A field-scale demonstration of air sparging to remediate tritiated fluids

Two pilot field-scale studies were conducted during the period of May 24 to July 22, 1996, to evaluate the potential of air sparging to remediate tritiated fluids. Previous analytical solutions to the rate of tritium removal were evaluated and compared to the experimental results. The analytical solution of Craig and Gordon that describes isotopic fractionation of an evaporating body of water appears to most accurately describe the process, versus the more limited isotopic exchange equation of Slattery and Ingraham and the mass transfer equation of Wilson and Fordham, which are accurate only at moderate to high humidities and do not describe the tritium enrichment process that would occur at low humidities. The results of the two experiments demonstrated that air sparging of tritium is a viable process in the field. Tritium removal rates of 60 percent were reported during the first experiment and 66 percent for the second experiment. Comparison to previous laboratory work revealed that rates could have been improved by starting with higher concentrations, utilizing smaller bubbles, and longer bubble path lengths. Risks associated with the pilot study were greater the closer one worked to the experiment with a maximum increase in the Lifetime Excess Total Risk per Unit Uptake of 2.4 x 10{sup -5}. Conduct of this experiment at locations with much higher activities of tritium would significantly increase the associated risk.