This Section presents a summary of the key
conclusions of this EIA associated with the construction and operation of the
proposed offshore wind farm. The
purpose of the assessment was to thoroughly evaluate the offshore
wind farm and its components in
terms of predicted impacts to key environmental sensitive receivers and to determine
whether this option can meet the requirements of the EIAO-TM.
15.2
Consideration of
Alternatives
This EIA Study has examined a series of Alternatives
as follows:
·
Consideration
of Alternative Site Locations (Section 3);
and
·
Consideration
of Design Options and Construction Methods (Section
4);
15.2.1
Consideration of Alternative Site
Locations
15.2.2
Consideration of Different Layouts and
Design Options
An assessment of different design options and
construction methods was conducted to investigate not only the environmental
considerations of each option, but to include an examination of the engineering
feasibility. Options ranged from
alternative foundation design to siting of an offshore vs. onshore substation. Where appropriate, options were
discounted on environmental grounds. However, in general, a worse case
assessment approach has been taken forward to ensure a precautionary level of
assessment and to allow flexibility for future design changes during the
subsequent Detailed Design Phase. The
options have been considered consistently across all of the EIA chapters, which
address the requirements of the Study Brief (ESB-151/2006) and EIAO-TM.
The following provides a summary of
alternative design options and construction methods that have been considered.
Design Options
Wind Farm Layout: The preliminary layout has considered the
influence of site constraints and spacing requirements in order to avoid wake
loss across the wind farm. A
geometric design has been taken forward for the purpose of informing the
assessment as this would help to reduce visual impacts and navigational risk. The preliminary layout will, however,
potentially be subject to amendment during the Detailed Design Phase.
Wind Turbines: A range of turbines are available on the market
with various dimensions for height and rotor diameter. Preliminary dimensions are not expected
to exceed a tip height of +125mPD. In
the event the wind turbine model with a maximum rotor diameter of 111m be
adopted, the maximum tip height would be +136mPD. The turbines with greatest rotor diameter
have been used for the assessment as part of a precautionary assessment of
impacts. It is, however, possible that
a smaller rotor diameter could be used for the size of turbines being
considered as these are available on the market.
Foundation Design: Three types of wind turbine foundation design were considered. It was concluded that a piled foundation (monopile
or tripod pile) provided the best environmental and engineering option. However, monopiles (with rock scour
protection) are likely to occupy the larger seabed footprint and hence were
taken forward to the EIA stage in order to produce a more conservative
assessment of impacts.
Lighting and Marking: A number of options were considered and the
preferred option was identified in accordance with the requirements of the Civil
Aviation Department and Marine Department. The requirements for lighting and marking
are not expected to give rise to unacceptable adverse environmental impacts.
Substation: A sub-station will be required to
transform the voltage of the electricity generated at the wind turbine to a
high voltage suitable for transmission of power ashore. A base case of an offshore substation has
been taken forward for assessment; however, there may be an option for an
onshore substation subject to detailed engineering design.
Monitoring Mast: A wind monitoring mast will be required to
measure wind, wave and current information for operational purposes. The wind monitoring mast foundation is comprised
of 8 nos. of 1.6m diameter steel tubular piles fixed into seabed in which each
pile individually can be considered as a small monopile. The structure has an overall height of
80m AMSL and will consist of
a steel lattice tower supported on a piled
foundation. Anemometry equipment will be installed on
the lattice tower and wave and
current sensors installed on the seabed/foundation structure.
Construction Methods
Foundation Installation: Percussive piling techniques have been selected
as the most appropriate method of installation due to their proven mitigation
for environmental protection, no generation of wastes required for off-site
disposal, a proven industry method and a significantly reduced installation
schedule. The percussive piling
method for foundations of wind turbines and the wind monitoring mast has been taken forward for assessment in
this EIA Report.
Subsea Cable Installation: Grab dredging and jetting techniques have
been identified as being the preferred method for cable installation. The area of grab dredging is, however, restricted
to the nearshore area to the Lamma Power Station Extension to allow for cable
landing preparation works. This
restriction will assist in reducing the amount of sediment that needs dredging
and subsequent offsite disposal. It
is also deemed necessary to install cable protection as appropriate where the
proposed cable for the wind farm development crosses existing telecommunication
cables.
