Superior Mayor Jim Paine and Duluth Mayor Emily Larson are calling on the Husky Energy refinery in Superior to stop using hydrogen fluoride at the site after Thursday’s fire burned within 200 feet of the tank containing the dangerous chemical.

The move comes a day after Paine told the News Tribune that he needed more time to learn about hydrogen fluoride and the refinery process before taking a position on the issue.

In a news release Tuesday, Paine said he met with Rob Peabody, president and CEO of Husky Energy, and Chief Operating Officer Rob Symonds, and urged them to stop using hydrogen fluoride, citing concerns from the community.

“I asked them to discontinue its use and convert to a safer chemical process and to report back to me on any and all cost and infrastructure challenges that might prevent them from doing so,” Paine wrote.

Paine did not respond to requests for additional comment by the News Tribune Tuesday.

Breathing in hydrogen fluoride at high levels, or in combination with skin contact, can cause death from an irregular heartbeat or from fluid buildup in the lungs. The gas can also cause blindness by rapid destruction of the corneas. Evacuations Thursday were made with hydrogen fluoride in mind and officials considered a potential release of the chemical the worst-case scenario.

Larson announced her position in a news release earlier Tuesday.

In a telephone interview with the News Tribune Tuesday, Larson said that while it is Paine’s role to meet with government and Husky officials, her role was to support Paine and help send a strong message to Husky Energy.

“I need to make it very, very clear that that risk is not an acceptable one for our communities to manage,” Larson said.

Sulfuric acid is seen as a safer alternative to hydrogen fluoride.

A Husky Energy representative did not immediately respond to the News Tribune Tuesday, but on Monday, Kollin Schade, the refinery’s manager, said the company will examine whether to continue storing hydrogen fluoride at the facility, but the investigation must be completed first.

“We will be looking at all kinds of different options for the refinery configuration going forward. Right now … our main concern is to try to understand exactly what happened here,” Schade said during the Monday press conference.

The Superior refinery is one of about 50 nationally that still uses hydrogen fluoride to process high-octane gasoline.

The refinery can handle about 78,000 pounds of hydrogen fluoride, according to federal EPA records from 2012, but it contained about 15,000 pounds of the chemical at the time of the fire. The fire never reached the hydrogen fluoride, and on Friday Schade said that tank was “not compromised whatsoever” by the explosions or fire.

“We welcome their investment in our economies and the good-paying jobs this work provides. However, choosing the known risks of hydrogen fluoride is not something that is in keeping with the premise of being a good corporate partner. It elevates danger to our environment and our people,” Larson wrote in Tuesday’s release.

Cause of explosion still unknown

Thursday’s initial explosion happened within the fluid catalytic cracking unit, the U.S. Chemical Safety Hazard Investigation Board confirmed Tuesday, but it could take more than a year to figure out why.

That unit is where the crude oil is distilled to create gas and other products made from the crude, said the board’s senior adviser Tom Zoeller.

“It’s a high-temperature, high-pressure system,” he said, noting the refinery was preparing for a shutdown, a critical time for refineries.

Because the systems are regulated at certain temperatures and pressures, “you need to be very mindful of the operations,” Zoeller said.

The board will conduct a metallurgical analysis of the cracking unit to figure out why the metal it is constructed with ruptured. The team of four investigators will study the pattern of the blast, collect parts, ask for extensive documentation from Husky, examine maintenance records and interview workers who were on site during the explosion.

Zoeller said such investigations can take up to 18 months. Investigators from the board were at the site 16 hours after the first explosion, Zoeller said. They have not yet been given access to inspect the explosion site. The federal Chemical Safety Hazard Investigation Board doesn’t issue fines or citations, but does make recommendations. It could release some information prior to completing its report, Zoeller said, and if anything is discovered that the public has an urgent need to know, that would be released.

Agencies continue to monitor cleanup

The Wisconsin Department of Natural Resources continues to monitor the fire’s impact on nearby water and ensure the runoff water used in the firefighting efforts is properly disposed, WDNR communications director Jim Dick said in an email to the News Tribune Tuesday.

Nothing unusual has been found, but six or seven booms have been placed in Newton Creek to keep contaminants out, and firefighting runoff is being sent to on-site fire ponds, according to Dick.

“(Husky Energy) is considered the responsible party and therefore responsible for the actual cleanup and remediation work,” Dick said, adding that the DNR will ensure the company properly disposes runoff and will approve any of the company’s cleanup plans.

The DNR will continue to test the surface water “for an undetermined amount of time,” Dick said.

In a release Tuesday, Superior Water Light and Power said the city’s drinking water was not affected by Thursday’s explosion and fire and is safe for consumption.

“SWL&P’s water quality was not affected and the water is safe for all customers to use, and there is no longer a need for customers to conserve water,” the release said.

No water and natural gas infrastructure was damaged during the incident, the release said, but there was “minor damage to the electric system near the Husky refinery,” which has been repaired.

The U.S. Environmental Protection Agency has reported no elevated levels of chemicals in the air since Saturday.

All but one EPA on-scene coordinator left the scene Monday as it was determined Husky had “adequate air monitoring resources,” according to an EPA statement.

GHD, a contractor hired by Husky, continues to monitor air quality.

The EPA is supporting the DNR in water monitoring and sampling.

News Tribune staff writer Jana Hollingsworth contributed to this report.

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