The EPA Administrator, Lisa P. Jackson, signed the following final rule on 08/06/2012, and EPA is submitting it for publication in the Federal 

Register (FR). While we have taken steps to ensure the accuracy of this Internet version of the rule, it is not the official version of the rule for 

purposes of public comment. Please refer to the official version in a forthcoming FR publication, which will appear on the Government Printing 

Office's FDsys website (http://fdsys.gpo.gov/fdsys/search/home.action) and on Regulations.gov (http://www.regulations.gov) in Docket No. 

EPA-R09-OAR-2010-0683. Once the official version of this document is published in the FR, this version will be removed from the Internet and 

replaced with a link to the official version.

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 49

[EPA-R09-OAR-2010-0683; FRL-9703-2]

Source Specific Federal Implementation Plan for Implementing 

Best Available Retrofit Technology for Four Corners Power Plant: 

Navajo Nation

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final Rule.

SUMMARY: The Environmental Protection Agency (EPA) is 

promulgating a source-specific Federal Implementation Plan (FIP) 

requiring the Four Corners Power Plant (FCPP), a coal-fired 

power plant located on the Navajo Nation near Farmington, New 

Mexico, to achieve emissions reductions required by the Clean 

Air Act’s (CAA) Best Available Retrofit Technology (BART) 

provision. In this final action, EPA is requiring FCPP to reduce 

emissions of oxides of nitrogen (NOx) and is setting emission 

limits for particulate matter (PM) based on emission rates 

already achieved at FCPP. These pollutants contribute to 

visibility impairment in the numerous mandatory Class I Federal 

areas surrounding FCPP. For NOx emissions, EPA is requiring FCPP 

to meet a plant-wide emission limit of 0.11 lb/MMBtu on a 

rolling 30-day heat input-weighted average. This represents an 

80 percent reduction from the current NOx emission rate and is 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 2 of 153

expected to provide significant improvement in visibility. EPA 

is also finalizing an alternative emission control strategy that 

gives the owners of FCPP the option to close Units 1 – 3 and 

install controls on Units 4 and 5 to each meet an emission limit 

of 0.098 lb/MMBtu, based on a rolling average of 30 successive 

boiler operating days. For PM, EPA is requiring Units 4 and 5 at 

FCPP to meet an emission limit of 0.015 lb/MMBtu, and retaining 

the existing 20 percent opacity limit. These PM limits are 

achievable through the proper operation of the existing 

baghouses. EPA is also requiring FCPP to comply with a 20 

percent opacity limit on its coal and material handling 

operations.

EFFECTIVE DATE: This rule is effective on [insert date 60 days 

from date of publication in the Federal Register].

FOR FURTHER INFORMATION CONTACT: Anita Lee, EPA Region 9, (415) 

972-3958, r9air_fcppbart@epa.gov. 

SUPPLEMENTARY INFORMATION: EPA has established a docket for 

this action under Docket ID No. EPA-R09-OAR–2010–0683. The index 

to the docket for this action is available electronically at 

http://www.regulations.gov and in hard copy at EPA Region 9, 75 

Hawthorne Street, San Francisco, California. While 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 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 3 of 153

either location (e.g. Confidential Business Information (CBI)). 

To inspect the hard copy materials, please schedule an 

appointment during normal business hours with the contact listed 

in the FOR FURTHER INFORMATION CONTACT section. A reasonable fee 

may be charged for copies.

Throughout this document, “we”, “us”, and “our” refer to 

EPA.

Table of Contents

I. Background of the Final Rule

II. Summary of Final Federal Implementation Plan (FIP) 

Provisions

III. Analysis of Major Issues Raised by Commenters

A. Comments on Factor One - Cost of Controls

1. Comments on the Analysis of the Cost of SCR at FCPP

2. Comments on Top-Down Analysis Versus Incremental 

Cost Effectiveness

B. Comments on Factor Two - Economic, Energy, and Non-Air 

Quality Environmental Impacts

1. Comments on Economic Impacts

a. General Comments on Economic Impacts

b. Comments on EPA’s Economic Analysis

2. Comments on Energy and Non-Air Quality Environmental 

Impacts

C. Comments on Factor Three - Existing Controls at FCPP
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 4 of 153

D. Comments on Factor Four - Remaining Useful Life at FCPP

E. Comments on Factor Five - Anticipated Visibility 

Improvements

F. Comments on BART Determinations

1. Comments on the Proposed BART Determination for NOx

2. Comments on the Proposed BART Determination for PM

3. Comments on BART for SO2

4. Other Comments on BART

G. Comments on Arizona Public Service’s Alternative and 

EPA’s Supplemental Proposal

H. Other Comments

IV. Administrative Requirements

A. Executive Order 12866: Regulatory Planning and Review 

and Executive Order 13563: Improving Regulation and Regulatory 

Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination 

with Indian Tribal Governments

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 5 of 153

H. Executive Order 13211: Actions Concerning Regulations 

That Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations

K. Congressional Review Act

L. Petitions for Judicial Review

I. Background of the Final Rule 

FCPP is a privately owned and operated coal-fired power 

plant located on the Navajo Nation Indian Reservation near 

Farmington, New Mexico. Based on lease agreements signed in 

1960, FCPP was constructed and has been operating on real 

property held in trust by the Federal government for the Navajo 

Nation. The facility consists of five coal-fired electric 

utility steam generating units with a total capacity of 2060 

megawatts (MW). Units 1, 2, and 3 at FCPP are owned entirely by 

Arizona Public Service (APS) which serves as the facility 

operator, and are rated to 170 MW (Units 1 and 2) and 220 MW 

(Unit 3). Units 4 and 5 are each rated to a capacity of 750 MW, 

and are co-owned by six entities: Southern California Edison1 (48 

 

1 Arizona Public Service is currently seeking regulatory approvals to 

purchase Southern California Edison’s share of Units 4 and 5.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 6 of 153

percent), APS (15 percent), Public Service Company of New Mexico 

(13 percent), Salt River Project (SRP) (10 percent), El Paso 

Electric Company (7 percent), and Tucson Electric Power (7 

percent).

EPA’s proposed BART determination for FCPP, published on 

October 19, 2010, provided a thorough discussion of the 

statutory and regulatory framework for addressing visibility 

through application of BART for sources located in Indian 

country, and of the factual background for BART determinations 

at FCPP. 75 FR 64221. 

On February 25, 2011, as a result of additional information 

provided by stakeholders, EPA published a Supplemental Proposal. 

FR 76 10530. We briefly summarize the provisions of our Proposal 

and our Supplemental Proposal below. 

Part C Subpart II of the 1977 CAA establishes a visibility 

protection program that sets forth “as a national goal the 

prevention of any future, and the remedying of any existing, 

impairment of visibility in mandatory class I Federal areas 

which impairment results from manmade air pollution.” 42 U.S.C. 

7491A(a)(1). EPA promulgated regional haze regulations on April 

22, 1999. 64 FR 35765. Consistent with the statutory requirement 

in 42 U.S.C. 7491(b)(2)(a), EPA’s 1999 regional haze regulations 

include a provision requiring States to require certain major

stationary sources to procure, install and operate BART. This 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 7 of 153

provision covers sources “in existence on August 7, 1977, but 

which ha[ve] not been in operation for more than fifteen years 

as of such date” and which emit pollutants that are reasonably

anticipated to cause or contribute to any visibility impairment.

EPA has determined that FCPP is a BART-eligible source (75 FR 

64221).

In determining BART, States are required to take into

account five factors identified in the CAA and EPA’s 

regulations. 42 U.S.C. 7491(g)(2) and 40 CFR 51.308. Those

factors are:(1) the costs of compliance, (2) the energy and nonair quality environmental impacts of compliance, (3) any 

pollution control equipment in use or in existence at the

source, (4) the remaining useful life of the source, and (5) the 

degree of improvement in visibility which may reasonably be 

anticipated to result from the use of such technology. 40 CFR

51.308(e)(1)(ii)(A). EPA’s guidelines for evaluating BART are 

set forth in Appendix Y to 40 CFR Part 51.

In 1998, EPA promulgated the Tribal Authority Rule (TAR) 

relating to implementation of CAA programs in Indian country. 

See 40 CFR part 49; see also 59 FR 43956 (Aug. 25, 1994) 

(proposed rule); 63 FR 7254 (Feb. 12, 1998) (final rule); 

Arizona Public Service Company v. EPA, 211 F.3d 1280 (DC Cir. 

2000), cert. den., 532 U.S. 970 (2001) (upholding the TAR).
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 8 of 153

In the TAR, EPA determined that it has the discretionary

authority to promulgate “such federal implementation plan 

provisions as are necessary or appropriate to protect air

quality” consistent with CAA sections 301(a) and 301(d)(4) when 

a Tribe has not submitted or EPA has not approved a Tribal 

Implementation Plan (TIP). 40 CFR 49.11(a).

EPA has previously promulgated FIPs under the TAR to 

regulate air pollutants emitted from FCPP. In 1999, EPA proposed 

a FIP for FCPP. That FIP proposed to fill the regulatory gap 

that existed because New Mexico permits and State Implementation 

Plan (SIP) rules are not applicable or enforceable in the Navajo 

Nation, and the Tribe had not sought approval of a TIP covering 

the plant. 64 FR 48731 (Sept. 8, 1999).

Before EPA finalized the 1999 FIP, the operator of FCPP 

began negotiations to reduce SO2 emissions from FCPP by making 

upgrades to improve the efficiency of its SO2 scrubbers. The 

parties to the negotiations requested EPA to make those SO2

reductions enforceable through a source-specific FIP. Therefore,

EPA proposed a new FIP for FCPP in September 2006. 71 FR 53631

(Sept. 12, 2006). In the final FIP, EPA indicated that the new 

SO2 emissions limits were close to or the equivalent of the

emissions reductions that would have been required in a BART 

determination. 72 FR 25698 (May 7, 2007). The FIP also required 

FCPP to comply with a 20 percent opacity limit on both the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 9 of 153

combustion and fugitive dust emissions from material handling 

operations. 

APS, the operator of FCPP, and Sierra Club each filed 

Petitions seeking judicial review of EPA’s promulgation of the 

2007 FIP for FCPP on separate grounds. The Court of Appeals for 

the Tenth Circuit rejected both Petitions. The Court agreed with 

EPA’s request for a voluntary remand of a single narrow aspect 

of the 2007 FIP: the opacity limit for the fugitive dust for the 

material handling operations. Id. At 1131.

On October 19, 2010 (75 FR 64221) EPA proposed a second FIP 

under 40 CFR 49.11(a) finding it is necessary or appropriate to 

establish BART requirements for NOx and PM emissions from FCPP, 

and proposed specific NOx and PM limits as BART. For NOx, EPA 

proposed a plant-wide emission limit of 0.11 lb/MMBtu, 

representing an 80 percent reduction from current NOx emission 

rates, achievable by installing and operating SCR technology on 

Units 1-5. For PM, EPA proposed an emission limit of 0.012 

lb/MMBtu for Units 1 - 3 and 0.015 lb/MMBtu for Units 4 and 5 

achievable by installing and operating any of several equivalent 

controls on Units 1 - 3, and through proper operation of the 

existing baghouses on Units 4 and 5. EPA also proposed a 10 

percent opacity limit from Units 1 – 5 and a 20 percent opacity 

limit to apply to FCPP’s material handling operations to respond
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 10 of 153

to the voluntary remand EPA took on this issue from the 2007

FIP.

On November 24, 2010, APS, acting on behalf of FCPP's 

owners, submitted a letter to EPA offering an alternative to 

reduce visibility-impairing pollution. APS proposed to close 

Units 1 - 3 by 2014 and install and operate SCR on Units 4 and 5 

to each meet an emission limit of 0.11 lb/MMBtu by the end of 

2018. On February 25, 2011, we published a Supplemental Proposal 

(76 FR 10530) with a technical evaluation of APS’ alternative. 

Our Supplemental Proposal also provides a detailed summary of 

the legal background for proposing an alternative emission 

control strategy as achieving better progress towards the 

national visibility goal (76 FR 10530).

In our Supplemental Proposal, EPA proposed to allow APS the 

option to comply with the alternative emission control strategy 

in lieu of complying with our October 19, 2010, proposed BART 

determination. EPA’s alternative emission control strategy 

involved closure of Units 1 – 3 by 2014 and installation and 

operation of add-on post combustion controls on Units 4 and 5 to 

each meet a NOx emission limit of 0.098 lb/MMBtu by July 31, 

2018. EPA proposed that this alternative emission control 

strategy represents reasonable progress towards the national 

visibility goal, under CAA Section 169A(b)(2), because it would 

result in greater visibility improvement in surrounding Class I 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 11 of 153

areas at a lower cost than our October 19, 2010, BART proposal.

The proposal to require PM and opacity limits on Units 1 – 5, as 

well as 20 percent opacity limits for controlling dust from coal 

and ash handling and storage facilities, was unchanged.

II. Summary of Final FIP Provisions

EPA is finding today that it is necessary or appropriate to 

promulgate a source-specific FIP requiring FCPP to achieve 

emissions reductions required by the CAA’s BART provision. 

Specifically, EPA is requiring FCPP to meet new emissions limits 

for NOx and PM. These pollutants contribute to visibility 

impairment in the 16 mandatory Class I Federal areas surrounding 

FCPP. For NOx emissions, EPA is finalizing a BART determination 

as well as an optional alternative to BART. FCPP can choose 

which emissions control strategy to follow and must notify EPA 

of its choice by July 1, 2013. Our final BART determination 

requires FCPP to meet a plant-wide heat input-weighted emission 

limit of 0.11 lb/MMBtu on a rolling 30-calendar day average 

which represents an 80 percent reduction from current NOx

emission rates. This NOx limit is achievable by installing and 

operating add-on post-combustion controls on Units 1 - 5. 

Installation and operation of the new NOx controls on one 750 MW 

unit must be within 4 years of [insert date 60 days from date of 

publication in Federal Register]. NOx controls on the remaining 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 12 of 153

units must be installed and operated within 5 years of [insert 

date 60 days from date of publication in Federal Register].

Alternatively, FCPP may choose to comply with an 

alternative emission control strategy for NOx in lieu of 

complying with EPA’s final BART determination for NOx. This 

alternative emission control strategy requires permanent closure 

of Units 1 – 3 by January 1, 2014, and installation and 

operation of add-on post combustion controls on Units 4 and 5 to 

meet a NOx emission limit of 0.098 lb/MMBtu each, based on a 

rolling average of 30 successive boiler operating days, by July 

31, 2018.

For PM, EPA is requiring Units 4 and 5 to meet a BART

emission limit of 0.015 lb/MMBtu within 60 days after restart 

following the scheduled major outages for Units 4 and 5 in 2013 

and 2014. This emission limit is achievable through the proper 

operation of the existing baghouses. EPA is determining that it 

is not necessary or appropriate to finalize our proposed PM BART 

determination for Units 1 – 3 or our proposed opacity limit of 

10 percent on Units 1 – 5. FCPP must continue to meet the 

existing 20 percent opacity limit on Units 1 – 5. 

To address our voluntary remand of the material handling 

requirements from the 2007 FIP, EPA is finalizing our proposal 

to require FCPP to comply with a 20 percent opacity limit on its 

material handling operations, including coal handling.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 13 of 153

In our final rule, EPA has made several revisions to the 

proposed rule and Supplemental Proposal based on comments we 

received during the public comment period. These revisions 

include: revising the compliance date under BART from within 3 

to 5 years2 of the effective date of the final rule to within 4 

to 5 years3 of the effective date; revising the interim limits to 

only include an interim limit for one 750 MW unit rather than 

all units to match the revised compliance timeframes; adding 6

months to the notification dates to EPA on APS’s plans to 

implement BART or the BART Alternative; revising the averaging 

time for the NOx limit under the BART Alternative from a 30-day 

average to a rolling average of 30 successive boiler operating 

days; retaining the existing opacity limit of 20 percent instead 

of setting a new 10 percent opacity limit on Units 1 – 5; 

determining that it is not necessary or appropriate at this time 

to finalize a BART determination for PM for Units 1 – 3; and 

revising the effective date of the PM emission limit for Units 4 

and 5 to the next schedule major outage rather than following 

installation of new post-combustion NOx controls. We include the 

rationale for these revisions in our responses to comments. All 

 

2 We proposed to require phased installation of add-on NOx controls on at 

least 560 MW of generation within 3 years of the effective date of the final 

rule, on at least 1310 MW of generation within 4 years of the effective date, 

and plant-wide within 5 years of the effective date. 3 We are finalizing the rule to require phased installation of add-on NOx

controls on at least 750 MW of generation within 4 years of the effective 

date and on the remaining units within 5 years of the effective date.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 14 of 153

comments we received are included in the docket and EPA has 

summarized and responded to all comments in a separate Response 

to Comments (RTC) document that is also included in the docket 

for this final rulemaking. In this Federal Register notice, EPA 

is including a summary of the major comments we received and a

summary of our responses. 

III. Summary of Major Issues Raised by Commenters

Our October 19, 2010, proposal included a 60-day public 

comment period that ended on December 20, 2010. On November 12, 

2010, EPA published a notice of public hearings to be held in 

the Four Corners area on December 7 – 9, 2010 (75 FR 69374). On 

December 8, 2010, EPA published in the Federal Register a notice 

that EPA received an alternative proposal from APS and would be 

extending the public comment period to March 18, 2011, and 

postponing the previously scheduled public hearings in order to 

evaluate that alternative proposal (75 FR 76331). Notices of 

public hearings and rescheduled hearings were published in three 

newspapers near the Four Corners Power Plant4

. Our supplemental 

proposal on February 25, 2011, subsequently extended the public 

comment period until May 2, 2011, and announced four public 

 

4 Notices of scheduled public hearings were published in the Farmington 

Daily Times and the Durango Herald on November 3, 2010 and February 17, 2011, 

and the Navajo Times on November 4, 2010 and February 17, 2011. Notices of 

the extended public comment period and postponement of the December public 

hearings were published in the Farmington Daily Times and the Durango Herald

on November 24, 2010 and in the Navajo Times on December 2, 2010.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 15 of 153

hearings on the proposed BART determination and supplemental 

proposal in the Four Corners area on March 29, 30, and 31, 2011. 

In all, 90 oral testimonies were presented at the public 

hearings. 

We received nearly 13,000 written comments. Of these, over 

12,800 comments came from private citizens who submitted 

substantially similar comments. We received an additional 

110 unique written comments (not including duplicates, requests 

for extension of the public comment period, or requests for 

additional hearings). We do not consider or address letters or 

comments unrelated to the rulemaking in this notice or in our 

response to comments document. The unique comments can be broken 

down by general type as follows: 78 from private citizens, 

eight from environmental advocacy groups, four from the owners 

of FCPP, five from state/local government entities, four from 

public interest advocacy groups, two from tribes, four from 

utility industry associations, three from federal agencies, one 

from a U.S. Senator, and one from the operator of the Navajo 

Mine.

A. Comments on Factor One - Cost of Controls

We received a number of comments on our approach for 

estimating the cost of SCR at FCCP, the incremental cost 

effectiveness of controls, and on our top-down approach for 

evaluating controls.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 16 of 153

1. Comments on the Analysis of the Cost of SCR at FCPP

Comment: Some of the owners of FCPP and a utility industry 

association stated that in analyzing the cost of SCR at FCPP, 

EPA improperly reworked and reduced the SCR cost estimates 

submitted for FCPP by eliminating line item costs that are not 

explicitly included in the EPA Control Cost Manual (citing 75 FR 

64227). Commenters noted that APS’ estimate was prepared by B&V, 

an engineering firm with extensive experience with the 

installation and operation of pollution control equipment and 

that the prices used in the cost analysis were based on quotes 

from equipment vendors that reflected current pricing. 

Response: EPA disagrees with the comment that EPA 

improperly reworked and reduced the SCR cost estimates. EPA used 

a hybrid approach for our cost analysis that relied primarily on 

the highest of several cost estimates provided by APS, but also 

followed the BART Guidelines that state “[i]n order to maintain 

and improve consistency, cost estimates should be based on the 

OAQPS Control Cost Manual, where possible”,5 to determine whether 

APS included cost estimates for services or equipment associated 

with SCR that were either not needed (e.g., mitigation for 

increased sulfuric acid emissions or catalyst disposal), or not 

allowed under the EPA Control Cost Manual (e.g., legal fees). 

 

5 The OAQPS Control Cost Manual is now called the EPA Control Cost Manual. 

The EPA Control Cost Manual is available from the following website:

http://www.epa.gov/ttncatc1/products.html#cccinfo
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 17 of 153

Our cost analysis relied primarily on the highest cost 

estimates submitted by APS. EPA accepted all site-specific costs 

provided by APS for cost categories (e.g., purchased equipment, 

installation) that are typically included in a cost estimate 

conducted in accordance with the EPA Control Cost Manual, and 

only excluded line item costs that are not explicitly included 

in the EPA Control Cost Manual or in a limited number of cases 

where EPA determined alternative costs were more appropriate 

(e.g., costs of catalysts, interest rates). We note that EPA’s 

cost estimate presented in the Technical Support Document (TSD)6

($718 million total for Units 1 – 5) is only 18 percent lower 

than the highest B&V cost estimate and less than 0.6 percent

lower than the lowest and most recent B&V cost estimate.

Our detailed, line-by-line analysis7 was included in the 

docket for our proposed rulemaking and provided an explanation 

for why we retained, modified, or rejected each line item in the 

SCR cost estimate for each of the five units at FCPP. 

Comment: One of the owners of FCPP asserted that EPA’s 

estimate of the average cost effectiveness of SCR at FCPP is 

significantly higher than the level ($1,600 per ton of NOx

removed) that EPA determined was not cost effective in the 2005 

 

6 See “TSD Proposal – Technical Support Document 10-6-10”, Document 

No. EPA-R09-OAR-2010-0683-0002. 7 See “TSD ref [40] Four Corners SCR Cost Analysis (EPA) 8-26-10”, Document 

No. EPA-R09-OAR-2010-0683-0033.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 18 of 153

BART rules for presumptive BART limits. The commenter asserted 

that there is no basis for EPA to depart from its own rules by 

concluding that SCR is BART for FCPP when this technology is 

many times more expensive than the costs EPA rejected as 

presumptive BART in the 2005 BART rules. The commenter noted 

that its cost analysis estimated that the average cost 

effectiveness of combustion controls for the five units at FCPP 

would range from $524 to $1,735 per ton of NOx removed, while the 

average cost effectiveness of SCR would range from $4,215 to 

$5,283 per ton. The commenter also noted that EPA’s estimate of 

average cost effectiveness for SCR at FCPP ranged from $2,515 to 

$3,163 per ton. The commenter stated that, at the low end, only 

the estimate of the average cost effectiveness of combustion 

controls is in line with EPA’s estimates of cost-effective 

controls for presumptive BART limits, while the estimate of 

average cost effectiveness of SCR is significantly higher. 

