The agreement also calls for updating process equipment operating procedures, worker training, equipment maintenance and performing tests on pressure vessels and piping to reduce the possibility of an accidental release of hazardous chemicals at the Wyoming refinery, which operates in proximity to nearly 10,000 residents.
A company spokesman was unavailable for comment on Friday.
Hazardous substances of concern used at the Sinclair refinery include large quantities of propane, butane, and flammable hydrocarbon mixtures.
Under the Clean Air Act, facilities that utilize hazardous and flammable substances above specified thresholds must submit a risk management plan to assist with emergency preparedness, chemical release prevention, and minimization of releases that occur.
In June 2010, EPA inspectors found that the facility had not adequately implemented those regulations. The settlement comes shortly after regulators fined Sinclair for a number of other incidents, according to the Casper Star-Tribune. In other incidents:
• The Occupational Safety and Health Administration fined Sinclair $215,250 for two separate fires in May that severely burned several workers.
• Sinclair and the EPA reached a $14.3 million settlement in August for excessive emissions of nitrous oxide and sulfur dioxide in incidents dating back to 2008.
• The Wyoming Department of Environmental Quality reached a $5.4 million settlement with Sinclair last year over a 2010 oil leak that killed birds on the refinery's evaporation ponds. Also in 2010, the department sought a $660,000 settlement with Sinclair over a spill of 3 million gallons of a gasoline blend.
The Sinclair refinery processes about 80,000 barrels of crude oil a day, including oil from the Canadian tar sands, into gasoline and diesel. The refinery was built in 1923.
The consent decree was filed in U.S. District Court for Wyoming and is subject to a 30-day comment period and final approval by the court.