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Report:Groundwater-quality Monitoring—October 27,2004, 7500 West Eleventh Street, Tracy, CA. Page 13 <br /> of the secondary plume of affected groundwater on the Navarra Site, general fell from <br /> '4 what were already low concentrations over the period July 27, 2004 to October 28, 2005. <br /> The concentration of gasoline fell from 800 gg/L to 190 gg/L. However, there was a <br /> modest rise in the concentration of diesel-range compounds from 91 gg/L to 160 gg/L and <br /> TBA from 5.7 gg/L to 88 gg/L. These results extend a pattern of seasonal increase and <br /> decrease in the concentrations of fuel hydrocarbons in the secondary plume, which <br /> 4i oscillates around a generally-declining trend of concentration that has been on-going <br /> l since July 2002. <br /> 2.5.4 Groundwater Quality in the Deqper Confined Aquifers <br /> fj <br /> As has consistently been the case since groundwater samples were first recovered from <br /> s those wells in April 2002, with the exception of a slight trace of MTBE that was i <br /> apparently present in the sample recovered from Monitoring Well.3A on April 11, 2002, <br /> the samples recovered on October 27, 2004 from Monitoring Wells MW-3A, MW-3B <br /> and MW-12A were again free of petroleum hydrocarbons. Thus, there is overwhelming <br /> evidence that the deeper aquifers, which are separated from the near-surface aquifer and <br /> from each other by clay aquitards, are completely free of components of fuel <br /> 3 <br /> hydrocarbons. <br /> 1 <br /> 4ti 1 <br /> � 3 <br /> } <br /> I <br /> sic <br /> F <br />