Technical Support Document 

for the 

PNM BART Revision to the New Mexico Regional Haze State 

Implementation Plan and Federal Implementation Plan 

Prepared and Reviewed by: 

Michael Feldman 

Brian Tomasovic 

April 2014 
2 

TABLE OF CONTENTS

I. Relationship of this TSD to our Proposal .................................................................................... 5

II. Background to Regional Haze and Requirements for Best Available Retrofit Technology ...... 5

III. Evaluation of State Submittal ................................................................................................. 11

A. Provisions for stationary source emissions of NOx and PM: 40 CFR 51.309(d)(4)(vii) ..... 12

A.1. BART Five Factor Determination: 40 CFR 51.308(e)(1)(ii)(A)-(B) ........................... 12

A.1.a New Mexico’s NOx BART Analysis for the SJGS ................................................ 15

A.1.b. NMED’s NOx BART Determination: .................................................................... 26

A.1.c EPA’s Evaluation Regarding NOx BART Determination for SJGS ....................... 29

A.2. Installation of BART: 40 CFR 51.308(e)(1)(iv) – (v) ................................................... 38
3 

TABLES

Table 1. SJGS Operational Characteristics .................................................................................. 13

Table 2. New Mexico’s determination of NOx Control Effectiveness ......................................... 17

Table 3. NOx Control Effectiveness for Additional Control Technology Alternatives ............... 17

Table 4. New Mexico’s Analysis of the Impacts and Cost Effectiveness of NOx Control 

Technologies ................................................................................................................................. 18

Table 5. New Mexico’s Analysis of Impacts and Cost Effectiveness of the Three NOx Control 

Scenarios ....................................................................................................................................... 20

Table 6. Updated Visibility Modeling Scenarios ........................................................................ 22

Table 7. Key CALPUFF modeling options and inputs ................................................................. 23

Table 8. Modeled Emission Rates (lb/hr) ..................................................................................... 24

Table 9. Modeled Stack Parameters .............................................................................................. 25

Table 10. Modeled Average Visibility Improvement of the 98th Percentile Delta-dv Impacts from 

2001-2003 ..................................................................................................................................... 25

Table 11. Baseline Visibility Results, 98th percentile (dv) ........................................................... 31

Table 12. 4 SCR Visibility Results, 98th percentile (dv) .............................................................. 32

Table 13. 4 SNCR Visibility Results, 98th percentile (dv) ............................................................ 33

Table 14. State Alternative 2 SNCR/2 Shutdown Visibility Results, 98th percentile (dv) ........... 33

Table 15. 2001-2003 average percent reduction in visibility impairment (98th percentile) from 

the baseline to the 3 evaluated control scenarios. ......................................................................... 34

Table 16. Average number of days impacted over 0.5 and 1.0 dv ............................................... 35

Table 17. Incremental Cost-Effectiveness ................................................................................... 37

Table 1. SJGS Operational Characteristics .................................................................................. 13

Table 2. New Mexico’s determination of NOx Control Effectiveness ......................................... 17

Table 3. NOx Control Effectiveness for Additional Control Technology Alternatives ............... 17

Table 4. New Mexico’s Analysis of the Impacts and Cost Effectiveness of NOx Control 

Technologies ................................................................................................................................. 18

Table 5. New Mexico’s Analysis of Impacts and Cost Effectiveness of the Three NOx Control 

Scenarios ....................................................................................................................................... 20

Table 6. Updated Visibility Modeling Scenarios ........................................................................ 22

Table 7. Key CALPUFF modeling options and inputs ................................................................. 23

Table 8. Modeled Emission Rates (lb/hr) ..................................................................................... 24

Table 9. Modeled Stack Parameters .............................................................................................. 25
4 

Table 10. Modeled Average Visibility Improvement of the 98th Percentile Delta-dv Impacts from 

2001-2003 ..................................................................................................................................... 25

Table 11. Baseline Visibility Results, 98th percentile (dv) ........................................................... 31

Table 12. 4 SCR Visibility Results, 98th percentile (dv) .............................................................. 32

Table 13. 4 SNCR Visibility Results, 98th percentile (dv) ............................................................ 33

Table 14. State Alternative 2 SNCR/2 Shutdown Visibility Results, 98th percentile (dv) ........... 33

Table 15. 2001-2003 average percent reduction in visibility impairment (98th percentile) from 

the baseline to the 3 evaluated control scenarios. ......................................................................... 34

Table 16. Average number of days impacted over 0.5 and 1.0 dv ............................................... 35

Table 17. Incremental Cost-Effectiveness ................................................................................... 37

FIGURES

Figure 1 - Map of Class I Areas ...................................................................................................... 6

Figure 2 - Location of the Class I Areas in New Mexico ............................................................... 7

Figure 3 - Map of Regional Planning Organization Boundaries .................................................... 8

Figure 4. Class I areas within 300km of the San Juan Generating Station ................................... 22

Figure 5. Comparison of Visibility Improvement of Alternatives at San Juan Generating Station

....................................................................................................................................................... 26

Figure 6. Visibility Impact Results (Figure 7-2 of 2013 PNM Report) ........................................ 34
5 

New Mexico Regional Haze Technical Support Document (TSD) 

I. Relationship of this TSD to our Proposal 

 The Environmental Protection Agency (EPA) is proposing to approve revisions to the 

New Mexico Regional Haze State Implementation Plan that address the Best Available Retrofit 

Technology (BART) requirement for oxides of nitrogen (NOx) for the Public Service of New 

Mexico (PNM) San Juan Generating Station (SJGS) in San Juan County, New Mexico and the 

New Mexico Visibility Transport SIP that address impacts of emissions from SJGS, as required 

by the Federal Clean Air Act (CAA) mandate to ensure that emissions from sources in New 

Mexico do not interfere with programs in other states to protect visibility. In conjunction with 

these proposed approvals, we propose to withdraw the federal implementation plan (FIP) that 

addresses the NOx BART and visibility transport requirements for the SJGS. 

 

Pursuant to 40 CFR 51.309(d)(4)(vii), a regional haze SIP submitted under the 309 

program to address SO2 emissions must contain any necessary long-term strategies and BART 

requirements for PM and NOx. These BART determinations must be submitted pursuant to 40 

CFR 51.308(e). 

This TSD is not meant to be a complete rationale for the proposal. It merely provides 

additional information for some of the technical aspects of the basis for this proposal when 

needed. In some of the non-technical areas, the Federal Register notice provides more detail than 

does this TSD. Also, this TSD evaluates the requirements of section 51.308(e) in the order in 

which they appear in that regulation, whereas our Federal Register notice groups the 

requirements into related areas so the concepts can be understood more easily. In this regard, the 

TSD can serve as a checklist of whether the requirements have been addressed. Lastly, the TSD 

attempts to refer the reader to the specific portions of the 2013 New Mexico RH SIP submittal 

that we relied upon for our analysis of particular portions of section 51.309(d)(4)(vii). 

 This document often uses language such as, "we find” or other similar phrases that on the 

surface would suggest a final determination has been made. However, all aspects of the TSD 

should be considered to be part of our proposal and are subject to change based on comments 

and other information received during the public comment period. 

II. Background to Regional Haze and Requirements for Best Available Retrofit Technology 

 In Section 169A of the 1977 Amendments to the Clean Air Act (CAA), Congress set 

forth a program for protecting visibility in Federal Class I areas which calls for the “prevention 
6 

of any future, and the remedying of any existing, impairment of visibility in mandatory Federal 

Class I areas which impairment results from manmade air pollution.” Congress adopted the 

visibility provisions to protect visibility in 156 Federal Class I areas, which include certain 

national parks, memorial parks, and wilderness areas over a certain size, and all international 

parks. These areas are defined at 40 CFR 81.400, are listed by State at 40 CFR 81.401-81.437, 

and are depicted in Figure 1, with the Class I areas in New Mexico depicted in Figure 2. 

Figure 4, later in this TSD, shows the Class I areas within 300 km of PNM’s San Juan 

Generating Station. 

. 

Figure 1 - Map of Class I Areas 
7 

Figure 2 - Location of the Class I Areas in New Mexico 

 On December 2, 1980, we promulgated regulations to address visibility impairment that 

is “reasonably attributable” to a single source or small group of sources. (45 FR 80084) These 

regulations represented the first phase in addressing visibility impairment and deferred action on 

regional haze that emanates from a variety of sources until monitoring, modeling and scientific 

knowledge about the relationships between pollutants and visibility impairment improved. 

In the 1990 Amendments to the CAA, Congress added Section 169B and called on us to 

issue Regional Haze rules. The RH rule that we promulgated on July 1, 1999 (64 FR 35713) 

revised the existing visibility regulations to integrate provisions addressing regional haze 

visibility impairment and establish a comprehensive visibility protection program for Federal 

Class I areas. These regulations represented the second phase in addressing visibility impairment. 

States were required to submit state implementation plans (SIPs) to us that set out each state’s 

plan for complying with the RH Rule, including consultation and coordination with other states 

and with Federal Land Managers (FLMs). States were required to submit a Regional Haze SIP to 

us within three years after the date of designation of areas under the National Ambient Air 

Quality Standard (NAAQS) for fine particulate matter (PM2.5). We promulgated PM2.5
8 

designations on December 17, 2004, and thus, regional haze SIPs were to be submitted to us by 

December 17, 2007, which is also specified at 40 CFR 51.308(b). 

 The RH rule addressed the combined visibility effects of various pollution sources over a 

wide geographic region. Consequently, all 50 states, including those without Class I areas, 

Washington, D.C., and the Virgin Islands, were required to submit Regional Haze SIPs (40 CFR 

51.300(b)(3)). We designated five Regional Planning Organizations (RPOs) to assist with the 

coordination and cooperation needed to address the visibility issue, as shown by Figure 3. 

Figure 3 - Map of Regional Planning Organization Boundaries 

 New Mexico, through the NMED joined state air agencies from Alaska, Arizona, 

California, Colorado, Hawaii, Idaho, Montana, New Mexico, North Dakota, Oregon, South 

Dakota, Utah, Washington, and Wyoming in forming the WRAP, in 1997 to implement the 

Grand Canyon Visibility Transport Commission’s recommendations to EPA 1

. WRAP also 

includes federally recognized Indian tribes located within the geographic boundaries of its 

                                                            

1

 Recommendations for Improving Western Vistas, Report of the Grand Canyon Visibility Transport Commission to 

the EPA, June 1996. Available at: http://www.wrapair.org/WRAP/reports/GCVTCFinal.PDF 
9 

member states. The State of New Mexico and its agency, the NMED, chose to participate in the 

WRAP to develop the technical analyses needed to fulfill the requirements of the RH Rule. 

