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February 28, 1997 Ms. Anastasia Duarte-Wilkinson SEC%f1_'11X Time Oil Company International incorporated 2737 West Commodore Way Seattle, WA 98199 SUBJECT: Quarterly Monitoring Report, October-December 1996 Jackpot Food Mart 14000 East Highway 88 Lockeford, California Ms. Duarte-Wilkinson: This report presents the results of quarterly groundwater monitoring and sampling conducted at the Jackpot Food Mart at 14000 East Highway, Lockeford, California(the site, see Figure 1). GROUNDWATER MONITORING AND SAMPLING Ten groundwater monitor wells were sampled on December 19, 1996 at the site. Monitor wells MW-i through MW-4 were installed as part of an environmental investigation conducted in December 1994. In July 1996,monitor wells MW-5 through MW-10 were installed as part of an additional environmental site assessment. Prior to purging each groundwater monitor well,a water sample was taken and subjective analyses 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 2 to 4 casing 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. If the well was slow to recover or purged dry, the water level in the monitor well was allowed to recover to at least 80 percent of its static level before sampling. The groundwater samples were then collected by lowering a clean disposable bailer into the well and collecting a representative sample. The groundwater samples were slowly transferred to laboratory-cleaned sample containers, sealed with teflon caps, labelled with the sample number, sample time and date,and immediately placed on ice in an insulated container. Each sample was logged onto a chain-of-custody record for subsequent delivery to Excelchem Environmental Labs located in Roseville, California. Groundwater samples were analyzed for TPHg and BTEX,using modified EPA Method 8015, and EPA Method 602 respectively. Groundwater Elevation Data Depth to groundwater was obtained from the existing groundwater monitor wells at the site using a water level indicator graduated to 0.01 foot. The depth to groundwater measurement was converted to a groundwater elevation for each well and used to construct a potentiometric surface map (Figure 2), and calculate the local groundwater flow direction and hydraulic gradient. The groundwater potentiometric surface elevation averaged approximately 73.87 feet below ground surface (bgs) during this monitoring event. The groundwater flow direction at the site is directed toward the southwest with a hydraulic gradient of approximately 0.02 feet per feet (ft./ft). A summary of data regarding groundwater'levels LCKFRDgm.996 SECOR J0710-001-01 February 28,1997 !/87 Trihule Road. Siiitc C. Sacramento, CA 95575-4404 (916)648-9160 19161648-8051 FAX