SURFACTANT-ENHANCED REMEDIATION OF A TRICHLOROETHENE-CONTAMINATED AQUIFER - 2 - TRANSPORT OF TCE

Field studies were conducted under an induced gradient in a trichloroe thene (TCE)-contaminated aquifer at Picatinny Arsenal, NJ, to study(a) the rate-limited desorption of TCE from aquifer sediments to water and (b) the effect of a surfactant (Triton X-100) on the desorption and t ransport of TCE. Clean water was injected into the contaminated aquife r for 206 day. Triton X-100 was added for a 36-day period (days 36-71 from the start of clean water injection). The effect of Triton X-100 o n the desorption and transport of TCE in the field was examined by obs erving the concentrations of these two solutes in four monitoring well s 3-9 m from the injection wells. These data show a small but discerni ble increase in the TCE concentration in two of the wells correspondin g approximately to the time when surfactant reaches the wells; in the other two monitoring wells, the increase in TCE concentration is negli gible. A solute transport model that assumes local sorption equilibriu m and used a laboratory-derived distribution coefficient could not ade quately describe TCE desorption and transport observed in the aquifer. Two model formulations that accounted for rate-limited sorption-two-s ite and multisite models-fit the data well. TCE concentrations after s urfactant injection were underpredicted by the models unless mass tran sfer rate was increased to account for the effect of surfactant on the rate of TCE desorption. The concentration data from the two wells and the model analysis suggest that the rate of TCE desorption is increas ed (by approximately 30%) as a result of Triton X-100 injection.