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.` California Regional Water Quality COPol Board <br /> 9 PH2: 2 ! <br /> Central Valley Region ,- <br /> Robert Schneider,Chair <br /> S A N C t'Ui UN Aithold Schwarzenegger <br /> Alan C.Lloyd,Ph.D. <br /> LTH DEP 4TAI Governor <br /> secretaryfor 11020 Sun Center Drive#200 Rancho Cordova,CA 95670- R TfiEN T <br /> Environmental (916)464-3291•Fax(916)464-4704 <br /> Protection http://www.swrcb.ca.gov/rw4cb5 <br /> 8 September 2005 <br /> Ms.Nancy Nelson <br /> Geo Corporation <br /> C/o J. M. Equipment Company <br /> 819 9' Street <br /> Modesto, CA 95351 <br /> E TESTI M. EQUI <br /> CWORK pL4N. OZONE OMPANY, 1245 WEST CHARTER WAY, STOC%TON,SAN JOAQUIN COUNTY ENT <br /> I have reviewed the Work Plan: Ozone Sparging SECOR Benchscale Test (Workplan),received <br /> 10 August 2005 from your consultant Geological Technics,Inc. (GTI) The Workplan was written in <br /> response to a San Joaquin County Environmental Health Department letter dated 27 June 2005,which <br /> required Regional Board staff review the Workplan and provide written confirmation of compliance with <br /> requirements for the proposed injection of ozone and hydrogen peroxide. <br /> The Work Plan proposes conducting a laboratory Bench Scale Test(BST)prior to implementation of a <br /> remedial technology consisting of injecting liquid hydrogen peroxide (14202) and gaseous ozone into the <br /> aquifer. Site specific samples containing soil from three borings and groundwater will be tested for: <br /> "...Effectiveness of the ozone sparging technology in remediating the petroleum hydrocarbons- <br /> impacted soil and groundwater... ", and <br /> "...Possible mobilization ofgeneral minerals in soils, impacts to total dissolved solids and the <br /> creation of degradation byproducts from the petroleum hydrocarbon and fuel oxygenate chemical <br /> oxidation... " <br /> ll not be measured by EPA method 7196A if the total <br /> Page 3 of the Workplan states "...Chromate wi <br /> chromium concentration is below 50 pg/L the maximum contaminant level (MCL... " <br /> My comments are the following: <br /> 1. There are several problems with the statement restricting testing for Chromate (Cr6+)to total <br /> chrome levels above the MCLs. <br /> a. Total Chrome levels below the MCLS have produced detectable concentrations of Cr + in <br /> other BSTs for ozone sparging in San Joaquin County. Adding H2O2 to ozone increases <br /> the oxidation potential,which may result in additional oxidation of minerals containing <br /> Cr3+to Cr 6+. Since one purpose of the BST is to determine if detectable detrimental <br /> degradation products are present,limiting the BST to total chromium levels above MCLS <br /> will not provide the necessary data to conduct a thorough evaluation for potential <br /> detrimental effects to water quality. <br /> b. The BST should include test results and a stoichiometry equation to show that, if produced, <br /> Cr 6+will be reduced back to Cr3+within a reasonable time frame after treated groundwater <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />