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Report:Groundwater-quality Monitoring-December 20-21,2005, 7500 West Eleventh Street, Tracy, CA. Page 18 <br /> 5.0 CONCLUSIONS <br /> Based on the data obtained from the groundwater-quality monitoring round conducted at <br /> the 7500 West Eleventh Street site in December 2005 and its integration with.the data <br /> gathered cumulatively over the seven-year period since December 1998 when <br /> investigations were initiated at this site, SJC concludes the following. <br /> 1. The plumes of water affected by releases of fuel hydrocarbons that were <br /> released at the former fueling station at 7500 West Eleventh Street remain <br /> stable. <br /> 2. A groundwater mound centered near Monitoring Well MW-16 that was <br /> first observed in February 2005, continued to be present. During the <br /> December 2005 sampling round, it was determined that Monitoring Well <br /> MW-16 contains a heavy concentration of sewage. Due to the biohazard <br /> posed by that material, that well was not sampled. The presence of the <br /> sewage supports SJC's earlier conclusion that the groundwater mound <br /> resulted from the failure of a septic tank leach field that serves the <br /> building at 7501 West Eleventh Street. <br /> 3. Concentrations of components of fuel hydrocarbons within the plumes of <br /> affected groundwater are continuing to oscillate around a downward trend. <br /> 4. A 0.03 ft. thickness of floating product (LNAPL) was present on the <br /> groundwater in Monitoring Well MW-7 in December 2005. <br /> 5. No concentrations of any components of fuel hydrocarbons were detected <br /> in samples recovered from any of the three monitored potable water <br /> supply wells. <br /> i <br /> r' <br /> I <br /> sic <br />