Field Injection and Verification of Nanometer-Size Zero-Valent Iron to Remediate Hexavalent Chromium at DOE’s Hanford Site

摘要

Laboratory and field investigations have been conducted to evaluate the feasibility of injecting nanometer-size zero-valent iron (nZVI) into the subsurface at the U.S. Department of Energy Hanford Site in Washington State. The purpose of this work was to investigate a practical method of repairing portions of the In Situ Redox Manipulation barrier, located in the 100-D Area of the Hanford Site. This barrier was installed to intercept a hexavalent chromium [Cr(VI)] plume moving towards the Columbia River. The investigation involved evaluation of suitable nZVI compounds that would produce reducing conditions in the aquifer necessary to reduce Cr(VI) to immobile trivalent chromium. After initial screening of candidate materials, geochemical and injectability laboratory studies and computer modeling were performed, resulting in identification of RNIP-M2 (RNIP), by Toda Kogyo Corporation, as the most suitable material for mending the ISRM barrier.