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Water Quality Monitoring Report French Camp Landfill 6.0 ANNUAL SUMMARY 6.1 General During the 2014 monitoring year, groundwater elevation measurements were performed quarterly and water quality sampling and soil-pore gas monitoring were performed semiannually in accordance with WDR Order No. 115-2007-0046. All of the monitoring points were sampled for the monitoring parameters summarized in Table 1. A tabular summary of the historical monitoring data is presented in Appendix C and time-series plots depicting groundwater and surface water constituent concentrations are presented in Appendix D. Stiff diagrams of the semiannual data obtained in 2014, hydrographs illustrating the historical groundwater elevations of the detection monitoring wells, and information relative to well screen elevations and pump intake elevations are also included in Appendix D. 6.2 Groundwater Over the 2014 monitoring year, groundwater elevations varied by about one to two feet with hydraulic gradients ranging between 0.001 ft/ft to 0.004 ft/ft to the east and southeast. Groundwater quality conditions beneath the French Camp Landfill during the 2014 monitoring year are generally similar to those observed in previous years. During one or both semiannual monitoring periods in 2014, inorganic CLs were exceeded for chloride in the samples from wells MW-913 and MW-10A; for pH value at wells MW-9A and MW-10A; and for specific conductance and TDS in the sample from well MW-10A. However, none of the constituents that exceeded a CL exhibited a statistically significant increasing trend. In January 2005 a No Release Demonstration (NRD) for groundwater monitoring well MW-10A was performed (Herst, 2005) in response to CL exceedances of chloride and TDS. The NRD concluded that French Camp Landfill, located within the central Stockton area, has been impacted by saltwater intrusion and the elevated chloride and TDS concentrations measured in well MW-10A are believed to be the result of this condition and not the result of landfill-related impacts. With the exception of TCFM at well WM-9A and chloroform at well MW-6A, no VOCs were measured at quantifiable concentrations in groundwater samples during the 2014 monitoring year. Roth TCFM and chloroform have been previously confirmed in retest samples, however, neither of these VOCs exhibited an increasing trend. Given the distance of well MW-6A from the landfill, the chloroform concentrations measured in well MW-6A are not believed to be the result of a release from the landfill. The TCFM concentrations measured in well MW-9A are well below risk-based concentrations and have been attributed to LFG. 6.3 Surface Water Surface water elevations at stream gauging locations varied by about one to two feet during the 2014 monitoring year. These changes reflect tidal and seasonal precipitation patterns. Surface water generally flows west toward the San Francisco Bay. Project No.2014.0012 FC 2SA14 Report.docx 6 1/20/2015, Rev.0