OSHA, EPA  Investigations Lead to Convictions in Deadly Mill Explosion Case

OSHA, EPA Investigations Lead to Convictions in Deadly Mill Explosion Case

Oct. 19, 2023
The explosion killed 5 workers and seriously injured others.

A federal jury in Madison, Wisconsin, on Oct. 13, convicted current and former Didion Milling Inc. officials of workplace safety, environmental, fraud and obstruction of justice charges following a deadly explosion in 2017 at a corn mill that Didion Milling operated in Cambria, Wisconsin. The explosion killed five workers and seriously injured others.

Didion Milling Vice President of Operations, Derrick Clark, was convicted of conspiring to falsify documents, making false Clean Air Act compliance certifications as Didion’s “responsible official” and obstructing the Occupational Safety and Health Administration’s (OSHA) investigation of the explosion at the corn mill by making false and misleading statements during a deposition.

Former Didion Milling Food Safety Superintendent, Shawn Mesner, was convicted of participating in a fraud conspiracy against Didion Milling’s customers and conspiring to obstruct and mislead OSHA for his role in falsifying sanitation records used at Didion to track the completion of cleanings designed to remove accumulations of corn dust at the mill. 

“Derrick Clark and Shawn Messner chose to intentionally mislead OSHA investigators and made false statements about their knowledge of working conditions at the plant to protect themselves and cover their mistakes,” said OSHA Regional Administrator Bill Donovan in Chicago, in a statement. “Their blatant actions demonstrated a callous disregard for the loss of life, injuries and property damage that occurred under their leadership at the Didion Mill. Both Clark and Messner ignored their legal and moral obligation to protect workers before and after the explosion. OSHA is committed to taking all necessary action to hold employers responsible for protecting workers on the job.”

A permit issued under the Clean Air Act required compliance by Didion Milling at its corn mill including the operation of baghouses equipment, which are designed to limit the release of particulate matter like corn dust into the environment. The permit also required a “responsible official,” a senior manager with authority, to periodically certify the mill’s compliance with air pollution control permit conditions and disclose known permit violations. Clark falsely certified Didion’s compliance without disclosing that baghouse logs – documentation on maintenance of baghouse equipment – had been systematically falsified to conceal permit violations.

Grain dust can be explosive, and OSHA safety standards require grain milling facilities like the Didion Milling corn mill to develop and implement housekeeping programs, including regular cleanings, to reduce grain dust accumulation. Didion Milling maintained its master sanitation schedule to record the performance of required cleanings. Clark and Mesner were convicted of participating in a conspiracy to falsify that cleaning log, including directing others to backfill entries for uncompleted cleanings.

Federal law gives OSHA six months to gather facts and issue appropriate citations after a safety violation occurrence. In matters involving worker deaths, evidence that corporate managers knew about violations can result in issuance of a “willful” citation and a criminal referral.  OSHA subpoenaed Clark’s testimony in September 2017, during the corn mill explosion fatality investigation. Clark gave false and misleading testimony about his knowledge of problems with the dust collection system at Didion’s corn mill, his knowledge of explosion hazards and his knowledge of prior fires at the facility.

Didion Milling sold its milled corn products to food and beverage manufacturers. Sanitation at food manufacturing facilities is necessary for food safety, and excessive accumulations of grain dust can cause food safety problems. Through deceptive means, including repeatedly presenting a falsified cleaning log to food safety auditors, Mesner conspired to deceive Didion’s customers about its sanitation practices. As food safety superintendent, Mesner directed operations personnel to falsify the log to make it appear as if the cleaning schedule was being followed.  

The jury  also acquitted former Didion Milling environmental manager James Lenz of charges relating to falsifying environmental records and conspiring to make false statements and obstruct agency proceedings.  

Didion Milling previously pleaded guilty to falsifying the cleaning logs and baghouse logs at the mill and agreed to pay a criminal fine of $1,000,000 and restitution of $10.25 million to the victims of the 2017 explosion. Didion Milling shift superintendents Nicholas Booker, Michael Bright and Joel Niemeyer previously pleaded guilty to false statement charges for participating in the falsification of the cleaning logs and baghouse logs. Didion Milling shift superintendent Anthony Hess pleaded guilty to obstructing OSHA by making false and misleading statements about the accuracy of the cleaning log during a sworn statement taken as part of OSHA’s investigation into the mill explosion. Former Didion Milling environmental manager Joseph Winch previously pleaded guilty to conspiracy to conceal environmental violations from regulators by falsifying compliance certifications and providing falsified logs to regulators.

About the Author

EHS Today Staff

EHS Today's editorial staff includes:

Dave Blanchard, Editor-in-Chief: During his career Dave has led the editorial management of many of Endeavor Business Media's best-known brands, including IndustryWeekEHS Today, Material Handling & LogisticsLogistics Today, Supply Chain Technology News, and Business Finance. In addition, he serves as senior content director of the annual Safety Leadership Conference. With over 30 years of B2B media experience, Dave literally wrote the book on supply chain management, Supply Chain Management Best Practices (John Wiley & Sons, 2021), which has been translated into several languages and is currently in its third edition. He is a frequent speaker and moderator at major trade shows and conferences, and has won numerous awards for writing and editing. He is a voting member of the jury of the Logistics Hall of Fame, and is a graduate of Northern Illinois University.

Adrienne Selko, Senior Editor: In addition to her roles with EHS Today and the Safety Leadership Conference, Adrienne is also a senior editor at IndustryWeek and has written about many topics, with her current focus on workforce development strategies. She is also a senior editor at Material Handling & Logistics. Previously she was in corporate communications at a medical manufacturing company as well as a large regional bank. She is the author of Do I Have to Wear Garlic Around My Neck?, which made the Cleveland Plain Dealer's best sellers list.

Nicole Stempak, Managing Editor:  Nicole Stempak is managing editor of EHS Today and conference content manager of the Safety Leadership Conference.

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