Mandan Refinery Responds to Chemical Releases; no indication of public threat | Accident and incident

Emergency and refinery officials responded Monday morning to a chemical release at the Mandan refinery that caused some workers to evacuate until the problem was resolved.

The North Dakota Department of Environmental Quality confirmed a release of hydrofluoric acid, which the oil refinery operator said began around 8 a.m. Marathon Petroleum did not know how much of the chemical was released, but said it was taking steps to monitor air quality and that “there is no indication of community impact.”

Local and state officials told the Tribune that they, too, did not believe the release posed a risk to the public.

Morton County Emergency Manager Cody Mattson said late Monday morning that his office would take steps to notify residents if the incident posed a threat, “but at this time there was no threat. “.

Traffic cones blocked the tanker’s entrance to the Mandan refinery in Marathon as officials dealt with a chemical release on Monday morning.

Tom Stromme

Marathon crews were able to stop the release Monday morning, said Rebekah Pfaff, a state environmental specialist who was in contact with the company.

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“They fired water cannons, which then reacted with the gas so that it became liquid and didn’t leave the site,” she said.

Workers were seen returning to the refinery mid-morning.

Marathon said no injuries were reported and it will conduct an investigation to determine the cause of the incident.

“The top priorities right now are keeping responders, the community safe and limiting the impact on the environment,” Marathon said.

Pfaff said she didn’t know what caused the incident and was unaware of any previous releases of the chemical in North Dakota. She expects Marathon to file a report with the state with more details about the release once the company has had time to investigate. She also didn’t know how much of the chemical had been released. Marathon said it would determine the volume during its investigation.

The company said it was monitoring the air with “technology commonly used in industrial emergency response practices” and was able to detect a variety of potential emissions.

The Department of Environmental Quality has an ambient air quality monitor in Bismarck, but it wouldn’t detect hydrofluoric acid, Pfaff said.

A light wind was present Monday morning in Bismarck-Mandan, blowing from south to north, according to the National Weather Service. The refinery is on the northern edge of Mandan along the Missouri River.


Tankers wait outside the Mandan refinery in Marathon on Monday morning. No trucks were allowed to enter the plant at that time due to a chemical release.

Tom Stromme

Hydrofluoric acid is widely used in petroleum refining and other industrial processes, according to the National Institute for Occupational Safety and Health. The substance “is considered a weak acid but remains extremely harmful due to its ability to penetrate tissue,” according to the institute.

Breathing the chemical can irritate the eyes, nose and respiratory tract, and skin contact can cause burns and in some cases be fatal. according to the United States Centers for Disease Control and Prevention. The severity of a person’s reaction depends on the amount and duration of exposure.

Incidents involving hydrofluoric acid at petroleum refineries have occurred in the past. A 2019 explosion at a Philadelphia refinery released more than 5,000 pounds of the chemical and prompted local laws to ban refineries from using the substance, according to StateImpact Pennsylvania report.

Monday’s incident is the second reported emergency in the past six months at the Mandan refinery. The plant burned more gas than normal in November 2021 when the plant’s cooling tower circulation pumps shut down unexpectedly, according to a report Marathon filed with the state. The company attributed the incident to an “equipment communication problem”.

Contact Amy R. Sisk at 701-250-8252 or [email protected]

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