1
Environmental Assessment
An evaluation of the potential impacts
identified in Part 2 – Section 2.1 as
a result of the construction and operation of each of the South Soko terminal options has been undertaken to determine the
key issues. The importance (ie significance) of potential impacts has been evaluated
using the concepts described within the aforementioned section. The result of this evaluation is
presented below. From these
results, a comparison of each preliminary layout (the Layout) and design option
is presented based on the number of important or significant issues.
1.1
Accidental
Spills/Leaks/Dropped Objects
LNG receiving terminals have an excellent
safety record, accidental events such as spills and leaks, vessel grounding/
collisions, dropped objects and loss of materials either on land or into the
sea during construction or operation of the LNG terminal are potential
scenarios which may result in adverse impacts on the environment and personnel
injury.
The severity of impacts as a result of
accidental events will depend on a number of factors including the nature of
the event (ie type of hazard – hazardous material
release, physical impact etc.), the magnitude of the event (eg
quantities of material actually released) as well as the sensitivity of the
environment at the accident location/ impact site.
Whilst the consequences (ie scale of damage) resulting from accidental events may be
severe, the likelihood of their occurrence is typically unlikely to very
unlikely. However, this resultant
low level of risk associated with such events is traditionally only achieved by
the application of the highest standards of HSE management including hazard
identification, risk assessment and the implementation of extensive control and
recovery measures. Nevertheless,
regardless of the layout and design each option is considered to have a
negligible impact due to the unlikely event of such an event occurring.
The evaluation of impacts as a result of
accidental spills/leaks/dropped objects for each of the South Soko terminal layout options are presented in Table 1.1.
Table 1.1 Evaluation
of Impacts for Accidental Spills/Leaks/Dropped Objects
Air quality impacts may potentially arise
through the following:
·
Construction
vehicle/equipment/ vessels engine exhaust emissions (eg.
primarily NOx, CO, NMHC (non methane hydrocarbon) and
small quantities of SO2, particulates and smoke);
·
Construction
emissions from concrete batching plant; and,
·
Operational
emissions from SCVs, LNG carrier generators during
unloading of LNG, gas-turbine generators, onsite vehicles, emergency
generators, diesel-driven firewater pumps and the hydrocarbon emissions from
emergency venting (e.g., NOx, CO, SO2 and
HC).
Due to the relatively remote location of the South Soko terminal and the implementation of good site practice
and the control measures stipulated in the Air
Pollution Control (Construction Dust) Regulation, the adverse air quality
impact arising from the above potential sources during construction phase is
not expected.
Associated impacts are therefore
considered to be negligible for all options. Emissions associated with the concrete
batching plant to be located during construction works may, however, result in
low impacts to air quality, regardless of layout design. Similarly, as each layout would require
the installation of provisions for emergency venting of gas, potentially low
impacts to air quality may result during operations. Impacts to air quality may also affect
visibility, hence aesthetics, albeit likely to be of negligible impact for all
layout options.
The evaluation of impacts to air emissions
for each of the South Soko terminal layout options
are presented in Table 1.2.
Table 1.2 Evaluation
of Impacts for Air Emissions
Potential sources of impact through
run-off during the construction and operation of the LNG terminal may include:
·
Rainfall
run-off from disturbed site areas/ construction material stockpiles; and,
·
Entrainment
of debris and refuse in stormwater run-off resulting
in the fouling of receiving water resources.
Runoff and drainage from the earthworks
and construction areas may contain elevated sediment loads resulting in
increased turbidity in the surrounding waters. Such increases may subsequently affect
marine organisms that inhabit these waters. Run-off may also contain debris (litter)
as well as other contaminants (eg oil, grease, fuels
etc) unless effectively controlled on-site.
It is considered that although control
measures will likely be enforced to reduce surface run-off in each of the
layout options, environmental impacts to resources/receptors would range from
negligible (ie aesthetics) to those which may be
considered to be of low impact (ie water quality, intertidal/ subtidal habitats,
etc) due to the ecological value of these sensitive receivers. Such impacts would be unlikely to
differentiate between layout design during either construction or operation of
the LNG terminal.
The evaluation of impacts from run-off for
each of the South Soko terminal layout options are
presented in Table 1.3.
Table 1.3 Evaluation
of Impacts for Run-off
Potential sources of impact through
blasting works during the construction of the LNG terminal may include:
·
Acute
increases in environmental noise and subsequent impacts to biological and human
sensitive receivers within proximity to works; and
·
Exposure
to hazardous substances with subsequent concerns to health and safety.
