The U.S. Environmental Protection Agency on Feb. 16 offered preliminary findings to the state of Ohio on SO2 NAAQS-compliance in two areas along the Ohio River Valley with a heavy (though not as heavy as before) concentration of coal-fired power plants.
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). A nonattainment area does not meet the NAAQS or 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 cannot be classified on the basis of available information as meeting or not meeting the NAAQS.
Ohio submitted updated recommendations to EPA in September 2015, ahead of a July 2, 2016, deadline for EPA to designate certain areas around the country in various states established by the U.S. District Court for the Northern District of California as the result of an environmental group lawsuit. This deadline is the first of three deadlines established by the court for EPA to complete area designations for the 2010 SO2 NAAQS. EPA on Feb. 16 sent Ohio a letter and supporting technical review with its preliminary decisions about the two affected areas in Ohio.
Clermont County (Zimmer power plant)
Clermont County contains a stationary source that according to 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 exclude it from consideration.
In 2012, the 1,300-MW W.H. Zimmer Generating Station, owned by several parties including American Electric Power and operated by co-owner Dynegy, emitted 11,975 tons of SO2, and had an emissions rate of 0.53 lbs SO2/MMBTU.
In its submission, Ohio recommended that the area surrounding Zimmer, specifically all townships in Clermont County with the exception of Pierce Township, be designated as attainment. Pierce Township was designated nonattainment for the 2010 SO2 NAAQS in 2013. This township included a major source (the coal-fired Beckjord Generating Stations) that was subsequently shut down in 2014. Ohio has addressed this township separately, notably by submitting a redesignation request in August 2015 for this township, and EPA will be addressing this township separately.
EPA also noted that the coal-fired Miami Fort Power Station permanently stopped using its Unit 6 in June 2015. Although the plant’s other SO2 emitting units still operate, preliminary 2015 data from EPA’s Air Markets Database shows that Miami Fort emitted 14,239 tons per year (tpy) in 2015, which is about half of its 2014 emissions.
“After careful evaluation of the state’s recommendation and supporting information, as well as all available relevant information, EPA intends to designate Ohio’s recommended townships in Clermont County, Ohio as unclassifiable/attainment for the 2010 SO2 NAAQS,” said the agency.
Gallia County (Gavin power plant)
In 2012, American Electric Power’s 2,670-MW General James M. Gavin Power Plant emitted 31,269 tons of SO2, and its emissions rate was 0.36 lbs SO2/MMBTU.
In its submission, Ohio recommended that the area surrounding Gavin, specifically Gallia County and a portion of Meigs County which contains the SO2 monitor, be designated as attainment. “After careful review of the state’s assessment, supporting documentation, and all available data, EPA finds that due to a discrepancy in the state’s analysis, the area cannot be designated attainment at this time, but the evidence does not fully support a designation of nonattainment,” said the agency. “Therefore, EPA intends to designate Gallia County and a portion of Meigs County as unclassifiable.”
The state evaluated other SO2 sources located within 50 kilometers of the area of analysis, EPA noted. The coal-fired Phillip Sporn and Mountaineer power stations of AEP were covered. The Sporn station closed in June 2015. The predominant winds from the southwest, as measured at Huntington, W.Va, would disperse the emissions of the Mountaineer plant in West Virginia, just across the Ohio River from Meigs County, toward the eastern portion of Meigs County (not included in Ohio’s designation recommendation). There are no other significant sources of SO2 in or near Gallia and Meigs counties. Only Gavin and the coal-fired Kyger Creek power plant were determined by the state to have the potential to cause significant concentration gradient impacts within the area of analysis.
In September 2015, the Sierra Club submitted a modeling analysis for the area surrounding Gavin. This analysis indicated a violation of the NAAQS. In a November 2015 letter to EPA, Ohio commented that the Sierra Club analysis used an inaccurate stack configuration for Kyger Creek, with incorrect hourly emissions and stack parameter information for both Gavin and Kyger Creek. An additional source was modeled with overly conservative emissions data. These errors have the potential to cause significant misrepresentations of the impacts of these sources, such that EPA does not consider the Sierra Club’s modeling to provide a reliable assessment of whether the area is violation the NAAQS. EPA, as mentioned, also does not consider Ohio’s analysis to be a reliable assessment of concentrations in the area. Since the deficiencies in the two analyses are different, the Sierra Club analysis does not provide a reliable indication, even in combination with the state’s analysis, as to whether the area is attaining the NAAQS.
Due to the use of the computerized AERMOD beta option LOWWIND3, which cannot be approved at this time, EPA does not find Ohio’s modeled analysis demonstrating attainment in the Gallia County area to be a reliable assessment of whether the area is attaining the standard. EPA intends to designate the area recommended by Ohio as unclassifiable. While a monitor that is 13 kilometers from Gavin indicates attainment at its location, this monitor provides little basis for determining whether areas closer to the major facilities in this area are attaining the NAAQS. Consistent with the conditions in the March 2015 court-ordered schedule, EPA will evaluate and designate all remaining undesignated areas in Ohio by either Dec. 31, 2017, or Dec. 31, 2020.