Screenings and Preliminary Assessments

PRELIMINARY ASSESSMENT

Under state law (ORS 465.245), DEQ conducts Preliminary Assessments (PAs) at sites where hazardous substances may pose a significant threat to human health or the environment. Compared to a screening, the PA is a more formal and detailed investigation, designed to determine whether a site is releasing, has released, or could release hazardous substances to the environment, and whether a response action is required. For a PA, the investigator compiles available data about a site and its immediate vicinity. This includes site history and operations, information on potential sources of contamination, pathways for migration of contaminants, and receptors or targets potentially affected by the contamination. The PA Report summarizes data gathered about the site and makes recommendations for further action that are as specific as possible, given the facts available. While the PA identifies whether a site could endanger human health or the environment, it is not intended to fully characterize site contamination or to quantify the magnitude of site risks.

Following a PA, some sites require sampling to determine what further actions might be needed. In such cases, an additional investigative effort and report are called for: an Expanded PA (XPA).

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