Coal-fired Power Plant Settlement Requires SCR Retrofit

The owner and operator of a coal-fired power plant in St. Johns, Ariz., has agreed to install pollution controls at an estimated cost of $400 million to reduce harmful emissions and pay a $950,000 civil penalty, according to an Aug. 12 press release from the U.S. Environmental Protection Agency and U.S. Department of Justice.

The settlement resolves alleged violations of the New Source Review requirements of the Clean Air Act.

The Salt River Project Agricultural Improvement and Power District (SRP) has agreed to install and operate new pollution control equipment on both generating units at its Coronado Generating Station. The controls will reduce combined emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) by over 21,000 tons each year.

SRP will install flue gas desulfurization devices, known as scrubbers, to control SO2 at both units and selective catalytic reduction (SCR) controls to limit NOx at one of the units. This is the first settlement ever to secure an SCR retrofit of an existing coal-fired electric generating unit in the Western United States.

"The reductions in harmful emissions secured by this settlement are substantial and will have a beneficial impact on air quality in Arizona and downwind areas," said Ronald J. Tenpas, assistant attorney general for the Justice Department's Environment and Natural Resources Division. "SRP's willingness to settle rather than litigate the various issues in this case allowed the parties to focus their efforts on securing the best results for the environment. The Justice Department will continue our efforts to pursue emission reductions from power plants across the country to achieve the benefits envisioned by the Clean Air Act."

SRP also will spend $4 million on environmentally beneficial projects to reduce air emissions and mitigate the impacts of the alleged violations. The projects include the following: • retrofit public school bus diesel engines in the Phoenix metropolitan area with pollution control equipment; • install solar photovoltaic panels on school buildings in Arizona and fund the maintenance of the panels for at least 10 years; • offer incentives to residential homeowners, such as rebates, toward the replacement of pre-1988 wood stoves with cleaner burning, energy-efficient stoves or hearth appliances.

In a complaint that the government filed concurrently with lodging this consent decree, the agencies alleged that the utility illegally modified the two units at the plant, thereby increasing air pollution. Specifically, the government cited the utility for failing to obtain necessary pre-construction permits and install required pollution control equipment.

The proposed consent decree will be lodged with the U.S. District Court for the District of Arizona, and will be subject to a 30-day public comment period. For more information, visit

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