A Phase 1 Desk Study is an assessment of a site’s potential for contamination

The report uses various information sources to develop a “Conceptual Site Model,” which is used to determine the site’s risk rating. Assessing a sites risk from contamination involves following the procedures set out in a number of British Standards, including BS10175, CLR11 and the LCRM.

Most small developments start with a Phase 1 Desk Study. This desk-based report has various names including desk study, preliminary investigation, preliminary risk assessment or contaminated land risk assessment. They’re all essentially the same thing and form Phase 1 of the ‘Phased Approach to Land Contamination.’ We call it a Phase 1 Preliminary Risk Assessment. Cornwall Council’s useful Validation Guide “A Guide to Submitting Planning Applications” contains information on when and why a Phase 1 Report might be required, as well as what they should contain [page 25]. Our Desk Studies are carefully structured to ensure they pass through planning without a hitch.

Perhaps one of the most important sections of a Phase 1 Desk Study is the historical map review. This involves detailed analysis of historic maps dating back to the late 19^th Century, with particular emphasis on sources of contamination. An example of such would be an historic fuel station located up-slope of the site, with the potential for hydrocarbons from leaking underground tanks leaching onto the site. In this case the receptor is future inhabitants of the site, who may ingest the hydrocarbons through consumption of home-grown produce, or inhale ground gas resulting from the breakdown of the hydrocarbons.

A Phase 1 Desk Study should involve a “site walkover,” or “site reconnaissance.” This element of the report consists of an engineer/geologist making general site notes, including most importantly any signs of contamination (such as asbestos roofing, or leaking heating oil tanks). It is also useful at this stage to consider the potential for further intrusive works which may be required, and thus record any site access restraints.

Environmental, geological and hydrogeological data are acquired from a third party (Landmark Environmental Data), and pulled into the report to “complete the picture.” Examples of pertinent information include the locations of nearby abstraction licenses, background soil chemistry and geotechnical hazard data.

The above information is summarised in the conceptual side model, which takes each potential risk in turn, and evaluates its likelihood of occurrence and degree of severity. The final risk classification (high, medium or low) determines whether further work is required in the form of a Phase 2 Site Investigation.

Our team of experts are used to writing desk studies of varying scale across the country, get in touch to find out more or for a free quote!