Regional haze SIPs must assure reasonable progress towards the national goal of 

achieving natural visibility conditions in Class I areas. Section 169A of the CAA and our 

implementing regulations require states to establish long-term strategies for making reasonable 

progress toward meeting this goal. SIPs must also give specific attention to certain stationary 

sources that were in existence on August 7, 1977, but were not in operation before August 7, 

1962, and require these sources, where appropriate, to install BART controls for the purpose of 

eliminating or reducing visibility impairment. 

Pursuant to 40 CFR 51.309(d)(4)(vii), a regional haze SIP submitted under the 309 

program must contain any necessary long term strategies and BART requirements for PM and 

NOx These BART provisions must be submitted pursuant to 40 CFR 51.308(e). We promulgated 

regulations addressing RH in 1999, 64 FR 35714 (July 1, 1999), codified at 40 CFR part 51, 

subpart P.2 These regulations require all states to submit implementation plans that, among other 

measures, contain either emission limits representing BART for certain sources constructed 

between 1962 and 1977, or alternative measures that provide for greater reasonable progress than 

BART. 40 CFR 51.308(e). States are directed to conduct BART determinations for such sources 

that may be anticipated to cause or contribute to any visibility impairment in a Class I area. 

Rather than requiring source-specific BART controls, states also have the flexibility under 40 

CFR 51.308(e)(2) to adopt an emissions trading program or other alternative program as long as 

the alternative program provides greater reasonable progress towards improving visibility than 

BART. The discussion below specifically applies to regional haze SIPs that opt to require BART 

on sources subject to the BART requirements, rather than satisfying the requirements for 

alternative measures that would be evaluated under 40 CFR 51.308(e)(2). 

On July 6, 2005, the EPA published the Guidelines for BART Determinations Under the 

Regional Haze Rule at Appendix Y to 40 CFR Part 51 (hereinafter referred to as the “BART 

Guidelines”) to assist states in determining which of their sources should be subject to the BART 

requirements and the appropriate emission limits for each applicable source. The BART 

Guidelines are not mandatory for all sources. However, in making a BART determination for a 

fossil fuel-fired electric generating plant (EGU) with a total generating capacity in excess of 750 

megawatts, a state must use the approach set forth in the BART Guidelines. See CAA section 

169A(b)(2) A state is encouraged, but not required, to follow the BART Guidelines in making 

BART determinations for other types of sources. 

                                                            

2

 In American Corn Growers Ass’n v. EPA, 291 F.3d 1 (D.C. Cir. 2002), the U.S Court of Appeals for the District 

of Columbia Circuit issued a ruling vacating and remanding the BART provisions of the regional haze rule. In 2005, 

we issued BART guidelines to address the court’s ruling in that case. See 70 FR 39104 (July 6, 2005). 
10 

The process of establishing BART emission limitations can be logically broken down 

into three steps: first, states identify those sources which meet the definition of ‘‘BART-eligible 

source’’ set forth in 40 CFR 51.3013

; second, states determine whether such sources ‘‘emit[] any 

air pollutant which may reasonably be anticipated to cause or contribute to any impairment of 

visibility in any such area’’ (a source that fits this description is “subject to BART,”) and; third, 

for each source subject to BART, states identify the appropriate type and the level of control for 

reducing emissions. 

Under the BART Guidelines, states may select a visibility impact threshold, measured in 

deciviews (dv), below which a BART-eligible source would not be expected to cause or 

contribute to visibility impairment in any Class I area. The state must document this threshold in 

the SIP and state the basis for its selection of that value. Any source with visibility impacts that 

model above the threshold value would be subject to a BART determination review. The BART 

Guidelines acknowledge varying circumstances affecting different Class I areas. States should 

consider the number of emission sources affecting the Class I areas at issue and the magnitude of 

the individual sources’ impacts. Any visibility impact threshold set by the state should not be 

higher than 0.5 dv. See 40 CFR pt. 51, app. Y, section III.A.1. 

The BART Guidelines establish the dv as the principal metric for measuring visibility. Id. 

This visibility metric expresses uniform changes in visibility impairment in terms of common 

increments across the entire range of visibility conditions, from pristine to extremely hazy 

conditions. Visibility is sometimes expressed in terms of the visual range which is the greatest 

distance, in kilometers or miles, at which a dark object can just be distinguished against the sky. 

The dv is a more useful measure for tracking progress in improving visibility because each dv 

change is an equal incremental change in visibility perceived by the human eye. 

In their SIPs, states must identify subject-to-BART sources and document their BART 

control determination analyses In making BART determinations, section 169A(g)(2) of the CAA 

requires that states consider the following factors: (1) the costs of compliance; (2) the energy and 

non-air quality environmental impacts of compliance; (3) any existing pollution control 

technology in use 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. States are free to determine the weight and significance to be assigned to each factor. 

                                                            

3

 BART-eligible sources are those sources that have the potential to emit 250 tons or more of a visibility-impairing 

air pollutant, were put in place between August 7, 1962 and August 7, 1977, and whose operations fall within one or 

more of 26 specifically listed source categories. 
11 

A regional haze SIP must include source-specific BART emission limits and compliance 

schedules for each source subject to BART. Once a state has made its BART determination, the 

BART controls must be installed and operated as expeditiously as practicable, but no later than 

five years after the date of the EPA approval of the regional haze SIP. CAA section 169(g)(4); 40 

CFR 51.308(e)(1)(iv). In addition to what is required by the RHR, general SIP requirements 

mandate that the SIP must also include all regulatory requirements related to monitoring, 

recordkeeping, and reporting for the BART controls on the source. See CAA section 110(a). 

III. Evaluation of State Submittal 

 In our past evaluations of New Mexico RH SIP submittals, as well as the RH SIP revision 

under review in the proposal associated with this TSD, we reviewed all the parts of the 

document, including the body of the SIP revision itself, and the submitted appendix D, and all 

other submitted documents. In addition, our evaluation drawsupon the following documents that 

may not otherwise be specifically discussed in our TSD and/or the Federal Register 

publication(s) of our proposal: 

1. 40 CFR Part 51. 

2. Appendix V to 40 CFR Part 51. 

3. The “BART Guidelines” in Appendix Y to Part 51—Guidelines for BART Determinations 

 Under the Regional Haze Rule, 70 FR 39104, July 6, 2005. 

4. Guidance for Tracking Progress Under the Regional Haze Rule, EPA-454/B-03-004, 

 September, 2003. 

5. Guidance for Demonstrating Attainment of Air Quality Goals for PM2.5 and Regional Haze, 

 January 2, 2001. 

6. Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule, EPA- 

 454/B-03-005, September 2003. 

7. The “Baseline Memo,” which is entitled, “2002 Base Year Emission Inventory SIP 

 Planning: 8-Hour Ozone, PM2.5 and Regional Haze Programs, dated 11/18/2002, from Lydia 

 Wegman to the Regional Air Directors.” 

8. Guidance for Setting Reasonable Progress Goals Under the Regional Haze Program, dated 

 June 1, 2007. 

9. Visibility Monitoring Guidance, EPA-454/R-99-003, June 1999. 

10. Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National 

 Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations, EPA-454/R-05- 

 001, dated August, 2005. 

11. Interim Air Quality Policy on Wildland and Prescribed Fires, April 23, 1998. 
12 

A. Provisions for stationary source emissions of NOx and PM: 40 CFR 51.309(d)(4)(vii) 

Pursuant to 40 CFR 51.309(d)(4)(vii), a regional haze SIP submitted under the 309 SIP 

program must contain any necessary long term strategies and BART requirements for PM and 

NOx. These BART provisions must be submitted pursuant to 40 CFR 51.308(e).New Mexico 

must submit a SIP containing emission limitations representing Best Available Retrofit 

Technology (BART) and schedules for compliance with BART for each BART eligible source 

that may reasonably be anticipated to cause or contribute to any impairment of visibility in any 

mandatory Class I Federal area, unless it demonstrates that an emissions trading program or 

other alternative will achieve greater reasonable progress toward natural visibility conditions. 

Section 40 CFR 51.308(e)(2) – (3) concerning the use of a trading program or other 

alternative to BART to satisfy the requirements of BART for PM and NOx are not applicable to 

the NM RH SIP revision evaluated here. Section 309 provides an alternative method of 

satisfying the Section 308 SO2 BART requirements with emission milestones and a backstop 

trading program (40 CFR 51.309(d)(4)). The milestones must be shown to provide for greater 

reasonable progress than would be achieved by application of BART pursuant to 40 CFR 

51.308(e)(2). 

In our prior review and action on the New Mexico 2011 RH SIP revision, we agreed with 

New Mexico’s identification of sources that are BART-eligible and subject to BART, including 

Units 1,2,3 and 4 of the SJGS. 77 FR 70693 (November 27, 2012). We approved the State’s PM 

BART determinations and emission limits for these units, as well as the State’s participation in 

the SO2 emission reduction milestones and backstop trading program, while taking no action on 

the State’s NOx BART determinations and emission limits for these units. The State’s 

conclusions were also consistent with the determinations that the EPA made in the course of 

promulgating its FIP for the SJGS. In that final action we found that units 1, 2, 3, and 4 of the 

SJGS comprise the only New Mexico source subject to BART. 77 FR 70693 (November 27, 

2012).The focus of our current review is on the third component—the determination of NOx 

BART controls for these units. Specifically, this proposal addresses New Mexico’s duty to 

address the following sections of the RH rule: 

• 51.308(e)(1)(ii)(A) - BART five factor determination 

• 51.308(e)(1)(ii)(B) - BART for larger fossil fuel power plants 

• 51.308(e)(1)(iv)-(v) – installation of BART 

A.1. BART Five Factor Determination: 40 CFR 51.308(e)(1)(ii)(A)-(B) 
13 

 NMED must make a determination of BART for each BART-eligible source in New 

Mexico that emits any air pollutant which may reasonably be anticipated to cause or contribute 

to any impairment of visibility in any mandatory Class I Federal area. All such sources are 

subject to BART. 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 within the State. In this analysis, New 

Mexico must take into consideration 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 

improvement in visibility which may reasonably be anticipated to result from the use of such 

technology. 

The third step of a BART evaluation is to perform the BART analysis. The BART Guidelines4 

describe the BART analysis as consisting of the following five basic steps: 

• Step 1: Identify All Available Retrofit Control Technologies, 

• Step 2: Eliminate Technically Infeasible Options, 

• Step 3: Evaluate Control Effectiveness of Remaining Control Technologies, 

• Step 4: Evaluate Impacts and Document the Results, and 

• Step 5: Evaluate Visibility Impacts. 

The SJGS consists of four coal-fired generating units and associated support facilities. 

