Today we continue our discussion on soil vapor intrusion. Some states like New York have developed detailed vapor intrusion guidance of their own. New York's guidance explicitly raises concerns about reliance on modeling and exterior soil vapor screening and encourages indoor and sub-slab sampling where there is a reason to believe that vapor intrusion may occur. A joint strategy between the New York State Department of Environmental Conservation (DEC) and the New York State Department of Health (DOH) has recently been developed to evaluate vapor intrusion pathways at all of the remedial sites in New York. The goal of the policy and guidance documents is to conduct soil vapor intrusion evaluations as efficiently and effectively as possible at all such sites. DEC's strategy is entitled "Evaluating the Potential for Soil Vapor Intrusion at Past, Present, and Future Sites."
In October 2006, DOH released a document entitled "Final Guidance for Evaluating Soil Vapor Intrusion in the State of New York." DOH's guidance complements DEC's policy by providing recommendations on how to evaluate soil vapor intrusion.
In cooperation with DEC, DOH is responsible for assessing potential human exposure pathways at contaminated sites. The guidance describes the methodology by which the state will address soil vapor intrusion at a site and will prioritize remedial sites for vapor intrusion evaluations.
The DEC/DOH joint strategy on vapor intrusion evaluations reflects the following concepts:
- Evaluations are among the top priorities of state agencies
- The likelihood of exposures varies from site to site;
- The number of sites at which vapor intrusion evaluations are warranted is quite large
- Revisiting this issue concurrently at all volatile chemical sites where remedial or corrective actions have been implemented is not feasible
- These sites need to be prioritized