Response: EPA disagrees with this comment. Although the 

commenters argue that the BART guidelines established a 

threshold for cost effectiveness against which future BART 

determinations must be compared, the BART Guidelines did not 

establish a cost effectiveness threshold for all BART 

determinations. In developing the presumptive NOx limits for BART 

in 2005, EPA did not set the cost effectiveness values estimated 

for combustion controls as the threshold for determining whether 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 19 of 153

a given control technology was or was not cost effective. The 

BART Guidelines do not set a numerical definition for “cost 

effective”, and the analysis of presumptive limits uses cost 

effectiveness as a means to broadly compare control 

technologies, not as threshold for rejecting controls for an 

individual unit or facility that exceed the average cost 

effectiveness of combustion controls.

Additionally, a comparison of the average cost 

effectiveness estimates in the 2005 BART guidelines against 

EPA’s cost effectiveness estimates in 2010 for FCPP is not an 

“apples to apples” comparison. The technical support 

documentation for the 2005 BART guidelines indicate that cost 

effectiveness of controls was not determined based on sitespecific cost estimates developed for each BART-eligible 

facility; rather, cost estimates for existing facilities were 

determined using assumptions for capital and annual costs per 

kilowatt (kW)8 or kilowatt-hour (kW-hr), and then scaled 

according to boiler size at the existing facilities. The 

supporting information for the 2005 BART Guidelines estimated 

SCR costs9 for FCPP Units 4 and 5 that are comparable to SCR cost 

 

8 In the 2005 BART presumptive limit analysis, EPA estimated capital costs 

at all facilities nationwide assuming that SCR costs were $100/kW, and then 

scaling by the size of the facility (kW). 9 The 2005 BART guidelines estimated SCR capital costs at FCPP to be $64 

million and total annual costs to be $11 million. Cost effectiveness 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 20 of 153

estimates generated by the National Park Service (NPS) in 2009 

using the EPA Control Cost Manual10. The same commenters have 

previously dismissed the NPS SCR cost estimates based on the EPA 

Control Cost Manual because it does not include site-specific 

costs.11 In short, the commenter’s recommendation to use 

generalized cost estimates from the 2005 BART Guidelines as a 

bright line threshold for comparison with site-specific 2010 

cost estimates is inconsistent with its own criticisms of the 

EPA Control Cost Manual. 

In determining that a different level of control than the 

presumptive limit was warranted as BART for FCPP, EPA evaluated 

the five statutory factors in our assessment for FCPP. This 

evaluation was detailed in the Technical Support Document for 

our proposed BART determination and included an analysis of cost 

effectiveness, energy and non-air quality impacts of controls, 

existing controls at the facility, the remaining useful life of 

the facility, and the visibility improvement reasonably 

 

calculations rely on total annual costs and annual NOx reductions from the 

control technology. 10 In the ANPRM, in addition to reporting APS’ cost estimates and EPA’s 

revisions to APS’ cost estimates, for reference, EPA also reported cost 

estimates developed by NPS using the EPA Control Cost Manual and provided to 

EPA during consultations with the FLMs prior to our ANPRM. NPS estimated SCR 

capital costs to be $53 million and total annual costs to be $10 million. See 

Table 9 in the October 2010 TSD for the proposed BART determination for FCPP. 

In its comments on the ANPR, NPS revised its cost estimates for SCR on Units 

4 and 5 to $114 million (capital cost) and $18 million (total annual cost) –

see Table 12 in the TSD for the proposed BART determination. 11 APS and other entities provided comments to EPA on the NPS cost 

estimates reported in the ANPRM, see document titled “Comments on ANPRM 09 

0598 APS Comments and Exhibits” document ID number EPA-R09-OAR-2009-0598-

0195. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 21 of 153

anticipated to result from controls. Therefore, EPA has not 

improperly disregarded the BART guidelines in our analysis for 

FCPP.

Comment: A number of commenters stated that EPA’s BART 

analysis for FCPP was inconsistent with its own regulations in 

that it failed to consider control costs as a function of 

visibility improvement. These commenters typically stated that

EPA’s BART determination for FCPP must consider the cost 

effectiveness of control technology options in terms of dollars 

per deciview-improved. 

Response: The BART Guidelines require that cost 

effectiveness be calculated in terms of annualized dollars per

ton of pollutant removed, or $/ton.12 The commenters are correct 

in that the BART Guidelines list the $/deciview ratio as an 

additional cost effectiveness metric that can be employed along 

with $/ton for use in a BART evaluation. However, the use of 

this metric further implies that additional thresholds or 

notions of acceptability, separate from the $/ton metric, would 

need to be developed for BART determinations. We have not used 

this metric for BART purposes at FCPP because (1) it is 

unnecessary in judging the cost effectiveness of BART, (2) it 

complicates the BART analysis, and (3) it is difficult to judge. 

 

12
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 22 of 153

In particular, the $/deciview metric has not been widely used 

and is not well-understood as a comparative tool. In our 

experience, $/deciview values tend to be very large because the 

metric is based on impacts at one Class I area on one day and 

does not take into account the number of affected Class I areas 

or the number of days of improvement that result from 

controlling emissions. In addition, the use of the $/deciview 

suggests a level of precision in the CALPUFF model that may not 

be warranted. As a result, the $/deciview can be misleading. We 

conclude that it is sufficient to analyze the cost effectiveness 

of potential BART controls for FCPP using $/ton, in conjunction 

with an assessment of the modeled visibility benefits of the 

BART control. 

EPA considered cost of controls, including the total 

capital costs, annual costs, and $/ton of NOx pollution reduced

in our proposed BART determination. Additionally, in response to 

comments received on our proposal, EPA included calculations and 

consideration of incremental cost effectiveness (see Section 3.2 

of the Response to Comments document in the docket for this 

final rulemaking). EPA considered visibility impacts, including 

the degree of impairment, the number of Class I areas affected 

by FCPP, the deciview improvement resulting from controls, and 

the percent change in improvement. EPA determined that these 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 23 of 153

metrics are sufficient in completing our five-factor analysis 

for FCPP. 

Comment: One commenter stated that BART must be determined 

in the context of reasonable progress rather than in isolation 

and that the cost effectiveness metric used by EPA (i.e., $/ton 

of NOx reduced) does not satisfy the statutory requirement to 

consider the cost to comply with the Regional Haze program 

because it does not include compliance costs related to 

requirements for reasonable progress. 

Response: Congress identified BART as a key measure for 

ensuring reasonable progress. We disagree that BART must be 

determined in the context of reasonable progress. If anything, 

reasonable progress depends on BART. Because the Class I areas 

affected by emissions from FCPP are not achieving the glidepath, 

it is important that states, tribes, and EPA require reasonable 

measures to be implemented to ensure that progress is made 

towards the national visibility goal. 

The BART guidelines specify that the cost of controls be 

estimated by identifying the emission units being controlled, 

defining the design parameters for emission controls, and 

developing a cost estimate based on those design parameters 

using the EPA Control Cost Manual while taking into account any 

site-specific design or other conditions that affect the cost of 

a particular BART control option. The BART guidelines do not 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 24 of 153

require the costs of compliance under BART to consider costs 

that may be associated with reasonable progress. 

Comment: The Navajo Nation commented that EPA should 

analyze the affordability of controls under the supplemental 

proposal by performing a detailed analysis, rather than an 

approximation, of the cost of compliance for installing SCR on 

Units 4 and 5, including a consideration of the impacts of 

closing Units 1 – 3.

Response: EPA disagrees that we should perform a detailed 

cost analysis of the alternative emission control strategy put 

forth in the Supplemental Proposal. The Regional Haze Rule, in 

assessing an alternative measure in lieu of BART (40 CFR 

51.308(e)(2)) requires several elements in the alternative plan 

(e.g., a demonstration that the alternative will achieve greater 

reasonable progress than BART, and that reductions are surplus

to the baseline date of the SIP), but does not require an 

analysis of the cost of the alternative plan. 

Similarly, an affordability analysis of the alternative 

emission control strategy is not required under the Regional 

Haze Rule; however, at the request of the Navajo Nation,

pursuant to EPA’s customary practice of engaging in extensive 

and meaningful consultation with tribes, EPA commissioned a 

study to estimate potential adverse impacts to the Navajo Nation 

of APS’s option to close Units 1 – 3 and will provide the report 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 25 of 153

to the Navajo Nation by letter as a follow-up to our 

consultation.

2. Comments on Top-Down Analysis Versus Incremental Cost 

Effectiveness

Comment: A number of commenters note that EPA’s proposed 

BART analysis was inconsistent with its own regulations in that 

it used a top-down analytic approach and failed to conduct an 

incremental cost evaluation. Commenters indicated that in using 

the top-down analysis, EPA failed to carry out the five-factor 

analysis for each of the technically feasible retrofit 

technologies as required by the BART Guidelines (citing 40 CFR 

part 51, Appendix Y, section I.F.2.c), including combustion 

control technology which the BART Guidelines identify as 

presumptive BART. 

Response: EPA disagrees with these comments. In the 

preamble to the final BART guidelines, EPA discusses two options 

presented in the 2001 proposal and 2004 reproposal of the 

guidelines for evaluating ranked control technology options (See 

discussion at 70 FR 39130). Under the first option, States would 

use a sequential process for conducting the analysis, beginning 

with a complete evaluation of the most stringent control option. 

The process described is a top-down approach analogous to the 

analysis we used in our proposed BART determination for FCPP. If 

the analysis shows no outstanding issues regarding cost or 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 26 of 153

energy and non-air quality environmental impacts, the analysis 

is concluded and the top level of technically feasible controls 

is identified as the “best system of continuous emission 

reduction”. Therefore, in conducting our BART determination for 

FCPP, EPA’s top-down approach for assessing the five factors was 

consistent with the discretion allowed under the BART 

guidelines. EPA additionally notes that the TSD for our proposed 

rulemaking included analyses of the costs, non-air impacts, and 

visibility improvements associated with combustion controls at 

FCPP, but that there is no requirement for a five-factor 

analysis on all potentially available control options if the top 

down approach is used and the top level of technically feasible 

controls is selected (70 FR 39130).

Comment: One of the owners of FCPP asserted that the BART 

rules require an incremental cost analysis and provided an 

analysis comparing the costs of combustion controls to the costs 

of SCR. According to the commenter’s analysis, the incremental 

cost effectiveness of moving from combustion controls to SCR 

ranges from $6,553 to $8,605 per ton of NOx reduced for the five 

units at FCPP. This commenter and another FCPP owner asserted 

that this “extraordinarily high” incremental cost highlights the 

fact that combustion controls, not SCR, satisfy the cost 

effectiveness test applied by EPA in adopting the presumptive 

BART limits in the BART rules.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 27 of 153

Response: EPA agrees that the BART Guidelines recommend 

consideration of both average and incremental cost 

effectiveness, however, EPA disagrees with the commenter that 

the incremental cost effectiveness should be a comparison 

between combustion controls and SCR for this particular 

facility. As discussed at length in the TSD for our proposed 

BART determination for FCPP, Region 9 has determined that 

combustion controls (burner modifications and overfire air, 

including ROFA) will not be effective at significantly reducing 

emissions at Four Corners without potential operational 

difficulties due to inherent design and physical limitations of 

the boilers. Therefore, in estimating incremental cost, it is 

inappropriate and misleading to include combustion controls in 

the analysis for this particular facility. To respond to this 

comment, EPA conducted an incremental cost effectiveness 

analysis and included it in our docket for this final 

rulemaking.13 Based on our incremental cost analysis, EPA has 

determined that the incremental cost of SCR compared to 

selective non-catalytic reduction (SNCR), the next most 

stringent option ($2,500 per ton to $3,300 per ton), is 

reasonable and does not support the commenter’s conclusion that 

SCR is not BART for FCPP.

 

13 See “Incremental cost.xlsx” in the docket for this final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 28 of 153

EPA estimated the total capital cost of BART for NOx to be 

$718 million and total annual costs (annualized capital costs 

plus additional operating costs) to be $93 million per year. 

This final BART determination is expected to reduce emissions of 

NOx by 80 percent, from 43,000 tons per year to 8,500 tons per 

year, resulting in a facility-wide average cost effectiveness of 

about $2,700 per ton of NOx removed. EPA anticipates that this 

investment will reduce the visibility impairment caused by FCPP 

by an average of 57 percent at 16 Class I areas within 300 km of 

the facility. A detailed summary of the cost and visibility 

benefits were provided in the Technical Support Document for the 

proposed rulemaking. As discussed in our Supplemental Proposal, 

although APS did not provide a cost estimate for the BART 

Alternative and the RHR does not require an evaluation of costs 

associated with a BART Alternative, if APS chooses to implement 

the Alternative, EPA anticipates those costs to be approximately 

39 percent lower than the cost of BART. The BART Alternative is 

expected to reduce emissions of NOx by 87 percent, from 43,000 

tons per year to 5,600 tons per year, resulting in a facilitywide average cost effectiveness of roughly $1,600 per ton of NOx

removed.14 EPA anticipates that implementation of the BART 

 

14 EPA estimates facility-wide average cost effectiveness of the BART 

Alternative to be lower than BART because under the BART Alternative, Units 1 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 29 of 153

Alternative will reduce visibility impairment caused by FCPP by 

an average of 72 percent at 16 Class I areas within 300 km of 

the facility. 

B. Comments on Factor Two - Economic, Energy, and Non-Air 

Quality Environmental Impacts

We received a number of comments on the economic impacts 

and on the energy and non-air quality environmental impacts.

1. Comments on Economic Impacts

a. General Comments on Economic Impacts

Comment: Several commenters stated that EPA’s analysis of 

historical and expected costs of electricity from FCPP neglect 

to include public health costs related to air pollution and the 

negative impacts to tourism resulting from loss of visibility. 

The commenters concluded that the cost effectiveness metric used 

to determine BART must account for health costs related to poor 

air quality. 

Response: EPA disagrees with the comment that the cost 

effectiveness of BART must account for public health costs 

associated with poor air quality. Neither Section 169A of the 

CAA, nor the BART Guidelines, require the BART analysis to 

 

– 3 can be closed instead of retrofitted with new air pollution controls. On 

a per unit basis, the cost effectiveness of Units 4 and 5 is not expected to 

differ between BART or the BART Alternative. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 30 of 153

include or quantify benefits to health or tourism. Moreover, an 

analysis of health and tourism benefits is unlikely to alter the 

outcome of our BART determination, which already requires the 

most stringent control technology available for NOx.

Comment: The Navajo Nation, one federal agency, and two of 

the owners of FCPP stated that EPA must consider the collateral 

adverse effects on the Navajo Nation and the surrounding 

communities of its BART determination. The commenters provided 

background on the substantial interest that the Navajo Nation 

has in the continued operation of FCPP. The commenters indicated 

that FCPP and its coal supplier, the Navajo Mine operated by BHP 

Billiton (BHP), together provide income to the Navajo Nation 

that contributes substantially to the Nation’s economic 

viability and its sustainability as an independent sovereign 

nation. The commenters added that this resource extraction-based 

economy is the result of a conscious effort of the United States 

dating from the 1950s to develop the Nation’s coal resources.

According to the commenter, if FCPP and the Navajo Mine were to 

close as the result of the imposition of cost-prohibitive 

emission controls, the resulting revenue and job losses would be 

significant for the Navajo Nation.

Response: EPA agrees with commenters that the operation of 

FCPP and the Navajo Mine contribute significantly to the economy 

of the Navajo Nation and the Four Corners Region. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 31 of 153

It is not EPA’s intention to cause FCPP to shut down, nor 

is it within our regulatory authority under the Regional Haze 

Rule to require shutdown or redesign of the source as BART. As 

expressed in comments from the Navajo Nation to our Advanced 

Notice of Proposed Rulemaking,15 EPA understands that the Navajo 

Nation’s primary concern regarding the BART determination is the 

potential for FCPP closure. Therefore, as discussed in our 

proposed BART determination, EPA conducted an affordability 

analysis not typically included in a BART five-factor analysis

in order to assess whether requiring SCR on all five units at 

FCPP would cause the power plant to close. 

The model was designed to determine which future 

alternative results in lower power costs: a) power produced at 

FCPP after installation of SCR or, b) replacing the power from 

FCPP with the appropriate amount of wholesale power purchases. 

As discussed in the TSD for our proposed BART determination, the 

model results suggested that even if the owners of FCPP 

installed and operated SCR on all five units, the facility could 

still produce power at a lower cost than the cost to purchase 

replacement wholesale power on the open market. Thus, EPA 

concluded in our proposed BART determination that requiring SCR 

as BART on all five units would not likely result in plant 

 

15 Comment letter from President Joe Shirley, Jr. dated March 1, 2010 in 

the docket for the ANPR: EPA-R09-OAR-2009-0583-0209.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 32 of 153

closure. No information was provided by the commenter to change 

this conclusion in the proposal. 

Comment: The Navajo Nation asserted that EPA failed to 

consult with the Nation prior to publishing the supplemental 

proposal and failed in its trust responsibility to consider the 

economic impacts of closing Units 1 - 3. A federal agency 

commenter noted that EPA’s current analysis focuses primarily on 

increased costs to rate payers and the companies’ profitability, 

and stated that the analysis needs to incorporate the loss in 

revenue, jobs, and royalties resulting from the closure of Units 

1 - 3 under the supplemental proposal. 

Response: A timeline of correspondence and consultation 

with the Navajo Nation and other tribes for EPA actions on FCPP 

and Navajo Generating Station is included in the docket for the 

final rulemaking.16 EPA notes that the Regional Administrator of 

EPA Region 9 called President Joe Shirley on February 9, 2011 to 

inform him of EPA’s Supplemental Proposal. However, governmentto-government consultation with the Navajo Nation on FCPP did 

not occur until May 19, 2011, with additional consultation 

occurring on June 13, 2012, prior to issuing our final 

rulemaking. The Navajo Nation raised concerns about the 

 

16 See document titled: “Timeline of all tribal consultations on BART.docx” 

in the docket for this final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 33 of 153

potential adverse impacts of the BART Alternative and requested 

that EPA conduct an analysis to estimate those impacts. 

Although the Regional Haze Rule does not require a cost 

analysis of a BART alternative, at the request of the Navajo 

Nation, as part of EPA’s customary practice of engaging in 

extensive and meaningful consultation with tribes and tribal 

authorities with regard to relevant Agency actions, EPA did 

commission an analysis to estimate potential adverse impacts on 

the Navajo Nation, with respect to coal- and power plant-related 

revenues, of the optional BART Alternative to retire Units 1 –

3. The report will be provided to President Shelly by letter as 

a follow-up to our consultation with the Navajo Nation. 

Comment: One owner of FCPP stated that EPA’s proposal to 

require SCR at FCPP presents significant challenges and risks 

with regard to its resource planning. The commenter pointed out 

that implementation of the BART proposal would require the

commenter to make a significant capital investment in FCPP, 

which could only be recovered through long-term operation of the 

plant. According to the commenter, this would have the effect of 

locking FCPP into the commenter’s generation portfolio for a 

considerable period or risk stranding those investments. 

Response: EPA appreciates the perspectives shared in this 

comment, but we disagree that our five-factor BART analysis

should consider the potential loss of an owner’s flexibility to 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 34 of 153

respond to possible future economic or regulatory scenarios. EPA 

cannot give substantial consideration in our BART analysis to 

external factors that are of uncertain magnitude and that may or 

may not occur. EPA further notes that the RHR allows for the 

development of BART alternatives that achieve greater reasonable 

progress than BART and EPA appreciates the fact that the owners 

of FCPP put forth an alternative that gives them more 

flexibility and results in greater emission reductions at FCPP.

b. Comments on EPA’s Economic Analysis

Comment: One public interest advocacy group concurred with 

the EPA’s analysis that the potential increase to APS rate

payers as a result of SCR is expected to be less than 5 percent, 

as described in the TSD. The commenter stated that EPA’s

estimates are reasonable and that the average increase in the 

cost of generation at FCPP as a result of SCR implementation 

would be 22 percent, or $0.0074 per kWh, as stated in the TSD.

One of the owners of FCPP stated that installation of BART 

controls would increase its average residential customer monthly

bills by $5.10 (3.8 percent) and larger industrial customer

monthly bills by $17,400 (6.4 percent). The commenter also 

indicated that installing SCR and baghouses on Units 1 - 3 would 

increase the cost of electricity production on a $/MWh basis by 

more than 50 percent which, in conjunction with other market and 

regulatory uncertainties, may make the units uneconomical. The 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 35 of 153

commenter also raised concerns related to the economic viability 

of Units 4 and 5 if SCR were installed on those units. 

Another of the owners of FCPP, who also owns part of San 

Juan Generating Station and Navajo Generating Station, indicated 

that if SCR was required on all three power plants, its 

customers would face a rate increase of 4 to 6 percent, which 

would be significant because the local economy is fragile and 

has endured an 8 percent rate increase (not adjusted for 

inflation) since 1992. 

Response: EPA agrees with the first commenter that based 

upon our analysis the potential increase to APS rate payers as a 

result of SCR is expected to be less than 5 percent. EPA cannot 

assess the estimated residential and industrial rate increase

claimed by the second and third commenters with our economic 

analysis because the commenters did not provide information for 

us to evaluate their conclusions. However, EPA notes that the 

installation of baghouses on Units 1 - 3 is no longer relevant 

because EPA has determined that it is not necessary or 

appropriate at this time to set new PM limits for Units 1 – 3. 

This is because the Mercury and Air Toxics Standard (MATS) rule, 

which sets a filterable PM limit of 0.03 lb/MMBtu, is now final17

and EPA is finalizing in this rulemaking the option to allow APS 

 

17 See 77 FR 9304, February 16, 2012.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 36 of 153

to comply with either BART or the BART alternative, which 

involves closure of Units 1 - 3.

Comment: One of the owners of FCPP expressed concern that 

EPA’s analysis focuses on the effects on APS and Southern 

California Edison ratepayers, and not on the other owners of 

FCPP. This commenter’s specific concerns include that the use of 

a “return on rate”-based methodology would not apply to

organizations of the commenter’s type (a publicly owned utility) 

because it is not an investor-owned utility. In addition, the

commenter stated that the EPA analysis did not attempt to 

determine the impact of different assumptions, such as an 

uncertainty with the future price of coal, on the conclusions of 

the analysis. Specifically, the “small difference” that EPA 

estimates between FCPP with SCR installed and the cost of 

purchasing power to replace FCPP generation suggests that a 

small change in an underlying assumption (return on rate, coal 

price, carbon pricing, etc.) could result in model results that 

show SCR to be a higher cost option than purchasing power. The 

commenter also raised the concern that EPA’s analysis did not 

examine different “payback periods,” but instead relied on a 

payback period of 25 years, which may be inappropriate because 

the useful life of the plant is far from certain. The commenter 

said that EPA should recognize that there is a real risk that 

one or more owners may decide not to invest in SCR, which would
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 37 of 153

force the shutdown of FCPP unless another owner could be found

in a timely manner. The commenter also said that shutdown of 

FCPP would have significant adverse consequences on the Navajo 

Nation. 

