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L & M OPERABLE UNIT-THIRD QUARTER 2013 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Groundwater Monitoring and Sampling <br /> November 1, 2013 <br /> 2.7.1.2 Fuel Oxygenates and Petroleum Hydrocarbon Concentrations <br /> A summary of 3Q13 shallow zone dissolved phase concentration trends of TPHg, TPHd, TPHo, <br /> benzene, MTBE, and TBA in comparison to results reported during the 2Q13 are presented in <br /> the table below. Values in parentheses represent number of detections that were reported <br /> during 2Q13. <br /> Number Number Wells With Number <br /> Wells Wells of Wells With <br /> of Wells of Wells Stable or Non- <br /> Constituent Concentrations Concentrations Stable or <br /> Concentrations Concentrations Detectable <br /> Increased Increased Decreased Decreased Concentrations Non-Detectable <br /> Concentrations <br /> TPHg MW-9 1 (0) MW-20 1 (0) 2AMW-12, 2(0) <br /> MW-18, <br /> TPHd MW-18 1 (2) MW-9,2AMW-12, 3(2) 0(0) <br /> MW-20 <br /> TPHo 2AMW-12 1 (1) MW-9, MW-18, 3(0) - 0(3) <br /> MW-20 <br /> Benzene MW-9 1 (0) 0(1) 2AMW-12, 3(3) <br /> MW-18, MW-20 <br /> MTBE MW-9 1 (1) 0(0) 2AMW-12, 3(3) <br /> MW-18, MW-20 <br /> TBA MW-9 1 (1) 0(0) 2AMW-12, 3(3) <br /> MW-18, MW-20 <br /> Notes: <br /> Wells MW-21 through MW-23, MW-25, MW-28, MW-31, MW-34,and MW-45 were not sampled during 2Q13 per MRP No.R5-2012-0805. Wells <br /> 2MW-13,2AMW-14,and MW-19 were not sampled during 2Q-13 and 3Q13 due to the presence of SPH in the wells. <br /> • In general, reported TPHg, TPHd, TPHo, benzene, MTBE, and TBA concentrations in <br /> samples from the shallow zone wells were within historical ranges during 3Q13 <br /> (Figure 3 through Figure 8). TPHg, TPHd, TPHo, benzene, MTBE, and TBA <br /> concentrations generally remained stable or non-detect from the previous quarter. <br /> • The extent of shallow petroleum hydrocarbon constituents appear to be generally <br /> delineated with the exception to the north where the Stockton Deep Water Channel <br /> appears to be influencing groundwater quality. The UOU and MOU wells were not <br /> sampled by the City of Stockton during 3Q13; therefore, shallow petroleum hydrocarbon <br /> constituents could not be delineated to the east. TPHg, TPHd, TPHo, Benzene, MTBE, <br /> and TBA appear to be fairly stable throughout the shallow zone. <br /> 5ta ntec 2.13 <br />