2010; Yeow and Cheng 2003; Yang et al. 2010). Further information is presented in Appendix 7.3.
341. Using these approaches, the worst case scour volumes under a 1 in 50 year return period event are less than the worst case volumes of sediment potentially released following sea bed preparation activities and therefore the magnitude of effect would be lower.
342. In addition, given the sediment types prevalent across the East Anglia THREE site, most of the small quantities of sediment released due to scour processes would rapidly settle within a few hundred metres of each wind turbine.
7.6.2.4.1 Assessment of effect magnitude and/or impact significance 343. Taking the aforementioned considerations into account, the worst case changes in suspended sediment concentrations due to scour around foundation structures are likely to have the following magnitudes of effect (Table 7.31):
Table 7.31Magnitude of effects on the suspended sediment regime due to scour around foundations under worst case scenario
Location
Near-field* Far-field
Scale Low Negligible Duration High Negligible Frequency
Medium Negligible
Reversibility Magnitude of Effect
Negligible Negligible
Low Negligible
* The near-field effects are confined to a small area (likely to be of the order of several hundred metres up to a kilometre fromthe foundation), andwould not cover the whole East Anglia THREE site.
344. The effects on suspended sediment transport arising from scour processes would not extend more than a few hundred metres away from each wind turbine location before the sediment settles on the sea bed. Therefore, there is no impact associated with the proposed project on the marine geology, oceanography and physical processes receptor groups since these are located remotely from this zone of potential effect.
345. The effects do, however, have the potential to impact upon other receptors and therefore the assessment of impact significance is addressed within relevant chapters of the PEIR, taking into consideration the tidal ellipses presented in Figure 7.4, which represent the potential pathways between the source and receptor.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm Chapter 7 Marine Geology, Oceanography and Physical Processes Page 68
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