Cristina Ortega and Emma Preston are environmental consultants at Groundsure. In this blog, they take a look at landfill sites that have been located near to the coast. If you have any comments or questions about this blog, please contact firstname.lastname@example.org
We already know that landfills are particularly harmful to the environment and, amongst other issues, produce methane, a powerful greenhouse gas1. However, coastal landfills have an additional problem of being compromised by flooding and coastal erosion with the potential of dangerous substances spilling into rivers, streets and beaches. If a coastal landfill area is not adequately managed, the combination of sea levels, storm events and coastal erosion could result in contaminates becoming mobile and therefore able to enter into coastal ecosystems 3,4,12,13,16,20.
Records suggests there are at least 1,264 historical landfill sites in England and Wales that fall within the Environment Agency’s Tidal Flood Zone 3 3,4,5,16 . Flood Zone 3 is known as an undefended area with an annual probability of flooding of 1.0% or greater from rivers, and 0.5% or greater from the sea.
In coastal areas features such as reclaimed land for ports and harbours, flood embankments and coastal defences themselves are thought, in many cases, to have been constructed using potentially contaminating waste materials (4,5). In addition to this, limited information has historically been kept on the locations and fill types of landfill sites, particularly prior to 1976 3,4,16. This means the number of landfills is likely to be in excess of known figures and that the scale of risk posed by individual sites is somewhat unknown 3,4,5. In recent years, research has begun to try to address this and establish the type and extent of contamination that exists within coastal landfill sites 3,4.
A recent study, funded by the Environment Agency and conducted by Queen Mary University of London, believed to be the first of its kind, examined the levels of toxic pollutants in two coastal landfill sites in Essex 3,4,16. These sites were Leigh Marshes Landfill, which was active between 1955 and 1967 and Hadleigh Marsh Landfill, active between 1980 to 1987 3,4,16. 100% of the samples taken at Leigh Marsh and 63% of those taken from Hadleigh Marsh were found to contain contaminants at a level that surpassed marine sediment quality guidelines ‘probable effect levels’ 3,4. This suggested that both sites would pose a significant threat to both flora and fauna if they were allowed to erode or were subject to flooding 3,4. The types of contaminants found to be present at the sites included heavy metals such as lead, as well as polycyclic aromatic hydrocarbons 4. At the Hadleigh Marsh site where the land-filled material is part of the flood embankments themselves, the research estimated that there is 9,250kg of lead, 985kg of PAHs and 125kg of cadmium, among the 77,000 tonnes of waste present 4.
The leaching of contaminated material not only presents a risk to public health and safety, but also has the potential to cause adverse biological, chemical and physical effects on the environment 4,5. This is particularly concerning given 537 of the known sites are on, or in close proximity to, bathing water catchment areas and 406 are within, or in close proximity to, sites of special scientific interest 4. Investigations conducted in Essex, the Thames Estuary and at Lodmoor landfill in Dorset examined the geochemical and physiochemical effects on adjacent marsh and mudflat environments 3,10,13,16. It was found that current and future coastal erosion is likely to lead to a significant release of contaminants from former landfills sites into adjacent ecosystems and that pollutants from landfill sites had the potential to persist in surrounding coastal systems decades after the landfill sites had closed 10,13,16,17.
Implications on Management Policy
In the light of predicted increases in flooding and erosion it has been suggested that a vulnerability index for historic coastal historic landfills needs to be created in order to prioritize management resources 4, 16. However, limited record keeping in the past poses a significant challenge to any management plans, as in many cases the locations or fill types of landfills were never logged 4,16. Even where the location is known, the lack of information on the fill means that it is likely to be necessary to assess each site independently and develop site specific management plans depending on the level of risk the fill material poses 3,4,16.
A defence-based approach was chosen at Trow Quarry located on the coast near South Shields5,18. Coastal erosion in the area meant that some of the waste material that had been deposited at the site between the 1960s and 1980s was intermittently being washed onto the foreshore and out to sea 5,18. Ground investigations revealed that the waste at the site contained asbestos, chemical compounds (such as arsenic and cyanide), heavy metals (such as lead, and mercury), diesel, petroleum organics, hospital syringes and glass 5. To prevent further releases of contaminants occurring a rock revetment was constructed and the slope was regraded to increase stability 5, 18. Although this option has reduced the risk over the next 50 years, there is still some uncertainty as to how the site will be dealt with in the long term 5, 18.
A risk management approach was taken at Spittles Lane Landfill near Lyme Regis in Dorset, where a major coastal landslip in 2008 had caused large quantities of waste including glass, metals, and other potential pollutants to be deposited on the foreshore 5, 7. The management plan put in place since the landslip involves a monitoring and sampling scheme combined with beach inspections and the collection of any waste on the foreshore deemed to pose a significant risk 5. In addition to this, provisions have been put in place to warn the public of potential risks when they arise and a strategy was developed to deal with future major incidents 5.
In summary, the ideal management solution would be to relocate waste away from sites at risk of flooding or coastal erosion in future, however due to the large costs involved it is unlikely to be feasible to do this in many cases 4. Realistically, management policy is likely to be based on the specific risks associated with each site 5. In some cases, where the risk is high or managed realignment is planned, it may be necessary to evacuate the potential source of pollution 5. In other cases, policies that provide a barrier to the source receptor pathway, such as holding or advancing the current line of defence may be more appropriate 5. However, in situations where the risks are low to medium, no active intervention or managed realignment may still be considered viable if the risks are managed 5.
