||Design and Methods
Water and sediment quality
Desk based analysis and sediment sampling.
High energy site with only small quantities of mobile sediment. The most waterborne pollutants will be readily dispersed. Sediments did not contain significant quantities of contaminants. No impact through elevated suspended sediments or contaminant suspension on existing water or sediment quality.
Coastal Processes (sediments fluxes, waves and tidal currents)
Desk based and modelling study to describe the seabed processes impacts and effects of device deployment.
The seabed is primarily bed rock with pocket and gully deposits of coarse pebbles and cobbles, apart from the potential cable landfalls which will pass under the sand and gravel beaches.
The site is exposed to high energy waves from the Atlantic making it a dynamic environment. The nearshore areas are designated for nature or geology conservation and are important as a recreational area. A moderate impact of the development on the waves close to the device is expected and some localized impact on the currents and beach processes in its immediate vicinity. There is unlikely to be any noticeable impacts further away from the device towards the shore.
Onshore physical environment
Assessment of the potential impacts of the proposed development on the onshore physical environment.
The geology and hydrology of the area could be sensitive to construction. However best practice and environmental management controls are implemented during the construction phase, the scheme will have no adverse effects on the onshore physical environment.
Investigation into the mixing effects provided by the flow discharged from the system’s turbines
Field measurements on water velocities and suspended sediments. Use of computational models to simulate the impacts of the submersion of surface water by the discharging vertical turbines.
In a worst case scenario with no tide or wave induced cross flow and maximum discharge through a turbine, there could be a localized heating effect from the submersion of surface water in summer. In a more realistic model, incorporating a tidal flow, there is little heating of the seabed and the benthic ecology should not be affected even in the local vicinity of the device. It appears from the models that there will be localized heating effects of the water body above the sea bed however. This may have an impact on pelagic species, the effect is likely to be similar in nature but on a far smaller scale to cooling water discharge from power stations. Predicted effects on biodiversity reduction and/or abundance increase of some warmer water organisms are said to be highly localized and unlikely to have a significant widespread impact on the local marine environment .
Impact on designated sites
Assessment of the potential impacts of the device on designated sites in vicinity.
The device will be deployed within an area designated as a conservation site known as the Pembrokeshire Marine Special Area of Conservation (SAC).
Study at the existing environment and deployment site to assess the impacts of the deployment.
Installation of the mooring system may increase the overall diversity of the local seabed communities by providing colonization areas. Potential impacts: ploughing action of cable burial, pinning of the cable over areas of bedrock and potential damage caused by anchors and anchor lines. It is not envisaged that these activities will have significant impact.
Potential impacts: effect of the mooring chains and structures on sensitive and designated species attached to and protruding from bedrock reef habitat. To mitigate impacts blocks should be located out of sensitive areas.
Have some potential to impact on the marine communities however it is considered to be low.
Desk based review and consultations to determine the fish species present in the area to assess any likely impacts to these species.
The area is rich in species such as dab and several species of shark were identified as using the area. Migratory species such as salmon and several internationally protected species such as river lamprey and basking shark are also using the site. Commercial species such as crab, lobster and crayfish are also present in the area. The effects on such species are considered to be negligible in the context of the extent of local fisheries.
Fish are unlikely to pass over the ramp structure into the reservoir. Grills prevent large fish to pass through turbines and it is envisaged that they will flow back out of the reservoir unharmed. The turbines turn at a relatively slow speed so any fish small enough to pass through the grills should pass through the turbines unharmed.
Electromagnetic Fields (EMF)
Assessment of the potential impacts of equipment electromagnetic fields on sensitive fish species.
The Wave Dragon device power export cable would be no more than 2.3 km in length and would therefore represent a very small feature within the existing marine environment. The expected magnetic field from the cable is considered to be relatively low and given both the small scale of the project and the low magnitude of the anticipated magnetic field it is not anticipated that there is any likelihood of a significant impact for magnetically sensitive fish species.
Desk based literature review and local consultations were undertaken in order to assess the potential for impacts on marine mammals, including cetaceans, seals, otters and marine turtles.
The immediate area of the installation site is not understood to be of high importance for marine mammals in a local context, though Pembrokeshire coastal waters are recognized as being of relatively high importance regionally and nationally.
Impact to marine mammals mainly relates to noise issues both during installation and operation. Noise disturbance of marine mammals may occur up to several hundred meters from the noisiest construction activities for short periods of time within the construction period but this is not considered to be significant. There is the potential for greater effects on cetaceans in the area during installation but appropriate measures will be used to minimize noise during the construction process.
