Suncor Energy Inc. must pay a record US$10.5 million fine for air pollution at its Commerce City refinery in Colorado, the latest setback for the Canadian energy company’s effort to improve its health and safety record.

The punishment stems from incidents between July 2019 and June 2021, and requires Suncor to prevent air pollution at the plant near Denver, the Colorado Department of Public Health and Environment said in a release.

The agency also required the Calgary-based company that operates Alberta oil sands mines and wells as well as refineries across North America to double the number of air-pollution monitors at the plant. Many violations were linked to power disruptions.

The fine “is the largest our agency has ever reached for a single facility for air pollution,” said Jill Hunsaker Ryan, the agency’s executive director. “The agency will continue to use every tool available to prevent Suncor from having future violations.”

As part of the agreement, Suncor agreed to pay $2.5 million in penalties and undertake electrical-reliability improvements at a minimum cost of $8 million, Suncor said in an email. 

“Suncor is committed to continuous improvement and meeting our regulatory requirements,” the company said.

Suncor’s Commerce City refinery has been plagued by breakdowns, fires and emissions in recent years including fires. The company’s environmental and safety lapses sparked an investor revolt lead by Elliott Investment Management LP that resulted in the appointment of former Imperial Oil Ltd. chief Rich Kruger as Suncor CEO a year ago.