Vapor Migration Considerations Under the New Phase I Standard

Sunday, June 16, 2013

This article is the second in a series exploring the proposed changes to the new Phase 1 ESA standard.

When ASTM International releases the new Phase 1 environmental site assessment (ESA) standard, some of the changes will require the environmental professional (EP) performing the Phase 1 to specifically consider vapor migration–not only as a concern from potential onsite sources, but also any possible encroachment from surrounding properties.  

Several proposed changes to the new standard make it clear that the EP must now consider vapor migration in the subsurface during the Phase 1 process.  The revised standard will include a reference to ASTM Standard E2600-10: Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions, which provides a standard procedure that an EP may use for evaluating vapor migration.  Situations where the potential for vapor phase contaminants to be present on or migrate onto the subject property are identified as a vapor encroachment condition (VEC).

It is important for Phase 1 users to realize that an identified VEC is not necessarily a recognized environmental condition (REC).  A determination regarding whether or not a potential VEC represents a true vapor intrusion concern is left to the EP.  An open dialog with the EP regarding these types of conditions can provide great value for the user in evaluating what risk these conditions represent for the subject property (currently and in the future).

Other proposed changes to the new Phase 1 standard address further consideration to regulatory agency file and records reviews.  These changes will be the topic of a subsequent article.

Currently, the U.S. Environmental Protection Agency (EPA) is reviewing the draft revised standard to ensure its consistency with the All Appropriate Inquiries (AAI) rule.  Pending EPA approval, the new standard (E1527-13) is anticipated to be released in the summer of 2013 and will become effective immediately.