Final Technical Support Document
Kentucky
Area Designations for the 2010 SO2 Primary National Ambient Air Quality Standard
Summary
Pursuant to section 107(d) of the Clean Air Act (CAA), the U.S. Environmental Protection
Agency (EPA, or the Agency) must designate areas as either "unclassifiable," "attainment," or
"nonattainment" for the 2010 1-hour sulfur dioxide (SO2) primary national ambient air quality
standard (NAAQS). Section 107(d) of the CAA defines a nonattainment area as one that does not
meet the NAAQS or that contributes to a NAAQS violation in a nearby area, an attainment area
as any area other than a nonattainment area that meets the NAAQS, and an unclassifiable area as
any area that cannot be classified on the basis of available information as meeting or not meeting
the NAAQS.
July 2, 2016, is the deadline established by the U.S. District Court for the Northern District of
California for the EPA to designate certain areas. This deadline is the first of three deadlines
established by the court for the EPA to complete area designations for the 2010 SO2 NAAQS.
This deadline applies to certain areas in Kentucky (Commonwealth) because two emission
sources meet the conditions of the court's order.
Kentucky submitted updated recommendations on September 16, 2015. Table 1 below lists
Kentucky's recommendations and identifies the counties in Kentucky that the EPA is designating
in order to meet the July 2, 2016 court-ordered deadline. These final designations are based on an
assessment and characterization of air quality through ambient air quality data, air dispersion
modeling, other evidence and supporting information, or a combination of the above.
Table 1 - Kentuc
ty's Recommended and the EPA's Final Designations
Area
State's
Recommended
Area Definition
State's
Recommended
Designation
The EPA's Final
Area Definition
The EPA's
Final
Designation
Ohio County,
KY
Ohio County in its
entirety
Attainment
Same as
Commonwealth's
Recommendation
(Ohio County, KY)
Unclassifiable
Pulaski County,
KY
Pulaski County in
its entirety
Attainment
Same as
Commonwealth's
Recommendation
(Pulaski County,
KY)
Unclassifiable
Background
On June 3, 2010, the EPA revised the primary (health based) SO2 NAAQS by establishing a new
1-hour standard at a level of 75 parts per billion (ppb) which is met at an ambient air quality
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monitoring site when the 3-year average of the 99th percentile of 1-hour daily maximum
concentrations does not exceed 75 ppb. This NAAQS was published in the Federal Register on
June 22, 2010 (75 FR 35520), and is codified at 40 CFR 50.17. The EPA determined this is the
level necessary to protect public health with an adequate margin of safety, especially for
children, the elderly, and those with asthma. These groups are particularly susceptible to the
health effects associated with breathing SO2. The two prior primary standards of 140 ppb
evaluated over 24 hours, and 30 ppb evaluated over an entire year, codified at 40 CFR 50.4,
remain applicable.1 However, the EPA is not currently designating areas on the basis of either of
these two primary standards. Similarly, the secondary standard for SO2, set at 500 ppb evaluated
over 3 hours, codified at 40 CFR 50.5, has not been revised, and the EPA is also not currently
designating areas on the basis of the secondary standard.
General Approach and Schedule
Section 107(d) of the CAA requires that not later than 1 year after promulgation of a new or
revised NAAQS, state governors must submit their recommendations for designations and
boundaries to the EPA. Section 107(d) also requires the EPA to provide notification to states no
less than 120 days prior to promulgating an initial area designation that is a modification of a
state's recommendation. If a state does not submit designation recommendations, the EPA may
promulgate the designations that it deems appropriate without prior notification to the state,
although it is our intention to provide such notification when possible. If a state or tribe disagrees
with the EPA's intended designations, it is given an opportunity within the 120-day period to
demonstrate why any proposed modification is inappropriate. The EPA is required to complete
designations within 2 years after promulgation of a new or revised NAAQS, unless the EPA
determines that sufficient information is not available, in which case the deadline is extended to
3 years. The 3-year deadline for the revised SO2 NAAQS was June 2, 2013.
