1. Otterburne, January 25, 2014
A natural gas pipeline operated by TransCanada ruptured, sending a massive fireball into the sky during the winter of 2014 in Otterburne, a small community about 60 kilometres outside of Winnipeg.The explosion would force Manitoba Hydro to shut down natural gas flows to thousands of customers in the area, leaving some residents without heat for day. A pre-existing crack present for over 50 years was the culprit in a gas line explosion, a Transportation Safety Board of Canada investigation found.
2. Brookdale, April 14, 2002
A TransCanada Pipelines gas line ruptured, exploded and caught fire two kilometres west of the village of Brookdale, northeast of Brandon. The explosion created two craters — one at each end of the ruptured section of pipe — and burned for nearly four hours.
About 100 people were evacuated within a four-kilometre radius of the blast, but there were no injuries.
The investigation found that, similar to the Rapid City blast, stress corrosion cracking was found to have caused the explosion. It was unusual in this case as the affected pipe was coated with asphalt and buried in non-corrosive soil. It was discovered that the combination of the pipe’s coating separating from the surface, a fluctuating water table, the presence of anaerobic bacteria and other factors all combined to create a corrosive environment.
3. St. Norbert, April 15, 1996
At a spot where a TransCanada gas pipeline crosses the La Salle River, gas escaped from a crack in the pipe, caught fire and an explosion destroyed a nearby home. The explosion also left a 13.5-metre-wide crater on the bottom of the river and damaged hydro lines and trees on both sides of the river. No one was injured.
The investigation found “environmental assisted cracking” to be the cause. A shift in the river slope led the pipe to move and stress out a crack in the pipe that may have been present since the pipeline was laid in 1962.
4. Rapid City, July 29, 1995
A TransCanada Pipelines gas line ruptured and caught fire near Rapid City, north of Brandon. An adjacent gas pipe also ruptured and caught fire which damaged a third line.
The incident left a 51-metres wide crater that was five metres deep. One TransCanada employee suffered minor cuts and bruises.
The investigation found the first rupture was caused by stress corrosion cracking, the slow growth of small cracks in an environment capable of corroding a pipe. The second rupture was partly the result of a delay in shutting down the flow of gas to the first pipe.