The US Chemical Safety Board (CSB) has released an investigation update on the December 2020 explosion at a chemical plant in Belle, West Virginia which killed one worker and injured three others.
The blast occurred in an industrial dryer unit while Optima Belle, the tenant at the plant, was performing a process to remove water from chlorinated dry bleach.
The explosion occurred at around 22:00 local time on December 8 and caused a shelter-in-place order to be issued by police which affected around 2,000 people. The 2-mile (3.2km) radius cordon around the plant was lifted on December 9 after emergency responders gave the area an all clear and a fire was extinguished.
According to Optima Chemicals, a preliminary investigation indicated that a 1,200 gallon metal dryer became over pressurised during a chemical product drying operation. The material in the dryer was a chlorinated compound used for sanitisation.
In an update on its investigation into the incident, the CSB said the explosion occurred when Optima Belle was performing a process to remove water from chlorinated dry bleach. Optima Belle was performing a trial batch process operation for the Clearon Corporation and the explosion occurred during the first trial batch. The blast resulted in multiple projectiles, one of which landed on a nearby highway and injured a local resident.
The CSB is working with Optima Belle to sample and test the chlorinated dry bleach powder involved in the incident. The CSB said dark specks were observed in the chlorinated dry bleach powder shortly before the incident, causing the powder samples to fail visual inspection multiple times before the incident. The CSB is working to determine the source of these dark specks and their composition.
The objective of the CSB‘s investigation is to determine the cause/probable cause of the explosion and develop a written report with the facts, conditions and circumstances associated with the incident.
Optima Chemicals is a tenant on the site in Belle, located around 12 miles (18km) south of Charleston, which belongs to Chemours. The company said that John Gillenwater, a chemical operator at the plant, was killed by the blast. Two other chemical operators were also inside the building when the explosion happened. Those two workers were taken to hospital where they were evaluated and later released.