State regulators must provide more information to justify the air-emissions permit awarded to the Cemex Inc. cement plant near Lyons, the Environmental Protection Agency has ruled.
The cement plant faced a string of state and federal enforcement actions and agreed in March to pay a $528,325 fine.
The EPA order came in response to a petition by an environmental group claiming that the state Department of Public Health and Environment had improperly granted the permit.
The group, Rocky Mountain Clean Air Action, has merged with WildEarth Guardians.
"This is a step in holding the state accountable," said Jeremy Nichols, WildEarth Guardians’ climate and energy program director
While the EPA rejected most of the challenges, it did find that there was insufficient information explaining why the state did not impose tougher air-pollution controls in 1980 and 1985, when overhauls were made at the cement plant.
Under the Clean Air Act, when a plant makes substantial changes, it may be subject to newer and tougher air-quality standards.
"In five of seven cases, there was an explanation, but in these two, there wasn’t," said Carl Daly, section chief for air permitting in the EPA’s Denver office.