Fifteen workers suffered “serious exposure” to an ammonia gas leak Sunday morning inside the Birds Eye food packaging plant in Darien, WI, officials said.
Police and firefighters responded at 5:15 a.m. to the plant at W880 County X, Darien, for a leak of ammonia gas used in a refrigeration process in certain rooms inside the plant.
Racine Fire Department Chief Steve Hansen, whose hazardous materials team was called to handle the leak, said those injured were being treated for eye irritation and ammonia gas “inhalation injuries,” including lung spasms.
The 15 workers ended up transported to five different area hospitals, a hazardous materials team official said.
Hansen said the ammonia at the plant is similar to the type farmers inject in crop fields as fertilizer.
Hansen said ammonia chemically is a “strong base” that, in heavy enough concentration, can combine with moisture on the skin and cause severe acid burns. But he said he was not aware of anyone at the plant receiving such burns.
Authorities on Sunday afternoon still were trying to learn the exact cause of the leak, but Walworth County Sheriff Kurt Picknell and Hansen said authorities suspect a “mechanical malfunction.”
Picknell said there was no explosion or fire during the leak.
The leak was contained to limited areas within the plant, and it did not affect all of the about 140 people who work the early shift at the plant, Picknell said. About 75 workers were triaged at the plant site before being released by medics who had responded to the incident, he said.
HazMat crews continued to ventilate the plant Sunday afternoon, and roads around the plant were open to traffic by Sunday afternoon.
Crews flushed ammonia from the plant by using fans to pressurize air inside the plant and force the ammonia outside. The release of ammonia into the air was considered a hazard for nearby residents and businesses, Picknell said.
Hansen expected it would take several hours to ventilate the plant and remove any potential pockets of ammonia throughout parts of the plant affected.
“It’s slow and methodical for the HazMat team,” Picknell said.
Plant monitoring equipment initially flagged the leak, authorities said. Employees in the plant and a nearby set of apartments for seasonal workers evacuated, and the plant’s operations shut down for several hours Sunday.
Employees followed internal operations plans for a hazardous materials release before authorities arrived, Picknell said.
Earlier Sunday, people arriving for work at Birds Eye were being directed to return home. By about 11 a.m., seasonal workers were allowed to return to apartments nearby as a HazMat team continued to work.
“The safety of our employees is our top priority and focus right now,” said Janice Monahan, a representative from Pinnacle Foods and Birds Eye, the two companies affiliated with the Darien plant.
Monahan confirmed several employees were hospitalized after the leak, but she did not offer further details on their injuries or their medical statuses.
The U.S. Environmental Protection Agency and the federal Occupational Safety and Health Administration were notified of the leak, Picknell said, and its cause remained under investigation by authorities and officials at Birds Eye and Pinnacle Foods, he and Hansen said.