SITE INFORMATION AND CORRESPONDENCE

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Flag City Chevron • - 3 - • 20 March 2012 6421 Capitol Ave., Lodi, San Joaquin County Interim groundwater remediation measures were initiated in April 2000. Groundwater from extraction well EW-1 was pumped at a rate of 2-gallons per minute into an above ground storage tank. Samples of extracted groundwater contained MtBE at a maximum concentration of 1,800 ug/L. In May 2000, soil borings P-18 through P-35 were advanced to 20' bgs to assess MtBE impacts to soil and groundwater in and around the Chevron fuel dispensers, storm drain, and UST system. Analytical soil results identified maximum concentrations of MtBE in the fuel dispenser area as 720 ug/kg at approximately 10' bgs. Additionally, soil samples collected from the south-southwest of the UST pit contained maximum concentrations of MTBE as 630 ug/kg at approximately 15' bgs. Grab groundwater samples near the dispensers contained maximum concentrations of TPHg, 11,000 ug/L; TPHd, 1,900 ug/L; BTEX, 2,900 ug/L; and MTBE, 11,000 ug/L (Boring P-30). In May 2000, six multi-leveled (four zone) monitoring wells (MW-8 through MW-13) were installed on and off-site to a total depth of 150` bgs. Maximum concentrations of CDCs in groundwater samples collected from MW-8 through MW-13 were: MtBE, 2,500 ug/L; TPHg, 180 ug/L; TPHd, 940 ug/L; and B, 33 ug/L. Additionally, tertiary amyl methyl ether (TAME) and ethyl tertiary butyl ether (ETBE) were detected in one sample at 87 ug/L and 2.5 ug/L respectively, TBA in four samples up to 24 ug/L, and ethanol in twenty-one samples at a maximum concentration of 1,200,000 ug/L. An investigation into the high concentrations of ethanol from the multi-leveled wells reported that ethanol-coated bentonite tablets were used during the construction of the multi-level wells, and had caused short term impacts to groundwater in the vicinity of the multi-level wells. By August 2000, all ethanol results were non- detect in all wells. Weekly sample results from EW-1 of interim groundwater remediation in May-June 2000 reported that MtBE concentrations ranged from 400 ug/L to 1,800 ug/L. Between July 2000 and December 2000, nine additional groundwater extraction wells (EW-2 through EW-10) were installed on-site to depths of 35'-50' bgs. One groundwater pump and treat system utilizing granulated activated carbon (GAC) was installed at the site. On 22 November 2000, the groundwater pump and treat (P&T) system was fully operational and began discharging under General NPDES Permit No. 5-00-119-01. In March 2002, the Rocky's Restaurant domestic well RDW-1 was properly abandoned under SJCEHD permit, and Rocky's Restaurant was hooked up to the SJC County Service Area (CSA 31) public water supply. In October 2002, five additional monitoring wells (MW-14 through MW-18) were installed off-site near Rocky's Restaurant. MtBE was detected in all five wells at concentrations up to 220 ug/L. Two borings (P36 & P37) were advanced on the northern end of the site and one boring (P38) was advanced off-site further north. All three borings were completed to 50' bgs. No soil samples were collected from the borings, however "grab" groundwater samples collected from all three borings contained up to TPHd, T, 1 ug/L, and X, 0.78 ug/L. MtBE was not detected in the grab groundwater samples. In March 2002, upgradient monitoring well MW-8A, which had been non-detect for MtBE for ten sampling events (seven quarters), began detecting