On August 5, 2013, the EPA published a final rule establishing air quality designations for 29
areas in the United States for the 2010 SO2 NAAQS, based on recorded air quality monitoring
data from 2009 - 2011 showing violations of the NAAQS (78 FR 47191). In that rulemaking, the
EPA committed to address, in separate future actions, the designations for all other areas for
which the Agency was not yet prepared to issue designations. The EPA designated a portion of
Campbell and Jefferson Counties in Kentucky as nonattainment in this initial set of designations.
Following the initial August 5, 2013, designations, three lawsuits were filed against the EPA in
different U.S. District Courts, alleging the Agency had failed to perform a nondiscretionary duty
under the CAA by not designating all portions of the country by the June 2, 2013 deadline. In an
effort intended to resolve the litigation in one of those cases, plaintiffs Sierra Club and the
Natural Resources Defense Council and the EPA filed a proposed consent decree with the U.S.
District Court for the Northern District of California. On March 2, 2015, the court entered the
1 40 CFR 50.4(e) provides that the two prior primary NAAQS will no longer apply to an area 1 year after its
designation under the 2010 NAAQS, except that for areas designated nonattainment under the prior NAAQS as of
August 22, 2010, and areas not meeting the requirements of a SIP Call under the prior NAAQS, the prior NAAQS
will apply until that area submits and the EPA approves a SIP providing for attainment of the 2010 NAAQS. The
two Kentucky areas are not designated nonattainment under the prior NAAQS nor are they areas not meeting the
requirements of a SIP Call under the prior NAAQS.
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consent decree and issued an enforceable order for the EPA to complete the area designations
according to the court-ordered schedule.
According to the court-ordered schedule, the EPA must complete the remaining designations by
three specific deadlines. By no later than July 2, 2016 (16 months from the court's order), the
EPA must designate two groups of areas: (1) areas that have newly monitored violations of the
2010 SO2NAAQS and (2) areas that contain any stationary sources that had not been announced
as of March 2, 2015, for retirement and that according to the EPA's Air Markets Database
emitted in 2012 either (i) more than 16,000 tons of SO2 or (ii) more than 2,600 tons of SO2 with
an annual average emission rate of at least 0.45 pounds of SO2 per one million British thermal
units (lbs S02/mmBTU). Specifically, a stationary source with a coal-fired unit that as of January
1, 2010, had a capacity of over 5 megawatts and otherwise meets the emissions criteria, is
excluded from the July 2, 2016, deadline if it had announced through a company public
announcement, public utilities commission filing, consent decree, public legal settlement, final
state or federal permit filing, or other similar means of communication, by March 2, 2015, that it
will cease burning coal at that unit.
The last two deadlines for completing remaining designations are December 31, 2017, and
December 31, 2020. The EPA has separately promulgated requirements for state and other air
agencies to provide additional monitoring or modeling information on a timetable consistent with
these designation deadlines. We expect this information to become available in time to help
inform these subsequent designations. These requirements were promulgated on August 21, 2015
(80 FR 51052), in a rule known as the SO2 Data Requirements Rule (DRR), codified at 40 CFR
part 51 subpart BB.
Updated designations guidance was issued by the EPA through a March 20, 2015 memorandum
from Stephen D. Page, Director, U.S. EPA, Office of Air Quality Planning and Standards, to Air
Division Directors, U.S. EPA Regions 1-10. This memorandum supersedes earlier designation
guidance for the 2010 SO2 NAAQS, issued on March 24, 2011, and it identifies factors that the
EPA intends to evaluate in determining whether areas are in violation of the 2010 SO2 NAAQS.
The guidance also contains the factors the EPA intends to evaluate in determining the boundaries
for all remaining areas in the country, consistent with the court's order and schedule. These
factors include: 1) Air quality characterization via ambient monitoring or dispersion modeling
results; 2) Emissions-related data; 3) Meteorology; 4) Geography and topography; and 5)
Jurisdictional boundaries. This guidance was supplemented by two non-binding technical
assistance documents intended to assist states and other interested parties in their efforts to
characterize air quality through air dispersion modeling or ambient air quality monitoring for
sources that emit SO2. Notably, the EPA's documents titled, "SO2 NAAQS Designations
Modeling Technical Assistance Document" (Modeling TAD) and "SO2 NAAQS Designations
Source-Oriented Monitoring Technical Assistance Document" (Monitoring TAD), were
available to states and other interested parties. Both of these TADs were most recently updated in
February 2016.
