Technical Approach

Results of the SEED project suggest that zero-valent iron may be sufficient for treatment of explosives-contaminated groundwater when applied at the field scale. However, the contrast between recent column results and results obtained from batch experiments illustrates the substantial uncertainties inherent in extrapolating from the laboratoryto field-scale. This project will address the key areas of uncertainty through a combination of large column and pilot-scale field tests designed to lead directly to full-scale implementation. Specifically, the products and kinetics of removal of TNT and RDX will be investigated using columns in the laboratory and at the Umatilla Army Depot. The research team will use a variety of methods to extract and characterize all residues of TNT and RDX, determine the effects of changing several key operating conditions, and integrate all results in a reactive-transport model that should be sufficient to begin the design of a full-scale demonstration. Some of this study will be performed in canister reactors fed by a slip-stream from the influent of the existing pump-and-treat system at the Umatilla Chemical Depot. However, further work will emphasize the implementation of Fe  as the reactive material in a full scale, in situ permeable reactive barrier of conventional design.