CERCLA (Superfund) Site Assessments

OSE evaluates sites using the Superfund remedial site assessment process, to determine and implement appropriate responses to releases of hazardous substances to the environment. During the site assessment process, OSE collects 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).

Following discovery, OSE typically uses the HRS model 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. Sites with preliminary HRS scores of 28.5 or greater are examined by OSE in a series of investigations designed to build a scientifically and legal defensible data set justifying the site’s placement on the NPL.  Non-federal sites on the NPL are eligible for Superfund-financed remedial actions.  (See Chart below)

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; Nuclear Regulatory Commission (NRC); and state or other federal cleanup programs.  In some cases, the CERCLA site assessment process may be delayed if a site is being actively investigated and remediated under Illinois EPA’s voluntary Site Remediation Program.  

Special Projects

Items framed in red are performed by Office of Site Evaluation

  1. Text and graphic adapted from: S.EPA Superfund Program Implementation Manual 2017.