Response: The commenter is correct that EPA calculated 

rate impacts for only two of the four investor-owned utilities 

that own FCPP and excluded others, including an owner that 

operates as a publicly owned utility. The analysis estimating 

the increase in electricity generation costs is applicable to 

all owners of FCPP, but the rate impact analysis provided in the 

model was not intended to capture the rate impacts of all 

owners. APS and Southern California Edison (SCE) were selected 

because their combined ownership shares account for nearly 75

percent of the plant’s output. In addition to our expectation 

that the utilities with the largest ownership share in FCPP 

would generally experience greater ratepayer impacts from 

capital expenditure projects like SCR installation, we also 

assumed that ratepayers of investor-owned utilities would likely 

experience larger impacts than public power customers due to the 

fundamental difference between their respective approaches to 

setting rates. Specifically, rates for public power utilities, 

in contrast to investor-owned utilities, do not include recovery 

for a margin above cost allowed as part of a regulated rate of 

return. Thus, all other variables being equal, one would expect 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 38 of 153

the same capital investment to result in a larger rate impact 

for customers of investor-owned utilities than for customers of 

public power entities. Therefore, EPA continues to believe that 

our analysis of ratepayer impacts for only APS and SCE are 

appropriately conservative to demonstrate worst-case impacts to 

ratepayers of all six owners.

EPA agrees with the commenter that there are many companyspecific factors and a wide range of assumptions that would 

affect a given owner’s decision to make further substantial 

investments (such as SCR) at FCPP. Although many of those 

factors were outside the focus of the modeling because they were 

either unrelated to BART or were related to regulatory 

uncertainties in the future, we included a qualitative 

discussion in Appendix B to the TSD regarding decision variables 

that EPA assumed each owner must consider before making capital 

expenditures. Additionally, EPA notes that the use of low, 

medium and high future projected prices for the Palo Verde Index 

in Appendix B to the TSD for the proposed rulemaking represents 

a sensitivity analysis for the market comparison. 

With respect to the comment on the “payback period”, the 

economic analysis for the proposed BART determination did not 

identify “payback periods”. Rather, the commenter appears to be 

referring to the 25-year period used in the discounted cash flow 

model. EPA does not disagree with the commenter’s stated concern 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 39 of 153

that a shorter plant life, and thus shorter discounting periods, 

would yield different economic results. However, EPA disagrees 

with commenters that a shorter useful life should be considered 

in the economic analysis because there is no enforceable 

obligation on APS to cease operations on a given (earlier) date.

2. Comments on Energy and Non-Air Quality Environmental 

Impacts

Comment: One private citizen stated that no consideration 

was given to the effect of removing FCPP generation from the 

grid. According to the commenter, the events of February 2, 

2011, show there are times when gas-fired generation cannot 

replace coal-fired generation because there is not enough gas 

transportation capacity.

Response: EPA disagrees with the commenter that we should 

consider the effect of removing FCPP generation from the grid. 

As stated elsewhere, it is not EPA’s intention, nor is it within 

our regulatory authority, to require closure or require a 

redefinition of the source, in order to comply with the BART 

requirement of the Regional Haze Rule. Furthermore, the owners 

of FCPP did not provide evidence that the installation of SCR 

would cause FCPP to close.

EPA also notes that APS proposed to purchase the shares of 

Units 4 and 5 currently owned by Southern California Edison in 

order to close Units 1 – 3 (of which APS is sole owner) and 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 40 of 153

install SCR on Units 4 and 5 as an alternative to BART. APS has 

received approval from the Arizona Corporation Commission and

the California Public Utilities Commission to purchase Southern 

California Edison’s share of Units 4 and 5. APS is also seeking 

approval from the Federal Energy Regulatory Commission to 

implement its proposal.18 Decisions on investing in pollution 

controls or shutting down units are made by the owners in 

conjunction with their oversight boards or public utility 

commissions. These oversight bodies are also responsible for 

assuring the adequacy of electrical generating capacity, whether 

from coal, gas or nuclear fuels or renewable sources. 

Comment: Thirty-seven private citizens commented that FCPP 

causes significant threats to public health due to its effects 

on air quality. In addition, a number of environmental and 

public interest advocacy groups provided comments on health and 

ecosystem impacts of the pollutants emitted by FCPP. 

Regarding health impacts, the commenter noted that the same 

pollutants that contribute to visibility impairment also harm 

public health – the fine particulates that cause regional haze

can cause decreased lung function, aggravate asthma, and result 

in premature death in people with heart or lung disease. The 

 

18 On March 22, 2012, the California Public Utilities Commission (PUC) 

approved the sale of SCE’s ownership share in FCPP to APS. On April 18, 2012, 

the Arizona Corporation Commission voted to allow APS to purchase SCE’s 

ownership share in FCPP.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 41 of 153

commenter added that NOx and volatile organic compounds (VOCs)

can also be precursors to ground-level ozone, which is 

associated with respiratory diseases, asthma attacks, and 

decreased lung function. According to the commenter, ozone 

concentrations in parks in the Four Corners region approach the

current health standards, and likely violate anticipated lower 

standards.

The same commenter also contended that consideration of 

non-air quality impacts extends to impacts on wildlife and

habitat as well as natural and cultural heritage. According to 

the commenter, haze-causing emissions also harm terrestrial and 

aquatic plants and animals, soil health, and water bodies by 

contributing to acid rain, ozone formation, and nitrogen 

deposition.

With these health and environmental considerations in mind, 

in addition to visibility and economic considerations discussed 

in other sections of this document, the commenter urged the EPA 

to finalize more stringent BART determinations for FCPP. 

The commenter noted that FCPP is a significant source of 

mercury emissions and provided information on the health and 

ecosystem effects of mercury, as well as on the deposition of 

mercury and the levels of mercury found in the Four Corners 

area. In addition, the commenter stated that FCPP emits more 

than 16 million tons per year (tpy) of CO2, and that such 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 42 of 153

emissions contribute significantly to climate change which is 

likely to result in increasing temperatures and increase drought 

in the Southwest. The commenter noted that the supplemental 

proposal would reduce emissions of both mercury and CO2.

One environmental advocacy group stated that a formal 

Health Impact Assessment should be conducted by independent 

experts before EPA’s final decision to answer such questions as 

whether shutting down Units 1 – 3 is sufficient to protect local 

health, and what health impacts would result from delaying 

pollution controls on Units 4 and 5 until 2018.

Response: EPA agrees that there are potential benefits to 

health and the environment from reducing emissions of NOx. 

However, quantifying health benefits is not within the scope of 

the BART five factor analysis required under the CAA (§169A(g)). 

The BART Guidelines provide additional information on how to 

analyze “non-air quality environmental impacts, and focuses on 

adverse environmental impacts associated with control 

technologies, i.e., generation of solid or hazardous wastes and 

discharges of polluted water, that have the potential to affect 

the selection or elimination of a control alternative” (see 70 

FR 39169). Thus, although the BART Guidelines do state that 

relative environmental impacts (both positive and negative) of 

alternatives can be compared with each other, they state that 

“if you propose to adopt the most stringent alternative, then it 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 43 of 153

is not necessary to perform this analysis of environmental 

impacts for the entire list of technologies”. EPA agrees with 

commenters that controlling pollutant emissions may have cobenefits for reducing ozone production and acid deposition. EPA 

does not interpret the BART Guidelines to require quantification 

of human health or environmental co-benefits in determining 

BART, particularly if the most stringent BART option is

finalized. Similarly, EPA does not interpret the BART guidelines 

to require human health or environmental assessments of 

alternative compliance strategies as long as we have determined 

that the alternative strategy achieves better progress towards 

the national visibility goal. 

Comment: The commenter stated that human exposure to 

environmental hazards is an important factor in assessing 

impacts of FCPP. The commenter encouraged EPA to pursue health 

studies in collaboration with the Navajo Nation to study local 

risks associated with exposure to criteria pollutants, indoor 

air pollutants, and other contributing air pollutants, from 

which improved public health and effective rulemakings under the 

CAA may be achieved. 

Response: Assessing human exposure and quantifying health 

benefits are outside the scope of the requirements of the 

Regional Haze Rule. EPA sets National Ambient Air Quality 

Standards (NAAQS) to establish levels of air quality that are 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 44 of 153

protective of public health, including the health of sensitive 

populations, for a number of pollutants including particulate 

matter. These "sensitive" populations include asthmatics, 

children, and the elderly. At this time the Navajo Nation is not 

identified as out of attainment with any of the NAAQS. However, 

EPA recognizes that there are significant concerns about risk 

and exposure to air pollutants on the Navajo Nation and EPA will 

continue discussions with the Navajo Nation and will involve 

other federal agencies, as appropriate, to help address these 

concerns.

C. Comments on Factor Three - Existing Controls at FCPP

Comment: One of the owners of FCPP agreed with EPA’s 

summary of the existing controls at the plant, but noted that 

the proposed FIP is only the most recent action in a long line 

of regulatory and voluntary efforts to reduce emissions of 

pollutants that impact visibility, including SO2, NOx, and PM 

emissions. The commenter asserted that FCPP has a strong history 

of retrofitting pollution controls and recounted the facility’s 

history of installing these controls and reducing emissions.

Response: EPA agrees that there have been numerous 

installations of pollution controls over the several decades 

that FCPP has been in operation. The most recent voluntary 

effort by FCPP increased the SO2 removal from its long-term level 

of 72 percent removal to 88 percent removal. This was 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 45 of 153

accomplished before the end of 2004 and became effective as a 

regulatory requirement in June 2007. The improvement in SO2

removal has resulted in a decrease of over 22,000 tons of SO2 per 

year since that time. 

D. Comments on Factor Four - Remaining Useful Life at FCPP

Comment: One of the owners of FCPP noted that the BART 

rules state that the normal amortization period (20 years for NOx

control devices) is appropriate to use as the remaining useful 

life if the plant’s “remaining useful life will clearly exceed” 

that amortization period (citing 70 FR 39169). The commenter 

asserted, however, that as a result of substantial uncertainty 

related to multiple factors, it is not at all clear that the 

plant’s remaining useful life is at least 20 years. 

Moreover, according to the commenter, one factor that 

should not be allowed to shorten the useful life under the BART 

rules is the choice of BART itself – EPA cannot use a 20-year 

amortization period to justify a specified technology (e.g., 

SCR) if the application of the technology would be so costly as 

to make the facility uneconomical and shorten its useful life 

(citing 70 FR 39164, 39171). 

The commenter made a number of arguments related to the 

possibility of a shorter useful life at FCPP that are briefly 

summarized here. The excessive cost of SCR will dramatically 

increase the energy costs of the plant, potentially making it 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 46 of 153

uneconomical. The proposed “phase-in schedule” for SCR may force 

closure of units because APS will not have certainty by the 

compliance deadline that the lease will be extended or that 

Southern California Edison’s ownership share will have been 

successfully transitioned. Emerging environmental laws and 

regulations present cost and operational uncertainty that may 

shorten FCPP’s useful life (including new GHG laws and 

regulations, MATS, new ash-handling requirements, and new 

requirements for cooling water intake structures). 

Response: EPA disagrees that we must consider a shorter 

useful life because of uncertainty related to the factors cited 

by the commenter. It is inappropriate to consider a useful life 

shorter than 20 years based solely on uncertainty or the

possibility of shut down. EPA further notes that in its cost 

analysis on behalf of APS, B&V stated “the remaining useful life 

of Units 1 through 5 was at least 20 years”.19 Unless there is an 

enforceable obligation for APS to cease operations or unless APS 

convincingly demonstrates that controls (rather than uncertainty 

associated with future requirements) will cause facility 

closure, the default 20 year amortization period represents the 

appropriate period for the remaining useful life.

 

19 See B&V Engineering Analysis for Units 1 – 5 at FCPP dated December 

2007. Document number 0011 in docket for proposed rulemaking: EPA-R09-OAR2010-0683.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 47 of 153

EPA agrees that our proposed “phase-in” schedule for 

installation of add-on post-combustion NOx controls on Unit 1 – 3 

for BART, which was added in the supplemental proposal, may have 

allowed less than two years for engineering and installation 

from the date by which APS intends to make its decision on 

continuing operation or shutting the units down by 2014. EPA is 

finalizing a modified schedule for the installation of add-on 

post combustion controls from what was originally proposed 

(phased-in installation of controls within three to five years 

of effective date) by requiring one of the 750 MW units to 

comply with the BART emission limit within 4 years of the 

effective date of this final rule and the remaining units (Units 

1 - 3 and either Unit 4 or 5) within 5 years of the effective 

date of this final rule. 

Comment: One industry commenter stated that EPA, rather 

than evaluate APS’ supplemental proposal as an alternative 

emission control strategy, should instead “re-determine” BART 

for each of the five units at FCPP based on the APS-proposed 

shutdown scenario for Units 1 – 3, i.e., reducing the remaining 

useful life of Units 1 – 3 to 2014 and then using the short 

remaining life of those units to determine that BART for Units 1 

– 3 is no additional control. The commenter concluded that a 

“better-than-BART” control strategy does not seem to be 

necessary for determining the appropriate requirements for FCPP 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 48 of 153

under the APS-proposed shutdown scenario; instead, a BART 

determination for each unit with appropriate weighting of the 

statutory factors appears to present a logical and lessburdensome means of applying section 169A(b)(2) of the CAA to 

FCPP.

Response: EPA disagrees that APS’s supplemental proposal 

should be evaluated in terms of a BART re-determination rather 

than in terms of its current status as a “better-than-BART” 

alternative measure. The 2006 Regional Haze Rule (71 FR 60612) 

established the procedures described in 40 CFR 51.308(e)(2) and 

(3) for scenarios involving programs that may make greater 

reasonable progress than source-by-source BART. These provisions 

were specifically included to allow for the flexibility to 

consider alternative measures such as the one proposed by APS, 

and EPA considers it the most appropriate method for evaluating 

APS’S supplemental proposal. 

Comment: One industry commenter discussed the “remaining 

useful life” statutory factor, noting that under the BART 

Guidelines remaining useful life is ignored in the majority of 

BART determinations (citing 40 CFR part 51, Appendix Y, section 

IV.D.4.k), which the commenter asserted is inappropriate. 

According to the commenter, Congress designated the remaining 

useful life of the source as an important consideration because 

it did not want to impose the burdens of control technology 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 49 of 153

retrofits on sources that were more than 15 years old at the 

time the statute was enacted. Given that it is now 34 years 

after the BART requirements were enacted, the commenter stated 

that the “remaining useful life” statutory factor should weigh 

heavily in BART determinations for older sources such as FCPP, 

instead of being ignored. 

Response: EPA disagrees with the commenter that we ignored 

the “remaining useful life” statutory factor in our BART 

decision. EPA considered this factor in our BART analysis (see 

pages 42-43 of the TSD for our proposed BART determination). As 

discussed in the TSD, the remaining useful life of an Electric 

Generating Unit (EGU) subject to BART is determined by the 

utility. EPA cannot arbitrarily decide that an EGU has less 

useful life when it is not within our BART rulemaking authority 

to require closure of an EGU. If a utility used a shorter useful 

life than one that would allow the full amortization of any 

necessary pollution controls, EPA would take that into account 

in the cost analysis, provided that there was an enforceable 

obligation for the facility to cease operation by that time. 

E. Comments on Factor Five - Anticipated Visibility 

Improvements

Comment: One of the owners of FCPP presented information 

on visibility conditions on the Colorado Plateau and the role of 

NOx emissions in Western visibility impairment. The commenter 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 50 of 153

noted that SO2 and NOx emissions have been decreasing in recent 

years. The commenter also presented information that purported 

to show that whether averaged over the haziest 20 percent of 

days, the clearest 20 percent of days, or all days, power plant 

NOx emissions contribute less than 1.5 percent to the light 

extinction at Mesa Verde National Park. 

Another commenter questioned EPA’s assertion that NOx and PM 

from FCPP are significant contributors to visibility impairment 

in the numerous mandatory Class I areas surrounding FCPP (citing 

75 FR 64221), stating that coal-fired power plants, including 

FCPP, are relatively small contributors to regional haze in the 

surrounding Class I Areas.

Response: EPA modeling of FCPP showed visibility impacts 

ranging from 1.2 to 6.0 deciviews (dv), depending on the Class I 

area, with the sum of impacts at all sixteen Class I areas 

totaling 43 dv. This is a significant contribution to visibility 

impairment. Even if an individual source category appears small 

to some commenters, the many segments of the emissions inventory 

together cause significant visibility impairment and must be 

addressed in order to make progress towards the national goal of 

remedying visibility impairment from manmade pollution. Section 

169A of the CAA requires BART determinations on BART-eligible 

EGUs regardless of trends or ambient visibility conditions.

Application of BART is one means by which we can ensure that 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 51 of 153

downward emission and visibility impairment trends continue. EPA

identifies stationary sources as an important category to

evaluate in a BART analysis. 

Comment: Three of the owners of FCPP, the Navajo Nation, 

and two utility industry associations argued that EPA’s use of 

Interagency Workgroup on Air Quality Modeling (IWAQM) Phase II 

default background ammonia values is not appropriate. They 

argued the following points: (1) actual field measurements show 

lower ammonia concentrations than used by EPA; (2) EPA is 

mistaken in its assumption that background ammonia 

concentrations along the path of the plant’s plume determine 

nitrate concentrations and their contribution to haze at the 

receptor site; (3) EPA’s “corroborating” approach of “backcalculating” ammonia is flawed because it erroneously assumes 

that the ammonia associated with measured sulfate and nitrate 

would all be available to react with FCPP emissions, whereas in 

reality those measurements reflect emissions from many sources; 

(4) EPA’s analysis of nitrate predictions as a check on the 

ammonia values used is also flawed because it erroneously 

assumes that the resulting measured nitrate levels are solely 

due to FCPP emissions; (5) comparable analysis using the EPA 

ammonia value shows substantial and “physically impossible” 

over-predictions of nitrate. The commenters conclude that the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 52 of 153

use of IWAQM values invalidates EPA’s BART modeling and the BART 

determination that relied on the modeling. 

Another utility industry association stated that several 

measurement programs on the Colorado Plateau show that actual 

ammonia values in Class I areas near FCPP are significantly 

lower than the IWAQM default value, indicating that these values 

typically range from 0.1 to 0.6 ppb. The commenter noted that 

ammonia concentrations are lowest during the cold season when 

the visibility impacts of NOx emissions are the highest. 

Accordingly, the commenter asserted that using a single ammonia 

value throughout the year is not scientifically valid and should 

be replaced with seasonally variable values.

The Navajo Nation expressed concern regarding discrepancies 

between EPA and APS modeling inputs, given the commenter’s 

understanding that APS obtained advance EPA approval for its 

modeling protocols. Some commenters stated that EPA had earlier 

agreed to lower ammonia concentrations, and so should not be 

using the higher IWAQM value now.

In contrast, one public interest advocacy group concurred 

with EPA’s back-calculation method for ammonia background levels 

(citing the TSD, page 60). The commenter added that the requests 

to EPA from other commenters for additional ammonia monitoring 

data are unrealistic in today’s budget environment. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 53 of 153

Response: EPA disagrees with commenter objections to the 

background ammonia concentrations used in our modeling. Our use 

of the 1 ppb IWAQM Phase II default background ammonia value is 

appropriate. Most of the objections have already been discussed 

in EPA’s TSD for the proposal; and several of them concern the 

“back-calculation” method that we used only as corroboration for 

using the 1 ppb results we principally relied on. Also, even if 

the lower ammonia concentrations urged by some commenters were 

accepted, EPA’s sensitivity modeling results provided in the TSD 

for our proposed BART determination showed the visibility 

benefits would still support EPA’s BART determination. EPA also

provided the results of modeling runs that used the lower 

ammonia background concentrations recommended by some commenters 

(see TSD Table 37). The visibility benefits of the NOx controls 

for BART are substantial under all ammonia scenarios, including 

the lower background ammonia concentrations recommended by 

commenters. For 12 Class I areas, modeling even with those lower 

background concentrations showed improvements of 0.5 dv or more, 

an amount recognized in the BART Guidelines as significant (e.g. 

at 70 FR 39120).

The lack of ammonia and ammonium measurements in the Class 

I areas of concern requires that EPA estimate background ammonia 

concentrations by some method, considering available data and 

approaches. As discussed in the BART proposal and its 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 54 of 153

accompanying TSD, EPA understands that there is no single

accepted method for estimating the background concentration of 

ammonia, and that any method will have advantages and 

disadvantages. The lack of consensus on a method was a factor in 

EPA’s decision to rely on the 1 part per billion (ppb) default 

value in IWAQM, as was the fact that IWAQM is the only available 

guidance on this issue. In summary, there is insufficient 

monitoring information available to use a different value, or to 

support any seasonally varying values and, as described below, 

these values are reasonable to use in this analysis.

On the first issue, field measurements cited by the 

commenters were not performed in the Four Corners area, nor at 

the Class I areas near FCPP, so they do not give appropriate 

ammonia background concentrations for modeling of FCPP. In 

addition, the studies provide only gaseous ammonia (NH3) and not 

ammonium (NH4) that has reacted with SO2 or NOx emissions. For 

purposes of assessing FCPP impacts relative to natural 

background, per the BART Guidelines, both ammonia and ammonium 

should be assumed to be available to interact with emissions 

from FCPP. The ammonia-only measurements cited by the commenters 

underestimate the available ammonia. Finally, as discussed in 

the TSD, field measurements in the Four Corners area showed 

ammonia measurements ranging from 1.0 ppb to 1.5 ppb, and 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 55 of 153

sometimes as high as 3.5 ppb.20 This provides some additional 

support for the 1 ppb used by EPA.