Each of the three layout options will
involve the use of explosive materials to conduct blasting operations during
the excavation of rock from the existing hillsides. Regardless of the volume of blasting to
be required, magazine storage and explosive manufacturing plant will be
temporarily located on site. The
storage and use of such materials have the potential to result in adverse
impacts through direct exposure to blast materials, ie
habitat and terrestrial flora and fauna, and indirect impacts through increased
noise, vibration and noise.
Although underwater blasting is not necessary for the construction of
any of the potential layouts, it can be expected that terrestrial works may
have adverse consequences on marine habitats and organisms, albeit likely to be
of negligible consequence. Due to
the requirement for such works at all sites, impacts are considered to be of a
similar severity between layout options.
The evaluation of impacts associated with
blasting during construction for each of the South Soko
terminal layout options are presented in Table
1.4.
Table 1.4 Evaluation
of Impacts for Blasting
1.5
Discharges to Soil/
Groundwater
Potential sources of soil and groundwater
contamination associated with the construction and operation of the LNG
terminal may include:
·
Inappropriate
storage/ handling and disposal of waste materials;
·
Accidental
spills and leaks of environmentally hazardous materials (oils, cleaning
residues, hazardous materials etc); and
·
Inappropriate
management and control of on-site operations (including effluents, fuel and
hazardous material storage and use etc).
Minor spills during re-fuelling, lube/
hydraulic oil, oil filter etc. change-outs from construction equipment (eg generator sets) and vehicles have the potential to
result in localised contamination.
A leak from a temporary fuel storage tank has the potential to cause
significant soil and groundwater contamination. Risks of soil and groundwater
contamination can be controlled via effective operational and hardware control
measures. Providing such measures
are identified and are implemented in an effective manner, risks of
contamination can be maintained to within acceptable levels. For the purposes of this consideration
of alternatives, it has been determined that each layout would have the
potential to result in similar environmental impacts to resources/receptors, regardless
of configuration or design.
The evaluation of impacts associated with
discharges to soil/groundwater for each of the South Soko
terminal layout options are presented in Table
1.5.
Table 1.5 Evaluation
of Impacts for Discharges to Soil/Groundwater
1.6
Effluents
(Cleaning/Recycling/Disposal)
Potential impacts to resources/receptors
through effluent (cleaning/recycling/disposal) associated with the construction
and operation of the LNG terminal may include:
·
Wastewater
from typical construction activities (eg. concreting,
dredged spoil storage/ removal, painting etc);
·
Sanitary
effluents from temporary chemical toilets for construction workers’ day use;
and
·
Routine
disposal of operational effluents (ie ‘black water’
composed of human body wastes from toilets and urinals and ‘grey water’ from
showers, sinks, laundries, kitchens etc) from operational staff.
In order to clean/recycle/dispose of
effluents generated through the construction and operation of the LNG terminal
it is expected that a small-scale package, such as a Blivet
Sewage Treatment Works or RBC plant, will be installed during both phases of
works. Treated construction phase
effluent will be discharge through a temporary outfall.
During the operational phases, effluent is
expected to be treated and disposed offshore via a combined sewage and cooled
water discharge outfall. Although
all effluent will be treated to meet the required discharge standards prior to
mixing within the outfall, the potential for impacts to the surrounding water
body and consequently the marine flora and fauna located within it, would be
expected to have the potential to undergo an increase in impact likelihood. Such impacts would, however, be expected
to be of limited time duration and low severity.
For the purposes of this consideration of
alternatives, it has been determined that each layout would have the potential
to result in similar environmental impacts to resources/receptors as a result
of effluent generation and discharge, regardless of configuration or design.
The evaluation of impacts from effluents
(cleaning/recycling/disposal) for each of the South Soko
terminal layout options are presented in Table
1.6.
Table 1.6 Evaluation
of Impacts for Effluents (Cleaning/Recycling/Disposal)
Excavation will be required for each
layout option as part of the construction of the South Soko
terminal for the following reasons:
·
To
enable the tanks to be founded directly onto rock which will permit the use of
pad/raft foundations, thus negating the need for deep foundations; and
·
To
screen the tanks from the visually sensitive receivers on the south side of Lantau island.
Impacts associated with the excavation of
material associated with the construction will primarily occur through dust
generated from excavation activities, increase in terrestrial noise and visual
and aesthetic impacts through alteration of the existing landscape. In addition, due to the identification
of sites of archaeological interest and cultural resources within the areas
required to be excavated, impacts to such will occur.
