Preparation Pays Off At Thionyl Chloride Emergency

Seasoned responders are usually on the lookout for Murphy's Law at emergencies. What can go wrong quite often does go wrong and that is why we are called for help. But old Murphy took a day off at a hazardous material incident in northeastern Wisconsin...


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Seasoned responders are usually on the lookout for Murphy's Law at emergencies. What can go wrong quite often does go wrong and that is why we are called for help. But old Murphy took a day off at a hazardous material incident in northeastern Wisconsin.

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Photo by Val Ihde
A tractor trailer carrying drums containing thionyl chloride, a corrosive chemical, was struck by a train. This view of the incident is from the southeast.

On Thursday, Dec. 7, 1995, a tractor-trailer carrying 55 drums of thionyl chloride was hit by a slow-moving train near the intersection of U.S. Highway 41 and Cleveland Avenue in Marinette, WI. The resulting collision left 26 drums on the ground; several of the drums were heavily damaged. Surprisingly, no drums leaked. No one was hurt in the accident but four civilians were treated and released at a local hospital.

Corrosive Product

The chemical in the drums, thionyl chloride, is classified as a corrosive by the U.S. Department of Transportation (DOT). It is a colorless to slightly yellow liquid with a suffocating odor that is used to manufacture other chemicals that help to make toilet paper biodegradable. Thionyl chloride is also used to make pesticides, plastics, chlorinating agents and catalysts. It decomposes into hydrogen chloride, which is highly irritating, and sulphur dioxide, especially on contact with water.

Symptoms from overexposure to thionyl chloride include irritated and burned skin and eye, nose, and respiratory irritation. Exposure to the decomposition gases are moderately toxic; however, acute doses may cause pulmonary edema, bronchial spasms and death.

How It Happened

The truck driver said he did not see the train when he turned the corner onto the road that crossed the tracks. When he heard the train's air horn, he stepped on the accelerator in an attempt to get across the tracks but his truck was hit.

The impact cut the trailer in half and spun the back end, emptying the 26 drums onto the intersection. The truck traveled 200 feet before stopping with the front half of the trailer still attached. The train, consisting of three engines and about 15 rail cars, stopped almost immediately, as it was moving at only 14 mph.

All of the 55-gallon drums had been placed over axles. With 26 drums over the two axles in the rear of the trailer, the others were loaded over the tractor's axles in the front of the trailer. The middle of the trailer, where the train hit, was empty. This greatly reduced the likelihood of drums rupturing. Of the 26 drums expelled from the rear half of the trailer, only eight landed on their sides; the rest were upright.

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Photo by Val Ihde
Twenty-nine of the drums were loaded over the tractor's axles in the front of the trailer.

After the collision, the truck driver immediately ran to a nearby auto repair shop for help and to warn others to keep away. He called 911 and reported what happened and what was involved. The train engineer also went to the shop to warn people about the mishap and to evacuate the building. Three bystanders then instructed other people in the area to leave before themselves vacating the area.

About a half hour after these bystanders had left the scene, they began to experience upper respiratory discomfort. All three had apparently been exposed to chemical vapors at the scene and drove themselves to a hospital for treatment. The vapors were from residual chemical within the trailer and were not concentrated enough to cause a substantial exposure. The victims complained of nausea, burning noses and mouths, and funny tastes in their mouths. All were treated and released.

Law enforcement officials immediately shut off traffic from all directions, being careful to remain upwind and avoid exposure. (The wind was from the southwest at 7 mph; the temperature was 10 degrees Fahrenheit.) The Marinette Fire Department arrived and assisted with site control. The department's incident command system was immediately employed. Also, a command center was set up at the Marinette fire station.

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