On August 2, 2017, a portion of a school building exploded in Minneapolis, Minn. Two individuals were killed, and nine others were injured as a result. A subcontract for the local gas company, CenterPoint Energy (CPE), was making the necessary piping configuration adjustments to allow the meter set to be moved from inside the utility room to outside. The three-inch plug isolation valve was left in the open position when the piping was disconnected. The utility room quickly filled with natural gas and ultimately led to the explosion.
On December 2, 2019 the National Transportation Safety Board (NTSB), who investigates transportation incidents released a Pipeline Accident Brief detailing the explosion. “The NTSB determines that the probable cause of the natural gas explosion at the Minnehaha Academy occurred when a pipefitting crew disassembled piping upstream of a gas service meter. Contributing to the accident was the lack of detailed documentation that clearly established the scope of work to be performed.”
CPE, the local gas company, immediately initiated several changes to their practices after the incident, including:
- Supplying more detailed individualized work scope and plans for customer meter moves.
- Requiring group safety meetings prior to the commencement of work on job sites (including both CPE employees and contractors). The meetings include detailed discussions of individual responsibilities.
- Enhancing training for all employees, including refresher training for tenured employees.
- Increasing awareness training for licensed mechanical contractors and customers about the demarcation point between LDC facilities and customer-owned piping.
APGA members are encouraged to review the NTSB briefing to evaluate what enhancements may be made to their practices to prevent future similar incidents,
https://www.ntsb.gov/investigations/AccidentReports/Reports/PAB1903.pdf. There were no safety recommendations issued with this report.
For questions on this article, please contact Erin Kurilla of APGA staff by phone at 202-464-2742 or by email at
ekurilla@apga.org.