Document ID: EPA-R09-OAR-2018-0590-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Revisions to the Source-Specific Federal Implementation Plan for Navajo Generating Station, Navajo Nation
Posted Date: 2018-11-09T05:00Z

[Federal Register Volume 83, Number 218 (Friday, November 9, 2018)]
[Proposed Rules]
[Pages 55994-56002]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-24482]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 49 and 52

[EPA-R09-OAR-2018-0590; FRL-9986-21-Region 9]

Revisions to the Source-Specific Federal Implementation Plan for 
Navajo Generating Station, Navajo Nation

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing limited 
revisions to the source-specific federal implementation plan (FIP) that 
regulates emissions from the Navajo Generating Station (NGS), a coal-
fired power plant located on the reservation lands of the Navajo Nation 
near Page, Arizona. We are proposing to lower the emission limitation 
for particulate matter (PM) to conform to the most stringent emission 
limitation currently applicable to NGS under another EPA regulation, 
and to replace the opacity limitation and annual PM source testing 
requirement with a requirement to demonstrate compliance with the lower 
PM emission limitation using a continuous emission monitoring system 
for particulate matter.

DATES: Any comments on this proposal must arrive by December 10, 2018.

ADDRESSES: Submit your comments, identified by Docket ID number EPA-
R09-OAR-2018-0590, at http://www.regulations.gov, or via email to 
[email protected]. For comments submitted at Regulations.gov, follow 
the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, the EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. The EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the Web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the 
EPA's full public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Anita Lee, EPA Region IX, (415) 972-
3958, [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us'' and 
``our'' refer to the EPA.

Table of Contents

I. Background
    A. Action
    B. Facility
    C. Attainment Status
    D. The EPA's Authority To Promulgate a FIP in Indian Country
    E. Historical Overview of NGS FIP Actions
II. Basis for Proposed Action
III. Summary of FIP Provisions
    A. Proposed FIP Revisions
    B. Justification for Proposed FIP Revisions
IV. Solicitation of Comments
V. Environmental Justice Considerations
VI. Statutory and Executive Order Reviews

I. Background

A. Action

    In this action, the EPA is proposing limited revisions to the FIP 
for NGS that we promulgated on October 3, 1991 (``1991 FIP''), March 5, 
2010 (``2010 FIP''), and August 8, 2014 (``2014 FIP'').\1\ The 
provisions of the 1991 action are codified in the Code of Federal 
Regulations (CFR) at 40 CFR 52.145(d), and the 2010 and 2014 
regulations are codified at 40 CFR 49.5513. We refer collectively to 
the provisions from the 1991, 2010, and 2014 actions as the ``FIP'' or 
the ``NGS FIP.'' The NGS FIP includes federally enforceable emission 
limitations for PM, opacity, sulfur dioxide (SO2), and 
oxides of nitrogen (NOX).
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    \1\ See 56 FR 50172 (October 3, 1991), 75 FR 10174 (March 5, 
2010), and 79 FR 46552 (August 8, 2014).
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    Generally, the EPA is proposing to move provisions from the 1991 
FIP to a different section of the CFR and to

[[Page 55995]]

update certain provisions in the 1991 FIP to be consistent with recent 
national rulemakings. Specifically, we are proposing to move the 1991 
FIP provisions from 40 CFR 52.145(d) to 40 CFR 49.5513. If finalized, 
the effect of our action will be to move requirements for NGS from 
subpart D of part 52, which contains the state implementation plan 
(SIP) provisions for Arizona, to subpart L of part 49, which contains 
source-specific FIP requirements for NGS, to consolidate all of the 
applicable requirements for NGS in one section of the CFR. We are 
proposing to update the definition of ``boiler operating day'' in the 
1991 FIP to be consistent with the definition in the 2014 FIP.\2\
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    \2\ See 40 CFR 52.145(d)(1) and 40 CFR 49.5513(j)(2)(iii).
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    In addition, we are proposing to revise the PM compliance 
demonstration from annual source testing to the use of PM continuous 
emissions monitoring systems (PM CEMS), which were installed and 
calibrated on each of the three units at the facility in 2016. We are 
also proposing to lower the PM emission limitation in the 2010 FIP from 
0.060 pounds per million British thermal units (lb/MMBtu) to 0.030 lb/
MMBtu. This lower emission limitation already applies to NGS pursuant 
to the EPA's Mercury and Air Toxics Standard (MATS) Rule.\3\ Because 
the operator of NGS will be using PM CEMS to demonstrate compliance 
with the 0.030 lb/MMBtu emission limitation for PM, the EPA is also 
proposing to remove the opacity emission limitation and associated 
continuous opacity monitoring system (COMS) requirements from the NGS 
FIP. The opacity limitation and COMS have generally functioned as 
surrogates for ensuring compliance with PM emission limitations. This 
proposed revision is consistent with the provisions related to PM CEMS 
and opacity in the New Source Performance Standard for Electric Utility 
Steam Generating Units (``NSPS for EGUs'') and the Acid Rain Program 
requirements at 40 CFR 75.14(e), which generally provide that any owner 
or operator that elects to install, calibrate, maintain, and operate a 
PM CEMS for demonstrating compliance with a sufficiently stringent PM 
emission limitation (i.e., 0.030 lb/MMBtu or lower) need not meet the 
opacity limit and monitoring requirements.\4\
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    \3\ See 77 FR 9303 (February 16, 2012) and 81 FR 20172 (April 6, 
2016) (Final Technical Corrections).
    \4\ See NSPS for EGUs at 40 CFR 60.42Da and the Acid Rain 
Program requirements at 40 CFR part 75. Subpart Da to part 60 is the 
``Standard of Performance for Electric Utility Steam Generating 
Units'' and applies to units that are capable of combusting more 
than 73 MW heat input of fossil fuel and for which construction, 
modification, or reconstruction commenced after September 18, 1978. 
The units at NGS were constructed prior to 1978 and are not subject 
to part 60 subpart Da. The NGS units are subject to the Acid Rain 
Program requirements of CAA Title IV, but are eligible for an 
exemption from the requirement for COMS in CAA section 412(a), 
pursuant to 40 CFR 75.14.
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    Finally, we are proposing to clarify requirements that have already 
been satisfied (e.g., a one-time requirement that has been met to 
submit a description of dust suppression methods to the Regional 
Administrator) and update the addresses to which the owner or operator 
must submit reports.

