1 

6560.50 

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Part 49 

[EPA-R09-OAR-2010-0683; FRL-____] 

Supplemental Notice 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 Notice Requesting Comment 

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. 

APS offered to shut down Units 1 – 3 by 2014 and to install and 

operate Selective Catalytic Reduction (SCR) technology on Units 

4 and 5 by July 31, 2018. In today’s notice, EPA is 

supplementing our October 19, 2010 BART proposal with our 

technical evaluation of APS’ alternative proposal. We are 
2 

proposing to find that a different alternative emissions control 

strategy, based on APS’ proposal but requiring FCPP to comply 

with a NOx emission limit of 0.098 lb/MMBtu on Units 4 and 5 by 

July 31, 2018, instead of the 0.11 lb/MMBtu limit by December 

31, 2018 proposed by APS, would achieve more progress than EPA’s 

BART proposal towards achieving visibility improvements in the 

surrounding Class I areas. EPA is providing 30 days advance 

notice of our scheduled hearings and opening a comment period on 

this Supplemental Notice that extends from the publication date 

of this notice until May 2, 2011, which is 30 days after our 

last scheduled hearing, resulting in more than 60 days to 

comment on this Supplemental Notice. 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 today’s action, EPA is 

also extending the public comment period on the October 19, 2010 

BART proposal until May 2, 2011. 

DATES: Comments on this Supplemental Notice must be 

submitted no later than May 2, 2011. 

ADDRESSES: Submit comments, identified by docket number 

EPA-R09-OAR-2010-0683, by one of the following methods: 

Federal eRulemaking Portal: www.regulations.gov. Follow 

the on-line instructions. 
3 

 E-mail: r9air_fcppbart@epa.gov. 

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 

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 www.regulations.gov or e-mail. 

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 
4 

Notice. 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 Notice. 

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 Notice. 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 Notice. 

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 Diné, 

and data pertaining to our proposal at the Public Hearing. 

English-Diné 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 
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one of the methods provided in the Addresses Section of this 

Supplemental Notice. Verbatim transcripts, in English, of the 

hearings and written statements will be included in the 

rulemaking docket. 

The open houses and public hearings will be held at the 

following locations: 

Shiprock Chapter, Shiprock, New Mexico – March 29, 2011, 

Open House from 3:00 PM - 6:00 PM and Public Hearing from 7:00 

PM – 9:00 PM 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 9:00 AM – 1:00 PM 

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 

3:00 PM - 5:00 PM and Public Hearing from 6:00 PM – 9:00 PM 

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 3:00 PM 

- 5:00 PM and Public Hearing from 6:00 PM – 9:00 PM local time, 

Fort Lewis College, Center of Southwest Studies Lyceum Room, 

1000 Rim Drive, Durango, Colorado, 81301,(970) 247-7456. 
6 

The public hearings for the three evening events are 

scheduled to close at 9:00 PM, 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 Notice, you may submit comments, identified by 

docket number EPA-R09-OAR-2010-0683, by one of the following 

methods listed in the Addresses section. 

Docket: The index to the docket for this action is 

available electronically at 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, r9air_fcppbart@epa.gov. 

SUPPLEMENTARY INFORMATION: Throughout this document, “we”, 

“us”, and “our” refer to EPA. 
7 

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 
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D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation and 

Coordination with Indian Tribal Governments 

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks 

H. Executive Order 13211: Actions Concerning 

Regulations That Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and Advancement Act 

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and LowIncome 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 
9 

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. 
10 

 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 1000 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 Notice, finds that 

an alternative emission control strategy to shutdown 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, 
11 

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. 

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 

1963 1963 1964 1969 1970 

 

1

 EPA’s revisions to APS’ proposal is referred to throughout this notice as 

“the alternative emission control strategy”. 
12 

Began 

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/MMBtu) 

0.78 0.64 0.59 0.49 0.49 

PM 

Baseline 

emission 

rate 

(lb/MMBtu) 

0.025 0.029 0.029 0.014 0.010 

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 
13 

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. 

Table 2: Emission reductions achieved by closing Units 1 – 3, 

reproduced from APS’s November 24, 2010 submittal2

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 (acrefeet) 6,000 144,000 

CO2 (million tons) 5.2 125 

II. Legal Background for Proposing to Approve APS’ Alternative 

Emission Control Strategy as Achieving Better Progress Towards 

the National Visibility Goal 

 

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). 
14 

 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 SO2 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 SO2 emission limit, based on 

analysis of several different levels of SO2 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 SO2 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). 
15 

 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 
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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, 
17 

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 gapfilling 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 
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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 

[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 
19 

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 Notice, 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. 
20 

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 electricitygenerating 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 Notice 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 Notice, 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 
21 

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. 
22 

 

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. 

