Abstract: At approximately 8:00 a.m. on March 8, 1991, Employees #1 through #3 were assigned to excavate an area around the main gas collection header to clean the water trap, which was believed to be filled or otherwise blocked with mud. They dug a 10 ft by 50 ft by 8 ft deep trench and cleaned out the trap before breaking for lunch. When they returned, the employees encountered some difficulty in the reassembling the trap and pipe. One of the employees, the foreman, decided to use an electric impact wrench. When he pushed the trigger of the wrench, the trench ignited. Employees #1 through #3 sustained burns in the ensuing fire. No tests were conducted before the employees entered the trench, nor was it verified that the pipe used to collect methane gas from the landfill was properly shut off.