How are Risk Assessments carried out?

Risk assessments are the cornerstone of contaminated land management. They underpin the approach of both the Government and the Environment Agency, and are the essential tool for implementing Part IIA of the Environment Act.

Risk assessment is both a philosophy and a toolbox. It combines an understanding of the impact of pollutants on health and the environment together with knowledge of the behaviour of those pollutants along the pathway from their source to their target.

The starting point for an assessment of risk at a contaminated land or spill site is understanding the “pollutant linkage”. This requires the identification of three components:

• A Source (contaminant) – a substance that is in, on or under the land
  and has the potential to cause harm or to cause pollution of controlled
  waters;

• A Receptor – something that could be adversely affected by a 
  contaminant, such as people, an ecological system, property, or a water
  body; and

• A Pathway – a route or means by which a receptor can be exposed to,
  or affected by, a contaminant.

A risk only exists when all three components are present.

When the combination of contaminant–pathway–receptor is present this is described as a pollutant linkage.

Each pollutant linkage needs to be separately identified, understood and dealt with if appropriate, which is normally presented in the form of a Conceptual Model.

The conceptual model is the main focus of preliminary risk assessment, and the model is subsequently refined or revised as more information and understanding is obtained through the risk assessment process. These principles apply to risk assessment for both Human Health and Controlled Waters.

Risk assessments are undertaken using a Tiered Approach, each tier involving an increasing level of detail and complexity. The three tiers used in CLR11 are:

 I. Preliminary risk assessment (Qualitative Risk Assessment);
 II. Generic quantitative risk assessment ;
 III. Detailed quantitative risk assessment.