On the second issue, in using a 1 ppb background EPA did 

not rely on an assumption about the importance of background 

ammonia along the path of the plume, as claimed by the 

commenters. The 1 ppb background is a representative value for 

areas in the west under existing EPA guidance, in the IWAQM 

document. The commenters’ objection is based on the rapidity of 

the nitrate-nitric acid equilibrium, which they state implies 

that ammonium nitrate can only be estimated using ammonia 

measurements right at the Class I area, and not the ammonia that 

occurs earlier along the plume’s path to the area. EPA’s TSD for 

the proposed rulemaking did state (TSD p.62) that the Federal 

Land Managers partly relied on this assumption as one of the 

rationales for the back-calculation method, discussed below; EPA 

also expressed support for the idea that the method can be 

viewed as a 24-hour temporal integration, not just a spatial 

integration over the plume path, and that this aspect can be 

viewed as desirable for the 24-hour average visibility estimate 

that CALPUFF provides (TSD pp.71-72). This plausibility argument 

applies despite the rapid nitrate-nitric acid equilibrium cited 

 

20 Mark E. Sather et al., 2008. “Baseline ambient gaseous ammonia 

concentrations in the Four Corners area and eastern Oklahoma, USA”. Journal 

of Environmental Monitoring, 2008, 10, 1319-1325, DOI: 10.1039/b807984f
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 56 of 153

by the commenters, and in any case was not relied on by EPA in 

using the 1 ppb default ammonia background.

As the commenters stated under the third issue, EPA used a 

back-calculation ammonia estimation method as an alternative 

means of corroboration for the 1 ppb IWAQM method, which is more 

fully explained in the TSD for the proposed rulemaking.

Essentially, it uses measured particulate ammonium sulfate and 

nitrate to estimate the amount of ammonia that must have been 

present to form those ammonia compounds. The commenters object 

that the method assumes that all the calculated ammonia is 

available to interact with the FCPP plume as background ammonia. 

However, this assumption is reasonable for the single-source 

CALPUFF modeling performed under the BART Guidelines. It

estimates ammonia concentrations that would be monitored at the 

Class I area if only this single source existed; it includes 

ammonia that is currently in the form of ammonium because of 

interaction with other sources’ emissions. It remains true that 

some portion of the calculated ammonia would in reality not be 

available for FCPP, because it arrives at the monitor from a 

different direction than FCPP’s pollutant plume; on the other 

hand, the data would also include directions contributing belowaverage ammonia, reducing that effect.

In addition, the back-calculated ammonia is based on 

measurements only of particulate ammonium, the form associated 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 57 of 153

with measured sulfate and nitrate; it does not include any 

gaseous ammonia that may also be present. In this sense, the 

back-calculated ammonia is a lower bound on the ammonia that may 

be available to interact with source emissions; that is, the 

method may underestimate ammonia concentrations. This possible 

underestimation tends to offset possible overestimation

discussed above.

EPA does not claim that the back-calculation method is 

dispositive; it incorporates various assumptions and 

imperfections that make clear it is only an estimate. However, 

it is based on real measured data at Class I areas, and has some 

counterbalancing tendencies for over- and under-estimation. 

After weighing various lines of argument about the backcalculation method, EPA disagrees with the commenters who 

recommended that it be rejected altogether. The method provides 

a useful estimate of ammonia for BART modeling, by providing 

concentrations representative of the high values that would be 

observed at the Class I areas in the absence of other sources. 

The back-calculation method, therefore, is used to corroborate 

that it is appropriate to use the 1 ppb IWAQM default for 

background ammonia concentrations.

In the fourth issue raised by commenters, the commenters 

claim that the assumption of full availability to FCPP of the 

back-calculated ammonia invalidates EPA’s comparison of 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 58 of 153

monitored nitrate levels with those modeled using the backcalculated ammonia (TSD p.73). As just discussed for the third 

issue, EPA disagrees that the assumption is invalid for 

corroboration of single-source BART assessment modeling. For 

single-source BART modeling, on balance, is reasonable to assume 

all the ammonia is available to the source, given the 

counterbalancing tendencies for over- and underestimation

inherent in the back-calculation method discussed above. In any 

case, this method mainly provided corroboration for the results 

from using the 1 ppb ammonia default. 

The fifth issue about “physically impossible” nitrate overpredictions does not account for the fact that any model 

evaluation is expected to have under- and over-predictions, 

depending on the meteorological conditions and the geographic 

location modeled, as well as on the location of the monitor used 

for comparison. The commenter’s apparent requirement for no 

overpredictions whatsoever would require a model with the 

converse problem, a bias toward underprediction. While 

consistent over-prediction in a full model performance 

evaluation would indeed raise concerns over its validity, as EPA 

stated, our nitrate comparison was not intended as a model 

performance evaluation, but rather as a “rough check” for the 

back-calculation corroboratory method (TSD p.73). EPA found that 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 59 of 153

the modeled and monitored values, for both the maximum values 

and the 98th percentiles, were generally in agreement.

Finally, contrary to the commenter’s assertion, EPA did not 

receive a modeling protocol in advance of modeling by APS’s 

contractor. EPA disagrees with commenters that EPA committed to 

use the same ammonia concentrations used by APS’s contractor in 

our own modeling analysis for our BART determination.

Comment: Three of the owners of FCPP and a utility 

industry association asserted that CALPUFF version 5.8 used in 

EPA’s BART analysis is outdated. Because of enhancements to the 

model’s chemistry, the commenters asserted that CALPUFF version 

6.4 represents the best application that is currently available. 

A number of the commenters mentioned a December 2010 meeting 

between the CALPUFF developer and the FLMs where the FLMs 

reportedly supported an expedited review and approval of CALPUFF 

version 6.4.

Another owner of FCPP stated that the version of CALPUFF 

used by EPA has a tendency to over-predict nitrate 

concentrations, which is compounded by EPA’s use of what the 

commenter stated are overestimated ammonia background values. 

The commenter asserted that this combination of errors results 

in a significant over-prediction of visibility improvements for 

more stringent NOx BART control options. Further, the commenter 

stated that this disproportionately affects the incremental 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 60 of 153

visibility benefits predicted for SCR over Low NOx Burners (LNB) 

compared to LNB over baseline. 

In contrast, one federal agency was generally supportive of 

the modeling methods employed by EPA with the regulatory 

approved version 5.8 of the CALPUFF modeling system. 

Response: EPA disagrees with the commenters that any new 

CALPUFF version should be used for the BART determination. EPA 

relied on version 5.8 of CALPUFF because it is the EPA-approved 

version in accordance with the Guideline on Air Quality Models 

(“GAQM”, 40 CFR 51, Appendix W, section 6.2.1.e); EPA updated 

the specific version to be used for regulatory purposes on June 

29, 2007, including minor revisions as of that date; the 

approved CALPUFF modeling system includes CALPUFF version 5.8, 

level 070623, and CALMET version 5.8 level 070623. CALPUFF 

version 5.8 has been thoroughly tested and evaluated, and has 

been shown to perform consistent with the version from the time 

of the initial 2003 promulgation, in the analytical situations 

CALPUFF has been approved for. Any other version would be 

considered an “alternative model”, subject to the provisions of 

GAQM section 3.2.2(b), requiring full model documentation, peerreview, and performance evaluation. No such information for the 

later CALPUFF versions that meet the requirements of section 

3.2.2(b) has been submitted to or approved by EPA. Experience 

has shown that when the full evaluation procedure is not 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 61 of 153

followed, errors that are not immediately apparent can be 

introduced along with new model features. For example, changes 

introduced to CALMET to improve simulation of over-water 

convective mixing heights caused their periodic collapse to 

zero, even over land, so that CALPUFF concentration estimates 

were no longer reliable. 

In addition, the latest version of CALPUFF, 6.4, 

incorporates a detailed treatment of chemistry. EPA’s 

promulgation of CALPUFF (68 FR 18440, April 15, 2003) as a 

“preferred” model approved it for use in analyses of Prevention 

of Significant Deterioration increment consumption and for 

complex wind situations, neither of which involve chemical 

transformations. For visibility impact analyses, which do 

involve chemical transformations, CALPUFF is considered a 

“screening” model, rather than a “preferred” model; this 

“screening” status is also described in the preamble to the BART 

Guidelines (at 70 FR 39123, July 6, 2005). The change to 

CALPUFF 6.4 is not a simple model update to address bug fixes, 

but a significant change in the model science that requires its 

own rulemaking with public notice and comment.

Furthermore, it should be noted that the US Forest Service 

and EPA review of CALPUFF version 6.4 results for a limited set 

of BART applications showed that differences in its results from 

those of version 5.8 are driven by two input assumptions and not 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 62 of 153

associated with the chemistry changes in 6.4. Use of the socalled “full” ammonia limiting method and finer horizontal grid 

resolution are the primary drivers in the predicted differences 

in modeled visibility impacts between the model versions. These 

input assumptions have been previously reviewed by EPA and the 

FLMs and have been rejected based on lack of documentation, 

inadequate peer review, and lack of technical justification and 

validation.

EPA intends to conduct a comprehensive evaluation of the 

latest CALPUFF version along with other “chemistry” air quality 

models in consultation with the Federal Land Managers, including 

a full statistical performance evaluation, verification of its 

scientific basis, determination of whether the underlying 

science has been incorporated into the modeling system 

correctly, and evaluation of the effect on the regulatory 

framework for its use, including in New Source Review 

permitting. CALPUFF version 5.8 has already gone through this 

comprehensive evaluation process and remains the EPA-approved 

version, and is thus the appropriate version for EPA’s BART 

determination for FCPP.

Comment: Some commenters argued against the visibility 

metrics that EPA introduced in the BART proposal. One commenter 

noted that none of the metrics (percent improvement in dv 

impacts, cumulative changes in dv, and dv impacts scaled by the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 63 of 153

geographic area of the affected Class I area) is addressed in 

the BART rules, and posited that their introduction into the 

BART process is intended to inflate the estimated visibility 

benefits of the control options at FCPP. Regarding the percent 

improvement metric, the commenter stated that these values 

(unlike values of the haze index in dv) have no consistent 

relationship to the human perception of haze changes and no 

consistent relationship to changes in ambient visibilityimpairing particle concentrations.

Similarly, one of the owners of FCPP stated that cumulative 

change in dv is not an appropriate metric to describe visibility 

improvement and should be withdrawn. This commenter made a 

number of points which are briefly described here. The peak 

impact from a source occurs at different times in different 

Class I areas because a facility’s emissions cannot result in 

peak concentrations in all directions at once. Thus, this metric 

really does not represent a cumulative regional impact of the 

source (and hence the benefit of controls); rather it simply 

produces a mathematical summation of the peak impacts occurring 

at different times at various Class I areas. It is inappropriate 

to add improvements over all Class I areas. A 0.5 dv improvement 

in one Class I area and a 0.5 dv improvement in another area 

does not result in a 1 dv improvement – the improvement is a 0.5 

dv improvement, which occurs in two different locations. Any one 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 64 of 153

observer would experience only a 0.5 dv improvement; he or she 

can only experience the visibility improvement in the Class I 

area being visited. 

Conversely, one environmental advocacy group commenter 

supported the use of a cumulative impact analysis. The commenter 

asserted that the cumulative impact of a source’s emissions on 

visibility, as well as the cumulative benefit of emission 

reductions, is a necessary consideration as part of the fifth 

step in the BART analysis, particularly in cases such as FCPP

where the source causes or contributes to visibility impairment 

at a significant number of Class I areas. The commenter stated 

that failing to account for a source’s cumulative impairment and 

the cumulative pollution control benefit would result in a 

failure to acknowledge the regional approach to reducing haze.

Response: EPA believes that it is important to consider 

the visibility impact on multiple Class I areas. The goal of the 

visibility program is to remedy visibility impairment at all 

Class I areas. CAA 169A(a)(1). One approach to account for the 

benefits to all affected Class I areas is the cumulative “total 

dv” metric. EPA relied on the modeled impacts and benefits at 

each Class I area individually, the number of Class I areas 

affected, and also considered, but did not rely on, the sum of 

visibility impacts and benefits across all 16 Class I areas.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 65 of 153

Comment: Two commenters questioned EPA’s use of 0.5 dv as 

the threshold of a humanly perceptible change in visibility 

(citing 75 FR 64228). One commenter added that the establishment 

of a specific deciview threshold as a “bright line” to define 

whether a certain control will be imposed as BART is contrary to 

the intent of the BART rules and the objectives of the Regional 

Haze program, which require EPA to consider the cost of each 

control option in relation to the associated visibility benefit.

One of the owners of FCPP expressed the belief that 

application of SCR at FCPP would result in no perceptible 

visibility improvement and therefore cannot be BART. 

Response: EPA disagrees with the commenters that the 

visibility benefit from the proposed BART controls is too small 

to warrant requiring the controls; in addition, EPA is not using 

a perceptibility threshold in this BART determination. EPA 

agrees that thresholds should not be considered a “bright line” 

in making BART decisions. In the BART Guidelines, EPA described 

1 dv as the threshold for an impact that “causes” visibility 

impairment, and 0.5 dv as a threshold for an impact that 

“contributes” to visibility impairment, for determining whether 

a source is subject to BART, though States were accorded 

discretion to use different thresholds (70 FR 39118, July 6, 

2005; also 39120-39121). These thresholds do not apply to BART 

determinations for sources that have been found subject to BART; 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 66 of 153

States or EPA could consider visibility impacts less than 0.5 dv 

to warrant BART controls. To the extent that the comment is 

questioning the BART eligibility of FCPP, EPA has already 

established that FCPP is BART eligible and the commenter did not 

provide evidence to the contrary.

Even if the commenters are correct that 0.5 dv change is 

not perceptible, EPA noted that “[e]ven though the visibility 

improvement from an individual source may not be perceptible, it 

should still be considered in setting BART because the 

contribution to haze may be significant relative to other source 

contributions in the Class I area. Thus, we disagree that the 

degree of improvement should be contingent upon perceptibility. 

Failing to consider less-than-perceptible contributions to 

visibility impairment would ignore the CAA’s intent to have BART 

requirements apply to sources that contribute to, as well as 

cause, such impairment.” (70 FR 39129) That is, impacts smaller 

than 0.5 dv do contribute to impairment. Conversely, an 

improvement of 0.5 dv or even less contributes to improvement in 

visibility impairment. As stated in the proposal, the modeled 

improvements in visibility are large enough to warrant requiring 

the proposed BART controls. While the actual improvements may be 

larger, from 0.6 to 2.8 dv, even as small an improvement as 0.5 

dv is a contribution toward improving visibility, especially 

when the benefits at multiple Class I areas are considered. In 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 67 of 153

conjunction with improvements from other sources, this will help 

and is necessary for progress toward the CAA goal of remedying 

manmade visibility impairment.

Comment: One environmental advocacy group commenter stated 

that EPA underestimated visibility improvement from installing 

NOx controls because it overestimated the production of sulfuric 

acid by the SCR and underestimated the amount of sulfuric acid 

removed downstream of the SCR. The commenter cited reports 

attached to the comments to argue that sulfuric acid does not 

limit SCR NOx control efficiency. The reports also state that 

modeling shows that greater NOx removal rates are not offset by 

sulfuric acid emissions but instead yield greater visibility 

improvements than those proposed by EPA. The commenter states 

that this would result in a significant visibility benefit from 

increasing the SCR NOx efficiency from 80 percent to 90 percent 

and therefore concludes that a higher level of NOx control than 

80 percent should be determined BART.

Response: EPA disagrees that we overstated the production 

of sulfuric acid from the SCR catalyst and underestimated the 

amount of sulfuric acid removed downstream of the SCR. In the 

TSD for our proposed BART determination, we estimated sulfuric 

acid emissions using the Electric Power Research Institute 

(EPRI) methodology and provided detailed explanations for all of 

the assumptions we applied (see TSD p.55-59, 64-65, and 68).
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 68 of 153

While we fully acknowledge and understand that the generalized 

EPRI methodology does not precisely represent true sulfuric acid 

emissions for a given facility, this method is a commonly used 

calculation methodology for estimating sulfuric acid emissions 

under a future operating scenario involving SCR. 

EPA assumed in our BART proposal that a 3+1 system (four

layers of catalyst) would achieve 80 percent NOx removal. Greater 

reduction efficiencies would likely require an additional layer 

of catalyst, which models indicate would increase sulfuric acid 

emissions. Based on the SO2 to SO3 conversion rate guarantee we 

received from Hitachi for its CX series catalyst (ultra-low 

conversion) of 0.167 percent per layer, the use of an additional 

catalyst layer would equal five layers of catalyst and a 0.835 

percent conversion rate. EPA is not aware of SCR systems that 

use five layers of catalyst, and the addition of a fifth layer 

would also affect the cost and operation of the unit. 

Although EPA agrees that the modeling referenced by the 

commenter indicates greater visibility improvement from an SCR 

system achieving 90 percent removal compared to 80 percent

removal despite higher sulfuric acid emissions,21 EPA does not 

agree that this requires EPA to determine that a greater level 

 

21 EPA notes that the baghouses on Units 4 and 5 are assumed to provide a 

significant amount of control of sulfuric acid emissions, therefore, such 

slight increases in sulfuric acid emissions would not be expected on units 

that are not equipped with baghouses.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 69 of 153

of control is required as BART. The level of control recommended 

by the commenter is equivalent to those required as the Best 

Available Control Technology (BACT) for new facilities. As 

discussed in responses to other comments, the Regional Haze Rule 

requires a case-by-case BART determination, which need not be 

equivalent to BACT for new facilities. As discussed in our 

proposed BART determination and in our Supplemental proposal, 

given the boiler size and configuration at FCPP that limit use 

of combustion controls, and other considerations related to ash 

content of coal, EPA is finalizing its determination that 80 

percent control is appropriate as BART for FCPP.

F. Comments on BART Determinations

1. Comments on the Proposed BART Determination for NOx

Comment: A number of commenters, including owners of FCPP, 

the Navajo Nation, and a utility industry association, assert 

that EPA’s BART analysis was inconsistent with its own 

regulations in that it did not give proper weight to the 

“presumptive BART” limits for NOx that it established for EGUs 

through notice-and-comment rulemaking (generally citing 70 FR 

39104, July 6, 2005). The commenters noted that these 

presumptive BART limits are based on the use of combustion 

controls, and that EPA had considered and rejected establishing 

presumptive BART limits based on SCR. A brief summary of these 

comments follows. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 70 of 153

In establishing presumptive BART limits for NOx emissions 

from EGUs, EPA concluded that combustion control-based 

presumptive limits “are extremely likely to be appropriate for 

all greater than 750 MW power plants subject to BART” (a 

category that includes FCPP), that they are “highly costeffective controls,” and that they “would result in significant 

improvements in visibility and help to ensure reasonable 

progress toward the national visibility goal (citing 70 FR

39131). Additionally, EPA has made clear that “the presumptions 

represent a reasonable estimate of a stringent case BART...”

(citing 71 FR 60612, 60619, Oct. 13, 2006).

Commenters argue that EPA was not correct in stating in the 

proposed BART determination for FCPP that in setting presumptive 

BART limits, it “did not consider the question of what more 

stringent control technologies might be appropriately determined 

to be BART” (citing 75 FR 64226). Rather, EPA’s 2005 rules were 

clear that the Agency had considered – and rejected –

establishing presumptive BART limits based on SCR (citing 70 FR

39136). Thus, EPA established through rulemaking that SCR is not 

an appropriate basis for presumptive BART limits and that 

combustion controls should generally be deemed BART.

Commenters also argue that a BART analysis must begin with 

and take into account the presumptive BART limits and EPA’s 

rationale for setting them. If a source is able to meet the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 71 of 153

limit through the application of combustion controls, there 

should be an exceedingly strong presumption that such controls 

constitute BART.

Commenters state that EPA’s analytical approach disregarded 

the presumptive limits entirely. By using a top-down approach in 

which it started its analysis by evaluating SCR and then 

determined that SCR is BART for FCPP, EPA never undertook an 

assessment of combustion controls. 

Commenters further argue that in its BART analysis, APS 

demonstrated that each unit at FCPP can meet the presumptive 

BART limits through the application of advanced combustion 

control technologies. 

Under the BART rules, a deviation from presumptive BART, 

either upwards or downwards, is authorized if an alternative 

control level is justified based on “careful consideration of 

the statutory factors” (citing 70 FR 39131). Commenters argue 

that EPA did not carefully consider the BART factors and then

conclude that an alternative to presumptive BART limits is 

appropriate. Instead, commenters state that EPA dismissed the 

presumptive BART limits before even considering the BART 

factors.

Response: EPA disagrees with the commenters’ assertions 

that we did not give sufficient weight to presumptive BART NOx
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 72 of 153

limits, or that the BART determination for FCPP was performed in 

a manner inconsistent with the RHR. 

As noted in other responses in this document, the 

presumptive NOx limits established in the BART Guidelines are 

determined to be cost effective and appropriate for most units. 

The establishment of presumptive BART limits, and the 

corresponding technology upon which those limits are based, does 

not preclude States or EPA from setting limits that differ from 

those presumptions. Indeed, the five statutory factors 

enumerated in the BART Guidelines provide the mechanism for 

establishing different requirements. We note the RHR states: 

States, as a general matter, must require 

owners and operators of greater than 750 MW 

power plants to meet these BART emission 

limits. We are establishing these 

requirements based on the consideration of 

certain factors discussed below. Although we 

believe that these requirements are 

extremely likely to be appropriate for all 

greater than 750 MW power plants subject to 

BART, a State may establish different 

requirements if the State can demonstrate 

that an alternative determination is 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 73 of 153

justified based on a consideration of the 

five statutory factors.22

The RHR also states: 

If, upon examination of an individual EGU, a 

State determines that a different emission 

limit is appropriate based upon its analysis 

of the five factors, then the State may 

apply a more or less stringent limit.23

Therefore, the presumptive emission limits in the BART 

Guidelines are rebuttable.24 The presumptive emission limits 

apply to power plants with a total generating capacity of 750 MW 

or greater insofar as these sources are required to adopt 

emission limits at least as stringent as the presumptive limits, 

unless after considering the five statutory factors, the State 

determines that the presumptive emission limits are not 

appropriate. Moreover, the RHR and BART Guidelines do not exempt 

States from a five factor BART analysis, and that BART analysis 

may result in a determination of BART emission limits that are 

more or less stringent than the presumptive emission limits for 

subject to BART sources. The RHR states: 

For each source subject to BART, 40 CFR 

51.308(e)(1)(ii)(A) requires that States identify the 

 

22 70 FR 39131 23 70 FR 39132 24 71 FR 60619
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 74 of 153

level of control representing BART after considering 

the factors set out in CAA section 169A(g), as 

follows: 

States must identify the best system of continuous 

emission control technology for each source subject to 

BART taking into account the technology available, the 

costs of compliance, the energy and non-air quality 

environmental impacts of compliance, any pollution 

control equipment in use at the source, the remaining 

useful life of the source, and the degree of 

visibility improvement that may be expected from 

available control technology.25

EPA’s site-specific five-factor analysis performed for FCPP 

demonstrates that, in considering the expected remaining useful 

life of FCPP and the existing controls, SCR is cost effective, 

results in the most visibility improvement of all feasible 

control technologies, and does not cause energy or non-air 

quality environmental impacts that warrant its elimination as 

the top control option. As a result, regardless of the 

appropriateness of SCR as a control technology for most units on 

a national scale, or the extent to which EPA considered SCR in 

establishing the presumptive limits, the site-specific five-

 

25 70 FR 39158
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 75 of 153

factor analysis performed for FCPP justifies a different NOx BART 

limit than the presumptive NOx BART limit. 

