246. Negligible magnitude and medium sensitivity indicate that physical disturbance would be of negligible significance to benthic habitats and species within the offshore cable corridor.
10.6.2.2.3 Summary of Operation Impact 2 247. The impact of physical disturbance has been assessed as being of negligible significance for both the East Anglia THREE site and the offshore cable corridor. It is unlikely that there would be any interactions between the sources of impact within the different study areas and therefore the overall impact of physical disturbance caused by the operation of the project would be of negligible significance.
10.6.2.3 Impact 3: Increased Suspended Sediment Concentrations 248. Changes in the tidal and wave regimes around foundation structures and cable protection are likely to result in localised scour of the sea bed under a worst case that involves no scour protection being placed around such structures. As the source of the impact would occur in both study areas the assessment of this impact is not separated in the same way that other impacts have been.
249. As discussed in Operation Impact 1 (section 10.6.2.1) empirical scour assessments have been completed to determine scour depths, areas and associated sediment volumes for the worst case foundation type of gravity base structures (Chapter 7 Marine Geology, Oceanography and Physical Processes). Further information on the scour assessment methodology is presented in Appendix 7.3.
250. The worst case scour volumes are considerably less than the worst case volumes of sediment potentially released following sea bed preparation activities considered in Construction impact 2 (section 10.6.1.2) and therefore the magnitude of this effect would be less.
251. In addition, given the sediment types prevalent across the East Anglia THREE site, and the offshore cable corridor, most of the small quantities of sediment released due to scour processes would rapidly settle within a few hundred metres of each wind turbine or cable protection structure. Therefore, the magnitude of the impact is likely to be negligible to low.
252. The receptors of this impact are discussed in Construction Impact 2 (section 10.6.1.2) where it was concluded that their sensitivity was between low to medium. A low magnitude and a medium sensitivity to this impact indicate that smothering due to increased suspended sediment during operation of the project would result in an impact ofminor adverse significance.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 1 Introduction Page 76
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