BILL RICHARDSON 

Governor 

DIANE DENISH 

Lieutenant Governor 

New Mexico 

ENVIRONMENT DEPARTMENT 

Air Quality Bureau 

1301 Siler Road, Building B 

Santa Fe, NM 87507 

Phone (505) 476-4300 

Fax (505) 476-4375 

www.nmenv.state.nm.us

RON CURRY 

Secretary 

SARAH COTTRELL 

Deputy Secretary 

APPENDIX A: 

New Mexico Environment Department 

Air Quality Bureau 

BART Determination 

Public Service Company of New Mexico 

San Juan Generating Station, Units 1-4 

June 21, 2010 
San Juan Generating Station 

BART Determination 

Page 1 

Regulatory Background and Introduction: 

In 1999, the EPA published a final rule to address a type of visibility impairment known as regional haze 

(64 FR 35714, July 1, 1999). This rule requires States to submit state implementation plans (SIPs) to 

address regional haze visibility impairment in 156 Federally-protected parks and wilderness areas. The 

1999 rule was issued to fulfill a long-standing EPA commitment to address regional haze under the 

authority and requirements of sections 169A and 169B of the Clean Air Act (CAA).1 

As required by the CAA, the EPA included in the final regional haze rule a requirement for Best 

Available Retrofit Technology (BART) for certain large stationary sources. The regulatory requirements 

for BART were codified at 40 CFR 50.308(e) and in definitions that appear in 40 CFR 50.301. 

The BART-eligible sources are those sources which (1) have the potential to emit 250 tons per year or 

more of a visibility impairing air pollutant, (2) were put in place between August 7, 1962 and August 7, 

1977, (3) and whose operations fall within one or more of 26 specifically listed source categories. Under 

the CAA, BART is required for any BART-eligible source which a State determines “emits any air 

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

any such area.” Accordingly, for stationary sources meeting these criteria, States must address the BART 

requirement when they develop their regional haze SIPs. 1 

The EPA published a second Regional Haze rulemaking on June 6, 2005 that made changes to the Final 

Rule published July 1, 1999. This second rulemaking was in response to a U.S. District Court of Appeals 

ruling that vacated part of the regional haze rule. The June 6, 2005 Final Rule (1) required the BART 

analysis to include an analysis of the degree of visibility improvement resulting from the use of control 

technology at BART-subject sources; (2) revised the BART provisions; (3) included new BART 

Guidelines contained in a new Appendix Y to Part 51 (Guidelines); and (4) added the requirement that 

States use the Guidelines for determining BART at certain large electrical generating units (EGUs). 1

The Guidelines also contained specific presumptive limits for SO2 and NOx for certain large EGUs based 

on fuel type, unit size, cost effectiveness, and presence or absence of pre-existing controls. For NOx 

emissions, the EPA directs states to generally require owners and operators to meet the presumptive limits 

at coal-fired EGUs greater than 200 MW with a total facility-wide generating capacity greater than 750 

MW. The presumptive limits for NOx are based on coal type, boiler type and whether SCR or SNCR are 

already installed at the source. 

Analysis of BART Eligible Sources in NM: 

In May 2006, the New Mexico Environment Department, Air Quality Bureau (Department) conducted an 

internal review of sources potentially subject to the BART rule. 

Section II of the Guidelines prescribes how to identify BART-eligible sources. States are required to 

identify those sources that satisfy the following criteria: (1) sources that fall within the 26 listed source 

categories as listed in the CAA, (2) sources that were “in existence” on August 7, 1977 but were not “in 

operation” before August 7, 1962, and (3) sources that have a current potential to emit that is greater than 

250 tons per year of any single visibility impairing pollutant. New Mexico identified 11 sources as 

BART-eligible sources as part of this review.2

 

The Guidelines then prescribe to the states how to identify those sources that are subject to BART. At 

this point, states are directed to either (1) make BART determinations for all BART-eligible sources, or 
San Juan Generating Station 

BART Determination 

Page 2 

(2) to consider exempting some of the sources from BART because they may not reasonably be 

anticipated to cause or contribute to any visibility impairment in a Class I area. New Mexico opted to 

perform an initial screening model on each of these BART-eligible sources to determine whether each 

source did cause or contribute to any visibility impairment. The Guidelines direct States that if the 

analysis shows that an individual source or group of sources is not reasonably anticipated to cause or 

contribute to any visibility impairment in a Class I area, then the States do not need to make a BART 

determination for that source or group of sources. 1 

The Western Regional Air Partnership (WRAP) performed the initial BART modeling for the state of 

New Mexico. The procedures used are outlined in the WRAP Regional Modeling Center (RMC) BART 

Modeling Protocol that is available at: 

http://pah.cert.ucr.edu/aqm/308/bart/WRAP_RMC_BART_Protocol_Aug15_2006.pdf

The basic assumptions in the WRAP BART CALMET/CALPUFF modeling used for New Mexico are as 

follows: 

i. Use of three years of modeling of 2001, 2002, and 2003. 

ii. Visibility impacts due to emissions of SO2, NOx and primary PM emissions were 

calculated. PM emissions were modeled as PM2.5. 

iii. Visibility was calculated using the Original IMPROVE equation and Annual Average 

Natural Conditions. 

Initial modeling was performed for the 11 source complexes in New Mexico with visibility estimated 

from the sources’ SO2, NOx, and PM emissions. Then for those sources whose 98th percentile visibility 

impacts at any Class I area due to their combined SO2, NOx, and PM emissions exceeded the 0.5 dv 

significance threshold, the separate contribution to visibility at Class I areas was assessed for SO2 alone 

(SO4), NOx alone (NO3), PM alone (PMF) and combined NOx plus PM emissions (NO3 + PMF).2

Of the 11 source complexes analyzed, only one source complex’s visibility impacts at any Class I area 

due to combined SO2, NOx, and PM emissions exceeded the 0.5 dv threshold (PNM San Juan Generating 

Station Boilers #1-4). Of the 10 other source complexes, none exceed a 0.33 dv impact. Consequently, 

only the PNM San Juan Boilers #1-4 were evaluated for visibility impacts.2

On November 9, 2006, the Department informed PNM that the modeling performed by the WRAP 

indicated the visibility impairment from the San Juan Generating Station (SJGS) was over the 0.5 dv 

threshold, and was therefore subject to a BART analysis. In response, Black & Veatch (B&V), on behalf 

of PNM, submitted the BART Modeling Protocol document which described the CALPUFF modeling 

methodology to be used as part of the BART engineering evaluation for Units 1-4 at the SJGS.

SJGS Source Description: 

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 

which 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 

and is delivered to the facility by conveyor. 

 
San Juan Generating Station 

BART Determination 

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The SJGS Boiler Units 1 and 2 have a unit capacity of 350 and 360 MW, respectively. The units are 

equipped with Foster Wheeler subcritical, wall-fired boilers that operate in a forced draft mode. The 

SJGS Boiler Units 3 and 4 each have a unit capacity of 544 MW and are equipped with a B&W 

subcritical, opposed wall-fired boilers that operate in a forced draft mode. 