The potential impacts to water quality
caused by construction and operational activities of the offshore wind farm and
its components have been assessed in Section
6 of this EIA Report. The impacts have been identified and assessed to
be in compliance with the criteria and guidelines stated in the EIAO – TM Annexes 6 and 14 respectively.
Sensitive
receivers potentially affected by construction and operational activities of the
proposed wind farm development have been identified and the potential impacts
have been evaluated. The key
sensitive receivers include finless porpoise, green turtles, the Potential South
Lamma Marine Park, commercial fisheries spawning habitat, fish
culture zones, ecologically sensitive areas (horseshoe crab habitat and coral
communities), beaches (gazetted and non – gazetted) and sea water intakes. The assessment has included the
potential impacts caused by marine works (i.e. foundation construction, dredging
and jetting) on water quality due to the increases of suspended sediments
concentrations, potential decreases of dissolved oxygen and increases of
nutrient concentrations, as well as those caused by operational activities such
as the alteration of the hydrodynamic regime.
Computational
models have been used to simulate the variation in suspended
sediments concentration during the construction phase and the impacts due to change in currents resulting
from the presence of marine structures during the operation phase.
Potential impacts arising from the proposed
dredging works are predicted to be largely confined to the specific works area adjacent
to the Lamma Power Station Extension. Modelling results indicate that the SS elevations
as a result of grab dredging, jetting and foundation construction are expected to localised to the mixing zone and
largely compliant with the WQO and tolerance criterion at the
majority of sensitive receivers. The
exception is for isolated colonies of low value coral communities at the Lamma Power
Station Extension seawall where through the application of silt curtains during
dredging works no unacceptable impacts would be expected to occur. The predicted elevations of suspended
sediment concentrations during the construction phase are transient in nature
and not predicted to cause significant adverse impacts to water quality at the
sensitive receivers.
During the operation phase, unacceptable adverse
impacts to water quality are not expected to occur. Hydrodynamic modelling has shown that the
wind farm development will have negligible near-field and far-field impacts on
current flow and direction as well as flushing capacity at key channels in
Unacceptable
impacts to water quality sensitive receivers have been further avoided through
the adoption of mitigation measures including the siting of the proposed wind
farm and submarine cable away from many water quality sensitive receivers, the
selection of acceptable working rates for the marine works, construction
operational mitigations (i.e. dredging operational measures) and appropriate
on-site land based construction activities. No mitigation measures are required
during the operational phase.
The identified potential concurrent
projects that could lead to cumulative water quality impacts are the marine
dumping activities at the South Cheung Chau uncontaminated mud disposal site. Modelling carried out for this Project showed
that impacts of the wind farm and submarine cable construction activities are
very localised and transient. Sediment
does not disperse at appreciable concentrations beyond the works areas. A review of modelling of disposal activities
at the South Cheung Chau Disposal Ground shows that sediment plumes would not
reach the wind farm area and plumes would not overlap with those generated from
the jetting works, should they coincide. It is therefore anticipated that the works
proposed for this Project would not lead to potential for increasing the loading
of sediments within the wider marine environment that is associated with the
uncontaminated mud disposal ground. No significant cumulative impacts associated
with water quality are therefore expected.
Water
quality monitoring and auditing is recommended for the construction phase and
the specific monitoring requirements are detailed in the Environmental Monitoring and Audit Manual (EM&A Manual) associated with this EIA Report. As no unacceptable impacts have been
predicted to occur during the operation of the wind farm, monitoring of impacts
to marine water quality during the operational phase is not considered
necessary.
The potential impacts to waste management
caused by construction and operational activities of the offshore wind farm have
been assessed in Section 7 of this EIA Report. The impacts have been identified and assessed to
be in compliance with the criteria and guidelines stated in the EIAO – TM Annexes 7 and 15 respectively.
The key potential impacts during the
construction phase are related to waste generated from dredging, seawall removal,
site works at the laydown area and excavation/filling of onshore cable trenches.
