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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 /> Gauging data for the City of Stockton in UOU and MOU wells (provided by Wallace-Kuhl) is <br /> included as Appendix F. Electronic Deliverable Format (EDF) upload confirmations for the <br /> 3Q13 L&M OU monitoring and sampling event are presented in Appendix G. <br /> 2.3 THIRD QUARTER 2013 SHALLOW GROUNDWATER RESULTS <br /> 2.3.1 Shallow Zone Groundwater Gradient <br /> Groundwater elevations for shallow zone wells at the L&M OU, MOU, and UOU, ranged from <br /> -2.27 ft below mean sea level (MSL; 2AMW-14) to 2.67 ft above MSL (MW-45; Table 3, Table <br /> 4, and Figure 2). Groundwater flow direction ranged from the southeast to the south-south <br /> west at an average gradient ranging from 0.011 to 0.009 foot per feet (ft/ft), respectively. <br /> Historic groundwater gradient data is included in Table 6; vertical gradients are summarized in <br /> Table 7. A groundwater elevation contour map of the July 15, 2013 monitoring event is <br /> included as Figure 2. <br /> 2.3.2 Shallow Zone Groundwater Analytical Data <br /> During 3Q13, groundwater samples were collected from 12 A-Zone wells. Groundwater <br /> analytical results are summarized below and presented on Table 3 and Table 4. TPHg, TPHd, <br /> TPHo, benzene, MTBE, and TBA isoconcentration contour maps are attached as Figure 3 <br /> through Figure 8, respectively. Certified laboratory analytical reports and laboratory validation <br /> forms for the L&M OU samples are included in Appendix E. <br /> 2.3.2.1 Separate Phase Hydrocarbons <br /> During 3Q13, sheen (SPH thickness of less than 0.1 inch) was observed in three shallow wells <br /> (2AMW-13, 2AMW-14, and MW-19). A figure depicting historical depth to SPH versus time in <br /> comparison to depth to groundwater levels measured in well 2AMW-14 is included as Figure 9. <br /> Well 2AMW-14 is singled out for trending purposes because it is centrally located on the Site <br /> and has contained measurable SPH or observed SPH sheen since its installation in second <br /> quarter 2002. <br /> 2.3.2.2 Petroleum Hydrocarbons and Fuel Oxygenates <br /> TPHg, TPHd, TPHo, and Fuel Oxygenates with concentrations at or above the laboratory <br /> method reporting limits (MRLs) are summarized on the following table. <br /> 5tantec 2.2 <br />