[Federal Register Volume 76, Number 38 (Friday, February 25, 2011)]
[Proposed Rules]
[Pages 10530-10544]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-3998]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 49

[EPA-R09-OAR-2010-0683; FRL-9269-4]


Supplemental Proposed Rule of Source Specific Federal 
Implementation Plan for Implementing Best Available Retrofit Technology 
for Four Corners Power Plant: Navajo Nation

AGENCY: Environmental Protection Agency (EPA).

ACTION: Supplemental proposed rule.

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SUMMARY: On October 19, 2010, the Environmental Protection Agency (EPA) 
published a proposal to promulgate a source specific Federal 
Implementation Plan (FIP) requiring the Four Corners Power Plant 
(FCPP), located on the Navajo Nation, to achieve emissions reductions 
required by the Clean Air Act's Best Available Retrofit Technology 
(BART) provision. On November 24, 2010, Arizona Public Service (APS) 
acting on behalf of FCPP's owners submitted a letter to EPA offering an 
alternative proposal to reduce visibility-impairing pollution. In this 
action, EPA is supplementing our October 19, 2010 BART proposal with 
our technical evaluation of APS' alternative proposal. We are proposing 
to find that a different alternative emissions control strategy would 
achieve more progress than EPA's BART proposal towards achieving 
visibility improvements in the surrounding Class I areas.

DATES: Comments on this supplemental proposed rule must be submitted no 
later than May 2, 2011.
    Open houses and public hearings will be held on the following 
dates:

    Shiprock Chapter, Shiprock, New Mexico--March 29, 2011;
    Nenahnezad Chapter, Fruitland, New Mexico--March 30, 2011;
    Farmington, New Mexico--March 30, 2011;
    Durango, Colorado--March 31, 2011.

ADDRESSES: Submit comments, identified by docket number EPA-R09-OAR-
2010-0683, by one of the following methods:

[[Page 10531]]

    Federal eRulemaking Portal: http://www.regulations.gov. Follow the 
on-line instructions.
    E-mail: [email protected].
    Mail or deliver: Anita Lee (Air-3), U.S. Environmental Protection 
Agency Region IX, 75 Hawthorne Street, San Francisco, CA 94105-3901.
    Instructions: All comments will be included in the public docket 
without change and may be made available online at http://www.regulations.gov, including any personal information provided, 
unless the comment includes Confidential Business Information (CBI) or 
other information whose disclosure is restricted by statute. 
Information that you consider CBI or otherwise protected should be 
clearly identified as such and should not be submitted through http://www.regulations.gov or e-mail. http://www.regulations.gov is an 
``anonymous access'' system, and EPA will not know your identity or 
contact information unless you provide it in the body of your comment. 
If you send e-mail directly to EPA, your e-mail address will be 
automatically captured and included as part of the public comment. If 
EPA cannot read your comment due to technical difficulties and cannot 
contact you for clarification, EPA may not be able to consider your 
comment.
    Hearings: EPA is holding public hearings in four locations in the 
Four Corners area to accept oral and written comments on our October 
19, 2010 proposed rulemaking and this supplemental proposed rule. See 
the SUPPLEMENTARY INFORMATION for further information on the hearings.
    The open houses and public hearings will be held at the following 
locations:
    Shiprock Chapter, Shiprock, New Mexico--March 29, 2011, Open House 
from 3 p.m.-6 p.m. and Public Hearing from 7 p.m.-9 p.m. local time, 
Phil L. Thomas Performing Arts Center, Highway 64 West, Shiprock, New 
Mexico, 87420, (505) 368-2490;
    Nenahnezad Chapter, Fruitland, New Mexico--March 30, 2011, combined 
Open House and Public Hearing from 9 a.m.-1 p.m. local time, Nenahnezad 
Chapter House, Multi-Purpose Room, Highway 64 to County Road 6675 to 
end of Navajo Route 365, (505) 960-9702;
    Farmington, New Mexico--March 30, 2011, Open House from 3 p.m.-5 
p.m. and Public Hearing from 6 p.m.-9 p.m. local time, San Juan 
College, Henderson Fine Arts Building Rooms 9006 and 9008, Farmington, 
New Mexico, 97402, (505) 326-3311;
    Durango, Colorado--March 31, 2011, Open House from 3 p.m.-5 p.m. 
and Public Hearing from 6 p.m.-9 p.m. local time, Fort Lewis College, 
Center of Southwest Studies Lyceum Room, 1000 Rim Drive, Durango, 
Colorado, 81301, (970) 247-7456.
    Docket: The index to the docket for this action is available 
electronically at http://www.regulations.gov and in hard copy at EPA 
Region IX, 75 Hawthorne Street, San Francisco, California. While all 
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), and some may not be publicly available in either location 
(e.g., 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.

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 EPA.
    EPA is providing 30 days advance notice of our scheduled hearings 
and opening a comment period on this supplemental proposed rule that 
extends from the publication date of this document until May 2, 2011, 
which is 30 days after our last scheduled hearing, resulting in more 
than 60 days to comment on this supplemental proposed rule. On December 
8, 2010, EPA extended the comment period for our October 19, 2010 BART 
proposal until March 18, 2011. EPA is accepting comment on both 
proposals concurrently. Accordingly, in this action, EPA is also 
extending the public comment period on the October 19, 2010 BART 
proposal until May 2, 2011.
    EPA will not respond to comments during the public hearing. When we 
publish our final action, we will provide written responses to all oral 
and written comments received on our October 19, 2010 proposal and on 
this supplemental proposed rule. To provide opportunities for questions 
and discussion, EPA will hold open houses prior to, or concurrently 
with, the public hearings. During these open houses, EPA staff will be 
available to informally answer questions on our proposed action and 
this supplemental proposed rule. Any comments made to EPA staff during 
the open houses must still be provided formally in writing or orally 
during a public hearing in order to be considered in the record.
    Oral testimony may be limited to 5 minutes for each commenter to 
address the proposal or this supplemental proposed rule. We will not be 
providing equipment for commenters to show overhead slides or make 
computerized slide presentations. Any person may provide written or 
oral comments, in English or Din[eacute], and data pertaining to our 
proposal at the Public Hearing. English-Din[eacute] translation 
services will be provided at both the Open Houses and the Public 
Hearings in Shiprock, Fruitland, and Farmington. English-Dine 
translation services will not be provided at the Durango Open House and 
Public Hearing unless it is requested by March 14, 2011. If you require 
a reasonable accommodation, by March 14, 2011, please contact Anita Lee 
using one of the methods provided in the ADDRESSES section of this 
supplemental proposed rule. Verbatim transcripts, in English, of the 
hearings and written statements will be included in the rulemaking 
docket.
    The public hearings for the three evening events are scheduled to 
close at 9 p.m., but may close later, if necessary, depending on the 
number of speakers wishing to participate.
    If you are unable to attend the public hearings but wish to submit 
written comments on the proposed rule or this supplemental proposed 
rule, you may submit comments, identified by docket number EPA-R09-OAR-
2010-0683, by one of the following methods listed in the ADDRESSES 
section.

Table of Contents

I. Background and Summary
II. Legal Background for Proposing To Approve an Alternative 
Emissions Control Strategy as Achieving Better Progress Towards the 
National Visibility Goal
III. EPA's Technical Analysis of Better Reasonable Progress Towards 
National Visibility Goal
    A. Estimated NOX Emission Reductions
    1. Proposed NOX Emission Limit To Apply on Units 4 
and 5 With Installation of SCR by July 31, 2018
    2. Alternative Emissions Control Strategy Will Result in Greater 
Visibility Improvement than BART
    B. Benefits in Addition to NOX Emissions Reductions
    C. Modeling and Demonstrating Reasonable Progress
    D. Alternative Emissions Control Strategy Has Lower Cost Than 
EPA's Proposed BART Determination
IV. EPA's Supplemental Proposal
V. Administrative Requirements
    A. Executive Order 12866: Regulatory Planning and 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

[[Page 10532]]