Consent Decree: 

On March 5, 2005, PNM entered into a consent decree with the Grand Canyon Trust, the Sierra Club, and 

the Department to settle alleged violations of the CAA. The consent decree required PNM to meet a PM 

average emission rate of 0.015 pounds per million British thermal units (lb/MMbtu) (measured using EPA 

Reference Method 5), and a 0.30 lb/MMbtu emission rate for NOx (daily rolling, thirty day average), for 

each of Units 1, 2, 3, and 4. As a result, PNM has installed new Low NOx burners (LNB) with overfire 

air (OFA) ports and a neural network (NN) system to reduce NOx emissions, and pulse jet fabric filters 

(PJFF) to reduce the PM emissions (See Table 1). 

Table.1: SJGS Characteristics 

SJGS Characteristics 

Unit SJGS 1 SJGS 2 SJGS 3 SJGS 4 

Fuel Type Sub-bituminous Sub-bituminous Sub-bituminous Sub-bituminous 

HHV of Fuel (btu/lb) 9692 9692 9692 9692 

Unit Rating, MW 

(gross) 360 350 544 544 

Boiler Heat Input 

(Mbtu/hr) 3707 3688 5758 5649 

Type of Boiler Wall-fired Wall-fired Opposed Wall-fired Opposed Wall-fired 

Steam Cycle Subcritical Subcritical Subcritical Subcritical 

Draft of Boiler Forced Forced Forced Forced 

Existing Emissions Controls

PM PJFF PJFF PJFF PJFF 

SO2 Wet FGD Wet FGD Wet FGD Wet FGD 

NOx LNB/OFA/NN LNB/OFA/NN LNB/OFA/NN LNB/OFA/NN 

BART Analysis Overview: 

Per 40 CFR 51.308 Regional haze program requirements, 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, the State must take into consideration each available technology, the associated costs of 

compliance of each, 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.1

 

The determination of BART for fossil-fuel power plants having a total generating capacity in excess of 

750 megawatts must be made pursuant to the Guidelines.1
San Juan Generating Station 

BART Determination 

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PNM’s BART Analysis for NOx and PM:

PNM submitted the BART analysis for the SJGS to the Department on June 6, 2007. The BART analysis 

was performed in two stages. First, a BART analysis was performed for the consent decree technologies 

being implemented at the SJGS. In the second stage of the BART analysis, additional control technology 

alternatives to the consent decree technologies were identified and evaluated. To determine the visibility 

improvements from both the consent decree technology upgrades and additional control technology, the 

Department determined it was appropriate to review both pre-consent decree to consent decree visibility 

improvement and improvement projected from consent decree plus additional control technologies. 

Per Appendix Y to 40 CFR Part 51 – Guidelines, PNM followed the 5 Step Process in the SJGS BART 

Analysis: 

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 

a) Costs of Compliance 

b) Energy Impacts 

c) Air quality environmental impacts 

d) Non-air environmental impacts 

e) Remaining useful life 

Step 5 – Evaluate Visibility Impacts 

In response to the Department’s requests, PNM has submitted multiple amendments to the original June 

2007 BART Analysis application. What follows is a summary of the original and additional submittals: 

June 6, 2007

The original BART analysis application included a five factor analysis of NOx technology. Modeling 

analyses were performed to provide SJGS plant-wide regional haze visibility impacts at 16 Class I areas. 

These analyses were based on a constant 1 ppb background ammonia concentration and no nitrate 

repartitioning. The NOx control technologies analyzed were the Selective Catalytic Reduction (SCR) and 

SNCR/SCR Hybrid.3

November 6, 2007 

Modeling analyses were performed to provide SJGS plant-wide regional haze visibility impacts at 16 

Class I areas. The analysis was based on refinements which included using the nitrate repartitioning 

methodology and monthly variable background ammonia concentrations. Again, the NOx control 

technologies analyzed were the SCR and SNCR/SCR Hybrid.3

March 29, 2008

PNM submitted an additional discussion of cost estimation methods used to determine costs of SCR 

installation and a discussion of Nalco Mobotec ROFA and Rotamix technology.3

 

March 31, 2008

Two modeling analyses were performed to provide SJGS plant-wide and unit specific regional haze 

visibility impacts at 16 Class I areas for the SCR NOx control technology only. One of the analyses, 

believed by PNM to be the more representative of ammonia chemistry of the area, was based on the 
San Juan Generating Station 

BART Determination 

Page 5 

November 6, 2007 refinements which included using nitrate repartitioning methodology and monthly 

variable background ammonia concentrations. The other analysis included nitrate repartitioning and a 

constant background ammonia concentration as requested by the Department.3

May 30, 2008

Two modeling analyses were performed to provide SJGS plant-wide and unit specific regional haze 

visibility impacts at 16 Class I areas for the SNCR NOx control technology only. Similar to the March 

31, 2008 analyses, one of the analyses was based on the November 6, 2007 refinements which included 

using nitrate repartitioning methodology and monthly variable background ammonia concentrations. The 

other analysis used nitrate repartitioning methodology and constant background ammonia concentration. 

It should be noted that PNM modeled all variants of SNCR together (including Fuel Tech and Nalco 

Mobotec) as one technology called SNCR. This is the same approach that is used for modeling SCR 

control technology, where all variants are modeled generically as SCR.3

At the request of the Department, PNM and B&V also provided a five-factor BART analysis for SNCR 

technology and a discussion of coal characteristics of the coal burned at the SJGS. 

August 29, 2008 

Three modeling analyses were performed to provide SJGS plant-wide and unit specific regional haze 

visibility impacts at 16 Class I areas for the ROFA with Rotamix, Rotamix, ROFA, and WESP PM 

control technologies (the NOx and PM analyses were submitted separately). Similar to the May 30, 2008 

analyses, these analyses were also based on the November 6, 2007 refinements which included using the 

nitrate repartitioning methodology and monthly variable background ammonia concentrations.3

At the request of the Department, PNM and B&V also provided a five-factor BART analysis of Nalco 

Mobotec control technology, including ROFA, Rotamix and ROFA/Rotamix and a five-factor BART 

analysis of additional PM control technology.3

March 16, 2009 

Four modeling analyses were performed to provide SJGS plant-wide and unit specific regional haze 

visibility impacts at 16 Class I areas. These include SCR technology, SCR/SNCR Hybrid technology; 

SCR technology with sorbent injection; and SCR/SNCR Hybrid technology with sorbent injection. As 

requested by the Department, for each of these cases, the modeling also took into consideration inherent 

SO3 removal of the SO3 formed from the catalyst oxidation of SO2 to SO3.3

Step 1 of the BART Analysis: Identification of All Available Retrofit Emissions Control 

Technologies

NOx Control Technologies

The main strategies for reducing NOx emissions take two forms: 1) modification to the combustion 

process to control fuel and air mixing and reduce flame temperatures, and 2) post-combustion treatment 

of the flue gas to remove NOx. PNM and B&V identified the following available NOx control 

technologies and a discussion of each of the technologies: 

1) Low NOx Burners, Overfire Air, and Neural Network 

Low NOx burners slow and control the rate of fuel and air mixing, thereby reducing the oxygen 

availability in the ignition and main combustion zones. Overfire Air uses low excess air levels in 
San Juan Generating Station 

