Patent ID: 7448828

Claim:
A method of collecting biogas from a landfill having waste and an outer surface contacting the atmosphere, wherein the landfill contains (i) at or near the outer surface contacting the atmosphere a gas-containment layer that has low gas permeability; and (ii) a gas-permeable layer toward the interior of the landfill from the gas-containment layer and toward the exterior of most of the landfill waste mass, the gas-permeable layer having at least 10-fold the gas-permeability of the gas-containment layer; the method comprising: (a) collecting biogas from the landfill from a location toward the interior of the landfill from the gas-permeable layer with at least one gas-collection well that collects biogas from an extraction location toward the interior of the landfill from the gas-permeable layer and separated by waste from the gas-permeable layer and draws it to the surface, the well comprising a biogas-collecting wellhead at the extraction location and a gas-impermeable conduit linking the wellhead to the surface to draw biogas from the wellhead to the surface; wherein if any biogas is collected directly from the gas permeable layer, it is less than 10% of the volume of biogas collected from the landfill from the extraction location toward the interior of the landfill through the at least one gas-collection well.