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EA <br /> San Joaquin County <br /> Environmental Health De DIRECTOR <br /> artment gonna Heran, REHS <br /> 1'' . <br /> z: 2 600 East Main Street <br /> c. .� PROGRAM COORDINATORS <br /> =< Stockton, California 95202-3029 Robert McClellon,REHS <br /> Jeff Carruesco,REHS,RDI <br /> . = 'P Website: www.sjgov.org/ehd Kasey Foley,REHS <br /> �! 6 ii Phone: (209)468-3420 <br /> Fax: (209)464-0138 <br /> May 4, 2010 Gr <br /> Thrifty Oil Company <br /> Mr. Chris Panaitescu <br /> 13116 Imperial Hwy. <br /> Santa Fe Springs, CA 90670 <br /> Subject: Thrifty Gas Station #171 LOP Case#: 1299 <br /> 1250 N. Wilson Way APN: 117-310-01 <br /> Stockton, CA 95205 Geotracker ID#: T0607700132 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Revised <br /> Feasibility Study/ Work Plan for MPE System Upgrade (FS-WP), which had been submitted to <br /> Geotracker. The FS was required by the EHD in correspondence dated February 18, 2010, <br /> after the EHD determined that the November 4, 2009 Feasibility Study did not include details <br /> necessary for the EHD to complete its evaluation and approve adding Oxygen Releasing <br /> Compound (ORC) socks into three wells located in the core of the groundwater plume. <br /> In the November 4, 2009 Feasibility Study, Thrifty Oil Company (TOG) had concluded that the <br /> addition of ORC socks would be a feasible and cost-effective remedial alternative for cleaning <br /> j up the dissolved petroleum hydrocarbon-impacted groundwater at the site. The EHD expressed <br /> ' concern with the ability to monitor the effectiveness of this'`remedial action with all the wells in <br /> the plume containing the ORC socks, thereby not allowing groundwater sampling to take place. <br /> The EHD requested a revision to the FS. <br /> The FS-WP included TOC statements that meeting the monitoring requirements established by <br /> the EHD would substantially increase the scope and costs'Pof using the ORC socks and make <br /> the remedial alternative cost-ineffective. The proposed use of. ORC socks has been dropped <br /> from the options TOC will propose for remediation of this site. <br /> TOC has now concluded that groundwater extraction, which was originally determined to be too <br /> expensive, is now a viable remedial option if limited to 0.3 gallons per minute (gpm), with <br /> storage and treatment onsite, and discharge to the City of Stockton sewer lines under their <br /> permit. Based on estimated costs and time needed, TOC has chosen this groundwater <br /> treatment option along with upgrading the existing soil vapor extraction system as the preferred <br /> combined remedial options for this site. TOC refers to this combined soil/groundwater treatment <br /> as multi-phase extraction, MPE. <br /> Although a previous GWE test conducted at the site indicated that this rate of extraction was <br /> effective at removing dissolved petroleum hydrocarbon mass, the conclusion was based on an <br /> average influent concentration of dissolved total petroleum hydrocarbons as gasoline (TPHg) at <br />