Last month, U.S. District Court Judge James D. Peterson for the Western District of Wisconsin sentenced six Didion Milling Inc. officials, including a corporate vice president and former food safety, environmental, and operations managers, for their role in a fatal explosion on May 31, 2017, at a mill operated by Didion.

“On the night of the explosions, a fire originated in milling equipment at Didion’s corn mill in Cambria, Wisconsin,” states an EPA news release. “It led to a series of explosions in the facility, killing five workers and seriously injuring others. The explosions also damaged and caused the collapse of multiple mill buildings. An investigation into Didion’s worker and food safety and environmental practices uncovered criminal violations of law attributable to both the company and senior officials.”

Grain milling results in grain dust, which is flammable and must be effectively managed for workplace, environment, and food safety and quality reasons. Mill operators must adhere to rules and requirements intended to minimize hazards and maintain workplace safety through cleaning programs that remove dust accumulations from inside a mill. Mill operators must also capture dust before it gets into the environment as particulate matter.

Investigations of the explosion at the mill revealed long-standing inadequate safety measures and improper handling of grain dust that Didion and its employees concealed through falsified documents and other obstructive conduct.

Didion Vice President of Operations Derrick Clark was sentenced to 2 years in prison, a year of supervised release, and a $5,000 fine. Former Environmental Manager Joseph Winch was sentenced to 2 years in prison, 2 years of supervised release, and a $10,000 fine for conspiring to falsify Didion’s environmental compliance certifications. Former Food Safety Superintendent Shawn Mesner was sentenced to 2 years in prison and a year of supervised release after being convicted in October 2023 of conspiring to commit fraud and falsify Didion’s sanitation log.

Three former Didion shift superintendents—Anthony Hess, Joel Niemeyer, and Michael Bright—were sentenced to probation and fines for falsification of Didion’s sanitation log. Nicholas Booker, a fourth shift superintendent, is scheduled to be sentenced in March.
Former Didion Environmental Manager James Lenz was acquitted by the jury of charges relating to falsifying environmental records and conspiring to make false statements and obstruct agency proceedings.

Additionally, the Didion company pled guilty to falsifying its environmental and sanitation logs. In January 2024, Peterson sentenced the company to pay $10.25 million in restitution to the victims of the May 2017 explosion and a $1 million fine, as well as to serve 5 years of probation, with special conditions related to oversight of Didion’s operations.

“These defendants put Didion workers in grave danger and five people tragically lost their lives, devastating their families and their community,” said Attorney General Merrick B. Garland in the EPA news release. “Companies of all sizes should take note: failure to comply with our country’s workplace safety and environmental laws can cost workers their lives and put individual corporate managers in federal prison.”

The Department of Justice (DOJ) secured guilty pleas in October 2023 from the company, Didion, and company officials, as well as convictions against two more Didion officials.

“Didion Milling maintained its master sanitation schedule to record the performance of required cleanings,” states a DOJ press release. “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 [the Occupational Safety and Health Administration (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’s Clean Air Act (CAA) permit required specific compliance actions, including the operation of baghouse equipment, which is 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,” the DOJ press release adds.

Additionally, Didion’s milled corn products were sold 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,” according to the DOJ press release. “As food safety superintendent, Mesner directed operations personnel to falsify the log to make it appear as if the cleaning schedule was being followed.”

Regulations

To prevent dust explosions and fires, OSHA advises manufacturers to:

1. Develop and implement a written housekeeping program with instructions to reduce dust accumulations on ledges, floors, equipment, and other exposed surfaces.
2. Identify "priority" housekeeping areas in grain elevators.
3. Inside bucket elevators can undergo primary explosions. OSHA's grain handling standard requires that belts for these bucket elevators purchased after March 30, 1988, be conductive and have a surface electrical resistance not exceeding 300 megohms. These bucket elevators must be equipped with a motion detection device that will shut down the elevator when the belt speed is reduced by no more than 20 percent of the normal operating speed.
4. Implement a preventive maintenance program with regularly scheduled inspections for mechanical and safety control equipment, which may include heat-producing equipment such as motors, bearings, belts, etc.
5. Minimize ignition sources through controlling hot work (electric or gas welding, cutting, brazing, or similar flame-producing operations).
6. Install wiring and electrical equipment suitable for hazardous locations.
7. Design and properly locate dust collection systems to minimize explosion hazards.
8. Install an effective means of removing ferrous material from grain streams so such material doesn’t enter equipment such as hammer mills, grinders, and pulverizers.

CAA regulations require grain mill operators to use specialized industrial cleaning practices to reduce the accumulation of grain dust. Accurate records of cleaning and maintenance practices are mandatory.

Didion’s falsification of its cleaning logs concealed its CAA permit violations and, tragically, led to a fatal explosion.

The moral of this case study is that it’s imperative for risk managers and other corporate executives to realize that failure to comply with regulations can have more severe consequences than mere financial penalties. Failures of this magnitude often, sadly, result in tragedy and criminal penalties.