months and the dredging for the turning basin and approach
channel approximately 7 - 8 months.
Increases in SS levels in the vicinity of sensitive receivers are
expected to be low and temporary, and within environmentally acceptable
limits. The duration for the percussive
piling will last for 4 months. The
underwater sound impact is unlikely to adversely affect dolphins. Operational phase discharges will
continue during the life of the LNG terminal but are not predicted to cause
adverse impacts to marine ecological resources as the discharges disperse
rapidly and only affect an area close to the LNG jetty where low sightings of
dolphins occur.
·
Reversibility: The only permanent impacts at Black
Point to dolphins are likely to be from the reclamation works which will affect
approximately 16 ha of marine waters where Indo-pacific Humpback Dolphin have
been recorded in medium densities.
·
Magnitude: No unacceptable impacts to affected
individual dolphins have been predicted to occur. Although the reclamation is
16 ha in size, it represents a small portion of available dolphin habitat. Also although analysis shows medium
densities of dolphins occur off Black Point, this area would not be regarded as
key dolphin habitat in particular due to considerable disturbance caused by
heavy marine traffic. Operational
phase impacts are not expected to cause significant adverse impacts and are
considered to be of low magnitude.
The impact assessment presented above
indicates that with appropriate mitigation and precautionary measures, no
biologically significant impacts to individual marine mammals whose home ranges
overlap with the proposed project area are expected to occur. Nevertheless, the 16 ha reclamation will
cause permanent and irreversible loss of marine mammal habitat of medium
ecological importance.
Impacts to marine mammals during
operation of the terminal are predicted to be within environmentally acceptable
levels through appropriate design of the seawater outfall (as discussed in Part 3 Section 6 - Water Quality).
9.9
Summary of Mitigation Measures
9.9.1
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 (eg dredging 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 have
largely been avoided during the
construction and operation of the Black Point terminal, particularly to the key
ecological sensitive receivers (marine mammals), through the following
measures:
·
Avoid
Direct Impacts to Ecologically Sensitive Habitats: The site for the Black Point has been
selected based on a review of alternative locations (Part 1, Section 5) and avoided the key habitats for Indo-Pacific
Humpback Dolphin (including Sha Chau
and Lung Kwu Chau Marine
Park, Peaked Hill Island, West Lantau) and areas of
high marine mammal sighting density.
The location of the LNG terminal at Black Point has a medium sighting
density of marine mammals.
·
Avoid
Indirect Impacts to Ecologically Sensitive Habitats: The site for the Black Point has been
selected so dispersion of sediment from dredging and sand filling does not
affect the receivers at levels of concern.
·
Adoption
of Acceptable Working Rates:
The modelling work has demonstrated that the selected working rates for
the dredging will not cause unacceptable impacts to the receiving water
quality. Consequently, unacceptable
indirect impacts to marine ecological resources have been avoided.
9.9.2
General
Measures for Marine Ecological Resources
The
following measures to mitigate the impact of the construction and operation of
the on marine ecological resources are recommended:
·
The vessel
operators will be required to control and manage all effluent from
vessels;
·
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 section (Part 3 Section 6).
9.9.3
Specific
Measures for Marine Mammals
Measures to mitigate the impact of the construction and
operation of the terminal 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 dolphins.
·
All vessel operators working on the
Project construction or operation will 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
will be required to slow to 10 knots when passing through a high density
dolphin area (west Lantau, Sha
Chau and Lung Kwu Chau) 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 subjected to undue
disturbance or harassed;
·
The vessel operators 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;
Periodic
re-assessment of mitigation measures for marine mammals and their effectiveness
will be undertaken.
9.10
Additional (Precautionary) Measures for Marine
Mammals
In accordance
with the requirements of Clause 3.7.5.5 (vii) of the Study Brief, precautionary
measures have been identified to assist the protection of marine mammals. During piling works for the jetty
construction, the following additional measures will be adopted:
· To reduce underwater sound levels associated with percussive piling, the
following steps will be taken:
-
Quieter hydraulic hammers should be used instead of the noisier diesel
hammers;
-
Acoustic decoupling of noisy
equipment on work barges should be undertaken.
· Additional practices are recommended during percussive piling including:
- Instigate ‘ramping-up’ of
the piling hammer to gradually increase the level of underwater sound
generation;
-
Activities will be continuous without short-breaks and avoiding sudden
random loud sound emissions.
·
An exclusion zone of 500 m
radius will be scanned around the work area for at least 30 minutes prior to
the start of piling from the barge or an elevated observation point on land. If cetaceans are observed in the
exclusion zone, piling will be delayed until they have left the area. This measure will ensure the area in the
vicinity of the piling is clear of marine mammals prior to the commencement of
works and will serve to reduce any disturbance to marine mammals;
·
When dolphins are spotted
by qualified personnel within the exclusion zone, construction works will cease
and will not resume until the observer confirms that the zone has been
continuously clear of dolphins/ porpoises for a period of 30 minutes. This measure will ensure the area in the
vicinity of the piling is clear of marine mammals during works and will serve
to reduce any disturbance to marine mammals;
·
Consistent with standard Hong Kong practice, the percussive pile driving
will be conducted during the day time for a maximum of 12 hours, avoiding
generation of underwater sounds at night time.
·
Percussive pile driving will not be conducted during the peak calving
season of the Indo-Pacific Humpback dolphin, ie March
through August.
