The Migration and Entrapment of DNAPLs in Physically and Chemically Heterogeneous Porous Media

Abstract

Dense nonaqueous phase liquids (DNAPLs) are common subsurface contaminants at many Department of Energy (DOE) hazardous waste sites. The migration and entrapment of DNAPLs at these sites is greatly influenced by subsurface heterogeneity, both physical and chemical. Unfortunately, the physics of DNAPL flow in chemically heterogeneous systems is poorly understood and, hence, multiphase flow simulators typically assume that subsurface soils are completely water-wet (chemically homogeneous). The primary objective of this research is to improve our understanding of and ability to simulate the influence of subsurface chemical heterogeneities on DNAPL flow and entrapment in the saturated zone. Laboratory and numerical investigations are being conducted for a matrix of organic contaminants and porous media encompassing a range of wettability characteristics. Specific project objectives include: (1) quantification of system wettability and interfacial tensions; (2) determination of hydraulic property relations; (3) investigation of DNAPL infiltration behavior in two-dimensional systems; (4) modification of a continuum based multiphase flow simulator to account for coupled physical and chemical heterogeneity; and (5) exploration of the migration of DNAPLs and the development of innovative remediation schemes under heterogeneous conditions using this model.