February 09

EPA Sets Timeline for Proposed Addition of Vapor Intrusion Component to the Hazardous Ranking System

The U.S. Environmental Protection Agency (EPA) proposed the addition of a subsurface intrusion (SsI) component to the Superfund Hazard Ranking System (HRS) last week. The SsI component includes both shallow water contamination that could intrude occupied structures and homes and Vapor Intrusion (VI). The focus, however, falls on the VI exposure pathway, which can now be the sole reason for a site being added to the National Priorities List (NPL) via the HRS process.  The proposed rule will be published in the Federal Register, thereby enacting a sixty day public comment period.

The HRS is a numerical screening system that uses information from initial, limited investigations to determine a site’s potential to harm human health or the environment. Sites receive a score ranging from 0 to 100, and those with scores of 28.50 qualify for the NPL—although the EPA typically takes other factors into consideration before officially placing a site on the list. Sites on the NPL are eligible for long-term remedial action funded by the federal Superfund program.

In the proposed rule, the EPA says, “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.”

While it is not anticipated that the number of NPL sites will drastically increase, it is likely that the EPA will be paying more attention to sites with only VI potential as a larger part of the program.

The best option for sites placed on the NPL is to find the right consultant to conduct the cleanup and address VI concerns. EnviroForensics is among the nation’s leaders in vapor intrusion and sites contaminated with PCE and TCE, and our VI team possesses the skills and expertise to handle VI assessment and mitigation. Additionally, we work to secure alternative funding for our clients by locating and utilizing historical insurance policies.

VI exposure concerns have become more routinely addressed within the past few years. As VI gains better understanding and awareness, regulations on it will continue to be created. Business owners should be proactive in dealing with VI risk on their properties, and any investigation or remediation performed at a site should include a thorough VI assessment.

About the Author


Jeff Carnahan, L.P.G.

Vice President, Chief Technical Officer

Jeff Carnahan is a Licensed Professional Geologist (LPG) with over 18 years of environmental consulting and remediation experience. In his role as Chief Technical Officer, Jeff encourages and upholds the superior level of technical expertise found at EnviroForensics. His expertise has focused on the investigation and interpretation of subsurface releases of hazardous substances for the purpose of evaluating and controlling the risk and cost implications to his clients. He has amassed extensive experience working with releases of chlorinated solvents within voluntary and enforcement cleanup programs for various State agencies and the U.S. EPA. Throughout his career Jeff has provided technical support to the legal community regarding the cause, origin, timing, and cost of environmental releases. His litigation and expert opinion experience has focused primarily on chlorinated solvents and cost-recovery claims on behalf of insurance policyholders. Additionally, Jeff has over 14 years of experience in the investigation and mitigation of vapor intrusion issues and oversees the VI Assessment Team at EnviroForensics.