Abstract: Employee #1 was a helper for his coworker, a pipe layer. They were part of a crew that was installing a 16 in. diameter forced sanitary sewer main. Employee #1 was standing on a benched portion of the east side wall of a 7 to 8 ft deep trench. The west side wall of the trench was cut straight up and down along the pavement of a service road. There was already a 6 in. diameter forced sewer main in the same trench area, about 2 ft to the east and about 3 to 4 ft above the new sewer main. The trackhoe operator saw the west side wall start to collapse and yelled for the workers to get out of the trench. The pipe layer ran up the backfilled end of the trench to the south. He was knocked down and soil covered the back of his legs, but he did not sustain any recorded injuries. Employee #1 did not react quickly enough and was pinned by the collapsing dirt . He sustained a fractured lower leg and knee damage. There was a trench box on site, but it was not used because of clearance problems with the existing forced sewer main and the edge of the service road.