Reference: ESB-146/2006 Issue 3
Date: May 2009
1.3 Site Selection
1.6 The Project Team
2.2 Water Quality
2.3 Benthic Ecology
2.4 Pelagic Ecology
List of Figures
List of Tables
Table 1.1 Summary of Foundation & Substructure Options
184.108.40.206 “The Project” refers to the development of the proposed 200MW Hong Kong Offshore Wind Farm (HKOWF) in Southeastern Waters of the HKSAR.
The Project is proposed to be
220.127.116.11 Section 1.2 summarises the site selection process, and its importance in avoiding impacts, which is of preference to attempting to mitigate them.
18.104.22.168 Up to 67 turbines will be arranged in a grid, and each will be affixed to the seabed by a foundation consisting of a jacket structure with suction caissons. The suction caisson foundation avoids the need for dredging or marine piling, thereby minimising potential adverse ecological impacts on marine sensitive receivers.
22.214.171.124 The turbine substructure also offers the opportunity for artificial reef development.
126.96.36.199 To ensure maritime safety, access to the wind farm by unauthorized marine traffic, including major fishing vessels, shall be restricted and actively managed, enabling the Project to function as a fisheries protection area and thereby contribute to sustainable fisheries management in the HKSAR.
188.8.131.52 The key strategic benefits of the Project include:
· Capacity to produce ~1% of total HKSAR annual electricity needs. The energy required to build a wind farm is typically recovered in the first year of operation, thus bringing a net positive effect on greenhouse gas emissions.
· Significant benefits to local air quality, with every year of Project operation offsetting approximately: 
· 343,000 - 383,000 tonnes of carbon dioxide;
· 54 - 60 tonnes of sulphur dioxide;
· 394 - 440 tonnes of nitrogen oxides; and
· 14 - 16 tonnes of particulate material.
· A substantial contributor to the HKSAR’s renewable energy target of 1 - 2% of all energy from renewable sources by 2012.
184.108.40.206 Key Project components shall include:
· Up to 67 wind turbines
· An offshore transformer platform
· Sub sea collection and transmission cables
· Research Mast
220.127.116.11 The base scenario for Project development assumes that 67 nos. of 3MW turbines shall be installed, the EIA Study also allows for installation of a smaller number of larger turbines – in this case, 40 nos. of 5MW turbines – that would approximately generate the same power and occupy the same total sea area.
18.104.22.168 The turbines will be arranged in a grid, and each will be affixed to the seabed by a foundation consisting provisionally of a jacket structure with suction caissons.
22.214.171.124 The turbines will be linked by collection cables to an offshore transformer platform from which electricity shall be transmitted to shore via two 132kV cables where the cables will connect into a small underground cable connection pit (onshore works are not part of this EIA). A research mast will also be installed to collect data on the offshore environment.
126.96.36.199 The site selection process is probably the single most important method for mitigating potential environmental impacts from a wind farm. By choosing the right site it is possible to largely eliminate many potential impacts before they arise.
The potential for large-scale
land-based RE development in the HKSAR is limited due to lack of land
availability – most land being already developed, under conservation
protection, and / or simply ill-suited for large-scale deployment of RE. This is well demonstrated in the EIA’s
recently completed by CAPCO for its Commercial Scale Wind Turbine Pilot
Demonstration at Hei Ling Chau and Hong Kong Electric for their wind turbine on
188.8.131.52 As detailed in section 2 of the main EIA, HKSAR offshore waters offer more usable space, and of the offshore technologies available, wind power is viable for large-scale development.
184.108.40.206 There are several factors that need to be considered when assessing the location of a potential offshore wind farm, including:
· Physical Location: Mean wind speed, water depth, seabed character, sub-surface geology, coastal processes, and seascape / landscape assessment.
· Biological Environment: Protected areas, benthic, demersal and pelagic marine life, and birds.
· Human Environment: Utility infrastructure, economic development opportunities, tourism / leisure, archaeology, navigation, fisheries, port facilities, civil and military aviation, radar facilities (aviation and marine).
220.127.116.11 For any potential development location there are also likely to be insurmountable issues (e.g., water too deep to build in) and other issues that, subject to study and adequate mitigation may be surmountable (e.g., habitat management). Marine environment criteria were thus selected that represented absolute or relative constraints for Project development, including:
· Physical Infrastructure, (e.g., Bridges and tunnels, Marine Parks);
· Shipping lanes, Fairways & Anchorages;
· Productive fisheries areas; and
· Marine conservation areas, including core habitat for marine mammals.
