Table 8.4 Selected Cefas Action Levels (take from Cefas 2000) Contaminant


Action Level 1 (mg/kg)


Arsenic


Cadmium Chromium Copper Nickel


Mercury Lead Zinc


Organotins (TBT, DDT) PCBs (sum of ICES 7)


PCBs (sum of 25 congeners) 44. 20


0.4 40 40 20


0.3 50


130 0.1


0.01 0.02


100 5


400 400 200 3


500 800 1


None 0.2


Cefas guidance indicates that, in general, contaminant levels below Action Level 1 are not considered to be of concern and are, therefore, likely to be approved for disposal at sea. Material with contaminant levels above Action Level 2 are generally considered to be unsuitable for disposal at sea. Dredged material with contaminant levels between Action Levels 1 and 2 requires further consideration and testing before a decision can be made.


45.


The Canadian Sediment Quality Guidelines involved the derivation of Interim marine Sediment Quality Guidelines (ISQGs) or Threshold Effect Levels (TEL) and Probable Effect Levels (PEL) from an extensive database containing direct measurements of toxicity of contaminated sediments to a range of aquatic organisms exposed in laboratory tests and under field conditions (CCME 2002).


46.


These values are not statutory standards. They were designed specifically for Canada and are based on the protection of pristine environments and are provided here as a more precautionary suite of sediment quality criteria. The findings should, therefore, be treated with caution. In the absence of suitable alternatives, however, it has become commonplace for these guidelines to be used by regulatory and statutory bodies in the UK, and elsewhere, as part of a ‘weight of evidence’ approach. The use of these standards within impact assessments for offshore wind farm projects is also widely accepted.


47.


Selected Canadian guidelines are presented in Table 8.5, and comprise two assessment levels. The lower level is referred to as the TEL and represents the


Preliminary Environmental Information May 2014


East Anglia THREE Offshore Windfarm


Chapter 8 Marine Water and Sediment Quality Page 16


Action Level 2 (mg/kg)


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