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San Joaquin County DIRECTOR <br /> Donna Heran,REHS <br /> OPgU!N C Environmental Health Department ASSISTANT DIRECTOR <br /> Z. 600 East Main Street Laurie Cotulla,REHS <br /> N ?� Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> Carl Borgman,REHS <br /> - - Mike Huggins,REHS,RDI <br /> • 6 .: �P , Website: www.Sjgov.org/ehd Margaret Lagorio,REHS <br /> Phone: (209)468-3420 Robert McClellon,REHS <br /> Fax: (209)464-0138 Jeff Carruesco,REHS,RDI <br /> Kasey Foley,REHS <br /> August 6, 2008 <br /> Mr. Bill Borgh Hardev & Amarjit Khinda Etal <br /> ConocoPhillips 27000 S. Leeward <br /> 76 Broadway Tracy, CA 95304 <br /> Sacramento, CA 95812 <br /> Subject: Circle K/ Service Station #01205 Site Code: 507198 <br /> 16470 Cambridge Drive RO#:0138 <br /> Lathrop, CA 95330 Global ID#: T0607700822 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Results <br /> of Remedial Well Installation and Ozone Bench Scale Test (Results) dated June 27, <br /> 2008 and has also discussed the site with the Central Valley Regional Water Quality <br /> Control Board (CVRWQCB). <br /> The Results covered the installation of sparge well SP-4 on March 17, 2008 and the <br /> subsequent bench scale test (BST) of ozone injection. Prima Environmental conducted <br /> the bench scale tests and Stantec Consulting's conclusions, included in the report, <br /> stated that ozone could remove total petroleum hydrocarbons as gasoline (TPHg) <br /> benzene, ethylbenzene, m, p-xylenes (BTEX), and methyl tert-butyl ether (MtBE) and <br /> that removal was due primarily to in-situ destruction rather than volatilization. <br /> Additionally, the hexavalent chromium [Cr(VI)] and bromates and bromides that were <br /> generated during the test were attenuated to acceptable levels in acceptable times. <br /> Recommendations in the Results stated that the remaining fourteen ozone sparge wells <br /> would be installed and the four previously tested SVE wells would be connected to a <br /> newly constructed remediation unit proposed to be onsite. Additionally, Cr(VI) and <br /> bromate would be added to the monitoring and sampling plan for onsite wells MW-2, <br /> MW-5, MW-6, and offsite MW-12. <br /> The EHD had tentatively approved the Revised Corrective Action Plan, dated <br /> September 18, 2007, and required the BST to determine if waste discharge <br /> requirements (WDR) would need to be issued by the CVRWQCB. After discussing <br /> Results with Mr. James Barton, it was decided that a pilot test should be conducted at <br /> the site and a limited number of sparge wells installed to verify the results of the bench <br /> scale test. <br /> The CVRWQCB has requested that a contingency plan to control and mitigate formation <br /> of undesirable intermediate products or mobilization of metals be part of your work plan. <br /> 16470 Cambridge Drive BST impl SVE+ozone CML 8-6-08.doc <br />