Monday, April 21, 2008

Chemical Incident Review – 4-21-08

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.

Jasper Engines and Transmissions; Carefree, IN

On March 20th an explosion in a storage tank at the facility waste water treatment plant resulted in 26 people being treated at a local hospital and over 300 people being evacuated from the facility. A truck driver mistakenly unloaded ferric chloride into a sulfuric acid storage tank. The mistake was discovered in time to evacuate the waste treatment plant before the explosion.

Bulk unloading of chemicals into incorrect storage tanks can result in the mixing of incompatible chemicals. Explosions, toxic chemical releases, and fires are not unusual results. Allowing some one from off site to unload these chemicals without close supervision is asking for mistakes to happen. This is also a potential route for a terrorist attack.

A terrorist attack would not be limited to hooking up a tank wagon to an incorrect tank. It could include changing the paperwork on an incoming shipment to make it look like the correct chemical. This would be effective at facilities that do not allow truck drivers to unload their trucks.

The only effective way to avoid this problem is to test all incoming chemicals before they are moved into storage tanks. Even facilities without extensive lab capabilities can do a simple reaction test. A small sample of the incoming material is added to a sample of the material actually in the storage tank. The mixture is then observed for signs of a reaction. The truck is not unloaded until this test is passed.

Cargill; Booneville, AR

On March 23rd a fire started in this meat packing plant during some maintenance work on Sunday afternoon. A number of small explosions and the presence of a large anhydrous ammonia tank caused the firedepartment to pull their equipment back and allow the fire to burn. Ammonia leaking from the refrigeration system piping resulted in the evacuation of about 180 people, including residents of a nursing home and patients at a local hospital. The discovery of a second, un-vented ammonia tank on Monday resulted in new evacuations. No injuries were reported.

Concerns about storage tanks of gasses or volatile liquids exploding in a fire will keep fire fighters at a distance, preventing effective fire fighting. This is the reason that many facilities keep these storage tanks separated from the main facility and limiting flammable storage near these tanks. Tanks of chemicals like anhydrous ammonia are a special concern because emergency venting to relieve pressure will result in a toxic cloud being released.

The emergency response plan for the facility must address these problems. The local first responders have to be involved in the planning to ensure that they understand the true nature and extent of the problem. This may prevent them from needlessly allowing the facility to burn to the ground.

This facility was destroyed. The largest single employer in a small town is closed. Even though no one was hurt during the fire, the long term effects on the town are nearly as catastrophic as if there had been a large number of casualties.

Water Treatment Plant; Palm Beach, FL

A part of an on-site sodium hypochlorite production unit ‘exploded’ early in the morning of January 4th, sending plastic shards across the building and spilling a small quantity of bleach. It was not clear if the event was the result of burning hydrogen gas or simply an over-pressurization of the plastic cylinder. No one was injured.

The equipment was installed a number of years ago to replace a chlorine disinfection unit at the facility. While the unit was out of service after the incident, chlorine was used as a temporary replacement.

On-site production of bleach or chlorine has been advocated as a safer alternative to the use of delivered chlorine gas. Both systems use electricity and salt water to make their disinfection products. These systems typically produce a small amount of hydrogen gas that must be safely vented from the equipment. The article noted that the particular equipment used at this facility had reported problems with operators unnecessarily closing those vents.

Inherently Safer Technology is frequently more complicated technology than what it replaces. This needs to be taken into account during the planning and implementation process. Increased training for operators and management will be required. New risks and hazards will have to be learned and dealt with.

1 comment:

Anonymous said...

Seems too difficult for the chemical industry to learn what the gasoline station folks did many years ago -- make nozzles and tank openings different/incompatible for incompatible chemicals.  We had a chlorine release in Alexandria Va years ago because of a similar preventable human error.

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