The Hazard Ranking System (HRS) is a process used by Site Investigations, whereby a particular site is scored based on prior assessments and investigations performed which revealed contaminants at elevated levels. Through a series of analyses and data gathering activities, a score is calculated based on issues such as source types, the containment of those sources, and existing or potential targets that could be affected by the contamination revealed in association with the site. Essentially, the HRS assigns a score indicating the relative risk at a site. In order for a site to be proposed for placement on the National Priorities List, a list of sites qualifying for federally funded long-term cleanups, a site score must be at or above 28.50. To learn more about the HRS, you may refer to the Site Investigations Guidance Documents, located at the link listed above.
The General Indiana Scoring Model (ISM) uses information gathered during assessments/research to calculate a score for the site, which indicates whether the site may be placed on the Commissioner's List of sites that qualify for state-funded remedial actions. The ISM is a less-rigorous scoring model than that used in the HRS. In order for a site to be placed on the Commissioner's List, the total site score must be at or above 10.
The PA/SI and IA combine activities usually completed during a Preliminary Assessment (PA), such as site reconnaissance and initial information gathering, with activities completed during the Site Investigation (SI), such as a review of available data and field sampling. These have been combined in order to reduce repetitive tasks as well as the costs at sites that clearly need an SI before a full PA is completed.
Abbreviated Preliminary Assessments
According to the U.S. EPA, regions have found that they can often determine a site's status in the Superfund site screening process and whether it should be removed from the process altogether, with less information than is required for a conventional PA.
Pre-CERCLIS Screening Assessments
All sites referred to IDEM's attention are screened before they are entered into CERCLIS. In this way Pre-CERCLIS screening can reduce the number of sites unnecessarily entered into CERCLIS. Screenings also provide a useful tool in assuring that those sites that are entered into CERCLIS are further assessed for their risks to human health and the environment. It is then determined whether Federal response action (removal action, remedial action, oversight) is needed.