The Respondent’s facility consists of a large distribution warehouse, including a cold storage area, over 100 truck loading bays, 80 trucks, a truck maintenance garage, a diesel fueling depot, an administrative office, and an employee cafeteria and locker rooms. There is an approximately 1,500 square foot ammonia refrigeration machinery room (the “Machinery Room”) located at the northwest end of the warehouse. The refrigeration equipment in the Machinery Room includes compressors, evaporators, condensers, and other machinery described below. The diesel fueling depot located on the west end of the truck maintenance garage contains a 10,000-gallon aboveground storage tank (“AST”) and a 5,000 gallon AST that each contain diesel fuel. The Facility is located in an industrial park, with a high school and a large residential community located less than one-quarter mile away. At all times relevant to the violations alleged herein, the Facility’s ammonia refrigeration system used approximately 10,000 pounds of anhydrous ammonia. A sign on the control panel outside the machinery room stated that the system was charged with 9,995 pounds of ammonia, a charge that is within 0.05% of the threshold amount of 10,000 and therefore likely to sometimes exceed the 10,000 pound threshold. Accordingly, Respondent “stored” and “handled” anhydrous ammonia.