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i 3.2 COC Removal The concentrations of GRO in the aqueous phase and in the off-gases are shown in Table 5 . All of the treatments significantly reduced the amount of GRO in the aqueous phase: in most cases, < 2 % of the GRO present in the Control remained after treatment and complete removal was seen in the tests employing H2O2, iron, and acid. However, most (34- 119%) of the GRO lost was volatilized rather than destroyed. Better GRO destruction was achieved using a lower dose of H202, probably because the reaction was less vigorous, resulting in a greater contact time between the oxidant and the GRO. Treatment with H202only resulted in very little (0-23 %) GRO destruction. Treatment with H2O2 and acid (with or with out iron) enhanced destruction to 63 -66% when the initial concentration of H2O2 was 2%. Treatment with chelated iron was probably the least effective treatment. Use of 2% H2O2 did not destroy any of the GRO . Although the 5% H2O2/FeEDTA test results suggest that 91 % of the GRO was destroyed, this number is probably significantly overestimated. Both the 2% H2O2/FeEDTA and the %5 H202/FeEDTA reactions were vigorous and nearly instantaneous. However, the effect was much greater for the 5%H2O2FeEDTA tests and a large volume of off-gases were not collected because the reactor could not be capped fast enough to capture them. Thus, the volume of the collected off-gases is low and the concentration of GRO in the off-gases may also be low, both of which imply that % Volatilized reported in Table 5 isartificially low and that the %Destroyed is artificially high. The %5 H2O2/FeEDTA test became very warm to the touch. None of the other tests had a noticeable change in temperature. 3.3 Effect of Treatment on Secondary Water Quality The effect of each oxidant system on secondary water quality parameters is shown in Table 6. All of the treatments increased the concentration of Cr(VI) relative to the controls and most also affected the concentrations of several metals. ORP and pH were not significantly affected in most cases. Cr(VI) was formed in all cases, in concentrations ranging from 0.027 mg/L to 0. 139 mg/L. The Cr(VI) concentrations are consistent with the concentrations of total dissolved chromium. The amount of Cr(VI) observed in these tests corresponds to the oxidation of 0. 14-0 .69 mg Cr(VI)/kg soil. It is unclear whether all of this Cr would be oxidized in a field application because of differences in field and laboratory conditions. Treatment with H202only (Tests 2 and 3) affected only Cr(VI), total Cr, vanadium, and pH. Cr(VI) increased from < 0.001 mg/L in the control test to 0. 0858 mg/L and 0. 111 mg/L in the 2% H202 Only and 5% H202 Only tests, respectively. The concentrations of total Cr were 0.079 mg/L and 0. 11 mg/L, respectively. Vanadium increased by an order of magnitude: from about 0.0061 mg/L in the control to 0.062-0.065 mg/L in the H2O2 i PRIMA Environmental, Inc. 12 Eval of Peroxide February 8, 2007 Cambria--G Street, Davis