Environmental risk assessment and revised remediation plan for the marine sediments in Vikkilen

Sammendrag

The Climate and Pollution Directorate (now the Norwegian Environment Agency) made a request dated 08.11.2010 to AS Nymo, Grimstad municipality to conduct supplementary investigations at their shipyard in Vikkilen and develop a remedial action plan for contaminated ground and seabed sediments at the shipyard. AS Nymo has commissioned NIVA to produce the risk assessment and plan development. For the risk assessment purpose Vikkilen has been divided into three subareas: A (just outside the yard), B (remaining seafloor north of Skjevika), and C (outer Vikkilen). To make a finer grading of the risk pattern and remediation effects area B has been further divided into 5 sediment areas based on levels of TBT and extent of ship traffic (Figure S1). A stepwise assessment was made of the risk reduction as function of increase in the remediation area, by use of the Klif guidelines TA-2802/2011. A recommended remediation plan was presented to the Norwegian Environment Agency in 2012. This plan has now been revised on basis of an improved description of areas that may be eroded by ship propellers. This report presents both the stepwise risk assessment of the subareas, and the revised sediment remediation plan.