Exxon Mobil Corp. and the federal government have settled a case arising from the company being charged with violating the Clean Air Act due to air pollution violations at eight petrochemical plants in Texas and Louisiana.

News sources say the company has agreed to pay a $2.5 million civil penalty related the violations and spend approximately $300 million to install new equipment to improve operation and monitoring of industrial flares at the facilities.

Secretary of State Rex Tillerson was chief executive officer at Exxon until late last year.

In another EPA action, Denver-based PDC Energy will also pay a $2.5 million civil penalty – for violations of the Clean Air Act stemming from emissions of volatile organic compounds from its oil and gas exploration and production in Colorado. The company will also pay $22.2 million related to storage tanks that were leaking smog-forming compounds.

PDC Energy has agreed to spend about $18 million on systems upgrades and another $1.7 million to mitigate the problems.

Both companies have denied any wrongdoing.