[Federal Register Volume 83, Number 81 (Thursday, April 26, 2018)]
[Proposed Rules]
[Pages 18243-18248]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-08622]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R08-OAR-2018-0015; FRL-9976-45--Region 8]
Approval and Promulgation of Air Quality Implementation Plans;
Colorado; Regional Haze State Implementation Plan
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve a State Implementation Plan (SIP) revision submitted by the
State of Colorado on May 26, 2017, addressing regional haze. The EPA is
proposing to approve source-specific revisions to the nitrogen oxides
(NOX) best available retrofit technology (BART)
determination for Craig Station Unit 1. This unit is owned in part and
operated by Tri-State Generation & Transmission Association, Inc. (Tri-
State). We are also proposing to approve revisions to the
NOX reasonable progress determination for Tri-State's Nucla
Station. The EPA is taking this action pursuant to section 110 of the
Clean Air Act (CAA).
DATES: Comments: Written comments must be received on or before May 29,
2018.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2018-0015, to the Federal Rulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
www.regulations.gov. The EPA may publish any comment received to its
public docket. Do not submit electronically any information you
consider to be Confidential Business Information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in www.regulations.gov or in hard copy at the Air Program,
Environmental Protection Agency (EPA), Region 8, 1595 Wynkoop Street,
Denver, Colorado 80202-1129. The EPA requests that if at all possible,
you contact the individual listed in the FOR FURTHER INFORMATION
CONTACT section to view the hard copy of the docket. You may view the
hard copy of the docket Monday through Friday, 8:00 a.m. to 4:00 p.m.,
excluding federal holidays.
FOR FURTHER INFORMATION CONTACT: Jaslyn Dobrahner, Air Program, EPA,
Region 8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado, 80202-
1129, (303) 312-6252, [email protected].
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean the EPA.
Table of Contents
I. What action is the EPA taking?
II. Background
A. Requirements of the Clean Air Act and the EPA's Regional Haze
Rule
B. Best Available Retrofit Technology (BART)
C. Reasonable Progress Requirements
D. Consultation With Federal Land Managers (FLMs)
E. Regulatory and Legal History of the 2012 Colorado SIP
III. Craig Unit 1--NOX BART
A. Background
B. May 26, 2017 Submittal
C. The EPA's Evaluation of Craig Unit 1 Amendments
IV. Nucla--NOX Reasonable Progress
A. Background
B. May 26, 2017 Submittal
C. The EPA's Evaluation of Nucla Amendments
V. Coordination With FLMs
VI. The EPA's Proposed Action
VII. Incorporation by Reference
VIII. Statutory and Executive Order Reviews
I. What action is the EPA taking?
On December 31, 2012, the EPA approved a regional haze SIP revision
submitted by the State of Colorado on May 25, 2011. The 2011 SIP
revision included NOX BART emission limits for Craig Station
Units 1 and 2 near Craig, Colorado, and a NOX reasonable
progress emission limit for the Nucla Station located in Montrose
County.\1\ The State of Colorado submitted proposed revisions to the
2011 SIP submittal on May 26, 2017, that modify the NOX BART
determination for Craig Unit 1 and the NOX reasonable
progress determination for Nucla. The EPA is now proposing to approve
those revisions. Specifically, the EPA is proposing to approve the
State's revisions to the Craig Unit 1 NOX BART determination
that would require Craig Unit 1 to meet an annual NOX
emission limit of 4,065 tons per year (tpy) by December 31, 2019. The
SIP revision would also require the unit to either (1) convert to
natural gas by August 31, 2023, and if converting to natural gas,
[[Page 18244]]
comply with a NOX emission limit of 0.07 lb/MMBtu (30-day
rolling average) beginning August 31, 2021, or (2) shut down by
December 31, 2025. The EPA is also proposing to approve the State's
revisions to the Nucla NOX reasonable progress determination
that would require the source to meet an annual NOX emission
limit of 952 tpy by January 1, 2020, and shut down on or before
December 31, 2022.
