The U.S. Environmental Protection Agency, in a Feb. 16 preliminary decision, has kind of made a non-decision about whether the area around MidAmerican Energy‘s George Neal South coal plant is in attainment under the SO2 NAAQS program.
Under section 107(d) of the Clean Air Act (CAA), EPA must designate areas as either “unclassifiable,” “attainment,” or “nonattainment” for the 2010 1-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 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.
July 2 of this year is the deadline for the EPA to designate for SO2 NAAQS purposes certain areas established by the U.S. District Court for the Northern District of California in a lawsuit brought by environmental groups. This deadline is the first of three deadlines established by the court for the EPA to complete area designations for the 2010 SO2 NAAQS.
On Feb. 16, EPA sent a letter and supporting technical document to the state of Iowa giving its preliminary decision. The Iowa Department of Natural Resources (IDNR) submitted updated recommendations in September 2015.
Said the supporting technical document from EPA: “After careful evaluation of the state’s recommendation and supporting information, as well as all available relevant information, the EPA intends to designate an area around MidAmerican Energy George Neal South Generating Facility as unclassifiable for the 2010 SO2 NAAQS. Specifically, the area is comprised of the entirety of Woodbury County, Iowa. The unclassifiable designation is based on the fact that although IDNR provided modeling to the EPA that demonstrated attainment for the area, some emission limits used by IDNR in this modeling analysis are not currently federally enforceable.
“The Woodbury County, Iowa, area 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). Specifically, in 2012, the MidAmerican Energy Company’s George Neal South electric generating facility emitted 14,272 tons of SO2 and had an emissions rate of 0.638 lbs SO2/mmBTU. As of March 2, 2015, this stationary source had not met the specific requirements for being ‘announced for retirement.’ Pursuant to the March 2, 2015 court-ordered schedule, the EPA must designate the area surrounding this facility by July 2, 2016.
“In its submission, the Iowa Department of Natural Resources (IDNR) recommended that the area surrounding MidAmerican Energy Company’s George Neal South electric generating facility, specifically the entirety of Woodbury County, be designated as attainment based on an assessment and characterization of air quality from the facility and other nearby sources which may have a potential impact in the area of analysis where maximum concentrations of SO2 are expected. This assessment and characterization was performed using air dispersion modeling software, specifically using AERMOD, analyzing allowable emissions. 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 area and intends to designate the area, i.e., Woodbury County, as unclassifiable.”
George Neal South is operated by MidAmerican Energy and is located in western Iowa in the western portion of Woodbury County. MidAmerican also operates the nearby George Neal North coal-fired facility.
In 2014, MidAmerican installed SO2 scrubbers on George Neal South Unit 4 and George Neal North Unit 3. The corresponding permitted emission limit after the installations was based on a 30‐day rolling average of 2,760 lb/hr and 2,200 lb/hr for George Neal South Unit 4 and George Neal North Unit 3, respectively. IDNR performed an evaluation of these 30‐day average rolling permit limits for both emission units to develop a critical 1-hour emission rate which would preserve the variability of the hour‐to‐hour emission profile with scrubber controls, yet be conservative so as to protect the ambient air quality standard for the attainment demonstration. IDNR reviewed CEMS data for similar MidAmerican emission units with similar control technology to establish an appropriate emission rate for modeling George Neal South Unit 4 and George Neal North Unit 3. INDR used Walter Scott, Jr. Energy Center Unit 3 and Louisa Generating Station coal-fired boilers as surrogate units to George Neal South Unit 4 and George Neal North Unit 3.
Another approach was used by the IDNR for George Neal North Units 1 and 2. IDNR used potential to emit limits for SO2 based on a consent decree between MidAmerican and the Sierra Club that requires the two units to cease combusting coal and switch to natural gas only by April 16, 2016. However, the consent agreement between MidAmerican and the Sierra Club is not federally enforceable, EPA noted, meaning the agency can’t consider it in this decision at this time.