B. Facility

    NGS is a coal-fired power plant located on the reservation lands of 
the Navajo Nation, just east of Page, Arizona, and approximately 135 
miles north of Flagstaff. NGS is co-owned by several entities and 
operated by Salt River Project (SRP).\5\ The facility currently 
operates three units, each with a capacity of 750 megawatts (MW) net 
generation, providing a total capacity of 2250 MW. Operations at the 
facility produce air pollutant emissions, including emissions of 
SO2, NOX, and PM. Existing pollution control 
equipment at NGS includes wet flue gas desulfurization units for 
SO2 and PM removal, electrostatic precipitators for PM 
removal, and low-NOX burners with separated over-fire air to 
reduce NOX formation during the combustion process. In the 
future, the owner or operator of NGS will be taking steps to reduce 
emissions of NOX further, pursuant to the requirements of 
the 2014 FIP.
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    \5\ Currently, the participants in NGS are the United States 
Bureau of Reclamation, SRP, Arizona Public Service Company, Tucson 
Electric Company, and NV Energy. SRP, which serves as the facility 
operator, recently increased its ownership share after it purchased 
the shares previously owned by the Los Angeles Department of Water 
and Power.
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C. Attainment Status

    The area around NGS is designated attainment, unclassifiable/
attainment or unclassifiable for all criteria pollutants under the 
Act.\6\
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    \6\ See 40 CFR 81.303.
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D. The EPA's Authority To Promulgate a FIP in Indian Country

    When the CAA was amended in 1990, Congress included a new 
provision, section 301(d), granting the EPA authority to treat tribes 
in the same manner as states where appropriate.\7\ In 1998, the EPA 
promulgated regulations known as the Tribal Authority Rule (TAR).\8\ 
The EPA's promulgation of the TAR clarified, among other things, that 
state air quality regulations generally do not, under the CAA, apply to 
facilities located anywhere within the exterior boundaries of Indian 
reservations.\9\ Prior to the addition of section 301(d) and the 
promulgation of the TAR, some states had mistakenly included emission 
limitations in their SIPs that they may have believed could apply under 
the CAA to private facilities operating on adjacent Indian 
reservations.
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    \7\ See 40 U.S.C. 7601(d).
    \8\ See 40 CFR parts 9, 35, 49, 50, and 81. See also 63 FR 7254 
(February 12, 1998).
    \9\ See 63 FR 7254 at 7258 (noting that unless a state has 
explicitly demonstrated its authority and has been expressly 
approved by the EPA to implement CAA programs in Indian country, the 
EPA is the appropriate entity to implement CAA programs prior to 
tribal primacy), Arizona Public Service Company v. EPA., 211 F.3d 
1280 (D.C. Cir. 2000), cert. denied sub nom, Michigan v. EPA., 532 
U.S. 970 (2001) (upholding the TAR); see also Alaska v. Native 
Village of Venetie Tribal Government, 533 U.S. 520, 526 n.1 (1998) 
(primary jurisdiction over Indian country generally lies with 
federal government and tribes, not with states).
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    In the preambles to the proposed and final 1998 TAR, the EPA 
generally discussed the legal basis in the CAA that authorizes the EPA 
to regulate sources of air pollution in Indian country.\10\ The EPA 
concluded that the CAA authorizes the EPA to protect air quality 
throughout Indian country.\11\ The TAR, therefore, provides that the 
EPA ``[s]hall promulgate without unreasonable delay such federal 
implementation plan provisions as are necessary or appropriate to 
protect air quality, consistent with the provisions of sections 
[301](a) and 301(d)(4), if a tribe does not submit a tribal 
implementation plan meeting the completeness criteria of 40 CFR part 
51, Appendix V, or does not receive EPA approval of a submitted tribal 
implementation plan.'' \12\
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    \10\ See 59 FR 43956 (August 25, 1994); 63 FR 7253 (February 12, 
1998).
    \11\ See 63 FR 7253 at 7262 (February 12, 1998); 59 FR 43956 at 
43960-43961 (August 25, 1994) (citing, among other things, to CAA 
sections 101(b)(1), 301(a), and 301(d)).
    \12\ See 63 FR at 7273 (codified at 40 CFR 49.11(a)). In the 
preamble to the final TAR, the EPA explained that it was 
inappropriate to treat tribes in the same manner as states with 
respect to section 110(c) of the Act, which directs the EPA to 
promulgate a FIP within 2 years after the EPA finds a state has 
failed to submit a complete state plan or within 2 years after the 
EPA disapproval of a state plan. Although the EPA is not required to 
promulgate a FIP within the 2-year period for tribes, the EPA 
promulgated 40 CFR 49.11(a) to clarify that the EPA will continue to 
be subject to the basic requirement to issue any necessary or 
appropriate FIP provisions for affected tribal areas within some 
reasonable time. See 63 FR at 7264-65.
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E. Historical Overview of NGS FIP Actions

    On December 2, 1980, EPA issued regulations addressing visibility

[[Page 55996]]

impairment that is traceable or ``reasonably attributable'' to a single 
source or small group of sources.\13\ These regulations required a 
number of states to submit SIPs no later than September 2, 1981. Most 
states, including Arizona, failed to submit SIPs as called for by the 
regulations. Accordingly, in 1987, the EPA issued visibility FIPs 
consisting of general plan requirements and long-term strategies for 29 
states including Arizona.\14\
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    \13\ 45 FR 80084 (December 2, 1980), codified at 40 CFR 51.300-
51.307.
    \14\ See 52 FR 45132 (November 24, 1987).
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    In 1989, based on a report submitted by the National Park Service, 
the EPA proposed to find that a portion of the visibility impairment in 
Grand Canyon National Park was reasonably attributable to NGS.\15\ 
Under the 1991 FIP, NGS was required to phase-in compliance with the 
SO2 emission limit, by installing scrubbers in 1997, 1998, 
and 1999.\16\ In establishing the SO2 emission limit for NGS 
in the final 1991 FIP, the EPA determined that the FIP would provide 
for greater reasonable progress toward the national visibility goal 
than implementation of Best Available Retrofit Technology (BART).\17\
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    \15\ 56 FR 50172 (October 3, 1991), codified at 40 CFR 52.145.
    \16\ 40 CFR 52.145(d)(7).
    \17\ 56 FR 50172 (October 3, 1991).
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    On September 8, 1999, the EPA proposed a source-specific FIP for 
NGS.\18\ The 1999 proposed FIP stated: ``Although the facility has been 
historically regulated by Arizona since its construction, the state 
lacks jurisdiction over the facility or its owners or operations for 
CAA compliance or enforcement purposes.'' The EPA intended for the 
proposed action in 1999 to ``federalize'' the emission limitations that 
Arizona had erroneously included in its SIP.\19\ The EPA received 
comments on the proposed FIP but did not finalize the proposal.
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    \18\ See 64 FR 48725 (September 8, 1999).
    \19\ 64 FR 48725 at 48727.
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    In 2006, the EPA published a new proposed rule to promulgate 
federally enforceable numerical emission limitations for PM and 
SO2 and took action to finalize it in 2010.\20\ The 2010 FIP 
also established an opacity limit and a requirement for specific 
control measures to limit dust emissions. In the 2010 FIP, the EPA 
determined that the emission limitations for PM and SO2 were 
more stringent than, or at least as stringent as, the emission 
limitations that had historically applied at NGS pursuant to an 
operating permit issued by Arizona. Therefore, the EPA concluded that 
air quality in this area would be positively impacted by the 2010 
FIP.\21\
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    \20\ 75 FR 10179 (March 5, 2010) codified at 40 CFR 49.24(a) 
through (i) and redesignated to 40 CFR 49.5513(a) through (i). See 
76 FR 23879 (April 29, 2011).
    \21\ 75 FR 10174 (March 5, 2010).
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    On August 8, 2014, the EPA promulgated a final rule that 
established limits for NOX emissions from NGS under BART 
provisions of the Regional Haze Rule.\22\ We finalized an alternative 
to BART based on agreed-upon recommendations developed by a group of 
diverse stakeholders. The 2014 FIP 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 to 2044 cap is met.
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    \22\ 79 FR 46514 (August 8, 2014).
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II. Basis for Proposed Action

