Ammonium nitrate (AN) was the source of the April 17, 2013, explosion at a West, Texas, fertilizer warehouse that killed 14 people and injured more than 200.  But the real culprit may be the lack of updated codes and regulatory oversight for the substance. 

That’s the view of Rafael Moure-Eraso, chair of the U.S. Chemical Safety Board (CSB), which assembled a large investigative team in West the day after the accident.  In a June 27, 2013, hearing of the Senate Environment and Public Works Committee (EPW), Moure-Eraso summarized CSB’s observations and preliminary findings.  

No fire-suppression features

West Fertilizer was a small retail distribution center that blended fertilizer on-site and served farmers in the surrounding community.  Fertilizers such as AN and anhydrous ammonia were delivered to the site by railcar or truck.  The AN was stored in a warehouse with wood-framed bins with wooden walls.  The building had no automatic sprinkler or fire-suppression features.  Many residences, a nursing home, an apartment complex, a high school, and an intermediate school are within a 2,000-foot radius of West Fertilizer. 

On the day of the explosion, a fire of undetermined origin broke out and was reported to 911 dispatchers.  The community’s volunteer fire-fighting force responded.  Although the firefighters were aware of the hazard from the anhydrous ammonia tanks, they were not informed of the explosion hazard from approximately 60 tons of fertilizer-grade AN inside the warehouse.  While the firefighters were positioned nearby, the AN detonated.  Moure-Eraso indicated that about 30 tons of the AN exploded.  The schools were unoccupied, but residents of the nursing home were “severely affected,” said Moure-Eraso.

“A shock wave, traveling faster than the speed of sound, crushed buildings, flattened walls, and shattered windows,” Moure-Eraso said. 

In addition to the deaths and injuries, damage estimates from “some reports” may exceed $230 million, “an unimaginable blow to a town of just 2,800 residents–more than $80,000 for each man, woman, and child living in West,” according to Moure-Eraso.
In a May 17, 2013, letter the CSB said it considered the disaster “to be among the most serious U.S. chemical incidents affecting the public in many decades.”

Codes allow wooden storage

In his testimony, Moure-Eraso noted the following:

• Codes developed by both the National Fire Protection Association (NFPA) and the International Code Council (ICC) to ensure the safety of AN are quite old and appear to be confusing or contradictory even to code experts. 
• The most current NFPA 400 standard allows AN to be stored in wooden buildings and in wooden bins and does not mandate automatic sprinkler systems unless more than 2,500 tons of AN are stored.  In addition, the standard contains a grandfather provision that allows existing buildings there were constructed before code adoption–and that fail to meet all of its provisions–to continue in use.
• Fertilizer industry officials told the CSB that wooden buildings are still the norm for the distribution of AN fertilizer across the United States.
• OSHA’s explosives and blasting agents standards (29 CFR 1910.109) does have requirements for AN fertilizer but, like NFPA, does not prohibit wooden bins or wooden construction and does not require sprinklers unless more than 2,500 tons of AN are present.
• AN is not a listed chemical under EPA’s Risk Management Program (RMP, 40 CFR Part 68).  West Fertilizer was an RMP facility because of its stored anhydrous ammonia, and the company’s off-site consequence analysis considered only the possibility of an ammonia leak, not an explosion of AN.

This is only a portion of Moure-Eraso’s long list of “large holes” in safety measures governing AN.  

“Specifically, the CSB has not identified any U.S. standards or guidance that prohibit or discourage many of the factors that likely contributed to the West disaster,” said Moure-Eraso.

Click here for Moure-Eraso’s testimony at the EPW hearing.