On the basis of the designs of each
layout, Options 1 and 3 will require the excavation of approximately 2.1 Mm3 and 2.3 Mm3, respectively, of soil and rock. In contrast, Option 2 will only require
the excavation of approximately 1.3 Mm3 of soil and rock. As the location of the removal of
material is relatively similar, ie either the
northern or southern hill slopes, or both, it would be fair to assume that the
differences in excavated material requirements would have similar differences
in the potential for impacts to occur.
As such, Option 2 is considered to have less severity of impact than
Options 1 and 3.
The evaluation of impacts from excavation
for each of the South Soko terminal layout options
are presented in Table 1.7.
Table 1.7 Evaluation
of Impacts for Excavation
Vessel anchoring (anchor deployment and
recovery) within the vicinity of the construction site will result in localised
seabed sediment/ substrate disturbance and alterations to the seabed
profile. Anchor operations may also
result in secondary impacts on water quality (local increases in turbidity) and
harm to the subtidal marine fauna living in the
seabed. It is likely that any
impacts that may occur would be more severe during construction operations when
there will be increased marine traffic to the site and the higher likelihood of
anchoring occurring. Impacts,
however, would be expected to be similar between options regardless of layout
design.
The evaluation of impacts from marine
anchoring for each of the South Soko terminal layout
options are presented in Table 1.8.
Table 1.8 Evaluation
of Impacts for Marine Anchoring
1.9
Marine Dredging and Disposal
Marine dredging operations during construction
may release sediment into suspension within the surrounding waters by the
following mechanisms:
·
Impact
of the dredging equipment (eg grab, trailer arm) on
the seabed as it is lowered;
·
Washing
of sediment off the outside of the grab as it is raised through the water
column and when it is lowered again after being emptied;
·
Leakage
of water from the grab as it is hauled above the water surface;
·
Spillage
of sediment from over-full grabs;
·
Loss
from grabs which cannot be fully closed due to the presence of debris;
·
Release
by splashing when loading barges by careless, inaccurate methods;
·
Disturbance
of the seabed as the closed grab is removed, which may be exacerbated by the
release of gas (if present) from the disturbed sediments;
·
During
the transport of dredging materials, sediment may be lost through leakage from
barges;
·
Changes
in hydrodynamics due to changes in bathymetry; and,
·
Aesthetic
impacts through generation of sediment plumes.
The disposal of this dredged spoil
material has the potential to result in a range of direct and indirect adverse
impacts including:
·
Water
column impact (elevated suspended solids levels during spoil discharge);
·
Indirect
effects on marine ecology due to degraded water quality;
·
Alteration
of seabed sediments (accumulation of dredged material);
·
Smothering
effects on benthic (seabed) ecology;
·
Indirect
effects on fisheries due to both degraded water quality as well as seabed
deposition of spoil; and,
·
Aesthetic
impacts through generation of sediment plumes.
According to the engineering design of the
three layouts for the South Soko terminal one of the
major differences appears to be in the dredging and subsequent disposal
requirements of marine sediments.
Both Option 1 – Base Case and Option 2 – Full Reclamation have been
estimated to require approximately 3.36 Mm3 of marine sediments to be removed in
order to dredge the approach channel and turning basin to the required depth
for safe LNG carrier passage (-15mPD).
In contrast, Layout 3 – SE Jetty will only require 1.07Mm3 of marine sediments to be removed.
The primary difference is the approach
channel and turning circle for this layout has been designed to only come into
the southeastern side of South Soko
Island, which is in contrast to Options 1 and 2 where the channel
circumnavigates the southern, eastern and northern sides of the island before
ending at the northwest near Sai Wan Bay.
The increased dredging requirements of
Options 1 and 2 will have subsequent increases in potentially adverse
consequences to resources and receptors, such as those to water quality, marine
habitats (both intertidal and subtidal),
marine mammals, as well as fisheries resources and operations. These differences have been reflected in
the impact severity and likelihood assessments.
The evaluation of impacts from marine
dredging and disposal for each of the South Soko
terminal layout options are presented in Table
1.9.
