Long-term Performance of Permeable Reactive Barriers Using Zero-valent Iron: An Evaluation at Two Sites

The permeable reactive barrier (PRB) technology is an in-situ approach for remediating groundwater contamination that combines subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from a groundwater plume is achieved by altering chemical conditions in the plume as it moves through the reactive barrier. Because the reactive barrier approach is a passive treatment, a large plume can be treated in a cost-effective manner relative to traditional pump-and-treat systems. There have now been more than forty implementations of the technology in the past six years, which have proven that passive reactive barriers can be costeffective and efficient approaches to remediate a variety of compounds of environmental concern. However, in all of the installations to date comparatively few data have been collected and reported on the long-term performance of these in-situ systems, especially with respect to the buildup of surface precipitates or biofouling (O’Hannesin and Gillham, 1998; McMahon et al., 1999; Puls et al., 1999; Vogan, 1999; Phillips et al., 2000; Liang et al., 2000).