For the first time, EPA has proposed to add a property to the National Priorities List (“NPL”), otherwise known as the Superfund list, based solely on the risk of vapor intrusion. The NPL contains the worst contaminated, highest priority properties in the United States. Before the rules were changed effective in May 2017, EPA added properties to the NPL based on a release of contamination to soils, surface water, ambient air and/or groundwater only. The new rule, however, allowed EPA to evaluate risk to human health from intrusion of contaminants into an occupied building from vapors or groundwater existing in the subsurface below the building. (The majority of subsurface intrusion results from vapors, but not all.)
Although several states have started to take action to address or require remediation from subsurface intrusion, this is a significant step by the federal government. The proposed site is the Rockwell International Wheel & Trim Site in Grenada, MS. EPA will be taking comments on the proposal until March 19, 2018.
It has been estimated that thousands of sites across the country are subject to subsurface intrusion. EPA and many states have indicated that they will reevaluate even those properties that were not previously included on the federal or state lists of contaminated sites following an assessment based solely on analyses of the four previously recognized exposure pathways. Property owners had not had any concrete examples of how the new rule would be used to evaluate risk until now. Review of the agency’s scoring of this site using the revised Hazard Ranking System will be instructive of how EPA may score other properties in the future.