SEAR FIELD TESTS:
1) Canadian Forces Base Borden, June 1990 to August 1991:
There was a controlled release of Tetrachloroethylene (PCE) into the Borden Aquifer over a 3 meters square area contained by sheet piling that penetrated into the underlying clay aquitard. The Borden Aquifer consists of a clean sand with less than 1% clay, negligible organic materials and fresh groundwater. It was the responsibility of John Fountain to design, implement, monitor and interpret the results of a SEAR test using solubilization. This results of this test demonstrated that surfactant flooding is an effective way of rapidly removing NAPL from an aquifer, that surfactant can be successfully recycled (with volatile contaminants) through the use of airstripping and that persistence of NAPL in low flow zones extends the required time for restoration. Design and results of this test are described in more detail in the following reference:
Fountain, John C., R.C. Starr, T. Middleton, M. Beikirch, C. Taylor, and D. Hodge. (1996) "A Controlled Field Test of Surfactant-Enhanced Aquifer Remediation", Groundwater, 34(5) 910-916.
2) Corpus Christi, Texas, June 1991 to February 1993:
Carbon Tetrachloride contamination was found in a fined grained sand containing smectitic clays that varied from 1 to 15 percent by weight. There was negligible organic material and highly saline groundwater. Again it was the primary responsibility of John Fountain to design, implement, monitor and interpret the results of a SEAR test using solubilization. From this test it was found that NAPL removal is very rapid, but is governed by the hydraulic conductivity at the site and is further affected by the sorption of surfactants to smectitic clays. Design and results of this test are described in further detail in the following references:
Fountain, J.C., C. Waddell-Sheets, A. Lagowski, C. Taylor, D. Frazier, and M. Byrne, (1995). "Enhanced Removal of Dense Nonaqueous Phase Liquids Using Surfactants: Capabilities and Limitations from Field Trails", In: Surfactant-Enhanced Subsurface Remediation, D. Sabatini, R. Knox, and J. Harwell, eds., Amer. Chem. Soc. Symposium Series #594, 177-190.
Lee, M.D., G.E. Gregory, D.G. White, J.C. Fountain, and S.H. Shoemaker, (1995). "Surfactant-Enhanced Anaerobic Bioremediation of a Carbon Tetrachloride DNAPL. In Bioremediation of Chlorinated Solvents", In: Bioremediation of Chlorinated Solvents, Proceedings of the In-Situ and on-site Bioremediation Conference, R.E. Hinchee, A. Leeson, L. Semprini, eds., Battelle Press, 147-151.
Fountain, J.C., (1993). "Extraction of Organic Pollutants Using Enhanced Surfactant Flushing II: Pilot Scale Field Trial at Corpus Christi, Texas", New York State Center for Hazardous Waste Management, Tech. Rpt. 10 p.
3) Portsmouth Gaseous Diffusion Plant, Ohio, July 1996 to December 1996:
In conjunction with Intera Corporation and the Department of Energy, a SEAR flood was implemented to remove the primary contaminant Trichloroethylene (TCE) from a gravel aquifer containing smectitic clays that varied from 5 to 20 percent by weight. It was the responsibility of John Fountain to choose the surfactant system to be implemented. Characterization of the DNAPL distribution in the test cell included a partitioning tracer test before injection of surfactant, and methanol preserved sub-samples of multiple cores taken at 10 cm spacings. A microemulsification system blending surfactant, salt and alcohol was chosen as the most effective way to remove the DNAPL (through displacement of the contaminant). Results of this test can be found in further detail in the following report prepared by INTERA:
"The In-Situ Decontamination of Sand and Gravel Aquifers by Chemically Enhanced Solubilization of Multiple-Component DNAPLs with Surfactant Solutions" Phase II Final Topical Report: Solubilization Test and Partitioning Interwell Tracer Tests, DOE Contract Number DE-AC21-92MC29111, Submitted to Morgantown Energy Technology Center U.S. Department of Energy.
4) PPG Industries, Lake Charles, LA, January 1997 to June 1998:
Ethylene Dichloride (EDC) contamination was found in the 10 foot water bearing unit comprised of silty and clayey sands averaging 10% smectite clays by weight. A 25 by 15 foot area was enclosed by sheet pile barriers that penetrated into a lower clay unit. It was the primary responsibility of John Fountain to design, monitor and interpret the results of a SEAR test. To avoid the risk of downward mobilization of EDC into the regional aquifer by the lowering of interfacial tensions, surfactant solubilization was used. Characterization of the DNAPL in the test cell included a partitioning tracer test (January 1997) and methanol preserved sub-samples of multiple cores taken at 10 cm spacings to determine the amount of contamination initially present in the test cell. Surfactant injection was stopped as of June 1997, and the post water flood continued until December 1997. Coring of the test cell is planned for February 1998 to determine the efficiency of cleanup procedures.