A Wisconsin oil refinery that has been cited for numerous serious safety problems continues to use a dangerous chemical that a union and advocacy groups say puts workers and nearby residents at unnecessary risk.

Murphy Oil USA Inc. in Superior, Wis., is one of 50 refineries nationwide using hydrofluoric acid, a corrosive, toxic chemical commonly known as HF. Explosions and other accidents involving HF have killed and injured refinery workers, according to a collaborative investigation by the Center for Public Integrity, a nonprofit investigative news organization in Washington, D.C., ABC News and the nonprofit Wisconsin Center for Investigative Journalism.

In its own risk management plan, mandated by the U.S. Environmental Protection Agency, Murphy Oil calculated the worst-case scenario: A low-hanging cloud of HF could travel 25 miles — which could envelop Superior and Duluth, Minn. — and put 180,000 people in the Twin Ports area at risk of injury or death.

“We see it as a national security issue,” said Bruce Speight, director of the Wisconsin Public Interest Research Group, a nonprofit public advocacy organization, in response to the investigation’s findings. “It goes beyond state lines: If an accident were to happen at the Murphy refinery, it wouldn’t only affect Wisconsin residents.”

Federal safety inspectors at the Occupational Safety and Health Administration (OSHA) in  2008 cited Murphy Oil for 35 violations — including 33 classified as “serious” and one as “willful.” (http://www.osha.gov/pls/imis/establishment.inspection_detail?id=307043505). When the company agreed to pay a $179,100 penalty, the willful violation was relabeled as “unclassified.”

At least 10 of the violations dealt with the alkylation unit, where hydrofluoric acid is used as a catalyst to refine high-octane gasoline. And 24 of the violations were for “process safety management of highly hazardous chemicals,” designed to prevent or minimize the consequences of dangerous chemical releases.

Refinery manager David Podratz said Murphy Oil recently underwent a safety audit of its alkylation unit.

He said the company has looked into alternatives, but decided to stay with HF. Podratz declined to offer specifics and referred most questions to Murphy Oil USA Inc.’s corporate office  in El Dorado, Ark., which did not respond to multiple phone messages this week.

A third of the nation’s 148 petroleum refineries use HF despite the availability of safer alternatives, putting at least 16 million Americans at risk, the investigation found. Industry groups say switching to safer chemicals can cost $50 million to $150 million per refinery.

Exposure to HF can cause serious lung damage, burns, and damage to eyes — even death.

In a 1987 accident at a Texas City, Tex., refinery that released a cloud of thousands of pounds of HF and isobutane, a fuel used in camp stoves, 4,000 residents were evacuated and more than 1,000 people went to hospitals reporting skin, eye, nose, throat and lung irritation.

According to Murphy Oil’s risk management plan, the Superior refinery has a maximum capacity of 81,000 pounds of hydrofluoric acid. The refinery is located within a half-mile of homes. Experiments conducted in the mid-1980s showed the chemical can be lethal nearly two miles from its point of release.

Kim Bro, a Washburn, Wis., consultant who advises on environmental risks, said the danger of an HF release at Superior appears to be “a low-likelihood but significant effect if it were to occur.”

But in context, he said, “It’s just one aspect of a pretty dirty business,” and added that this industrialized area of northern Wisconsin has many other health hazards.

When OSHA regulators inspected Murphy Oil in 2007, they cited unmarked valves in the alkylation unit, the proximity of one structure to hazardous chemicals, and a pipe carrying hydrofluoric acid that was too old and likely should have been replaced.

In the most serious violation, safety inspectors found deactivated alarms in the alkylation unit. It was classified as “willful,” meaning they found evidence of intentional violation of the law or plain indifference to it.

Malfunctioning alarms were blamed for a second Texas City refinery explosion, in 2005, that killed 15 people and injured 170 others.

Responding to the 2007 inspection at Murphy Oil, refinery manager Podratz told the Houston Chronicle in 2008  (http://www.chron.com/disp/story.mpl/front/5605687.html) the alarms were considered a nuisance because they went off when some control room doors were opened.

A relatively small refinery about two miles from Lake Superior, Murphy Oil employs 156 people at the 35,000-barrel-per-day plant, according to the U.S. Energy Information Administration. (http://www.eia.doe.gov/neic/rankings/refineries.htm)

Publicly held Murphy Oil Corp. has owned the Superior refinery since 1958 and is among the largest property taxpayers in Douglas County. The refinery contributes about $100 million in salaries and services to the local economy.

Keith Kesler, director of emergency management, communications and general services for Douglas County, which includes Superior, says Murphy Oil has always promptly notified him of safety issues at the refinery.

“They’re very good about reporting, even if they just spill a little gasoline,” said Kesler, who has held the position for 11 years.

“Certainly, we’ve tried to keep the community aware of what’s going on here,” said Podratz, citing a community advisory board and public meetings about Murphy’s risk management plan.

Advocates such as Speight, however, say it’s time for the remaining refineries to make the switch to HF alternatives.

United Steelworkers, a union representing 30,000 refinery workers nationwide, has urged refineries to phase out the use of HF.

The U.S. Public Interest Research Group, a federation of state advocacy groups including Speight’s organization in Wisconsin, is pushing to reintroduce federal legislation this year that would require companies to use safer alternatives to dangerous chemicals when available.

“If there’s a safer alternative, we should use it, we shouldn’t put the public at risk,” Speight said. “It’s just so commonsense.”

The Duluth News Tribune contributed to this report. The nonprofit Wisconsin Center for Investigative Journalism (www.WisconsinWatch.org) collaborates with Wisconsin Public Television, Wisconsin Public Radio, the UW-Madison School of Journalism & Mass Communication and other news media.