```

[Federal Register Volume 79, Number 153 (Friday, August 8, 2014)]
[Rules and Regulations]
[Pages 46513-46555]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-18228]

[[Page 46513]]

Vol. 79

Friday,

No. 153

August 8, 2014

Part II

 Environmental Protection Agency

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40 CFR Part 49

 Approval of Air Quality Implementation Plans; Navajo Nation; Regional 
Haze Requirements for Navajo Generating Station; Final Rule

Federal Register / Vol. 79 , No. 153 / Friday, August 8, 2014 / Rules 
and Regulations

[[Page 46514]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 49

[EPA-R09-OAR-2013-0009; FRL-9914-62-Region 9]

Approval of Air Quality Implementation Plans; Navajo Nation; 
Regional Haze Requirements for Navajo Generating Station

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is promulgating a 
source-specific Federal Implementation Plan (FIP) requiring the Navajo 
Generating Station (NGS), a coal-fired power plant located on the 
Navajo Nation near Page, Arizona, to achieve reductions in oxides of 
nitrogen (NOX) required under the Best Available Retrofit 
Technology (BART) provisions of the Clean Air Act (CAA) and the 
Regional Haze Rule (RHR). On February 5, 2013, EPA issued a proposed 
BART determination for NGS and an alternative to BART. In a 
supplemental proposal on October 22, 2013, EPA proposed to approve a 
new alternative plan, based on an agreement developed by a group of 
stakeholders known as the Technical Work Group (TWG). EPA is finalizing 
the alternative to BART described in our supplemental proposal. This 
rule is consistent with the TWG Agreement, including a lifetime cap in 
total emissions of NOX from NGS over 2009-2044 (2009-2044 
NOX Cap). Our final action will achieve greater emissions 
reductions than BART and is expected to significantly reduce the impact 
of NGS on visibility at 11 mandatory Class I Federal areas. The 
operator of NGS must implement one of several alternative operating 
scenarios to achieve the necessary emission reductions to comply with 
the 2009-2044 NOX Cap.

DATES: Effective date: This rule is effective on October 7, 2014.

FOR FURTHER INFORMATION CONTACT: Anita Lee, EPA Region 9, (415) 972-
3958, lee.anita@epa.gov.

SUPPLEMENTARY INFORMATION: EPA has established a docket for this action 
under Docket ID No. EPA-R09-OAR-2013-0009. The index to the docket for 
this action is available electronically at http://www.regulations.gov 
and in hard copy at EPA Region 9, 75 Hawthorne Street, San Francisco, 
California. While documents in the docket are listed in the index, some 
information may be publicly available only at the hard copy location 
(e.g. copyrighted material, voluminous or oversized documents, etc.), 
and some may not be publicly available in either location (e.g. 
Confidential Business Information (CBI)). To inspect the hard copy 
materials, please schedule an appointment during normal business hours 
with the contact listed in the FOR FURTHER INFORMATION CONTACT section. 
A reasonable fee may be charged for copies.
    Throughout this document, ``we'', ``us'', and ``our'' refer to EPA.

Table of Contents

I. Executive Summary
II. Background for the Final Rule
    A. History of NGS
    B. Summary of Statutory and Regulatory Framework for Addressing 
Visibility and Sources Located in Indian Country
    C. Summary of Proposed Rule and Supplemental Proposal
    D. Summary of Legal Rationale for Compliance Flexibility
III. Summary of Final FIP Provisions
IV. Summary of Major Issues Raised by Commenters
V. Summary of Final Action
VI. Administrative Requirements
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act
    L. Petitions for Judicial Review

I. Executive Summary

    EPA is taking final action pursuant to the CAA and the RHR to 
require Units 1, 2, and 3 at NGS to reduce emissions of NOX 
in order to reduce the impact NGS has on visibility at 11 mandatory 
Class I Federal areas. We are finalizing an alternative to BART based 
on agreed-upon recommendations developed by a group of diverse 
stakeholders known as the Technical Work Group (TWG). Our final action 
limits emissions of NOX from NGS by establishing a long-term 
facility-wide cap on total NOX emissions from 2009 to 2044 
and requires the implementation of one of several alternative operating 
scenarios to ensure that the 2009-2044 cap is met. Generally, the 
alternative operating scenarios require the closure of one unit at NGS 
(or the curtailment of electricity generation by a similar amount) in 
2019, and compliance with a NOX emission limit that is 
achievable with the installation of selective catalytic reduction (SCR) 
on two units in 2030.
    As part of our final action, EPA is also setting a source-specific 
BART Benchmark against which to compare the TWG Alternative to ensure 
that it will achieve greater reasonable progress than BART. The BART 
Benchmark is consistent with the BART determination we proposed on 
February 5, 2013, requiring all three units at NGS to meet an emission 
limit achievable with SCR within five years of a final rule. EPA is not 
finalizing our proposed BART determination for NGS in the regulatory 
requirements of this Final Rule.
    EPA's action to finalize an alternative to BART consistent with the 
TWG Agreement will achieve greater NOX emission reductions 
at lower cost than BART in exchange for flexibility in the timeframe 
for achieving NOX reductions. When fully implemented, this 
Final Rule requires over an 80 percent reduction in NOX 
emissions from NGS and is expected to significantly reduce the impact 
of NGS on visibility at 11 mandatory Class I Federal areas.

II. Background for the Final Rule

A. History of NGS

    NGS is a coal-fired power plant located on the Navajo Nation Indian 
Reservation near Page, Arizona. The facility consists of three 750 
megawatt (MW) coal-fired electric utility steam generating units with a 
total capacity of 2250 MW constructed from 1974 to 1976. The three 
units at NGS are co-owned by six entities: The United States Bureau of 
Reclamation (Reclamation) (24.3 percent); Salt River Project (21.7 
percent), which also serves as the facility operator; Los Angeles 
Department of Water and Power (21.2 percent); Arizona Public Service 
(14 percent); NV Energy (11.3 percent); and Tucson Electric Power (7.5 
percent).
    Federal participation in NGS was authorized in the Colorado River 
Basin Project Act of 1968 as a preferred alternative to building 
hydroelectric dams in the Grand Canyon for the purpose of providing 
power to the Central Arizona Project (CAP).\1\ The

[[Page 46515]]

CAP is a 336-mile water distribution system that delivers about 1.5 
million acre-feet (AF) per year of Colorado River water from Lake 
Havasu in western Arizona to non-Indian agricultural (NIA) water users 
in central Arizona, Indian tribes located in Arizona, and municipal 
water users in Maricopa, Pinal, and Pima Counties in Arizona. The CAP 
water is used to meet the terms of a number of Indian water-rights 
settlements in central Arizona and to reduce groundwater usage in the 
region. A portion of Reclamation's share of electricity from NGS powers 
the pumps that move CAP water to its destinations along the 
distribution system.
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    \1\ For more detail and for citations or references to the 
information provided in this Background section, please see the 
Proposed Rule at 78 FR 8274 (February 5, 2013).
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    Several tribes located in Arizona, including the Gila River Indian 
Community, the Ak-Chin Indian Community, the Tohono O'odham Nation, the 
San Carlos Apache Tribe, the White Mountain Apache Indian Tribe, the 
Fort McDowell Yavapai Nation, the Salt River Pima-Maricopa Indian 
Community, the Navajo Nation, the Yavapai-Apache Nation, the Hopi 
Tribe, the Pascua Yaqui Tribe, the Yavapai-Prescott Tribe, and the 
Tonto Apache Nation, have CAP water allocations or contracts. In 
exchange for allocations of CAP water at reduced cost and access to 
funds for the development of water infrastructure, the tribes with 
water settlement agreements have released their claims to other water 
in Arizona. Excess NGS power owned by Reclamation that is not used by 
CAP is sold and profits are deposited into the Lower Colorado River 
Basin Development Fund (Development Fund) to support the tribal water 
settlement agreements. The U.S. Department of the Interior (DOI or 
Interior), through Reclamation, plays an important role in the 
implementation of these settlement agreements and the management of the 
Development Fund.
    The coal used by NGS is supplied by the Kayenta Mine, operated by 
Peabody Energy and located on reservation lands of both the Navajo 
Nation and the Hopi Tribe. Taxes and royalties from NGS and the Kayenta 
Mine are paid to the Navajo Nation and Hopi Tribe, contributing to the 
annual revenues for both governments. EPA understands that the process 
is underway to renew site leases for NGS and the Kayenta Mine, as well 
as associated rights of way agreements and contracts with the Navajo 
Nation and Hopi Tribe.
    Given the extent of federal and tribal interests in NGS, on January 
4, 2013, EPA, DOI, and the Department of Energy (DOE) signed a joint 
federal agency statement (Joint Statement) committing to collaborate on 
several short- and long-term goals, including analyzing and pursuing 
strategies for providing clean, affordable, and reliable power, 
affordable and sustainable water, and sustainable economic development 
to key stakeholders who currently depend on NGS.\2\ The Joint Statement 
also recognizes the trust responsibility of the Federal government to 
Indian tribes.
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    \2\ See document title ``2013--0104 Joint Federal Agency 
Statement on NGS'' within document number 0005 in the docket for 
this proposed rulemaking at EPA-R09-OAR-2013-0009, which can be 
found at www.regulations.gov.
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B. Summary of Statutory and Regulatory Framework for Addressing 
Visibility and Sources Located in Indian Country

    In our Proposed Rules, we provided a detailed discussion of the 
statutory and regulatory framework for addressing visibility impairment 
in the mandatory Class I Federal Areas, addressing sources located in 
Indian country under the statute and the Tribal Authority Rule (TAR), 
and developing BART determinations pursuant to the CAA and the BART 
Guidelines set forth in Appendix Y to 40 CFR Part 51.\3\ Here, we 
provide a brief summary of the statutory and regulatory framework.
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    \3\ See 78 FR 8274 (February 5, 2013) and 78 FR 62509 (October 
22, 2013).
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    Title I, part C, subpart II of the CAA Amendments of 1977 
establishes a visibility protection program that sets forth ``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 man-made air pollution.'' \4\ EPA 
promulgated regional haze regulations implementing the program on April 
22, 1999.\5\ Consistent with the statutory requirement in 42 U.S.C. 
7491(b)(2)(a), EPA's 1999 regional haze regulations include a provision 
that States must require certain major stationary sources to procure, 
install, and operate BART. This provision covers sources in listed 
industrial categories with the potential to emit 250 or more tons per 
year of an air pollutant that were ``in existence on August 7, 1977, 
but which ha[ve] not been in operation for more than fifteen years as 
of such date.'' These sources are considered to be ``BART-eligible.'' 
\6\ NGS meets these criteria and is a BART-eligible source.\7\
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    \4\ See 42 U.S.C. 7419A(a)(1).
    \5\ See 64 FR 35765 (April 22, 1999).
    \6\ See 40 CFR 51.308(e)(1).
    \7\ See 74 FR 44314 (August 28, 2009); 78 FR 8279 (February 5, 
2013); see also 56 FR 50172 (October 3, 1991) addressing BART for 
SO2 based on Reasonably Attributable Visibility 
Impairment.
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    BART-eligible sources that are reasonably anticipated to cause or 
contribute to visibility impairment are ``subject'' to the BART 
requirements.\8\ Generally speaking, a BART-eligible source with a 
predicted visibility impact of 0.5 deciviews (dv) or more in a Class I 
area is considered to ``contribute'' to visibility impairment.\9\ NGS 
contributes to visibility impairment at 11 surrounding Class I areas in 
excess of this threshold, and is thus subject to BART.
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    \8\ See 70 FR 39104 at 39161 (July 6, 2005).
    \9\ Id.
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    In determining BART, States are required to take into account five 
factors identified in the CAA and EPA's regulations.\10\ Those factors 
are: (1) The costs of compliance, (2) the energy and non-air quality 
environmental impacts of compliance, (3) any pollution control 
equipment in use or in existence 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.\11\ EPA's guidelines for evaluating BART provide 
more detail and are set forth in Appendix Y to 40 CFR Part 51.
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    \10\ 42 U.S.C. 7491(g)(2) and 40 CFR 51.308(e)(1)(A)(ii)(A).
    \11\ 40 CFR 51.308(e)(1)(ii)(A).
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    In 1998, EPA promulgated the Tribal Authority Rule (TAR) relating 
to implementation of CAA programs in Indian country.\12\ In the TAR, 
EPA determined that it has the discretionary authority to promulgate 
``such federal implementation plan provisions as are necessary or 
appropriate to protect air quality'' consistent with CAA sections 
301(a) and 301(d)(4) when a tribe has not submitted or EPA has not 
approved a Tribal Implementation Plan (TIP).\13\ EPA has previously 
promulgated FIPs under the TAR to regulate air pollutants emitted from 
NGS.\14\
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    \12\ See 40 CFR part 49; see also 59 FR 43956 (August 25, 1994) 
(proposed rule); 63 FR 7254 (February 12, 1998) (final rule); 
Arizona Public Service Company v. EPA, 211 F.3d 1280 (D.C. Cir. 
2000), cert. den., 532 U.S. 970 (2001) (upholding the TAR).
    \13\ See 40 CFR 49.11(a).
    \14\ See 56 FR 50172 (October 3, 1991). In 1999, EPA proposed a 
FIP for NGS to fill the regulatory gap that existed because Arizona 
State permits and SIP rules are not applicable or enforceable in the 
Navajo Nation, and the Tribe had not sought approval of a TIP 
covering the plant. 64 FR 48731 (September 8, 1999). EPA then re-
proposed the FIP with some additional conditions in September 2006. 
71 FR 53631 (September 12, 2006). EPA finalized that NGS FIP on 
March 5, 2010. 75 FR 10174.
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    Under the CAA, compliance with emission limits determined to be 
BART must be achieved as expeditiously as practicable but not later 
than 5 years after the effective date of the final BART determination 
(See CAA 169A(b)(2)(A) and (g)(4)). As discussed in greater detail in 
our Proposed Rule, EPA

[[Page 46516]]

recognizes that the circumstances related to NGS create unusual and 
significant challenges for a 5-year compliance schedule.\15\ Based on 
those challenges and our discretion under the TAR for implementing CAA 
requirements in Indian country, we considered other options that are 
consistent with the CAA and RHR, and that provide for a more flexible, 
extended compliance schedule.
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    \15\ Because of its complicated history and its location on the 
Navajo Nation, NGS faces numerous unique complexities and the 
unusual requirement to comply with NEPA for lease and other rights-
of-way approvals, which apply only to NGS and Four Corners Power 
Plant, the other coal-fired power plant located on the Navajo 
Nation. EPA also understands the importance of the continued 
operation of NGS and the Kayenta Mine to the Navajo Nation and Hopi 
Tribe as a source of direct revenues through lease payments and coal 
royalties, as well as the importance of Reclamation's share of NGS 
to supply water to many tribes located in Arizona in accordance with 
several water settlement acts. EPA also recognizes that Reclamation 
may have fewer options compared to the other owners for financing 
pollution control or other large capital improvement projects at 
NGS. SRP expressed concern that the owners of NGS may choose to 
retire the facility if faced with the financial risk of making a 
large capital investment within 5 years without also having 
certainty that the lease and contract re-negotiations would conclude 
in a timely and favorable manner.
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    EPA's BART regulations allow an alternative in lieu of BART, 
provided the alternative results in greater reasonable progress than 
would have been achieved through installation of BART.\16\ Generally, 
an alternative is considered to be approvable provided it results in 
greater emissions reductions and the geographic distribution in 
emissions from the alternative is not substantially different than the 
distribution of the emissions under BART.\17\ For a state that is 
subject to the submittal deadlines in the RHR, the regulations provide 
that alternatives to BART must ensure that all necessary emission 
reductions occur within the period of the first long-term strategy for 
regional haze (i.e., by 2018) for states that were required to submit 
regional haze SIPs in December 2007.\18\ Thus, if states had submitted 
timely regional haze SIPs in 2007 with BART compliance deadlines in 
2012, the RHR provided more than 5 additional years for the 
implementation of alternatives to BART.
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    \16\ 40 CFR 51.308(e)(2).
    \17\ 40 CFR 51.308(e)(3).
    \18\ 40 CFR 51.308(e)(2)(iii).
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C. Summary of Proposed Rule and Supplemental Proposal

    EPA published an advanced notice of proposed rulemaking (ANPR) 
concerning BART for NGS and the Four Corners Power Plant in August 
2009.\19\ On February 5, 2013, EPA's proposed BART determination for 
NGS was published in the Federal Register and provided a thorough 
discussion of the statutory and regulatory framework for addressing 
visibility through application of BART for sources located in Indian 
country, and of the factual background for our BART determination at 
NGS.\20\ The proposal analyzed the five BART factors and proposed to 
find that BART for NGS was installation of emissions controls to meet a 
NOX emission limit of 0.055 lb/MMBtu based on a rolling 
average of 30 boiler operating days (30-BOD average).\21\ However, in 
recognition of the important role that NGS and the Kayenta Mine play in 
providing employment and revenue to the Navajo Nation and Hopi Tribe, 
and the role of Reclamation's share of electricity generated by NGS in 
fulfilling water settlement agreements with numerous tribes located in 
Arizona, we proposed that the potential economic impacts to tribes 
argue for thoughtful consideration of how flexibility in the compliance 
timeframe could be provided consistent with the air quality goals of 
the CAA.\22\ Therefore, as discussed in our Proposed Rule, EPA proposed 
to exercise our authority and discretion under section 301(d)(4) of the 
CAA and 40 CFR 49.11(a) to propose an appropriate timeframe for 
alternative measures to BART under the RHR for NGS. We provided a 
thorough discussion of the legal rationale for setting the compliance 
schedule for alternative measures in our Proposed Rule.\23\
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    \19\ See 74 FR 44314 (August 28, 2009).
    \20\ See 78 FR 8274 (February 5, 2013).
    \21\ Id. at 8288.
    \22\ Id. at 8284.
    \23\ Id. at 8289.
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    Our Proposed Rule included a framework for evaluating alternatives 
to BART.\24\ As part of the framework, EPA proposed a NOX 
emission credit for the previous early and voluntary installation of 
low-NOX burners with separated over-fire air (LNB/SOFA) over 
the 2009-2011 timeframe (LNB/SOFA credit). We proposed that the LNB/
SOFA credit supported setting a compliance timeframe based on the 
flexibility under section 301(d)(4) of the CAA and 40 CFR 49.11(a).\25\ 
EPA proposed to find that an alternative is ``better than BART'' if the 
total emissions over 2009-2044 from the alternative measure, minus the 
LNB/SOFA credit, are less than the total emissions under our proposed 
BART determination for the same period (i.e., the BART Benchmark). 
Consistent with this framework, EPA proposed an alternative to BART, 
requiring compliance with an emission limit of 0.055 lb/MMBtu on one 
unit per year in 2021, 2022, and 2023 (Alternative 1). We calculated 
that total emissions under Alternative 1 over 2009-2044, minus the LNB/
SOFA credit, would be less than emissions based on the BART Benchmark. 
Thus, we proposed to find that Alternative 1 was ``better than BART''. 
EPA recognized that there may be interest in additional flexibility 
beyond the 2021-2023 timeframe. EPA evaluated two additional compliance 
schedules but did not propose to approve them as ``better than BART'' 
alternatives because total emissions over 2009-2044 under these 
compliance schedules exceeded the BART Benchmark. However, we noted 
that potential technologies or other options for achieving additional 
emission reductions could bridge the NOX emission reduction 
deficit for alternatives to BART with compliance schedules that do not, 
by themselves, meet the BART Benchmark.\26\ We invited stakeholders to 
submit additional BART alternatives, consistent with our proposed 
framework, for EPA's consideration.
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    \24\ Id. at 8290-92.
    \25\ 78 FR 62509 at 62511 (October 22, 2013).
    \26\ 78 FR 8274 at 8291 (February 5, 2013).
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    On July 26, 2013, a stakeholder group, known as the Technical Work 
Group on NGS (TWG), submitted an agreement that had been established 
among the seven diverse entities in the TWG. We refer to the July 26, 
2013, document as the ``TWG Agreement.'' The TWG is composed of 
representatives from Central Arizona Water Conservation District 
(CAWCD), the Environmental Defense Fund (EDF), the Gila River Indian 
Community (Gila River or the Community), the Navajo Nation (Navajo), 
Salt River Project (SRP) on behalf of itself and the other non-federal 
owners, DOI, and Western Resource Advocates (WRA). Although EPA 
attended the opening session of a ``kick-off'' meeting for the TWG on 
March 21, 2013, at which we described our Proposed Rule, EPA did not 
otherwise participate in the TWG and was not involved in any of the 
discussions leading to submittal of the TWG Agreement.
    Appendix B to the TWG Agreement contained TWG's recommendation for 
an alternative to BART. In general, the alternative plan in the TWG 
Agreement included closure of one unit at NGS, or curtailment of net 
generating capacity by an equivalent amount, in 2019 and compliance 
with a NOX emission limit of 0.07 lb/MMBtu on two units at 
NGS beginning in 2030. The TWG Agreement

[[Page 46517]]

also included a provision requiring the operator of NGS to cease 
conventional coal-fired generation at NGS by the end of 2044.
    EPA independently evaluated Appendix B to the TWG Agreement to 
determine whether it complied with the framework we put forth in our 
Proposed Rule, as well as the statutory and regulatory requirements in 
the CAA and the RHR. On October 22, 2013, EPA published a Supplemental 
Proposal describing the TWG Agreement and requesting comment.\27\ Our 
Supplemental Proposal contained a detailed evaluation of Appendix B to 
the TWG Agreement along with a discussion of our legal rationale for 
proposing to approve requirements consistent with the TWG Agreement as 
meeting the requirements for an alternative to BART. Throughout this 
document, we refer to the regulations we proposed in our Supplemental 
Proposal that are consistent with Appendix B of the TWG Agreement as 
the ``TWG Alternative.'' Thus, in this document, the term TWG 
Alternative refers to EPA's independent regulatory requirements for NGS 
consistent with the TWG Agreement, rather than to Appendix B of the TWG 
Agreement.
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    \27\ See 78 FR 62509 (October 22, 2013).
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    In our Supplemental Proposal, we proposed to revise the numerical 
value of the BART Benchmark from our Proposed Rule. We also proposed a 
2009-2044 NOX Cap based on the revised numerical value of 
the BART Benchmark. In our Proposed Rule, we calculated the BART 
Benchmark to be 358,974 tons of NOX. As discussed in our 
Supplemental Proposal, we proposed three changes to the BART Benchmark: 
(1) Correction of a transcription error; (2) correction of the date 
that EPA anticipated would be 5 years following the effective date of 
the final rule (i.e., July 1, 2019 instead of January 1, 2018); and (3) 
application of the LNB/SOFA credit to the BART Benchmark, rather than 
alternatives to BART, to represent emissions under BART if LNB/SOFA had 
been installed concurrently with selective catalytic reduction (SCR) to 
reduce NOX emissions.\28\ Based on these changes, EPA 
proposed a 2009-2044 NOX Cap of 494,899 tons. Although EPA 
revised our accounting method for the LNB/SOFA credit in our 
Supplemental Proposal, EPA provided a demonstration that the method EPA 
used in our Proposed Rule to compare our proposed BART determination 
against BART alternatives was equivalent to the method in the 
Supplemental Proposal.\29\ The application of the LNB/SOFA credit to 
the BART Benchmark in the Supplemental Proposal represented what total 
emissions over 2009-2044 would have been under our proposed BART 
determination if the operator of NGS had elected to install LNB/SOFA 
concurrently with SCR, i.e., within 5 years of a final rule, rather 
than in 2009-2011. Calculation of the BART Benchmark and 2009-2044 
NOX Cap in this manner is easier to apply and enforce in the 
context of a cap in NOX emissions because the LNB/SOFA 
credit is built into the BART Benchmark rather than subtracted each 
year from actual cumulative emissions.\30\
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    \28\ Id. Tables 1 and 3 at 62515-62516.
    \29\ Id. Table 2 and footnote 32 at 62515.
    \30\ In contrast, in our Proposed Rule, we calculated the BART 
Benchmark and emissions under BART alternatives using the actual 
early installation dates for LNB/SOFA and then applied the LNB/SOFA 
credit to BART alternatives for comparison against the BART 
Benchmark. Although this method would have resulted in a lower 
numerical value for the 2009-2044 NOX Cap, the LNB/SOFA 
credit (representing the early emission reductions achieved over 
2009-2018) would have instead been subtracted from the calculations 
of cumulative emissions under the BART alternative. Although this is 
functionally equivalent to the method used in the Supplemental 
Proposal, this method would make annual comparisons of actual 
cumulative emissions under the BART alternative against the BART 
Benchmark more complicated because it would have required 
adjustments every year to total emissions to subtract out the LNB/
SOFA credit. By accounting for the LNB/SOFA credit in the BART 
Benchmark, the actual annual emissions from NGS can be directly 
compared to the BART Benchmark without any further adjustments.
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    In addition to the enforceable 2009-2044 NOX Cap, our 
Supplemental Proposal defines the operating scenarios that would be 
required depending on the final outcome of NGS ownership after the 
expiration of the current lease term at the end of 2019. In the TWG 
Agreement, the owners of NGS committed to maintain emissions from NGS 
below the 2009-2044 NOX Cap regardless of post-2019 
ownership of NGS and the applicable operating scenario. As a result, 
the operating scenarios in the TWG Alternative include specific actions 
for achieving emission reductions in 2019 and in 2030. The TWG 
Alternative also provides for an operating scenario that is less well-
defined in terms of specific actions but establishes a second 
NOX emissions cap over the period of 2009-2029 (2009-2029 
NOX Cap) that is equivalent to emission reductions that 
would be achieved by a more well-defined operating scenario. The 2009-
2029 NOX Cap would apply in addition to the 2009-2044 
NOX Cap. The Supplemental Proposal included requirements for 
annual emission reporting to EPA that would also be made publicly 
available as part of the compliance demonstration for the TWG 
Alternative.

D. Summary of Legal Rationale for Compliance Flexibility

    In our February 5, 2013, proposal for NGS, EPA proposed an 
alternative to BART that we referred to as Alternative 1. EPA proposed 
to find that consideration of a compliance schedule beyond 2018 for 
Alternative 1 at NGS was appropriate for a number of reasons, including 
the importance of NGS to numerous Indian tribes located in Arizona and 
the federal government's reliance on NGS to meet the requirements of 
water settlements with several tribes. Providing this timeframe for 
compliance would not, in itself, avoid or mitigate increases in water 
rates for tribes located in Arizona; however, it would provide time for 
the collaborating federal agencies to explore options to avoid or 
minimize potential impacts to tribes, including seeking funding to 
cover expenses for the federal portion of pollution control at NGS.
    In developing this framework, EPA proposed to exercise its 
authority and discretion under section 301(d)(4) of the CAA, 42 U.S.C. 
7601(d)(4) and the TAR, 40 CFR 49.11(a), and proposed an appropriate 
timeframe for an alternative measure under the RHR for NGS. EPA 
considered this timeframe to be consistent with the general 
programmatic requirements. Under the RHR, States and regulated sources 
had almost 20 years from the issuance of the rule in 1999 to design and 
implement alternative measures to BART. For numerous reasons, including 
the myriad stakeholder interests and complex governmental interests 
unique to NGS, we are only now addressing the BART requirements for 
NGS.
    Our proposal to require emission reductions beyond 2018 was 
supported by CAA section 301(d)(4) and the TAR codified at 40 CFR 
49.11(a). The TAR reflects EPA's commitment to promulgate ``such 
Federal implementation plan provisions as are necessary or appropriate 
to protect air quality'' in Indian country where a tribe either does 
not submit a Tribal Implementation Plan (TIP) or does not receive 
approval of a submitted TIP (emphasis added).
    The use of the term ``provisions as are necessary or appropriate'' 
indicates EPA's determination that it may only be necessary or 
appropriate to promulgate a FIP of limited scope. The United States 
Court of Appeals for the Tenth Circuit has previously endorsed the

[[Page 46518]]

application of this approach in a challenge to the FIP for the Four 
Corners Power Plant, stating: ``[40 CFR 49.11(a)] provides the EPA 
discretion to determine what rulemaking is necessary or appropriate to 
protect air quality and requires the EPA to promulgate such 
rulemaking.'' \31\ The court went on to observe: ``Nothing in section 
49.11(a) requires EPA . . . to submit a plan meeting the completeness 
criteria of [40 CFR part 51] Appendix V.'' \32\ While the decision in 
the Tenth Circuit focused on 40 CFR part 51, Appendix V, EPA believes 
the same considerations apply to the promulgation of a FIP intended to 
address the objectives set forth in 40 CFR 51.308(e)(2). In particular, 
EPA has discretion to determine if and when a FIP addressing the 
objectives set forth in 40 CFR 51.308(e)(2) should be promulgated, 
which necessarily includes discretion to determine the timing for 
complying with the requirements of any such FIP.
---------------------------------------------------------------------------

    \31\ See Ariz. Public Serv. Co. v. EPA, 562 F.3d 1116 (10th Cir. 
2009).
    \32\ Id.
---------------------------------------------------------------------------

III. Summary of Final FIP Provisions

    EPA is finalizing our finding that it is necessary or appropriate 
to promulgate a source-specific FIP requiring NGS to achieve 
NOX emission reductions required by the BART provisions of 
the CAA and RHR. EPA is determining that our proposed NOX 
emission limit of 0.055 lb/MMBtu, based on our analysis of the relevant 
factors, establishes the appropriate BART Benchmark for determining 
``better than BART.'' Further, we are finalizing our assessment that 
the TWG Alternative, which establishes an enforceable 2009-2044 cap on 
NOX emissions from NGS over the life of the facility is 
``better than BART.'' Finally, we are finalizing the TWG Alternative as 
the FIP requirements for NGS.
    EPA is promulgating four possible operating scenarios under the TWG 
Alternative (see Table 1). The operator of NGS must implement one of 
the four enforceable operating scenarios in order to comply with the 
2009-2044 NOX Cap. The applicable operating scenario will 
depend on the outcome of ownership changes related to LADWP, NV Energy, 
and Navajo Nation, as well as whether the operator of NGS can increase 
capacity (by no more than 189 MW) to accommodate ownership changes, 
without triggering New Source Review permitting requirements, as 
described in Table 1. Once the ownership outcomes are finalized, the 
operator of NGS must implement the applicable Alternative as shown in 
Table 1. For example, if LADWP and NV Energy both retire their 
ownership shares of NGS and the Navajo Nation does not elect to 
purchase an ownership share of NGS, TWG Alternative A1 applies and the 
operator of NGS must implement Alternative A1 and may not elect to 
implement Alternatives A2, A3, or B. By December 1, 2019, the operator 
of NGS must notify EPA of the applicable Alternative (i.e., TWG 
Alternative A1, A2, A3, or B).
    In addition to the enforceable 2009-2044 NOX Cap, 
Alternatives A1, A2, and A3 each has enforceable emission reduction 
measures in 2019 and 2030 (see Table 1). Under Alternative B, in 
addition to the enforceable 2009-2044 NOX Cap, the operator 
of NGS must also ensure that cumulative NOX emissions over 
2009-2029 comply with the 2009-2029 NOX Cap. The 2009-2029 
NOX Cap is calculated based on emissions that would have 
been emitted over that period under Alternative A1. Under all 
Alternatives, if, based on required annual reports submitted by the 
operator of NGS to EPA, cumulative emissions of NOX from NGS 
exceed the 2009-2044 NOX Cap at any time prior to December 
31, 2044, the operator of NGS must permanently cease operation of NGS. 
In addition, under Alternative B, if cumulative emissions of 
NOX exceed the 2009-2029 NOX Cap prior to 2029, 
the operator of NGS must temporarily cease operation of all units at 
NGS.\33\ Under all Alternatives, the operator must permanently cease 
operation of all units at NGS by December 22, 2044.
---------------------------------------------------------------------------

    \33\ The combination of the 2009-2044 and 2009-2029 
NOX Caps under TWG Alternative B means that if NGS 
exceeds the 2009-2029 NOX Cap prior to 2029 it must cease 
operation, but the operator may re-start operation after 2030 as 
long as cumulative emissions have not yet exceeded the 2009-2044 
NOX Cap.
---------------------------------------------------------------------------

    Under all TWG Alternatives, the operator of NGS must report to EPA 
annual emissions and heat input data and must make this information 
publicly available on its Web site. In addition, under TWG Alternative 
B, the operator must also submit to EPA annual Emission Reduction Plans 
projecting year-by-year emissions covering the 2020-2029 and 2030-2044 
periods so that there is a plan for operation of NGS that ensures that 
cumulative emissions of NOX do not exceed the 2009-2029 
NOX Cap and the 2009-2044 NOX Cap. Although year-
by-year emissions projected in the annual Emission Reduction Plans are 
not enforceable (i.e., emissions in a given year are not required to 
match projections for that year in an Emission Reduction Plan), the 
requirement to submit Emission Reduction Plans is enforceable, and 
provides the operator with a framework for planning for future 
emissions reductions. The requirement also provides EPA and the public 
the opportunity to monitor and evaluate progress of emission reductions 
under TWG Alternative B.

                   Table 1--Summary of the Major Regulatory Provisions of the TWG Alternative
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
Applicability
    (Step 1)....................   If LADWP and NV Energy both exit NGS without        If LADWP
                                   selling their ownership interests (i.e., retire shares),    or NV Energy
                                   or both exit by selling to an existing NGS participant;     sells to a 3rd
                                   or one retires shares and the other sells to an existing    party, or does
                                   NGS participant; and                                        not exit NGS;
                                 ------------------------------------------------------------
    (Step 2)....................   If Navajo   If Navajo   If Navajo   n/a.
                                   Nation does not     Nation purchases    Nation purchases
                                   purchase            up to 170 MW by     up to 170 MW by
                                   ownership share     12/31/19; and       12/31/19; and
                                   by 12/31/19;
    (Step 3)....................   n/a......   If          If          n/a.
                                                       Participants        Participants
                                                       increase capacity   cannot increase
                                                       without             capacity without
                                                       triggering permit   triggering
                                                       requirements;       permitting);
Applicable Alternative..........  Then TWG            Then TWG            Then TWG            Then TWG
                                   Alternative A1      Alternative A2      Alternative A3      Alternative B
                                   applies.            applies.            applies.            applies.
                                 -------------------------------------------------------------------------------
Applicable Requirements.........   Comply with 2009-2044 NOX Cap of 494,899 tons.
                                   Permanently cease operation of all units if cumulative emissions
                                   before 2044 exceed 2009-2044 NOX Cap.

[[Page 46519]]

 
                                   Permanently cease conventional coal-fired electricity generation by
                                   December 22, 2044.