· Important coral sites
18.104.22.168 These various constraints (surmountable and insurmountable) were entered into a Geographic Information System (GIS) for analysis, from which it was possible to identify potential areas for project development. Where appropriate, buffers were added to some selection criteria. During the course of the Study the branding of an area of coastline as a “Geopark” has been announced by Government. This area lies within the constraints of coastline previously identified.
22.214.171.124 Figure 1.4 displays the consolidated ecological constraints that formed one component of the overall constraints map produced through this analysis.
126.96.36.199 Figure 1.5 displays the output of the consolidated constraints mapping exercise - the identification of three broad areas relatively constraint-free for potential wind farm development:
· Southeastern Waters
188.8.131.52 The Southeastern Waters was considered to offer the best potential for a commercial scale offshore wind farm development due to the large area of contiguous seabed, the relative lack of environmental sensitivity indicated by the site screening exercise and the anticipated higher relative wind speed.
184.108.40.206 In order to define a more specific location and turbine layout within this broad area a number of criteria were subject to further assessment. These included optimising grid connection (to minimise offshore cabling works and electrical losses), visual sensitivity (using landform to screen the Project) and wind direction (to maximise advantage of prevailing wind direction).
220.127.116.11 During this refinement process, the Project was also re-located further away from the Ninepin Islands and Basalt Island without moving closer to the ecologically sensitive Victor Rock, with the final location and layout as presented in Figure 1.1.
The constraints mapping
exercise was repeated to refine the transmission cable route, with four landing
options analysed. The
Route option 1 was preferred as
it comprises the shortest route
18.104.22.168 The wind farm components of most relevance to construction phase impact assessment are the foundation and substructure that may affect the seabed and associated marine life. The “foundation” is the component that penetrates into the seabed and the “substructure” links the foundation with the “superstructure” via a transition piece. Figure 1.7 illustrates the concept.
22.214.171.124 A preliminary review of the various foundation and substructure options was completed to assist the EIA Study. Table 1.1 summarises the relative environmental merits of each option and combination.
Table 1.1 Summary of Foundation & Substructure Options
Technical and Environmental benefits
Technical and Environmental Disbenefits
Well understood and proven technique
No seabed preparation required
Underwater noise from piling can impact pelagic species
May not be feasible in deep water / shallow rock-head sites
Suction Caisson Foundation
Less marine plant required
Easy to commission and decommission
No seabed preparation, piling or dredging required
No major disbenefit
Gravity Base Foundation
Well understood and proven technique
Significant amounts of dredging and site preparation works can impact water quality and therefore affect ecology
Unlikely to be economically viable
Well understood and proven technique
Not technically feasible at site due to water depth/ground condition combination
Tripod / jacket sub-structure
Complex structure allows for more marine growth
Suitable for water depth at site
No major disbenefit
126.96.36.199 Table 1.1 shows that gravity foundations would require significant ground preparation and dredging, whilst pile foundations would create more noise impact through hammering and driving. Suction caissons (shaped like an over-turned bucket) can be installed into the ground or seabed through a combination of self-weight and suction without any sediment removal. Figure 1.8 displays the concept.
188.8.131.52 For this reason suction caisson foundations represent the least impact option the suction caisson foundation is the preferred solution and were adopted as the ‘base case’ for Project development - this conclusion has since been validated by site specific testing and monitoring.
184.108.40.206 For the suction caisson substructure options, a 4-legged jacket would have marginally higher impact (due to being slightly larger with one extra suction caisson) than a 3 legged tripod / jacket and has therefore been adopted as the base case option for this EIA Study.
220.127.116.11 In May 2008, project partner CLP led on the testing of a suction caisson at the proposed project location. The test was carried out under the supervision of various Government Departments, including the Buildings Department (structural aspects) and EPD (environmental aspects).The test involved the installation of a full scale suction caisson foundation. The foundation was left for 45 days and then removed. During the installation water quality sampling and video monitoring was carried out to inform the EIA water quality modelling assumptions. Building Department was also there to verify the tension test carried out to verify load bearing parameters - all of which met or exceeded design requirements. Figure 1.9 shows the test barge with the suction caisson onboard.
