The City of Denton Landfill at ECO-W.E.R.C.S. is a Type 1 Landfill which receives Municipal Solid Waste (MSW). The Landfill has a unique liner system designed to protect groundwater. Waste going into the Landfill is compacted and covered with dirt. The compacted waste decomposes very slowly due to the lack of oxygen, this process is called anaerobic decomposition. Landfill gas is the natural by-product of the decomposition of solid waste in landfills and is comprised primarily of carbon dioxide and methane. Methane is a greenhouse gas and an important energy source.
In 2008, the Landfill at ECO-W.E.R.C.S. installed a landfill gas collection system to collect and use landfill gas as a green energy source. Currently, there are 73 vertical wells (pictured below) and 34 horizontal collection lines. The system covers the entire 63-acres of current waste in place. The collected gas is directed to an electric power generator on-site which is connected to the Denton Municipal Utilities electric grid. The current capacity of the electric generator is 1.6 megawatts, powering the equivalent of approximately 1,600 homes per year. The electric power station was designed for expansion as methane gas production increases.
Enhanced Leachate Recirculation
In 2009, the Landfill at ECO-W.E.R.C.S. received approval from the Texas Commission on Environmental Quality (TCEQ) for the recirculation of leachate and stormwater to increase landfill gas production. Leachate is water that trickles down through the waste pack to the bottom liner. A leachate collection system pumps leachate back to the upper levels of the waste pack. This process speeds up the decomposition of waste which increases methane gas production and recovery.
With the addition of the enhanced leachate recirculation system, when the waste has completely decomposed, this allows the area to be reused for new trash and start the process over again. This unique effort to utilize methane emissions provides significant energy, economic and environmental benefits.
For more information on Landfill Gas to Energy projects visit the the Environmental Protection Agency's (EPA) Landfill Methane Outreach Program (LMOP).