                                 -------------------------------------------------------------------------------
Additional Emission Cap.........   n/a                                                 Comply
                                                                                               with 2009-2029
                                                                                               NOX Cap of
                                                                                               416,865 tons.
                                 ------------------------------------------------------------
Specific Requirements *.........   By 12/31/   By 12/31/   By 12/31/  
                                   19 permanently      19 permanently      19 reduce net       Temporarily cease
                                   close 1 unit.       close 1 unit.       generating          operation if
                                                                           capacity by no      cumulative
                                                                           less than 561 MW.   emissions before
                                                                                               2029 exceed 2009-
                                                                                               2029 NOX Cap.
                                   By 12/31/   By 12/31/   By 12/31/
                                   30 meet NOX limit   19 operator may     30 meet NOX limit
                                   of 0.07 lb/MMBtu    increase capacity   of 0.07 lb/MMBtu
                                   on 2 units.         by no more than     on 2 units.
                                                       189 MW.
                                                       By 12/31/
                                                       30 meet 0.07 lb/
                                                       MMBtu on 2 units.
                                 -------------------------------------------------------------------------------
Reporting.......................   By December 1, 2019, notify EPA of applicable Alternative (A1, A2,
                                   A3, or B).
                                   Submit annual report summarizing heat input and annual and cumulative
                                   emissions of NOX.
                                   Make annual report publicly available on Web Site.
                                   Submit application to revise Part 71 Operating Permit by December 31,
                                   2020.
                                 -------------------------------------------------------------------------------
Additional Reporting............   n/a                                                 By 12/31/
                                                                                               19 and annually
                                                                                               thereafter submit
                                                                                               Emission
                                                                                               Reduction Plans
                                                                                               to project year-
                                                                                               by-year emissions
                                                                                               to assure
                                                                                               compliance with
                                                                                               NOX Caps.
----------------------------------------------------------------------------------------------------------------
* All units must comply with the existing NOX emission limit of 0.24 lb/MMBtu established in a 2008 permitting
  action. See discussion in Proposed Rule at 78 FR 8284 (February 5, 2013). This limit applies to each unit
  unless otherwise stated.

    In our final rule, EPA has included several revisions to the 
proposed regulatory text (40 CFR 49.5513(j)) put forth in the 
Supplemental Proposal. The substantive revisions include:
    1. Revision to Sec.  49.5513(j)(3) to clarify that EPA is 
finalizing a ``better than BART'' Alternative;
    2. Additions to Sec.  49.5513(j)(3) to specify that the operator 
must temporarily cease operation of NGS if cumulative emissions of 
NOX exceed the 2009-2029 NOX Cap of 416,865 tons 
at any time prior to December 31, 2029 (under Alternative B), and must 
permanently cease operation of NGS if cumulative emissions of 
NOX exceed the 2009-2044 NOX Cap of 494,899 tons 
at any time prior to December 31, 2044 (under all Alternatives);
    3. Additions to Sec.  49.5513(j)(3)(i)(A)(2), (B)(3), and (C)(2), 
to specify that the NOX emission limit of 0.07 lb/MMBtu is 
to be calculated based on a rolling average basis of 30 boiler 
operating days;
    4. Correction to Sec.  49.5513(j)(3)(ii)(D), to specify that 
Alternative B shall also apply if either of the Departing Participants 
(i.e., LADWP or NV Energy) remains as a participant in NGS;
    5. Addition of Sec.  49.5513(j)(3)(iii), consistent with the TWG 
Agreement, to require the owners of NGS to cease its operation of 
conventional coal-fired generation at NGS no later than December 22, 
2044;\34\
---------------------------------------------------------------------------

    \34\ See page 14 of the TWG Agreement (section IV.F). This 
section of the TWG Agreement also states that ``[a]t its election, 
consistent with the Lease Amendment, the Navajo Nation may continue 
plant operations at NGS after December 22, 2044 consistent with EPA 
approval.'' EPA is not including this provision into the regulatory 
requirements at Sec.  49.5513(j)(3)(iii), however, EPA expects that 
NGS would be substantially modified if the Navajo Nation elects to 
continue operation of the facility after NGS ceases conventional 
coal-fired generation in 2044, and that NGS must then meet all 
applicable regulatory and permitting requirements in existence at 
that time.
---------------------------------------------------------------------------

    6. Addition to Sec.  49.5513(j)(4)(ii), to change the annual 
reporting date to begin in 2015 instead of the specific date of January 
31, 2015, and specify that the report must be submitted to EPA and also 
made publicly-available within 30 days of the submittal deadline 
associated with the annual emission inventory required by the Part 71 
Operating Permit for NGS;
    7. Addition to Sec.  49.5513(j)(4)(iii), to clarify that the Part 
71 Operating Permit for NGS shall incorporate practically enforceable 
limits for NOX of 0.24 lb/MMBtu, on a 30[hyphen]day rolling 
average basis, for each Unit equipped with LNB/SOFA, and 0.07 lb/MMBtu, 
on a rolling average basis of 30 boiler operating days, for each Unit 
equipped with SCR, as federally enforceable permit conditions; and
    8. Addition of Sec.  49.5513(j)(4)(iv)(C), to specify that the 
requirement to submit annual Emission Reduction Plans beginning no 
later than December 31, 2019, must be incorporated into the Part 71 
Operating Permit for NGS as a federally enforceable permit condition.
    9. Revision to Sec.  49.5513(j)(7) to require the owner or operator 
of NGS to maintain records that document compliance with the 
NOX Cap (e.g., daily emissions and heat input data) for the 
life of the facility, rather than at least five years.
    10. Deletion of Sec.  49.5513(j)(7)(vi) that required record-
keeping of all major maintenance activities conducted on emission 
units, air pollution control equipment, and CEMS because record-keeping 
of maintenance activities are not needed to ensure compliance with the 
2009-2029 and 2009-2044 NOX Caps.
    11. Revision to Sec.  49.5513(j)(11) to state that the affirmative 
defense provisions of paragraphs Sec.  49.5513 (c)(2) and Sec.  
49.5513(i) do not apply to paragraph Sec.  49.5513(j).\35\
---------------------------------------------------------------------------

    \35\ We note that in our Supplemental Proposal, we reported the 
affirmative defense provisions as paragraphs (c)(1) and (g)(3) in 
error. The correct citations are to paragraph (c)(2) and paragraph 
(i) of 40 CFR 49.5513.
---------------------------------------------------------------------------

    Revision (1) above is necessary to clarify that EPA is finalizing a 
``better than BART'' alternative in lieu of BART.

[[Page 46520]]

The BART Benchmark used to assess the ``better than BART'' alternative 
is based on our proposed BART determination for NGS, and the ``better 
than BART'' alternative is consistent with our Supplemental Proposal of 
the TWG Alternative. Revision (3) above is necessary because EPA 
inadvertently did not specify the averaging period associated with the 
emission limits for NOX in our Supplemental Proposal. 
Revisions (2) and (4) through (10) above are in response to comments 
submitted to EPA on our Supplemental Proposal. Revision (11) above 
amends a proposed provision in our Supplemental Proposal that limited 
the applicability of the existing affirmative defense provisions for 
startups, shutdowns, and malfunctions (from the previous FIP for NGS 
codified at 40 CFR 49.5513(c)(2) and 40 CFR 49.5513(i)) to 
malfunctions.\36\ In this Final Action, we are revising (j)(11) to make 
clear that the existing affirmative defense provisions do not apply to 
the emission limits established in the TWG Alternative.
---------------------------------------------------------------------------

    \36\ See final action for the previous FIP for NGS at 75 FR 
10179 (March 5, 2010).
---------------------------------------------------------------------------

    Following the close of the public comment period, the United States 
Court of Appeals for the DC Circuit issued a decision concerning 
various aspects of the NESHAP for Portland cement plants issued by EPA 
in 2013, including the affirmative defense provision of that rule.\37\ 
The court found that EPA lacked authority to establish an affirmative 
defense for private civil suits and held that under the CAA, the 
authority to determine civil penalty amounts lies exclusively with the 
courts, not EPA. The court did not address whether such an affirmative 
defense provision could be properly included in a SIP. However, the 
court's holding makes it clear that the CAA does not authorize 
promulgation of such a provision by EPA. In particular, the court's 
decision turned on an analysis of CAA sections 113 (Federal 
enforcement) and 304 (Citizen suits). These provisions apply with equal 
force to a civil action brought to enforce the provisions of a FIP. The 
logic of the court's decision thus applies to the promulgation of a FIP 
and precludes EPA from including an affirmative defense provision in a 
FIP. Therefore, we are not including an affirmative defense provision 
in the final FIP.
---------------------------------------------------------------------------

    \37\ NRDC v. EPA, 2014 U.S. App. LEXIS 7281 (D.C. Cir.), in the 
docket for this rulemaking.
---------------------------------------------------------------------------

    We note that, if a source is unable to comply with emission 
standards as a result of a malfunction, EPA may use case-by-case 
enforcement discretion, as appropriate. Further, as the DC Circuit 
recognized, in an EPA or citizen enforcement action the court has the 
discretion to consider any defense raised and determine whether 
penalties are appropriate.\38\
---------------------------------------------------------------------------

    \38\ Id. at 24 (arguments that violations were caused by 
unavoidable technology failure can be made to the courts in future 
civil cases when the issue arises).
---------------------------------------------------------------------------

IV. Summary of Major Issues Raised by Commenters

    The public comment period for our Proposed Rule opened on February 
5, 2013. On two occasions, we extended the comment period on our 
Proposed Rule at the request of stakeholders, with a final closing date 
of January 6, 2014. Although we posted the pre-publication version of 
our Supplemental Proposal to the docket and to our Web site on 
September 25, 2013, the public comment period for the Supplemental 
Proposal officially began when it was published in the Federal Register 
on October 22, 2013.\39\ We accepted public comments on our 
Supplemental Proposal, concurrently with our Proposed Rule, until 
January 6, 2014. Our Supplemental Proposal also included notice of five 
public hearings, one on the Navajo Nation, one on the Hopi reservation 
and three in the State of Arizona. The public hearings occurred during 
the week of November 12, 2013. In all, 194 oral testimonies were 
presented at the public hearings.
---------------------------------------------------------------------------

    \39\ See document number 0182 (Pre-publication version of 
Supplemental Proposal for NGS Signed on September 25, 2013), posted 
to docket on September 25, 2013 and publication of Supplemental 
Proposal in Federal Register at 78 FR 62509 (October 22, 2013).
---------------------------------------------------------------------------

    We received over 77,000 written comments. Of these, over 76,800 
comments came from private individuals who submitted substantially 
similar comments by email or postcard. We received an additional 300 
unique written comments (not including duplicates, requests for 
extension of the public comment period, or requests for additional 
hearings) from a variety of individuals and entities, including tribal 
governments, environmental or public interest advocacy groups, water 
interest groups, groups representing industry or commerce, the operator 
and participants in NGS and the Kayenta Mine, elected officials, and 
state and local governments.
    In this document, EPA is providing an abbreviated summary of the 
major comments and EPA's responses to those comments, grouped together 
by subject matter. The complete response to comments document (RTC) 
includes the full summary of all substantive comments and EPA's full 
responses to those comments. The RTC is included in the docket for this 
rulemaking.\40\ We are not responding to comments unrelated to our 
Proposed Rule or Supplemental Proposal for NGS in this document or in 
the RTC.
---------------------------------------------------------------------------

    \40\ See document titled ``EPA Responses to Comments on Final 
Rule for NGS'' in the docket for this rule.
---------------------------------------------------------------------------

A. General Comments From Public Hearings

    Comment: Contribution of NGS to the local and state economy and 
support for TWG Alternative
    Many commenters at the public hearings preferred the TWG 
Alternative because they believe that EPA's proposed BART determination 
would force NGS and the Kayenta Mine to close, causing economic harm to 
an area where the majority of residents are low-income and where 
opportunities for employment are limited. Many commenters stressed that 
NGS employs over 500 people and the Kayenta Mine has over 400 
employees, and the loss of these jobs would only exacerbate the 
unemployment rate in the area, which currently ranges from 47 percent 
to 60 percent.
    A number of commenters noted that NGS supplies more than 90 percent 
of the energy used by Central Arizona Water Conservation District 
(CAWCD), which operates the Central Arizona Project (CAP), which 
transfers water from the Colorado River throughout Arizona. A few 
commenters urged EPA to uphold its federal trust obligations and ensure 
that tribal communities continue to have access to affordable water, 
and advised EPA to make a decision consistent with the legal rights 
that the Gila River Indian Community and other stakeholders negotiated 
and that Congress granted under the Arizona Water Settlements Act of 
2004.
    A few commenters support the TWG Alternative because they believe 
it is a fair compromise created by a diverse group of stakeholders that 
provides a path for future operation at NGS by allowing for potential 
ownership changes and by providing an extension to install SCR 
technology, while still ensuring that the total emission reductions of 
NOX will be greater than those achieved under EPA's proposed 
BART determination.
    Response: EPA recognizes the contribution of NGS and the Kayenta 
Mine to the economy of the Navajo Nation, the Hopi Tribe, the city of 
Page, and the state of Arizona. In our Proposed Rule, EPA discussed the 
history of NGS and the relationship between NGS, the Central Arizona 
Project, and numerous tribes located in

[[Page 46521]]

Arizona.\41\ EPA notes that NGS is a facility that is subject to the 
BART requirement of the RHR, and emissions from NGS affect visibility 
at 11 national parks and wilderness areas in the Southwest. The 
analyses in our Proposed Rule and Supplemental Proposal determined that 
additional controls at NGS are cost-effective, will significantly 
reduce the contribution of NGS to visibility impairment at numerous 
Class I areas, and should not cause NGS to retire. However, for a 
number of reasons, including the importance of NGS to numerous Indian 
tribes located in Arizona and the federal government's reliance on NGS 
to meet the requirements of water settlements with several tribes, EPA 
also outlined a framework for considering ``better than BART'' 
alternatives that ensures emission reductions while providing 
additional flexibility to the operator of NGS.\42\
---------------------------------------------------------------------------

    \41\ See 78 FR 8274, at 8275 (February 5, 2013).
    \42\ Id. and 78 FR 62509 (October 22, 2013).
---------------------------------------------------------------------------

    EPA agrees with comments that the TWG Agreement represents a 
compromise between diverse stakeholders, although we recognize that the 
members of the TWG did not invite all affected stakeholders to 
participate in their discussions. The TWG Alternative provides 
certainty for future operation of NGS, flexibility in the compliance 
timeframe, and more emission reductions of NOX than would 
have been achieved under EPA's proposed BART determination. Based on 
our analysis in our Supplemental Proposal and consideration of all 
comments received, EPA is taking action to finalize requirements 
consistent with the TWG Agreement we put forth in our Supplemental 
Proposal, i.e., the TWG Alternative.
    Comment: Impact of air pollutants from NGS on public health and 
welfare and support for proposed BART determination.
    Several commenters favor EPA's proposed BART determination for NGS 
because they believe that emissions from NGS cause health problems in 
the area, including respiratory illness and heart disease. One 
commenter cited a Clean Air Task Force study which states that NGS is 
responsible for approximately $127 million in health costs every year. 
Many of these commenters urged EPA to conduct health studies to 
determine the actual impact to health in these communities.
    Some commenters favor stringent controls because they believe that 
emissions from NGS adversely affect native plant species and harm 
traditional dry land farming. Others assert that emissions from NGS can 
be linked to high levels of mercury found in fish species located in 
nearby lakes. Many commenters expressed concerns over the well-being of 
the Navajo Aquifer. A number of commenters favor stringent controls 
because they believe that emissions produced from NGS contribute to 
climate change.
    In contrast, a few commenters questioned the extent to which 
emissions from NGS impact public health and the environment, asserting 
that the haze is a result of emissions from natural sources (e.g., 
volcanoes, wind/dust storms, and forest fires) and pollution produced 
from nearby cities (i.e., Phoenix, Los Angeles, and Las Vegas). Another 
commenter asserted that EPA's Web site states that vehicles are the 
largest producers of NOX emissions in the country and 
concludes that EPA is ignoring mobile sources and unfairly targeting 
stationary sources.
    Some commenters preferred EPA's proposed BART determination over 
the TWG Alternative because they believe that the alternative is based 
on a false premise. They asserted that the closure of a single unit is 
not equivalent to cleaning up all three units because the reduction in 
capacity will ultimately require new electricity generation elsewhere 
because the demand for power does not change.
    Response: Protection of human health and the environment is EPA's 
mission and forms the basis for many Agency actions, including 
establishing the National Ambient Air Quality Standards (NAAQS), and 
promulgation of regulations such as the New Source Performance 
Standards (NSPS) and the National Emission Standards for Hazardous Air 
Pollutants (NESHAP). In addition to Clean Air Act requirements to 
protect human health, in the 1977 Clean Air Act Amendments, Congress 
declared 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 
(See CAA Sec.  169A).
    EPA agrees that visibility-impairing pollutants are among the same 
pollutants that affect human and ecosystem health; however, health 
studies are beyond the scope of this BART analysis. Similarly, 
hazardous air pollutants (HAPs), such as mercury, are not visibility-
impairing pollutants and therefore are beyond the scope of this BART 
analysis.\43\
---------------------------------------------------------------------------

    \43\ Emissions of HAPs from various source categories are 
addressed generally through the NESHAP. EPA addressed mercury 
emissions from power plants specifically in the final Mercury and 
Air Toxics Standard (MATS). 77 FR 9304 (February 16, 2012).
---------------------------------------------------------------------------

    EPA agrees that climate change is an important issue.\44\ However, 
the RHR addresses pollutants that impair visibility and is not intended 
to address pollutants that contribute to climate change. EPA has 
developed various programs and activities to address emissions of 
greenhouse gases.\45\ On June 2, 2014, EPA signed a proposal to cut 
greenhouse gas emissions from coal-fired power plants by up to 30 
percent by 2030.\46\ Although regulation of greenhouse gases is 
conducted under separate statutory requirements from regional haze, EPA 
is mindful that this BART determination for NGS is not the only 
regulatory program that affects this facility and the region.
---------------------------------------------------------------------------

    \44\ http://www.epa.gov/climatechange/basics/.
    \45\ http://www.epa.gov/climatechange/EPAactivities.html.
    \46\ See http://www2.epa.gov/carbon-pollution-standards.
---------------------------------------------------------------------------

    EPA agrees with comments that mining and combustion of coal affect 
the environment. EPA notes that Reclamation has started its process to 
develop an Environmental Impact Statement (EIS) required under the 
National Environmental Protection Act (NEPA) for activities resulting 
from the continued operation of NGS and the Kayenta Mine.\47\ The on-
going NEPA process provides numerous opportunities and the appropriate 
forum to raise concerns related to the impacts of mining and use of 
water from the Navajo Aquifer. We further note that representatives of 
DOI attended all the public hearings on NGS held by EPA and are aware 
of the issues raised by commenters during the BART process regarding 
mining and the Navajo Aquifer.
---------------------------------------------------------------------------

    \47\ For more information, please see www.ngskmc-eis.net.
---------------------------------------------------------------------------

    EPA disagrees with the assertion that EPA is unfairly targeting 
stationary sources of emissions and ignoring the significant 
contribution of motor vehicle emissions. Consistent with title II of 
the CAA, the EPA Office of Transportation and Air Quality protects 
public health and air quality by, among other things, regulating air 
pollution from motor vehicles, engines, and the fuels to operate 
them.\48\ New cars and sport utility vehicles sold today have emission 
levels of hydrocarbons, NOX, and carbon monoxide that are 
98-99 percent lower than new vehicles sold in the 1960s on a per mile 
basis.\49\ Similarly, standards established for heavy-duty highway and 
non-road

[[Page 46522]]

sources require emission rate reductions on the order of 90 percent or 
more for particulate matter and NOX. In 2014, EPA finalized 
new vehicle emission standards and reduced the fuel sulfur content of 
gasoline to achieve additional reductions in tailpipe and evaporative 
emissions from passenger cars, light-duty vehicles, medium-duty 
passenger cars, and some heavy-duty vehicles starting in 2017.\50\
---------------------------------------------------------------------------

    \48\ http://www.epa.gov/otaq/.
    \49\ See, e.g., 76 FR 74854, at 74900 (December 1, 2011).
    \50\ See Fact Sheet for Tier 3 Standards available at http://www.epa.gov/otaq/documents/tier3/420f14010.pdf.
---------------------------------------------------------------------------

    EPA agrees that forest fires and volcanic eruptions, when they 
occur, can impact visibility to a greater extent than anthropogenic 
sources of emissions. However, Congress directed EPA to develop rules 
to address on-going emissions from stationary sources subject to BART 
to remedy the existing impairment of visibility in Class I areas and 
restore visibility to natural conditions.
    EPA disagrees with assertions that the TWG Alternative is based on 
a false premise because the closure or curtailment of one unit would 
just result in electricity being produced elsewhere. Closure of one 
unit at NGS or the curtailment of an equivalent amount of electricity 
generation is possible based on LADWP and NV Energy's intended 
divestiture from NGS. Consistent with state law in California and 
Nevada, additional electricity needed to replace lost generation from 
NGS, associated with LADWP and NV Energy's divestiture, would come from 
energy sources that emit less air pollution than a conventional coal-
fired power plant operating with SCR on all units.\51\
---------------------------------------------------------------------------

    \51\ See RTC and references therein.
---------------------------------------------------------------------------

    Comments regarding specific aspects of the TWG Alternative are 
discussed in Section 9.0 of the RTC.
    Comment: Environmental and Social Justice.
    Several commenters consider the presence of NGS and several other 
power plants in and around the Navajo Nation to represent an 
environmental and economic justice issue. One commenter noted that a 
Navajo water hauler in Kaibeto, a Navajo community near Page, pays 10 
to 20 times more for water, or $13,000 per acre foot, than municipal 
CAP water users in Glendale or a farmer in Tempe, who pay $551 and $41 
per acre feet, respectively.
    Several commenters opined that the leaders of the Navajo Nation and 
EPA have not protected the interests of the local population. A few 
expressed concerns over how the alternatives were written, noting that 
many tribal residents do not understand the technical language used in 
the documents and therefore cannot adequately comment on the validity 
of the alternatives proposed. Some commenters argued that pollution can 
be controlled using existing technology and EPA should apply the same 
standard to NGS as other coal-burning power plants (e.g., Four Corners 
Power Plant). A few commenters argued that extending the compliance 
timeframe for NGS demonstrates that the federal government considers 
itself exempt from federal law. Several argued that tribal communities 
do not have the funds to develop proposals and/or conduct environmental 
assessments and urged that EPA uphold federal trust responsibilities 
and create an equal playing field.
    Response: EPA defines Environmental Justice as ``the fair treatment 
and meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies. EPA has this goal for all communities and persons across the 
country. It will be achieved when everyone enjoys the same degree of 
protection from environmental and health hazards and equal access to 
the decision-making process to have a healthy environment in which to 
live, learn, and work.'' \52\
---------------------------------------------------------------------------

    \52\ http://www.epa.gov/environmentaljustice/.
---------------------------------------------------------------------------

    EPA takes fair treatment and meaningful involvement seriously and 
provided numerous opportunities for tribal governments, environmental 
and tribal non-governmental organizations, and other interested 
stakeholders to provide input in the development of our Proposed Rule, 
Supplemental Proposal, and Final Rule for NGS. EPA began our public 
involvement process for a BART determination for NGS in 2009, when we 
published an Advanced Notice of Proposed Rulemaking (ANPR). Although we 
initially provided a 30-day public comment period, at the request of 
tribal governments and other interested stakeholders, we extended the 
comment period for tribes another 30 days to October 28, 2009 and, to 
allow additional time for government-to-government consultation on NGS, 
agreed to accept comments from tribes until March 1, 2010.
    EPA received over 6,000 comments on the ANPR.\53\ During 2009 
through 2012, EPA met with various stakeholders, including tribal 
governments and tribal environmental groups, to discuss NGS and hear 
concerns related to a BART determination for this facility.\54\ We 
initially provided a 90-day comment period for the Proposed Rule on 
February 5, 2013, and at the request of various stakeholders, we 
provided several extensions of the public comment period, which closed 
on January 6, 2014. During the 11-month comment period, EPA continued 
to meet with stakeholders, at their request, to discuss our proposed 
BART determination for NGS and our framework for ``better than BART'' 
alternatives.\55\
---------------------------------------------------------------------------

    \53\ See page 25 of the TSD to the February 5, 2013 Proposed 
Rule.
    \54\ See, for example document number 0232 in the ANPR docket at 
EPA-R09-OAR-2009-0598, and document numbers 0008 and 0009 in the 
docket for this rule.
    \55\ See, for example, document number 0150, 0152, 0166, 0173, 
0302, and 0303 in the docket for this rule.
---------------------------------------------------------------------------

    On July 26, 2013, the TWG submitted Appendix B to the TWG Agreement 
to EPA for consideration. EPA posted the TWG Agreement to our docket on 
the same day to provide the public an opportunity to review it.\56\ On 
September 25, 2013, EPA posted our Supplemental Proposal, along with 
supporting documents, to the docket to allow for pre-publication review 
by interested parties.\57\ The Supplemental Proposal was published in 
the Federal Register on October 22, 2013. The comment period for the 
Supplemental Proposal closed on the same day as the BART proposal, on 
January 6, 2014. The Supplemental Proposal also included notice of five 
open house and public hearing events EPA scheduled throughout Arizona 
in November 2013. The open houses allowed members of the public an 
opportunity to talk with representatives from EPA and ask questions. 
EPA held events at the LeChee Chapter House, located on the Navajo 
Nation, as well as in Page, Arizona, and provided oral interpretation 
services between English and Din[eacute] (the Navajo language). EPA 
also held an event at the Hopi Day School, located in Kykotsmovi, the 
seat of the Hopi tribal government.\58\ Finally, we also held events in 
Phoenix and in Tucson, Arizona, to allow stakeholders in central and 
southern Arizona, representing CAP water interests and several tribes 
receiving CAP water, the opportunity to provide comment and talk with 
representatives from EPA. Although EPA understands that the TSD

[[Page 46523]]

and Federal Register notices include technical information that may be 
difficult to understand, EPA provided Fact Sheets and handouts, written 
in plain language, at the open house and public hearing events.\59\ EPA 
representatives were also present at the events to discuss and explain 
our Proposals. EPA recognizes that many tribal communities do not have 
the funds to develop alternative proposals or hire experts on their 
behalf; however, this does not diminish such communities' ability to 
participate in the rulemaking process in a meaningful way as EPA takes 
seriously its responsibility to explain its proposal to all interested 
parties and assesses all comments, regardless of the form of the 
comment or whether or not the commenter has a technical background.
---------------------------------------------------------------------------

    \56\ See document number 0122 in docket for this rule.
    \57\ See document numbers 0182, 0183, and 0184 in the docket for 
this rule.
    \58\ EPA engaged with the government of the Hopi Tribe to search 
for an oral interpreter between English and the Hopi language, but 
the Hopi Tribe was unable to locate anyone to provide those 
services.
    \59\ See document 0219 in the docket for this rule.
---------------------------------------------------------------------------

    As stated in our Proposed Rule and Supplemental Proposal, EPA has 
determined that these proposed rules, if finalized, will not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations because they increase the 
level of environmental protection for all affected populations (i.e., 
require emission reductions from NGS).\60\ EPA recognizes that some 
commenters may view the timeframe for compliance under EPA's framework 
for BART Alternatives as an environmental justice issue. We note that 
the LNB/SOFA credit, an important component of the extended timeframe, 
was based on real, actual emission reductions beginning in 2009 that 
were voluntary and not required by any rule or regulation. We also note 
that the TWG Alternative, which calls for closure of one unit in 2019 
(or equivalent curtailment) will result not only in greater reductions 
of NOX than would have been achieved under BART, but also 
reductions of several other pollutants, including SO2, PM, 
CO2, and mercury. Thus, although the TWG Alternative 
includes a compliance timeframe for achieving additional reductions in 
2030, over 2009-2044, the TWG Alternative will result in reductions of 
additional pollutants that affect visibility or human health, and will 
provide an enforceable mechanism to ensure that NGS ceases conventional 
coal-fired electricity generation at NGS by the end of 2044.
---------------------------------------------------------------------------

    \60\ See discussions under Executive Order 12898 in 78 FR 8793 
(February 5, 2013) and 78 FR 62520 (October 22, 2013).
---------------------------------------------------------------------------

    EPA recognizes that numerous commenters expressed frustration 
regarding social inequities related to costs and benefits of coal 
mining and combustion and water availability and cost. We recommend 
participating in the EIS process for NGS and Kayenta Mine to raise any 
concerns related to costs, benefits, and the environmental and social 
justice of coal mining and coal combustion at the Kayenta Mine and NGS.

B. Comments on Factor 1--Cost of Controls

    Comment: EPA underestimated SCR costs.
    Several commenters asserted that EPA underestimated the cost of 
compliance by improperly reworking cost estimates developed for SRP by 
Sargent and Lundy (S&L) in 2010 and disregarding real costs that would 
be incurred. One commenter quoted the BART Guidelines and the final RHR 
to assert that although the use of the Control Cost Manual is 
encouraged, it is not mandated, and that EPA has discretion to use 
additional sources of cost information. The commenter believes, 
therefore, that the SRP estimates for the excluded cost items are 
appropriate to use because they are more precise than the generic 
statements that EPA relied upon in the Control Cost Manual.
    Response: EPA disagrees with the comment that we improperly 
reworked and underestimated the SCR cost estimates. We note, however, 
that even if we had relied only on the cost estimate provided by SRP, 
EPA still would have concluded that SCR is cost-effective at NGS.
    EPA used a hybrid approach for our cost analysis that relied 
primarily on the cost estimates provided by SRP, but also followed the 
BART Guidelines to determine whether S&L included cost estimates for 
services or equipment associated with SCR that were not allowed under 
the EPA Control Cost Manual. The BART guidelines state ``[i]n order to 
maintain and improve consistency, cost estimates should be based on the 
OAQPS Control Cost Manual, where possible''.\61\ The capital cost 
estimate EPA presented in the proposed rulemaking for SCR plus LNB/SOFA 
($541 million total for Units 1-3) is only 8 percent lower than the SRP 
cost estimate ($589 million). SRP's cost estimate would not have 
changed our conclusion that SCR is cost-effective at NGS.
---------------------------------------------------------------------------

    \61\ The OAQPS Control Cost Manual is now referred to as the EPA 
Control Cost Manual.
---------------------------------------------------------------------------

    As discussed in the TSD to the proposed rulemaking, EPA made four 
adjustments to SRP's cost estimates for SCR, namely, to exclude 
``Owners Construction Management, O&M Support and Contract Service,'' 
``Owners Legal Support and Insurance,'' and ``Allowance for Funds Used 
During Construction,'' and to use an interest rate of 7 percent.\62\ 
Our detailed, line-by-line analysis was included in the docket for this 
proposed rulemaking and provided an explanation for why we retained, 
modified, or rejected each line item.\63\ Please see the RTC for 
additional discussion of these four adjustments to the S&L cost 
analysis.
---------------------------------------------------------------------------

    \62\ See Table 12 of the TSD to the February 5, 2013 Proposed 
Rulemaking, available as document number 0014 in the docket for this 
rule.
    \63\ See MS Excel document titled ``EPA cost analysis for NGS'' 
within document number 0004 in the docket for this rule.
---------------------------------------------------------------------------

    In our proposed rule, we presented total capital and total annual 
cost estimates from EPA and SRP, as well as average and incremental 
cost-effectiveness values based on EPA and SRP assumptions for total 
annual cost and total annual NOX reductions. Based on SRP's 
analysis, average cost-effectiveness of SCR+LNB/SOFA at NGS was less 
than $3,000 per ton and incremental cost-effectiveness of SCR+LNB/SOFA 
(compared to SNCR+LNB/SOFA) was approximately $5,300 per ton.\64\ EPA 
stated that the cost-effectiveness values calculated by both EPA and 
SRP for SCR+LNB/SOFA are lower than or within the range of other BART 
evaluations where EPA or a state has determined that SCR is BART 
(ranging from approximately $2,000 to $6,000 per ton). EPA has 
accordingly determined that SCR is cost-effective at NGS.\65\ 
Therefore, even if EPA accepted the S&L cost estimates submitted by 
SRP, as commenters suggest, EPA would still have determined that SCR is 
cost-effective for NGS.
---------------------------------------------------------------------------

    \64\ See Table 3 of our Proposed Rule, 78 FR 8281 (February 5, 
2013).
    \65\ See our Proposed Rule at 78 FR 8281 (February 5, 2013).
---------------------------------------------------------------------------

    Comment: EPA overestimated SCR costs.
    One commenter asserted that EPA overestimated the cost of 
installing SCR at NGS. Although the commenter supported EPA's 
adjustments to the S&L cost estimates, the commenter asserted that 
further revisions are appropriate. The commenter stated that EPA 
overestimated the following costs: Outage costs associated with 
installation and ``preinstallation'' work; catalyst costs; and 
auxiliary power. In addition, the commenter asserted that EPA 
overestimated annual costs by assuming 20 years as the basis for 
amortizing costs and using an inflated interest rate of 7 percent.
    Although the commenter concurs with EPA's conclusion that SCR plus 
LNB/SOFA is cost-effective at $2,240

[[Page 46524]]

per ton of NOX removed, the commenter re-calculated cost-
effectiveness to be $1,412 per ton for Unit 1, $1,331 per ton for Unit 
2, and $1,497 per ton for Unit 3.
    Response: EPA disagrees with the commenter that any revisions to 
EPA's estimate of SCR costs are necessary. Even if some of the costs 
projected by S&L and used by EPA may be overestimated (e.g., the 
commenter points primarily to capital recovery, catalyst replacement 
costs, and costs for lost power generation), EPA disagrees that we must 
correct every issue of concern raised by the commenters in order to 
support our determination of the BART Benchmark. EPA made four specific 
corrections to the estimates provided by S&L and SRP to make the cost 
calculation methodology consistent with methodologies used for BART 
cost calculations nationally.\66\ As noted in other responses even if 
we consider the average and incremental cost effectiveness of SCR using 
SRP and S&L's full cost projections, EPA would still determine that SCR 
at NGS is cost-effective. The cost-effectiveness values cited by the 
commenter, below $1,500 per ton, certainly suggest that SCR could be 
even more cost-effective than the values we relied upon in our 
proposal, but this would not change our overall determination that SCR 
is cost-effective for NGS.
---------------------------------------------------------------------------

    \66\ See, e.g., Final Regional Haze Plan for Arizona (Phase 1) 
at 77 FR 72512 at 72531 (December 5, 2012); Final Regional Haze Plan 
for North Dakota at 77 FR 20894 at 20916-17 (April 16, 2012); Final 
Regional Haze Plan for New Mexico at 76 FR 52388 at 52399-52400 
(August 22, 2011); Final Regional Haze Plan for Wyoming at 79 FR 
5032 at 5082 (January 30, 2014).
