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n � G ' 31 January 2003 AGE-NC Project No 96-0232 Page 11 of 17 j q H, charactenstics, and that the detected chromatogram peaks were possibly the result of biological in Benzene (utilizing EPA Method 8021B) was detected in water samples collected from monitoring14 wells MW-11D and MW-13A at concentrations of 1 7 pg/1 and 1 3 gg/l, respectively, toluene was detected in water samples collected from wells MW-9B and MW-11D at concentrations of 1 I µg/l and 1 5 µg11, respectively - MTBE (utilizing EPA Method 8260M) was detected in water samples collected from monitoring ' wells MW-2, MW-7, MW-8A, MW-9A, MW-11A, MW-11B, MW-11D, MW-13A, and MW-14 through MW-18 at concentrations as high as 220 µg/l(MW-18), isoconcentration maps displaying the estimated extent of dissolved MTBE in First Zone and Second Zone aquifer are depicted in Figures 8 and 9 In addition,MTBE was detected in water samples collected from extraction wells G EW-1, EW-2, and EW-4 through EW-10 at concentrations as high as 53 µg/1 (EW-8), an isoconcentration map displaying the estimated extent of dissolved MTBE In the area of the ground water extraction wells is depicted in Figure 10 No other constituents of concern were detected above laboratory reporting limits in the water samples collected during the fourth quarter 2002 sampling event Analytical results of ground water monitoring well samples,are summarized in Tables 5 and 6 The laboratory reports (McCampbell Analytical Inc work order nos 0212093, 0212097 and 0212123) and chain-of-custody forms are presented in Appendix H 4.0. ADDITIONAL NPDES SAMPLING REQUIREMENTS a` „ An RWQCB waste water discharge permit (NPDES permit no CAG915001) for discharge was issued to Flag City Chevron by RWQCB letter dated 06 November 2000 In accordance with the State Water Resources Control Board's (SWRCB) State Implementation Policy (SIP), Flag City J I Chevron was directed by,RWQCB letter`s, dated'i 1 September and 05 November 2001 to perform additional quarterly NPDES sampling for a variety of potential waste constituents from the pump- and-treat effluent sampling point The additional effluent ground water samples were logged on achain-of-custody form, placed in a chilled container and transported to California Department of Health Services (DHS)-certified laboratories'for analysis for • Volatile organic compounds by EPA Method 8260, • Semi-volatile organic compounds by EPA Method 8270, • Pesticides and polychlorinated bi-phenols (PCBs) by EPA Method 8080 Advanced GeoEnvironmental,Inc