Abstract: Employees #1 through #4 were in an approximately 79 ft long by 10 ft deep trench that was 7 ft wide at the top and 6 ft wide at the bottom. They were installing sections of sanitary sewer pipe connecting a new manhole to an existing manhole about 105 ft away. At the time of the accident, Employee #1 was at the far south end of the trench near where a trackhoe was located. He was holding a measuring rod to check the slope at the end of a section of pipe that had just been installed. Employees #2 and #3 were attempting to level the section of pipe by standing on top of it. Employee #4 was just north of them, having just left the area. The site foreman was on the pavement above the trench, using a laser measuring device to determine the slope of the pipe from the new manhole. The trackhoe operator was in the operator's seat of his vehicle at the south end of the trench. A cave-in occurred and Employee #1 suffered crushing injuries to his head and was killed. Employees #2 and #3 sustained multiple injuries, including head and facial fractures. Employee #4 suffered cuts and abrasions to his legs. The cause of the accident was the lack of adequate sloping and overall the failure to provide an effective protection system against cave-ins. The excavation had been was dug in previously disturbed soil, which was classified as OSHA Type C soil, a loose, cohesionless, granular soil. Water in the bottom of the trench had resulted in numerous cave-ins prior to the one that injured Employees #1 through #4. In addition, heavy equipment and vehicular traffic adjacent to the trench and they generated significant vibrations.