---------------------------------------------------------------------------

    Comment: Updated SCR cost estimate from SRP.
    SRP contracted with S&L in 2013 to review and update the SCR cost 
estimates that were prepared in 2010. S&L escalated costs for 
inflation, and incorporated other minor adjustments to reflect a lower 
NOX design target. SRP's revised capital cost estimates for 
SCR installation on all three units total $650 million (in 2013 
dollars) compared to SRP's 2010 cost estimate of $544 million.
    Response: EPA reviewed the updated 2013 cost estimates developed by 
S&L and provided by SRP.\67\ In its 2013 cost report, S&L explains that 
it escalated labor and material costs, and updated cost estimates based 
on a revised design target of 0.03 lb/MMBtu (so that the SCR system is 
deployed as a 3+1 system rather than a 2+2 catalyst layer system), and 
other design features, including a low-load temperature control system 
to operate SCR at lower loads. S&L escalated several costs at rates 
above 6.7 or 8 percent (e.g., freight, scaffolding). S&L did not make 
any revisions to the components of variable annual costs, including 
maintenance labor, auxiliary power, steam, and catalyst replacement. To 
be consistent with the cost estimates in our Proposed Rule, EPA 
accepted most of the line item costs as adjusted by S&L and made the 
same four adjustments to the 2013 cost estimates as we had applied to 
the 2010 cost estimates. These changes result in an 8 percent 
difference in total capital costs of SCR between EPA's 2013 estimate 
and SRP's 2013 estimate and a 21 percent difference in the total annual 
costs of SCR between the 2013 estimates from EPA and SRP (see Table 2).
---------------------------------------------------------------------------

    \67\ See RTC and references therein.

                            Table 2--Cost Estimates for SCR in 2010 and 2013 Dollars
----------------------------------------------------------------------------------------------------------------
                                        Total capital      Total capital    Total annual cost  Total annual cost
                                       cost  (million)    cost  (million)      (million) in       (million) in
                                           in 2010$           in 2013$            2010$              2013$
----------------------------------------------------------------------------------------------------------------
EPA Estimate........................               $496               $598                $59                $69
SRP Estimate........................                544                650                 75                 88
----------------------------------------------------------------------------------------------------------------

    In our proposed BART determination, EPA also presented the average 
and incremental cost-effectiveness of controls, based on the 
combination of combustion controls (LNB/SOFA) and post-combustion 
controls (i.e., SNCR or SCR). Therefore, cost-effectiveness values 
presented in our Proposed Rule were based on total annual cost of SCR 
in combination with annual cost of LNB/SOFA (SCR+LNB/SOFA), SNCR in 
combination with LNB/SOFA (SNCR+LNB/SOFA) or LNB/SOFA alone.\68\ Based 
on the updated 2013 cost estimates for SCR, Table 3 shows the average 
and incremental cost-effectiveness of controls, in both 2010 and 2013 
dollars, based on EPA and SRP assumptions for total annual cost and 
annual NOX reductions achieved by SCR. See RTC for further 
detail on cost-effectiveness of SNCR+LNB/SOFA and LNB/SOFA.
---------------------------------------------------------------------------

    \68\ 78 FR 8281, February 5, 2013.

                                            Table 3--Cost Effectiveness of Controls in 2010 and 2013 Dollars
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            2010 $                                                      2013 $
                                 -----------------------------------------------------------------------------------------------------------------------
                                               EPA                           SRP                           EPA                           SRP
--------------------------------------------------------------------------------------------------------------------------------------------------------
SCR+ LNB/SOFA:
    Total Annual Cost *.........  $67.5 million...............  $80.2 million...............  $74.4 million                 $92.6 million.
    Annual NOX reduced (tpy)....  28,573......................  26,180......................  28,573                        26,180.
    NOX Limit (lb/MMBtu)........  0.055.......................  0.080.......................  0.055                         0.080.
    Average Cost Effectiveness    $2,369......................  $3,069......................  $2,605                        $3,537.
     ($/ton).
    Incremental Cost              $3,522......................  $4,889......................  $3,899                        $5,695.
     Effectiveness (vs. LNB/
     SOFA) ($/ton).
    Incremental Cost              $3,239......................  $5,357......................  $3,798                        $6,647.
     Effectiveness (vs. SNCR+LNB/
     SOFA) ($/ton).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* EPA's cost effectiveness calculations represent SCR in combination with LNB/SOFA, rather than SCR alone.

    Based on the revised 2013 cost estimates for SCR+LNB/SOFA, the 
revised average cost-effectiveness of SCR+LNB/SOFA is roughly 10 
percent higher (based on EPA's estimates) than the average cost-
effectiveness values

[[Page 46525]]

reported in our Proposed Rule, and roughly 15 percent higher based on 
SRP's estimates.\69\ The 2013 values for average cost-effectiveness of 
SCR+LNB/SOFA based on EPA and SRP estimates are still comparable to the 
range of values determined cost-effective for SCR in other BART 
determinations. For these reasons, EPA continues to consider SCR+LNB/
SOFA as cost-effective at NGS.
---------------------------------------------------------------------------

    \69\ For informational purposes, EPA included the incremental 
cost-effectiveness values of SCR+LNB/SOFA (estimated in 2010 and 
2013) compared to LNB/SOFA and SNCR+LNB/SOFA, but we note that a 
comparison of the percent change in incremental cost-effectiveness 
between 2010 and 2013 is not informative because SRP did not provide 
updated cost estimates (in 2013 dollars) for the other control 
technologies.
---------------------------------------------------------------------------

    Comment: Cost-Effectiveness of Presumptive BART.
    One commenter stated that in establishing presumptive limits in the 
BART Guidelines, EPA recognized that SCR is not cost-effective and that 
combustion controls such as LNB/SOFA represent the most cost-effective 
control options for most boiler types. The commenter pointed out that 
in establishing presumptive limits, EPA considered controls that cost 
less than $1,500 per ton to be cost-effective, and that the cost-
effectiveness for SCR at NGS, which ranges from $3,000 to $6,000 per 
ton based on 2010 estimates, is well above this threshold. The 
commenter concluded that EPA should have rejected SCR and proposed LNB/
SOFA as BART for NGS.
    Response: EPA disagrees with the assertion that the BART Guidelines 
established a threshold for cost-effectiveness against which all future 
BART determinations must compare. In developing the presumptive 
NOX limits for BART in 2005, EPA did not set the cost-
effectiveness values estimated for combustion controls as the threshold 
for determining whether a given control technology was or was not cost-
effective. If EPA had intended the cost-effectiveness values estimated 
in 2005 to represent a threshold for BART, it is reasonable to assume 
that the BART Guidelines would have included those cost-effectiveness 
values as thresholds in Appendix Y, and would have required future cost 
estimates to be presented in 2005 dollars for appropriate comparison to 
the thresholds. The BART Guidelines do not set a numerical definition 
for ``cost-effective'', and the analysis of presumptive limits uses 
cost-effectiveness as a means to broadly compare control technologies, 
not as a threshold for rejecting controls for an individual unit or 
facility that exceed the average cost-effectiveness of combustion 
controls. In addition, as discussed in the RTC, a value of $1,500 per 
ton is not an appropriate or relevant value for determining cost-
effectiveness.
    Comment: Indirect costs should also be considered under Factor 1.
    The Gila River Indian Community asserted that EPA conducted the 
analysis of cost-effectiveness incorrectly by not including the 
indirect costs of the requirements and only considering the direct cost 
of the requirements. The commenter stated that EPA did not give 
sufficient consideration to the high costs to tribes associated with 
indirect impacts of its proposed BART determination.
    Response: EPA disagrees with the assertion that our cost-
effectiveness analysis was incorrect because it did not include 
indirect costs in the assessment of the costs of compliance. The BART 
Guidelines, which States and EPA must follow in BART determinations for 
fossil-fuel fired power plants greater than 750 MW,\70\ focus on the 
direct costs of the pollution control equipment and other capital and 
annual costs associated with the control technology alternatives. The 
BART Guidelines do not require consideration of the cost of potential 
indirect effects of BART control options when assessing the costs of 
compliance. Therefore, EPA disagrees that our analysis for Factor 1 was 
incorrect or incomplete because it did not include indirect costs to 
tribes. EPA further notes that under Factor 2, the energy and non-air 
quality environmental impacts analysis, the BART Guidelines 
specifically require the energy impact analysis to consider direct 
energy impacts (e.g., parasitic load from certain control technologies) 
and to generally exclude indirect energy impacts of controls (e.g., 
energy to produce raw materials for construction of control equipment) 
unless the indirect impact is unusual or significant.
---------------------------------------------------------------------------

    \70\ 40 CFR 51.308(e)(1)(ii)(B).
---------------------------------------------------------------------------

    However, because of the unique relationship between NGS, tribes, 
and tribal water settlement agreements, and to inform our government-
to-government consultation with tribes, EPA did consider potential 
indirect effects of control options to tribes under Factor 2. EPA 
quantified the impact to electricity rates and CAP water rates, and 
also assessed whether installation of SCR would result in electricity 
generation costs at NGS that exceed the cost to purchase power on the 
wholesale market. Therefore, although EPA appropriately did not 
consider indirect costs in our analysis of Factor 1, EPA did include 
consideration of indirect impacts to tribes and other entities in our 
analysis of Factor 2.

C. Comments on Factor 2--Energy and Non-Air Quality Environmental 
Impacts, Including Economic Impacts

    Comment: EPA's Affordability Analysis relied on invalid 
assumptions.
    One commenter submitted a report, prepared by Management 
Information Services, Inc. (MISI report), asserting that EPA made 
several assumptions that underestimated the cost of continuing to 
operate NGS with additional controls, including the assumption that no 
new capital would be deployed at NGS over the next 25 years, the 
assumption that the increase in the annual NGS lease cost would be $15 
million per year (which is lower than actual increase in lease cost of 
$43 million per year that was released after publication of our 
Proposed Rule), and the use of EPA's capital cost estimates for SCR 
instead of the cost estimated by S&L.
    Other commenters asserted that EPA underestimated the cost of 
closing NGS and purchasing power on the wholesale market, by not 
accounting for costs associated with stranded investments and 
decommissioning NGS.
    Response: EPA recognizes the economic importance of NGS to the 
State of Arizona, the Navajo Nation, and the Hopi Tribe. The purpose of 
the Affordability Analysis in our docket was to determine whether the 
control options for BART would have a detrimental impact on the 
competitiveness of NGS in the western power market, affecting whether 
the NGS owners would continue to operate NGS or replace NGS generation 
with less expensive market power. The Affordability Analysis indicated 
that, even if SCR installation was required on all three units at NGS, 
power produced at NGS would remain less expensive than the cost to 
replace power through wholesale purchases. Because utilities will 
generally provide power to their customers in a least-cost manner and 
because NGS, with the installation and operation of SCR, remained the 
less expensive option, EPA determined that the operation and 
installation of SCR, in and of itself, was not likely to force NGS to 
close.
    In response to multiple comments expressing concern related to 
simplifying assumptions or outdated data, EPA updated the Affordability 
Analysis with the most current power market price curves from the U.S. 
Energy Information Administration (EIA) and recent forward power market 
prices in March 2014 and other more current modeling variables. These

[[Page 46526]]

revisions are discussed in more detail in the RTC as well as in 
additional supporting documents.\71\ The updated model results, 
comparing the net present value (NPV) of electricity generation costs 
with air pollution controls installed compared to the costs to purchase 
an equivalent amount of power on the wholesale market, are summarized 
in the RTC. Overall, the combined changes do not change the conclusions 
from the original Affordability Analysis that installing and operating 
SCR at NGS would be less costly than closing NGS and purchasing 
replacement power from the wholesale market.
---------------------------------------------------------------------------

    \71\ See RTC and references therein.
---------------------------------------------------------------------------

    Comment: EPA's failure to appropriately consider the impacts to 
non-Indian agricultural (NIA) water users renders its Factor 2 analysis 
arbitrary, capricious, and an abuse of discretion.
    One commenter stated that, as a result of errors and omissions, 
EPA's Factor 2 analysis is arbitrary, capricious, and an abuse of 
discretion. The commenter asserted that there are several problems with 
the EPA analysis related to NIA users of CAP water, including erroneous 
assumptions, insufficient support for conclusions, failure to consider 
decreased farming profitability and increased unemployment, failure to 
acknowledge the inability of NIA water users to pass along cost 
increases as compared to municipal users, and other factors.
    Response: EPA recognizes that CAP water is an important resource 
for NIA and other users of water in Arizona. As a result, as one of a 
number of discretionary analyses EPA conducted on the indirect impacts 
on major stakeholders, EPA calculated water rate increases to NIA users 
of CAP water and municipal and industrial users of CAP water.
    EPA disagrees that our discussion of impacts to NIA users of CAP 
water renders our Factor 2 analysis arbitrary, capricious, and an abuse 
of discretion. Neither the CAA nor the BART Guidelines require 
consideration of indirect costs or indirect impacts of controls in a 
BART analysis. EPA, nevertheless, included an evaluation of impacts to 
some of the major stakeholders in NGS in our BART analysis under Factor 
2, including NIA users, as consistent with the statement in the BART 
Guidelines that ``the energy impacts analysis may consider . . . 
whether a given alternative would result in significant economic 
disruption or unemployment'' (emphasis added).\72\
---------------------------------------------------------------------------

    \72\ See BART Guidelines at 70 FR 39169 (July 6, 2005).
---------------------------------------------------------------------------

    EPA recognizes that the information we had available to us about 
NIA users of CAP water was limited, and we acknowledged in the TSD to 
our Proposed Rule that we had several questions about CAP and 
groundwater availability to NIA water users. EPA appreciates the 
clarifications and additional information provided by NIA users of CAP 
water during the comment period for our proposals. The additional 
information provided during the comment period about NIA users of CAP 
water does not change our conclusion under Factor 2, that the potential 
economic impacts to tribes argue for flexibility in the compliance 
timeframe for NGS, because this compliance flexibility also benefits 
other stakeholders, including the NIA users of CAP water.
    Comment: EPA must evaluate cumulative economic impact of other 
rulemakings.
    One commenter asserted that the BART proposal must take into 
account the context in which the regional haze rules are being 
implemented and conduct a cumulative impact analysis of all EPA 
rulemakings. The commenter noted that the two remaining copper smelters 
in Arizona are already subject to BART for SO2 and they also 
have to make significant capital investments to comply with other 
regulatory programs and initiatives such as the revised SO2 
NAAQS.
    Response: EPA disagrees with the assertion that we must consider 
the total cost impact of all EPA regulatory requirements in a BART 
analysis. EPA recognizes that other facilities, whose water and 
electricity rates may be affected by our BART determination for NGS, 
may also be subject to BART for their own emissions of visibility-
impairing pollutants. As a general matter, EPA is mindful that 
facilities may be affected by multiple regulatory and program 
activities. We note that BART is a case-by-case determination that is 
based on a source-specific analysis of five factors, which include 
considerations of the unique circumstances of each affected facility, 
as required under the CAA.
    Comment: Impact to the Development Fund.
    One commenter stated that the increased cost of electricity 
generation associated with SCR would reduce the competitiveness of the 
price of NGS power on the wholesale market and therefore reduce the 
revenue that flows into the Development Fund.
    Response: As discussed in our Proposal Rule and TSD, EPA recognizes 
that any electricity owned by Reclamation based on its 24.3 percent 
participation in NGS that is not used by CAP is sold and revenues are 
deposited into the Development Fund.\73\ This fund is authorized to pay 
the delivery portion of the cost of CAP water for certain Indian tribes 
and to pay the cost of constructing delivery systems to bring CAP water 
to certain Indian tribes.\74\ EPA considers the potential economic 
impacts to tribes, including potential impacts to the Development Fund, 
as part of BART factor 2 to support the appropriateness of flexibility 
in the compliance timeframe for NGS.
---------------------------------------------------------------------------

    \73\ See Proposed Rule at 78 FR 8282 (February 5, 2013) and TSD 
at pages 71-72.
    \74\ See Proposed Rule at 78 FR 8283 (February 5, 2013).
---------------------------------------------------------------------------

    Comment: No basis for public health claim.
    One commenter asserted that EPA has no basis for claiming that the 
NOX reductions from NGS would lead to a public health 
benefit. The commenter noted that EPA establishes NAAQS at levels that 
are protective of public health and welfare with an adequate margin of 
safety that accounts for sensitive populations such as children and the 
elderly, and that EPA has never found that any of the areas around NGS 
fail to attain the NAAQS. The commenter asserted that EPA must conduct 
a health risk evaluation that follows the four basic steps of the risk 
assessment process: Hazard identification, dose[hyphen]response, 
exposure assessment, and risk characterization.
    Response: EPA agrees that the purpose of this rule is to reduce 
visibility impairment caused by emissions of NOX from NGS. 
EPA has not conducted a health risk evaluation for this rulemaking that 
attempts to characterize or quantify a public health benefit. Because 
NOX is itself a criteria pollutant that affects public 
health and is also a precursor to ozone and fine particulate matter, 
which are also criteria pollutants that affect public health, we 
consider it reasonable to state that other benefits could exist. We 
also note that EPA does not agree that there are no health benefits 
from reductions in ozone and fine particulate matter below the level of 
the NAAQS. On the contrary, EPA's practice of quantifying these 
benefits in regulatory impact assessments has been strongly supported 
by peer-reviewed science.\75\
---------------------------------------------------------------------------

    \75\ See EPA, 2010, ``Summary of Expert Opinions on the 
Existence of a Threshold in the Concentration-Response Function for 
PM2.5-related Mortality Technical Support Document.'' 
Available from http://www.epa.gov/ttn/ecas/regdata/Benefits/thresholdstsd.pdf.

---------------------------------------------------------------------------

[[Page 46527]]

D. Comments on Factor 3--Existing Controls at NGS

    Comment: EPA failed to consider existing controls.
    Based on EPA's statement in the Proposed Rule that the early 
installation of LNB/SOFA would not influence EPA's BART determination 
and EPA's use of a baseline scenario in the visibility modeling that 
did not include LNB/SOFA, the operator of the Kayenta Mine concluded 
that EPA failed to consider existing controls.
    Response: EPA disagrees with the assertion that we failed to 
consider existing controls. As described in our Proposed Rule and 
consistent with the BART Guidelines (directing BART determinations to 
conduct the five-factor analysis generally using a 2001-2003 baseline) 
EPA evaluated LNB/SOFA as a separate control technology in our BART 
analysis, as well as a technology that can be used in combination with 
post-combustion control technologies (i.e., SNCR and SCR).\76\ We also 
discussed the voluntary installation of LNB/SOFA in 2009-2011 under 
Factor 3: Existing Controls at NGS.\77\
---------------------------------------------------------------------------

    \76\ See Proposed Rule at 78 FR 8280, 8284 and 8285 (February 5, 
2013).
    \77\ Id. at 8284.
---------------------------------------------------------------------------

    As discussed in section 8.5 of the RTC, EPA properly considered 
baseline emissions over the period 2001-2003 in our analysis of cost-
effectiveness and anticipated visibility benefits of controls. 
Therefore, although we did not ``consider existing controls'' in the 
exact manner preferred by the commenter, we appropriately considered 
the existence of LNB/SOFA in Factor 3 of our BART analysis. In 
addition, the ``better than BART'' framework that we used to assess and 
finalize BART alternatives explicitly accounts for the existing LNB/
SOFA.
    Comment: EPA should determine existing controls to be BART.
    Several commenters noted that NGS spent millions of dollars on LNB/
SOFA to reduce NOX emissions to levels below the presumptive 
NOX emission levels in the BART Guidelines.
    One commenter stated that installing LNB/SOFA prior to a 
requirement to do so under the RHR or any other CAA requirement has 
resulted in greater total NOX emission reductions in the 
first regional haze planning period than would be required by the most 
stringent EPA BART determination.
    Response: EPA recognizes that the early and voluntary installation 
of LNB/SOFA on one unit per year in 2009-2011 at NGS resulted in 
significant emission reductions from NGS. EPA agrees that the early 
installation of LNB/SOFA on one unit per year was voluntary and 
resulted in significant NOX reductions in the first planning 
period for Regional Haze. However, based on our five-factor analysis, 
we have determined that SCR+LNB/SOFA is also cost-effective and would 
result in significant additional visibility improvement at a number of 
Class I areas. We therefore disagree that LNB/SOFA should be determined 
BART for NGS.

E. Comments on Factor 5--Anticipated Visibility Benefits

    Comment: General Comments on Visibility.
    Numerous commenters questioned the extent to which NGS impacts 
visibility at Class I areas or disputed EPA's analysis that 
installation of SCR at NGS would improve visibility. Many commenters 
asserted that the haze is produced from emissions from other sources.
    Some commenters stated that the wind near and around the Grand 
Canyon blows predominantly west to east; thus, emissions from the NGS 
are pushed away from several Class I areas, not towards them.
    Response: We are aware of the studies cited by commenters 
purporting to show that controls on NGS would yield little visibility 
improvement, and we address them in section 7.0 of the RTC. We are also 
aware of work performed by the Western Regional Air Partnership (WRAP) 
suggesting that the relative contribution of nitrate from point sources 
to visibility impacts is relatively small.\78\ The CAA and RHR require 
that BART be installed on certain old, large stationary sources as part 
of the overall approach to improving visibility at Class I areas. No 
control at an individual source will be sufficient to meet the goal of 
remedying existing impairment of visibility in mandatory class I 
Federal areas which result from manmade air pollution, as set out in 
section 169A of the CAA.
---------------------------------------------------------------------------

    \78\ See, e.g. WRAP PM Source Apportionment Technology (PSAT) 
results, available on WRAP Technical Support System, Source 
Apportionment Web page at http://vista.cira.colostate.edu/TSS/Results/SA.aspx.
---------------------------------------------------------------------------

    On the issue of wind direction, we note that the CALPUFF modeling 
uses three years of hourly meteorological input, which is based on 
meteorological modeling as well as observational data from stations 
throughout a large area. The input includes wind speed and direction, 
and would include the particular wind direction patterns noted by the 
commenter. The more sophisticated meteorological treatment in CALPUFF 
enables it to track the pollutant plume from NGS, including its twists 
and turns over multiple days. We consider this approach to adequately 
account for variability in winds noted by the commenter.
    Comment: EPA underestimated visibility benefits of SCR.
    One commenter stated that the visibility benefits of SCR are 
greater than those modeled by EPA because EPA underestimated SCR 
performance and because EPA overestimated the potential increase in 
sulfate emissions that may come with the addition of SCR controls by 
assuming an SO2 to SO3 conversion rate that is 
too high and using an erroneous value for the coal sulfur content. The 
commenter stated that its own modeling shows greater visibility 
improvement than demonstrated by EPA.
    Response: We disagree that EPA underestimated the visibility 
benefits of SCR and we note that the commenter's assertion that the 
visibility benefits are even better would not change our proposed 
determination under Factor 5 that the anticipated visibility benefits 
of SCR+LNB/SOFA are significant and support our proposed BART limit for 
NOX, achievable with SCR+LNB/SOFA. Please see the RTC for a 
detailed discussion of EPA's responses to the commenter's specific 
assertions.
    Comment: EPA overestimated visibility impact of NGS by using 
background ammonia concentrations that were too high.
    Several commenters argued that EPA's assumed ammonia background 
concentration of 1 part per billion (ppb), the default value 
recommended by the Interagency Workgroup on Air Quality Modeling 
(IWAQM), is unrealistically high compared to measured values in the 
area, resulting in artificially high model projections of visibility 
impacts, particularly in the winter.\79\ The commenter noted that the 
use of a constant value of 1.0 ppb for background ammonia concentration 
fails to account for known variations in monthly or seasonal ammonia 
concentration.
---------------------------------------------------------------------------

    \79\ Interagency Workgroup On Air Quality Modeling (IWAQM) Phase 
2 Summary Report And Recommendations For Modeling Long Range 
Transport Impacts (EPA-454/R-98-019), EPA OAQPS, December 1998, 
http://www.epa.gov/scram001/7thconf/calpuff/phase2.pdf.
---------------------------------------------------------------------------

    One commenter cited an analysis conducted on behalf of SRP by AECOM 
and Dr. Ivar Tombach. The commenter stated that the Tombach study 
compared modeled predictions of

[[Page 46528]]

ammonium nitrates using both EPA's and AECOM's ammonia background 
concentrations to measured ammonia values, demonstrating that the EPA's 
assumptions over-predict actual measured values by a factor of 10 or 
more in some cases.
    One commenter noted that when the IWAQM guidance was issued 14 
years ago, CALPUFF did not have the capability of accommodating monthly 
ammonia background concentrations as it has since been updated to do. 
The commenter asserted that EPA's reliance on a constant value is an 
outdated approach.
    Response: EPA has already considered and addressed the same 
arguments and data provided by commenters related to background ammonia 
concentrations in other rulemakings, including our final rule for Four 
Corners Power Plant.\80\ As summarized briefly below, EPA disagrees 
that our use of the IWAQM default background ammonia concentration for 
arid areas of 1 ppb was inappropriate. Please see the RTC for the full 
response to this comment.
---------------------------------------------------------------------------

    \80\ See RTC and references therein.
---------------------------------------------------------------------------

    We have carefully reviewed the comments and concluded that, on 
balance, the evidence does not support using lower values for 
background ammonia concentrations, as argued by the commenters, in 
estimating the visibility impacts from NGS. Much of the existing 
measured data cited by the commenters is from other states and may not 
be representative for evaluating visibility impacts from NGS.\81\ 
Further, existing data sometimes represent ammonia alone rather than 
total ammonia and ammonium. Because ammonium represents part of the 
pool of ammonia that could be available to interact with the 
SO2 and NOX emitted from stationary sources, it 
should be accounted for in the value for background ammonia 
concentrations used in the model. In several of the research papers 
cited by commenters, the amount of measured ammonium is comparable to 
and at times much greater than the amount of ammonia.\82\ Measurements 
made by SRP closer to NGS over December 2009 to April 2010, which 
included ammonia and ammonium, showed that depending on time and 
location, typical ammonia concentrations ranged from 0.2 ppb to 0.8 ppb 
and the concentration of total ammonia and ammonium ranged from 0.6 to 
1.2 ppb, which is considerably higher than the 0.2 ppb winter values 
used in SRP's modeling.\83\ Although some of the ammonium may not be 
available to interact with pollutants from NGS, the sum of ammonia and 
ammonium provides an upper bound estimate of background ammonia 
concentrations, and represents a conservative estimate for modeling.
---------------------------------------------------------------------------

    \81\ See e.g., SRP comments Appendix G, ``Measurements of 
Ambient Background Ammonia on the Colorado Plateau and Visibility 
Modeling Implications'', Prepared by Salt River Project, 
Contributors: Ivar Tombach and Robert Paine, September 2010. 
Referred to here as ``SRP monitoring report'', or Tombach & Paine 
2010.
    \82\ See RTC and references therein.
    \83\ SRP monitoring report, or Tombach & Paine 2010, and SRP 
comments Appendix C. ``Revised BART Analysis for the Navajo 
Generation Station Units 1-3'' (January 2009) and Appendix I. 
``Visibility Modeling Using Upgraded CALPUFF Model'' (February 
2011).
---------------------------------------------------------------------------

    We further note that there are measurements of gaseous ammonia 
alone that show concentrations close to or greater than the 
concentration of 1 ppb, even in winter when ammonia concentrations are 
expected to be lowest. Winter measurements, representing 3-week 
averages, ranged from 1.1 ppb to 1.8 ppb at a monitor at the Farmington 
Airport in northwestern New Mexico.\84\ Measurements from the winters 
of 2011-2013 from the AMoN network ranged from 1.1 to 1.3 ppb for 
Farmington, and 0.7-0.9 ppb for Chiricahua, in southeastern 
Arizona.\85\
---------------------------------------------------------------------------

    \84\ See RTC and references therein.
    \85\ Id.
---------------------------------------------------------------------------

    We further note that there is significant variability in the 
concentrations of ammonia measured at different times and places. Even 
the SRP monitoring report (Tombach & Paine, 2010, cited above) 
describes a surprisingly high spatial variability in ammonia 
concentrations. Because of the variability and its unknown causes, the 
data collected for SRP did not lead to a clear picture of appropriate 
and representative background ammonia concentrations to use with 
CALPUFF.
    Finally, we note that using the background ammonia concentrations 
recommended by commenters does not change our conclusion under Factor 5 
because CALPUFF modeling of SCR shows substantial visibility benefits 
even using the alternative assumptions.\86\ Using a background ammonia 
concentration of 1 ppb ammonia, EPA modeled the greatest benefit from 
SCR+LNB/SOFA to be 5.4 deciviews at Capitol Reef NP, and modeled a 
visibility benefit exceeding 1 to 2 deciviews at ten additional Class I 
areas. Using the ammonia concentration recommended by some commenters 
(ranging from 0.2 ppb in winter to 1.0 ppb in summer), EPA modeled the 
greatest benefit of SCR to be 2.3 dv, and modeled a visibility benefit 
exceeding 1 deciview at nine Class I areas, with three of these nine 
areas having a benefit of approximately two deciviews. Even assuming a 
lower ammonia concentration, the modeling demonstrates that the 
installation of SCR+LNB/SOFA at NGS would have a significant beneficial 
impact on visibility at a number of Class I areas. Our conclusion as to 
the appropriate BART Benchmark for NGS would not accordingly change.
---------------------------------------------------------------------------

    \86\ See RTC and references therein.
---------------------------------------------------------------------------

    Comment: EPA should have used an updated version of CALPUFF.
    Several commenters asserted that EPA erred in using CALPUFF version 
5.8 in its modeling rather than the more recent CALPUFF version 6.42, 
released by TRC. One commenter argued that CALPUFF version 6.42 
predicts lower visibility benefits than version 5.8.
    Response: We disagree with the commenters that a new CALPUFF 
version should be used for the BART determination. We relied on version 
5.8 of CALPUFF because it is the version approved by EPA through a 
public notice and comment rulemaking, in accordance with the Guideline 
on Air Quality Models (``GAQM'', 40 CFR part 51, Appendix W, section 
6.2.1.e).\87\ CALPUFF version 6.4 is not approved by EPA for regulatory 
purposes, and we do not agree that the changes made to this most recent 
version of CALPUFF were simple model updates to address bugs. A full 
evaluation of a new model such as CALPUFF version 6.4 is needed before 
it should be used for regulatory purposes as errors that are not 
immediately apparent can be introduced along with new model features.
---------------------------------------------------------------------------

    \87\ See RTC and references therein.
---------------------------------------------------------------------------

    Comment: Closure of Mohave Project did not improve visibility and 
shows CALPUFF is unreliable.
    One commenter discussed the findings of an analysis conducted after 
the closure of the Mohave Power Project (MPP) (a 1,580 MW coal-fired 
power plant) to evaluate whether the closure had resulted in improved 
visibility in Grand Canyon National Park.\88\ The commenter indicated 
that although CALPUFF version 5.8 modeling predicted that the plant had 
a significant impact on visibility in the Grand Canyon, this study 
concluded that there was ``virtually no evidence that the MPP closure 
improved visibility in the Grand Canyon.'' The commenter asserted that 
this study raises questions about the reliability of CALPUFF.
---------------------------------------------------------------------------

    \88\ See RTC and references therein.
---------------------------------------------------------------------------

    Response: We disagree that the Terhorst & Berkman (T&B) study cited 
by the commenters raises questions about CALPUFF's reliability. The

[[Page 46529]]

conclusion in the T&B study on the effect of MPP closure is actually 
similar to that from earlier analyses, which also predicted 
improvements less than the human perceptibility threshold of 1 dv. A 
response to the T&B study written by White et al., stated that the T&B 
analysis is ``misleadingly presented as discrediting previous studies 
and their interpretation by regulators. In reality the T&B analysis 
validates a consensus on MPP's visibility impact that was established 
years before its closure.'' \89\
---------------------------------------------------------------------------

    \89\ W.H. White, R.J. Farber, W.C. Malm, M. Nuttall, M.L. 
Pitchford, B.A. Schichtel, Comment on ``Effect of coal-fired power 
generation on visibility in a nearby national park (Terhorst and 
Berkman, 2010)'', Atmospheric Environment 55 (2012) 173-178. 
doi:10.1016/j.atmosenv.2012.02.076. Also available at: http://www.dri.edu/marc-pitchford?showall=&start=2.
---------------------------------------------------------------------------

    White et al., explicitly addressed the purported disagreement 
between the T&B methodology and results from CALPUFF, pointing out that 
the comparison was flawed in several ways. First, the ambient data 
relied upon by T&B are collected only every third day; this results in 
an insufficient number of days for a valid statistical comparison to 
the 98th percentile results reported from CALPUFF. Another important 
flaw is that when T&B translated visibility extinction into deciviews, 
they used recent polluted conditions as the background for comparison, 
whereas the BART Guidelines and the CALPUFF results use natural 
conditions as background.\90\ When the T&B results are computed using 
natural background, they are substantially larger, and generally in 
agreement with CALPUFF results.
---------------------------------------------------------------------------

    \90\ EPA considered and rejected comments on the proposed BART 
Guidelines that visibility impacts should be evaluated relative to 
current degraded visibility conditions and concluded that ``[u]sing 
existing conditions as the baseline for single source visibility 
impact determinations would create the following paradox: The 
dirtier the existing air, the less likely it would be that any 
control is required.'' (70 FR 39104 at 39124, July 6, 2005).
---------------------------------------------------------------------------

F. Comments on BART Determination for NOX

    Comment: BART limit for NGS should be 0.04 lb/MMBtu.
    One commenter argued that the final BART emission limit should be 
more stringent and no higher than 0.04 lb/MMBtu. The comment noted that 
permitting authorities have required lower NOX limits than 
0.055 lb/MMBtu in recent BACT determinations based on SCR in 
combination with combustion controls.
    Response: EPA disagrees with the commenter that the BART Benchmark 
for NGS should be 0.04 lb/MMBtu. We note that the commenter has not 
provided any specific information to show that NGS could demonstrate 
continuous compliance with an emission limit of 0.04 lb/MMBtu. The 
commenter generally argued that SCR systems are typically designed to 
achieve 90 percent removal. EPA notes that although an SCR system can 
be designed to a specific target, the design target is typically not 
equivalent to the actual emission limit.\91\ EPA proposed a limit of 
0.055 lb/MMBtu achievable with SCR+LNB/SOFA, and using a baseline 
emission rate of 0.35 lb/MMBtu, this represents a removal efficiency of 
84 percent.\92\ However, as noted elsewhere in the RTC, the limit of 
0.055 lb/MMBtu, which accommodates startup, shutdown, and low-load 
operation, is based on a design target of 0.03 lb/MMBtu. This 
represents a design target removal efficiency of 91 percent for 
SCR+LNB/SOFA (from a baseline of 0.35 lb/MMBtu), or 88 percent for SCR 
alone (i.e., from 0.24 lb/MMBtu).
