PNNL

Abstract

The Reactive Wells is a new groundwater remediation technology that replaces the filter pack sand of the typical groundwater well with absorbents, bio-amendments, oxidants, or reductants. These reactive materials form a reactive barrier that selectively detoxifies or stabilizes targeted contaminants as the Reactive Well operates. This patent-pending technology is an active, in-situ system that produces no secondary waste streams and is designed to treat ?hot spots? in relatively short periods of time. It is currently designed as a recirculating well, although some conditions may warrant a single pass system. One reactive material being evaluated for use in the filter pack is zero-valent iron (Fe-0). Chlorinated hydrocarbon compounds are among the large number of contaminants that Fe-0 degrades. Laboratory column experiments were undertaken to determine the residence time required for degradation of these contaminants by Fe-0. Laboratory experiments conducted with 1,1,2-Trichloroethane (TCA)- and 1,1-Dichloroethane (DCA)-contaminated groundwater, showed that the concentrations of these contaminants decrease by half in less than 4 minutes. Supporting data showed that Cr+6 concentration in the groundwater decreased by half in less than 0.2 minutes. Based on these results, a well pumping at 64 L/min through a 60-cm flow path could decrease the concentration of TCA and DCA from 1.5 mg/L to