On June 14, 2010, ASTM International published a revised Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions, designated as E2600-10 (the VES Guide). The VES Guide replaces ASTM's previous version released in March of 2008, which was entitled Standard Practice for the Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions.
The VES Guide provides a process for conducting a vapor encroachment screen (VES) in real estate transactions. This guide could also be used in brownfield redevelopment projects or other redevelopment activities. The purpose of a VES is to help identify if a vapor encroachment condition (VEC) exists at the target property. A VEC is defined as the "presence or likely presence of chemicals of concern (COC) vapors in the sub-surface of the target property caused by the release of vapors from contaminated soil or groundwater either on or near the target property as identified by Tier 1 or Tier 2 procedures."
As noted above, a VES consists of two tiers. Tier 1 generally uses information similar to that obtained when performing an ASTM E1527-05 Phase I Environmental Site Assessment (Phase I ESA) to determine if a VEC exists at the target property. Tier 1 identifies known or suspected contaminated properties within the area of concern (1/3 mile for volatile compounds; 1/10 mile for petroleum hydrocarbons). Tier 2 is more comprehensive and evaluates certain characteristics of a known contaminated plume resulting from contaminated properties and the proximity of the contaminated plume to the target property. If no plume information is available, Tier 2 screening can involve sampling.
If it is determined that vapors could reach the subsurface of the property, further investigation (that is beyond the scope of the VES Guide) would be necessary to determine: (1) if vapor intrusion is occurring at any buildings on the target property and (2) whether the VEC constitutes a Recognized Environmental Condition (REC) under the Phase I ESA standard.
The VES Guide focuses solely on vapor encroachment as opposed to assessing the vapor intrusion pathway. Vapor intrusion is the migration of volatile chemicals from contaminated soil and groundwater into buildings. The VES Guide specifically excludes a vapor intrusion assessment. The VES Guide suggests that a vapor intrusion assessment should be conducted to provide a definitive determination if a vapor intrusion problem exists at the target property or to narrow the uncertainty. One should be aware that vapor intrusion guidance continues to evolve at a rapid pace and currently available state and federal regulatory and technical guidance documents contain disparate and often conflicting recommendations for data needs, data collection methods, and screening or evaluation criteria. At last count, nearly 30 states have issued vapor intrusion guidance.
As it relates to RECs, it is critical to understand the relationship between the VES Guide and a Phase I ESA. U.S. EPA has determined that a Phase I ESA constitutes "all appropriate inquiry" (AAI) as defined under CERLCA and the regulations thereunder, including 40 C.F.R. §312.11. AAI is a threshold step to qualifying for certain landowner liability protections under CERCLA. The VES Guide does not constitute or meet the requirements for conducting AAI or any part of AAI. The VES Guide does not replace a Phase I ESA or any obligation to identify all RECs related to the target property. Instead, the VES Guide provides a methodology to accomplish this for vapors. If it is determined that vapors can migrate to the subsurface of the target property (thereby creating a VEC), the Phase I ESA would need to determine whether or not the VEC constitutes a REC.
We believe that the VES Guide is a practical and reasonable tool to help an environmental professional determine whether vapor intrusion is likely to be an issue at a property. We anticipate that the VES Guide will become a routine component of a Phase I ESA.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
