2008a. “Field Evidence for Flow Reduction through a Zero-Valent Iron Permeable Reactive Barrier,” Groundwater Monitoring and Remediation 28(3): 47–55

The combination of detailed multilevel ground water geochemistry samples, a natural-gradient tracer test, minislug tests, and a numerical flow and transport model was used to examine flow through a zero-valent iron permeable reactive barrier (PRB) installed to remove explosives from ground water. After 20 months of operation, the PRB continued to completely re-move explosives from the ground water flowing through it. However, the data indicate that a portion of ground water flow was being diverted beneath the PRB. Ground water geochemistry was significantly altered by the PRB, and concentrations of some ions, including sulfate, carbonate, and calcium, were substantially reduced due to precipitation. Field data and numerical model results indicate that, after 20 months of operation, flow through the PRB was reduced to approximately one-third of its expected value. Background Zero-valent iron permeable reactive barriers (ZVI PRBs) have significant impacts on ground water geochem-istry. In addition to removing a broad range of contami-nants, they can remove dissolved oxygen, sulfate, nitrate, carbonate, calcium, and other ions and can lead to precipi