EPA disagrees with commenters’ assertions that we 

disregarded presumptive NOx BART limits. Although we do not rely 

upon the numerical values of the presumptive NOx limits listed in 

the BART Guidelines, the technological basis for presumptive NOx 

BART limits, such as the use of combustion control technology, 

boiler type, and coal type, were considered in the site-specific 

five-factor analysis. Combustion control technology was 

specifically considered as a potential retrofit technology, and 

costs and visibility improvements associated with combustion 

controls were calculated and included in the TSD in order to 

provide a comparison to other NOx control technologies. 

In addition, EPA disagrees that the rule directs 

authorities to consider non-combustion control technology only 

when presumptive limits cannot be met using combustion control 

technology. While a BART determination deviating from 

presumptive BART must be supported by the results of the fivefactor analysis, the rule does not restrict the ability of

States (or in this case, EPA) to initiate a five-factor 

analysis. 

Comment: Two of the owners of FCPP and the Navajo Nation 

asserted that advanced combustion controls constitute BART for 

FCPP because such controls will result in meaningful emission 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 76 of 153

reductions and will contribute to reasonable progress toward 

visibility improvement. 

One of these commenters noted that EPA has “determined that 

combustion controls are not likely to be effective control 

technologies at FCPP” (citing 75 FR 64226). The commenter 

asserted that EPA’s determination is based on superficial 

analysis and is mistaken. This commenter cited its comments 

which contain a detailed analysis of the use of LNB and OFA on 

FCPP’s units. According to the commenter, this analysis confirms 

that the use of advanced combustion controls on the five units 

at FCPP will reduce plant-wide NOx emissions by 34 percent and, 

for those units that are subject to presumptive BART limits, the 

reductions more than satisfy the presumptive limits in the BART 

rules. 

Two of the commenters added that considering that neither 

SCR nor advanced combustion controls will produce humanly 

perceptible visibility improvements in the nearby Class I areas, 

control technologies that result in limits that meet presumptive 

BART should be determined BART and that these reductions will 

contribute to reasonable progress toward the national visibility 

goal.

The Navajo Nation stated that a phased approach to 

emissions controls at FCPP, beginning with combustion controls, 

is fully consistent with both the CAA and the RHR, and is the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 77 of 153

approach that the EPA should take as a prudent trustee of the 

Navajo Nation. 

This commenter added that the BART component of the CAA and 

RHR was meant to provide for a measured response to emissions 

from aging power plants; thus, requiring the most expensive 

controls is inconsistent with the law and regulations governing 

the BART process. The commenter also asserted that requiring a 

power plant over which EPA has exclusive jurisdiction to bear a 

greater regulatory burden than similarly situated plants 

regulated by the States is contrary to the purposes of the Act, 

the RHR, and to the economic interests of the Navajo Nation.

Response: EPA disagrees with the comment that advanced 

combustion controls on all five units at FCPP will reduce plantwide NOx emissions by 34 percent. APS has provided conflicting 

information regarding whether or not advanced combustion 

controls will be effective at significantly reducing NOx

emissions at FCPP. As outlined in the TSD for our 2010 BART 

proposal, we have concluded that combustion controls will not be 

effective at significantly reducing NOx emissions at FCPP. 

EPA disagrees that installation of SCR will not result in

humanly perceptible impacts. As noted above, EPA’s visibility 

modeling of the impacts of SCR installation at FCPP indicates 

visibility improvements at the sixteen nearby Class I areas

ranging from 0.9 to 2.5 dv. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 78 of 153

EPA agrees with certain aspects of comments from the Navajo 

Nation regarding a phased implementation strategy to attaining 

national visibility goals. In 40 CFR 51.308(f), States are 

required to revise their regional haze implementation plans 

every ten years, which is a process that involves evaluating 

their ability to attain reasonable progress goals and 

potentially updating their long-term strategy for regional haze. 

The periodic revision requirement described in 40 CFR 51.308(f), 

however, does not extend to the implementation plan for BART 

requirements. The phased approach described by the Navajo Nation

has certain benefits, and a phased approach is incorporated into 

the alternative emission control strategy.

Comment: Two federal agencies and two groups of 

environmental advocacy groups assert that the NOx emission limit 

for the units at FCPP should be 0.05 lb/MMBtu based on the 

capabilities of SCR. The federal agency commenters stated that, 

given that BART is meant to achieve the best possible emissions 

reductions, EPA should not base its emission limits on the 

“minimum reduction expected from SCR, estimated by Hitachi Power 

Systems America” (citing the TSD for our proposed rulemaking) 

because real-world application of SCR indicates that lower NOx

emission limits are routinely reached. Regarding the emission 

limits for Units 4 and 5, the commenters noted that of the 20 

cell burners with SCR in 2010, 12 had lower NOx limits than 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 79 of 153

proposed by EPA for FCPP, with 3 EGUs at less than 0.06 

lb/MMBtu. Based on this information, the original APS BART 

analysis of SCR at 0.06 lb/MMBtu (annual and 24-hour average),

and the “common knowledge” that SCR can achieve at least 90

percent reduction, the commenters concluded that the 

installation of SCR at FCPP is capable of reducing annual NOx

emissions by 90 percent to 0.05 lb/MMBtu on an annual average 

basis.

One of the federal agency commenters specifically refuted 

EPA’s rationale in the supplemental proposal for its 80 percent 

SCR efficiency estimate. The main points are summarized below.

EPA took into account the degradation of the SCR catalyst 

over its lifetime and calculated the emission limit to reflect 

the capability of the catalyst just prior to its replacement on 

a 3-year cycle. Commenters assert this issue is not a technical 

limitation on SCR, but is simply a cost item to be accounted for 

in the proper design and operation of the SCR.

EPA stated that pursuing NOx control efficiencies of greater 

than 80 percent on Units 4 and 5 is limited by formation of H2SO4

from the SCR catalyst because the additional layers of catalyst 

needed to increase NOx control efficiency would increase 

emissions of H2SO4, most affecting nearby Mesa Verde National 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 80 of 153

Park. The commenter gave several reasons why this argument is 

incorrect. 

EPA stated that the high ash content (approximately 25 

percent) of the coal burned at FCPP may adversely affect the 

capability of SCR to reach the highest end of the control 

efficiency range without the use of additional layers of 

catalyst or more frequent catalyst replacement. According to the 

commenter, this is not consistent with previous EPA proposals 

for SCR emissions limits at facilities that use coal with 

similar ash content. Unless the FCCP ash contains some unusual 

catalyst poison, the 25 percent ash content is not a technical 

feasibility issue that would affect SCR effectiveness, but is a 

matter of proper SCR design, operation, and maintenance.

This federal agency commenter also asserted that NOx BART 

for Units 1 - 3 should be 0.05 lb/MMBtu on an annual basis. The 

commenter noted that unsuccessful attempts to reduce NOx

emissions at FCPP with combustion controls occurred over a 

decade ago when this technology was not as fully developed as 

now, and pointed out that APS’S BART analysis concluded that 

such controls are technically feasible and would reduce NOx

emissions significantly. 

The commenter evaluated Clean Air Markets Division (CAMD)

data for 2000 - 2009 and found 33 dry-bottom, wall-fired boilers 

with NOx emissions rates similar to FCPP Units 1 - 3 (0.6 - 0.8 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 81 of 153

lb/MMBtu) that had been reduced to 0.4 lb/MMBtu or less by 

application of modern combustion controls. The commenter 

asserted that because the typical approach is to first reduce NOx

emissions by combustion controls before adding SCR, these realworld CAMD data support the belief that using combustion 

controls and SCR could reduce NOx at FCPP Units 1 - 3 to 0.05 

lb/MMBtu on an annual basis.

The commenter asserted that modern SCRs are routinely 

designed and operated to achieve 90 percent NOx control and that 

based on this well-accepted industry standard, NOx control of at 

least 90 percent is BART. 

The commenter also contended that LNB and OFA are feasible 

for all five units at FCPP. The commenter rejected EPA’s 

statement that it would be difficult to retrofit Units 4 and 5 

with modern LNB technology (citing 76 FR 10534) and pointed out 

that the operator of FCPP has stated that the combination of LNB 

and OFA is technically feasible for these units. The commenter 

indicated that the use of LNB/OFA on Units 1-5 would reduce NOx

emissions by 27 to 46 percent, making SCR with a removal 

efficiency of 90 percent sufficient to satisfy a 0.05 lb/MMBtu 

NOx limit.

The commenter stated that a 0.05 lb/MMBtu limit is 

consistent with EPA’s determinations elsewhere, such as for the 

San Juan Generating Station (proposed limit of 0.05 lbs/MMBtu, 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 82 of 153

30-day rolling average) and for Desert Rock (final permit limit 

of 0.035 lbs/MMBtu, 365-day rolling average). According to the 

commenter, an EPA-issued permit containing a lower NOx limit 

creates a presumption of technical feasibility for purposes of 

BART. Commenters also argued that emission limits should be 

based on a 30-boiler operating day rolling average.

Response: EPA disagrees with the commenter’s assertion 

that emission limits associated with BART must meet the lowest 

emission rate achieved with that technology at any coal-fired 

power plant. The Regional Haze Regulations at 40 CFR 

§51.308(e)(1)(ii)(A) state that:

The determination of BART must be based on an analysis 

of the best system of continuous emission control 

technology available and associated emission 

reductions achievable for each BART-eligible source 

that is subject to BART . . . 

Additionally, the BART Guidelines state that: “[i]n assessing 

the capability of the control alternative, latitude exists to 

consider special circumstances pertinent to the specific source 

under review, or regarding the prior application of the control 

alternative”, (70 FR 39166) and that “[t]o complete the BART 

process, you must establish enforceable emission limits that 

reflect the BART requirements. . .” (70 FR 39172). The fivefactor BART analysis described in the Guidelines is a case-by-
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 83 of 153

case analysis that considers site specific factors in assessing 

the best technology for continuous emission controls. After a 

technology is determined as BART, the BART Guidelines require 

establishment of an emission limit that reflects the BART 

requirements, but does not specify that the emission limit must 

represent the maximum level of control achieved by the 

technology selected as BART. The BART Guidelines and the 

Regional Haze Rule do not preclude selection of the maximum 

level of control achieved by a given technology as BART, 

however, the emission limit set to reflect BART must be 

achievable by the specific source and should be determined based 

on consideration of site-specific factors. Therefore, limits set 

as Best Available Control Technology (BACT) during Prevention of 

Significant Determination (PSD) review (e.g., Desert Rock) may 

provide relevant information, but should not be construed to 

automatically represent the most appropriate BART limits 

representative of a given technology for every facility.

While some commenters asserted that combustion controls 

would be feasible upstream of SCR to further reduce NOx emissions 

to meet a limit of 0.05 lb/MMBtu, in its comment letter, the 

National Park Service (NPS) agreed with EPA that the addition of 

combustion controls may “not (be) worth the small incremental 

reduction in NOx emissions”. As discussed in the TSD for our 

proposed BART determination, because additional combustion 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 84 of 153

controls at FCPP would not achieve significant reductions in NOx

and may cause operability issues for the boilers, EPA determined 

that SCR, without the addition of new combustion controls, is 

BART for FCPP.

Several environmental organizations argued that a 30-day 

rolling average emission limit of 0.05 lb/MMBtu should be 

determined BART for FCPP and provided supporting documentation.26

EPA disagrees that an emission limit set in association with a 

BART determination must represent the lowest achieved emission 

rate from the best performing unit using that technology. EPA 

notes that, after further examination27 of the commenters’ 

supporting documentation, the maximum 30-day calendar average 

emission rates for the 17 top performing units exhibited 

significant variability (0.056 – 1.1 lb/MMBtu), even though the 

annual average emission rates listed are all below 0.07 

lb/MMBtu. 

In its comments, the National Park Service provided 

examples of 3 cell burner boilers currently equipped with SCR: 

Cardinal Units 1 and 2 and Belews Creek Unit 1. Based on NOx data 

from the Clean Air Markets Division (CAMD), EPA notes that over 

2009 – 2011, NOx emissions from Cardinal Unit 1 showed an 

 

26 See items (2 and 3) in collection of documents titled “Public Comment_8 

Environmental Groups (Barth)_Letter 5-2-11”. Document Number EPA-R09-OAR2010-0182. 27 See the Response to Comments, Section 8.1 in the docket for this final 

rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 85 of 153

increasing trend. Cardinal Unit 2 shows a similar pattern as 

Unit 1, with an increasing trend in minimum and maximum 30-day 

calendar averages. Belews Creek 1 also showed a similar pattern 

of generally increasing minimum and maximum 30-day calendar 

average emission rates. Although commenters are correct in 

stating that the best performing units can achieve 30-day 

rolling emission rates of 0.05 lb/MMBtu or lower, CAMD data show 

significant variability in emission rates, both over time for a 

given unit, and between the best performing units. Some of this 

variability may be related to catalyst aging, or may be related 

to the participation of these units in trading programs 

(therefore these units operate without an absolute limit on 

individual boilers). Regardless of the cause of this 

variability, EPA notes that significant variability over a 30-

day average, even among the best performing units, does exist, 

and EPA disagrees that an emission limit set in association with 

a BART determination must represent the lowest rate achieved on 

30-day rolling average basis from the best performing unit using 

that technology.

EPA examined the most recent Clean Air Markets Division 

(CAMD) emission rate data for 12 cell burner boilers currently 

operating with SCR over 2009 – June 201128. In order to determine 

 

28 See the Response to Comments Section 8.1 in the docket for this final 

rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 86 of 153

what might be an appropriate percent reduction to represent all 

cell burner boilers currently using SCR, we calculated the 

average percent reduction from the highest emission rate 

achieved over all 12 units. The percent reduction achieved from 

the monthly calendar average emission rate over 2009 – June 2011 

from the 12 units ranged from 48 to 90 percent, with an average 

value of 78 percent. 

Commenters claim that emissions of sulfuric acid mist and 

the high ash content of coal used by FCPP, and considerations of 

catalyst life are not barriers to achieving higher NOx reduction 

efficiencies than proposed by EPA. EPA disagrees with comments 

that our statement regarding the impact of additional layers of 

catalyst on increasing sulfuric acid emissions is unsupported. 

EPA understands from our correspondence with Hitachi Power 

Systems America that each layer of catalyst used results in an 

incremental increase in the conversion rate of SO2 to SO3. The 

EPRI method used for calculating sulfuric acid requires the 

input of a SCR catalyst oxidation rate. This oxidation rate 

varies depending on catalyst type and number of layers used. For 

the ultra low SO2 to SO3 oxidation catalysts offered by Hitachi, 

each layer contributed roughly 0.167 percent conversion, with 

three layers totaling 0.5 percent. The use of an additional 

layer, such as in a 3+1 system, would thus increase the 

conversion rate to nearly 0.7 percent when all four catalyst 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 87 of 153

layers are in operation. Further NOx reductions achieved from the 

addition of a 5th layer of catalyst would likely exacerbate 

pluggage and back-pressure concerns related to the ash content 

of the coal and may affect cost and operation of the unit. 

Commenters have not submitted information to refute this.

The ash content of coal has an important effect on the 

effectiveness of SCR because high ash content in coal can cause 

pluggage and catalyst erosion and thus reduce available catalyst 

area and activity for NOx reduction. Commenters point to San Juan 

Generating Station (SJGS) and Desert Rock as facilities with 

lower SCR-based NOx emission limits that use high ash content 

coal. EPA Region 6 recently finalized a FIP for SJGS with a 

limit of 0.05 lb/MMBtu, representing an 83 percent reduction in 

NOx emissions. The emission limit EPA Region 6 set for SJGS is 

lower than the limit we set for FCPP because SJGS uses a 

different boiler type than FCPP and modern combustion controls 

have already been installed and have reduced NOx emissions at 

SJGS by 29 – 33 percent29. EPA has determined that because Units 

4 and 5 at FCPP are cell burner boilers, modern combustion 

controls would not significantly reduce NOx emissions from FCPP. 

Even though the emission limit differs, the reduction efficiency 

 

29 See page 4-3 of report titled “PNM BART Report for SJGS_final to 

PNM_June 18, 2007.pdf” in the docket for this final rulemaking. Pre-consent 

decree emission rates on Units 1 – 4 at SJGS ranged from 0.42 – 0.45 

lb/MMBtu. Post-consent decree emission limits for those units were 0.30 

lb/MMBtu
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 88 of 153

from the installation and operation of SCR at FCPP and SJGS are 

generally consistent, particularly when considering the 

similarly high ash content of coal (greater than 20 percent) 

used at both facilities. In 2008, EPA Region 9 issued a preconstruction Prevention of Significant Deterioration (PSD) 

permit to allow construction of a new coal-fired power plant on 

the Navajo Nation, known as the Desert Rock Energy Facility 

(Desert Rock)30. If constructed, Desert Rock would have used the 

same coal as FCPP from the BHP Navajo Mine and the final PSD 

permit set a NOx limit of 0.05 lb/MMBtu (on a rolling 365-day 

average). Commenters argue that if Desert Rock was required to 

meet a limit of 0.05 lb/MMBtu using the same coal as FCPP, the 

ash content should not hinder FCPP from achieving similarly low 

NOx emission rates. EPA notes that if constructed, Desert Rock 

would have been a new, state-of-the-art facility specifically 

designed with boiler characteristics, combustion controls, and 

post-combustion controls to meet the Best Available Control

Technology (BACT) requirements for numerous criteria and noncriteria pollutants. FCPP is an existing, over 40-year-old power 

plant. The Regional Haze Rule requires a case-by-case BART (best 

 

30 Desert Rock has not been constructed. EPA requested a voluntary remand 

of the Desert Rock PSD permit in 2009 to incorporate new applicable 

requirements. The developers of Desert Rock have not yet submitted a revised 

PSD application to EPA.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 89 of 153

available retrofit technology) determination, which need not be 

equivalent to BACT for new facilities. 

Based on the significant 30-calendar day average 

variability exhibited by the top performing units cited by 

commenters, and the variability in 30-calendar day average and 

the 2009 – June 2011 30- calendar day average percent NOx

reduction of 78 percent exhibited by 12 cell burner boilers 

equipped with SCR, EPA continues to affirm that a limit 

representing an 80 percent reduction in NOx emissions reflects 

what is achievable using the technology determined as BART for 

FCPP. 

Comment: One of the owners of FCPP stated a willingness to 

support a NOx emission limit of 0.098 lb/MMBtu for Units 4 and 5 

under the alternative proposal, but only in the context of an 

alternative emission reduction strategy that includes resolution 

of the related issues. 

The Navajo Nation similarly endorsed the proposed 80 

percent reduction in NOx emissions from Units 4 and 5, with a 

limit of 0.098 lb/MMBtu, under the supplemental proposal, based 

on the site-specific parameters at FCPP. 

Response: EPA agrees that the appropriate limit for Units 

4 and 5 under the alternative strategy is 0.098 lb/MMMtu (based 

on a rolling average of 30 successive boiler operating days). 

The final rule reflects this limit.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 90 of 153

Comment: One of the owners of FCPP opposed EPA’s proposal 

to “phase in” NOx controls at FCPP under a traditional BART FIP, 

commencing 3 years from the date the FIP becomes effective. The 

commenter asserted that this proposal does not afford adequate 

time to properly design, engineer, and construct the controls 

before the compliance deadline. 

Response: EPA partially agrees with this comment. We 

revised the BART compliance date for one 750 MW unit to within 4 

years from the effective date of this final rule. The remaining 

750 MW unit and Units 1 - 3 must meet a compliance date of 

within 5 years of the effective date of the final rule. The 

revised compliance time within 4 and 5 years allows time for 

design, engineer, and construct controls.

Comment: One environmental advocacy group stated that the 

proposed plant-wide BART limit of 0.11 lb/MMBtu across all five 

FCPP units violates Executive Order 12898 on environmental 

justice. Specifically, the commenter asserted that given the 

significant differences in pollution control systems among 

FCPP’s five units, allowing a plant-wide average could create 

pollution “hotspots” with respect to co-pollutants. As an 

example, the commenter noted that while Units 4 and 5 have

baghouses, Units 1 – 3 use less efficient venturi scrubbers for

control of sulfur dioxide, particulate matter, and mercury. The 

commenter asserted that the plant-wide average limit for NOx
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 91 of 153

would allow increased emissions from Units 1 – 3 in the event of 

a temporary outage or reduced output from one or both of the 

larger units. The commenter stated that while this may not 

increase the total NOx emissions from the plant, it would

increase the amount of mercury and other toxic co-pollutants 

emitted into the surrounding community, which is a low-income 

community of color.

Response: EPA disagrees with the commenter that a plantwide BART limit of 0.11 lb/MMBtu across all five FCPP units 

violates Executive Order 12898 on environmental justice. This 

final rule will not have disproportionately high and adverse 

human health or environmental effects on minority or low-income 

population because it increases the level of environmental 

protection for all affected populations in the area including 

any minority or low-income population. 

The commenter is correct that in the event of a temporary 

outage or reduced output from Unit 4 or 5 the operator could 

continue to operate FCPP units 1 - 3 under the original BART 

proposal provided that they maintain compliance with the plantwide emission limit of 0.11 lb/MMBtu for NOx. In order to 

maintain compliance with the plant-wide emission limit, Units 1 

- 3 would have to operate at a lesser capacity than they would 

normally operate if Unit 4 and 5 were functioning because units 

1 - 3 have higher NOx emission rates than Units 4 and 5. The NOx
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 92 of 153

emission rates from Units 1 - 3 with SCR, based on 80 percent 

control of current emission rates would be 0.16, 0.13, and 0.12 

lb/MMBtu respectively which are higher than the proposed plantwide emission limit. Therefore, to maintain compliance with the 

plant-wide NOx emission limit (which is based upon a 30-calendar 

day rolling average), Units 1 - 3 would have to operate at a 

reduced capacity in any 30-day period in which Units 4 and 5 are 

operating a reduced capacity, so as to maintain the balance 

among the five units. This reduced capacity would result in an 

overall lower rate of emission for mercury and other copollutants from Units 1 - 3. Therefore, there would be no 

increased emissions of mercury or other co-pollutants and no 

“hot-spots” or disproportionately high and adverse human health 

or environmental effects on minority or low-income population.

