An unforeseen disaster

The buncefield explosion

Overview

� Introduction

� Chain of events

� Explosion and ignition source

� Organisational factors� Organisational factors

� Conclusion

No smoke without fire

IntroductionIntroduction

Overview

� Hemel Hempstead

� Buncefield oil depot

� The incident

� Responses

Hemel Hempstead

� Oil storage facility

� North of London

� County of

Hertfordshire

� 89,000 people

Hemel Hempstead

� Engineering compagnies

� Nearby London and

motorway

� Hertfordshire Oil Storage � Hertfordshire Oil Storage

Terminal (HOST)

Hemel Hempstead

Buncefield oil depot

� UK oil pipeline network

� Operator is Total for 60%,

Texaco for 40% and Shell

and BP also use their and BP also use their

facilities

Buncefield oil depot

Buncefield oil depot

� 5th largest of UK

� Capacity:

� 273 million litres of fuel

� 400 tanker lorries every day � 400 tanker lorries every day

� 2.37 million tonnes oil every year

� 5% of UK oil storage

� Storage of aviation fuel, diesel

and petrol

The Incident

� Explosion at six o’clock

� Heard 160 km away in the

Netherlands and France

� 2.4 scale of Richter� 2.4 scale of Richter

� Flames seen hundreds of

meters high from many

kilometers away

The Incident

The Incident

� Huge black smoke plume

headed over southeast

London

� Ultimately towards France � Ultimately towards France

and Portugal

� Could be seen on satellite

images

The Incident

The Incident

� Security worker at the depot:

"I sat down and all of a sudden there was

a huge orange light and a massive a huge orange light and a massive

explosion which blew the doors through

and knocked me off my chair, and the

ceiling fell in.”

The Incident

� Widespread damages

in local area:

� Broken windows and

blown-in doorsblown-in doors

� Cars caught fire

� Removed wall 800

meters away

� Roofs blown off

The Incident

The Incident

� 22 tanks were destroyed

� Biggest of its kind since

WWII

Responses

� 150 firefighters with 6

pumps for 25,000 litres of

water per minute

� Fire under control by the � Fire under control by the

evening of wednesday the

14th

Responses

� Heathrow Airport:

� 30% of supplied fuel

� Delay of landings

� Plains had to refuel at � Plains had to refuel at

other airports

� Fuel shortage for

months

Responses

� 2000 people had to find

alternative homes

� 227 schools, libraries

and other public and other public

buildings closed

� M1 motorway closed for

12 hours

Responses

� ‘go in, stay in, tune in’

� Information provided about plume

direction and spread

Responses

� Information collected

about air quality, soil

and grass samples

� Minimal impact of fire � Minimal impact of fire

on population due to

heat and weather

conditions

� Minimal health risks

Events leading to the explosionsEvents leading to the explosions

Chain of events

Overview

� Succession of events

� Layout of the tank

� Spread of vapour

� Bow-Tie Model

Layout of tank 912

� Levels and

temperature

� Independent

ultimate high level ultimate high level

switch

� Override keyswitch

� Floating deck

� Breather holes

� Deflector plate

Bow Tie

Looking at the location of the explosion Looking at the location of the explosion

Explosion and ignition source

Overview

� Facts

� Explosion mechanisms

� Ignition source

� Emergency generator cabin

� Pump house

� Conclusion

Facts

� Leak of unleaded petrol� Flashpoint below 32ºC

� Flammable range; 1.4%-7.6%

� Highest overpressures were

generated in the area of the

Northgate and Fuji car parks

Overpressures

Explosion mechanisms

� Gas cloud is ignited within a

confined volume� Majority of the cloud was not

confined!confined!

� Deflagration� Velocity is subsonic

� Turbulence, acceleration

Explosion mechanisms

� Detonation� Faster than the speed of sound

� Coalescence of a strong shock wave

and a fast-moving chemically reacting and a fast-moving chemically reacting

front

Ignition source

Emergency generator cabin:

� Scenario 1 � 'bang-box' explosion inside the

generator cabin

� Propagate with diminishing speed

across the south of the Northgate car

park

� Accelerate rapidly up the tree line

along Buncefield Lane (deflagration)

� Second explosion in the Pump house

Ignition source

Ignition source

Emergency generator cabin:

� Scenario 2 � 'bang-box' explosion inside the

generator cabingenerator cabin

� Detonation, as a result of pressure

and flame interaction with the

Porsche car

� Deflagration across Buncefield Lane

� Second explosion in the Pump house

Ignition source

Pump house:� Scenario 3

� Activation of the site emergency

system, sparks generated, explosionsystem, sparks generated, explosion

� Flame propagating toward the tree

lines (deflagration)

