MAEP Professional Development Meeting Presents . . .
November 7, 2018
New Tools for Vapor Intrusion Mitigation Design
Todd McAlary, Ph.D., P.Eng., P.G., GeoSyntec
Summary of ESTCP Research Project ER2013-22
Mitigation systems for radon and volatile organic compound (VOC) vapor intrusion to indoor air (VI) are usually designed to impose a measurable vacuum beneath the floor slab of a building through gas extraction from below the floor and the primary monitoring parameter is the static vacuum imposed by the system. This approach has some limitations associated with spatial variability in the vacuum field, temporal variability in the ambient cross-slab pressure gradient and building-specific conditions (bulk average permeability of the floor slab and material below the floor). Several new lines of evidence have been developed through a 5-year research program sponsored by the U.S. Department of Defense, through the ESTCP program. The analysis includes monitoring of transient vacuum response to turning the extraction fans on and off, helium tracer testing and mass emission monitoring combined with a mathematical model of fluid flow in a two-layer system (Hantush and Jacob, 1955). The incremental cost to include the additional lines of evidence is small and the savings generally increase as the size of the building increases, so net savings are to be expected for medium or large buildings. Case studies from three buildings of different sizes will be included to demonstrate the application of the new lines of evidence.
Todd McAlary has a Bachelor’s degree in Geological Engineering, a Master’s degree in Contaminant Hydrogeology, a Ph.D. in Chemistry and has been the Practice Leader for Vapor Intrusion services at Geosyntec Consultants, Inc. for 20 years. He was one of three co-authors of the U.S. EPA 2001 RCRA guidance on vapor intrusion and has been a member of EPA’s expert panel on vapor intrusion since 2000. He has conducted applied research on several new technologies for vapor intrusion assessment and mitigation, including passive sampling, high volume soil vapor sampling, mathematical modeling, tracer testing, building pressure cycling and recently developed a new method for calculating building-specific attenuation factors from flow and vacuum measurements. He also has a Certificate in University Teaching and is an Adjunct Professor at the University of Toronto.
5:30 p.m. – 9:00 p.m.
Block Brewing Company
1140 S Michigan Ave
Howell, MI 48843
Schedule of Events:
5:30 p.m. – 6:15 p.m. – Registration and Cocktail Reception
6:15 p.m. – 7:15 p.m. – Dinner
7:15 p.m. – 9:00 p.m. – Presentation Followed by Questions