On the 11th of December, 2005, in the early hours of the morning, a booming explosion
echoed across the English county of Hertfordshire.
The ground shook with what felt like a minor earthquake – something rarely felt in this
part of the UK.
As residents awoke, dazed and confused, they saw a giant plume of black smoke on the horizon.
Although they didn’t know it at the time, they were looking at the start of the largest
fire to take place in Europe since the end of World War Two.
The Buncefield Oil Storage Terminal, also known as the Hertfordshire Oil Storage Terminal,
is a major oil depot located on the edge of Hemel Hempstead, around an hour north of London.
It is the fifth largest oil depot in the UK, with a capacity of approximately 273 million
litres (or 60 million Imperial gallons) of fuel.
It was built in 1968, by construction company George Wimpey, for use by two oil and gas
companies: BP and Shell.
It was part of a wider project which saw a number of terminals built around the UK, all
linked by pipes running up and down the country, connecting them directly to major refineries.
This intricate network of pipes, known as the United Kingdom Oil Pipeline (or UKOP),
meant that products like diesel and petrol could be transported around the country quickly
and cheaply.
The terminal was operated by the British Pipelines Agency (or BPA), who also ran the United Kingdom
Oil Pipeline network.
During the 1980s, the entire network was extended and the Buncefield site became available for
more oil companies to access, while the UKOP network expanded with a “North” line and
a “South” line.
Another line was added during the 1990s.
Buncefield, given its relatively central location, played a crucial role in this network.
An important part of the Buncefield depot was the northwest portion of the site, where
six large tanks were situated, numbered 910 to 915.
The tanks were packed tightly together, to make optimum use of the available space, and
they were surrounded by a “bund wall” – a strong, reinforced concrete and earth
wall designed to contain any spillage from the tanks.
The control building was to the south of these tanks.
At night it could be difficult to see these tanks from the control room, but CCTV cameras
had been installed so that the tanks could be monitored.
There was also a complex system of sensors, alarms and fill level monitors, that would
notify anyone in the control room of anything unusual.
On the 10th of December, 2005, just before the evening shift change at the site, tank
912 was made ready to receive around 38,000 litres (or 8,400 Imperial gallons) of fuel
from the UKOP network, via the pipe system.
There was only enough room for around 22,700 litres (or 5,000 Imperial gallons) in tank
912, so the delivery destination of the fuel would need to be changed once it was full.
This was common practice.
The fill rate, which was set by workers in the control room, meant that the whole transfer
should take around 14 hours to complete, with the crucial change of destination required
at around 4:00am on the 11th of December.
However, as 4:00am approached, the display in the control room showed that tank 912 was
only 96.4% full, and so filling continued.
At this time, an unrelated problem with a road tanker loading system arose.
This required the attention of the control room supervisor, who had to leave the control
room to speak to the staff at the loading gantry, and then reboot the system.
At 5:30am, unbeknownst to the staff in the control room, tank 912 quietly started to
overflow - gasoline was streaming out of the roof vents, spilling over into the bund.
A switch inside the tank, designed to trip if the fill level got too high, had failed.
The spillage created a rich fuel and air vapour, which formed a cloud above the tank.
At around 5:45am, the flow rate into the tank increased, due to another transfer elsewhere
in the facility finishing.
In the case of tank 912, this only increased the rate at which the gasoline was pouring
out of the tank.
The vapour cloud moved with the breeze, which carried it away from the control room.
Within the control room, in fact, there was no suggestion that anything was wrong.
Elsewhere on site, though, some tanker drivers reported that they could smell petrol.
Before this could be properly investigated, at 6:01am, a massive explosion took place.
Later analysis suggested that the initial spark came from a fire pump house – an area
that ordinarily would be one of the last that anyone on site might think a likely place
for an explosion.
On this day, however, the vapour cloud had seeped into its vicinity.
The explosion was massive.
By some reports, it was heard in Belgium, France and the Netherlands, while the British
Geological Survey noted that the event measured 2.4 on the Richter scale – equivalent to
a minor earthquake.
