There are more than 1200 historic landfills in coastal areas in England which are at risk of flooding and erosion and this is likely to increase in the future as a consequence of sea level rise. There are no recognised methods to assess the impact of eroding wastes into the marine environment, but the potential hazards arising from such sites may be geological in their timescales.
In less developed coastal areas, shoreline management plans (SMPs) seek to allow natural physical processes such as erosion to progress. However, where a landfill is present, there may be a requirement to defend the shoreline to protect people and the environment from hazards that could be released. Therefore the presence of landfills can constrain SMPs.
The University of Southampton obtained funding from NERC to better understand the long-term management of coastal located landfills on dynamic coasts and assess different management approaches to the problems that such sites pose. The project estimated the long-term impact of coastal processes under different sea level rise scenarios on three selected landfills and investigated different management options to prevent pollution, including removing the waste material. The project sought to apply and build on the guidance presented in CIRIA C718, “Guidance on the management of landfill sites and land contamination on eroding or low-lying coastlines”
The case-study sites were selected from sites on the South coast of England from Lyme Regis in the west to Shoreham-by-Sea, 115 miles to the east. The area encompassed three County Councils (Dorset, Hampshire and West Sussex) and four unitary authorities including Southampton and Portsmouth. In addition to the unitary authorities the area covered 12 local authorities.
Stakeholder involvement helped select 3 case-study sites as contrasting situations from a total of over 148 historic landfill sites that intersected the 1 in 200 year flood level and from 60 sites threatened by erosion in the next century. One site is currently on a cliff top and is eroding into the sea. The second landfill sits behind an existing coastal defence structure and is constraining options for managing and adapting the shoreline management plan. The final site is an example where a landfill is protected by informal coastal defence structures in a low wave energy estuarine environment. In each case, the impact of potential rises in sea level over the next 100 years are considered in the context of landfill management, including landfill removal and remediation, and shoreline management planning.
The detailed case-study reports of the three sites can be downloaded from the links below.
As a result of this research, the Environment Agency funded CIRIA to issue supplementary guidance on the management of coastal landfills (SP169 available from the CIRIA website). The University of Southampton research team worked with researchers from Queen Mary University of London and SCOPAC (Standing Conference on Problems Associated with the Coastline) to produce the guidance which highlighted (1) the need for greater understanding of the amount, character and impact of waste that could be released from a landfill site, (2) the need to address regulation of waste eroding from coastal landfills, (3) significant gaps in information on erosion rates and impact of sea level rise on future erosion at specific sites, and (4) and the absence of funding sources to address problems at these sites.