The U.S. Environmental Protection Agency, in a Feb. 16 finding about two areas in North Dakota, said the state didn’t adequately take into account certain coal-fired emissions in one of the areas as related to the SO2 NAAQS program, but that didn’t throw the area into the dreaded nonattainment category at this time.
Under section 107(d) of the Clean Air Act (CAA), EPA must designate areas as either “unclassifiable,” “attainment,” or “nonattainment” for the 2010 one-hour sulfur dioxide (SO2) primary national ambient air quality standard (NAAQS). The CAA defines a nonattainment area as one that does not meet the NAAQS or that contributes to a violation in a nearby area. An attainment area is defined as any area other than a nonattainment area that meets the NAAQS. Unclassifiable areas are defined as those that cannot be classified on the basis of available information as meeting or not meeting the NAAQS.
North Dakota submitted updated recommendations to EPA in September 2015, ahead of a July 2, 2016, deadline for the EPA to designate certain areas around the country established by the U.S. District Court for the Northern District of California. That ruling came in an environmental group lawsuit. This deadline is the first of three deadlines established by the court for the EPA to complete area designations for the 2010 SO2 NAAQS. EPA sent a Feb. 16 letter and supporting technical analysis to the state advising the state of the agency’s preliminary decision ahead of the July 2 deadline.
The southern portion of McLean County contains a stationary source that according to the EPA’s Air Markets Database emitted in 2012 either more than 16,000 tons of SO2 or more than 2,600 tons of SO2 and had an annual average emission rate of at least 0.45 pounds of SO2 per one million British thermal units (lbs SO2/mmBTU). As of March 2, 2015, this stationary source had not met the specific requirements for being “announced for retirement,” which would exempt it from this process. Specifically, in 2012, the Coal Creek Station emitted 16,273 tons of SO2, and had an emissions rate of 0.34 lbs SO2/mmBTU.
On the eastern border of Mercer County, about 16.5 kilometers southwest of the Coal Creek facility is a stationary source that according to the EPA’s Air Markets Database emitted in 2012 more than 16,000 tons of SO2 and more than 2,600 tons of SO2 and had an annual average emission rate of at least 0.45 pounds of SO2 per one million lbs SO2/mmBTU. As of March 2, 2015, this stationary source had also not met the specific requirements for being “announced for retirement.” In 2012, the Leland Olds Station emitted 38,323 tons of SO2, and had an emissions rate of 2.06 lbs SO2/mmBTU.
In its submission, North Dakota recommended that the area surrounding both the Coal Creek and Leland Olds stations be designated as attainment. Said EPA: “After careful review of the State’s assessment, supporting documentation, and all available data, the EPA does not agree with the State’s recommendation for the combined area because the Leland Olds allowable emissions rate was not adequately adjusted to account for the 2010 SO2 NAAQS, and therefore intends to designate the area as unclassifiable.”
The Coal Creek Station is located in central North Dakota in the southern portion of McLean County. The Leland Olds Station is located in central North Dakota near the eastern border of Mercer County.
EPA separately assessed emissions for the central portion of Mercer County, which contains another stationary source. In 2012, the Coyote Station emitted 10,639 tons of SO2, and had an emissions rate of 0.79 lbs SO2/mmBTU.
In its submission, North Dakota recommended that the area surrounding the Coyote Station be designated as attainment. The EPA agreed that the area is attaining the NAAQS, and intends to designate it as unclassifiable/attainment.
All three of these power plants are fired with locally-mined lignite. The 1,100-MW Coal Creek plant is operated by Great River Energy. The 669-MW Leland Olds plant is operated by Basin Electric Power Cooperative. And the 427-MW Coyote Station is operated by Otter Tail Power.