---------------------------------------------------------------------------

    \91\ EPA's Environmental Appeals Board has recognized that PSD 
emission limits must be set to allow fluctuations in operations, 
stating: ``To account for these possibilities, a permitting 
authority must be allowed a certain degree of discretion to set the 
emissions limitation at a level that does not necessarily reflect 
the highest possible control efficiency, but will allow the 
permittee to achieve compliance consistently.'' In Re Masonite 
Corporation, 5 E.A.D. 551, 560-61 (1994).
    \92\ See RTC and references therein.
---------------------------------------------------------------------------

    EPA disagrees with the commenter's assertion that emission limits 
associated with BART must meet BACT or the lowest emission rate ever 
achieved with that technology at any coal-fired power plant. The BART 
Guidelines state that: ``[i]n assessing the capability of the control 
alternative, latitude exists to consider special circumstances 
pertinent to the specific source under review, or regarding the prior 
application of the control alternative'', (70 FR 39166) and that ``[t]o 
complete the BART process, you must establish enforceable emission 
limits that reflect the BART requirements . . .'' (70 FR 39172). The 
five-factor BART analysis described in the Guidelines is a case-by-case 
analysis that considers site specific factors in assessing the best 
technology for continuous emission controls. After a technology is 
determined as BART, the BART Guidelines require establishment of an 
emission limit that reflects the BART requirements, but does not 
specify that the emission limit must represent the maximum level of 
control achieved by the technology selected as BART. For these reasons, 
EPA is not using the lower limit recommended by the commenter in 
setting the BART Benchmark.
    Comment: BART limit for NGS should be in the range of 0.07-0.08 lb/
MMBtu.
    Several commenters asserted that the NOX emission limit 
EPA proposed for NGS is unachievable. One commenter noted that the 
averaging period for the proposed limit of 0.055 lb/MMBtu includes 
periods when the SCR is unable to operate such as startup, shutdown, 
and periods of load-cycling. The commenter made the following 
arguments: (1) The S&L analysis submitted by the commenter shows that 
the proposed emission limit is unachievable on a continuous basis; (2) 
the NOX emissions achieved in other SCR retrofit situations 
do not justify the proposed emission limit.
    Response: EPA disagrees with the commenter that the limit used in 
setting the BART Benchmark for NGS should be higher than our proposed 
limit of 0.055 lb/MMBtu, in the range of 0.07 to 0.08 lb/MMBtu.\93\
---------------------------------------------------------------------------

    \93\ The response included in this Final Rule is abbreviated and 
excludes the graphs and tables EPA generated to support our 
response. For additional detail, please see the RTC.
---------------------------------------------------------------------------

    The S&L report generally argues that because the emission limit is 
established based on a 30-BOD average basis, the proposed emission 
limit of 0.055 lb/MMBtu is not consistently achievable at NGS. The S&L 
analysis is based on a design target of 0.03 lb/MMBtu and suggests an 
emission limit in the range of 0.07-0.08 lb/MMBtu would be required to 
accommodate periods of load-cycling operation, startups, and shutdowns. 
S&L is recommending a limit that is 2.3 to 2.7 times higher than the 
design target, or a compliance margin of 133 to 167 percent.
    The S&L report discusses the temperature limitations associated 
with SCR and explains that at temperatures below a specific minimum 
operating temperature, a component of the SCR system (i.e., ammonia 
injection) must cease to prevent ammonium salt formation on the 
catalyst. S&L asserts that a minimum operating temperature of 
580[emsp14][deg]F is typical for retrofit SCR control systems installed 
on coal-fired electric generating units with similar coal sulfur 
content and states that this temperature corresponds with a gross load 
of approximately 650 MW (650 gross MW, or MWg). S&L further assumes 
that SRP will likely modify the units to increase flue gas temperatures 
at lower operating loads by installing one of several options for low 
load temperature control. In their analysis, S&L assumes the low load 
temperature control would be achieved with a water-side bypass (to 
allow water to bypass the economizer tube bundles during low-load 
operation). The S&L report

[[Page 46530]]

states ``[b]ased on a preliminary review of the available systems, a 
water-side bypass system should be capable of increasing the 
temperature of the bulk flue gas by approximately 25[emsp14][deg]F to 
65[emsp14][deg]F during low-load operation. For this evaluation, a low-
load temperature control system capable of achieving a temperature 
increase of 65[emsp14][deg]F during low-load operations was assumed for 
modeling purposes.'' S&L further estimates that this would correspond 
to a minimum gross load of 450 MWg for the SCR to operate, or operation 
at 55 percent capacity.
    Using the assumption that the SCR would not operate at loads below 
450 MWg, S&L used 2012 operations data at NGS to estimate emission 
rates at NGS assuming a design target of 0.03 lb/MMBtu with actual 
steady-state operations achieving 0.04 lb/MMBtu. S&L modeled eighteen 
different operating scenarios and identified seven scenarios, which 
included periods of low load cycling along with unit startup and 
shutdowns, that resulted in the maximum 30-BOD average for each unit 
and facility-wide, that exceeded 0.055 lb/MMBtu. The highest 30-BOD 
average S&L modeled was 0.077 lb/MMBtu for Unit 2, achieved under 3 
different operating scenarios involving low-load cycling.
    SRP and S&L did not provide the underlying data used in the S&L 
analysis. Therefore, EPA evaluated the S&L report by reviewing 
emissions data from the EPA Air Markets Program Data (AMPD) for 
multiple years, as well as emissions data from other facilities that 
were constructed or retrofit with SCR. EPA sought to understand 2012 
operations at NGS within the context of longer term operational trends 
at the facility, as well as understand the minimum operating load 
assumed by S&L for NGS within the context of minimum operating loads at 
other facilities with SCR.
    EPA evaluated the reported hourly gross load operating data for 
Units 1-3 at NGS for the years 2001, 2003, 2010, 2011, 2012, and 
2013.\94\ Emission data from AMPD show that NGS, and in particular, 
Unit 2, spent a higher percentage of operating hours at gross loads 
below 450 MWg in 2012 compared to other years. The 2012 gross load 
profiles for Unit 2 (as well as Units 1 and 3) are characteristic of 
load-cycling units, with significant periods of time below the 
purported SCR minimum operating load of 450 MWg, particularly in the 
spring. Please see the RTC for more detail. In 2010, Unit 2 also 
operated for significant periods of time at loads below 450 MWg. 
However, these periods in 2010 occurred following the major outage on 
Unit 2 (following installation of LNB/SOFA on that unit). Although 
Units 1-3 at NGS did appear to operate as load-cycling units and 
operated below 450 MWg for significant periods of time in 2012, this 
type of operation does not appear to be characteristic of typical 
operation at NGS, based on our evaluation of previous years, as well as 
2013.
---------------------------------------------------------------------------

    \94\ See RTC and references therein.
---------------------------------------------------------------------------

    Based on the gross load operating profiles for six years, EPA 
estimated the rolling 30-BOD averages for each BOD to determine whether 
the operating profiles (which included actual startup, shutdown, and 
load-cycling in each year) would result in 30-BOD averages that would 
exceed 0.055 lb/MMBtu. Based on our analysis, EPA projected the highest 
30-BOD average to be 0.079 lb/MMBtu (Unit 2 in 2010). Using 2012 data, 
representative of load-cycling operation, EPA projected the highest 30-
BOD average to also occur on Unit 2 (0.075 lb/MMBtu). Similarly, S&L 
projected the highest 30-BOD average in 2012 was from Unit 2, at 0.077 
lb/MMBtu. Therefore, although the scenarios modeled by S&L and EPA were 
not identical, the highest 30-BOD averages projected by EPA and S&L, 
using similar starting assumptions, were comparable. Our analysis, of 
projected SCR performance, which included emission and operating 
profiles of actual startup and shutdown events, and load-cycling in 
various years, showed that Unit 3 was not projected to exceed 0.055 lb/
MMBtu in any of the evaluated years, and that there were several years 
within these six selected years that Units 1 and 2 would also not 
exceed 0.055 lb/MMBtu.
    The analysis of projected 30-BOD average emission rates assumes 
that S&L's value of 450 MWg (or 55 percent capacity) for the minimum 
operating load to operate SCR at NGS is correct. EPA notes that 450 MWg 
was a value that S&L assumed based on preliminary analysis of available 
low load temperature control systems. SRP submitted a similar S&L 
analysis to EPA for Units 1 and 3 at Coronado Generating Station 
(CGS).\95\ Units 1 and 2 at CGS are 430 MWg Riley-Turbo units that 
typically operate as load-cycling units. CGS burns low-sulfur coal from 
the Powder River Basin (PRB coal). With the application of low-load 
temperature controls on these units, S&L's analysis suggests that the 
minimum operation load for SCR on Units 1 and 2 at CGS would be 138 MWg 
(or 32 percent capacity). This is significantly lower than the 55 
percent capacity S&L assumed for NGS. S&L stated that the coal sulfur 
content will affect the minimum operating load for SCR. NGS does not 
burn PRB coal; however, NGS does burn low-sulfur coal from the Kayenta 
Mine. AECOM, SRP's consultant for visibility modeling, reported the 
maximum sulfur content of the coal as 0.593 percent based on daily data 
for the 2001-2003 period. For comparison, various sources reference PRB 
coal as generally low-sulfur coal with a sulfur content of less than 1 
percent, or a mean of 0.5 percent.\96\ In contrast, high sulfur coal is 
typically above 3 percent.\97\
---------------------------------------------------------------------------

    \95\ See RTC and references therein.
    \96\ See, for example, publication from the U.S. Geological 
Survey, figure PQ-4 and Table PQ-1, available at http://pubs.usgs.gov/pp/p1625a/Chapters/PQ.pdf.
    \97\ Id.
---------------------------------------------------------------------------

    EPA evaluated emission data of eight well-performing units burning 
PRB coal and generated empirical estimates for minimum operating loads 
and capacity requirements for SCR operation at those facilities. Based 
on this analysis (see RTC for further detail), EPA estimated capacity 
requirements for SCR operation that ranged from 35 percent to 46 
percent, with an average value of 40 percent. Using the average (40 
percent) and the maximum (46 percent) capacity requirement to operate 
SCR, EPA projected that NGS would meet a limit of 0.055 lb/MMBtu (on a 
30-BOD average) for all but 3 cases (i.e., Units 1 and 2 in 2012, and 
Unit 2 in 2010) under the 46 percent capacity requirement. Under the 40 
percent capacity requirement to run SCR, Units 1 and 2 in 2012 would 
remain below 0.055 lb/MMBtu and for Unit 2 in 2012 the highest 30-BOD 
average was projected to be exactly 0.055 lb/MMBtu. Operation of Unit 2 
in 2010 was not typical of normal operation. Please see RTC for more 
detail on this analysis.
    The S&L report concludes that even with a design target for SCR of 
0.03 lb/MMBtu, a limit of 0.07-0.08 lb/MMBtu is required to accommodate 
periods of startup, shutdown, and load-cycling operation. EPA agrees 
that load-cycling operation appears to be an important factor; however, 
EPA concludes that the critical S&L assumption, that the units at NGS 
must operate at approximately 55 percent capacity in order for the SCR 
to operate, was not sufficiently supported and was acknowledged by S&L 
to be an assumption based on a preliminary review of available low-load 
temperature control systems. EPA also notes that in the S&L revised 
2013 cost analysis, S&L included costs for hot water recirculation 
systems which

[[Page 46531]]

``maintains SCR in operation at all plant operating loads'' (emphasis 
added).\98\
---------------------------------------------------------------------------

    \98\ See page 1-2 of the Sargent and Lundy report prepared for 
SRP, dated January 2, 2014, included as Appendix U to the SRP 
comment letter in the docket for this rulemaking.
---------------------------------------------------------------------------

    In summary, EPA is finalizing a BART Benchmark based on an emission 
limit for NGS of 0.055 lb/MMBtu on a rolling 30-BOD basis. In 
determining the achievability of this limit, EPA has conducted an 
analysis that considers actual periods of startup, shutdown, and low-
load cycling. Based on the understanding that S&L would design the SCR 
system at NGS to a design target of 0.03 lb/MMBtu, the BART limit of 
0.055 lb/MMBtu represents an adequate compliance margin to accommodate 
periods of startup, shutdown, and load-cycling operation.
    Comment: Presumptive Limit for NOX.
    Several commenters noted that with existing LNB/SOFA controls, NGS 
emits NOX at rates below the presumptive limit of 0.28 lb/
MMBtu established by the EPA in the BART Guidelines. A commenter stated 
that to properly justify departure from the presumptive BART limit, EPA 
must evaluate the impacts of the presumptive BART limit in its five-
factor analysis.
    Response: EPA disagrees with the comment that installation of LNB/
SOFA at NGS should satisfy BART simply because it meets the presumptive 
limit for NOX of 0.28 lb/MMBtu in the BART Guidelines for 
tangential-fired boilers burning bituminous coal. Presumptive BART 
limits, and the corresponding technology upon which those limits are 
based, do not preclude states or EPA from setting limits that differ 
from those presumptions based on case-specific consideration of the 
relevant BART factors. The presumptive limits generally represent a 
minimum level of control for BART for various types of power plants, 
based on EPA's assessment of the typical costs of controls and likely 
visibility benefits.\99\ EPA further disagrees with the assertion that 
we did not evaluate the impacts of the presumptive BART limit in our 
five-factor analysis. The presumptive BART limit of 0.28 lb/MMBtu is 
based on the installation and operation of modern combustion controls. 
EPA evaluated LNB/SOFA (at a limit of 0.24 lb/MMBtu, which is each 
unit's existing permitted NOX limit for operation with LNB/
SOFA) in the five-factor analysis on which our proposed rule was based. 
Please see our RTC for a detailed discussion.
---------------------------------------------------------------------------

    \99\ See 77 FR 14604, 14608-14610 (March 12, 2012) for a 
detailed discussion of the presumptive limits.
---------------------------------------------------------------------------

    Comment: Install SCR within 3.5 years.
    One commenter stated that the CAA requirement for BART to be 
installed ``as expeditiously as practicable'' requires installation and 
full implementation of SCR on all three units at NGS within 3.5 years 
rather than five years. The commenter stated that EPA provided no site-
specific factors at NGS that would require a longer-than-average 
installation time for SCR (particularly in light of the fact that it 
appears contractors in the region will not be overwhelmed).
    Response: EPA disagrees with the commenter that a 3.5-year 
compliance deadline for the installation of SCR would be practicable 
for NGS. EPA agrees that there are numerous sources of information, 
including EPA's response to comments on its BART determination for 
SJGS, to suggest that on average, the time required to design and 
construct an SCR system can range from 37 to 43 months. The commenter 
also cites EPA documents suggesting that it generally takes 21 months 
to design, install, and test one SCR unit, and 35 months for SCR 
installation at power plants with multiple SCR units, and another 
publication that suggests that SCR can be installed in less than five 
years (i.e., document from The Brattle Group). Our RTC contains a 
detailed discussion of our conclusion that the Brattle Group estimate 
of 47 months (nearly 4 years) applies to one unit, not multiple units 
at one facility.\100\
---------------------------------------------------------------------------

    \100\ See May 2012 Brattle Group document, page 12 and page 17, 
in the docket for this rule.
---------------------------------------------------------------------------

    In addition, although EPA cited one facility where the retrofit of 
seven units required 35 months, EPA also stated ``ideally, longer than 
35 months would allow for all the retrofits to occur over a period of 
several years so that facility owners can properly plan outages and 
suppliers can properly plan for resource availability.'' \101\
---------------------------------------------------------------------------

    \101\ See EPA 2002 Multipollutant Strategies document, page 22, 
in the docket for this rule.
---------------------------------------------------------------------------

    The commenter also states that ``it appears contractors in the 
region will not be overwhelmed'' to justify why installation time for 
SCR should not be longer than average.\102\ We note that ``installation 
time'' is one part of compliance, and that EPA must also consider time 
for design, procurement, and permitting. We also note that the 
commenter did not provide any support for its statement that 
contractors in the region will not be overwhelmed. We note that several 
EGUs in the southwest have compliance dates for the installation of SCR 
around 2018.\103\ Therefore, EPA anticipates that leading up to 2018, 
numerous coal-fired EGUs in the region will be retrofited with post-
combustion controls.
---------------------------------------------------------------------------

    \102\ See page 17 of the EarthJustice comment letter, in the 
docket for this rule.
    \103\ See Final BART FIP for Four Corners Power Plant an 
compliance dates under the BART Alternative at 77 FR 51620 at 51648 
(August 24, 2012) and Final Regional Haze FIP for Arizona (phase 1) 
at 77 FR 72512 at 72578 (December 5, 2012).
---------------------------------------------------------------------------

    In taking action to finalize a BART Benchmark, EPA is retaining the 
five year compliance period as proposed. Because BART compliance at NGS 
involves the design, procurement, and installation of SCR on three 
units and upcoming ownership changes at NGS as discussed in our 
proposed rule, EPA is determining that a five-year BART compliance 
timeframe at NGS is as expeditious as practicable. This is within the 
range cited by the commenters and the facility operator (i.e., average 
of 21 to 47 months per unit, or 35 months to 67 months for multiple 
units at one facility) and is consistent with the CAA which requires 
BART compliance as expeditiously as practicable but no later than five 
years following the effective date of the final rule.\104\
---------------------------------------------------------------------------

    \104\ See section 169A of the CAA (sections 169A(b)(2)(A) and 
(g)(4)).
---------------------------------------------------------------------------

G. Comments on BART for PM

    Comment: Support/opposition for finding not to establish PM BART.
    Several commenters supported EPA's statement in the Proposed Rule 
that ``[b]ecause emissions of PM are well controlled at NGS through 
federally enforceable limits, EPA is not proposing that it is 
``necessary or appropriate'' under the TAR to determine BART for PM 
emissions at NGS.''
    Some commenters noted that implementation of the Mercury and Air 
Toxics Standards (MATS) in the near future will establish an additional 
federally enforceable limit for PM of 0.03 lb/MMBtu. The commenters 
added that the BART Guidelines provide that one can generally rely on 
MACT standards for purposes of BART.
    In contrast, two commenters asserted that EPA was incorrect to 
determine that it need not evaluate BART for control of PM at NGS. The 
commenter asserts that the existing PM limit of 0.06 lb/MMBtu was not 
based on a BART analysis and does not reflect a well-controlled PM 
emission rate for a coal-fired EGU.
    One commenter asserted that the electrostatic precipitators (ESPs) 
at NGS do not represent the best system of control for PM. The 
commenter believes that EPA's determination is inconsistent with recent 
BART and BACT

[[Page 46532]]

determinations for coal-fired utility boilers that set emissions limits 
for PM of 0.015 lb/MMBtu or lower based on the use of fabric filter 
baghouses. The commenter concluded that EPA should revise its 
determination and complete a BART analysis for PM that includes 
evaluation of fabric filter baghouses.
    Response: EPA agrees with the comment that it is not necessary or 
appropriate to require BART for PM emissions from NGS at this time. As 
we stated in our proposed rule: ``Emissions of PM and SO2 
are controlled by hot-side electrostatic precipitators (HS-ESPs) and 
wet scrubbers, respectively.'' \105\ Because NGS will be required to 
comply with the PM emissions limits in the MATS rule, EPA continues to 
find that it is not necessary or appropriate at this time to promulgate 
a BART emission limit for PM from NGS. EPA is not determining that the 
existing PM emission limit for NGS is BART. Instead, it is EPA's 
position that it is not necessary or appropriate under our 
discretionary authority under the TAR, promulgated at 40 CFR 49.11, to 
conduct a BART determination for PM emissions because they are 
currently well-controlled and will be further reduced by compliance 
with the 0.03 lb/MMBtu emission limit in the MATS rule.
---------------------------------------------------------------------------

    \105\ 78 FR 8279 (February 5, 2013).
---------------------------------------------------------------------------

    One commenter asserted that EPA should require fabric filter 
baghouses as BART for PM. EPA cannot agree or disagree that baghouses 
would be required as BART for PM because, as described above, we have 
determined that it is not necessary or appropriate at this time to 
conduct a BART determination for PM at NGS.

H. Comments on BART for SO2

    Comment: Support for finding that Reasonable Progress is met for 
SO2.
    Several commenters noted that EPA recognized in the Proposed Rule 
that the emission limits EPA established for SO2 in 1991 
were determined to achieve greater reasonable progress than would BART. 
Several commenters agreed that no additional emission limits or 
controls should be required as a result of BART for SO2 
emissions. One commenter noted that the existing SO2 limit 
at NGS is more stringent than the BART Guidelines' presumptive 
SO2 limit.
    Response: EPA agrees with these comments. As EPA stated in our 
proposal in February 2013, the SO2 emissions limit 
established in EPA's 1991 SO2 FIP was determined to be 
better than BART under the visibility regulations addressing reasonably 
attributable visibility impairment. Specifically, EPA determined that 
promulgating a SO2 emission limit of 0.10 lb/MMBtu on an 
annual average basis would result in greater cumulative SO2 
emissions reductions and visibility improvement over time than would 
the SO2 BART limit that EPA had proposed for NGS. NGS 
installed a wet flue gas desulfurization system to reduce 
SO2 emissions on each of its boilers in 1997-1999.\106\
---------------------------------------------------------------------------

    \106\ EPA initially codified the requirements for NGS to meet an 
SO2 emission limit in an existing FIP for the State of 
Arizona. See 40 CFR 52.145. After promulgation of the TAR, EPA moved 
the NGS SO2 FIP to 40 CFR 49.5513
---------------------------------------------------------------------------

I. Comments on EPA's BART Alternative

    Comment: Support for EPA's authority for ``better than BART.''
    Several commenters discussed and supported EPA's policy and legal 
rationale for its discretion to approve ``better than BART'' 
alternatives and to provide an extended period for implementation of 
such an alternative at NGS. One commenter also opined that the 
5[hyphen]year compliance period for BART that is defined in section 
169A(g)(4) of the CAA applies by its terms only to: (1) SIPs, by 
providing that the BART compliance date shall be no later than ``five 
years after the date of approval of a plan revision under this 
section''; and (2) FIPs promulgated under CAA section 110(c), by 
providing that the BART compliance date under any such FIP shall be no 
later than ``five years after . . . the date of promulgation of such a 
plan revision in the case of action by the Administrator under section 
110(c).'' The commenter concluded that because the FIP for NGS is not 
promulgated under section 110(c) of the CAA, the 5-year timeframe for 
BART does not apply to NGS.
    Response: EPA agrees with the comment in support of our action to 
find that the TWG Alternative meets the framework established in our 
Proposed Rule. EPA agrees that we have the legal authority under the 
CAA and RHR to implement a ``better than BART'' alternative.\107\ EPA 
agrees that we have the authority under the CAA and the TAR to extend 
the compliance date that will apply to the ``better than BART'' 
alternative pursuant to CAA Section 301(d)(4) and 40 CFR 49.11(a), as 
discussed in detail below.
---------------------------------------------------------------------------

    \107\ See 40 CFR 51.308(e)(2); CAWCD v. EPA, 990 F.2d 1531 (9th 
Cir. 1993); CEED v. EPA, 398 F.3d 653 (D.C. Cir. 2005); UARG v. EPA, 
471 F.3d 1333 (D.C. Cir. 2006).
---------------------------------------------------------------------------

    We also note that regardless of whether the commenter is correct 
that the CAA does not require compliance with the BART requirements 
within five years for sources subject to a FIP in Indian country, we 
consider five years to be a reasonable timeframe for the installation 
and operation of SCR at NGS. To the extent the commenter is correct 
that the timing provisions of section 169A(g)(4) are outside the scope 
of EPA's action to implement a FIP in Indian country under section 301 
and the TAR, this further supports EPA's determination that extending 
the compliance deadline beyond 2018 for a BART alternative at NGS is 
appropriate.
    EPA also agrees with the comment that approving the TWG Alternative 
for NGS will not compromise the ultimate goal of the RHR based on 
progress toward eliminating human[hyphen]caused visibility impairment 
in Class I areas by 2064.\108\ The TWG Agreement provides that NGS will 
cease conventional coal-fired generation in 2044. Because the TWG 
Agreement included this provision, we are including a provision in the 
Final Rule that requires the operator of NGS to cease conventional 
coal-fired generation by December 22, 2044.\109\ The TWG Agreement 
further states that the Navajo Nation may elect to operate NGS after 
December 22, 2044 consistent with EPA approval. EPA is not including 
this provision in the regulatory requirements at Sec.  
49.5513(j)(3)(iii); however, EPA expects that NGS would be 
substantially modified if the Navajo Nation were to elect to continue 
operation of the facility after NGS ceases conventional coal-fired 
generation in 2044, and that NGS would then need to meet all applicable 
regulatory and permitting requirements in existence at that time. In 
addition, any power generating units that may be built to replace NGS 
would also be subject to environmental review and air permitting 
requirements.
---------------------------------------------------------------------------

    \108\ See CAA section 169A(1)(a).
    \109\ See 79 FR 12944, 12950 (March 7, 2014). ``While it is true 
that the Regional Haze Rule and BART Guidelines do not contemplate 
unit retirements as a potential BART option, neither rule prohibits 
states or EPA from considering a shutdown as part of a BART 
determination if the strategy is proposed by the owner of a BART-
eligible source.''
---------------------------------------------------------------------------

    Comment: General opposition to EPA's ``better than BART'' 
determinations.
    One commenter stated that EPA may approve an alternative to BART 
only under certain limited circumstances, with the fundamental legal 
requirement being a demonstration that the alternative will ``achieve 
greater reasonable progress toward natural visibility conditions'' as 
supported by the clear weight of evidence. The commenter indicated that 
there are two ways EPA can make such a

[[Page 46533]]

demonstration: (1) Showing that the distribution of emissions is 
substantially similar under BART and the alternative measure, and that 
the alternative measure provides greater emissions reductions; or (2) 
performing modeling to demonstrate that visibility does not decline in 
any affected Class I area and there is an overall improvement in 
visibility. The commenter stated that the EPA may not use the first 
prong of the above test because the TWG Alternative distributes 
emissions over time differently than BART. Because the TWG Alternative 
also results in reductions of SO2 and PM, the commenter 
states that the pollutants reduced are also distributed differently. 
The commenter added that a BART alternative must ensure that all 
necessary emission reductions occur in the first planning period, which 
ends in 2018, and that any emission reductions resulting from the 
alternative measure must be surplus to reductions required under other 
provisions of the CAA.
    Response: EPA disagrees with the commenter's statement that the TWG 
Alternative fails to demonstrate that it will ``achieve greater 
reasonable progress toward natural visibility conditions.'' As 
explained below, we disagree with the various comments underlying the 
argument that our framework for analyzing the TWG Alternative is 
flawed.
    EPA appropriately focused on a comparison of the emissions 
reductions from BART and the TWG Alternative, rather than using 
visibility modeling to compare the two approaches. As the commenter 
noted, EPA's regulations provide a specific two-pronged test that may 
be used to demonstrate that a BART alternative achieves greater 
reasonable progress. In this rulemaking, EPA has applied the first 
prong of that test to demonstrate that the TWG Alternative provides for 
greater reasonable progress. The first prong of the test, set out in 40 
CFR 51.308(e), states that if the distribution of emissions is not 
substantially different under BART and the alternative, and ``the 
alternative measure results in greater emission reductions,'' the 
alternative may be deemed to achieve greater reasonable progress. 
Because both BART and the TWG Alternative apply to the same source the 
geographic distribution of emissions is similar.\110\ EPA therefore 
applied this test to determine whether the TWG Alternative provided for 
greater reasonable progress, taking into account total NOX 
emissions over the 2009 to 2044 period from both BART and the TWG 
Alternative.
---------------------------------------------------------------------------

    \110\ In providing states with the flexibility to adopt 
alternative measures in lieu of BART, EPA assumed that under the 
BART alternative provisions, states would most likely adopt a 
trading program rather source specific BART controls. See, e.g., 40 
CFR 308(e) (a regional haze SIP must contain BART limits unless the 
State demonstrates that ``an emissions trading program or other 
alternative will achieve greater reasonable progress. . .''). The 
geographic distribution of emissions under a trading program is 
unlikely to be similar to that under source-specific BART. In 
contrast, the geographic distribution of emissions under a ``better 
than BART'' alternative that applies only to the BART source in 
question would be similar.
---------------------------------------------------------------------------

    The commenter argues, however, that the emissions must be 
temporally similar in order for this test to apply. When EPA added 
Sec.  51.308(e)(3) to the regional haze regulations in 2005, however, 
we made clear that EPA intended this test to apply where the geographic 
distribution of emissions between the BART and an alternative were 
similar.\111\ This approach is reasonable, as visibility modeling is 
not needed to demonstrate that a greater reduction in emissions from a 
source will result in greater visibility benefits than a lesser 
reduction in emissions from the same source. Accordingly, to the extent 
that the regulations are not clear that the test applies where the 
geographic distribution of emissions is similar, our interpretation is 
a reasonable one. In concluding that this test is the appropriate one 
to apply, EPA is not ignoring the commenter's argument that the TWG 
Alternative distributes emissions over time very differently than would 
BART, and that in the near term, visibility would improve more rapidly 
if EPA were to require the installation of BART controls sooner. It is 
not necessary to model the visibility impacts of the TWG Alternative 
and BART, however, to reach that conclusion.\112\
---------------------------------------------------------------------------

    \111\ 70 FR 39136.
    \112\ Although the commenter argues that visibility modeling is 
required to demonstrate that the TWG Alternative makes greater 
reasonable progress, the commenter notes only in passing the second 
test set out in the regulations at 40 CFR 51.308(e)(3) governing 
situations where BART and a BART alternative will result in 
dissimilar distributions of emissions. In such situations, greater 
reasonable progress may be shown if visibility modeling shows that 
(i) visibility does not decline in any Class I area, and (ii) there 
is an overall improvement in visibility by comparing the average 
differences between BART and the alternative over all affected Class 
I areas. Even absent visibility modeling, it seems clear that the 
TWG Alternative, which requires NGS to reduce emissions from current 
levels, will not cause visibility to decline in any Class I area. 
Visibility modeling done by EPA in response to comments regarding 
the limited benefits of SO2 and PM reductions suggests 
that the TWG Alternative also passes the second half of this test. 
As explained in the RTC, EPA modeled the visibility impacts of TWG 
Alternatives A1, A2, and A3 (the operating scenarios that include 
reductions in alternative pollutants). See RTC for further 
discussion. This modeling shows that the cumulative visibility 
benefits of the TWG Alternative outweigh those associated with BART. 
Although we have not modeled the visibility impacts of Alternative 
B, compliance with the 2009-2044 and 2009-2029 NOX Caps 
will require NGS to achieve emission reductions similar to those 
required under Alternative A1 because the 2009-2029 NOX 
Cap is based on emissions that would be expected to occur under 
Alternative A1 (closure of one unit in 2019) and the 2009-2044 
NOX Cap applies to all alternatives under the TWG 
Alternative.
---------------------------------------------------------------------------

    EPA is accordingly determining that the provisions for retiring 
capacity and installing SCR under the TWG Alternative achieve a similar 
geographic distribution of emissions and that the appropriate test to 
apply is whether the alternative provides for greater emissions 
reductions than BART. In applying that test, EPA considers it 
reasonable to consider the cumulative emissions under BART and the BART 
alternative, rather than to simply compare annual emissions in some 
future year under the two scenarios. This approach provides a 
reasonable mechanism to give credit to NGS for its early reduction in 
NOX emissions from the installation of combustion controls.
    The commenter also objects to EPA's decision to approve a BART 
alternative that will not be fully implemented by 2018. EPA agrees that 
the regional haze rule requires BART alternatives to be fully 
implemented by states by 2018, the end of the first planning period for 
states that were required to submit regional haze plans.\113\ As noted 
in the Proposed Rule, given the deadline for the submittal of regional 
haze SIPs, EPA's regulations accordingly built in an additional five 
years beyond the BART compliance date for the implementation of BART 
alternatives.\114\
---------------------------------------------------------------------------

    \113\ 40 CFR 51.308(e)(2)(iii).
    \114\ 78 FR 8288.
---------------------------------------------------------------------------

    We note that in this action, although the TWG Alternative will not 
be fully implemented until 2044, NOX emissions from NGS have 
already declined from historical levels, and significant additional 
declines in emissions are expected in 2019 and again in 2030. 
Nonetheless, we acknowledge that we are looking forward to 2044 for 
full implementation of the TWG alternative, well beyond the 2018 date 
in the RHR. We explained the basis for our proposed decision to set the 
compliance period for the TWG Alternative in the Supplemental Proposal. 
EPA's reasoning on this issue is grounded in CAA section 301 and the 
TAR. The TAR generally exempted Tribes from the CAA submittal deadlines 
that applied to States. EPA interprets the requirement in 40 CFR 
51.308(e)(2)(iii) to constitute a reasonably severable RHR submittal 
deadline that applies to States but not

[[Page 46534]]

to Tribes. If the alternative measure is promulgated by the State, it 
must ``submit[s] an implementation plan containing the following plan 
elements and include[s] documentation for all required analyses: . . . 
(iii) A requirement that all necessary emission reductions take place 
during the period of the first long-term strategy for regional haze.'' 
Therefore, it is a required ``plan element'' for a State-only required 
implementation plan submittal. See 40 CFR 51.308(b)(3) (requirements 
for States to submit long-term strategies). Because it is not mandatory 
for the Tribe to submit a long-term strategy, there is no mandatory 
requirement for the Tribe to ensure that all emissions reductions from 
a better than BART alternative occur within some deadline.
    This result is equitable as well as reasonable. States were 
required to submit SIPs in 2007, allowing 11 years for a ``better than 
BART'' alternative to be achieved in 2018. Because this is a FIP for a 
source in Indian country, and we are only now implementing the 
requirement in 2014, it is equitable to extend the compliance time as 
well. Please see the RTC for a more detailed discussion.
    In summary, EPA is determining that the TWG Alternative is ``better 
than BART'' based on achieving greater NOX emissions 
reductions over a similar geographic distribution, within the date of 
the goal specified in the RHR of achieving natural conditions in 2064. 
Given the requirement to cease conventional coal-fired generation at 
NGS in 2044, and with cumulative emissions over 2009 to 2044 being less 
than the BART Benchmark, the TWG Alternative satisfies the requirements 
of the RHR with respect to NOX BART as applied to Navajo 
Nation based on the TAR.