The storage, handling, collection, transport,
disposal and/or re-utilisation of these materials and their associated
environmental impacts have been the primary focus of the assessment.
It is estimated that a total of
approximately 3,000 m3 of marine sediment will be dredged. These sediments are considered to be
uncontaminated and are suitable for Open Sea Disposal and this will be
confirmed during the detailed engineering design phase. Up to 2,145 m3
of existing seawall will be removed and reinstated as part of the works. All excavated material will be stored at the
Laydown Area and reused to reinstate the seawall. As such, it is not anticipated that any waste
will be generated.
Other wastes produced during the
construction phase are of small quantity and will be disposed of according to
their nature, avoiding potential adverse impacts. The potential environmental impacts associated
with the storage, handling, collection, transport and disposal of waste
produced during operational activities have been estimated to be insignificant and
will therefore meet the criteria specified in the EIAO-TM.
Unacceptable
impacts as a result of the waste produced during the construction phase have
been avoided through the adoption of specific mitigation measures and in particular through the establishment
and implementation of a Waste Management Plan (WMP).
In order to ensure that the construction
Contractor(s) has implemented the recommendations of the EIA Report, regular
site audits will be conducted of the waste streams, to determine if wastes are
being managed in accordance with the approved procedures and the site WMP.
The proposed wind farm was studied in detail through a
site selection study in order to select a site that avoided to the extent
practical, adverse impacts to important habitats for birds particularly
migratory birds or bird species of high ecological value.
A total of 14 identified species were recorded in the
Project Site including Aleutian Tern, Ancient Murrelet, Barn Swallow, Black Kite,
Black-headed Gull, Black-naped Tern, Black-tailed Gull, Bridled Tern, Common
Tern, Heuglin’s Gull, Little Tern, Red-necked Phalarope, Whiskered Tern and
White-winged Tern, two of which were considered bird species of conservation
interest (Black Kite and Ancient Murrelet). In addition, in the wider Study Area a
further three bird species
of conservation interest were recorded, including White-bellied Sea Eagle, Common Buzzard and Pacific Reef Egret. Most of the birds that are of
conservation interest are common and widespread in Hong Kong with the exception
of Pacific Reef Egret (uncommon but widespread resident),
Potential construction phase impacts to birds may
arise from the permanent loss of habitats due to the construction of wind
turbine foundation, substation and monitoring mast; temporary disturbance and
displacement of birds. The
relatively small scale loss of approximately 0.16 ha of open waters within the
Project Site is not expected to be significant for bird/migratory bird
populations in view of similar habitats in the vicinity and the limited bird
use in the area. The direct
ecological impact due to the construction of the wind turbine is expected to be
low, and will not contribute to any potential cumulative impact.
Barrier
effect to bird movement and bird collisions during the operation of the wind
farm were assessed. Aleutian Tern, Ancient Murrelet, Barn
Swallow, Black Kite, Black-headed Gull, Black-naped Tern, Black-tailed Gull,
Bridled Tern, Common Tern, Heuglin’s Gull, Little Tern, Red-necked Phalarope,
Whiskered Tern and White-winged Tern have utilised the Project Site and
therefore are the species that may be affected
by the operation of the wind farm. However,
these species were recorded in relatively low numbers and most of them were
flying over the area. Since the wind farm is not located within
important bird habitat or on the flight path of migratory birds, the potential
risk of bird collision will be low. In addition, collision risk assessment using the worse case scenario also predicted
low number of bird collision. Overall,
no adverse residual impacts
are envisaged.
A bird monitoring programme will be undertaken to
confirm that the construction and operation of the wind turbines will not cause
adverse impacts to birds. Monitoring
for bird abundance and distribution will be undertaken for one year during the pre-construction
phase, one year during the construction phase for the wind turbines and the
first year of the operation of the turbines.
Potential construction phase impacts to
marine ecological resources, as well as impacts to marine mammals and sea turtles,
may arise from the permanent loss of habitat in the footprint of marine structures,
disturbances to benthic habitats as a result of jetting and dredging and
impacts on intertidal and subtidal habitats during seawall removal.
