South Arne field development: An environmental impact assessment of oil spills

The South Arne field being developed by Amerada Hess A/S is located in 60 m water depth approximately 200 km from the Danish mainland, in block 5604/2 9 of the Danish sector of the North Sea, As part of the development of the field, a comprehensive environmental impa ct assessment has been carried out, including the assessment of the impact from oil spills. The Danish authorities required that a 'worst case' oil sp ill be chosen as the basis for the assessment on birds and aquatic organism s including plankton, fish eggs and larvae and benthos, A well blow-out at the surface was chosen as the worst case for the impact on birds, and a seabed blow-out for aquatic organisms. The oil spill modelling was carried out with the DEEPBLOW, SLIKMAP and OSCA R models from SINTEF, The modelling identified environmentally sensitive ar eas which could potentially be influenced by an oil spill. These included t he Dogger Bank, western Skagerrak, south-western Norwegian Trench, the east ern German Eight and the Wadden Sea. Historical meteorological and hydrodynamic scenarios were chosen from a lon g period of records to ensure that the plume passed through the environment ally sensitive resource areas, For birds, a scan of the literature and available databases was made to det ermine the numbers and species of birds in the areas swept by the surface s lick, the number of fatalities was estimated and finally the recovery time for each species population was estimated. The impact on aquatic organisms was estimated using the predicted environme ntal concentration/predicted no effect concentration (PEC/PNEC) method of t he CHARM model. This method is normally applied to continuous discharges, b ut here has been used to estimate the impact of a transient pollution cloud resulting from an oil spill, (C) 2000 Elsevier Science Ltd. All rights res erved.