Abstract: A five-man crew had the job of removing material buildup in a 5 mole, #1 Borax storage silo 33 feet in diameter and 80 feet high. The buildup was about 10 feet thick around the inside of the silo and extended the full length and height of the silo. The material was barred down from a scaffold and bosun chair and allowed to fall to the bottom of the silo where there is a manually operated gate to the silo's unloading chute. The entrance to the work area is through a 2-foot by 2-foot door in the side of the silo to a waiting suspended scaffold. When the barred-down material reached the silo entrance door, it was released through the unloading chute. The tail cable of the suspended scaffold was embedded in the loose material buildup. Employees #1 and #2 entered the silo with no lanyard attached to their body harnesses. They stood on the loose material and attempted to free the tail cable from the broken material they were standing on. The gate on the silo unloading chute opened and Employee #1 went down, grabbing the belt of Employee #2. Employee #1 remained embedded in the material during the next 5 hours while rescue attempts were made. Employee #1 suffocated by the time he was freed. Employee #2 was rescued and suffered no life threatening injuries.