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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 5 <br />VOC concentrations. A methane and TO-15 VOC sample will only be collected if the methane concentration <br />exceeds 1% by volume or organic vapors (total VOCs) exceed 1 part per million from prescreening activities. The <br />screening results (and laboratory results, if applicable) will be reported in the subsequent quarterly monitoring <br />report. <br />2.2.2 Quarterly Results <br />Field inspection results are provided in Appendix B. All but four of the lysimeters were dry or contained insufficient <br />soil pore liquids for sampling. One suction lysimeter (LY-POND-N) at the Site contained sufficient liquid for <br />analyses of VOCs. No VOCs were detected in the sample collected from this location. <br />Tables 5a and 5b present analytical results for suction and pan lysimeter locations, respectively, with VOCs <br />detected at concentrations exceeding the applicable MDLs or PQLs at the Site during fourth quarter 2024. <br />Cumulative data for all monitoring points for the unsaturated zone for 2024 are included in Appendix D. <br />2.3 Surface Water Monitoring <br />This section describes the surface water monitoring during fourth quarter 2024 and the associated results. <br />Surface water monitoring is conducted in accordance with MRP Section B.3 (RWQCB 2024a). <br />2.3.1 Monitoring Program <br />Two creeks are present near the Site (Figure 1). The north fork of Little John’s Creek borders the north and west <br />sides of the Site. The south fork of Little John’s Creek borders the south side of the landfill area on the east and <br />west sides of the Site. Both creeks are dammed upstream by Farmington Dam and usually are dry. Surface runoff <br />from the landfill areas is channeled to sedimentation basins, which are located near the southwestern corner of <br />the Site, adjacent to the creeks, as shown in Figure 5. The water in the sedimentation basins typically is <br />evaporated. <br />Four surface water monitoring points have been established for the Site (MRP Table 11 [RWQCB 2024a]). The <br />surface water monitoring locations are described in Table 2-1 below and on Figure 5. <br />Table 2-1 Surface Water Detection Monitoring Network <br />Monitoring Point Program or Function Location <br />FSW-2 Background (Upstream) South fork of Little John’s Creek, Operational <br />FSW-1 Downstream South fork of Little John’s Creek, Operational <br />ASW-1 Background (Upstream) North fork of Little John’s Creek, Operational <br />ASW-2 Downstream North fork of Little John’s Creek, Operational <br /> <br />Samples are collected from each monitoring point if surface water is present during the monitoring event and <br />analyzed as required by MRP Tables 12 and 13 (RWQCB 2024a). Supplemental analyses are conducted every 5 <br />years with the next 5-year analyses planned for the third quarter of 2028.