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

I. Background and Summary

    EPA's proposed BART determination, which was published on October 
19, 2010, provided a thorough discussion of the legal and factual 
background concerning our proposed BART rulemaking and FCPP. 75 FR 
64221. APS is the sole owner of Units 1-3, a partial owner of Units 4 
and 5, and the operator of FCPP. APS provided an initial response to 
EPA's BART proposal during a meeting on November 9, 2010 and by letter 
dated November 24, 2010. The initial response indicated that APS had 
reached an agreement on November 8, 2010, to purchase the ownership 
interest in Units 4 and 5 from Southern California Edison (SCE). APS 
further announced that upon final authorization of purchasing SCE's 
interest in Units 4 and 5, APS would begin a process to shut down Units 
1-3 that would be completed by the beginning of 2014. In addition, upon 
final authorization, APS would commence work in 2014 to install SCR on 
Units 4 and 5 with a schedule for the SCR to be fully installed and 
operational on both units by 2018. APS proposed a NOX 
emissions limit of 0.11 lb/MMMBtu, to be achieved by the end of 2018. 
APS justified requesting its schedule of 2014 to shut down Units 1-3 
and 2018 to install SCR on Units 4 and 5 based on its need to secure 
several Federal, State, and Tribal authorizations to execute this 
alternative emissions control strategy.
    According to APS' calculations, under their alternative strategy, 
FCPP would, beginning in 2019, emit 2,650 tons per year (tpy) less 
NOX pollution than under EPA's October 19, 2010 BART 
proposal. APS also provided a summary of the significant annual and 
cumulative (through 2037) reductions of NOX, sulfur dioxide 
(SO2), particulate matter (PM), mercury (Hg), water use, and 
carbon dioxide (CO2) that would result from shutting down 
Units 1-3 and operating SCR on Units 4 and 5. EPA's October 19, 2010 
BART proposal did not require reductions of SO2, Hg, or 
CO2 emissions or reductions in water use.
    APS states that revenue associated with operating FCPP comprises 
roughly 35% of the Navajo Nation's general fund. FCPP and the mine 
supplying the coal provide about 1,000 jobs, the majority of which are 
filled by Native American employees. FCPP and the mine also pay 
significant taxes and generate other revenue for the area.
    EPA requested APS to submit the emissions calculations and modeling 
files supporting the conclusions APS set forth in its letter of 
November 24, 2010. APS submitted those emissions calculations and 
modeling files to EPA on November 29, 2010 and December 3, 2010. The 
emission calculation spreadsheet is available in our electronic docket 
(EPA-R09-OAR-2010-0683, document number 0080.1--identified as an xlsx 
file), and the modeling files are available upon request.
    EPA has conducted its own technical analysis of the alternative 
proposal APS put forward on November 24, 2010. Our analysis, as 
described in this supplemental proposed rule, finds that an alternative 
emission control strategy to shut down Units 1-3 by 2014 and operate 
SCR on Units 4 and 5 by July 31, 2018 to achieve a more stringent but 
still feasible NOX emission limit of 0.098 lb/MMBtu will 
result in greater visibility improvement than both EPA's October 19, 
2010 BART proposal and November 24, 2010 APS' alternative proposal.\1\ 
Our analysis differs in some respects from APS regarding the emissions 
benefit and visibility improvement from APS' proposal. However, when 
viewing the combined short term and long term effect of the alternative 
emission control strategy, EPA is proposing to find that shutting down 
Units 1-3 in 2014 and operating SCR on Units 4 and 5 by July 31, 2018 
will result in greater visibility improvement at the surrounding Class 
I areas.
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    \1\ EPA's revisions to APS' proposal is referred to throughout 
this notice as ``the alternative emission control strategy''.
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    FCPP is comprised of five coal-fired units of different sizes and 
ownership. Ownership of Units 4 and 5, the two largest units at FCPP at 
750 MW each, is currently shared between six entities--SCE, APS, Public 
Service Company of New Mexico (PNM), Salt River Project (SRP), El Paso 
Electric Company (EPEC), and Tucson Electric Power (TEP). Table 1 
provides a brief summary of characteristics of the five units.

                                          Table 1--Summary of Units 1-5
----------------------------------------------------------------------------------------------------------------
                                      Unit 1          Unit 2          Unit 3          Unit 4          Unit 5
----------------------------------------------------------------------------------------------------------------
Year Operation Began............            1963            1963            1964            1969            1970
Capacity (MW)...................             170             170             220             750             750
Heat Input Rate (MMBtu/hr)......           1,863           1,863           2,400           7,411           7,411
NOX Baseline emission rate (lb/             0.78            0.64            0.59            0.49            0.49
 MMBtu).........................
PM Baseline emission rate (lb/             0.025           0.029           0.029           0.014           0.010
 MMBtu).........................
                                 -------------------------------------------------------------------------------
Ownership.......................                     APS--100%
                                   SCE--48%, APS--15%, PNM--13%,
                                   SRP--10%, EPEC--7%, TEP--7%.
----------------------------------------------------------------------------------------------------------------

    Table 2 provides a summary of the annual and cumulative emissions 
and water use reductions that will result from APS' proposal. Table 2 
shows the emission reductions as stated by APS in its submittal, 
however, for the cumulative NOX emissions reduced, EPA 
believes with the correction of an evident calculation error on the 
part of APS this value should be 388,416 tons (16,184 tons per year x 
24 years), not 104,958.

[[Page 10533]]



 Table 2--Emission Reductions Achieved by Closing Units 1-3, Reproduced
                From APS' November 24, 2010 Submittal \2\
------------------------------------------------------------------------
                                              Annual        Cumulative
------------------------------------------------------------------------
NOX (tons)..............................          16,184         104,958
SO2 (tons)..............................           2,852          68,448
PM (tons)...............................             678          16,272
Hg (pounds).............................             361           8,664
Water use (acre-feet)...................           6,000         144,000
CO2 (million tons)......................             5.2             125
------------------------------------------------------------------------

     
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    \2\ Annual emissions are based on APS' current emissions 
reported to EPA. Cumulative emissions are based on APS's proposal 
from 2014 to 2037 prior to end of new lease (24 year period).
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II. Legal Background for Proposing To Approve APS' Alternative Emission 
Control Strategy as Achieving Better Progress Towards the National 
Visibility Goal

    Section 169A(b)(2) of the Clean Air Act requires a complete 
implementation plan for visibility improvement to contain such 
emissions limits, schedules of compliance, and other measures that may 
be necessary to make reasonable progress towards the national 
visibility goal. The implementation plan provisions must include, as 
appropriate, BART under CAA section 169A(b)(2)(A) and a long term 
strategy under CAA section 169A(b)(2)(B).
    In 1991, EPA considered a factual situation similar to the 
circumstances at hand. EPA had published a proposed rule requiring the 
owners and operators of Navajo Generating Station (NGS) to install 
emissions controls to reduce SO 2 emissions because those 
emissions from NGS were shown to impair visibility in the Grand Canyon 
National Park. 55 FR 5173 (Feb. 8, 1991). The proposed rulemaking 
included an SO 2 emission limit, based on analysis of 
several different levels of SO 2 reduction, as BART pursuant 
to authority in CAA Section 169A(b)(2)(A). 56 FR 5178. Before EPA 
finalized the rule, the owner and operator of NGS, along with several 
environmental groups, submitted an alternative plan to EPA. The 
alternative plan would provide greater emissions reductions of SO 
2 at a lower cost than EPA's proposed rule. EPA published a 
Supplemental Notice seeking comments on the alternative plan. 56 FR 
38399 (Aug. 13, 1991).
    In the NGS Supplemental Notice, EPA examined its legal authority 
under Section 169A(b)(2). Id. Appendix B. EPA noted that in crafting 
the visibility reasonable progress requirements,

    Congress did not explicitly address, and apparently did not even 
consider, whether there could be greater visibility improvement at a 
lower cost in furtherance of the national goal through an 
implementation plan provision that relied more generally on 
subsection (b)(2), rather than on specific provisions of 
subparagraph (A) and/or subparagraph (B). Where Congress has not 
directly spoken to the precise question at issue, EPA may make a 
reasonable construction of the statute that is appropriate in the 
context of the particular program at issue. Chevron, U.S.A., Inc. v. 
Natural Resources Defense Council, Inc., 467 U.S. 837, 842-45 
(1984).

    Id. at 38403. EPA evaluated the alternative plan and agreed that it 
would provide greater visibility improvement at lower cost than EPA's 
proposed BART rulemaking. EPA's Supplemental Notice stated:

    Based on the staff conclusions regarding the factual 
circumstances of this case, EPA could reasonably find that the 
present alternative, with its higher expected visibility improvement 
and lower expected costs (in comparison to the February 1991 
proposed rule), best fulfills the overarching statutory requirement 
in section 169A(b)(2)(which incorporates the more specific 
provisions of subparagraphs (A) and (B)) that implementation plan 
revisions adopted under subparagraphs 169A make ``reasonable 
progress'' toward the national visibility goal.

    Id.
    EPA finalized the proposed rule for NGS in October 1991. 56 FR 
50172 (Oct. 3, 1991). In the final rule, EPA adopted the rationale from 
the August 1991 Supplemental Notice that EPA had legal authority under 
section 169A(b)(2) to finalize an alternative to BART provided it made 
greater reasonable progress towards the national visibility goal. Id. 
at 50177.
    The Central Arizona Project (CAP) petitioned the Ninth Circuit 
Court of Appeals to review EPA's final rule. The Ninth Circuit issued 
an opinion on March 25, 1993, upholding EPA's legal authority to 
finalize an alternative to BART as making reasonable progress where 
that alternative resulted in greater visibility improvement at a lower 
cost. Central Arizona Water Conservation District v. United States 
Environmental Protection Agency, 990 F.2d 1531 (9th Cir. Mar. 25, 
1993). The Court noted that ``[u]nder the unique circumstances of this 
case, however, EPA chose not to adopt the emission control limits 
indicated by BART analysis, but instead to adopt an emission 
limitations standard that would produce greater visibility improvement 
at a lower cost.'' Id. at 1543. The Court then held:

    Since the Act itself is ambiguous on the specific issue, we 
apply the Supreme Court's deferential standard from Chevron and hold 
that the agency's reliance on the ``reasonable progress'' provisions 
is a ``permissible construction of the statute,'' 467 U.S. at 843, 
104 S.Ct. at 2782, since ``reasonable progress'' is the overarching 
requirement that implementation plan revisions under 42 U.S.C. 
7491(b)(2) must address.

    Id.
    EPA revised its regulations implementing sections 169A and 169B of 
the CAA in several iterations beginning in 1999. Among other things, 
the 1999 Regional Haze Rule codified the gap-filling approach EPA used 
in the 1991 NGS rulemaking. 64 FR 35714, 35739 (July 1, 1999). The 
Regional Haze Rule requires a State or Tribe to submit an 
implementation plan containing either emission limitations representing 
BART, 40 CFR 308(e)(1), or other alternative measures that will achieve 
greater reasonable progress than would have resulted from BART, 40 CFR 
308(e)(2). EPA anticipated at the time that ``the most likely 
alternative measures adopted * * * will be an emissions trading 
program,'' 64 FR at 35743, but did not limit the States or Tribes to 
such an approach. The requirements for alternative programs designed to 
achieve better than BART are established at 40 CFR 51.308(e)(2).
    The EPA modified the regulations addressing alternatives to source-
specific BART requirements in 2005 and again in 2006. In 2005, EPA 
established specific criteria for determining whether a trading program 
or other alternative measures provides for greater reasonable progress. 
70 FR 39104 (July 6, 2005). To assess whether an alternative meets this 
core requirement, States and Tribes must first consider the 
distribution of emissions that would result from BART as compared to 
the alternative. The regulations provide that


[[Page 10534]]


    [i]f the distribution of emissions is not substantially 
different than under BART, and the alternative measure results in 
greater emissions reductions, then the alternative measures may be 
deemed to achieve greater reasonable progress.

