| Abstract: | Air sparging has been used for several years as an in situ technique for removing volatile compounds from contaminated ground water, but few studies have been completed to quantify the extent of remediation. To gain knowledge of the air flow and water behavior around air injection wells, laboratory tests and model simulations were completed at three injection flow rates (62, 187, and 283 lpm) in a cylindrical reactor (diameter - 1.2 m, depth = 0.65 m). Measurements of the air flux distribution were made across the surface of the reactor at 24 monitoring locations, six radial positions equally spaced along two orthogonal transects. Simulations using a multiphase flow model called T2VOC were completed for a homogeneous, axisymmetric configuration. Input parameters were independently measured soil properties. In all the experiments, about 75 percent of the flow injected exited the water table within 30 cm of the sparge well. Predictions with T2VOC showed the same. The averages of four flux measurements at a particular distance from the sparge well compare satisfactorily with T2VOC predictions. Measured flux values at a given radius varied by more than a factor of two, but the averages were consistent between experiments and agreed well with T2VOC simulations. The T2VOC prediction of the radial extent of sparging coincided with the distance out to which air flow from the sparge well could not be detected in the reactor. The sparging pattern was relatively unaffected by the air injection rate over the range of conditions studied. Changes in the injection rate resulted in nearly proportional changes in flux rates. |
