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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 /> Laboratory Validation, report number 88688: <br /> There was no observed validation issues with A-Zone monitoring wells. <br /> 2.4 THIRD QUARTER 2014 B-ZONE GROUNDWATER RESULTS <br /> 2.4.1 B-Zone Groundwater Gradient <br /> B-Zone groundwater elevations at the Site ranged from 6.71 ft below MSL (MW-35) to <br /> 1.24 ft above MSL (MW-44; Table 3, Table 4, and Figure 10). Groundwater flow direction <br /> and gradient during 3Q14 in the B-Zone was calculated to the northeast at a gradient <br /> of 0.012 ft/ft from the central portion of the Site and to the north-northwest at a <br /> gradient of 0.015 in the northwest portion of the Site (Figure 10). The current gradient <br /> flow and direction is consistent with previous quarters; to the northeast at 0.02 ft/ft. <br /> Historic groundwater flow direction and gradient data is summarized in Table 6. Vertical <br /> gradient data is summarized in Table 7. <br /> 2.4.2 B-Zone Groundwater Analytical Data <br /> During 3Q14, groundwater samples were collected from 13 B-Zone wells. Groundwater <br /> analytical results are summarized below and included in Table 3. TPHg, TPHd, TPHo, <br /> benzene, MTBE, and TBA isoconcentration contour maps are included as Figure 11 <br /> through Figure 16, respectively. The certified laboratory analytical reports including <br /> laboratory validation sheets for the groundwater sampling event conducted for the <br /> L&M OU are included in Appendix E. <br /> 2.4.2.1 Separate Phase Hydrocarbons <br /> During 3Q14, sheen was observed in three wells (MW-17, MW-46, and MW-52). Five <br /> monitoring wells, MW-43, and MW-47 through MW-50, which historically contain <br /> measureable SPH or Sheen, were not gauged or sampled this quarter due to the <br /> operation of an active or passive skimmer present in those monitoring wells. <br /> 2.4.2.2 Petroleum Hydrocarbons and Fuel Oxygenates <br /> TPHg, TPHd, TPHo, and Fuel Oxygenates with reported concentrations at or above the <br /> laboratory MRLs are summarized on the following table. <br /> 5ta ntec 2.7 <br />