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22 November 1996 <br /> AGE-NC Project No 95-0130 <br /> Page 3 of 4 <br /> concentrations ranging between 1 7 yg/1 and 38,000 ,ug/l The other volatile aromatic compounds <br /> (toluene, ethylbenzene and xylenes) were detected from wells MW-1 through MW-5 and VW-1C at <br /> concentrations ranging between non-detect and 20,000/_'g/1 <br /> MTBE was detected in ground water samples from VW-1 C, MW-3 and MW-4 at concentrations of <br /> 780 Mcg/1, 34 µg/1 and 0 57 µg/1, respectively Analytical results of ground `eater samples are <br />' sununanzed in Table 2 -Analytical Results of G7 ound Water Samples The laboratory report (CAL <br /> Laboratory No 915) and chain-of-custody are included in Appendix B <br /> 40. CONCLUSIONS & RECOMMENDATIONS <br /> 41 CONCLUSIONS <br /> • Between July and October 1996, ground water flow direction and gradient remained relatively <br /> constant <br /> • The ground water surface elevation at the site continues to remain above the slotted screened <br /> intervals in wells MW-1 through MW-4 Therefore, samples collected from these wells may <br /> not be representative of shallower ground water conditions at the site <br /> C Momtonng well MW-5 is located up-gradient from the Top Filling Station UST area, while <br /> monitoring well MW-4 is located down-gradient Based on the consistently high <br /> concentrations of petroleum hydrocarbons in MW-5 and the prevailing gi ound water flow <br /> direction, it appears Iikely that the hydrocarbon compounds detected in MW-5 are related to <br /> the operation of former USTs at the Wells Fargo Bank property <br /> • Concentrations of benzene detected in MW-1 through MW-5 and VW-1 C exceeded the State <br /> Lof California Maximum Contaminant Levels (MCLs) for drinking water of 1 0 Pg/l <br /> • Concentrations of toluene detected in VW-1C exceeded the State of California MCLs for <br /> drinking water of 150 pgll <br /> • Concentrations of ethylbenzene detected 2n MW-5 and VW-1C exceeded the State of <br /> California MCLs for drinking water of 700 ,ug/l <br /> • Concentrations of xylenes detected in VW-1C exceeded the State of California MCLs for <br /> drinking water of 1,750,ug/l <br /> • Concentrations of MTBE in VW-1C exceeded the State of California Drinking Water AL of <br /> 35 ppb <br /> • Due to elevated concentrations of petroleum hydrocarbons detected at VW-1C, it appears <br /> that VW-1C is near the center of the dissolved hydrocarbon plume <br />