COMPLIANCE INFO_2025 Q3 CORRECTIVE ACTION

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Brendan Kenny Central Valley Regional Water Quality Control Board October 15, 2025 www.arcadis.com Forward Landfill 3Q25 CAP Update 3/4 In accordance with the WDRs in the Order, the GWTS effluent limit for VOCs was not detected above the practical quantitation limit. Given the results from all effluent samples collected, the GWTS was compliant with the WDRs during the reporting period. Details regarding influent and effluent sampling, field sheets, and copies of the laboratory reports are provided under separate cover in the Third Quarter 2025 Groundwater Treatment System Monitoring Report and will be submitted by October 30, 2025. Residential Treatment Systems During the reporting period, Forward continued to provide operation, monitoring, and maintenance for 14 residential GWTSs on Austin and Newcastle Roads. The treatment systems are composed of inline sediment filters and dual GAC vessels that remove VOCs from the water prior to the water entering the residences. Regular system sampling and maintenance on the treatment systems are performed by Del-Tech. The effluent (post-treatment) sample concentration limit for VOCs at each residential GWTS was non-detect. All residential GWTSs were in compliance with this effluent limit during the reporting period. The effluent results are representative of water that flows into the tap at each address. A separate summary report for the residential GWTSs is prepared quarterly and the results for the reporting period will be submitted by November 1, 2025. Landfill Gas Collection and Control System During the reporting period, the landfill GCCS at the Site was monitored by a network of landfill gas extraction wells. The landfill gas collected from these wells is routed and split between two onsite flares (FL-100 and FL- 150) and the onsite landfill gas-to-energy plant operated by Ameresco. Flares FL-100 and FL-150 were previously reported as Flare A-2 and Flare A-3, respectively. The landfill gas extraction wells are monitored bi-weekly and landfill gas probes are monitored quarterly by SCS Engineers (SCS) of Modesto, California and reported by Geosyntec Consultants (Geosyntec) of Oakland, California. The SCS quarterly probe monitoring results and bi- weekly extraction well monitoring results are included in Tables 1 and 2, respectively, of Geosyntec’s Third Quarter 2025 Corrective Action Program Update, which is included as Attachment 2. The CAO requires annual VOC analysis by United States Environmental Protection Agency (USEPA) Method TO- 15 for any probe with methane concentrations exceeding 1 percent by volume and/or VOC concentrations exceeding 10 ppbv (parts per billion by volume). On September 16, 2025, four gas probes (GP-1AD, GP-10D, GP-10M, and GP-10S) had exceedances of methane greater than one percent by volume. In addition, the same four probes had VOC concentrations above 10 ppbv with concentrations ranging from 500 ppbv in gas probe GP- 1AD to 6,800 ppbv in gas probe GP-10M (Attachment 2, Table 1). As a result, four probes (GP-1AD, GP-10D, GP-10M, and GP-10S) will require annual sampling and analysis of VOCs using USEPA Method TO-15 in accordance with the CAO. The next annual sampling event will be performed no later than November 30, 2025. In addition, 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 landfill GCCS during the reporting period is documented by Geosyntec (Attachment 2). During the reporting period, the average flow rates to flares FL-100 and FL-150 were 1,477 and 1,410 standard cubic feet per minute (scfm), respectively. Except for standard flare malfunctions or shutdowns, the landfill GCCS operated continuously (24 hours per day) without any significant downtime. A summary of operation time for FL-100 and FL-150 is provided below:  Flare FL-100 had a total run time of 727.6 hours and a total downtime of 16.4 hours in July 2025, a total run time of 726.8 hours and a total downtime of 17.2 hours in August 2025, and a total run time of 720 hours and no down time in September 2025. Flare FL-100 recorded a maximum adjusted flow rate of 3,221 scfm.