Abstract: AT APPROXIMATELY 12:55 PM ON JUNE 8, 1988, EMPLOYEE #1 WAS INSTALLING THE LAST THREE PIECES OF 12 BY 42 INCH SHORING IN A DOUBLE MANHOLE WHICH WAS 20 FEET LONG, 10 FEET WIDE AND 10 FEET DEEP. HE WAS WORKING ON HIS KNEES PLACING PLANKS BEHIND THE 2 BY 10 PLANKING TO CLOSE THE OPENING UNDER THE 4-4 WAY CLAY ELECTRICAL DUCT LINE. THE ELECTRICAL LINE WAS COVERED WITH A LAYER OF CONCRETE 3 1/2 INCHES THICK. THE CONCRETE OVER AND ON EACH SIDE OF THE CONDUIT HAD BEEN REMOVED, BUT A PIECE OF THE BOTTOM STILL REMAINED. THE PIECE WAS 24 INCHES WIDE AND ABOUT 30 INCHES LONG, AND WAS LOCATED ABOVE EMPLOYEE #1. THE PIECE SUDDENLY BROKE IN TWO AND FELL ABOUT 36 INCHES, STRIKING EMPLOYEE #1 IN THE CALVES. HE WAS TAKEN TO THE HOSPITAL, TREATED FOR CUTS AND BRUISES, AND RELEASED BEFORE THE END OF HIS SHIFT.