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Water Quality Monitoring Report <br />First Quarter 2024 <br />www.arcadis.com <br />Forward Landfill 1Q24 Water Quality Mon Report_05012024 16 <br />currently operated as part of the GWTS. Extraction well EW-5 was brought online in December 2019. A sixth <br />extraction well (EW-3) is no longer operated due to low extraction rates; it was replaced by deeper well EW-3R. <br />The extracted groundwater is currently treated by two 10,000-pound granular activated carbon (GAC) vessels, <br />which were installed in January 2020. Historically, the extracted groundwater was treated by an air stripper <br />(through May 2018), four 2,000-pound GAC vessels (through November 2018), and then by two 6,000-pound <br />GAC vessels (through January 2020). The treated effluent is discharged to a recharge basin adjacent to the <br />Austin Road Unit. <br />During first quarter 2024, the GWTS treated approximately 55,955,109 gallons of extracted groundwater, which <br />represents an average flow rate of approximately 621,723 gallons per day. Based on the extracted volumes and <br />measured VOC concentrations, the GWTS removed approximately 0.91 pound of VOCs in first quarter 2024. <br />VOC recovery rose significantly following upgrades to the GWTS, including the addition of extraction well EW-5 at <br />the end of 2019. <br />During first quarter 2024, Del-Tech inspected and monitored the GWTS semimonthly. Operational details are <br />documented in the First Quarter 2024 CAP Report (Appendix E). <br />2.11 Supplemental Hazardous Waste Monitoring <br />Supplemental monitoring of select wells and leachate sumps is required by Water Code Section 13267 Order for <br />Technical Reports Regarding Acceptance of Hazardous Waste, Forward Landfill, San Joaquin County, dated May <br />16, 2017 (RWQCB 2017). <br />The supplemental monitoring includes quarterly analyses of dissolved inorganics and metals at monitoring wells <br />AMW-1, AMW-2, AMW-4, and AMW-7. In addition, leachate sumps FU-04E/W, FU-06, and FU-17 are analyzed <br />for dissolved inorganics and metals semiannually during the second and fourth quarters of the calendar year. The <br />results of these supplemental analyses for first quarter 2024 are presented in Table 15. <br />3 Summary <br />This section summarizes the water quality monitoring results for first quarter 2024 for the Forward and Austin <br />Road Units. <br />3.1 Forward Unit <br />CNSDAM evaluation of the environmental monitoring results for the Forward Unit from first quarter 2024 indicates <br />that monitoring wells MW-2A, MW-3, MW-10, and MW-19R will be resampled during second quarter because of <br />one or more VOC detections. For the inorganic monitoring parameters, CLs were exceeded in MW-1, MW-2A, <br />MW-3, MW-10, MW-13, MW-14, MW-16, MW-17R, MW-19R, and MW-21. In a letter dated April 23, 2024, the <br />RWQCB was notified of these exceedances (Forward 2024b). <br />Surface water samples were collected from the upstream and downstream surface water monitoring stations <br />during the first quarter 2024 monitoring period. No VOCs were detected at FSW-1 and FSW-2. For the inorganic <br />monitoring parameters, no CLs were exceeded during the first quarter 2024 monitoring period.