COMPLIANCE INFO_2024 Q1 WATER QUALITY RPT

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Brendan Kenny Central Valley Regional Water Quality Control Board April 15, 2024 www.arcadis.com Forward Landfill 1Q24 CAP Rpt_04152024 3/4 All five of the active groundwater extraction wells (EW-1, EW-2, EW-3R, EW-4, and EW-5) and the treatment system were operational throughout the majority of the reporting period, except for brief maintenance activities and for the shutdowns as described above. Flow rates were continuously monitored and adjusted to increase groundwater capture with the upgraded treatment system. Landfill Gas Collection and Control System During the First Quarter of 2024, the landfill gas collection and control system (GCCS) at the Austin Unit of the Forward Landfill included 215 active landfill gas extraction wells. The landfill gas collected from these wells is routed and split between the Ameresco Landfill Gas to Energy Facility (LFGEF) and Forward’s Flares A-1 and A-2 for thermal destruction. The landfill gas extraction wells are monitored semimonthly (twice per month) by SCS Field Services of Modesto, California (SCS). The SCS semimonthly monitoring results for Point of Compliance wells and individual wells are included in Tables 1 and 2 of the Quarterly Program Update, which is included as Attachment C. Probes GP-10D, GP-10M, and GP-10S had exceedances of methane greater than one percent by volume. In addition, probes GP- 1AD, GP-2AD, GP-4AD, GP-10D, GP-10M, GP-10S, GP-11D, GP-11M, GP-11S, GP-12D, GP-12M, and GP-12S had VOC concentrations above 10 parts per billion by volume. The next annual sampling event will be performed by the end of November 2024, or as requested by the client. As recorded in Table 1, VOCs were detected at concentrations ranging from 400 parts per billion (ppb) in GP-2AD to 38,000 ppb in GP-10S. The landfill GCCS undergoes periodic maintenance and tuning to produce the highest percentage of landfill gas and to minimize the collection of oxygen. The general operation of the GCCS during the First Quarter of 2024 is documented by SCS (Attachment C). During the First Quarter 2024, the instantaneous total flow rate was measured at the site and included both LFG flares and the Ameresco LFGTE Facility. The instantaneous total flow rate of LFG on March 9, 2024 and March 15, 2024, was 1,228 standard cubic feet per minute (scfm) at the LFGEF facility, 2,609 scfm at Flare A-1 (New Flare), and 1,328 scfm at Flare A-2 (Old Flare). SCS documented there was no significant downtime during the First Quarter of 2024. Residential Treatment Systems Forward, Inc. has been monitoring domestic drinking water wells in the vicinity of the landfill since 2017 as part of the domestic well monitoring program. Also, some owners of private wells have been receiving bottled water as a result of low VOC detections for several years. During the Fourth Quarter of 2023, Forward, Inc. continued to provide operation, monitoring and maintenance for 14 residential water treatment systems on Austin and Newcastle Roads. The treatment systems are composed of inline sediment filters and dual GAC canisters that remove VOCs from the water prior to entering the residence. Regular system sampling and maintenance on the treatment systems is performed by Del-Tech to ensure that VOCs do not enter the water supply. Systems offers were declined by two residences who have opted for a city water connection instead and a third party (two homes) has currently declined both water treatment systems and a city water connection.