Submitted to: Advances in Water Resources
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/4/2004
Publication Date: 6/20/2004
Citation: Phelan, T.J., Lemke, L.D., Bradford, S.A, O'Carroll, D.M., Abriola, L.M. 2004. Influence of textural and wettability variations on predictions of DNAPL persistence and plume development in saturated porous media. Advances in Water Resources. 27:411-427. Interpretive Summary: Organic liquid contaminants have leaked into groundwater systems at many hazardous waste sites. Here the organic liquid can slowly dissolve into flowing water and threaten drinking water supplies. Many groundwater systems have variations in soil texture (size) and composition (chemical properties). Computer simulations explored the role of such variations on organic liquid migration and cleanup. Results indicate that variations in soil texture and composition can have important implications for organic liquid fate in groundwater systems. Knowledge of site specific soil characteristics will likely be required to predict this behavior.
Technical Abstract: Numerical simulations examine the migration, entrapment, and mass recovery behavior of DNAPLs in aquifer systems with coupled textural and wettability variations. Permeability fields of varying degrees of heterogeneity were generated with sequential Gaussian simulation, based upon geostatistical parameters derived from core grain size measurements in a sandy glacial outwash aquifer. Using solid-phase wettability as a representative metric for chemical heterogeneity, organic-wet mass fraction was correlated to porous media permeability. A multiphase flow simulator incorporating wettability dependent constitutive relationships for capillary behavior was used to obtain residual saturation distributions for tetrachloroethene (PCE) spill events in these synthetically generated aquifers. The simulated saturation distributions were then used as initial conditions in compositional simulations of PCE dissolution, to examine the effect of coupled wettability and permeability variations on DNAPL mass recovery. Simulations reveal considerable differences in predicted depth of organic penetration, extent of vertical spreading, and magnitude of maximum entrapped saturation for the various modeled scenarios. These differences are directly linked to observable variations in effluent concentration and mass recovery predictions in the aqueous phase flushing simulations. Results suggest that mass recovery behavior may be highly realization dependent.