Note FAN: See
Material Safty Data Sheet on a fire-fighting foam called
AFFF 3% Foam Concentrate - PN#04426. Manufactured by Amerex
February 7, 2006
The Guardian (UK)
Toxic legacy poses a giant problem
Officials ponder what to do with huge quantity of contaminated
By Ian Sample,
In a corner of Maple Cross sewage treatment
works near Rickmansworth in Hertfordshire lies a 12m-litre problem
that fails to go away. It is the
forgotten legacy of the inferno at Buncefield oil depot in December
- six giant settlement tanks full of spent firefighting foam,
black water and a long list of toxic contamination.
It took 500 tankers five weeks to bring here the dirty mixture,
known to environmental officers as "firewater". During
the 60-hour battle to contain the blaze, the foam and water used
by 650 firefighters collected behind a protective bund, a wall
designed to contain the spill if an oil tank on site ruptured
its contents. For now, the firewater is safe, held in 20 metre-deep
concrete tanks beyond the cesspools and pipes that criss-cross
the 50-acre site.
"During the firefight we knew we needed to get it off site,
because the bund was filling up like a bath with the taps full
on," said Colin Chiverton, who heads the team dealing with
the foam for the Environment Agency. "But what to do with
it next is uncharted territory."
When the first tankers arrived at Maple Cross little was known
about the firewater's toxicity. The blaze was so large that 16
forces from around the country were brought in to tackle it, bringing
what foam they could lay their hands on. Scientists puzzling over
what to do knew they were dealing with a host of toxic chemicals
used to make the specialised oil fire foams. But also lurking
in the liquid was a host of toxic substances released by the fire
Scientists at the Environment Agency and Thames Water, which
owns Maple Cross, sent samples of the firewater to labs in Cardiff,
Leeds and Hampshire to look for more than 40 contaminants they
feared might be there. Many tested positive. "We know enough
to say we cannot allow this to get into the environment, either
the ground or the water," said Mr Chiverton.
Officials are most concerned about a toxic
substance called PFOS or perfluorooctane sulphonate, a chemical
used in some firefighting foams that does not break down in the
environment. Instead, it accumulates in organisms and works its
way up the food chain, where it can become a serious problem.
Following an Environment Agency report on PFOS, the Department
for Environment, Food and Rural Affairs (Defra) moved to phase
it out, but so much foam was needed at Buncefield that fire brigades
were forced to bring their old PFOS-containing stocks as well.
The lab tests revealed other toxic substances too, including zinc,
which is toxic to aquatic animals, and Pahs or polyaromatic hydrocarbons.
Another substance, MTBE, was also picked up. Before the lab tests
were complete it was clear that disposing of the firewater was
going to be fraught with difficulty. Government officials were
initially keen to see if it could be made safe by running it through
the sewage treatment works, but the plan was quickly ruled out.
"If we try and pump it from the settlement tanks into the
treatment works it will immediately foam up like bubble bath.
Our pumps like pumping liquids and if they try to pump foam, they
will destroy themselves," said Dave Wiltshire of Thames Water.
The problem became apparent when tankers arrived from Buncefield:
as they released firewater into the tanks they brimmed with a
head of foam one metre high.
Simply adding an antifoaming agent to flatten
the froth is a non-starter. Antifoaming chemicals are made from
oils, the one substance the foam is specifically designed to be
resilient to. The lab results showed that even if the firewater
could be safely pumped into the sewage treatment process, doing
so could be catastrophic. The problem lies with what is
called the chemical oxygen demand of the firewater - the amount
of oxygen a substance consumes as it breaks down. Tests showed
that the firewater was so full of organic chemicals that it would
suck up nearly 500 times as much oxygen as the normal household
effluent the treatment works is designed to handle. The vast tanks
of bacteria used to digest waste into harmless byproducts would
quickly suffocate and die through lack of oxygen.
"If the beds of bacteria go and die on us, we won't have
a working treatment facility and that would be a major problem.