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\1\ 77 FR 76871 (December 31, 2012).
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II. Background
A. Requirements of the Clean Air Act and the EPA's Regional Haze Rule
In section 169A of the CAA, added by the 1977 Amendments to the
Act, Congress created a program for protecting visibility in the
nation's national parks and wilderness areas. This section establishes
``as a national goal the prevention of any future, and the remedying of
any existing, impairment of visibility in mandatory Class I Federal
areas which impairment results from manmade air pollution.'' \2\ On
December 2, 1980, the EPA promulgated regulations to address visibility
impairment in Class I areas that is ``reasonably attributable'' to a
single source or small group of sources.\3\ These regulations
represented the first phase in addressing visibility impairment. The
EPA deferred action on regional haze, which emanates from a variety of
sources, until monitoring, modeling and scientific knowledge about the
relationships between pollutants and visibility impairment were
improved.\4\
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\2\ 42 U.S.C. 7491(a). Areas designated as mandatory Class I
Federal areas consist of national parks exceeding 6000 acres,
wilderness areas and national memorial parks exceeding 5000 acres,
and all international parks that were in existence on August 7,
1977. 42 U.S.C. 7472(a). In accordance with section 169A of the CAA,
EPA, in consultation with the Department of Interior, promulgated a
list of 156 areas where visibility is identified as an important
value. 44 FR 69122 (November 30, 1979). The extent of a mandatory
Class I area includes subsequent changes in boundaries, such as park
expansions. 42 U.S.C. 7472(a). Although states and tribes may
designate as Class I additional areas which they consider to have
visibility as an important value, the requirements of the visibility
program set forth in section 169A of the CAA apply only to
``mandatory Class I Federal areas.'' Each mandatory Class I Federal
area is the responsibility of a ``Federal Land Manager.'' 42 U.S.C.
7602(i). When we use the term ``Class I area'' in this section, we
mean a ``mandatory Class I Federal area.''
\3\ 45 FR 80084, 80084 (December 2, 1980).
\4\ Regional haze means visibility impairment that is caused by
the emission of air pollutants from numerous anthropogenic sources
located over a wide geographic area. Such sources include, but are
not limited to, major and minor stationary sources, mobile sources,
and area sources. 40 CFR 51.301.
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Congress added section 169B to the CAA in 1990 to address regional
haze issues. The EPA promulgated a rule to address regional haze on
July 1, 1999.\5\ The Regional Haze Rule (RHR) revised the existing
visibility regulations to integrate provisions addressing regional haze
and established a comprehensive visibility protection program for Class
I areas. The requirements for regional haze, found at 40 CFR 51.308 and
51.309, are included in the EPA's visibility protection regulations at
40 CFR 51.300-51.309. The EPA revised the RHR on January 10, 2017.\6\
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\5\ 64 FR 35714, 35714 (July 1, 1999) (codified at 40 CFR part
51, subpart P).
\6\ 82 FR 3078 (January 10, 2017).
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The CAA requires each state to develop a SIP to meet various air
quality requirements, including protection of visibility.\7\ Regional
haze SIPs must assure reasonable progress toward the national goal of
achieving natural visibility conditions in Class I areas. A state must
submit its SIP and SIP revisions to the EPA for approval. Once
approved, a SIP is enforceable by the EPA and citizens under the CAA;
that is, the SIP is federally enforceable.
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\7\ CAA sections 110(a), 169A, and 169B, 42 U.S.C. 7410(a),
7491, and 7492(a).
