a method of injecting steam into a landfill is provided . the steam enhances methane gas production in the landfill during the anaerobic phase , accelerates decomposition / biodegradation of the organic component of the trash prism during both the aerobic and anaerobic phases , and increases the rate of settlement of the landfill . a method of introducing a gaseous anaerobic fertilizer into the landfill is also provided . the fertilizer accelerates the decomposition / biodegradation of the organic component of the trash prism . a method of reducing the volume of a plastic component of the trash prism is provided , wherein the temperature and pressure of injected steam are raised to a level sufficient to melt plastic . finally , a method of reducing the volume of a quantity of refuse prior to placing the refuse in a landfill is provided , wherein the refuse is heated to melt a plastic component of the refuse .