Abstract: At approximately 3:30 a.m. on December 27, 2004, Employee #1 was performing an industrial vacuuming operation. Employee #1 and a coworker were cleaning out an area known as the casters, while the casters were shutdown. Before the facility is shut-down, freshly made steel billets are produced in the melt shop of the facility and are then rolled along a series of steel support rollers, like an assembly line. Underneath are a series of three concrete trenches that follow the steel rollers in parallel. The trenches are approximately 4 ft deep by 2 ft wide. These trenches are crossed perpendicularly by steel I-beams every few feet to help support the roller assembly. During the active process hot molten slag, metal scale and metal fragments are produced and accumulate in a gum- like manner. Over time the metal conglomeration builds up underneath the I-beams and fills up the concrete trenches. After the system was shut-down and cooled, an industrial vacuum cleaning service began chipping into the trench. As the brittle debris was chipped into a loose sand-like mass it was vacuumed up. Employee #1 and a coworker chipped their way down into the debris within the trench in an area easily accessible. They began chipping horizontally along the trench until they encountered areas of overhead debris that was gummed about the I-beams. Employee #1 was reported to have chipped in a crouched position until he had formed a tunnel. Above Employee #1 was large amounts of gummed-up metal scale and debris. After Employee #1 had worked himself several feet into such a tunnel the coworker left to go on brake. Employee #1 worked deeper into the tunnel. Sometime at this point the upper mass of the debris gave-way above him, engulfing him. Several solid chunks of metal were contained within the load and added to the weight of the debris. Employee #1 asphyxiated.