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SECOR ' • Fourth Quarter 2003 Quarterly Progress Report January 14, 2004 ' Page 2 3 0 EVALUATION OF GROUNDWATER EXTRACTION GWET and SVE systems were activated on July 3, 2000 A brief description and performance evaluation of the remedial systems during 4Q03 are presented below Certified laboratory analytical reports and ' chain-of-custody documentation and remedial system operation and maintenance field data sheets are included in Appendices D and E, respectively On August 20, 2003, SVE was discontinued as approved by the Regional Water Quality Control Board (RWQCB) in their letter dated August 18, 2003 A copy of ' this letter is included in Appendix F 31 Groundwater Extraction System The GWET system includes 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 GWET system, process samples were collected monthly 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 before 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, DIPS, 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 Maximum Constituent Concentrations(µg11) Zone ' MtBE TBA EtBE TAME Ethanol Methanol INFL 9 <10 <2 <2 <100 <400 ' MID-1 <2 <10 <2 <2 <100 <400 MID-2 <2 <10 <2 <2 <100 <400 ' EFFL <2 <10 <2 <2 <100 1 <400 Explanations Indicates the constituent was not present at or above the method detection limit shown ' Between September 17 and December 11, 2003, the GWET system discharged a total of 815,541 gallons of treated groundwater (Table 4) As of December 11, 2003, the GWET system had treated a total of 8,663,405 gallons Calculated discharge rates during the 4Q03 monitoring period ranged from 5 99 to ' 6 62 gallons per minute (gpm) During 4003, the system extracted an estimated 0 3 pounds of TPHg and 01 pounds of MtBE To date, ' the system has extracted approximately 9 4 pounds of TPHg, 0 2 pound of benzene, and 85 0 pounds of . MtBE Plots of GWET system mass removal trends and influent groundwater TPHg, benzene, and MtBE concentrations versus time are shown on Figure 6 and 7, respectively ' I%Chevron1957751Penodic Morntonng\Q P R1200314th Quarter-2003 QPR doc