The fines were due to the findings of multiple health and safety violations.
The violations left employees at the refinery, which straddles the Delaware-Pennsylvania border, vulnerable to accidents that could result in injury or possible death, said the U.S. Department of Labor's Occupational Safety and Health Administration.
The violations were addressed and weren't related to the refinery explosion that took place in May. The company announced plans Monday to close the ethylene unit where the blast happened.
OSHA was still investigating that explosion, but Sunoco’s initial investigation found that pipe failure caused the gas leak.