Each coal-fired unit burns pulverized coal and No. 2 diesel oil (for startup) in a boiler, and 

produces high-pressure steam that powers a steam turbine coupled with an electric generator. 

Electric power produced by the units is supplied to the electric power grid for sale. Coal for the 

units is supplied by the adjacent San Juan Mine. Units 1 and 2 have a unit capacity of 350 and 

360 MW, respectively. Units 3 and 4 each have a unit capacity of 544 MW. The BART 

determination for SJGS, as a fossil-fuel fired power plant having a total generating capacity 

greater than 750 megawatts, must be made pursuant to the guidelines in appendix Y of 40 CFR 

Part 51 (Guidelines for BART Determinations under the Regional Haze Rule) 

Table 1. SJGS Operational Characteristics 

 Unit #1 Unit #2 Unit #3 Unit #4 

Unit Rating, 

MW (gross) 360 350 544 544 

+Boiler Heat 

Input, MBtu/hr 3,707 3,688 5,758 5,649 

Type of 

Boiler/Manufacturer 

Wall-fired/ Foster 

Wheeler 

Wall-fired/ Foster 

Wheeler 

Opposed Wallfired/Babcock & 

Wilcox 

Opposed Wallfired/Babcock & 

Wilcox 

                                                            

4

 70 FR 39164. 
14 

Existing emissions controls (post-consent decree): 

NOx LNB/OFA/NN for all units 

SO2 Wet FGD for all units 

PM PJFF for all units 

On March 10, 2005, PNM entered into a consent decree with the Grand Canyon Trust, 

Sierra Club, and New Mexico Environmental Department (NMED), resulting in the installation 

of low-NOx burners (LNB) with overfire air (OFA) ports and a neural network (NN) system to 

reduce NOx emissions, and a full-sized pulse jet fabric filter (PJFF) to reduce PM emissions.5

 

The wet limestone scrubber was modified to eliminate flue gas bypass, and dibasic acid (DBA) 

was added to the scrubber process to improve SO2 removal. Installation of these controls on all 

four units was completed in the spring of 2009. Prior to installation of controls to meet the 

consent decree, all SGJS units were equipped with hot-side electrostatic precipitators (ESP) for 

PM control, and wet limestone flue gas desulfurization (FGD) systems for SO2 control. SJGS 

Units1, 3, and 4 also had LNB controls for NOx prior to the installation of controls for the 

consent decree. 

In June 2007, the operator of the SJGS, Public Service Company of New Mexico (PNM) 

submitted its NOx BART evaluation to NMED. That analysis was added to and revised multiple 

times to incorporate new information or in response to comments/requests from NMED6

 for 

additional visibility modeling analyses, control technology considerations, and cost analyses.7

PNM’s April 2013 BART Analysis addendum8 (referred to hereafter as the “2013 PNM report”) 

is an addendum and update to the 2007 evaluation and subsequent revisions. This analysis adds 

to and updates the previous analyses and considers a new scenario not previously evaluated. 

 

The 2013 RH SIP revision under review in this action builds upon the 2011 RH SIP 

revision and its supporting BART analyses, and examines a new control scenario including unit 

shutdowns not previously analyzed. For purposes of reviewing the projected visibility benefits 

and cost-effectiveness, this scenario, called the State Alternative is compared to the control 

scenario in the FIP (SCR on all four units) and the State’s 2011 NOx BART determination 

(selective non-catalytic reduction (SNCR) on all four units). The State Alternative differs from 

the NOX BART emission limit of 0.05 lb/MMBtu in the FIP (which can be met by the 

installation of SCR on all four units) and the State’s earlier submitted, superseded (if the 2013 

                                                            

5

 Consent Decree in The Grand Canyon Trust and Sierra Club, Plaintiffs, The State of New Mexico, PlaintiffIntervenor, v. Public Service Company of New Mexico, Defendant, (CV 02-552 BB/ACT (ACE)), lodged in the 

United States District Court, District of New Mexico, on March 10, 2005, at 15-16. 6

 Correspondence between PNM and NMED concerning these BART analyses is contained in NMED Exhibit 6 of 

the 2011 RH SIP revision. 

7 PNM’s 2007 BART analysis and subsequent analyses are Exhibit 7a through 7t of the NMED’s 2011 RH SIP 

revision. 

8

 Public Service of New Mexico, Best Available Retrofit Technology Analysis, Addendum, April 1, 2013, submitted 

as Exhibit 6 of the 2013 RH SIP revision 
15 

RH SIP revision is fully approved) determination of 0.23 lb/MMBtu (which can be met by 

installation of SNCR on all four units). The State Alternative contains several elements, 

including among other things, the installation of SNCR on Units 1 and 4 and enforceable 

deadlines by which Units 2 and 3 will be permanently retired. The emission reductions, visibility 

improvements, and additional non-air quality environmental benefits due to the unit shutdowns 

were an important consideration in New Mexico’s selection of the State Alternative as NOx 

BART for the SJGS. More specifically, the 2013 RH SIP revision requires the following: 

 Fifteen (15) months after the EPA final approval of the 2013 RH SIP revision, but no 

earlier than January 31, 2016, PNM will complete installation of SNCR technology 

on SJGS Units 1 and 4 and meet an emission limit of 0.23 lb/MMBtu on a rolling 30-

day average basis;9 

 Retirement of the SJGS Units 2 and 3 by December 31, 2017; 

 The PNM will commence a program of testing and evaluation, after the installation of 

SNCRs, to determine if additional NOX emission reductions can be achieved. The 

Testing Program, consisting of SNCR performance testing, fuel performance testing, 

and long-term performance evaluation, must be completed no later than January 31, 

2017.10

In accordance with section 169A of the CAA, the RHR, and the BART Guidelines, New 

Mexico weighed the five statutory factors in making its NOX BART determination. New 

Mexico’s final evaluation is available in the revised Chapter 10 and Appendix D of the 2013 RH 

SIP revision. We note that the State Alternative also results in additional reductions in the 

emissions of SO2 on Units 1 and 4. These SO2 emission reductions occur separately and apart 

from the SO2 backstop trading program that the EPA has already approved as satisfying SO2

BART. These SO2 reductions will result in increased visibility improvement, and result in 

permitted emissions substantially below the level needed to prevent SO2 emissions from New 

Mexico from interfering with the visibility programs of other States, as discussed in our review 

of the State’s 2013 Visibility Transport SIP in the Federal Register notice for this action. 

A.1.a New Mexico’s NOx BART Analysis for the SJGS 

                                                            

9

 The permit conditions at A112C specify the averaging time and calculation methodology for the enforceable 

emission limit for NOX on Units 1 and 4 of 0.23 lb/MMBtu on a boiler operating day basis, averaged across the two 

units. 

10 Unless the long-term performance evaluation is delayed due to a delay in EPA approval or per the language in the 

Term Sheet at paragraph 1(d)(iv) concerning the evaluation period spanning the required number of days during 

both the summer and winter months. 
16 

In promulgating our FIP, we drew heavily upon the analyses prepared by the NMED and 

PNM that were available at the time. While we agreed with some conclusions presented in those 

analyses, we also disagreed with a number of points that are outlined in the proposed and final 

FIP Federal Register notices. 76 FR 491 (January 5, 2011) and 76 FR 52388 (August 22, 2011). 

The BART review of the State Alternative in the 2013 RH SIP revision examines a new control 

scenario, the State Alternative, and compares it to the control scenarios in the FIP and the 2011 

RH SIP revision. As explained above, the State Alternative is a new control scenario proposed 

by the PNM in coordination with the State that includes the shutdown of two units at the SJGS 

by December 31, 2017. Consequently, this control scenario is different than the control scenarios 

contemplated in the FIP and the 2011 RH SIP revision. Although the EPA’s regulations do not 

require states to consider a fuel switch or a shutdown of an existing unit as part of their BART 

analyses, a state may include such options in its analysis where a company voluntarily offers 

such measures as a strategy for reducing emissions. 

The SJGS currently has low-NOX burners (LNB) with overfire air (OFA) and a neural 

network to reduce NOX emissions and comply with a 2005 consent decree11 emission limit of 

0.30 lb NOX/MMBtu on a daily rolling 30-day average basis. NMED performed a BART five –

factor analysis for NOx. A summary of this analysis is presented below: 

State Submittal: Section 10.4, 10.5 and Appendix D 

 

Step 1- Identify All Available Retrofit Control Technologies: To address step 1 of the BART 

analysis, New Mexico identified a number of potentially available NOX control technologies, 

including SNCR, SCR, SNCR/SCR Hybrid, Natural Gas Reburn, Nalco Mobotec ROFA and 

Rotamix, NOxStar, ECOTUBE, PowerSpan ECO, Phenix Clean Combustion, and e-SCRUB. 

NOxNOx 

Step 2- Eliminate Technically Infeasible Options: NMED determined the following potentially 

available NOx control technologies are not technically feasible: Natural Gas Reburn, NOxStar, 

ECOTUBE, PowerSpan ECO, Phenix Clean Combustion, and e-SCRUB. This conclusion is 

consistent with our own analysis in development of the FIP. New Mexico concluded that SCR, 

SNCR, SNCR/SCR Hybrid, and Nalco Mobotec ROFA and Rotamix are technically feasible 

control options for the SJGS units. 

Step 3- Evaluate Control Effectiveness of Remaining Control Technologies: Table 2 shows the 

control effectiveness of each remaining control technology in New Mexico’s BART analysis, 

                                                            

11 Consent Decree in The Grand Canyon Trust and Sierra Club, Plaintiffs, The State of New Mexico, PlaintiffIntervenor, v. Public Service Company of New Mexico, Defendant, (CV 02–552BB/ACT (ACE)), lodged in the 

United States District Court, District of New Mexico, on March 10, 2005, at 15–16. 
17 

based on a baseline emission rate of 0.30 lb/MMBtu. In its 2011 RH SIP revision, New Mexico 

revised the achievable controlled emission rate of SNCR from its earlier analysis of 0.24 

lb/MMBtu to 0.23 lb/MMBtu, based on tests and an updated performance guarantee from the 

vendor.12 New Mexico previously evaluated SCR at an emission rate of 0.07 lb/MMBtu and a 

control efficiency of 77%.13 In its 2013 RH SIP revision, however, New Mexico revised its 

evaluation of SCR, concluding that at an emission rate of 0.05 lb/MMBtu and a control 

efficiency of 83% are achievable, consistent with our own evaluation in the FIP. Table 3 

summarizes the control efficiencies and emissions contemplated in the three analyzed scenarios. 

