Undetected cracks blamed for Enbridge gas pipeline blast in 2018

Photo: Dhruv Desai

The Transportation Safety Board of Canada says cracks that went undetected by the operator led to an Enbridge Inc. natural gas pipeline rupture that resulted in an explosion and fire northeast of Prince George in October 2018.

No one was injured in the incident but 125 people in a two-kilometre radius were evacuated as a precaution and the outage led to province-wide natural gas shortages and conservation efforts through the winter.

In its final report, the federal agency confirms the pipeline ruptured due to stress corrosion cracks on the outside surface of the pipe, echoing its initial diagnosis in an open letter sent to Enbridge subsidiary Westcoast Energy Inc. last October.

It says polyethylene tape coating applied to the exterior surface of the pipe to protect it from corrosion deteriorated over time, allowing soil moisture to come into contact with the pipe surface and leading to corrosion and cracking.

It says deficiencies in predicting the extent of cracking and a deferred inspection led to a hazard being undetected prior to the pipeline rupture.

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.

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.