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`. N%wf 27 October 2005 AGE-NC Project No. 96-0235 Page 6 of 11 Hexachrome Water soluble hexachrome was not significantly generated by ozonation of this natural soil,although our normal 0.2 ppb RL was obscured by hexachrome in the blank. The 10-15 ppb amounts found in the glassware blanks exceeded the 8-10 ppb found in the reacted soil indicating that at least a small pptn, sorption or decomposition reaction occurred in the presence of soil. This was a first time use for this glassware and the trace generation of hexachrome in glassware blanks was observed in a previous ozonation experiment that used different glassware. We will continue to run glassware blanks with fresh solution until hexachrome is absent to ensure lower RLs for future experiments. Water soluble hexachrome (DISTLC extraction) was not detected (<20 ppb) in the soil before or after ozonation nor was TTLC hexachrome (<800 ppb), although both were obscured by high reporting limits. K2Cr207, a water soluble form of hexachrome, was chosen for spiking & was spiked at a concentration of 71 mg C"/L, for the LCS, LCSD and MS. Recoveries were reasonable, 82-91% for the LCS-LCSD, but water phase recoveries were only 21-30% for the MS, dropping from 29- 30%on days 1 and 2 to 21%on day 5. Only 6.5%of the spike was recovered from the soil phase of the MS on day 5 using TTLC 3060 methodology. One interpretation of the MS QC data is that 70% of the water soluble chromate is reduced to tri-valent Cr,roughly equivalent to the available VOCs, and that— 1/3 of the remaining chromate is precipitated from the water phase(iron chromate?)and is recoverable as TTLC hexachrome. This implies that a much lower concentration of spike would not be recovered at all, and begs the question as to why trace amounts (10 ppb) are still present in the sample. An explanation is that the Nernst equation, as well as chemical equilibria, dictate that the reduction of chromate is both reaction and concentration dependent, so that: Cr04 2 +reduced entity=reduced Cr solid +oxidized entity, so that the final equilibrium chromate concentration is dependent upon the concentration of the reduced entity and its reduction potential, as well as the ratio of the reduced:oxidized entity.In other words,even trace levels of hexachrome should be able to be decomposed with a stronger reducing agent but that the reducing agent present here was not sufficient to decompose it to <0.2 ppb. POST-REACTION DECAY STUDY Dissolved ozone concentrations ranged from 0.029 - 0.066 mg/L during the reaction time interval and are tabulated in the results section.It decreased to ND(<0.005 mg/L)4 days after its generation was stopped. Dissolved hexachrome did not decay during the seven day post-reaction decay study.Its initial value of 7 is roughly equivalent to the 8.4 ppb found in the Final water, as a significant volume of water was removed for Final water testing and 200ml de-ionized water added back into in the reaction vessel. The post-reaction day 1 to day 7 data scatter (2.1 to 7.0 ppb) is far greater than our —5% precision for hexachrome by 218.6 and this indicates that as yet not understood variables(aliquoting or filtering)are important. DISTLC and TTLC hexachrome remained ND during the post-reaction Advanced GeoEnvironmentsl,Inc.