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09 May 2002 AGE-NC Project No 96-0232 Page 11 of 18 at concentrations as high as 320µg1l(MW-13A),TPH-mo was detected in a water sample collected from MW-13A at a concentration of 450 µg11 The laboratory reports noted that the TPH-d sample chromatograms had no recognizable patterns and/or a few Isolated peaks Based on further laboratory review of the TPH-d sample chromatograms, the laboratory further Indicated to AGE that with the exception of MW-12A and MW-13A, the TPH-d detections did not have typical diesel characteristics, and that the detected chromatogram peaks were possibly the result of biological interference (Appendix I) BTEX constituents were not detected In any of the samples collected during the March 2002 sampling event However, MTBE (utilizing EPA Method 8020) was detected in water samples collected from wells MW-7, MW-8A, MW-9A, MW-11A, MW-11B, MW-11D, MW-12A, MW- 13A at concentrations as high as 600 µg/l (MW-8A) MTBE (utilizing EPA Method 8260M) was detected in water samples collected from monitoring wells MW-1, MW-2, MW-6B, MW-7, MW-8A, MW-9A, MW-11A, MW-11B, MW-1113 and MW-12A at concentrations as high as 700 µg/1 (MW-8A), isoconcentration maps displaying the estimated extent of dissolved MTBE in First Zone and Second Zone aquifer are depicted in Figures 7 and 8 MTBE was detected in water samples collected from extraction wells EW-4, EW-5,EW-6, EW-8, EW-9 and EW-10 at concentrations as high as 100 µg/l (EW-4), an isoconcentration map displaying the estimated extent of dissolved MTBE in the area of the ground water extraction wells is depicted In Figure 9 No other constituents of concern were detected above laboratory reporting limits in the water samples collected during the first quarter 2002 sampling event Site investigation and the current first quarter 2002 analytical results of ground water monitoring well samples are summarized in Tables 5 and 6 The laboratory reports(Me Campbell Analytical Inc workordernos 0203513 and 0204142) and cham-of-custody forms are presented in Appendix I 5.0 ADDITIONAL NPDES SAMPLING REQUIREMENTS 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 Chevron was directed by RWQCB letters, dated 11 September and 05 November 2001 to perform additional 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 a chain-of-custody form, placed in a chilled container and transported to California Department of Health Services (DHS)-certified laboratories for analysis for Advanced GeoEnvironmental,Inc