Anchor QEA, LLC
Michael Gefell, P.G., C.P.G., is a Principal Scientist at Anchor QEA. He holds a BA in Geological Sciences from Cornell University and MS in Geology from the University of California – Davis. Mr. Gefell has over 29 years of experience in environmental site assessment and remediation. Primary areas of interest include: quantitative hydrogeology, NAPL mobility assessment, groundwater/surface-water interaction, innovative site characterization methods, fractured bedrock, modeling and remedial design. He is the Technology Spotlight Editor and an Associated Editor of Groundwater journal, and recipient of the Technology Award from the National Ground Water Association.
Advancing Mobility Testing and Aqueous-Phase Sampling in NAPL Zones
Michael J. Gefell, P.G., C.P.G. (email@example.com) (Anchor QEA, Lakewood, CO, USA)
Dimitri Vlassopoulos, Ph.D., and Masa Kanematsu, Ph.D. (Anchor QEA, Portland, OR, USA)
David S. Lipson, Ph.D. (HRS Water Consultants, Inc., Lakewood, CO, Lakewood, CO, USA)
Bruce Thompson (de maximis, inc., Windsor, CT, USA
At non-aqueous phase liquid (NAPL) sites, NAPL mobility and aqueous-phase concentrations directly affect risk and remedial design. NAPL effective hydraulic conductivity (Kn) affects pore-scale recoverability, velocity and flux. It can be estimated and the overall NAPL mobility interpreted from laboratory NAPL mobility tests using multiple lines of evidence. If NAPL is immobile or can be contained by an engineered remedy, aqueous chemical concentrations and fluxes drive risk and remedial needs. However, any NAPL included in a water sample or adhered to a passive hydrophobic sampler is added mass that is reported with the dissolved concentration, thereby overstating actual conditions. Laboratory and field data are presented demonstrating the use of porous, hydrophilic, ceramic capillary barriers to exclude NAPL and collect representative porewater and groundwater samples by diffusion or pumping. In combination, the methods presented herein mark significant advances in our ability to quantify mass fluxes associated with NAPL zones.