Wisconsin Administrative Code › Department of Natural Resources › NR 500-599 - Environmental Protection - Solid Waste Management › Chapter NR 504 - Landfill Location, Performance, Design And Construction Criteria › Section NR 504.08 - Minimum design and construction criteria for landfill gas extraction systems

Current through June 24, 2024
(1) GENERAL. All landfills accepting wastes
				with the potential to generate gas shall be designed to prevent the migration
				of explosive gases generated by the waste fill.
(2) ACTIVE GAS EXTRACTION AND TREATMENT. In
				order to efficiently collect and combust hazardous air contaminants, all
				landfills which accept municipal solid waste shall be designed with an active
				gas recovery system. All gas recovery systems shall include the following
				design features, unless otherwise approved by the department:
(a) Vertical gas extraction wells shall be
				proposed throughout the entire landfill with a maximum radius of influence of
				150 feet per well and lesser radii proposed for wells located near the
				perimeter of the landfill. The radii of influence of adjacent wells shall
				overlap. Alternate well spacings may be proposed if site specific data is
				obtained through performance of pump tests.
(b) All vertical gas extraction wells shall
				extend to 10 feet above the leachate collection system and shall be placed in
				36 inch diameter boreholes. An exemption may be proposed to allow for placement
				of gas extraction wells closer to the leachate collection system.
(c) The pipe in the borehole shall be a
				minimum 6 inch diameter, Schedule 80 polyvinylchloride or an approved
				alternate.
(d) The lower 2/3 to 3/4
				of the pipe in the borehole shall be slotted or perforated pipe.
(e) The backfill around the slotted or
				perforated pipe in the borehole shall be one to one and 1/2 inch washed stone.
				The top 10 feet of the borehole shall be sealed.
(f) Each gas extraction well shall have a
				flow control valve and sampling access port.
(g) The gas header system shall be looped to
				allow alternative flow paths for the gas.
(h) The minimum slope on the header pipe
				shall be 2% for pipes over the waste mass.
(i) Polyethylene pipe shall be used for
				header and lateral pipes.
(j) The
				sizing of the blower, header and laterals shall ensure that a minimum vacuum of
				10 inches water column is available in the header adjacent to those wells
				located furthest from the blower.
(k) A drip leg or equivalent shall be
				installed immediately before the blower to separate condensate from gas while
				preserving the suction at the wells while under maximum operating vacuum.
(l) All condensate transfer piping
				and gas transfer piping located outside of the limits of waste shall be
				designed to be fully encased in at least 2 feet of clay, double-cased pipe or
				by using another approved secondary containment method except for systems with
				multiple drip legs within the landfill where the bulk of the condensate has
				been removed.
(m) The system shall
				be designed to have the ability to collect and treat all condensate, measure
				volumes and collect samples.
(n) A
				flare shall be designed to meet the requirements of ch. NR 445.