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San Joaquin County <br /> ° Environmental Health Department DIRECTOR <br /> Donna Heran, REHS <br /> +� y{ 600 East Main Street <br /> Stockton , California 95202-3029 PROGRAM COORDINATORS <br /> Robert McCleilon, REHS <br /> - Jeff Carruesco, REHS, RDI <br /> Website: www s ov. or 1ehd Kasey Foley. REHS <br /> q �iFo,�CI� 9 <br /> Phone: (209)) 468"3420 <br /> Fax: (209) 464-0138 <br /> April 21 , 2010 <br /> Mr. Denis L. Brown Mr. David Hoover <br /> Shell Oil Products US California Fuel Supply Inc <br />;j HSEQ / Science & Engineering 587 Ygnacio Valley Road <br /> 20945 S. Wilmington Ave . Walnut Creek, CA 94596 <br /> Carson , CA 90810 <br /> Subject: Former Shell Station LOP Case #: 390870 <br /> 2575 Country Club Blvd . APN : 123-020- 12 <br /> Stockton , CA 95204 Global ID#: T0607732095 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Bench <br /> Scale Test Report by Conestoga-Rovers & Associates (CRA) dated March 8, 2010. The <br /> EHD had directed Shell to show that injection of an oxidant into the subsurface could <br /> reduce the concentrations of petroleum hydrocarbons in the subsurface and not form <br /> unacceptable byproducts. Prior to injecting chemical oxidants into the subsurface, a <br /> bench scale test is needed and the results are to be approved by the EHD before Shell <br /> can submit it to the Central Valley Regional Water Quality Control Board (CVRWQCB) for <br /> evaluation for a general permit. The report also included a work plan to install remediation <br /> pilot test wells for onsite, insitu oxidant injection . <br /> Multiple oxidants (Fenton's Reagent, sodium persulfate , and catalyzed sodium persulfate) <br /> were tested by the Shell laboratory in Niagara Falls , New York. Conclusions in the report <br /> discussed the amount of each oxidant added (loading rates) and mentioned the metal <br /> byproducts produced , but did not include analytical data for any of them. The discussion <br /> in the report for the amount of time needed for the byproduct concentrations to attenuate <br /> and return to pre-test conditions was limited to a statement that "these metals are not <br /> expected to move out of the treatment area and will re-precipitate in the treatment area <br /> within a few months of treatment. " <br /> The EHD has discussed this report with Mr. James Barton of the CVRWQCB and both <br /> agencies agree that the report did not adequately provide the data or rationales for some <br /> of the conclusions in the report. Neither the laboratory data for baseline (pre-treatment) <br /> metal concentrations in the groundwater sample nor the laboratory data for metal <br /> concentrations after sample exposure to the oxidants were included . Attenuation rates for <br /> the metal byproducts or sodium concentrations to return to pre-test conditions were not <br /> provided . <br /> k <br /> I <br /> a <br /> i <br />