2. Comments on the Proposed BART Determination for PM

Comment: One of the owners of FCPP asserted that the 

existing controls at FCPP constitute BART for PM emissions. The 

commenter contended that the impact of PM controls on the 

visibility in the neighboring Class I areas would be 

“vanishingly small” while the cost would be “exorbitant” 

(resulting in cost effectiveness ranging from $51,500 – $148,659 

per ton reduced and from $1.4 billion – $3.7 billion per dv 

improvement). 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 93 of 153

The Navajo Nation stated that EPA acknowledged the high 

incremental cost of new PM controls on Units 1 – 3 (citing 75 FR 

64230), yet justified the cost effectiveness of baghouses by 

comparison with similar retrofit projects in EPA Region 9. This 

commenter asserted that EPA failed to properly evaluate the 

costs associated with installation of baghouses using sitespecific parameters, thereby deviating from the BART Guidelines. 

The commenter asserted that continued operation of venturi 

scrubbers to meet emission limits of 0.03 lb/MMBtu and an 

opacity limit of 20 percent satisfies BART for Units 1 – 3.

The Navajo Nation expressed support for the supplemental 

proposal to require a PM emission limit of 0.015 lb/MMBtu and 10 

percent opacity limit on Units 4 and 5. The commenter presumed 

that FCPP can readily meet these standards prior to installation 

of SCR since the limits can be achieved with the existing 

baghouses.

Regarding the EPA’s proposed 10 percent opacity standard 

for each unit, two of the owners of FCPP stated that the EPA has 

not specified any costs or predicted any improvement in 

visibility that would result from such limits. The commenters 

asserted that without such basis, the EPA cannot justify the 

proposed opacity limits. 

Response: As stated in our proposed BART determination for 

PM, the existing venturi scrubbers on Units 1 – 3 at FCPP do not 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 94 of 153

constitute BART. In our proposed BART determination for FCPP, 

EPA proposed a PM emission limit for Units 1 – 3 that can be 

achieved through the installation of any of four different PM 

control options. At the time of our BART proposal, the MATS Rule 

for electric utility steam generating units had not yet been 

proposed, nor had APS suggested its alternative emission control 

strategy to close Units 1 – 3 in lieu of complying with BART for 

NOx. Because the final MATS rule has been issued31 and sets 

filterable PM and mercury limits that would be applicable to the 

units at FCPP, and because EPA is finalizing this rule to allow 

APS to either comply with the alternative emission control

strategy or BART for NOx, EPA is determining that it is not 

necessary or appropriate at this time to finalize our proposal 

to set new PM limits for Units 1 – 3. 

Regarding our proposed BART determination for PM for Units 

4 and 5, we are finalizing the proposed 0.015 lb/MMBtu emission 

limit based upon the proper operation of the existing baghouses. 

However, we have determined based on the comments we received 

from the operator of FCPP that it is not necessary or 

appropriate to take final action on the proposed 10 percent 

opacity limit. We have determined that imposing a 10 percent 

opacity limit will not provide greater assurance that Units 4 

 

31 See 77 FR 9304, February 16, 2012
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 95 of 153

and 5 at FCPP are meeting the PM emission limit of 0.015. We 

have determined previously that a 20 percent opacity limit is 

sufficient to ensure the PM emission limit is being continuously 

met. The 10 percent opacity limit was generally supported by the 

Navajo Nation and environmental groups. EPA has promulgated some 

recent rules for electric generating units that have retained a 

20 percent opacity standard rather than reducing that limit to 

10 percent. Specifically, EPA’s revised the New Source 

Performance Standard for large electric generating units at 40 

CFR Part 60, Subpart Da, to lower the PM emission limit for new 

units to 0.09 lb/MMBtu for gross energy output or 0.097 lb/MMBtu 

for net energy output. For existing units that reconstruct or 

modify, Subpart Da establishes an emissions limit of 0.015 

lb/MMBtu. For both standards, EPA retained a 20 percent opacity 

standard as being sufficient to ensure compliance with either 

the 0.090 (0.097) lb/MMBtu or 0.015 lb/MMBtu PM emission limit. 

EPA’s MATS rule, which was finalized just a few months ago, also 

retained a 20 percent opacity standard as being sufficient to 

ensure compliance with the PM emission limit that will be 

required for electric generating units subject to that rule.

The importance of the opacity limit is that a certain 

percentage opacity is an instantaneous demonstration that a unit 

is in compliance with its PM emission limit. If a unit does not 

install and operate a PM continuous emissions monitor, then EPA 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 96 of 153

ensures compliance with the PM emission limit by requiring an 

episodic source test. For the periods between episodic source 

testing, EPA can reasonably assure continuous compliance with 

the PM emission limit by observing that the unit’s stack 

emissions do not exceed a set opacity. EPA’s recent rulemakings 

have determined that 20 percent opacity is sufficient to ensure 

compliance with a PM emission limit lower than the emission 

limit we have determined is BART for Units 4 and 5. Accordingly, 

EPA is determining the 20 percent opacity limit that we 

promulgated in our 2007 FIP for FCPP as being adequate to ensure 

continuous compliance with the PM BART limit or 0.015 lb/MMBtu.

EPA concludes that this change is a logical outgrowth of the 

comments received on the proposal.

Comment: One commenter indicated that EPA has proposed a 

BART limit only for PM, which appears to be only filterable

particulate matter. The commenter asserted that the BART 

guidelines specify that BART should be evaluated and defined for 

both PM10 and PM2.5 (citing 40 CFR part 51, Appendix Y, section 

IV.A) and, consequently, that EPA must evaluate and define BART 

limits for both PM10 and PM2.5. The commenter also asserted that 

as part of the PM2.5 BART determination, EPA must impose emission 

limits on condensable particulate matter, which is typically in 

the size range of 2.5 micrometers or smaller. Thus, the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 97 of 153

commenter stated that in addition to a filterable PM BART limit, 

EPA should impose a BART limit on total PM2.5.

One public interest advocacy group supported EPA’s proposal 

and supplemental proposal to require a PM limit and a 10 percent 

opacity limit on Units 4 and 5. The commenter indicated that 

these limits should become effective prior to SCR installation, 

regardless of whether the BART or alternative emission control 

plan is implemented. 

Response: EPA disagrees with the commenters’ 

recommendation that the condensable fraction must be included in 

the PM BART limits. EPA has previously outlined our rationale

for why an H2SO4 limit is not appropriate at this time (it will 

be addressed through the pre-construction permitting process if 

needed) and EPA expects that H2SO4 will be the main component of

condensable PM that would be expected from a coal-fired EGU with 

an SCR.

EPA agrees with commenters that PM limits on Units 4 and 5 

should become effective prior to SCR installation, as Units 4 

and 5 generally already meet the 0.015 lb/MMBtu limit.32 EPA is

finalizing a compliance date for PM emission limits on Units 4 

and 5 to be within 6 months after restart following the next 

scheduled major outages in 2013 and 2014. As discussed 

 

32 See document titled: “TSD ref. [2-3, 95] 

FCPP_BART_Scenarios_Emissions_EPA_Proposal.xlsx” in the docket for this 

proposed rulemaking at EPA-R09-OAR-2010-0683-0017.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 98 of 153

previously, EPA has determined that finalizing the proposed 

opacity limit of 10 percent on Units 4 and 5 is not necessary or 

appropriate at this time. 

3. Comments on BART for SO2

Comment: Some commenters stated that SO2 BART should be 

required for FCPP, while one commenter simply noted that FCPP is 

subject to BART for SO2. One federal agency commenter stated 

that FCPP is subject to BART for SO2. The commenter stated that 

Units 4 and 5 should be able to meet a limit of 0.12 lb/MMBtu on 

an annual average basis by upgrading the existing scrubbers.

One set of environmental advocacy groups discussed the 

Regional Haze rules, the TAR, and the SO2 emissions from FCPP and 

concluded that EPA is under a legal obligation to conduct a BART 

analysis for SO2 emissions from FCPP and, to the extent EPA has 

failed to make a finding that it is “necessary or appropriate” 

to regulate SO2 emissions from the FCPP, such a failure is 

arbitrary, capricious, and not supported by the administrative 

record.

According to the commenter, EPA argues that FCPP’s current 

SO2 emissions limits are “close to or equivalent” to the limit 

that would be established under BART. The commenter asserted 

that this conclusion is arbitrary and capricious because EPA has 

failed to undertake any scientific or technical analysis to 

support its conclusion.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 99 of 153

A public interest advocacy group stated that the SO2 limits 

need to be tightened for FCPP to further reduce visibility 

impairment and to reduce the acidification of rainfall caused by 

the formation of H2SO4. The commenter stated that because the 

damaging effects of H2SO4 in precipitation on ancestral Puebloan 

sandstone dwellings and pictographs are not fully understood, it 

is disappointing for the FCPP proposals not to address SO2. 

Response: EPA finalized a FIP in May 2007 that required 

significant SO2 emissions reductions from FCPP and established 

continuous SO2 emissions limits for FCPP. See 72 FR 25698 (May 7, 

2007). The 2007 FIP required FCPP to increase the removal 

efficiency of its SO2 emissions controls from 72 percent to 88 

percent, resulting in a SO2 emissions reduction of approximately 

22,000 tons per year. EPA had proposed this FIP in September 

2006. The 2006 proposed FIP stated that “EPA believes that the 

SO2 controls proposed today for FCPP are close to or the 

equivalent of a regional haze BART determination of SO2. This 

takes into consideration the early reductions this action will 

achieve and the modification to the existing SO2 scrubbers.” 72 

FR 25700. In finalizing that rulemaking in the 2007 FIP, EPA 

stated that it was exercising its authority pursuant to Section 

49.11 of the TAR to implement measures that are necessary or 

appropriate to protect air quality in Indian country. Id. EPA 

determined that the SO2 emissions reductions would be federally 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 100 of 153

enforceable as soon as the 2007 FIP was finalized which would be 

potentially five years before EPA could achieve enforceable SO2

emissions reductions through making a BART determination. See 

id. EPA also considered the Navajo Nation’s request for EPA to 

establish enforceable SO2 emissions reductions immediately that, 

in the opinion of the Navajo Nation, “appear[] to be equivalent 

to BART.” Id. Therefore, EPA’s determination on this issue in 

finalizing the 2007 FIP was “that it is neither necessary nor 

appropriate at this time to undertake a BART determination for 

SO2 from FCPP given the timing of the substantial SO2 reductions 

resulting from this FIP.” Id. In addition, we stated that “given 

that the SO2 controls for FCPP immediately achieve significant 

reductions in SO2 comparable to what could ultimately be achieved 

through a formal BART determination, EPA believes that it will 

not be necessary or appropriate to develop a regional haze plan 

to address SO2 for the Navajo Nation in the near term.” Id. 

25700-701. Both APS, as operator of FCPP, and Sierra Club sought 

judicial review of our 2007 FIP. 

The comments on this action essentially repackage the 

comments we received and provided a response for on the 2007 

FIP. The comments have not presented any new facts or legal 

considerations that have arisen or changed since we responded to 

comments requesting a BART determination for SO2 in 2007.

4. Other Comments on BART
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 101 of 153

Comment: One group of environmental advocacy groups stated 

that as an alternative to a condensable PM2.5 limit, EPA could 

set limits on the pollutants which form condensable PM2.5, such 

as sulfuric acid mist (H2SO4) and ammonia, as EPA proposed as 

part of the San Juan Generating Station (SJGS) BART rulemaking

(citing 76 FR 503-4, January 5, 2011). If EPA adopts this 

approach, the commenter urged EPA to set an emission limit for 

H2SO4 no higher than the limit of 1.06 x 10-4 lb/MMBtu for each 

unit as proposed for SJGS based on the use of low reactivity 

catalyst and the most current information from the Electric 

Power Research Institute. If CEMS are unavailable for this 

pollutant, the commenter urged EPA to require stack test 

monitoring for H2SO4 on a more frequent basis than annual

monitoring. 

The commenter also requested that EPA set emission limits 

for ammonia at a rate no higher than the 2.0 parts per million 

as proposed at SJGS, to be monitored with CEMs.

Response: EPA disagrees with the comment that Region 9

should set the same emission limits for ammonia and sulfuric 

acid as Region 6 in its proposed BART determination for SJGS.

In its January 5, 2011 proposed rulemaking for SJGS, Region 

6 proposed an ammonia slip limit of 2.0 ppmvd on an hourly 

average and requested comment on a range from 2.0 ppmvd to 6.0 

ppmvd. In its final BART rulemaking (76 FR 52388, August 22, 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 102 of 153

2011), Region 6 determined that an emission limit and monitoring 

were not warranted for ammonia and did not finalize its BART 

determination for SJSG with the proposed 2.0 ppmvd ammonia 

limit. 

In its proposal for SJGS, Region 6 proposed an emission 

limit for sulfuric acid of 1.06 x 10-4 lb/MMBtu on an hourly 

average, and requested comment on a range from 1.06 x 10-4 to 

7.87 x 10-4 lb/MMBtu. In its final rulemaking, Region 6 finalized 

an emission limit for sulfuric acid of 2.6 x 10-4 lb/MMBtu to 

minimize its contribution to visibility impairment. Region 6

calculated this emission limit using an estimation methodology 

from EPRI, assuming the use of an ultra-low activity catalyst 

(0.5 percent total conversion of SO2 to SO3), zero ammonia slip, 

no sorbent injection, and EPRI-recommended values for removal by 

existing downstream control equipment.

Actual measurements of baseline sulfuric acid emissions 

have not yet been determined at FCPP and the calculation of 

projected sulfuric acid emissions after installation and 

operation of SCR using the EPRI methodology is dependent on 

future decisions made by the facility on the type of SCR 

catalyst and number of layers used, as well as numerous 

assumptions about loss to downstream components, such as air 

preheaters and baghouses, the true values of which are currently 

not yet defined or known for FCPP. Furthermore, EPA Region 9 is 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 103 of 153

the permitting authority for preconstruction permits on the 

Navajo Nation, and an increase in sulfuric acid emissions from 

the installation of SCR may trigger major modification PSD 

permit requirements at a low threshold of 7 tpy (see 40 CFR 

52.21) or Tribal minor new source review (NSR) permit 

requirements at a threshold of 2 tpy (see 40 CFR Part 49 Subpart 

C). Preconstruction permitting review may also be triggered from 

significant emissions increases of PM2.5 from SCR installation at 

FCPP. If one of these pollutant triggers PSD, the permitting 

authority must provide an Additional Impact Analysis under the 

PSD program. The PSD program also requires the permitting 

authority to determine BACT for pollutants that triggered PSD. A

similar control technology review may also be required at the 

discretion of the permitting authority under the Tribal Minor 

NSR program. For these reasons, Region 9 has determined that for 

FCPP, emission limits and monitoring requirements for sulfuric 

acid are more appropriately reviewed in the preconstruction 

permitting process.

Comment: Citing the BART Guidelines at 40 CFR part 51, 

Appendix Y, section V, one environmental advocacy group stated 

that BART emission limits and compliance schedules must be based 

on “boiler operating day.”

The commenter asserted that the “very high” proposed BART 

emission limits suggest that EPA set these limits to encompass 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 104 of 153

spikes that occur during startups and shutdowns. The commenter 

asserted that setting and enforcing limits based on boiler 

operating day would necessarily exclude spikes that occur before 

and after outages, such as startups, shutdowns, and 

malfunctions. According to the commenter, such periods should be 

subject to separate limits set at the pre-SCR uncontrolled level 

to encourage good work practice standards during these periods 

while allowing the SCR and other emission control technologies 

to be operated at an efficient and continuous capacity in

compliance with BART. 

Response: EPA agrees that the NOx limit under the 

alternative emission control strategy should be set for 30

successive boiler operating days and that a “boiler operating 

day” should be defined as any day in which the boiler fires 

fossil fuel. Because the NOx emission limit under the alternative 

emission control strategy already includes periods of startup 

and shutdown, separate limits are not required. The final rule 

reflects this approach.

For the original proposed BART determination, EPA does not 

find it necessary to define boiler operating day because the 

BART limit is a heat input-weighted plant-wide limit. Only 

operating hours for any of the five units would be included. 

When a unit is not operating, those hours are not included in

the plant-wide 30-day average. Additionally, the heat input-
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 105 of 153

weighted plant-wide limit also includes periods of startup and 

shutdown; therefore, separate limits are not required.

Comment: One environmental advocacy group stated that EPA 

should require FCPP to install all control equipment within 3

years of the date of a final FIP, as EPA did at SJGS. The 

commenter stated that there is ample data to support the 

contention that all this emission control technology can be 

installed and operational within 3 years or less.

Response: EPA disagrees with the comment that Region 9

should set a 3-year compliance timeframe because Region 6

proposed a 3-year compliance timeframe for SJGS. In its proposed 

rulemaking for SJGS,33 Region 6 proposed a 3-year timeframe for 

SJGS to comply with the proposed limits but requested comment on 

a compliance range of 3 – 5 years. In its final rulemaking34, 

Region 6 finalized a compliance timeframe of 5 years and 

determined that because of site congestion at SJGS, a longer 

timeframe than average (37 – 43 months) to install SCR on the 4 

units at SJGS would be required. The final BART determination 

for FCPP requires retrofit of five existing units at FCPP. In 

the final rule for FCPP, Region 9 is requiring installation and 

operation of SCR controls for one 750 MW unit within 4 years of 

the effective date, and the remaining 750 MW unit and Units 1 –

 

33 See 76 FR 491, January 5, 2011 34 See 76 FR 52388, August 22, 2011
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 106 of 153

3 within 5 years of the effective date. Based on all of the 

factors that will be involved in the design, purchase and 

operation of the SCR controls, Region 9 considers this schedule 

to be appropriate and expeditious.

G. Comments on APS’s Alternative and EPA’s Supplemental 

Proposal

Comment: One of the owners of FCPP pointed out that the 

November 2010 APS proposal included two critical components: (1) 

a proposal to close Units 1 – 3 and install SCRs on Units 4 and 

5; and (2) EPA’s contemporaneous agreement that these activities 

resolve any liability FCPP may have under regional haze BART, 

Reasonably Attributable Visibility Impairment Best Available 

Retrofit Technology (RAVI BART), NSR, and New Source Performance 

Standard (NSPS). The commenter asserted that EPA’s supplemental 

proposal addresses only half of APS’S proposal – the half that 

achieves better than BART emission reductions, plant-wide 

reductions of all other emissions, and greater visibility 

improvement at nearby Class I areas – but ignores the other half 

of the APS proposal – the half that provides APS and the FCPP

co-owners with needed regulatory certainty. Unless there is a 

contemporaneous resolution of these key issues with EPA, the 

commenter cannot and does not support EPA’s supplemental 

proposal. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 107 of 153

Response: EPA understands that the owners of FCPP were 

seeking to resolve any potential regulatory noncompliance issues 

simultaneously. However, EPA must use different mechanisms for 

promulgating rules and resolving enforcement issues. The comment 

requests resolution of potential past non-compliance with NSR 

and NSPS requirements. Potential past non-compliance can be 

resolved through entering into a Consent Decree containing a 

judicially approved release from liability. Such a Consent 

Decree under the CAA must be approved by the United States 

Department of Justice and must also be lodged in a United States 

District Court where the public is allowed to comment on it. 

Consent Decrees must be entered by the United States District 

Court for a release of liability of potential past noncompliance to be effective. Accordingly, this rulemaking action 

cannot effectuate any release of liability for potential past 

non-compliance with NSR or NSPS.

EPA is aware that several environmental groups have 

petitioned the Department of Interior to make a finding that 

impairment at Class I areas is reasonably attributable to FCPP.35 

The NPS, on behalf of Department of Interior, has declined to 

 

35 See National Parks Conservation Association, et al., Petition to United 

States Department of Interior, United States Department of Agriculture, and 

United States Forest Service, February 16, 2010, in the docket for this 

rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 108 of 153

make such a finding based on EPA’s work in this rulemaking.36 The 

environmental groups also filed a Complaint in the United States 

District Court for the District of Columbia37 contending that the 

Department of Interior was unreasonably delaying making a 

finding of reasonable attribution from FCPP. On June 30, 2011, 

the Court dismissed the Complaint38 holding that the NPS’s 

letters refusing to make the finding of reasonable attribution 

constituted denying the Petitioners’ request for a RAVI finding. 

Therefore, there are no pending petitions with the Department of 

Interior requesting a finding that visibility impairment at any 

Class I areas is reasonably attributable to FCPP. In any event, 

a BART determination under RAVI would likely be the same as 

under this BART determination.

Comment: One of the owners of FCPP stated that it is 

imperative to note that its support of the supplemental proposal 

(if other potential liabilities are resolved as discussed above)

is based solely on the rationale that this achieves a result 

better than the proposed BART FIP, and that this “better than 

 

36 See letter from Will Shafroth, Department of Interior to Stephanie 

Kodish, NPCA, March 8, 2011 in the docket for this proposed rulemaking. 37 See National Parks Conservation Association, et al., Petition to United 

States District Court for the District of Columbia, January 20, 2011, in the 

docket for this final rulemaking. 38 See National Parks Conservation Association, et al., Plaintiffs, v. 

United States Department of Interior and United States Department of 

Agriculture, Defendants. Civil Action No. 11-130 (GK). United States District 

Court for the District of Columbia, June 30, 2011, 794 F. Supp. 2d 39; 2011 

U.S. Dist. LEXIS 70170; 74 ERC (BNA) 1015. In the docket for this final 

rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 109 of 153

BART” outcome is a result of the closure of Units 1, 2, and 3. 

The commenter stressed that in no case – either in the original 

BART FIP proposal or in the supplemental proposal – does the 

commenter support any determination that SCR constitutes BART

for FCPP. A second FCPP owner stated that its acceptance of the 

supplemental proposal upon resolution of the other potential 

issues would be a voluntary action based on its own business 

interests; the commenter does not support any BART determination 

that calls for installation of SCR at FCPP.

Response: EPA disagrees with the commenters that SCR is 

not BART. Based on our five-factor analysis, as described in the 

TSD for our proposed BART determination, SCR is cost effective 

and results in the greatest anticipated improvement in 

visibility. One of the owners of FCPP notes that the “betterthan-BART” outcome is a result of the closure of Units 1, 2, and 

3. However, the closure of Units 1 – 3 alone does not result in 

greater emission reductions than EPA’s proposed BART 

determination, and represents only a roughly 30 percent

reduction from baseline emissions. The closure of Units 1 – 3, 

in combination with SCR on Units 4 and 5, results in the 

“better-than-BART” outcome. 

The voluntary nature of the alternative emission control

strategy does not negate EPA’s BART determination because (1) 

EPA must first determine what BART is in order to fulfill the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 110 of 153

requirements of the alternative program to BART as prescribed in 

the Regional Haze Rule, and (2) EPA cannot require the full or 

partial closure of a facility as a BART alternative, therefore 

the alternative emission control strategy remains an optional 

business choice of the owners of FCPP to implement in lieu of 

BART, if they see fit.