    40 CFR 51.308(e)(3). Where the alternative would result in a 
different distribution of emissions, the regulations require dispersion 
modeling to determine differences in visibility between BART and the 
trading program and establish a test against which to measure the 
results of the modeling. Id.
    In 2006, EPA again revised the Regional Haze Rule, focusing on 
regulatory issues associated with the use of an emissions trading 
program as an alternative to BART. In this rulemaking, EPA allowed for 
a less prescriptive approach to determining whether an alternative 
program provides for greater reasonable progress based on the clear 
weight of evidence. 40 CFR 51.308(e)(2)(i)(E).71 FR 60612 (Oct. 13, 
2006).
    To meet the requirement of the Regional Haze Rule that all 
necessary emission reductions take place during the period of the first 
long-term strategy for regional haze, if APS elects to implement this 
alternative emission control strategy, EPA is proposing to require 
Units 4 and 5 to comply with the 0.098 lb/MMBtu NOX emission 
limit by July 31, 2018, five months earlier than APS' proposed schedule 
for complete SCR installation and operation.
    In today's supplemental proposed rule, EPA is proposing to find, 
based on the weight of evidence, that a final rule requiring APS to 
shut down Units 1-3 by 2014 and install and operate SCR on Units 4 and 
5 by July 31, 2018 will result in greater reasonable progress towards 
the national visibility goal under section 169A(b)(2) than EPA's 
October 19, 2010 BART proposal. Therefore, EPA is proposing to add 
regulatory language to the proposed BART rule for FCPP that allows APS 
the option to implement its alternative emissions control strategy in 
lieu of EPA's BART determination.

III. EPA's Technical Analysis of Better Reasonable Progress Towards 
National Visibility Goal

    Units 1-3 comprise approximately 27% of the electricity-generating 
capacity at FCPP; however, Units 1-3 contribute disproportionately to 
facility-wide emissions of NOX (36%), PM (43%), and Hg 
(61%). The alternative emissions control strategy of shutting down 
Units 1-3 will consequently result in substantial emissions reductions 
at FCPP of all pollutants emitted by those units, particularly 
NOX, PM, and Hg. See Table 2.
    As discussed below, this supplemental proposed rule proposes to 
require Units 4 and 5, by July 31, 2018, to meet a lower NOX 
emission limit than APS' proposal, five months earlier than proposed by 
APS. In this supplemental proposed rule, EPA is proposing to approve 
this EPA revision of APS' proposal as an alternative to BART because it 
demonstrates better reasonable progress towards the national visibility 
goal. Our evaluation shows that the alternative emissions control 
strategy will provide greater visibility improvement at all 16 Class I 
areas than EPA's BART proposal. See 40 CFR 51.308(e). We discuss our 
proposed NOX emissions limit for Units 4 and 5 first because 
our subsequent analysis of the emissions reductions and visibility 
improvements rely in part on that limit. We will also briefly evaluate 
associated non-visibility environmental benefits from the alternative 
emission control strategy. Finally, we propose to retain and revise our 
October 19, 2010 BART proposal, with a revision described below 
regarding phase-in of new controls, as a contingent rule if APS does 
not implement its alternative emissions control strategy.
    By letter dated January 25, 2011, the National Parks Conservation 
Association, Black Mesa Water Coalition, Dine Care, Center for 
Biological Diversity, Heal Utah, Grand Canyon Trust, Natural Resources 
Defense Council, San Juan Citizens Alliance, Sevier Citizens for Clean 
Air & Water, Sierra Club and WildEarth Guardians submitted comments on 
EPA's BART proposal and the proposal APS outlined in its November 24, 
2010 letter to EPA. The letter from the consortium of environmental 
groups requested EPA to require lower emission limits for several 
pollutants emitted by FCPP. EPA considers the January 25, 2011 letter a 
comment, which we have posted to our docket and will provide a response 
to in our final rulemaking.

A. Estimated NOX Emissions Reductions

1. Proposed NOX Emission Limit To Apply on Units 4 and 5 
With Installation of SCR by July 31, 2018
    EPA's October 19, 2010 BART proposal provided for a facility-wide 
heat input-weighted emission limit for FCPP's Units 1-5 of 0.11 lb/
MMBtu on a 30-day rolling average basis.\3\ EPA determined that FCPP 
could achieve this limit by reducing NOX emissions from each 
of its five units by 80%. The limit we proposed in our October 19, 2010 
BART proposal did not include or rely on combustion controls, i.e., new 
Low-NOX burners (LNB). As described in more detail in our 
October 19, 2010 proposal (75 FR 64221), and the technical support 
document for the proposal, the original cell boiler design of Units 4 
and 5 is difficult to retrofit with modern LNB technology, and even if 
combustion controls might result in some improvement in NOX 
performance, the potential operational problems were not worth the 
small incremental reduction in NOX emissions. EPA proposed 
to provide a plant-wide limit to allow flexibility to FCPP to 
accommodate anticipated SCR retrofit challenges associated with the 
small fireboxes for Units 1-3.
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    \3\ The BART guidelines at 40 CFR part 51 appendix Y, require 
averaging times for EGUs be based on a 30-day rolling average.
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    EPA has evaluated the NOX emission limit we consider 
achievable under APS' alternative emissions control strategy. In APS' 
calculations for its November 24, 2010 proposal, APS assumed that under 
its proposed strategy, Units 4 and 5 would meet a limit of 0.11 lb/
MMBtu with installation and operation of SCR, not an 80% reduction from 
the Unit 4 and 5 baseline of 0.49 lb/MMBtu. If we apply an 80% 
emissions reduction solely to Units 4 and 5, APS should be able to 
achieve a NOX limit of 0.098 lb/MMBtu for each unit. Our 
calculations are based on average baseline emissions from Units 4 and 5 
of 0.49 lb/MMBtu each, reduced by a conservative estimate of 80% 
control of baseline emissions.
    In calculating the NOX emission limit of 0.098 lb/MMBtu, 
EPA is taking into account the degradation of the SCR catalyst over its 
lifetime resulting in the need for periodic replacement to maintain its 
activity and performance. Historically, FCPP units are scheduled for 
outages only once every three years. Based on this, EPA anticipates 
that APS will change out its catalyst on the historic outage schedule 
and the new catalyst will be installed every three years. EPA has 
calculated the 30-day emission limit (0.098 lb/MMbtu) to reflect the 
capability of the catalyst to reduce NOX at the end of this 
three year period.
    EPA has also determined that pursuing higher levels of 
NOX reduction efficiency (i.e., greater than 80%) from SCR 
on Units 4 and 5 is limited by the formation of sulfuric acid 
(H2SO4) from the SCR catalyst.\4\ Although more 
layers

[[Page 10535]]

of catalyst could be used in the SCR unit to further enhance 
NOX removal, the presence of additional catalyst would 
result in higher emissions of sulfuric acid, which is also a 
visibility-impairing pollutant. Minimizing the formation of primary 
SO3/H2SO4 in the catalyst bed is most 
important for visibility improvement at Mesa Verde National Park, the 
closest Class I area to FCPP. Primary SO3/
H2SO4 formed on the SCR catalyst would be capable 
of impairing visibility immediately after release into the atmosphere, 
whereas SO2 emissions need time and distance to convert to 
sulfuric acid or particulate ammonium sulfate before these emissions 
impact visibility.
---------------------------------------------------------------------------

    \4\ The SCR catalyst can oxidize sulfur dioxide (SO2) 
to sulfur trioxide (SO3, which, in the presence of water 
vapor, forms sulfuric acid) (H2SO4) aerosol, 
which causes visibility impairment.
---------------------------------------------------------------------------

    Finally, the achievable NOX emission limit for FCPP is 
affected by the high ash content in the coal burned by FCPP. The ash 
content is approximately 25%, which may adversely affect the capability 
of SCR to reach the highest end of the control efficiency range 
achieved at other power plants without the use of additional layers of 
catalyst or more frequent catalyst replacement.
    For these reasons, EPA is proposing to require a NOX 
emission limit in this supplemental proposed rule of 0.098 lb/MMBtu. We 
are proposing to approve the alternative emission control strategy 
requiring Units 1-3 to shut down by January 1, 2014 and Units 4 and 5 
to meet an 80% NOX reduction, with a limit of 0.098 lb/
MMBtu, by July 31, 2018. This emission limit can be met by installation 
of SCR.
    EPA is requesting comment on whether to provide FCPP with 
additional flexibility for meeting the 0.098 lb/MMBtu (30-day rolling 
average) limit by setting the limit as a heat-input weighted limit for 
Units 4 and 5,\5\ similar to our BART proposal on October 19, 2010 
which set a plant-wide heat-input-weighted limit for Units 1-5. EPA is 
also requesting comment on whether our final rule should also set a 
lower NOX emission limit that would be averaged over a 
longer averaging time to reflect the capability of the SCR when the 
catalyst is fresher at the beginning of the three-year outage schedule. 
Therefore, EPA is requesting comment on whether an additional, more 
stringent (i.e., lower than 0.098 lb/MMBtu) heat-input-weighted 
emission limit, representing greater than 80% control, and averaged 
over one or three years would be appropriate to assure the optimized 
operating efficiency for an SCR-controlled unit where EPA anticipates a 
three-year replacement of the catalyst.\6\ A heat-input-weighted limit 
averaged over one year could reflect the capability over the third year 
of the catalyst in use in either unit. A three-year average on an 
individual unit would reflect the capability of the catalyst to reduce 
NOX over its entire duration of use. EPA anticipates that 
the most stringent numerical limit would be for a single-unit limit on 
a 3-year rolling average. Under either of these approaches, the 
emission limit would be set such that the facility would be required to 
inject sufficient ammonia to maximize the reduction of the 
NOX no matter what the age of the catalyst.\7\
---------------------------------------------------------------------------

