Putrescible matter producing methane gas in landfills has caused explosions resulting in damaged property, caused injury and death. The danger may present from 10 to 20 years for any given site.
Landfill gas (LFG) is a natural byproduct of decomposing landfill waste. Without adequate controls, LFG can pollute the environment surrounding a landfill. In addition to emitting directly into the atmosphere, the gas can percolate through surrounding soils, penetrating nearby buildings and affecting vegetation growth.
As organic wastes decompose anaerobically within a landfill, a gaseous mixture of methane and carbon dioxide in roughly equal parts is produced. This 'landfill gas' was only recognised as a pollutant - and one with the potential to explode - relatively recently, and in devising ways of controlling the gas, many landfill sites have installed landfill gas recovery systems which either simply flare off the gas to dispose of it or alternatively utilise the gas for electricity production or heat generation.
Landfills were the number one source of Canadian emissions of methane in 1990 - 38% of a total of 3.7 megatonnes.