Vapor Intrusion Update
February 2012 -- Vapor intrusion (VI) is a process by which chemicals in soil or groundwater migrate to indoor air above a contaminated site. VI first hit the regulatory scene in 1993 when people began to first realize that this was a primary pathway to be exposed to suburface contamination. As a result, requirements were initally established governing assessment and cleanup requirements for contaminated sites. After a decade, VI gained momentum after it was discovered that the severity of the VI issues was initally underestimated. Since then, staying abreast of all the varying requirements and guidance among the states (and the multitude of regulatory departments within each state) has been challenging, to say the least.
There are currently three different agency programs (Brownfields, Inactive Hazardous Sites, and DSCA) that can impose VI assessment requirements on your property in North Carolina, with more in the works. Each program has its own VI criteria and assessment guidance, which vary considerably. On top of that you have various guidances and standards under EPA, ASTM and ITRC that vary in approach to each other, including the North Carolina guidance, and are used by many to establish an “industry standard” for assessing the risk associated with VI. Even when the applicable guidance is clear, work plan revisions are often imposed to accommodate variances requested by different State regulators among different regional offices. To make matters more complex, North Carolina is currently consolidating their three program VI guidance documents into one “Division-Wide” (i.e. Division of Waste Management) document for consistency. This document is currently scheduled to be ready in March 2012. At the same time, however, EPA is considering changes that will make thevapor intrusion pathway even more stringent, which will effect current VI guidance efforts at the State level.