DENVER (KDVR) — Federal regulators objected to a plan that would have exempted the Suncor Energy refinery from monitoring some of its pollution sources.

The oil and gas refinery in Commerce City is undergoing an air pollution permit renewal under Title V of the Clean Air Act. Regulators with the Colorado Department of Public Health and Environment approved the proposed update before sending it to federal regulators for review.

But in a response, the Environmental Protection Agency found the plan would have exempted some pollution sources from monitoring without any justification. Under the proposed revision, Suncor would have been freed from monitoring flares — or the burning of raw gas — at its main plant, its truck loading dock and its railcar dock.

The EPA also found that Colorado has approved around 40 changes to Suncor’s air pollution permit since its last revision in 2009, all without public input.

Issuing those minor permits, “including those authorizing physical changes to the facility that would increase emissions, without a process for public notice and comment raises significant concerns,” the EPA commented.

Environmental justice was also a concern in the EPA’s objections. The agency pointed out that the population around the facility is “disproportionately impacted by multiple sources of industrial and transportation-related air pollution.”

The EPA urged the state to prepare a cumulative air quality assessment around the Suncor refinery to include emissions from nearby industrial facilities and transportation sources.

CDPHE will have 90 days to revise the areas of concern and present them to the public. The permit would then go back to the EPA for review.

Suncor refinery in Commerce City already site of air pollution violations

The Suncor refinery has a history of noncompliance when it comes to pollution. Both Rep. Diana DeGette and Sen. Michael Bennet raised the issue during the latest permitting process, urging the EPA to take a closer look at the proposed permit.

The company has already reached a record settlement with Colorado over air quality violations, including an incident when white ash rained from the facility on nearby neighborhoods.