In-Well Air Stripping/Bioventing Study at Tyndall Air Force Base, Florida

This study was conducted to determine the feasibility of incorporating in-well air stripping systems into the design of bioventing systems to effectively extend bioventing to simultaneously remediate hydrocarbon contamination in both the vadose and saturated zones. The field study was conducted for 12 months between June 1994 and June 1995. The data demonstrated that the in-well air stripping systems were able to circulate the groundwater throughout the 25-foot radius of influence. The air stripping component of the systems performed well even though the air-to-water ratio could not be optimized. The well systems were shown to be effective at remediating the benzene, toluene, ethylbenzene, and xylenes (BThX) of the hydrocarbon contamination in the groundwater within the treatment cell. The following conclusions were made: (1) the air lift pumping mechanism was capable of circulating groundwater in the aquifer; (2) the volatile compounds were effectively stripped from the groundwater; (3) anoxic groundwater entering the well was sufficiently oxygenated during air lift; (4) the residual oxygen in the off-gas from the in-well air stripping system was sufficient for supporting bioventing in the vadose zone; (5) volatile compounds in the off-gas from the well system were degraded in the vadose zone through bioventing when the mass loading did not exceed the degradative capacity of the microorganisms; and (6) bioventing was very effective for remediating residual hydrocarbon contamination in the vadose zone. Overall, the study proved that extending bioventing through incorporation of in-well air stripping was feasible and that the technology should be pursued. PDF updated 30 July 2012.