New ASTM Vapor Intrusion Standard
In March 2008, ASTM International issued its Standard E2600-08 entitled “Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions.” The goal is to identify whether there is a potential for a vapor intrusion condition to exist. The stated purpose of the standard is to define “good commercial and customary practice” for real estate transactions in the United States for conducting vapor intrusion assessments for properties with, or in proximity to, contamination of soil and groundwater by certain volatile compounds. However, it is likely that the standard will be significant in litigation involving claims based on alleged vapor intrusion.
Contents of Standard E2600-08.
The standard specifies a relatively conservative four-tier screening process to identify whether a property has a vapor intrusion potential. The process is site-specific and requires collection of information about the specific property and neighboring properties. The four tiers are:
· Tier 1 - Initial (non-invasive) Screening
· Tier 2 – Semi-Site Specific Numeric Screening
· Tier 3 – Vapor Intrusion Condition Assessment
· Tier 4 – Mitigation
Tiers 1 and 2 should be conducted by an “environmental professional” as defined in Standard E1527 addressing Phase I Environmental Site Assessments or ESAs. Tiers 3 and 4 should be conducted by such an environmental professional who has specific vapor intrusion experience.
At any point in the screening process, the property owner may elect to avoid potential vapor intrusion issues by implementing preemptive mitigation.
In Tier 1, the environmental professional uses non-numerical information typically collected during a Phase I ESA to determine whether a potential vapor intrusion condition is unlikely to occur because of the site conditions or physical setting. Information to be considered includes: existing/planned uses of the site; site and neighboring property histories; physical setting (soil type, geological, hydrological, hydrogeological and topographic information); existence of natural or man-made conduits; types of contamination (i.e., likely to have soil vapor). The distance from potential sources of volatile contamination must be considered. Standard E2600-08 presumes a potential for vapor intrusion is unlikely when the lineal distance between the nearest edge of contamination and the nearest planned or existing structure is greater than or equal to 100 feet for volatile contaminants other than dissolved petroleum hydrocarbon chemicals and 30 feet for those petroleum chemicals. The types of structures planned or existing on the site are also important. If there are intrinsically safe building designs such as well-ventilated underground parking garages or multifamily units with first floor open parking, a potential for vapor intrusion is unlikely.
The screening moves on to Tier 2 if the potential for vapor intrusion cannot be ruled out as a result of the Tier 1 screening and if the property owner does not choose to implement preemptive mitigation. Tier 2 compares site-specific groundwater and/or soil vapor concentrations to applicable government-established generic and semi-site-specific Risk Based Concentrations (RBCs). Site-specific soil, soil vapor and groundwater data from previous sampling and analyses may be used. If such data are not available, sampling is required. If the applicable RBC is exceeded, a potential vapor intrusion condition exists. The next step is either Tier 3, vapor intrusion assessment, or Tier 4, preemptive mitigation.
Tier 3 uses interior or exterior measurements and predictive modeling or attenuation factors (whichever procedure is accepted by relevant lead agency) to assess vapor intrusion potential. A multiple lines of evidence approach is recommended to determine whether vapor intrusion exists.
Tier 4 is selection of mitigation alternatives. Mitigation may include one or more of institutional controls, engineering controls or intrinsically safe building design. Institutional controls in this context are like those used in other environmental contexts and include deed restrictions and other legally enforceable conditions placed on property to reduce the likelihood of exposure. Engineering controls may include source removal and treatment, barriers and venting to prevent subsurface vapors from entering a building, pressurization of building interior to direct vapors away from enclosed spaces, and indoor air treatment systems.
Limits on Standard E2600-08.
First, the new standard is not intended by the ASTM to represent the standard of care by which the adequacy of an environmental professional’s service is judged. However, as a practical matter, it is likely that courts and litigants in negligence cases involving vapor intrusion will nonetheless regard Standard E2600-08 as evidence of conduct that meets the standard of care.
Second, Standard E2600-08 does not replace, expand or otherwise change Standard E1527 addressing Phase I ESAs. ASTM intends that Standard E-2600-08 may be used independently of Standard E1527 or as a voluntary supplement to that standard. It is not intended to be a substitute for a Phase I environmental assessment under Standard E1527.
Third, Standard E2600-08 states that it is not a requirement for “all appropriate inquiry” under CERCLA and does not “constitute, expand, or in any way define” the scope of CERCLA all appropriate inquiry. Compliance with Standard E1527 is generally regarded as sufficient to satisfy CERCLA’s all appropriate inquiry rule, and Standard E2600-08 was developed specifically to address a gap in Standard E1527. In light of these circumstances, prospective brownfields developers may well conclude that it is prudent to include Standard E2600-08 in their environmental consultants’ scope of work.
Fourth, Standard E2600-08 does not address requirements under federal, state or local law regarding vapor intrusion. For example, it does not address action levels, required remediation or possible legal obligations such as disclosure.
Finally, Standard E2600-08 does not address whether a potential vapor intrusion pathway is a complete exposure pathway or whether potential vapor intrusion poses an unacceptable risk to human health. Those determinations require further analysis under federal and/or state guidance documents identified in appendices to the standard.
Benefits of Standard E2600-08.
The Standard E2600-08 process is intended to quickly and inexpensively screen out properties that are unlikely to have a vapor intrusion condition. This process is not intended to be exhaustive or eliminate all uncertainty. Consistent with good commercial practice, the process will be guided by the type of property, the risk tolerance of the buyer and the information already available or developed in the screening process. Standard E2600-08 also confirms that a commercially reasonable option for owners of properties that are not screened out at Tier 1 is to choose preemptive mitigation and thereby avoid the expense and time to proceed through the Tier 2 and 3 activities.