After
discussion with project stakeholders including the Government of the Hong Kong
SAR on potential additional construction restrictions, during the dredging
works for the project, the following additional measures will be adopted:
·
A marine mammal exclusion
zone within a radius of 250 m from dredgers 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. If cetaceans are observed in the
exclusion zone, dredging will be delayed until they have left the area. This measure will ensure the area in the
vicinity of the dredging 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 area during dredging, it is considered that cetaceans will have
acclimatised themselves to the works therefore cessation of dredging is not
required ([34]).
·
Dredging for the Approach
Channel and Turning Circle will be scheduled so it does not occur during the
peak calving period for the Indo-Pacific Humpback dolphin at Black Point (March
through August).
9.11
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 600 m of
natural rocky shore and approximately 120 m of artificial shoreline which are
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 1.1 km of sloping rubble
mound/rock or concrete armour seawalls that have been demonstrated to become recolonised by assemblages of a similar nature after
construction;
·
The loss of approximately 600 m of subtidal hard surface habitats which are of low ecological
value. The residual impact is
considered to be acceptable as the loss of these habitats is compensated by the
provision of seawalls (providing approximately 1.1 km of habitat) that have
been demonstrated to become recolonised by
assemblages of a similar nature after construction; and
·
The loss of approximately 16 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
relatively small in size in the context of surrounding similar habitat.
·
The loss of approximately 16 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 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.
Even though medium densities of dolphins may occur in these waters, the
habitat which would be lost would not be considered key marine mammal habitat
in particular due to considerable disturbance by heavy marine traffic.
·
Maintenance dredging of small specific
areas of the approach channel and turning is expected to be required once every
4 - 5 years. Since impact to water
quality is expected to be compliant with current WQO standards (refer to Part 3 Section 6.7.2), the residual impact associated with maintenance
dredging is considered to be acceptable.
The
cumulative impacts of the various project specific construction activities have
been demonstrated in Part 3 Section 6 – Water Quality as not causing
unacceptable impacts to water quality.
Consequently, unacceptable cumulative impacts to marine ecological
resources are not predicted to occur.
No operational phase cumulative impacts are predicted as there are no
ongoing projects in the immediate vicinity of Black Point.
Since
there is no publicly available information on the Hong Kong Macau Zhuhai bridge project, an assessment of cumulative impacts
related to this project cannot be currently undertaken.
9.13
Environmental Monitoring and 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 LNG terminal at Black Point.
Full details are presented in the separate EM&A Manual.
9.13.1
Construction
Phase
During
the construction phase, the following EM&A measures will be undertaken to verify
the predictions in the EIA 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 Part 3 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 in waters surrounding any marine
percussive piling works during construction of the LNG jetty as described in Part 3 Section 9.10. Through
implementation of the recommended EM&A measures, unacceptable impacts on
marine mammals will be avoided.
Details
of the marine mammal exclusion zone monitoring components are presented in full
in the EM&A Manual.
9.13.2
Operation
Phase
The
assessment presented above as indicated that operational phase impacts are not
expected to occur to marine ecological resources. The maintenance dredging of the approach
channel and turning circle is expected to take place once every 4 – 5
years. This dredging would result
in minor direct impacts due to temporary loss of small areas of low ecological
value subtidal soft bottom habitat. Indirect impacts associated with water
quality impacts due to maintenance dredging are not expected to be small scale
and localised to the works area and would cause exceedance
of current Water Quality Objective standards (refer to Part 3 Section 6.7.2 for
details). As a consequence, impacts on marine ecology are not expected.
No
marine ecology specific operational phase monitoring is considered necessary.
The
proposed Black Point terminal was studied in detail through a site selection
study in order to select a preferred site that avoided to the extent practical,
adverse impacts to habitats or species of high ecological value. The marine ecological sensitive
receivers include Sha Chau
and Lung Kwu Chau Marine
Park and the Indo-Pacific Humpback Dolphin (Sousa
chinensis).
Potential
construction phase impacts to marine ecological resources, as well as impacts
to marine mammals, may arise from the permanent loss of habitat due to
reclamation, disturbances to benthic habitats in the turning basin and approach
channel, or through changes to key water quality parameters, as a result of the
dredging and reclamation. As
impacts arising from the proposed dredging 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 large exceedances of the WQO, adverse impacts to water quality,
and hence marine ecological resources or marine mammals, are not
anticipated.
Although
the loss of 16 ha of marine mammal habitat 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
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.
Even though medium densities of dolphins may occur in these waters, the
habitat which would be lost would not be considered key marine mammal habitat
in particular due to considerable disturbance by heavy marine traffic.
Operational
phase adverse impacts to marine ecological resources are not expected to
occur. Unacceptable impacts from
discharges of cooled water and antifoulants are not
anticipated to occur as the effects from these discharges will be localised to
the direct vicinity of the outfall.
Construction
methods and specific mitigation measures that will be adopted include the
provision of rubble mound/armour rock seawalls on the edges of the reclamations
to facilitate colonisation by intertidal and subtidal organisms.
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
mitigate impacts to water quality to acceptable levels (compliance with WQOs) are also expected to mitigate impacts to marine
ecological resources.
Additional
(precautionary) measures have been identified for marine works taking place in
areas where marine mammals are sighted and these include monitored exclusion
zones during marine percussive piling work for the construction of the jetty. In line with common local practice in
Hong Kong, percussive piling works in the marine environment will be conducted
inside bubble jackets, so as to ameliorate underwater sound level transmission.