Associate Professor, Department of Civil Engineering
Dr. Mumford is an Associate Professor in the Department of Civil Engineering at Queen’s University. He received his Bachelor’s and Master’s degrees from the University of Waterloo, his Ph.D. from McMaster University, and held a postdoctoral fellowship at the University of Western Ontario before joining Queen’s University in 2010. His research is focused on the study of multiphase flow in porous media and its application to the remediation of non-aqueous phase liquids in soil and groundwater, with particular specialization in the behaviour of gases in contaminated groundwater systems including in situ thermal remediation, bubble-facilitated transport, and the numerical simulation of gas migration and mass transfer.
PLATFORM PRESENTER – Vapor Intrusion: Don't Hold Your Breath
Potential Effects of Bubble-Facilitated VOC Transport on Vapor Intrusion: Column Experiments
Most conceptual and numerical models of vapor intrusion assume that the transport of volatile organic compounds (VOCs) from a source to near a building foundation is a diffusion-limited process. However, alternate conditions have been identified that could lead to faster transport and higher indoor air concentrations, including gas bubble flow in the saturated zone. In this study, a series of one-dimensional laboratory column experiments were used to measure VOC mass flux due to bubble-facilitated transport from LNAPL smear zones. Analysis of gas-phase samples collected from the top of the columns showed VOC mass fluxes that were two orders-of-magnitude greater than in control columns with no bubble flow. These results demonstrate the potential for bubble-facilitated transport to increase transport rates linked to vapor intrusion, and will serve as a basis for further development of conceptual and numerical models to investigate the conditions under which this mechanism may play an important role.