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<br />Forward/Austin Landfill – Third Quarter 2022 www.scsengineers.com <br />1 <br /> <br />FORWARD/AUSTIN LANDFILL <br />PERIMETER LANDFILL GAS (LFG) MONITORING PROBE <br />AND ON-SITE STRUCTURE TESTING <br />THIRD QUARTER 2022 <br /> <br />INTRODUCTION <br />This letter provides results of gas monitoring probes (GMP) and on-site structure testing for the third <br />quarter of 2022 (July through September) performed by SCS Field Services (SCS). All testing, <br />monitoring protocols and reporting were performed in general conformance with Title 27 California <br />Code of Regulations (CCR) Article 6. Briefly, these regulations require that solid waste disposal site <br />owners/operators implement LFG control or monitoring provisions to ensure that methane gas <br />concentrations in soils at the property boundary do not exceed the lower explosive limit (LEL, or 5 <br />percent by volume) and that interiors of on-site structures do not exceed 1.25 percent by volume in <br />air. Below is a summary of our quarterly monitoring activities. <br />SUMMARY AND CONCLUSIONS <br />On July 12, August 8 and 15, 2022, no methane gas (the combustible component of LFG) in excess <br />of the LEL was detected at any perimeter subsurface compliance GP probe location tested or in <br />excess of 1.25 percent by volume in air at any interior locations or on-site structures. These results <br />indicate that at the time of our testing the subject site perimeter subsurface GP probes and interiors <br />of on-site structures are in compliance with requirements of Title 27 CCR. <br />GAS TESTING INSTRUMENTATION AND METHODS <br />Testing for methane gas, oxygen gas, carbon dioxide gas and pressure was performed using a <br />Landtec GEM-5000 Gas Analyzer calibrated to methane gas. The instrument measures combustible <br />gas concentrations as a percentage by volume (0 to 100 percent) in the gas sampled. The detection <br />limit for this instrument is approximately 0.10 percent by volume. <br />Gas monitoring probe testing procedures are as follows: <br />• Connect sample tubing, open test valve; observe pressure and record data. <br />• For probes 20 feet deep or less, turn on sample pump, observe and record methane, <br />oxygen, and carbon dioxide gas concentrations, when readings have stabilized for 30 <br />seconds. <br />• For probes more than 20 feet deep, turn on sample pump, extract a minimum of one <br />probe volume, observe and record methane, oxygen, and carbon dioxide gas <br />concentrations, when readings have stabilized for 30 seconds. <br />• Close test valve, disconnect sample instruments and secure sample location.