Senior Principal Environmental Consultant
David Folkes is a Senior Principal Environmental Consultant based in Colorado with more than 35 years of experience focused on environmental and geotechnical consulting throughout the United States and Canada. One of the nation's foremost experts on vapor intrusion (VI) evaluation and mitigation, Dave was invited by U.S. EPA to address the national Resource Conservation and Recovery Act meetings held in 2000 and 2002 on VI issues impacting sites throughout the country.
ALTERNATE PLATFORM PRESENTER – Vapor Intrusion: Don't Hold Your Breath
Vapor Intrusion Mitigation by Passive Venting of Aerated Floors
A 3-D CFD model was used to evaluate the efficacy of passive venting of aerated floors to control vapor intrusion. Passive venting eliminates the need for fans and associated operation and maintenance costs, while aerated floors allow efficient sub-slab venting with minimal friction losses, increasing the effectiveness of weak passive forces (thermal, wind). Passive venting was simulated in the model by varying temperatures in the building, the void space, and outdoor air. The resulting thermal gradients caused depressurization and venting of the aerated floor void space. With one riser pipe, makeup air was provided by downward flow through the perimeter crack. With two riser pipes, the model predicted upward flow through one riser pipe and downward air flow in the other riser pipe, with some downward air flow through the perimeter crack. Both scenarios would result in effective vapor intrusion control.