BART Determination 

Page 6 

the primary combustion zone with the remaining (overfire) air added higher in the furnace to 

complete combustion. Neural Network provides improvements in the heat rate and reduce 

combustion-related emissions by fine-tuning the combustion process.3

 

2) Selective Non Catalytic Reduction (SNCR) 

SNCR is based on the chemical reduction of the NO molecule into molecular nitrogen and water 

vapor. A nitrogen based reducing agent (reagent), such as ammonia or urea, is injected into the 

post combustion flue gas. The reduction with NO is favored over other chemical reaction 

processes at temperatures ranging between 1600F and 2100F (870C to 1150C), therefore, it is 

considered a selective chemical process.4

3) Selective Catalytic Reduction (SCR) 

The SCR process chemically reduces the NO molecule into molecular nitrogen and water vapor 

in the presence of a reducing catalyst. A nitrogen based reducing reagent such as ammonia or 

urea is injected into the ductwork, downstream of the combustion unit. The waste gas mixes with 

the reagent and enters a reactor module containing catalyst. The hot flue gas and reagent diffuse 

through the catalyst. The reagent reacts selectively with the NO within a specific temperature 

range and in the presence of the catalyst and excess oxygen.5

 

SCR plus Sorbent Injection 

Sorbent injection removes SO3 in the flue gas by reaction of the SO3 with an alkaline sorbent 

material to form a particulate that is subsequently removed in a particulate control device. The 

alkaline material injected can be a magnesium, sodium, or calcium-based sorbent. The injection 

points for the reagents may vary. For this analysis, hydrated lime was selected.4 

4) SNCR/SCR Hybrid 

The SNCR/SCR hybrid systems use components and operating characteristics of both SNCR and 

SCR systems. Hybrid systems were developed to combine the low capital cost and high ammonia 

slip associated with SNCR systems with the high reduction potential and low ammonia slip 

inherent in the catalyst of SCR systems.3

SNCR/SCR Hybrid plus Sorbent Injection 

Sorbent injection removes SO3 in the flue gas by reaction of the SO3 with an alkaline sorbent 

material to form a particulate that is subsequently removed in a particulate control device. The 

alkaline material injected can be a magnesium, sodium, or calcium-based sorbent. The injection 

points for the reagents may vary. For this analysis, hydrated lime was selected.4 

5) Gas Reburn 

The gas reburn process combusts auxiliary natural gas, along with coal, in the boiler. Three 

separate combustion zones in the boiler are manipulated to reduce NOx emissions.4

 
San Juan Generating Station 

BART Determination 

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6) Nalco Mobotec ROFA and Rotamix 

ROFA and Rotamix are proprietary control technologies developed by Nalco Mobotec. ROFA, 

or Rotating Opposed Firing Air, is a modified overfire air technology that utilizes rotation of flue 

gases and turbulent mixing to reduce NOx emissions. Rotamix is a version of SNCR technology 

and operates under the same principles as other SNCR technology.3

 

7) NOxStar 

NOxStar is the trademarked name for a NOx control technology that involves the injection of 

ammonia and a hydrocarbon (typically natural gas) into the flue gas path of a coal-fired boiler at 

around 1600F to 1800F for the reduction of NOx.3

 

8) ECOTUBE 

The ECOTUBE system utilizes retractable lance tubes that penetrate the boiler above the primary 

combustion burner zone and inject high-velocity air as well as reagents. The lance tubes work to 

create turbulent airflow and to increase the residence time for the air/fuel mixture. In principle, 

the OFA and SNCR processes are combined in this technology.3

 

9) PowerSpan ECO 

The PowerSpan ECO system is a multi-pollutant technology with limited experience. The 

PowerSpan 5ECO system is located downstream of an existing particulate control device and 

treats the power plant’s flue gas in three process steps to achieve multi-pollutant removal of 

sulfur dioxide (SO2), nitrogen oxides (NOX), oxidized mercury, and fine particulate matter.3

 

10) Phenix Clean Combustion 

Phenix Clean Combustion System is an advanced hybrid coal gasification/combustion process 

that prevents the formation of NOx and SO2 emissions when burning coal.3

 

11) e-SCRUB 

The e-SCRUB process is similar to the PowerSpan technology in that it uses an energy source to 

oxidize pollutants in the flue gas. However, there are some variations in the oxidation energy 

source and the byproduct recovery systems. 

PM Control Technologies

 

Particulate matter emissions can only be controlled by post-combustion control technologies. PNM 

identified the following technologies as available in their BART analysis for PM. 

1) Flue Gas Conditioning with Hot-Side ESP 

Flue gas conditioning improves the collection efficiency of particulate matter in the ESP. Flue 

gas leaving the air heater into the ESP can be conditioned by addition of ionic compounds, such 

as SO3 or ammonia. These compounds combine with the moisture in the flue gas and are 
San Juan Generating Station 

BART Determination 

Page 8 

deposited on the surface of the fly ash particles. This will increase the conductivity of the fly ash 

and make it more suitable for capture.3

2) Pulse Jet Fabric Filter (PJFF) 

In PJFFs, the flue gas typically enters the compartment hopper and passes from the outside of the 

bag to the inside of the bag, depositing particulate on the outside of the bag. To prevent collapse 

of the bag, a metal cage is installed on the inside of the bag. The flue gas passes up through the 

center of the bag into the output plenum. Cleaning is performed by initiating a downward pulse 

of air into the top of the bag. The pulse causes a ripple effect along the length of the bag. This 

releases the dust cake from the bag’s exterior surface, allowing the dust to fall into the hopper.3

3) Compact Hybrid Particulate Collector 

A variant of the PJFF is the compact hybrid particulate collector. This is a high air to cloth (A/C) 

ratio fabric filter installed downstream of existing particulate collection devices where the 

majority of PM has been removed.3

 

4) Max-9 Electrostatic Fabric Filter 

The Max-9 filter is essentially a high-efficiency PJFF utilizing a discharge electrode as in an ESP. 

However, there are no collector plates. When the dust particles are charged, they are attracted to 

the grounded metal cage inside the filter element, just as they would be attracted to the collecting 

plates in an ordinary precipitator.3

 

Step 2 of the BART Analysis: Eliminate Technically Infeasible Control Technologies

NOx Control Technologies

PNM excluded several of the identified NOx controls due to technical infeasibility. In the BART analysis 

application, PNM excluded the following NOx control technologies: 

1) Selective Non Catalytic Reduction 

PNM determined in its submittal of June 6, 2007 that SNCR technology was technically 

infeasible because the technology was unable to meet the presumptive limits for NOx; determined 

by EPA to be 0.23 lb NOx/MMbtu for dry bottom wall-fired boilers burning sub-bituminous coal. 

 A vendor estimated that the technology could only achieve 0.24 lb NOx/MMbtu. In order for the 

technology to achieve the presumptive limit, PNM stated that ammonia slip limit would need to 

be raised from 5 ppm to 10 ppm, and that this higher ammonia slip posed additional operational 

problems. 

