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Desk Study Preliminary Risk Assessment

What is a Desk Study Preliminary Risk Assessment?

Preliminary Risk Assessment goes by many names including PRA, Phase I and desk study. The Preliminary Risk Assessment is a qualitative risk assessment process that involves collecting and reviewing largely desk-based information including historical, archival and contemporary information to establish where previous activities  that may have contaminated the land were located, and what types of contamination may be expected to be present.

The purpose of the Desk Study is to develop a conceptual model, identifying potential sources of contamination, migratory pathways and sensitive receptors. Together these form a source pathway receptor linkage. If these three elements are identified, a risk assessment will be completed to determine what action, if any, is needed.

How much does a desk study cost?


A site investigation desk study usually consists of a number of historical maps, a search of private and publicly available database information and a site visit. The information is reviewed, source pathway receptor linkages identified, a risk assessment completed and a conceptual site model (CSM) drawn of the site. Depending on the size and complexity of the site, costs typically range from £600 to £1000 (excluding VAT). Significantly cheaper assessments may be missing information such as an appropriate site visit or a detailed CSM.

If the PRA concludes there are unacceptable, unquantified or unknown risks, it may be necessary to carry out a Site Investigation.

Risk management matrix chart with pen an
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