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Daily cover is the name given to the layer of compressed soil or earth which is laid on top of a day's deposition of waste on an operational landfill site. The cover helps prevent the interaction between the waste and the air, reducing odors and enabling a firm base upon which vehicles may operate. Work at the Fresno Sanitary Landfill was instrumental in establishing the need and utility of daily cover.
While soils are the traditional materials employed in daily cover, alternative options such as "green waste", mixtures of paper sludge and tire derived aggregate (TDA) have displayed mechanical characteristics desirable for daily cover. When compared to traditional soil layers, the paper sludge paste was 2-3 times lighter, at least two orders of magnitude more impermeable, and comparable in shear strength.