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amec'O <br /> well LPW-2 (downgradient well), and 0.94 feet bmsl in well LPW-3 (upgradient well). <br /> Groundwater elevations at each well are approximately 2.75 to 4.06 feet lower than the <br /> groundwater elevations calculated from the February 2010 monitoring event (AMEC <br /> Geomatrix, 2010a). Overall, the groundwater elevations were within the range of previously <br /> calculated elevations for the Lathrop facility (Table 1). <br /> Based on the water level measurements collected in August 2010, the average groundwater <br /> gradient in the vicinity of the former stockpile is 0.004 ft/ft with a north-northeasterly flow <br /> direction. Interpreted groundwater elevation contours are shown on Figure 2. The calculated <br /> groundwater gradient and the flow direction are consistent with the historical data for the <br /> Lathrop facility. <br /> 4.1.2 French Camp Facility <br /> During the August 2010 monitoring event, groundwater was encountered at elevations of <br /> 9.42 feet bmsl in well FCW-1 (cross-gradient well), 9.31 feet bmsl in well FCW-2 (cross- to <br /> downgradient well), and 8.81 feet bmsl in well FCW-3 (upgradient well). Groundwater <br /> elevations at each well are approximately 1.67 to 2.04 feet lower than the groundwater <br /> elevations calculated from the November 2009 monitoring event (AMEC Geomatrix, 2010c). <br /> Overall, the groundwater elevations were within the range of previously calculated elevations <br /> for the French Camp facility (Table 1). <br /> Based on the water level measurements collected in August 2010, the average groundwater <br /> gradient in the vicinity of the former stockpile is 0.002 ft/ft with a north-northwesterly flow <br /> direction. Interpreted groundwater elevation contours are shown on Figure 3. The calculated <br /> groundwater gradient and groundwater flow direction is consistent with the historical data for <br /> the French Camp facility. <br /> 4.2 GROUNDWATER SAMPLE ANALYTICAL RESULTS <br /> Groundwater sample analytical results from this and previous monitoring events are <br /> summarized in the following sections and in Tables 2 and 3. The results of the August 2010 <br /> semi-annual event are shown graphically on Figures 4 and 5. Laboratory analytical reports <br /> and chain-of-custody documentation are presented in Appendix B. The groundwater sample <br /> concentration trends for TPH-diesel, Cr, and Cr VI for the wells at Lathrop and French Camp <br /> are shown on Figures 6 through 11 and Figures 12 through 17, respectively. <br /> 4.2.1 Lathrop Facility <br /> During the August 2010 sampling event, TPH-diesel was not detected above the laboratory <br /> reporting limit of 50 pg/L in the groundwater samples from all three monitoring wells (LPW-1, <br /> LPW-2, and LPW-3). Since May 2007, TPH-diesel has not been detected above the diesel <br /> AMEC Geomatrix, Inc. <br /> P:\10626.000.0\Docs\Semi-Annua1 Groundwater Monitoring&Sampling\Semi-Annual 1-10 7 <br />