Design and investigation of landfill caps to minimize infiltration

The design of landfill caps to minimize infiltration is an important aspect in the closure of sanitary landfills. Soil material properties, sequencing and use of vegetative layer/covers are important aspects in design of cap systems. Very few comprehensive field investigations have been undertaken to evaluate the effectiveness of various liner designs. Results of a field investigation from the U.S. is presented for a number of proposed cap designs. Each component of the water balance equation Δ S = [P+I] - [ET+R+Q] where S,P,I,ET,R and Q represent water storage, rainfall irrigation, evapo-transpiration, surface runoff, and deep seepage respectively, was measured during the investigation. The results of the investigation are discussed along with a description of the instrumentation program.