On February 29, 2016, USEPA issued a proposed rule to add a subsurface vapor intrusion component to the Superfund Hazard Ranking System (“HRS”).  The HRS is the principal mechanism EPA uses to evaluate sites for placement on the National Priorities List (NPL).  The National Priorities List (NPL) is the list of national priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the United States and its territories.  The NPL is intended primarily to guide the EPA in determining which sites warrant further investigation.

Previously,  the HRS was based upon ground water migration, soil exposure, surface water migration, and vapor migration pathways were not considered.  The proposed rule would expand the number of available options for EPA to evaluate potential threats to public health from releases of hazardous substances, pollutants, or contaminants.

This addition will allow an HRS evaluation to directly consider human exposure to hazardous substances, pollutants, or contaminants that enter regularly occupied structures through subsurface intrusion in assessing a site’s relative risk, and thus, enable subsurface intrusion contamination to be evaluated for placement of sites on the NPL.

There will be a sixty-day public comment period.  The proposed rule can be viewed at http://www.epa.gov/superfund/hrs-subsurface-intrusion