Surfactant Remediation of Soils Contaminated With Chlorinated Solvents

This thesis contains the study of two techniques that could be used in the remediation of dense nonaqueous-phase liquids (DNAPL) within typical aquifers: (1) the use of partitioning tracers to locate contaminated zones within the aquifer, estimate the volume of contaminant within the tracer swept volume, and/ or assess a remediation process performance, and (2) the use of surfactant enhanced aquifer remediation to remove contaminant from the aquifer. A partitioning interwell tracer test is where tracers are injected into an aquifer through one well and produced from another. A chromatographic lag of the tracers is observed in the produced fluid. The magnitude of the lag depends on the size of the tracer partition coefficient. This chromatographic lag can be used to note the presence of a contaminant and estimate the volume of contaminant between the injection and production wells. Performing this test before and after remediation can tell how much of the contaminant was removed. Surfactants can be used in a remediation effort to either enhance solubilization of existing contaminant or mobilize the contaminant trapped in the free phase. Each contaminant encountered requires that phase behavior experiments be performed to predict the behavior of the surfactant with the contaminant, the groundwater in the aquifer, varying amounts of salts, and any chemicals added to the surfactant solution such as co-solvents or polymer. Xanthan gum was used in the surfactant solution to enhanced the sweep efficiency of the displacement of the groundwater with the surfactant solution. The polymer was used in phase behavior studies, surfactant floods, and tracer tests. Several batch phase behavior studies were performed. Two different contaminants were examined, (1) trichloroethylene and (2) a field contaminant obtained from Hill Air Force Base, Utah. Several column experiments using soil from three field sites were conducted to assess the performance of either tracers, surfactants or both. The results of these studies and how they relate to the remediation of dense nonaqueous-phase liquid are the main objective of this thesis.