10.6.2 Potential Impacts during Operation:
10.6.2.1 Impact 1: Permanent Habitat Loss through placement of infrastructure on the sea bed.
217. Habitat loss during operation would occur from two main sources; placement of structures on the sea bed and scour associated with these structures. The scour assessment conducted for the proposed East Anglia THREE project (Chapter 7 Marine Geology, Oceanography and Physical Processes and Appendix 7.3) shows that the scour holes which would develop if no scour protection was placed around infrastructure would be smaller than the footprints of the proposed scour protection. Therefore, the worst case scenario for benthic ecology is likely to be the placement of scour protection.
218. If scour protection is applied it is likely to be in the form of rock, concrete mattresses, sand-filled geotextile bags, or similar.
219. The total overall maximum footprint of the proposed East Anglia THREE project would be 3.16km2 (Table 10.2).
10.6.2.1.1 East Anglia THREE site 220. Within the East Anglia THREE site permanent habitat loss (defined as the 25 year lifespan of the project) would be instigated by the placement of foundations structures, cable protection and scour protection associated with all of these infrastructure (Table 10.2).
221. As a worst case scenario it has been assumed that up to 10% of the inter-array and export cables within the East Anglia THREE site would not be buried and that instead be surface-laid and protected in some manner. The effects on sea bed morphology and sediment transport arising from the presence of cable protection measures would not extend far beyond the direct footprint (Chapter 7 marine Geology, Oceanography and Physical processes). Therefore, the footprint of the cable protection is considered to be the worst case scenario.
222. As discussed in Construction Impact 1 (section 10.6.1.1) four distinct infaunal groups were identified (Figure 10.6) within the East Anglia THREE site with all except group L (considered to be an outlier) common across the East Anglia Zone as shown in Table 10.11. These infaunal groups correspond to three biotopes identified using the method described by Connor et al. (2004). The sensitivity of these biotopes to substratum loss (equivalent to permanent habitat loss) is shown in Table 10.17.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 1 Introduction Page 71
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