Vapor Intrusion Adds an Invisible Curve Ball to Real Estate Transactions

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Gas Works Park - Brownfields

Whether you are a buyer, seller, lender, or third party to a real estate transaction you need to understand the risks associated with vapor intrusion. Let’s first define vapor in this context. Vapor is the gaseous form of a volatile liquid compound. Liquids evaporate under specific conditions and vapor intrusion occurs when vapors migrate from soil and/or groundwater contamination to indoor air above a contaminated site.

Vapor intrusion affects indoor air quality and can be detrimental to building occupants if left undetected. Since vapor can be odorless, current property owners may be unaware of this issue prior to putting their property on the market. Therefore, most prospective buyers seek some form of regulatory assurance or liability protection from the current property owner to ensure that contamination is not present.

In fact, the latest revisions to the American Society of Testing Materials’ standard (ASTM E1527-2013) for conducting Phase I Environmental Site Assessments places an even greater emphasis on examining the potential for vapor intrusion. Several variables can affect the vapor intrusion pathway including seasonal climate changes and temporal variations at the time sampling is conducted. As a result, the Minnesota Pollution Control Agency (MPCA) issued new guidelines in late 2016 and early 2017 that require more frequent, multiple sample trials to assess for vapor intrusion. These new guidelines can complicate the real estate transaction causing uncertainty and increasing due diligence assessment costs.

Traditionally, the key stakeholders involved in a real estate transaction were familiar with, and understood that soil and/or groundwater contamination posed little direct risk to the property. Sites with soil and/or groundwater contamination rarely required much action, if land use was to remain unchanged. Vapors on the other hand, do not necessarily require any change in land use to necessitate action from a prospective buyer. This invisible curve ball increases the need for in-depth due diligence.

To avoid the unknowns and limit unnecessary costs throughout the process partner with Wenck. Our experts understand the regulatory process and we are uniquely positioned to provide vapor intrusion assessments, health risk evaluations, regulatory oversight, and turnkey mitigation construction solutions.

Recently, Wenck was retained to provide rapid action vapor assessment and mitigation services to a high-profile site under the MPCA’s VIC Program. We had 45 days before a 20,000-square foot industrial building was scheduled to open as a charter school. The building was formerly used for industrial manufacturing operations that resulted in tetrachloroethylene (PCE) releases. Within 30 days, Wenck evaluated the vapor pathway, completed vapor mitigation designs that included depressurization sumps and pits, installed a vapor mitigation system, and conducted pilot tests under a high level of regulatory oversight. Retrofitting large commercial buildings on a short timeline requires experience, innovative design, and a flexible team.

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Aaron Benker

Wenck Contact

Aaron Benker

Principal