A New Standard for Environmental Due Diligence

3/3/2008

A new standard issued by ASTM International should assist parties involved in a real estate transaction, whether a purchase, financing, corporate transaction that includes real estate, or even a lease. The standard is titled “Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions” and supplements a Phase I Environmental Site Assessment to address prior inconsistencies in addressing the concern of vapor intrusion. The standard was developed through a consensus process that involved state and federal

regulatory agencies as well as the private sector.

Vapor intrusion (VI) is now a hot topic among environmental regulators. Intrusion of vapors into buildings can occur when a volatile hazardous substance (e.g., gasoline or dry cleaning solvent) is present in soil or groundwater, and vapors migrate into buildings, either through the foundation or following the path of utilities and other points of entry into the building. VI can occur even where a release is off-site, because contaminants migrate in groundwater, and vapors can migrate even further. Some states—including New York—are reopening previously “closed” sites where VI was not considered and the regulators are concerned that it may pose a risk.

Consideration of VI issues should be part of the environmental due diligence process. While not specifically required in a standard Phase I Environmental Site Assessment, consultants often noted the potential for VI since it presents a business risk. Until now, there has not been any standard practice for ruling out VI as a concern, leading many consultants to be overly conservative, recommending follow-up testing or other precautions because of liability concerns. ASTM’s standard now provides a practical, tiered approach for assessing VI risk.