flow include a surfactant such as sodium dodecyl sulphate tween 80 vitconol other environmentally friendly or biodegradable surfactants or other types of materials having a similar effect on the u03b6 potential fig1 is a schematic diagram of three anodes and two cathodes positioned in situ in a region of sandy soil to determine the most efficient well wall design for removal of anions such as chromates from a particular soil region chromate anions are removed predominantly by electromigration toward the anodes any electroosmosis toward the cathode either in the well wall or the soil is undesirable because it will oppose the direction of the electromigration however since the soil was sandy the anode wells had to be designed with a low kh i e ceramic and or kaolinite in order to retain the solution containing the remediated chromium anions furthermore the return of chromate anions into the soil from the anode by electroosmosis was deterred by adding a sodium dodecyl sulphate surfactant to the anode to reduce the zeta potential of the well wall and perhaps the zeta potential of the soil the well walls for anode wells 50 52 and 54 were made of 4 u2033 diameter pvc polyvinyl chloride pipe schedule 40 with horizontal slots perforations about 3 mm wide the anode wells were wrapped with porous polyethylene filter to prevent the soil particles from entering the well the well surroundings were packed with a mixture of kaolinite georgia kaolinite rc 32 crozier nelson houston tex and sand about 1 2 mm diameter silica sand the anode wells 52 and 54 were packed with a mixture of 20 weight percent wt kaolinite and 80 wt sand the anode well 50 had a double wall structure consisting of two perforated pvc pipes about one inch apart and packed.