Abstract: Halogenated organics contaminating soil formations are decomposed by an applied voltage-enhanced Grignard reaction with metallic magnesium, either pure or in alloy form, that has been lowered into the soil formation, in conjunction with hydrolysis of the resulting organomagnesium halide to release the halogen from the starting contaminant. Renewal of the magnesium surface to permit an enhanced decomposition is achieved by connection of the magnesium electrode to an electric potential generator and applying the potential either continuously or in pulse-wise manner, preferably repeatedly reversing the applied potential to electrochemically clean the magnesium-containing electrode surface. Dissolved Cr(VI) is likewise reduced to chromium of lower oxidation states and thus rendered less toxic.