Abstract: At approximately 4:45 a.m. on September 3, 2013, a coworker was approaching the Manning Ammonia display panel located in plant's chemical room adjacent to the plant's old engine refrigeration room, heard an audible ammonia system alarm coming from the panel. The coworker approached the Manning Ammonia display panel and saw that the Manning display panel was reading 250 parts per million. After observing the display panel the coworker went to the old engine refrigeration room's north door, opened it, and observed a dense vapor cloud hovering above the floor. The coworker closed the old engine refrigeration room's door and notified the Supervisor. The Supervisor evacuated the plant and called Emergency Medical Service. As the Supervisor evacuated the plant, the coworker returned to the old engine refrigeration room with a full face respirator, ammonia gloves and a sulfur stick, and observed the oil drain plug from the High Temperature Accumulator lying on the floor in a puddle of oil. The coworker picked up the oil drain plug and screwed the drain plug back into the elbow of the accumulator's drain and left the room. Employees #1, 2, and 3 worked as packers were working lines 5, 1 and 2. As they were being evacuated the employees started suffering health problems such as irritation in their throats, numbness around the mouth region and difficulty breathing. EMS County Paramedics treated the employees and transported them to St. Francis Hospital, where they were observed for exposure to chemicals and anxiety. The employees were released after two hours observation.