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Fourth Quarter 2004 Quarterly Groundwater Monitoring Report Stockton Center Site Authority—University Park January 10,2005 Page 4 of 6 Table 3 Groundwater Analytical Results (November 10 and 11,2004) Sample 1D 3024-MW1-11110104 3024-MW2-11111104 3024-MW3-11110104 Analyte Units —r /1 IL /L Benzene <0.5 <0.5 6.2 Toluene <0.5 <0.5 <0.5 Ethyl benzene <0.5 0.9 2.5 Total xylenes <1.0 1.0 119 TPH-G <50 220 514 TPH-D <50 NA 130 TPH-MO <500 NA <500 TPH-K <250 NA 320* MTBE <0.5 <0.5 83 Ethanol <20 <20 <20 Tertiary-butanol <5.0 <5.0 33 Di-isopropyl ether <0.5 <0.5 <0.5 Ethyl tertiary-butyl ether <0.5 <0.5 <0.5 Tert-am 1 methyl ether <0.5 <0.5 1.4 1,2-dichloroethane <0.5 2.1 160 1,2-dibromoethane <0.5 <0.5 <0-5 =Sample chromatogram does not match the standard kerosene chromatogram.All peaks were integrated within the kerosene range. NA=Not analyzed for this parameter(no sample collected due to insufficient groundwater volume in well). Unit Conversions: Analytical Ng/L:parts per billion(ppb) TPH-G=total petroleum hydrocarbons quantified as gasoline. TPH-K,D,and MO=total petroleum hydrocarbons quantified as kerosene,diesel,and motor oil. —• MTBE=methyl tertiary-butyl ether SUMMARY AND PROPOSED FUTURE WORK The laboratory analytical results and the estimated groundwater gradient for the current monitoring are generally consistent with the historic monitoring data. The current groundwater gradient direction (southeast) is within the historic range of groundwater gradient directions (approximately due east to approximately due south). The site water table has dropped from approximately 38 feet below the ground surface to approximately 43 feet below the ground surface during the site monitoring history (December 2001 to November 2004).The next groundwater monitoring event is scheduled for February 2004. Condor prepared a Soil and Groundwater Remediation Work Plan, dated March 3, 2003, at the request of David Rosso, representative for the Stockton Center Site Authority (SCSA). At that time, site development was anticipated to proceed rapidly and the proposed scope of work for remediation was intended to facilitate the rapid site development by quickly and aggressively cleaning up the site with less regard to cost. The scope of work described in the Work Plan included (1) groundwater dewatering with dewatering wells, groundwater treatment, and proper disposal of treated groundwater; (2) soil over- excavation, including transport and disposal of contaminated soil; and (3) in-situ groundwater remediation utilizing ozone sparging technology. In a letter dated March 27, 2003, Mr. Nuel Henderson of the San Joaquin County Environmental Health Department (SJCEHD) approved the soil over- .excavation portion of the Soil and Groundwater Remediation Work Plan as an interim remedial measure. However, Mr. Henderson also indicated that ozone sparging would not be considered by the SJCEHD until site characterization was complete. As the plan for site development was modified and clarified during 2003, very aggressive and timely but less cost-effective site remediation (over-excavation, as proposed in the above described March 3, 2003 work plan) was no longer considered necessary by the SCSA. Condor, on behalf of the SCSA, proposed '1 �s 1- Ir 1) CONDOR