The presence of dense nonaqueous phase liquids (DNAPLs) in aquifers poses a significant problem to drinking water quality. Because DNAPLs slowly dissolve, are toxic, and tend to penetrate deep into the porous medium, they are a source of long term contamination. Current conventional pump-and-treat techniques are inadequate in remediating DNAPL contaminated aquifers. The use of surfactants to enhance the pump-and-treat technique, however, shows considerable promise, but has only been studied extensively in homogeneous columns with uniformly distributed DNAPLs. The objective of this study was therefore to completely remove the DNAPL perchloroethylene (PCE) from one-dimensional heterogeneous porous medium columns with non-uniform PCE distributions and to determine the effect of the surfactant on mass transfer and hydraulic behavior of the surfactant flood. For comparison, surfactant (Tween 80) enhanced remediation was first studied for a homogeneous porous medium and subsequently for several heterogeneous porous medium columns at various degrees of water saturation. The homogeneous column consisted of a coarse sand, while the heterogeneous columns consisted of a fine sand layer between two coarse sand layers. PCE spills were applied to the tops of the columns and allowed to redistribute until static equilibrium was reached. The columns were first flushed with water to remove most of the free PCE and then flushed with surfactant solutions (4.0% by volume) and effluent samples were collected and analyzed for PCE. Volumetric water and PCE content values, as well as PCE concentrations in solution at each measurement location, were determined by means of dual-energy gamma radiation measurements. Although the PCE was readily removed from all columns, the PCE concentrations in the effluent solutions of the initially unsaturated column never reached the micelle solubility limit. The volumetric PCE content decreased more rapidly in the coarse than in the fine sand, implying a greater mass transfer coefficient for the coarse than for the fine sand. Following the spills, the unsaturated porous medium had lower volumetric PCE contents than the saturated porous media. Consequently, smaller water/PCE interfacial areas and lower mass transfer coefficients were determined during unsaturated than during saturated conditions.