1996 Technical Reports
Numerical Analysis of the In-Well Vapor-Stripping System Demonstration at Edwards Air Force Base
M.D. White, T.J. Gilmore
Pacific Northwest National Laboratory, Richland, Washington
PNNL-11348 (UC-2010), Pacific Northwest National Laboratory, Richland, Wa., 1996.
Summary
In-well vapor stripping is a remediation technology designed to remove dissolved volatile organic compounds from groundwater. The in-well vapor-stripping system comprises an engineered and a hydrologic component that operate in unison to form an in situ recirculation pattern. The engineered system is driven with compressed air, utilizing an air-lift pumping scheme that volatilizes dissolved organic compounds. The volatile vapors are removed from the gas stream above the ground surface and pumped water is infiltrated into the hydrologic system below the ground surface. This technology was demonstrated at Edwards Air Force Base (AFB) near Mojave, California, by collaborating researchers from Pacific Northwest National Laboratory and Stanford University as part of the interim cleanup activities at the base. Preliminary results on the performance of the demonstration system have been reported and indicate a significant reduction in the concentration of contaminant, dissolved trichloroethylene (TCE), around the demonstration well.
Performance Assessment of the In-Well Vapor-Stripping System
T. J. Gilmore, M. J. Pinto, M. D. White, S. Ballard, S. M. Gorelick, O. Taban, F. A. Spane, Jr.
Pacific Northwest National Laboratory, Richland, Washington
PNNL-11414 (UC-2010), Pacific Northwest National Laboratory, Richland, Wa., 1996.
Summary
In-well vapor stripping is a remediation technology designed to preferentially extract volatile organic compounds dissolved in groundwater by converting them to a vapor phase and then treating the vapor. This vapor-stripping system is distinctly different from the more traditional in situ air-sparging concept. In situ sparging takes place in the aquifer formation; in-well vapor stripping takes place within the well casing.
The system was field demonstrated at Edwards Air Force Base, California; the first-time demonstration of this technology in the United States. Installation and testing of the systemm were completed in late 1995, and the demonstration was operated nearly continuously for 6 months (191 days) between January 16 and July 25, 1996. Postdemonstration hydrochemical sampling continued until September 1996.
Gas Release During Salt-Well Pumping: Model Predictions and Comparisons to Laboratory Experiments
L.M. Peurrung, S.M. Caley, E.Y. Bian, P.A. Gauglitz
Pacific Northwest National Laboratory, Richland, Washington
PNNL-11310 (UC-2030), Pacific Northwest National Laboratory, Richland, Wa., 1996.
Summary
The Hanford Site has 149 single-shell tanks (SSTs) containing radioactive wastes that are complex mixes of radioactive and chemical products. Some of these wastes are known to generate mixtures of flammable gases, including hydrogen, nitrous oxide, and ammonia. Nineteen of these SSTs have been placed on the Flammable Gas Watch List (FGWL) because they are known or suspected, in all but one case, to retain these flammable gases. Salt-well pumping to remove the interstitial liquid from SSTs is expected to cause the release of much of the retained gas, posing a number of safety concerns. Research at the Pacific Northwest National Laboratory (PNNL) has sought to quantify the release of flammable gases during salt-well pumping operations. This study is being conducted for Westinghouse Hanford Company as part of the PNNL Flammable Gas Project. Understanding and quantifying the physical mechanisms and waste properties that govern gas release during salt well pumping will help to resolve the associated safety issues.