Abstract: At approximately 7:00 p.m. on June 9, 1994, employees were using a John Deere excavator to bust concrete into an excavation hole at a high-rise facility for the elderly. The hole had been dug on May 23 to remove an underground storage tank. In the process, a natural gas pipeline had been exposed, and the employer failed to support or adequately protect the line. The concrete blasting continued uninterrupted for between 5 and 6 hours a day, and the vibrations caused the unsecured pipeline to separate from its compression coupling. Natural gas permeated the ground and entered the building; the gas exploded and caught fire. Damage to the exterior pipe covering indicated that there had also been physical damage to the pipe. No employee injuries were reported as a result of this accident.