Based on complete, quality assured and certified ambient air quality data collected between 2013
and 2015, no violations of the 2010 SO2 NAAQS have been recorded at ambient air quality
monitors in any undesignated part of Kentucky. However, there are two sources in the state
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meeting the emissions criteria of the consent decree for which the EPA must complete
designations by July 2, 2016. In this final technical support document, the EPA discusses its
review and technical analysis of Kentucky's updated recommendations for the areas that we
must designate. The EPA also discusses any intended and final modifications from the state's
recommendation based on all available data before us.
The following are definitions of important terms used in this document:
1)	2010 SO2 NAAQS - the primary NAAQS for SO2 promulgated in 2010. This NAAQS is
75 ppb, based on the 3-year average of the 99th percentile of the annual distribution of
daily maximum 1-hour average concentrations. See 40 CFR 50.17.
2)	Attaining monitor - an ambient air monitor meeting all methods, quality assurance, and
siting criteria and requirements whose valid design value is equal to or less than 75 ppb,
based on data analysis conducted in accordance with Appendix T of 40 CFR part 50.
3)	Design Value - a statistic computed according to the data handling procedures of the
NAAQS (in 40 CFR part 50 Appendix T) that, by comparison to the level of the NAAQS,
indicates whether the area is violating the NAAQS.
4)	Designated nonattainment area - an area which the EPA has determined has violated the
2010 SO2 NAAQS or contributed to a violation in a nearby area. A nonattainment
designation reflects considerations of the state's recommendations and all of the
information discussed in this document. The EPA's decision is based on all available
information including the most recent 3 years of air quality monitoring data, available
modeling analyses, and any other relevant information.
5)	Designated unclassifiable area - an area for which the EPA cannot determine based on all
available information whether or not it meets the 2010 SO2 NAAQS.
6)	Designated unclassifiable/attainment area - an area which the EPA has determined to
have sufficient evidence to find either is attaining or is likely to be attaining the NAAQS.
The EPA's decision is based on all available information including the most recent 3
years of air quality monitoring data, available modeling analyses, and any other relevant
information.
7)	Modeled violation - a violation based on air dispersion modeling.
8)	Recommended attainment area - an area a state or tribe has recommended that the EPA
designate as attainment.
9)	Recommended nonattainment area - an area a state or tribe has recommended that the
EPA designate as nonattainment.
10)	Recommended unclassifiable area - an area a state or tribe has recommended that the
EPA designate as unclassifiable.
11)	Recommended unclassifiable/attainment area - an area a state or tribe has recommended
that the EPA designate as unclassifiable/attainment.
12)	Violating monitor - an ambient air monitor meeting all methods, quality assurance, and
siting criteria and requirements whose valid design value exceeds 75 ppb, based on data
analysis conducted in accordance with Appendix T of 40 CFR part 50.
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Technical Analysis for Ohio County, Kentucky Area
Introduction
The Ohio County, KY, area contains one 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 S02per one million
British thermal units (lbs S02/mmBTU). Specifically, in 2012, the D. B. Wilson electric
generating facility (Plant Wilson) emitted 7,387 tons of SO2 and had an emissions rate of 0.45
lbs S02/mmBTU. 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 Commonwealth of Kentucky recommended that the area surrounding Plant
Wilson electric generating facility, specifically Ohio 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 potential to emit (PTE) emissions.
