The Desk Study research and site reconnaissance should form the initial phase of any site investigation prior to development. The aim of the ensuing report is to identify and quantify the potential risks associated with geotechnical, environmental or contamination hazards of a site.
A Desk Study is a compulsory requirement for many local authorities in their planning application process. It is the responsibility of the local authority to apply due scrutiny to developments to ensure they meet the requirements of current guidance and legislation.
A Desk Study can be used as part of a pre-purchase assessment. Since its introduction in 2012, the National Planning Policy Framework has encouraged "the effective use of land by reusing land that has been previously developed (brownfield land)". Much of this brownfield land lies within towns and cities with excellent access to existing infrastructure. However, sites such as these may conceal unforeseen hazards and if acquired can result in the transfer of costly liabilities.
Depending on the requirements of the report and the individual site setting, the desk study will research various sources of evidence to identify all hazards which will pose developmental considerations. These sources of evidence include historic maps, geological maps, aerial photography, coal mining records, public data, archival records and environmental registers. From these sources, hazards are identified which may include former landfills, mining activity, geological instability, contamination sources, pollution controls and incidents.
The site reconnaissance forms a crucial aspect of a desk study, this can identify potential issues to the proposed development and help inform later site investigation works which are unrecorded in the research data. This may include asbestos containing materials in buildings, buried or overhead utilities, access restrictions and illegal dumping of waste. Valuable information may also be gleaned from the current occupiers of the site or members of the public, this may include information unrecorded in the research data or unobserved during the reconnaissance.
The findings of the Desk Study are then summarised into a Conceptual Site Model (CSM) which identifies the potential sources of contamination and pathways to on-site and off-site receptors. The CSM should be viewed as a living document, which is revised as additional information is obtained. Where no potential hazards or linkages are identified then further investigation may be unnecessary, however, where hazards with active linkages are identified then these will require further investigation.