In 1959 several 40-gallon steel drums were dumped at what was then known as the West Ham tip.
Buried under 3.7m of earth in a cesspool, they contained metal and brickwork from a local factory. The drums' contents were contaminated with a radioactive material described as 'an isotope of thorium with some derivatives', according to a 1972 memo.
The lanndfill site was closed in 1967. It has since been capped and had a housing estate and park built on top. Little attention had been given to the radioactive waste that lay beneath. Until now.
In 2012 the world's greatest cyclists will be pedalling furiously across the former West Ham tip in pursuit of Olympic Gold medals. Construction of the London Games' Velopark which comprises an indoor cycle circuit and an outdoor BMX track, is due to begin in 2009.
Land preparation, meanwhile, has already begun, and the prospect of radioactive waste being unearthed has understandably alarmed local residents.
Nuclear waste in this small section of the 200ha site is one example of the many clean-up challenges facing remediation contractors Nuttall and Morrison who are expected to gain full access to the Park lands in July, after compulsory purchase orders are completed.
Morrison is responsible for cleaning up the northern half of the site, Nuttall the south. Both have launches site investigations on already-vacated parcels of land dotted around the Olympic Park.
So far Morrison has begun clearance work in the north of the park and Nuttall has started clearing the site for the 2012 Olympic pool, the Aquatics centre, will stand.
Both contractors have been banned from talking to the press by their client the Olympic Delivery Authority (ODA). With no one willing to reveal what they have found in the ground so far, the vacuum has been filled with wild speculation in the mainstream media that the Park is the most contaminated site the world has ever seen.
In an attempt to unearth the truth, I went to East London and walked the Olympic Park site with a remediation specialist.
'I don't think there's anything on this site that would faze the likes of Nuttall and Morrison, ' says GRM Development Solutions director Chris Jerram, standing on the bank of the River Lea.
With the exception of radioactive waste, he says, the majority of contaminants on the site will be typical of those found on post-industrial brownfield developments the length and breadth of the UK.
When the site in the Lea Valley was first earmarked for the London 2012 park, the London Development Agency commissioned Capita Symonds to carry out an assessment of the likely impact of the scheme on land and water quality.
This assessment, published in 2004, revealed a variety of past industrial uses including electricity generation, compensation reservoirs, brickfields, gas works, wharves, mills and distilleries.
Additional historical evidence points to factories producing soap, matches, ink, dyes, paraffin, patent manure, rubber, creosote, fertiliser, varnish, electrical goods.There was also a bone-rendering plant on the site.
The area was heavily bombed during the Second World War, so, according to the ODA's own risk assessment, it is highly likely the site contains unexploded ordnance. It contains a variety of vegetation, including an officially estimated 4ha of Japanese Knotweed (NCE 8 February).
A walk around the site also reveals that much of it is popular for dumping and fly-tipping, the mountain of tyres near Pudding Mill Lane station to the south of the site being just one example.
But, says Jerram, all of these problems can be dealt with.
The ODA has appointed 14 specialist subcontractors to work with Nuttall and Morrison and the techniques employed will include abestos removal, soil stabilisation, soilwashing, groundwater remediation, thermal desorption, complex sorting, bioremediation, ground barriers, dredging, and demolition.
It is understood that the ODA has also appointed a number of nuclear waste specialists to assess the Park's radioactive levels. As well as the thorium beneath the VeloPark, it is likely that the Park is contaminated with radium from a factory which once produced luminous paint.
A radiological survey of the old West Ham tip by Atkins in 1994 failed to reach a conclusion about onsite radioactive levels.
Atkins' sub surface survey went to a maximum depth of 6m, but the consultant's report acknowledges the fact that the steel drums containing the waste could have been buried as deep as 11m.
Responses to the report from by the Health & Safety Executive and HM Inspectorate of Pollution conclude that the matter only requires further investigation if the site is disturbed.
Radioactive threat aside, the large number of waterways running through the site will provide the main challenge to remediation contractors. They will need to create impermeable barriers around polluted ground near the water to prevent soluble contaminants in the ground being flushed into the water during clean up work.
Water's prevalence onsite also presents problems for the removal of Japanese knotweed, says Jerram.
'There are chemicals that will kill Japanese knotweed in one season, but they aren't supported by the Environment Agency close to water courses, ' he says.
Most likely, says Jerram, the knotweed will be dug out, but this wouldn't necessarily mean adopting the highly costly method of taking knotweed and its contaminated soil to landfill.
It could be dug out and then treated on a different part of the site, says Jerram. This applies to not only knotweed, but any form of contaminant.
'The entire site will be closed off and there will be a lot of areas within the Olympic Park that won't have buildings, ' says Jerram.
'This means there will be a lot of areas that they could move material to for remediation and it wouldn't hold the build programme up.' This is exactly what the ODA is planning. Its remediation strategy states that it intends to seek Environment Agency permission to landfill waste onsite without requiring a waste management license.
Viewing the park, Jerr says it will be the case that some sections of the park are more badly contaminated than the ODA expects, while others will be better. Because of the scale of the site, Jerram admits remediation has the potential to have a significant impact on the budget for the Games.
This was certainly a worry for Jack Lemley, when he quit his role as ODA chairman last year.
He claimed that the Government had underestimated the scale and cost of the clean up.
The current of. cial cost of cleaning up the park and surrounding areas is £1bn, and this is expected to rise when the ODA budget is announced later this month.
'You can only have a stab at overall budgetary cost at this stage, and you can only really tell the true cost once all the ground investigation is done, ' concludes Jerram.