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Stantec
<br /> L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2010 SITE STATUS,
<br /> REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT
<br /> Groundwater Monitoring and Sampling
<br /> January 31, 2011
<br /> Number
<br /> Wells With
<br /> Wells With Wells of Wells With
<br /> Number Number Stable or Non-
<br /> Constituent Zone Increased Concentrations Stable or Non-
<br /> of Wells of Wells Detectable
<br /> Concentration Decreased Detectable
<br /> Concentrations
<br /> Concentrations
<br /> MW-16, MW-24,
<br /> MW-26, MW-27,
<br /> MW-29, MW-32,
<br /> MW-35, MW-42,
<br /> B 0(0) 0(0) 15(15)
<br /> MW-44, MW-51,
<br /> MW-56, MW-57,
<br /> MW-58, MW-59,
<br /> TBA
<br /> MW-60
<br /> MW-61, MW-62,
<br /> C MW-54, MW-64 2(l) MW-63 1 (1) MW-65, MW-66, 5(6)
<br /> MW-67
<br /> MW-68, MW-69,
<br /> MW-55, MW-70,
<br /> D 0(3) MW-71 3(0) MW-72, MW-73, 5(5)
<br /> MW-74
<br /> In general, reported TPHg, TPHd, TPHo, benzene, MtBE, and TBA concentrations in samples
<br /> from the deep zone wells were within historical ranges during 4Q10 (Figures 11 through 16 for
<br /> B-Zone, Figures 18 through 23 for C-Zone, and Figures 25 through 30 for D-Zone). TPHg
<br /> concentrations in groundwater samples collected from all deep zone wells (B, C, and D-Zone),
<br /> during 4Q10, increased or generally remained stable or non-detect, and were consistent with
<br /> historical data. TPHd concentrations in groundwater samples collected from B and D-Zone
<br /> wells, during 4Q10, generally decreased, and groundwater samples collected from C-Zone wells
<br /> generally increased, during 4Q10. TPHo and TBA concentrations in groundwater samples
<br /> collected from all deep zone wells (B, C, and D-Zone), during 4Q10, generally decreased or
<br /> were non-detect, and were consistent with historical. Benzene concentrations in groundwater
<br /> samples collected from C and D-Zone wells, during 4Q10, generally increased or remained
<br /> stable, and groundwater samples collected from B-Zone wells generally remained stable or
<br /> non-detect, and were consistent with historical data. MtBE concentrations in groundwater
<br /> samples collected from B-Zone wells, during 4Q10, generally decreased or remained
<br /> non-detect, and groundwater samples collected from C and D-Zone wells generally remained
<br /> stable or were non-detect, during 4Q10.
<br /> Dissolved TPHg, TPHd, and MtBE concentrations are located in two separate sections of the
<br /> site (north and southwest) in B-Zone groundwater collected during 4Q10. In the northern
<br /> section of the site, dissolved TPHg is delineated except to the east. Dissolved TPHd and MtBE
<br /> are delineated to the south and west. In the southern section of the site, TPHg, TPHd, and
<br /> MtBE are delineated to the northwest, north, and east. Dissolved TPHo in B-Zone groundwater
<br /> I:\Tidewater\TW Stockton(Parcel 2A-0415)\Reports\QMR\2010\4010-Annual\4Q10 and Annual OSSRQRSRQMR Stockton_FINAL.doc 2.23
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