Abstract: At 1:39 p.m. on June 8, 1988, Employees #1 through #3 were installing a 24 in. steel gas main in a trench that was approximately 125 ft long by 13 ft wide at the top and 5 ft wide at the bottom by approximately 14 ft deep. The area they were working in was shored by 2 ft 3/4 in., 8 ft by 12 ft steel plates. Two in. steel pipe was used as cross braces. The employees were going to weld two sections of pipe together. The ends did not match up so one section had to be marked and cut. This operation was performed inside the shored area. The retaining ring on the east pipe section had to be loosened and pushed back from the end of the pipe so that about 2 ft could be cut off. This ring was pushed back along the pipe by Employees #1 and #3, who, in so doing, stepped outside the shoring just as a section of the north side of the trench caved in. Employee #1 suffered a ruptured spleen, intestinal bleeding, and various contusions and abrasions. Employee #2 suffered a bruised right leg and Employee #3 suffered a fractured pelvis and various leg contusions. The area that caved in was where an inactive telephone service had been installed and intersected the gas main trench. Causes of this accident included working in a previously backfilled area, and lack of shoring in that area.