On March 24, 1972, in the Annandale section of Fairfax County, VA, a contractor's backhoe snagged a 2 inch steel gas main, operating at 22 psig and pulled the main out of a compressional coupling 22 feet away. Gas compnay personnel arrived on the scene about 40 minutes later and started to search for the break. The gas was not shut off and nearby houses were not checked for the presence of gas. About 20 minutes after the gas company crew had arrived, a house, 240 feet away from the other houses exploded and burned. As a result of the accident, three persons died and one was injured; two houses were destoyed and and third was badly damaged.
We determined that the cause of the explosion in the three houses was the ignition of gas that leaked from a main damaged by a contractor's backhoe.
Contributing to the accident were:
- the delay by the has company in shutting off the flow of the leaking gas,
- the failure to check for gas in the houses,
- the failure of the area residents to report the presence of leaking gas in their houses, and
- the failure to notify the police and fire officials.
Also contributing were the failure of area residents to report tyhe odor of gas in their houses, and the failure of the county to supply the contractor with the accurate gas main location which had been provided by the gas company.
As a result of this investigation, we issued 23 new recommendations. We issued recommendations to the:
- Office of Pipeline Safety Administration,
- American Public Works Association,
- American Society of Mechanical Engineers Gas Piping Standards Committee,
- National Science Foundation,
- Office of Emergency Preparedness,
- National Bureau of Standards,
- The American Gas Association, and
- The Washington Gas Company
