In waste management, controlling and monitoring moisture is essential. Liquid waste like chemicals or other fluids, moisture created by decaying matter, and stormwater all combine to form a substance known as leachate. This is toxic fluid, and it's incredibly important to keep it out of the environment and away from animals or humans. Modern, sanitary landfills employ an extensive leachate management system in order to collect and safely dispose of leachate. Reducing the amount of leachate is an important part of this, which means mitigating moisture from the environment as much as possible. At the end of each day, newly packed waste is covered with a daily cover. This protects the waste from outside animals or inclement weather like rain or snow.
Moisture in landfills can come from organic materials decomposing, liquid waste, or precipitation. As this moisture percolates through the landfill, it picks up a variety of contaminants. These can include hazardous chemicals such as volatile organic compounds, chloride, nitrogen, solvents, phenols, and heavy metals. If these hazardous byproducts are exposed to the soil, they will quickly steep into the water table and travel to nearby ecosystems. Eventually, these contaminants can end up in drinking water, lakes, streams, and areas where humans live and work.
Gas is also released as organic matter breaks down and decomposes. Some typical but dangerous landfill gasses are ammonia, sulfide, methane and carbon dioxide. When humans are exposed to these gasses, they can suffer from respiratory issues, birth defects, and other harmful conditions.
The EPA alongside state and local governments enforce minimum requirements for operating a municipal solid waste landfill. The EPA requires the installation of a layer of two feet or more of compacted clay, overlaid by a flexible, durable geomembrane, such as high-density polyethylene. The purpose of this type of liner system is to protect groundwater and soil from leachate releases. A wide variety of liners are used for the control of leachate. These options include a variety of geomembranes, geosynthetic clay liners, geotextiles, geogrids, geonets, and geocomposites. Each type of liner has specific uses and abilities.
