A transfer pad cover includes a frame structure covered by a water-proof sheet material. The frame structure is supported by bar joists that are mounted for movement along tracks. The entire structure is moved by hand or motor or by a truck from which a liquid transfer will be made to a position adjacent the transfer pad during the transfer operation. When the material and frame structure are sufficiently weighted down so that it is unsafe to move the cover, the joists will rest on a ground surface, preventing movement of the cover. In an alternate embodiment, the rails are sloped and the truck pushes the cover off of the pad. When the truck leaves the pad, the slope of the rails causes the cover to automatically return to protect the pad under the influence of gravity.