Table 1.9 Evaluation
of Impacts for Marine Dredging and Disposal
Construction will generate additional
marine traffic within and into the study area. Marine vessel traffic generated by the
project will include vessels for dredging, construction barges, delivery of equipment, materials and supplies and removal of
marine dredged material. These
additional construction vessel movements have the potential to cause:
·
Increased
marine accidents;
·
Interference
with vessels approaching, departing and moored in the immediate surroundings;
·
Interference
with other marine vessels, eg recreational, fishing
vessels etc.;
·
Increase
in terrestrial and underwater noise; and
·
Increase
in likelihood for collision with marine mammals.
For the purposes of this consideration of
alternatives, it has been determined that each layout would have the potential
to result in similar environmental impacts to resources/receptors as a result
of marine traffic, regardless of configuration or design.
The evaluation of impacts from marine
traffic for each of the South Soko terminal layout
options are presented in Table 1.10.
Table 1.10 Evaluation
of Impacts for Marine Traffic
The principal sources of noise during
construction activities will include:
·
Piling
(hydraulic hammer type piling rig);
·
Blasting
(explosives);
·
General
construction equipment (eg. compressors, cranes,
generators sets etc.) and activities (hammering, cutting, grinding, welding
etc.); and
·
Transport
vehicles (cars and trucks)/construction vessels.
It is assumed that the equipment to be
employed during the construction of the site would be similar regardless of
which layout design would be constructed.
Operational noise associated with the terminal is not expected to be
severe.
For the purposes of this consideration of
alternatives, it has been determined that each layout would have the potential
to result in similar environmental impacts to resources/receptors as a result
of noise, regardless of configuration or design.
Note that potential ecological impacts and
impacts on fisheries associated with underwater noise generated during piling
works are included in Section 1.12 below.
The evaluation of impacts from noise for
each of the South Soko terminal layout options are
presented in Table 1.11.
Table 1.11 Evaluation
of Impacts for Noise
Piling will cause vibration in the
surrounding seabed/ ground. Driving
of piles in water will generate a certain amount of underwater sound. Other underwater sound generation will
occur from additional marine construction activity, such as dredging as well as
support vessel operations.
Excessive underwater sound generation has
the potential to disturb marine life (eg. fish,
turtles, mammals etc.). Marine
mammals rely on acoustic information to communicate and to explore their
environment. Therefore, it is
desirable to attenuate any sound generated that has the potential to
significantly disrupt communication or echolocation activities of marine
mammals near construction activities.
Piling operations will be required for all
layouts in order to construct the jetty and trestle for the LNG carrier. Layout Options 1 and 2 of the South Soko terminal would require the jetty to be constructed in
the northeastern Sai Wan
Bay of South Soko Island, whereas, Option 3 will have
the jetty located on the southeastern side of the
island.
Long-term monitoring of marine mammal abundance
and distribution in these waters (Part 2
– Section 10) indicates that marine mammal sightings in the general area of
South Soko were infrequent, with more sightings in
the waters in the vicinity of Options 1 and 2, compared with waters surrounding
the jetty in Option 3. Given the
low density of marine mammals near to proposed piling activity, the potential
for adverse impacts to occur to marine mammals as a result of marine piling
operations is lowest for Option 3.
The evaluation of impacts from piling
activities for each of the South Soko terminal layout
options are presented in Table 1.12.
Table 1.12 Evaluation
of Impacts for Piling
The engineering design of Option 2 – Full Reclamation
will require the reclamation of approximately 13 hectares (ha) of existing
marine habitats. The majority of
reclamation will occur to the west of the existing platform to house the
proposed turbine substation, utility area and laydown
area. The area to the east of the
platform will be used for the service berth.
In comparison, both Options 1 and 2, Base
Case and SE Jetty respectively, will require only approximately 1.7 ha of
marine habitats to be reclaimed.
This will primarily be needed for the utility pier on the west of the
platform (or for Tank 3 for the SE Jetty layout) and to the east for the
service berth.
The differences in reclamation area will
result in subsequent increases in potential impacts to resources and receptors,
such as those to water quality, marine habitats (both intertidal
and subtidal), marine mammals, fisheries resources
and operations as well as visual and aesthetics. These differences have been reflected in
the impact severity and likelihood assessments.
The evaluation of impacts from reclamation
for each of the South Soko terminal layout options
are presented in Table 1.13.
Table 1.13 Evaluation
of Impacts for Reclamation
Site formation works at each option will
involve the consideration of the volume of excavated materials, the potential
for afteruse, slope stabilisation and
maintenance. It is noted that
volumes of excavated material and afteruse are
considered under excavation and waste generation and disposal, therefore for
the purposes of assessing the environmental consequences of site formation the
focus has been to identify any key differences between overall site formation,
stabilisation and maintenance.