    Comment: EPA overestimated the BART Benchmark.
    Aside from its assertions that an approach using a BART Benchmark 
based on total emissions is not lawful under the CAA, one commenter (an 
organization representing itself and several other non-governmental 
organizations) stated that EPA's assumptions in calculating a numerical 
value for the BART Benchmark included errors and improper credits. 
Specifically, the commenter asserted that: (1) EPA's credit for the 
early installation of LNB/SOFA runs counter to the Regional Haze Rule, 
EPA's longstanding policies, and EPA's specific statements regarding 
the haze determination for NGS, (2) EPA's proposal to delay BART due to 
the LNB/SOFA credit creates a dangerous precedent that threatens to 
significantly undermine the regional haze program, (3) EPA made a 
number of errors in its calculations that all have the effect of 
artificially inflating the BART Benchmark. The specific errors 
purported by the commenter are outlined in more detail in the RTC. The 
commenter asserts that in total, assuming a final rule by July 1, 2014, 
their recommended revisions to the BART Benchmark would reduce the 
estimated emissions under BART during EPA's chosen timeframe (2009-
2044) by nearly 100,000 tons, a reduction of approximately 26 percent. 
The commenter asserted that if EPA persists in using the emission cap 
framework, EPA must correct the NOX cap to prevent 
alternatives from being compared to an artificially inflated estimate 
of total NOX emissions.
    Response: EPA disagrees with the assertion that we are delaying 
BART. As stated elsewhere in the RTC, as well as in our Proposed Rule 
and Supplemental Proposal, EPA did not propose to ``delay BART.'' EPA 
proposed to provide additional flexibility in the compliance timeframe 
for alternatives to BART.\115\
---------------------------------------------------------------------------

    \115\ See 78 FR 8288, column 1, describing our proposed BART 
determination. See also 78 FR 8289, section titled ``Legal Rationale 
for Extending Compliance Schedule for Alternative Measures for 
NGS.''
---------------------------------------------------------------------------

    The commenter alleges that ``EPA's claimed reliance on ``early'' 
LNB/SOFA as an excuse to avoid or delay what is legally required is 
misplaced and without foundation in the facts or law.'' \116\ The 
commenter cites three sources to support its assertion that the LNB/
SOFA credit runs counter to the RHR and EPA's long-standing policies: 
(1) Page 18 of a report written by Victoria Stamper (Stamper Report), 
which was commissioned by the commenter and submitted as part of its 
comments,\117\ (2) page 35728 of the July 1, 1999 Regional Haze Rule, 
and (3) section IV.D.4.d of the BART Guidelines.\118\ EPA disagrees 
with these assertions.
---------------------------------------------------------------------------

    \116\ See page 22 of the EarthJustice comment letter dated 
January 3, 2014 (document 0367 in the docket for this rule).
    \117\ See document number 0372 in the docket for this rule.
    \118\ Id. page 21.
---------------------------------------------------------------------------

    First, the commenter's use of quotation marks around the word 
``early'' implies that the LNB/SOFA modifications were not, as a 
factual matter, installed early. However, EPA notes that in 2008, when 
the operator of NGS began discussions with EPA regarding the permitting 
requirements associated with the significant increase in carbon 
monoxide (CO) emissions that would result from the installation of LNB/
SOFA, EPA had already begun our process for evaluating BART for NGS, 
but had not yet proposed a BART determination or put forth our ANPR. 
Therefore, no requirement existed that mandated the installation of 
LNB/SOFA at NGS. In addition, the operator of NGS was aware that a BART 
determination, that would likely involve but may not be limited to LNB/
SOFA, was forthcoming. As noted in our Proposed Rule, the operator of 
NGS could have waited until the compliance date for BART to initiate 
any reductions in NOX emissions; however, the operator 
elected in 2008 to seek the necessary permit to install LNB/SOFA on one 
unit per year over 2009-2011.\119\ Thus, because the LNB/SOFA 
modifications were made in 2009-2011, NOX emissions from NGS 
declined from a high of over 35,000 tons in 2002 to less than 20,000 
tons after 2011.\120\ Although some of the decline in total 
NOX emissions can be attributed to a decrease in capacity 
utilization (i.e., decline in heat input of approximately 13 percent 
when comparing 2002 to 2013), the dominant contributor to the decline 
in NOX emissions from NGS was from the installation of LNB/
SOFA over 2009-2011. EPA considers these emission reductions to be real 
reductions that were not required (i.e., voluntary and surplus) and 
were achieved in advance of any actual requirement to reduce emissions 
(i.e., early).
---------------------------------------------------------------------------

    \119\ See Proposed Rule at 78 FR 8289 (February 5, 2013).
    \120\ See RTC and references therein. In 2011, NGS emitted 
19,900 tons of NOX, in 2012, NGS emitted nearly 16,500 
tons of NOX and in 2013, nearly 17,500 tons of 
NOX.
---------------------------------------------------------------------------

    In addition, each of the three citations provided by the commenter 
does not support its assertions that our proposal to credit NGS for the 
early installation of LNB/SOFA runs counter to the Regional Haze Rule 
or EPA's long-standing policies. These three citations merely address 
the appropriate baseline period to use in the five-factor BART 
analysis. Page 18 of the Stamper Report supports our use of 2001-2003 
as the baseline period for our BART determination for NGS and cites to 
64 FR 35728 of the July 1, 1999 Regional Haze Rule that discusses EPA's 
determination that the most appropriate baseline period would be over 
the 2001 to 2004 timeframe. The baseline period is used for evaluating 
the costs and visibility benefits of controls. The Stamper Report also 
cites Section IV.D.4.d of the BART Guidelines at 40 CFR Part 51 
Appendix Y, that states baseline emissions should generally

[[Page 46535]]

represent a realistic depiction of anticipated emissions for the source 
based on actual emissions from a baseline period.
    The commenter also cited the discussion in our Proposed Rule under 
Factor 3, where we described, in 2008, how the early installation of 
LNB/SOFA would not prejudice the implementation of more effective 
controls for BART. As stated previously, we did not use the LNB/SOFA 
credit to justify a less stringent determination of BART for NGS. The 
commenter characterizes the credit as a shift in course from the 
agreements and understandings established in 2008 during the PSD permit 
process for the installation of LNB/SOFA. EPA disagrees. As stated in 
our Proposed Rule, citing the Ambient Air Quality Impact Report from 
the 2008 Proposed PSD Permit, EPA stated that the early installation of 
LNB/SOFA systems would not affect the baselines for cost or visibility 
improvements, and therefore will not influence EPA's determination of 
the NOX reductions required for BART.\121\ EPA's BART 
analysis for NGS was consistent with this statement. As previously 
noted, EPA used the 2001-2003 period as the baseline for determining 
cost-effectiveness and visibility benefits of controls, and determined, 
based on our analysis of all five factors, that SCR+LNB/SOFA is an 
appropriate BART Benchmark for NGS.
---------------------------------------------------------------------------

    \121\ See 78 FR 8284 (February 5, 2013).
---------------------------------------------------------------------------

    The commenter relies on EPA's statements about the appropriate 
baseline period to support an assertion that in a BART analysis, EPA 
should not give consideration or credit for controls installed after 
the baseline period. As stated in section 5.0 of the RTC (section 5.0), 
although we appropriately acknowledged the installation of LNB/SOFA 
after the baseline period at NGS under Factor 3 (existing controls at 
the facility), our analysis of cost-effectiveness and anticipated 
visibility benefits appropriately compared SCR+LNB/SOFA against the 
2001-2003 baseline period.\122\
---------------------------------------------------------------------------

    \122\ We note that in State of North Dakota v. EPA, the U.S. 
Court of Appeals for the Eighth Circuit vacated and remanded EPA's 
promulgation of a FIP for Coal Creek Station because EPA did not 
consider the existing pollution control technologies in use at Coal 
Creek Station that were voluntarily installed after the baseline 
period. This document is included in the docket for this rule.
---------------------------------------------------------------------------

    EPA's proposed credit for early installation of LNB/SOFA was not 
associated with our five-factor analysis or BART determination for NGS. 
Rather, EPA discussed the LNB/SOFA credit in our framework for 
evaluating alternatives to BART. Specifically, in discussing our 
framework for BART Alternatives, EPA calculated the cumulative 
NOX reductions achieved early because the operator of NGS 
elected to install LNB/SOFA on one unit per year over 2009-2011, 
instead of waiting for the compliance period for BART. In our Proposed 
Rule and Supplemental Proposal we used this value, the LNB/SOFA credit, 
when comparing BART Alternatives to BART. As discussed elsewhere in the 
RTC, EPA's proposal to allow BART Alternatives to take credit for the 
early installation of LNB/SOFA at NGS is a reasonable use of our 
discretion under the TAR.\123\
---------------------------------------------------------------------------

    \123\ See 78 FR 62511 (October 22, 2013).
---------------------------------------------------------------------------

    EPA disagrees with the assertion that this credit creates a 
dangerous precedent that threatens to significantly undermine the 
regional haze program. EPA notes that part of our rationale for the 
better than BART framework for NGS (including the credit for the early 
installation of LNB/SOFA and the adjusted compliance timeframe for BART 
Alternatives) was the potential impacts to numerous tribes that rely on 
NGS and/or CAP, as well as EPA's regulations specifying that SIP 
submittal deadlines that apply to states do not apply to Tribes (or to 
EPA when implementing FIPs in Indian country). Further, EPA notes that 
the relationship between NGS and CAP is unique, the only other BART-
eligible source in Indian country is the Four Corners Power Plant, and 
EPA has already completed the BART determination and FIP for this 
facility.\124\
---------------------------------------------------------------------------

    \124\ See 77 FR 51620 (August 24, 2012).
---------------------------------------------------------------------------

    EPA also disagrees with the assertion that we overestimated the 
BART Benchmark and NOX Cap. The commenter argues that SCR 
can meet a lower emission limit than proposed by EPA and that EPA 
should have set a compliance date within 3.5 years. As discussed in 
Section 8.1 of the RTC, EPA disagrees that the BART Benchmark should be 
based on an emission limit of 0.040 lb/MMBtu and that compliance should 
be required in 3.5 years. EPA is finalizing a BART Benchmark based on 
our determination requiring NGS to meet a limit of 0.055 lb/MMBtu 
within five years of the effective date of the Final Rule. Therefore, 
EPA is not revising the BART Benchmark or NOX Cap to assume 
a limit of 0.040 lb/MMBtu or a shorter compliance time for BART.
    In addition, the commenter recommends that EPA use average heat 
input over the baseline period (i.e., over 2001-2003) rather than the 
average over the pre-LNB/SOFA time period (i.e., average over 2001-
2008) to calculate future emissions. The commenter notes that our 
calculations for cost-effectiveness use baseline heat input over 2001-
2003 to calculate pre- and post-control emissions (approximately 5,264 
tons per year). The commenter asserts that this inconsistency is 
arbitrary. The commenter correctly notes that EPA used the average heat 
input over 2001-2008 (the pre-LNB/SOFA time period) to estimate 
emissions over 2009-2019 that would have occurred if the operator of 
NGS had not installed LNB/SOFA early, and emissions over 2019 to 2044 
under BART (5,345 tons per year). The average heat input over the 
baseline period of 2001-2003 was 191,505,266 MMBtu, while the average 
heat input over 2001-2008 was 194,373,910 MMBtu. This is a difference 
of about 1.5 percent. EPA agrees that use of the same 2001-2003 
baseline heat input value for estimating pre- and post-control emission 
rates is appropriate and consistent with the RHR and BART Guidelines, 
particularly in light of the goal of understanding the effect of a 
given control technology on emissions (i.e., assume identical values 
for baseline and future heat input to isolate the impact of control 
technologies). However, this approach does not mean that an average 
from the three-year baseline period (2001-2003) is most appropriate for 
estimating future emissions in determining the BART Benchmark. EPA 
notes that the use of average heat input for 2001-2008 includes the 
baseline period recommended by the commenters and provides a larger 
data set, and therefore a more robust average value for estimating 
future emissions. EPA considers the use of an average value based on 
three years to be less robust than an average value based on eight 
years of data for representing potential future operation; therefore, 
EPA is retaining our use of the average heat input over 2001-2008 for 
estimating emissions over 2009-2044. EPA further notes that emission 
caps in permit requirements are typically established based on the 
facility's potential to emit (PTE) and would thus be calculated using 
maximum heat input values. The highest observed annual heat input value 
was 199,398,687 MMBtu and, if used in the NOX cap, would 
result in a significantly higher BART Benchmark.
    The commenter also argues that in calculating the NOX 
cap, EPA should use a value that reflects an annual average for post-
control emission rates rather than a rate based on a 30-day average 
limit of 0.055 lb/MMBtu. The commenter reviewed daily data from

[[Page 46536]]

2000 to 2013 and calculated the ratio of the maximum 30-day average 
rate to the annual rate for each year and determined an average ratio 
of 1.135. Based on this ratio, the commenter recommended that the BART 
emission limit of 0.055 lb/MMBtu (on a rolling average of 30 boiler 
operating days) be reduced by a factor of 1.135 as an estimate of what 
the annual average post-control emission rate would be at NGS (i.e., 
0.048 lb/MMBtu). EPA agrees that generally, emission rates averaged 
over an annual basis are lower than emission rates averaged over a 30-
day basis. However, EPA did not propose setting a BART limit for NGS on 
an annual average basis and EPA did not receive any comments suggesting 
that we do so. Without an enforceable annual limit, EPA considers it 
inappropriate to assume a lower emission rate in our calculation of the 
NOX Cap. We note that the BART Guidelines require that BART 
limits for EGUs be set on a rolling average of 30 boiler operating 
days. Therefore, although the BART Guidelines would not preclude 
establishing multiple emission limits over different averaging periods, 
the BART Guidelines do not require it.
    Separately, the commenter also asserts that EPA overestimated the 
2009-2044 NOX Cap. The commenter represents EPA's 
NOX Cap as the scenario it calls ``CAP-1'' with a value of 
494,899 tons. This value is consistent with the 2009-2044 
NOX Cap EPA proposed in our Supplemental Proposal.\125\ The 
commenter asserts that this value is overestimated because (1) actual 
heat input data should be used to calculate the NOX Cap; and 
(2) the LNB/SOFA could be installed in two years.\126\ EPA disagrees 
with these assertions.
---------------------------------------------------------------------------

    \125\ See Table 3 of our Supplemental Proposal at 78 FR 62516 
(October 22, 2013).
    \126\ See Table 3 of the report written by Nathan Miller and 
Raijit Sahu (Miller/Sahu Report) commissioned by the commenter and 
submitted with its comments. See document number 0370 in the docket 
for this rule.
---------------------------------------------------------------------------

    The commenter argues that for the period of 2009-2013, actual heat 
input data should be used to calculate the NOX Cap instead 
of the average heat input value over 2001-2008. EPA acknowledges that 
actual heat input data is available for the 2009-2013 period; however, 
EPA considers using the average value to be appropriate, recognizing 
that years of lower than average capacity utilization will be balanced 
with years of higher than average capacity utilization at NGS.
    The commenter also asserts that LNB/SOFA could have been required 
in two years, on a separate compliance timeframe than installation of 
SCR and that this should have been incorporated in our calculation of 
the NOX Cap. EPA is not aware of any BART determination that 
required combustion controls on a different schedule than post-
combustion controls. Although the commenter correctly notes that LNB/
SOFA was installed in three years (on one unit per year over 2009-
2011), EPA notes that the operator began the permitting process in 2008 
and installed the LNB/SOFA during periods of major outage for each 
unit, which occurs at NGS every six years for each unit.\127\ EPA 
expects that it would not have been practicable to require installation 
of LNB/SOFA within two years following the final rule because, in order 
to accommodate one year for permitting, it would have required major 
outages on all three units in the same year. Therefore, EPA does not 
consider it practicable to assume the LNB/SOFA would or could have been 
installed on a separate track from the SCR.
---------------------------------------------------------------------------

    \127\ See tab titled ``Outage Cycle'' in the document titled 
``EPA Analysis of BART Alternatives'' in document number 0004 in the 
docket for this rule.
---------------------------------------------------------------------------

    Although the commenter makes assertions related to purported 
overestimations of the BART Benchmark and the 2009-2044 NOX 
Cap separately, the commenter combines all of the assertions together 
to argue that the 2009-2044 NOX Cap should be 373,029 tons 
(121,870 tons, or 25 percent, lower than EPA's proposed 2009-2044 
NOX Cap of 494,899 tons). As outlined above, EPA disagrees 
than any of the purported corrections suggested by the commenter are 
necessary or appropriate for projecting annual emissions to calculate 
the 2009-2044 NOX Cap.
    Comment: EPA double-counted the benefits of LNB/SOFA.
    One commenter asserted that EPA double-counted the benefits of the 
early installation of LNB/SOFA, stating that EPA calculated cumulative 
emissions for the BART alternatives including the benefits of early 
reductions, then subsequently applied a LNB/SOFA credit again to BART 
alternatives.
    Response: EPA disagrees with the assertion that we double-counted 
emission reductions associated with the early installation of LNB/SOFA.
    In our February 5, 2013 proposed rule, EPA calculated the value of 
the LNB/SOFA credit based on the difference between total emissions 
under the BART scenario where LNB/SOFA is installed concurrently with 
SCR and the actual scenario when LNB/SOFA was installed early. The 
value of this credit was then applied to total emissions over 2009-2044 
under Alternative 1.\128\ Although our calculation of emissions under 
Alternative 1 did account for actual emissions with early installation 
of LNB/SOFA, and thus applying the LNB/SOFA credit to the BART 
Alternative may appear to be double counting, it is not double-counting 
because the BART Alternatives were compared against a BART Benchmark 
that also accounted for actual emissions with early installation of 
LNB/SOFA. Thus, both the BART Benchmark and Alternative 1 were 
calculated the same way (actual emissions accounting for early LNB/SOFA 
installation), and the LNB/SOFA credit was only applied to Alternative 
1. An example of double-counting would have been if EPA had applied the 
LNB/SOFA credit to cumulative emissions over 2009-2044 under 
Alternative 1 and then compared that value to total emissions over the 
same period under BART assuming LNB/SOFA and SCR were installed 
concurrently.
---------------------------------------------------------------------------

    \128\ See document titled ``EPA Analysis of BART 
Alternative.xlsx'' in document 0004 in the docket for the rule.
---------------------------------------------------------------------------

    In our October 22, 2013 Supplemental Proposal, EPA approached the 
calculation from a different but equivalent perspective. The new 
calculation approach was used because it was more intuitive to apply 
and understand in the context of an enforceable cap on NOX 
emissions. In the Supplemental Proposal, the BART Benchmark was 
established as the total emissions over 2009-2044 that would have 
occurred if LNB/SOFA and SCR were installed concurrently, five years 
following the effective date of the final rule. Total emissions under 
BART Alternatives were then calculated using actual emissions beginning 
in 2009 (i.e., accounting for the early installation of LNB/SOFA) and 
projections for future emissions. Thus, in the methodology used in the 
Supplemental Proposal, the LNB/SOFA credit was applied to the BART 
Benchmark and NOX Cap, rather than to the TWG Alternative. 
This method is equivalent to the one used in the Proposed Rule but does 
not give the appearance of double-counting. In our Supplemental 
Proposal and supporting documents, EPA included calculations to show 
that these two methods are equivalent.\129\ The two methods are 
equivalent because what matters in the ``better than BART'' context is 
the difference between total emissions under BART and total emissions 
under

[[Page 46537]]

the BART Alternative. Whether the LNB/SOFA credit is applied to BART or 
BART Alternatives will affect the absolute value of a total (e.g., 
using the numbers in Table 2 of the Supplemental Proposal, the LNB/SOFA 
credit represents a difference of 377,008 tons or 480,489 tons), but it 
does not affect the difference between BART and BART Alternatives. The 
method used in the Supplemental Proposal is more intuitive because BART 
and the BART Benchmark reflect total emissions over 2009-2044 that 
would have occurred if LNB/SOFA were installed concurrently with SCR, 
and the BART Alternatives reflect actual emissions without further 
credit or modification. Because no credits or modifications are made to 
actual emissions under the BART Alternatives, this method is the more 
logical accounting methodology for determining compliance with the 
2009-2044 NOX Cap.
---------------------------------------------------------------------------

    \129\ See Table 2 of the Supplemental Proposal (78 FR 62515, 
October 22, 2013) and document number 0191 titled ``Supplemental 
Better than BART Alterntives.xlsx'' in the docket for this rule.
---------------------------------------------------------------------------

    Comment: BART Alternatives would interfere with reasonable progress 
goals in other states.
    One commenter stated delaying the compliance date for BART will 
allow NGS to continue emitting pollutants in excess of the levels 
modeled by the WRAP and will interfere with the ability of Arizona, 
Utah, and Colorado to meet their reasonable progress goals for 2018.
    Response: The issue raised by the commenter is outside the scope of 
our rulemaking addressing the NOX BART requirements for NGS. 
Although 40 CFR 51.308(d)(3) requires states to submit long-term 
strategies that are sufficient to ensure that the state has included 
all measures needed to achieve its share of emission reductions agreed 
to through the regional planning process, the Navajo Nation has not yet 
submitted a long-term regional haze strategy. In addition, EPA has not 
yet found it necessary or appropriate to address these requirements 
through a FIP. If EPA determines it is necessary or appropriate to do 
so, we will take appropriate action.
    Meanwhile, we note that for NGS, the WRAP assumed that 
NOX emissions in 2018 would equal 10,611 tons per year. 
NOX emissions under the TWG Alternative, in turn, will range 
from approximately 13,000 to 15,000 tons per year following the closure 
of one unit (or equivalent curtailment) at the end of 2019. We also 
note that the closure of one unit (or equivalent curtailment) by the 
end of 2019 would reduce not only NOX, but also emissions of 
SO2. Given the overall changes in emissions from the various 
regional haze actions since the WRAP made its projections, we will be 
better able to assess the need, if any, for further action once 
Arizona, Utah, and Colorado have prepared regional haze SIPs for the 
second planning period.

J. Comments on the TWG Alternative and EPA's Supplemental Proposal

    Comment: Opposition to TWG Alternative because it is premised on 
SCR as BART.
    One commenter argued that the 2009-2044 NOX Cap used for 
the TWG Alternative is unduly and arbitrarily stringent because it is 
based on a limit of 0.055 lb/MMBtu, which the commenter believes is too 
stringent because (1) EPA should not have determined that SCR is BART 
and (2) even if SCR were the appropriate basis for BART, 0.055 lb/MMBtu 
is not achievable. The commenter stated that because Arizona 
agricultural users will phase out their use of CAP Ag Pool water by 
December 2030 pursuant to the 2004 Arizona Water Settlement Act (AWSA), 
capital costs that are collected in advance of SCR operation will be 
imposed on NIA users in exchange for no benefit. The commenter asserted 
that if EPA finalizes either of the ``better than BART'' alternatives 
without modification, it would be arbitrarily and capriciously 
apportioning compliance costs to NIA water users for which they are not 
responsible. Given EPA's acknowledgment of the compliance flexibility 
that exists with respect to the TAR, the commenter believes that the 
failure to consider potential ``better than BART'' alternatives that 
would afford compliance flexibility to all NGS stakeholders on an 
evenhanded basis constitutes an abuse of discretion on the part of EPA.
    Response: EPA disagrees with the assertion that the TWG Alternative 
is unduly and arbitrarily stringent because it is based on a BART limit 
of 0.055 lb/MMBtu. We consider the limit of 0.055 lb/MMBtu to 
appropriate for establishing the BART Benchmark for NGS. EPA addressed 
specific comments related to the BART limit in section 8.1 of the RTC. 
We also note that the TWG Alternative was developed as an agreement 
between diverse stakeholders, including SRP, the operator of NGS on 
behalf of itself and other co-owners, and the CAWCD. Although both 
entities submitted comments in opposition to the proposed BART limit of 
0.055 lb/MMBtu, both parties signed the TWG Agreement that establishes 
the NOX Cap based on the proposed BART limit of 0.055 lb/
MMBtu.
    The commenters indicate that their access to CAP Ag Pool water is 
expected to end in 2030, and assert that the timeframes for compliance 
with the limit of 0.07 lb/MMBtu in 2030 would necessitate water rate 
increases prior to 2030. The commenter asserts that it is arbitrary and 
capricious for NIA water users to pay a few years of higher CAP water 
rates for controls that will not be operational until after their 
access to the CAP Ag Pool expires. EPA notes that the direct impact of 
compliance with the limit of 0.07 lb/MMBtu in 2030 under the TWG 
Agreement, presumably with installation and operation of SCR, would be 
on the cost of electricity generation. Increasing water rates are 
indirect impacts that result from the relationship between NGS and CAP. 
EPA does not set or determine water rates charged by CAWCD to the CAP 
Ag Pool or any other classes of CAP customers. EPA's proposed and final 
approval of requirements consistent with the TWG Agreement as a 
``better than BART'' alternative is based on our review of the 
anticipated emission reductions associated with the TWG Alternative 
compared to BART. Although EPA, DOI, and DOE have committed to work 
together on many issues related to NGS, including funding for the 
federal portion of capital improvements at NGS, EPA does not determine 
how controls would be financed and how and when electricity or water 
rates would be adjusted to recover costs.
    Comment: TWG Alternative does not fully meet EPA's obligations to 
the Gila River Indian Community.
    The Gila River Indian Community said that even though it fully 
supports the TWG Alternative, it is concerned that EPA has not met its 
obligations to the Community because of the significant costs on NGS 
and associated impacts on the Community. Rather, the commenter views 
the TWG Alternative as the first step in a process that will limit the 
impacts on the Community because only under the TWG Alternative will 
key U.S. commitments contained in the TWG Agreement be realized. 
Specifically, under the TWG Agreement, and as outlined by the 
commenter, DOI will work with the Community and other tribes in the 
area around NGS, to evaluate the actual impacts the regulatory 
requirements will have on NGS over time. The commenter specifically 
referred to the U.S. commitment to allocate $10 million annually for 10 
years starting in 2020, from the Reclamation Water Settlements Fund to 
reduce impacts to the Development Fund.
    Response: EPA acknowledges the comment and is aware that costs 
associated with implementing the TWG Alternative will have implications 
for numerous Tribes, including the Gila

[[Page 46538]]

River Indian Community. EPA is committed to continuing to work with the 
Department of the Interior and the Department of Energy in the 
Interagency Working Group on NGS, as laid out in the Joint Statement 
signed in January 2013 by the heads of the three agencies, to work with 
tribes to address long-term issues related to NGS. The provisions in 
the TWG Agreement that are not related to EPA's authority to evaluate 
BART or a ``better than BART'' alternative, however, are beyond the 
scope of this rulemaking.
    Comment: TWG Alternative is vague and unenforceable.
    One commenter stated that a BART determination must include clear 
requirements for emissions reductions and a clear timeline for those 
reductions, to ensure continuing visibility improvements in Class I 
areas. The commenter indicated that without specific emission limits 
and/or commitments to retire specific amounts of capacity from specific 
units, as of a date certain, it is impossible to calculate the 
visibility improvements that will result from the TWG Alternative, 
particularly TWG Alternatives A3 and B, and it will be impossible for 
individuals or EPA to assess whether NGS is on track to meet the 
emission reductions necessary to ensure reasonable progress toward 
natural visibility in affected Class I areas.
    Response: EPA disagrees with the assertion that the TWG Alternative 
is vague and unenforceable. EPA acknowledges that the TWG Alternative 
provides flexibility in a manner that appears complex. This complexity 
is a result of the role future ownership outcomes will have in 
determining the most reasonable compliance options in the future. Once 
the ownership issues are resolved, the scope of options under the TWG 
Alternative narrows. Although some flexibility still remains in the TWG 
Alternative, particularly under TWG Alternative B, the options for 
future operation of NGS are bounded by the limitations provided by the 
2009-2044 and 2009-2029 NOX Caps.
    Contrary to the assertions by commenters, EPA included proposed 
regulatory language in our Supplemental Proposal that provided specific 
and enforceable timelines for achieving emission reductions under the 
TWG Alternative. The proposed language under 40 CFR 49.5513(j)(3)(i), 
``Operating Scenarios to Comply with 2009-2044 NOX Cap,'' 
defines the timeframes and requirements under TWG Alternatives A1, A2, 
A3, and B, all of which must be implemented in a manner that ensures 
total NOX emissions over 2009-2044 remain below the 2009-
2044 NOX Cap. Specifically, Sec.  49.5513(j)(3)(i)(A) 
defines Alternative A1, and specifies the following requirements: (1) 
By December 31, 2019, the owner/operator shall permanently cease 
operation of one coal-fired unit and (2) by December 31, 2030, the 
owner/operator shall comply with a NOX emission limit of 
0.07 lb/MMBtu on each of the two remaining coal-fired units. 
Alternative A1 is the simplest of the possible operating scenarios 
under the TWG Alternative and Sec.  49.5513(j)(3)(ii)(A) specifies that 
Alternative A1 applies under three potential future ownership 
possibilities.
    TWG Alternative A2 is defined in Sec.  49.5513(j)(3)(i)(B) and 
requires (1) by December 31, 2019, the owner/operator shall permanently 
cease operation of one coal-fired unit, and (2) by December 31, 2019, 
the owner/operator may elect to increase net generating capacity of the 
remaining two coal-fired units by a combined total of no more than 189 
MW. The actual increase in net generating capacity shall be limited to 
the sum of 19 MW and the ownership interest, in net MW capacity of up 
to 170 MW, purchased by the Navajo Nation by December 31, 2019. The 
owner/operator shall ensure that any increase in the net generating 
capacity is in compliance with all pre-construction permitting 
requirements, as applicable, and (3) by December 31, 2030, the owner/
operator shall comply with a NOX emission limit of 0.07 lb/
MMBtu on each of the two remaining coal-fired units. The future 
ownership possibilities that would trigger Alternative A2 are defined 
in Sec.  49.5513(j)(3)(ii)(B).
    TWG Alternative A3 is defined in Sec.  49.5513(j)(3)(i)(C) and 
requires (1) by December 31, 2019, the owner/operator shall reduce net 
generating capacity of NGS by no less than 561 MW. The actual reduction 
in net generating capacity of NGS shall be determined by the difference 
between 731 MW and the ownership interest, in net MW capacity of up to 
170 MW, purchased by the Navajo Nation by December 31, 2019, and (2) by 
December 31, 2030, the owner/operator shall comply with a 
NOX emission limit of 0.07 lb/MMBtu on two units. The future 
ownership possibilities that would trigger Alternative A2 are defined 
in Sec.  49.5513(j)(3)(ii)(C).
    TWG Alternative B is defined in Sec.  49.5513(j)(3)(i)(D) and 
requires that in addition to the 2009-2044 NOX Cap, the 
owner/operator shall ensure compliance with the 2009-2029 
NOX Cap. The 2009-2044 NOX Cap is defined in 
Sec.  49.5513(j)(2)(ii) as no more than 494,899 tons of NOX, 
and the 2009-2029 NOX Cap is defined in Sec.  
49.5513(j)(2)(i) as no more than 416,865 tons of NOX. The 
2009-2029 NOX Cap is based on closure of one unit by 
December 31, 2019 and the 2009-2044 NOX Cap is based on 
compliance with the BART emission limit of 0.055 lb/MMBtu by July 1, 
2019. The future ownership possibilities that would trigger Alternative 
B are defined in Sec.  49.5513(j)(3)(ii)(D). As described in Sec.  
49.5513(j)(4)(iv), if TWG Alternative B is triggered, the owner/
operator must submit annual Emission Reduction Plans that contain the 
anticipated year-by-year emissions to ensure compliance with the 2009-
2029 and 2009-2044 NOX Caps.
    The commenter asserts that under the scenario of reduced capacity 
(three units remain open, i.e., TWG Alternative A3), EPA ignored other 
possible outcomes and simplistically assumed that two units would 
continue to operate at full capacity with SCR and the unit whose 
operation is curtailed would operate only with LNB/SOFA. The commenter 
asserts that there is no guarantee that the operator will choose to 
comply with TWG Alternative A3 in this manner. Although this specific 
arrangement under TWG Alternative A3 is not required, EPA disagrees 
that nothing compels the operator to comply with this operating 
scenario in a manner that reduces emissions comparably with the 
assumption that two units would operate at full capacity with SCR and 
the unit that is curtailed would operate with LNB/SOFA. EPA notes that 
under TWG Alternative A3, as well as all other TWG Alternatives, the 
owner/operator must operate the units at NGS so that total emissions 
remain below the 2009-2044 NOX Cap (as well as the 2009-2029 
NOX Cap under Alternative B). For example, under TWG 
Alternative A3, if the operator chose to curtail all three units by a 
total of 561 MW equally and comply with a limit of 0.07 lb/MMBtu on two 
units and 0.24 lb/MMBtu on one unit, total emissions over 2009-2044 are 
not likely to comply with the 2009-2044 NOX Cap.\130\ Thus, 
the operator would be prohibited from operating in this manner and 
would need to, for example, significantly curtail operations to reduce 
emissions further, or risk violating the FIP.
---------------------------------------------------------------------------

    \130\ See RTC and references therein.
---------------------------------------------------------------------------

    As noted in our Supplemental Proposal, EPA estimated total 
NOX emissions over 2009-2044 for TWG Alternatives A1, A2, 
and A3 to provide assurance that the owner/operator could reasonably 
meet the 2009-2044 NOX Cap under the specific terms of those 
alternatives. EPA does not need to

[[Page 46539]]

determine that all operating possibilities that are consistent with the 
requirements of TWG Alternative A1, A2, and A3 would also meet the 
2009-2044 NOX Cap. The regulatory requirements EPA is 
finalizing for the TWG Alternative provide specific dates on which the 
owner/operator must close a unit, curtail operations, and meet emission 
limits. While there is some flexibility in how emissions might be 
curtailed under TWG Alternative A3, the 2009-2044 NOX Cap 
ensures that the operator does not implement a strategy that results in 
substantially more emissions than would be achieved by installing SCR 
on the two units that are operated at full capacity and curtailing 
operations on the unit that was not retrofit with SCR.
    The commenter asserts that there are an infinite number of ways the 
operator could comply with the 2009-2029 and 2009-2044 NOX 
Caps under TWG Alternative B. The commenter further states that the two 
possibilities EPA considered in our Supplemental Proposal are not 
likely to be the outcomes under TWG Alternative B. EPA agrees that TWG 
Alternative B provides more flexibility than TWG Alternative A. 
