University of California Water Resources Center

Groundwater contamination by organic solvents, gasoline and other petroleum products, and similar nonaqueous phase liquids (NAPLs) is a widespread phenomenon resulting from leaking storage tanks, spills, and improper disposal techniques (Duffy et al., 1980; Harris et al., 1982i Mackay et al., 1985). Due to the potential health problems associated with the occurrence of these carcinogenic or mutagenic organic compounds within groundwater systems, considerable interest in the dynamics of NAPLs within the vadose and phreatic zones exists.

Current efforts at understanding NAPL dynamics within subsurface environments are principally directed toward successful description of transport processes through the use of numerical solutions to flow equations (Kuppasamy et al., 1987; Faust, 1985). Immiscible phase flOW, dispersive, diffusive, and convective transport of dissolved components, volatilization, sorption, and degradation are all recognized as important processes contributing to net organic contaminant transport (Baehr, 1987).