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B. Best Available Retrofit Technology (BART)
Section 169A of the CAA directs the EPA to require states to
evaluate the use of retrofit controls at certain larger, often
uncontrolled, older stationary sources in order to address visibility
impacts from these sources. Specifically, section 169A(b)(2)(A)
requires states to include in their SIPs such measures as may be
necessary to make reasonable progress toward the natural visibility
goal, including a requirement that certain categories of existing major
stationary sources built between 1962 and 1977 procure, install, and
operate the ``Best Available Retrofit Technology'' as determined by the
states. Under the RHR, states are directed to conduct BART
determinations for such ``BART-eligible'' sources that may reasonably
be anticipated to cause or contribute to any visibility impairment in a
Class I area.
On July 6, 2005, the EPA published the Guidelines for BART
Determinations under the Regional Haze Rule (the ``BART Guidelines'')
to assist states in determining which sources should be subject to the
BART requirements and in setting appropriate emission limits for each
covered source.\8\ The process of establishing BART emission
limitations follows three steps: first, identify the sources that meet
the definition of ``BART-eligible source'' set forth in 40 CFR 51.301;
\9\ second, determine which of these sources ``emits any air pollutant
which may reasonably be anticipated to cause or contribute to any
impairment of visibility in any such area'' (a source which fits this
description is ``subject to BART''); and third, for each source subject
to BART, identify the best available type and level of control for
reducing emissions. Section 169A(g)(7) of the CAA requires that states
consider five factors in making BART determinations: (1) The costs of
compliance; (2) the energy and non-air quality environmental impacts of
compliance; (3) any existing pollution control technology in use at the
source; (4) the remaining useful life of the source; and (5) the degree
of improvement in visibility which may reasonably be anticipated to
result from the use of such technology. States must address all
visibility-impairing pollutants emitted by a source in the BART
determination process. The most significant visibility-impairing
pollutants are sulfur dioxide (SO2), NOX, and
particulate matter (PM).
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\8\ 70 FR 39104; 40 CFR part 51, appendix Y.
\9\ BART-eligible sources are those sources that have the
potential to emit 250 tons or more of a visibility-impairing air
pollutant, were not in operation before August 7, 1962, but were in
existence on August 7, 1977, and whose operations fall within one or
more of 26 specifically listed source categories. 40 CFR 51.301.
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A SIP addressing regional haze must include source-specific BART
emission limits and compliance schedules for each source subject to
BART. In lieu of requiring source-specific BART controls, states have
the flexibility to adopt alternative measures, as long as the
alternative provides greater reasonable progress towards natural
visibility conditions than BART (i.e., the alternative must be ``better
than BART'').\10\ Once a state has made a BART determination, the BART
controls must be installed and operated as expeditiously as
practicable, but no later than 5 years after the date of the EPA's
approval of the final SIP.\11\ In addition to what is required by the
RHR, general SIP requirements mandate that the SIP include all
regulatory requirements related to monitoring, recordkeeping, and
reporting for the BART emission limitations.\12\
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\10\ 40 CFR 51.308(e)(2) and (3).
\11\ CAA section 169A(g)(4), 42 U.S.C. 7491(g)(4); 40 CFR
51.308(e)(1)(iv).
\12\ CAA section 110(a), 42 U.S.C. 7410(a); 40 CFR part 51,
subpart K.
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C. Reasonable Progress Requirements
In addition to BART requirements, each regional haze SIP must
contain measures as necessary to make reasonable progress towards the
national visibility goal. As part of determining what measures are
necessary to make reasonable progress,
[[Page 18245]]
the SIP must first identify anthropogenic sources of visibility
impairment that are to be considered in developing the long-term
strategy for addressing visibility impairment.\13\ States must then
consider the four statutory reasonable progress factors in selecting
control measures for inclusion in the long-term strategy--the costs of
compliance, the time necessary for compliance, the energy and non-air
quality environmental impacts of compliance, and the remaining useful
life of potentially affected sources.\14\ Finally, the SIP must
establish reasonable progress goals (RPGs) for each Class I area within
the State for the plan implementation period (or ``planning period''),
based on the measures included in the long-term strategy.\15\ If an RPG
provides for a slower rate of improvement in visibility than the rate
needed to attain the national goal by 2064, the SIP must demonstrate,
based on the four reasonable progress factors, why the rate to attain
the national goal by 2064 is not reasonable and the RPG is
reasonable.\16\
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\13\ 40 CFR 51.308(d)(3)(iv).