Table 2. New Mexico’s determination of NOx Control Effectiveness 

Control Technology Control Efficiency 

(%) 

Controlled Emission Rate 

(lb/MMBtu) 

ROFA 13% 0.26 

Rotamix (SNCR) 23% 0.23 

SNCR 23% 0.23 

ROFA/Rotamix 33% 0.20 

SCR/SNCR Hybrid 40% 0.18 

SCR 83% 0.05 

Table 3. NOx Control Effectiveness for Additional Control Technology Alternatives14

 Unit 1 Unit 2 Unit 3 Unit 4 

Facility15

Total 

Emissions 

Design 

Basis 

Heat 

Input 

3707 MMBtu/hr 3688 MMBtu/hr 5758 MMBtu/hr 5649 MMBtu/hr 

lb/ 

MMBtu tpy 

lb/ 

MMBtu tpy 

lb/ 

MMBtu tpy 

lb/ 

MMBtu tpy tpy 

Baseline 0.30 4410 0.30 4419 0.30 6431 0.30 6309 21000 

SCR 0.05 690 0.05 687 0.05 1072 0.05 1052 3502 

SNCR 0.23 3174 0.23 3158 0.23 4931 0.23 4837 16100 

SNCR 

with 

Retired 

Units 

0.23 3174 --- --- --- --- 0.23 4837 8011 

                                                            

12 Public Service Company of New Mexico, San Juan Generating Station, Revised SNCR Analysis, February 11, 

2011 (2011 NM RH SIP, NMED Ex. 7t) 

13 As we discuss in our FIP regarding NOx BART for the SJGS, we found that SCR is capable of achieving an 

emission limit of 0.05 lbs/MMBtu on each of the units of the SJGS, based on a 30 boiler operating day average. 76 

FR 52388. 

14 From Table 5-1 of Best Available Retrofit Technology Analysis Addendum, Public Service of New Mexico, April 

1, 2013 submitted as Exhibit 6 of the 2013 RH SIP revision. 

15 Calculated based on 85% annual unit capacity 
18 

Step 4- Evaluate Impacts and Document the Results: The BART Guidelines require that the cost 

of compliance, energy impacts, non-air quality environmental impacts, and remaining useful life 

of the facility be analyzed for each potential control technology in step 4. Table 4, which is 

found as Table 10 of the revised Appendix D of the 2013 RH SIP revision, summarizes the unit 

specific cost analysis results submitted to NMED by PNM. The control effectiveness for SCR 

and SNCR in this analysis have been updated and the costs of these two options have also been 

revised to reflect more recent cost information submitted by PNM16 to NMED for evaluation. 

The costs associated with ROFA, ROFA/Rotamix and Rotamix are based on the 2008 vendor 

quotes17 and later adjusted to 2010 dollars.18 The cost of sorbent injection is included in the cost 

analysis for SCR.19 We note that costs for the SCR and SNCR options are in 2013 dollars and 

annualized over 30 years, while all remaining control options are in 2010 dollars and annualized 

over 20 years. Because the rate of inflation between 2013 and 2010 was minimal (1.07 percent), 

the costs are comparable. 

Table 4. New Mexico’s Analysis of the Impacts and Cost Effectiveness of NOx Control 

Technologies 

Control 

Technology 

Emission 

Limit 

lb/MMBtu 

NOX

Emissions 

(tpy) 

NOX

Reduction 

(tpy) 

Total 

Capital 

Investment 

(TCI) 

(1,000$) 

Total 

Annualized 

Cost 

(TAC) 

(1,000$) 

Cost 

Effectiveness 

($/ton) 

Incremental 

Cost 

Effectiveness 

($/ton) 

Energy 

Impacts 

(1,000$) 

Non-Air 

Impacts 

(1,000$) 

Unit 1

SCR + 

sorbent 0.05 690 3,450 180,862 22,165 6,425 6,749 746 NA1

SNCR/SCR 

Hybrid 0.18 2,484 1,656 110,683 16,816 10,154 35,917 706 1,762 

ROFA/ 

Rotamix 0.20 2,760 1,380 30,790 6,902 5,001 7,982 1,413 3 

Rotamix 

(SNCR) 0.23 3,174 966 11,822 3,597 3,723 116 51 4 

SNCR 0.23 3,174 966 17,392 5,400 5,590 80 43 NA1

ROFA 0.26 3,588 552 19,256 3,549 6,429 -- 1,363 NA1

Consent 

Decree 0.30 4,140 1,254 14,580 1,422 1,134 NA NA1 NA1

                                                            

16 Best Available Retrofit Technology Analysis Addendum, Public Service of New Mexico, April 1, 2013, submitted 

as Exhibit 6 of the 2013 RH SIP revision 

17 PNM San Juan Generating Station BART Analysis of Nalco Mobotec NOx Control Technologies, August 29, 

2008. NMED Exhibit 7n of the 2011 RH SIP revision 

18 PNM San Juan Generating Station BART Analysis Update, February 11, 2011. NMED exhibit 7t of the 2011 RH 

SIP revision 

19 Table 2 was constructed by PNM to incorporate costs due to sorbent injection, as a means of SO3 control in 

conjunction with SCR. This was done by PNM in response to a request by NMED. As NMED notes in its BART 

analysis, it understands there are SCR catalysts now on the market that are capable of a much smaller SO2 to SO3

conversion. Furthermore, our analysis contained in the TSD to the FIP and the FIP indicate that anticipated SO3 

emissions to be much lower than estimated by PNM and finds that sorbent injection is not necessary. The TSD for 

our FIP, “Visibility Modeling for BART Determination: San Juan Generating Station, New Mexico,” and the 

proposed and final FIP are available in the docket to our FIP and also included in the docket for this action. 
19 

Pre-CD 0.43 5,394 NA NA NA NA NA NA NA1

Unit 2

SCR + 

sorbent 0.05 687 3,433 203,360 24,562 7,157 7,755 729 NA1

SNCR/SCR 

Hybrid 0.18 2,471 1,648 115,151 17,306 10,503 37,887 346 1,762 

ROFA/ 

Rotamix 0.20 2,746 1,373 30,790 6,902 5,027 8,024 1,413 3 

Rotamix 

(SNCR) 0.23 3,158 961 11,822 3,597 3,742 117 51 4 

SNCR 0.23 3,158 961 17,392 5,400 5,618 80 43 NA1

ROFA 0.26 3,570 549 19,256 3,549 6,462 -- 1,363 NA1

Consent 

Decree 0.30 4,119 2,060 14,126 1,378 669 NA NA1

 NA1

Pre-CD 0.45 6,179 NA NA NA NA NA NA NA1

Unit 3

SCR + 

sorbent 0.05 1,072 5,359 264,208 32,585 6,080 6,313 1,107 NA1

SNCR/SCR 

Hybrid 0.18 3,859 2,572 178,759 26,604 10,342 39,171 507 2,658 

ROFA/ 

Rotamix 0.20 4,287 2,144 35,724 9,810 4,576 7,498 2,810 5 

Rotamix 

(SNCR) 0.23 4,931 1,501 13,919 4,988 3,324 -378 84 5 

SNCR 0.23 4,931 1,501 17,163 8,224 5,480 -578 51 NA1

ROFA 0.26 5,574 857 22,081 5,231 6,100 -- 2,725 NA1

Consent 

Decree 0.30 6,431 2,573 12,715 1,240 482 NA NA1

 NA1

Pre-CD 0.42 9,004 NA NA NA NA NA NA NA1

Unit 4

SCR + 

sorbent 0.05 1,052 5,257 235,940 29,508 5,613 5,623 1,102 NA1

SNCR/SCR 

Hybrid 0.18 3,786 2,524 171,412 25,808 10,226 38,034 507 2,658 

ROFA/ 

Rotamix 0.20 4,206 2,103 35,724 9,810 4,664 7,643 2,810 5 

Rotamix 

(SNCR) 0.23 4,837 1,472 13,919 4,988 3,388 -385 84 5 

SNCR 0.23 4,837 1,472 17,163 8,224 5,587 -590 51 NA1

ROFA 0.26 5,468 841 22,081 5,231 6,218 -- 2,725 NA1

Consent 

Decree 0.30 6,309 2,524 12,870 1,256 498 NA NA1

 NA1

Pre-CD 0.42 8,833 NA NA NA NA NA NA NA1

1

 PNM performed an impact analysis for these technologies and incorporated any monetized 

energy or non-air environmental impacts into the cost analysis. 

The 2013 RH SIP revision includes a new analysis to inform the State’s BART 

determination and its weighing of the statutory factors for BART. This analysis contemplates 

three scenarios, SCR on all four units, SNCR on all four units, and the State Alternative, which 

includes unit shutdowns and SNCR on the remaining operating units. Table 5 summarizes the 
20 

cost and impact analysis of the three scenarios from Table 4. The remaining useful life of the 

units with installed control technologies (units not being retired) was determined to be 30 years 

and therefore, the statutory factor of the remaining useful life of the source does not weigh in 

favor of any option over another. New Mexico estimated the cost-effectiveness of the State 

Alternative at $1,049/ton compared to $6,218/ton for the four SCR scenario, and $5,561/ton for 

the four SNCR scenario. 

 

Table 5. New Mexico’s Analysis of Impacts and Cost Effectiveness of the Three NOx Control 

Scenarios 

Control Scenario NOx 

Emission 

Level 

NOx 

Emissions 

(TPY) 

NOx 

Emission 

Reduction 

(TPY) 

Total 

Capital 

Investment 

(TCI) 

(1000$) 

Total 

Annualized 

Cost (TAC) 

(1000$) 

Cost 

Effectiveness 

($/ton) 

Energy 

Impacts 

SCR All Units (FIP) 

SJGS 1 – SCR 0.05 690 3,450 180,862 22,165 6,425 746 

SJGS 2 – SCR 0.05 687 3,433 180,862 24,562 7,157 729 

SJGS 3 – SCR 0.05 1,072 5,359 264,208 32,585 6,080 1,107 

SJGS 4 – SCR 0.05 1,052 5,258 235,940 29,508 5,613 1,102 

Total 3,500 17,500 861,871 108,820 6,218 3,683 

SNCR All Units (State’s 2011 BART Determination) 

SJGS 1 – SNCR 0.23 3,174 966 17,392 5,400 5,590 43 

SJGS 2 – SNCR 0.23 3,158 961 17,392 5,400 5,618 43 

SJGS 3 – SNCR 0.23 4,931 1,501 17,163 8,224 5,480 51 

SJGS 4 – SNCR 0.23 4,837 1,472 17,163 8,224 5,587 51 

Total 16,100 4,900 69,111 27,248 5,561 187 

SNCR Units 1&4 (State Alternative) 

SJGS 1 – SNCR 0.23 3,174 966 17,392 5,400 5,590 43 

SJGS 2 – retire n/a n/a 4,119 n/a n/a n/a n/a 

SJGS 3 – retire n/a n/a 6,431 n/a n/a n/a n/a 

SJGS 4 – SNCR 0.23 4,837 1,472 17,163 8,224 5,587 51 
21 

Total 8,011 12,989 34,556 13,624 1,049 94 

New Mexico also examined the energy and non-air quality environmental impacts of the 

three scenarios. Compared to current operations and the four SCR and four SNCR scenarios, the 

State Alternative results in: 

 up to a 53% decrease in water usage at the facility (from 21,000 acre-feet to 10,161 acrefeet); 

 a wastewater generation reduction of up to 50%; 

 reduced energy and non-air quality environmental impacts from decreased raw material 

usage and resource savings, including reduced limestone mining, diesel refining, carbon 

activation, and coal mining associated with operations at SJGS;20 and 

 50% reduction in solid waste (from 1.71 million tons per year to 854,130 tons per year). 

