Abstract: The employer's crew was conducting a horizontal boring operation requiring them to drill approximately 4 ft underground for a distance of approximately 300 ft. The company had located the utilities by contacting the state's "one call" number, and had exposed the utilities where they would cross them. The first bore shot was thwarted by an obstruction and they had to pull out and try another spot approximately 2 to 4 ft south of the original point of entry. The second bore shot went well, but the job required attaching a reamer and a copper cable to the boring apparatus and pulling them back through. The 8 in. wide reamer was twice the diameter of the bore drill and it struck a gas line and a sewer line on its return to the boring machine. The natural gas traveled through the gas line and into an adjacent building, which exploded and ignited into flames. The employer had failed on the second shot to expose the utility at the point where the boring device was to cross it, and therefore was unaware of the change in elevation of the gas line.