Abstract: Employees of a local water district were dismantling a valve protection shack at a remote unattended drinking water storage tank with connecting valves and piping. Employee #1 climbed onto a 16 in. outlet valve in order to climb onto the roof to pull nails from the tin roofing and strip it off. He was standing with his left foot on a sector of the 16 in. butterfly valve and his right foot placed on the outside diameter of the valve wheel on the horizontal worm shaft (an 18 in. diameter wheel with four protruding spokes, made of 1 in. diameter pipe, extending 4 in. beyond the wheel). The chain and lock used to secure the wheel were not in place. When Employee #1 stepped onto the valve wheel with his right foot to climb onto the roof, the wheel turned and he fell, landing on his buttocks onto a spoke of the valve wheel and suffering a puncture to the rectum. Employee #1 failed to use a ladder for roof access.