National Risk Management Research Laboratory, Groundwater, Watershed & Ecosystem Restoration Division
Dense Non-Aqueous Phase Liquids (DNAPL) are organic liquids comprised of slightly water-soluble chemicals or chemical mixtures that have a density greater than water. DNAPLs may pool atop low permeability layers upon entering the subsurface. Even with the removal or destruction of most pooled DNAPL mass, small amounts of the remaining contaminant, which had been transported into the low permeability layer, can dissolve into flowing groundwater and continue to act as a contamination source for decades. Recently developed models assume that transport in the low permeability zones is strictly diffusive; however, field observations suggest that more mass is stored in the low permeability zones than can be explained by diffusion alone.
This research will use numerical simulation to study remediation process at contaminated sites characterized by preferential pathways (high-permeability layers) interacting with surrounding low-permeability zones. The specific tasks include (1) DNAPL dissolution kinetics in source area, (2) fate and transport in high permeability zone, (3) incorporating the mass transfer into the low permeability zones, (4) estimating the time scale of back diffusion, and (5) understanding the effects of site conditions on natural attenuation processes in an aquifer system underlain by an aquitard with micro-fractures.
Huang J, Goltz M: Journal of Hydrologic Engineering (19)5: 1053-1058, 2014
Brown GH, et al: Aquitard contaminant storage and flux resulting from dense nonaqueous phase liquid source zone dissolution and remediation. Water Resources 48, W06531, doi:10.1029/2011WR011141, 2012
Huang J, Christ JA, Goltz MN: Analytical solutions for efficient interpretation of single-well push-pull tracer tests. Water Resources 46, W08538, doi:10.1029/2008WR007647, 2010
Groundwater; Flow; Transport; Modeling; Nonaqueous phase liquid; Remediation; Optimization;