TREATMENT OF CHROMIUM VI IN THE UNSATURATED ZONE COUPLED WITH GEOPHYSICAL

In Situ Chemical Reduction (ISCR) is a promising technique for the transformation of highly toxic and soluble hexavalent Chromium (CrVI) into the relatively low toxicity and less mobile trivalent Chromium (CrIII). There have been several studies focusing on CrVI contaminated groundwater (EPA 2000). However, in situ remediation techniques of unsaturated soils has not been diffusely tested (Puls and Khan, 2003; Ludwig and Su, 2005; Ludwig et al, 2007). Hystorically, the Spinetta Marengo industrial site (Alessandria, Italy) had been contaminated with Cromium (Cr) due to the activities of the chrome planting facility, dismantled in the early 80s. The data suggest that CrVI in the unsaturated soils is the source of groundwater contamination. A novel pilot test study has been conducted at the SM site to evaluate the effectiveness of different treatment techniques in reducing CrVI concentrations in the unsaturated zone. The objects of this research were also (1) to examine the solubility of the precipitated solid phases in the treatment zone; (2) tocompare the feasibility of different injection techniques; (3) to verify that the approach can be used in a safe manner; and (4) to evaluate the potential of the treatment for a cost-effective full-scale site remediation.