\14\ CAA section 169A(g)(1), 42 U.S.C. 7491(g)(1); 40 CFR
51.308(d)(1)(i)(A).
\15\ 40 CFR 51.308(d), (f).
\16\ 40 CFR 51.308(d)(1)(ii).
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D. Consultation With Federal Land Managers (FLMs)
The RHR requires that a state consult with FLMs before adopting and
submitting a required SIP or SIP revision.\17\ States must provide FLMs
an opportunity for consultation, in person and at least 60 days before
holding any public hearing on the SIP. This consultation must include
the opportunity for the FLMs to discuss their assessment of impairment
of visibility in any Class I area and to offer recommendations on the
development of the RPGs and on the development and implementation of
strategies to address visibility impairment. Further, a state must
include in its SIP a description of how it addressed any comments
provided by the FLMs. Finally, a SIP must provide procedures for
continuing consultation between the state and FLMs regarding the
state's visibility protection program, including development and review
of SIP revisions and 5-year progress reports, and on the implementation
of other programs having the potential to contribute to impairment of
visibility in Class I areas.
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\17\ 40 CFR 51.308(i).
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E. Regulatory and Legal History of the 2012 Colorado SIP
On December 31, 2012, the EPA approved a regional haze SIP revision
submitted by the State of Colorado on May 25, 2011. On February 25,
2013, the National Parks Conservation Association (NPCA) and Wild Earth
Guardians (Guardians) filed petitions for review in the U.S. Court of
Appeals for the Tenth Circuit of the EPA's final approval of the
Colorado regional haze SIP.\18\ Among other things, Guardians and NPCA
challenged the NOX BART limit for Craig Unit 1. Tri-State
and the State of Colorado joined the litigation as intervenors. After
the court consolidated the cases for review, and after several months
of court-supervised mediation, the parties reached a settlement under
which Craig Unit 1 would be subject to a 0.07 lb/MMBtu NOX
limit, consistent with the installation of selective catalytic
reduction (SCR) controls, by August 31, 2021.\19\ The settlement
further required that the EPA ask the Tenth Circuit to vacate the
previous approval of the Colorado SIP revision relating to Craig Unit 1
and remand the rule to the agency for further action. The court granted
the EPA's request on December 22, 2014, and signed an order ending the
litigation on August 15, 2015.
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\18\ WildEarth Guardians v. EPA, No. 13-9520 (10th Cir.) and
National Parks Conservation Association v. EPA, No. 13-9525 (10th
Cir.).
\19\ 79 FR 47636 (August 14, 2014).
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In accordance with the terms of the 2014 settlement, Colorado
submitted a SIP revision to the EPA in 2015 to revise the Craig Unit 1
NOX BART determination, emission limit, and associated
compliance deadline. Specifically, Colorado determined that
NOX BART for Craig Unit 1 was an emission limit of 0.07 lb/
MMBtu, which was based on the capabilities of SCR, and established an
associated compliance date of August 31, 2021.
In 2017, Colorado submitted a regional haze SIP revision to the EPA
reassessing the NOX limit for the Craig Unit 1. The
revisions were developed after discussions in 2016 between Tri-State,
Guardians, NPCA, the State of Colorado, and the EPA, and require one of
two possible NOX BART compliance paths for Craig Unit 1 to
either (1) shut down by December 31, 2025, or (2) convert to natural-
gas firing by August 31, 2023. If Craig Unit 1 is converted to natural-
gas firing, the NOX emission limit will be 0.07 lb/MMBtu
after August 31, 2021 (30-day rolling average). If Craig Unit 1 is shut
down, the NOX emission limit will be 0.28 lb/MMBtu (30-day
rolling average) until December 31, 2025. Colorado withdrew the 2015
SIP revision when it submitted the 2017 SIP revision that is the
subject of this proposed action.
