targeting the saturated zone. It is superior to the baseline technolo-
gies by virtue of eliminating the need for multiple vertical wells spread over several acres of land for extensive cleanup operations. It also significantly shortens the time required to complete cleanup operations. By actively injecting air (or other gas) to expel VOCs, it addresses a major limitation pos-
ed by the baseline technologies, where VOCs extraction declines over time due to diffusion-limited flow rates.

Accomplishments

This technology has been success-
fully demonstrated at the Savan-
nah River Site. Significant im-
provements in remedial perform-
ance were achieved over baseline

technologies in the air sparging/air stripping phases of this demonstra-
tion. The use of horizontal wells showed a fivefold increase in con-
taminant removal rate over that of vertical wells. Over the 20-week test period, the horizontal wells removed 16,000 pounds of chlor-
inated solvents. This rate was equivalent to 11 pump-and-treat wells pumping at a rate of 500 gallons per minute. Analysis of groundwater samples from moni-
toring wells showed a significant drop of TCE and PCE concentra-
tions in the groundwater after the completion of the demonstration. The use of horizontal wells for air sparging/vapor extraction at the Savannah River Site is predicted to result in a 40% cost savings compared to the use of conven-
tional pump-and-treat technology.