August Mack Newsletter | July, 2018

Vapor Intrusion in Ohio: What You Need to Know
by Brandon Lewis

Vapor intrusion, referred to simply as VI, is the migration of volatile chemicals from the subsurface into overlying buildings.  Common sources of volatile chemicals associated with VI include dry cleaners (tetrachloroethene, or PCE), degreasing operations at auto shops or factories (trichloroethene (TCE), PCE and other volatile organic compounds), and gas stations (benzene and naphthalene from fuels).  Releases of these chemicals to subsurface soil and groundwater do not only pose a VI risk for the release site, but also the adjacent properties and receptors.  The potential vapor impacts are generally associated with the soil and groundwater contamination, but can also follow preferential pathways like sewers and utility lines.   As such, contaminant plumes can be highly variable, ranging from less than 100 feet to several thousand feet depending on the nature of the release and chemical characteristics of the compound.

VI is a relatively new field of environmental study and investigation. Subsurface investigations of soil and groundwater have had the benefit of over 40 years of application in environmental regulatory programs to refine investigational techniques, regulations, and risk assessment criteria to assess impacts. Conversely, VI investigations are behind the curve, and VI has only come to the forefront as a potential risk within the last approximately 15 years. VI issues have become one of the most common environmental impediments to site closure and property transactions in the marketplace today.  Due to the evolving science and investigational strategies associated with this new field, regulatory guidance on vapor intrusion has been challenging to develop and even more challenging to implement.

What are the effects of VI exposure?  The overall effects VI exposure are going to be specific to the chemical released, but in general, both acute (short term) and chronic (long term) health effects are possible. Acute health effects can range from disorientation, irritation of eyes, skin, and lungs and nausea at high concentrations, to potential for fetal heart defects from inhalation of low concentrations of TCE for a short amount of time (recent EPA conclusion that is somewhat controversial).   Chronic health effects occur from exposures over longer durations and are typically associated with carcinogenic compounds such as PCE, TCE, and benzene. 

Ohio EPA issued its first VI guidance in 2010, titled “Sample Collection and Evaluation of Vapor Intrusion to Indoor Air”.  The 2010 guidance was intended for use in assessing sites in Ohio’s Remedial Response and Voluntary Action Programs.  The guidance provided information on the process for evaluating the VI pathway, beginning with an assessment of the chemicals and concentrations in soil and groundwater, to potential sampling beneath or in the buildings.  The guidance outlined a stepwise approach for assessing VI, and included a flow chart as a simplified guide of how to confirm or screen out VI concerns.  The 2010 VI guidance was updated in May 2016, and included several important changes:

  • It eliminated the use of the Johnson & Ettinger Model to evaluate potential for vapors to migrate into overlying structures; and
  • It requires that the use of the U.S. EPA Vapor Intrusion Screening Level (VISL) calculator, which is highly conservative and much less flexible with respect to adding site-specific information into the calculator.  

In addition, in September 2016, Ohio EPA released new VI screening levels (chemical specific) that included Accelerated, Urgent, and Imminent Hazard response actions.  These response actions include mitigating the VI issue within a few weeks of identification to immediate removal of occupants of the building. These responses actions were heavily focused on TCE, but also included some additional actions for PCE, vinyl chloride, and naphthalene.  Ohio EPA is also currently completing additional revisions to the VI guidance and an updated document is expected to be released some time later this year. 

The impact of vapor intrusion on property transactions and remediation is significant in Ohio (and throughout the US).  In fact, in late 2016 and early 2017 the Ohio EPA sent a series of letters to Ohio Voluntary Action Program (VAP) Certified Professional (CPs) stating that if they had a site that contained VI impacts, particularly those associated with TCE, then it was recommended that they evaluate the situation and make sure current property owners are aware of a potential VI condition.  These letters do not constitute a re-opener of closed sites, but serve as a “shot across the bow” that CPs have a responsibility to ensure that public is protected and that they need to identify and notify closed sites that there is the potential health threat.

Not only does VI bring investigational and regulatory issues in tow, there are also legal and technical concerns that commonly complicate, impede or prevent closure or purchase of a property.  These emerging policy concerns, coupled with the short term TCE developmental risks of fetal heart malformations and the VI exposure pathway, have made a perfect storm of issues and concerns for the general public, site reviewers, attorneys and regulators alike.  August Mack is very experienced in addressing the challenges associated with evaluating and managing VI.  Should the term VI rear its ugly head on your project or deal, August Mack can assist you with assessing what is becoming all too common of a concern.

Brandon C. Lewis is a Senior Project Manager for Closure Services in August Mack’s Ohio office. He has 12 years of environmental consulting experience. His professional experience and technical expertise lies in RCRA Corrective Action (federal and state level), underground storage tank (UST) closures, subsurface investigations, groundwater monitoring, vapor intrusion, data evaluation, remedial evaluation/construction, and remedial systems operations.  Brandon is also experienced in phase I assessments, asbestos surveys, and asbestos abatement oversight.  Brandon provides technical project oversight and staff development of the Ohio office’s Closure department.

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