NET ENVIRONMENTAL BENEFIT ANALYSIS — A TOOL OF DECISION-MAKING AT OIL SPILL RESPONSE

Development of oilfields started in Arctic requires adequate response preparedness to potential oil spills. Mechanical recovery due to specific conditions of Arctic has a lot of limitation in application and cannot prevent pollution of Special protected areas (SPA). It is necessary to consider application of dispersants and in situ burning (ISB). Oil spill dispersants are mixtures of nontoxic surface active agents in organic solvent, specifically formulated to enhance the natural dispersion of oil into the sea water column thus enhancing the biodegradation processes. Dispersed oil is practically non adhesive to feather of birds and hair of mammals. The treatment of oil with dispersants requires a cautious strategy in making decisions. It can be achieved by usage of special tool –Net Environmental Benefit Analysis (NEBA) procedures. The decision of dispersants application should be based on the following comparison: “What would be the impact of the pollution when treated with dispersant and when non treated with dispersant?” The NEBA should consider the behaviour of the treated non-treated oil, assess consequently the different resources which will be concerned either by the treated oil or by the surface film oil, assess the sensitivity of the different resources at concern towards the dispersed oil and toward the floating oil film. These analyses assist decision makers when considering whether or not the use of dispersants is appropriate to minimize the environmental/economic damage. This article describes the experience of NEBA application to substantiate decisions how to respond to potential oil spills at the sites on Aniva bay of Sakhalin-2 project at different oil spills scenarios. It was used incremental approach to choose them. Based on sensitivity maps, information about level of impact dispersed and floating oil on bioresources and results of mathematical modelling efficacy of different response methods application: monitoring (no actions to recover spilt oil), mechanical recovery and mechanical recovery together with dispersants application it was shown that SPA can be protected from pollution in most scenarios only in case of dispersants application. Amount of oil stranded on shore in case of application of response method was used as criteria of efficacy of method application level of damage.

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