Monday, June 21, 2010

Reader Comment 06-19-10 Chlorine Gas

Fred Millar replied to my complaints about his use of the term ‘midnight rules’ in a comment to that blog post. Just one of the typical problems with the use of political terms, they have meanings and they have connotations. In the current environment of political discourse we all have a tendency to hear the connotations that fit out pre-conceived picture of the political scene. I withdraw my complaint. Catastrophic Leaks Fred does close his comment with something certainly worth discussing. He wrote:
“Some homeland security experts talk about "The next BOOM?" that will compell attention to lack of effective regulation, whereas I tend to focus on the the next screaming "WHOOSH!" of toxic gas, which the best US gas modelers assume will mostly all blast out of a 90-ton chlorine railcar , e.g., within 2 minutes. Leaving local emergency responders no effective response except to run with everybody else.”
Fred is absolutely correct, the catastrophic failure of a chlorine (or anhydrous ammonia, or hydrogen fluoride, or whatever TIH of your particular fear) railcar is just about the most horrible consequence that can be reasonably imagined as a consequence of a terrorist attack or even just a plain old accident. Forget the overblown fears of a rogue nuke or a jihadist bio-attack; those are just Hollywood scenarios. Having said that, I don’t spend much time worrying about a catastrophic failure of a railcar. That takes too much skill, practice and patience to execute. You can’t just slap an explosive charge on one of the essentially armored tanks and get a catastrophic failure (and I have been assured by some people that would know that such testing has been done). I know the techniques that would have to be used, on a theoretical basis, and they are painstaking and require extensive practice and precise execution. In my opinion this puts them beyond the skill set of our recent attackers. So, I am concerned, but not worried. Less than Catastrophic Leaks No, what I am more afraid of happening is that an adequately trained and experienced attacker manages to put a relatively small hole in the side of one of these tankers. The huge toxic cloud that Fred fears from a catastrophic failure would not result and quite frankly no one would know to run from the much smaller toxic cloud that would form along the right-of-way of the train. The deaths would be relatively few, probably measured in the low hundreds (I know hundreds of dead civilians is unthinkable, but much less terrible than the tens of thousands that Fred is concerned with). The concentration would be low enough and the gas irritating enough to cause most people to get out of the cloud before they were exposed to a fatal dose. As the train continued to motor unaware through a large urban area at 10 to 15 miles per hour it would spread a cloud of chlorine gas that would permeate the areas on either side of the tracks, as the urban wind currents spread the cloud in unpredictable local eddies. Determining what areas to evacuate, and in which to order residents to shelter-in-place would take so much time as to be totally ineffective. Large numbers (thousands?) of people would be seriously injured before anyone realized the source of the release and could do something to stop the train and mitigate the release. For most of those injured people, if they were treated properly and promptly, the effects would be unpleasant, but certainly survivable. Unfortunately, our medical services are not set up to handle truly mass casualty type events over a large area of an urban center. The lung damage alone will require large numbers of ventilators and specialized therapies that are just not available on that scale. This would lead to subsequent deaths that would not be laid at the feet of the attackers, but would be blamed, with more than some justification, on the government for not adequately addressing the emergency needs of the populous. Prevention Which ever of us is more probably correct in predicting the more likely attack, I don’t think either of us really expects such an attack to happen (I know I don’t; I fear it, but don’t expect it). If that’s the case why worry? If I’m wrong about the attack not happening, the results just don’t bear considering. We call this low probability, high consequence event; you know like a well blow-out a mile down in the Gulf. With events like this you know that you have to take some action to prevent the unlikely. The question is how many resources can you afford to expend to prevent an unlikely event like this? This is what we need to decide. Both Fred and I would like to see all through-shipments of TIH chemicals moved outside of major urban areas. This would effectively eliminate the risk of these cars being targeted by terrorist, reducing the risk to ‘just’ the normal (very low) accident rate associated with the shipment of these chemicals. Fred believes that re-routing can accomplish this in most instances, I think that it is going to require some significant infrastructure changes (I know Fred, I oversimplified both of our positions, completely overlooking the elimination of some number of shipments). But, in any case, no matter how much Fred and I argue this between ourselves, it is readily apparent that no one is really willing to address this issue in a meaningful way. The costs are just too high it seems. Hopefully we will have time to change that calculation before such an attack actually occurs.

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