There has been an increase in the awareness of environmental consequences of major accidents, particularly as a result of the Buncefield fire (UK Hertfordshire Oil Storage Terminal) and the offshore Deepwater Horizon oil spill, and the connection between failures in process safety systems and environmental damage. Whilst there is an obvious link in principle between incidents and environmental consequence, there has been relatively limited work to prioritise planning and preventative expenditure reflecting environmental, as well as safety, outcomes. This paper presents a process whereby integration of process safety data and environmental fate and transport modelling can be used by oil & gas operators to understand and prioritise actions to reduce and mitigate potential environmental risks and to use an understanding of these as the basis for integrated safety planning and management.

In addition to risk ranking major accident events and their consequences, the approach can also be used to help inform emergency planning and the preparedness of operators. One example application of the approach is the use of modelling techniques to analyse the flow routes of released products from secondary containment, factoring-in the influence of man-made structures and drainage infrastructure as well as the fate and transport of material in the environment. Modelled outputs can help identify where improvements in containment systems may be beneficial in reducing risk and in informing emergency response. This paper provides a case study to illustrate how a risk based approach has been applied to enable an agreement with the regulatory authority on an appropriate scope of upgrades to major accident prevention protection measures for environmental protection.

The approach is tiered, to enable an appropriate degree of assessment commensurate with the level of risk; relatively low frequency events are not considered further, but are documented. Removal of those unlikely events through a process of compartmentalisation of a site provides a transparent method by which events which could generate the greatest impact on the environment may be identified. The key conclusion is that a detailed assessment of environmental risk can identify the most appropriate areas of a facility for environmental improvement, and conversely provide a defensible, risk-based rationale significant saving in capital expenditure on programmes which may ultimately serve little benefit in terms of protecting the environment.

The approach outlined has significance across the oil & gas industry as it enables closer integration of process safety and environmental consequence assessments and provides oil & gas operators with a managed approach to making investment decisions which are likely to have the greatest net safety and environmental benefit.

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