299. Work is ongoing to complete cable crossing agreements with Greater Gabbard Offshore Wind Farm and Galloper Wind Farms it is hoped that these would be finalised for the DCO submission. In order to complete this assessment it has been assumed that at each of the 72 cable crossings cable protection up to 6m wide would be required for up to 100m either side of the crossing point for each of the cables involved in each crossing. This equates to a total introduced surface area of approximately 0.23km2 of introduced substrate, which in the context of the wider North Sea is considered of low magnitude.
300. As discussed in Operation Impact 5 (section 10.6.2.5) it is not possible to predict what species would colonise the cable protection (although a summary of the types of organisms likely to colonise hard structures is provided in section 10.6.2.5). Previous studies of offshore structures indicate that the change from sandy sea bed to solid substrate would result in potential increases in the diversity and biomass of the marine community of the area through colonisation of the structures. However, there is likely to be only a small interaction between the remaining available sea bed and the introduced hard substrate and any interactions would be highly localised.
301. Sensitivity of the receptors is difficult to assess but due to their ubiquity in the region and the scale of these changes in relation to the communities present in the wider area, it is unlikely that the changes would result in any significant broad scale community or biodiversity changes. The sensitivity of the receptor is therefore considered to be at worst within the medium category.
302. When considering changes to existing communities the cumulative impact of colonisation of the combined cable crossings and associated cable protection would likely result in an impact of minor adverse significance. Confidence in the accuracy of this assessment is low and therefore a precautionary rating has been used when assigning the sensitivity of the impact.
10.7.2.4 Impact 4: Impact to the Outer Thames Estuary SPA 303. With regard to the Outer Thames SPA, impacts could come from the installation and operational effects of cable protection. This could be up to 1% of the East Anglia ONE export cables, up to 2.5% of the East Anglia THREE export cables and as yet undetermined amount of cable protection for the east Anglia FOUR cable export cables within the SPA. In addition, all these cables would cross the Greater Gabbard Offshore Wind Farm and GalloperWind Farm export cables within the SPA (see cumulative impact 2 above) with the potential for up to 72 crossings.
304. This SPA is designated to protect the nationally important wintering populations of red-throated diver (Gavia stellata) that it supports (see Chapter 13 Offshore Ornithology). The primary prey of the red-throated diver is fish species although
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 1 Introduction Page 85
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