III. Craig Unit 1--NOX BART
A. Background
The 2011 regional haze SIP for Colorado established a
NOX BART emission limit for Craig Units 1 and 2. The Craig
Station is located in Moffat County, approximately 2.5 miles southwest
of the town of Craig. This facility is a coal-fired power plant with a
total net electric generating capacity of 1264 megawatts (MW),
consisting of three units. Units 1 and 2, which are subject to BART,
are dry-bottom pulverized coal-fired boilers, each rated at a net
capacity of 428 MW.
In the 2011 submittal, Colorado determined that selective non-
catalytic reduction (SNCR) was BART for both Unit 1 and Unit 2, based
on the cost-effectiveness and visibility improvement associated with
this level of control. Colorado determined that SCR, a more stringent
control technology, was not BART because its costs were too high.
Colorado also determined that SNCR could achieve an emission limit of
0.27 lb/MMBtu (30-day rolling average) at both Unit 1 and Unit 2.
Nevertheless, as a BART alternative, Colorado ultimately adopted a more
stringent emission limit for Unit 2 (0.08 lb/MMBtu, 30-day rolling
average, based on SCR) and a slightly less stringent limit for Unit 1
(0.28 lb/MMBtu, 30-day rolling average, based on SNCR). The EPA
approved Colorado's BART alternative and NOX BART emission
limits into the SIP on December 31, 2012.\20\
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\20\ 77 FR 76871 (December 31, 2012).
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B. May 26, 2017 Submittal
On May 26, 2017, Colorado submitted a SIP revision containing
amendments to the Colorado Code of Regulations, Regulation Number 3,
Stationary Source Permitting and Air Pollutant Emission Notice
Requirements, Part F, Regional Haze Limits--Best Available Retrofit
Technology (BART) and Reasonable Progress (RP), Section VI, Regional
Haze Determinations. In assessing BART for Craig Unit 1, Colorado
determined that, under either a 20- or 30-year remaining useful life,
NOX BART would be an emission limit of 0.07 lb/MMBtu based
on the installation of SCR.\21\ Colorado
[[Page 18246]]
then reassessed NOX BART for Craig Unit 1 under the two
compliance paths associated with the 2016 settlement discussions: A
shutdown in 2025 or a conversion to natural gas in 2023.\22\ After
completing this reassessment, Colorado established the following
amendments:
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\21\ This limit, consistent with the 2014 settlement, was
contained in the 2015 SIP submission. As noted previously, the State
withdrew that submission when it submitted the 2017 SIP revision,
but the State's justification for the 0.07 lb/MMBtu NOX
BART limit is retained in the 2017 SIP.
\22\ Colorado used the term ``reassessment,'' and we interpret
the term to mean that the state reassessed its previous BART
determination under the differing future factual scenarios to see
whether those facts were outcome determinative.
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Craig Unit 1 will either (1) close on or before December
31, 2025; or (2) cease burning coal no later than August 31, 2021, with
the option to convert Unit 1 to natural-gas firing by August 31, 2023;
In the case of a conversion to natural-gas firing, a 30-
day rolling average NOX emission limit of 0.07 lb/MMBtu (30-
day rolling average) will be effective after August 31, 2021;
The owner/operator of Craig Unit 1 will notify the State
in writing on or before February 28, 2021, whether Unit 1 will cease
operation or convert to natural gas;
For both scenarios, Craig Unit 1 will be subject to an
interim NOX emission limit of 0.28 lb/MMBtu (30-day rolling
average), effective January 1, 2017 (first compliance date January 31,
2017), until December 31, 2025 if closing or August 31, 2021 if
converting to natural gas; and
Craig Unit 1 will be subject to an annual NOX
emission limit of 4,065 tpy effective December 31, 2019, which will be
calculated on a calendar year basis beginning in 2020.
