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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 /> In general, reported TPHg, TPHd, TPHo, benzene, MtBE, and TBA concentrations in samples <br /> from the shallow zone wells were within historical ranges during 3Q11 (Figures 3 through 8). <br /> TPHg concentrations decreased in a few wells, but generally remained stable or non-detect <br /> from the 2Q11 to 3Q11. TPHd concentrations increased in a few wells, but generally remained <br /> stable or non-detect from the 2Q11 to 3Q11. TPHo, benzene, MtBE, and TBA concentrations <br /> generally remained stable or non-detect from the 2Q11 to 3Q11. <br /> The extent of shallow TPHg and TPHd are historically delineated except to the north where the <br /> Stockton Deep Water Channel exists. During 3Q11, TPHg was delineated to the south, <br /> southwest, and west. TPHg delineation to the east was not obtained due to the fact that UOU <br /> and MOU wells were not sampled during 3Q11. During 3Q11, TPHd was detected southwest of <br /> the Site just south of the Mormon Slough in well MW-30. In addition, TPHd was delineated, <br /> except to the east where the UOU and MOU wells were not sampled during 3Q11. TPHo, <br /> benzene, MtBE, and TBA were delineated during 3Q11. TPHg, TPHd, TPHo, Benzene, MtBE, <br /> and TBA appear to be fairly stable throughout the shallow zone wells. <br /> 2.7.2 Deep Zone <br /> The following sections summarize trends for detected petroleum hydrocarbons, fuel oxygenates, <br /> and observed SPH for deeper (B-, C-, and D-Zone) groundwater beneath the Site. <br /> 2.7.2.1 SPH <br /> A summary of 3Q11 SPH thickness and SPH sheen in comparison to the 2Q11 is provided in <br /> the following table. <br /> Well Identification SPH Thickness SPH Thickness Difference <br /> (Zone) 2Q11 (Feet)* 3Q11 (Feet)* (Feet) <br /> MW-17 B Sheen Sheen NA <br /> MW-43 (B) 0.27 0.23 - 0.04 <br /> MW-46 (B) Sheen Sheen NA <br /> MW-47 (B) Sheen Sheen NA <br /> MW-48 (B) 0.02 0.02 0.0 <br /> MW-49 B 0.45 0.08 - 0.37 <br /> MW-50 (B) 32.70 27.55 - 5.15 <br /> MW-52 (B) Sheen Sheen NA <br /> Definitions: <br /> B = B-Zone wells <br /> NA = Not applicable/not available <br /> SPH = Separate phase hydrocarbon <br /> * = SPH removal occurred prior to groundwater sampling. <br /> I:\Tidewater\TW Stockton(P2A)\QMRs\2011\3Q11\3011 QSSR QRSR QMR Stockton_FINAL.doc 2.22 <br />