The Transportation Safety Board (TSB) of Canada has found that undetected stress corrosion cracking led to the 2018 Enbridge pipeline rupture that resulted in a fire near Prince George.
The Oct. 9 incident saw a 91-centimetre pipe rupture about 13 kilometres northeast of the city.
No one was injured in the blast, but it did force the evacuation of about 125 people within a two-kilometre radius.
The outage led to province-wide natural gas shortages and conservation efforts through the winter.
Deficiencies in predicting the extent of the cracking — as well as a deferred inspection — allowed the issue to go undetected, the TSB said.
“This allowed soil moisture to come into contact with the pipe surface, leading to corrosion and cracking,” said the TSB.
“Growing and merging over time, the cracks reduced the load-bearing capacity of the pipeline at normal operating pressures.”
The investigation also found that while Enbridge had conducted periodic emergency response exercises in the years before the explosion, not all nearby communities and other pipeline operators were included.
“If pipeline emergency response exercises are not conducted periodically with all potentially affected stakeholders, gaps in emergency response plans may not be identified, thereby increasing the risk that all parties will not be sufficiently prepared to respond to a pipeline emergency,” concluded the regulator.
Enbridge says it has completed a pipeline integrity program including enhanced pipeline inspections on its natural gas pipeline system in B.C. to prevent similar incidents from occurring.
Michele Harradence, Enbridge chief operations officer for gas transmission and midstream, apologized for the incident.
“We commit that we have learned from this incident and have taken steps to ensure the safety of our natural gas system,” she said in a statement on Wednesday.
— With files from The Canadian Press