As part of landfill operations, individual waste cells are filled and then closed by capping them with a final cover and planting grasses for erosion control. The landfill cap consists of a clay cap on the side slopes and a composite capping system on the top, flatter portions of the landfill. Topsoil is placed and grasses are planted for long-term erosion control. In 2003, Waste Management closed and placed the final cap on 37 acres.