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�} ell 4 Fourth Quarter 1996 Monitoring and Sampling Report 2 • The Southland Corporation,455 Grant Line Rd ,Tracy,CA February 24, 1997 December 18, 1996 monitoring and sampling event are presented in Table 1, and historical results are summarized in Table 1A(Attachment 2) Field data sheets are included in Attachment 3 Monitoring Well Sampling and Analytical Results Groundwater samples were collected from wells MW-1 through MW-6, MW-8 through MW-11, MWA5, GWE-2, and GWE-3 Before sampling, at least three well-casing volumes of groundwater was removed from each monitoring well, unless the well was purged dry Field measurements of temperature, conductivity, and pH were recorded during well purging The groundwater samples were collected using disposable bailers and placed in analysis-specific sample containers with analysis-specific preservatives The samples were then sealed and labeled with the fob identification number, the sample number, date, time, and type of laboratory analysis required The samples were stored on ice in an insulated container and transported under chain-of-custody manifest to NEI/GTEL Environmental Laboratories, Inc in Wichita, Kansas The groundwater samples were analyzed for BTEX, MTBE and TPH-G using Environmental Protection Agency (EPA) methods 8020/modified 8015 Groundwater purged during the fourth quarter monitoring and sampling event was placed in a Department of Transportation (DOT)approved 55-gallon drum to be pumped through the groundwater extraction system at a later date I Dissolved benzene and TPH-G were detected in groundwater samples from monitoring wells MWA, MW- 8, MW-9, MW-10, GWE-2, and GWE-3 with highest concentrations reported in MW-10 at 3,700 micrograms per liter(ug/L)and 26,000 ug/L, respectively(Figure 3) MTBE was reported in monitoring wells MW-8, MW-9, and GWE-3 with highest concentrations reported in MW-9 at 140 ug/L Analytical results from the groundwater samples collected on December 18, 1996 are presented in Table 1, and historical analytical results are summarized in Table 1A The laboratory analytical reports and the chain-of-custody records for the December 18, 1996 sampling event are included in Attachment 4 Remediation Progress Summary Extraction from newly installed extraction well GWE-2 in the former tank pit was initiated on December 11, 1996 Groundwater is being extracted from GWE-2 at an average rate of 6 gpm, but due to minor start-up problems, extraction has not been continuous The effectiveness of dewatering in lowering the water table for soil vapor extraction may be known by the middle of February 1997, but maximum drawdown may not be achieved until after the rainy season 02310496 RFr(STHL 5 1) FLUOR DANIEL GTI