ARCHIVED REPORTS_2017_3 - Laserfiche WebLink

Home Browse Search

L Water Quality Monitoring Report Forward Landfill Non -Statistical Data Analysis During the fourth quarter 2016 monitoring period, the CNSDAM was performed for VOCs detected in the DMP wells. As shown in Table 3-1, excluding suspected lab contaminants, non - statistical indications of a release were identified at well AMW-6 as a result of a quantifiable concentration of tetrachloroethene (PCE) and a trace -level concentration of dichlorodifluoromethane (DCDFM). For well AMW-12, trace concentrations of methyl ethyl ketone (MEK) and PCE were also detected. At well AMW-12, PCE was previously reported to the RWQCB and confirmed in retest samples. It should be noted that the PCE concentrations measured at well AMW-12 remain well below state and/or federal maximum contaminant levels (MCLs), and is being evaluated quarterly for temporal trends (Section 2.1.4). Forward had previously requested that well AMW-6 be reclassified as a CAP well, since similar concentrations have been historically measured in this well. Concentration Limit Thresholds In accordance with RWQCB Order No. 115-2014-0006, the routine inorganic monitoring data obtained from the Austin Unit DMP wells during the fourth 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 3-3, the following CLs were exceeded during the fourth quarter 2016 monitoring period. AMW-6 — bicarbonate AMW-12 — nitrate -N Retesting will not be performed for well AMW-6 since this well is interpreted to be a CAP well, mis-identified in the most recent WDR. In a letter dated January 19, 2017, the RWQCB was notified of the CL exceedance of nitrate -N in well AMW-12 and retesting is scheduled for January 2017. 3.1.5 Corrective Action/Evaluation Program Field and laboratory results for CAP and EMP wells for the fourth quarter 2016 monitoring period are summarized in Table 3-2. Excluding suspected laboratory contaminants, 17 of 28 CAP/EMP wells reported one or more VOCs exceeding a Practical Quantitation Limit (PQL), with CAP well AMW-1 having the greatest number of VOCs (12) including 11 measured above a PQL. An annual report discussing the CAP and EMP monitoring results for the Austin Unit was prepared by Geo -Logic Associates (GLA, 2016) and is included in Appendix H. 3.1.6 Cannery Waste Land Application Monitoring Field and laboratory results for CWLAM wells for the fourth quarter 2016 monitoring period are summarized in Table 3-4 and were compared to Water Quality Protection Standards (WQPS) Project No. 2016.0007 1 Water Quality Monitoring Report 12 January 2017