New Mexico determined that these energy and non-air quality environmental benefits 

weighed heavily in favor of the State Alternative over the four SCR and four SNCR scenarios. 

In addition to the energy and non-air quality environmental benefits outlined above, New 

Mexico noted that the State Alternative will also result in a substantial decrease in PM emissions 

from coal processing, handling, and transportation, as well as reductions in greenhouse gas 

emissions, mercury and other hazardous air pollutant emissions, and acid gas emissions from the 

facility. 

Step 5- Evaluate Visibility Impacts: The final factor to consider in the BART analysis is the 

degree of visibility improvement anticipated to result from the BART control options. The 

BART guidelines recommend use of the CALPUFF air quality dispersion model to estimate the 

visibility improvements at each Class I area, typically within a 300 km (186 mile) radius of the 

source, of alternative control technologies, and to compare these to each other and to the impact 

of the baseline, or current, source configuration. As part of its 2011 RH SIP revision, New 

Mexico submitted the initial and revised visibility modeling performed by PNM for the SJGS 

that included modeled visibility impacts at the sixteen Class I Areas within 300 km of the facility 

(Figure 4). For a detailed description and our review of this modeling, see the Technical Support 

Document (TSD) that accompanied the proposed FIP (referred to as the “2011 EPA TSD”). In 

this earlier analysis, SCR was modeled at an emission rate of 0.07 lb/MMBtu. 

                                                            

20 Table 23 of Appendix D of the 2013 RH SIP revision quantifies the reduction in raw material usage. 
22 

Figure 4. Class I areas within 300km of the San Juan Generating Station 

The PNM submitted an updated visibility analysis (see Exhibit 6 of the 2013 RH SIP revision) to 

New Mexico for evaluation that included revised emission rates for SO2, and H2SO4, and a 

revised background ammonia concentration of 1 ppb. The background ammonia concentration of 

1 ppb is consistent with the background ammonia concentration used in our earlier modeling 

analysis and detailed in the 2011 EPA TSD. The SO2 emission rate for the four SCR and four 

SNCR control scenarios was updated to 0.15 lb/MMBtu, consistent with the EPA modeling in 

support of the FIP, reflective of the emission rate determined by the EPA in its August 22, 2011, 

final action to be necessary to satisfy the CAA’s visibility transport requirements, and set in the 

submitted 2011 VT SIP revision. The SO2 emission rate for the State Alternative was updated to 

reflect the more stringent SO2 limit that results from implementation of the State Alternative. 

The H2SO4 modeled emission rates were revised to be consistent with the estimated current 

emission rates calculated by the EPA and detailed in the 2011 EPA TSD. The 2013 analysis 

used the same modeling protocol followed by the EPA in support of the FIP and detailed in the 

2011 EPA TSD. This modeling compared the three control scenarios mentioned above. These 

modeling scenarios are summarized in Table 6 below (Table 21 of Appendix D of the 2013 RH 

SIP revision). 

Table 6. Updated Visibility Modeling Scenarios 
23 

Scenario Operating condition and emissions modeled. 

Baseline Units 1-4 operating only with existing air pollution control technology and new 

permitted SO2 and Total Particulate Matter (TPM) emission rates of 0.15 lb/MMBtu and 

0.034 lb/MMBtu, respectively. 

Sulfuric Acid (H2SO4) emission rate of 0.000046 lb/MMBtu 

4 SCR Units 1-4 operating with existing air pollution control technology and with new SCR 

installation; NOx at 0.05 lb/MMBtu and new permitted SO2 and TPM emission rates of 

0.15 lb/MMBtu and 0.034 lb/MMBtu, respectively. 

Sulfuric Acid (H2SO4) emission rate of 0.00026 lb/MMBtu 

4 SNCR Units 1-4 operating with existing air pollution control technology and with new SNCR 

installation; NOx at 0.23 lb/MMBtu and new permitted SO2 and TPM emission rates of 

0.15 lb/MMBtu and 0.034 lb/MMBtu, respectively. 

Sulfuric Acid (H2SO4) emission rate of 0.000046 lb/MMBtu 

2 

SNCR/2shut

down 

Units 2 & 3 retired, Units 1 & 4 operating with existing air pollution control technology 

and with new SNCR installation; NOx at 0.23 lb/MMBtu, permitted TPM emission rate 

of 0.034 lb/MMBtu, and a reduced SO2 emission rate of 0.10 lb/MMBtu. 

Sulfuric Acid (H2SO4) emission rate of 0.000046 lb/MMBtu 

A description of the modeling protocol followed for the 2011 and 2013 analysis can be found in 

Appendix D of the 2013 NM RH SIP beginning page 19 and is summarized below in Table 7. A 

summary of visibility modeling inputs from both the 2011 modeling analysis and the 2013 

updated modeling analysis can be found in Tables 16 thru 19 of Appendix D of the 2013 NM RH 

SIP and Section 7.6 of the 2013 PNM report. 

Table 7. Key CALPUFF modeling options and inputs 

 2011 Modeling 2013 Modeling 

Model Version 

 CALMET 6.211 5.8 

 CALPUFF 6.112 5.8 

 POSTUTIL 1.52 1.56 

 CALSUM 1.33 1.33 

 CALPOST 6.131 6.221 

Key CALMET settings 

DGRIDKM Grid spacing (km) 4 4 

NZ Number of layers 11 11 

NOOBS 

1 = use of surface and precipitation (no upper air 

observations ); 0 = use of surface, precipitation, 

and upper air observations 

1 0 

RMAX1 Maximum radius of influence (surface layer, km) 50 100 

RMAX2 Maximum radius of influence (aloft layers, km) 100 200 

R1 Relative weighting of first guess wind field and 

observation (km) 100 50 

R2 Relative weighting aloft 200 100 
24 

Key CALPUFF inputs 

 Background Ammonia 

Monthly variable (ppb); 

[0.2,0.2,0.5,0.5, 

1,1,1,1,1,0.5,0.5,0.2] 

Constant 1ppb 

 SCR controlled NOx emission rate 0.07 lb/MMBtu 0.05 lb/MMBtu 

 Sulfuric Acid emission rate assume all inorganic 

condensable PM is H2SO4. 

Electric Power 

Research Institute 

methodology 

CALPOST 

Method 6 utilizes the IMPROVE equation; 

Method 8 utilizes the “revised” IMPROVE 

equation 

Method 6 Method 8 

 

Table 8. Modeled Emission Rates (lb/hr) 

 Unit 1 Unit 2 Unit 3 Unit 4 

Baseline (post-consent decree controls) 

SO2 556.1 553.2 863.7 847.4 

SO4 0.17 0.17 0.27 0.26 

NOx 1223.3 1217.0 1900.1 1864.2 

SOA 14.09 14.01 21.88 21.47 

PM fine 30.56 30.40 47.46 46.59 

PM coarse 23.57 23.49 36.67 35.95 

EC 1.51 1.51 2.38 2.30 

4 SCR control scenario 

SO2 556.1 553.2 863.7 847.4 

SO4 0.96 0.96 1.50 1.47 

NOx 185.4 184.4 287.9 282.5 

SOA 14.09 14.01 21.88 21.47 

PM fine 30.56 30.40 47.46 46.59 

PM coarse 23.57 23.49 36.67 35.95 

EC 1.51 1.51 2.38 2.30 

4 SNCR control scenario 

SO2 556.1 553.2 863.7 847.4 

SO4 0.17 0.17 0.27 0.26 

NOx 852.6 848.2 1324.30 1299.30 

SOA 14.09 14.01 21.88 21.47 

PM fine 30.56 30.40 47.46 46.59 

PM coarse 23.57 23.49 36.67 35.95 

EC 1.51 1.51 2.38 2.30 

2 SNCR/ 2 shutdown control scenario

SO2 370.7 --- --- 564.9 

SO4 0.17 --- --- 0.26 

NOx 852.6 --- --- 1299.30 

SOA 14.09 --- --- 21.47 

PM fine 30.56 --- --- 46.59 
25 

PM coarse 23.57 --- --- 35.95 

EC 1.51 --- --- 2.30 

Table 9. Modeled Stack Parameters 

 Stack 

Height (M) 

Base 

Elevation 

(M) 

Stack 

Diameter 

(M) 

Stack Exit 

Velocity 

(M/s) 

Stack Exit 

Temp (K) 

Unit 1 121.92 1615.44 6.10 21.34 322.83 

Unit 2 121.92 1615.44 6.10 21.34 322.83 

Unit 3 121.92 1615.44 8.53 17.07 322.83 

Unit 4 121.92 1615.44 8.53 16.76 322.83 

Table 10 below shows the results of New Mexico’s visibility modeling. This modeling summary 

depicts the visibility improvement for the 98th percentile21 of modeled results over the baseline 

for each control scenario. In comparing the four-SCR scenario to the State Alternative, the 

largest average difference over three years is 0.47 dv at Mesa Verde, 0.24 dv at Canyonlands, 

and 0.13 dv at Weminuche. The average difference at the 13 other Class I areas is less than 0.1 

dv between the two control scenarios. Figure 5 below (figure 10-2 in the NM RH SIP) displays 

the 2013 visibility modeling analysis results for each modeled year and the average across all 16 

Class I areas for each control scenario. 

Table 10. Modeled Average Visibility Improvement of the 98th Percentile Delta-dv Impacts from 

2001-200322

Class I area 

Distance 

to SJGS 

(km) 

Improvement over Baseline Improvement 

of 4 SCR 

over 4 SNCR 

Improvement of 

4 SCR over State 

Alternative 4 SCR 4 

SNCR 

State 

Alternative 

Arches 222 1.30 0.48 1.23 0.82 0.07 

Bandelier Wilderness 210 0.77 0.28 0.78 0.49 -0.01 

Black Canyon of the 

Gunnison Wilderness 203 0.77 0.28 0.72 0.49 0.05 

Canyonlands 170 2.02 0.64 1.78 1.38 0.24 

Capitol Reef 232 0.70 0.25 0.74 0.45 -0.04 

Grand Canyon 285 0.30 0.10 0.34 0.20 -0.04 

Great Sand Dunes National 

Monument 269 0.77 0.29 0.74 0.48 0.03 

La Garita Wilderness 169 1.01 0.37 0.95 0.64 0.06 

                                                            

21  The visibility analysis focuses on the 98th percentile of modeled results to avoid giving undue weight to any

extreme results. See 70 FR 39121.

