The Buncefield Explosion: Were the Resulting Overpressures Really Unforeseeable?

On Sunday 11 December 2005, a severe unconfined vapour cloud explosion followed by several tank fires occurred at the Buncefield oil storage depot in England, causing widespread damage to homes and businesses surrounding the site, hopefully without any victim.

The damage caused by the resulting blast wave(s) surprised all the process safety community and explosion experts, as common hazard assessments would have predicted overpressures of only 5 kPa instead of 200 kPa as suggested by collected data.

One of the particularities of the Buncefield oil storage depot is that it was surrounded by long and continuous rows of trees and bushes: this has been identified to be responsible for the resulting high overpressures.

Recently, explanations of the resulting overpressures were given by explosion experts using data from large-scale explosion tests and CFD simulations.

This article aims to show that careful application of simple methodologies used in common risk assessments would have allowed to properly estimating explosion severity and resulting overpressures.