Table 7.33Magnitude of effects on sea bed morphology and sediment transport due to cable protection measures for inter-array cables under worst case scenario
Location
Near-field* Far-field
Scale High Negligible Duration High Negligible Frequency High Negligible
Reversibility Magnitude of Effect
Negligible Negligible
High Negligible
* The near-field effects are confined to a small area (likely to be within the footprint of cable protection works), andwould not cover the whole East Anglia THREE site.
364. The effects on sea bed morphology and sediment transport arising from the presence of inter-array cable protection measures would not extend far beyond the direct footprint. Therefore, there is no impact associated with the proposed project on the identified marine geology, oceanography and physical processes receptor groups since these are located remotely from this zone of potential effect.
365. The significance of these effects on other receptors is addressed within relevant chapters of the PEIR.
7.6.2.7 Impact 7: Morphological and sediment transport effects due to cable protection measures for offshore export cables
366. As a worst case scenario it has been assumed that burial of the export cables would not practicably be achievable within some areas of the offshore cable corridor and, instead, cable protection measures would need to be provided to surface-laid cables in these areas.
367. The locations where cable protection measures are most likely to be required are primarily in areas of cable crossings with the Galloper and Greater Gabbard Offshore Wind Farms and in areas of sea bed characterised by exposed bedrock.
368. The impact assessment in relation to this issue assumes a worst case of cable protection measures being required along:
Up to 10% of the length of the export cables at, or east of, the cable crossings with the Greater Gabbard Offshore Wind Farms and Galloper Wind Farm Export cables.
Up to 2.5% of the length of the export cables to the west of these cable crossings.
369. Cable protection may take the form of concrete mattresses, fronded concrete mattresses, rock dumping, bridging or positioning of gravel bags.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm Chapter 7 Marine Geology, Oceanography and Physical Processes Page 72
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