    In this proposed FIP revision, the EPA is exercising its 
discretionary authority under sections 301(a) and 301(d)(4) of the CAA 
and 40 CFR 49.11(a). The EPA is proposing that it is necessary or 
appropriate to revise the FIP for NGS to be more consistent with the 
MATS Rule and the NSPS for EGUs. In particular, we are proposing to 
require the use of PM CEMS to demonstrate compliance with a lower PM 
emission limitation and remove the opacity limitation and COMS 
monitoring requirement, which has served as a surrogate for a 
compliance demonstration for the PM emission limitation. As explained 
in the preamble to the 2010 FIP establishing the opacity limitation and 
COMS requirement, water droplets, which are present in the NGS stacks 
because of the SO2 scrubbers, can cause inaccurate excess 
emission readings from the COMS.\23\ Therefore, the PM CEMS would 
provide a better continuous demonstration of compliance with the PM 
emission limitation than an opacity limit and COMS.
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    \23\ See 75 FR 10175. We also explained that, ``NGS will 
continue to have a requirement to operate COMs on each stack since 
the COMs do operate properly during start-up and at other times when 
the SO2 scrubbers are bypassed for maintenance purposes . 
. . Therefore, in the final rule excess opacity due to uncombined 
water droplets in the stack does not constitute an exceedance, but 
it will be reported on the quarterly excess emissions reports.'' 75 
FR 10177. See also, 40 CFR 49.5113(f)(4).
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    For the reasons set forth above, we are proposing to find that 
limited revisions to the FIP for NGS are necessary or appropriate to 
further protect air quality on the Navajo Nation.

III. Summary of FIP Provisions

A. Proposed FIP Revisions

    The EPA is proposing the following limited revisions to the FIP for 
NGS at 40 CFR 52.145(d) and 40 CFR 49.5513. We have included two 
documents in the docket for this proposed rulemaking that show the 
original text of 40 CFR 52.145(d) and 40 CFR 49.5513 and the EPA's 
proposed revisions to those provisions.\24\
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    \24\ See documents titled ``2018 NGS part 49 FIP RLSO.docx'' and 
``2018 part 52 FIP RLSO.docx'' in the docket for this rulemaking.
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1. Revisions to 40 CFR 52.145(d)
    The EPA is proposing to move the 1991 FIP promulgated at 40 CFR 
52.145(d) to 40 CFR 49.5513(k) to consolidate the NGS FIP requirements 
in a single section of the CFR. We are also proposing to revise 40 CFR 
52.145(d) by changing internal citations referring to paragraph (d) to 
refer instead to paragraph (k). For clarity, in this action we continue 
to refer to the 1991 FIP as designated in 40 CFR 52.145(d).
    In addition, we are proposing to revise the definition of boiler 
operating day in paragraph 52.145(d)(1) to be consistent with its 
definition in the 2014 FIP.
2. Revisions to 40 CFR 49.5513(b)
    Under paragraph (b) of 40 CFR 49.5513, we are proposing to clarify 
that the applicable compliance date for this section is April 5, 2010, 
which was the original effective date for this section, unless 
otherwise specified within specific provisions in 40 CFR 49.5513.
3. Revisions to 40 CFR 49.5513(d)
    In 40 CFR 49.5513(d)(2), we are proposing to revise the emission 
limitation for PM from 0.060 lb/MMBtu to 0.030 lb/MMBtu, add a 
compliance date for this revised limit, and remove specifications 
related to PM testing. In 40 CFR 49.5513(d)(3), we are proposing to 
remove the compliance date for submitting to the EPA a dust suppression 
plan and to clarify the status of this plan, which the owner or 
operator submitted on June 4, 2010 and revised on February 2, 2015.\25\ 
The final revision we are proposing to 40 CFR 49.5513(d) is to remove 
the opacity limit and exclusions for water vapor in paragraph (4).
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    \25\ See Part 71 Federal Operating Permit Draft Statement Of 
Basis Navajo Generating Station Permit No. NN-OP-15-06 (September 
2015), p. 15.
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4. Revisions to 40 CFR 49.5513(e)
    In 40 CFR 49.5513(e)(1), we are proposing to delete the requirement 
to

