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S E C O R <br />F <br />Second Quarter 2004, Quarterly Progress Report <br />July 13, 2004 <br />Page 2 <br />3.0 EVALUATION OF GROUNDWATER EXTRACTION <br />GWET and Soil Vapor Extraction (SVE) systems were activated on July 3, 2000. Certified laboratory <br />- analytical reports and chain -of -custody documentation and remedial system operation and maintenance <br />field data sheets are included in Appendices D and E, respectively. On August 20, 2003, SVE was <br />discontinued as approved by the Regional Water Quality Control Board (RWQCB) in their letter dated <br />Y August 18, 2003. A copy of this letter is included in Appendix F. A brief description and performance <br />evaluation of the GWET remedial system during 2Q04 are presented below, <br />l <br />3.1 Groundwater Extraction System <br />The GWET system includes groundwater extraction wells EX -1, EX -2 and EX -3 (Figure 5). These wells <br />are equipped with submersible pumps connected through mechanical piping to a series of granular <br />activated carbon (GAC) vessels prior to an industrial sewer discharge point. Chevron discharges treated <br />groundwater at the subject site under City of Lodi (City) wastewater discharge permit #328. <br />To assess effectiveness of the GWET system, process samples were collected monthly during this <br />reporting period. Sample locations include a influent port (INFL) prior to the first GAC vessel, between <br />the first and second GAC vessels (MID -1), between the second and third GAC vessels (MID -2), and <br />before discharge (EFFL) to the industrial sewer. During these sampling events, INFL, MID -1, MID -2 and <br />EFFL samples were analyzed for TPHg, BTEX, MtBE, TBA, DIPS, EtBE, TAME, ethanol, methanol, EDB <br />and 1,2 -DCA. Maximum concentrations of detected constituents are presented below. Current and <br />historical analytical information is presented as Table 3. <br />Between December 12, 2003 and March 09, 2004, the GWET system discharged a total of 765,216 <br />gallons of treated groundwater (Table 4). As of March 09, 2004, the GWET system had treated a total of <br />9,428,621 gallons. Calculated discharge rates during the 2Q04 monitoring period ranged from 5.58 to <br />6.77 gallons per minute (gpm). <br />approximately 9.7 pounds of TPHg, 0.2 pound of benzene, and 85.0 pounds of MtBE. Plots of GWET <br />- system mass removal trends and influent groundwater TPHg, benzene, and MtBE concentrations versus <br />,. time are shown on Figure 6 and 7, respectively. <br />kNChevron1957751Periodic MonitoringlQ P R1200412nd Quarter -2004 QPR.doc <br />