Leachate Recirculation Using Geocomposite Drainage Layer in Engineered MSW Landfills

At a municipal solid waste (MSW) landfill located in Michigan, leachate recirculation using a 34 m long by 12 m wide permeable blanket made of geocomposite drainage layer (GDL) was tested. Leachate was injected in the GDL using a perforated HDPE pipe place on the middle and immediately on the top of the GDL running parallel to the width of the blanket. Sixteen moisture content sensors, one piezometer, two thermocouple sensors, and a vertical load sensor were embedded immediately below the GDL blanket to monitor the flow of recirculated leachate. After the blanket was covered with waste, leachate was injected in the blanket at rates ranging from 0.9 to 2.6 m³/hr/m of the blanket width. Data collected from the embedded sensors indicated that the leachate traveled at a rate ranging from 8 to 25 m/hr through the blanket depending upon the rate of injection of the leachate. The rate of leachate flow through the GDL layer was not uniform. However, every moisture content sensor either remained saturated or indicated an increase in the moisture content as a result of leachate recirculation. Hence, we have concluded that the GDL blanket is a feasible alternative for recirculation or injection of leachate in MSW landfills.