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11 <br />C] <br />Water Quality Monitoring Report <br />Forward Landfill <br />Ki Ji 0.003 <br />V =—=(255 )*-2.19ji/day <br />ne dar 0.35 <br />where: V= Groundwater flow velocity. <br />K = Hydraulic conductivity of the water -bearing unit (255 ft/day). <br />i = Average hydraulic gradient: i ;zz 0.003 during the second quarter 2017. <br />ne = Effective porosity (ne = 0.35); an estimated value. <br />The estimated groundwater flow rate is calculated to be 2.19 feet/day (798 feet/year). <br />3.1.4 Detection Monitoring Program <br />Field and laboratory results for the Austin Unit DMP wells for the second quarter 2017 are <br />summarized in Table 3-1. <br />Non -Statistical Data Analysis <br />During the second quarter 2017 monitoring period, the CNSDAM was performed for VOCs <br />detected in the DMP wells. As shown in Table 3-1, non -statistical indications of a release were <br />identified at wells AMW-6 and AMW-12 as a result of quantifiable concentrations of PCE. Of <br />note, the PCE concentration measured at well AMW-12 (6.6 ug/L) also exceeded the state and <br />federal maximum contaminant level (MCL; 5.0 ug/L). In a letter dated July 31, 2017, the <br />RWQCB was notified of the CL exceedance in well AMW-12. Quantifiable VOCs were placed in <br />"Tracking Mode" and are being evaluated quarterly for temporal trends (see below). <br />Concentration Limit Thresholds <br />In accordance with RWQCB Order No. 115-2014-0006, the routine inorganic monitoring data <br />obtained from the Austin Unit DMP wells during the second quarter 2017 monitoring period <br />were compared to intrawell concentration limits (CLs) established for each well. Details on the <br />statistical analysis for the established CLs are presented in Appendix G of the fourth quarter <br />2014 Water Quality Monitoring Report for the Forward Landfill (GLA, 2014). As summarized in <br />Table 3-3, the following inorganic CLs were exceeded during the second quarter 2017 <br />monitoring period. <br />• AMW-6 — bicarbonate, calcium, magnesium, strontium <br />• AMW-7 — strontium <br />Tracking Mode <br />Constituent concentrations reported above a CL within the previous three years of monitoring <br />were placed in "Tracking Mode" and are evaluated for temporal trends using Mann -Kendall <br />trend analyses. The results of the trend analyses indicate that an increasing trend was <br />Project No. 5017.1030 I Water Quality Monitoring Report 11 <br />July 2017 <br />