Until the Tennessee Valley Authority can get new SO2 scrubbers operating and included in federal enforceable documentation, the U.S. Environmental Protection Agency has decided on a preliminary basis to fail the area around the plant for attainment of its SO2 NAAQS standards.
EPA on Feb. 16 sent out letters to various states about a round preliminary decisions being made about attainment in specific areas of those states. 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.
Tennessee submitted updated recommendations in September 2015, and an updated submission in October 2015, ahead of a July 2, 2016, deadline for the EPA to designate certain areas. This deadline established by the U.S. District Court for the Northern District of California is the first of three deadlines established by the court for the EPA to complete area designations for the 2010 SO2 NAAQS.
Sumner County, Tennessee, 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 lbs SO2/mmBTU. As of March 2, 2015, this stationary source had not met the specific requirements for being “announced for retirement,” whiich would cause to be excluded.
Specifically, in 2012, TVA’s coal-fired Gallatin Power Plant (TVA Gallatin) emitted 21,731 tons of SO2 and had an emissions rate of 0.62 lbs SO2/mmBTU. Pursuant to the March 2, 2015, court-ordered schedule, the EPA must designate the area surrounding the facility by July 2, 2016.
In its submission, Tennessee recommended that the area surrounding TVA Gallatin, specifically the 50 kilometer (km) radius of the facility, be designated as attainment based on an assessment and characterization of air quality from TVA Gallatin and other nearby sources which may have a potential impact in the area of analysis where maximum concentrations of SO2 are expected. This boundary represents 12 whole and partial counties. This assessment and characterization was performed using air dispersion modeling software, i.e., 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 modeling analysis because it does not use the necessary technical information and approach to determine if the area is meeting the SO2 NAAQS,” said EPA’s technical document supporting its Feb. 16 preliminary decision. “Specifically, the EPA reviewed two scenarios that Tennessee provided in its submission and does not believe that either of these scenarios were performed consistent with the Modeling TAD or the EPA guidance on modeling for the SO2 NAAQS. One scenario involved the consideration of TVA Gallatin’s 2012-2014 actual emissions whereas the other scenario involved the consideration of future allowable potential to emit (PTE) emission limits based on installation of SO2 controls. The latter scenario is the basis for Tennessee’s attainment designation recommendation.
“The EPA has identified input errors for Tennessee’s modeling analysis, and areas where further refinements of the modeling are necessary to be most consistent with the modeling approaches found in the Modeling TAD and the EPA guidance. Therefore, the EPA intends to designate Sumner County in its entirety as unclassifiable. The remainder of the counties recommended by the state as attainment, in addition to any remaining undesignated area of Tennessee, will be addressed by either December 31, 2017, or December 31, 2020, consistent with the deadlines in the final consent decree.
“The EPA notes that the future allowable emission rates modeled for the Sumner County Area (and which the state uses to support its attainment recommendation) have not yet been established as federally-enforceable by the state of Tennessee. It is for this reason as well, that the EPA intends to designate Sumner County as unclassifiable.
“In order for the EPA to consider the future allowable emission limit for TVA Gallatin for the designations to be finalized no later than July 2, 2016, the state will have to ensure that these limits are federally-enforceable (and the EPA has confirmed such) by the time this round of designations is complete. Regarding the TVA Gallatin future emission limit, if a limit with an averaging time longer than 1-hour is desired, supporting technical information will also need to include explanation, of whether the longer term average limit, that the EPA determines is comparatively stringent to a 1-hour limit at the critical emission value, ensures attainment of the SO2 NAAQS.
“According to an April 14, 2011, TVA Federal Facilities Compliance Agreement (FFCA) , all TVA units are limited to a system-wide annual tonnage limitations for SO2. This consent decree requires TVA Gallatin to install and commence continuous operations of SO2 controls (e.g., flue gas desulfurization (FGD), renewable biomass, repower, or retirement) for units 1-4 no later than December 31, 2017. In its September 16, 2015 designation recommendation, Tennessee indicated that TVA Gallatin was installing FGD on two of the four coal-fired units to comply with the TVA agreement and expected the control upgrades to be complete and operational by April 16, 2016. Tennessee specified that currently two FGD systems are already on-line and operating. Tennessee stated that enforceable emission limits associated with these control upgrades are expected to be included in TVA Gallatin’s title V permit by April 8, 2016.
“On October 30, 2015, Tennessee supplemented their recommendation to include a technical analysis to support their September 16, 2015 recommendation of attainment, including a modeling demonstration indicating that FGD on unit 4 was operational and that control of the remaining three units would be completed by April 2016. In January 2016, Tennessee provided additional information to support the state’s recommendation. The EPA has not yet had time to complete a full review of this information but will consider it prior to finalizing designations. If the state provides additional information prior to promulgation of final designations, the EPA will consider this information in our final designation for the Sumner County Area.”