3

 The BART guidelines at 40 CFR Part 51 Appendix Y, require averaging 

times for EGUs be based on a 30-day rolling average. 
23 

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 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. 
24 

 

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 catalyst4. Although more layers 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. 

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 

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. 
25 

 

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 Notice 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 55, 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 

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. 
26 

 

(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 heatinput-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 

6

 This more stringent numerical NOx limit with the longer averaging time 

could reflect the capability of the catalyst 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 19, 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. 
27 

 

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 on 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. 
28 

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 
29 

 

regional haze9. 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. 

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 progress towards the 

Clean Air Act’s national visibility goal. 

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. 
30 

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. 
31 

 

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. 

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, 201211, and the alternative 

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 accommodate 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. 

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. 
32 

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). 

Table 4: EPA’s comparison of NOx emissions (tons) based on EPA 

BART proposal and the Alternative Emission Control Strategy 

 EPA BART 

proposal 

Alternative 

Emission 

Control 

Strategy 

Proposal 

with Lower 

Emissions 

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 

 

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. 
33 

Table 5: EPA’s comparison of PM emissions (tons) based on EPA 

BART proposal and the Alternative Emission Control Strategy 

 EPA BART 

proposal 

Alternative 

Emission 

Control 

Strategy 

Proposal 

with Lower 

Emissions 

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 

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 
34 

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 Notice, 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 Notice. 

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 
35 

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, 
36 

 

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. 

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 

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. 
37 

control strategy proposed in this Supplemental Notice 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. 
38 

 

APS provided EPA with the modeling files generated by 

AECOM14. EPA has evaluated those modeling files for this 

Supplemental Notice. APS’ modeling differs in some minor ways 

from the modeling used to support EPA’s October 19, 2010 BART 

proposal. 

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 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). 

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 Notice. 
39 

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). 

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 - 315

Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 

 

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. 
40 

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’s 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 
41 

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). 
42 

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’s Alternative Proposal Compared to 

Baseline Impacts from 2001 – 2003 using 1 ppb Ammonia Background 

Scenario as modeled by AECOM 

Class I Area Distance 

to FCPP 

Baseline 

Impact 

Improvement 

From EPA’s 

Proposal 

Improvement From 

APS’s proposal

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 

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 

 

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. 
43 

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 % 

Change in Delta 

dv 

42.93 24.5 59% 30.9 74% 

 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. 

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 
44 

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. 

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 

 

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. 

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”. 
45 

 

 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 APS20. 

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. 
46 

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 

Class I Area Distance 

to FCPP 

Baseline 

Impact 

Improvement 

From EPA’s 

Proposal 

Improvement From 

Alternative 

Emission 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 

 

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. 
47 

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 % 

Change in Delta 

dv 

42.94 23.65 57% 30.19 72% 

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. 

IV. EPA’s Supplemental Proposal 

In this Supplemental Notice, 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 
48 

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. 
49 

In this Supplemental Notice, 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 
50 

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 Notice 

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 

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 notice 

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. 
51 

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 Notice, 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). 
52 

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 
53 

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 Notice 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 

Notice to our proposed action on small entities, I certify that 

this supplemental notice 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 

(D.C. Cir. 1985) 

D. Unfunded Mandates Reform Act (UMRA)
54 

This Supplemental Notice to our 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 Notice 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 Notice will not impose direct 

compliance costs on the Navajo Nation, and will not preempt 

Navajo law. This Supplemental Notice to our proposed action 

will, if finalized, reduce the emissions of two pollutants from 

a single source, the Four Corners Power Plant. 
55 

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 Notice to our 

proposed action, 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 Notice to our 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. 
56 

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 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 Fed. Reg. 

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 
57 

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 Notice, 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 Notice, 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, 
58 

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 Notice is not subject to Executive Order 

13045 because it requires emissions reductions of two pollutants 

from a single stationary source. Because this Supplemental 
59 

Notice 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), Pub L. No. 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 
60 

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. 
61 

Particulate Matter Emissions - EPA Methods 1 though 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, 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 Notice, 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. 

AUTHORITY: 42 U.S.C. 7401 et seq. 

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: 

62 
63 

§ 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) except as indicated in paragraphs (i)(1) – (4). 

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 plantwide 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 plantwide 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. 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 
64 

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 
65 

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: 
66 

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 
67 

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 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 
68 

preceding 29 valid daily averages to determine the 30 day 

rolling average. The NOx monitoring system shall meet the data 

requirements of 40 CFR Part 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) 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 
69 

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.