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background soil was not available to test and because hydrocarbons will be oxidized by ozone or Peroxone and therefore will not be available to reduce Cr(VI) For each soil tested, two vials containing 5 g of soil and 25 mL of 10 miilimolar phosphoric acid (10 mM H3PO4) and Cr(VI), were prepared The H3PO4 solution was prepared such that the initial concentration of Cr(VI) in one of the vials was 5,200 µg/L Cr(VI), while the concentration in the other was 13,000 gg/L Cr(VI) These vials were placed on a shaker table for 18 hours, after which the aqueous phases were analyzed for residual Cr(VI) The available Cr(VI) reducing capacity was calculated according to Avail Cr(VI} Reducing Capacity(Mg/kg soil) [CrV1)],n,t– [Cr(Vn]fina]x (0 025L/0 005 kg) Eqn 8 where [CrVn],nit=the initial concentration of Cr(VI) in µg/L [CrVI)]f,,al=the final concentration of Cr(VI) in µg/L 2.6.4 Long-term Reducing Capacity of Soil--Pre-treatment, Spiked Cr(V1) The long-term reducing capacity of soil was estimated since attenuation of Cr(VI) over several weeks or months may be acceptable in the field Seven replicates containing COMP7 soil (50 g) and 50 mL of MW-13 groundwater spiked to 570 µg/L Cr(VI) were prepared The replicates were placed on a shaker table Periodically, one replicate was sampled and analyzed for Cr(VI) 2.6.5 Long-term Reducing Capacity of Soil—Past-treatment, Ambient Cr(VI) The long-term reducing capacity of soil was estimated to simulate the effect of Cr(VI)- impacted groundwater leaving the treatment zone and coming into contact with untreated soil COMP7 soil (100g) and IL of V-4 groundwater were sparged with 1% ozone at a rate of 500 mL/mmute for about 6 hours After sparging, four replicates each consisting of 150 mL of the ozone-sparged water and 30 g untreated COMP3 soil were prepared These replicates were mixed intermittently by hand Periodically, one replicate was sampled and analyzed for Cr(VI) NOTE An effort was made to set up this test using Peroxone-treated water, in addition to ozone, but the initial concentration of Cr(VI) in the Peroxone-treated water was < 10 µg/L Cr(VI) The Peroxone-treated water was prepared in the same manner as the ozone- treated water except that aqueous phase also contained I% H2O2 PRIMA Environmental 9 Eval of Peroxone June 1,2005 ETIC-Exxon#3942