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Spectral Induced Polarization Response of Unconsolidated Saturated Sand and Surfactant Solutions
Citation:
Magill, M., D. D. WERKEMA, AND D. Kreamer. Spectral Induced Polarization Response of Unconsolidated Saturated Sand and Surfactant Solutions. Presented at American Geophysical Union Fall Annual Meeting, San Francisco, CA, December 15, 2008.
Impact/Purpose:
Presentation
Description:
Dense non-aqueous phase liquids (DNAPL), such as chlorinated solvents, are common groundwater contaminants. Traditional pump-and-treat methods are often not effective at removing residual DNAPL from the subsurface. Surfactant-enhanced aquifer remediation is a promising remediation method that utilizes subsurface surfactant floods to decrease the interfacial tension between the non-aqueous phase and groundwater and increase the contaminant solubility and mobility in water. This remediation method is not widely used because of unknown subsurface distribution and effectiveness. The ability to effectively monitor and perhaps map the spatial distribution of surfactant floods used in remediation could reduce monitoring uncertainty and increase their use. Previous work has shown that surfactants in aqueous solutions significantly alter the solution conductivity, but this work has not investigated the surfactant response in aquifer type materials. In this project, spectral induced polarization measurements of four surfactant aqueous solutions in a sand matrix were evaluated. The frequency range assessed was 0.732 Hz to 187.5 Hz. The surfactants, which are typically used in the remediation of tetrachloroethylene, were Aerosol MA-80-I, Dowfax 8390, and Steol CS-330. These surfactant solutions were injected into a closed system of 20-30 Ottawa silica sand. Resistivity and phase responses were measured. The surfactant treatments altered both phase and resistivity in varying degrees, with Aerosol MA-80-I showing a marked decrease in both, and the Steol CS-330 exhibiting little change relative to the control column. These results suggest geoelectrical property changes may be an applicable property to map and monitor surfactant floods in the subsurface. Future work will continue to investigate this application.