On February 16, 2016, the EPA notified Kentucky that we intended to designate the Ohio
County, KY area as unclassifiable, based on our view that available information did not enable
us to determine whether the area is meeting the NAAQS. Additionally, we informed the
Commonwealth that our intended boundaries for the unclassifiable area consisted of Ohio
County. Our intended designation and associated boundaries were based on, among other things,
Plant Wilson's future allowable limit was not yet federally-enforceable and there was no
indication of an SO2 emissions limit consisting of a 1-hour averaging time or a comparatively
stringent longer term averaging period, as well as uncertainty surrounding the shutdown of the
nearby source Tennessee Valley Authority (TVA) Paradise Station Units 1 and 2. Detailed
rationale, analyses, and other information supporting our intended designation for this area can
be found in the preliminary technical support document for Kentucky, and this document along
with all others related to this rulemaking can be found in Docket ID EPA-HQ-OAR-2014-0464.
Assessment of New Information
In our February 16, 2016, notification to Kentucky regarding our intended unclassifiable
designation for the Ohio County, KY area, the EPA requested that any additional information
that the Agency should consider prior to finalizing the designation should be submitted by April
19, 2016. On March 1, 2016, the EPA also published a notice of availability and public comment
period in the Federal Register, inviting the public to review and provide input on our intended
designations by March 31, 2016 (81 FR 10563).
The EPA is explicitly incorporating and relying upon the analyses and information presented in
the preliminary technical support document for the purposes of our final designation of
unclassifiable for this area, except to the extent that any new information submitted to the EPA
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or conclusions presented in this final technical support document and our response to comments
document (RTC), available in the docket, supersede those found in the preliminary document.
The EPA received additional information from Kentucky on March 2, 2016, and April 18, 2016,
for consideration regarding our intended designations of this area. The March 2, 2016, submittal
included revised modeling and an explanation regarding establishment of the new allowable SO2
emission limit using a 30-day rolling average for the Wilson Plant. The April 18, 2016, submittal
included information on the TVA Paradise Fossil Plant nearby source in Muhlenberg County,
Kentucky, and a preliminary proposed title V permit establishing a new allowable PTE limit of
0.627 lbs SCh/mmBTU on a 30-day rolling average to support the recommended attainment
designation for Ohio County for the SO2 NAAQS.
Kentucky's original attainment designation recommendation for the entirety of Ohio County was
based on Plant Wilson's air dispersion modeling analysis which considered a future allowable
emission limit of 0.85 lbs. S02/mmBTU at the facility, actual emissions from the TVA Paradise
Fossil Plant Unit 3 (located just southeast of Plant Wilson in Muhlenberg County), and
background concentrations based on rural and natural background sources as well as regional
impacts from distant large SO2 sources, and assumed that the TVA-Paradise Units 1 and 2 would
be retired. The EPA's February 16, 2016, intended designation's TSD documented issues
regarding the Ohio County, Kentucky, area analysis which resulted in the EPA's February 16,
2016, intended unclassifiable designation. These issues included 1) the federal enforceability of
the new allowable emission limit through an appropriate mechanism by April 19, 2016, ensuring
that if a longer-term averaging time is established it is comparatively stringent to a 1-hour
averaging limit, and 2) uncertainty regarding the shutdown status of units 1 and 2 at the nearby
TVA Paradise Fossil Plant and whether these units 2012-2014 actual SO2 emissions should be
included in the modeling. The EPA indicated that if the Commonwealth resolved these issues
then the Agency would consider revising the intended designation to unclassifiable/attainment.
However, after careful review, the EPA has determined that the Kentucky has not addressed the
specific issues identified in the intended designation.
Kentucky's April 18, 2016, information included a proposed title V permit revision to establish a
new federally enforceable allowable SO2 emission limit of 0.627 lbs S02/mmBTU. On March 2,
2016, Kentucky submitted to the EPA via email information explaining how this new emission
limit was calculated. However, this explanation did not provide detailed calculations on how the
limit was derived, including the actual hourly emissions data used for the calculations. On April
26, 2016, the EPA received the actual proposed title V permit for the allowable SO2 limit for
review initiating the Agency's 45-day review.2 The proposed permit included a condition
stipulating the new allowable limit would only be effective upon final action by the EPA to
designate Ohio County attainment. Additionally, Kentucky indicated that they anticipate issuing
the final permit on or about June 9, 2016. The EPA's February 16, 2016, intended designations
indicated that the EPA would consider an alternative designation to unclassifiable only if the new
allowable emission limit was federally-enforceable and effective prior to final designations. EPA
2 On May 20, 2016, the EPA Region 4 provided comments via letter to the Commonwealth on the proposed April
26, 2016, title V permit revision to establish a new federally enforceable allowable PTE limit of 0.627 lbs
SCh/mmBTU on a 30-day rolling average for Plant Wilson to support attainment recommendation. A copy of this
letter is in the docket for the final designations rulemaking.
