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By David E. Hubler
Contributor, EDM Digest
An 80,000-gallon tank of anhydrous ammonia sprang a leak Tuesday morning at a co-op in south Mason City, Iowa, forcing two businesses to evacuate, the local Globe Gazette newspaper reported. There were no reported injuries, but some area roads were closed as a precaution against the ammonia leak.
According to the Mason City fire department, the tank was full when a piece of equipment flew off and sheared part of the valve about 9:30 a.m. Over the course of the day, about 21 percent of the ammonia escaped.
Cerro Gordo County Chief Deputy, David Hepperly, told the Globe Gazette that workers at the Five Star Co-Op were unable to stop the leak, so they had to let ammonia bleed off and monitor the weather.
Anhydrous ammonia is a colorless gas with pungent, suffocating fumes. It is used as an agricultural fertilizer and industrial refrigerant.
“As liquid anhydrous ammonia is released from its container into the air, it expands rapidly, forming a large cloud that acts like a heavier-than-air gas for a period of time,” the newspaper explained. “Because the vapors hug the ground initially, the chances for humans to be exposed are greater than with other gases. Symptoms of anhydrous ammonia exposure include eye, nose, and throat irritation, breathing difficulty, wheezing, or chest pain.”
Hazmat Team Uses Valve to Control Ammonia Leak
Mason City Fire Department Deputy Chief of Operations Aaron Beemer said that a hazmat team put a new valve in place to control the ammonia leak shortly before 4 p.m., almost seven hours after the leak was first reported. Area roads were then reopened.
"We're lucky enough to have the wind taking it to the south right now where there's no real effect for anybody," Cerro Gordo County Chief Deputy David Hepperly said. "Had the winds shifted to the west, we would have had to evacuate," he added.