Historic landfill sites located near the UK’s coast could pose a serious risk to the environment if they erode due to flooding, according to a new study from Queen Mary University of London (QMUL).
There were said to be some 1264 sealed historic coastal landfill sites in England and Wales which no longer receive waste, but fall wholly or partially within the Environment Agency’s Tidal Flood Zone 3.
As part of the study, said to be the first of its kind, researchers from QMUL investigated the contents of two sites in Essex: Leigh Marshes Landfill, used from 1955 to 1967; and Hadleigh Marsh Landfill, used from 1980 to 1987, to determine the potential consequences should the sites be tidally flooded or erode.
The analysis found that 100% of the Leigh Marsh waste samples and 63% of the Hadleigh Marsh samples contained contaminants at concentrations that exceed marine sediment quality guidelines ‘probable effects levels’, which the researchers said indicated that adverse effects to flora and fauna could be expected if the waste was to erode into surrounding coastal wetlands.
The findings will form part of a forthcoming report for the Environment Agency, authored by Dr Kate Spencer, Reader in Environmental Geochemistry at QMUL, and James Brand, PhD student at QMUL’s School of Geography.
“It’s important to state clearly that we’re not saying these sites are currently eroding,” she said. “What our findings show is that in the event of erosion, there would be serious environmental consequences due to the level of contaminants that would pollute the surrounding protected ecological sites.”
The main risks to these landfills was said to come from the effects of climate change, including erosion and flooding with salt water from storm surges and higher water levels.
According Spencer, many of these sites may be vulnerable to erosion and coastal flooding in the future.
“If you take a look inside these sites, they reflect consumption and waste patterns of the time,” she said. “So one historic landfill site might contain a huge amount of plastics, and another might be full of coal ash.”
“Many of them were in use when there were no rules about what went in,” continued Spencer. “This is important because it means that we can’t draw national conclusions from individual sites – every landfill is essentially unique and some will prove more risky than others.”
Brand added that it was “important to understand the sheer scale of some of these sites”. The Hadleigh Marsh site contains 500,000 cubic metres of waste – if this waste were to erode and be released to the adjacent marsh, there is sufficient material to cover 138 football pitches to a depth of half a metre.
The study added that while a policy of relocating the waste away from vulnerable sites would be preferable, it is likely that the waste will continue to be protected in situ due to the enormous costs and risks associated with relocating the waste.
The researchers said that the next stage of their work will create a vulnerability index for historic coastal landfill sites, to determine where resources and attention might best be focused.
The Environment Agency defines landfill sites as: A historic (closed) landfill site is one where there is no PPC permit or waste management licence currently in force. This includes sites that existed before the waste licensing regime, if a site has been licensed in the past, and this licence has been revoked, ceased to exist or surrendered and a certificate of completion has been issued.
