Billing Code 4910-60-P
DEPARTMENT OF TRANSPORTATION
PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION

Pipeline Safety: Emergency Plans and Procedures for Responding to Multiple Gas Leaks and Migration of Gas into Buildings

AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT.

ACTION: Notice; issuance of an advisory bulletin.

SUMMARY: The Office of Pipeline Safety (OPS) is issuing this advisory to owners and operators of gas pipeline distribution systems. Owners and operators should review their emergency plans and procedures to determine whether the procedures prompt the appropriate actions 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.

FOR FURTHER INFORMATION CONTACT: Marvin Fell, (202)366-6205, or by e-mail, marvin.fell@rspa.dot.gov. This document can be viewed at the OPS home page at http://ops.dot.gov.

SUPPLEMENTARY INFORMATION:

I. Background

On January 22, 1999, while excavating a trench behind a building in the downtown area of Bridgeport, Alabama, a backhoe operator damaged a natural gas service line. This resulted in two leaks on the natural gas service line, which was operating at a pressure of 35 pounds per square inch (psig). One leak occurred where the backhoe bucket contacted the gas service line and pulled it aboveground. Although the second leak was not visible, the ensuing investigation revealed that the natural gas service line was separated at an underground joint near the gas meter, and close to a building. As a result, natural gas migrated into the building. The gas ignited, destroying three downtown buildings in a two square block area. The incident resulted in four fatalities and five injuries.

The National Transportation Safety Board (NTSB) investigated this incident and determined that the probable cause of the accident was (1) the failure of the construction contractor to establish and follow safe procedures for excavation activities, resulting in damage to the 3/4-inch steel natural gas service line and (2) the failure of the operator to provide appropriate emergency response to the subsequent natural gas leak.

The operator's written emergency procedures in effect at the time of the accident instructed service personnel to ". . . evaluate the extent of the emergency, request assistance as needed, and to inform the manager if necessary." However, the procedures did not instruct employees responding to a reported leak to consider the possibility of multiple leaks, check for gas accumulation in nearby buildings, and, if necessary, take steps to promptly stop the flow of gas.

II. Advisory Bulletin (ADB-01-02)

To: Owners and Operators of Gas Distribution Systems.

Subject: Emergency Plans and Procedures for Responding to Multiple Gas Leaks and Migration of Gas into Buildings

Purpose: To advise owners and operators of gas distribution pipeline systems to review their emergency plans and procedures to determine whether the procedures prompt the appropriate actions 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.

Advisory: Owners and operators of gas distribution systems should ensure that their emergency plans and procedures require employees who respond to gas leaks to consider the possibility of multiple leaks, to check for gas accumulation in nearby buildings, and, if necessary, to take steps to promptly stop the flow of gas. These procedures should be communicated to both employee and contractor personnel who are responsible for emergency response to pipeline incidents.

Issued in Washington, D.C. on _______________.

Jeffrey D. Wiese

Manager, Program Development

Office of Pipeline Safety