Onshore and Intertidal Ecology
Combination of a walk-over survey and a desk study were used to provide information to support the impact assessment for the ecology in the inter-tidal zone and of onshore habitats and species in relation to potential cable landfall locations at Marloes Sands and Westdale Bay and in the vicinity of candidate onshore cable routes.
The Pembrokeshire coastline has a diverse range of shoreline habitats from exposed bedrock on headlands to sheltered sandy coves and sheltered mud in the estuaries. Hard substrate areas, for example on bedrock or boulders outcropping from sand, typically support communities of algae.
The potential cable routes will pass through the Dale and Marloes Site of Special Scientific Interest (SSSI), which is a conservation site designated for its maritime grassland, heath, cliff crevice and ledge vegetation and coastal scrub. The project design aims to minimize disturbance and impacts to rocky reef or inter-tidal areas by avoiding these areas at the cable landfall therefore the impact is likely to be very small. Minor changes in beach profiles arising from the changes in the coastal processes during the operation of the device were found to be possible and may cause some habitat loss caused by moving sands. This impact would be temporary in nature and beach profiles are known to change significantly through natural processes. Certain important species, specifically Scaly Cricket, were identified by the studies in one of the landfall areas on Marloes Sands. These will be investigated further and the finalized design will take this into account. Scaly Cricket habitat will be avoided by moving temporary works away from sensitive areas.
Desk based study, drawing on current knowledge and data to assess the potential for impacts to birds. Consultations were also undertaken with key representatives on bird populations in the area. Lighting required as aids to navigation was also assessed.
The deployment area is proximate to three bird conservation areas and ten bird species were identified as being of importance, including the Manx Shearwater, and Red-billed Chough.
For the ten key species assessed the impact was considered to be low. Both the deployment and operation phases indicated negligible negative effects and for species like Storm Petrel, Lesser Black-backed Gull and Kittiwake the device would have no negative effects. Given the high intensity of ships in the area creating artificial lighting at night in the near shore environment, the addition of navigation lighting from the device scheme will present a negligible addition.
Landscape and Seascape Assessment
Desk study and preliminary site survey, baseline seascape landscape and visual assessment (including field survey).
The land within the study area all forms part of the Pembrokeshire National Park and the coastline is designated as heritage coast. Two Landscapes of Historic Interest are located within the study area, Skomer Island and the Milford Haven Waterway. Within the 7 km radius study area and the main users of the area, key viewpoints and key features were identified.
The presence of the offshore islands, together with the land form of the Dale Peninsula provides both enclosure and visual interest. It was noted that the absence of any land form in a south westerly direction allows long distance views across open sea. There are several Public Rights of Way routed throughout the mainland study area. Nine viewpoints were identified to be of high sensitivity. The device could be viewed from the setting units identified to the north and south i.e. to the north of Skomer Island, Milford Haven and Pickard. However, any views to the device would be restricted to coastal locations within these areas and any potential effects will be reduced due to the distance and the low height (above sea level) of the device. Sea users may be able to see the device at closer quarters; however this is dependent upon the route through the sea area that the users choose. The proposed development will be a temporary feature, expected to remain in place for up to five years. All readily visual components will be removed and effects to landscape and visual amenity, including seascape, will be reversed.
Archeology and Cultural Heritage Assessment
Geophysical and desk based studies. The geophysical survey was undertaken of the offshore survey area and cable route to shore, covering both the cable route options to Marloes Sands and Dale including a 2km area of search buffer zone.
The marine survey area was found to contain seven wrecks and sites of archaeological interest; in addition there are 110 reported losses within the area for which there are no known seabed remains. There is the potential for archaeological remains within the deployment area and it is anticipated that the final position of the mooring blocks will need to be informed by a seabed inspection prior to installation.
The onshore cable route corridor was found to contain 28 sites and monuments. Further studies will be required to assess the likely impacts to the onshore archaeology and cultural heritage through the onshore construction phase once onshore infrastructure has been further defined.
Assessment of the social and economic environmental in the Pembrokeshire and West Wales region.
Employment in the area was found to be dominated by the service and public sector with tourism featuring as the dominant factor in the Pembrokeshire economy. It was noted that the region attracts large numbers of visitors for the outdoor and marine activities present in the region. The Pembrokeshire Coastal Path and marine leisure activities such as sailing, diving, kayaking and coasteering were all found to make major contributions to the area’s economy.