� Scenario 4

� Explosion in the pump house resulted

in a detonation

Ignition source

Ignition source

� Damage to the trees was

extensive and became worse as

Tree Cherry Trees Lane was

approached (scenario 1, 2)

� Relatively even level of damage

across the full car park area

(scenario 2)

� High level of damage to cars

parked at the south-east corner of

the car park (scenario 3, 2)

Ignition source

� Abrasion on the south side of posts

and trees (all options)

� Expected fuel-rich concentration of � Expected fuel-rich concentration of

the cloud in the vicinity of the pump

house (against scenario 4)

Conclusion

� Uncertainty regarding the

composition of the vapour cloud

� Uncertainty regarding the

explosion severity required to

cause the level of damage cause the level of damage

observed

� The time available, as the possible

scenarios could not be tested

against the considerable amount

of information available

Putting the ‘human’ in human errorPutting the ‘human’ in human error

Organisational factors

Organisational factors

� E-mail to Buncefield Investigations

� “As you may be aware, the criminal investigation is still ongoing and, although a decision to prosecute still ongoing and, although a decision to prosecute rests with HSE and the Environment Agency and not with the Board, we are unable to discuss certain issues in order to prevent prejudice of any potential criminal proceedings. Due to this, we are unable to assist you further with the information you require”

Tom Monger, Information Officer – Buncefield Major Incident Investigation Board

Organisational factors

The aftermathThe aftermath

Consequences

Overview

� Injuries/deaths

� Post traumatic stress

� Structure damages (on site)

� Economical damages (environment)� Economical damages (environment)

� Air quality

� Water quality

� Reputation

� Lawsuit damages

Injuries/deaths

� Although 43 people were

injured in the blasts on

Sunday, the 11th of

december, none were december, none were

fataly wounded.

� there were no fatalities.

Post traumatic stress

� Survey among 5000

residents. 40%

respondence.

� Explosion had high

physical impact;

88% heard the blast

84% considered smoke

close to house.

Post traumatic stress

� Low psychological

distress after explosion.

� Highest in South Dacorum

where fire was most where fire was most

apparent.

� Seeing and smelling the

fire was associated with

higher distress.

Structure damage

� Blast and following fire

destroyed most of the fuel

depot.

� Estimates up to 1 billion � Estimates up to 1 billion

euro in damages.

� BP part survived but is

still not in operation.

Economical damages

� 76% of the surrounding

households had experienced

some damage

� Some 92 firms on the � Some 92 firms on the

Maylands business park,

employing about 9,500

people, were directly

affected by the explosion.

Economical damages

� The incident cost firms more

than £70m, according to a

study by the East of England

Development Agency.

� About 1,422 jobs were

relocated and 79 people lost

their jobs.

Air Quality

� Particulate Measure (PM)

� 10, 5, 1

� 10 is harmful

� 5 and 1 get into system,

potentially very harmful

Air Quality

� NETCEN has estimated that

8000 tonnes of PM10 particles

have been released = 6% of

total annual emitions in UK.total annual emitions in UK.

� Plume was mainly black carbon

soot.

Air Quality

� No significant increase in

ground level polution.

� High buoyancy of the plume

resulted in bulk of emisions resulted in bulk of emisions

being trapped aloft, above cold

layers of air.

� Explosion in summer would

have caused far higher air

polution.

Water quality

� Fires were put out using fire

fighting foam

� Non dissolvable and not � Non dissolvable and not

biodegradable

� Big volumes of water, oil and

foam after fire had been put

out.

Water quality

� 26 million litres of

contaminated water used to

fight the blaze is stored

� During the years some

800,000 litres of stored water

was found to have leaked into

the Colne from the Blackbird

sewage treatment works.

Water quality

� ‘Fire water’ (water, oil, foam)

caused elevated levels of

ground water contaminance

but below concern levels.

� Concentration of PFOS in

drinking water was below 3

micrograms/litre which is

indicated as “unlikely to cause

health problems” by HPA.

Reputation

Chevron Stock price 2003 - 2007

Lawsuit damages

� Some 3,300 claims, worth a

potential £700m, have been

filed by individuals, loss

assessors and companies. assessors and companies.

� Of the claims, there are about

250 from individuals, which

total £20m, and 2,754 out of

the 3,300 claims are for less

than £10,000.

Summing upSumming up

Conclusion

Conclusion

� On December 11th 2005 the

Buncefield depot exploded

� Cause: Tank overflow > vapour

cloud

� Ignition source is still under

investigation

Conclusion

� Due to ongoing criminal

investigation, information

about the organisational

factors can not be made publicfactors can not be made public

� No fatalities

� Mainly structure damage

� Limited damage to

environment