David Gray, an EPA spokesman in Dallas, said the company's plan identified a worst-case scenario as an accidental release of all 54,000 pounds of anhydrous ammonia, which at room temperature is a gas.
"This scenario is a plausible worse-case scenario as gaseous anhydrous ammonia can be lethal," Gray said.
The risk management plan also did not cite a possible explosion of ammonium nitrate, the solid granular fertilizer stored at the site. But that would not be unusual, he said, because ammonium nitrate is not regulated under the Clean Air Act.
The plant's plan said there was no risk of fire or explosion, and noted they had no sprinklers, water deluge or other safety mechanisms installed.
"We do not yet know what happened at this facility. The ongoing investigation will inform us on the plan's adequacy," Gray said.
The Texas Commission on Environmental Quality also dealt with the company, and issued a permit for handling anhydrous ammonia — which requires safety equipment the company had told the EPA it didn't have. But TCEQ acknowledged it may never have checked to confirm the equipment was there.
"It's a minor source under the Clean Air Act so it doesn't get much scrutiny at all," said Neil Carman, a Sierra Club clean air expert and chemist who used to work for the TCEQ.
The company's last contact with regulation may have come as recently as April 5, when the state Office of the State Chemist inspected the plant. But that agency focuses mostly on ensuring that commercial fertilizers are properly labeled and blended, said Roger Hoestenbach, the office's associate director. His inspectors found no problems, he said, but they would not have checked for safety systems such as sprinklers. That office also provided the company with the required license to store and handle ammonia nitrate, and renewed it in September after a summer inspection, he said.
Many other towns in Texas have small fertilizer distributors operating under similar regulations near populated areas.
Matt Murray, owner of ABC Fertilizer and Supply in Corsicana, bought his facility about 15 years ago. It sits in an industrial zone in the town of about 23,700 people, but in a community barely five miles long, it is still not far from the population center, he said.
"Every little community, town that's in Texas, has one of these," he said.
Murray's facility also has a state license to sell ammonium nitrate.
Even though Murray said he has discussed an evacuation plan with his local fire chief, there is nothing in writing. And he isn't required to have a formal plan. That may be changing now, he said.
"It's been something that's been brewing for years and years, ever since Oklahoma," he said.