2018 Husky Energy Refinery explosion

Husky Energy Oil Refinery explosion

Students from Superior High School waiting for rides after being evacuated due to the explosion.
Date	April 26, 2018 (2018-04-26)
Time	10:00 AM CST
Location	Superior, Wisconsin
Coordinates	46°41′23.9″N 92°04′13.4″W
Type	Explosion caused by mixture between flammable hydrocarbons and air.
Deaths	0
Non-fatal injuries	36

On April 26, 2018, an explosion and subsequent fire occurred at the Husky Energy Oil Refinery in Superior, Wisconsin. An initial explosion was reported at 10:00 AM and was extinguished close to noon, however a piece of debris had hit a storage tank containing asphalt, which ignited after spilling across the refinery, sending a thick plume of black smoke into the air. Thirty-six people, including 11 refinery employees, were sent to local hospitals, but there were ultimately no fatalities. Residents 3 miles to the east and west of the refinery, 2 miles to the north, and 10 miles to the south were evacuated from their homes temporarily due to concerns of both the toxicity of the smoke affecting those who lived south of the refinery and concerns regarding the plant's hydrofluoric acid tank causing further damage.

Background

The oil refinery in Superior, Wisconsin, which processes 50,000 barrels of oil a day, was acquired by Husky Energy from Calumet Specialty Products Partners in November 2017, retaining 180 Calumet employees. The company processes heavy oil from oil sands and conventional operations in western Canada. The refinery has a partnership with the Superior Fire Department, which provides its personnel training and resources when fighting industrial fires. It was eventually acquired by Canadian company Cenovus Energy in March 2021.

Early morning closure

On the morning of the explosion, at 5:30 a.m., refinery workers were planning to shut down the Fluid Catalytic Cracking Unit (FCCU) of the refinery for routine maintenance. The FCCU is used to break down hydrocarbons from crude oil into smaller hydrocarbons, which can blend into products such as gasoline. When the FCCU is shut down, slide valves in the middle of the unit are used as a barrier between a reactor, containing flammable hydrocarbons, and a regenerator, containing air. If the hydrocarbons and air mix, an explosion can occur. On the morning of the incident, workers attempted to stop the flow of hydrocarbons to the regenerating unit, however, one of the valves was eroded, causing air to flow upward into the reactor, into equipment that contained flammable hydrocarbons.

Explosion and fire

The mix of the air and hydrocarbons caused a massive explosion in the FCCU at approximately 10:00 a.m. that morning. The explosion sent debris flying 200 feet, one piece puncturing a hole in an above-ground storage tank that contained around 50,000 barrels of asphalt, causing the asphalt to spill along the ground into the refinery's main units. The asphalt ignited near additional storage tanks, eventually traveling to the FCCU of the refinery, causing a fire producing thick black smoke to travel into the air. The smoke went so far into the sky, it was picked up on weather radar.

Evacuation

The black smoke traveled southeast as far as Solon Springs in Douglas County. An evacuation of the plant was ordered at 1:00 p.m., however at 2:41 p.m., an evacuation for residents 10 miles south of the plant was ordered due to concerns of the toxicity of the huge plumes of black smoke. Residents who lived 3 miles north, east, and south of the refinery were also ordered to evacuate due to concerns about the change in the direction of the wind forcing the toxic smoke above more homes, and due to concerns about the refinery's hydrofluoric acid tank causing potential further explosions and damage. Schools in the Superior School District as well as the Essentia Health-St. Mary's Medical Center in Superior was also urged to evacuate. Students were evacuated to an AMSOIL building in northwestern Superior. Schools in the Maple School District in Douglas County were also closed as a precaution. Those injured were taken to hospitals in Duluth, Minnesota.

Firefight

The fire was initially expected to burn for days. The refinery's emergency response team, as well as the Superior Fire Department, initially went defensive against the fire due to concerns of safety due to the intense heat as well as other units of the refinery which were a cause of concern. A plan was developed at around 3 p.m. The large asphalt fire was extinguished with foam, and the fires around the crude unit of the refinery were extinguished with dry chemical fire extinguisher and water. The fire was fully extinguished at 7 p.m., however the evacuation order remained in place until 6 am the next day due to concerns regarding the stability of the plant's hydrogen fluoride tank.

Investigation, lawsuit, and aftermath

A sign on the exterior of the plant counting the days since the plant has been the focus of an incident.

The USCSB's report of this incident is still ongoing. They released their last report on the incident in August 2018 confirming a worn-out slide valve was a factor in the explosion, as well as a detailed animation of the incident with the information they concluded on December 18, 2019.

Controversy began to rise surrounding the facility's use of HF. Superior Mayor Jim Paine and Duluth Mayor Emily Larson have publicly come forward expressing disapproval with the plant's use of the chemical, citing multiple safety hazards to the surrounding communities had the HF tank been affected by the fire.

Husky Energy faced a class-action lawsuit against residents who were forced to evacuate their homes, citing a section from the report of the USCSB that stated that their equipment "failed to separate oxygen and hydrocarbons, allowing a flammable mixture to form." Husky reached a $1M settlement in July 2021.

Reconstruction of the refinery began in the fall of 2019, and is expected to become fully operational in early 2023. Construction was halted in May 2020 due to the COVID-19 pandemic, but was resumed in June 2020.

In April 2022, close to the fourth anniversary of the explosion, a group claiming to be a PR firm for Cenovus Energy called "Husky Friends" sent Superior residents postcards and kits containing things such as information about hydrogen fluoride. Cenovus came forward after the group began to announce their campaign to the press saying that they have no ties to the organization. The group's spokesperson told a local news channel in Duluth that the group's intent was to warn people about the dangers of HF using satire. The company has not filed legal action against the firm or announced any plans to.