Permeable Reactive Barrier (PRB) Demonstration Treatment System

A zero-valent iron PRB was installed in 1995, by the U.S. Air Force, as a technology demonstration across a portion of the Main TCE Plume just north of the Source Area Reduction System (SARS).  The intent of the technology demonstration was to test the feasibility of an in situ passive treatment system for TCE-contaminated groundwater in Operable Unit 5.  The system, as installed, consisted of an iron filing wall installed perpendicular to the Main TCE groundwater plume and used sheet piling walls to assist in funneling contaminated groundwater through the treatment zone of the zero-valent iron.  In practice, the iron facilitates the reductive dechlorination of the chlorinated solvents which are reduced to non-detectable concentrations within the treatment zone of the wall. The PRB, installed by the Air Force, remains in place but is no longer effective for the treatment of chlorinated solvents in groundwater.