The Department did not agree with PNM’s argument that because SNCR could not meet the 

presumptive limits the technology should be eliminated as technically infeasible. Therefore the 

Department requested PNM to perform the complete 5-factor BART analysis required by the 

Guidelines on SNCR. PNM submitted the five-factor analysis of SNCR in a subsequent 

submittal dated May 30, 2008. 
San Juan Generating Station 

BART Determination 

Page 9 

2) Natural Gas Reburn 

PNM determined that the current boiler space inhibits sufficient residence time for the natural gas 

reburn zone. The Department accepts PNM’s elimination of this technology due to space 

limitations. 

3) NalcoMobotec ROFA and Rotamix 

PNM determined the Rotamix technology was technically infeasible due to limited application at 

coal-fired boilers equivalent to the size of Units 1-4 at SJGS. PNM determined ROFA 

technology was technically infeasible because ROFA is a variant of OFA, which at the time was 

being installed at Units 1-4 at SJGS. 

The Department did not agree with PNM’s position that Rotamix has limited application at coalfired boilers equivalent the size of Units 1-4 at SJGS. The Department did not agree that because 

ROFA is a variant of OFA, the technology can be eliminated as technically infeasible. Therefore 

 the Department requested PNM perform the complete 5-factor analysis for ROFA and Rotamix. 

PNM performed the analysis and submitted the analysis in two subsequent submittals dated 

March 29, 2008 and August 29, 2008. 

4) NOxStar 

NOxStar currently has only one major installation in the US. In addition, PNM stated that in 

recent discussions the supplier has identified limited ability and willingness to market the 

commercial technology. The Department agrees that this technology has limited application to 

large coal-fired boilers and is not technically feasible. 

5) ECOTUBE 

The ECOTUBE technology has been demonstrated on industrial/small boilers firing sold waste, 

wood, and biomass.3

 ECOTUBE has limited application to boilers similar to Units 1-4 at the 

SJGS. The Department agrees that this technology has limited application to large coal-fired 

boilers and is not technically feasible. 

6) PowerSpan 

PowerSpan has not been demonstrated on large boilers, such as Units 1-4 at SJGS. The 

Department agrees that this technology has limited application to large coal-fired boilers and is 

not technically feasible. 

7) Phenix Clean Combustion 

PNM determined that the Phenix Clean Combustion system is still in the demonstration and 

testing stage, and there are no commercial retrofits at facilities similar to SJGS. The Department 

agrees that this technology has no demonstrated application to the source type and is not 

technically feasible. 
San Juan Generating Station 

BART Determination 

Page 10 

8) e-SCRUB 

PNM determined that the e-SCRUB technology has only one known medium scale installation 

with limited data. The Department agrees that the technology should be considered technically 

infeasible due to limited demonstrated applications. 

PM Control Technologies

PNM excluded the following PM control technologies as technically infeasible: 

1) Flue Gas Conditioning with Hot-Side ESP 

 

Flue gas conditioning does improve collection efficiencies, but will not achieve an emission limit 

lower than the current PM limit in their air quality permit. The Department agrees that flue gas 

conditioning control technology should not be considered in the BART analysis. Because the 

vendor was unable to guarantee a lower emission rate, the technology does not need to undergo 

the three additional factors of the five factor analysis. 

2) Compact Hybrid Particulate Collector 

The compact hybrid particulate collector does not provide a performance guarantee lower than 

the current permitted limit for PM. The Department agrees that the compact hybrid PM control 

technology should not be considered in the BART analysis. Because the vendor was unable to 

guarantee a lower emission rate, the technology does not need to undergo the three additional 

factors of the five factor analysis. 

3) Max-9 Electrostatic Fabric Filter 

The Max-9 electrostatic fabric filter has been installed in a small-sized utility boiler, but there are 

no commercial installations of a similar size to Units 1-4 at SJGS. The Department agrees that 

the limited application of this technology to large utility boilers justifies removing the technology 

as technically infeasible. 

During the Department review of available PM control technologies, the Department requested PNM to 

perform a complete five-factor BART analysis on Wet Electrostatic Precipitator (WESP). The 

Department believes this technology should have been identified as technically feasible in Step 1 of the 

PM BART analysis. PNM performed a complete five-factor BART analysis on WESP and PJFF and 

submitted report in a subsequent submittal dated August 28, 2008. 

Step 3 of the BART Analysis: Evaluate Control Effectiveness of Remaining Control Technologies

PNM contracted with B&V to determine the control effectiveness of each remaining available NOx and 

PM control technology for Units 1-4. The control efficiencies of each of the NOx control technologies 

are summarized in Tables 2 – 5, and the control efficiencies of the PM control technologies are 

summarized in Tables 6 – 9. 
San Juan Generating Station 

BART Determination 

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Table 2: NOx Control Effectiveness for Unit 1 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.43 5394 

CD 23 5394 1254 0.30 4140 

ROFA 13 4140 552 0.26 3588 

Rotamix (SNCR) 23 4140 966 0.23 3174 

ROFA/Rotamix 33 4140 1380 0.20 2760 

SCR/SNCR Hybrid 40 4140 1656 0.18 2484 

SCR + Sorbent 77 4140 3174 0.07 966 

Table 3: NOx Control Effectiveness for Unit 2 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.45 6179 

CD 33 6179 2060 0.30 4119 

ROFA 13 4119 549 0.26 3570 

Rotamix (SNCR) 23 4119 961 0.23 3158 

ROFA/Rotamix 34 4119 1373 0.20 2746 

SCR/SNCR Hybrid 40 4119 1648 0.18 2471 

SCR + Sorbent 77 4119 3158 0.07 961 

Table 4: NOx Control Effectiveness for Unit 3 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.42 9004 

CD 29 9004 2573 0.30 6431 

ROFA 13 6431 857 0.26 5574 

Rotamix (SNCR) 23 6431 1500 0.23 4931 

ROFA/Rotamix 33 6431 2144 0.20 4287 

SCR/SNCR Hybrid 40 6431 2572 0.18 3859 

SCR + Sorbent 77 6431 4930 0.07 1501 

Table 5: NOx Control Effectiveness for Unit 4 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.42 8833 

CD 29 8833 2524 0.30 6309 

ROFA 15 6431 963 0.26 5468 

Rotamix (SNCR) 25 6431 1594 0.23 4837 

ROFA/Rotamix 35 6431 2225 0.20 4206 

SCR/SNCR Hybrid 41 6431 2645 0.18 3786 

SCR + Sorbent 77 6431 4959 0.07 1472 

Table 6: PM Control Effectiveness for Unit 1 
San Juan Generating Station 

BART Determination 

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Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.050 690 

PJFF (CD) 70 690 483 0.015 207 

WESP 33 207 69 0.010 138 

Table 7: PM Control Effectiveness for Unit 2 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.050 687 

PJFF (CD) 70 687 481 0.015 206 

WESP 33 206 69 0.010 137 

Table 8: PM Control Effectiveness for Unit 3 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.050 1072 

PJFF (CD) 70 1072 750 0.015 322 

WESP 33 322 108 0.010 214 

Table 9: PM Control Effectiveness for Unit 4 

Control Technology Control 

Efficiency 

(%) 

Baseline 

Emissions 

(tpy) 

Emissions 

Reduction 

(tpy) 

Controlled 

Emission Rate 

(lb/MMbtu) 

Controlled 

Emission Rate 

(tpy) 

Pre-Consent Decree 

(Pre-CD) 

NA NA NA 0.050 1052 

PJFF (CD) 70 1052 737 0.015 315 

WESP 33 315 105 0.010 210 

Step 4 of the BART Analysis: Perform Impacts Analysis of Remaining Control Technologies

The Guidelines require states to consider four types of impact analysis in Step 4 of the BART analysis. 