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has therefore determined that the preliminary permit, including the condition that it would only
be effective upon a hypothetical future action, is not federally-enforceable. Furthermore,
Kentucky has provided no additional calculations, including actual hourly emissions data,
demonstrating how the limit was determined. Therefore, the 0.627 lbs SCh/mmBTU emission
limit is not federally-enforceable and effective for Plant Wilson, and cannot at this time be relied
upon for modeling of allowable emissions to show that the area is now meeting the NAAQS.
Consequently, the EPA cannot rely upon this information to support a determination of whether
the area is meeting the NAAQS.
Regarding TVA Paradise Units 1 and 2, the Commonwealth noted in the April 18, 2016,
correspondence to the EPA that the facility requested (from the EPA) an Administrative Order of
compliance with the Mercury and Air Toxics Standards to April 16, 2017, to allow all units at
the facility to operate while new natural gas fired combined cycle electricity generating units
were being constructed. EPA's Office of Enforcement and Compliance Assurance granted the
CAA Administrative Order on April 16, 2016. Therefore, all three units at Paradise are currently
operating at least until April 2017. According to Kentucky's September 16, 2015 modeling
report and the revised modeling report submitted on March 2, 2016, TVA Paradise units 1 and 2
actual emissions were excluded from the modeling because both units were scheduled for
retirement by April 2016. The modeling reports included 2012-2014 actual emissions from TVA
Paradise unit 3. Kentucky's April 18, 2016, information did not provide modeling to evaluate
Units 1 and 2 actual emissions nor did the Commonwealth provide an explanation why both
units were excluded from the modeling analysis. Because Kentucky did not consider all three
operating units from TVA Paradise in the modeling analysis, the EPA has determined that it does
not have sufficient information regarding the actual impacts from Plant Paradise to the area
around Plant Wilson and within Ohio County, and therefore cannot accurately and completely
evaluate the modeling analysis provided by the Commonwealth, and cannot fully determine
whether or not the Ohio County area is attaining the NAAQS.
Conclusion
After careful evaluation of all available data and information, the EPA is unable to determine
whether the Ohio County, Kentucky area is meeting or not meeting the 2010 1-hour SO2
NAAQS, and therefore is designating the area as unclassifiable for the 2010 1-hour SO2 NAAQS
because Plant Wilson's 0.627 lbs S02/mmBTU 30-day rolling average future allowable limit has
not been established as federally-enforceable and effective prior to final designation. Also,
adequate documentation has not been provided to demonstrate that the limit is comparatively
stringent to a 1-hour emission limit. Additionally, the EPA cannot confirm the modeled impacts
from the nearby TVA Paradise facility because Kentucky only considered actual emissions from
Unit 3 and excluded Units 1 and 2 from the modeling analysis. The boundary for this
unclassifiable area consists of Ohio County in its entirety, and is shown in the figure below. Also
included in the figure are nearby emitters of SO2 and Kentucky's recommended area.
The EPA finds that the final unclassifiable area, consisting of Ohio County is comprised of a
clearly defined legal boundary, and we find this boundary to be a suitably clear basis for defining
our final unclassifiable area.
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Figure 1: The EPA's final unclassifiable area: Ohio County, KY Area
Ohio County, Kentucky Area
Legend
EPA's final designated Unclassifiable Area(whole county]
^ State Boundary Recommendation
• Consent Decree S02 Source
o S02 Emission Source
0 Attaining Monitor S02 NAAQS (2012-2014)
¦ City
| County Boundary
Ipy: tons peryear
At this time, our final designations for the Commonwealth only applies to the Ohio County area,
and the others contained in this final TSD. Consistent with the court-ordered schedule, the EPA
will evaluate and designate all remaining undesignated areas in Kentucky by either December
31, 2017, or December 31, 2020.
