Climate change and remediation – changes afoot? 

Joanne Kwan (CIRIA), Claire Dickinson (Geo-Environmental Matters) & Paul Nathanail (GHD)

97% of respondents to CIRIA’s ‘Climate and Contaminated land Survey’ carried out at the end of 2020 think climate change will affect their contaminated land projects in the future but 56% do not know if they are managing the risk well enough. 

The survey also revealed 60% of respondents had not yet considered climate change in contaminated land projects, something that will no doubt change following the replacement of CLR11, which did not mention climate change, with the Land Contamination Risk Management (LCRM). LCRM will help “factor in climate change to ensure site works and any long term remediation is sustainably robust”.

Climate change continues to be a global challenge.  Although, the UK has declared a ‘Climate Change Emergency’, and the current and future National Planning Policy Framework (NPPF) (out for consultation until 27 March 2021) is prioritising the use of brownfield land, which is often contaminated, there is no UK guidance on how to manage climate change risk in land quality assessments and remediation.  Furthermore, understanding within the contaminated land community on the topic of climate change, other than the risks from fluvial flooding and surface water flooding, is low.

So what are the issues? And why do we need to change our practices?

There is an urgent need to consider extreme weather events in land quality assessment and in the design of remediation projects if we are to prevent some of the more foreseeable risks occurring, including:

  • Changes in temperature that can affect biochemical and chemical properties of contaminants and therefore their behaviour.  It will also alter the effectiveness of some remediation systems e.g. bioremediation, MNA.
  • Extreme weather events e.g. flash floods, freezing, landfill fire, wild fire.  Increased run-off from contaminated stockpiles.  Increased mobilisation of contaminants by flooding. Low pressure events causing tidal surges inundating coastal contaminated sites and mobilising contaminants or releasing landfill leachate into the natural environment. Prolonged drought desiccating clay caps causing them to crack.
  • Intense rainfall reducing land stability and increasing erosion of the UK’s 1200 coastal landfills or more recent sediments.  Breaches can expose waste allowing it to pollute the environment and enter the food chain by being consumed by fish and birds. 
  • Contaminated sediments being redeposited onto farmland by flood waters where they can affect livestock and crops. 

Furthermore, climate change may become an ‘uninsurable’ pollution risk, something that was alluded to at a recent CIRA Climate Change event. Many Insurers are concerned with:

  • sites with long term contamination management and containment systems 
  • possible regulatory review of previously approved schemes resulting in increased monitoring or remediation requirements

As LCRM is implemented, remediation designs will need to be demonstrably resilient to extreme climate events.  CIRIA is considering supporting industry and regulators through programmes to identify:

  • remediation technologies whose performance may be affected by climate change.
  • what adaptation is required by individual remediation technologies 
  • ongoing remediation projects where adaptation measures should be retrofitted 

If you want to know more and help shape the guidance that industry needs to continue to bring back in to beneficial use land affected by contamination safely then why not join CIRIA’s Extreme climate incidents and contaminated land interest group