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r, December 11, 1995 SECOR Il!!C'711C111011C11�l1Gf111JU1ClIC'CI Ms Anastasia Duarte-Wilkinson Time Oil Company 2737 West Commodore Way Seattle, WA 98199-1233 SUBJECT: Quarterly Monitoring Report, July - September 1995 Jackpot Food Mart 1434 West Yosemite Avenue Manteca, California Ms Wilkinson This report presents the results of quarterly groundwater monitoring and sampling conducted October 4, 1995 at Time Oil Company's Jackpot Food Mart at 1434 West Yosemite Avenue, Manteca, California (the Site, see Figure 1, Site Location Map) This report also summarizes the status of soil remediation at the Site for the period between July 1 and September 30, 1995. GROUNDWATER MONITORING AND SAMPLING Four groundwater monitor wells were sampled on October 4, 1995 These wells were installed as part of an environmental investigation completed in October 1992 Prior to sampling, depth to water in each groundwater monitor well was taken and subjective analyses were performed The subjective analyses consisted of checking for floating product or a hydrocarbon sheen by lowering a clean Teflon bailer down the well and collecting a sample at the groundwater-air interface. Wells not containing floating product were purged of approximately 3 to 5 volumes of water or until groundwater parameters of pH, temperature, and conductivity stabilized as measured by portable meters calibrated to a standard buffer and conductivity standard (Attachment I). Groundwater samples were then collected by lowering a clean disposable bailer into the well and collecting a representative sample of the formation water The groundwater sample was slowly transferred to laboratory-cleaned sample containers, sealed with Teflon lined caps, and transferred to cooled storage The samples were then transported under suitable chain-of-custody to a State of California certified laboratory for the requested testing Each groundwater sample was analyzed for total petroleum hydrocarbons as gasoline (TPHg) and benzene, toluene, ethylbenzene, and xylenes (BTEX), using modified EPA Method 8015 and EPA Method 602, respectively Groundwater Elevation Data Groundwater at the Site was measured at depths between 16 00 to 16 42 feet below ground surface A summary of data regarding groundwater levels through October 4, 1995 is presented in Table 1 Since the last quarterly sampling event, the groundwater potentiometric surface elevation has decreased approximately 3 17 feet The groundwater gradient is directed toward the northeast at a magnitude of approximately 0 002 ft./ft (Figure 2) Historically, the groundwater flow direction SECOR Intenw(tonaI,Inc Time Oil Company gMMan l I December 1995 j�it 11hVI I �rlc)(11) ,1,