These four types of impacts consider the costs of compliance, energy impacts, non-air quality 

environmental impacts, and remaining useful life of the facility. These impacts are included in the costeffectiveness of each additional control technology and allow comparisons to be made between the 

remaining controls. B&V performed an impact analysis for the remaining NOx and PM control 

technologies in accordance with the Guidelines. 

B&V prepared the design parameters and developed estimates of capital and annual costs for applications 

of SCR, SCR/SNCR Hybrid, ROFA, Rotamix, ROFA/Rotamix, PJFF, and WESP technologies. B&V 

relied on a number of sources to prepare the design parameters, including information from the Nalco 

Mobotec equipment vendors, EPA cost manuals, engineering and performance data, and B&V’s own inhouse engineering estimates. 
San Juan Generating Station 

BART Determination 

Page 13 

PNM evaluated the energy impacts, non-air quality environmental impacts, and remaining useful life of 

all additional technically feasible control options for NOx and PM. Energy impacts from control 

equipment that consume auxiliary power during operation were considered for all control options. For 

SCR and SCR/SNCR Hybrid technology, the non-air quality environmental impacts included the 

consideration of water usage and waste generated from each control technology. For WESP technology, 

PNM considered the auxiliary power consumption to operate the WESP and fans, and the additional 

water consumption and waste water disposal requirements from operating the WESP. Lastly, the 

remaining useful life was defined as 20 years. Therefore, no additional cost adjustments for a short 

remaining useful boiler life need to be considered. The results of the impact analyses for additional NOx 

and PM control technologies are summarized in Tables 10 and 11 on the following pages. 

Following the initial submittal, the Department made additional requests for information on the impact 

analysis for SCR, SNCR, ROFA, Rotamix and WESP, and for further consideration of inherent and 

additional control of SO3 from both the SCR and SCR/SNCR Hybrid technology. 

SCR Costs

The Department reviewed the original cost analysis for SCR technology and subsequently requested PNM 

to provide additional information on the basis of their cost analysis of SCR technology. In response to 

the request, B&V provided additional clarification for the cost analysis for SCR technology and submitted 

it to the Department on March 29, 2008. The submittal discussed how the OAQPS cost control manual is 

an insufficient method for determining actual costs of retrofitting the SJGS with SCR and provided a 

comparison between cost estimation based on the OAQPS manual and the B&V provided estimate. 

Consideration of SO3 Control

PNM’s initial analysis of SCR and SCR/SNCR technology took into consideration additional oxidation of 

SO2 to SO3 across the SCR catalyst bed. The Department requested PNM to consider inherent removal 

of SO3 emissions from existing air pollution control equipment, and removal of SO3 emissions through 

installation of sorbent injection. PNM responded with an amended submittal addressing both inherent 

and add-on removal of SO3. PNM’s submittal provided cost estimates of the sorbent injection system 

and updated visibility modeling for both SCR and SCR/SNCR Hybrid technologies. 

The Department understands that there are SCR catalysts now on the market that are capable of a much 

smaller SO2 to SO3 conversion (around 0.5%) as opposed to the assumed 1%. The Department believes 

use of such a catalyst will minimize SO3 oxidation to less than what was represented in PNM’s analysis. 

 

SNCR, WESP, ROFA, and Rotamix Review

PNM provided additional impact analyses of SNCR, WESP, ROFA, and Rotamix technologies and 

submitted those updates to the Department. 
San Juan Generating Station 

BART Determination 

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Table 10: Impact Analysis and Cost Effectiveness of Additional NOx Control Technologies 

Control 

Technology 

Emission 

Performance 

Level 

(lb/MMbtu) 

Expected 

Emission 

Rate (tpy) 

Expected 

Emission 

Reduction 

(tpy) 

Total Capital 

Investment 

(TCI) 

(1,000$) 

Total 

Annualized 

Cost 

(TAC) 

(1,000$) 

Cost 

Effectivenes

s ($/ton) 

Incremental 

Cost 

Effectivenes

s 

($/ton) 

Energy 

Impacts 

(1,000$) 

Non-Air 

Impacts 

(1,000$) 

Unit 1 

SCR + sorbent 0.07 966 3,174 164,732 21,998 6,931 3,815 1,596 NA1 

SNCR/SCR 

Hybrid 0.18 2,484 1,656 104,436 16,207 9,786 34,218 706 1,762 

ROFA/Rotamix 0.20 2,760 1,380 29,350 6,762 4,900 7,765 1,413 3 

Rotamix 

(SNCR) 0.23 3,174 966 11,306 3,547 3,672 222 51 4 

ROFA 0.26 3,588 552 18,293 3,455 6,259 -- 1,363 NA1

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

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

Unit 2 

SCR + sorbent 0.07 961 3,158 177,178 23,364 7,398 4,431 1,565 NA1

SNCR/SCR 

Hybrid 0.18 2,471 1,648 108,628 16,670 10,117 36,029 346 1,762 

ROFA/Rotamix 0.20 2,746 1,373 29,350 6,762 4,925 7,803 1,413 3 

Rotamix 

(SNCR) 0.23 3,158 961 11,306 3,547 3,690 223 51 4 

ROFA 0.26 3,570 549 18,293 3,455 6,291 -- 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 0.07 1,501 4,931 227,774 30,527 6,191 2,086 2,267 NA1

SNCR/SCR 

Hybrid 0.18 3,859 2,572 168,507 25,606 9,954 37,285 507 2,658 

ROFA/Rotamix 0.20 4,287 2,144 34,070 9,648 4,501 7,339 2,810 5 

Rotamix 

(SNCR) 0.23 4,931 1,501 13,316 4,929 3,285 -- 84 5 

ROFA 0.26 5,574 857 20,983 5,124 5,976 -- 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 0.07 1,472 4,837 211,764 28,760 5,946 1,691 2,288 NA1

SNCR/SCR 

Hybrid 0.18 3,786 2,524 161,572 24,849 9,846 36,107 507 2,658 

ROFA/Rotamix 0.20 4,206 2,103 34,070 9,648 4,587 7,479 2,810 5 

Rotamix 

(SNCR) 0.23 4,837 1,472 13,316 4,929 3,348 -- 84 5 

ROFA 0.26 5,468 841 20,983 5,124 6,091 -- 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.
San Juan Generating Station 

BART Determination 

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Table 11: Impact Analysis and Cost Effectiveness of Additional PM Control Technologies 

1 PNM performed an impact analysis for these technologies and incorporated any monetized energy or non-air environmental impacts into 

the cost analysis.

