Abstract: At 3:00 p.m. on December 14, 2007, Employee #1 and a coworker, both certified concrete pump operators, had finished pumping 20 yards of concrete for the walls and columns of a new multi-story residential apartment building. One of them controlled the boom at the top of the building and had direct radio communication with the man at the trailer, who operated the machine's switches and controls. They had started work at approximately 9:00 a.m. Having completed the pour, Employee #1 and the coworker blew out the hose and pipes using air pressure and sponges, in accordance with cleaning procedures, and were working together at ground level to finish washing and cleaning the concrete pump hopper. Employee #1 reversed the hydraulic pump and dumped the excess concrete into the waste bin. He then proceeded to wash the hopper with the water hose. Seeing some sand still collected in the bottom of the hopper, he opened the hopper grate and reached inside with his left hand to scoop out the small amount of sand. Inside the hopper was an S-valve and an agitator tube. As Employee #1 reached down into the hopper, the S-tube cycled and trapped his hand against the concrete delivery cylinder. The coworker had momentarily turned away, but looked back at the hopper when he heard a bang. He saw what had happened and operated the controls to reverse the S-tube and release Employee #1's hand, which was nearly amputated. Subsequent investigation determined that the machine was not turned off and deenergized before Employee #1 reached into the hopper. Employee #1 had not received training in lockout/tagout procedures. He did control the switches and later stated that he believed that he had placed the pump in the OFF position as he completed the cleaning task. The employer was cited for violations related to lock-out/tag-out procedures.