Water infiltration in final cover layer of landfills in northeast region of Brazil

Final cover layers in landfills often suffer changes in their characteristics due to climatological cycles. This paper presents the behavior in two different configurations, performed on an experimental landfill, located in northeastern Brazil. The layers were instrumented with water content and temperature sensors, and a lysimeter to measure infiltration. The soil was characterized in laboratory and water retention curve allowed the suction evaluation and correlation with climatological variations. The total annual infiltration for the two layers was close to that recommended by USEPA for humid climate. Both layers presented infiltration rates in months of rainfall above 280 mm and saturation above 80%. When daily precipitation events were below 50 mm and the degree of saturation was below 60%, no infiltration was recorded. The two layers showed a very similar behavior with respect to infiltration, although the methanotrophic layer has always displayed saturation slightly above the capillary barrier.