Entergy‘s White Bluff coal plant in Arkansas has dodged a preliminary bullet, with the U.S. Environmental Protection Agency deciding that the area around it can meet the SO2 NAAQS.
In recent days, EPA has been sending out letters to various states, with the one to Arkansas dated Feb. 11. 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.
Arkansas submitted updated recommendations in September 2015, ahead of a July 2, 2016, deadline for the EPA to designate certain areas in various states as 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.
The Jefferson County, Arkansas, 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). As of March 2, 2015, this stationary source had not met the specific requirements for being “announced for retirement,” which exclude it from consideration.
Specifically, in 2012, Entergy’s coal-fired White Bluff Steam Electric Station emitted 31,687 tons of SO2, and had an emissions rate of 0.59 lbs SO2/mmBTU. Pursuant to the March 2, 2015 consent decree, the EPA must designate the area surrounding the facility by July 2, 2016.
In its submission, Arkansas recommended that the area surrounding White Bluff station, specifically the entirety of Jefferson County, be designated as unclassifiable/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, i.e., AERMOD, analyzing actual emissions.
Said an EPA technical document: “After careful review of the state’s assessment, supporting documentation, and all available data, the EPA agrees that the area is attaining the standard, and intends to designate Jefferson County as unclassifiable/attainment.”
There are two boilers in operation at the White Bluff station, Unit 1 and Unit 2. Units 1 and 2 are vented to a common, dual-flue stack. For these main units, three years (2012-2014) of actual hourly emissions, stack temperature, and exhaust flow rate data were input into the model. This emissions data was provided by Entergy from prior submittals to the EPA’s Clean Air Markets Database, while temperature and exhaust flow rates were provided by Entergy from the facility’s CEM system.