18.104.22.168 The indicative dimensions of the suction caisson foundation / jacket substructure combination to be installed are as follows:
· Suction caisson diameter: ~ 12 - 15m
· Substructure + foundation weight: 1,000 - 1,300 tons
· Seabed penetration: ~ 12m (incl. ~ 5m self-weight penetration)
Overall height: ~
22.214.171.124 Full details of the wind farm components, evaluation of their relative merits and details of installation can be found in section 2 of the EIA Study report.
126.96.36.199 The purpose of this EIA Study is to provide information on the nature and extent of environmental impacts arising from the construction and operation of the Project and related activities taking place concurrently. This information will contribute to decisions by the Director of EPD on:
· The overall acceptability of any adverse environmental consequences that may arise as a result of the Project and the associated activities of the Project;
· Any conditions and requirements for the detailed design, construction and operation of the Project required to mitigate against adverse environmental consequences wherever practicable; and
· The acceptability of residual impacts after implementation of the proposed mitigation measures.
188.8.131.52 Satisfying the aims of the EIA Study has been managed by achieving a number of more specific objectives as listed in the EIA Study Brief (ESB-146/2006). The objectives of the EIA study are to:
· Describe the Project and associated works together with the requirements and environmental benefits for carrying out the Project;
· Identify and describe elements of community and environment likely to be affected by the Project and/or likely to cause adverse impacts to the Project, including natural and man-made environment and the associated environmental constraints;
· Consider alternative options with a view to avoiding and minimising the potential environmental impacts to ecological sensitive areas in the Mirs Bay, Port Shelter, Junk Bay, Eastern Buffer and Southern Buffer Water Control Zones and other sensitive uses; to compare the environmental benefits and dis-benefits of each of the different options; to provide reasons for selecting the preferred option(s) and to describe the part of environmental factors played in the selection;
· Identify and quantify any potential loss or damage and other potential impacts to ecology and fisheries resources, flora, fauna and natural habitats and to propose measures to mitigate these impacts;
· Identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;
· Identify and quantify any potential landscape and visual impacts and to propose measures to mitigate these impacts;
· Identify the negative impacts on any historical and archaeological resources and to propose measures to mitigate these impact;
Propose the provision of
mitigation measures so as to minimise pollution, environmental disturbance and
nuisance during construction and operation of the Project
· Investigate the feasibility, practicability, effectiveness and implications of the proposed mitigation measures;
· Identify, predict and evaluate the residual environmental impacts (i.e. after practicable mitigation) and the cumulative effects expected to arise during the construction and operation of the Project in relation to the sensitive receivers and potential affected uses;
· Identify, assess and specify methods, measures and standards, to be included in the detailed design, construction and operation of the Project which are necessary to mitigate these environmental impacts and cumulative effects and reduce them to acceptable levels;
· Investigate the extent of the secondary environmental impacts that may arise from the proposed mitigation measures and to identify constraints associated with the mitigation measures recommended in the EIA study, as well as the provision of any necessary modification; and
· Design and specify environmental monitoring and audit requirements to ensure the effective implementation of the recommended environmental protection and pollution control measures.
184.108.40.206 The technical summaries in Section 2 present how the above study objectives have been achieved.
220.127.116.11 The Project Proponent for this Environmental Impact Assessment (EIA) Study is Hong Kong Offshore Wind Limited (HKOWL) – a 100% subsidiary of Wind Prospect (HK) Limited, itself a subsidiary of the Wind Prospect Group.
18.104.22.168 Wind Prospect (www.windprospect.com) is a leading international vertically integrated wind farm development, construction and operation company that has worked on over 45 wind farms around the world. Examples of Wind Prospect projects being constructed in 2007/08 include the 90MW offshore Burbo Bank Wind Farm in the UK and over 200 MW of onshore wind farms in Europe and the Asia-Pacific Region.
22.214.171.124 Wind Prospect always works in partnership with leading local partners and for the proposed HKOWF will work with CLP Power Hong Kong Limited (CLP) – the HKSAR’s largest energy utility and a leading investor in wind power and other clean energy technologies.
126.96.36.199 The lead consultant for the EIA Study was BMT Asia Pacific Limited - part of the BMT Group of companies (www.bmt.org). BMT is a leading international multi-disciplinary engineering, science and technology consultancy offering services to clients in range of sectors including the energy and marine transportation sectors.
188.8.131.52 The Project Team was supported by specialists from Hyder Consulting Limited, Cosine Limited, IGGE (HK) Limited, Asiatic Marine Limited, Urbis Limited, City University, Lam Geotechnics Limited, ALS Limited, Hong Kong Coastal Activities Centre Limited, E-connect Limited, Strategic Access Limited and Pinsent Masons; and also Messers Yu Yat Tung and Wan Po.
