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Brendan Kenny <br />Central Valley Regional Water Quality Control Board <br />April 15, 2025 <br />www.arcadis.com <br />Forward Landfill 1Q25 CAP Update_04152025 <br />3/4 <br />summary report for the residential GWTS is prepared quarterly and the results for the First Quarter of 2025 will be <br />submitted by April 30, 2025. <br />Landfill Gas Collection and Control System <br />During the First Quarter of 2025, the landfill GCCS at the Site was monitored by a network of landfill gas <br />extraction wells. The landfill gas collected from these wells is routed and split between two onsite flares (FL-100 <br />and FL-150) and the onsite landfill gas to energy plant operated by Ameresco. Flares FL-100 and FL-150 were <br />previously reported as Flare A-2 and Flare A-3, respectively. The landfill gas extraction wells are monitored bi- <br />weekly by SCS Field Services (SCS) of Modesto, California and reported by Geosyntec Consultants (Geosyntec) <br />of Oakland, California. The SCS bi-weekly monitoring results for Point of Compliance wells and individual wells <br />are included in Tables 1 and 2 of the First Quarter 2025 Corrective Action Program Update, which is included as <br />Attachment B. <br />VOCs were detected at concentrations ranging from 3,600 parts per billion by volume (ppbv) in GP-10S to 5,000 <br />ppbv in GP-10M (Table 1; Attachment B). The CAO requires annual TO-15 sampling for any probe with methane <br />concentrations exceeding 1 percent by volume and VOC concentrations exceeding 10 ppbv. On March 19, 2025, <br />five gas probes (GP-10D, GP-10M, GP-10S, GP-11D, and GP-11S) had exceedances of methane greater than <br />one percent by volume. In addition, three gas probes (GP-10D, GP-10M, and GP-10S) had VOC concentrations <br />above 10 parts ppbv. As a result, three probes (GP-10S, GP-10M, and GP10S) will require annual TO-15 <br />sampling. The next annual sampling event will be performed no later than November 30, 2025. <br />In addition, the landfill GCCS undergoes periodic maintenance and tuning to produce the highest percentage of <br />landfill gas and to minimize the collection of oxygen. The general operation of the landfill GCCS during the First <br />Quarter of 2025 is documented by Geosyntec (Attachment B). During the First Quarter of 2025, the average flow <br />rates to flares FL-100 and FL-150 were 1,262 standard cubic feet per minute (scfm) and 1,424 scfm, respectively. <br />Except for standard flare malfunctions or shutdowns, the landfill GCCS operated continuously (24 hours per day) <br />without any significant downtime. A summary of operation time for FL-100 and FL-150 is provided below: <br /> Flare FL-100 had a total run time of 716.67 hours and a total downtime of 27.33 hours in January 2025, a <br />total run time of 672 hours and no downtime in February 2025, and a total run time of 743.9 hours and a <br />total down time of 0.1 hours in March 2025. Flare FL-100 recorded a maximum adjusted flow of 1,600 <br />scfm. <br /> Flare FL-150 had a total runtime of 716.25 hours and a total downtime of 27.75 hours in January 2025, a <br />total runtime of 671 hours and downtime of 1 hour in February 2025, and a total run of 743.9 hours and <br />total downtime of 0.1 hours in March 2025. Flare Fl-150 recorded a maximum adjusted flow rate of 1,700 <br />scfm. <br />Closing <br />Arcadis will continue to monitor the GWTS, the residential GWTS, and the landfill GCCS. Program Updates will <br />be submitted to the Water Board by the required due dates. <br />If you have any questions or need additional information, please contact Dalia Rumani at 626 991 7597.