The amendments also excepted Craig Unit 1 from complying with the
original SIP effective date of January 30, 2013, and associated
compliance date 5 years later. The Colorado Air Quality Control
Commission adopted the revisions on December 15, 2016 (effective
February 14, 2017).
1. Shutdown
For the shutdown compliance path, the State considered two
amortization periods to reflect the remaining useful life based on two
possible projected compliance dates and the shutdown date of December
31, 2025. The first scenario used an amortization period of 4 years and
4 months, calculated as the difference between a projected compliance
date of August 31, 2021, (which would have been required under the
State's BART determination made in conjunction with the 2014
settlement) and the December 31, 2025 shutdown date. The associated
emissions reductions, annualized cost, and cost-effectiveness values
for SNCR and SCR using the amortization period is shown in Table 1.
Table 1--Craig Station Unit 1 NOX Cost Comparison
[4 years, 4 months of operation]
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Emissions Cost
Control technology reduction Annualized effectiveness
(tpy) cost ($) ($/ton)
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SNCR............................................................ 779 6,172,522 7,928
SCR............................................................. 4,048 64,106,699 15,835
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The second scenario used an amortization period of 8 years, to
reflect the difference between the December 31, 2025 shutdown date and
the December 31, 2017 compliance date that the 2012 SIP revision
approval established.\23\ The associated emissions reductions,
annualized costs, and cost-effectiveness values for SNCR and SCR using
the amortization period of 8 years is shown in Table 2.
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\23\ The operation period begins in calendar year 2018 (December
31, 2017). The effective date of the EPA's approval of Colorado's
regional haze SIP was January 30, 2013. As noted previously, the
Tenth Circuit vacated the EPA's approval of the Craig portions of
this SIP on December 22, 2014.
Table 2--Craig Station Unit 1 NOX Cost Comparison
[8 years of operation]
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Emissions Cost
Control technology reduction Annualized effectiveness
(tpy) cost ($) ($/ton)
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SNCR............................................................ 779 4,755,842 6,109
SCR............................................................. 4,048 41,476,535 10,245
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Under both amortization scenarios, the remaining useful life of
Craig Unit 1 is shorter than the 20-year amortization period used in
the 2012 BART determination, which increases the annualized costs and
cost-effectiveness values of the control technologies.\24\ Based on
this assessment, the State determined that neither SNCR or SCR is cost-
effective when the remaining useful life is shortened to either 4 years
and 4 months or 8 years, depending on the scenario selected, as a
result of the shutdown of Craig Unit 1 on December 31, 2025.
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\24\ The EPA finalized revisions to the Air Pollution Control
Cost Manual (Chapters 1 and 2), https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution, in May 2016; these revisions change the amortization
period for SCR from 20 years to 30 years. The amortization period
for SNCR remains at 20 years.
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2. Natural Gas Conversion
For the natural gas conversion compliance path, Craig Unit 1 will
cease to burn coal by August 31, 2021, with the option to convert to
natural-gas firing by August 31, 2023. A 30-day rolling average
NOX emission limit of no more than 0.07 lb/MMBtu will apply
after August 31, 2021.
C. The EPA's Evaluation of Craig Unit 1 Amendments
We are proposing to approve Colorado's BART reassessment for two
possible compliance scenarios for Craig
[[Page 18247]]
Unit 1: (1) Shutdown or (2) conversion to natural gas.
As a threshold matter, we agree with the State's assessment that an
emission limit of 0.07 lb/MMBtu would be NOX BART for Craig
Unit 1 under either a 20- or 30-year remaining useful life. But we also
agree with the State that it is appropriate to reassess the
NOX BART limit under the shutdown and natural gas conversion
scenarios, either of which would considerably shorten the remaining
useful life of the existing coal-fired boiler.
