|
Revised Quarterly Monitoring Report –
<br />Fourth Quarter/Annual 2024
<br />www.arcadis.com
<br />Revised - Forward Landfill 4Q24 Quarterly Mon Report 06262025 20
<br />submitted on August 1, 2024. The reporting period for this report was third quarter 2023 through second quarter
<br />2024. Time-series plots of total VOC concentrations with historical data are included in the 2024 Annual
<br />Corrective Action Evaluation Report (Arcadis 2024f).
<br />Overall total VOC concentrations have generally decreased or remained static following implementation of
<br />corrective action measures. Historically, monitoring wells AMW-13 and AMW-22S have exhibited the highest total
<br />VOC concentrations downgradient of the Site. During the monitoring period, one or more VOCs exceeded state
<br />maximum contaminant levels in wells AMW-1, AMW-13, AMW-18B, AMW-22, AMW-22S, AMW-23M, AMW-24R,
<br />AMW-46, AMW-50M, and AMW-51M, AMW-58S, and domestic well 8106-A (Tables 3a through 3c and 10).
<br />The corrective action system was previously addressed in four quarterly corrective action progress reports
<br />(Arcadis 2024b, 2024e, 2024j, 2025b) and four quarterly groundwater treatment system monitoring reports
<br />(Arcadis 2024a, 2024d, 2024i, 2025a) during 2024. The corrective action system at the Site consisted of
<br />operational five groundwater extraction wells (EW-1, EW2, EW-3R, EW-4, and EW-5) and an associated
<br />treatment system during 2024. The available data suggest that VOC mass recovery increased significantly after
<br />extraction well EW-5 became operational.
<br />6.5 Leachate Monitoring
<br />In accordance with the RWQCB-approved Leachate Recirculation Plan dated March 3, 2017 (Forward 2017), and
<br />MRP Section D.1 (MRP Tables 25 through 28 [RWQCB 2024a]), leachate recirculation is performed at the Site.
<br />According to the Forward Landfill Operations Manager, leachate recirculation was performed at the Site during
<br />fourth quarter 2024 for dust suppression activities.
<br />Forward Landfill personnel inspect leachate sumps and surface impoundments weekly at the Site. If leachate is
<br />present in a sump, it is pumped either into surface impoundment WMU F (North) or WMU F (West) for
<br />evaporation. A total of 2,133,400 gallons of leachate was pumped into the two surface impoundments during 2024
<br />(Section 6.3).
<br />During 2024, leachate was observed in leachate holding areas F-Leachate Pond, D-88A/B, D-89, D-93/95, WMU
<br />D-01N/S, WMU D-02, and F-North, and a total of 775,800 gallons of leachate was pumped into surface
<br />impoundment WMU-F (North) from these leachate holding areas (Section 6.3).
<br />During 2024, leachate was also observed in leachate holding areas WMU FU-03, WMU FU-04E/W, WMU FU-05,
<br />WMU FU-06, FU-17, FU-19W/E and F-West and a total of 1,357,600 gallons of leachate was pumped into surface
<br />impoundment WMU-F (West) from these leachate holding areas (Section 6.3).
<br />Quarterly flow rates are summarized in Section 4.1.3. Documentation for the first three quarters of 2024 was
<br />provided in previous quarterly monitoring reports (Arcadis 2024c, 2024g, 2024k).
<br />Quarterly monitoring for field parameters was previously conducted during first, second, and third quarters 2024
<br />(Arcadis 2024c, 2024g, 2024k). The fourth quarter 2024 field results and annual laboratory analytical results are
<br />discussed in Section 4.1.3.
<br />Freeboard observations are summarized in Section 4.1.3. Documentation for the first three quarters of 2024 was
<br />provided in previous quarterly monitoring reports (Arcadis 2024c, 2024g, 2024k).
<br />
|