David R. Gillay, Barnes & Thornburg LLP 1

This is the second in a series of articles focusing on an unseen villain known as vapor intrusion.
This article discusses some of the challenges and new tools to secure and maintain regulatory closure
of contaminated sites where this pathway is potentially present.

Vapor intrusion (VI) is the migration of volatile chemicals from subsurface soil and groundwater into buildings. It
shares many common characteristics with the intrusion of naturally occurring radon gas into buildings. This emerging
contamination “pathway” has affected thousands of closed and contaminated sites across the country.

The VI pathway reveals some of the potential future risks flowing from the risk-based closure of contaminated sites. A
risk-based approach generally allows the responsible party to tailor the remedy to the real-world exposures at each
site, instead of simply removing all of the contaminant or achieving a numerical closure level for unrestricted use
in certain environmental media. Risk-based decision-making is a mechanism to integrate source reduction and risk
management of a cleanup to ensure it protects human health, applies sound science and common sense, and is flexible
and cost-effective. Depending on known or anticipated risks to human health and the environment, an integrated risk-based approach may include monitoring and data collection, active or passive remediation, containment, institutional
controls, or a combination of these actions.

To effectively manage liability, a responsible party must find the balance between source reduction and risk
management for residual contamination. Evolving VI pathway guidance and dramatic changes to a contaminant’s
toxicity can disrupt this delicate balance.

In late 2002, the United States Environmental Protection Agency (EPA) first released draft guidance on the VI pathway.
The EPA finalized its VI pathway guidance well over a decade later, in the summer of 2015. During the EPA’s careful
deliberation and release of its VI guidance, the vast majority of state environmental agencies published their own VI
guidance. The VI guidance landscape remains in flux and continues to evolve, with more emphasis on the movement
of soil gas in the subsurface.

As the regulatory scrutiny intensified on the VI pathway, the EPA updated its toxicological review for one of the most
ubiquitous chlorinated solvents, Trichloroethylene or TCE, in our nation’s groundwater. Published in 2011, this review
suggested that a low level of TCE may pose an immediate potential hazard and adverse developmental outcomes could
potentially result from short-term TCE inhalation exposures during pregnancy. One of the more controversial studies
that the EPA used identified that even a woman’s single exposure to TCE during fetal development may be sufficient to
produce an adverse developmental effect. The VI pathway was quickly designated a primary conduit for TCE vapors to
enter a structure and amplified this potential risk.

As a consequence of evolving VI guidance and developmental toxicity concerns with TCE exposure, many states,
including New York, Michigan, Minnesota, and Massachusetts, systemically started to reevaluate and, where
appropriate, reopen closed sites with TCE contamination.

Maintaining regulatory closure

So, given the rapidly changing regulatory climate, how can a responsible party secure and, perhaps more importantly,
maintain regulatory closure for a contaminated site? A phase-based approach may be the best choice, coupled with
some new tools.

Phase 1. The first phase should focus on an internal audit of your portfolio of active and/or closed sites. There are
ways to help ensure that the audit is privileged and confidential. This audit should be conducted through legal counsel
and include an experienced consulting expert to help evaluate the risk-based assumptions and evaluate any new
pathways (like VI). This expert should consider, among other criteria, the applicable screening levels for the VI pathway
and conduct an updated receptor survey for both on and off-site land uses.

Phase 2. The second phase could involve collecting additional samples. If it is determined that the VI pathway was not
adequately assessed or evaluated, then you should consider developing a VI Decision Matrix, VI Sampling and Analysis
Plan, and updating the VI Conceptual Model.

Phase 3. The third phase is site-specific and data-driven. Developing a so-called Long Term Stewardship (LTS) Plan
that embraces and effectively uses new regulatory, legal, and technical tools to manage the VI pathway is considered
a best practice. There is state and federal guidance available to draft a successful LTS Plan or equivalent approach.
There are important legal mechanisms, including environmental restrictive covenants or ordinances, which when
properly drafted can be very effective to manage potential future VI pathway liability. An LTS Plan can include new
technology and tools, like the newly patented remote monitoring device known as the Vapor Sentinel. This new device
provides remote telemetric monitoring technology to provide around-the-clock data collection and reporting.

The VI pathway can be complex and the science continues to evolve at a rapid pace, but with counsel from legal and
environmental professionals and a phase-based plan tailored to your site, you can successfully secure and maintain
closure. The last article in this series will cover various landowner liability protections and some recent toxic tort
litigation centered on the VI pathway and alleged TCE exposure.

This publication should not be construed as legal advice or legal opinion on any specific facts or circumstances. The contents
are intended for general informational purposes only, and you are urged to consult your lawyer on any specific legal questions
you may have concerning your situation. David R. Gillay, Esq., is a Partner in the Environmental Department of Barnes &
Thornburg LLP’s Indianapolis Office and may be reached at 317.946.9267 or david.gillay@btlaw.com.

1 David leads Barnes & Thornburg LLP’s Environmental department’s remediation, redevelopment, and environmental transactions practices. He has focused on the legal, regulatory, and technical impact and implications related to the vapor intrusion pathway, chlorinated
VOCs (with an emphasis on TCE), and potential long-term stewardship obligations related to environmentally challenged properties for
nearly two decades. David is a frequent writer and speaker, having participated in a variety of private association, client, and continuing
legal and business education seminars with a special focus on vapor intrusion, TCE, and developing cost-effective solutions to manage
residual contamination as part of redevelopment projects and the sale of contaminated property. David was recently elected to join the
American Association of Radon Scientists and Technologists (AARST) Board of Directors and continues to serve as counsel of record for
the Midwestern States Environmental Consultants Association (MSECA). Prior to joining Barnes & Thornburg, he obtained an advanced
environmental engineering degree and practiced as an environmental consultant on various projects across the country.