Hundreds of landfill sites have become vulnerable to coastal erosion as climate change causes sea levels to rise.
Costs could run into millions of pounds, as the sea exposes waste in both known and unrecorded sites.
The concern is raised in new guidance from the Construction Industry Research and Information Association (Ciria), issued ahead of a conference next month.
Ciria said it produced the guidance because erosion and flooding could contaminate beaches and waters “more frequently as a consequence of the effects of climate change, especially [as] sea levels rise”.
It said exposure of materials in eroded landfill sites was an emerging issue, but there was “limited experience of dealing with such problems from identification through to solution”.
Climate change projections indicate that sea levels will rise at an increasing rate, according to the Environment Agency (EA).
The agency warned in a briefing this month: “There is a plausible chance of sea level rise significantly exceeding one metre by the end of the century. Such increases could lead to more sea flooding and greater coastal erosion, potentially affecting more [landfill] sites and to a greater extent.”
The Ciria guidance said responsibility for eroded landfills fell across several professional disciplines, including waste management, pollution prevention, flood and coastal management and spatial planning.
There is also potential confusion about regulatory and clean-up responsibilities, with county councils being responsible for waste disposal, districts for coastal protection and the EA for supervising landfills.
The potential costs are impossible to quantify since unknown landfills and future actions of the sea are involved. Landfill companies approached by MRW declined to discuss the matter.
“Exposure of materials in eroded landfill sites is an emerging issue, but experience to deal with it is limited”
But the Ciria guidance gave indicative costs for defences of between £2 per metre for planting dune grass, up to £5,000 per metre for a concrete sea wall.
It said that some 1,500 historic landfill sites within low-lying coastal areas or estuaries in England and Wales were at risk of flooding. A further 100 historic sites could become at risk through rising sea levels. There are also 184 permitted sites in low-lying coastal areas.
None of these figures includes Scotland and Northern Ireland.
There are also potential dangers where waste was dumped to reclaim land.
Ruth Tyson, a land quality specialist at consulting engineer Royal Haskoning DHV, which helped Ciria produce the guidance, said: “There are hundreds of sites that could be affected - not just on the east coast, which is prone to erosion, but elsewhere too.”
One is at Northam Burrows, near Westward Ho!, Devon, where erosion caused waste to emerge from a low cliff last autumn (pictured, above). Torridge District Council installed rock armour boulders as protection ahead of high tides, and decided at a meeting last month to install monitoring equipment and make regular inspections.
Solutions need not be costly. The guidance cited a case study at West Dorset District Council, which has decided to monitor the eroded Spittles Lane landfill near Lyme Regis and clear up debris as needed.
West Dorset District Council’s head of public health Jeanette Guy said it was impossible to build defences economically on a coast so prone to erosion, and that the waste exposed had not resulted in any contamination.
Hazardous waste washed out from quarry
Trow Quarry, near South Shields, was filled with waste between the 1960s and 1980s and then capped for use as a public open space.
Most was non-hazardous waste, but some was a danger to the environment and health. It was being washed out from the coastal margin by processes of erosion and deposited on the adjoining foreshore or washed into the sea, Ciria explained.
An investigation found asbestos, arsenic, cyanide, diesel and syringes among waste present. It was decided to build a rock defence barrier in 2008 sufficient to reduce coastal erosion risk for the next 50 years.
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