[[Page 55997]]

operate COMS. In 40 CFR 49.5513(e)(2), we are proposing to replace the 
existing specifications related to annual PM testing with a requirement 
to demonstrate compliance with the PM emission limit in 40 CFR 
49.5513(d)(2) using PM CEMS in accordance with 40 CFR part 63 subpart 
UUUUU and add a compliance date for this requirement. Under 40 CFR 
49.5513(e)(4), we are proposing to remove the provision related to 
COMS. Under 40 CFR 49.5513(e)(8), we are proposing to correct an 
outdated reference.
5. Revisions to 40 CFR 49.5513(f)
    The EPA is proposing revisions to the reporting and recordkeeping 
requirements to provide additional clarity that all reports and 
notifications required in 40 CFR 49.5513(f), (f)(2), and (f)(4), should 
be reported to the Navajo Nation Environmental Protection Agency 
(NNEPA) and the EPA. We are also revising 40 CFR 49.5513(f) to update 
addresses for reporting to the EPA. In addition, in 40 CFR 
49.5513(f)(4), consistent with the proposed removal of the opacity 
emission limitation and COMS requirement in 40 CFR 49.5513(d) and (e), 
we are proposing to replace a requirement to submit excess opacity 
reports as recorded by COMS with a requirement to submit excess 
emission reports for PM as recorded by CEMS, and to remove additional 
provisions related to the COMS.
6. Revisions to 40 CFR 49.5513(j)
    Under 40 CFR 49.5513(j)(8), we are proposing to remove addresses 
for the NNEPA and the EPA that are already provided in 40 CFR 
49.5513(f) and to require that all reports and notifications under 40 
CFR 49.5513(j) be submitted to the NNEPA and the EPA in accordance with 
40 CFR 49.5513(f).

B. Justification for Proposed FIP Revisions

1. Revisions to 40 CFR 52.145(d)
    We are proposing to move the 1991 FIP from 40 CFR 52.145(d) to 40 
CFR 49.5513(k). The 1991 FIP was originally codified in 40 CFR part 52 
subpart D, which contains the SIP provisions for the state of Arizona. 
The provisions at 52.145 relate to visibility protection and paragraph 
(d) pertains to the control of SO2 emissions from NGS based 
on the effects of those emissions on visibility at Grand Canyon 
National Park. Because the EPA has subsequently promulgated FIP 
requirements for NGS in 40 CFR part 49 subpart L, for regulatory 
clarity, we are proposing to move the SO2 requirements from 
the 1991 FIP to the same part of the CFR as the implementation plans in 
Indian country, including the FIP requirements for NGS promulgated in 
2010 and 2014. This move will not relax any existing FIP requirements 
for NGS and will have no effect on air quality in the area surrounding 
NGS.
    Throughout 40 CFR 52.145(d), the provisions include internal 
citations referring to specific subparagraphs in paragraph (d). 
Consistent with our proposal to move the provisions from the 1991 FIP 
to 40 CFR 49.5513(k), we are also proposing to revise the internal 
citations that currently refer to paragraph (d) (i.e., 40 CFR 
52.145(d)) to refer instead to paragraph (k) (i.e., 40 CFR 49.5513(k)). 
This proposed revision will not relax any existing FIP requirements for 
NGS and will have no effect on air quality in the area surrounding NGS.
    We are also proposing to revise a definition of boiler operating 
day in 40 CFR 52.145(d)(1). The term is currently defined as a 24-hour 
calendar day during which coal is combusted in that unit for the entire 
24-hours. We are proposing to revise the definition to mean a 24-hour 
period between 12 midnight and the following midnight during which any 
fuel is combusted at any time, such that it is not necessary for fuel 
to be combusted the entire 24-hour period. This revised definition, if 
finalized, would be identical to the definition of boiler operating day 
promulgated in the 2014 FIP and would be consistent with the recent 
changes to the definition promulgated by the EPA elsewhere (e.g., the 
NSPS for EGUs).
2. Revisions to 40 CFR 49.5513(b)
    Under paragraph (b) of 40 CFR 49.5513, we are proposing to add a 
statement to the compliance dates specifying that compliance with the 
requirements of the section is required by April 5, 2010, which was the 
original effective date for this section, unless otherwise specified 
within specific provisions in 40 CFR 49.5513. Because the FIP 
provisions for NGS promulgated in 1991, 2010, and 2014 all have 
different compliance dates, we are proposing to revise this provision 
for regulatory clarity. The compliance date for the FIP provisions for 
NGS promulgated in 2010 would remain April 5, 2010, while the deadlines 
for the 1991 and 2014 FIPs would remain as specified in paragraphs 40 
CFR 52.145(d)(6) and 49.5513(j) respectively. The compliance dates for 
the revised PM limit and PM CEMS requirements would be specified in 
paragraphs 40 CFR 49.5513(d)(2) and (e)(2), as explained below. This 
proposed revision would not relax any existing FIP requirements for NGS 
and would have no effect on air quality in the area surrounding NGS.
3. Revisions to 40 CFR 49.5513(d)
    In 40 CFR 49.5513(d)(2), we are proposing to revise the PM emission 
limitation from 0.060 lb/MMBtu to 0.030 lb/MMBtu for consistency with 
the numerical PM emission limitation in the MATS Rule. The current 
applicable emission limitation for PM in the 2010 FIP is higher than 
the PM emission limitation in the MATS Rule. Revising the PM emission 
limitation in 40 CFR 49.5513(d)(2) to 0.030 lb/MMBtu will make the PM 
emission limitation in the FIP conform to the applicable, more 
stringent emission limitation in the MATS Rule. The EPA anticipates 
this will not result in any substantive change in the applicable 
requirements or the method of PM control for this facility. We propose 
to require compliance with this limitation in the FIP by the effective 
date of the final FIP. In 40 CFR 49.5513(d)(2), we are also proposing 
to delete the current provisions related to PM emissions testing. The 
requirements for demonstrating compliance with the PM emission 
limitation are instead addressed in 40 CFR 49.5513(e). In 40 CFR 
49.5513(d)(3), we are proposing to clarify the requirement for 
submitting to the EPA a dust suppression plan.
    In 40 CFR 49.5513, we are proposing to remove paragraph (d)(4), 
which contains provisions related to the opacity limit. In 2016, SRP 
installed and calibrated PM CEMS on each unit at NGS. We are proposing 
to remove the opacity limit from the NGS FIP because in 40 CFR 
49.5513(e)(2), we are proposing to add a new requirement to operate the 
PM CEMS on each unit to demonstrate compliance with the PM emission 
limitation of 0.030 lb/MMBtu. This provision is consistent with the 
NSPS for EGUs at 40 CFR 60.42Da(b)(1) and the Acid Rain Program 
requirements at 40 CFR 75.14(e), which generally provide that any owner 
or operator that elects to install, calibrate, maintain, and operate a 
PM CEMS for demonstrating compliance with a sufficiently stringent PM 
emission limitation (i.e., 0.030 lb/MMBtu or lower) need not meet the 
opacity limit and monitoring requirements.\26\ The PM

[[Page 55998]]

