The Superfund remedial site assessment (aka remedial site evaluation) process evaluates sites to determine and recommend the appropriate responses to releases of hazardous substances to the environment. During the site assessment process, EPA, states, tribes, and other Federal government environmental programs collect data to identify, evaluate, and rank hazardous waste sites based on Hazard Ranking System (HRS) criteria. The HRS is a numerically based screening system that uses information from initial, limited investigations to assess the relative potential of sites to pose a threat to human health or the environment. It is the principal mechanism EPA uses to place uncontrolled waste sites on the National Priorities List (NPL). Sites with HRS scores of 28.5 or greater are eligible for placement on the NPL. Only sites on the NPL are eligible for Superfund-financed remedial actions. The following diagram shows how sites flow through the Superfund site assessment process.
The Superfund site assessment process typically begins with site discovery or notification of a release or potential of a release into the environment and/or notification to EPA of hazardous waste activity by citizens, states, tribes, or other environmental programs. However, with Federal facilities, the process starts when the facility has been listed on the Federal Agency Hazardous Waste Compliance Docket (Docket).
Following notification, non-Federal sites undergo pre-CERCLIS screening to determine whether the CERCLA site assessment process is appropriate. Federal facilities bypass this step since CERCLA mandates a preliminary assessment at each site placed on the Docket. Once a potentially hazardous site is identified as appropriate for the site assessment process, it receives a site discovery date and is added to the active CERCLIS site inventory. Using criteria established under the HRS, EPA and/or its state and tribal partners or the appropriate Federal department or agency then conduct a Preliminary Assessment and if warranted, a Site Inspection or other more in-depth assessment to determine whether the site warrants short - or long-term cleanup attention. Sites that do not warrant further interest are assigned a No Further Remedial Action Planned (NFRAP) decision. Sites that do warrant further removal - or remedial-type study are referred to appropriate cleanup programs for further work. These cleanup programs include EPA removal, RCRA, state/tribal cleanup programs such as Voluntary Cleanup Programs (VCPs), the Superfund Alternative Approach (SAA), and the National Priorities List. At the conclusion of each assessment, the HRS model is applied to derive a preliminary site HRS score. Sites with preliminary HRS scores below 28.5 generally require no further Superfund remedial interest and are assigned a NFRAP decision. The NFRAP decision can also be made at sites with preliminary HRS scores of 28.5 or higher if EPA determines the site would receive a no action Record Of Decision (ROD) if it was placed on the NPL. Most of the sites assessed for potential NPL listing are screened out of the program.