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i <br /> L 2.RESULTS FOR SECOND SEMIANNUAL PERIOD 2011 <br /> 6" Groundwater Analytical Methods <br /> Groundwater samples collected from the sampled monitoring wells were submitted to <br /> LAlpha Analytical,Inc., a California-certified analytical laboratory located in Sparks,Nevada. <br /> Copies of the laboratory reports from Alpha Analytical are provided in Appendix B. <br /> Groundwater and quality assurance/quality control (QA/QC) samples were analyzed for <br /> the following: <br /> • Total petroleum hydrocarbons as gasoline (TPHg) and as diesel (TPHd) using United <br /> L States Environmental Protection Agency (EPA)Method 8015 modified <br /> 4 • BTEX using EPA Method 8260B <br /> 1• The following QA/QC samples were collected: <br /> L <br /> • Duplicate sample from well N-7 (labeled DUP-1) <br /> L • Two equipment blank samples, one for each day of sampling(labeled EB-1A and EB-1B) <br /> • One trip blank sample for the cooler of samples (labeled TB-1) <br /> LSample analyses were conducted within a standard 10-day laboratory turnaround time. <br /> The split HydraSleeve samples are distinguished from the standard purge samples by <br /> placing"HS" after the well name for the sample ID. <br /> L <br /> 2.1.2 Results <br /> I <br /> G„ Groundwater Elevation and Flow <br /> Groundwater level data collected on September 1,2011,are presented in Table 2,and <br /> elevation contours for these data are shown in Figure 3.These data are included in the <br /> tabulation of the eight most recent monitoring events in Appendix C. Hydrographs of the <br /> historical data are provided in Appendix D. <br /> t <br /> i„ Groundwater Elevations <br /> The depths to groundwater for the September 1,2011, data were as follows. <br /> • Shallow-interval groundwater monitoring wells are constructed with total depths <br /> between 14 and 23.5 feet bgs. Calculated elevations for the shallow-interval <br /> groundwater monitoring wells ranged from 1.73 feet above mean sea level (msl) at <br /> ` well M-2,located in the northwestern portion of the Site near Trapper Slough,to <br /> -9.55 feet msl in well N-19,located in the southeastern portion of the Site. <br /> • The deeper-interval groundwater monitoring well (N-24)is constructed at a total depth <br /> ti. of 42 feet bgs.The calculated groundwater elevation for N-24 was-9.96 feet msl. <br /> These data are consistent with historical data,as shown in the hydrographs in Appendix D. <br /> L <br /> L <br /> L <br /> ES102411163308SCO/LW3521.DOCX/112970003 2-3 <br /> iw <br />