277. Chapter 7 Marine Geology, Oceanography and Physical Processes assess the magnitude of effect of such cable protection on the Outer Thames Estuary SPA as low section 7.6.2.7. and therefore given that only 0.0004% of the SPA is affected the magnitude of this impact is considered to be low.
278. As previously discussed in Construction Impact 1 the sensitivity of the benthic ecology to disturbance within the offshore cable corridor is considered to be low and therefore the impact to the Outer Thames SPA by reduction in prey source for red- throated divers is likely to be of negligible significance.
10.6.2.7 Impact 7: Electromagnetic Fields (EMF) 279. Electromagnetic fields as a result of the presence of inter-array and export cables may be detected by the some benthic species. EMF’s are strongly attenuated and decrease as an inverse square of distance from the cable (Gill and Bartlett 2010), any effects would therefore be highly localised. Furthermore, the majority of cables would be buried to up to 5m depth reducing the effect of EMF. Therefore, the magnitude of such an impact is considered negligible.
280. Evidence for sensitivity to EMFs comes from physiological and behavioural studies on a small number of marine invertebrates and no direct evidence of impacts to invertebrates from undersea cable EMFs exists. Biological effects studies have demonstrated small responses to magnetic fields in the development of echinoderm embryos and in cellular processes in a marine mussel, however at intensity fields far greater than those expected from undersea cables (Normandeau et al. 2011).
281. As discussed in other impacts the value of the benthic habitats and species within the East Anglia THREE site and offshore cable corridor is relatively low. This coupled with the fact that there is little evidence to suggest that benthic species would be adversely impacted by EMF (Chapter 9 Underwater Noise and Vibration and Electromagnetic Fields), the sensitivity of the receptor is considered to be negligible. In accordance with Table 10.9 a negligible significance is therefore predicted.
10.6.3 Potential Impacts during Decommissioning 282. On expiry of the lease for the proposed East Anglia THREE project, EATL would remove all structures, except cables and pin piles deeper than 1 to 2m, and return the sea bed to a usable state in accordance with the Department of Energy and Climate Change (DECC) decommissioning guidance (DECC 2011).
283. During the decommissioning phase, there is potential for wind turbine, foundation and cable removal activities to cause changes in suspended sediment concentrations and / or sea bed or shoreline levels as a result of sediment disturbance effects.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 1 Introduction Page 81
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