EPA Considering Revising HRS to Include Vapor Intrusion Pathway

The Hazardous Ranking System (HRS) is a regulation issued by EPA for scoring sites for inclusion on the National Priorities List (NPL). Risks posed by various exposure pathways are assessed and then numerical values are assigned. Sites are evaluated that score above 28.50 on the HRS are eligible for proposal to the NPL.

The principal driver for a high score on the HRS is contamination of drinking water. Because vapor intrusion was not a regulatory concern when the HRS was revised in 1990, the vapor intrusion pathway is not one of the pathways that are evaluated when scoring a site. However, in a critical report earlier this year, the GAO suggested that the vapor pathway be evaluated when ranking sites for the NPL.

I learned today at a vapor intrusion meeting at EPA region 2 that EPA is in the evaluating revising the HRS to specifically include the vapor intrusion pathway. If this change is implemented, it could mean that sites could be listed solely on the basis of vapor intrusion. This could dramatically expand the universe of sites eligible for the NPL. For example, GAO estimated in its report that if the VI pathway was used to rank sites, possibly 20 sites in New Jersey alone could be eligible for inclusion on the NPL.