The owners of an oil refining plant in El Dorado have agreed to pay a $4 million fine for violations of federal clean air regulations.
The Environmental Protection Agency and the state of Kansas announced the agreement with HollyFrontier on Thursday.
Regulators say the plant exceeded emission limits and did not comply with chemical accident prevention and safety requirements.
As part of the agreement, the company agreed to make improvements at the refinery to reduce emissions of sulfur dioxide and particulate matter, and to improve risk management practices.
The consent decree is subject to a 30-day public comment period and final court approval.