The present study aims to develop a methodology for the evaluation of the environmental risk induced by accidental oil spills from offshore installations, with a particular attention to the impact on the sea and on the coastlines. The necessity of outlining such a methodology is justified by a lack of focus on the environment as a damaged target among those considered by traditional risk assessment procedures, addressed until now exclusively to humans. Thanks to an increasing environmental consciousness of institutions, industry and people, the new environmental policies have incremented the preservation of the environment. In fact, Directive 2013/30/EU on safety of offshore oil and gas operations, recently transposed in the Italian legislation, introduced strict criteria relating not only to health and safety but also to environment profiles in the context of offshore oil and gas operations. The methodology developed aims at the estimation of the risk of sea contamination based on plausible accidental releases, marine weather conditions and, possibly, clean-up strategies. The methodological approach is closely related to the one adopted for risk assessment addressed to humans conventionally used in the context of major accident risk analysis of industrial plants. In the following, the methodology will be described in detail and applied to a case study for exemplification purposes.
Risk analysis methodologies usually allow to evaluate quantitative risk indexes assuming humans as the only target. However, industrial accidents occurred both offshore and onshore in the past have highlighted the presence of severe consequences also for the environment, caused by the release of significant quantities of hazardous substances. Only qualitative or semi-quantitative methods are actually available for the evaluation of the environmental risk induced by relevant accidents.
Therefore, standardized quantitative environmental risk indexes and methodologies for their estimation are currently missing in the technical literature. Even Directive 2013/30 /EU "Safety of offshore oil and gas operations and amending Directive 2004/35/EC" [1] does not suggest any methodological tool for integrating environmental impacts into major accident risk assessments. The Directive puts in evidence that the environmental consequences of oil spills are estimable trough specific software tools, yet the legislator does not specify how to combine consequences and probabilities in order to calculate risk.
The objective of the present study is to realize a methodology to evaluate the environmental risk induced by offshore oil spills, in fulfillment to the requirements of the Directive 2013/30 /EU.
