The CSB has released its case study titled “Key Lessons for Preventing Inadvertent Mixing During Chemical Unloading Operations,” which examines a mixture of incompatible materials at a Processing Plant that produces distilled spirits and specialty wheat proteins and starches in Atchison, Kansas on October 21, 2016. The mixture resulted in a chemical release containing chlorine and other compounds that traveled into the community. The CSB’s investigation examines several key issues including the design of chemical transfer equipment, automated and remote shut off systems, and chemical unloading procedures.
The CSB’s investigation found that on the morning of the incident, a tanker truck arrived at the facility to deliver sulfuric acid. A facility employee escorted the driver to the locked loading dock and unlocked the gate to the fill lines and the sulfuric acid fill line. But unknown to the operator, the sodium hypochlorite fill line was also unlocked. And the two lines, which were only 18 inches apart, looked similar but were not clearly marked. The driver inadvertently connected his truck’s sulfuric acid hose to the sodium hypochlorite line and sulfuric acid began flowing inside.
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 two materials combined to produce chlorine gas and other by-products that sent over 140 individuals, both workers and members of the public, to area hospitals, and resulted in shelter-in-place and evacuation orders for thousands of local residents.
The CSB’s final report includes 11 key lessons and outlines clear safety improvements that can be implemented at similar facilities across the country.