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Stantec <br /> L & M OPERABLE UNIT- THIRD QUARTER 2011 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Groundwater Monitoring and Sampling <br /> October 28, 2011 <br /> 2.5 THIRD QUARTER 2011 C-ZONE GROUNDWATER RESULTS <br /> 2.5.1 C-Zone Groundwater Gradient Data <br /> C-Zone groundwater elevations at the Site ranged from 5.04 ft below MSL in well MW-54 to <br /> 4.81 ft below MSL in well MW-66 (Table 3 and Figure 17). Groundwater gradient during 3Q11 <br /> in the C-Zone was calculated to the north-northeast with an approximate hydraulic gradient of <br /> 0.0003 ft/ft (Figure 17). Historical groundwater flow direction and gradient data are summarized <br /> in Table 8, and vertical gradients summarized in Table 9. The C-Zone groundwater elevation <br /> contour map for the July 18, 2011 monitoring event is included as Figure 17. <br /> 2.5.2 C-Zone Groundwater Quality Data <br /> During 3Q11, groundwater samples were collected from eight C-Zone wells between July 18 <br /> and 21, 2011 (Table 1). Groundwater analytical results are presented in Tables 4 through 7, <br /> and summarized below. TPHg, TPHd, TPHo, benzene, MtBE, and TBA isoconcentration <br /> contour maps are included as Figures 18 through 23, respectively. The certified laboratory <br /> analytical reports for the groundwater sampling event conducted for the L&M OU are included in <br /> Appendix D. <br /> 2.5.2.1 Separate Phase Hydrocarbons <br /> During 3Q11, measurable SPH or SPH-sheen was not observed in any C-Zone wells. <br /> 2.5.2.2 Petroleum Hydrocarbons and Fuel Oxygenates <br /> TPHg, TPHd, TPHo, and fuel oxygenates with concentrations at or above the MRLs are <br /> summarized below. <br /> Iffidewater7W Stockton(P2A)\QMRs\2011\3Q11\3011 QSSR QRSR QMR Stockton_FINAL.doc 2.12 <br />