22 Table 10-4 of the 2103 NM RH SIP. 
26 

Maroon Bells-Snowmass 

Wilderness 271 0.35 0.13 0.35 0.22 0.00 

Mesa Verde 40 2.91 0.61 2.44 2.30 0.47 

Pecos Wilderness 248 0.68 0.24 0.69 0.44 -0.01 

Petrified Forest 213 0.26 0.11 0.29 0.15 -0.03 

San Pedro Parks 

Wilderness 155 1.38 0.47 1.29 0.91 0.09 

West Elk Wilderness 216 0.87 0.31 0.79 0.56 0.08 

Weminuche Wilderness 98 1.55 0.47 1.42 1.08 0.13 

Wheeler Peak Wilderness 258 0.64 0.25 0.67 0.39 -0.03 

Figure 5. Comparison of Visibility Improvement of Alternatives at San Juan Generating Station. 

A.1.b. NMED’s NOx BART Determination: 

State Submittal (pages 10-14 to 10-16) 

2013 BART Determination 
27 

The Department considered the terms of the non-binding agreement between the EPA, NMED 

and PNM, signed February 15, 2013 (the “State Alternative”), and the resulting significant 

environmental improvements of this alternative and compared this scenario to the 4 SNCR and 4 

SCR scenarios previously evaluated. The Department’s determination of BART was based on 

consideration of the BART statutory factors in the context of the following elements of the State 

Alternative (2 SNCR/2 Shutdown). 

1) PNM will retire Units 2 and 3 by December 31, 2017. These retirements do not give 

rise to control equipment costs requiring amortization. The remaining useful life of the 

source is defined as 30 years for the three scenarios described (4 SCR, 4 SNCR, 2 

SNCR/2 Shutdown). Therefore, the statutory factor of the remaining useful life of the 

source does not weigh in favor of any option over another. 

2) PNM will obtain the necessary construction permit modification to limit the SO2 

emission rates at Units 1 and 4 to 0.10 lb/MMBtu on a daily rolling 30-day average 

basis. These SO2 emission reductions occur separately and apart from the SO2 backstop 

trading program that EPA has already approved as satisfying BART. In addition to 

increased visibility improvement, these SO2 reductions will lead to non-air quality 

environmental benefits, such as decreased acid deposition. 

3) The retirement of Units 2 and 3 will reduce the facility annual NOx emissions by an 

additional 10,550 tons. When added to the controlled emission rate of Units and 1 and 4, 

total annual NOx emission will be reduced by 12,989 tons. Additionally, PNM will 

conduct performance testing to determine if the SNCRs installed on Units 1 and 4 can 

achieve significantly less than 0.23 lb/MMBtu. 

4) The 2 SNCR/2 Shutdown scenario would result in less material usage than the 4 SCR 

and 4 SNCR scenarios. See Table 23. This will result in less limestone required to be 

transported and mined, less diesel fuel that would need to be refined for this power plant, 

less coal mined and less carbon that would need to be activated. Closure of two units will 

result in up to 53 percent less water used, from 21,000 acre-feet to 10,161 acre-feet; 

wastewater generated will be reduced by up to 50 percent, from 41 million gallons to 21 

million gallons; and solid waste generated will be reduced by up to 50 percent, from 1.71 

million tons per year to 854,130 tons per year. 

Table 23: Raw Material Usage Comparison 

Raw Material 2 SNCR/2 

Shutdown (TPY) 

Baseline, 4 

SNCR, and 4 SCR 

Limestone(1) 86,052 172,104 

Activated 

Carbon(1) 

130 261 
28 

Coal(2) 2,667,364 5,334,729 

No. 2 Diesel 

Oil(2) 

1,007,336 2,014,671 

(1) Based on 2012 material usage data. 

(2) Based on 2011 material usage data. 

The energy and non-air quality environmental benefit of these resource savings 

weighs heavily in favor of the 2 SNCR/2 Shutdown scenario over the 4 SCR and 4 SNCR 

scenarios. 

. 

5) The two-unit retirement scenario will result in a substantial decrease in particulate 

matter emissions from coal processing, handling and transportation, as well as a 

substantial reduction in greenhouse gas emissions, mercury and other hazardous air 

pollutant emissions, and acid gas emissions as detailed in Table 24 below. The non-air 

quality environmental benefits of these reductions, such as less impact on climate and 

less deposition of mercury to waterways, weigh heavily in favor of the 2 SNCR/2 

Shutdown scenario 

6) Table 22 shows the average visibility improvement between the three scenarios of 4 

SCR, 4 SNCR and 2 SNCR/2 unit shutdown. The 2 SNCR/2 Shutdown scenario achieves 

significant visibility improvements as compared to the baseline and installation of SNCR 

on Units 1-4. The visibility improvements from the State Alternative of SNCR on two units 

and two units shutdown compare very closely with the SCR installation scenario as 

contained in the FIP (less than 0.5 dv impact at any Class I area). For the 4 SCR and 2 

SNCR/2 Shutdown scenarios, the average difference over three years is 0.47 dv at Mesa 

Verde and 0.24 dv at Canyonlands. 

Therefore, with respect to the statutory factor of the degree of visibility improvement 

anticipated, the 2 SNCR/2 unit shutdown scenario is superior to the 4 S[N]CR scenario, 

and substantially equivalent to the 4 SCR scenario. 

7) Table 10 includes the cost in dollars per ton for SCR and SNCR, as well as other 

scenarios. The total capital investment of the FIP 4 SCR scenario is estimated at nearly 

$861,871,000, as compared to $34,556,000 for the installation of SNCR at Units 1 and 4. 

This additional and significant capital expenditure that would be required to comply with 

the 4 SCR scenario is not justified given the slight improvement in visibility of the 4 SCR 

scenario over the 2 SCR/2 Shutdown scenario. 

8) Finally, with respect to the statutory requirement to consider existing pollution 

controls at the source, such existing pollution control equipment was evaluated for all 
29 

alternatives beginning in Step 1 of the analysis, and is outlined in Table 10. NMED 

determined that existing control equipment is not sufficient to meet BART requirements 

for NOx at San Juan Generating Station. This factor has no further relevance in selecting 

among the control options in this case. 

Weighing all the above considerations as required by CAA § 169A, the Department has 

determined that the State Alternative (2 SNCR/2 Shutdown), which achieves substantial 

environmental benefits beyond the requirements of the FIP (4 SCR), the SIP (4 SNCR) and the 

requirements of the BART Guidelines at 40 CFR Part 51 Appendix Y at a significantly lower cost 

than the FIP scenario of 4 SCRs, satisfies the statutory and regulatory requirements of BART. 

A.1.c EPA’s Evaluation Regarding NOx BART Determination for SJGS: 

The FIP that became effective on September 21, 2011 previously established NOX 

BART for SJGS at the emission rate of 0.05 lb/MMBtu on a 30 boiler operating day average, 

achievable through installation and operation of an SCR retrofit on all four units (76 FR 52388; 

August 22, 2011). 23 At the outset, we note that the NOX BART determination for the SJGS that 

was submitted by New Mexico to replace the FIP cannot be disapproved solely on the basis that 

it differs from the determination established in the FIP. The CAA defines a FIP as “a plan (or 

portion thereof) promulgated by the Administrator to fill all or a portion of a gap or otherwise 

correct all or a portion of an inadequacy in a [SIP].” CAA section 302(y). Because a FIP is 

intended as a gap-filling measure, the EPA encourages states to submit approvable SIP revisions 

that correct the deficiencies that a given FIP remedied. Such a SIP revision need not adopt the 

same suite of control options and techniques as the EPA’s FIP, nor does it necessarily have to be 

as stringent as the EPA’s FIP in all instances. Rather, when a State submits a SIP revision to the 

EPA with the intention of replacing a FIP, the EPA must approve the SIP revision so long as the 

SIP revision does not “interfere with any applicable requirement concerning attainment and 

reasonable further progress . . . or any other applicable requirement of [the Act].” CAA section 

110(l). In regards to regional haze SIPs and the statutory requirement to make BART 

determinations for certain older major stationary sources, the EPA must approve a State’s SIP 

revision so long as the State complies with the CAA’s visibility protection provisions, the RHR, 

and the BART Guidelines, and makes a reasonable control determination based on the weighing 

of the five factors. We have analyzed New Mexico’s new NOX BART determination with these 

requirements in mind. 

                                                            

23 The proposed FIP, the TSD, and Final Rule are added to the docket for this rule making. These records contain 

significant technical analyses that we consider available to commenters for this proposed action on the State’s 

submittal. 
30 

The record supports the proposal to conclude that New Mexico has met the requirements 

of 40 CFR 309(d)(4)(vii) and the BART Guidelines in determining NOx BART for SJGS. This 

conclusion is based on our review of the 2013 RH SIP revision, including the applicable permit 

conditions and all supporting analyses identified above. The record also supports the proposal to 

withdraw the FIP requirements pertaining to regional haze and rescind the emission limits for 

NOx and H2SO4

24, as well as the accompanying compliance schedule that would otherwise apply 

to SJGS. Upon final approval of the 2013 RH SIP revision, the FIP requirements may be 

withdrawn through a separate Administrator-signed final action. Additionally, our final approval 

action, if finalized as proposed, will moot the 2011 RH SIP revision concerning the four-SNCR 

scenario. 

New Mexico’s revised BART determination includes a control scenario proposed by 

PNM that includes the shutdown of two of the four units at the SJGS by December 31, 2017. As 

such, the control scenario in this analysis is different than the control scenarios contemplated in 

the FIP. Although the EPA’s regulations do not require states to consider a fuel switch or a 

shutdown of an existing unit as part of their BART analyses, a state may include such options in 

its analysis where a company voluntarily offers such measures as a strategy for reducing 

emissions. As discussed previously, New Mexico determined that the State Alternative was NOX 

BART for the SJGS. New Mexico made this determination based on an analysis of the five 

BART factors. Their analysis of the five BART factors included consideration of the high 

incremental cost-effectiveness and low incremental visibility improvement of the FIP compared 

with the State Alternative, as well as the additional non-air quality environmental and energy 

benefits of the latter. The energy and non-air quality environmental impacts, such as reduced 

solid waste generation, waste water generation, and water and energy usage, associated with the 

State Alternative scenario support the conclusion that the State Alternative is BART. 25 New 

Mexico also noted additional air quality benefits associated with shutting down Units 2 and 3. 

