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Development of Category 4 Screening Levels for Assessment of Land Affected by Contamination

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A methodology for developing Category 4 Screening Levels (C4SLs) has now been published.

In 2012 the revised Contaminated Land Statutory Guidance introduced a new four category system for classifying land as contaminated under Part 2A of the Environmental Protection Act 1990.

This category system ranged from Category 4, where the level of risk posed to human health or the environment is acceptably low, to Category 1, where the level of risk is clearly unacceptable.

To help regulators determine whether land was suitable for use and definitely not contaminated, a project research group was established to define the screening level for Category 4. 

This project has now been completed. A methodology for developing Category 4 Screening Levels (C4SLs) has now been published along with C4SLs for six substances that are commonly identified in contaminated land risk assessments. These are:

  • cadmium
  • benzo(a)pyrene
  • benzene
  • arsenic
  • lead
  • chromium VI.

The final project report can be found on the Department for Environment, Food and Rural Affairs website (external link).

To accompany the final project report (which covers both England and Wales) the Welsh Government has produced a Policy Companion Document that outlines the policy decisions made in determining the final C4SLs.