While the RHR does not require states to consider source
retirements or fuel switching (e.g., from coal to gas) as BART options,
states are free to do so.\25\ In other states, we have approved state-
adopted requirements for the shutdown of a source or for switching
fuels, which have usually been negotiated between the source operator
and the state. We also have approved BART determinations that took into
account the resulting shorter remaining useful life of the affected
source.
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\25\ 40 CFR part 51, appendix Y.
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We agree with Colorado's BART reassessment for both the shutdown
and natural gas conversion scenarios. Specifically, we acknowledge and
agree with the assumptions used to calculate the two different
amortization periods for the shutdown scenario. In past SIP actions,
the EPA has measured amortization periods from the projected compliance
date to the date of retirement. In this instance, the compliance date
for SCR is August 31, 2021, which would have been required under the
State's BART determination made in conjunction with the 2014
settlement, resulting in an amortization period of four years and four
months as reflected in Colorado's first amortization period scenario
(Table 1). For SNCR, the projected compliance date would be earlier,
thus resulting in a longer amortization period, albeit one shorter than
8 years; the 8-year amortization period is therefore a conservative
approach that understates the annualized costs of both SCR and SNCR.
When considering the shortened remaining useful life under either
amortization scenario associated with Craig Unit 1 shutting down by
December 31, 2025, the EPA finds Colorado's determination reasonable
that neither SNCR or SCR is cost effective. Therefore, we are proposing
to approve Colorado's NOX BART reassessment that if Craig
Unit 1 shuts down by December 31, 2025, neither SNCR or SCR would be
BART due to the high cost-effectiveness values associated with a
shortened remaining useful life. We are also proposing to approve the
alternative compliance path that allows Craig Unit 1 to convert to
natural-gas firing by August 31, 2023, and cease burning coal by August
31, 2021, with an associated NOX BART emission limit of 0.07
lb/MMBtu (30-day rolling average) on that date, because this emission
limit is equivalent to the one that the State found would be BART under
a 20- or 30-year remaining useful life scenario. Accordingly, natural-
gas firing is another means by which NOX BART can be met for
Craig Unit 1. Finally, we are proposing to approve Colorado's
requirement that an annual NOX limit of 4,065 tpy will be
effective on December 31, 2019, for Craig Unit 1 because this
additional measure would strengthen the SIP as there currently is no
regional haze annual NOX limit for Unit 1.
IV. Nucla--NOX Reasonable Progress
A. Background
The Tri-State Nucla Station is located in Montrose County
approximately 3 miles southeast of the town of Nucla, Colorado. The
Nucla facility consists of one coal-fired steam-driven electric
generating unit, Unit 4, with a rated electric generating capacity of
110 MW (gross).
In 2006, Tri-State installed a small-scale SNCR system on Unit 4
that injects anhydrous ammonia to achieve NOX reductions.
The SNCR system is used when NOX emissions approach 0.4 lb/
MMBtu; rates above this result in mass emissions that approach the
annual permitted NOX limit of 1,987.9 tpy (12-month rolling
average). Although Colorado, in its 2011 submittal, determined that
full-scale SNCR and SCR were technically feasible for reducing
NOX emissions at Nucla Unit 4, the State determined that
neither control technology was necessary for reasonable progress based
on the uncertainty of the control efficiency for SNCR and what Colorado
determined would likely be excessive costs associated with SCR.
Instead, Colorado determined that Nucla Unit 4 should meet an emission
limit of 0.5 lb/MMBtu (30-day rolling average) as expeditiously as
practicable, but in no event later than December 31, 2017, based on
consideration of the four reasonable progress factors. The EPA approved
this emission limit into the SIP on December 31, 2012, as meeting the
relevant regional haze requirements.
