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%-U0Vjuu rIuuuvu �UIIIVu y rage i Former Chevron Service Station #9-5775, 301 West Kettleman Cane, Lodi, California January 11, 2002 1.0 INTRODUCTION SECOR International Incorporated (SECOR), on behalf of Chevron Products Company (Chevron), presents 4a' quarter 2001 groundwater monitoring results, and operating data for the groundwater extraction (GWE) and soil vapor extraction (SVE) systems at 301 West Kettleman Lane, Lodi, California (Figure 1). In addition, included within this report is an updated site conceptual model (SCM). This report was prepared in accordance with Cleanup and Abatement Order (CAO) No. 5-00-704, dated April 20, 2000 (Attachment A), and covers the period of September 26 through December 26, 2001. 2.0 GROUNDWATER MONITORING AND SAMPLING Between November 19 and 20, 2001, SECOR conducted 4'h quarter 2001 groundwater monitoring and sampling. Wells were gauged on November 19, 2001, and sampled from November 19 through November 20, 2001. Field and laboratory procedures are presented in Attachment B. Certified laboratory analytical reports and chain -of -custody documentation and monitoring and sampling field data sheets are included in Attachments C and D, respectively. A brief description is presented below. 2.2 Monitoring Well Gauge Data During the 4h quarter monitoring well gauge data indicates the approximate depth to 01 groundwater in A, B, and C -zones ranging from 59 to 63 feet below ground surface (bgs). Gauge data is presented as Table 1. Groundwater flows measured in the A -zone were calculated to flow from northwest to southeast under an approximate gradient of 0.01 to 0.004 feet/foot. Groundwater near the site appears to flow radially toward extraction wells EX -1 and EX -3 (Figure 2). Groundwater in the B -zone flows to the southeast, with an approximate hydraulic gradient of 0.01 to 0.007 feet/foot (Figure 3). • 2.1 Sample Analytical Results During the 4'' quarter sampling event groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethyl -benzene, and total xylenes, methyl tertiary butyl ether (MtBE), tertiary butyl alcohol (TBA), di -isopropyl ether (RIPE), ethyl tertiary butyl ether (EtBE), tertiary amyl methyl ether (TAME), ethanol, methanol, ethylene di -bromide (EDB), and 1,2-dicholoethane (1,2 -DCA). Sample analytical results are presented as Table 2. Maximum concentrations of detected constituents for A, B, and C - zones are presented in the table below. An A -zone isoconcentration contour map for MtBE is presented as Figure 4. L•1Chevron1957751Periodic MonitoriaglQuarterly Progress Reportsl4thQuarter 200114th Quarter -2001 Progress Report.doc