Control 

Technolog

y 

Emission 

Performance 

Level 

(lb/MMbtu) 

Expected 

Emission 

Rate (tpy) 

Expected 

Emission 

Reduction 

(tpy) 

Total Capital 

Investment 

(TCI) 

(1,000$) 

Total 

Annualized 

Cost (TAC) 

(1,000$) 

Incremental 

Cost 

Effectiveness 

($/ton) 

Cost 

Effectiveness 

($/ton) 

Energy 

Impacts 

(1,000$) 

Non-Air 

Impacts 

(1,000$) 

Unit 1

WESP 0.010 138 69 99,308 11,855 20,696 171,812 1,112 NA1

PJFF (CD) 0.015 207 483 67,072 10,427 NA 21,588 4,488 NA1

Pre-CD 0.050 690 NA NA NA NA NA NA NA 

Unit 2

WESP 0.010 137 70 99,663 11,895 16,157 169,929 1,112 NA1

PJFF (CD) 0.015 207 480 69,840 10,764 NA 22,425 4,488 NA1

Pre-CD 0.050 687 NA NA NA NA NA NA NA 

Unit 3

WESP 0.010 214 108 129,565 15,558 28,741 144,056 1,728 NA1

PJFF (CD) 0.015 322 750 72,696 12,454 NA 16,605 6,895 NA1

Pre-CD 0.050 1072 NA NA NA NA NA NA NA 

Unit 4

WESP 0.010 210 105 130,012 15,609 29,352 148,657 1,728 NA1

PJFF (CD) 0.015 315 737 73,328 12,527 NA 16,997 6,895 NA1

Pre-CD 0.050 1052 NA NA NA NA NA NA NA 
San Juan Generating Station 

BART Determination 

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Step 5 of the BART Analysis: Visibility Impacts Analysis of Remaining Control Technologies

The Guidelines require states to assess visibility improvement based on the modeled change in visibility 

impacts for the pre-control and post-control emission scenarios. 

The objective of this source-specific, refined modeling analysis report is to describe the methodologies 

and procedures of visibility modeling to support the BART engineering analysis for PNM’s SJGS Units 

1, 2, 3, and 4. These units were identified as subject-to-BART by the Department based on BART 

screening exemption modeling conducted by the Western Regional Air Partnership’s (WRAP) Regional 

Modeling Center (RMC). Because of the results of the WRAP screening modeling, PNM SJGS was 

required to conduct a refined BART analysis that included CALPUFF visibility modeling for the facility. 

 

The modeling approach followed the requirements described in the WRAP’s BART modeling protocol, 

CALMET/CALPUFF Protocol for BART Exemption Screening Analysis for Class I Areas in the Western 

United States dated August 15, 2006. The refined modeling methodology is described in detail below. 

CALPUFF System

The CALPUFF modeling system consists of a meteorological data pre-processor (CALMET), an air 

dispersion model (CALPUFF), and post-processor programs (POSTUTIL, CALSUM, CALPOST). The 

CALPUFF model was developed as a non-steady-state air quality modeling system for assessing the 

effects of time-varying and space-varying meteorological conditions on pollutant transport, 

transformation, and removal. 

CALMET is a diagnostic wind model that develops hourly wind and temperature fields in a threedimensional, gridded modeling domain. Meteorological inputs to CALMET can include surface and 

upper-air observations from multiple meteorological monitoring stations. Additionally, the CALMET 

model can utilize gridded analysis fields from various mesoscale models such as MM5 to better represent 

regional wind flows and complex terrain circulations. Associated two-dimensional fields such as mixing 

height, land use, and surface roughness are included in the input to CALMET. The CALMET model 

allows the user to “weight” various terrain influence parameters in the vertical and horizontal directions 

by defining the radius of influence for surface and upper-air stations. 

CALPUFF is a multi-layer, Lagrangian puff dispersion model. CALPUFF can be driven by the threedimensional wind fields developed by the CALMET model (refined mode), or by data from a single 

surface and upper-air station in a format consistent with the meteorological files used to drive steady-state 

dispersion models. All far-field modeling assessments described here were completed using the 

CALPUFF model in the refined mode. 

CALSUM is a post-processing program that can operate on multiple CALPUFF output files to combine 

the results for further post-processing. POSTUTIL is a post-processing program that processes CALPUFF 

concentrations and wet/dry flux files. The POSTUTIL model operates on one or more output data files 

from CALPUFF to sum, scale, and/or computer species derived from those that are modeled, and outputs 

selected species to a file for further post-processing. CALPOST is a post-processing program that can 

read the CALPUFF (or POSTUTIL or CALSUM) output files and calculate the impacts to visibility. 
San Juan Generating Station 

BART Determination 

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All of the refined CALPUFF modeling was conducted with the version of the CALPUFF system 

recommended by the WRAP BART modeling protocol. Version designations of the key programs are 

listed in Table 12. 

Table 12: CALPUFF System Used 

WRAP Protocol PNM Analyses 

Program Version Level Version Level 

CALMET 6.211 060414 6.211 060414 

CALPUFF 6.112 060412 6.112 060412 

POSTUTIL N/A N/A 1.52 060412 

CALSUM N/A N/A 1.33 051122 

CALPOST 6.131 060410 6.131 060410 

Meteorological Data Processing (CALMET)

As required by the WRAP modeling protocol, the CALMET model was used to construct an initial threedimensional windfield using data from the MM5 model. Surface and upper-air data were input to 

CALMET to adjust the initial windfields. Because the MM5 data were afforded to simulate atmospheric 

variables on the CALMET windfields, the daily MM5 meteorological data files provided by the WRAP 

RMC for the years 2001, 2002, and 2003 were utilized as input into CALMET. These variables were 

processed into the appropriate format and introduced into the CALMET model through the utilization 

of additional meteorological data files. Locations of the observations that were input to CALMET, 

including surface and precipitation stations, are shown in Figures 1 and 2. Default settings were used in 

the CALMET input files for most of the technical options. Table 13 lists the key user-defined CALMET 

settings that were selected. 
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Figure 1: Surface Stations 
San Juan Generating Station 

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Figure 2: Precipitation Stations 
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Table 13: Key User-Defined CALMET Settings 

Variable Description Value 

PMAP Map projection LCC 

DGRIDKM Grid spacing (km) 4 

NZ Number of layers 10 

ZFACE Cell face heights (m) 0, 20, 100, 200, 350, 500, 750, 

1000, 2000, 3000, 4000, 5000 

NOOBS 1=Use of surface and precipitation (no upper air 

observations); use MM5 for upper air data 

1 

IEXTRP Extrapolate surface wind obs to upper level 1 

RMIN2 Minimum distance for extrapolation 4 

IPROG Use gridded prognostic model output 14 

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

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

TERRAD Radius of influence for terrain (km) 10 

R1 Relative weighting of first guess wind field and 

observation (km) 

100 

R2 Relative weighting aloft (km) 200 

ITPROG 3D temperature from observations or from MM5 1 

CALPUFF Modeling Setup

To allow chemical transformations within CALPUFF using the recommended chemistry mechanism 

(MESOPUFF II), the model required input of background ozone and ammonia concentrations. 

