A Chemical Accident or a Terrorist Attack?

There is an article on Mainetoday.com (http://news.mainetoday.com/apwire/D8P6DBIG0-137.html) about a chlorine release at a paper mill. The leak was caused when a driver delivering Sodium Hypochlorite to the mill hooked up to a tank containing Muriatic Acid. Fortunately, he realized his mistake and quickly shut the valve before too much Hypochlorite was moved into the tank. The resulting chlorine release resulted in 60 employees being decontaminated and treated on site and 9 employees being transported to the local hospital for decontamination, treatment and observation.

One of the interesting things about this accident is that this mill probably used to use Chlorine gas for their bleaching operations and switched to an 'inherently safer chemical', Sodium Hypochlorite. While Sodium Hypochlorite is safer than Chlorine it is not without it's own hazards.

A second interesting thing is that neither Sodium Hypochlorite nor Muriatic Acid (dilute Hydrochloric Acid) is a 'Chemical of Interest' in the proposed Appendix A to 6 CFR part 27. This means that if there were no other chemicals on the site that were listed in Appendix A (fortunately this is a paper mill so they have lots of hazardous chemicals), this site would not have to submit to a Top Screen procedure so that DHS could determine if it was a high-risk facility. This also means that they would not have to have any security measures in place to protect against terrorist attack.

If this truck driver had been a terrorist instead of some one making an honest mistake, this could have been a deadly attack. The valve would have remained open and most of the contents of the truck would have been added to the tank. This reaction between Sodium Hypochlorite and Muriatic Acid produces heat as well as Chlorine gas. Depending on the concentration of the Sodium Hypochlorite the heat might have been sufficient to boil the contents of the tank, possibly resulting in a tank rupture as well as the chlorine release. The Chlorine cloud would have been larger, possibly with a lethal concentration over some portion of the paper mill property. Due to the very large size of paper mills there probably would not have been much off site effect unless the storage tanks were near the property boundaries.

Security Vulnerability Assessments (SVA) and Site Security Plans (SSP) are going to have to address this type of attack. There are a large number of chemicals that are relatively innocuous by themselves, but become extremely dangerous when mixed with something else. Unfortunately, these situations are not currently regulated by the US Government, even though the Chemical Safety Board has repeatedly called on both OSHA and the EPA to revise their rules to cover reactive chemistries instead of just hazardous chemicals.

Prevention of this type of attack is relatively easy, once you identify the hazard. First off, no outsider is ever allowed to unload anything. It must be unloaded by properly trained and cleared site personnel. Secondly, you require the use of a dual key system to unlock the unloading lines (dedicated lines needless to say). The unloader has one key and a supervisor can get the second key from the QA lab, after the lab clears the incoming raw material. This is a very low cost, but effective system.

Unfortunately, too many facilities never consider this type of problem. If this solution had been in place this accident never would have happened. There would not have been a disruption of the mill operations and no one would have had to go to the hospital or treated for chlorine burns on site. This is another case where a good security procedure is also a good safety procedure.