Abstract: Employee #1, a coworker, and the acting foreman were in a 7-ft-wide by 30-ft-long by 5.5-to-6-ft-deep trench, tightening the side bolts on a dresser coupling. Employee #1 was sitting several feet away from the western end of the trench on a 12-ft by 20-ft cast iron water pipe with his feet on the northern side of the pipe. The coworker was at the western end of the trench on the southern side of the pipe between Employee #1 and the acting foreman, who was at the eastern end of the trench. The northern wall of the trench collapsed, pinning Employee #1's lower left side between the slab of earth and the pipe. He sustained a fractured leg. The trench had not been shored, sheeted, braced, or sloped. Employee #1 and the coworker had received no formal training on working in trenches. The acting foreman had received some training years ago. The trench soil was a clay and shale mixture.