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S E C 0 R Second Quarter 2003, Quarterly Progress Report July 14, 2003 Page 2 3.0 EVALUATION OF GROUNDWATER EXTRACTION AND SOIL VAPOR EXTRACTION SYSTEMS GWE and SVE systems were activated on July 3, 2000. A brief description and performance evaluation of the remedial systems during 2Q03 are presented below. Certified analytical reports and chain -of - custody documentation and remedial system operation and maintenance field data sheets are included in Appendices D and E, respectively. 3.1 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 (City) wastewater discharge permit #328. 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. Zone Maximum Constituent Concentrations (µg11) MtBE TBA EtBE TAME Ethanol Methanol INFL 17 <10 <2. <2. <100. <400. MID -1 <2. <10 <2. <2. <100. <400. MID -2 <2. <10 <2. <2. <100. <400. EFFL <2. I <10 <2. <2. 1 <100. <400. Explanations: < Indicates the constituent was not present at or above the method detection limit shown Between March 19 and June 18, 2003, the GWE system discharged a total of 965,693 gallons of treated groundwater over a period of 91 days (Table 4). As of June 18, 2003, the GWE system has treated a total of 7,104,669 gallons. Calculated discharge rates during the 2Q03 monitoring period ranged from 5.84 to 6.68 gallons per minute (gpm). During 2003 the system extracted an estimated 0.3 pounds of TPHg and 0.1 pounds of MtBE. To date, i the system has extracted approximately 9 pounds of TPHg, 0.2 pounds of benzene, and 84.8 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. I i IAChevron1957751Period1c Monitoring\Quartedy Progress Reporls1200312nd Quarter -2003 QPR.doc i