Therefore, it is likely a reactive rather than preventive approach to management will be taken at many sites in the short to medium term 11. This is partially due to the time needed to establish the level of risk posed, but also due to funding limitations meaning that any prescribed management has to be viable in terms of cost benefit analysis 5, 11. This has been the case at a disused landfill site at Bray, in the county of Wicklow. Fragments of asbestos and potassium have been eroded onto the beach and about 200 meters of the tip has been exposed 2,8. Investigations have suggested a ‘do nothing’ scenario is not an option, however in the short term, inspections and removal of contaminated material when it is released is the only viable solution 8,11. This is until funds can be obtained to cover the estimated cost of up to €12 million for longer term management options, which range from protecting the toe of the landfill from erosion with rock amour to removing its entire contents 10.
Being aware if your property has been built in close proximity to a landfill is something to be considered as part of the transaction of your property. Landfill sites can potentially pose a contaminative risk as they can produce gas and leachate which can move through soils, service conduits and some types of rock strata. Furthermore, if a landfill is located directly beneath a property, structural and subsidence problems can become apparent if such issues were not taken into consideration during site design and construction. Environmental data within Groundsure reports provide information held by the Environment Agency regarding landfill sites around the UK. More information about which data is covered within our reports can be found by visiting https://www.groundsure.com/search-reports/.
- 2010 to 2015 government policy: waste and recycling. Available at: https://www.gov.uk/government/publications/2010-to-2015-government-policy-waste-and-recycling/2010-to-2015-government-policy-waste-and-recycling
- Bawden, T. (2016). Landfill dumps across UK ‘at risk of leaking hazardous chemicals’. Retrieved from: http://www.independent.co.uk/environment/landfill-dumps-across-uk-at-risk-of-leaking-hazardous-chemicals-a6887956.html
- Brownfield briefing. (2016). Contamination threat from erosion of coastal landfills. Retrieved from: https://brownfieldbriefing.com/47227/contamination-threat-from-erosion-of-coastal-landfills
- Carrington, D. (2016). Pollution risk from over 1,000 old UK landfill sites due to coastal erosion. Retrieved from: https://www.theguardian.com/environment/2016/may/05/pollution-risk-from-over-1000-landfill-sites-england-wales-coastal-erosion
- Cooper, N.J., Bower, G., Tyson, R., Flikweert, J.J., Rayner, S. & Hallas, A. (2012). Guidance on the management of landfill sites and land contamination on eroding or low-lying coastlines. Retrieved from: http://www.ciria.org/Resources/Free_publications/Landfill_on_eroding_coastlines.aspx
- Environment Agency. (2015). Flood map for planning risk. Retrieved from: http://apps.environment-agency.gov.uk/wiyby/cy/151263.aspx
- Gallois, R.W (2009). A recent large landslide at the Spittles, Lyme Regis, Dorset and its implications for the stability of the adjacent urban area. Geoscience in South-West England: Proceedings of the Ussher Society, 12(2), 101–108
- Journal.ie (2017). Asbestos and other toxic waste leaking into Irish Sea off Bray and Dublin coast. Retrieved from: http://www.thejournal.ie/toxic-waste-bray-3267083-Mar2017/
- Ledoux, L., Cornell, S., O’Riordan, T., Harvey, R., & Banyard, L. (2005). Towards sustainable flood and coastal management: identifying drivers of, and obstacles to, managed realignment. Land Use Policy, 22(2), 129-144.
- Njue, C.N., Cundy, A.B., Smith, M., Green, I.D. & Tomlinson, N. (2012). Assessing the impact of historical coastal landfill sites on sensitive ecosystems: a case study from Dorset, Southern England. Estuarine, Coastal and Shelf Science, 114, 166-174.
- O’Brien, T. (2017). Cost to clean up former dump at Bray could be €12m. Retrieved from: http://www.irishtimes.com/news/ireland/irish-news/cost-to-clean-up-former-dump-at-bray-could-be-12m-1.3014984]
- O’Shea, F., Spencer, K. & Brasington, J. (2012). Development of a risk assessment model for diffuse landfill pollution as a result of climate change. Retrieved from: https://www.researchgate.net/publication/270876315_Development_of_a_risk_assessment_model_for_diffuse_landfill_pollution_as_a_result_of_climate_change
- O’Shea, F., Spencer, K., Brasington, J. & Webb, M. (2013). Impacts of coastal landfills on the quality of estuarine environments. Retrieved from: https://www.researchgate.net/publication/263586547_Impacts_of_Coastal_Landfills_on_the_Quality_of_Estuarine_Environments?channel=doi&linkId=54b8f89c0cf28faced62649d&showFulltext=true
- O’Shea, F. & Spencer, K. (2015). Contamination of Coastal Sediments from historic landfills: a ticking time-bomb. Retrieved from: http://sednet.org/wp-content/uploads/2015/12/2015-pres3-5-FrancisOShea.pdf
- Pontee, N., & Parsons, A. (2012). Adaptation as part of sustainable shoreline management in England and Wales. Proceedings of the Institution of Civil Engineers: Maritime Engineering, 165(3), 113-130.
- Queen Mary University of London. (2016). Floods and coastal erosion may expose contents of UK landfills, study finds. Retrieved from: http://www.qmul.ac.uk/media/news/items/hss/176675.html
- Shrubsole, G. (2016). Leaking landfills – a ticking timebomb as climate change hits? Retrieved from: https://www.foe.co.uk/blog/leaking-landfills-ticking-timebomb-climate-change-hits
- South Tyneside Council (n.d) Trow Quarry. Retrieved from: https://www.southtyneside.gov.uk/article/36334/Trow-Quarry
- Turner, R., Burgess, D., Hadley, D., Coombes, E. & Jackson, N. (2007). A cost–benefit appraisal of coastal managed realignment policy. Global Environmental Change, 17(3-4), 397-407.
- University of Southampton (n.d) Coastal landfill and shoreline management: implications for coastal adaptation infrastructure. Retrieved from: http://gtr.rcuk.ac.uk/projects?ref=NE%2FN012909%2F1