THE DESIGN of future hazardous waste landfill sites will have to be radically overhauled after the Environment Agency discovered that contaminant levels take much longer to fall than previously thought.
Sites will either have to be beefed up so that they last 1,000 years or have chemical processes designed into them, to increase the rate at which their toxicity declines.
The Agency will be forced to update its approach to landfill after research revealed that it takes at least 1,000 years for contaminant levels to fall to acceptable levels.
Until now it was believed that contaminant emission rates in hazardous landfills would fall to sufficiently low levels by the time a landfill liner deteriorated to achieve 'equilibrium status' in a few decades.
But the research, carried out for the Agency by consultant Golders, has revealed that even lower level waste classified as hazardous from July next year under the Waste Acceptance Criteria takes more than 1,000 years to reach equilibrium status.
'We're now talking 1,000 years not decades, as thought, ' said Environment Agency landfill policy manager Jan Gronow, speaking at a conference on Optimising 21st century Landfill organised by sister title New Civil Engineer.
Gronow added that half of all hazardous waste required more than 2,000 years to stabilise.
Financial provision is currently made to deal with a 50 to 100 year 'aftercare' period, she said, and a new 1,000 year strategy would now be required.