B. May 26, 2017 Submittal
The May 26, 2017 submittal includes the following amendments to the
Colorado Code of Regulations, Regulation Number 3, Stationary Source
Permitting and Air Pollutant Emission Notice Requirements, Part F,
Regional Haze Limits--Best Available Retrofit Technology (BART) and
Reasonable Progress (RP), Section VI, Regional Haze Determinations,
related to Nucla:
Nucla will close on or before December 31, 2022; and
Nucla will be subject to an annual NOX emission
limit of 952 tpy effective January 1, 2020, on a calendar year basis
beginning in 2020.
The amendments also removed Nucla's original compliance date of
December 31, 2017, and the requirement for a proposed compliance
schedule from Nucla due within 60 days after the EPA's approval of the
reasonable progress portion of Colorado's regional haze SIP. The
current NOX emission limit of 0.5 lb/MMBtu (30-day rolling
average) is not amended.
C. The EPA's Evaluation of Nucla Amendments
Because the amendments, requiring Nucla to shut down on or before
December 31, 2022, and meet an annual NOX limit of 952 tpy
by January 1, 2020, do not alter the previously approved 0.5 lb/MMBtu
(30-day rolling average) emission limit requirement, the closure of
Nucla achieves greater NOX emission reductions than the
relevant portions of the 2012 SIP, (which did not previously include
any shutdown date). We therefore propose to approve Colorado's revision
related to Nucla.
V. Coordination With FLMs
Class I areas in Colorado are managed by either the U.S. Forest
Service (FS) or the U.S. National Park Service (NPS). As described in
section II.D of this proposed rule, the Regional Haze Rule grants the
FLMs a special role in the review of regional haze SIPs. Under 40 CFR
51.308(i)(2), Colorado was obligated to provide the FS and the NPS with
an opportunity for consultation in development of the State's proposed
SIP revisions. Colorado provided the FS and the NPS with access to the
proposed revisions to Regulation Number 3, Part F on January 12,
2017.\26\ The FLMs did not provide any comments on the proposed
revisions.
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\26\ Email between Colorado and NPS, January 2017.
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VI. The EPA's Proposed Action
In this action, the EPA is proposing to approve SIP amendments to
Regulation Number 3, Part F, Section VI, shown in Table 3, submitted by
the State of Colorado on May 26, 2017, addressing the NOX
BART and reasonable progress
[[Page 18248]]
requirements for Craig Unit 1 and Nucla, respectively.
Table 3--List of Colorado Amendments That EPA Is Proposing To Approve
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Amended Sections in May 26, 2017 Submittal Proposed for Approval
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Regulation Number 3, Part F: VI.A.2 (table); VI.A.3; VI.A.4; VI.B.2
(table); VI.B.3; VI.B.4; VI.D; VI.E.
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VII. Incorporation by Reference
In this rule, the EPA is proposing to include in a final EPA rule
regulatory text that includes incorporation by reference. In accordance
with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by
reference the amendments described in section VI. The EPA has made, and
will continue to make, these materials generally available through
www.regulations.gov and at the EPA Region 8 Office (please contact the
person identified in the FOR FURTHER INFORMATION CONTACT section of
this preamble for more information).
VIII. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely proposes to approve state law as meeting federal
requirements and does not impose additional requirements beyond those
imposed by state law. For that reason, this proposed action:
Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Orders 12866 (58
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act; and
Does not provide the EPA with the discretionary authority
to address, as appropriate, disproportionate human health or
environmental effects, using practicable and legally permissible
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
In addition, the SIP is not proposed to apply on any Indian
reservation land or in any other area where the EPA or an Indian tribe
has demonstrated that a tribe has jurisdiction. In those areas of
Indian country, the rule does not have tribal implications and will not
impose substantial direct costs on tribal governments or preempt tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen dioxide, Particulate
matter, Sulfur oxides.
Authority: 42 U.S.C. 7401 et seq.
Dated: April 16, 2018.
Debra Thomas,
Acting Regional Administrator, Region 8.
[FR Doc. 2018-08622 Filed 4-25-18; 8:45 am]
BILLING CODE 6560-50-P