Each of the three layout options will be
prepared, excavated and stabilised in similar formats (see Section 1.7 above). As
such, it is expected that the differences between the three layouts will not be
significant enough to differentiate between in terms of environmental
impacts. Similar impacts to waste
generation and disposal as well as landscape, aesthetics and archaeological
resources may then be expected to occur for each layout. Thus, for the purposes of this
consideration of alternatives, it has been determined that each layout would
have the potential to result in similar environmental impacts to
resources/receptors as a result of site formation , regardless of configuration
or design.
The evaluation of impacts from site
formation for each of the South Soko terminal layout
options are presented in Table 1.14.
Table 1.14 Evaluation
of Impacts for Site Formation
1.15
Waste Generation and
Disposal
All options will require the excavation of
rock from the existing hillsides in order to provide sufficient flat land to
meet the functional requirements of the LNG terminal. However, as the Option 2 layout design
will involve the construction of a comparatively large area of reclamation, it
has been estimated that all excavated material under this design will be able
to be reused in the reclamation. In
addition, it is expected that up to 1,261,000 m3 of fill will need to be imported,
possibly from existing construction and demolition (C&D) waste storage facilities. Hong Kong is currently storing surplus
C&D material, thus the necessity to import such material would be
considered to be a positive impact for the Option 2 layout.
In contrast to Option 2, the design of
Options 1 and 3, the Base Case and SE Jetty, respectively, will result in a
surplus of approximately 0.04 and 0.12 Mm3 of soil following excavation and
construction works. This material
will be exported to allocated waste disposal facilities and would be considered
as a potentially high impact to such facilities.
The evaluation of impacts waste generation
and disposal for each of the South Soko terminal
layout options are presented in Table
1.15.
Table 1.15 Evaluation
of Impacts for Waste Generation and Disposal
During the operation of the LNG terminal
discharges will include cooled water, as seawater will be used for warming the
LNG in the Open Rack Vaporizers.
For operational reasons, the discharges will likely contain antifoulants.
Although all discharges will be designed to comply with the Water Pollution Control Ordinance Technical
Memorandum on Standards for Effluents Discharged into Drainage and Sewerage
Systems, Inland and Coastal Waters, impact(s) to marine ecological and
fisheries habitats within the surrounding waters needs to be assessed and
managed.
For the purposes of this consideration of
alternatives, it has been determined that each layout would have the potential
to result in similar environmental impacts to resources/receptors as a result
of antifoulant discharge, regardless of configuration
or design.
The evaluation of impacts from antifoulants for each of the South Soko
terminal layout options are presented in Table
1.16.
Table 1.16 Evaluation
of Impacts for Antifoulants
As mentioned above, the operation of the
terminal is expected to involve the intake of seawater into open rack
vaporisers and the discharge of cooled seawater. The volume of seawater intake and the
cooled seawater in the effluent has the potential to impact marine ecological
and fisheries habitats in the surrounding waters through a localised reduction
in water temperature.
As with antifoulants,
for the purposes of this consideration of alternatives, it has been determined
that each layout would have the potential to result in similar environmental
impacts to resources/receptors as a result cooled water discharge, regardless
of configuration or design.
The evaluation of impacts from cooled
water discharge for each of the South Soko terminal
layout options are presented in Table
1.17.
Table 1.17 Evaluation
of Impacts for Cooled Water Discharge
The construction of the reclamation, jetty
and dredged areas will result in localised alterations in the water flows (both
in terms of velocity and direction).
Altered water flows have the potential to result in secondary effects on
the sedimentary regime in the vicinity of the site; increased or changed water
flow patterns have the potential to result in localised scour (ie. resuspension) of seabed
sediments. Conversely the creation
of areas of calmer or lower velocity water flows have the potential to result
in increased sedimentation effects.
The reclamation requirements for layout
Option 2, Full Reclamation, may be expected to potentially change the
hydrodynamics in the surrounding waters.
Impacts as a result of these changes may occur to water quality, marine
ecological and fisheries sensitive receivers. In addition, the extended footprint of
the site would likely increase the exposure to visual sensitive receivers, such
as those on Lantau Island. Such operational impacts are considered
to be a disadvantage of this layout in comparison to the others under
investigation.
The evaluation of impacts from the layout
characteristics for each of the South Soko terminal
layout options are presented in Table
1.18.
Table 1.18 Evaluation
of Impacts for Layout Characteristics
