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4.1.1.2.1 Proposed method for assessment: The information generated by the physical processes chapters will be used to determine the magnitude of smothering both in terms of the area impacted and the thickness of deposited material.
Assessment of the sensitivities will be guided by the assessments available on MarLIN.
4.1.1.3 Re‐mobilisation of contaminated sediments: 27.
Sediment disturbance could lead to the mobilisation of contaminants that could be harmful to the benthos. Work undertaken for East Anglia ONE suggests that there is little contamination in the sediments offshore and for the windfarm areas it is considered unlikely this impact will be significant.
4.1.1.3.1 Proposed method for assessment: The magnitude of the impact will be assessed based on the levels of contamination within the sites and export cable routes and the maximum amount of sediment disturbance that will occur during construction.
Contamination levels of the sediment will be derived from existing data (for example the National Marine Monitoring Programme (NMMP) Cefas 2001) and results of sampling carried out by EAOW. Contaminant sampling carried out by EAOW includes:
o East Anglia ONE sampling (which found no evidence of anthropogenic impacts in the Warren Springs disused disposal ground (which covers East
Anglia ONE and part of the cable route)); and
o East Anglia 2013 contaminated sediment sampling within sites East Anglia THREE and East Anglia FOUR and along the cable route.
Assessment of the sensitivities will be guided by the assessments available on MarLIN.
4.1.1.4 Underwater noise and vibration: 28.
Research into the effects of underwater noise upon benthos is on‐going. However it is likely that there is habituation to noise created by the existing shipping which occurs in the area. There may be reactions from some benthic species to episodic noise such as that from pile driving (Lovell et al, 2005, Heinisch and Weise, 1987). Any impact is likely to be localised and temporary (i.e. occurring only during piling).
4.1.1.4.1 Proposed method for assessment: The qualification of the magnitude of this impact will be guided by both the results of noise assessments and the findings of the ES chapter that will assess the impacts of underwater noise (Chapter 9 Underwater noise, vibration and EMF).
Evidence Plan Benthic Ecology Method Statement
East Anglia THREE & East Anglia FOUR Offshore Windfarms