While important, these other air quality benefits, such as reduced ozone and PM formation, 

reduced greenhouse gases, and reduced mercury deposition, are not among the BART factors, 

and were not considered in our evaluation of the State’s NOx BART determination. 

While the BART Guidelines require states to analyze visibility improvement on a facility-wide 

basis, 26 states have typically analyzed the costs of compliance and other BART factors for each 

                                                            

24 Since we are proposing to approve the State Alternative that does not include SCR operation, we are also 

proposing to withdraw the H2SO4 emission limit in the FIP as it is no longer necessary to protect visibility 

impairment from the facility due to emissions of H2SO4. 25 [T]he State must take into consideration 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 improvement in visibility which may reasonably be anticipated to result 

from the use of such technology. 40 CFR 51.308(e)(1)(ii)(A). 

26 The BART Guidelines state that “you must conduct a visibility improvement determination for the source(s) as 

part of the BART determination.” 40 CFR pt. 51, app. Y, section IV.D.5 (emphasis added). 
31 

individual emission unit that comprises the BART-eligible source. Nevertheless, we do not 

interpret the BART Guidelines as requiring states to use this approach with regards to analyzing 

the other BART factors. Instead, we believe that states have the flexibility to analyze these 

factors on either a unit-specific or facility-wide basis, depending on the unique facts of each 

case. Here, we believe that New Mexico’s decision to evaluate the BART factors on a facilitywide basis was a reasonable way to take into account the visibility, energy, and non-air quality 

environmental benefits associated with unit shutdowns. Had New Mexico used a unit-specific 

approach, these benefits would have been discounted altogether, which would unfairly prevent 

states and sources from considering unit shutdowns as a viable strategy for achieving BART. 

New Mexico’s approach is also consistent with the State’s separate objective to meet the goodneighbor requirement of the CAA for visibility, i.e., to ensure that collective emissions from the 

SJGS are not interfering with other states’ measures to protect visibility. 

i. Visibility Analysis 

We reviewed the CALPUFF modeling that supported the visibility impact analysis in the 

2013 RH SIP revision. The revised CALPUFF modeling followed a modeling protocol 

consistent with the EPA guidance and recommendations, as well as the modeling performed by 

the EPA in support of the FIP. Modeled emission rates were revised to reflect SCR control 

efficiency evaluated in our FIP analysis, as well as the sulfuric acid emission rate estimated using 

the EPA’s methodology as described in the 2011 EPA TSD. Please see Appendix D and Exhibit 

6 of the 2013 RH SIP revision for more details concerning the modeling inputs, model results, 

and New Mexico’s evaluation. The visibility modeling protocol and key inputs are summarized 

in the previous section, and in Tables 6 and 7. We note that New Mexico modeled the visibility 

improvement from the State Alternative by including the additional SO2 reductions attributable 

to the implementation of the State Alternative, but did not include those reductions in the other 

modeling scenarios. 27 While we have some concerns with the appropriateness of including SO2 

reductions from Units 1 and 4 in one of the NOx BART control options analyzed, rather than as 

part of the facility’s baseline emissions, we note that the visibility benefits associated with the 

State Alternative are predominately due to NOx reductions resulting from installation of SNCR 

and the significant emission reductions associated with the shutdown of Units 2 and 3. As a 

result, we do not think the inclusion of these additional SO2 emission reductions meaningfully 

impact our evaluation of the visibility benefits of the evaluated control scenarios. 

The modeling results for each modeled scenario are available in section 7.8 of the 2013 

PNM report and are reproduced below. 

Table 11. Baseline Visibility Results, 98th percentile (dv) 

                                                            

27 The SO2 emission limit of 0.10 lb/MMBtu for Units 1 and 4 is effective as of March 5, 2014. 
32 

Class I area 2001 2002 2003 Average Maximum 

Arches 3.51 0.96 1.52 1.99 3.51 

Bandelier Wilderness 1.40 1.30 1.03 1.24 1.40 

Black Canyon of the 

Gunnison Wilderness 1.36 1.41 0.63 1.13 1.41 

Canyonlands 4.66 2.12 2.29 3.02 4.66 

Capitol Reef 2.39 0.46 0.66 1.17 2.39 

Grand Canyon 0.93 0.26 0.38 0.52 0.93 

Great Sand Dunes National 

Monument 0.85 1.54 1.08 1.16 1.54 

La Garita Wilderness 1.39 1.94 1.14 1.49 1.94 

Maroon Bells-Snowmass 

Wilderness 0.71 0.61 0.34 0.55 0.71 

Mesa Verde 5.16 5.22 5.02 5.13 5.22 

Pecos Wilderness 0.94 1.27 1.03 1.08 1.27 

Petrified Forest 0.52 0.46 0.38 0.45 0.52 

San Pedro Parks Wilderness 2.21 1.98 2.08 2.09 2.21 

West Elk Wilderness 1.59 1.43 0.68 1.24 1.59 

Weminuche Wilderness 2.15 2.95 2.02 2.37 2.95 

Wheeler Peak Wilderness 1.12 1.10 0.91 1.04 1.12 

Table 12. 4 SCR Visibility Results, 98th percentile (dv) 

Class I area 2001 2002 2003 Average Maximum 

Arches 1.13 0.49 0.46 0.69 1.13 

Bandelier Wilderness 0.49 0.49 0.42 0.47 0.49 

Black Canyon of the 

Gunnison Wilderness 0.42 0.42 0.26 0.36 0.42 

Canyonlands 1.57 0.69 0.75 1 1.57 

Capitol Reef 0.83 0.25 0.32 0.47 0.83 

Grand Canyon 0.33 0.13 0.2 0.22 0.33 

Great Sand Dunes National 

Monument 0.32 0.5 0.35 0.39 0.5 

La Garita Wilderness 0.5 0.58 0.36 0.48 0.58 

Maroon Bells-Snowmass 

Wilderness 0.28 0.19 0.14 0.2 0.28 

Mesa Verde 2.17 2.15 2.33 2.22 2.33 

Pecos Wilderness 0.4 0.48 0.33 0.4 0.48 

Petrified Forest 0.2 0.16 0.22 0.19 0.22 

San Pedro Parks Wilderness 0.72 0.75 0.67 0.71 0.75 

West Elk Wilderness 0.46 0.4 0.23 0.37 0.46 

Weminuche Wilderness 0.83 0.92 0.73 0.82 0.92 

Wheeler Peak Wilderness 0.42 0.45 0.32 0.4 0.45 
33 

Table 13. 4 SNCR Visibility Results, 98th percentile (dv) 

Class I area 2001 2002 2003 Average Maximum 

Arches 2.67 0.72 1.15 1.51 2.67 

Bandelier Wilderness 1.08 0.98 0.8 0.96 1.08 

Black Canyon of the 

Gunnison Wilderness 1.01 1.07 0.47 0.85 1.07 

Canyonlands 3.71 1.62 1.81 2.38 3.71 

Capitol Reef 1.82 0.38 0.56 0.92 1.82 

Grand Canyon 0.72 0.24 0.3 0.42 0.72 

Great Sand Dunes National 

Monument 0.65 1.15 0.81 0.87 1.15 

La Garita Wilderness 1.05 1.47 0.85 1.12 1.47 

Maroon Bells-Snowmass 

Wilderness 0.53 0.46 0.27 0.42 0.53 

Mesa Verde 4.67 4.43 4.47 4.52 4.67 

Pecos Wilderness 0.73 1 0.78 0.84 1 

Petrified Forest 0.39 0.34 0.31 0.34 0.39 

San Pedro Parks Wilderness 1.72 1.56 1.59 1.62 1.72 

West Elk Wilderness 1.21 1.07 0.51 0.93 1.21 

Weminuche Wilderness 1.74 2.36 1.61 1.9 2.36 

Wheeler Peak Wilderness 0.86 0.83 0.67 0.79 0.86 

Table 14. State Alternative 2 SNCR/2 Shutdown Visibility Results, 98th percentile (dv) 

Class I area 2001 2002 2003 Average Maximum 

Arches 1.37 0.35 0.55 0.76 1.37 

Bandelier Wilderness 0.52 0.48 0.39 0.46 0.52 

Black Canyon of the 

Gunnison Wilderness 0.49 0.52 0.22 0.41 0.52 

Canyonlands 1.99 0.82 0.91 1.24 1.99 

Capitol Reef 0.89 0.16 0.24 0.43 0.89 

Grand Canyon 0.33 0.09 0.13 0.18 0.33 

Great Sand Dunes National 

Monument 0.31 0.57 0.39 0.42 0.57 

La Garita Wilderness 0.5 0.71 0.41 0.54 0.71 

Maroon Bells-Snowmass 

Wilderness 0.26 0.21 0.12 0.2 0.26 

Mesa Verde 2.8 2.65 2.61 2.69 2.8 

Pecos Wilderness 0.35 0.47 0.37 0.39 0.47 

Petrified Forest 0.19 0.16 0.13 0.16 0.19 

San Pedro Parks Wilderness 0.87 0.74 0.79 0.8 0.87 

West Elk Wilderness 0.58 0.53 0.25 0.45 0.58 

Weminuche Wilderness 0.85 1.21 0.79 0.95 1.21 

Wheeler Peak Wilderness 0.4 0.39 0.33 0.37 0.4 
34 

 Figure 6. Visibility Impact Results (Figure 7-2 of 2013 PNM Report) 

The modeling results indicate the largest differences in average 98th percentile impacts 

over the three modeled years between the four-SCR scenario and the State Alternative are 0.47 

dv at Mesa Verde, 0.24 dv at Canyonlands, and 0.13 dv at Weminuche. The average difference at 

the 13 other Class I areas is less than 0.1 dv between the two control scenarios. The largest 

differences in maximum impacts over the three modeled years are 0.47 dv at Mesa Verde, 0.42 

dv at Canyonlands, 0.29 dv at Weminuche, and 0.24 dv at Arches. Table 16 shows the 

percentage reduction in visibility impairment from the baseline for the three control scenarios 

evaluated. The largest average differences occur at Mesa Verde (9%), Canyonlands (7%), and 

West Elk (7%). At Capitol Reef, Grand Canyon and Petrified Forest, the 2 SNCR/2 Shutdown 

scenario of the State alternative results in greater average reduction in visibility impairment than 

the 4 SCR scenario of -10%, -11% and -9%, respectively. 

Table 15. 2001-2003 average percent reduction in visibility impairment (98th percentile) from 

the baseline to the 3 evaluated control scenarios. 

