U.S. EPA’s Vapor Guidance: “More Data, More Sampling and Analysis”

“The cumulative impact of the EPA guidance is to require the generation of more data, which means more sampling and analysis, more frequent and stringent remediation, and potentially higher remediation costs.”

~Six Things the Private Sector Should Know About EPA’s Final Vapor Intrusion Guidance, Pepper Hamilton LLP

In June, the U.S. Environmental Protection Agency issued its final technical guidance on vapor intrusion: OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. If you think the federal guidance won’t impact transactional due diligence, think again. As a recent legal brief pointed out, the guidance impacts the assessment of volatile organic chemicals (VOCs), which are present at many contaminated groundwater sites; namely:

  • 78 percent of Superfund sites;
  • 57 to 69 percent of Department of Defense remediation sites;
  • many underground storage tanks; and
  • virtually all historic dry cleaning facility sites.

On June 24, 2015, I moderated an EDR Insight webinar focused squarely on the confusion surrounding trichloroethylene, or TCE, the most common groundwater contaminant. Attorney speaker David Gillay predicted that the updated TCE toxicity values and vapor intrusion risk will result in more sites “getting caught in the net, and driving more sampling and evaluations prior to real estate transactions.” Yesterday attorneys at Pepper Hamilton LLP made a similar prediction.

Below are some noteworthy excerpts from the Pepper Hamilton list of six critical aspects where EPA’s new vapor guidance has added to or modified the agency’s prior recommendations—guidance that “will likely make compliance significantly more complex, stringent and/or costly:”

  1. The Guidance is biased toward early action and preemptive mitigation.
  • EPA advises regulators to balance more sampling and preemptive mitigation “with a bias for initiating response actions necessary or appropriate to eliminate, reduce, or control hazards posed by a site as early as possible.
  • PRPs, therefore, will be faced at many sites (to a greater extent than previously has been the case) with the decision of whether to initiate interim/early action, including temporary relocation in the context of remedy selection.
  • Similarly, assessing this remediation risk will be more complex in a transactional due diligence inquiry.
  1. EPA prefers actions that eliminate or substantially reduce the level of vapor-forming chemicals via more expensive treatment or removal alternatives.
  • Installing engineered exposure controls to reduce or eliminate VI in buildings or to reduce indoor air exposure levels (including ventilation, overpressurization and other common VI remedies) are considered “interim” or “early” response actions.
  • Thus, EPA prefers the most expensive remedial actions (soil removal or treatment in situ), treatment of groundwater, removal of groundwater or decontamination of sewer or utility lines.
  1. The EPA VI Guidance recommends that the non-cancer assessment at VI sites should consider the potential for adverse health effects from short-duration inhalation exposures (i.e., acute, short-term or subchronic exposure durations), as well as longer-term inhalation exposure (i.e., chronic exposure) conditions.
  • The VI Guidance does not explicitly cite the TCE’s inhalation reference concentration (RfC) or mention Region 9’s use of a 24-hour indoor air action level.
  • EPA recommends that action be taken when the measured indoor air concentration divided by the RfC exceeds 1, which is quite stringent.
  • EPA’s new recommendation to consider adverse health effects from short-duration inhalation exposures may result in a significant increase in the number of VI remedial sites and increased remediation costs.
  1. EPA utilizes multiple lines of evidence, but the scientific criteria to meet this evidentiary standard are not well defined.
  • EPA generally recommends that multiple lines of evidence be developed and their results weighed together when evaluating and making risk-informed decisions pertaining to VI.
  • However, the VI Guidance, other EPA guidance and judicial interpretations do not define precisely what evidence (whether singular or multiple lines) is sufficient to demonstrate that a contaminated groundwater plume is the cause of the VI at levels above indoor air remediation levels or is likely to cause such exceedances in the future.
  1. The distance beyond which structures will not be affected by vapor intrusion should be a site-specific determination.
  • Many aspects of the VI Guidance require more intensive data gathering. For example, the Guidance recommends against using a de facto 100-foot buffer at landfills where methane is generated in sufficient quantities, at commercial or industrial settings where a vapor-forming chemical(s) has been released within an enclosed space, and at sites with pressurized gas transmission lines.
  • In other situations, the Guidance recommends a more site-specific analysis, particularly for buildings with significant preferential migration routes (e.g., geologic fractures, utility corridors). All of these changes increase sampling and evaluation costs.”
  1. There is no authority for EPA’s dismissal of the Occupational Safety and Health Administration (OSHA) permissible exposure levels (PEL) as a basis to determine whether vapor intrusion mitigation is necessary in nonresidential buildings.
  • EPA’s Superfund guidance has long listed and used OSHA PELs as indoor remediation levels for workplace exposure, and the EPA VI Guidance fails to explain adequately the legal or factual rationale for this change in policy.
  • Determining the contribution of VOCs in indoor air due to VI from a contaminated groundwater plume versus caused by normal industrial plant operations is inherently difficult. However, if the industrial operations at a plant alone will result in concentrations above the industrial indoor air remediation level, then addressing the portion of indoor VOC level attributable to the VI groundwater plume will not result in “compliance” with the industrial indoor air remediation level.


The authors of the Pepper Hamilton brief join a long list of other attorneys and professionals involved in commercial property transactions who believe the impact of the EPA final VI Guidance will be felt in the marketplace in the form of more data generation and analysis. In turn, this creates demand for the expertise of environmental professionals with a deep understanding of federal and state vapor guidance, knowledge of the current tools available for sampling and mitigation, the expertise to interpret and explain sampling data to clients, and the experience to exercise professional judgment in advising a client on the best remedial options for a particular property.


This brief is based on a Pepper Hamilton LLP publication, Six Things the Private Sector Should Know About EPA’s Final Vapor Intrusion Guidance, authored by Todd Fracassi, Andrewa Hayden and William J. Walsh. The full brief contains valuable, thoughtful guidance on the application of the federal vapor guidance. The authors are careful to note that “the Guidance is subject to professional judgment and interpretation and should not be universally applied at all sites.” For the complete brief, visit http://www.jdsupra.com/legalnews/six-things-the-private-sector-should-42469/.