SCORING ON THE BASIS OF CURRENT CONDITIONS
Under the original HRS, EPA generally scored the three migration pathways based on the conditions at the site before any response action had been taken, rather than based on current conditions at the site. In revising the HRS, EPA decided that it may be appropriate to evaluate sites based on current conditions and to consider prior responses in calculating an HRS score.
The policy of evaluating sites based on current conditions raised concerns that it might:
EPA examined two approaches to incorporate current site conditions in the HRS score. Under either approach, EPA would only consider actions prior to a site inspection, which provides most of the data used to score a site. Because response action at sites may be an ongoing process, it would be burdensome to recalculate scores continually to reflect such actions. The two approaches were:
- Encourage private parties to only take action sufficient to lower the score so the site would not be placed on the NPL.
- Discourage public agencies from taking early actions that could lower the score, thus preventing the site from being on the NPL and therefore eligible for Superfund monies.
EPA decided to consider response actions prior to a site inspection because it will provide increased incentives for rapid response.
- Consideration of current conditions for certain pathways or factors where appropriate.
- Consideration of current conditions routinely, but identification of situations where initial conditions more accurately reflect risks.
EPA decided not to limit consideration of current conditions to certain pathways (for example, the soil exposure pathway) because this would overstate the risk at sites where removal of wastes has eliminated threats in all pathways and could lead to their being placed on the NPL. This approach would also provide less incentive for a rapid response action, which could lower the contamination risk in all pathways.
EPA is placing these limitations on what response actions will be considered:
- Response actions will be considered only if they actually remove waste from the site and dispose or destroy it in a RCRA-permitted facility. This approach should discourage private parties from taking only the action needed to lower the score below the HRS cutoff.
- Where EPA cannot adequately determine the amount of hazardous constituents remaining onsite, a minimum value will be assigned to the hazardous waste quantity factor.
U.S. EPA, Office of Solid Waste and Emergency Response, "The Revised Hazard Ranking System: Background Information." Publication 9320.7-03FS. November 1990.
See also U.S. EPA's online Introduction to the HRS.
For Further Information, Contact:
Hazardous Site Evaluation Division
Office of Emergency and Remedial Response
Mail Code OS-230
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
The Superfund Hotline, (800) 424-9346 in the continental U.S., or (202) 382-3000 in the Washington, D.C. area.