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 exceedances of the water quality objectives outside of the
mixing zones, adverse impacts to water quality, and hence marine ecological
resources or marine mammals and green turtles, are not anticipated.
Although the loss of 0.16 ha of water
column 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, including the sizable ranges and mobility of
affected animals and the fact that the habitat that would be lost is not be
considered to be a critical habitat for marine mammal or sea turtles. The area is also subject to considerable disturbance
by heavy marine traffic and trawling by fishing vessels.
The loss of 3.6 ha of soft bottom seabed
habitat would also be an inevitable and adverse consequence of the project. However, this habitat is considered to be
of low conservation value and is not significant in context to the amount of
similar habitat available elsewhere in
The removal of low ecological value
artificial rocky shore as a result of seawall removal activities for cable
landing (see Section 5) will not lead
to unacceptable impacts for subtidal or intertidal ecology. The reinstatement of the seawall with
materials that have been removed will mean that there will be no long term
change in the amount of available artificial intertidal and subtidal hard
bottom habitat.
Percussive piling has the potential to
cause impacts to marine mammals, and to a lesser extent, sea turtles through
underwater sound generation. Impacts
to noise sensitive species from percussive piling operations associated with
wind turbine installations in offshore waters has been shown to be significantly
reduced by avoidance of works during peak seasons of finless porpoise, adopting
soft-starts procedures and strictly controlled exclusion zones. Through the adoption of such mitigation
for the proposed wind farm, i.e. marine mammal / sea turtle exclusion zones,
adoption of closed periods for piling works during peak marine mammal season
and noting that the wind farm site is away from
Operational phase adverse impacts to
marine ecological resources are not expected to occur. In particular, unacceptable impacts to
marine mammals and sea turtles from the generation of underwater sound levels
are not predicted to be of concern. In addition, the wind farm structures,
and in particular rock scour material may have the potential to create an
artificial reef, which could have beneficial impacts related to food supply for
marine mammals.
No unacceptable residual impacts are
predicted to marine ecological resources.
During the construction phase of wind
turbines, pre-, during and post-installation monitoring of marine mammal
abundance, behaviour and distribution, including vessel-based surveys, passive
acoustic monitoring and land-based theodolite tracking, will be undertaken. Periodic re-assessment of mitigation measures
for marine mammals and their effectiveness will also be undertaken during these
periods.
The potential impacts to commercial
fisheries caused by construction and operational activities of the proposed
offshore wind farm and its components have been assessed in Section 10 of this EIA Report. The impacts have
been identified and assessed to be in compliance with the criteria and
guidelines stated in the EIAO – TM Annexes 9 and 17 respectively.
Fisheries sensitive receivers have been
identified and the potential impacts arising from the construction and
operation phases of the offshore wind farm and its components have been
evaluated. Potential impacts to
fisheries resources and fishing operations may arise from the short term
disturbance of marine habitat due to foundation construction, dredging and
jetting or through changes to key water quality parameters, as a result of
marine works, underwater sound generation, and restriction of fishing activity
in proximity to the marine working areas. Water quality impacts arising from the proposed
dredging, jetting and foundation construction works are predicted to be largely
confined to the specific works areas and to be temporary in nature. The predicted elevations of suspended
sediment concentrations due to the Project are not predicted to exceed the
assessment criteria over large areas or at sensitive receivers and they are not
expected to cause significant adverse impacts to water quality or to any
fishing grounds or species of importance to the fishery. Restriction of access for fishing during construction
consists of a small area (500 m from works) and should not significantly affect
fisheries in the area in the context of similar or better fishing areas
elsewhere. In additional, increase
vessel traffic is small scale and should not pose a significant risk to fishing
vessels, particularly given the high levels of marine traffic that currently
exist in the area that fishing vessels contend with on a daily basis.
During the operation of the wind farm a
total of 700 ha of habitat will be lost to fisheries operations within and
adjacent to the turbine array. This
represents 0.42% of
Underwater
sound generation from marine construction and operation works is not expected to
have a significant impact on fisheries resources.
No fisheries-specific mitigation measures
are required during the construction or operation activities.
