ASTM International (ASTM) has issued a final standard for assessing the risks associated with vapor intrusion in real property transactions. The final standard, ASTM E2600-08 Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions (Standard), was released on March 3, 2008, and establishes a flexible, tiered approach for evaluating the potential for vapor intrusion to adversely impact property.
Background
Vapor intrusion occurs when volatile organic compounds (VOCs) found in underlying contaminated soil and/or groundwater migrate as vapor through soils into the indoor air spaces of overlying or adjacent buildings. In many cases, it is most cost effective to evaluate the potential for indoor air contamination from vapor intrusion early in the scope of any investigation. This is a challenging task, however, in part because background levels of VOCs in the ambient indoor air (i.e., from consumer products, art supplies, or dry-cleaned clothes) may compete with or hinder identification of an underground source of contamination. Nevertheless, there are direct and indirect vapor intrusion methodologies provided by the U.S. Environmental Protection Agency (EPA) and several states designed to analyze whether subsurface vapors are intruding into indoor air spaces.
Development of the Standard
In 2005, ASTM created a specific task group to develop an ASTM standard to assess vapor intrusion as it relates to property transactions and to determine whether vapor intrusion is a recognized environmental condition (REC) under ASTM E1527-05 Standard Practice for Environmental Site Assessments (ESA): Phase I Environmental Site Assessment Process. ASTM released an internal draft vapor intrusion standard in January 2007 that contemplated using a tiered approach to assess the potential for vapor intrusion to be classified as an REC.
The final Standard adopted a flexible, four-tiered approach that evaluates the presence of vapor intrusion conditions (VIC) in a multiple-step process.
By following the steps set forth in the Standard, a potential purchaser can determine whether a VIC issue exists at a property, and what potential mitigation may be appropriate to address the issue.
Regulation of Vapor Intrusion
Practical Considerations
Vapor intrusion is of particular concern at or near locations where i) remediation was completed without an assessment of the vapor intrusion pathway; ii) the property currently is undergoing remediation; or iii) the property is located in an area with historic contamination in the soil and/or the groundwater. However, simple and cost-effective solutions to vapor migration might be available during construction or renovation of a property, but only if the issue is identified early in the investigation process. If the issue is raised later in a redevelopment project, the remedy may be more costly, disruptive, and time-consuming. To that end, even if the target property or neighboring properties are "closed," a purchaser should consider reevaluating the site(s) for this newly articulated risk early in the due-diligence process. States recently have increased their efforts to "map" contaminated sites; as a result, the process of identifying potential migrating contamination that could pose a risk to indoor air quality may be more effective.
The risk of toxic-tort claims and claims for diminution in property values related to vapor intrusion is particularly exacerbated by the lack of clear and uniform standards, the substantial debate regarding acceptable risks associated with indoor vapors, and the continuing development of vapor-intrusion modeling and assessment practices. We have noticed a trend in construction best practices to incorporate vapor-mitigation systems as a low-cost prophylactic measure in all new construction, effective for both vapor intrusion from contamination as well as naturally occurring radium. These systems are fairly simple to design and add little cost if installed during the construction (or renovation) of the building.
Conclusion
Vapor intrusion presents potential liability concerns for prospective purchasers. The new ASTM Standard provides potential purchasers with an important tool to evaluate and, where necessary, mitigate the vapor-intrusion risk. Assessment of this risk will continue to evolve as states issue final rules and EPA continues to evaluate whether additional controls or guidance are necessary.
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