Abstract: At approximately 10:30 a.m. on September 18, 2007, Employee #1 and a coworker, both carpenters, were working at a heavy construction site in Lakeside, CA, where the employer was building a pump station for a public water reservoir. Among their duties that day was building a form for a poured concrete wall. The coworker was standing on the form, about 2 ft above the ground, and had his positioning device hooked to a horizontal waler to hold himself in place while he used both hands to move a horizontal beam into position. Employee #1 was walking behind him when the positioning device slipped off the waler. The coworker fell backward off the wall. He landed on his feet but struck Employee #1 with enough momentum to push him over. Employee #1's right leg became jammed against a wooden drain cover as he fell, fracturing both the tibia and fibula. He was transported to Sharp Grossmont Hospital, where he underwent surgery to repair his leg. The coworker was not injured.