The water quality monitoring programme will provide management actions
and supplemental mitigation measures to be employed should impacts arise,
thereby ensuring the environmental acceptability of the Project. As impacts to the fisheries resources and
fishing operations are small and of short duration, the development and implementation
of a monitoring and audit programme specifically designed to assess the effects
on commercial fisheries resources is not deemed necessary. In addition, the adoption of appropriate mitigation
measures to manage navigational risks will also mean that the risk to fishing
vessels would be low.
A Fisheries Review and Consultation
Programme will also be implemented prior to the commencement of construction of
the wind turbines. The general
intention of the FRCP will be to outline, in consultation with the fishery
sector, whether there is scope for fishing operations to be conducted within
the development area. The FCRP will also aim to explore the
possibilities of additional measures/projects to be undertaken within the development
area for the enhancement of fisheries resources. If deemed acceptable, a Fisheries
Enhancement Plan (FNP) will be developed for the wind farm area.
15.8
Landscape and
Visual Impact
A Landscape and Visual Impact Assessment has been
undertaken for the South West Lamma site. The landscape impacts where identified
and some mitigation measures proposed. The residual landscape impacts are:
1.
There
will be negligible residual
construction impacts on LCAs 2 Inshore Waters Landscape and LCA 4 Coastal
Upland and Hillside Landscape.
2.
There
will be slight residual construction
impacts LCA 3 Industrial Urban Landscape. Approximately 2.78 ha of this LCA will be
affected during construction, however this area will be fully mitigated with
the adoption of the mitigation measures proposed.
3.
There
will be moderate adverse residual
construction impacts on LCA1 Offshore Waters Landscape. Approximately 700 ha of
this LCA will be lost and can not be mitigated.
4.
There
will be negligible residual
operational impacts on LCAs 2 Inshore Waters Landscape, 3 Industrial Urban
Landscape and 4 Coastal
5.
There
will be negligible residual
construction and operation impacts on the following LRs:
·
LR 2
Man made rocky sea-wall. Approximately 0.001 ha of this LR will be lost during
construction; however this will be fully mitigated with the adoption of the
mitigation measures proposed.
·
LR 3
Industrial Area. Approximately 0.02 ha of this LR will be lost during construction;
however this will be fully mitigated with the adoption of the mitigation
measures proposed.
·
LR 4
Soft Landscape areas. Approximately 0.001 ha of this LR will be lost during construction;
however this will be fully mitigated with the adoption of the mitigation
measures proposed.
·
LR 5
Mixed Shrubland. There will be no impacts on this LR.
·
LR 6
Pond. There will be no impacts on this LR.
6.
There
will be slight residual construction and operation impacts on LR1 Seascape as 0.16ha
will be lost and can not be mitigated.
A Visual Impact Assessment was undertaken with
several conservative assumptions:
1.
Whilst
the review of
2.
Based
on the analysis of the parameters of human vision, the more conservative limit of
view of 15.5 km has been adopted, and;
3.
Intervening
vegetation and buildings have not been considered during the identification of VSRs.
Nineteen VSRs were identified and assessed based on
their sensitivity and magnitude of change. Whilst visual mitigation of the wind
turbine structures is difficult, four VMM’s were proposed, however the ability
of these mitigation in reducing the significance threshold of the impacts is limited.
The residual impacts identified
were as follows:
1.
There
will be negligible residual visual
impacts from VSR3 Lamma Ferry Pier, VSR 14 Stanley Waterfront and VSR 15 Wong Nai
Chung Gap and Violet Hill.
2.
There
will be slight residual visual impacts from VSR1 Lamma Island (Hung Shing Ye
beach), VSR2 Lo So Shing Beach, VSR4 Ferry to Cheung Chau, VSR 5 Cheung Chau,
VSR6 Discovery Bay, VSR 8 Chi Ma Wan Peninsula, VSR 9 Cheung Sha, VSR 10 Lantau
Trail, VSR 12 Queen Mary Hospital and Mount Davis, VSR 13 Pok Fu Lam - Pauline
Chan Building at HKU, VSR16 Ocean Park, and VSR 18 Penny’s Bay.
