The Buncefield oil storage and transfer facility is located to the
north of London. Refined stocks such as petrol and aviation
jet fuel are pumped remotely into the facility from refineries across England and out to sites across south-east England
including Heathrow and Gatwick airports. On the morning of
December 11, 2006 the liquid level indicator on one of the
large tanks failed while it was receiving unleaded petrol from
a remote site. Even though the petrol was being pumped in
at a rate of 550m3/h into Tank 912 from 3:00 am onwards the
liquid level indicator did not show a change in the height of
liquid in the tank. Just over 2h later the tank was completely
full and flow should have stopped automatically. It did not
and unleaded petrol began to cascade down the outside of the
tank