An innovative technique for the in situ treatment of hexavalent chromium within unsaturated soils

In situ chemical reduction (ISCR) is a technique commonly used to transform highly toxic and soluble hexavalent chromium (CrVI) into relatively low toxic and less mobile trivalent chromium (CrIII). There have been several studies focussed on CrVI contaminated groundwater, but in situ remediation techniques of unsaturated soils have not been thoroughly tested (Fruchter et al 2000; Khan et al 2003; Ludwig et al 2007). The Spinetta Marengo (SM) industrial site (Alessandria, Italy) was contaminated with cromium (Cr) as a result of the activities of the chrome planting facility that was dismantled in the mid-1970s. Data indicated that the source of groundwater contamination was CrVI in the unsaturated soils. A novel pilot test study was conducted at the SM site to evaluate how effective different treatment techniques were in reducing CrVI concentrations in the unsaturated zone.