Vapor Intrusion

by MAR Staff | Nov 26, 2012
By Samuel Butcher, LSP and VP Loureiro Engineering Associates, Rockland
The Massachusetts Department of Environmental Protection (MassDEP) recently revised a policy and is currently revising regulations regarding how indoor air vapors associated with contamination are assessed and remediated. These policy and regulation changes could impact commercial and residential property owners and possibly affect a commercial or residential sale.

Q. What is Vapor Intrusion?
Some forms of soil and groundwater contamination are “volatile” and will evaporate into the air space beneath a building and potentially be drawn into the building. This is common in the winter when hot air within the building leaks out and is replaced by air from beneath the building or outside. Air that is contaminated as a result of volatile contaminants and migrated into the building is called vapor intrusion.

Q. What are some common sources of contamination that could lead to vapor intrusion?
Products such as dry cleaning solvents and degreasers (which often contain chlorinated compounds) or fuels, such as gasoline, kerosene, and fuel oil, are the most common volatile chemicals. Contamination such as metals or pesticide do not lead to vapor intrusion because the contaminants are not volatile.

Q. Why is MassDEP changing the policy and regulations?
The MassDEP is changing the policy and regulations because recent studies demonstrate a clearer insight of how vapors can migrate through soil or groundwater and into a building. Further, studies show that the risk to public health associated with inhaling these vapors once they have migrated to indoor air is greater than once
believed. As a result, MassDEP determined that how we investigate and clean up these vapors had to change.

Q. What do I need to do?
If you have no reason to believe there is contamination on a property or on nearby properties, then you probably do not need to do anything. But remember that contamination can migrate. A spill from across the street can find itself under an abutting building as a result of migration in groundwater or through buried utilities. If there is evidence, or if you suspect there might be contamination on a property, it is wise to consult with someone to determine whether vapor intrusion should be investigated. If you know there is contamination on your property, ask an expert whether the new policy and regulations mean that an evaluation of the potential for vapor intrusion is necessary.