CEMS is a monitoring system that provides a continuous assessment of 
compliance with a PM emission limitation. Generally, opacity limits and 
COMS have been used as a surrogate to ensure compliance with a PM 
emission standard that would otherwise be subject only to periodic 
source testing.\27\ NGS is not subject to the NSPS for EGUs at 40 CFR 
60.42Da. However, we are proposing to follow the same rationale from 
Subpart Da to remove the opacity limit and COMS requirement because we 
are concurrently proposing to revise the NGS FIP to require the 
installation, calibration, operation, and maintenance of PM CEMS to 
demonstrate compliance with the lower proposed PM emission limitation 
of 0.030 lb/MMBtu. As explained in the preamble to our 2010 FIP, water 
droplets, which are present in the NGS stacks because of the 
SO2 scrubbers, can cause inaccurate excess emission readings 
on the COMS.\28\ Because the PM CEMS provides a better continuous 
demonstration of compliance with the revised and more stringent PM 
emission limitation than an opacity limit and COMS, this proposed 
revision would not relax any existing requirements in the NGS FIP with 
respect to PM emissions and would not adversely affect air quality in 
the surrounding area.
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    \26\ See NSPS for EGUs at 40 CFR 60.42Da and the Acid Rain 
Program requirements at 40 CFR part 70. Subpart Da to part 60 is the 
``Standard of Performance for Electric Utility Steam Generating 
Units'' and applies to units that are capable of combusting more 
than 73 MW heat input of fossil fuel and for which construction, 
modification, or reconstruction commenced after September 18, 1978. 
The units at NGS were constructed prior to 1978 and are not subject 
to part 60 subpart Da.
    \27\ See, e.g., discussion of opacity in the 2007 FIP for the 
Four Corners Power Plant, 72 FR 25698 at 25701 (May 7, 2007), 
stating that opacity limits are generally applied to ensure a unit 
is meeting its PM limit.
    \28\ See 75 FR 10175. We also explained that, ``NGS will 
continue to have a requirement to operate COMs on each stack since 
the COMs do operate properly during start-up and at other times when 
the SO2 scrubbers are bypassed for maintenance purposes . 
. . Therefore, in the final rule excess opacity due to uncombined 
water droplets in the stack does not constitute an exceedance, but 
it will be reported on the quarterly excess emissions reports.'' 75 
FR 10177. See also, 40 CFR 49.5113(f)(4).
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4. Revisions to 40 CFR 49.5513(e)
    In 40 CFR 49.5513(e)(1) and (e)(4), we are proposing changes to 
remove testing and monitoring requirements for opacity, consistent with 
our proposed removal of the opacity limit in 40 CFR 49.5513(d)(4). 
Because we are proposing to remove the opacity limit, the requirements 
in 40 CFR 49.5513(e)(1) to operate COMS and in (e)(4) to maintain two 
sets of opacity filters for the COMS are no longer necessary. In 
paragraph (e)(2), we are proposing to replace the existing 
specifications related to annual PM testing with a requirement to 
install, calibrate, maintain, and operate PM CEMS to demonstrate 
compliance with the 0.030 lb/MMBtu emission limit in accordance with 
the specifications in the MATS Rule by the effective date of the final 
FIP. The use of PM CEMS is a continuous measurement and is a better 
method for ensuring compliance with the revised and more stringent PM 
emission limit than annual source testing for the existing less 
stringent PM emission limit combined with an opacity limit and COMS. 
Therefore, these combined revisions would not relax existing 
requirements with respect to PM emissions or result in adverse effects 
on air quality in the surrounding area.
    Under 40 CFR 49.5513(e)(8), we are proposing to correct an outdated 
reference to ``Section 49.24(d)(3),'' which has been recodified as 40 
CFR 49.5513(d)(3).\29\
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    \29\ 76 FR 23876 (April 29, 2011).
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5. Revisions to 40 CFR 49.5513(f)
    The EPA is proposing revisions to the reporting and recordkeeping 
requirements to specify that all reports and notifications required in 
40 CFR 49.5513 should be sent to the NNEPA and the Regional 
Administrator of the Region IX office of the EPA. Because 40 CFR 
49.5513(f)(2) repeats addresses and other reporting details already 
provided in paragraph (f), we are also proposing to delete the 
redundant provisions in paragraph (f)(2). These proposed administrative 
changes would not relax any requirements or have any effect on air 
quality in the area surrounding NGS.
    In addition, consistent with the proposed removal of the COMS 
requirement in paragraph (e), we are also proposing to remove the 
reporting requirements related to the COMS in paragraph (f)(4). The use 
of PM CEMS is a continuous measurement and is a better method for 
ensuring compliance with the revised and more stringent PM emission 
limit than annual source testing for the existing less stringent PM 
emission limit combined with an opacity limit and COMS. Therefore, 
these combined revisions would not relax existing requirements with 
respect to PM emissions or result in adverse effects on air quality in 
the surrounding area.
6. Revisions to 40 CFR 49.5513(j)
    In 40 CFR 49.5513(j)(8), we are proposing to remove addresses for 
the NNEPA and the EPA that are already provided in 40 CFR 49.5513(f) 
and to require that all reports and notifications under paragraph (j) 
be submitted to the NNEPA and the EPA in accordance with 40 CFR 
49.5513(f). This proposed revision removes redundant information and 
requires reporting for 40 CFR 49.55153(j) to be consistent with the 
reporting requirements in 40 CFR 49.5513(f). Therefore, these proposed 
revisions would not adversely affect air quality in the surrounding 
area. These proposed changes to 40 CFR 49.5513(j)(10) do not relax any 
requirements or have any effect on air quality in the area surrounding 
NGS.

IV. Solicitation of Comments

    As described above, the EPA is proposing the following revisions: 
(1) Move the 1991 FIP provisions from 40 CFR 52.145(d) to 40 CFR 
49.5513; (2) revise a definition of boiler operating day; (3) clarify 
the compliance dates applicable to the FIP requirements; (4) lower the 
PM emission limitation in the 2010 FIP from 0.060 lb/MMBtu to 0.030 lb/
MMBtu; (5) revise the PM compliance demonstration from annual source 
testing to the use of PM CEMS; (6) and replace the existing opacity 
limit and COMS requirement with a new requirement to demonstrate 
compliance with the PM emission limitation of 0.030 lb/MMBtu using PM 
CEMS.
    The EPA solicits comments on the limited provisions of the NGS FIP 
that we are proposing to revise in this rulemaking. We are not 
accepting comment on any provisions of the NGS FIP that we are not 
proposing to revise. Accordingly, please limit your comments to those 
specific provisions listed above that we are proposing to revise in 
today's action.

