Last Thursday, May 16, officials from the Fire Marshal’s Office of Texas and the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives announced that the cause of the April 17 fertilizer-plant explosion in the town of West was “undetermined.” However, they had eliminated a number of possible causes and narrowed the probable ones to three: something to do with the 120-V electrical system in the plant, a golf cart stored in the same room with the ammonium nitrate bins, and arson.
Considering the horrible jumble of wreckage that the explosion left behind, even this much progress in the investigation is laudable. The investigators did determine that about 28 to 34 tons of ammonium nitrate, a fertilizer ingredient, exploded in the blast that dug a crater ten feet deep and 93 feet wide and caused seismometers to register the equivalent of a 2.1-magnitude earthquake. It could have been worse: another 140 tons of the material stored either onsite or in railcars at a nearby siding did not explode.
The investigation revealed that the ammonium nitrate that exploded was stored in wooden bins next to bins of flammable seeds. No sprinkler system was in place, and under current fire-code regulations none was required in the industrial facility.
The reconstructed sequence of events is fairly brief. At 7:29 PM on the evening of April 17, a fire was reported at the facility. Unless there were personnel on site that late in the evening, it is likely that no one was present at the time and the first report was turned in only after smoke was visible outside the plant. So the fire may have had some time to get going before it was reported. This is significant, because when ammonium nitrate is heated, it can turn from a white powder into a solid mass that transmits shock waves well.
Nine minutes after the fire was reported, firefighters arrived and began to play water on the blaze, which the investigation stated did not contribute to the explosion. Investigators speculated that as the fire progressed, a piece of heavy equipment might have come loose and fallen onto the now-solidified mass of ammonium nitrate, causing a detonation wave that led to two almost simultaneous explosions, 22 minutes after the fire was reported. It was these explosions that killed fifteen people, most of them firefighters, and laid waste to 37 blocks of the small town.
Not involved in the news conference at which these findings were announced, were members of the federal Chemical Safety Board (CSB), an agency charged with investigating chemical accidents with a view toward making recommendations about how to avoid them in the future. A Dallas Morning News reporter interviewed members of the Board involved in the West investigation, and their work is still continuing. Rather than focusing on the narrow question of exact causes, the CSB is examining the broader picture of how regulations affected the outcome of the incident and how community responses could have been improved. Questions have been raised, for example, about the wisdom of storing so much explosive material literally across the street from an apartment complex, and not much farther from a school and a nursing home. Any time a fire occurs at a facility where large amounts of ammonium nitrate are stored, prudence would dictate that at a minimum, the area within a possible explosion range should be evacuated.
On July 30, 2009, a fire at a fertilizer plant in Bryan, Texas where large quantities of ammonium nitrate were stored led to the evacuation of thousands of residents of that college town (home to Texas A&M) as a precaution. Fortunately, the fire burned itself out without incident and no damage outside the plant resulted. But as the West explosion shows, things could have turned out very differently. The Bryan incident also differs from West in that the people who accidentally started the fire were the ones who reported it promptly, giving more warning than otherwise.
While regulation is always a two-edged sword that can cause more harm than it alleviates, the West explosion will at least inspire re-examination of the whole complex of federal, state, and local laws, as well as insurance-company practices, that bear on the storage of ammonium-nitrate fertilizer. Determining the appropriate level of regulation, as well as the appropriate agency or agencies to issue regulations, is not an easy task. Local officials, especially in smaller towns such as West, rarely have the expertise to come up with customized, science-based regulations about hazardous materials that do not cause problems most of the time. But federal regulations are a blunt instrument, and customarily matters such as fire codes are left to the states and local communities to decide on. National organizations such as the National Fire Protection Association (NFPA) issue model guidelines and codes, but it is a state or local option as to whether these codes are made part of local laws.
The deaths in the West explosion were preventable, and I for one hope that the memory of this tragedy will lodge in the minds of firefighters, code-enforcement officials, and governmental agencies who are in a position to keep such things from happening, or at least lower the chances of them happening, in the future. The sharing of basic information and knowledge about how much of what stuff is stored where needs to be mandated so that first responders know both what they are dealing with and what is prudent to do in a given situation. Firefighting is a hazardous job, and loss of life in the line of duty is one of the risks that firefighters take on when they join their companies. But if better information and procedures, even if mandated by the federal government, will keep both firefighters and their communities safer in situations such as what happened in West last month, it may be time to change the way things are done.
Sources: I referred to an article on the West investigation news conference published on the Dallas Morning News website on May 18 at http://www.dallasnews.com/news/west-explosion/headlines/20130518-in-west-investigators-focus-shifts-from-explosions-cause-to-closing-safety-gaps.ece. I also used an article from the KRHD-TV website for information on the Bryan, Texas evacuation, found at http://www.abc40.com/story/10823244/ammonium-nitrate-fire-forces-mass-evacuation.