Comment: One environmental advocacy group and one federal 

agency asserted that the supplemental proposal is not better 

than BART for NOx. Generally, commenters argue that based on the 

extended compliance timeframe for the alternative emission

control strategy, the use of an artificially inflated baseline, 

the potential increase in output from Units 4 and 5, and 

assuming that SCR can achieve 0.05 lb/MMBtu of NOx on an annual 

basis, the BART alternative fails to achieve greater cumulative 

NOx reductions than would installation of BART (SCR) on all five 

units.

Response: EPA disagrees with the comment that the 

alternative emission control strategy is not better than BART, 

but agrees that a reexamination of baseline emissions and 

projected capacity factors in the future is warranted. As 

reported in the TSD for our proposed BART determination, 

facility-wide NOx emissions over 2001 – 2009 ranged from 40,331 

to 47,300 tpy. While the baseline emissions provided by APS and 

used by EPA in our Supplemental Proposal was within the range of 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 111 of 153

annual NOx emissions, in response to these comments, we conducted 

an additional analysis to compare the alternative emission 

control strategy against our final BART determination for NOx

using the 2001 – 2010 average as the baseline emission rate and 

an assumed capacity factor of 81 percent39 for Units 4 and 5 

under the alternative emission control strategy.40 This analysis 

shows that in 2014 and 2015, the alternative emission control 

strategy results in lower NOx emissions than BART due to the 

closure of Units 1 – 3 at the end of 2013. In 2016, 2017, and 

2018, BART results in lower emissions than the alternative, and 

in 2019 and beyond, the alternative emission control strategy 

(5,556 tpy), with phased-in controls on Units 4 and 5 by the end 

of 2018, results in lower emissions than BART (8,479 tpy). In 

total, the BART Alternative results lower emissions from FCPP 

over more calendar years (2014-2015, and 2019 and beyond) than 

does BART (2016-2018). Even if APS operated Units 4 and 5 at 100 

percent capacity, EPA calculates that emissions under the 

alternative emission control scenario in 2019 and beyond to be 

6,859 tpy, which is still lower than under BART (8,479 tpy). On 

a cumulative basis, i.e., the sum total of NOx emissions over 

 

39 In testimony to the ACC, Mark Schiavoni of APS testified that he 

anticipates capacity factors over 2015 – 2030 to range from 75 – 81 percent

for Units 4 and 5. See document titled “Schiavoni Testimony_TRANSCRIPT.pdf” 

in the docket for this final rulemaking 40 See document titled “BART vs Alternative.xlsx” in the docket for this 

final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 112 of 153

2011 to 2064, the BART Alternative also results in lower 

emissions than BART, both at an 81 percent capacity factor and 

at 100 percent capacity.

Commenters argue that if the BART emission limit were 

lower, the alternative would not be better than BART. For 

example, if EPA required an emission limit representing a 90

percent reduction in NOx emissions, annual NOx emissions would be 

lower than 5,000 tpy. However, as discussed in responses to 

similar comments, EPA has determined that an 80 percent

reduction in NOx emissions is BART for FCPP. It is inappropriate 

to compare the alternative emission control strategy against a 

target for BART that commenters would like to see based on 

maximum emission reductions achieved without consideration of 

site-specific characteristics of FCPP that EPA has determined 

are not appropriate for FCPP. 

Commenters further argue that by offering FCPP a BART 

compliance deadline of July 2018, EPA is illegally extending a 

mandatory deadline under the CAA, and that installation of SCR 

at Units 4 and 5 can easily be accomplished within 2 years. EPA 

disagrees and notes that the compliance timeframe for EPA’s BART 

determination requiring SCR installation on all 5 units is 

within 5 years of the effective date of the final rule, 

consistent with the maximum time allowed under the CAA 

§169A(g)(4) in the definition of “as expeditiously as 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 113 of 153

practicable”. The commenter is confusing requirements under BART 

and requirements under the alternative to BART. EPA is not 

extending the BART compliance deadline beyond a 5-year period.

Rather, EPA is allowing additional time to implement the 

alternative emission control strategy, as allowed under the 

provisions of the RHR for the implementation of “other 

alternative measure rather than to require sources subject to 

BART to install, operate, and maintain BART” (See 40 CFR 

§51.308(e)(2)). In our Supplemental Proposal, EPA cited the 

requirement (under 40 CFR §51.308(e)(2)(iii)) that “all 

necessary emission reductions take place during the period of 

the first long-term strategy for regional haze”. 

EPA disagrees with commenters that reductions under the 

alternative to BART violates 40 CFR §51.308(e)(2)(iii). The 

requirement simply states the reductions take place during the 

period of the first long term strategy and does not specifically 

prescribe that those reductions must take place at the 

beginning, middle, or end of the period of the first long term 

strategy. 

H. Other Comments

Comment: Forty-five private citizens and several private 

citizens who submitted written comments at a public hearing 

explicitly stated that they support EPA’s efforts to clean up 

FCPP. Many of these commenters asked for the strictest 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 114 of 153

regulations. Another private citizen implied that EPA should act 

to clean up emissions from FCPP and noted that cleaner air will 

result in a cleaner Colorado snow pack, which will result in 

cleaner water in the Colorado River.

Twelve private citizens and a few private citizens who 

submitted written comments at a public hearing stated that FCPP 

should be de-commissioned. Several of these commenters asserted

that the plant should only be shut down if it cannot cease 

emitting pollutants, while others stated the plant should be 

shut down immediately. 

Nine private citizens and some of the private citizens who 

submitted written comments at a public hearing stated that 

renewable energy sources can be used in place of coal-fired

power plants.

Response: EPA acknowledges the comments supportive of our 

proposals but disagrees with commenters that suggest that FCPP 

should be de-commissioned or shut down immediately. 

In addition to other CAA programs, EPA assesses air quality 

with respect to NAAQS. The Four Corners area is designated 

attainment for each of the NAAQS.41 This means that the air 

quality in the Four Corners area is meeting the national healthbased standards set by EPA.

 

41 Please see http://www.epa.gov/region09/air/maps/maps_top.html for EPA 

Region IX air quality designations.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 115 of 153

For this action, EPA finds that under 40 CFR 49.11, it is 

necessary or appropriate to achieve emissions reductions of NOx

from FCPP required by the CAA’s Regional Haze program. NOx is a 

significant contributor to visibility impairment in the numerous 

mandatory Class I Federal areas surrounding FCPP. The emission 

reductions finalized will help achieve the goals of the Regional 

Haze Rule. The Regional Haze Rule however does not require nor 

does it authorize EPA to de-commission or shut down facilities 

to achieve the goals of the rule.

EPA agrees with commenters who stated that renewable energy 

sources can be used in place of coal-fired power plants. 

However, the Regional Haze Rule does not require that coal-fired 

facilities use or switch to renewable energy sources to meet the 

goals of the rule.

Comment: The Navajo Nation pointed out that as a federal 

agency, EPA has a trust responsibility to the Navajo Nation that 

requires it to give special consideration to the Nation’s best 

interests in any action.42 Because of the significant economic 

interest of the Navajo Nation in FCPP the commenter asserted 

that the BART proposal clearly implicates the Nation’s tribal 

trust interests. The commenter further contended that since EPA 

 

42 To support this assertion, the commenter cited Executive Order 13175 (65 

FR 67249, November 6, 2000; EPA Policy on Consultation and Coordination with 

Indian Tribes, section IV “Guiding Principles,” May 4, 2011 (EPA Tribal 

Policy); and the 1984 EPA Indian Policy.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 116 of 153

is adopting a FIP for BART in lieu of a TIP by the Navajo 

Nation, the EPA is essentially “standing in the shoes” of the 

Nation for purposes of making the BART determination and should, 

therefore, defer to tribal views when making environmental 

policy decisions and give the same weight to the BART factors 

that the Navajo Nation would in determining BART for FCPP; that 

is, to the extent that the Nation recommends a particular 

control technology as BART for power plants located on the 

Nation’s lands, EPA should give substantial weight to that 

recommendation as part of its decision-making process. (The 

commenter asserted that advanced combustion controls, rather 

than SCR, properly represent BART for FCPP.) Thus, the commenter 

stated that as the Nation’s trustee and “stand-in” for the BART 

determination for FCPP, the EPA should not select a more 

stringent BART than the commenter stated is required by the 

Regional Haze Rule to achieve “reasonable progress” where doing 

so would likely have substantial adverse impacts on the Navajo 

Nation. 

The commenter also stated that EPA has a duty to undertake 

government-to-government consultations with the Navajo Nation, 

and that EPA must coordinate with the Navajo Nation in its 

relationship with, and reliance on, other federal agencies. The 

commenter pointed out that EPA relies on data provided by the 

NPS, another federal trustee of the Nation, but has not 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 117 of 153

coordinated consultation between NPS and the Navajo Nation on 

this rulemaking. The commenter indicated that the May 2011 EPA 

Tribal Policy recognizes that such coordination is required 

under Executive Order 13175 and asserted that EPA should 

coordinate consultation with the U.S. Forest Service (who 

provided data used in the proposed rulemaking) as well as 

various Department of the Interior (DOI) agencies that have an 

interest in this rulemaking, including NPS, the Bureau of Indian 

Affairs, the U.S. Fish and Wildlife Service, the Office of 

Surface Mining Reclamation and Enforcement, and potentially the 

Bureaus of Land Management and Reclamation. The commenter added 

that consultation with Department of Energy (DOE) may be 

important in regard to including FCPP in a study that DOE is 

proposing to carry out for NGS, which also is located on the 

Navajo reservation and uses Navajo coal.

Response: It is EPA’s policy (EPA Policy on Consultation 

and Coordination with Indian Tribes, May 4, 2011, (EPA Tribal 

Consultation Policy))43 to consult on a government-to-government 

basis with federally recognized tribal governments when EPA 

actions and decisions may affect tribal interests. Consultation 

is a process of meaningful communication and coordination 

between EPA and tribal officials prior to EPA taking actions or 

 

43 See “EPA Policy on Consultation and Coordination with Indian Tribes”, 

May 4, 2011, in the docket for this final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 118 of 153

implementing decisions that may affect tribes. One of the 

primary goals of the EPA Tribal Policy is to fully implement 

both Executive Order 13175 and the 1984 Indian Policy, with the 

ultimate goal of assuring tribal concerns and interests are 

considered whenever EPA’s actions may affect tribes by 

strengthening the consultation, coordination, and partnership 

between tribal governments and EPA.

For this action, EPA consulted with Navajo Nation in 

accordance with the Executive Order and EPA’s Indian Policies on 

numerous occasions. A record of all consultations with tribes is 

included in the Docket for this final rulemaking.44 As stated in 

the 2011 EPA Tribal Consultation Policy, as a process, 

consultation includes several methods of interaction that may 

occur at different levels.45 EPA consulted with the Navajo Nation 

at various times throughout the process at various levels of 

government, including in-person meetings with the President of 

the Navajo Nation on May 19, 2011, and June 13, 2012.

EPA acknowledges the significant interest of the Navajo 

Nation in FCPP. Based on the results from the original analysis 

for the proposed BART determination, EPA concluded that the 

installation and operation of SCR on all five units at FCPP 

 

44 See document “Timeline of all Tribal Consultations on BART.docx” in the 

docket for this final rulemaking. 45 See “EPA Policy on Consultation and Coordination with Indian Tribes”, 

May 4, 2011, in the docket for this final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 119 of 153

would not adversely affect the competitiveness of FCPP’s cost to 

generate electricity compared to the cost to purchase 

electricity on the open market. Thus, EPA infers that a BART 

determination requiring SCR on all five units, in itself, should 

not force the closure of FCPP. EPA notes that we do not expect 

adverse impacts to the Navajo Nation if FCPP continues operating 

all units and complies with BART. However, potential adverse

impacts to the Navajo Nation may result if the owners of FCPP 

choose to implement the optional BART Alternative. At the 

request of the Navajo Nation during consultation, EPA 

commissioned a study to examine potential adverse impacts to 

Navajo Nation from the BART Alternative. The results of this 

analysis were discussed with President Shelly during a 

consultation meeting on July 13, 2012 and will be provided to 

President Shelly by letter as a follow-up to our consultation.

EPA agrees that we are acting to implement the BART 

requirements for a facility located on the Navajo Reservation in 

circumstances in which the Tribe has not applied, or been 

approved, to administer the applicable CAA program. EPA is 

mindful of the Navajo Nation’s views and recommendations, 

particularly where there is a potential substantial adverse 

economic impact to the Navajo Nation. We disagree however that 

the Agency must “defer to tribal views when making environmental 

policy decisions”. EPA is carrying out the requirements of the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 120 of 153

CAA and the Regional Haze Rule pursuant to our authority to 

implement these requirements in the absence of an EPA-approved 

program. EPA notes that the CAA and the TAR provide mechanisms 

for eligible Indian tribes to seek approval of tribal programs 

should they wish to administer CAA requirements. 

For this action EPA carefully considered the unique 

location of FCPP with respect to proximate Class I areas as well 

as its economic importance to Navajo Nation. We conducted a 

detailed analysis of available emission control technologies 

against the five-factors specified in the BART Guidelines. EPA 

also conducted extensive air modeling (included in the 

Supplemental Proposal). Additionally, we have considered the 

numerous comments we received on our proposals. In making our 

final decision we have had to balance the findings of our 

analysis along with the interests of various stakeholders, our 

unique government-to-government relationship with tribes, and 

our responsibility to carry out the requirements of the CAA and 

Regional Haze Rule to achieve reasonable progress towards 

visibility improvements. 

This final FIP strikes a reasonable balance between 

reducing emissions to improve visibility while allowing for the 

facility to implement those reductions in a manner that is 

consistent with its continued operation and economic viability. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 121 of 153

EPA has received information and comments from numerous 

federal agencies for this rulemaking and considered these in our 

final decision (all information and comments are included in the 

docket). EPA plans to coordinate with the Department of Interior 

or other federal agencies, as appropriate, in any future tribal 

consultations related to BART for FCPP or the Navajo Generating 

Station, the other coal-fired power plant located Navajo Nation.

EPA acknowledges that the Department of Interior has 

contracted with the National Renewable Energy Lab (NREL) of the 

Department of Energy to examine renewable energy options for the 

Navajo Generating Station, which is also located on the Navajo 

Nation and uses coal from the Kayenta Mine, located on Navajo 

and Hopi land. Information on the NREL study is available from 

DOI46 and will be included in the docket for EPA’s upcoming 

proposed rulemaking for NGS.

Comment: One public interest advocacy group, the Navajo 

Nation, and one environmental advocacy group supported 

establishment of a 20 percent opacity limit for material 

handling. The public interest advocacy group stated that the 

FCPP site is subject to numerous dust-storm events originating 

in northwestern Arizona, and the additional fugitive dust that 

could be picked up by these strong winds at the FCPP property 

 

46 http://www.doi.gov/navajo-gss/index.cfm
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 122 of 153

added to the incoming dust from the west makes breathing and 

outdoor activity miserable on from 4 to 12 days per year for 

residents of Montezuma County, CO and San Juan County, NM.

One of the owners of FCPP noted that in addition to the 

proposed BART requirements, EPA proposed separate fugitive dust 

control requirements and a 20 percent opacity limitation for 

certain material handling operations, which are unrelated to the 

CAA visibility program. The commenter laid out the history of 

EPA’s past attempt to apply fugitive dust controls to FCPP. The 

commenter argued that the proposed requirements are arbitrary 

and should not be finalized because the facts upon which EPA 

relies are inadequate to support the conclusion that fugitive 

dust control requirements are “necessary or appropriate” to 

protect air quality at FCPP. 

Response: EPA acknowledges support for establishing a 20 

percent opacity limit for material handling and a Dust Control 

Plan at FCPP. EPA has finalized both these requirements. EPA 

notes that the Dust Control Plan shall include a description of 

the dust suppression methods for controlling dust from site 

activities including coal handling and storage facilities, ash 

handling, storage, and landfills, and road sweeping activities. 

The 20 percent opacity standard will apply to any crusher, 

grinding mill, screening operation, belt conveyor, or truck 

loading or unloading operation. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 123 of 153

EPA agrees with the commenter that the fugitive dust and 20 

percent opacity limit are unrelated to the CAA visibility 

program. EPA also agrees with the history laid out by the 

commenter on fugitive dust controls at FCPP. EPA included these 

dust control requirements in the previous FIP finalized in 2007 

because EPA considered them necessary or appropriate under the 

TAR to assure that dust from this facility does not contribute 

to possible violations of the NAAQS for PM10. The commenter is 

correct that EPA withdrew the 2007 FIP requirements on dust when 

APS appealed the rule. EPA had not adequately documented in the 

record for the 2007 FIP our basis for establishing the 20 

percent opacity regulation. For the 2007 FIP, EPA chose not to 

defend our position based on the record for that rulemaking and 

instead chose to address the issue in a subsequent FIP action, 

such as this one. 

EPA disagrees with the commenter that the fugitive dust and 

opacity requirements are arbitrary or that our argument is 

inadequate to support our conclusion that fugitive dust control 

requirements are necessary or appropriate to protect air quality 

at FCPP.47

EPA’s basis for finding that it is necessary or appropriate 

for FCPP to comply with a requirement to limit its material 

 

47 For example, see document titled “Four Corners Power Plant Complaint to 

MSHA” in the docket for this final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 124 of 153

handling emissions to 20 percent or less is being set forth in 

this rulemaking. FCPP receives approximately 10 million tons of 

coal per year for combusting in Units 1-5. This massive quantity 

of coal moves by conveyor belt across FCPP’s property line 

through numerous transfer points before the coal is loaded into 

the storage silos that feed the individual combustion units. 

Each of these transfer points along with the conveyor belts has 

the potential for PM emissions. The PM can be minimized through 

the use of collection devices or dust suppression techniques 

such as covered conveyors or spraying devices at the transfer 

points. EPA first promulgated dust control requirements for new 

coal handling equipment on January 15, 1976 (41 FR 2232). This 

rule affected equipment constructed or modified after the 1970s 

that affected facilities built or modified after October 24, 

1974. The purpose of these New Source Performance Standards 

(NSPS) was:

NSPS implement CAA section 111(b) and are 

issued for categories of sources which have 

been identified as causing, or contributing 

significantly to, air pollution which may 

reasonably be anticipated to endanger public 

health or welfare. The primary purpose of 

the NSPS are to help States attain and 

maintain ambient air quality by ensuring 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 125 of 153

that the best demonstrated emission control 

technologies are installed as the industrial 

infrastructure is modernized. 

See 74 FR 51951 (October 8, 2009).

EPA’s basis for finding that it is necessary or appropriate 

for FCPP to comply with a requirement to limit its material 

handling emissions to 20 percent or less is being set forth in 

this rulemaking. EPA has promulgated a 20 percent opacity limit 

for all new coal handling operations built after the mid 1970s 

in the New Source Performance Standards. This NSPS standard 

applied to any coal handling equipment processing more than 200 

tons per day of coal. Because FCPP receives approximately 10 

million tons of coal per year for combusting in Units 1 - 5, it 

may be processing more than 27,000 tons per day. This is more 

than 100 times the smallest size coal handling operation subject 

to the NSPS, and which EPA considered necessary for protecting 

public health and welfare. As mentioned before, FCPP’s massive 

quantity of coal moves by conveyor belt across FCPP’s property 

line, passing through numerous transfer points before the coal 

is loaded into the storage silos that feed the individual 

pulverizers and combustion units. Each of these transfer points 

along with the conveyor belts has the potential for PM 

emissions. The PM can be minimized by collection devices or dust 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 126 of 153

suppression techniques such as covered conveyors or spraying 

devices at the transfer points. 

FCPP and the BHP Navajo Mine that provides FCPP’s coal are 

within close proximity to Morgan Lake which is a recreational 

lake with public access just beyond the FCPP’s property line. 

Excess dust can blow over the FCPP property line to Morgan Lake 

and adjacent properties. EPA and Navajo Nation EPA receive

numerous complaints from Navajo Tribal members concerning excess 

dust emissions generated from the ash landfill FCPP maintains, 

as well as from the other material handling and storage 

operations. 

EPA concludes that it is necessary or appropriate to set 

enforceable fugitive dust/PM suppression measures to protect 

ambient air quality because (1) there is a large potential for 

dust emissions from the facility coal and ash operations to be 

emitted and blow across the property line, (2) EPA and Navajo 

Nation EPA have received numerous complaints concerning excess 

dust from the ash landfill and other operations, and (3) these 

activities are occurring in close proximity to a public access 

area.

EPA disagrees with the commenter that the 20 percent 

opacity limit is arbitrary and capricious. While EPA 

acknowledges that New Mexico does not have a general opacity 

limit that applies to dust, the other three Four Corners States 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 127 of 153

do. In Arizona and Colorado a general 20 percent opacity limit 

applies at all facilities including “grandfathered” coal-fired

EGUs. In Utah the general opacity limit for facilities built 

before the CAA in 1971 is a 40 percent opacity limit. However, 

all of Utah’s large coal-fired EGUs were constructed after 1971 

and are subject to a 20 percent general opacity limit, i.e., the 

NSPS. Therefore, if FCPP had been built a few years later or a 

few miles in a different direction, it would be subject to the 

NSPS or a SIP provision limiting its coal material handling and 

storage operations to 20 percent opacity.

Because FCPP is located on the Navajo Nation where 

generally applicable limits that often are included in SIPs do 

not exist and because it was constructed nearly 40 years ago, 

and because dust control measures at coal-fired power plants are 

important for maintaining the PM10 NAAQS in the areas adjacent to 

the power plant properties, EPA finds that it is necessary or 

appropriate to impose measures to limit the amount of PM 

emissions from these material handling and storage emission 

sources. EPA recently imposed similar dust control requirements 

at the Navajo Generating Station, which is also on the Navajo 

Nation. 75 FR 10174.

Comment: One environmental advocacy group stated that the 

EPA must consult in accordance with sections 7(a)(1) and 7(a)(2) 

of the Endangered Species Act (ESA) with regards to the proposed 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 128 of 153

FIP because of the impacts of FCPP on threatened and endangered 

fish, wildlife, and plants and their designated critical 

habitats, which the commenter discussed at some length. The 

commenter added that EPA has discretion under the TAR to limit 

emissions of mercury, selenium, and other pollutants that may 

adversely affect the razorback sucker and Colorado pikeminnow, 

and these species’ critical habitats. According to the 

commenter, this discretion is part of what triggers the Agency’s 

obligation to consult pursuant to sections 7(a)(1) and 7(a)(2) 

of the ESA. 