V. Environmental Justice Considerations

    The Navajo Generating Station is located on the reservation lands 
of the Navajo Nation, and the EPA recognizes there is significant 
community interest in the emissions and environmental effects of this 
facility. As discussed elsewhere in this document, the proposed 
revisions to the NGS FIP would strengthen the FIP by requiring the use 
of PM CEMS to demonstrate compliance with the lower PM emission 
limitation of 0.030 lb/MMBtu. Because the proposed revisions strengthen 
the NGS FIP, the EPA considers this action to be beneficial for human 
health and the environment, and to have no potential disproportionately 
high and adverse effects on minority, low-income, or indigenous 
populations.

[[Page 55999]]

VI. Statutory and Executive Order Reviews

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

    This action is not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget (OMB) 
for review. This rule applies to only one facility and is therefore not 
a rule of general applicability.

B. Executive Order 13771: Reducing Regulations and Controlling 
Regulatory Costs

    This action is not expected to be an Executive Order 13771 
regulatory action because this action is not significant under 
Executive Order 12866.

C. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 
This rule applies to only one facility. Therefore, its recordkeeping 
and reporting provisions do not constitute a ``collection of 
information'' as defined under 44 U.S.C. 3502(3) and 5 CFR 1320.3(c).

D. Regulatory Flexibility Act (RFA)

    I certify that this proposed action will not have a significant 
economic impact on a substantial number of small entities. This action 
will not impose any requirements on small entities. Firms primarily 
engaged in the generation, transmission, and/or distribution of 
electric energy for sale are small if, including affiliates, the total 
electric output for the preceding fiscal year did not exceed four 
million megawatt-hours. Each of the owners of the facility affected by 
this rule, Salt River Project, the Bureau of Reclamation, Arizona 
Public Service, Tucson Electric Power, and NV Energy, exceed this 
threshold.

E. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments.

F. 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 on the distribution of power 
and responsibilities among the various levels of government.

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

    This action does not have tribal implications, as specified in 
Executive Order 13175. Although this proposed action affects a facility 
located in Indian country, the proposed limited revisions to existing 
provisions in the NGS FIP will not have substantial direct effects on 
any Indian tribes, on the relationship between the federal government 
and Indian tribes, or on the distribution of power and responsibilities 
between the federal government and Indian tribes. Thus, Executive Order 
13175 does not apply to this action. However, we note that we have 
engaged in numerous discussions with the NNEPA during the development 
of this proposed rule and continue to invite consultation on this 
proposed action.

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

    EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern health or safety risks that the EPA has 
reason to believe may disproportionately affect children, per the 
definition of ``covered regulatory action'' in section 2-202 of the 
Executive Order. This action is not subject to Executive Order 13045 
because it does not concern an environmental health risk or safety 
risk.

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

    This action is not subject to Executive Order 13211 because it is 
not a significant regulatory action under Executive Order 12866.

J. National Technology Transfer and Advancement Act

    This action involves technical standards. The technical standards 
in this action are based on the technical standards used in other 
rulemakings promulgated by the EPA. We refer to the discussion of the 
technical standards and voluntary consensus standards in the final rule 
for 40 CFR part 60 subpart Da and 40 CFR part 63 subpart UUUUU at 77 FR 
9304 at 9441 (February 16, 2012).

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

    The EPA believes the human health or environmental risk addressed 
by this action will not have potential disproportionately high and 
adverse human health or environmental effects on minority, low-income 
or indigenous populations. If this rule is finalized as proposed, we 
expect that the limited revisions to the FIP will strengthen 
requirements for PM compliance demonstrations with a lower PM emission 
limitation of 0.030 lb/MMBtu, and will not relax any other existing 
requirements.

List of Subjects

40 CFR Part 49

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

40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Reporting and recordkeeping 
requirements, Visibility.

    Dated: October 26, 2018.
Deborah Jordan,
Acting Regional Administrator, Region IX.

    Chapter I, title 40, of the Code of Federal Regulations is proposed 
to be 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.

Subpart L--Implementation Plans for Tribes--Region IX

0
2. Section 49.5513 is amended by:
0
a. Revising paragraph (b);
0
b. Revising paragraphs (d)(2) and (3);
0
c. Removing paragraph (d)(4);
0
d. Revising paragraphs (e)(1) and (2);
0
e. Removing and reserving paragraph (e)(4);
0
f. Revising paragraph (8);
0
g. Revising paragraphs (f) introductory text and (f)(2) and (4);
0
h. Revising paragraphs (j)(8) introductory text; and
0
i. Adding paragraph (k).
    The revisions and additions read as follows:

[[Page 56000]]

