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L & M OPERABLE UNIT-THIRD QUARTER 2013 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Groundwater Monitoring and Sampling November 1, 2013 TBA (mg/L) <0.005 <0.005 0% The calculated TPD between sample MW-72 and QCDUP-6 were within the acceptable limit (20%) with the exception of TPHo. The RPD for TPHo was calculated at +/- 24.4%, approximately 4.4% outside the acceptable limit; however, the reported analytical value for TPHo in MW-72 is relatively consistent with historical values. The data can be considered representative. 2.6.2.2 General Laboratory Notes The laboratory validation notes are consistent with the quality assurance and quality control. Each set of issues corresponds directly with the denoted report. Laboratory reports are included in Appendix E. Laboratory Validation, report number 85467: There was no observed validation issues with D-Zone monitoring wells. 2.7 THIRD QUARTER 2013 SEPARATE PHASE HYDROCARBONS AND HYDROCARBON CONCENTRATION TRENDS 2.7.1 Shallow Zone The following sections summarize trends for detected petroleum hydrocarbons, fuel oxygenates, and observed SPH for shallow (A-Zone) groundwater beneath the Site. 2.7.1.1 Separate Phase Hydrocarbons Measurable SPH or SPH-sheen has historically been observed in shallow A-Zone wells MW-10, 2AMW-13, 2AMW-14, MW-19, and DPE-1 through DPE-13. Due to the quantity and viscous nature of the SPH, and the presence of emulsified SPH and groundwater in some of these wells, the depth to groundwater/SPH interface and corresponding SPH thickness have historically been difficult to accurately measure. This is evident by the inability to obtain SPH thickness measurements from wells 2AMW-14 and DPE-4 in December 2002, from well DPE-8 in February 2004, and from wells DPE-8 and DPE-10 in May 2005. Variations in measured depth to water/SPH and SPH thickness are apparent in several of these wells from quarter to quarter. This may also be attributed to seasonal fluctuations in groundwater levels. SPH or sheen has historically been reported in well 2AMW-14 since May 2002 (Table 3, Figure 9). Historical thickness of SPH in well 2AMW-14 has ranged from 0.02 ft reported during the first quarter 2005 to a maximum thickness of 2.99 ft reported during the fourth quarter 2003. Well 2AMW-14 was not assessed during the third through fourth quarters of 2004 due to its connection to a free product removal system. Recently, 2AMW-14 has contained sheen only. SPH or sheen has historically been reported in well MW-10 since February 2004 and has ranged in thickness from 0.01 to 3.09 ft (February 2007; Table 3). Well MW-10 was abandoned in November 2008 due to the City of Stockton's excavation activities. 5tantec 2.11