Substantial volumes of gas are generated at the Bisasar Road and other landfill sites as a result of the natural processes of refuse degradation in an anaerobic environment. The first stage of a full scale gas recovery system was commissioned at the Bisasar Road landfill site in September 1996. A gas curtain installed in September 1995 has been effective in stopping the sideways movement of gas. A volume of 900 m³ of gas, with an average methane content of 42% is being pumped and flared continuously. One benefit from removing the gas is greater settlement of the refuse due to accelerated decomposition of organic material. This extends the useful life of the landfill. Other benefits include reduced damage to the ozone layer, less chance of vegetation die back and reduced risk of spontaneous fires within the landfill. Landfill gas management also reduces the risk and nuisance of the landfill site to adjacent residential areas. Containing and removing the gas also provides the opportunity for its use as an alternative source of energy. A negative impact, which is probably negligible, but not quantifiable at this stage, is the flaring's contribution to global warming.