Gas Collection & Management System

Gas collection and management system Methane gas is a natural gas produced when solid waste decomposes within a landfill. At American Landfill, methane gas is collected and controlled via underground pipes located within the waste disposal area.

In 1996, landfill gas collection wells were first installed at American Landfill. Today, American Landfill has more than 100 gas collection wells located at the facility. The landfill gas collection system in general includes gas collection wells, lateral and header pipes, gas condensate removal units, control valves, other ancillary components including blower units for vacuum application, and a utility flare to safely burn landfill gas.

Landfill gas collection wells are spaced approximately 250 feet apart to optimize gas collection. A typical landfill gas collection well consists of a combination of solid and perforated pipes and a wellhead assembly. A 36-inch borehole is drilled through the waste. The depth of the borehole is based on the design requirements. A combination of solid and perforated pipes are then placed in the borehole. Typically the pipe size of the gas well ranges from six inches to eight inches based on design requirements. The pipes utilized are either schedule 80 PVC pipes or SDR 17 HDPE pipes. After the pipe installation, washed gravel is placed around the perforated pipe and cohesive soils are placed around the solid pipe. Upon achieving the design grades for the well, a bentonite plug is installed on top of the ground surface around the well. A wellhead assembly consisting of a sampling port for gas monitoring, a temperature gauge and a control valve assembly is installed on top of the well to regulate the flow of landfill gas. In some areas of the facility,

American Landfill has installed a leachate extraction system in conjunction with the landfill gas collection system. This unique design assists in removal of liquids located within the waste and enhances gas production. The leachate removed by this method is transferred to a leachate storage tank by aid of gravity drains located within the waste.