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Water Quality Monitoring Report Forward Landfill Concentration Limit Thresholds In accordance with RWQCB Order No. 115-2014-0006, the routine inorganic monitoring data obtained from the Forward Unit during the first quarter 2017 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 first quarter 2017 monitoring period. • MW-10—barium, bicarbonate, calcium, magnesium, nitrate-N, potassium, sodium, strontium,total dissolved solids • MW-13—pH • MW-15—bicarbonate, nitrate-N • MW-17—calcium, magnesium, potassium, sodium • MW-18—bicarbonate, calcium, magnesium, nitrate-N, potassium, sodium • MW-19—calcium, nitrate-N, potassium • MW-22—calcium, potassium, sodium, strontium • MW-24—calcium, sodium In a letter dated April 17, 2017,the RWQCB was notified of these CL exceedances. Constituents exceeding a CL were place in "tracking mode" and are being evaluated quarterly for temporal trends (discussed below). Tracking Mode Constituent concentrations reported above a CL within the previous three years of monitoring were placed in "Tracking Mode" and are evaluated for temporal trends using Mann-Kendall trend analyses. The results of the trend analyses indicate that increasing trends were calculated for cis-1,2-DCE at well MW-2A; bicarbonate, calcium, potassium, sodium, strontium at well MW-10; RIPE at well MW-16; carbon tetrachloride at well MW-17; and sodium at well MW-24 (Table 2-5). Mann-Kendall trend analyses calculations are presented in Appendix G. 2.1.5 Vadose Zone Monitorine The current vadose-zone monitoring network at the Forward Unit consists of 10 lysimeters (seven suction lysimeters and three pan lysimeters). These lysimeter locations are shown on Figure 2-1. As shown on Table 2-6A, samples were collected from suction lysimeters LY-BG-1 and W-2, while the remaining suction lysimeters were reported dry or there was an insufficient volume of soil-pore liquid (5-10 ml). As shown in Table 2-613, a quantifiable concentration of tert-butyl alcohol was measured in the soil-pore liquid collected from background lysimeter LY- BG-1. Project No.6017.1030 I Water Quality Monitoring Report 7 April 2017