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  • International Workplace
  • 31 January 2007
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Workplace Law FM Conference - Buncefield

The Buncefield oil storage depot explosion in December 2005 resulted in 40 casualties, damage to residential and commercial premises nearby, and significant environmental pollution.

Today (31 January), at Workplace Law’s 8th Annual Facilities Management Legal Update Conference, Taf Powell, Head of the HSE’s Offshore Division and the Buncefield Investigation Manager, presented a session examining the lessons learned from the HSE investigation with regard to planning, fire safety, managing chemicals and business continuity.

Powell began the session by describing the incident, its immediate impact and the response by emergency services.

He described how an investigation into the causes of the incident began five days after the explosion – the time when the fires were eventually put out.

The clean up of the site in order to make it safe to approach took a long time, Powell commented. Investigators weren’t able to actually get into the bund area where the incident first began until a couple of months after the explosion.

While showing a video filmed on site Powell described the destruction the blast had caused. It was so powerful that industrial skips and vehicles were crushed where they stood.

Powell detailed the investigation board’s efforts to date in investigating the incident, including the employment of 150 experts, the taking down of 200 statements and the viewing on one year’s worth of CCTV coverage

Indeed, as Powell told the conference’s delegates, the board’s first report explained how it was CCTV footage that gave the first indication of what caused the explosion - when it showed the overflowing Bund A.

This first report explained how forensic evidence showed the explosion had been caused by a vapour cloud explosion – but that was the best that could be discovered at the time. Investigators believed the cloud had been caused by fuel from Bund A but at that time they could not be sure.

The board’s second report, Powell explained, showed how Bund A had “failed disastrously”, with problems such as the melting of wall jointings, flaking away of concrete and corners moving. He also explained that the sealant used for the Bund was only good for up to 80 degrees of heat, something the explosion and fire far exceeded. All in all, said Powell, these findings gave the board some “very interesting” things to think about.

The second report also covered issues to do with the environment. Just what kind of affect the tackling of the fire will have, as it was the fire suppressants used by the fire service rather than the fire itself that have the potential to cause environmental damage, is a long-term issue that has to be studied.

By the board’s third report investigators now knew the vapour cloud that caused the explosion had been formed by unleaded petrol escaping from an over full fuel tank in Bund A.

A 3am on Sunday morning –the day of the incident - the level gauge of the tank showed a flat reading, suggesting that the tank was no longer filling; however, this was not the case. The flat reading meant that the normal alarms which should have gone off to indicate a tank was getting too full were disabled.

The level of fuel in the tank continued to rise past the final high level device which should have set off an alarm and sent a signal that automatically cut off the flow of fuel to the tank at the pipeline; however, once again, this failed to happen.

At 5.20am the fuel began to overflow from the tank and the butane it contained vaporised; the fuel continued to break up and vaporise as more fuel overflowed from the tank. According to Powell investigators believe that 10% of the fuel that escaped vaporised.

At 5.38 CCTV footage showed a 2m deep vapour cloud flowing over Bund A; at 5.50am the flow of fuel to the tank actually rose meaning that by 6am the vapour cloud had grown to 6m deep and equalled about 30 tonnes. The first explosion occurred at 6.01 and the second followed shortly after; this second explosion measured 2.3 on the Richter scale.

The second explosion was so intense that investigators have been unable to model it, in his session Powell likened it to having the force of a bomb.

The board raised certain areas of concern in its first report, including:

  • Design and operation of fuel sites;
  • Emergency preparedness;
  • Land use planning; and
  • CAs policies and procedures.

These concerns are all part of ongoing reforms. Recommendations on design and operation of sites will be released soon and the Government is also set to release a public consultation over land use.

In the meantime the Buncefield board’s investigation is still ongoing; running alongside this there is also a criminal investigation being carried out.

Further information and all of the investigation board's reports can be found at: http://www.buncefieldinvestigation.gov.uk/index.htm.