Assessing the risks from land contamination: All change!
15 June 2009, News release from Atkins
The rich industrial heritage of the UK carries with it a legacy of soil contamination.
In addition, there may be naturally elevated levels of some contaminants in soils. We often need to assess whether the land we live, work and play on does not pose unacceptable risks to people. Assessment may be carried out under the planning regime, where new development is being undertaken, or under Part 2A of the Environmental Protection Act, where current use is considered, for instance if houses have been built over an old landfill.
Since 2002, contaminated land risk assessors have used various versions of the Contaminated Land Exposure Assessment (CLEA) Model and the associated framework. The model estimates human exposure to soil contamination for a number of land uses and automatically compares it to toxicological benchmarks. Defra and the Environment Agency used the CLEA Model to derive a set of Soil Guideline Values (SGVs) for selected contaminants.
In August 2008, the CLEA Model, SGVs and much of the associated framework were withdrawn to be replaced with a completely new version of the model with accompanying framework documents for consultation. Final versions were released in January 2009, although we are still awaiting new SGVs.
One of the main drivers for the updates was consultation with key stakeholders by Defra, with a particular focus on examining whether choices of human exposure and toxicological inputs used in the model might contain undue levels of conservatism. Much of the contaminated land community therefore expected that soil assessment criteria derived using the new CLEA model would be much higher. However, the complete review of recent scientific literature on contaminant fate and transport, exposure modelling and human behaviour and physiology means that assessment criteria can go down as well as up.
Our Land Quality business is in a strong position to steer clients through the implications of the new CLEA model and guidance for their sites. We have provided technical support to the Environment Agency during the development of CLEA, including audit of the CLEA software. In conjunction with CLA:IRE, we are also providing training on using the new CLEA v1.04 model.
While we wait for the Environment Agency to publish new SGVs, there is a lack of criteria to use for assessing risks to human health from soils. Atkins is deriving appropriate interim screening criteria (ATRISK Soil Screening Values), which we make commercially available. We also derive these for substances and land uses for which SGVs will not be available.
Atkins has delivered many challenging projects at varying timescales for a diverse client base and we also provide environmental services to Government departments, national agencies and regional and local authorities.
Associate Director: Land Quality, Atkins
For further information please email Atkins