On April 25, 2019, about 4:20 a.m. local time, two 1,000-gallon nurse tanks (tank unit 200) on a trailer towed by a farm tractor released about 650 gallons of anhydrous ammonia (AA) gas on a public road near John Kevek Farms, Inc. (Kevek Farms) in Beach Park, Illinois. The farm tractor was towing a fertilizer applicator and trailer carrying tank unit 200 from one agricultural field to another when the applicator coupling disconnected, releasing AA gas through the adapter. The farm tractor operator was an independent contractor fertilizing fields for Kevek Farms, which owned the farm tractor, fertilizer applicator, applicator hose, and applicator coupling. Conserv FS, an agricultural cooperative, owned tank unit 200 and the trailer on which it was mounted. A total of 83 people, including first responders and residents, were treated at local hospitals in the 24 hours following the release. Fourteen of the 83 people were admitted and, of those, 8 were admitted to the intensive care unit. Symptoms included respiratory difficulty, eye pain, dizziness and nausea. Conditions were dark at the time of the release, and the temperature was 37°F with a wind speed of 6 mph.
Based on information the farm tractor operator provided to investigators, he began work on April 25 between 3:00 a.m. and 4:00 a.m. and fertilized a field in Winthrop Harbor, Illinois. He did not close any valves on the tank unit or disconnect the applicator hose before driving the farm tractor over public roads to reach another field. While on the way, he noticed the cab of the farm tractor begin to fill with AA gas. He immediately jumped out of the cab to escape the gas cloud and yelled for bystanders to call 911. He was not injured.
The first 911 call was received at 4:24 a.m. by a Gurnee Communications Center dispatcher. The caller reported a vehicle fire and one person lying on the ground, along with a strong smell and difficulty breathing. The Gurnee Communication Center dispatched a fire engine and ambulance. After emergency responders on the scene reported the presence of hazardous materials (hazmat), the response expanded to involve multiple fire and police departments.
During the response, a hazmat technician on the scene found the applicator coupling disconnected from the adapter mounted on the nurse tank unit’s bulkhead and the main shutoff valve open. Both tanks were empty. He closed the shutoff valve and instructed two firefighters to check the valves on top of the nurse tanks, which they found open. The hazmat technician instructed the firefighters to close the valves. The incident ended about 12:04 p.m.
Based on the starting load of AA and the acreage fertilized before the release, the owner of Kevek Farms estimated about 30 percent of the loaded AA remained in tank unit 200. The AA release study later conducted by the National Transportation Safety Board (NTSB) estimated that about 3,640 pounds (or 650 gallons) of AA was released over 30 to 40 minutes.
We determined that the probable cause of the April 25, 2019, Beach Park, Illinois, anhydrous ammonia release was the unscrewing of the applicator coupling from the anhydrous ammonia tank unit. Contributing to the severity of the release was Conserv FS’s configuration of the multiple tank unit piping, which restricted the flow rate such that the excess flow valves did not close when the applicator coupling unscrewed, allowing both tanks to release anhydrous ammonia until empty.
