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S E C O R Fourth Quarter 2002, Quarterly Progress Report January 14, 2003 Page 2 2.0 EVALUATION OF GROUNDWATER EXTRACTION AND SOIL VAPOR EXTRACTION SYSTEMS 2.1 Introduction GWE and SVE systems were initiated on July 3, 2000. A brief description and performance evaluation of the remedial systems during 4Q02 are presented below. Certified analytical reports and chain -of -custody documentation and remedial system operation and maintenance field data sheets are included in Attachments D and E, respectively. 2.2 Groundwater Extraction System The GWE system consists of groundwater extraction wells EX -1, EX -2 and EX -3 (Figure 5). 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. Chevron discharges treated groundwater at the subject site under City of Lodi wastewater discharge permit #310. To assess effectiveness of the GWE system, process samples were collected bimonthly during this reporting period. Sample locations include a 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 TPHg, BTEX, MtBE, TBA, DIPE, EtBE, TAME, ethanol, methanol, EDB and 1,2 -DCA. Maximum concentrations of detected constituents are presented below. Current and historical analytical information is presented as Table 3. Between September 24 and December 17, 2002, the GWE system discharged a total of 1,255,970 gallons of treated groundwater over a period of 85 days (Table 4). As of December 17, 2002, the GWE system has treated a total of 5,318,694 gallons. Calculated discharge rates during the 4002 monitoring period ranged from 5.64 to 10.34 gallons per minute (gpm). During 4002 the system extracted an estimated 0.3 pounds of TPHg and 0.3 pounds of MtBE. To date, the system has extracted approximately 8.3 pounds of TPHg, 0.2 pounds of benzene, and 84.6 pounds of MtBE. Plots of GWE system mass removal trends and influent groundwater TPHg, benzene, and MtBE concentrations versus time are shown on Figure 6 and 7, respectively.