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L & M OPERABLE UNIT-THIRD QUARTER 2014 SITE STATUS, REMEDIAL SUMMARY,
<br /> AND GROUNDWATER MONITORING REPORT
<br /> Groundwater Monitoring and Sampling
<br /> October 31, 2014
<br /> 2.7.1.2 Fuel Oxygenates and Petroleum Hydrocarbon Concentrations
<br /> A summary of 3Q14 shallow zone (A-Zone) dissolved phase concentration trends of
<br /> TPHg, TPHd, TPHo, benzene, MTBE, and TBA in comparison to results reported during the
<br /> 2Q14 are presented in the table below. Values in parentheses represent number of
<br /> detections that were reported during 2Q14.
<br /> Number Number Wells With Number
<br /> Wells of Wells Wells of Wells Stable or Non- of Wells With
<br /> Constituent Concentrations Concentrations Stable or
<br /> Concentrations Concentrations Detectable
<br /> Increased Increased Decreased Decreased Concentrations Non-Detectable
<br /> Concentrations
<br /> TPHg 2AMW-12,MW- 2 (3) MW-9,MW_18, 3 (l) MW-21,MW-22 2 (0)
<br /> 23 MW-20
<br /> TPHd 2AMW-12, 3 (4) MW-9,MW-20, 4(0) --- 0 (0)
<br /> MW-18,MW-23 MW-21,MW-22
<br /> TPHo 2AMW-12,MW- 3 (l) MW-9,MW-21 2 (1) MW-22,MW-23 2 (2)
<br /> 18,MW-20
<br /> 2AMW-12,
<br /> Benzene MW-9 1 (1) --- 0 (0) MW-18,MW-20, b (3)
<br /> MW-21,MW-22,
<br /> MW-23
<br /> MW-9,
<br /> 2AMW-12,
<br /> MTBE --- 0 (0) --- 0 (i) MW-18,MW-20, 7 (3)
<br /> MW-21,MW-22,
<br /> MW-23
<br /> MW-9,MW-18,
<br /> TBA --- 0(l) MW-12 1 (1) MW-20,MW-21, b (2)
<br /> MW-22,MW-23
<br /> Notes:
<br /> Wells MW-25,MW-28,MW-31,MW-34, and MW-45 were not sampled during 2Q14 per MRP No.R5-2012-0805. Wells 2MW-13,2AMW-14,
<br /> and MW-19 were not sampled during 2Q14 and 3Q14 due to the presence of SPH or Sheen in the wells.
<br /> • In general, reported TPHg, TPHd, TPHo, benzene, MTBE, and TBA concentrations
<br /> in samples from the shallow zone wells were within historical ranges during 3Q14
<br /> (Figure 3 through Figure 8). TPHg, TPHd concentrations increased in several wells
<br /> during 3Q14. TPHo, benzene, MTBE, and TBA concentrations generally remained
<br /> stable or non-detect from the previous quarter.
<br /> • The extent of shallow petroleum hydrocarbon constituents appears to be
<br /> generally delineated with the exception to the north where the Stockton Deep
<br /> Water Channel appears to be influencing groundwater quality. The JOU and
<br /> MOU wells were not sampled by the City of Stockton during 3Q14; therefore,
<br /> shallow petroleum hydrocarbon constituents could not be delineated to the
<br /> east. TPHg, TPHd, TPHo, Benzene, MTBE, and TBA appear to be fairly stable
<br /> 5ta ntec 2.15
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