Abstract: At approximately 2:00 p.m. on May 6, 2010, a gas serviceman of North Western Energy responded to a gas leak call from a residential home in Columbia Falls, MT. An electrical contractor had been using a backhoe to dig a hole for a new light pole and struck a gas line. The gas serviceman arrived at the site, assessed the site conditions, and called his office. Someone decided to dispatch three more employees to the gas-leak site. When the gas serviceman arrived, he talked to the fire department members already at the site. The gas serviceman used his gas monitor to determine if gas concentrations were at explosive levels in the air at the immediate area of the gas leak. After the gas serviceman's tests indicated that no explosive hazard was present, he had the electrical contractor remove his equipment from the area. When the three other employees from North Western Energy arrived on site, Employee #1 began monitoring air quality and two of his coworkers set up a Vermeer model backhoe to begin digging a bell-shaped hole around the 2-inch gas service main, so that the gas line could be repaired. After the first bell hole was completed, Employees #1 and one of the coworkers set up the backhoe to start digging the second bell hole. Employee #1 was monitoring the air around the second bell hole and had his back to the residential home, as one coworker was operating the backhoe. At approximately 4:00 p.m., an explosion occurred in the residential home. A large wall portion from the home struck and partially buried Employee #1. The coworker was knocked off the seat of the backhoe. The second coworker was in the first bell hole, approximately 150 feet from the second bell hole, when the explosion occurred. The second coworker checked Employee #1 and directed someone to call EMS. Employee #1 was killed.