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NC Landfill Baseline Condition 3/9/2025 <br />Summary Report <br />Landfill Name or Identifier: North County Sanitary Landfill <br />Date: <br />First-Order Decomposition Rate Equation: <br />Where, <br />QCH4 = annual methane generation in the year of the calculation (m 3 /year ) <br />i = 1-year time increment Mi = mass of waste accepted in the ith year (Mg ) <br />n = (year of the calculation) - (initial year of waste acceptance) <br />j = 0.1-year time increment <br />k = methane generation rate (year -1 ) <br />L0 = potential methane generation capacity (m 3 /Mg ) <br />About LandGEM: <br />Sunday, March 9, 2025 <br />LandGEM is based on a first-order decomposition rate equation for quantifying emissions from the decomposition of landfilled waste in <br />municipal solid waste (MSW) landfills. The software provides a relatively simple approach to estimating landfill gas emissions. Model defaults <br />are based on empirical data from U.S. landfills. Field test data can also be used in place of model defaults when available. Further guidance on <br />EPA test methods, Clean Air Act (CAA) regulations, and other guidance regarding landfill gas emissions and control technology requirements <br />can be found at http://www.epa.gov/ttnatw01/landfill/landflpg.html. <br />Description/Comments: <br />tij = age of the jth section of waste mass Mi accepted in the ith year <br />(decimal years , e.g., 3.2 years) <br />LandGEM is considered a screening tool — the better the input data, the better the estimates. Often, there are limitations with the available data <br />regarding waste quantity and composition, variation in design and operating practices over time, and changes occurring over time that impact <br />the emissions potential. Changes to landfill operation, such as operating under wet conditions through leachate recirculation or other liquid <br />additions, will result in generating more gas at a faster rate. Defaults for estimating emissions for this type of operation are being developed to <br />include in LandGEM along with defaults for convential landfills (no leachate or liquid additions) for developing emission inventories and <br />determining CAA applicability. Refer to the Web site identified above for future updates. <br />Waste design capacity was estimated based on the volume design capacity of 41.2 million cubic yards of disposal and <br />average reduse desnsity of approximately 0.5 tons per cubic yard specified in the Permit. Historical Data: 1991 to 2023. <br />Future tonnage predicted based on 250,000 tons of waste in 2024 and assume 3% increase annually thereafter. Under <br />this scenario, the North County Landfill will reach the 20.6 million tons design capacity by 2059. <br />REPORT - 1