Advisian was appointed to assess the extent of possible bund overtopping in the event of failure of an atmospheric crude oil tank to enable the client to take mitigation measures and prepare response and contingency plans.
The client required a study of an atmospheric crude oil tank and associated bund to assess the risk of overtopping. The results were to be reported to the Health and Safety Executive, the UK regulatory body.
A site walkover was undertaken to verify the ground model and inspect the tank, bund and surrounding area. Following the site walkover a fluid flow model was constructed using the commercially available TUFLOW package. The model included LiDAR data, tank dimensions, bund heights and fluid properties.
Models were run to assess the impacts from catastrophic tank failure, tank tear, mixer hatch failure and import pipeline failure. These failure scenarios were identified from literature as being the most credible failure scenarios. The model was used to assess the surface flow of crude oil and wave propagation within and over the bunds and where applicable to off-site receptors.
The model outputs included images and animations of spill migration with time to assess the geographic spread of crude oil following a failure event.
Assessment of bund overtopping indicated that only the unlikely event of immediate catastrophic tank failure would compromise the bund containment measures and flow off-site.
The results were used to inform management and engineering mitigation measures and enable the client to prepare their response and contingency plans for the Health and Safety Executive.
