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Report: Groundwater-quality Monitoring—December 13,2001; 7500 West Eleventh Street, Tracy. CA. Page 7 The groundwater in monitoring well MW-5, which is to the west of the principal plume of affected groundwater, continued to be generally free of any detectable analytes of concern. However, the fuel oxygenate TBA, at a concentration of 9.1 µg/L, was detected in the sample recovered from that well on December 13, 2001. We currently suspect that this result is spurious, but results from future rounds of groundwater sampling and analysis will serve to confirm or negate this supposition. The sample recovered on December 13, 2001 from well MW-2, which is also interpreted to be beyond the western limit of the plume, contained no detectable concentrations of any analytes of concern. As has been the case for samples recovered from well MW-6 during earlier groundwater- quality monitoring rounds, the sample recovered on December 13, 2001 from that well, located on the western side of the plume of affected groundwater, contained only a trace of diesel-range hydrocarbons. The diesel was at a concentration of 66 µg/L. Similarly,the sample contained MTBE at a concentration of 590 µg/L. For the first time since groundwater-quality monitoring began, the December 13, 2001 sample from this well } contained a detectable concentration of gasoline-range hydrocarbons - at a concentration of 55 µg/L. } 2.5 Disposal of Purge Water ='rr When the results of the groundwater analyses were available, the monitoring well purge L' water held in 50-gallon drums on the 7500 West Eleventh Street property was segregated into two groups.' drums holding purge water from wells in which water samples recovered were affected by petroleum hydrocarbons and those containing clean water. The clean purge water was disposed by decanting it from the drum onto the surface of the ..� 7500 West Eleventh Street property. The drums containing water affected by fuel hydrocarbons were left stored on that property. That water will be shipped to a permitted recycling facility for disposal when sufficient quantity has accumulated for that to be } done economically following future rounds of groundwater sampling and analysis. 3.0 FUTURE ROUNDS OF GROUNDWATER SAMPLING AND ANALYSIS , The SJCPHS has requested that additional rounds of groundwater sampling and analysis } ' be conducted at the 7500 West Eleventh Street site until such time as that agency directs otherwise. The next round of groundwater sampling and analysis is scheduled for mid .: March 2002. 'i sic