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• EXECUTIVE SUMMARY Bench-scale treatability testing was conducted on soil and groundwater from the Exxon 43942 site in Stockton, California, which contained diesel range total petroleum hydrocarbons (TPH-d), gasoline range total petroleum hydrocarbons (TPH-g), BTEX compounds (benzene, toluene, ethylbenzene and xylenes), and methyl-t-butyl ether (MTBE) Testing was conducted to evaluate and compare the ability of ozone (03) and Peroxone (a mixture of ozone and hydrogen peroxide) to remove petroleum hydrocarbons from soil and groundwater at the site and to determine whether removal was due to volatilization (by sparging) or to destruction (via chemical oxidation) This was accomplished by comparing the effect of sparging with a chemically inert gas (nitrogen) to the effect of sparging with ozone The effect of each treatment on hexavalent chromium [(Cr(VI)] (which can be formed by oxidation of naturally occurring trivalent chromium) and other secondary water quality parameters were also evaluated The potential fate of Cr(VI), which was sometimes formed by ozone and Peroxone, was also assessed The laboratory study clearly demonstrated that ozone and Peroxone (a mixture of ozone and hydrogen peroxide) could destroy TPH-g, TPH-d and BTEX in soil and groundwater from this site Destruction appears to be more efficient with Peroxone, which volatilized lower amounts of COCs than ozone Sparging with nitrogen (an inert gas) also . significantly reduced the amount of CDCs in groundwater, but the removal was due to volatilization, not destruction of hydrocarbons Treatment with ozone and Peroxone generated Cr(VI), but tests indicate that this Cr(VI) can naturally attenuate when in contact with untreated soil In some tests, the amount of Cr(VI) produced was very low (< 6 ttg/L) In other tests, the Cr(VI) was very high (570 gg/L) The cause of the variability is unknown Tests indicated that untreated soil could reduce Cr(VI) to its trivalent form, and that the amount of Cr(VI) that can be generated is significantly less than the amount that untreated soil is capable of reducing Bromate was not detected above the detection limit of 8 µg/L in either the ozone or Peroxone tests Although the concentration of bromide decreased in these tests, it was not converted to bromate The effect of ozone and Peroxone on most other water quality parameters was small Exceptions were barium and vanadium, the concentrations of which increased upon treatment The groundwater oxidant demand was 110-180 mg 03/L, which is lower than predicted based on the concentrations of COCs, but indicates that the clean groundwater does not have an excessively high demand The soil oxidant demand was 400-700 mg 03/kg soil PRIMA Environmental Eval of Peroxone June 1,2005 ETIC-Exxon#f3942