Demonstration Results

The site selected for the demonstration was a shallow alluvial plume containing approximately 300 µg/L of trichloroethene (TCE) at F. E. Warren Air Force Base, Wyoming. As of January 2005, the e-barrier had been operating continuously for 24 months. TCE flux reduction was sustained over this period. At the highest imposed potential (6.5 volts), bulk TCE flux reduction of 90% was demonstrated. Data from the primary transect through the center of the e-barrier indicated TCE flux reduction of 95%. In general, no adverse reaction intermediates were observed. An exception was the apparent formation of chloroform at the center of the e-barrier at 6.5 volts. Cost components associated with the demonstration e-barrier included (1) capital expenses of $409/ft² of intercepted plume and (2) operation and maintenance (O&M) expenses of $10/ft²/year. Taking into account opportunities for cost reduction and economies of scale, the costs for full-scale systems are anticipated to be 25 to 50% lower than the demonstration cost. Using this assumption, a typical full-scale e-barrier would have capital and O&M costs similar to those of current proven technologies for treating TCE (i.e., pump-and-treat and zero-valent iron permeable reactive barriers).