    \5\ The heat-input-weighted limit would be based on the heat 
input generated by each individual unit, rather than the rated 
capacity, which is identical for Units 4 and 5.
    \6\ This more strigent numerical NOX limit with the 
longer averaging time could reflect the capability of the catelyst 
over a more extended period than a short term limit that 
accommodates deterioration of catalyst activity just before new 
catalyst is installed.
    \7\ Although ammonia also contributes to visibility impairment, 
as discussed in the Technical Support Document for our October 29, 
2010 proposal, ammonia slip from the SCR is expected to react with 
SO3/H2SO4 in the flue gas to form 
particulate ammonium sulfate or bisulfate, which would be captured 
by the downstream air preheaters, scrubbers, and baghouses.
---------------------------------------------------------------------------

2. Alternative Emissions Control Strategy Will Result in Greater 
Visibility Improvement Than BART
    As noted above, EPA's BART proposal was for a facility-wide heat 
input-weighted NOX emission limit on Units 1-5 of 0.11 lb/
MMBtu on a 30-day rolling average basis.\8\ If EPA were to finalize its 
BART proposal, the facility-wide NOX emission limit would 
apply 5 years after the effective date of the final rule. To evaluate 
the alternative emissions control strategy, EPA is assuming that the 
earliest possible effective date for a final BART rule for FCPP would 
be January 1, 2012. This means that FCPP would be required to meet the 
facility-wide 0.11 lb/MMBtu NOX emission limit beginning in 
2017. APS calculated this to mean that in 2017 the total that could be 
emitted from Units 1-5 under EPA's BART proposal would be 9,184 tpy 
NOX (See item number 0080.1 in the docket for this 
rulemaking: ``Emissions calculations from APS for its Alternative 
Proposal 11-29-10.xlsx'').
---------------------------------------------------------------------------

    \8\ For PM, EPA proposed an emission limit of 0.012 lb/MMBtu to 
Units 1-3 and 0.015 lb/MMbtu on Units 4 and 5. The limit on Units 1-
3 would be achievable by installing and operating new particulate 
controls on those units, such as new electrostatic precipitators or 
baghouses, and by proper operation of the existing baghouses on 
Units 4 and 5.
---------------------------------------------------------------------------

    APS is proposing to reduce NOX (and other pollutants) by 
shutting down Units 1-3 by January 1, 2014, three years earlier than 
would be achieved by EPA's BART proposal. Because of these shutdowns, 
APS projected that NOX emissions from FCPP, under its 
proposed alternative, during 2014-2016 would be lower than would be 
emitted in those years under EPA's October 19, 2010 proposal. However, 
under the alternative emission control strategy, emissions in 2017 and 
2018 would be higher than in EPA's October 19, 2010 proposal, because 
APS would not achieve its final NOX reductions until the 
beginning of 2019. Under APS' proposal, beginning in 2019, Units 4 and 
5 would meet an emission limit of 0.11 lb/MMBtu, resulting in total 
emissions of 6,498 tpy NOX. Therefore, APS' proposal would 
produce approximately 30% less NOX emissions per year than 
EPA's BART proposal beginning in 2019.
    In contrast to APS' proposal to meet a limit of 0.11 lb/MMBtu by 
the end of 2018, EPA is proposing as the alternative emission control 
strategy to require a lower NOX emission limit of 0.098 lb/
MMBtu beginning July 31, 2018. EPA is proposing a compliance date five 
months earlier than APS' proposal in order to meet the requirement of 
the Regional Haze Rule that all necessary emission reductions for an 
alternative measure take place during the period of the first long-term 
strategy for regional haze.\9\ 40 CFR 51.308(e)(2)(iii). Under this 
alternative control strategy, total annual emissions of NOX 
from FCPP at 0.098 lb/MMBtu would be 5,798 tpy. EPA's emissions 
calculations are included in the docket for this proposed rulemaking 
(see ``EPA comparison of BART and alternative 2-3-11.xlsx''). If EPA 
finalizes a rule requiring APS to implement EPA's alternative emissions 
control strategy with a NOX emission limit of 0.098 lb/
MMBtu, FCPP would produce approximately 37% less NOX 
emissions per year than under EPA's BART proposal.
---------------------------------------------------------------------------

    \9\ The Regional Haze Rule requires revisions to regional haze 
implementation plans be submitted to EPA by July 31, 2018 and every 
ten years thereafter. This date marks the end of the first long term 
strategy period.
---------------------------------------------------------------------------

    The alternative emissions control strategy would realize the 37% 
greater NOX emissions reductions two years later than would 
potentially result from EPA's BART proposal, but within the period of 
the first long-term strategy for regional haze. Our evaluation, 
supported by the modeled visibility improvements discussed in Section 
C, is that significantly lower NOX emissions from FCPP 
occurring within the period of the first long term strategy and 
continuing on into the future, but occurring two years later than could 
potentially occur through EPA BART proposal, will achieve better 
reasonable

[[Page 10536]]

progress towards the Clean Air Act's national visibility goal.
    The amount by which NOX will be reduced between 2014 and 
2019 is somewhat less certain because of differing assumptions used in 
APS' and EPA's evaluations. APS compared NOX emissions for 
each year from 2014 until 2019 under its proposal against EPA's October 
19, 2010 BART proposal as reproduced in Table 3.

   Table 3--APS' Comparison of NOX Emissions (Tons) Based on EPA BART
Proposal and APS Alternative Proposal, Reproduced From November 24, 2010
                           Submittal From APS
------------------------------------------------------------------------
                                           EPA proposal    APS proposal
------------------------------------------------------------------------
2014....................................          45,132          28,948
2015....................................          45,132          28,948
2016....................................          45,132          28,948
2017....................................           9,184          28,948
2018....................................           9,184          28,948
2019....................................           9,184           6,498
------------------------------------------------------------------------

    The values APS used in Table 3, however, assume that EPA's BART 
determination would not have required installation of any 
NOX emissions controls until 2017 and that SCR would become 
fully operational on all 5 units simultaneously in 2017. Therefore, APS 
interpreted EPA's BART proposal to allow NOX emissions of 
45,132 tpy to continue until the beginning of 2017.
    EPA's BART proposal on October 19, 2010, however, included interim 
emission limits for the 5 units that would (if finalized) have applied 
following a phased-in schedule for SCR installation. Historically FCPP 
has operated on a 3-year outage cycle for its boilers.\10\ Therefore, 
EPA's BART proposal assumed that Units 1-3 would be retrofit 
simultaneously in one outage, Unit 4 would be retrofit in a second 
annual outage, and Unit 5 would be retrofit in the third annual outage.
---------------------------------------------------------------------------

    \10\ FCPP is a baseload power plant that operates its boilers 
year-round at full capacity except during outages. Power plants 
typically schedule periodic major and minor outages to allow for 
routine maintenance of its boiler units. To accomodate its five 
boiler units, EPA understands that the boilers at FCPP are on a 
three-year major outage cycle, with Units 4, 5, and 1-3 alternating 
major outages every 3 years.
---------------------------------------------------------------------------

    Table 4 compares our calculations of the short-term (2014-2019) 
NOX emissions and Table 5 compares our calculations for 
short-term (2014-2019) PM emissions, between EPA's BART proposal, 
assuming EPA could finalize the interim emissions limits to be 
effective January 1, 2012,\11\ and the alternative emissions control 
strategy with a final compliance date for installation and operation of 
SCR on Units 4 and 5 of July 31, 2018.\12\ (See ``EPA Comparison of 
BART and Alternative 2-3-11.xlsx'' in the docket for this rulemaking).
---------------------------------------------------------------------------

    \11\ The interim limits that EPA included in the proposed BART 
rule included a larger margin of compliance with the interim limits 
to provide APS the flexibility to develop strategies for meeting the 
plant-wide limit of 0.11 lb/MMBtu by 2017 in ways other than 
achieving 80% reduction equally on all units.
    \12\ The annual emissions in both Tables 2 and 4 are likely 
overestimated because they do not account for zero emissions from an 
individual unit (or set of units) when it is not operating during 
its scheduled outage.

