In March 2008, ASTM International published ASTM E 2600-08: Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions. This is the first comprehensive national standard to address vapor intrusion in the context of real estate transactions, and it provides prospective purchasers with a useful diligence tool for identifying and dealing with potential liabilities prior to purchasing property. As such, this new standard may increase the level of due diligence performed by prospective purchasers.
Until now, prospective purchasers have routinely performed Phase I Environmental Site Assessments consistent with ASTM E 1527-05. While the standard Phase I meets CERCLA's requirements for "all appropriate inquiry" and allows a prospective purchaser to maintain certain defenses to liability under CERCLA, the Phase I does not address vapor intrusion. With the introduction of ASTM E 2600- 08, a vapor intrusion assessment ("VIA") can now be performed in connection with the Phase I. ASTM cautions that the VIA itself is not a requirement of and does not constitute "all appropriate inquiry;" however, the inquiries required by a Phase I and a VIA complement each other.
Under the new standard, an environmental professional performs a VIA at a property to identify whether a vapor intrusion condition ("VIC") exists. A VIC is broadly defined to include the "likely" presence of COCs in the indoor air environment from contaminated soil/groundwater vapors that "may" present an unacceptable health risk to occupants. To identify VICs, ASTM prescribes a four-tiered process that provides flexibility in response to cost and time constraints. The first three tiers describe screening and investigation approaches, while the fourth tier focuses on mitigation. Each tier is discussed on the following pages.
Tier 1 Screening
The Tier 1 screening is a non-invasive screening mechanism that can readily be performed as a supplement to a standard Phase I. Similar to a Phase I, the environmental professional must evaluate: (i) existing/planned use of the property; (ii) types of existing/planned structures; (iii) surrounding area; (iv) government records; (v) historical records; (vi) physical setting information (topography, soil type, etc.); (vii) significant conduits (i.e., sewers, storm drains); and (viii) user specialized knowledge, experience, and commonly known or reasonably ascertainable information.
The environmental professional must further evaluate whether there are contaminated sites within relevant areas of concern and whether such sites are likely to have COCs. If applicable information is available, the environmental professional must also perform a "plume test." The plume test evaluates whether COCs within a contaminated plume are within a "critical distance" of structures (or boundary line in the absence of structures) at the target property, and whether risk based concentrations ("RBCs") are exceeded. If the distance between the contaminated plume and the structures is less than 100 feet (or 30 feet in the case of dissolved petroleum hydrocarbon COCs), then a potential VIC (or "pVIC") is presumed to exist.
Based on the Tier 1 screening, the environmental professional must either conclude that there is a pVIC or that vapor intrusion is unlikely to be an issue. If a pVIC cannot be screened out, it is generally presumed to exist. For example, in the absence of further information, up-gradient contaminant sources within relevant areas of concern with suspected COCs are presumed to be pVICs. Similarly, down-gradient and cross-gradient contaminant sources within the critical distance of the target property with suspected COCs are also presumed to be pVICs in the absence of further information.
If a pVIC can be screened out, then there is no need to perform additional assessment. If a pVIC exists, however, then further assessment may be warranted based on consultation between the environmental professional and the prospective purchaser.
Tier 2 Screening
A Tier 2 screening involves an evaluation of site-specific data using semi-site specific screening criteria. Soil, groundwater and/or soil gas test results must be collected if such data does not already exist, either as part of a Phase II environmental site assessment or as a separate scope of work. If the data already exists as part of a previous Phase II, then it may have been reviewed and evaluated during the Tier 1 screening.
The Tier 2 screening compares generic or specific RBCs with concentrations of COCs that are within the critical distance. The ASTM standard indicates that generic state RBCs should be used when available. If these are not available and the state does not prohibit the use of RBCs, then either the federal generic RBCs or site-specific RBCs can be used. Using this information, the environmental consultant should be able to determine whether the plume is within the critical distance of the target property, and whether COCs create a potential pVIC based upon comparison with RBCs.
If the applicable RBC is not exceeded, then there is no pVIC. If the applicable RBC is exceeded, then a pVIC exists. The prospective purchaser may wish to further investigate to determine whether there is an actual VIC or to proceed with vapor intrusion mitigation.
Tier 3 VIC Assessment
If a pVIC cannot be ruled out through a Tier 1 or Tier 2 screening, then a prospective purchaser may wish to perform actual interior or exterior vapor testing as part of a Tier 3 VIC assessment, using appropriate guidance. In addition to indoor air sampling, a Tier 3 VIC assessment contemplates that groundwater and/or soil gas data can be used to estimate the impact on indoor air. The ASTM standard acknowledges that guidance documents "contain disparate and often conflicting recommendations for data needs, data collection methods, and screening or evaluation criteria." Instead of adopting a specific guidance document, the ASTM standard merely indicates that the environmental professional and the user (i.e., prospective purchaser) should "evaluate" the most current technical and regulatory guidance. Even a Tier 3 VIC assessment may fail to rule out the presence of a pVIC, and in such cases a pVIC is still presumed to exist.
Tier 4 Mitigation
To address pVICs that cannot be ruled out, and to address actual VICs, the ASTM standard discusses several mitigation approaches. These approaches involve institutional controls, engineering controls, and intrinsically safe building design. Institutional controls include legally enforceable controls such as deed restrictions. Examples of engineering controls include source removal/treatment, soil vapor barriers, vapor collection systems, and indoor air treatment systems. Examples of intrinsically safe building designs include well ventilated parking facilities below office buildings and residences. The ASTM standard leaves it to the user and the qualified professional to determine the most appropriate mitigation approach.
Summary
ASTM E 2600-08 allows prospective purchasers and others to anticipate changing site conditions, and to detect and prevent unacceptable vapor intrusion conditions at properties. The built-in flexibility of this new standard and its ability to complement the Phase I process suggest that its use will become commonplace within the commercial real estate industry. As the standard continues to evolve and its use becomes more routine, VIAs may reshape the potential for vapor intrusion liability. For example, landowners, builders and developers could face lawsuits from injured property occupants alleging negligence for the failure to perform a vapor intrusion assessment. Moreover, vapor intrusion assessments could become part of "all appropriate inquiry," complicating a prospective purchaser's ability to maintain certain defenses to CERCLA liability and making it easier for regulatory agencies to recover costs spent responding to vapor intrusion threats. Given the usefulness of VIAs and the potential effects this new ASTM standard may have on the commercial real estate industry, prospective purchasers should consider performing VIA's in accordance with ASTM E 2600-08.
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