The study was unable to qualify any effects on the levels of tourism caused by the device, however considering surveys on tourism for other renewable energy projects suggest the possibility of the Wave Dragon device to become a tourist attraction. The resulting capital expenditure and direct and indirect job creation is likely to be complemented by additional reputation benefits for the region. It is envisaged that the development would provide employment for the equivalent of 70 people in the construction and deployment stage, and the equivalent employment of 18 people through indirect and induced benefits.
The underwater noise has been estimated from measurements of a single Kaplan turbine in a controlled laboratory environment, and compared to on-site measurements.
Underwater noise generation as a result of ships propulsion systems, bow thrusters, rotating machinery, generators, dynamic positioning systems (if used) and ship echo-sounders. These sources are likely to dominate the underwater noise environment to a range of a few kilometers.
Noise will be mainly caused by increased vessel traffic in the region. The generator system may cause a behavioral response in marine mammals over a range of a few meters but this is not considered significant. Other mechanisms associated with wave interaction with the body of the device and hydraulic noise can also be considered insignificant. It is unlikely that the underwater noise, produced during any construction and operation activities will kill or cause direct physical injury to fish or marine mammal species. Disturbance to some sensitive species may occur in very close proximity to the deployment but this is considered to be insignificant.
Commercial Fisheries Assessment
Desk study on commercial fishing activity and its value, areas of use and landing data from official records. Consultations with Fisheries organizations and individual fishermen in the region. This information was used to assist and supplement the official statistics. Visual records.
The maximum number of fishing vessels active on site at any one time is three, however these are not always the same vessels.
The main impacts identified relate to the loss of access to grounds, restricted access through navigational controls, disruption to the industry through the cable laying and stabilization, loss of habitat (and potentially resource) and increased risk through the potential for accidents and collisions. There is some potential for enhanced fisheries through a mussel seeding scheme, attached to the device, however this is subject to the correct permissions being granted. It is considered that the impact of the deployment and operation of the device will be minimal, provided good liaison and clear early notification is given to the fishing industry.
Navigation: Detailed Navigation Risk Assessment
Navigation Risk Assessment: Maritime traffic survey of the area supplemented by research of other available data sources as well as consultation with other navigational stakeholders.
The deployment location is away from the main shipping lanes in the area, which are associated with Milford Haven. The risk of a commercial ship drifting off course and colliding with the structure was assessed to be very low.
There is large redundancy in the mooring system and hence there is negligible risk of mooring failure of the device causing it to come adrift. Even if this were to occur, contingency plans will be in place to alert shore-based personnel and respond to the emergency. Based on the best-estimate of fishing activity the frequency of fishing vessel collisions was estimated to be 1 in 100 years. To aid the identification of the device and minimize the likelihood of any collisions, the device will be appropriately lit and marked and awareness of the location of the device will be raised amongst local stakeholders. The generic risks of collision and cable snag are considered low, and risks of stranded personnel will be included within the Emergency Response Plan to be drafted prior to construction.
Other Relevant Projects
Identification of marine activities or industries in areas surrounding the deployment location.
Six types of marine activities and industries were identified:
- Offshore oil and gas
- Marine aggregate extraction
- Subsea cables and pipelines
- Marine waste disposal and dumping
- Military and civil aviation
- Abandoned munitions
|Reports and Papers
- Wave Dragon Wales (2007): Wave Dragon Pre-Commercial Wave Energy Device, Environmental Statement Volume 1: Non-Technical Summary, 36 pp (in English and Welsh)
- Wave Dragon Wales (2007): Wave Dragon Pre-Commercial Wave Energy Device, Environmental Statement Volume 2: Technical Report, 434 pp.
- Wave Dragon Wales (2007): Wave Dragon Pre-Commercial Wave Energy Device, Environmental Statement Volume 3: Figures 7 pp + 123 figures
- Iain Russell & Hans Chr. Soerensen: Wave Dragon: Results From UK, EIA and Consenting Process, Proceedings of the 7th European Wave and Tidal Energy Conference, Porto, Portugal, 2007, 8 pp
- Capman, J., Masters, I., Willis, M., Fidler, R.: Investigation into the mixing effect of a 7MW overtopping wave energy converter, Swansea University, School of Engineering, April 2009, April 2008, 14 pp.
- CMACS: Wave Dragon pre-commercial Demonstrator; Benthic Environmental Impact assessment update Based on supplementary benthic information, document: J3045 v2, February 2008, 46 pp.
- Beels, C., Troch, P., De Visch, K., Kofoed, J. P., De Backer, G., 2010. Application of the time-dependent mild-slope equations for the simulation of wake effects in the lee of a farm of Wave Dragon wave energy converters. Renewable Energy, 35, 1644–1661.