    Table 4--EPA's Comparison of NOX Emissions (Tons) Based on EPA BART Proposal and the Alternative Emission
                                                Control Strategy
----------------------------------------------------------------------------------------------------------------
                                                                  Alternative
                                                   EPA BART        emission
                                                   proposal         control       Proposal with lower emissions
                                                                   strategy
----------------------------------------------------------------------------------------------------------------
2012..........................................          45,132          45,132  Same.
2013..........................................          45,132          45,132  Same.
2014..........................................          45,132          28,947  Alternative.
2015..........................................          33,908          28,947  Alternative.
2016..........................................          22,074          28,947  EPA BART.
2017..........................................           9,026          28,947  EPA BART.
2018..........................................           9,026          19,302  EPA BART.
2019 and beyond...............................           9,026           5,798  Alternative.
----------------------------------------------------------------------------------------------------------------


Table 5--EPA's Comparison of PM Emissions (Tons) Based on EPA BART Proposal and the Alternative Emission Control
                                                    Strategy
----------------------------------------------------------------------------------------------------------------
                                                                  Alternative
                                                   EPA BART        emission
                                                   proposal         control       Proposal with lower emissions
                                                                   strategy
----------------------------------------------------------------------------------------------------------------
2012..........................................           1,564           1,564  Same.
2013..........................................           1,564           1,564  Same.
2014..........................................           1,564             886  Alternative.
2015..........................................           1,564             886  Alternative.
2016..........................................           1,179             886  Alternative.
2017..........................................           1,179             886  Alternative.
2018..........................................           1,179             886  Alternative.
2019 and beyond...............................           1,179             886  Alternative.
----------------------------------------------------------------------------------------------------------------


[[Page 10537]]

    Therefore, if finalized as proposed and effective on January 1, 
2012, we estimate that EPA's BART proposal would result in lower 
NOX emissions from 2016-2018, an additional year (2016) 
compared to APS' calculations that do not account for interim limits. 
In 2014 and 2015, and beginning in 2019 into the future, the 
alternative emissions control strategy would result in lower 
NOX emissions than EPA's BART proposal. For PM, starting in 
2014, the alternative emission control strategy would always result in 
lower emissions of PM compared to EPA's BART proposal because of the 
closure of Units 1-3 in 2014.
    In today's supplemental proposed rule, EPA acknowledges that the 
interim emission limits proposed on October 19, 2010, were based on 
APS' historic outage schedule and were required to ensure that the 
installation of new controls occurred as expeditiously as practicable. 
APS may have challenged those proposed interim emission limits and 
requested EPA to finalize a BART rule that allowed installation of SCR 
on all units simultaneously 5 years after the effective date of the 
final rule (i.e., in 2017). Thus, if EPA's re-evaluation of the interim 
limits resulted in a determination that the interim limits were not 
practicable, the interim emission reductions we estimated over 2015-
2016, might not have been realized if the final rule was issued without 
interim limits. In our October 19, 2010 proposal, EPA also failed to 
include proposed regulatory language regarding the phased-in SCR 
installation, a gap which we address in Section D of this supplemental 
proposed rule.

B. Benefits in Addition to NOX Emissions Reductions

    On November 29, 2010, APS provided to EPA the spreadsheet on which 
its emission estimates were based. This spreadsheet is included in the 
docket for the proposed rulemaking (See the spreadsheet posted to the 
docket for this rulemaking: EPA-R09-OAR-2010-0683.0080.1, ``Emissions 
calculations from APS for its Alternative Proposal 11-29-10.xlsx''). 
Baseline emissions reported by APS (labeled ``status quo'' in the 
spreadsheet) of NOX, SO2, PM, Hg, and 
CO2, are included in Table 6. Emissions of NOX, 
SO2, and PM are reported in tons per year (tpy); Hg 
emissions are reported in pounds per year (lb/yr); and CO2 
emissions are reported in million tons per year.

 Table 6--Baseline Emissions of NOX (tpy), PM (tpy), SO2 (tpy), Hg (lb/Year), and CO2 (Million tpy) Reported by
                                                       APS
----------------------------------------------------------------------------------------------------------------
                                                              NOX         PM        SO2         Hg        CO2
----------------------------------------------------------------------------------------------------------------
Unit 1...................................................      5,790        186        748        113        1.6
Unit 2...................................................      4,751        215        731        109        1.5
Unit 3...................................................      5,643        277      1,373        139        2.1
Unit 4...................................................     14,474        443      4,298        117        6.0
Unit 5...................................................     14,474        443      4,611        116        6.0
----------------------------------------------------------------------------------------------------------------

    The alternative emission control strategy to shut down Units 1-3 by 
2014 not only results in 100% control of NOX, but also 100% 
control of all other pollutants emitted by those units, including 
SO2, PM, Hg and other hazardous air pollutants, and 
CO2, whereas EPA's proposal to install SCR on Units 1-5 and 
new PM controls on Units 1-3 would only result in 80% and 57% \13\ 
control of NOX and PM, respectively.
---------------------------------------------------------------------------

    \13\ The percent reduction in PM emissions was calculated for 
Units 1-3 and assumed that imposing an emission limit on Units 4 and 
5 would not change the measured emission rates from those units 
because Units 4 and 5 would continue to be controlled by the 
existing baghouses. Thus, the PM emission reduction is calculated as 
a MW-weighted average reduction from Units 1-3, using baseline 
emissions that range from 0.025 lb/MMBtu (Unit 1) to 0.029 lb/MMBtu 
(Units 2 and 3), and the proposed post-control BART limit of 0.012 
lb/MMBtu on Units 1-3.
---------------------------------------------------------------------------

C. Modeling and Demonstrating Reasonable Progress

    The Regional Haze Rule requires that implementation plans that rely 
on an alternative measure to BART demonstrate that the alternative 
achieves greater reasonable progress than would be achieved through the 
installation and operation of BART. 40 CFR 51.308(e)(2). The rule 
further states that ``[i]f the distribution of emissions is not 
substantially different than under BART, and the alternative measure 
results in greater emissions reductions, than the alternative measures 
may be deemed to achieve greater reasonable progress''. 40 CFR 
51.308(e)(3). Because the emissions reductions under EPA's October 19, 
2010 BART proposal and the alternative emission control strategy 
proposed in this supplemental proposed rule occur from the same 
facility, the distribution of emissions under BART and the alternative 
are not substantially different. Therefore, because the alternative 
emission control strategy results in greater emissions reductions that 
our BART proposal, EPA may deem the alternative emission control 
strategy to achieve greater reasonable progress.
    Although an explicit modeling demonstration is not required based 
on the provisions of 40 CFR 31.08(e)(3), APS provided a modeling 
analysis demonstrating that its proposed alternative would result in 
greater visibility improvement than EPA's October 2010 BART proposal. 
EPA evaluated the modeling submitted by APS and modeled our alternative 
emission control strategy in comparison to our October 2010 proposal. 
EPA compared our BART proposal to the alternative emissions control 
strategy based on emissions after full SCR installation is complete. 
For EPA's BART proposal, SCR would have been completed on all units in 
2017 if the final BART rule becomes effective in 2012. For the 
alternative emissions control strategy, EPA is proposing emissions 
reductions from full SCR installation and operation on Units 4 and 5 be 
completed by July 31, 2018.
    APS provided EPA with the modeling files generated by AECOM.\14\ 
EPA has evaluated those modeling files for this supplemental proposed 
rule. APS' modeling differs in some minor ways from the modeling used 
to support EPA's October 19, 2010 BART proposal.
---------------------------------------------------------------------------

    \14\ Modeling files from APS and EPA modeling analyses are 
available from EPA upon request. Please see the FOR FURTHER 
INFORMATION CONTACT section of this supplemental proposed rule.
---------------------------------------------------------------------------

    In the Technical Support Document (TSD) for our October 19, 2010 
BART proposal, EPA provided the emission rates of various pollutants 
from each of the five units used in the CALPUFF modeling analysis. 
These modeling inputs for the SCR control case, in pounds per hour (lb/
hr) are included in Table 7 and represent the 24-hour average actual 
emission rate from the highest emitting day of the meteorological 
period modeled (2001-2003), consistent with the guidelines

[[Page 10538]]

provided in 40 CFR Part 51, Appendix Y (BART Guidelines). The CALPUFF 
inputs require values for SO2, sulfate (SO4), 
NOX, secondary organic aerosol (SOA), fine PM, coarse PM, 
and elemental carbon (EC).
    The modeling inputs used by APS in its analysis of its proposal are 
included in Table 8. APS' emission inputs for NOX and PM 
rely on EPA's proposed 30-day rolling average emission limits (as shown 
in Table 40 of our Technical Support Document). These inputs represent 
80% control of baseline NOX emissions: limit for Unit 1 = 
0.16 lb/MMBtu, Unit 2 = 0.13 lb/MMBtu, Unit 3 = 0.12 lb/MMBtu, and 
Units 4 and 5 = 0.10 lb/MMBtu each; and PM emission rates of 0.012 lb/
MMBtu from Units 1-3 and 0.015 lb/MMBtu from Units 4 and 5. APS used 
the peak 24-hour average emissions when modeling the Baseline Impact, 
but used the lower 30-day rolling average emission limits shown in 
Table 8 to model visibility benefits from controls rather than the 
highest emitting day average shown in Table 7. Thus, the baseline and 
SCR control scenarios from APS' modeling are not directly comparable 
because of the different averaging times of the inputs (24-hour versus 
30-day average).
---------------------------------------------------------------------------

    \15\ In our October 2010 BART proposal, we conducted our 
modeling analyses for NOX and PM controls separately. In 
Table 6, the emission inputs for NOX and SO4, 
from the SCR control case, are combined with inputs for SOA, PM 
fine, PM coarse, and EC, from the PM control case, for better 
comparison with APS's representation of EPA's BART proposal. 
Emission inputs for SO2 were identical for the SCR and PM 
control scenarios.