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

* * * * *
    (b) Compliance dates. Compliance with the requirements of this 
section is required no later than April 5, 2010, unless otherwise 
indicated by compliance dates contained in specific provisions.
* * * * *
    (d) * * *
    (2) Particulate matter. By [DATE 30 DAYS AFTER DATE OF PUBLICATION 
OF FINAL RULE IN THE FEDERAL REGISTER], no owner or operator shall 
discharge or cause the discharge of particulate matter into the 
atmosphere in excess of 0.030 lb/MMBtu, on a plant-wide basis.
    (3) Dust. Each owner or operator shall operate and maintain the 
existing dust suppression methods for controlling dust from the coal 
handling and storage facilities, as documented in the dust suppression 
plan submitted on February 2, 2015, or any subsequent revision thereto. 
Each owner or operator shall not emit dust with an opacity greater than 
20% from any crusher, grinding mill, screening operation, belt 
conveyor, truck loading or unloading operation, or railcar unloading 
station, as determined using 40 CFR part 60, Appendix A-4 Method 9.
    (e) Testing and monitoring. (1) On and after the effective date of 
this regulation, the owner or operator shall maintain and operate 
Continuous Emissions Monitoring Systems (CEMS) for NOX and 
SO2 on Units 1, 2, and 3 in accordance with 40 CFR 60.8 and 
60.13(e), (f), and (h), and Appendix B of Part 60. The owner or 
operator shall comply with the quality assurance procedures for CEMS 
found in 40 CFR part 75.
    (2) By [DATE 30 DAYS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE 
FEDERAL REGISTER], the owner or operator shall install, calibrate, 
maintain, and operate particulate matter CEMS on Units 1, 2, and 3 to 
assure continuous compliance with the particulate matter limits in 
paragraph (d)(2) of this section, in accordance with 40 CFR part 63 
subpart UUUUU.
* * * * *
    (8) A certified EPA Reference Method 9 of Appendix A-4 of 40 CFR 
part 60 observer shall conduct a weekly visible emission observation 
for the equipment and activities described under paragraph (d)(3) of 
this section. If visible emissions are present at any of the equipment 
and/or activities, a 6-minute EPA Reference Method 9 observation shall 
be conducted. The name of the observer, date, and time of observation, 
results of the observations, and any corrective actions taken shall be 
noted in a log.
    (f) Reporting and recordkeeping requirements. All requests, 
reports, submittals, notifications and other communications to the EPA, 
Regional Administrator, or Administrator required by this section and 
references therein shall be submitted to the Director, Navajo 
Environmental Protection Agency, P.O. Box 339, Window Rock, Arizona 
86515, (928) 871-7692, (928) 871-7996 (facsimile); and to the Regional 
Administrator, U.S. Environmental Protection Agency, Region IX, to the 
attention of Mail Code: ORA-1, at 75 Hawthorne Street, San Francisco, 
California 94105, (415) 947-8000. For each unit subject to the 
emissions limitations in this section the owner or operator shall:
* * * * *
    (2) For excess emissions, notify the Regional Administrator by 
telephone or in writing within one business day. A complete written 
report of the incident shall be submitted to the Regional Administrator 
within ten (10) working days after the event. This notification shall 
include the following information:
* * * * *
    (4) Submit quarterly excess emissions reports for sulfur dioxide 
and PM as recorded by CEMS together with a CEMS data assessment report 
to the Regional Administrator no later than 30 days after each calendar 
quarter. The owner or operator shall complete the excess emissions 
reports according to the procedures in 40 CFR 60.7(c) and (d) and 
include the Cylinder Gas Audit.
* * * * *
    (j) * * *
    (8) Reporting. All reports and notifications under this paragraph 
(j) must be submitted as required by paragraph (f) of this section to 
the Director, Navajo Nation Environmental Protection Agency and to the 
Regional Administrator.
* * * * *
    (k) This paragraph (k) is applicable to the fossil fuel-fired, 
steam-generating equipment designated as Units 1, 2, and 3 at the 
Navajo Generating Station in the Northern Arizona Intrastate Air 
Quality Control Region 40 CFR 81.270).
    (1) Definitions--(i) Administrator means the Administrator of EPA 
or his/her designee.
    (ii) Affected unit(s) means the steam-generating unit(s) at the 
Navajo Generating Station, all of which are subject to the emission 
limitation in paragraph (k)(2) of this section, that has accumulated at 
least 365 boiler operating days since the passage of the date defined 
in paragraph (k)(6) of this section applicable to it.
    (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) Owner or operator means the owner, participant in, or operator 
of the Navajo Generating Station to which this paragraph (k) is 
applicable.
    (v) Unit-week of maintenance means a period of 7 days during which 
a fossil fuel-fired steam-generating unit is under repair, and no coal 
is combusted in the unit.
    (2) Emission limitation. The following emission limitation shall 
apply at all times. No owner or operator shall discharge or cause the 
discharge of sulfur oxides into the atmosphere in excess of 42 
nanograms per Joule (ng/J) [0.10 pound per million British thermal 
units (lb/MMBtu)] heat input.
    (3) Compliance determination. Until at least one unit qualifies as 
an affected unit, no compliance determination is appropriate. As each 
unit qualifies for treatment as an affected unit, it shall be included 
in the compliance determination. Compliance with this emission limit 
shall be determined daily on a plant-wide rolling annual basis as 
follows:
    (i) For each boiler operating day at each steam generating unit 
subject to the emission limitation in paragraph (k)(2) of this section, 
the owner or operator shall record the unit's hourly SO2 
emissions using the data from the continuous emission monitoring 
systems, required in paragraph (k)(4) of this section, and the daily 
electric energy generated by the unit (in megawatt-hours) as measured 
by the megawatt-hour meter for the unit.
    (ii) Compute the average daily SO2 emission rate in ng/J 
(lb/MMBtu) following the procedures set out in method 19, appendix A, 
40 CFR part 60 in effect on October 3, 1991.
    (iii) For each boiler operating day for each affected unit, 
calculate the product of the daily SO2 emission rate 
(computed according to paragraph (k)(3)(ii) of this section) and the 
daily electric energy generated (recorded according to paragraph 
(k)(3)(i) of this section) for each unit.
    (iv) For each affected unit, identify the previous 365 boiler 
operating days to be used in the compliance determination. Except as 
provided in paragraphs (k)(9) and (k)(10) of this section, all of the 
immediately

[[Page 56001]]