The proposed use of suction
caisson foundations avoids the need for any marine excavation or dredging in
offshore Eastern Waters. The key potential
impact during construction is therefore limited to the management of dredged
sediments from within
184.108.40.206 Other waste types associated with Project development include minor amounts of chemical wastes, sewage and general refuse. No significant environmental impacts from the handling and disposal of these waste types are anticipated, subject to the full implementation of the relevant waste management guidelines and best practices.
220.127.116.11 The potential for water quality impacts was greatly reduced from the outset by conducting a site selection process taking into account potential impacts, as well as by selecting suction caisson foundation technology, thereby eliminating the need for offshore dredging or major water quality impacts.
18.104.22.168 The key water quality issues and potential construction and operational phase impact of the Project have been assessed. The main concern relates to sediment dispersion during construction, particularly suspended sediment and possible contaminants, and the direct and secondary impacts of this on biological sensitive receivers.
An onsite test of a suction
caisson carried out in May 2008 verified that the predicted impacts of the
turbine foundations being proposed would not produce any adverse impacts. The key area for potential impact was identified
as the cable transmission route in
Mitigation measures including
limits on dredging rate have been determined for the transmission cable works
22.214.171.124 The potential for impact on benthic ecology was greatly reduced from the outset by conducting a site selection process taking into account potential impacts, as well as by selecting suction caisson foundation technology which avoids dredging.
Following desk-top review a
series of field surveys (shown in Figure 2.1) were
conducted that reaffirmed Eastern Waters as being of generally high marine
benthic conservation interest, although not within the wind farm footprint
which is composed of silty mud of low ecological value. The conservation importance of the benthic
Numerical modelling predicted
adverse impacts at minor coral communities in
126.96.36.199 The presence of the turbine foundations at the wind farm area will provide an artificial habitat for potential colonisation by benthic epifauna. The cumulative surface area of approximately 100,000 m2 (based on current Base Case Development Scenario of 67 tripod structures with legs nominal 5m diameter in 30m water depth) of ‘artificial reef’ sub-structures shall more than make up for the permanent loss / displacement of 48,000 m2 of silty mud of low ecological value, resulting in a significant enhancement effect at the wind farm area. The assessment in the water quality section identified that normal project operation will cause no significant changes in water quality, which indicates that there will be no adverse impacts on benthic ecology including infauna and epifauna communities during construction and operation phases of the project.
188.8.131.52 Figure 2.2 displays an example of a diverse community that has established on a submarine structure located south of the HKSAR in a period of less than 10 years.
184.108.40.206 The potential for impact on pelagic ecology was greatly reduced from the outset by conducting a site selection process taking into account potential impacts, as well as by selecting suction caisson foundation technology, avoiding both areas known to be sensitive and eliminating the need for piling or dredging at the wind farm.
220.127.116.11 Based on desk-top review and field survey it is evident that the waters of the proposed wind farm are not frequented by Indo-Pacific hump-backed dolphins and are only lightly utilized by Finless porpoise – with this species preferring more sheltered coastal waters around the Ninepins and Po Toi islands, and other waters to the south.
18.104.22.168 Figure 2.3 displays the distribution of Finless porpoise sightings in the HKSAR between 1996 and 2005. The EIA field survey displayed a similar general distribution and variability of encounters as that identified from AFCD long-term survey data in Eastern Waters.
22.214.171.124 Given this low usage of the Study Area and the preferred construction method, no adverse long-term impacts are anticipated on Finless porpoise from Project development, and no mitigation measures are proposed. Nevertheless, monitoring of marine mammals over a suitable period of time is recommended in order to be able to detect overall changes in use of the area. In addition, a 250m marine mammal exclusion zone will be implemented during installation of suction caissons and turbine substructures.
Regarding fishes, at worst only
a marginal increase in suspended sediment above baseline levels is predicted at
most locations during construction only.
Although the worst-case assessment scenario of concurrent marine
dredging and jetting at
126.96.36.199 A review of potential noise impacts has been completed, and this does not suggest any adverse impacts from marine vessel activity during Project construction or operation, or from underwater turbine noise. Suction caisson installation does not require piling.
