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Revised Quarterly Monitoring Report – <br />Fourth Quarter/Annual 2024 <br />www.arcadis.com <br />Revised - Forward Landfill 4Q24 Quarterly Mon Report 06262025 7 <br />3.3 Groundwater Extraction Treatment System <br />The groundwater extraction well system is outlined in MRP Section C.3 and Table 19 (RWQCB 2024a). <br />The groundwater treatment system (GWTS) at the Site has been operating since 1994 to mitigate VOC impacts in <br />groundwater. The GWTS currently operates in accordance with WDRs Order No. R5-2003-0080 (RWQCB 2003). <br />Groundwater monitoring of site extraction wells is also outlined in MRP Section C.3 and Table 19 (RWQCB <br />2024a) and requires the following extraction wells to be monitored: EW-1, EW-2, EW3R, EW-4, EW-5, and <br />CDCR-EW-1. It should be noted that four additional offsite extraction wells previously installed and not included in <br />the MRP (CDCR-EW-2, CDCR-EW-3, CDCR-EW-4, and CDCR-EW-5) are not connected to a remedial system <br />and, therefore, will not be monitored monthly as part of the corrective action program. However, these four <br />extraction wells, in addition to CDCR-EW-1, will be added to the routine quarterly monitoring program beginning in <br />second quarter 2025. <br />During fourth quarter 2024, Del-Tech inspected and monitored the GWTS semimonthly. Operational details are <br />documented in the Corrective Action Progress Report for fourth quarter 2024 (Arcadis 2025b). <br />3.4 Landfill Gas Corrective Action <br />The landfill gas corrective action system is outlined in the MRP, Section C.4 and Tables 20 through 24 (RWQCB <br />2024a). <br />The results of landfill gas monitoring of the landfill gas collection and control system, onsite structures, and <br />perimeter gas probes conducted at the Site during fourth quarter 2024 are presented in the quarterly Corrective <br />Action Progress Report (Arcadis 2025b). <br />In accordance with the Cleanup and Abatement Order (R5-2017-0703; RWQCB 2017a) and based on <br />exceedances measured during the year, samples were collected on October 4 and 7, 2024, for laboratory testing <br />by USEPA Method TO-15. VOC detection results are presented in the quarterly Corrective Action Progress <br />Report (Arcadis 2025b). According to SCS Field Services, there were no known failures of the landfill gas <br />collection and control system during fourth quarter 2024. <br />4 Additional Facility Monitoring <br />This section describes the additional facility monitoring of leachate, seeps, cannery waste land application, and <br />the Site. Additional facility monitoring is conducted in accordance with MRP Section D (RWQCB 2024a). <br /> <br />4.1 Leachate Monitoring and Leachate Collection and <br />Removal System Testing <br />This section describes leachate monitoring activities and testing of the leachate collection and removal system <br />(LCRS) during first quarter 2025, along with the associated monitoring results. The LCRS testing is conducted in <br />accordance with MRP Section D.1 (MRP Tables 25 through 28 [RWQCB 2024a]).