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Stantec <br /> L & M OPERABLE UNIT-THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Groundwater Monitoring and Sampling <br /> October 27, 2010 <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 third quarter 2010 (Figures 3 <br /> through 8). TPHd and MtBE concentrations generally increased and TPHg and benzene <br /> concentrations remained stable from the second quarter 2010 to the third quarter 2010. TPHo <br /> and TBA concentrations generally decreased from the second quarter to the third quarter 2010. <br /> The extent of shallow TPHg and TPHd are historically delineated except to the north where the <br /> Stockton Deep Water Channel exists. In addition, UOU and MOU wells to the east were not <br /> sampled during the third quarter 2010; thus no delineation was observed in these areas. In <br /> addition, TPHd also had a detection on the southwestern portion of the site just south of the <br /> Mormon Slough at MW-30. TPHo and MtBE were delineated to the north, south, and west; <br /> however, delineation to the east was not achieved during the 3Q10 in shallow groundwater. <br /> Benzene and TBA was delineated during the 3Q10. TPHg, TPHo, Benzene, MtBE, and TBA <br /> 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 third quarter 2010 SPH thickness and SPH sheen in comparison to the second <br /> quarter 2010 is provided in the following table. <br /> Well Identification SPH Thickness SPH Thickness Difference <br /> (Zone) 2Q10 (Feet) 3Q10 (Feet) (Feet) <br /> MW-17 B Sheen* Sheen* NA <br /> MW-43 (B) 0.54* 0.31* - 0.23 <br /> MW-46 (B) Sheen* Sheen* NA <br /> MW-47 (B) 0.03* 0.01* - 0.02 <br /> MW-48 B 0.10* 0.03* - 0.07 <br /> MW-49 B 0.24* 0.72* + 0.48 <br /> MW-50 (B) 30.66* 30.03* - 0.63 <br /> MW-52 (B) 0.01* 0.01* 0.0 <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(Parcel 2A-0415)\Reports\QMR\2010\3010\3010QSSRORSROMR Stockton_FINAL.doc 2.22 <br />