Monday, November 25, 2019

West's Unsatisfying Legacy

When some half-million pounds of ammonium nitrate fertilizer exploded in the small Texas town of West on Apr. 17, 2013, it not only killed fifteen first responders and other people, injured 160, and damaged or destroyed dozens of buildings.  It showed what can happen when critical information about explosive-material storage is not shared with local authorities.  The West fire department did not know what they were dealing with, and if they had, many or all of the fatalities could have been averted.

Largely as a result of this accident, in the last days of the Obama administration the U. S. Environmental Protection Agency (EPA) issued what became known as its "Chemical Disaster Rule."  According to a recent report in the Texas Tribune, this rule required that companies storing large quantities of potentially explosive chemicals make the fact known to local first responders and the public, and called for companies to make specific emergency plans and conduct meetings on a regular basis about emergency planning.

The rule was delayed until President Trump took office, and now the EPA is saying it's going to roll back many of its provisions.  After the rule was proposed, affected industries complained about it loudly, and so the modified rule eliminates the requirement for public access to information on dangerous chemical inventories.  Corporations claimed, with some justification, that making their inventory quantities public is an invasion of privacy, and could lead to increased threats by terrorist groups wanting to target locations where large quantities of explosive materials are kept.

One reason that news reports mentioned for the rollback was the finding of the accident's cause by the U. S. Bureau of Alcohol, Tobacco, and Firearms (ATF), which was made public to a limited extent in May of 2016.  The ATF concluded that the accident was caused by arson, but the way they concluded that is curious, to say the least. 

According to a 2017 Houston Chronicle article, the agency reportedly spent about $2 million on the investigation and interviewed hundreds of witnesses .  In this way, the ATF says it systematically eliminated any natural and accidental fire scenarios.  Having eliminated all natural and accidental causes, the agency's conclusion was that the fire was deliberately set by a person or persons unknown.  However, there is not a smidgen of direct evidence that indicates the fire was actually arson.

In science, there is an adage that goes, "Absence of evidence is not evidence of absence."  Logically speaking, the ATF is justified in concluding that arson was the cause if and only if they have actually eliminated absolutely every other conceivable possible cause of the fire.  For example, I suspect they did not consider any possible supernatural causes, as those are outside the purview of modern science.  However, since a supernatural cause is still a cause, it counts in the list of other causes they should have considered and actively eliminated, and they didn't.

Apparently, this sort of thing is so common in arson investigations it has a nice Latin legal name:  "negative corpus."  Meaning, I suppose, the body wasn't there, so you can draw some conclusions from its absence.  The Chronicle article says that negative corpus findings are no longer recommended by standards published by the National Fire Protection Association (NFPA) adopted in 2011.  But local and even federal arson investigators still use it.

The convenient thing about the conclusion that arson was at fault is that it absolves the facility operator from a large burden of responsibility.  It's one thing if your own faulty practices cause an accident, but legally it's quite a different thing if somebody sneaks in and sets your place on fire deliberately. 

To be fair, I would not have the slightest clue of how to investigate an explosion so violent that it left a large crater where the plant used to be and scattered it over a good part of a square mile.  It's quite possible that some tiny critical piece of evidence—a frayed extension cord, for example—would be entirely obliterated in the blast, making a successful investigation of the cause impossible.  But I would also not want to spend two million dollars on an investigation and end up saying, "We dunno." 

The West explosion revealed serious deficiencies in how ammonium nitrate and other explosive materials are stored and how such information is shared, or not shared.  Although I do not have direct access to the revised EPA rule, I can only hope by reading between the lines of the summaries that it still has some provision for informing local first responders about the presence of dangerous chemicals.  That was the most harmful missing factor in what led up to the tragedy at West. 

And as the NFPA now recommends, investigators should be able to say, "Look, we tried, but there's just no way to figure out what caused this," instead of defaulting to a spurious conclusion of arson simply because it's legally convenient and lets companies off the hook.  While arson is also one of the logical possibilities, it shouldn't be shoved to the front of the line simply because it alleviates liability problems.

The town of West was forever changed by the explosion in 2013, and I expressed the hope at the time that something good would come of the tragedy in the form of tightened regulation of facilities that were potential bombs, such as the West Fertilizer Company plant.  It's entirely possible that the original EPA regulations were excessively burdensome to companies that are already doing more or less what they should do because their private insurers keep them in line.  But I hope the newly revised regulations still make sure that the local first responders, whose lives will be on the line if anything goes wrong, at least have the information they need to take suitable precautions for their own safety and the safety of others.

Sources:   I referred to articles in the Texas Tribune at and, and in the Houston Chronicle at, as well as the Wikipedia article on the West Fertilizer Company explosion.

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