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Report:Groundwater-qualityMonitoring—July 27,2004: 7500 West Eleventh Street, Tracy,CA. Page 13 <br /> diesel-range hydrocarbons, it was found to be completely free of any hydrocarbon <br /> compounds (Cook 2004). Unfortunately, the aliquot of the sample from Monitoring Well <br /> MW-19 that was initially analyzed for BTEX compounds was not re-analyzed. <br /> Consequently, the analytical results for those compounds that were apparently present in <br /> the July 2004 sample are suspect. <br /> 2.5.3 Analytes of Concern in Secondary Groundwater Plume <br /> As has been observed in the past, the rise in the groundwater table in Monitoring Well <br /> MW-12 was associated with increases in the concentrations of analytes of concern in the <br /> sample recovered from that well on July 27, 2004, compared to the non-detectable <br /> concentrations of all analytes in the sample recovered from that well on April 21, 2004. <br /> The results from the sample recovered on July 27, 2004 show that the groundwater in that <br /> monitoring well at that time contained 91 gg/L of TPHd and 800 µg/L of TPHg, with <br /> associated traces of the BTEX compounds. These results extend a pattern of seasonal <br /> increase and decrease in the concentrations of fuel hydrocarbons in the secondary plume, <br /> _= which oscillates around a generally-declining trend of concentrations that has been on- <br /> going y <br /> oin since Jul 2002. <br /> 2.5.4 Groundwater Quality in the Deeper Confined Aduifers <br /> As has consistently been the case since groundwater samples were recovered from those <br /> wells in April 2002, with the exception of a slight trace of MTBE that was apparently <br /> '= present in the sample recovered from Monitoring Well 3A on April 11, 2002, the samples <br /> recovered on July 26, 2004 from Monitoring Wells MW-3A, MW-3B and MW-12A were <br /> again free of any analytes of concern. Thus, there is overwhelming evidence that the <br /> deeper aquifers, which are separated from the near-surface aquifer and from each other <br /> by clay aquitards, are completely free of components of fuel hydrocarbons. <br /> j-- <br /> t�i <br /> r <br /> R: <br /> sic <br />