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FIELD DEMONSTRATION STUDIES OF SURFACTANT-ENHANCED SOLUBILIZATION AND MOBILIZATION AT HILL AIR FORCE BASE, UTAH
Citation:
Knox, R. C., B. J. Shau, D. A. Sabatini, AND J. H. Harwell. FIELD DEMONSTRATION STUDIES OF SURFACTANT-ENHANCED SOLUBILIZATION AND MOBILIZATION AT HILL AIR FORCE BASE, UTAH. Chapter 5, , 49-63, (1999).
Description:
Surfactant-enhanced subsurface remediation can dramatically improve contaminant removal rates compared to the traditional pump-and-treat technology. Surfactants can be used to significantly enhance the solubilization of non-aqueous phase liquids (NAPL) constituents, or they can be used to reduce interfacial tensions thereby mobilizing the NAPL (mobilization). Both the solubilization and mobilization mechanisms were used to remediate separate portions of a NAPL-contaminated aquifer at Hill AFB, Utah. The demonstrations were conducted in cells contained by steel sheetpiling driven into an underlying impermeable layer. The solubilization demonstration cell showed excessive leakage through the sheetpiling; hence, the surfactant (Dowfax 8390) was not flushed through the entire cell. In spite of less than complete flushing of the cell, contaminant extraction in the solubilization cell was as high as 58% with ten pore volumes of surfactant flushing. In the mobilization cell, two surfactant solutions (Aerosol OT and Tween 80) were injected along with calcium chloride. The surfactant-mobilized NAPL had a higher viscosity than aqueous fluids resulting in reduced hydraulic conductivities and mounding of the solution. In under seven pore volumes, the average contaminant removal for the mobilization cell exceeded 90%. Flushing with water alone would have extracted less than 1% of the contaminant mass in the same time frame. The contaminant removal rates derived from pre-and post-demonstration soil cores are in concert with the contaminant mass removed in the extraction wells and generally agree with the pre- and post-demonstration partitioning tracer tests. The mobilization system was much more efficient than solubilization with both systems being much more efficient than water alone. By contrast, the solubilization system was much easier to design and implement. These demonstrations thus illustrate the exciting potential for surfactants to dramatically improve pump-and-treat remediation of residual oil.