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April 27, 1999 SECOR l,r1c , ,lulrr„rrrll,rc r,7l,ri,crlcrl Ms Anastasia Duarte-Wilkinson Time Oil Company 2737 West Commodore Way Seattle, WA 98199 SUBJECT: Quarterly Monitoring Report, January- March 1999 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 January 27, 1999 at the site Monitor wells MW-1 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, labeled with the sample number, sample time and date, and unmediately 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, BTEX, and MTBE using modified EPA Method 8015, and EPA Method 602 respectively Sample DUP was submitted as afield duplicate for monitor well MW-1 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 groundwater elevation contour map (Figure 2), and calculate the local groundwater flow direction and hydraulic gradient Groundwater at the site was measured at depths between 64 93 to 77 02 feet below ground surface (bgs) The groundwater potentiometric surface elevation averaged approximately 70 47 feet bgs during this monitoring event The groundwater elevation has decreased approximately 0 47 feet since the last sampling event in October 1998 The groundwater flow direction during this reporting period is toward the south with a hydraulic gradient of approximately 0 03 ft /ft A summary of data regarding groundwater levels measured through January 1)1T4ae OIRLOCKFORDgm 19! SECOR 7G"S-"I Q2A Apra 2719” 9912 Business Park Dave Suitt I00 Sfk rolownlo ( 19582- 1()10) ;G, 1 SRU(910) 10 1 IS8Q 1 1 t rr o rr v(r)r cnnr