The HSE and the Environment Agency have launched an official investigation into December’s massive explosion at the Buncefield fuel depot.
It is the biggest industrial blast in the UK since the Flixborough disaster in 1974 and the first major HSE investigation to take place since the Potters Bar derailment in 2002.
The two agencies, as the Joint Competent Authority, took over the investigation from Hertfordshire Constabulary on 14 December, three days after a number of explosions devastated the Hertfordshire Oil Storage Terminal (HOSL) site near Hemel Hempstead.
The investigation will try to establish the causes of the incident by collecting forensic and other evidence, carrying out interviews, and revisiting the provisions of the site operators’ safety report.
The three operators involved are HOSL – a joint venture between oil companies Total and Texaco; the British Pipeline Agency (BPA), in which Shell is the major shareholder; and BP Oil Ltd. Prohibition Notices were served by the HSE on HOSL and the BPA to ensure adequate risk assessments were made and control measures agreed with the Executive before any repair, modifications, remediation, or demolition were carried out in the wake of the blast. In a statement HOSL said its clean-up process at the site was being carried out “in strict adherence to the procedures laid down by the HSE investigation”.
An independent board has been set up to supervise the investigation in accordance with the HSE’s Major Incident Investigation Policy and Procedures. Board chair, the Rt Hon Lord Newton of Braintree, explained: “The investigation will be carried out thoroughly, objectively, and concluded in a timely manner, with its findings made public as soon as possible, subject to legal considerations.”
HSC chair Bill Callaghan added: “Our aim. . .is for the investigation to engage with the public and the local community in as open and transparent a way as possible. We will want the investigation to have the fullest engagement with those running the site, those employed on the site, and the wider industry.” At the time of going to press, the HSE said it was still “a couple of weeks away” from issuing a preliminary report.
Immediately after the explosion various possible causes were being mooted, including vapour cloud ignition, a pipeline malfunction, and storage tank failure. Witnesses who spoke to the press at the time reported seeing “steam and vapour” rolling across from some of the 20, or so fuel tanks on the site. According to the head of the HSE’s Offshore Division Taf Powell, who is managing the investigation, the vapour-cloud ignition line of inquiry is being pursued but he emphasised that “there are others that we cannot yet discount with certainty”.
Renowned disaster expert Trevor Kletz, visiting professor at Loughborough and Texas A&M universities, said that while it is almost impossible for petrol vapour to explode in the open air, it can happen. Recalling such an incident that occurred in the US in the 1980s, he told SHP: “As most practitioners know, there is not a lot that is new in safety. You should always look for similar things that have happened before.”
Fire and explosion hazard management consultant Niall Ramsden said another issue that may be raised by the investigation is automatic monitoring of tank contents and vapour releases. Explaining that there are no international recognised standard practices in this field, he said: “There is now greater scope to provide alarms for events outside of normal operating modes. It is obviously far too early in the investigations to say if such measures would have detected a ‘process upset’ and consequently allowed faster detection and response to the incident – hopefully before ignition – but they certainly could, in some circumstances.”
The HSE said its conclusions on the explosion would be communicated to interested government departments, including the Cabinet Office, which is currently coordinating a study (begun before Buncefield) aimed at formulating proposals for reducing the potential hazards from large industrial sites across Britain.
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