Makoto Nakashima

Installation of a Permeable Groundwater Treatment Wall and Its Remedial Effects

In order to prevent groundwater contamination of chlorinated organic compounds from flowing outside of the facility property, a permeable treatment wall using zero-valent iron was installed downgradient of the contaminant source. The permeable groundwater treatment wall consisted of block-style reactive zones, installed in a zigzag-shifting disposition. Each reactive zone segment was approximately 0.6 m thick, 3.0 to 6.0 m long, and 7.0 m deep. The reactive zones are intended to clean up the contaminated groundwater passing through the shallow boulder gravel aquifer. Remedial effectiveness has been confirmed through monitoring. The concentrations of tetrachloroethylene (PCE), trichloroethylene (TCE) and cis-1,2-dichloroethylene (cis-1,2-DCE) in the treated water were confirmed to be below the levels set by the Japanese Environmental Quality Standards for Groundwater (EQSG).