Methane gas is produced in a landfill by anaerobic decomposition. It can be collected using current technology and then used to generate electricity, or it can be purified and used as a power-generating fuel. Leachate is a thick liquid that forms when garbage decomposes. Newer landfills have synthetic liners above a clay-like soil that help to prevent the leachate from leaking into the groundwater, causing contamination. Older landfills do not utilize this type of liner, and are therefore a threat to our groundwater especially to nearby neighborhoods.
Loose waste is another problem.
It attracts disease carrying vermin of all types, and it can fly away in the breeze. Once the landfill stops accepting waste, a final multi-layer cover must be applied to keep liquids away from the waste. Vegetation is then planted to reduce the effects of erosion. After the landfill is closed, the degradation and settlement of the contents eventually reaches completion and stabilization. Upon stabilization, some landfill sites are used as parks, playgrounds, golf courses, or other facilities.