Class I area 4 SNCR 4 SCR 2 SNCR/2 

Shutdown 

Difference between 4 

SCR and 2 SNCR/ 2 

Shutdown 

Arches 24% 62% 63% -1% 

Bandelier Wilderness 23% 62% 63% -1% 

Black Canyon of the Gunnison 

Wilderness 25% 66% 64% 2% 

Canyonlands 22% 67% 60% 7% 

Capitol Reef 19% 54% 64% -10% 

Grand Canyon 17% 54% 65% -11% 
35 

Great Sand Dunes National 

Monument 25% 66% 63% 2% 

La Garita Wilderness 25% 68% 64% 4% 

Maroon Bells-Snowmass 

Wilderness 24% 63% 65% -2% 

Mesa Verde 12% 57% 48% 9% 

Pecos Wilderness 23% 63% 63% -1% 

Petrified Forest 23% 56% 65% -9% 

San Pedro Parks Wilderness 22% 66% 62% 4% 

West Elk Wilderness 25% 70% 63% 7% 

Weminuche Wilderness 20% 65% 60% 5% 

Wheeler Peak Wilderness 25% 62% 64% -2% 

An analysis of the difference in the average number of days with impacts greater than 0.5 

dv and 1 dv shows that the State Alternative results in nine fewer days with impacts greater than 

0.5 dv at Mesa Verde, but five more days with impacts greater than 1.0 dv. The number of days 

with impacts greater than 0.5 dv and 1 dv are summarized in the table below. Eleven Class I 

areas show no difference in the number of impacted days over 1 dv between the four-SCR 

scenario and the State Alternative. The modeled average number of days impacted over 0.5 dv 

between these two scenarios is 1 day or less for 11 of the Class I areas examined, with several 

Class I areas experiencing fewer days over the 0.5 dv threshold under the State Alternative 

control scenario. 

Table 16. Average number of days impacted over 0.5 and 1.0 dv 

Average number of days impacted 

over 0.5 dv 

Average number of days impacted 

over 1 dv 

Class I area 4 SCR State 

Alternative Difference 4 SCR State Alternative Difference 

Arches 13 14 -1 5 8 -3 

Bandelier Wilderness 6 7 -1 1 1 0 

Black Canyon of the 

Gunnison Wilderness 4 6 -2 1 1 0 

Canyonlands 23 22 1 8 10 -2 

Capitol Reef 6 6 0 2 2 0 

Grand Canyon 2 2 0 0 0 0 

Great Sand Dunes 

National Monument 3 4 -1 1 1 0 

La Garita Wilderness 7 9 -2 0 2 -2 

Maroon BellsSnowmass Wilderness 0 0 0 0 0 0 

Mesa Verde 109 100 9 45 50 -5 
36 

Pecos Wilderness 4 4 0 0 0 0 

Petrified Forest 1 0 1 0 0 0 

San Pedro Parks 

Wilderness 19 19 0 5 5 0 

West Elk Wilderness 3 6 -3 0 1 -1 

Weminuche 

Wilderness 35 41 -6 4 5 -1 

Wheeler Peak 

Wilderness 4 3 1 0 0 0 

 New Mexico found, and we agree, that the four-SCR scenario in the FIP results in only 

slightly more visibility benefit than the State Alternative at a few of the examined Class I areas 

when both modeled improvement at each Class I area and number of days with significant 

impacts are considered. For many of the Class I Areas, the difference in visibility impacts 

between the two scenarios is negligible. While we have some concern with the modeled visibility 

differences between the two control scenarios for Mesa Verde and Canyonlands, the record 

supports a proposal to find that the State’s decision to select the State Alternative was ultimately 

reasonable, especially considering the costs of compliance and the energy and non-air quality 

environmental impacts of the two scenarios. 

ii. Cost Analysis 

We also reviewed the cost-effectiveness analysis submitted with the 2013 RH SIP 

revision. The BART Guidelines require enhanced documentation to justify costs that 

significantly deviate from known costs of recent retrofits and to justify departures from the 

Control Cost Manual. 28 We note that the FIP originally concluded that the PNM had not 

provided the requisite justification or documentation for a variety of cost items in their previous 

cost analyses. In this instance, the cost evaluation included with the 2013 RH SIP revision is 

limited to the 2013 PNM Report submitted as Exhibit 6 of the 2013 RH SIP revision and the 

Sargent and Lundy SNCR and SCR Cost Estimates29 report, submitted as Appendix C of Exhibit 

6. New Mexico has not provided any additional documentation in the record for the various line 

items in its updated SCR cost estimates. Therefore, as a general matter, we cannot conclude that 

certain line items in SCR cost estimates are well supported. In particular, some of our more 

significant areas of concern are: inclusion of costs for a sorbent injection system, how the cost of 

the balanced draft system was assigned to SCR costs, assumptions for the amounts of fees and 

contingencies that account for almost 35% of the total project cost, and some of the assumptions 

supporting the design of the SCR box and projected catalyst demands. 

                                                            

28 See 70 FR 39168 and 39166 n.15. 

29 Public Service of New Mexico San Juan Generating Station Units 1, 2, 3 & 4, SNCR and SCR Cost Estimates, 

Final Report, Sargent and Lundy, March 29, 2013. 
37 

While we continue to have concerns with the updated cost analysis for SCR in the 2013 

RH SIP revision, we do not believe that these concerns render New Mexico’s determination 

unreasonable. Even if we were to use the cost of the four-SCR scenario estimated by the EPA in 

support of the FIP ($345 million for installation of SCR on all four units), there is a large 

difference between the four-SCR scenario and the State Alternative, which is estimated to cost 

$34.5 million. Moreover, the small difference in visibility benefits between the two scenarios and 

the environmental and energy benefits of the State Alternative continue to support the State’s 

determination that the State Alternative is BART. New Mexico came to a similar conclusion 

when considering cost estimates provided by the National Park Service (NPS), which found that 

the four-SCR scenario would cost approximately $374 million.30 Many of our concerns with 

New Mexico’s SCR cost estimates either are not applicable to its SNCR cost estimates (e.g., 

sorbent injection and balanced draft) or have a much smaller impact on the total estimated cost. 

Capital costs comprise a relatively small portion of the total cost of SNCR, where the bulk of the 

annual costs are due to the cost of sorbent. Consequently, we have chosen to rely on New 

Mexico’s cost estimates for SNCR. 

New Mexico estimated the annualized cost of the State Alternative to be $13,624,000/yr 

to reduce NOx emissions by 12,989 tons/yr, resulting in a cost-effectiveness of $1,049/ton. New 

Mexico estimated the annualized cost of the four-SCR scenario to be $108,820,000/yr to reduce 

NOx emissions by 17,500 tons/yr, resulting in a cost-effectiveness of $6,218/ton. The 

incremental cost-effectiveness to achieve the additional reduction of 4511 tons/yr between the 

two scenarios is $21,103/ton. If we use the costs for SCR from our FIP, then the annualized cost 

of the four-SCR scenario becomes $39,265,670/yr, resulting in an incremental cost-effectiveness 

of $5,684/ton. The latter incremental cost-effectiveness value is in the range of costs that states 

and the EPA have found to be reasonable in other regional haze actions. Nevertheless, when 

these costs are considered in combination with the other BART factors, including the marginal 

visibility benefits of the four-SCR scenario at most Class I areas and the unique energy and nonair quality environmental benefits associated with the State Alternative, we propose to find that 

the State made a reasonable determination. 

Table 17. Incremental Cost-Effectiveness 

Control Scenario Annualized cost

NOx Emission 

Reduction 

(tpy)

Incremental cost 

- effectiveness

State Alternative 

$13,624,000/yr 12,989 -------------- 

                                                            

30 See NMED response to comments from the NPS available as NMED Exh. 14 of the 2013 RH SIP revision. 
38 

4 SCR (NMED estimate) $108,820,000/yr 17,500 $21,103/ton 

4 SCR (EPA estimate) $39,265,670/yr 17,500 $5,684/ton 

 

iii. EPA’s Conclusion 

In conclusion, the record supports a proposal to find that when cost, energy and non-air 

quality environmental impacts, and anticipated visibility benefits are taken into consideration, 

New Mexico’s determination that the State Alternative is BART is reasonable. The State 

Alternative results in substantial visibility benefits and energy and non-air quality environmental 

benefits, and is highly cost-effective. The incremental visibility benefit of the four-SCR scenario 

of the FIP over the State Alternative is small at most Class I areas, and New Mexico reasonably 

concluded that this small additional visibility benefit did not justify the increase in costs 

associated with installation of SCR on all four units. The record supports a proposal to approve 

New Mexico’s 2013 RH SIP revision, including the 2013 permit conditions found at A112C that 

set the emission limits for Units 1 and 4, provide the methodologies for calculating the two units’ 

emission rates and showing compliance, require the shutdown of Units 2 and 3, and establish the 

testing and monitoring requirements, and the record supports a proposal to rescind the FIP 

requirements for NOX BART. Upon final approval, the FIP requirements addressing NOx 

BART for the SJGS, including the H2SO4 emission limit, may be withdrawn through a separate 

Administrator-signed final action. Additionally, our final approval action will moot the portions 

of the 2011 RH SIP revision not related to the State Alternative. 

A.2. Installation of BART: 40 CFR 51.308(e)(1)(iv) – (v) 

 Each source subject to BART must (1) install and operate BART as expeditiously as 

practicable, but in no event later than 5 years after approval of the SIP revision, and (2) maintain 

the control equipment required by this subpart and establish procedures to ensure such 

equipment is properly operated and maintained. 

State Submittal: 

New Mexico determined that the schedule provided in the 2013 RH SIP revision will 

result in the implementation of BART as expeditiously as practicable, as required under 40 CFR 

51.308(e)(1)(iv). New Mexico selected a NOX BART emission limit, achievable through 

installation and operation of an SNCR retrofit on Units 1 and 4 and the shutdown of units 2 and 
39 

3, which can be found in the preconstruction permit at A112C. In accordance with the Term 

Sheet, the permit requires: 

 Fifteen (15) months after the EPA final approval of the SIP revision, but no 

earlier than January 31, 2016, the PNM will complete installation of SNCR 

technology on the SJGS Units 1 and 4 and comply with an average nitrogen oxide 

(NOx) emission limit for Units 1 and 4 of 0.23 lb/MMBtu on a daily rolling 30-

day average basis. 

 Retirement of SJGS Units 2 and 3 by December 31, 2017. 

 

EPA’s Conclusion: 

The record supports a proposal to find that NMED has demonstrated it has the authority and 

enforceable mechanisms in place to ensure each source subject to BART will (1) install and 

operate BART as expeditiously as practicable, but in no event later than 5 years after approval of 

the SIP revision, and (2) maintain the control equipment required by this subpart and establish 

procedures to ensure such equipment is properly operated and maintained.