Preliminary Assessment/Site Inspection
The Preliminary Assessment (PA) and Site Inspection (SI) are used by EPA to evaluate the potential for a release of hazardous substances from a site.
An assessment of information about a site and its surrounding area. A Preliminary Assessment is designed to determine whether a sites poses little or no threat to human health and the environment or if it does pose a threat, whether the threat requires further investigation. PA investigations collect readily available information about a site and its surrounding area. The PA is designed to distinguish, based on limited data, between sites that pose little or no threat to human health and the environment and sites that may pose a threat and require further investigation. The PA also identifies sites requiring assessment for possible response actions. If the PA results in a recommendation for further investigation, a Site Inspection is performed. The EPA publication Guidance for Performing Preliminary Assessments Under CERCLA, September 1991, (NTIS PB92-963303, EPA 9345.0-01A) provides more information on conducting PAs.
identifies sites that enter the NPL Site Listing Process and provides the data needed for Hazard Ranking System (HRS) scoring (Introduction to the HRS) and documentation. SI investigators typically collect environmental and waste samples to determine what hazardous substances are present at a site. They determine if these substances are being released to the environment and assess if they have reached nearby targets. The SI can be conducted in one stage or two. The first stage, or focused SI, tests hypotheses developed during the PA and can yield information sufficient to prepare an HRS scoring package. If further information is necessary to document an HRS score, an expanded SI is conducted. The EPA publication Guidance for Performing Site Inspections Under CERCLA; Interim Final, September 1992, (NTIS PB92-963375, EPA 9345.1-05) provides more information on conducting SIs.
Information collected during the PA and SI is used to calculate an HRS score. Sites with an HRS score of 28.50 or greater are eligible for listing on the NPL and require the preparation of an HRS scoring package.