Abstract: At approximately 2:30 a.m. on November 11, 2004, two employees manually rolled a breathing air six-pack bottle rack from the east end to the west end of Plant 4, in the Unicracker. The bottle cart was rolled at a walking pace, with the steering wheels in front. Employee #1 was behind the cart on the fixed wheel end, and Employee #2 was positioned at the left front corner. As the cart was moved down the center aisle of the Plant, it rolled into a low area around a manhole cover. The front wheels of the cart caught the edge of the manhole cover and the cart turned sideways and fell on Employee #2. Employee #2 sustained a fractured right tibia.