Management of legacy landfill

DOI: https://doi.org/10.58248/PN759

Landfill

Landfill is “a waste disposal site for the deposit of the waste onto or into land”, according to The Environmental Permitting (England and Wales) Regulations 2016.

Modern landfills are regulated by statutory guidance introduced in the Waste Management Licencing Regulations 1994, the EU Landfill Directive (1999/31/EC) and subsequent regulations and statutory guidance. These introduced measures to prevent the release of pollution from the site, and post-closure monitoring and management.

However, there are closed landfills (a site where waste disposal has stopped) that do not have or have never had an active environmental permit or waste control licence. There are estimated to be 21,000 of these historical landfills across England and Wales. However, researchers, industry and local authority stakeholders suggest there are uncertainties in the data for England, which creates challenges in determining how many sites there are, and their contents, size and boundaries.

In England, most of these landfills pre-date modern requirements, creating uncertainties about pollution risks. Researchers suggest there are gaps in understanding the movement of landfill contaminants through the environment and other risks that emerged after sites were closed.

Waste management and contaminated-land regulation are devolved UK policy areas. In England, the Environmental Protection Act 1990 and Contaminated Land Statutory Guidance provides the legal framework for local authorities to determine whether land is contaminated. This framework uses ‘harm’ to describe impacts to people and the environment, apart from the water environment where ‘pollution’ is used to describe impacts.

Understanding possible risks

Research suggests that contaminants can persist within closed landfill sites for significant periods; ammonium and some persistent organic chemicals may be released decades after disposal. These emissions may move through the wider environment via groundwater, surface-water and sediment transport in rivers, estuaries and coastal waters, and via emissions to air.

The UK Health Security Agency reports that there is no clear evidence of harm to human health from open well-managed landfill sites but identify major data gaps for sites that pre-date modern landfill requirements.

Research into these landfills has suggested they may contain contaminants, such as metals, organic substances, and nutrients, which may be released for centuries after closure. These may accumulate in nearby areas including in the organisms and vegetation present in these habitats.

Natural hazards such as coastal erosion and flooding can enhance or create new pollutant pathways between waste and nearby environments, while drought can damage the integrity of landfill structures making them more prone to failure and contaminant release. This is an existing and growing risk, as a significant area of the UK is predicted to be lost to coastal erosion in the next ten years. Climate change will act as a multiplier of these risks.

Campaigns have been set up to advocate for better regulation and remediation of legacy landfill sites by communities and individuals.

Remediation challenges and approaches

Local authorities are responsible for identifying and determining contaminated land. However, if the risks posed by contaminated land are severe, local authorities may designate it as a ‘special site under the Environmental Protection Act. Responsibility for ensuring that the appropriate person carries out remediation, such as the site’s polluter, then transfers to the Environment Agency.

Remediation of legacy landfill sites may require planning permission from the local planning authority, and environmental permits from the Environment Agency in England. Where cost effective, landfill materials can be excavated and disposed of or recovered (landfill mining). Hybrid approaches include partial excavation, combined with stabilising and reusing the site, with risk controls being put in place (such as installing barriers).

Landfill mining in England is often constrained by factors such as low material value and permitting requirements. Excavated materials are classified as waste, either triggering landfill tax (a levy per tonne of waste disposed of in licensed landfill sites) or new landfill permits if re-landfilled on site. The forthcoming circular economy growth plan for England may address challenges around material reuse.

Other remediation options, suggested by industry contributors and researchers, range from in-situ containment with modern landfill engineering techniques to nature-based approaches to mitigating contamination.

Local authority contributors state that the withdrawal of Contaminated Land Capital Grants in England has limited remediation of high-risk sites with low development value. They suggest that multi-year funding and clearer planning appraisal routes are required and also raise concerns that coastal landfills are not eligible for the government’s flood and erosion risk grants.

Acknowledgements

This briefing was produced in consultation with experts and stakeholders, who are listed at the end of the briefing. POST would like to thank everyone who contributed their expertise.