Landfill Gas & Leachate Systems
Methane and other gases produced as a result of decomposition of organic waste may be captured and managed efficiently with landfill gas systems. Moretrench offers a range of landfill-related system installation and maintenance services for both passive and active gas collection and condensate and leachate collection. Those services include landfill gas extraction and conveyance systems, gas and leachate management, and barrier walls for perimeter containment and control.
Landfill Gas Extraction and Conveyance
Solid waste is made up of a significant portion of organic materials that produce methane and other gases during decomposition. Landfill gas systems capture and manage these gases.
Extraction systems consist of vertical and horizontal gas wells and conveyance piping . The collected gas may be processed through a permanent flare station or piped to an on-site methane power generating plant.
A good gas collection well must interface effectively with the solid waste, be constructed of materials capable of withstanding a corrosive environment, and be sealed with a bentonite plug and clean fill. The wellhead should be composed of valves, sample ports and flow measurement devices in order to evaluate the quality and quantity of extracted gases and can be enclosed within a subsurface vault. Read more here.
Landfill leachate is typically collected with slotted HDPE piping laid on a bed of permeable gravel materials within a trench and pumped to an on-site treatment plant. Treated leachate may then be discharged in accordance with local and state regulations.
Perimeter Cut-Off Walls
To ensure that landfill leachate and gas does not migrate off site, a perimeter cut-off wall may need to be installed. This typically consists of a soil-bentonite or cement-bentonite subsurface wall constructed by slurry trenching methods. Slurry trenches are narrow excavations typically keyed into an underlying impermeable stratum and backfilled with low permeability material to create hydraulic barriers that prevent the off-site migration of contaminated groundwater.