Abstract: AT APPROXIMATELY 10:30 AM ON NOVEMBER 24, 1986, EMPLOYEES #1 AND #2 WERE HELPING TO INSTALL 8 INCH PVC SEWER PIPE IN A TRENCH. THE TRENCH WAS 9 FEET DEEP, 120 FEET LONG, 3 FEET WIDE AT THE BOTTOM AND 13 FEET, 6 INCHES WIDE AT THE TOP. THE TRENCH WAS UNSHORED AND INADEQUATELY SLOPED. THE SIDES OF THE TRENCH WERE WERE COMPOSED OF SHALE, WITH LAYERS SLANTING DOWN TOWARD THE BOTTOM ON THE TRENCH'S SOUTH SIDE. A TRACK LOADER HAD BEEN TRAVELING ALONG THE SOUTH SIDE, DUMPING GRAVEL INTO THE TRENCH AT VARIOUS POINTS TO SECURE THE PIPE . THE TRENCH RAN EAST TO WEST, TOWARD MAHHOLE #4. ABOUT 40 FEET EAST OF MANHOLE 4, THE SOUTH SIDE GAVE WAY AND SLID DOWN, TRAPPING EMPLOYEES #1 AND #2 IN THE BOTTOM OF THE TRENCH. A THIRD EMPLOYEE MANAGED TO GET OUT. EMPLOYEE #1 SUFFERED A COMPOUND FRACTURE OF HIS RIGHT LEG, JUST ABOVE THE ANKLE, AND EMPLOYEE #2 SUFFERED A SEVERLY SPRAINED LEFT ANKLE.