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ECOLOGY: BIRD & ANIMAL SURVEYS


to voice their concerns we are often able to allay fears by showing how our work with wildlife and habitats helps to preserve biodiversity and where possible enhance it. This has the


additional benefit of positively reinforcing our client’s reputation for sustainability.”


THE BEST SOLUTION FOR PLANNING APPLICATION


Making expert assessments at the early stages informs the planning of species surveys, which are dependent on the habitats and known incidence of species in a particular area.


In a recent survey of heathland, across which a cable route was planned, the specialist survey team from Thomson Ecology identified rare species including Dartford Warbler, the nocturnal Nightjar and sand lizards. By avoidance and incorporating mitigation, such as horizontal directional drilling at the design stage, impacts on the habitat and species were avoided.


Thomson Ecology www.thomsonecology.com


including a hydrophone deployed over the side of a vessel and an autonomous seabed recorder that may be deployed for up to 6 weeks at a time sampling the prevailing noise levels. In each case at the end of the deployment period, the data is downloaded and processed by the Kongsberg engineers according to the client’s requirement.


ACOUSTIC PROPAGATION MODELLING TECHNIQUES


The environmental directives discussed above require that a developer must assess the acoustic impact on the environment likely to arise from the proposed development. Yet in the early stages of project planning and development the precise configuration of the wind farm with regards to numbers and locations of turbines may not have been decided upon.


This uncertainty renders the task somewhat problematic especially when it is necessary to provide an estimate of the underwater sound levels and potential impacts for each constructional scenario being considered. A full acoustic analysis for all scenarios may take many weeks to achieve: this often does not fit in with project timescales and can lead to considerable nugatory effort.


FLEXIBILITY


The regulatory authorities allow for a degree of flexibility in the plans that are eventually submitted to the consenting process provided they incorporate the worst possible case from an environmental impact perspective. To address this, the


project team, including marine ecologists, underwater noise modellers and members of the regulatory bodies confer in order to agree a project design that satisfies all necessary requirements and constraints. To assist in this process and to help define the worst case scenario in respect of man- made noise, Kongsberg has developed a ‘Quick-Look’ tool. This is an acoustic propagation computer programme that provides a ‘first-draft’ estimate to the spatial distribution of sound pressure arising from each sound source in the development.


The alternative approach to Quick-Look involves a fully comprehensive acoustic analysis which is time-consuming and requires detailed information about both the noise source and the marine environment in which it is operating. Each noise source must be defined in terms of its source level and its frequency spectrum over a given bandwidth while the environmental data must describe the bathymetry, oceanography and seabed geoacoustics of the site in which the noise sources are located.


The acoustic propagation programmes themselves are technically complex and generate mathematical solutions to the Elastic Wave equations. In order to achieve this, the programmes make use of mature and rigorous mathematic and scientific methodologies that have been reviewed extensively in the international literature over a number of years. This point is considered to be of fundamental importance. If acoustic modelling is


based on ’in-house‘ solutions using non peer-reviewed techniques this could compromise the developer in the event that the environmental impact assessment documents become subject to scrutiny.


GROWING DEMAND FOR ACOUSTIC IMPACT ASSESSMENT


Offshore wind development is likely to remain a high profile activity over the next few years if the UK is to meet its targets for the generation of renewable energy. Equally, environmental compliance must remain at the forefront if development is to be undertaken in a sustainable manner. This article has shown how a combination of expert technical services with the best available science may be brought together in order to quantify the acoustic impact of developments on the marine environment and hence to minimise any potential disruption that may ensue.


Kongsberg www.km.kongsberg.com


ED’S NOTE – Please note that this is an abridged version of a more comprehensive article. This can be accessed by scanning the pink QR Code below or clicking on the online link.


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www.windenergynetwork.co.uk


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