Combustible dust was a contributing factor in the May 31 explosion that killed five people at Didion Milling in Cambria, WI, a federal official said.
Although the federal Chemical Safety Board (CSB) has not yet completed its report from months of inspections at the site of explosion, lead investigator Mary Beth Mulcahy said one of the likely results of the Didion investigation is establishing best practices, and suggestions for regulations, that would be intended to help industries become aware of the dangers of combustible dust, and how to alleviate them.
The May 31 explosion killed five workers and injured 12 others, including a 21-year-old employee who suffered a double leg amputation.
Occupational Safety and Health Administration (OSHA) investigators found in December the explosion likely resulted from Didion’s failures to correct the leakage and accumulation of highly combustible grain dust throughout the Cambria, WI, facility and to properly maintain equipment to control ignition sources.
The CSB is investigating the incident as are the Wisconsin State Fire Marshal’s Office and the Wisconsin Department of Justice.
The Occupational Safety and Health Administration (OSHA) levied more than $1.8 million in penalties for fire safety shortfalls at Didion and the company is appealing those fines.
By interviewing witnesses, inspecting the damaged building and its heavy equipment, and constructing a computer model of how the explosion is likely to have occurred, investigators with the CSB will increase their understanding of a hazard that is far more common in industry than many people realize, Mulcahy said.
“We want to learn,” she said, “what causes safety hazards, and what are the larger safety concerns. We try to understand why an incident happened (and) what we can do to prevent similar incidents. But we don’t oversee construction of plants. That’s the role of regulators.”
Cambria Fire Chief Cody Doucette said earlier this month that neither he nor state and federal investigators have definitively determined what caused the deadly late-night explosion. Furthermore, Doucette said, that determination may not be made for a long time.
“We may not hear for a year or more,” he said. “We’re still waiting.”
Mulcahy said she, too, is in no position yet to state the CSB’s findings about the Didion explosion, because those findings are still being compiled.
Combustible dust is likely a contributing factor and the hazard is not confined to corn milling or other aspects of the grain processing industry.
Mulcahy said one of the things CSB investigators want to determine, in Didion’s case, is exactly how powerful the explosion was, where it originated and the path it may have traveled. The damaged building and equipment provide key evidence, she said, that can be used to create a computer model.
The last time investigators of the agency were in Cambria, Mulcahy said, was around Thanksgiving.
They went in to the structure only when it was determined to be safe, she said, and at times examined heavy equipment after it was brought out of the plant, sometimes by moving it with a forklift.
Hilary Cohen, spokeswoman for the CSB, said the board’s “factual update” on the Cambria explosion will be presented “soon,” in Cambria and in public. However, she said the findings are not likely to be ready by the time the Village Board meets in early February.