188.8.131.52 A total of 57 bird species were identified in the Study Area by boat surveys between May 2006 and December 2007, among which several species or species groups are considered of relatively higher sensitivity due to their conservation significance, distribution and / or abundance within the Study Area. These species include White-bellied Sea Eagle, the breeding terns, Red-necked Phalarope, Black-tailed Gull and Cattle Egret, Aleutian Tern and White-winged Black Tern.
Figure 2.4 displays the
average cumulative distribution of
184.108.40.206 The impact assessment suggests that potential impacts on all birds resulting from construction and operation of the proposed wind farm will not be significant. In all cases, and as in the above example, the Project is not located near any significant feeding or roosting areas. Bird numbers recorded within the wind farm area were generally a small proportion of the recorded populations.
220.127.116.11 The widely-used model developed by Scottish Natural Heritage was used and predicts negligible collision risk for all of the most sensitive species in the Study Area based on their distribution and abundance. The significance of construction and operation impacts on avifauna is anticipated to be very low. Overall, the proposed wind farm is considered to have no adverse impacts on avifauna.
18.104.22.168 The potential for impact on fisheries was greatly reduced from the outset by conducting a site selection process taking into account potential impacts and avoiding areas known to be most productive.
The Project will lead to the
permanent direct loss to commercial fishing of approximately
Surveys including radar data
analysis suggest that most fishing activity is limited to near shore waters
including around coastal islands rather than in the exposed and relatively
unproductive waters of the Project location.
Figure 2.5 highlights the distribution of fishing
activity in June and July 2007 during the fishing moratorium in the
No significant water
quality-induced impacts are predicted on the popular fishing area around the
22.214.171.124 Overall, the wind farm and the necessary restrictions on fishing activity provide an opportunity to reduce pressure on the over-exploited fisheries resources in Eastern Waters. Establishment of artificial reef communities on marine foundations may benefit the overall abundance and diversity of fisheries resources, and will complement sustainable fisheries management in the HKSAR.
126.96.36.199 Following desktop study and marine geophysical survey, a total of eight partially buried targets with marine archaeological potential have been identified. It has been identified that one target within the wind farm footprint may potentially be impacted by array cable installation, and mitigation measures have been proposed accordingly. A buffer separation zone to avoid direct impacts on all targets during construction and operation has also been proposed as a best practice.
188.8.131.52 Further marine geophysical investigations adopting seismic surveys shall be conducted in parallel with the detailed engineering design prior to any site works. The planning approach has been a precautionary one of impact avoidance by sensitively locating turbines and marine cables, and re-locating if necessary. With this approach, no adverse impacts on cultural heritage are anticipated.
184.108.40.206 The potential landscape and visual impact was greatly reduced from the outset by conducting a site selection process taking into account potential impacts.
220.127.116.11 Landscape and visual impacts should be acceptable with mitigation measures given the location of the Project and the use of existing landforms to shield the turbines from view where practicable. Figure 2.6 displays an indicative view of the Project during operation.
18.104.22.168 Although offshore wind turbines would be entirely new features in the local landscape, international research shows that a clear majority of the public have more favourable responses towards their appearance compared with other types of development. In the particular landscape and visual context of this Project, it is concluded that for most visual sensitive receivers the wind farm will not represent an unacceptable impact.
The environmental outcome of the
project is the development of a substantive renewable generating capability
from an offshore windfarm in south-eastern waters of
· Air Quality - Annual offset of approximately 350,000 tonnes of Carbon Dioxide, 55 tonnes of Sulphur Dioxide, 400 tonnes of Nitrogen Dioxide and 15 tonnes of particultes.
· Water Quality - Suction caissons adopted for windfarm foundations negating dredging, and jetted cable installation adopted for majority of route to minimise seabed disturbance.
Benthic Ecology - Windfarm
sited on low value seabed, with cable set away from coral communities
Pelagic Ecology - Minimally evasive
construction negates adverse impact on fish stocks and other marine life
· Avifauna - Siting away from coastlines and known communities reduce distubance and negligible collision risk for the most sensitive species in the Study Area
· Fisheries – Windfarm sited in low fishing intensity and relatively unproductive waters, away from important spawning and nursery grounds. Restrictions on fishing activity and turbine foundations acting as artificial reefs may benefit overall fisheries resources, although some local fishermen (particularly trawlers) who habitually fish in the wind farm site will be affected to a limited extent.
· Landscape - While the windfarm will be a new feature in the landscape, it is sited away from habitation and will not develop unacceptable impacts on the character of the area.