 Table 7--EPA's CALPUFF Modeling Inputs Used for Our October 19, 2010 BART Proposal With SCR on Units 1-5 and PM
                                           Controls on Units 1-3 \15\
----------------------------------------------------------------------------------------------------------------
                                                             Unit 1     Unit 2     Unit 3     Unit 4     Unit 5
----------------------------------------------------------------------------------------------------------------
SO2......................................................     522.54     615.12    1042.09    2026.10    2131.85
SO4......................................................       8.57       8.58      11.06       2.24       2.25
NOX......................................................     404.03     319.89     394.16    1003.20     901.71
SOA......................................................       9.40       9.41      12.13      32.00      32.20
PM fine..................................................      17.26      20.39      23.60     100.93      48.02
PM coarse................................................      13.19      15.58      18.03      77.12      36.69
EC.......................................................       0.66       0.78       0.91       3.88       1.85
----------------------------------------------------------------------------------------------------------------


    Table 8--APS' CALPUFF Modeling Inputs Representing EPA's BART Proposal (Units 1-5), Combining NOX and PM
               Controls, Provided by APS to Support Its Alternative Proposal (Units 4 and 5 Only)
----------------------------------------------------------------------------------------------------------------
                                                                   Units 1 and 2      Unit 3       Units 4 and 5
----------------------------------------------------------------------------------------------------------------
SO2.............................................................         1137.66         1042.09         4157.95
SO4.............................................................           17.15           11.06            4.49
NOX.............................................................          681.62          363.84         1605.10
SOA.............................................................           18.81           12.13           64.20
PM fine.........................................................           27.71           17.87          122.89
PM coarse.......................................................           11.29            7.28           93.90
EC..............................................................            1.06            0.69            4.72
----------------------------------------------------------------------------------------------------------------

    With respect to other modeling assumptions, APS used the same 
assumptions that supported EPA's October 19, 2010 BART proposal. APS 
directly used EPA's modeling inputs for the 1 ppb (IWAQM default) 
background ammonia scenario from our proposed BART determination and 
modeled additional scenarios: EPA's BART proposal using emission inputs 
for Units 1-5 in Table 7, and APS's proposed alternative using emission 
inputs from Table 7 for only Units 4 and 5 (with no modeling of Units 
1-3 to account for shut down of those units).
    EPA reviewed APS' emission inputs and modeling files and determined 
that when APS modeled EPA's October 19, 2010 BART proposal, APS relied 
on lower NOX and PM emissions than EPA used in our proposal. 
NOX emissions modeled by AECOM were 6-16% lower than EPA's 
modeling values from our proposal, and PM emissions as modeled by AECOM 
were 18-60% lower than our proposal. APS estimated that EPA's BART 
proposal (using the inputs from Table 7) would reduce the impact of 
FCPP on the 16 Class I areas by an average of 59%. APS modeling showed 
that its alternative emissions control strategy would reduce the impact 
of FCPP on the 16 Class I areas by an average of 74% (See Table 8).

 Table 8--Modeling Results--98th Percentile Delta dv Improvement and Percent Change in Delta Deciview (dv) \16\
 Impact From EPA's BART Proposal and APS' Alternative Proposal Compared to Baseline Impacts From 2001-2003 Using
                              1 ppb Ammonia Background Scenario as Modeled by AECOM
----------------------------------------------------------------------------------------------------------------
                                    Distance to    Baseline    Improvement from EPA's     Improvement from APS'
                                        FCPP        impact            proposal                  proposal
           Class I area            -----------------------------------------------------------------------------
                                     Kilometers
                                        (km)       Delta dv     Delta dv        %         Delta dv        %
----------------------------------------------------------------------------------------------------------------
Arches National Park..............          245         4.11          2.5           58         3.08           75
Bandelier Wilderness Area.........          216         2.90         1.71           58         2.12           74
Black Canyon of the Gunnison WA...          217         2.36         1.47           62         1.84           76
Canyonlands NP....................          214         5.24         2.97           54         3.86           72
Capitol Reef NP...................          283         3.23         1.94           54         2.46           72

[[Page 10539]]

 
Grand Canyon NP...................          345         1.63         0.91           58         1.14           75
Great Sand Dunes NM...............          279         1.16         0.69           63         0.84           76
La Garita WA......................          202         1.72         1.08           63          1.3           77
Maroon Bells Snowmass WA..........          294         1.04         0.65           64         0.79           78
Mesa Verde NP.....................           62         5.95         2.67           48         3.57           66
Pecos WA..........................          258         2.16         1.19           59         1.55           74
Petrified Forest NP...............          224         1.40         0.69           58         0.93           74
San Pedro Parks WA................          160         3.88         2.15           55         2.77           72
West Elk WA.......................          137         1.87         1.24           64         1.45           77
Weminuche WA......................          245         2.76         1.76           61         2.08           75
Wheeler Peak WA...................          265         1.53         0.88           60         1.12           75
                                   -----------------------------------------------------------------------------
    Total Delta dv or Average %     ...........        42.93         24.5          59%         30.9          74%
     Change in Delta dv...........
----------------------------------------------------------------------------------------------------------------

    EPA re-modeled the visibility impact of combined SCR and PM 
controls as outlined in our October 2010 BART proposal (but were 
modeled separately in our proposal) and the visibility impact of the 
alternative emissions control strategy. EPA's emission inputs continued 
to rely on the peak 24-hour average value over the meteorological 
period for NOX, rather than the 30-day rolling average 
emission limits used by APS. For PM, emission inputs are based on our 
proposed BART emission limits. Our emission inputs are shown in Table 9 
and the results of our modeling is shown in Table 10.
---------------------------------------------------------------------------

    \16\ The Baseline Delta dv values represent the visibility 
impact of FCPP on the given Class I area. Higher Delta dv 
Improvement values represent a smaller anticipated visibility impact 
of FCPP on the Class I area after controls are applied, and thus 
greater percent improvement.
---------------------------------------------------------------------------

    Table 9 differs from EPA's values in Table 7 because the 
combination of PM and NOX controls into a single modeling 
scenario results in lower sulfate emissions because new PM controls on 
Units 1-3 would provide additional control of the sulfuric acid 
produced by the SCR system. In estimating the reduction of sulfuric 
acid by the new PM controls, EPA chose to use the capture efficiency of 
a wet ESP (28%) in lieu of a baghouse (90%) \17\ because a wet ESP is 
expected to result in a lower capture rate for sulfuric acid than a 
baghouse, thus providing a more conservative estimate of the visibility 
benefits of combined PM and NOX controls from EPA's BART 
proposal.
---------------------------------------------------------------------------

    \17\ We proposed as BART a PM emission limit of 0.012 lb/MMBtu 
that could be met by either a wet ESP or a baghouse. We did not 
specify which control technology must be used to meet the proposed 
BART limit.

Table 9--EPA's CALPUFF Modeling Inputs (lb/hr) \18\ Representing our BART Proposal (NOX and PM Controls Combined
                 Units 1-5) and APS' Alternative Proposal (Units 4 and 5 Only With NOX Controls)
----------------------------------------------------------------------------------------------------------------
                                                                   Units 1 and 2      Unit 3       Units 4 and 5
----------------------------------------------------------------------------------------------------------------
SO2.............................................................         1137.66         1042.09         4157.95
SO4.............................................................           12.51            8.07            4.49
NOX.............................................................          723.92          394.16         1904.91
SOA.............................................................           18.81           12.13           64.20
PM fine.........................................................           27.70           17.87          122.89
PM coarse.......................................................           11.29            7.28           93.90
EC..............................................................            1.06            0.69            4.72
----------------------------------------------------------------------------------------------------------------

    EPA's modeling analysis shows that our BART proposal, which 
combines new NOX controls to achieve 80% reduction on Units 
1-5 and new PM controls on Units 1-3, would reduce FCPP's visibility 
impact on the 16 Class I areas by an average of 57%.\19\ The 
alternative emissions control strategy, to shut down Units 1-3 and 
install SCR on Units 4 and 5, would reduce FCPP's visibility impact on 
the 16 Class I areas by an average of 72%. Our modeling analysis of the 
alternative emissions control strategy shows about 2% lower visibility 
improvement compared to APS' analysis because we used slightly 
different emission inputs than APS.\20\
---------------------------------------------------------------------------

    \18\ The emission input calculations for this Supplemental 
Notice are provided in the docket as a spreadsheet titled ``FCPP--
Supplemental Emission--Inputs 01-04-11.xlsx''.
    \19\ In our October 2010 proposal, our separate modeling 
analyses of the NOX and PM controls showed that 
individually, SCR on Units 1-5 would reduce the visibility impact of 
FCPP by an average of 57% and PM controls on Units 1-3 by less than 
1%.
    \20\ EPA's inputs for NOX are consistent with the 
BART guidelines for modeling anticipated visibility improvement. 
Additionally, in modeling the combined effects of SCR and PM 
controls on Units 1-3 for the EPA BART scenario, EPA included a 
factor of 0.72 in the sulfuric acid calculation (as SO4) 
to account for the additional 28% sulfuric acid control provided by 
the wet ESP as reported in EPRI 2010. AECOM did not include 
additional control of sulfuric acid from the new wet ESP on Units 1-
3.

[[Page 10540]]



  Table 10--Modeling Results--98th percentile Delta dv Improvement and Percent Change in Delta Deciview (dv) 21
Impact From EPA's BART Proposal and Alternative Emission Control Strategy Compared to Baseline Impacts From 2001-
                         2003 Using 1 ppb Ammonia Background Scenario as Modeled by EPA
----------------------------------------------------------------------------------------------------------------
                                    Distance to    Baseline    Improvement from EPA's       Improvement from
                                        FCPP        impact            proposal            alternative emission
           Class I area            ----------------------------------------------------     control strategy
                                     Kilometers                                        -------------------------
                                        (km)       Delta dv     Delta dv        %         Delta dv        %
----------------------------------------------------------------------------------------------------------------
Arches National Park..............          245         4.11         2.41           55         2.99           72
Bandelier Wilderness Area.........          216         2.90         1.65           56         2.06           72
Black Canyon of the Gunnison WA...          217         2.36         1.43           60          1.8           75
Canyonlands NP....................          214         5.24         2.85           52         3.76           70
Capitol Reef NP...................          283         3.23         1.88           52          2.4           70
Grand Canyon NP...................          345         1.63         0.88           56         1.12           73
Great Sand Dunes NM...............          279         1.16         0.68           61         0.83           74
La Garita WA......................          202         1.72         1.06           61         1.28           75
Maroon Bells Snowmass WA..........          294         1.04         0.65           63         0.78           77
Mesa Verde NP.....................           62         5.95         2.49           46         3.42           64
Pecos WA..........................          258         2.16         1.18           57         1.52           72
Petrified Forest NP...............          224         1.40         0.66           56         0.92           72
San Pedro Parks WA................          160         3.88         2.04           53         2.75           70
Weminuche WA......................          137         1.87          1.2           62         1.42           76
West Elk WA.......................          245         2.76         1.74           59         2.04           73
Wheeler Peak WA...................          265         1.53         0.85           58          1.1           73
                                   -----------------------------------------------------------------------------
    Total Delta dv or Average %     ...........        42.94        23.65          57%        30.19          72%
     Change in Delta dv...........
----------------------------------------------------------------------------------------------------------------

