Abstract: Employee #1 was installing a sanitary sewer line in the bottom of a trench box that was 6 ft deep, 16 ft long and 12 ft wide. A second trench box that was 20 ft long and 8 ft high was placed on top of the 16-ft-long box. As pipe was installed an excavator opened the trench and slid the trench boxes along. The trench was not back filled as the trench boxes were moved ahead. A ladder was placed in the trench on the outside end of the trench boxes employees were going into the trench box from the end of the trench box. Employee #1 attempted to enter the trench box. The trench was not protected at the face of the trench's south end and collapsed. Employee #1 was engulfed with soil to waist height and was hospitalized.