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. Evaluation of Additional Remedial Alternatives FLAG CITY CHEVRON 6421 Capitol Avenue, Lodi, California 1.0 INTRODUCTION In accordance with the request of Mr Richard Bokides of the Bokides Family Limited Partership, Advanced GeoEnvironmental, Inc (AGE), has prepared this document to evaluate additional remedial alternatives for 6421 Capitol Avenue (the site), Lodi, California The location of the site is illustrated on Figure 1 A plan of the site is illustrated on Figure 2 In the AGE-prepared Quarterly Report-Second Quarter 2004(dated 30 July 2004),AGE requested suspension of the ground water pump-and-treat (P&T) system due to the lack of cost effectiveness for clean-up of MTBE-impacted ground water, additionally, AGE concluded that ground water pump-and-treat activities may be drawing a separate,northern MTBE-plume onto the site In a letter dated 13 August 2004,the California Regional Water Quality Control Board-Central Valley Region (CRWQCB)concurred with AGE's request and granted permission to cease all ground water pump- and-treat operations and all monitoring associated with the pump-and-treat system, however, the CRWQCB approval-letter stipulated that CRWQCB staff must be provided with an evaluation of additional remedial alternatives • Therefore,the enclosed evaluation has been prepared as required by the above CRWQCB-approval letter,and was prepared in accordance with guidelines established by the CRWQCB for investigation of underground storage tank (UST) sites Background information and a description of prior investigations at the site were included in AGE's Final Remediation Plan, dated 31 August 2000 2 0. PREVIOUS GROUND WATER REMEDIATION ACTIVITIES Between November 2000 and August 2004, on-site extraction wells EW-2 and EW-4 through EW-10 were selectively utilized for remediation of MTBE-impacted ground water at the site, each extraction well was independently adjusted to continuously extract ground water at a flow rate of approximately 4 to 5 GPM All extracted ground water was routed through a ground water treatment system consisting of coconut shell, liquid phase granular activated carbon (GAC) A grand total volume of approximately 27,086,201 gallons of MTBE-impacted water was treated and discharged to a conveyance ditch (located approximately 450 feet towards the south) under CRWQCB General Order 5-00-119 for discharge to surface waters of ground water from cleanup of petroleum fuel pollution and National Pollutant Discharge Elimination System (NPDES) waste water discharge permit no CAG915001 During operation of the pump-and-treat system, a total of 13 33 pounds of MTBE was removed from MTBE-impacted ground water, influent MTBE concentrations generally decreased at the P&T influent from concentrations as high as 1,200 micrograms per ltter(µg/1)to concentrations as low as 9 1 µgll P&T influent MTBE concentrations are summarized in Table 1,P&T performance data is summarized in Table 2 Due to the lack of cost Advanced GeoEnvironmental,Inc