Once again, since there have been no reported terrorist incidents at chemical facilities reported in the press, we will look at chemical accidents and incidents that have been reported. It has been a busy couple of weeks according to news reports, so we have lots to choose from. Remember, this is not being done to review safety, but rather to look at such incidents to see what they can teach us about security and mitigation.
Four Clover Farms; Muhlenberg Township, PA
A leaking valve on an anhydrous ammonia tank caused the evacuation of the facility when the valve broke during an attempt to stop the leak. First responders spayed a water mist on the tank from an adjacent building. The water mist knocked down the toxic cloud, converting the anhydrous ammonia to its less toxic aqueous form. No one was injured in the incident.
Many toxic inhalation hazard (TIH) chemicals are at least partially soluble in water and become less toxic when dissolved in water. With this in mind, a method of leak mitigation used by first responders for these TIH it to spray the cloud with a water mist. There is no reason why these tanks could not be ‘protected’ by an automated water misting system similar to a fire sprinkler. It would not eliminate the downwind hazard, but it would reduce the area affected and slow the spread.
Kimberly-Clark, New Milford, CT
Two contractors were taken to the hospital when they were overcome by chemical fumes while working on the roof of a building at the Kimberly-Clark mill. The fumes came from a roof-top vent of a bleach storage tank. The local area around the mill was shut down while the source of the problem was identified.
This is a not unusual problem with storage tanks that vent directly to the atmosphere. The most toxic chemicals are normally vented through scrubbers, but a wide variety of problematic chemicals are vented directly to the atmosphere. While not normally a problem, they may present a problem to personnel working around the vents.
In non-standard conditions, like fires, these vents may become more of a problem. Vents for combustible storage tanks may be the source of explosive fumes when the tanks are heated near their boiling point during a fire. Security plans for facilities with flammable-release COI need to take this into account.
Propane Tanks used to Transport Stolen Anhydrous Ammonia
The following information is not strictly a chemical incident, but is worth passing along. It comes from an organization for security guards, PrivateOfficer.com. They report that methamphetamine labs are using empty portable propane tanks to store anhydrous ammonia. Some of these tanks are apparently being turned back into propane tank exchange facilities; a serious potential hazard to those that refill such tanks.
Anhydrous ammonia is a required chemical in the manufacture of methamphetamines. It is most often stolen from commercial or agricultural storage tanks. Anhydrous ammonia requires a pressurized tank for storage, so it should not be surprising that propane tanks, the most readily available portable pressure tanks available, are being used for this purpose.
It does point to a potential terrorist weapon problem. Anhydrous ammonia is not normally available in small portable tanks (other than the wheeled tanks used for agricultural applications) so it is not regulated under CFATS as a Theft/Diversion chemical like Chlorine. Many agricultural states do regulate anhydrous storage tanks, mandating security procedures to prevent theft by illicit drug manufacturers.