Radon Reporter March 2022

THE RADON REPORTER | 13 VAPOR INTRUSION THE VAPOR INTRUSION PATHWAY MINI-SERIES Transactional Considerations David R. Gillay, Barnes & Thornburg LLP 1 This is the first in a series of three articles focusing on an unseen villain known as vapor intrusion to provide a look into key transactional considerations related to this environmental health hazard. 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” presents significant challenges, complicates property transactions and securing and maintaining regulatory closure of contaminated sites, and increases litigation and legal risks. VI issues are far-reaching and have affected thousands of sites across the country. Successfully dealing with VI issues requires a basic understanding of the complex science, rapidly changing regulatory landscapes at the state and federal levels, and evolving legal doctrines that may increase your liabilities. 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.