On January 22, 1999, while digging a trench behind a building at 406 Alabama Avenue, a backhoe operator damaged a 3/4 inch steel natural gas service line and a 1-inch water service line. This resulted in two leaks in the natural gas service line, which was operated at 35 psig. One leak occurred where the backhoe bucket had contacted and pulled the natural gas service line. The other was a physical separation of the gas service line at an underground joint near the meter, which was close to the building.
Gas migrated into the building at 406 Alabama Avenue, where it ignited about 10:02 a.m. An explosion followed, destroying three buildings: 404, 406, and 408 Alabama Avenue. Other buildings within a two-block area of the explosion sustained significant damage. Three fatalities, five serious injuries, and one minor injury resulted from this accident.
We determined that the probable cause of the accident was the failure of R&B Construction to establish and follow safe procedures for excavation activities, resulting in damage to a ¾-inch natural gas service line, and the failure of the Utilities Board of the City of Bridgeport to provide appropriate emergency response to the resulting natural gas leak.
As a result of this investigation, we made the following new safety recommendations:
To the Research and Special Programs Administration:
- Inform natural gas pipeline operators of the circumstances of the 1/22/88 accident in Bridgeport, AL. Further advise operators to review their emergency plans and procedures for responding to gas pipeline emergencies and modify them as necessary. The review should determine whether the procedures prompt the appropriate actinos for gas leaks caused by excavation damage near buildings and whether the procedures adequately address the possibility of multiple leaks and the underground migration of gas into nearby buildings.
- Evaluate, during annual inspections of utilities, the adequacy of operator emergency plans and written procedures for responding to gas pipeline emergencies, paying particular attention to procedures that address the possible migration of gas from excavation sites into nearby buildings. If warranted, require that operators modify the procedures.
The Alabama Public Service Commission:
- Inform Alabama natural gas operations of the 1/22/88 accident in Bridgeport, AL. Further advise operators to review their emergency plans and procedures for responding to gas pipeline emergencies and modify them as necessary. The review should determine whether the procedures prompt the appropriate actinos for gas leaks caused by excavation damage near buildings and whether the procedures adequately address the possibility of multiple leaks and the underground migration of gas into nearby buildings.
- Evaluate, during annual inspections of utilities, the adequacy of operator emergency plans and written procedures for responding to gas pipeline emergencies, paying particular attention to procedures that address the possible migration of gas from excavation sites into nearby buildings. If warranted, require that operators modify the procedures.
Publicize circumstances of the 1/22/88 accident in Bridgeport, AL and use the lessons learned from the acccident to increase public awareness of the importance of using the Center's one-call nbumber before beginning any ecavation work and of the safety hazards associated with underground utilities.
To the Utilities Board of the City of Bridgeport: Revise your emergency plan and procedures for responding to reported gas leaks, paying particular attention to the possibility of multiple leaks and to the underground migration of gas into nearby building from damaged pipelines. In addition, train appropriate personnel in the new procedures and ensure that they understand existing procedures to secure the area and protect people.
R&B Construction: Implement and enforce procedurs for using one-call before excavating and for safely excavating in the vicinity of underground utility lines. Provide adequate instruction to employees on the procedures.