We deal with waste from hundreds of thousands of homes from Hemel
Hempstead to Watford and St Albans," said Mr Wiltshire. "If
you released this into a river, it would use up so much oxygen,
it would knock it out. Nothing could cope with a shock like that,
not even our treatment works."
The biggest problem remains the PFOS. The
huge tanks of bacteria at Maple Cross cannot break it down, so
passing it through the treatment works will not remove it from
the firewater. Since the treated sewage from Maple Cross runs
into the River Colne, a tributary of the Thames which several
water companies extract from downstream, it is a risk neither
the Environment Agency or Thames Water will take.
Efforts are concentrating on ways of either extracting the PFOS
from the firewater, or finding a more radical solution. One surefire
way of disposing of PFOS is high temperature incineration, available
at two sites in Britain, Ellesmere Port in Cheshire and Fawley
in Hampshire. "The only problem is that water doesn't incinerate
very well," said Nick Cartwright of the Environment Agency.
For now, it is up to specialised consultants brought in by the
oil companies based at Buncefield to work out what to do. The
firms - Texaco, Total, Shell and BP - will foot the bill for disposing
of the firewater, which is expected to run into many millions.
"It's a case of polluter pays," said Andy de Bell, another
team member with Thames Water.
With luck, the consultants will come up with plans to deal with
the Buncefield foam in the next few weeks, after which the combined
forces of the Environment Agency, Thames Water, Defra, the Food
Standards Agency, the Drinking Water Inspectorate and the Health
and Safety Executive will be asked to agree on a way forward.
It is likely the foam will be sat at Maple Cross for some time.
"If there was a magic solution tomorrow, it would take around
five weeks to tanker it off site, but in reality, we're probably
looking at a few months before this is solved," said Mr Wiltshire.
"We've done the difficult bit. We've got it here, we've
contained it and it's not going anywhere until we're sure what
the best option is. We're certainly not going to come this far
and do something stupid with it now."
PFOS Perfluorooctane sulphonate was used in older firefighting
foams and is particularly effective against oil fires. It makes
the foam spread out into a thin layer on top of the burning oil,
smothering the flames. An Environment Agency risk assessment in
2004 recommended PFOS be phased out because of its toxicity. If
released into watercourses it builds up in fish and organisms
that feed on them. In 2001 3M, the major manufacturer of PFOs,
voluntarily stopped production of the chemical.
Pahs Polyaromatic hydrocarbons. They are byproducts of the burning
process and are also found in cigarette smoke and vehicle exhaust
fumes. Many contain the toxic chemical benzene and most are carcinogenic
MTBE Methyl tertiary butyl ether is added to unleaded fuel to
make it burn more efficiently and cut down on noxious emissions.
It dissolves easily in water, so spillages can rapidly get into
groundwater or watercourses. Very little is known about ingesting
MTBE, but animals have developed cancers after inhaling large
quantities. It makes water taste and smell awful at very low levels:
at 20-40 parts per billion, contaminated water tastes similar
11.12.05: Buncefield fuel depot explosion
Special report: oil depot explosion
Special report: firefighters
Special report: oil and petrol
Special report: waste and pollution
Steve Bell on the Buncefield oil depot fire
Oil depot explosion: archived articles
12.12.2005: First oil blazes put out
12.12.2005: Drivers face delays after depot blaze
12.12.2005: Fuel blasts close neighbouring firms
12.12.2005: Black rain will bring pollutants down to earth, warns
12.12.2005: Oil and freight industries dust off emergency plans
12.12.2005: What caused Europe's biggest blaze?
12.12.2005: 'My wife saw a mushroom cloud and said there's been
a nuclear explosion'
12.12.2005: Jackie Ashley: Millions of us have to accept we must
live duller lives
Can you see the smoke? Did you feel the blasts?
'I still can't believe I slept through the blast'
Guardian Unlimited © Guardian Newspapers Limited 2006