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Technical Analysis for Pulaski County, Kentucky Area
Introduction
The Pulaski County, KY, area contains one 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 SChper one million
British thermal units (lbs SCh/mmBTU). Specifically, in 2012, the John S. Cooper Power Station
electric generating facility (Cooper Station) emitted 7,428 tons of SO2 and had an emissions rate
of 1.07 lbs SCh/mmBTU. Cooper Station is located in the southern portion of Pulaski County
approximately 10 km north of the center of Somerset. 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 Commonwealth of Kentucky recommended that the area surrounding the
Cooper Station electric generating facility, specifically Pulaski 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 2012-2014 actual and
allowable PTE emissions.
On February 16, 2016, the EPA notified Kentucky that we intended to designate the Pulaski
County, Kentucky area as unclassifiable, based on our view that available information did not
support a determination regarding whether the area was meeting the NAAQS. Additionally, we
informed the Commonwealth that our intended boundaries for the unclassifiable area consisted
of Pulaski County. Our intended designation and associated boundaries were based on, among
other things, Cooper Station's modeling for units 1 and 2 using a mix of PTE emissions and
actual emissions, reliance upon a future allowable limit which is not yet federally-enforceable,
and the lack of an SO2 emissions limit with al-hour averaging time or a comparatively stringent
longer term averaging period. Detailed rationale, analyses, and other information supporting our
intended designation for this area can be found in the preliminary technical support document for
Kentucky, and this document along with all others related to this rulemaking can be found in
Docket ID EPA-HQ-0AR-2014-0464.
Assessment of new information
In our February 16, 2016, notification to Kentucky regarding our intended unclassifiable
designation for the Pulaski County, Kentucky area, the EPA requested that any additional
information that the Agency should consider prior to finalizing the designation should be
submitted by April 19, 2016. On March 1, 2016, the EPA also published a notice of availability
and public comment period in the Federal Register, inviting the public to review and provide
input on our intended designations by March 31, 2016 (81 FR 10563).
The EPA is explicitly incorporating and relying upon the analyses and information presented in
the preliminary technical support document for the purposes of our final designation of
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unclassifiable for this area, except to the extent that any new information submitted to the EPA,
our responses, or conclusions presented in this final technical support document supersede those
in the preliminary technical support document.
Subsequent to our February 16, 2016 notification, the EPA received additional information from
Kentucky on May 19, 2016, via email, and April 18, 2016, for consideration regarding our
intended designations of this area. The May 19, 2016, email included an explanation regarding
establishment of the new allowable SO2 emission limit using a 30-day rolling average. The April
18, 2016, submittal included an explanation of the hybrid emission modeling approach for units
1 and 2 (i.e. use of a mix of an allowable emissions for Unit 1 and actual emissions from Unit 2
being emitted from the same stack) based on the installation of a dry flue gas desulfurization
system and a proposed title V permit establishing a new allowable PTE limit of 0.100 lbs
SCh/mmBTU for unit 1 on a 30-day rolling average to support the recommended attainment
designation for Pulaski County for the SO2 NAAQS.
Kentucky's original attainment designation recommendation for the entirety of Pulaski County
was based on Cooper Station's air dispersion modeling analysis which considered a hybrid
approach based on a future allowable emission limit of 0.165 lbs SCh/mmBTU for unit 1 and
hourly emission rate for unit 2, and background concentrations based on rural and natural
background sources as well as regional impacts from distant large SO2 sources. The EPA's
February 16, 2016, intended designations TSD documented issues regarding the Pulaski County,
Kentucky Area analysis which resulted in the EPA's February 16, 2016 intended unclassifiable
designation. Specifically, EPA noted: 1) the modeling approach using a combination of future
PTE and actual emissions for Cooper Station's unit 1 and 2 was inappropriate because the two
units are combined and emitted from a common stack; and 2) the federal-enforceability of the
new allowable emission limit through an appropriate mechanism was needed by April 19, 2016,
and needed to ensure that if a longer-term averaging time is established it is comparatively
stringent to a 1-hour averaging limit. EPA explained in its intended designation TSD that Cooper
Station's hybrid modeling approach was inconsistent with the Modeling TAD's
recommendations and advised that Kentucky could revise their modeling configuration to either
use new future allowable PTE from both units, provided that these new limits were made
federally-enforceable prior to final designations. Alternatively, the EPA advised that Kentucky
could use actual emissions for their modeling from a common 3-year period for both units. After
careful review, the EPA has determined that Kentucky has not addressed the specific issues
identified in the intended designation.