preceding 365 boiler operating days will be used for compliance 
determinations.
    (v) Sum, for all affected units, the products of the daily 
SO2 emission rate-electric energy generated (as calculated 
according to paragraph (k)(3)(iii) of this section) for the boiler 
operating days identified in paragraph (k)(3)(iv) of this section.
    (vi) Sum, for all affected units, the daily electric energy 
generated (recorded according to paragraph (k)(3)(i) of this section) 
for the boiler operating days identified in paragraph (k)(3)(iv) of 
this section.
    (vii) Calculate the weighted plant-wide annual average 
SO2 emission rate by dividing the sum of the products 
determined according to paragraph (k)(3)(v) of this section by the sum 
of the electric energy generated determined according to paragraph 
(k)(3)(vi) of this section.
    (viii) The weighted plant-wide annual average SO2 
emission rate shall be used to determine compliance with the emission 
limitation in paragraph (k)(2) of this section.
    (4) Continuous emission monitoring. The owner or operator shall 
install, maintain, and operate continuous emission monitoring systems 
to determine compliance with the emission limitation in paragraph 
(k)(2) of this section as calculated in paragraph (k)(3) of this 
section. This equipment shall meet the specifications in appendix B of 
40 CFR part 60 in effect on October 3, 1991. The owner or operator 
shall comply with the quality assurance procedures for continuous 
emission monitoring systems found in appendix F of 40 CFR part 60 in 
effect on October 3, 1991.
    (5) Reporting requirements. For each steam generating unit subject 
to the emission limitation in paragraph (k)(2) of this section, the 
owner or operator:
    (i) Shall furnish the Administrator written notification of the 
SO2, oxygen, and carbon dioxide emissions according to the 
procedures found in 40 CFR 60.7 in effect on October 3, 1991;
    (ii) Shall furnish the Administrator written notification of the 
daily electric energy generated in megawatt-hours;
    (iii) Shall maintain records according to the procedures in 40 CFR 
60.7 in effect on October 3, 1991; and
    (iv) Shall notify the Administrator by telephone or in writing 
within one business day of any outage of the control system needed for 
compliance with the emission limitation in paragraph (k)(2) of this 
section and shall submit a follow-up written report within 30 days of 
the repairs stating how the repairs were accomplished and justifying 
the amount of time taken for the repairs.
    (6) Compliance dates. The requirements of this paragraph shall be 
applicable to one unit at the Navajo Generating Station beginning 
November 19, 1997, to two units beginning November 19, 1998, and to all 
units beginning on August 19, 1999.
    (7) Schedule of compliance. The owner or operator shall take the 
following actions by the dates specified, but the interim deadlines 
will be extended if the owner or operators can demonstrate to the 
Administrator that compliance with the deadlines in paragraph (k)(6) of 
this section will not be affected:
    (i) By June 1, 1992, award binding contracts to an architectural 
and engineering firm to design and procure the control system needed 
for compliance with the emission limitation in paragraph (k)(2) of this 
section.
    (ii) By January 1, 1995, initiate on-site construction or 
installation of a control system for the first unit.
    (iii) By May 1, 1997, initiate start-up testing of the control 
system for the first unit.
    (iv) By May 1, 1998, initiate start-up testing of the control 
system for the second unit.
    (v) By February 1, 1999, initiate start-up testing of the control 
system for the third unit.
    (8) Reporting on compliance schedule. Within 30 days after the 
specified date for each deadline in the schedule of compliance in 
paragraph (k)(7) of this section, the owner or operator shall notify 
the Administrator in writing whether the deadline was met. If it was 
not met, the notice shall include an explanation why it was not met and 
the steps which shall be taken to ensure future deadlines will be met.
    (9) Exclusion for equipment failure during initial operation. (i) 
For each unit, in determining compliance for the first year that such 
unit is required to meet the emission limitation in paragraph (k)(2) of 
this section, periods during which one of the following conditions are 
met shall be excluded.
    (A) Equipment or systems do not meet designer's or manufacturer's 
performance expectations.
    (B) Field installation including engineering or construction 
precludes equipment or systems from performing as designed.
    (ii) The periods to be excluded shall be determined by the 
Administrator based on the periodic reports of compliance with the 
emission limitation in paragraph (k)(2) of this section which shall 
identify the times proposed for exclusion and provide the reasons for 
the exclusion, including the reasons for the control system outage. The 
report also shall describe the actions taken to avoid the outage, to 
minimize its duration, and to reduce SO2 emissions at the 
plant to the extent practicable while the control system was not fully 
operational. Whenever the time to be excluded exceeds a cumulative 
total of 30 days for any control system for any affected unit, the 
owner or operators shall submit a report within 15 days addressing the 
history of and prognosis for the performance of the control system.
    (10) Exclusion for catastrophic failure. In addition to the 
exclusion of periods allowed in paragraph (d)(9) of this section, any 
periods of emissions from an affected unit for which the Administrator 
finds that the control equipment or system for such unit is out of 
service because of catastrophic failure of the control system which 
occurred for reasons beyond the control of the owner or operators and 
could not have been prevented by good engineering practices will be 
excluded from the compliance determination. Events which are the 
consequence of lack of appropriate maintenance or of intentional or 
negligent conduct or omissions of the owner or operators or the control 
system design, construction, or operating contractors do not constitute 
catastrophic failure.
    (11) Equipment operation. The owner or operator shall optimally 
operate all equipment or systems needed to comply with the requirements 
of this paragraph consistent with good engineering practices to keep 
emissions at or below the emission limitation in paragraph (k)(2) of 
this section, and following outages of any control equipment or systems 
the control equipment or system will be returned to full operation as 
expeditiously as practicable.
    (12) Maintenance scheduling. On March 16 of each year starting in 
1993, the owner or operator shall prepare and submit to the 
Administrator a long-term maintenance plan for the Navajo Generating 
Station that accommodates the maintenance requirements for the other 
generating facilities on the Navajo Generating Station grid covering 
the period from March 16 to March 15 of the next year and showing at 
least 6 unit-weeks of maintenance for the Navajo Generating Station 
during the November 1 to March 15 period, except as provided in 
paragraph (k)(13) of this section. This plan shall be developed 
consistent with the criteria established by the Western States 
Coordinating Council of the North American Electric Reliability Council 
to ensure an adequate reserve margin of electric

[[Page 56002]]

generating capacity. At the time that a plan is transmitted to the 
Administrator, the owner or operator shall notify the Administrator in 
writing if less than the full scheduled unit-weeks of maintenance were 
conducted for the period covered by the previous plan and shall furnish 
a written report stating how that year qualified for one of the 
exceptions identified in paragraph (k)(13) of this section.
    (13) Exceptions for maintenance scheduling. The owner or operator 
shall conduct a full 6 unit-weeks of maintenance in accordance with the 
plan required in paragraph (k)(12) of this section unless the owner or 
operator can demonstrate to the satisfaction of the Administrator that 
a full 6 unit-weeks of maintenance during the November 1 to March 15 
period should not be required because one of the conditions in 
paragraph (k)(13)(i) through (iv) of this section are met. If the 
Administrator determines that a full 6 unit-weeks of maintenance during 
the November 1 to March 15 period should not be required, the owner or 
operator shall nevertheless conduct that amount of scheduled 
maintenance that is not precluded by the Administrator. Generally, the 
owner or operator shall make best efforts to conduct as much scheduled 
maintenance as practicable during the November 1 to March 15 period.
    (i) There is no need for 6 unit-weeks of scheduled periodic 
maintenance in the year covered by the plan;
    (ii) The reserve margin on any electrical system served by the 
Navajo Generating Station would fall to an inadequate level, as defined 
by the criteria referred to in paragraph (k)(12) of this section;
    (iii) The cost of compliance with this requirement would be 
excessive. The cost of compliance would be excessive when the economic 
savings to the owner or operator of moving maintenance out of the 
November 1 to March 15 period exceeds $50,000 per unit-day of 
maintenance moved; and
    (iv) A major forced outage at a unit occurs outside of the November 
1 to March 15 period, and necessary periodic maintenance occurs during 
the period of forced outage.

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
3. The authority citation for part 52 continues to read as follows:

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

Subpart D--Arizona

Sec.  52.145   [Amended]

0
4. Section 52.145 amended by removing and reserving paragraph (d).

[FR Doc. 2018-24482 Filed 11-8-18; 8:45 am]
BILLING CODE 6560-50-P