3.
Moderate
residual visual impacts have been identified at VSR7 Silvermine Bay (Mui Wo), VSR11
The Peak, VSR 17 Mt Stenhouse and VSR 19 East Lamma Channel.
Four Visual Mitigation Measures are proposed that
will reduce the severity of these visual impacts.
According to Annex 10 of the Technical Memorandum
on the Environmental Impact Assessment Process (EIAO-TM) the Landscape and
Visual Impacts are considered acceptable with mitigation.
The potential impacts to cultural heritage
caused by construction and operational activities of the proposed offshore wind
farm and its components have been assessed in Section 12 of this EIA Report. The impacts have been identified and assessed to
be in compliance with the criteria and guidelines stated in the EIAO – TM Annexes 10 and 19 respectively.
The assessment has included a terrestrial
and marine archaeological investigation as well as a built heritage investigation.
No declared monuments, graded historic
buildings, government historic sites and archaeological sites listed by AMO have been identified within or
adjacent to the proposed works. One
potential marine archaeological site (SC007/57262) was identified from a review
of geophysical data. This site, potentially
a shipwreck, is located outside of any area of works and will not be directly
or indirectly affected by construction or operation of the wind farm. The avoidance of direct impacts to the
shipwreck identified during the geophysical survey will be verified by the
Environmental Team and the Independent Environmental Checker through review of
the final design prior to the installation of turbines and submarine cable. Designs will be checked to ensure that no
works will occur within 50 m of the shipwreck.
No marine
archaeological sites will be affected by works, and therefore, the proposed
development imposes no marine archaeological impact and no mitigation measures
are considered necessary.
HK Electric has conducted consultations and
engagement with project stakeholders to hear their views on the project plan while at
the same time, addressing their concerns. These stakeholders include representatives from
fishermen groups, green groups, District
Councillors, Rural Committees Members, government
advisory
committee
Members, various
Government Departments, learned institutions, industry practitioners and
members of the public. The feedback
from these consultations has been considered in the preparation of this EIA
Study Report.
15.11
Environmental
Monitoring and Audit (EM&A)
The construction and operation of the proposed offshore
wind farm development has
been demonstrated in this EIA Report to comply with the EIAO-TM requirements. Actual
impacts during the works will be monitored through a detailed Environmental
Monitoring and Audit (EM&A) programme. Full details of the EM&A programme
are presented in the EM&A Manual attached
to this EIA Report. This programme will
provide management actions and supplemental mitigation measures to be employed
should impacts arise, thereby ensuring the environmental acceptability of the
construction and operation of the proposed offshore wind farm development.
No unacceptable residual impacts have been predicted
for the construction and operation of the offshore
wind farm or its associated
facilities. It must be noted that for
all of the components assessed in the EIA
Report, the assessments and the residual impacts have been shown to be
acceptable and in compliance with the relevant assessment standards/criteria of
the EIAO-TM and its associated Annexes.
15.13
Environmentally
Responsible Designs
The EIA Study has facilitated the integration of
environmental considerations into the design process for the Project. One of the key environmental outcomes has
been the ability to plan, design and ultimately construct the offshore
wind farm so that direct
impacts to sensitive receivers are avoided, as far as practically possible. A detailed assessment of alternative
sites within the Study Area has been conducted as well as an assessment of the
site layouts and construction methods (See Section
15.2).
15.14
Environmental
Benefits of the Project
Implementation of the Project will make a contribution
to managing emissions of air pollutants and climate change and will provide
diversity of fuel supply. The purpose
of the proposed project is to utilize wind as source of renewable energy for
power generation to supplement fossil fuels, and to make contributions to the
improvement of the air quality in
The operation of the proposed 100MW offshore wind
farm with an estimated annual generation of 175GWh electricity would offset
approximately:
·
Annual
use of 62,000T of coal
·
Annual
emission of 150,000T of carbon dioxide
·
Annual
emission of 520T of sulphur dioxide
·
Annual
emission of 240T of nitrogen oxide
The electricity
generation from the proposed wind farm would be adequate to meet the
consumption for 50,000 families in