Respondent is primarily engaged in the production of anhydrous ammonia, urea fertilizer, and urea ammonium nitrate, which includes two ammonia units (A1 and A2), a urea production unit, a UAN unit, and various ancillary units, including a carbon dioxide pipeline compressor station and a hydrogen recovery unit. Respondent produces, processes, stores, or handles more than 10,000 pounds of anhydrous ammonia in multiple processes throughout the Facility. On Tuesday, December 29, 2015, the East and West cold storage tank relief valves lifted resulting from a malfunctioning solenoid valve on a governor oil system causing the ammonia refrigeration compressor to shut down. The malfunction was later determined to be the result of an undersized fuse designed to protect the safety interlock/instrumented system and the associated solenoid valve.