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A S S O C I A T E S I N C <br /> RESULTS <br /> Water levels have increased an average of 0 75 feet since the last monitoring event on July 6, 2001 <br /> (Table 1) A groundwater gradient map was created using the data collected on January 14, 2002 <br /> (Figure 2) Groundwater pnmanly flows east, away from the slough, with a gradient of approximately <br /> 0 078 feet/foot or 411 feet per mile <br /> TPHg and TPHd were not detected in any of the groundwater samples collected from wells MW 1 <br /> through MW6, although the detection ]louts for TPHg in the sample from well MW5 were elevated <br /> due to dilution factors BTEX and MTBE were not detected in the groundwater samples collected <br /> from wells MW1, MW3, MW4 and MW6 The samples from wells MW5 and MW7 contained <br /> benzene at concentrations of 18 and 230 parts per billion (ppb), respectively The samples from wells <br /> MW2, MW5 and MW7 contained MTBE at concentrations of 32 ppb, 3,900 ppb and 130,000 ppb, <br /> respectively The sample from well MW7 also contained toluene, ethyl benzene, and xylenes at <br /> concentrations well below their respective maximum contanunant levels(MCLS) Analytical results are <br /> summanzed in Table 2 Laboratory reports with chain-of-custody documents are included in <br /> Attachment 2 <br /> RECOMMENDATIONS <br /> Due to the detectable concentrations of MTBE in the groundwater samples from wells MW2, MW5 <br /> and MW7, ATC recommends continued monitoring and sampling of all site wells (MW 1 through <br /> MW7) for TPHg, TPHd, BTEX, and MTBE by EPA Methods 8015/8020 <br /> w 1625141quart1y\1gr-2002 doc 2 <br />