However, EPA disagrees that TWG Alternative B is so open-ended that it 
would not be enforceable or result in emission reductions at NGS. We 
note that the 2009-2029 NOX Cap was calculated based on the 
closure of one unit with no additional increase in capacity (i.e., 
equivalent to emissions under TWG Alternative A1). Thus, the operator 
cannot maintain the status quo (operation of all three units at full 
capacity at a limit of 0.24 lb/MMBtu) and meet the 2009-2029 
NOX Cap. We recognize that several commenters are concerned 
about the flexibility under TWG Alternative B. However, as discussed 
further in the RTC, we note that the range of possible operating 
choices for TWG Alternative B is substantially constrained by the 
requirement to comply with the 2009-2029 and 2009-2044 NOX 
Caps.
    Although we disagree with commenters that the TWG Alternative is 
vague and unenforceable, in response to the concerns expressed by these 
commenters, to provide additional assurance that cumulative emissions 
of NOX from NGS under the TWG Alternative will not exceed 
the BART Benchmark, EPA is adding the following provisions to the Final 
Rule. Under all Alternatives, if cumulative emissions of NOX 
from NGS exceed the 2009-2044 NOX Cap prior to 2044, the 
operator of NGS must permanently cease operation of NGS. In addition, 
under Alternative B, if cumulative emissions of NOX exceed 
the 2009-2029 NOX Cap prior to 2029, the operator of NGS 
must temporarily cease operation of all units at NGS.\131\
---------------------------------------------------------------------------

    \131\ The combination of the 2009-2044 and 2009-2029 
NOX Caps under TWG Alternative B means that if NGS 
exceeds the 2009-2029 NOX Cap prior to 2029 it must cease 
operation, but the operator may re-start operation after 2030 as 
long as cumulative emissions have not yet exceeded the 2009-2044 
NOX Cap.
---------------------------------------------------------------------------

    One commenter asserted that EPA was incorrect to claim that the TWG 
Alternative would absolve NGS of obligations related to a Reasonably 
Attributable Visibility Impairment (RAVI) finding that may be made for 
NGS.\132\ EPA disagrees that we claimed that the TWG Alternative would 
absolve NGS of obligations related to RAVI. The commenter cited to 
footnote 21 in our Supplemental Proposal.\133\ In that footnote, we 
acknowledged that the TWG had intended their alternative to satisfy 
both the ``better than BART'' requirements of the RHR as well as any 
requirements of the RAVI program. Our footnote merely noted that there 
was no outstanding petition to certify impairment from NGS at any Class 
I area and outlined the process and requirements for triggering a BART 
determination under RAVI. Although we stated that a BART determination 
under RAVI would likely be the same as a BART determination under 
regional haze (i.e., an analysis of the five factors listed in the 
CAA), EPA did not make any conclusions or absolve NGS of any 
obligations related to RAVI because there is currently no action before 
EPA to make an attribution finding related to NGS.
---------------------------------------------------------------------------

    \132\ See EarthJustice letter, page 10, footnote 25.
    \133\ See Supplemental Proposal, 78 FR 62513, footnote 21 
(October 22, 2013).
---------------------------------------------------------------------------

    EPA is finalizing the requirements of the TWG Alternative, 
consistent with Appendix B of the TWG Agreement, which require, among 
other things, emission reductions in 2019 and 2030. EPA is also adding 
as an enforceable requirement, the commitment from the TWG Agreement to 
cease conventional coal-fired electricity generation at NGS by 2044. 
EPA considers these timeframes to be consistent with the stated goal of 
section 169A of the CAA. EPA has addressed comments regarding 
consistency with EPA's regulations, including the RHR and the TAR, in 
section 8.5 of the RTC.
    Comment: Additional concerns with TWG Alternative.
    The Hopi Tribe indicated that it has serious concerns with the 
proposed TWG Alternative for several reasons, including because the TWG 
Alternative does not specify the technology, i.e., either SCR or an 
equivalent that will be used to achieve the same level of 
NOX reductions as the BART proposal. The commenter states 
the TWG Alternative is ambiguous because both scenarios are vague and 
do not include the same level of assurance that the NOX 
reductions will be the same as under the BART proposal. Also, because 
the time NGS would be permitted to operate without SCR (or equivalent 
alternative) would be adjusted under the TWG Alternative, the commenter 
believes the TWG Alternative jeopardizes the goal of the CAA and the 
purpose of this regulation.
    Response: Our proposed BART determination did not specify what 
technology must be used because BART is defined as an emission limit 
that represents the level of control representing BART, not a 
particular technology. Thus, our Proposed Rule and the Supplemental 
Proposal both imposed emission limits for NOX. The limits 
for BART (0.055 lb/MMBtu) and the TWG Alternative (0.07 lb/MMBtu) are 
based on what is achievable using a specific technology. Both limits 
are achievable with SCR, but the operator may consider using newer 
technologies, if available, as long as each unit complies with its 
applicable emission limit by its compliance date. The commenter also 
noted that the extended period for compliance under the TWG Alternative 
may jeopardize the goal of the CAA and the purpose of the RHR. Under 
section 169A of the CAA and the RHR, the goal of restoring visibility 
in Class I areas to natural conditions is set for 2064.\134\
---------------------------------------------------------------------------

    \134\ 40 CFR 51.308(d).
---------------------------------------------------------------------------

    Comment: ``Arbitrary'' 2044 end date.
    One commenter stated that the 2009-2044 period analyzed for the TWG 
Alternative is arbitrary because it is quite likely that one or more 
NGS units will operate beyond that time frame. The commenter asserted 
that if NGS units continue to operate for even 3 additional years, 
until 2047, the TWG Alternative permits outcomes that will result in 
greater total NOX emissions than the 2009-2044 
NOX Cap.
    Response: EPA disagrees with the comment that the 2044 end date for 
the NOX Cap is arbitrary. EPA used 2044 as the end date in 
our calculations of the BART Benchmark. We selected 2009-2044 as most 
appropriate because it includes the early installation dates for LNB/
SOFA and extends until the anticipated 2044 termination date of the 
renewed site lease that was approved by the Navajo Nation.\135\ Under 
the TWG

[[Page 46540]]

Agreement signed by six entities including the Navajo Nation and SRP, 
the NGS Co-Tenants shall cease their operation of conventional coal-
fired generating at NGS no later than December 22, 2044. At its 
election, consistent with the Lease Amendment, the Navajo Nation may 
continue plant operations at NGS after December 22, 2044 consistent 
with EPA approval.\136\ Thus, the Navajo Nation may seek to operate NGS 
after 2044, however, EPA expects that operation of NGS after the owners 
cease conventional coal-fired generation would involve substantial 
modification to NGS and NGS would be required to meet all applicable 
regulatory and permitting requirements in existence at that time. To 
make this end date federally-enforceable, EPA is adding it as a 
requirement to the regulatory language in today's final action. EPA is 
adding the regulatory language in the Final Rule under 40 CFR 
49.5513(j)(3)(iii) stating that by December 22, 2044, the owner/
operator shall permanently cease operation of all coal-fired units at 
NGS. At its election, the Navajo Nation may continue plant operation at 
NGS after December 22, 2044, consistent with EPA approval under the New 
Source Review program.
---------------------------------------------------------------------------

    \135\ See Footnote 60 in the Proposed Rule, 78 FR 8290 (February 
5, 2013).
    \136\ See Section VII.F of the TWG Agreement (page 14).
---------------------------------------------------------------------------

    Comment: Emissions under the TWG Alternative.
    One commenter stated that neither EPA nor TWG have provided a 
comprehensive technical analysis of the emissions that are possible 
under the TWG Alternative. The commenter asserted that it is EPA's 
responsibility to provide an administrative record that contains 
comprehensive modeling and analysis for any BART proposal, but EPA left 
this critical component of the alternatives analysis undone.
    The commenter provided its own calculations of emissions under TWG 
Alternative A and B and compared those estimates with its own 
calculation of a NOX Cap and BART Benchmark, and concluded 
that cumulative emissions from possible scenarios under the TWG 
Alternative are not lower than its NOX Cap or BART 
Benchmark.
    Response: EPA disagrees with the comment that we have failed to 
provide a comprehensive technical analysis of the TWG Alternative. We 
also disagree with the assertion that our administrative record for 
this rulemaking is incomplete. As stated elsewhere in the RTC, EPA's 
analysis of the TWG Alternative is consistent with the required 
analyses for alternatives to BART outlined in the RHR.
    The comment relies on a report prepared by Nathan Miller and 
Ranijit Sahu (Miller/Sahu) for the commenter contending that EPA's 
evaluation of the TWG Alternative is incorrect. But the report changes 
the central inputs underlying our calculations for BART and the TWG 
Alternative. The specific technical reasons that we disagree with the 
inputs that Miller/Sahu changed (e.g., NOX emissions limit 
achievable with SCR, heat input values from baseline period, annual vs. 
30-day emission rates) are explained in detail in section 8.5 of the 
RTC.
    Table 2 in the Miller/Sahu report depicts BART-1 as ``EPA BART (No 
Corrections),'' showing a value of 379,152 tons of cumulative 
NOX emissions over 2009-2044 that is nowhere traceable to 
EPA's documents.\137\ The Miller/Sahu report then makes several 
``corrections'' to reach a value of 280,554 tons of NOX 
emissions. EPA has explained in detail why we disagree with each of the 
Miller/Sahu ``corrections'' in section 8.5 of the RTC and references 
therein. For the reasons set forth in section 8.5, we also continue to 
disagree that our calculation of the BART Benchmark or the 
NOX Cap has relied on any incorrect inputs.
---------------------------------------------------------------------------

    \137\ Miller/Sahu Report, Table 2 at p. 7.
---------------------------------------------------------------------------

    Because we disagree with the ``corrections'' and the values 
presented in the Miller/Sahu report, we also disagree with the 
conclusions of Miller/Sahu that the TWG Alternative fails to satisfy 
our requirements for demonstrating an alternative is ``better than 
BART''. The commenter cannot change the fact that its alternative 
preferences on the inputs for calculating BART are just preferences by 
simply calling them ``corrections.''
    Comment: Visibility modeling under the TWG Alternative.
    One commenter stated that the TWG Alternative distributes emissions 
over time very differently than BART: While BART would require 
NOX reductions within 5 years, the bulk of the reductions in 
the TWG Alternative might not come until the end of the 2009-2044 
period. The commenter stated that the additional analysis and modeling 
it conducted reveals that the TWG Alternative is likely substantially 
worse than BART.
    Response: As discussed elsewhere in this document, because emission 
reductions achieved under the TWG Alternative will have the same 
geographic distribution as emission reductions under BART, EPA 
disagrees that visibility modeling is required for our evaluation of 
the TWG Alternative. We note that the commenter provided its own 
visibility modeling and EPA disagrees with methodologies used and 
conclusions drawn by the commenter.
    The Miller/Sahu Report compared anticipated visibility impacts from 
the TWG Alternative against the anticipated visibility impacts based on 
its own preferences for the NOX Cap and BART Benchmark. 
Although the commenter asserts that its analysis shows that visibility 
under the TWG Alternative is substantially worse than under its 
preferences for the BART Benchmark and NOX Cap, their 
analysis also shows that when the TWG Alternative is compared to the 
BART Benchmark and NOX Cap as proposed by EPA, the TWG 
Alternative scenarios it explored that meet the 2009-2044 and 2009-2029 
NOX Caps (as applicable) generally result in lower or 
comparable visibility impacts as BART.\138\
---------------------------------------------------------------------------

    \138\ See Exhibit 2 to the Miller/Sahu report and RTC and 
references therein.
---------------------------------------------------------------------------

    EPA conducted visibility modeling to compare TWG Alternatives A1, 
A2, and A3 in 2019 and 2030 against the BART Benchmark.\139\ As 
indicated by commenters, other possibilities exist beyond the scenarios 
for the TWG Alternatives we considered explicitly in our Supplemental 
Proposal. EPA has stated elsewhere that we need not consider potential 
emissions under all possible scenarios in setting the NOX 
Cap, but must verify that NGS can reasonably be expected to comply with 
2009-2044 NOX Cap under the various constraints imposed 
under the TWG Alternatives (i.e., closure, curtailment, and a secondary 
2009-2029 NOX cap). However, EPA explored two other 
possibilities under TWG Alternative A3 that included reducing capacity 
on all three units equally or reducing capacity on two units and 
installing SCR on the two units that operate at reduced capacity.\140\ 
EPA did not include those two additional possibilities under TWG 
Alternative A3 in our visibility modeling analysis because those 
scenarios do not reduce emissions sufficiently to meet the 2009-2044 
NOX Cap.
---------------------------------------------------------------------------

    \139\ See RTC and references therein.
    \140\ Id.
---------------------------------------------------------------------------

    Our visibility modeling of the TWG Alternatives compared to our 
proposed BART determination shows that, as expected, during the 
approximate 10-year period between 2019 and 2030, the visibility 
impacts of NGS under the TWG Alternatives are higher than the 
visibility impacts of NGS under BART. After 2030, when NGS achieves 
additional emission reductions through compliance with a limit of 0.07 
lb/

[[Page 46541]]

MMBtu on two units, our modeling indicates that the visibility impacts 
under the TWG Alternatives are comparable to or lower than visibility 
impacts under BART (see RTC for further detail). These results are not 
surprising and mirror the comparative reduction in NOX 
emissions under the TWG Alternatives and the BART Benchmark over time, 
showing greater overall visibility improvement under the TWG 
Alternative than under the BART Benchmark.
    As noted elsewhere in the RTC, EPA is including as part of the TWG 
Alternative, in the regulatory language in the Final Rule, a provision 
consistent with the TWG Agreement that the operator of NGS permanently 
cease conventional coal-fired generation by the end of 2044. Thus, 
under the TWG Alternative, the visibility impact of NGS is likely to be 
zero or near zero in 2045 and thereafter.\141\ Under BART, there would 
be no commitment or enforceable requirement to close after 2044, 
therefore, visibility impacts of NGS at all 11 Class I areas would be 
expected to continue in 2045 and thereafter.
---------------------------------------------------------------------------

    \141\ EPA expects that if the Navajo Nation elects to operate 
NGS after the owners have ceased conventional coal-fired generation, 
this would likely involve substantial modifications to NGS and NGS 
would be subject to all applicable regulatory and permitting 
requirements in existence at that time.
---------------------------------------------------------------------------

    Comment: Economic Impacts of the TWG Alternative.
    The Hopi Tribe expressed concern that EPA did not assess the 
potential economic impacts of the TWG Alternative to the Hopi Tribe. 
The commenter opined that EPA recognized the significance of NGS to the 
Hopi Tribe in its analysis under Factor 2. Because the TWG Alternative 
includes closure of at least one unit in 2019, and EPA did not address 
the potential economic impacts of partial closure of NGS on the Hopi 
Tribe, the commenter contended that the Agency has not complied with 
the RHR and BART Guidelines. The Hopi Tribe noted that in the event 
capacity is reduced at NGS under the Supplemental Proposal, the amount 
of coal and water purchases from the Tribe would decrease leading to a 
decrease in income to the tribe from the sale of these. The commenter 
also stated that the Supplemental Proposal is not as effective in 
improving air quality and visibility for the Hopi Reservation. 
Extending the timeframe during which NGS can continue to operate 
without SCR or an equivalent technology would cause a continued air 
quality burden on the Hopi Tribe.
    Response: EPA recognizes that the TWG Alternative, which includes 
closure of one unit at NGS or equivalent curtailment of operation, may 
change the royalties and other payments related to coal and water that 
are paid to the Hopi Tribe. Although EPA evaluated cost-effectiveness 
and affordability of the options in our analysis of BART controls, we 
disagree that we must also conduct an economic impact analysis for 
alternatives to BART. The BART Guidelines provide little guidance on 
the evaluation of alternatives to BART and the RHR does not require an 
analysis of economic impacts of BART Alternatives. EPA's evaluation of 
potential impacts to tribes in our analysis of BART controls was used 
to inform our government-to-government consultation with tribes and is 
consistent with BART. In addition, we have held numerous government-to-
government consultation meetings with tribes to discuss NGS during this 
rulemaking. EPA continues to recognize the issues and concerns of 
tribes located in Arizona regarding NGS and is committed to continuing 
to work with our federal partners and the tribes through the Joint 
Federal Agency Work Group on NGS to help address these issues.
    The Hopi Tribe also expressed concern that the TWG Alternative is 
less effective than BART at improving air quality and visibility on the 
Hopi Reservation. EPA notes that the purpose of the RHR is to reduce 
visibility impairment at Class I areas; however, EPA disagrees that the 
TWG Alternative is less effective than BART. Although the timeframe for 
implementation of the TWG Alternative (new reductions in 2019 and 2030) 
is longer than the timeframe for BART (in 2019), we note that BART 
would only reduce emissions of NOX, whereas the TWG 
Alternative, in 2019, would also reduce emissions of SO2, 
PM, CO2, and hazardous air pollutants as a result of the 
closure of one unit (or equivalent curtailment).
    Comment: Support for some changes EPA made to the TWG Agreement in 
the Supplemental Proposal.
    The TWG noted that there were several differences between Appendix 
B to the TWG Agreement and EPA's Supplemental Proposal of the TWG 
Alternative. The commenters expressed support for some of the 
differences, and expressed concern with others. One commenter agreed 
with the methodology that EPA used to calculate the 2009-2044 
NOX Cap of 494,899 tons.
    The commenter supported the additional requirement to report annual 
heat input, although this information is already reported through the 
Acid Rain Program. However, the commenters requested that additional 
time be provided to ensure that the data submitted in the annual report 
are consistent with the data that the NGS operator submits to the Clean 
Air Markets Database (CAMD), in the annual emission inventory, and in 
the greenhouse gas (GHG) report required by 40 CFR part 98, which are 
not due until March 31st.
    Response: EPA recognizes that the TWG supports some of the changes 
EPA made to Appendix B to the TWG Agreement, including EPA's revisions 
to the 2009-2044 NOX Cap and the requirement to report 
annual heat input. EPA agrees that it is reasonable to require the 
timeframe for the reporting requirements under BART to generally be 
more consistent with other reporting requirements. Therefore, EPA is 
revising the regulatory language accordingly.
    Comment: Suggested addition to Sec. Sec.  49.5513(j)(4)(iv)(A) and 
(B).
    The TWG requested that EPA clarify the scope and content of the 
title V permit revision that is necessary to incorporate elements of 
the BART alternative by adding the language from Appendix B of the TWG 
Agreement to the requirements of the TWG Alternative.
    Response: EPA did not include the language from the TWG Agreement 
related to the title V (part 71) operating permit in the regulatory 
language in our Supplemental Proposal because the title V (part 71) 
regulations require that the operating permits include all applicable 
requirements, which for NGS would include the permit limits that exist 
in its PSD permit (i.e., the limit of 0.24 lb/MMBtu when operating with 
LNB/SOFA) as well as the final requirements in this FIP (e.g., the 
limit of 0.07 lb/MMBtu on two units in 2030). Therefore, a specific 
requirement in the FIP that directs the operating permit to incorporate 
applicable requirements is not necessary. However, to the extent the 
TWG requests consistency with the language in the TWG Agreement, 
although EPA considers it unnecessary, EPA will amend Sec.  
49.5513(j)(4)(iii) as suggested by the commenter.
    We further note that in the proposed regulatory language in our 
Supplemental Proposal, EPA inadvertently did not specify an averaging 
period for the emission limits under the TWG Alternative Operating 
Scenarios (Sec.  49.5513(j)(3)). Therefore, EPA is adding to the 
regulatory language that emission limits apply over a rolling average 
of 30 boiler operating days, to 40 CFR Sec.  49.5513(j)(3), 
(j)(3)(i)(A)(2), (j)(3)(i)(B)(3), and (j)(3)(i)(C)(2).
    Comment: Another suggested addition to Sec. Sec.  
49.5513(j)(4)(iv)(A) and (B).

[[Page 46542]]

    The TWG stated that the Supplemental Proposal specified a 
short[hyphen]term NOX limit of 0.07 lb/MMBtu for TWG 
Alternative A, but not for Alternative B as was included in the TWG 
Agreement.
    Response: EPA agrees that if the owners of NGS elect to install SCR 
in order to comply with the applicable NOX Caps under TWG 
Alternative B, then it is useful to specify the emission limit that 
would apply. Although the limit of 0.07 lb/MMBtu (on a rolling average 
basis of 30 boiler operating days) would apply under TWG Alternatives 
A1, A2, A3, or B, EPA notes that the operator of NGS may need to 
operate SCR at an emission rate that is lower than 0.07 lb/MMBtu 
depending on their compliance with the NOX Cap, but the 
addition of this provision would prohibit emissions of NOX, 
when operating with SCR, to exceed 0.07 lb/MMBtu (on a rolling average 
basis of 30 boiler operating days). EPA will amend the regulatory text 
accordingly.
    Comment: Omitted ownership outcome.
    The TWG stated that the EPA described the NGS ownership outcomes in 
a manner that is different from the scenarios outlined in the TWG 
Agreement. The commenter indicated that the ownership outcomes appear 
to be consistent, except that one potential outcome was omitted--the 
scenario in which one or more of the existing NGS Participants (LADWP 
or NV Energy) remain in NGS, which would trigger Alternative B.
    Response: EPA agrees that we inadvertently omitted from Sec.  
49.5513(j)(3)(ii)(D) the potential scenario where one or both of the 
Departing Participants (i.e., LADWP or NV Energy) do not exit NGS as 
expected. EPA is updating the language to incorporate the omitted 
ownership possibility.
    Comment: Describe details of TWG Agreement more fully in the 
preamble to the Final Rule.
    The TWG expressed concern that EPA only briefly described the 
elements of the TWG Agreement in the Supplemental Proposal. One member 
of the TWG asserted that the limited discussion does not accurately 
present the provisions of the Agreement as it relates to clean energy 
economic development for affected Tribes, the rigorous development and 
consideration of clean energy alternatives to NGS, mitigation of 
CO2 emissions, and Local Benefit Fund to address concerns of 
the public in the vicinity of NGS and the Kayenta-Black Mesa Mine 
Complex. Should EPA proceed with this alternative in the Final Rule, 
the commenter requested that the Agency fully describe the key elements 
in the preamble to the Final Rule.
    Response: EPA acknowledges that the TWG Agreement contains 
additional provisions that will be beneficial to the tribes in the area 
and to the environment. However, EPA does not consider it appropriate 
to provide a detailed discussion of these additional provisions of the 
TWG Agreement in our Final Rule. EPA was not a signatory to the TWG 
Agreement and did not participate in the TWG Stakeholder group. The TWG 
Agreement speaks for itself and the participants and signatories are 
the appropriate entities to interpret the provisions of the TWG 
Agreement. EPA is finding that it is necessary or appropriate to 
regulate NOX emissions from NGS to reduce visibility 
impairment at the GCNP and 10 other Class I areas. The other measures 
described by the commenter are outside the scope of our authority for 
this action. Therefore, EPA is declining to provide any further 
discussion of the provisions in the TWG Agreement that go beyond 
addressing regional haze concerns associated with NOX 
emissions from NGS.
    The comment also requests EPA to add certain language to the Final 
Rule. Specifically, the comment asks EPA to add: ``Nothing in this 
final rule shall preclude the NGS Participants from seeking to obtain 
greenhouse gas emission reduction credits, or similar commodities 
associated with activities committed to in the TWG Agreement, under any 
Federal or State law or policy to the extent permitted under such 
applicable law or policy.''
    EPA is also declining to add the requested language to our Final 
Rule. EPA is not exercising any authority in this action other than 
implementing the BART provisions in CAA section 169A and the RHR, 
through our discretion in the TAR. It would be inappropriate in this 
action to take any position on the future use or regulation of GHG 
emission reductions or ``similar commodities.''
    Comment: TWG Alternative meets Reasonable Progress requirements.
    One member of the TWG stated that the TWG Alternative was intended 
to meet not only BART requirements, but also reasonable progress 
requirements applicable to NGS through 2044. The commenter requested 
that EPA acknowledge, in the preamble to the Final Rule, that the TWG 
Alternative satisfies both the BART and reasonable progress 
requirements of the CAA through 2044.
    Response: Today's final rule addresses the NOX BART 
requirements of the RHR for NGS. We have not considered whether the TWG 
Alternative meets the reasonable progress requirements for NGS. We note 
that EPA has not made any finding pursuant to 40 CFR 49.11(a) that it 
is necessary or appropriate at this time to promulgate a FIP to meet 
the reasonable progress or other requirements under the RHR. The 
requirement for states to develop reasonable progress goals and long-
term strategies to achieve those goals is set out in CAA section 169A 
and 40 CFR 51.308(d). There is no requirement that EPA address these 
requirements for sources on the Navajo Nation unless EPA makes a 
determination that it is necessary or appropriate for EPA to do so.
    Comment: Delete requirement to keep records of maintenance.
    One member of the TWG requested that EPA delete the requirement 
that the NGS operator keep records of all major maintenance activities 
that occur at NGS. According to the commenter, the existing title V 
permit, which requires that the operator maintain and operate emission 
control equipment in a manner that is consistent with good engineering 
practices to keep emissions at or below applicable emissions 
limitations, provides sufficient assurance that emission control 
equipment will be operated and maintained in accordance with best 
practices.
    Response: EPA is deleting the requirement proposed under Sec.  
49.5513(j)(7)(vi) to require the operator of NGS to keep records of all 
major maintenance activities at NGS because records of major 
maintenance activities are not needed for demonstrating compliance with 
the 2009-2044 or 2009-2029 NOX Caps or other provisions of 
the TWG Alternative.
    Comment: Require recordkeeping for the life of the plant.
    One commenter indicated that the requirement to maintain records 
for 5 years is insufficient and inappropriate for the compliance 
schedule associated with NGS and recommended that records be maintained 
from 2009 through the remaining operating life of the plant.
    Response: EPA agrees that because the operator of NGS must ensure 
compliance with the 2009-2044 NOX Cap, the operator of NGS 
should also maintain records for the life of the facility to 
demonstrate compliance with the TWG Alternative. In the regulatory 
language in our Final Rule, EPA is amending Sec.  49.5513(j)(7) to 
require the owner or operator of each unit to maintain records, as 
required under Sec.  49.5513(j)(7)(i) to (vi), until the earlier of 
December 22, 2044 or the date that

[[Page 46543]]

the owners cease conventional coal-fired operation of all units at NGS.
    Comment: Concern that affected parties were excluded from TWG.
    Numerous commenters expressed frustration that all affected parties 
were not included in the development of the TWG Alternative. The Hopi 
Tribe noted that they have a Generating Performance Agreement with SRP 
that should have mandated their involvement. The White Mountain Apache 
Tribe also noted that it was not party to the TWG Agreement. Another 
commenter noted that Executive Order (EO) 13175 requires that all 
tribal nations be consulted on these types of regulations, and asserted 
that EPA and DOI violated this EO. Another commenter argued that the 
TWG did not include grassroots organizations and discouraged their 
participation in TWG public forums.
    One commenter stated that the EPA did not give the public enough 
time to comment on the TWG Alternative before proposing approval of it 
and, on that basis, demanded that the EPA withdraw its proposed 
approval. The commenter added that the TWG Agreement assumes that the 
Hopi will support the Kayenta Mine Lease extension when it expires in 
2025, but the Hopi have yet to discuss the extension with the 12 Hopi 
independent villages, which is a requirement in the Hopi Constitution. 
Furthermore, the commenter noted that the TWG Agreement ignores the 
requirement of completing an EIS and ROD before the NGS site lease with 
the Navajo Nation expires in 2019. The commenter argued that DOI's 
signing of the TWG Agreement, without the fulfillment of these 
requirements, violates NEPA. The commenter added that in 1989, the Hopi 
Tribe rejected the Draft Kayenta Mine-Black Mesa Mine EIS in its 
entirety, and implied that the decision to accept the TWG proposal 
could compromise EPA's final decision.
    Response: EPA recognizes that there are affected tribes and other 
stakeholders that were not invited to participate in the Technical Work 
Group. EPA was not involved in the formation of the TWG and not 
involved in any meetings or discussions of the TWG.\142\ As discussed 
in section 10.0 of the Response to Comments document, consistent with 
Executive Order 13175: Consultation and Coordination with Indian Tribal 
Governments, EPA consulted with tribes early and regularly during the 
development of this rulemaking for NGS. We note that the Regional 
Administrator for Region 9 spoke with Chairman of the Hopi Tribe, LeRoy 
Shingoitewa, on September 13, 2013 about the TWG Alternative and 
notified elected leaders or legal counsel for five tribes when EPA 
signed the Supplemental Proposal. EPA also held individual and joint 
consultation meetings with tribal leaders in Phoenix, Arizona on 
December 9 and 10, 2013.
---------------------------------------------------------------------------

    \142\ At the request of the TWG, at their kick-off meeting, EPA 
presented a summary of our Proposed Rule and framework for BART 
Alternatives. The presentation at the TWG kick-off meeting was 
generally the same presentation EPA provided to other stakeholders. 
See document 0033 in the docket for the rule.
---------------------------------------------------------------------------

    EPA disagrees that we did not provide the public enough time to 
review the TWG Alternative. EPA posted the TWG Alternative to the 
public docket on July 26, 2013, the same day it was submitted to 
EPA.\143\ EPA reviewed the TWG Alternative and on September 25, 2013, 
signed a Supplemental Proposal that put forth the TWG Alternative as an 
additional better than BART alternative for public comment. On October 
22, 2013, the Supplemental Proposal was published in the Federal 
Register.\144\ The public had nearly six months to review the TWG 
Agreement and Alternative as submitted to EPA and approximately three 
months to review and comment on EPA's Supplemental Proposal. EPA also 
notes that EPA's rulemaking is not subject to NEPA.
---------------------------------------------------------------------------

    \143\ See document number 0122 in the docket for this rule.
    \144\ See document number 0182 and 0186 in the docket for this 
rule.
---------------------------------------------------------------------------

    Comment: EPA's relationship to the TWG is confusing.
    The White Mountain Apache Tribe stated that although EPA stated it 
was not involved in the Technical Work Group, EPA was a signatory of 
the ``Joint Federal Agency Statement Regarding Navajo Generating 
Station,'' the scope of which includes numerous elements that reference 
EPA's commitments, along with the Departments of the Interior and 
Energy, in relation to NGS. The commenter suggests that EPA was 
involved in a legal triangulation with the TWG signatories and that 
such action is an extra-jurisdictional exercise by EPA, to which the 
Tribe does not consent. The commenter concludes that the Tribe cannot 
consider the TWG Alternative unless its published form is changed by 
EPA to fully disentangle the proposal from the signatory group and all 
non-BART Agreement terms, and additional public comment is thereafter 
allowed.
    Response: We disagree that the Joint Federal Agency Statement 
Regarding Navajo Generating Station indicates that EPA was involved in 
the TWG. The Joint Federal Agency Statement was signed by the 
Administrator of EPA and the Secretaries of the Interior and Energy on 
January 4, 2013. Among other things, that document acknowledged that 
each of the three federal agencies has an interest in the operation of 
NGS and set forth the goals of the agencies with respect to NGS and 
energy production in the region served by NGS.
    Although EPA clearly has an interest in reducing the visibility 
impacts of NGS, EPA was not part of the TWG. EPA did not participate in 
any of the substantive discussions and negotiations of the TWG. Two 
representatives of EPA attended the beginning of the first meeting of 
the TWG but only to present a summary of EPA's February 5, 2013 
Proposed Rule.\145\ After the initial meeting, EPA was not involved 
with the TWG until the TWG Agreement was completed. As such, EPA 
disagrees with the commenter that EPA is ``entangled'' with the TWG.
---------------------------------------------------------------------------

    \145\ At the request of the TWG, at their kick-off meeting, EPA 
presented a summary of our Proposed Rule and framework for BART 
Alternatives. The presentation at the TWG kick-off meeting was 
generally the same presentation EPA provided to other stakeholders. 
See document 0033 in the docket for the rule.
---------------------------------------------------------------------------

    The TWG was not primarily composed of federal agencies. The TWG had 
two Tribes (Gila River Indian Community and the Navajo Nation), two 
environmental organizations (Environmental Defense Fund and Western 
Resource Advocates), two Arizona utilities (CAWCD and SRP) and DOI. 
Appendix B of the TWG Agreement contains provisions relating to BART 
but there were several other provisions of the TWG Agreement that are 
beyond the scope of BART and are not part of EPA's rulemaking in this 
action.
    For all the above reasons, EPA does not agree with the assumption 
underlying the comment that the White Mountain Apache Tribe ``cannot 
consider the TWG Alternative unless its published form is changed by 
EPA to fully disentangle the proposal from the signatory group and all 
non-BART Agreement terms.'' EPA does not agree that any further public 
comment is warranted.

K. Other BART Alternatives

    Comment: Suggested BART Alternative from EarthJustice.
    Despite its objections to the proposed BART alternatives, one 
commenter suggested an alternative that includes (1) an enforceable 
requirement that one NGS unit shut down by 2020 and (2) an enforceable 
requirement that the remaining two units install SCR and meet a 
NOX emission limit of 0.065 lb/MMBtu by the beginning of 
2020. The

[[Page 46544]]

commenter recognized that other alternatives may exist, but asserted 
that for any alternative to comply with the minimum legal requirements, 
it must produce better visibility outcomes in Class I areas than BART 
and demonstrate that it does so through the use of visibility modeling.
    Response: Neither the BART requirements nor the provisions in the 
RHR governing alternatives to BART requires that BART sources cease 
operation. As such, EPA does not consider it appropriate for the Agency 
to require the shutdown of one unit of NGS by 2020 absent the consent 
of the owners. Regardless of whether the suggested alternative would 
provide for earlier and greater visibility improvement, it is not an 
option at this time. As explained in this rulemaking, the TWG 
Alternative does comply with the legal requirements for BART 
alternatives.
    Comment: Suggested BART Alternative from CAP NIA Users: New 
controls should not be required until after 2030.
    One commenter presented a table purporting to show EPA's 
calculations of the NOX caps that would apply for a range of 
potential BART emission limits: 0.055, 0.06, 0.07, and 0.15 lb/MMBtu. 
According to the commenter, the NOX cap that would apply 
under limits of 0.06 and 0.07 lb/MMBtu would exceed the proposed 2009-
2044 NOX CAP by 2.5 and 7.5 percent, respectively. The 
commenter asserted that these differences would have imperceptible 
impacts on visibility and that, therefore, the use of the 
NOX cap based on a limit of 0.055 lb/MMBtu unduly 
constrained TWG Alternative A and resulted in an unwarranted 
requirement to install SCR on two NGS units by 2030, which would impose 
inequitable compliance costs on agricultural water users. The commenter 
stated that a NOX cap based on a BART limit of 0.06 or 0.07 
lb/MMBtu would be very similar to the proposed 2009-2044 NOX 
Cap, but would provide enough of an incremental increase to add 3 years 
of additional compliance flexibility for the installation of SCR on two 
units.
