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Laboratory column experiments were conducted to investigate the reduction of gasoline component leaching through the use of soil venting. Soil columns and procedures employed were aimed at simulating conditions in the vadose zone. Gasoline-contaminated soil columns that had been subjected to varying periods of soil venting were leached with water under both saturated and unsaturated flow conditions. Experiments were conducted testing for non-equilibrium transport and demonstrating reductions of gasoline constituent leaching.

Glass columns 10 cm long and 5.4 cm in diameter were packed with a clean glacial outwash sand and brought to low saturations of water and gasoline by controlling fluid pressures across capillary barriers. The columns were then subjected to steady air flow, each for a different length of time, so that each represented a different stage in the soil venting process. Water was percolated through these columns arid effluent was sampled and analyzed for benzene, toluene, ethylbenzene, m-/p-xylenes, o-xylene and naphthalene. Results of experiments testing for non-equilibrium transport using changes in water flow rate, indicated that chemical equilibrium between phases was reached in effluent water. Results from columns vented for different lengths of time showed soil venting to be effective at reducing constituent concentrations in leachate ultimately to < 1 mug L-1. The results were compared to an equilibrium based soil venting model.