An employee opened the rear door of an open top refuse container and was struck by a roll of plastic sheeting that weighed approximately 300 pounds. As the roll struck him, the employee fell backwards and struck the back of his head on a concrete pad. Another roll of plastic sheeting dislodged from the container and landed on top of his legs. The employee sustained fractures to his right ankle and pelvis, as well as a laceration to back of his head.