Response: EPA disagrees with the commenter that 

determining BART and promulgating this FIP for FCPP necessitates 

ESA Section 7 consultation. EPA understands that the U.S. Fish 

and Wildlife Service (FWS) is primarily concerned about the 

effects of mercury and selenium on endangered fish species in 

the San Juan River. EPA notes that under the BART Alternative, 

mercury and selenium emissions will be reduced from FCPP due to 

the closure of Units 1 – 3. Additionally, EPA’s national MATS 

rule set new emission limits for mercury that would apply to 

Units 1 – 3 at FCPP if those units continue operation. EPA 

further notes that the goal of the Regional Haze Rule is to 

reduce emissions of visibility-impairing pollutants in order to 

restore visibility to natural conditions at the mandatory 

Federal Class I areas, and mercury and selenium do not affect 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 129 of 153

visibility. Therefore, EPA does not have authority to regulate 

emissions of mercury or selenium under BART. 

Comment: The coal supplier for FCCP questioned the 

legality of EPA’s approach to the Regional Haze program at FCPP. 

According to the commenter, EPA’s BART and better-than-BART 

proposals are not authorized because BART is not “reasonably 

separable” from the remainder of a regional haze implementation 

plan for the Navajo Nation under the TAR. The commenter 

concluded that the minimum amount of reasonable progress that 

BART needs to achieve in a given Class I area cannot be 

determined until the amount of reasonable progress achieved by 

other CAA and state programs is subtracted from that area’s 

reasonable progress goal. The commenter asserted that the NOx

emission reductions that would be achieved under the 

supplemental proposal are in excess of the amount required to 

achieve the reasonable progress goals in the area.

The commenter added that EPA must consider the reasonable 

progress already achieved by past FCPP emission reductions. The 

commenter concluded that any necessary reasonable progress 

remaining to be achieved by NOx BART at FCPP cannot be determined 

until the reasonable progress achieved by prior emissions 

reductions at FCPP is considered.

The commenter stated that EPA’s BART determination did not 

properly weigh the statutory factors. Specifically, the 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 130 of 153

commenter indicated that individual Class I area visibility 

improvements from SCR have not been compared with respect to the 

statutory factors to visibility improvements from LNB, and the 

actual amounts of those improvements have not been measured 

against the amounts of improvements needed to meet reasonable 

progress goals.

Response: EPA disagrees with the commenter who questioned 

the legality of our approach and that stated that EPA’s BART and 

“better-than-BART” proposals are not authorized because BART is 

not “reasonably separable” from the remainder of a regional haze 

implementation plan for the Navajo Nation under the TAR. We also 

disagree that our approach to the Regional Haze program 

impermissibly isolates BART from the context of the overall 

reasonable progress goal in violation of the CAA, and that our 

proposed BART for FCPP should be withdrawn.

EPA’s authority to promulgate a source-specific FIP in 

Indian County is based on CAA sections 301(a) and (d)(4) and 

section 49.11 of the TAR provides EPA with broad discretion to 

promulgate regulations directly for sources located in Indian

country, including on Indian reservations if we determine such 

Federal regulations are “necessary or appropriate” and the Tribe 

has not promulgated a TIP. Specifically, in 40 CFR 49.11, EPA 

interpreted CAA section 301(d)(4) to authorize EPA to promulgate 

“such Federal implementation plan provisions as are necessary or 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 131 of 153

appropriate to protect air quality”. As such, because the Navajo 

Nation has not adopted a TIP for Regional Haze, the TAR provides

discretion to EPA to determine which requirements of the 

Regional Haze Rule are necessary or appropriate to protect air 

quality, and to promulgate just those implementation plan 

provisions accordingly. Because two stationary sources on the 

Navajo Nation meet the BART eligibility criteria, EPA has 

determined that it is necessary or appropriate at this time to 

evaluate source-specific FIPs to implement the BART requirement 

of the RHR for each BART-eligible facility located on the Navajo 

Nation. The basis for our determination is discussed in several 

prior responses (See, e.g., Sections 2.1, 4.1.2, and 8.1). The 

Courts have agreed with EPA that it may implement requirements 

that are necessary or appropriate without providing for all 

aspects of the CAA programs at a single time. See Arizona Public 

Service v. EPA, 562 F.3d 1116 (10th Cir. 2009).

EPA disagrees with the comment that BART must be 

established in relation to reasonable progress goals. State or 

Tribal Implementation Plans for Regional Haze must establish 

goals that provide for reasonable progress towards achieving 

natural visibility conditions for each mandatory Class I Federal 

area located within its borders (40 CFR 51.308 (d)(1). FCPP and 

NGS are both located within the Navajo Nation Indian 

Reservation, and for the reasons outlined above, EPA is 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 132 of 153

conducting BART determinations for each facility. There are no 

mandatory Class I Federal areas as designated by Congress 

located within the Navajo Nation.48 EPA further notes that the 

five-factor analysis outlined in the BART Guidelines, which were 

promulgated as a notice and comment rulemaking, does not require 

consideration of reasonable progress goals in determining BART 

for a given facility. 

EPA also disagrees that the minimum amount of reasonable 

progress that BART needs to achieve in a given Class I area 

cannot be determined until the amount of reasonable progress 

achieved by other CAA and state programs is subtracted from that 

area’s reasonable progress goal. Neither the CAA nor Regional 

Haze regulations set any quantitative presumptive targets for 

the amount of reasonable progress that must be achieved. Rather, 

the regulations allow for flexibility in determining the amount 

of reasonable progress towards the ultimate goal of returning to 

natural background conditions.

EPA disagrees with the commenter that EPA must consider the 

reasonable progress already achieved by past FCPP emission 

reductions and that previously uncontrolled SO2, NOx, and PM 

emission rates prior to previous FIPs for FCPP should serve as 

 

48 EPA notes that Navajo Nation has established its own parks and 

monuments, including Monument Valley, Canyon de Chelly, and the Four Corners 

Monument, however, these parks are not mandatory Class I Federal Areas as set 

by Congress.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 133 of 153

the baseline for measuring visibility improvements. In its own

five-factor BART analysis, APS used actual NOx emissions from 

2001 – 2003 as baseline emissions for determining visibility 

improvement from NOx controls. NOx emissions from 2001 – 2003 

were generally consistent with and representative of NOx

emissions over the past ten years. EPA agrees with APS in its 

use of actual emissions over a recent time frame, rather than 

attempting to rely on previously uncontrolled emissions emission 

rates from FCPP as a baseline. 

Additionally, nothing in the BART regulations or guidance 

requires that EPA consider past emission reductions in 

determining BART under the RHR. However, as part of the required 

five-factor analysis for BART EPA did evaluate and consider the 

current pollution control equipment in use at FCPP. 

EPA disagrees with the comment that EPA’s BART 

determination did not properly weigh the statutory factors. As 

discussed elsewhere in this document, the BART Guidelines allow 

the reviewing authority (State, Tribe, or EPA) the discretion to 

determine how to weigh and in what order to evaluate the 

statutory factors (cost of compliance, the energy and non air 

quality environmental impacts of compliance, any existing 

pollution control technology in use at the source, the remaining 

useful life of the source, and the degree of improvement in 

visibility which may reasonably be anticipated to result from 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 134 of 153

the use of such technology), as long as the reviewing authority 

justifies its selection of the “best” level of control and 

explains the CAA factors that led the reviewing authority to 

choose that option over other control levels (see 70 FR 39170, 

July 6, 2005). EPA provided a detailed justification for our 

BART evaluation process and five-factor analysis in the TSD for 

our proposed BART determination. 

EPA also disagrees with the comment that individual Class I 

area visibility improvements from SCR have not been compared 

with respect to the statutory factors to visibility improvements 

from LNB. In the preamble to our October 19, 2010, proposed BART 

determination and in the accompanying TSD, EPA compared the 

anticipated visibility improvement from SCR with the anticipated 

improvement from combustion controls (LNB or LNB+OFA) (See 75 FR 

64230, Table 3, and TSD Tables 36 – 39), and noted that EPA 

modeled the visibility improvement from SCR to far exceed the 

modeled improvement from combustion controls. 

IV: Administrative Requirements

A. Executive Order 12866: Regulatory Planning and Review and 

Executive Order 13563: Improving Regulation and Regulatory 

Review

This action will finalize a source-specific FIP for a 

single generating source. This type of action is exempt from 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 135 of 153

review under Executive Orders 12866 (58 FR 51735, October 4, 

1993) and 13563 (76 FR 3821, January 21, 2011).

B. Paperwork Reduction Act

This action does not impose an information collection 

burden under the provisions of the Paperwork Reduction Act, 44 

U.S.C. 3501 et seq. Under the Paperwork Reduction Act, a 

“collection of information” is defined as a requirement for 

“answers to . . . identical reporting or recordkeeping 

requirements imposed on ten or more persons . . . .” 44 U.S.C. 

3502(3)(A). Because the final FIP applies to a single facility, 

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. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 136 of 153

An agency may not conduct or sponsor, and a person is not 

required to respond to a collection of information unless it 

displays a currently valid OMB control number. The OMB control 

numbers for EPA's regulations in 40 CFR are listed in 40 CFR 

Part 9.

C. Regulatory Flexibility Act

The Regulatory Flexibility Act (RFA) generally requires an 

agency to prepare a regulatory flexibility analysis of any rule 

subject to notice and comment rulemaking requirements under the 

Administrative Procedure Act or any other statute unless the 

agency certifies that the rule will not have a significant 

economic impact on a substantial number of small entities. Small 

entities include small businesses, small organizations, and 

small governmental jurisdictions. 

For purposes of assessing the impacts of today's rule on 

small entities, small entity is defined as: (1) a small business

as defined by the Small Business Administration’s (SBA) 

regulations at 13 CFR 121.201; (2) a small governmental 

jurisdiction that is a government of a city, county, town, 

school district or special district with a population of less 

than 50,000; and (3) a small organization that is any not-forprofit enterprise which is independently owned and operated and 

is not dominant in its field.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 137 of 153

After considering the economic impacts of this action on 

small entities, I certify that this final action will not have a 

significant economic impact on a substantial number of small 

entities. The Four Corners Power Plant is not a small entity and 

the FIP for Four Corners Power Plant being finalized today does 

not impose any compliance requirements on small entities. See 

Mid-Tex Electric Cooperative, Inc. v. FERC, 773 F.2d 327 (D.C. 

Cir. 1985).

D. Unfunded Mandates Reform Act (UMRA)

This rule will impose an enforceable duty on the private 

sector owners of FCPP. However, this rule does not contain a 

Federal mandate that may result in expenditures of $100 million

(in 1996 dollars) or more for State, local, and tribal 

governments, in the aggregate, or the private sector in any one 

year. EPA’s estimate for the total annual cost to install and 

operate SCR on all five units at FCPP does not exceed $100 

million (in 1996 dollars) in any one year. Thus, this rule is 

not subject to the requirements of sections 202 or 205 of UMRA.

This action is also not subject to the requirements of section 

203 of UMRA because it contains no regulatory requirements that 

might significantly or uniquely affect small governments. This 

rule will not impose direct compliance costs on the Navajo 

Nation, and will not preempt Navajo law. This final action will 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 138 of 153

reduce the emissions of two pollutants from a single source, the 

Four Corners Power Plant.

E. Executive Order 13132: Federalism

This action does not have federalism implications. It will 

not have substantial direct effects on the States, on the 

relationship between the national government and the States, or 

in the distribution of power and responsibilities among the 

various levels of government, as specified in Executive Order 

13132. This final action requires emission reductions of NOx at a 

specific stationary source located in Indian country. Thus, 

Executive Order 13132 does not apply to this action.

F. Executive Order 13175: Consultation and Coordination With 

Indian Tribal Governments

Subject to the Executive Order 13175 (65 FR 67249, November 

9, 2000) EPA may not issue a regulation that has tribal 

implications, that imposes substantial direct compliance costs, 

and that is not required by statute, unless the Federal 

government provides the funds necessary to pay the direct 

compliance costs incurred by tribal governments, or EPA consults 

with tribal officials early in the process of developing the 

proposed regulation and develops a tribal summary impact 

statement. 

EPA has concluded that this action will have tribal 

implications. However, it will neither impose substantial direct 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 139 of 153

compliance costs on tribal governments, nor preempt Tribal law. 

This final rule requires FCPP, a major stationary source located 

on the Navajo Nation, to reduce emissions of NOx under the BART 

requirement of the Regional Haze Rule. The owners of FCPP 

submitted a BART Alternative to EPA for consideration that would 

provide compliance flexibility to the owners and result in 

greater reasonable progress than BART toward the national 

visibility goal. This BART Alternative involves closure of Units 

1 – 3 at FCPP and installation of add-on pollution controls to 

Units 4 and 5. EPA issued a Supplemental Proposal to allow the 

owners of FCPP the option to implement BART or the BART 

Alternative. Because the BART Alternative involves the optional 

closure of Units 1 – 3 and an associated decline in the amount 

of coal mined and combusted, taxes and royalties paid to the 

Navajo Nation by the owners of FCPP and BHP Billiton, operator 

of the coal mine that supplies FCPP, are expected to decline. 

The closure of Units 1 – 3 is not expected to result in layoffs, 

but is expected to result in a reduction in workforce at the 

mine and power plant over time through attrition. 

EPA consulted with tribal officials early in the process of 

developing this regulation to permit them to have meaningful and 

timely input into its development. EPA proposed to determine 

that it was necessary or appropriate to implement the BART 

requirement of the Regional Haze Rule for the Navajo Nation to 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 140 of 153

protect air quality and improve visibility at the sixteen 

mandatory Class I Federal areas surrounding FCPP and the eleven 

Class I areas surrounding NGS. EPA first put forth an Advanced 

Notice of Proposed Rulemaking (ANPR) on August 28, 2009 to 

accept comment on preliminary information provided by FCPP and 

NGS and to begin the consultation process with affected tribes 

and the Federal Land Managers. EPA has consulted on numerous 

occasions with officials of the Navajo Nation in the process of 

developing this FIP, including meetings with the President Ben 

Shelly of the Navajo Nation and his staff on May 19, 2011, after 

the close of the public comment period for our proposed BART 

determination and Supplemental Proposal, and on June 13, 2012, 

prior to our final action. The agendas for these two 

consultation meetings are provided in the docket for this final 

rulemaking.49 A timeline of correspondence and consultation with 

tribes on both power plants is included in the docket for this 

final rulemaking. 

Several tribes, including the Navajo Nation, submitted 

comments on the ANPR, which we considered in developing our 

proposal and the accompanying Technical Support Document. The 

 

49 See document number 0222 in docket EPA-R09-OAR-2011-0683 titled “Agenda 

May 19, 2011 Meeting; Gov to Gov Consultation with Navajo Nation”, and 

document titled: “2012_0613 Consultation with Navajo Nation agenda and 

attendees.pdf” in the docket for this final rulemaking.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 141 of 153

main concern expressed by the Navajo Nation was that requiring 

the top NOx control option, selective catalytic reduction (SCR) 

as BART would cause FCPP to close. In developing our proposed 

BART determination, EPA conducted an analysis to examine whether 

requiring SCR on Units 1 – 5 at FCPP would cause electricity 

generation costs to exceed the cost to purchase power on the 

wholesale market. Based on our analysis, we determined that 

electricity generation costs resulting from installation of SCR 

would not make FCPP uneconomical compared to the wholesale power 

market; therefore, we concluded that our proposed BART 

determination was unlikely to cause FCPP to close. 

The Navajo Nation provided comments on our proposed rule 

and Supplemental Proposal, in consultation and by letter, which 

EPA considered in developing this final rule. The Navajo Nation 

also expressed concern about the potential adverse impacts of 

the BART Alternative to the Navajo Nation and requested that EPA 

conduct an analysis to estimate potential adverse impacts to the 

Navajo Nation. Pursuant to EPA’s customary practice of engaging 

in extensive and meaningful consultation with tribes and tribal 

authorities with regard to relevant Agency actions, EPA 

commissioned an analysis of the optional BART Alternative to 

estimate potential adverse impacts to the Navajo Nation if the 

owners of FCPP chose to retire Units 1 – 3. EPA communicated 

these potential impacts to the Navajo Nation in our consultation 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 142 of 153

meeting with President Shelly on June 13, 2012. The report will 

be provided to President Shelly by letter as a follow-up to our 

consultation with the Navajo Nation.

The Navajo Nation also expressed support for phasedimplementation of controls to provide compliance flexibility to 

FCPP. The final rule allows the owners of FCPP to choose between 

BART or the BART Alternative and provides timeframes for phasedimplementation of control options.

EPA summarized and responded to comments from the Navajo 

Nation and the Salt River Pima Maricopa Indian Community 

received on the ANPR in the Technical Support Document for our 

proposed rulemaking. Following our meeting with President Shelly 

on May 19, 2011, EPA sent a follow up letter summarizing and 

responding to the concerns expressed by the Navajo Nation.50 In 

coordination with this final rulemaking, EPA will also be 

sending a letter to the President Shelly that summarizes and 

responds to the comments raised in his letter to EPA dated June 

2, 2011. 

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks

 

50 See document 0231 in docket EPA-R09-OAR-2011-0683 titled “EPA response 

to Navajo Nation dated 09/06/2011”.
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 143 of 153

Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks (62 FR 19885, April 

23, 1997), applies to any rule that: (1) is determined to be 

economically significant as defined under Executive Order 12866, 

and (2) concerns an environmental health or safety risk that EPA 

has reason to believe may have a disproportionate effect on 

children. If the regulatory action meets both criteria, the 

Agency must evaluate the environmental health or safety effects 

of the planned rule on children, and explain why the planned 

regulation is preferable to other potentially effective and 

reasonably feasible alternatives considered by the Agency.

This rule is not subject to Executive Order 13045 because 

it requires emissions reductions of NOx from a single stationary 

source. Because this action only applies to a single source and 

is not a rule of general applicability, it is not economically 

significant as defined under Executive Order 12866, and does not 

have a disproportionate effect on children. However, to the 

extent that the rule will reduce emissions of NOx, which 

contributes to ozone formation, the rule will have a beneficial 

effect on children’s health by reducing air pollution that 

causes or exacerbates childhood asthma and other respiratory 

issues.

H. Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 144 of 153

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 

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 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 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 145 of 153

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.

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. 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 146 of 153

EPA has determined that this final rule will not have 

disproportionately high and adverse human health or 

environmental effects on minority or low-income populations 

because it increases the level of environmental protection for 

all affected populations without having any disproportionately 

high and adverse human health or environmental effects on any 

population, including any minority or low-income population. 

This rule requires emissions reductions of two pollutants from a 

single stationary source, Four Corners Power Plant.

K. Congressional Review Act

The Congressional Review Act, 5 U.S.C 801 et seq., as added 

by the Small Business Regulatory Enforcement Fairness Act of 

1996, generally provides that before a rule may take effect, the 

agency promulgating the rule must submit a rule report, which 

includes a copy of the rule, to each House of the Congress and 

to the Comptroller General of the United States. Section 804 

exempts from section 801 the following types of rules (1) rules 

of particular applicability; (2) rules relating to agency 

management or personnel; and (3) rules of agency organization, 

procedure, or practice that do not substantially affect the 

rights or obligations of non-agency parties. 5 U.S.C 804(3). EPA 

is not required to submit a rule report regarding today’s action 

under section 801 because this action is a rule of particular 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 147 of 153

applicability. This rule finalizes a source-specific FIP for a 

single generating source. 

L. Petitions for Judicial Review

Under section 307(b)(1) of the Clean Air Act, petitions for 

judicial review of this action must be filed in the United 

States Court of Appeals for the appropriate circuit by [insert 

date 60 days from publication in Federal Register]. Filing a 

petition for reconsideration by the Administrator of this final 

rule does not affect the finality of this rule for the purposes 

of judicial review nor does it extend the time within which a 

petition for judicial review may be filed, and shall not 

postpone the effectiveness of such rule or action. This action 

may not be challenged later in proceedings to enforce its 

requirements. (See CAA section 307(b)(2).)

List of Subjects in 40 CFR Part 49

Environmental protection, Administrative practice and 

procedure, Air pollution control, Indians, Intergovernmental 

relations, Reporting and recordkeeping requirements.

August 6, 2012 ______/s/______

Dated: Lisa P. Jackson,

Administrator
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 148 of 153

Title 40, chapter I of the Code of Federal Regulations is 

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 49.5512 is amended by adding paragraphs (i) and 

(j) to read as follows:

§ 49.5512 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

limit in paragraph (i)(2)(ii) of this section 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 [insert date 60 days from 

date of publication in the Federal Register]. The owner or

operator may elect to meet the plant-wide limit early to remove 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 149 of 153

the individual unit limits. Particulate limits for Units 4 and 5 

shall be effective 60 days after restart following the scheduled 

major outage for Units 4 and 5 in 2013 and 2014.

(1) 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 exceedance shall be based on a 6-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) 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 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 150 of 153

day the rolling 30-calendar day 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

rolling 30-calendar day-average pound per million Btu emissions 

of NOx.

(ii) The interim NOx limit for the first 750 MW boiler 

retrofitted with add-on post-combustion NOx control shall be as

follows:

(A) Unit 4 or 5 shall meet, based on a rolling average of

30 successive boiler operating days, a limit of 0.11 lb/MMBtu.

(iii) Schedule for add-on post-combustion NOx controls

installation

(A) Within 4 years of the effective date of this rule, FCPP 

shall have installed add-on post-combustion NOx controls on at 

least 750 MW (net) of generation to meet the interim emission 

limit in paragraph (i)(2)(ii)(A).

(B) Within 5 years of the effective date of this rule, FCPP 

shall have installed add-on post-combustion NOx controls on all

2060 MW (net) of generation to meet the plant-wide emission 

limit for NOx in paragraph (i)(2)(i).

(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, 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 151 of 153

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 percent. 

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.

(3) In lieu of meeting the NOx requirements of paragraph 

(i)(2) 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 based on a rolling average of 30 successive 

boiler operating days. A “boiler operating day” is defined as 

any 24-hour period between 12:00 midnight and the following 

midnight during which any fuel is combusted at any time at the 

steam generating unit. Emissions from each unit shall be 
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 152 of 153

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 boiler operating 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 boiler operating day rolling 

average. The NOx monitoring system shall meet the data 

requirements of 40 CFR 60.49Da(e)(2) (at least 90 percent 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.

(4) By January 1, 2013, 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)(3) of this section. By July 1, 

2013, the owner or operator shall notify the Regional 

Administrator by letter whether it will comply with paragraph 

(i)(2) of this section or whether it will comply with paragraph

(i)(3) of this section and shall submit a plan and time table 

for compliance with either paragraph (i)(2) or (i)(3) of this
This document is a prepublication version, signed by the EPA Administrator, Lisa P. Jackson, on 08/06/2012. We 

have taken steps to ensure the accuracy of this version, but it is not the official version.

Page 153 of 153

section. The owner or operator shall amend and submit this 

amended plan to the Regional Administrator as changes occur.

(5) 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)(2) or (i)(3) 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.