An anhydrous ammonia leak occurred on April 16 at Five Star Cooperative’s Mason City, Iowa, location. A damaged valve was replaced by the hazardous materials team from the Mason City Fire Department around 4 p.m., according to the Globe Gazette, citing Deputy Chief of Operations Aaron Beemer, who estimated that some 21 percent of the ammonia inside the full 80,000-gallon tank escaped after the leak occurred around 9:30 a.m.
While the nearby Cartersville Elevator and Mason City Recycling Center were evacuated and nearby roadways closed, local residents were not evacuated, according to Cerro Gordo County Chief Deputy David Hepperly, who said wind blew the fumes away from inhabited areas.