A parked, unoccupied semi truck rolled into an active excavation site on the Enbridge Line 5 pipeline in Saxon, Wisconsin earlier this week, rupturing the line and sending clouds of natural gas billowing into the air. The incident forced home evacuations, a no-fly zone over the area, and left about 50 residents without electricity as crews cut power to prevent ignition.
Nobody was hurt. That’s the good news.
The bad news is that nobody at Enbridge can explain how a parked truck managed to roll away in the first place. The company told local media the affected pipeline section was isolated quickly, but offered no details on what set the rig in motion.
Video from Fox 6 Milwaukee captured the scale of the release: thick clouds of evaporating natural gas swallowed the construction site, dwarfing tall cranes stationed nearby. Hazmat teams and emergency responders remained on scene through Wednesday, conducting air quality readings within a one-mile radius. They tested for combustible gases, carbon monoxide, hydrogen sulfide, and volatile organic compounds.
Monitoring showed no hazardous gas levels outside the immediate breach area, according to Wisconsin Public Radio. Cold comfort for the 50 households still sitting in the dark while power remained shut off as a precaution.
Line 5 is no small piece of infrastructure. Built in 1953, the pipeline stretches 645 miles between Superior, Wisconsin, and Sarnia, Ontario. It moves up to 23 million gallons of crude oil and liquefied natural gas every day.
The construction work at the Saxon site is part of a $1 billion project to reroute the pipeline away from the Bad River Band of Lake Superior Chippewa reservation. It’s a politically and environmentally sensitive undertaking that has been the subject of years of legal battles. That context makes a runaway truck hitting the pipeline look even worse.
The liquids carried by Line 5, primarily used to produce propane, evaporate rapidly when exposed to the atmosphere. That creates both an immediate health risk and an environmental problem. Undiluted natural gas is a potent greenhouse gas, and any uncontrolled release adds to the ledger that pipeline opponents have been building against Enbridge for years.
Whether a mechanical failure caused the rollaway or someone simply forgot to set the parking brake remains unknown. Roll-away incidents are a persistent enough problem in the auto industry to trigger recalls on passenger vehicles regularly. On a commercial truck parked at an active pipeline excavation site, the stakes are far higher.
Enbridge has faced sustained scrutiny over Line 5 for more than a decade. Environmental groups and tribal authorities have pushed to shut the aging pipeline down entirely, arguing that its age and routing make a catastrophic failure inevitable. The company has countered by investing in the reroute project, positioning it as proof of its commitment to safety and environmental responsibility.
A semi truck rolling unattended into the very pipeline that project is meant to protect does not help that argument.
Crews were still working the site as of Wednesday. The pipeline section remained isolated, and Enbridge had not provided a timeline for repairs or a resumption of full operations. Air quality teams continued their sweeps.
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