A federal workplace safety regulator levied $531,000 in penalties and over a dozen safety citations against CHS Inc. for the September death of a grain bin worker in Nebraska.

On Friday, the Occupational Safety and Health Administration cited CHS, operating as Agri-Service Center Roseland in Roseland, Neb., for inadequate "safety gear," including the absence of a lifeline. The agency said the gear may have aided the grain worker, who became engulfed in a corn silo during a harvest and died of asphyxiation.

"We express our deepest condolences to the family," Inver Grove Heights-based CHS, the nation's top-grossing cooperative, said Friday in a statement. "We are reviewing the citations from OSHA and will reserve further comment at this time."

According to the OSHA letter, signed by Matthew Thurlby, OSHA's area director in Omaha, CHS has 15 days from receipt of the letter, dated March 8, to comply or contest the citations or request a meeting with OSHA.

In total, federal regulators cited CHS for 16 safety violations, including two alleged violations marked as "willful." Roughly $300,000 of the fines come from those two willful violations.

In addition to alleging an absence of proper safety equipment, OSHA says employees were unschooled on emergency protocols.

"The attendant for these bins did not know who to contact or how to contact them in the event of an emergency during the entry, such as an employee being engulfed," read one citation.

The grain worker was Travis Thelander, 34, according to local news reports in Nebraska. A family member declined to comment on the fine to the Star Tribune.

While a spokesperson for the Labor Department described the fines as "significant," past agriculture violations have resulted in larger monetary penalties. In 2011, federal authorities fined the operators of two Illinois grain elevators $1.4 million after the death of three workers, two of them teenagers.