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 2/4 Violations of the CAO CAO Task 9.a indicates that Quarterly Progress Reports shall include a description of any violations of the CAO during the relevant quarter. During the period of January 1 through March 31, 2024, there were no known violations of the CAO. All effluent samples were taken from GAC Unit #1, as it was the final stage in the GWTS before the point of compliance for the Order. The influent and effluent samples were submitted to Pace for VOC analysis by United States Environmental Protection Agency Method 8260B. Full laboratory analytical reports are included as Attachment B. Low concentrations of VOCs (up to 2.87 micrograms per liter [µg/L] of total VOCs) were detected in the six influent samples. Analytical results from the February 15, 2024 effluent samples of the lead and lag GAC vessels were anomalous and were assumed to be switched, which was confirmed with an extra sample collected February 23, 2024. No VOCs were detected above the practical quantitation limit (PQL) in the effluent samples collected at the point of compliance for the Order. The concentration limit for VOCs at the point of compliance is non-detect. Since all effluent samples were non- detect at the PQL, the GWTS was in compliance with the Order during the First Quarter 2024 reporting period. The Del-Tech semi-monthly field inspection forms are included in Attachment A. Laboratory analyses collected were conducted by Pace; Pace analytical reports are included in Attachment B. Remediation Systems Operations and Performance Summary CAO Task 9.a indicates that Quarterly Progress Reports shall include information on remedial system operation and performance during the relevant quarter. Operational and performance information for the GWTS and the landfill gas collection and control system are provided below. Groundwater Extraction and Treatment System A GWTS is operated at the Austin Road Unit, to address detections of volatile organic compounds (VOCs) in groundwater. Five groundwater extraction wells, designated EW-1, EW-2, EW-3R, EW-4, and EW-5 are currently operated as part of the GWTS. A sixth well, EW-3, is no longer operated due to low extraction rates; it was replaced by deeper well EW-3R. The extracted groundwater is currently treated by two 10,000-pound granular activated carbon (GAC) vessels, which were installed in January 2020. Historically, the extracted groundwater was treated by an air stripper (through May 2018) and then by four 2,000-pound GAC vessels (through November 2018) and then by two 6,000- pound GAC vessels (through January 2020). The treated effluent is discharged to a recharge basin adjacent to the Austin Road Unit. During the First Quarter of 2024, the GWTS was inspected and monitored semimonthly by Del-Tech Geotechnical Support (Del-Tech) of Oakdale, California. The Del-Tech semi-monthly field inspection forms are included in Attachment A. Between December 28, 2023 and March 27, 2024, the GWTS treated approximately 55,955,109 gallons of extracted groundwater, which represents an average flow rate of 621,723 gallons per day. Based on the extracted volumes and measured VOC concentrations, the GWTS removed approximately 0.91 pounds of VOCs during the reporting period. The Del-Tech downtime log for the reporting period is included in Attachment A. The operation of the GWTS was not affected by any downtime events during the reporting period.