    The same commenter also stated that based on the 2009-2044 
NOX Cap as proposed in the Supplemental Proposal, TWG 
Alternative A contains unused ``headroom'' that renders the operation 
of SCR by 2030 unnecessary. According to the commenter, TWG Alternative 
A has the effect of forcing NOX emissions to a level that is 
at least 33,000 tons below the NOX cap, which the commenter 
believes makes the requirement to install and operate SCR by 2030 
artificially stringent and unnecessary, and therefore arbitrary and 
capricious. The commenter indicated that the headroom under TWG 
Alternative A1 would yield more than 6 years of additional compliance 
flexibility for the operation of SCR, and TWG Alternatives A2 and A3 
would yield more than 3 years. The commenter concluded that EPA should 
revise the TWG Alternatives to provide the maximum amount of compliance 
flexibility for installation of SCR on NGS so as to not unnecessarily 
impose costs on NIA water users.
    Response: EPA disagrees with the assertion that new controls should 
not be required until after 2030. As stated previously, the TWG 
Agreement was a negotiated agreement, submitted to EPA, representing 
diverse interests. EPA evaluated the TWG Alternative to determine 
whether it was consistent with our framework for better than BART 
alternatives. Thus, although a few commenters may believe that the 
timeframes for compliance in the TWG Alternative are too stringent, the 
TWG Alternative is consistent with our proposed framework and it is 
consistent with the level of control in Appendix B to the TWG 
Agreement, which the operator and owners of NGS, as well as CAP, two 
tribes and two environmental organizations, have determined is 
acceptable.
    As stated elsewhere in the RTC, we disagree with the assertion that 
BART for NGS is an emission limit associated with SNCR (0.15 lb/MMBtu) 
or a less stringent limit associated with SCR (0.06 or 0.07 lb/MMBtu). 
Therefore, the additional time for compliance suggested by the 
commenters using higher BART Benchmarks or NOX Caps is not 
appropriate. The commenters further assert that NGS could comply with a 
limit of 0.07 lb/MMBtu in 2032 and 2033 and still maintain total 
emissions below the 2009-2044 NOX Cap. EPA disagrees with 
commenters that the ``unused headroom'' warrants additional time to 
comply with the limit of 0.07 lb/MMBtu. The emission estimates that EPA 
presented in our Supplemental Proposal for the TWG Alternative involved 
projecting future emissions to 2044 based on average heat input at NGS 
over 2001-2008. Heat input in the future is expected to be variable and 
could possibly remain higher than average over an extended period of 
time, significantly affecting the total flexibility or compliance 
margin. EPA's analysis was provided simply to assess whether operation 
consistent with the requirements under each TWG Alternative (A1-A3) 
could reasonably be determined to maintain emissions below the 2009-
2044 NOX Cap and were not intended to represent actual year-
by-year emissions in the future. Thus, the ``unused headroom'' is 
theoretical and could be smaller or larger than cited by the 
commenters.

L. Other Comments

    Comment: Disproportionate impacts to tribes.
    The Tonto Apache Tribe and the San Carlos Apache Tribe commented 
that both the original BART proposal and the proposed TWG Alternative 
are contrary to the obligations of the United States and its trust 
responsibilities to Indian Tribes under CAP. The commenters stated that 
both regulatory programs would have disproportionate impacts on tribes 
with CAP contracts. The commenters noted that environmental quality is 
of utmost importance to the tribes, but that clean air is the 
responsibility of all citizens. Therefore, the commenters assert that 
because the United States owns 24.3 percent of NGS, the costs of 
compliance for that 24.3 percent share should be shared among all 
American people, who will benefit from cleaner air. The commenters 
urged EPA to develop an alternative regulation that does not place 
additional burden on Indian Tribes.
    Response: EPA agrees that our proposed BART determination and the 
TWG Alternative will impact tribes with CAP water contracts. We note 
that the Joint Federal Agency Statement on NGS reflects the U.S. 
Government's recognition of its responsibilities related to NGS and 
trust responsibility to Indian tribes affected by NGS.
    Although EPA is finalizing a BART Benchmark for NGS, the regulatory 
requirements of this Final Rule will include only the requirements and 
compliance timeframes for the TWG Alternative as proposed in our 
Supplemental Proposal. Under the TWG Alternative, emission reductions 
at NGS would be achieved in phases, including closure of one unit or 
the equivalent in 2019, and compliance with an emission limit 
achievable with SCR in 2030. We note that the closure of one unit was 
possible because of the planned divestment of LADWP and NV Energy from 
NGS by 2019. Because LADWP and NV Energy are unrelated to CAP, EPA does 
not expect substantial compliance costs to be borne by Reclamation (and 
thus, tribes or other CAP water users) due to the first phase of 
emission reductions at NGS in 2019. EPA further notes that the 2030 
compliance date for meeting an emission limit achievable with SCR on 
two units at NGS is approximately 16 years from the present day. As 
stated elsewhere in the RTC, the requirements

[[Page 46545]]

under BART and the TWG Alternative include emission limits, rather than 
technology requirements. Thus, 16 years from now, although SCR will be 
capable of meeting the emission limit, other technologies or options 
may become available for the operator of NGS to more cost-effectively 
meet the NOX emission limit of 0.07 lb/MMBtu.
    EPA recognized the potential impacts to tribes of our proposed BART 
determination and sought ways to provide flexibility and a framework 
for affected stakeholders to develop alternative approaches to BART. 
EPA has determined that the TWG Alternative achieves greater emission 
reductions than would otherwise be achieved under our BART 
determination, while providing additional time for compliance. This 
additional time allows the DOI, DOE, and EPA time to work with tribal 
stakeholders to identify and implement strategies for achieving the 
goals outlined in the Joint Federal Agency Statement on NGS.
    Comment: EPA lacks authority to regulate NGS
    Several commenters indicated that EPA overstepped its authority and 
stated that EPA's proposal hinders the state's ability to deal with 
environmental issues on a local level. One commenter stated that EPA's 
regulations are an attack on free enterprise, and believes that the 
agenda of the current administration is to ban all coal-fired power 
plants regardless of the economic effect.
    Response: EPA disagrees that it has overstepped its regulatory 
authority and disagrees that any State has authority to regulate air 
pollution from sources located on the Navajo reservation. EPA's 
authority to regulate NGS is established in sections 301(a) and 
301(d)(4) of the CAA and the TAR. Section 301(d)(4) authorizes EPA to 
directly administer provisions of the CAA in Indian country under 
certain circumstances. The State of Arizona lacks authority to regulate 
air pollution sources located on the Navajo reservation.
    EPA disagrees that the regulations promulgated in this action, 
which are requirements consistent with the TWG Agreement, constitutes 
an attack on free enterprise. The TWG Alternative was submitted to EPA 
by a stakeholder group that had determined it was a more cost-effective 
approach to continuing to operate NGS than a prior proposal by EPA. EPA 
considered the direct costs of compliance in our five-factor BART 
analysis, and although not specifically required in the BART 
Guidelines, EPA also considered numerous indirect impacts and costs in 
our analysis of Factor 2. The comment provides no information other 
than conclusory statements that EPA failed to adequately consider the 
cost of compliance. EPA also disagrees that there is any agenda or 
effort to ban coal burning electricity generation. The TWG Agreement, 
as agreed upon by the members of the TWG, includes a provision that 
specifies continued operation of NGS as a conventional coal-fired power 
plant until 2044 when its lease with the Navajo Nation expires. 
Therefore, this rulemaking does not constitute a ban on burning coal.
    Comment: Lack of Consultation with Tribes.
    The Navajo Nation commented that EPA should improve communication 
at the start of any rulemakings to ensure that the Navajo Nation can 
provide meaningful information. The commenter said that even when the 
Agency develops supporting rule information like the RIA the Navajo 
Nation would like to be involved as it could impact the Nation. The 
commenter pointed out that EPA has known for decades that the Navajo 
Nation would be impacted by regulation of NGS and FCPP. The commenter 
quoted excerpts from Executive Order 13175--Consultation and 
Coordination with Indian Tribal Governments and said that the standard 
for determining if a regulation has tribal implication is not whether 
it ``impose[s] substantial direct compliance costs on tribal 
governments,'' but rather a regulation has ``substantial direct effects 
on one or more Indian tribes.''
    The Navajo Nation stated that it was not consulted during the 
development of the ANPR and indicated that in August of 2009, one day 
prior to the ANPR for NGS and FCPP, EPA made a courtesy call to the 
President of the Navajo Nation. The Navajo Nation believes that if 
early and meaningful consultation with the Nation had occurred this 
could have led to an adequate analysis of BART controls and careful 
examination of non-air quality impacts.
    The Gila River Indian Community expressed similar concerns 
regarding the lack of consultation. During a consultation on August 7, 
2012, the commenter stated that it was their understanding that EPA 
would describe to the Community the proposed regulation prior to the 
rulemaking being issued. Instead, the commenter said, EPA called the 
night before issuing the rule, which the commenter said was inadequate 
and inconsistent with the expectations regarding consultation. The 
commenter also understood that the rule was to be proposed in September 
2012 but it was not proposed until January 2013 and in the meantime 
several stakeholders provided additional input to the Agency. However, 
the Community was not consulted during this time. In addition, the 
Community expects an explanation of the final rule after it is issued 
by EPA.
    The Hopi Tribe also commented on the lack of consultation and 
involvement of tribes in developing the regulation. The commenter 
submitted multiple letters to EPA indicating its concern about not 
being involved in the development of the rule or consulted but without 
providing pertinent information. In one of the letters, the commenter 
said that the government acknowledged the Hopi Tribe as a stakeholder 
and the intention to work with the Tribe; however, contrary to 
statements in the Joint Federal Agency Statement on NGS to work with 
tribes, the Hopi Tribe was not included in the TWG.
    The Hopi Tribe specifically indicated that it was denied 
information regarding the TWG Alternative and the development of the 
alternative, something the commenter pointed out is essential in order 
to provide relevant and useful comments to EPA. The commenter said that 
it has submitted two Freedom of Information Act (FOIA) requests to DOI, 
which included documentation related to NGS and information documenting 
DOI's representation of the Hopi Tribe during the negotiation of the 
TWG Alternative. The commenter said that until it has the information 
requested via FOIA, it is not able to provide written comments on the 
TWG Alternative.
    The Hopi Tribe asserted that it is has been treated differently 
than other tribal stakeholders in the TWG Agreement. For example, the 
TWG Agreement states that SRP will advocate to EPA the Navajo Nation's 
treatment as state (TAS) status. The Hopi Tribe indicated that the TWG 
Alternative protects the economic interests of the Navajo Nation and 
the Gila Indian Community but compromises the coal revenues of the Hopi 
Tribe and contains no mitigation measures for the significant and 
adverse economic impact. The Hopi Tribe indicated that it will be 
disproportionately and adversely affected by the reduced capacity at 
NGS.
    The Kaibab Band of Paiute Indians expressed similar concerns 
regarding the lack of involvement of Indian Tribes and demanded that 
EPA consider the requests of the Kaibab Paiute. The commenter referred 
to the TWG Agreement and requested that the Kaibab Paiute Indian 
Reservation receive $2.5 million of the $5 million

[[Page 46546]]

Local Benefit Fund designated for community projects within 100 miles 
of NGS (the reservation is 60 miles from NGS). Also, the commenter said 
that the TWG Agreement promotes the development of clean energy, and 
based on that provision of the agreement, the commenter requested a 250 
MW solar farm.
    The Tohono O'odham Nation objected that a number of Indian nations 
that would be substantially affected by the rule were excluded from the 
TWG. The commenter noted that it is particularly concerned with 
maintaining CAP water delivery under whatever rule is finalized by EPA.
    Response: EPA understands the importance of NGS to numerous tribes 
located in Arizona and the importance of our trust responsibility to 
Indian tribes affected by NGS. As a result, we have attempted to ensure 
that these tribes were consulted throughout the rulemaking process. We 
respectfully disagree that there was a lack of consultation with 
tribes.
    EPA agrees with the Navajo Nation that Executive Order 13175 
defines ``policies that have tribal implications'' to refer to 
regulations or other actions that have substantial direct effects on 
one or more Indian tribes.\146\ We disagree that EPA's discussion of 
direct compliance costs on tribal governments is not a correct standard 
for consideration and note that section 5(b) of EO 13175 further states 
that
---------------------------------------------------------------------------

    \146\ http://www.gpo.gov/fdsys/pkg/WCPD-2000-11-13/pdf/WCPD-2000-11-13-Pg2806-2.pdf.

    To the extent practicable and permitted by law, no agency shall 
promulgate any regulation that has tribal implications, that imposes 
substantial direct compliance costs on Indian tribal governments, 
---------------------------------------------------------------------------
and that is not required by statute . . .

    In our discussion of EO 13175, we included consideration of 
substantial direct compliance costs to tribal governments, as well as 
the broader consideration of substantial direct effects on one or more 
Indian tribes. We conclude that our proposed action on NGS will have 
tribal implications and may have substantial indirect effects on 
tribes, but will not impose substantial direct compliance costs on 
Indian tribal governments. We also conclude that this rule is 
appropriate under the CAA because NGS is a facility that is subject to 
BART.
    In our proposed rule, EPA provided a document that listed all 
written or telephone correspondence as well as consultation meetings 
between EPA and Tribes on NGS. Although the commenter suggests that 
EPA's telephone call to the President of the Navajo Nation one day 
prior to the signature of the ANPR in August 2009 was our first 
communication with the Nation on the subject, we note that the timeline 
includes a meeting between EPA and the Navajo Nation that occurred two 
months prior to the ANPR to discuss EPA's plans to move forward on an 
ANPR related to our ongoing BART analyses for FCPP and NGS.\147\ EPA 
further notes that the ANPR was not a proposed rule. The ANPR was an 
Advanced Notice of Proposed Rulemaking where we provided the public 
advance notice of our intention to develop rulemakings for FCPP and 
NGS. EPA included some initial analysis of two of the BART factors and 
stated that the ``specific purpose of this ANPR is for EPA to collect 
additional information.'' \148\ Subsequent to the publication of the 
ANPR in the Federal Register on August 28, 2009, and prior to our 
proposed rule on NGS, EPA held four consultation meetings with tribes 
in 2009, eight consultation meetings with tribes in 2010, eight 
consultation meetings in 2011, and ten consultation meetings with 
tribes in 2012.\149\ Of these meetings, at least eight were held as 
group consultation sessions where all tribes in Arizona were invited to 
participate and were provided the opportunity to request individual 
consultation meetings as well.\150\
---------------------------------------------------------------------------

    \147\ See listed item indicating consultation meeting on June 
10, 2009 between Laura Yoshii, Acting Regional Administrator of EPA 
Region 9, and President Joe Shirley, Jr., of the Navajo Nation, to 
discuss moving forward on the ANPR for Four Corners Power Plant and 
NGS. See document titled ``2013--0109 Timeline of all tribal 
consultations on NGS.docx'' in document number 0005 in the docket 
for this rule.
    \148\ See 74 FR 44313 at 44314 (August 28, 2009).
    \149\ See document titled ``2013--0109 Timeline of all tribal 
consultation on NGS.pdf'' in document number 0005 in the docket for 
the rule at and document titled ``Updated Timeline of all Tribal 
Consultation on NGS--for Final Rule.pdf'' in the docket for the 
rule.
    \150\ Id., and see, e.g., document 0008 in the docket for the 
rule.
---------------------------------------------------------------------------

    The Navajo Nation, the Hopi Tribe, the Gila River Indian Community, 
the Tohono O'odham Nation, the Ak-Chin Indian Community, the Pascua 
Yaqui Tribe, the Fort McDowell Yavapai Nation, and the Yavapai-Apache 
Nation, and the Inter Tribal Council of Arizona submitted comments to 
EPA on the ANPR. EPA summarized and provided responses to comments 
received from tribal governments in the TSD for our proposed rule on 
NGS.\151\ The primary concerns expressed by the tribal governments 
related to the economic importance of NGS and the relationship of NGS 
with CAP and Indian Water Settlement Agreements. The Navajo Nation also 
commented on specific aspects of the five-factor analysis for BART, and 
the Hopi Tribe submitted an economic study it had commissioned that 
expresses concern that regulatory actions would force NGS to close. In 
our proposed rule and in our development of our proposed framework for 
BART Alternatives, including the credit for early installation of LNB/
SOFA, EPA recognized the importance of NGS to tribes in Arizona, both 
in contributing to the economies of the Navajo Nation and Hopi Tribe, 
and in serving as a source of electrical power for CAP and a source of 
revenue to the Lower Colorado River Basin Development Fund, as related 
to water settlement agreements with numerous tribes in Arizona. Based 
on this recognition, EPA put forth additional options for greater 
flexibility in the compliance timeframe and invited stakeholders to 
develop and submit additional BART Alternatives to EPA for 
consideration.
---------------------------------------------------------------------------

    \151\ See page 25 and 26 of the TSD to the Proposed Rule, 
document 0014 in the docket for this rule.
---------------------------------------------------------------------------

    Following the publication of our proposed rule on February 5, 2013, 
EPA engaged in 17 consultation meetings with tribes prior to the 
January 2014 close of the public comment period.\152\ Of these 
meetings, at least two were held as group consultation sessions where 
all tribes in Arizona were invited to participate and were provided the 
opportunity to request individual consultation meetings as well.\153\ 
EPA received comment letters on our proposal and Supplemental Proposal 
from the Navajo Nation, the Gila River Indian Community, the Tohono 
O'odham Nation, the Ak-Chin Indian Community, the Tonto Apache Tribe, 
the San Carlos Apache Tribe, and the Kaibab Band of Paiute 
Indians.\154\ At the request of two tribes for additional time beyond 
January 6, 2014 to submit comments, EPA agreed that we would consider 
comments from tribal governments submitted after the close of the 
comment period. The White Mountain Apache Tribe submitted comments on 
February 5, 2014.\155\ In addition, in response to their request to EPA 
for information related to NGS, we provided responsive documents to the 
Hopi Tribe on January 7, 2014.\156\ As shown in additional 
correspondence,

[[Page 46547]]

the Hopi Tribe requested additional time to submit comments, and EPA 
again agreed to consider late comments from the Hopi Tribe.\157\ EPA 
did not receive any further comments from the Hopi Tribe.
---------------------------------------------------------------------------

    \152\ See document titled ``Updated Timeline of all Tribal 
Consultation on NGS--for Final Rule.pdf'' in the docket for the 
rule.
    \153\ Id.
    \154\ See comment numbers 0340, 0317, 0387, 0402, 0419, and 0421 
in the docket for the rule.
    \155\ See comment number 0440 in the docket for the rule.
    \156\ See document titled ``2014--0107 EPA Letter to Chairman 
Honanie with Enclosure 1.pdf'' in the docket for this rule.
    \157\ See document titled ``2014--0131 Letter from Chairman 
Honanie.pdf'' and document titled ``2014--0206 EPA Response to 
Chairman Honanie--Hopi Tribe.pdf'' in the docket for this rule.
---------------------------------------------------------------------------

    Several tribes also expressed concern that the Technical Work Group 
included only two tribes, the Navajo Nation and the Gila River Indian 
Community, and excluded numerous other tribes that also have a 
significant economic interest in NGS. EPA recognizes that many tribes 
were not included in the development of the TWG Agreement. EPA was not 
involved in the formation of the TWG or any of the negotiations between 
the members of the TWG in developing the TWG Agreement. In addition, 
our evaluation of the TWG Agreement was for the sole purpose of 
determining whether Appendix B to the TWG Agreement meets our framework 
for a ``better than BART'' Alternative. Therefore, although EPA agrees 
that many tribes have economic interest in NGS and CAP, EPA does not 
have any role in the distribution of funds described in the TWG 
Agreement.
    Based on numerous consultation meetings between high-level 
officials from EPA and elected tribal leaders, beginning in 2009 and 
extending into 2013, and our development of flexible options for BART 
Alternatives in response to comments from tribes, EPA considers our 
consultation on NGS to be consistent with EO 13175 and EPA's policy to 
engage in early and meaningful consultation with tribes.\158\ EPA will 
provide notification of our Final Rule, in writing, to all tribal 
governments that submitted comments to EPA on our Proposed Rule or 
Supplemental Proposal and will provide our written responses to their 
specific comments. All written correspondence from tribal governments 
to EPA regarding NGS and our proposed BART determination is available 
in the docket for this rulemaking.\159\
---------------------------------------------------------------------------

    \158\ The EPA policy on Consultation and Coordination with 
Indian Tribes is posted on the following Web site: http://www.epa.gov/tribal/consultation/consult-policy.htm.
    \159\ See Appendix A (List of Written Comments) to the RTC and 
the docket for this rulemaking.
---------------------------------------------------------------------------

V. Summary of Final Action

    On February 5, 2013, EPA issued a proposed BART analysis of 
NOX controls at NGS. Based on that analysis, EPA proposed a 
NOX emission limit of 0.055 lb/MMBtu for all three units 
within five years of a Final Rule. Our proposed rule also set out a 
framework for evaluating BART alternatives at NGS. EPA proposed a 
``better than BART'' alternative (Alternative 1), consistent with this 
proposed framework, requiring compliance with a NOX emission 
limit of 0.055 lb/MMBtu on one unit per year in 2021, 2022, and 2023. 
EPA invited stakeholders to submit additional alternatives, consistent 
with our proposed framework for ``better than BART'' alternatives, to 
EPA for consideration.
    On July 26, 2013, a stakeholder group, known as the TWG, submitted 
an agreement among seven diverse entities (TWG Agreement) that included 
an additional BART alternative (Appendix B to the TWG Agreement). In 
general, this alternative includes closure of one unit at NGS, or 
curtailment of net generating capacity by an equivalent amount, in 2019 
and compliance with an emission limit of 0.07 lb/MMBtu on two units at 
NGS in 2030. The TWG Agreement also included a provision requiring the 
owners of NGS to cease conventional coal-fired generation at NGS by the 
end of 2044. EPA independently evaluated Appendix B to the TWG 
Agreement to determine whether it complied with the framework we put 
forth in our Proposed Rule, as well as the statutory and regulatory 
requirements in the CAA and the RHR.
    On October 22, 2013, EPA published a Supplemental Proposal. Our 
Supplemental Proposal contained a detailed evaluation of Appendix B to 
the TWG Agreement along with a discussion of our legal rationale for 
proposing to approve requirements consistent with the TWG Agreement as 
a ``better than BART'' alternative. Our Supplemental Proposal and this 
Final Rule refer to our regulations that are generally consistent with 
Appendix B to the TWG Agreement as the ``TWG Alternative.'' The 
Supplemental Proposal (i.e., the TWG Alternative) included regulatory 
requirements to achieve substantial NOX reductions over 
time, as well as a cap in cumulative NOX emissions from NGS 
over 2009-2044 (2009-2044 NOX Cap) to ensure that lifetime 
emissions from NGS under the TWG Alternative do not exceed lifetime 
emissions that would have otherwise occurred under our proposed BART 
determination for NGS (BART Benchmark).
    Based on our review of all comments we received on the Proposed 
Rule and Supplemental Proposal, EPA is taking action to finalize 
requirements consistent with the TWG Agreement, as a ``better than 
BART'' Alternative (TWG Alternative) put forth in our Supplemental 
Proposal. EPA is also taking final action to determine that a BART 
Benchmark, consistent with our proposed BART determination, is 
appropriate for establishing the 2009-2044 NOX Cap under the 
TWG Alternative. EPA is not finalizing our proposed BART determination 
for NGS in the regulatory requirements of this Final Rule, and EPA is 
not taking action to finalize Alternative 1, the ``better than BART'' 
Alternative we put forth in our Proposed Rule.
    This Final Action is expected to result in over an 80 percent 
reduction in NOX emissions and to significantly reduce the 
impact of NGS on visibility at 11 mandatory Class I Federal areas. 
EPA's action to finalize requirements consistent with the TWG Agreement 
as a ``better than BART'' alternative for NGS will ensure that lifetime 
NOX emissions from NGS do not exceed the BART Benchmark.

VI. Administrative Requirements

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action will finalize a source-specific FIP for a single 
generating source. This type of action is exempt from review under 
Executive Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 
3821, January 21, 2011).

B. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 
Under the Paperwork Reduction Act, a ``collection of information'' is 
defined as a requirement for ``answers to . . . identical reporting or 
recordkeeping requirements imposed on ten or more persons. . . .'' 44 
U.S.C. 3502(3)(A). Because the final FIP applies to a single facility, 
Navajo Generating Station, the Paperwork Reduction Act does not apply. 
See 5 CFR 1320(c).
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of

[[Page 46548]]

information; search data sources; complete and review the collection of 
information; and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations in 40 CFR are listed in 40 CFR Part 9.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to prepare a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements under the Administrative 
Procedure Act or any other statute unless the agency certifies that the 
rule will not have a significant economic impact on a substantial 
number of small entities. Small entities include small businesses, 
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of today's rule on small 
entities, small entity is defined as: (1) A small business as defined 
by the Small Business Administration's (SBA) regulations at 13 CFR 
121.201; (2) a small governmental jurisdiction that is a government of 
a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for-profit enterprise which is independently owned and operated 
and is not dominant in its field.
    After considering the economic impacts of this action on small 
entities, I certify that this final action will not have a significant 
economic impact on a substantial number of small entities. The Navajo 
Generating Station is not a small entity and the FIP for Navajo 
Generating Station being finalized today does not impose any compliance 
requirements on small entities. See Mid-Tex Electric Cooperative, Inc. 
v. FERC, 773 F.2d 327 (D.C. Cir. 1985). We recognize that several 
tribes located in Arizona have expressed concerns regarding potential 
indirect effects of this Final Rule; however, these indirect effects 
are not direct compliance costs or requirements on small entities.

D. Unfunded Mandates Reform Act (UMRA)

    This rule will impose an enforceable duty on the private sector 
owners of Navajo Generating Station. However, this rule does not 
contain a Federal mandate that may result in expenditures of $100 
million (in 1996 dollars) or more for State, local, and tribal 
governments, in the aggregate, or the private sector in any one year. 
EPA's estimate for the total annual cost to install and operate SCR on 
all three units at NGS if it had been required to comply with BART does 
not exceed $100 million (in 1996 dollars) in any one year. Because we 
are finalizing requirements consistent with Appendix B to the TWG 
Agreement, which provides more flexibility than EPA's proposed BART 
determination and would, at most, require installation and operation of 
SCR on two units, rather than three units at NGS, EPA expects the total 
annual cost of implementing the TWG Alternative to also not exceed $100 
million (in 1996 dollars). Thus, this rule is not subject to the 
requirements of sections 202 or 205 of UMRA. This action is also not 
subject to the requirements of section 203 of UMRA because it contains 
no regulatory requirements that might significantly or uniquely affect 
small governments. This rule will not impose direct compliance costs on 
the Navajo Nation, and will not preempt Navajo law. This final action 
will reduce the emissions of NOX from a single source, the 
Navajo Generating Station.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or in the distribution of power 
and responsibilities among the various levels of government, as 
specified in Executive Order 13132. This final action requires emission 
reductions of NOX at a specific stationary source located in 
Indian country. Thus, Executive Order 13132 does not apply to this 
action.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Subject to the Executive Order 13175 (65 FR 67249, November 9, 
2000) EPA may not issue a regulation that has tribal implications, that 
imposes substantial direct compliance costs, and that is not required 
by statute, unless the Federal government provides the funds necessary 
to pay the direct compliance costs incurred by tribal governments, or 
EPA consults with tribal officials early in the process of developing 
the proposed regulation and develops a tribal summary impact statement. 
EO 13175 defines ``policies that have tribal implications'' to refer to 
regulations or other actions that have substantial direct effects on 
one or more Indian tribes.
    EPA has concluded that this Final Action will have tribal 
implications based on the direct relationship between NGS and the 
Navajo Nation. In addition, EPA anticipates that the following direct 
and indirect effects may result from the TWG Alternative and 
Reclamation's ownership interest in NGS: Decreased revenues to the Hopi 
Tribe and the Navajo Nation associated with the closure of one unit or 
curtailment of electricity generation in 2019; and increased water 
costs to tribes associated with the installation of controls to meet an 
emission limit of 0.07 lb/MMBtu in 2030. However, it will neither pre-
empt Tribal law nor impose substantial direct compliance costs on 
tribal governments (no tribal government is an owner or participant in 
NGS and therefore no tribal government will be required to pay direct 
costs of compliance). We note that the Navajo Nation has the option to 
purchase up to a 170 MW share of NGS in 2019. EPA understands that the 
Navajo Nation has not yet made its decision and therefore, currently, 
no tribal government is a Participant in NGS.
    The owners of NGS, together with the Navajo Nation, the Gila River 
Indian Community, and several other stakeholders, submitted the TWG 
Agreement to EPA that would provide compliance flexibility to the 
owners and result in greater reasonable progress than BART toward the 
national visibility goal. This TWG Alternative involves closure or 
curtailment of production on one unit of NGS and installation of add-on 
pollution controls to the remaining two units. EPA issued a 
Supplemental Proposal proposing to find that the TWG Alternative met 
the requirements of the CAA and RHR. Today, EPA is finalizing 
requirements consistent with the TWG Agreement. Because the TWG 
Alternative involves the closure or curtailment of production on one 
unit and an associated decline in the amount of coal mined and 
combusted, to the extent that taxes or royalties paid to the Hopi Tribe 
and the Navajo Nation by the operators of Navajo Generating Station and 
the Kayenta Mine, are tied to the amount of coal that is mined or the 
amount of electricity that is generated at NGS, the revenues to the 
Hopi Tribe and Navajo Nation may be expected to decline. In addition, 
under the TWG Alternative, when the installation of add-on pollution 
controls occurs in 2030, EPA expects the CAWCD variable OM&R water rate 
to increase, affecting tribes with allocations of CAP water.
    EPA consulted with tribal officials early in the process of 
developing this regulation to permit them to have meaningful and timely 
input into its development. EPA first put forth an

[[Page 46549]]

ANPR on August 28, 2009 to accept comment on preliminary information 
provided by FCPP and NGS and to begin the consultation process with the 
Federal Land Managers and affected tribes.
    EPA received numerous comments on the ANPR from tribes and tribal 
organizations, including the Navajo Nation, Hopi Tribe, Gila River 
Indian Community, Ak-Chin Indian Community, Tohono O'odham Nation, 
Pascua Yaqui Tribe, Fort McDowell Yavapai Nation, Yavapai-Apache 
Nation, and the Inter Tribal Council of Arizona. Comments from the 
Navajo Nation on NGS and from the Hopi Tribe focused on the significant 
contribution of coal-related royalties, taxes, and employment at NGS 
and the Kayenta Mine to the economies of the Navajo Nation and the Hopi 
Tribe. Comments from the Gila River Indian Community, the Tohono 
O'odham Nation, and other tribes located in Arizona focused on the 
importance of continued operation of NGS as a source of power to CAP, 
in order for the federal government to meet obligations under existing 
water settlement agreements. The importance to tribes of continued 
operation of NGS and affordable water costs cannot be overemphasized.
    Given the extent of federal and tribal interests in NGS and the 
federal government's trust responsibility to Indian tribes, on January 
4, 2013, EPA, DOI, and DOE signed a joint federal agency statement 
committing to collaborate on several short- and long-term goals, 
including analyzing and pursuing strategies for providing clean, 
affordable and reliable power, affordable and sustainable water, and 
sustainable economic development to key stakeholders who currently 
depend on NGS.\160\ The partner agencies have already begun to work 
together with stakeholders to identify and undertake actions that 
support implementation of BART, including seeking funding to cover 
expenses for pollution control or other necessary upgrades for the 
federal portion of NGS. The agencies have also begun work to jointly 
support a phase 2 report to analyze a full range of clean energy 
options for NGS. Finally, the agencies intend to work with stakeholders 
to develop a roadmap for achieving long-term, innovative clean energy 
solutions for NGS.
---------------------------------------------------------------------------

    \160\ See Joint Federal Agency Statement Regarding Navajo 
Generating Station, dated January 4, 2013, in the docket for this 
proposed rulemaking.
---------------------------------------------------------------------------

    In our February 5, 2013 Proposed Rule, EPA exercised discretion to 
include in our analysis of Factor 2 (Energy and Non-Air Quality 
Impacts), an examination of the viability of continued operation of NGS 
if new NOX controls are required, to address the concern 
expressed by numerous tribes that a BART determination requiring SCR 
would force NGS to close. Our analysis showed that although SCR would 
increase the cost of electricity generation at NGS, installing and 
operating SCR at NGS would still be less costly than replacing NGS with 
power purchased from elsewhere in the West.\161\ However, we also 
recognized that the timing of regulatory compliance is an important 
consideration given potential ownership changes and other requirements 
related to the extension of the NGS lease and other rights-of-way 
agreements. As part of our Factor 2 analysis, we also estimated 
potential water rate increases to tribes.\162\ As discussed in our 
proposed rule, EPA considers the potential economic impacts to tribes 
to argue for flexibility in the compliance timeframe for NGS.
---------------------------------------------------------------------------

    \161\ See Factor 2 analysis, 78 FR 8281-8284 (February 5, 2013).
    \162\ Id.
---------------------------------------------------------------------------

    In addition to our proposed BART determination for NGS, EPA also 
proposed a framework for evaluating alternatives to BART that provide 
options for flexibility in achieving emission reductions at NGS. EPA 
proposed an alternative to BART consistent with our proposed framework 
and invited stakeholders to submit other alternatives to BART that 
reduce NOX emissions at NGS while providing long-term, 
sustainable benefits for tribes.\163\ We noted that the extended 
timeframe for compliance would not, in itself, avoid or mitigate 
increases in water rates for tribes located in Arizona; however, it 
would provide time for the collaborating federal agencies to explore 
options to avoid or minimize potential impacts to tribes, including 
seeking funding to cover the expenses for the federal portion of 
pollution control at NGS.\164\
---------------------------------------------------------------------------

    \163\ Id. at 8291.
    \164\ Id. at 8289.
---------------------------------------------------------------------------

    Following our Proposed Rule, the TWG, which included the Navajo 
Nation, the Gila River Indian Community, and the Interior, together 
with four additional groups, submitted their agreement (TWG Agreement) 
that contained an additional BART alternative for consideration 
(Appendix B to the TWG Agreement). Although EPA was not part of the 
TWG, we note that the TWG Agreement included seven elements, including 
elements directly or indirectly related to tribes, i.e., commitments by 
Interior to mitigate potential impacts from EPA's final BART rule to 
Affected Tribes and a commitment by SRP to make funds available for a 
Local Benefit Fund for community improvement projects within 100 miles 
of NGS or the Kayenta Mine.\165\
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    \165\ As described in our Supplemental Proposal (78 FR 62512, 
October 22, 2013), the seven elements of the TWG Agreement were (1) 
a description of a ``Reasonable Progress Alternative to BART'' 
(Appendix B to the TWG Agreement); (2) a study of options by 
Reclamation for replacing the federal share of energy being 
generated from NGS with low-emitting energy; (3) commitments by 
Interior to reduce or offset emissions of carbon dioxide 
(CO2) by three percent per year and facilitate the 
development of clean energy resources; (4) commitments by Interior 
to mitigate potential impacts from EPA's final BART rule to Affected 
Tribes; (5) a commitment by Interior to carry out the Phase 2 Study 
by the National Renewable Energy Laboratory (NREL) for the purposes 
of studying options for the future of NGS; (6) a commitment by SRP 
to make funds available for a Local Benefit Fund for community 
improvement projects within 100 miles of NGS or the Kayenta Mine; 
and (7) a summary of obligations of the Parties to the Agreement and 
miscellaneous legal provisions.
