National Transportation Safety Board
Office of Public Affairs
Washington, D.C. - The National Transportation Safety Board today determined that a cable installation crew inadequately attempted to install an utility pole anchor and struck a natural gas pipeline, causing an explosion that killed four people.
On December 11, 1998, while attempting to install a utility pole support anchor in a city sidewalk in St. Cloud, Minnesota, a communications network installation crew struck and ruptured an underground, plastic gas pipeline, thereby precipitating a natural gas leak. About 40 minutes later, an explosion occurred. As a result of the explosion, one person was seriously injured, and 10 persons received minor injuries. Six buildings were destroyed.
The Board also determined that the delay by the cable installation crew to notify the proper authorities contributed to the severity of the accident. Had the crew foreman or his supervisor called 911 or the utility owner immediately after the rupture, emergency responders and the power company personnel may have had time to fully assess the risk and to take actions that could have helped either to prevent the explosion or to avoid the resulting loss of life, the Board said.
It was noted that the firefighters of the St. Cloud Fire Department responded quickly to the scene of the leak; however, once on the scene, the firefighters' actions did not fully address the risk to people and property posed by the leak or reduce the consequences of a possible fire or explosion.
The Board concluded that while there is no evidence of impairment in the circumstances of the accident, toxicological testing performed after this accident was not useful for determining whether alcohol or drugs had any influence on the actions of the crewmembers while they were installing the anchor. Also, the Board found that had the gas line in this accident been equipped with an excess flow valve, the valve may have closed after the pipeline ruptured and the explosion may not have occurred.
As a result of the investigation, the Safety Board made safety recommendations to the following:
· Research and Special Programs Administration - Through the Path Forward initiative, take lead in enforcing industry to advise excavators to notify the pipeline operator immediately if their work damages a pipeline, and to call 911 or other local emergency response number immediately if the damage results in a release of natural gas or other hazardous substance or potentially endangers life, health, or property.
· Occupation Safety and Health Administration - Require excavators to notify the pipeline operator immediately if their work damages a pipeline, and to cal 911 or other local emergency response number immediately if the damage results in a release of natural gas or other hazardous substance or potentially endangers life, health, or property;
· Associated General Contractors of America; the National Utility Contractors Association; the Power and Communications Contractors Association; the National Cable Television Association; and the American Public Works Association - Advise your membership to review and revise their anchor installation procedures as necessary to ensure that safety margins around buried utilities are absolutely observed not only above ground but throughout the installation process.
· International Association of Fire Chiefs - Inform your membership of the circumstances surrounding the December 11, 1998, accident in St. Cloud, Minnesota, to make them aware of the potential dangers of gas migrating into buildings from damaged underground gas lines.
A copy of the report will be available in several weeks on our website at http://www.ntsb.gov. Paper copies of the report, when available, can be purchased from the National Technical Information Service (800) 533-NTIS.
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The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.