Abstract: On January 30, 1990, two workers were in a 7 to 8 ft deep trench installing a bulkhead for a grade beam concrete pour. Employee #1 was in a squatting position when the west wall of the trench collapsed. He tried to jump up and out of the trench, but the shoe on his right foot caught on a reinforcing steel pier mat. The falling clay earth covered Employee #1's right leg to just above the knee, and forced his foot against the mat so that he couldn't move it. His left leg was raised above the debris and was not trapped. Employee #1 was taken to a hospital where his injury was diagnosed as fluid on the right knee and he was released. Employee #1's leg was put in a removable cast and he is expected to lose about three weeks of work. No shoring or sloping had been provided for the vertical trench walls.