After carrying out a detailed desktop study and walk over survey it should be possible to identify pollutant linkages and develop a preliminary conceptual site model . The conceptual site model (CSM) comprises three elements:
• Potential sources of contamination
• Potential receptors that may be harmed
• Potential pathways linking the two
The CSM is a written and diagrammatical summary of the environmental processes on a site and its surrounding area, the potentially significant sources of contamination, pathways through which contaminants can travel, and receptors that eventually could be harmed. This must be included at all stages of the Site investigation. A CSM will provide a summary of the site including details such as;
• Its current status, history, geology and hydrogeology.
• Any potential contaminants, pathways and/or receptors.
• A summary of ‘Significant Pollutant Linkages’ – where there is a potential link between the potential contaminants and receptors.
• Any uncertainty in the information collected.
The CSM is used to collate and interpret results, guide further investigation, monitor changes and communicate results of the investigation to all stakeholders. It underpins each stage of contaminated land management.
The ‘conceptual site model’ produced will depend upon the previous site use and proposed development. In some circumstances there may be a large number of plausible pollutant linkages and in others there may only be a small number. The ‘conceptual site model’ developed as part of the Preliminary Risk Assessment should provide enough detail to determine what, if anything, will be required as part of a Quantitative Risk Assessment.