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21 February 1997 <br /> AGE-NC Project No 95-0130 <br />' Page 3 of 4 <br /> (toluene, ethylbenzene and xylenes)were detected in samples from wells MW-2, MW-3, MW-5, and <br /> VW-1C at concentrations ranging between 1 9 and 33,000,ugd <br /> MTBE was detected in ground water samples from MW-3, MW-4, and VW-1C at concentrations <br /> between 0 72 and 750 ug/l Analytical results of ground water samples are summarized in Table 2 - <br /> Analytical Results of Ground Water Samples The laboratory report (Castle Analytical Laboratories <br /> Reference No 98 1) and chain-of-custody forms are presented in Appendix B <br /> 40 CONCLUSIONS & RECOMMENDATIONS <br /> 41 CONCLUSIONS <br /> IBetween October 1996 and January 1997, ground water flow direction and gradient remained <br /> relatively constant at the site <br /> • The ground water surface elevation at the site continues to remain above the slotted screened <br /> intervals in wells MW-1 through MW-5 Therefore, samples collected from these wells may <br /> not be representative of shallower ground water conditions at the site <br /> • Based on the consistently high concentrations of petroleum hydrocarbons in MW-5 and the <br /> prevailing ground water flow direction, it appears likely that the hydrocarbon compounds <br /> detected in MW-5 are related to the operation of former USTs at the Wells Fargo Bank <br /> property <br /> • Concentrations of benzene detected in MW-2, MW-3, and VW-1 C exceeded the State of <br /> 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 µg11 <br /> Concentrations of ethylbenzene detected in MW-5 and VW-1C exceeded the State of <br /> California MCLs for drinking water of 700 µg/l <br /> • Concentrations of xylenes detected in VW-1 C exceeded the State of California MCLs for <br /> drinking water of 1,750 ,ug/1 <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 />' • The fluctuation of detected dissolved petroleum hydrocarbons in MW-3 and VW-1 C ("core" <br /> area) over the past four quarters is suggestive of an unstable dissolved hydrocarbon plume <br />