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The landfill is currently permitted to receive 825 tons per day. In 2003, the annual disposal rate <br /> was approximately 142,000 tons (an average 393 tons per day, based on 7 days a week of <br /> operation and 4 holidays per year). In 2003, the County documented a refuse diversion rate of <br /> 58%. <br /> The County anticipates that waste disposal will increase at an average rate of approximately 3% <br /> per year. <br /> 3.3 WASTE DECOMPOSITION PROCESS AND WASTE BY-PRODUCTS <br /> Municipal solids wastes placed in the NCRC&SL will undergo natural chemical and biological <br /> decomposition. The products of biological decomposition of organic wastes are solids, liquids, <br /> and gases. <br /> The waste decomposition process begins with organic waste products undergoing aerobic <br /> (presence of free oxygen) decomposition during storage and transport, and for a limited period <br /> after placement in the landfill. Aerobic decomposition continues until available oxygen is <br /> depleted. When oxygen is depleted, anaerobic (lack of oxygen) decomposition becomes <br /> dominant and proceeds until the biological material is decomposed. <br /> Typical byproducts of aerobic decomposition of MSW are carbon dioxide, water, and nitrate. <br /> Typical primary products of anaerobic decomposition are methane, carbon dioxide, water, <br /> organic acids, nitrogen, ammonia, iron sulfides, manganese, and hydrogen. These products are <br /> the primary factors controlling the quality and quantity of leachate and landfill gas produced. <br /> The percentage by volume of methane in the gas may range from 50% to 60% and carbon <br /> dioxide may range from 30%to 50% (Boyle, 1977). <br /> Methane production from MSW will continue for many years, from a few years to hundreds of <br /> years, in certain environments. The rate of gas production depends on a number of parameters: <br /> refuse composition, oxygen present, moisture content, pH, alkalinity, and temperature. Moisture <br /> filtrates through the landfill cover and into the refuse. The landfill will generally absorb <br /> moisture until its moisture retention capacity is reached and will then discharge liquid as <br /> leachate. <br /> North County RC&SL Page 10 of 48 Public Works/Solid Waste <br /> JTD County of San Joaquin—November 30,2004 <br />