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Water Quality Monitoring Report Forward Landfill Non-Statistical Data Analysis The California Non-Statistical Data Analysis Method (CNSDAM) was performed for VOCs detected less than 10 percent of the time in background samples. Under the CNSDAM, a measurably significant indication of release occurs in a given sample when: two or more VOCs exceed their respective Method Detection Limits (MDLs); or one or more VOCs equals or exceeds its respective practical quantitation limit (PQL). Excluding suspected field/laboratory contaminants, non-statistical indications of a release were identified at well MW-16 as a result of a quantifiable concentration of diisopropyl ether (DIPE); at well MW-17 as a result of a quantifiable concentrations of chloroform and carbon tetrachloride and trace-level concentrations of tetrachloroethene (PCE), trichloroethene (TCE), and trichlorofluoromethane (TDFM). Similar concentrations of VOCs in wells MW-16 and MW-17 were previously reported to the RWQCB and confirmed in retest samples so retesting was not performed for these wells. It should be noted that these confirmed VOCs are well below state and/or federal maximum contaminant levels (MCLS), and were place in "tracking mode" and are being evaluated quarterly for temporal trends. As discussed in Section 2.1.2, the quantifiable concentration of acetone measured in MW-3 is a suspected laboratory contaminant. Historically, low-level concentrations of VOCs have been detected in the samples collected from the Forward Unit. On behalf of Forward Inc., GLA performed an assessment of the source and potential impacts of low-level VOCs in groundwater adjacent to the Forward Landfill. It was concluded that the sporadic detection of low- level VOCs in groundwater (and lysimeter samples) at the Forward Unit are most likely due to landfill gas from unlined unit WMU-B. Forward has continued to minimize gas related impacts to groundwater by preventing ponding of water through regular site maintenance. Furthermore, in accordance with CCR Title 27, Section 20937, Forward continues to install additional landfill gas extraction wells, as needed. Forward is also in the process of implementing interim corrective action measures by bringing several inactive LFG extraction wells online in the vicinity of well MW-17. Concentration Limit Thresholds In accordance with RWQCB Order No. 115-2014-0006, the routine inorganic monitoring data obtained from the Forward Unit during the second quarter 2016 monitoring period were compared to intrawell concentration limits (CLs) established for each well. Details on the statistical analysis for the established CLs are presented in Appendix G of the fourth quarter 2014 Water Quality Monitoring Report for the Forward Landfill (GLA, 2014). As summarized in Table 2-4, the following CLs were exceeded during the second quarter 2016 monitoring period. • MW-2A—sodium • MW-10—calcium, strontium • MW-18—barium, bicarbonate M:\2016.0007\FA 2Q16.docx 7