D. Alternative Emission Control Strategy Has Lower Cost Than EPA's 
Proposed BART Determination

    APS did not provide any information to EPA on the cost of its 
proposed alternative. In our October 19, 2010 BART proposal and TSD, we 
presented cost and cost effectiveness information for SCR on Units 1-5. 
The cost effectiveness of SCR ranged from $2,515-$2,678 per ton of 
NOX reduced. The total capital investment and total annual 
cost of SCR on Units 1-3 represented approximately 39% of total 
facility-wide cost. Therefore, this alternative emissions control 
strategy, which calls for closing Units 1-3 and installing SCR on Units 
4 and 5, should be approximately 39% less costly than EPA's proposed 
BART determination requiring SCR retrofits on all five units.
---------------------------------------------------------------------------

    \21\ The Delta dv values represent the visibility impact of FCPP 
on the given Class I area. Higher Delta dv Improvement values 
represent a smaller anticipated visibility impact of FCPP on the 
Class I area after controls are applied, and thus greater percent 
improvement.
---------------------------------------------------------------------------

IV. EPA's Supplemental Proposal

    In this proposal, EPA is proposing that the closure of Units 1-3 by 
2014 and installation and operation of SCR on Units 4 and 5 to meet a 
NOX emission limit of 0.098 lb/MMBtu each by July 31, 2018, 
represents reasonable progress towards the national visibility goal 
under CAA Section 169A(b)(2) because it would result in better 
visibility improvement at a lower cost than our October 19, 2010 BART 
proposal. EPA is proposing to require FCPP to meet a NOX 
emission limit for Units 4 and 5 of 0.098 lb/MMBtu each on the 30-day 
rolling average by July 31, 2018.
    EPA is supplementing our October 19, 2010 BART proposal with 
regulatory language that would allow APS to comply with this 
alternative emission control strategy in lieu of complying with our 
October 19, 2010 BART proposal. EPA is continuing to propose to require 
APS to meet PM and 10% opacity limits on Units 4 and 5, as well as the 
20% opacity limits for controlling dust from coal and ash handling and 
storage facilities, included in our October 19, 2010 proposal. The 
October 2010 proposal required FCPP to meet the PM emission limits on 
Units 4 and 5 180 days after the re-start of the units following the 
installation of SCR on those units. EPA is requesting comment on 
whether the PM emission limits and opacity limits on Units 4 and 5 
should become effective prior to SCR installation, for both the 
proposed BART determination and the alternative emission control 
strategy.
    In this supplemental proposed rule, EPA is also including a 
proposed schedule for installation of add-on post-combustion 
NOX controls for our October 19, 2010 proposed BART 
determination, which was not included in the 2010 proposal, deleting 
the requirement under paragraph (i) to submit a plan and schedule for 
compliance to the Regional Administrator within 180 days of the 
effective date of the rule because it is redundant and less specific 
than the new requirement added as subparagraph (6) of paragraph (i) 
that a final plan be submitted by January 1, 2013, adding a test 
substitution allowance for PM testing on Units 4 and 5 that was 
included for Unit 1-3 but inadvertently excluded for Units 4 and 5 in 
the October 2010 proposal, and also replacing references to ``SCR'' in 
the regulatory language with ``add-on post-combustion NOX 
controls''.
    EPA is proposing to require FCPP to install and operate add-on 
post-combustion NOX controls on at least 560 MW of net 
generation within 3 years of the effective date of the final rule, and 
on at least 1310 MW of net generation within 4 years of the effective 
date of the final rule. EPA's proposed installation schedule requires 
add-on post-combustion NOX controls be installed on a given 
MW capacity rather than on specific units, in order to provide FCPP 
with the flexibility to determine the order of retrofits. As proposed, 
FCPP would have the option to begin retrofits on Units 1-3, or on Unit 
4 or 5.
    EPA is requesting comment by May 2, 2011 on both our October 19, 
2010 BART proposal and this supplemental proposed rule proposing to 
allow APS to implement this alternative emissions control strategy. We 
are additionally requesting comment on adding a NOX emission 
limit requiring greater than 80% control over longer averaging times 
weighted for heat-input, and the

[[Page 10541]]

appropriate effective date of the PM limits on Units 4 and 5.
    EPA understands that APS must receive approvals from several 
Federal and State agencies (e.g., the Federal Energy Regulatory 
Commission, the Arizona Corporation Commission, and the California 
Public Utilities Commission), and lease renewals from the Navajo 
Nation, which are expected to occur by the end of 2012, in order to 
implement this alternative emission control strategy. If this 
Supplemental rulemaking is finalized as proposed, APS will be required 
either to comply with this alternative emissions control strategy or 
the requirements of EPA's October 19, 2010 BART proposal as modified by 
this supplemental proposed rule regarding phase-in of controls. FCPP 
will be required to provide notification to EPA of its intended 
strategy for reducing NOX by June 1, 2012 and its final 
decision by January 1, 2013.

V. Administrative Requirements

A. Executive Order 12866: Regulatory Planning and Review

    This proposed action is not a ``significant regulatory action'' 
under the terms of Executive Order (EO) 12866 (58 FR 51735, October 4, 
1993) because it is supplementing a proposed rule that applies to only 
one facility and is not a rule of general applicability. This 
supplemental proposed rule, therefore, is not subject to review under 
EO 12866. This action proposes a source-specific FIP for the Four 
Corners Power Plant on the Navajo Nation.

B. Paperwork Reduction Act

    This proposed 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 proposed FIP 
applies to a single facility, Four Corners Power Plant, 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 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 supplemental 
proposed 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 supplemental 
proposed rule to our proposed action on small entities, I certify that 
this supplemental proposed rule to our proposed action will not have a 
significant economic impact on a substantial number of small entities. 
The FIP for Four Corners Power Plant being addressed today would not 
impose any new requirements on small entities. See Mid-Tex Electric 
Cooperative, Inc. v. FERC, 773 F.2d 327 (DC Cir. 1985)

D. Unfunded Mandates Reform Act (UMRA)

    This supplemental proposed rule, if finalized, will impose an 
enforceable duty on the private sector owners of FCPP. However, this 
proposed 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 five units at FCPP and the cost to install and 
operate new PM controls on Units 1-3 does not exceed $100 million (in 
1996 dollars) in any one year and the alternative emissions control 
strategy to shut down Units 1-3 and install SCR on Units 4 and 5 is 
expected to be less costly than EPA's proposed BART determination. 
Thus, this supplemental proposed rule is not subject to the 
requirements of sections 202 or 205 of UMRA. This proposed 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 supplemental proposed rule will 
not impose direct compliance costs on the Navajo Nation, and will not 
preempt Navajo law. This supplemental proposed rule will, if finalized, 
reduce the emissions of two pollutants from a single source, the Four 
Corners Power Plant.

E. Executive Order 13132: Federalism

    Under section 6(b) of Executive Order 13132, EPA may not issue an 
action that has federalism implications, that imposes substantial 
direct compliance costs on State or local governments, and that is not 
required by statute, unless the Federal government provides the funds 
necessary to pay the direct compliance costs incurred by State and 
local governments, or EPA consults with State and local officials early 
in the process of developing the proposed action. In addition, under 
section 6(c) of Executive Order 13132, EPA may not issue an action that 
has federalism implications and that preempts State law, unless the 
Agency consults with State and local officials early in the process of 
developing the proposed action.
    EPA has concluded that this supplemental proposed rule, if 
finalized, may have federalism implications because it makes calls for 
emissions reductions of two pollutants from a specific source on the 
Navajo Nation. However, the supplemental proposed rule, if finalized, 
will not impose substantial direct compliance costs on the Tribal 
government, and will not preempt Tribal law. Thus, the requirements of 
sections 6(b) and 6(c) of the Executive Order do not apply to this 
action.
    Consistent with EPA policy, EPA nonetheless consulted with 
representatives of Tribal governments early in the process of 
developing the proposed action to permit them to have

[[Page 10542]]

meaningful and timely input into its development.

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

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, Nov. 9, 2000), requires 
EPA to develop ``an accountable process to ensure meaningful and timely 
input by Tribal officials in the development of regulatory policies 
that have tribal implications.'' Under Executive Order 13175, to the 
extent practicable and permitted by law, EPA may not issue a regulation 
that has Tribal implications, that imposes substantial direct 
compliance costs on Indian Tribal governments, and that is not required 
by statute, unless the Federal government provides the funds necessary 
to pay 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. In 
addition, to the extent practicable and permitted by law, EPA may not 
issue a regulation that has Tribal implications and pre-empts Tribal 
law unless EPA consults with Tribal officials early in the process of 
developing the proposed regulation and prepares a tribal summary impact 
statement.
    EPA has concluded that this supplemental proposed rule, if 
finalized, may have Tribal implications because it will require 
emissions reductions of two pollutants by a major stationary source 
located and operating on the Navajo reservation. However, this 
supplemental proposed rule, if finalized, will neither impose 
substantial direct compliance costs on Tribal governments nor pre-empt 
Tribal law because the proposed FIP imposes obligations only on the 
owners or operator of the Four Corners Power Plant.
    EPA has consulted with officials of the Navajo Nation in the 
process of developing our October 19, 2010 proposed FIP. Additionally, 
EPA discussed our plans for supplementing our proposal with our 
analysis of APS' alternative emissions control strategy with Navajo 
Nation Environmental Protection Agency. EPA had an in-person meeting 
with Tribal representatives prior to the October 19, 2010 proposal and 
will continue to consult with Tribal officials during the public 
comment period on the proposed FIP. In addition, EPA provided Navajo 
Nation and other Tribal governments additional time to submit formal 
comments on our Advanced Notice of Proposed Rulemaking. Several Tribes, 
including the Navajo, submitted comments which EPA considered in 
developing this NPR. Therefore, EPA has allowed the Navajo Nation to 
provide meaningful and timely input into the development of this 
proposed rule and will continue to consult with the Navajo Nation and 
other affected Tribes prior to finalizing our BART determination.

