ARCHIVED REPORTS_SEMI-ANNUAL GROUNDWATER MONITORING REPORT AUGUST 2010

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ameO 27 feet, 26 feet, and 24 feet in borings FC-G8, FC-G9, and FC-G10, respectively (Geomatrix, 2006a). A summary of the static groundwater level measurements collected during previous groundwater monitoring events and calculated groundwater elevations for the French Camp facility is provided on Table 1. Historic groundwater monitoring data at the French Camp facility has indicated a groundwater flow direction ranging from west, northwest, to northeast at a calculated gradient between 0.001 ft/ft and 0.009 ft/ft with a decrease in the calculated gradient to 0.0002 ft/ft in November 2006 (Geomatrix, 2005b, 2006b, 2006c, 2007b; URS, 2004b). In August 2010, the calculated gradient (0.002 ft/ft) and the groundwater flow direction (north-northwesterly) were consistent with historical gradients and flow directions. 3.0 FIELD ACTIVITIES This section describes the groundwater monitoring activities performed by AMEC Geomatrix during the August 2010 semi-annual groundwater monitoring event. 3.1 GROUNDWATER MONITORING AND SAMPLING ACTIVITIES At the Facilities, depth to static groundwater level at each well was measured from the top of the well casing, prior to purging, using an electronic sounder. The measured groundwater levels were recorded on a Field Water Level Monitoring Record (Appendix A) and are tabulated in Table 1. After the measurement of groundwater levels, each groundwater monitoring well was purged using a disposable bailer. Well purging was conducted to remove approximately three casing volumes of groundwater from each well prior to the collection of a groundwater sample. During groundwater purging, water quality parameters (e.g., temperature, pH, and specific conductance) were measured to assess stabilization of the parameters prior to groundwater sample collection. Measured water quality parameters were recorded on the Field Well Sampling Record (Appendix A). Once the desired groundwater volume was purged and the water quality parameters stabilized, a groundwater sample was collected from each well after the water level in the well reached 80 percent (%) of its original static water level. Groundwater samples were collected from each monitoring well using a disposable polyethylene bailer. The groundwater samples were transferred from the bailer to laboratory- provided containers that were labeled and placed in an ice-filled cooler. The samples were analyzed by Agriculture and Priority Pollutants Laboratories, Inc. (APPL, Inc.) in Clovis, California, under chain-of-custody procedures. The groundwater samples were analyzed for the following parameters: AMEC Geomatrix, Inc. P:\10626.000.0\Docs\Semi-Annua1 Groundwater Monitoring&Sampling\Semi-Annual 1-10 5