Movable cover for fluid containment tanks

A movable cover for selectively covering a fluid containment tank comprising:

• a rotatable storage drum;
• a flexible cover attached at a first end to the storage drum such that when the storage drum rotates in a first direction, the flexible cover rolls onto the storage drum to uncover the fluid containment tank and wherein the storage drum rotates in a second direction when the flexible cover is rolled off of the storage drum to cover the fluid containment tank;
• a plurality of cover retaining devices attached to the flexible cover and disposed on either side of the cover;
• a plurality of guide rails disposed on either side of the fluid containment tank, wherein the flexible cover extends into a cavity in each of the guide rails;
• each cavity including a guiding surface that selectively engages the cover retaining devices to suspend the flexible cover over the fluid tank;
• at least one drive belt extending along the length of the guide rails;
• and
• a lead bar removably attached to a second end of the flexible cover, wherein the lead bar is attached to the drive belt such that when the drive belt is driven, the lead bar and flexible cover move along the guide rails to selectively cover the fluid containment tank.