Toxic waste clean-up on Olympic site cost taxpayers £12.7m

The government has spent £12.7m cleaning up a part of the Olympic site in east London that was "grossly contaminated" with toxic waste left behind under a chemical storage facility that was bulldozed to make way for the main stadium.

The contamination, on a site formerly occupied by Banner Chemicals Group, is so severe that the remediation process will continue long after the Games finish, according to Environment Agency officials.

Banner Chemicals vacated its facility on the banks of the River Lea in east London in 2006. Later investigation revealed that a significant quantity of toxic industrial solvents had mixed with groundwater. Some of the heavier chemicals had sunk through the groundwater to a depth of 40 metres and entered the bedrock below.

"We thought that this would be a dirty site but it turned out to be much worse than we expected, grossly contaminated," said Stuart Hayes, a hydrogeologist at the Environment Agency who is overseeing the clean-up operation. So far, only the topsoil has been cleaned. The next and much more difficult stage is to clean up the deeper pollution, said Hayes.

The Environment Agency says that "no one business can be identified as having caused specific pollution," but Hayes and his colleague at the agency Ian Moxon said the nature of the contamination indicated that the pollution had almost certainly come from the Banner facility.

Banner Chemicals said it was not aware of groundwater pollution when the site was bought to accommodate the Olympic development. The company said that the history of industrial development on the Olympic site meant that the pollution could have originated from a different source.

The £12.7m cost of the clean-up, which was revealed to the Guardian in a Freedom of Information Act request to the Olympic Delivery Authority should not be covered by tax payers, said Darren Johnson, chairman of the London assembly environment committee.

"We are talking about a lot of public money here, and it's money that could have been better spent buying more electric cars for the Olympic fleet or installing more renewable electricity. The polluter should pay, and I plan to raise this issue formally with the mayor of London," he said.

According to the London Development Agency, Banner Chemicals Group was paid £12.6m for the land before the Olympic development began.

Tests by the Environment Agency have detected a plume of vinyl chloride in groundwater – a product of the breakdown of chlorinated solvents, one of the main chemicals handled by Banner. Dr Jason Gerhard, a hydrogeologist based at the University of Western Ontario in London, Canada, described this as particularly worrying. "Vinyl chloride is one of the most toxic organic compounds found in groundwater and it can cause damage to the liver and nervous system." Chlorinated solvents can persist for decades in groundwater and are converted into vinyl chloride by microbes.

The director of Banner Chemicals, Colin Boyle, said that the company was not aware of any chemical leak at their east London facility. "We take our responsibilities seriously. We seek to implement best practice industry standards and to comply with all of the regulations that relate to installations of the kind we operate. You mention an incident involving some chemicals but I do not know what you are referring to and so you will appreciate that I am not in a position to comment," he said.

"There were many issues with contamination across the wider Olympic site, as one would expect given its historical industrial use. Indeed, there were a number of sites adjacent to our former site which involved contaminative uses," he added. "It is not unusual for remediation works to be carried out to make an industrial property suitable for alternative use and this work is very often carried out by the developer."

Banner Chemicals was established in 1860. Since leaving its east London facility, it has moved to a 5.5-acre site on the bank of the river Tees near Middlesbrough. According to a 2010 survey by the online magazine Real Business, it is the 25th fastest growing company in the UK, with sales of £76.2m in 2009.

Until recently, chemical distributors such as Banner Chemicals did not fall under Environment Agency regulations. In 2005, however, the law changed and officials inspected the site – but did not detect such serious contamination. According to Duane Hampton, a hydrogeologist at Western Michigan University, this is not surprising. He said: "Chlorinated solvents are hard to detect at that depth. You have to know where to look."

 Jim Pankow of the Maseeh College of Engineering and Computer Science at Portland State University in Oregon agreed. "It will be virtually impossible to clean up this spill if by 'clean up' you mean removing even 95% of the contaminant. The best that will be possible now is just to contain the spill so that the contaminated water does not leave the zone of contamination and endanger human health."

Another solution may be to inject bacteria deep underground that break down chlorinated solvents into non-toxic ethene – but it would be extremely expensive and rarely leaves the water drinkable, said Gerhard. "The cost of on-site remediation is typically in the millions of pounds and rises significantly when the pollution is located more than ten metres below the surface."

Hazel Reid, who was born near the site and now heads up Newham Tenants & Residents Federation, said: "As long as I can remember, this area has been polluted. The water used to float mauve it was so toxic. If you forgot your trainers your thumbs would fall off, we used to say."

"It's not fair that the public is having to pay to clean up the mess, but god knows if we left it to the companies to do it, nothing would happen. Someone has to pay for it, and if my 38p a week of tax goes into leaving behind something that my children and grandchildren can enjoy, then so be it," said Reid.