Biodegradable waste that is buried in municipal solid waste landfills will decompose over many decades forming methane, carbon dioxide, and trace constituents that include hazardous air pollutants (such as mercury), volatile organic compounds, and hydrogen sulfide. Usually larger landfills collect landfill gas to either flare or use in energy projects to produce electricity, heat, or steam. Depending upon the timing of gas collection and well placement in buried waste, addition of interim and final covers, and design and operation of the landfill, fugitive emissions can vary as found through the measurement conducted for this study. Even weather events can be a factor. Droughts can make surface and slope side cracks more difficult to maintain providing a path of least resistance for gas to pass through. High precipitation events such as tornados or hurricanes can make gas collection systems more difficult to maintain due to liquid build-up in collection wells. Landfills typically accept waste for 50 years or more. Even once the landfill closes, emissions can occur for decades requiring routine maintenance of the interim or final cover in addition to managing the well field and gas collection and control technology.