[
The overfilling of a storage tank and the subsequent escape of fuel and formation of flammable vapour are likely “with some certainty” to have caused the explosion at the Buncefield oil storage depot in December last year.
The third progress report of the major incident investigation board pinpoints the overfilling of tank 912 (now known to have contained unleaded petrol) as the first in a chain of events that subsequently led to the huge explosion. But the report says that more work is needed to fully understand the explosion mechanisms, and how it generated such extreme ‘overpressures’ which caused so much damage.
The report also acknowledges the public pressure for practical recommendations to come out of the investigation that will help enhance safety in and around similar sites. Two key areas likely to emerge are the design and operation of such sites and the planning controls around them.
Another matter of public interest was identifying who, if anyone, is responsible for the events leading to the incident. The investigation into the causes of the incident will feed into the criminal investigation. When this is finished, the Health & Safety Executive and the Environment Agency will decide whether there are any grounds to pursue proceedings.
In deciding what information can be currently published, the inquiry has considered the need to avoid prejudicing any subsequent legal proceedings.