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 supplemental proposed rule is not subject to Executive Order 
13045 because it requires emissions reductions of two pollutants from a 
single stationary source. Because this supplemental proposed rule only 
applies to a single source and is not a proposed 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 final rule will reduce 
emissions of PM and NOX, which contribute to ozone and PM 
formation, the rule will have a beneficial effect on children's health 
be 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 requirements. It 
would not be practical to specify these standards in the current 
proposed 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. 
EPA is requesting comment on other appropriate VCS for measuring 
opacity or emissions of PM and NOX.
Particulate Matter Emissions--EPA Methods 1 Through 5
Opacity--EPA Method 9 and Performance Specification Test 1 for Opacity 
Monitoring
NOX Emissions--Continuous Emissions Monitors

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,

[[Page 10543]]

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 supplemental proposed rule, if 
finalized, 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. This proposed rule 
requires emissions reductions of two pollutants from a single 
stationary source, Four Corners Power Plant.

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: February 9, 2011.
Jared Blumenfeld,
Regional Administrator, Region IX.

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

PART 49--[AMENDED]

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

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

    2. Section 49.23 is amended by adding paragraphs (i) and (j) to 
read as follows:


Sec.  49.23  Federal Implementation Plan Provisions for Four Corners 
Power Plant, Navajo Nation.

* * * * *
    (i) Regional Haze Best Available Retrofit Technology limits for 
this plant are in addition to the requirements of paragraphs (a) 
through (h) of this section. All definitions and testing and monitoring 
methods of this section apply to the limits in paragraph (i) of this 
section except as indicated in paragraphs (i)(1) through (4) of this 
section. The interim NOX emission limits for each unit shall 
be effective 180 days after re-start of the unit after installation of 
add-on post-combustion NOX controls for that unit and until 
the plant-wide limit goes into effect. The plant-wide NOX 
limit shall be effective no later than 5 years after the effective date 
of this paragraph. The owner or operator may elect to meet the plant-
wide limit early to remove the individual unit limits. Particulate 
limits for Units 1, 2, and 3 shall be effective 180 days after re-start 
of the units after installation of the PM controls but no later than 5 
years after the effective date of this paragraph (i). Particulate 
limits for Units 4 and 5 shall be effective 180 days after re-start of 
the units after installation of the add-on post-combustion 
NOX controls.
    (1) Particulate Matter for units 1, 2, and 3 shall be limited to 
0.012 lb/MMBtu for each unit as measured by the average of three test 
runs with each run collecting a minimum of 60 dscf of sample gas and 
with aduration of at least 120 minutes. Sampling shall be performed 
according to 40 CFR Part 60 Appendices A-1 through A-3, Methods 1 
through 4, and Method 5 or Method 5e. The averaging time for any other 
demonstration of the particulate matter compliance or exceedence shall 
be based on a six hour average. Particulate testing shall be performed 
annually as required by paragraph (e)(3) of this section. This test 
with 120 minute test runs may be substituted and used to demonstrate 
compliance with the particulate limits in paragraph (d)(2) of this 
section.
    (2) Particulate Matter from units 4 and 5 shall be limited to 0.015 
lb/MMbtu for each unit as measured by the average of three test runs 
with each run collecting a minimum of 60 dscf of sample gas and with a 
duration of at least 120 minutes. Sampling shall be performed according 
to 40 CFR Part 60 Appendices A-1 through A-3, Methods 1 through 4 and 
Method 5 or Method 5e. The averaging time for any other demonstration 
of the particulate matter compliance or exceedence shall be based on a 
six hour average. Particulate testing shall be performed annually as 
required by paragraph (e)(3) of this section. This test with 120 minute 
test runs may be substituted and used to demonstrate compliance with 
the particulate limits in paragraph (d)(2) of this section.
    (3) No owner or operator shall discharge or cause the discharge of 
emissions from the stacks of Units 1, 2, 3, 4 or 5 into the atmosphere 
exhibiting greater than 10% opacity, excluding uncombined water 
droplets, averaged over any six (6) minute period.
    (4) Plant-wide nitrogen oxide emission limits.
    (i) The plant-wide nitrogen oxide limit, expressed as nitrogen 
dioxide (NO2), shall be 0.11 lb/MMBtu as averaged over a 
rolling 30 calendar day period. NOX emissions for each 
calendar day shall be determined by summing the hourly emissions 
measured as pounds of NO2 for all operating units. Heat 
input for each calendar day shall be determined by adding together all 
hourly heat inputs, in millions of BTU, for all operating units. Each 
day the 30 day rolling average shall be determined by adding together 
that day's and the preceding 29 days' pounds of NO2 and 
dividing that total pounds of NO2 by the sum of the heat 
input during the same 30 day period. The results shall be the 30 day 
rolling pound per million BTU emissions of NOX.
    (ii) The interim NOX limit for each individual boiler 
with add-on post-combustion NOX control shall be as follows:
    (A) Unit 1 shall meet a rolling 30 calendar day NOX 
limit of 0.21 lb/MMBtu,
    (B) Unit 2 shall meet a rolling 30 calendar day limit of 0.17 lb/
MMBtu,
    (C) Unit 3 shall meet a rolling 30 calendar day limit of 0.16 lb/
MMBtu,
    (D) Units 4 and 5 shall meet a rolling 30 calendar day limit of 
0.11 lb/MMBtu, each.
    (iii) Schedule for add-on post-combustion NOX controls 
installation
    (A) Within 3 years of the effective date of this rule, FCPP shall 
have installed add-on post-combustion NOX controls on at 
least 560 MW (net) of generation.
    (B) Within 4 years of the effective date of this rule, FCPP shall 
have installed add-on post-combustion NOX controls on at 
least 1310 MW (net) of generation.
    (iv) Testing and monitoring shall use the 40 CFR part 75 monitors 
and meet the 40 CFR part 75 quality assurance requirements. In addition 
to these 40 CFR part 75 requirements, relative accuracy test audits 
shall be performed for both the NOX pounds per hour 
measurement and the heat input measurement. These shall have relative 
accuracies of less than 20%. This testing shall be evaluated each time 
the 40 CFR part 75 monitors undergo relative accuracy testing.
    (v) 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 of the 30 day 
plant wide rolling average.
    (vi) Upon the effective date of the plant-wide NOX 
average, the owner or operator shall have installed CEMS and COMS 
software that complies with the requirements of this section.
    (5) In lieu of meeting the NOX requirements of paragraph 
(i)(4) of this section, FCPP may choose to permanently shut down Units 
1, 2, and 3 by January 1, 2014 and meet the requirements of this 
paragraph to control NOX emissions from Units 4 and

[[Page 10544]]

5. By July 31, 2018, Units 4 and 5 shall be retrofitted with add-on 
post-combustion NOX controls to reduce NOX 
emissions. Units 4 and 5 shall each meet a 0.098 lb/MMBtu emission 
limit for NOX expressed as NO2 over a rolling 30 
day average. Emissions from each unit shall be measured with the 40 CFR 
part 75 continuous NOX monitor system and expressed in the 
units of lb/MMBtu and recorded each hour. A valid hour of 
NOX data shall be determined per 40 CFR part 75. For each 
calendar day, every valid hour of NOX lb/MMBtu measurement 
shall be averaged to determine a daily average. Each daily average 
shall be averaged with the preceding 29 valid daily averages to 
determine the 30 day rolling average. The NOX monitoring 
system shall meet the data requirements of 40 CFR 60.49Da(e)(2) (at 
least 90% valid hours for all operating hours over any 30 successive 
boiler operating days). Emission testing using 40 CFR part 60 appendix 
A Method 7E may be used to supplement any missing data due to 
continuous monitor problems. The 40 CFR part 75 requirements for bias 
adjusting and data substitution do not apply for adjusting the data for 
this emission limit.
    (6) By June 1, 2012, the owner or operator shall submit a letter to 
the Regional Administrator updating EPA of the status of lease 
negotiations and regulatory approvals required to comply with paragraph 
(i)(5) of this section. By January 1, 2013, the owner or operator shall 
notify the Regional Administrator by letter whether it will comply with 
paragraph (i)(5) of this section or whether it will comply with 
paragraph (i)(4) of this section and shall submit a plan and time table 
for compliance with either paragraph (i)(4) or (i)(5) of this section. 
The owner or operator shall amend and submit this amended plan to the 
Regional Administrator as changes occur.
    (7) The owner or operator shall follow the requirements of 40 CFR 
part 71 for submitting an application for permit revision to update its 
Part 71 operating permit after it achieves compliance with paragraph 
(i)(4) or (i)(5) of this section.
    (j) Dust. Each owner or operator shall operate and maintain the 
existing dust suppression methods for controlling dust from the coal 
handling and ash handling and storage facilities. Within ninety (90) 
days after promulgation of this paragraph, the owner or operator shall 
develop a dust control plan and submit the plan to the Regional 
Administrator. The owner or operator shall comply with the plan once 
the plan is submitted to the Regional Administrator. The owner or 
operator shall amend the plan as requested or needed. The plan shall 
include a description of the dust suppression methods for controlling 
dust from the coal handling and storage facilities, ash handling, 
storage, and landfills, and road sweeping activities. Within 18 months 
of promulgation of this paragraph each owner or operator shall not emit 
dust with opacity greater than 20 percent from any crusher, grinding 
mill, screening operation, belt conveyor, or truck loading or unloading 
operation.

[FR Doc. 2011-3998 Filed 2-24-11; 8:45 am]
BILLING CODE 6560-50-P