Dc Resistivity Monitoring Of Potassium Permanganate Injected To Oxidize Tce In Situ

The X-70 1B Site at the Portsmouth Gaseous Diffusion Plant, Piketon, OH, was<br>selected by Department of Energy’s Office of Science and Technology for a<br>demonstration of in-situ groundwater treatment by chemical oxidation. The goal was to<br>oxidize trichloroethylene (TCE), present in both the soil and groundwater of the local<br>_ Gallia aquifer, by circulating a solution of potassium permanganate (KMnO4) between<br>two horizontal wells positioned to intercept contaminated groundwater migrating from a<br>nearby industrial waste holding pond. Potassium permanganate is a salt. Laboratory<br>measurements showed that the addition of 1 .O% of potassium permanganate increased the<br>fluid conductivity of a Portsmouth groundwater sample from 339 to 7250 mS/m, or<br>equivalently, decreased the electrical resistivity from 29 ohm-m to 1.4 ohm-m. Although<br>the contaminated Gallia aquifer is only about 1.5m thick at this site, and is overlain by<br>nearly 8m of Minford clay, geophysical modeling showed that the change in resistivity<br>would be detectable from the surface using DC electrical resistivity if the injection<br>flooded a sufficient portion of the aquifer. Field measurements made using a multielectrode<br>resistivity system along two lines - one parallel and one perpendicular to the<br>two horizontal wells - confirmed that the potassium permanganate injection was<br>detectable as a subtle change in the resistivity section. The change in resistivity is<br>apparent after the background resistivity information collected before the injection is<br>removed from the data. We conclude that geophysical monitoring of in situ chemical<br>oxidation is a feasible, and a could reduce reliance on monitoring wells.