Article Contaminated Land Laboratories

Weighing up the Risk

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Ecological Risk Assessment (ERA)

A new framework for assessing risks to ecological systems from contaminants in soils was published by the Environment Agency in October 2008, superseding the draft methodology from 2004. The new methodology is designed to establish whether pollutant linkages are likely to exist between soil contamination and designated ecological receptors, and to gather information for making decisions on whether harm to receptors is occurring or could occur in the future.

The ERA framework fits into the established structure of the Environmental Protection Act 1990 (Part 2A Contaminated Land Regulations) for assessing risks from contaminated soil and is now a standard part of contaminated land assessments where ecological receptors are identified.

As well as the contaminated land regime, the guidance is relevant to planning and pollution control, habitats and conservation regimes, and the Environmental Damage Regulations. ERA will be applicable either for assessing risks during a due diligence process or for under-writing environmental insurance. It is also appropriate for assessments relating to environmental permit applications or for justifying an appeal against an Environmental Damage Notice.

The framework follows a three-tiered process:

  1. Screening: compares chemical data to UK published soil screening values (SSVs) or with published data from other countries;
  2. Survey: the use of ecological surveys and bioassays to gather evidence of harm to receptors;
  3. Assessment: the establishment of a connection between the established harm to the species or habitat and the soil contamination.
Soil Screening Values (SSVs) have been published for twelve compounds. The assessor can use the published values or derive a “predicted environmental concentration” specific to the site, using a simple “decision tool” that is available on the website.

SSVs are based on a “predicted no effect concentration” to an ecological receptor and are, therefore, extremely conservative. Published values are lower than equivalent guideline values for human health. Exceeding SSV triggers further assessment and is not an automatic requirement for remediation.


At PBA, we have already updated our existing assessment procedures to take account of the new framework and will continue to provide a full range of contamination and ecological services to enable effective management of ecological risks from soil contamination.

Jenny Allen (Environment)

Catherine Copping (Geo)