The resulting fire spread to 20 large storage tanks within the site, and the flames stretched
hundreds of feet into the air.
The smoke cloud was visible from Lincolnshire, around 110 kilometres (or 70 miles) away.
There were further explosions at 6:27am and 6:28am.
Nearby schools, churches and homes had their windows and doors shattered and blown from
hinges by the blast.
One house had its roof blown off.
Local police, who initially suspected that the explosions were the result of a deliberate
attack, began an urgent evacuation of the area, with people fleeing their homes to avoid
the smoke and escape the possibility of further explosions.
One resident that lived close to the site, a Mr David Mitchell, told reporters that he
had felt his house “shaking and shuddering”.
His five-year-old daughter slept through the explosion, but woke up under a pile of rubble
as the walls of their house caved in.
An IT company, Northgate Solutions, was based adjacent to the Buncefield depot.
Their office building had every single window blown out by the explosions.
Fortunately, due to the early morning timing of the blasts, there were only four members
of staff onsite rather than the 400 that would have been there during normal working hours.
As such, a very rapid evacuation was possible.
A Major Emergency was declared by 6:08am, and around 150 fire-fighters were called to
the incident.
The nearby motorway, the M1, was closed.
The priority was to contain the fire first, and then put it out.
It was one of the largest fires ever seen in the UK, and foam had to be sourced from
all over the country to fight the blaze.
By midday on the 11th of December, six hours after the first explosion, only 10 of 20 separate
fires on site had been extinguished.
One problem faced by firefighters was that even if they managed to put out a tank fire,
it could still be reignited by the many other fires in the vicinity.
There was also the constant threat of further explosions, so the firefighters would have
to periodically withdraw for their own safety.
There were also some difficulties controlling the actions of members of the public, some
of whom wished to get closer to the fire in order to obtain photographs and footage of
it.
Mobile phone cameras had only recently become commonplace.
With the fire making headlines around the country, many videos shot on mobile phones
by members of the public were aired to a national audience – something which, it was later
thought, may have encouraged others to try and get close enough to obtain footage of
their own.
In all, it took two days to put out the main fires, but then one tank reignited.
As this tank was relatively isolated, the firefighters let it burn out.
It would be five days after the initial explosion before the site was completely free from fire.
In large part because of the timing of the early morning explosion, nobody lost their
lives in the Buncefield fire.
43 people reported injuries, two of which were deemed to be serious injuries: they were
kept in hospital and treated for breathing difficulties, but their condition never deteriorated
to the point that it was life-threatening.
Given the scale of the explosions, the vast and apocalyptic smoke clouds, and the huge
amount of property damage, it was considered almost a miracle that nobody had died.
A government inquiry was carried out, and it was found that the key safeguards that
had been put in place to prevent an overfill had all separately failed.
Neither the switch that should have tripped when the tank was overfilled, nor the alarm
that it would have activated were in working order.
Several established safety procedures had not been followed, and it was found that the
bund wall around the tanks had failed to contain the entire spillage.
With such a large network of sites similar to Buncefield, a raft of new legislation was
brought in to prevent a repeat of the catastrophe.
The inquiry also found that, while the emergency response was swift, emergency services in
the area were unprepared to respond to a major oil fire.
Over 2,700 insurance claims were raised by local residents and businesses.
The process of settling these claims took many, many years.
Though the oil companies involved, Total and Texaco, admitted liability, they subsequently
queried a very large number of the claims.
A civil litigation lawyer involved in the process later said:
“They wanted receipts and then said maybe [the claimant] should have gone to Tesco rather
than Marks & Spencer.
[If a claimant] bought 28 pairs of knickers and only had a receipt for 25, we were writing
four or five letters over three pairs of knickers and had to take witness statements.
It was bizarre.”
Some claims took nearly seven years to settle.
Even decades on, some residents express doubt about how safe the drinking water is in the
area, given the amount of oil that was spilled.
The explosions, though they did not result in any deaths, nonetheless left an indelible
mark on the area – one that, even decades later, has not entirely faded.