Background ozone concentrations are important for the photochemical conversion of SO2 and NOx to 

SO4 and NO3, respectively. For ozone, the hourly ozone concentration files that were used by the 

WRAP RMC in the initial modeling were used for the BART technology evaluation. In addition to 

the hourly ozone data, the same monthly average background ozone value of 80 ppb that was used in the 

initial modeling was used in this modeling for times when hourly ozone data were not available. For 

ammonia, the monthly variable background ammonia concentrations were used for the BART modeling 

analysis. They are as follows: 

Table 14: Ammonia Background Concentration (ppb) 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

0.2 0.2 0.5 0.5 1.0 1.0 1.0 1.0 1.0 0.5 0.5 0.2 

There are many Class I areas within and surrounding New Mexico. On the basis of distance from BART 

applicable sources, topography, and meteorology, the screening modeling conducted by WRAP RMC 

determined that 16 Class I areas needed to be addressed in the BART analysis. The applicable Class I 

areas included in the BART analysis are located within 300 km of the SJGS facility. As shown in Figure 

3, the nearest Class I area is Mesa Verde National Park, located approximately 40 km north of the facility 

and the most distant Class I area is Grand Canyon National Park, located approximately 300 km of west 

of the facility. All Class I area distances from the facility fall within the range recommended for 

CALPUFF application. The 16 Class I areas are identified in Table 15 and an illustration of the receptors 

used in the modeling analysis for each Class I area is provided in Attachment B. The CALPUFF 
San Juan Generating Station 

BART Determination 

Page 21 

analyses used an array of discrete receptors with receptor elevations for the Class I areas, which were 

created and distributed by the National Park Service (NPS).

Figure 3: Location of SJGS and the Class I Area 

Table 15: Class I Areas 

1. Mesa Verde National Park (MEVE) 9. West Elk Wilderness (WEEL) 

2. Weminuche Wilderness (WEMI) 10. Arches National Park (ARCH) 

3. San Pedro Parks Wilderness (SAPE) 11. Capitol Reef National Park (CARE) 

4. La Garita Wilderness (LAGA) 12. Pecos Wilderness (PECO) 

5. Canyonlands National Park (CANY) 13. Wheeler Peak Wilderness (WHPE) 

6. Black Canyon of the Gunnison National Park (BLCA) 14. Great Sand Dunes National Park (GRSA) 

7. Bandelier National Monument (BAND) 15. Maroon Bells-Snowmass Wilderness 

(MABE) 

8. Petrified Forest National Park (PEFO) 16. Grand Canyon National Park (GRCA) 
San Juan Generating Station 

BART Determination 

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CALPUFF Inputs – Pre-Consent Decree, Baseline and Control Options

Source release parameters and emissions for pre-consent decree, baseline and control options for each unit 

are shown in Tables 16 through 19. 

Table 16: CALPUFF Inputs for Unit 1 

Model Input Data 

PreConsent 

Decree 

Consent 

Decree Rotamix ROFA/ Rotamix ROFA SCR/SNCR Hybrid 

SCR with 

Sorbent 

Hourly Heat Input 

(MMbtu/hour) 3707 3707 3707 3707 3707 3707 3707 

Sulfur Dioxide (SO2) 

(lb/MMbtu) 0.24 0.18 0.18 0.18 0.18 0.18 0.18 

Sulfur Dioxide (SO2) (lb/hr) 877.8 667.3 667.3 667.3 667.3 667.3 667.3 

Nitrogen Oxide (NOx) 

(lb/MMbtu) 0.43 0.33 0.23 0.20 0.26 0.18 0.07 

Nitrogen Oxide (NOx) 

(lb/hr) 1592.0 1223.3 852.6 741.4 963.8 667.3 259.5 

PM (lb/MMbtu) 0.050 0.015 0.015 0.015 0.015 0.015 0.015 

PM (lb/hr) 185.4 55.6 55.6 55.6 55.6 55.6 55.6 

SO3 as Sulfuric Acid 

(H2SO4) (lb/MMbtu) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 

SO3 as Sulfuric Acid 

(H2SO4)

(a) (lb/hr) 50.0 40.5 40.5 40.5 40.5 114.2 16.1 

Stack Conditions 

Stack Height (meters) 121.92 121.92 121.92 121.92 121.92 121.92 121.92 

Stack Exit Diameter 

(meters) 6.096 6.096 6.096 6.096 6.096 6.096 6.096 

Stack Exit Temperature 

(Kelvin) 336 322.83 322.83 322.83 322.83 322.83 322.83 

Stack Exit Velocity (m/s) 22.6 21.34 21.34 21.34 21.34 21.34 21.34 

(a)H2SO4 assumed to be 100 percent of the SO4 emissions calculated by the NPS Speciation 

Spreadsheet. 
San Juan Generating Station 

BART Determination 

Page 23 

Table 17: CALPUFF Inputs for Unit 2 

Model Input Data 

PreConsent 

Decree 

Consent 

Decree Rotamix ROFA/ Rotamix ROFA SCR/SNCR Hybrid 

SCR with 

Sorbent 

Hourly Heat Input 

(MMbtu/hour) 3688 3688 3688 3688 3688 3688 3688 

Sulfur Dioxide (SO2) 

(lb/MMbtu) 0.23 0.18 0.18 0.18 0.18 0.18 0.18 

Sulfur Dioxide (SO2) (lb/hr) 844.0 663.8 663.8 663.8 663.8 663.8 663.8 

Nitrogen Oxide (NOx) 

(lb/MMbtu) 0.45 0.33 0.23 0.20 0.26 0.18 0.07 

Nitrogen Oxide (NOx) 

(lb/hr) 1649.3 1217.0 848.2 737.6 958.9 663.8 258.2 

PM (lb/MMbtu) 0.050 0.015 0.015 0.015 0.015 0.015 0.015 

PM (lb/hr) 184.4 55.3 55.3 55.3 55.3 55.3 55.3 

SO3 as Sulfuric Acid 

(H2SO4) (lb/MMbtu) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 

SO3 as Sulfuric Acid 

(H2SO4)

(a) (lb/hr) 49.7 40.3 40.3 40.3 40.3 113.6 16.0 

Stack Conditions 

Stack Height (meters) 121.92 121.92 121.92 121.92 121.92 121.92 121.92 

Stack Exit Diameter 

(meters) 6.096 6.096 6.096 6.096 6.096 6.096 6.096 

Stack Exit Temperature 

(Kelvin) 338 322.83 322.83 322.83 322.83 322.83 322.83 

Stack Exit Velocity (m/s) 23.5 21.34 21.34 21.34 21.34 21.34 21.34 

(a)H2SO4 assumed to be 100 percent of the SO4 emissions calculated by the NPS Speciation 

Spreadsheet. 
San Juan Generating Station 

BART Determination 

Page 24 

Table 18: CALPUFF Inputs for Unit 3 

Model Input Data 

PreConsent 

Decree 

Consent 

Decree Rotamix ROFA/ Rotamix ROFA SCR/SNCR Hybrid 

SCR with 

Sorbent 

Hourly Heat Input 

(MMbtu/hour) 5758 5758 5758 5758 5758 5758 5758

Sulfur Dioxide (SO2) 

(lb/MMbtu) 0.28 0.18 0.18 0.18 0.18 0.18 0.18 

Sulfur Dioxide (SO2) (lb/hr) 1591.1 1036.4 1036.4 1036.4 1036.4 1036.4 1036.4 

Nitrogen Oxide (NOx) 

