Abstract: At approximately 10:50 a.m. on March 26, 2010, Employees #1 through #16, mostly working in the Slice Department, were exposed to anhydrous ammonia. Approximately 300 employees were evacuated from the plant. Other employees were decontaminated on-site by the county hazardous material responders. Thirty (30) gallons of anhydrous ammonia, used as a refrigerant, leaked from a fractured back flow regulator, Refrigerating Specialties Co., Model A4A. The liquid ammonia pooled on the roof and then flowed to the storm sewer drain. The storm sewer drain, made of polyvinyl chloride material, was cracked and released ammonia into the Slice Department. Employees #1 through #16 were taken to the hospital and treated with oxygen for breathing, albuterol inhaler for asthma, and eye washing. Employees #1 through #16 were not hospitalized.