---------------------------------------------------------------------------

    EPA has met with tribes on numerous occasions to discuss the 
significance of NGS to tribal economies and tribal water interests in 
Arizona.\166\ Consultations with tribes included potential economic 
impacts associated with a BART determination for NGS, as well as 
potential impacts from EPA's Mercury and Air Toxics Standards (MATS) 
rulemaking.
---------------------------------------------------------------------------

    \166\ See document titled ``Updated Timeline of All Tribal 
Consultations on NGS for Final Rule.docx'' in the docket for this 
rulemaking.
---------------------------------------------------------------------------

    In recognition of the unusual complexity of regulating NGS, 
representatives from EPA, including the Assistant Administrator and the 
Deputy Assistant Administrator for the Office of Air and Radiation and 
the Regional Administrator for Region 9, visited NGS and affected 
communities in the area. EPA officials have also met with additional 
stakeholders, at various locations, including EPA offices in San 
Francisco, California and Washington, DC, and offices of individual 
tribal governing councils and the Inter Tribal Council of Arizona.
    Following the publication of our proposed rule on February 5, 2013, 
EPA engaged in 17 consultation meetings with tribes prior to the 
January 2014 close of the public comment period.\167\ Of these 
meetings, at least two were held as group consultation sessions where 
all tribes in Arizona were invited to participate and were provided the 
opportunity to request individual consultation meetings as well.\168\ 
EPA received comment letters on our proposal and Supplemental Proposal

[[Page 46550]]

from the Navajo Nation, the Gila River Indian Community, the Tohono 
O'odham Nation, the Ak-Chin Indian Community, the Tonto Apache Tribe, 
the San Carlos Apache Tribe, and the Kaibab Band of Paiute 
Indians.\169\ At the request of two tribes for additional time beyond 
January 6, 2014 to submit comments, EPA exercised our discretion to 
accept comments from tribal governments after the close of the comment 
period. The White Mountain Apache Tribe submitted comments on February 
5, 2014.\170\ In addition, in response to their request to EPA for 
information related to NGS, we provided responsive documents to the 
Hopi Tribe on January 7, 2014.\171\ As shown in additional 
correspondence, the Hopi Tribe requested additional time to submit 
comments, and EPA continued to exercise our discretion to accept late 
comments from the Hopi Tribe.\172\ Our separate response to comments 
document contains a summary of all substantive comments and EPA's 
responses to those comments.
---------------------------------------------------------------------------

    \167\ See document titled ``Updated Timeline of all Tribal 
Consultation on NGS--for Final Rule.pdf'' in the docket for the 
rule.
    \168\ Id.
    \169\ See comment numbers 0340, 0317, 0387, 0402, 0419, and 0421 
in the docket for the rule.
    \170\ See comment number 0440 in the docket for the rule.
    \171\ See document titled ``2014--0107 EPA Letter to Chairman 
Honanie with Enclosure 1.pdf'' in the docket for this rule.
    \172\ See document titled ``2014--0131 Letter from Chairman 
Honanie.pdf'' and document titled ``2014--0206 EPA Response to 
Chairman Honanie--Hopi Tribe.pdf'' in the docket for this rule.
---------------------------------------------------------------------------

    Several tribes expressed concern that the Technical Work Group 
included only two tribes, the Navajo Nation and the Gila River Indian 
Community, and excluded numerous other tribes that also have a 
significant economic interest in NGS. Several tribes also asserted that 
the Proposed Rule and Supplemental Proposal have disproportionate 
impacts on tribes with CAP water settlements and urged EPA to develop 
an alternative regulation that does not place an additional burden on 
Indian tribes. Another tribe requested that a portion of the funds 
identified in the TWG Agreement be designated to their tribe.
    EPA recognizes that many tribes did not participate in the 
development of the TWG Agreement. EPA was not involved in the formation 
of the Technical Work Group or any of the negotiations between the 
members of the TWG in developing the TWG Agreement. In addition, our 
evaluation of the TWG Agreement was for the sole purpose of determining 
whether the TWG Alternative (Appendix B to the TWG Agreement) meets our 
framework for a ``better than BART'' Alternative. Therefore, although 
EPA agrees that many tribes have economic interests in NGS and CAP, EPA 
did not have a role in the TWG Agreement and does not have any role in 
the distribution of funds described in the TWG Agreement.
    EPA recognizes that our final action will have tribal implications. 
Because we are taking action to finalize requirements consistent with 
the TWG Agreement, EPA anticipates that increases in CAP water costs as 
a result of the installation of new air pollution controls at NGS would 
not occur until 2030. In addition, as stated elsewhere, EPA has 
committed to collaborating with other federal agencies to explore 
options to avoid or minimize potential impacts to tribes, including 
seeking funding to cover the expenses for the federal portion of 
pollution control at NGS.
    In summary, EPA has taken numerous steps, as described in the 
preceding paragraphs, to evaluate the potential impacts on Tribes and 
to identify and provide the flexibility for others to develop 
alternative approaches that would meet the requirements of the CAA and 
the RHR while being as sensitive as possible to concerns raised by 
Tribes. Through the Joint Federal Agency Statement on NGS, the federal 
government has recognized its obligations through its trust 
responsibility and through its specific historical and ongoing 
involvement with NGS and water rights settlements with Tribes. That 
agreement reflects our commitment to ongoing engagement with affected 
Tribes and to the pursuit of a long-term solution for electricity 
generation that is protective of the economic interests of Tribes and 
public health and the environment.
    Based on numerous consultation meetings between high-level 
officials from EPA and elected tribal leaders, beginning in 2009 and 
extending into 2013, and our development of flexible options for BART 
Alternatives in response to comments from tribes, EPA considers our 
consultation on NGS to be consistent with EO 13175 and EPA's policy to 
engage in early and meaningful consultation with tribes.\173\
---------------------------------------------------------------------------

    \173\ EPA's policy on Consultation and Coordination with Indian 
Tribes is posted on the following Web site: http://www.epa.gov/tribal/consultation/consult-policy.htm.
---------------------------------------------------------------------------

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    Executive Order 13045: Protection of Children from Environmental 
Health Risks and Safety Risks (62 FR 19885, April 23, 1997), applies to 
any rule that: (1) Is determined to be economically significant as 
defined under Executive Order 12866, and (2) concerns an environmental 
health or safety risk that EPA has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, the Agency must evaluate the environmental health or 
safety effects of the planned rule on children, and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency.
    This rule is not subject to Executive Order 13045 because it 
requires emissions reductions of NOX from a single 
stationary source. Because this action only applies to a single source 
and is not a rule of general applicability, it is not economically 
significant as defined under Executive Order 12866, and does not have a 
disproportionate effect on children. However, to the extent that the 
rule will reduce emissions of NOX, which contributes to 
ozone formation, the rule will have a beneficial effect on children's 
health by reducing air pollution that causes or exacerbates childhood 
asthma and other respiratory issues.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 (66 FR 28355 
(May 22, 2001)), because it is not a significant regulatory action 
under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Public Law 104-113, 12 (10) (15 U.S.C. 272 note) 
directs EPA to use voluntary consensus standards (VCS) in its 
regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. VCS are technical standards 
(e.g., materials specifications, test methods, sampling procedures and 
business practices) that are developed or adopted by the VCS bodies. 
The NTTAA directs EPA to provide Congress, through annual reports to 
OMB, with explanations when the Agency decides not to use available and 
applicable VCS.
    Consistent with the NTTAA, the Agency conducted a search to 
identify potentially applicable VCS. For the measurements listed below, 
there are a number of VCS that appear to have possible use in lieu of 
the EPA test methods and performance specifications (40 CFR Part 60, 
Appendices A and B) noted next to the measurement

[[Page 46551]]

requirements. It would not be practical to specify these standards in 
the current rulemaking due to a lack of sufficient data on equivalency 
and validation and because some are still under development. However, 
EPA's Office of Air Quality Planning and Standards is in the process of 
reviewing all available VCS for incorporation by reference into the 
test methods and performance specifications of 40 CFR Part 60, 
Appendices A and B. Any VCS so incorporated in a specified test method 
or performance specification would then be available for use in 
determining the emissions from this facility. This will be an ongoing 
process designed to incorporate suitable VCS as they become available.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629, February 16, 1994), establishes 
federal executive policy on environmental justice. Its main provision 
directs federal agencies, to the greatest extent practicable and 
permitted by law, to make environmental justice part of their mission 
by identifying and addressing, as appropriate, disproportionately high 
and adverse human health or environmental effects of their programs, 
policies, and activities on minority populations and low-income 
populations in the United States.
    EPA has determined that this final rule will not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations because it increases the 
level of environmental protection for all affected populations without 
having any disproportionately high and adverse human health or 
environmental effects on any population, including any minority or low-
income population.
    EPA recognizes that numerous commenters have stated that this 
rulemaking has environmental justice implications because NGS, which is 
among the largest coal-fired power plants in the country, is located on 
the Navajo Nation. Commenters have also expressed concern that the 
documents associated with this rule are too technical for community 
members to understand. Some commenters have also argued that EPA should 
apply the same standard to NGS as other coal-burning power plants 
(e.g., Four Corners Power Plant), and that the extended compliance 
timeframe for NGS is an environmental justice issue.
    Fair treatment and meaningful involvement are critical components 
of environmental justice and EPA takes fair treatment and meaningful 
involvement seriously. We provided numerous opportunities for tribal 
governments, environmental and tribal non-governmental organizations, 
and other interested stakeholders to provide input in the development 
of our Proposed Rule, Supplemental Proposal, and Final Rule for NGS.
    As discussed in more detail in the RTC, EPA began our public 
involvement process for a BART determination for NGS in 2009, when we 
published an Advanced Notice of Proposed Rulemaking (ANPR). During 2009 
through 2012, EPA met with various stakeholders, including tribal 
governments and Navajo environmental groups to discuss NGS and hear 
concerns related to a BART determination for this facility.\174\ During 
the 11-month comment period for our Proposed Rule, EPA continued to 
meet with stakeholders to discuss our proposed BART determination for 
NGS and our framework for ``better than BART'' alternatives.\175\
---------------------------------------------------------------------------

    \174\ See, for example, document number 0232 in the ANPR docket 
at EPA-R09-OAR-2009-0598, and document numbers 0008 and 0009 in the 
docket for this rule at EPA-R09-OAR-2013-0009.
    \175\ See, for example, document number 0150, 0152, 0166, 0173, 
0302, and 0303 in the docket for this rule.
---------------------------------------------------------------------------

    On July 26, 2013, the TWG submitted the TWG Agreement to EPA for 
consideration. EPA posted the TWG Agreement to our docket on the same 
day to provide the public an opportunity to review it.\176\ On 
September 25, 2013, EPA posted a Supplemental Proposal, along with 
supporting documents, to the docket to allow for early review by 
interested parties.\177\ The Supplemental Proposal was published in the 
Federal Register on October 22, 2013. The comment period for the 
Supplemental Proposal closed on the same day as the BART proposal, on 
January 6, 2014. The Supplemental Proposal also included notice of five 
open house and public hearing events EPA scheduled throughout Arizona 
in November 2013. The open houses allowed members of the public an 
opportunity to talk with representatives from EPA and ask questions. 
EPA held events at the LeChee Chapter House, located on the Navajo 
Nation, as well as in Page, Arizona, and provided oral interpretation 
services between English and Din[eacute] (the Navajo language). EPA 
also held an event at the Hopi Day School, located in Kykotsmovi, the 
seat of the Hopi tribal government.\178\ Finally, we also held events 
in Phoenix and in Tucson, Arizona, to allow stakeholders in central and 
southern Arizona, representing CAP water interests and several tribes 
receiving CAP water, the opportunity to provide comment and talk with 
representatives from EPA.
---------------------------------------------------------------------------

    \176\ See document number 0122 in the docket for this 
rulemaking.
    \177\ See document numbers 0182, 0183, and 0184 in the docket 
for this rulemaking.
    \178\ EPA engaged with the government of the Hopi Tribe to 
search for an oral interpreter between English and the Hopi 
language, but the Hopi Tribe was unable to locate anyone to provide 
those services.
---------------------------------------------------------------------------

    EPA understands that the TSD and Federal Register notices include 
technical information that may be difficult to understand. EPA provided 
Fact Sheets and handouts, written in plain language, at the open house 
and public hearing events.\179\ EPA representatives were also present 
at the events to discuss and explain our Proposals.
---------------------------------------------------------------------------

    \179\ See document 0219 in the docket for this rulemaking.
---------------------------------------------------------------------------

    EPA recognizes that some commenters may view the timeframe for 
compliance under EPA's framework for BART Alternatives as an 
environmental justice issue. We note that the Navajo Nation and other 
Tribes expressed concern with the potential economic impacts of this 
rulemaking. The flexibility we provided has allowed for a balance 
between these considerations.
    We further note that the LNB/SOFA credit, an important component of 
the timeframe under our ``better than BART'' framework, was based on 
real, actual emission reductions beginning in 2009 that were voluntary 
and not required by any rule or regulation. We also note that the TWG 
Alternative, which calls for closure of one unit in 2019 (or equivalent 
curtailment), will result not only in reductions of NOX, but 
also reductions of several other pollutants, including SO2, 
PM, CO2, and hazardous air pollutants. Although the 
compliance date of emission limit for two units (achievable with the 
installation of SCR) under the TWG Alternative is in 2030, over 2009 to 
2044, the TWG Alternative will result in greater NOX 
reductions than would have been achieved under BART, will result in 
step-wise reductions of NOX and additional pollutants that 
affect visibility or human health, and will provide an enforceable 
mechanism to ensure that NGS ceases conventional coal-fired electricity 
generation at NGS by the end of 2044. All of these measures will 
increase the level of environmental protection for communities affected 
by NGS.

[[Page 46552]]

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. Section 804 exempts from section 801 the following types 
of rules (1) rules of particular applicability; (2) rules relating to 
agency management or personnel; and (3) rules of agency organization, 
procedure, or practice that do not substantially affect the rights or 
obligations of non-agency parties. 5 U.S.C. 804(3). EPA is not required 
to submit a rule report regarding today's action under section 801 
because this action is a rule of particular applicability. This rule 
finalizes a source-specific FIP for a single generating source.

L. Petitions for Judicial Review

    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by October 7, 2014. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this rule for the purposes of judicial 
review nor does it extend the time within which a petition for judicial 
review may be filed, and shall not postpone the effectiveness of such 
rule or action. This action may not be challenged later in proceedings 
to enforce its requirements. See CAA section 307(b)(2).

List of Subjects in 40 CFR Part 49

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Indians, Intergovernmental relations, Reporting 
and recordkeeping requirements.

    Dated: July 28, 2014.
Gina McCarthy,
Administrator.

    Title 40, chapter I of the Code of Federal Regulations is amended 
as follows:

PART 49--INDIAN COUNTRY: AIR QUALITY PLANNING AND MANAGEMENT

0
1. The authority citation for part 49 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.

0
2. Section 49.5513 is amended by adding paragraph (j) to read as 
follows:

Sec.  49.5513  Federal Implementation Plan Provisions for Navajo 
Generating Station, Navajo Nation.

* * * * *
    (j)(1) Applicability. Regional Haze Best Available Retrofit 
Technology limits for NOX for this plant are in addition to 
the requirements of paragraphs (a) through (i) of this section. The 
provisions of this paragraph (j) are severable, and if any provision of 
this paragraph (j), or the application of any provision of this 
paragraph (j) to any owner/operator or circumstance, is held invalid, 
the application of such provision to other owner/operators and other 
circumstances, and the remainder of this paragraph (j), will not be 
affected thereby. Nothing in this paragraph (j) allows or authorizes 
any Unit to emit NOX at a rate that exceeds its existing 
emission limit of 0.24 lb/MMBtu as established by EPA permit AZ 08-01 
issued on November 20, 2008.
    (2) Definitions. Terms not defined below have the meaning given to 
them in the Clean Air Act or EPA's regulations implementing the Clean 
Air Act and in paragraph (c) of this section. For purposes of this 
paragraph (j):
    (i) 2009-2029 NOX Cap means a limit on emissions from Units 1, 2, 
and 3 of no more than 416,865 tons of NOX.
    (ii) 2009-2044 NOX Cap means a limit on emissions from Units 1, 2, 
and 3 of no more than 494,899 tons of NOX.
    (iii) Boiler operating day means a 24-hour period between 12 
midnight and the following midnight during which any fuel is combusted 
at any time in the steam-generating unit. It is not necessary for fuel 
to be combusted the entire 24-hour period.
    (iv) Coal-fired unit means any of Units 1, 2, or 3 at Navajo 
Generating Station.
    (v) Continuous Emission Monitoring System or CEMS means the 
equipment required by 40 CFR part 75 and this paragraph (j).
    (vi) Departing Participant means either Los Angeles Department of 
Water and Power or Nevada Energy, also known as NV Energy or Nevada 
Power Company.
    (vii) Emission limitation or emission limit means the federal 
emissions limitation required by this paragraph.
    (viii) Existing Participant means the existing owners of NGS: Los 
Angeles Department of Water and Power; Nevada Energy, also known as NV 
Energy or Nevada Power Company; Salt River Project Agricultural 
Improvement and Power District; Arizona Public Service Company; and 
Tucson Electric Company, together with the United States, acting 
through the Bureau of Reclamation.
    (ix) lb means pound(s).
    (x) Low-NOX Burners and Separated Over-Fire Air or LNB/SOFA means 
combustion controls installed on each Unit between 2009 and 2011.
    (xi) Navajo Nation means the Navajo Nation, a federally recognized 
Indian Tribe.
    (xii) NGS or Navajo Generating Station means the steam electric 
generating station located on the Navajo Reservation near Page, 
Arizona, consisting of Units 1, 2, and 3, each 750 MW (nameplate 
rating), the switchyard facilities, and all facilities and structures 
used or related thereto.
    (xiii) NOX means nitrogen oxides expressed as nitrogen dioxide 
(NO2).
    (xiv) Owner/operator means any person(s) who own(s) or who 
operate(s), control(s), or supervise(s) one more of the Units of the 
Navajo Generating Station.
    (xv) MMBtu means million British thermal unit(s).
    (xvi) Operating hour means any hour that fossil fuel is fired in 
the unit.
    (xvii) Unit means any of Units 1, 2, or 3 at Navajo Generating 
Station.
    (xviii) Valid data means CEMs data that is not out of control as 
defined in 40 CFR part 75.
    (3) ``Better than BART'' alternative for NOX. Total cumulative 
NOX emissions from Units 1, 2, and 3, from January 1, 2009 
to December 31, 2044, may not exceed the 2009-2044 NOX Cap. 
The owner/operator must implement the applicable operating scenario, 
under paragraph (j)(3)(i) of this section, to ensure NOX 
emission reductions sufficient to maintain total cumulative 
NOX emissions from Units 1, 2, and 3 below the 2009-2044 
NOX Cap.
    (i) Operating scenarios to comply with 2009-2044 NOX 
Cap. The owner/operator must comply with one of the following operating 
scenarios based on the applicability provisions in paragraph (j)(3)(ii) 
of this section.
    (A) Alternative A1. (1) By December 31, 2019, the owner/operator 
must permanently cease operation of one coal-fired Unit; and
    (2) By December 31, 2030, the owner/operator must comply with a 
NOX emission limit of 0.07 lb/MMBtu, based on a rolling 
average of 30 boiler operating days, on each of the two remaining coal-
fired Units.
    (3) The owner/operator must permanently cease operation of Units 1, 
2, and 3 if total cumulative emissions of NOX from Units 1, 
2, and 3, based on annual reports required under paragraph (j)(4)(ii) 
of this section, exceed the 2009-2044 NOX Cap at any time 
prior to December 31, 2044.
    (B) Alternative A2. (1) By December 31, 2019, the owner/operator 
must

[[Page 46553]]

permanently cease operation of one coal-fired Unit; and
    (2) By December 31, 2019, the owner/operator may increase net 
generating capacity of the remaining two coal-fired Units by a combined 
total of no more than 189 MW. The actual increase in net generating 
capacity shall be limited by the sum of 19 MW and the ownership 
interest, in net MW capacity, purchased by the Navajo Nation by 
December 31, 2019. Nothing in paragraph (j) of this section alters any 
regulatory requirements, including those for pre-construction 
permitting, associated with any increase in the net generating capacity 
of the Unit(s).
    (3) By December 31, 2030, the owner/operator must comply with a 
NOX emission limit of 0.07 lb/MMBtu, based on a rolling 
average of 30 boiler operating days, on each of the two remaining coal-
fired Units.
    (4) The owner/operator must permanently cease operation of Units 1, 
2, and 3 if total cumulative emissions of NOX from Units 1, 
2, and 3, based on annual reports required under paragraph (j)(4)(ii) 
of this section, exceed the 2009-2044 NOX Cap at any time 
prior to December 31, 2044.
    (C) Alternative A3. (1) By December 31, 2019, the owner/operator 
must reduce the net generating capacity of NGS by no less than 561 MW. 
The actual reduction in net generating capacity of NGS shall be 
determined by the difference between 731 MW and the ownership interest, 
in net MW capacity and limited to 170 MW, purchased by the Navajo 
Nation by December 31, 2019.
    (2) By December 31, 2030, the owner/operator must comply with a 
NOX emission limit of 0.07 lb/MMBtu, based on a rolling 
average of 30 boiler operating days, on two Units.
    (3) The owner/operator must permanently cease operation of Units 1, 
2, and 3 if total cumulative emissions of NOX from Units 1, 
2, and 3, based on annual reports required under paragraph (j)(4)(ii) 
of this section, exceed the 2009-2044 NOX Cap at any time 
prior to December 31, 2044.
    (D) Alternative B. (1) Total cumulative NOX emissions 
from Units 1, 2, and 3 may not exceed the 2009-2044 NOX Cap 
or the 2009-2029 NOX Cap.
    (2) The owner/operator must cease operation of Units 1, 2, and 3 if 
total cumulative emissions of NOX from Units 1, 2, and 3, 
based on annual reports required under paragraph (j)(4)(ii) of this 
section, exceed the 2009-2029 NOX Cap at any time prior to 
December 31, 2029. The owner/operator may restart operation of Units 1, 
2, and 3 after January 1, 2030, as long as total cumulative emissions 
of NOX from Units 1, 2, and 3, based on annual reports 
required under paragraph (j)(4)(ii) of this section, do not exceed the 
2009-2044 NOX Cap.
    (3) The owner/operator must permanently cease operation of Units 1, 
2, and 3 if total cumulative emissions of NOX from Units 1, 
2, and 3, based on annual reports required under paragraph (j)(4)(ii)), 
exceed the 2009-2044 NOX Cap at any time prior to December 
31, 2044.
    (ii) Applicability of alternatives. (A) Alternative A1 applies if 
by December 31, 2019, one of the following occurs:
    (1) Both of the Departing Participants retire their ownership 
interests in NGS by December 31, 2019, and the Navajo Nation does not 
purchase an ownership interest in NGS; or
    (2) Both of the Departing Participants sell their ownership 
interests in NGS to Existing Participants, and the Navajo Nation does 
not purchase an ownership interest in NGS; or
    (3) One of the Departing Participants retires its ownership 
interest in NGS and the other Departing Participant sells its ownership 
interest in NGS to an Existing Participant, and the Navajo Nation does 
not purchase an ownership interest in NGS.
    (B) Alternative A2 applies if by December 31, 2019, one of the 
following occurs:
    (1) Both of the Departing Participants sell their ownership 
interests in NGS to Existing Participants, the Navajo Nation has 
purchased an ownership interest in NGS, and the owner/operator has 
increased net generating capacity of the two remaining Units by a 
combined total of no more than 189 MW; or
    (2) One of the Departing Participants retires its ownership 
interest in NGS and the other Departing Participant sells its ownership 
interest in NGS to an Existing Participant, the Navajo Nation has 
purchased an ownership interest in NGS, and the owner/operator has 
increased net generating capacity of the two remaining Units by a 
combined total of no more than 189 MW.
    (C) Alternative A3 applies if by December 31, 2019, one of the 
following occurs:
    (1) Both of the Departing Participants sell their ownership 
interests in NGS to Existing Participants, the Navajo Nation has 
purchased an ownership interest in NGS, and the owner/operator has not 
increased net generating capacity of the Units at NGS; or
    (2) One of the Departing Participants retires its ownership 
interest in NGS and the other Departing Participant sells its ownership 
interest in NGS to an Existing Participant, the Navajo Nation has 
purchased an ownership interest in NGS, and the owner/operator has not 
increased net generating capacity of the Units at NGS.
    (D) Alternative B applies if, by December 31, 2019, if one of the 
following occurs:
    (1) Any of the Departing Participants sell their ownership 
interests in NGS to a Party other than the Navajo Nation that is not an 
Existing Participant, or
    (2) Any of the Departing Participants remains as a participant in 
NGS.
    (iii) By December 22, 2044, the owner/operator shall permanently 
cease conventional coal-fired electricity generation by all coal-fired 
Units at NGS.
    (4) Reporting and implementation requirements for BART. (i) No 
later than December 1, 2019, the owner/operator must notify EPA of the 
applicable Alternative for ensuring compliance with the 2009-2044 
NOX Cap.
    (ii) Beginning in 2015, and annually thereafter until the earlier 
of December 22, 2044 or the date on which the owner/operator ceases 
conventional coal-fired electricity generation by all coal-fired Units 
at NGS, the owner/operator must report to EPA, the annual heat input, 
the annual emissions of sulfur dioxide, carbon dioxide, and 
NOX from the previous full calendar year. In addition, the 
owner/operator must also report total cumulative emissions of 
NOX from NGS to assure compliance with the 2009-2044 
NOX Cap and the 2009-2029 NOX Cap (if 
applicable). The owner/operator must make this report available to the 
public, either through a link on its Web site or directly on its Web 
site. The report must be made available within 30 days of the submittal 
deadline associated with the annual emission inventory required by the 
Part 71 Operating Permit for NGS.
    (iii) No later than December 31, 2020, the owner/operator must 
submit an application to revise its existing Part 71 Operating Permit 
to incorporate the requirements and emission limits of the applicable 
Alternative to BART under paragraph (j)(3) of this section. The Part 71 
Operating Permit for NGS must incorporate practically enforceable 
limits for NOX of 0.24 lb/MMBtu, on a 30[hyphen]day rolling 
average basis, for each Unit equipped with LNB/SOFA, and 0.07 lb/MMBtu, 
on a rolling average basis of 30 boiler operating days, for each Unit 
equipped with SCR, as federally enforceable permit conditions.
    (iv) In addition to the requirements of paragraphs (j)(4)(i), (ii) 
and (iii) of this section, if Alternative B applies, the owner/operator 
must submit annual Emission Reduction Plans to the Regional 
Administrator.

[[Page 46554]]

    (A) No later than December 31, 2019 and annually thereafter through 
December 31, 2028, the owner/operator must submit an Emission Reduction 
Plan containing anticipated year-by-year emissions from Units 1, 2, and 
3 covering the period from 2020 to 2029 that will assure that the 
operation of NGS will result in emissions of NOX that do not 
exceed the 2009-2029 NOX Cap. The Emission Reduction Plan 
may contain several potential operating scenarios and must set forth 
the past annual actual emissions and the projected emissions for each 
potential operating scenario. Each potential operating scenario must 
demonstrate compliance with the 2009-2029 NOX Cap. The 
Emission Reduction Plan shall identify emission reduction measures that 
may include, but are not limited to, the installation of advanced 
emission controls, a reduction in generation output, or other operating 
strategies determined by the owner/operator. The owner/operator may 
revise the potential operating scenarios set forth in the Emission 
Reduction Plan, provided the revised plan ensure that NOX 
emissions remain below the 2009-2029 NOX Cap.
    (B) No later than December 31, 2029 and annually thereafter, the 
owner/operator shall submit an Emission Reduction Plan containing year-
by-year emissions covering the period from January 1, 2030 to December 
31, 2044 that will assure that the operation of NGS will result in 
emissions of NOX that do not exceed the 2009-2044 
NOX Cap. The Emission Reduction Plan shall identify emission 
reduction measures that may include, but are not limited to, the 
installation of advanced emission controls, a reduction in generation 
output, or other operating strategies determined by the owner/operator. 
The owner/operator may revise the potential operating scenarios set 
forth in the Emission Reduction Plan, provided the revised plan ensure 
that NOX emissions remain below the 2009-2044 NOX 
Cap.
    (C) The requirement to submit annual Emission Reduction Plans 
beginning no later than December 31, 2019, shall be incorporated into 
the Part 71 Operating Permit for NGS as federally enforceable permit 
conditions.
    (5) Continuous emission monitoring system (CEMS). (i) At all times, 
the owner/operator of each unit must maintain, calibrate, and operate a 
CEMS, in full compliance with the requirements found at 40 CFR part 75, 
to accurately measure NOX, diluent, and stack gas volumetric 
flow rate from each unit. All hourly valid data will be used to 
determine compliance with the emission limitations for NOX 
in paragraph (j)(3) of this section for each unit. If the CEMs data is 
not valid, that CEMs data shall be treated as missing data and not used 
to calculate the emission average. CEMs data does not need to be bias 
adjusted as defined in 40 CFR part 75. Each required CEMS must obtain 
valid data for at least 90 percent of the unit operating hours, on an 
annual basis.
    (ii) The owner/operator of each unit shall comply with the quality 
assurance procedures for CEMS found in 40 CFR part 75. In addition to 
these Part 75 requirements, relative accuracy test audits shall be 
calculated for both the NOX pounds per hour measurement and 
the heat input measurement. The calculation of NOX pounds 
per hour and heat input relative accuracy shall be evaluated each time 
the CEMS undergo relative accuracy testing.
    (6) Compliance determination for NOX emission limits. (i) 
Compliance with the NOX emission limits under paragraphs 
(j)(3)(i) of this section shall be determined on a rolling average 
basis of thirty (30) Boiler Operating Days on a unit by unit basis. 
Compliance shall be calculated in accordance with the following 
procedure: Sum the total pounds of NOX emitted from the Unit 
during the current Boiler Operating Day and the previous twenty-nine 
(29) Boiler Operating Days; sum the total heat input to the Unit in 
MMBtu during the current Boiler Operating Day and the previous twenty-
nine (29) Boiler Operating Days; and divide the total number of pounds 
of NOX by the total heat input in MMBtu during the thirty 
(30) Boiler Operating Days. A new 30 Boiler Operating Day rolling 
average shall be calculated for each new Boiler Operating Day. Each 30 
Boiler Operating Day rolling average shall include all emissions that 
occur during periods within any Boiler Operating Day, including 
emissions from startup, shutdown, and malfunction.
    (ii) If a valid NOX pounds per hour or heat input is not 
available for any hour for a Unit, that heat input and NOX 
pounds per hour shall not be used in the calculation for that 30 boiler 
operating day period.
    (7) Recordkeeping. The owner/operator of each Unit must maintain 
the following records until the earlier of December 22, 2044 or the 
date that conventional coal-fired operation of all units at NGS 
permanently ceases:
    (i) All CEMS data, including the date, place, and time of sampling 
or measurement; parameters sampled or measured; and results as required 
by Part 75 and as necessary to calculate each units pounds of 
NOX and heat input for each hour.
    (ii) Each Boiler Operating Day rolling average emission rate for 
NOX calculated in accordance with paragraph (j)(6)(i) of 
this section.
    (iii) Each unit's 30 Boiler Operating Day pounds of NOX 
and heat input.
    (iv) Records of quality assurance and quality control activities 
for emissions measuring systems including, but not limited to, any 
records required by 40 CFR part 75.
    (v) Records of the relative accuracy calculation of the 
NOX lb/hr measurement and hourly heat input.
    (vi) Any other records required by 40 CFR part 75.
    (8) Reporting. All reports and notifications under this paragraph 
(j) must be submitted to the Director, Navajo Environmental Protection 
Agency, P.O. Box 339, Window Rock, Arizona 86515, and to the Director 
of Enforcement Division, U.S. EPA Region IX, at 75 Hawthorne Street, 
San Francisco, CA 94105.
    (i) The owner/operator must notify EPA within two weeks after 
completion of installation of NOX control technology on any 
of the units subject to this section.
    (ii) Within 30 days after the first applicable compliance date in 
paragraph (j)(3) of this section and within 30 days of every second 
calendar quarter thereafter (i.e., semi-annually), the owner/operator 
must submit a report that lists for each calendar day, calculated in 
accordance with paragraph (j)(6) of this section, total lb of 
NOX and heat input (as used to calculate compliance per 
paragraph (j)(6) of this section, for each unit's last 30 boiler 
operating days. The owner/operator must include the results of the last 
relative accuracy test audit and the calculated relative accuracy for 
lb/hr NOX and heat input performed 45 days prior to the end 
of that reporting period. The end of the year report shall also include 
the percent valid data for each NOX, diluent, and flow 
monitor used in the calculations of compliance with paragraph (j)(6) of 
this section.
    (9) Enforcement. Notwithstanding any other provision in this 
implementation plan, any credible evidence or information relevant as 
to whether the unit would have been in compliance with applicable 
requirements if the appropriate performance or compliance test had been 
performed, can be used to establish whether or not the owner or 
operator has violated or is in violation of any standard or applicable 
emission limit in the plan.
    (10) Equipment operations. At all times, including periods of 
startup, shutdown, and malfunction, the owner/operator shall, to the 
extent practicable,

[[Page 46555]]

maintain and operate the unit including associated air pollution 
control equipment in a manner consistent with good air pollution 
control practices for minimizing emissions. Determination of whether 
acceptable operating and maintenance procedures are being used will be 
based on information available to the Regional Administrator, or their 
designee, which may include, but is not limited to, monitoring results, 
review of operating and maintenance procedures, and inspection of the 
unit.
    (11) Affirmative defense. The affirmative defense provisions of 
paragraphs (c)(2) and (i) of this section do not apply to this 
paragraph (j).
[FR Doc. 2014-18228 Filed 8-7-14; 8:45 am]
BILLING CODE 6560-50-P
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