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Chevron Products Company Page 1 Pormer Chevron service station #9-5775, 301 West Kettleman Lane, Lodi. California August 15. 2002 0 INTRODUCTION SECOR International Incorporated (SECOR), on behalf of Chevron Products Company (Chevron), presents operating data for the groundwater extraction (GWE) system at 301 Kettleman Lane, Lodi California (Figure 1). Chevron discharges treated groundwater at the subject site under City of Lodi Wastewater Discharge Permit #310. This report presents July 2002 data collected between June 25 and July 30, 2002. GROUNDWATER EXTRACTION SYSTEM Extraction and treatment of groundwater was initiated on July 3, 2000. The GWE system consists of extraction wells EX -1, EX -2 and EX -3 (Figure 2). These wells are equipped with submersible pumps connected through mechanical piping to a series of granular activated carbon (GAC) vessels prior to an industrial sewer discharge point. Pumping through the wells from areas affected by petroleum hydrocarbons prevents migration of these hydrocarbons off-site. A treatment system schematic is shown on Figure 3. To assess effectiveness of the GWE system, process samples were collected weekly during this reporting period. Sample locations include an influent port (INFL), prior to the first GAC vessel, between the first and second GAC vessels (MID -1), between the second and third GAC vessels (MID -2), and prior to discharge (EFFL) to the industrial sewer. During these sampling events, INFL, MID -1, MID -2, and EFFL samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethyl - benzene, and total xylenes (BTEX compounds), methyl tertiary butyl ether (MtBE), tertiary amyl methyl ether (TAME), ethanol, methanol, ethylene dibromide (EDB), and 1,2-dicholoethane (1,2 -DCA). Maximum concentrations of detected constituents are presented below. Current and historical analytical results are presented as Table 1. Sampling Port Maximum Constituent Concentration (gg/1) July 2 throw h July 30, 2002 MtBE TBA ELBE TAME Ethanol Methanol 11V17L 71 13 4.7 <2.0 <100 <400 MID -1 <2.0 <10 <2.0 <2.0 <100 <400 MID -2 <2.0 12 <2.0 <2.0 <100 <400 EFFL <2.0 <10 <2.0 <2.0 <100 <400 Explanations: < indicates the constituent was not present at or above the method 12orting limit shown Between June 25 and July 30, 2002, the GWE system discharged a total of 575,633 gallons of treated groundwater over a period of 36 days (Table 2). As of June 30, 2002, the GWE system has treated a total of 3,639,376 gallons. Calculated discharge rates during the July monitoring period ranged from 9.34 to 9.78 gallons per minute (gpm). During the July monitoring period the system extracted approximately 0.1 pounds of TPHg, 0.001 pounds of benzene, and 0.3 pounds of MtBE. To date, the system has extracted approximately 7.9 pounds of TPHg, 0.2 pounds of benzene, and 84.1 pounds of MtBE. Plots of GWE system mass removal trends and influent groundwater TPHg, benzene, and MtBE concentrations versus time are shown on Figures 4 and 5 [:1Chevron1957751Periodic Monitoring\O & M1ReportslMonth1y\Discharge Reports120021[uly 20021July 2002 DR.doe