Two recent developments, one by the Massachusetts Department of Environmental Protection (“MassDEP”) and one by ASTM International (“ASTM”), underscore the importance of addressing indoor air contamination that results when soil or groundwater contamination migrates as vapor. On the regulatory side, MassDEP has emphasized its focus on this issue by issuing a flurry of draft guidance and procedures. From an industry perspective, ASTM recently released a new industry standard for assessing indoor air contamination at properties that are the subject of real estate transactions. As MassDEP’s draft standards are regulatory in nature and appear stricter than the ASTM standard, the ASTM standard may be of limited relevance here in Massachusetts. However, it may serve to set the standard of care in states where Superfund regulations on this topic are not as detailed as those in Massachusetts.
Vapor Intrusion Law in Massachusetts
In Massachusetts, MassDEP has promulgated regulations and standards under the Massachusetts Contingency Plan (“MCP”) governing the mitigation of contaminants in indoor air space. Under the MCP, vapor intrusion is of regulatory concern when hazardous materials or oil are detected, or predicted to be detected, in the indoor air space at concentrations that pose, or would pose, a condition of significant risk. Specifically, for soil and groundwater, vapor intrusion is a concern when contaminant concentrations exceed the thresholds identified in the MCP Groundwater 2 Standards (“GW-2 Standards”), 310 CMR §§ 40.0932(6), 40.0974(2). The GW-2 Standards were recently updated in 2007. Even if GW-2 Standards are not exceeded, vapor intrusion is a concern when site-specific conditions suggest that indoor air may pose a significant risk.
Regardless of conditions in soil or groundwater, indoor air concentrations that pose a risk must be addressed unless the person performing response actions can establish that the contaminants are not the result of the disposal site. In 1992, MassDEP published a list of background concentrations of volatile hazardous materials. Concentrations above background were presumed to result from the disposal site. See Indoor Air Background Concentrations (1992) (no longer available on MassDEP’s website).
On January 24, 2008, however, MassDEP published new draft guidance for indoor air sampling. See Using Upper Percentile Values Within The Range Of Typical Indoor Air Concentrations At Residences and Schools, available here (the “Guidance”). Instead of merely listing background concentrations, this Guidance provides ranges of typical indoor air concentrations and advises that these ranges can be used as one (but not the only) line of evidence demonstrating that vapor intrusion is not a concern at a given property. If MassDEP adopts this Guidance, it will be more difficult for property owners to prove that vapor intrusion is not a concern. MassDEP accepted comments through February 29, 2008 but has not, as of today, published final guidance.
MassDEP also recently prepared a Standard Operating Procedure For Completing Response Actions (the “Procedure”), which provides internal agency guidance for addressing vapor intrusion. In many cases, this Procedure recommends costly indoor sampling at likely points of vapor intrusion to prove that indoor air has not been impacted by the disposal site or that response actions have eliminated or mitigated the impacts of vapor intrusion. While this Procedure is currently intended for internal use only, MassDEP has announced plans to publish an external version shortly. As discussed below, this Procedure is in some respects stricter than ASTM’s new standard for assessing vapor intrusion.
Industry Standards for Vapor Intrusion
On March 3, 2008, ASTM released new industry standard E 2600-08, Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions (the “ASTM Standard”). This standard provides a method for assessing whether a vapor intrusion condition (or “VIC”) exists on a property that is the subject of a real estate transaction (“subject property”). A copy of the ASTM Standard can be purchased here.
The ASTM Standard is designed to either supplement the standard for Phase I Environmental Site Assessments (E 1527-05) or be used as a stand-alone guidance document. As the accompanying White Paper to the Standard explains, the ASTM Standard recommends a conservative four-tier assessment that progresses as follows: (Tier 1) analyzing existing data; (Tier II) collecting site samples (soil, soil/gas, groundwater) and site-specific data about the subject and nearby properties; (Tier III) conducting more costly and sophisticated indoor air sampling, including sampling of points where vapor is likely to enter structures; and (Tier IV) implementing actions to eliminate or mitigate the path of vapor into such structures.
The ASTM Standard is in some sense conservative, because it presumes that a potential VIC exists at a property until the presence of a VIC can affirmatively be ruled out. The Standard is, however, also flexible because the tiers need not be addressed sequentially. For example, if a user cannot rule out the presence of a VIC by the conclusion of Tier II, the user can conduct more sophisticated indoor sampling under Tier III in the hope that such data will rule out a VIC. Alternatively, the user can immediately implement Tier IV to save the cost of conducting a Tier III investigation. Here in Massachusetts, however, the relevance of this option is limited in part because MassDEP’s new Standard Operating Procedure requires Tier III sampling to prove that some Tier IV response actions comply with MCP. The MassDEP Procedure is, therefore, more stringent than the ASTM Standard.
What It Means
As the MassDEP procedures and guidance may be stricter than the ASTM Standard, property owners and environmental professionals in Massachusetts should first consult the MCP response action performance standards, 310 CMR § 40.0919, and related MassDEP guidance to ensure that potential response actions comply with MCP. The ASTM Standard may, however, still be relevant when MCP performance standards or MassDEP guidance does not address the particular circumstances present at a given property. Like the prior ASTM standard for Phase I Environmental Site Assessments, the ASTM Standard for vapor intrusion may also ultimately define the standard of care in states where the regulations are not as prescriptive. In any case, these developments emphasize the regulatory and commercial significance of potential vapor intrusion issues. Property owners will ignore these issues at their peril.