Abstract: A retractable cover apparatus for use with an open-top bin is disclosed and comprises a cover and a support. The cover includes a cover portion and one or more carriage portions. Each carriage portion includes a pair of spaced-apart rollers rotatably mounted to said cover portion. The support defines a bifurcated track which permits constrained movement of said rollers in a manner which provides for movement of said cover between a sheltering position and an upwardly tilted open position; and between the sheltering position and a sealed position, relatively lower than the sheltering position. At the sheltering position, the cover overlies said open top when said bin is operatively disposed therebeneath; at the open position, the cover permits loading into said bin when said bin is operatively positioned; and at the sealed position, the cover is adapted to substantially seal said open top against the infiltration of atmospheric precipitation.