The Christmas Eve fire that injured two workers at Suncor Energy’s Commerce City refinery began when a vapor cloud leaked from an unused pump valve and exploded as the facility was being shut down after extreme cold caused equipment failures, according to a federal investigation.
The vapor was released from a pump that was not functional and had not been used or properly inspected in seven years, according to the report detailing the U.S. Occupational Safety and Health Administration‘s investigation into the accident. The fire burned for six hours.
The report, obtained by The Denver Post through a federal Freedom of Information Act request, said the likelihood of injury had been higher because “employees were exposed to the hazards for nearly 7 years without the equipment being inspected properly.”
Suncor was fined $15,625 — the maximum allowed — in June for a serious violation of federal safety standards in connection with the fire at Colorado’s only oil refinery.
Most of the 1,090-page report was redacted, but it still revealed some new information about the circumstances surrounding the Dec. 24 fire that burned one person’s face so badly that he was hospitalized. A second worker was injured but did not need hospitalization, according to the report.
OSHA officials could not be reached to explain why so much of the investigative report was withheld from the public.
In response to a Denver Post inquiry about the investigation, Leithan Slade, a Suncor spokesman, wrote in an email, “Suncor has repaired and replaced the equipment related to the fire and is identifying, inspecting and testing all dead legs in the unit where the December 24, 2022 fire occurred. That work will be complete by the end of the year.”
The OSHA investigation raises questions about how Suncor manages its inspection of “dead legs,” an industry term for pipes that are no longer used and are shut off from liquids and vapors.
The explosion took place after a cold front rolled into the region, causing an extreme and fast temperature drop, on the afternoon of Dec. 21. The deep freeze caused extensive problems, and Suncor officials over the course of about a week shut down the refinery.
The Commerce City facility remained closed until early April while it was being repaired, fueling a more than 50% jump in gas prices in Colorado.
The cause of the shutdown was shrouded in secrecy with Suncor revealing little information about what had happened. Since then, details have been emerging in bits and pieces.
At a Nov. 16 meeting of the Air Quality Control Commission, state air regulators gave a briefing on Suncor’s operations and their efforts to enforce environmental regulations at the refinery. That briefing included an update on the December shutdown, which remains under investigation by the state’s Air Pollution Control Division.
The extreme weather caused instruments to freeze and the refinery was unable to make steam, said Shannon McMillan, who manages the air division’s compliance and enforcement program. Other equipment also needed to be shut off because of freezing and thawing issues.
“There were also two people that were injured during the initial days of the shutdown, which obviously further elevated the concerns about what was going on,” McMillan said.
However, her division does not investigate injury accidents. Instead, the air division is looking into air pollution violations that occurred during the shutdown. The refinery exceeded the amount of hydrogen sulfide, sulfur dioxide and visible emissions allowed under its air permits and exceeded the benzene limits allowed in its water permit. That investigation is ongoing, McMillan said.
The Suncor refinery has more than 200,000 flanges and valves that require inspection, according to the air division’s briefing.
Suncor gave OSHA a copy of its dead leg inspection program but it was redacted in the copy of the report provided to The Post.
John Jechura, a Colorado School of Mines professor in the chemical and biological engineering department, described a dead leg as being like a garden hose that is turned off at the spigot and has the valve closed on the nozzle.
“If it gets water in it and there’s a deep freeze, it freezes and expands,” Jechura said. “You don’t really know it until it thaws out.”
The report shows the pump that exploded was a backup and rarely used, Jechura said. It would make sense for the refinery to have a system of backups in place so that operations would not be interrupted if one failed.
Jechura, who reviewed the OSHA report for The Post, said too much information was blacked out to determine whether there were oversights that led to the explosion or what Suncor could have done to prevent the accident.
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