There were several shortcomings in the design and labeling of loading stations as well as adherence to chemical unloading procedures at the MGPI Processing plant in Atchison, KS, which led to a toxic chemical release Oct. 21, federal officials said.

The MGPI facility produces distilled spirits and specialty wheat proteins and starches. The chemical release occurred when sulfuric acid inadvertently unloaded from a tanker truck into a fixed sodium hypochlorite tank at the plant, said officials at the Chemical Safety Board (CSB).

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The two materials combined to produce chlorine gas that sent over 140 individuals — workers and members of the public — to area hospitals and resulted in shelter-in-place and evacuation orders for thousands of local residents.

“This type of accident is preventable. Our investigation demonstrates all too clearly that complacency with routine practices and procedures can result in severe consequences,” said CSB Chairperson Vanessa Allen Sutherland. “A reaction that produced thousands of pounds of a hazardous chemical had the potential be much more serious – the CSB’s aim is to issue clear safety improvements which can be made to similar facilities across the country.”

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The CSB’s investigation found at 7:35 a.m., a tanker truck from Harcros Chemicals arrived at the MGPI facility to deliver sulfuric acid. There, a facility operator escorted the driver to a locked loading area. The operator unlocked the gate to the fill lines and also unlocked the sulfuric acid fill line.

The CSB found the facility operator likely did not notice the sodium hypochlorite fill line was also already unlocked before returning to his work station. The driver connected the sulfuric acid discharge hose from the truck into the sodium hypochlorite fill line. The line used to transfer sulfuric acid looked similar to the sodium hypochlorite line, and the two lines were in close proximity.

As a result of the incorrect connection, thousands of gallons of sulfuric acid from the tanker truck entered the facility’s sodium hypochlorite tank.

The resulting mixture created a dense green cloud, which traveled northeast of the facility until the wind shifted the cloud northwest toward a more densely populated area of town. The CSB investigation concluded emergency shutdown mechanisms were not in place or were not actuated from either a remote location at the facility or in the truck.

The CSB found a number of design deficiencies that increased the likelihood of an incorrect connection, such as the close proximity of the fill lines, and unclear and poorly placed chemical labels. In addition, the CSB found MGPI and Harcros did not follow internal procedures for unloading operations.

“Unloading activities occur at thousands of facilities across the country every day,” said CSB Investigator-in-Charge Lucy Tyler. “This event should serve to remind industry to review their own chemical unloading operations and work with motor carriers to ensure chemicals are unloaded safely.”

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