Groundwater Impacts and a Complete Exposure Pathway: Vapor Intrusion (VI) Case Studies with Mitigation Options

Monday, December 4, 2017
Bryant Hoffer, LPG, CHMM , Investigation/Remediation/Closure Department, August Mack Environmental, Inc., Indianapolis, IN

Groundwater impacts leading to Vapor Intrusion (VI) continues to be a hot-button topic in the environmental industry. As more information pertaining to VI becomes available, state and federal regulators, environmental consultants, environmental attorneys, insurers, and site owners are considering numerous approaches to sample, evaluate impacts, and mitigate the potentially complete pathway.

Various parameters of groundwater impacts affect the potential for a complete VI exposure pathway. These parameters include contaminant concentrations, depth to groundwater, lateral distance from groundwater impacts to occupied buildings, lithology of the unsaturated zone, and the individual characteristics of the Potential Contaminant (PC) at the Site.

There are several mitigation techniques currently available for sites with a complete/potentially complete VI exposure pathway. While numerous techniques are available for new construction (such as a vapor barrier, preemptive passive/active systems, and other new industry-specific products), the most common/effective strategy for existing buildings continues to be the installation/operation of Sub-Slab Depressurization Systems (SSDSs). These SSDSs introduce a pressure differential between the indoor air and sub-slab air. This pressure differential prevents the site PCs from entering the occupied building.

This poster will enable the reader to discover new sampling techniques, how to evaluate analytical data to determine the VI potential (with a focus on contaminant concentrations, depth to groundwater, and lithologic conditions), and learn about the common VI mitigation techniques. This poster will include case studies in which groundwater impacts have led to a potentially complete VI exposure pathway and the VI mitigation techniques used to effectively mitigate VI.

Bryant Hoffer, LPG, CHMM, Investigation/Remediation/Closure Department, August Mack Environmental, Inc., Indianapolis, IN
Bryant Hoffer has over ten (10) years of environmental consulting experience in Indiana. Consulting work has been focused on investigating/delineating surface/subsurface soil and groundwater impacts (resulting from gas station, dry-cleaners, and industrial operations), evaluating remediation options for sites across the state, implementing/operating various remediation systems, and working with the state regulatory agency (Indiana Department of Environmental Management). Mr. Hoffer has been involved with a variety of sites to evaluate the Vapor Intrusion (VI) exposure pathway, including collecting representative air samples (sub-slab, crawl-space, indoor air, and outdoor air), evaluating analytical results, and developing/implementing VI mitigation (at both residential and commercial facilities).


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