Abstract: On June 13, 2006, Employee #1, a concrete pump operator, was reading a concrete pump for a job at a construction site. Part of his duties involved the set-up and prejob inspection of the concrete pump, to ensure that debris was not in or around the pump "rock valve" that was located at the bottom of the hopper. While performing the set-up and prejob inspection of the concrete pump, he crawled underneath the hopper and opened a trap door. Then using a hand-held remote control, he cycled the valve so he could perform a check. He then cycled the valve a second time. Thinking he had turned the valve off with the remote, he placed his left hand through the opening when the valve cycled. Employee #1's left hand became pinned and was crushed. After the valve cycled back, Employee #1 was then able to free himself. Emergency services were contacted and Employee #1 was transported to UC Davis Medical Center, in Sacramento, California. He was then transferred to San Francisco Hospital, where he was hospitalized and underwent surgery to amputate his left hand several inches below the elbow.