Kentucky's April 18, 2016, information did not include revised modeling based on the EPA's
guidance for units 1 and 2, and therefore the EPA is unable to determine (based on Kentucky's
reliance on the hybrid modeling approach) if the area is meeting or is not meeting the SO2
NAAQS. Additionally, Kentucky's April 16, 2016, submittal included a proposed title V permit
revision to establish a new federally-enforceable allowable SO2 emission limit of 0.100 lbs
SCh/mmBTU for unit 1 based on 30-day rolling average. On May 19, 2016, Kentucky submitted
to the EPA via email information explaining the process by which the new emission limit was
determined. However, the Commonwealth's explanation did not provide detailed calculations on
how the limit was derived including the actual hourly emissions data used for the calculations.
As a result, EPA could not verify how the limits were determined or whether or not they would
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be feasible or ensure attainment of the NAAQS. Kentucky's April 18, 2016, submittal included
the proposed title V permit for the allowable SO2 limit for unit 1 for review.3 The proposed
permit included a condition stipulating the new allowable limit would be effective only upon
final action by the EPA to designate Pulaski County attainment. EPA has therefore determined
that the preliminary permit, including the condition that it would only be effective upon a
hypothetical future action, is not effective prior to this final designation and not federally-
enforceable, and cannot at this time be relied upon for modeling of allowable emissions to show
that the area is now meeting the NAAQS. Consequently, the EPA cannot rely upon this
information to support a determination of whether the area is meeting the NAAQS.
Conclusion
After careful evaluation of all available data and information, the EPA is unable to determine
whether the Pulaski County, Kentucky area is meeting or not meeting the 2010 1-hour SO2
NAAQS, and therefore is designating the area as unclassifiable for the 2010 1-hour SO2 NAAQS
because Cooper Station's 0.100 lbs SCh/mmBTU 30-day rolling average future allowable limit
for unit 1 is not established as federally-enforceable and effective prior to final designations.
Also, there is no indication the limit is comparatively stringent to a 1-hour emission limit.
Additionally, the EPA cannot confirm whether the area within the vicinity of the Cooper Station
and Pulaski County are meeting or not meeting the NAAQS due to Kentucky's hybrid modeling
approach. The boundary for this unclassifiable area consists of Pulaski County in its entirety, and
is shown in the figure below. Also included in the figure are nearby emitters of SO2 and
Kentucky's recommended area.
The EPA finds that our final unclassifiable area, consisting of Pulaski County is comprised of a
clearly defined legal boundary, and we find this boundary to be a suitably clear basis for defining
our final unclassifiable area.
3 EPA notes the proposed title V permit revision was submitted as an attachment to the Commonwealth's April 18,
2016 information, but was actually provided to EPA on April 14, 2016, initiating the 45-day review period. On May
20, 2016, the EPA Region 4 provided comments via letter to the Commonwealth on the proposed April 26, 2016
title v permit revision to establish a new federally enforceable allowable PTE limit of 0.100 lbs SCh/mmBTU on a
30-day rolling average for Cooper Station to support attainment recommendation. A copy of this letter is in the
docket for the final designations rulemaking.
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Figure 2: The EPA's final unclassifiable area: Pulaski County, KY Area
Pulaski County, Kentucky Area
At this time, our final designations for the Commonwealth only applies to the Pulaski County
area, and the others contained in this final TSD. Consistent with the court-ordered schedule, the
EPA will evaluate and designate all remaining undesignated areas in Kentucky by either
December 31, 2017, or December 31, 2020.
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