(lb/MMbtu) 0.42 0.33 0.23 0.20 0.26 0.18 0.07 

Nitrogen Oxide (NOx) 

(lb/hr) 2405.5 1900.1 1324.3 1151.6 1497.1 1036.4 403.1 

PM (lb/MMbtu) 0.050 0.015 0.015 0.015 0.015 0.015 0.015 

PM (lb/hr) 287.9 86.4 86.4 86.4 86.4 86.4 86.4 

SO3 as Sulfuric Acid 

(H2SO4) (lb/MMbtu) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 

SO3 as Sulfuric Acid 

(H2SO4)

(a) (lb/hr) 77.7 62.9 62.9 62.9 62.9 177.3 25 

Stack Conditions 

Stack Height (meters) 121.92 121.92 121.92 121.92 121.92 121.92 121.92 

Stack Exit Diameter 

(meters) 8.534 8.534 8.534 8.534 8.534 8.534 8.534 

Stack Exit Temperature 

(Kelvin) 335 322.83 322.83 322.83 322.83 322.83 322.83 

Stack Exit Velocity (m/s) 17.07 17.07 17.07 17.07 17.07 17.07 17.07 

(a)H2SO4 assumed to be 100 percent of the SO4 emissions calculated by the NPS Speciation 

Spreadsheet. 
San Juan Generating Station 

BART Determination 

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Table 19: CALPUFF Inputs for Unit 4 

Model Input Data 

PreConsent 

Decree 

Consent 

Decree Rotamix ROFA/ Rotamix ROFA SCR/SNCR Hybrid 

SCR with 

Sorbent 

Hourly Heat Input 

(MMbtu/hour) 5649 5649 5649 5649 5649 5649 5649 

Sulfur Dioxide (SO2) 

(lb/MMbtu) 0.29 0.18 0.18 0.18 0.18 0.18 0.18 

Sulfur Dioxide (SO2) (lb/hr) 1662.4 1016.8 1016.8 1016.8 1016.8 1016.8 1016.8 

Nitrogen Oxide (NOx) 

(lb/MMbtu) 0.42 0.33 0.23 0.20 0.26 0.18 0.07 

Nitrogen Oxide (NOx) 

(lb/hr) 2399.6 1864.2 1299.3 1129.8 1468.7 1016.8 395.4 

PM (lb/MMbtu) 0.050 0.015 0.015 0.015 0.015 0.015 0.015 

PM (lb/hr) 282.5 84.7 84.7 84.7 84.7 84.7 84.7 

SO3 as Sulfuric Acid 

(H2SO4) (lb/MMbtu) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 

SO3 as Sulfuric Acid 

(H2SO4)

(a) (lb/hr) 76.2 61.7 61.7 61.7 61.7 174.0 24.5 

Stack Conditions 

Stack Height (meters) 121.92 121.92 121.92 121.92 121.92 121.92 121.92 

Stack Exit Diameter 

(meters) 8.534 8.534 8.534 8.534 8.534 8.534 8.534 

Stack Exit Temperature 

(Kelvin) 331 322.83 322.83 322.83 322.83 322.83 322.83 

Stack Exit Velocity (m/s) 17.4 16.76 16.76 16.76 16.76 16.76 16.76 

(a)H2SO4 assumed to be 100 percent of the SO4 emissions calculated by the NPS Speciation 

Spreadsheet. 

Visibility Post-Processing (CALPOST)

Light extinction must be computed to calculate visibility. CALPOST has seven methods for 

computing light extinction. As recommended by the WRAP RMC protocol, this BART technology 

analysis used Method 6, which computes extinction from speciated PM with monthly Class I areaspecific relative humidity adjustment factors. Relative humidity is an important factor in determining 

light extinction (and therefore visibility) because sulfate and nitrate aerosols, which absorb moisture from 

the air have greater extinction efficiencies with greater relative humidity. This BART analysis used 

relative humidity correction factors [f(RH)s], obtained from Table A-3 of the EPA’s Guidance for 

Estimating Natural Visibility Conditions under the Regional Haze Rule (EPA, 2003), to determine 

sulfate and nitrate concentrations outputs from CALPUFF. The f(RH) values for each Class I area that 

was assessed are provided in Table 20. The default Rayleigh scatter value (bray) of 10 Mm-1 was also 

used. The light extinction equation is as follows: 

bext = 3 * f(RH) * [(NH4)2SO4] + 3* f(RH) * [NH4NO3] + 4*[OC] + 1* [PMf] + 0.6*[PMc] + 

10* [EC] + bray 

 
San Juan Generating Station 

BART Determination 

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Table 20: Monthly Relative Humidity Factors(a) for CALPOST 

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Arches 2.6 2.3 1.8 1.6 1.6 1.3 1.4 1.5 1.6 1.6 2.0 2.3 

Bandelier 2.2 2.1 1.8 1.6 1.6 1.4 1.7 2.1 1.9 1.7 2.0 2.3 

Black Canyon 

of the Gunnison 

2.4 2.2 1.9 1.9 1.9 1.6 1.7 1.9 2.0 1.8 2.1 2.3 

Canyonlands 2.6 2.3 1.7 1.6 1.5 1.2 1.3 1.5 1.6 1.6 2.0 2.3 

Capitol Reef 2.7 2.4 2.0 1.7 1.6 1.4 1.4 1.6 1.6 1.7 2.1 2.5 

Grand Canyon 2.4 2.3 1.9 1.5 1.4 1.2 1.4 1.7 1.6 1.6 1.9 2.3 

Great Sand Dunes 2.4 2.3 2.0 1.9 1.9 1.8 1.9 2.3 2.2 1.9 2.4 2.4 

La Garita 2.3 2.2 1.9 1.8 1.8 1.6 1.7 2.1 2.0 1.8 2.2 2.3 

Maroon 

Bells 

2.2 2.1 2.0 2.0 2.1 1.7 1.9 2.2 2.1 1.8 2.1 2.1 

Mesa Verde 2.5 2.3 1.9 1.5 1.5 1.3 1.6 2.0 1.9 1.7 2.1 2.3 

Pecos 2.3 2.1 1.8 1.7 1.7 1.5 1.8 2.1 2.0 1.7 2.0 2.2 

Petrified Forest 2.4 2.2 1.7 1.4 1.3 1.2 1.5 1.8 1.7 1.6 1.9 2.3 

San Pedro Parks 2.3 2.1 1.8 1.6 1.6 1.4 1.7 2.0 1.9 1.7 2.1 2.2 

West Elk 2.3 2.2 1.9 1.9 1.9 1.7 1.8 2.1 2.0 1.8 2.1 2.2 

Weminuche 2.4 2.2 1.9 1.7 1.7 1.5 1.6 2.0 1.9 1.7 2.1 2.3 

Wheeler Peak 2.3 2.2 1.9 1.8 1.8 1.6 1.8 2.2 2.1 1.8 2.2 2.3 

(a)Table A-3 of the EPA’s Guidance for Estimating Natural Visibility Conditions under the Regional

Haze Rule 

According to the final BART rule, the EPA’s default average annual aerosol concentrations for the 

western half of the United States, included in Table 2-1 of EPA’s Guidance for Estimating Natural 

Visibility Conditions Under Regional Haze Rule (EPA-454/B-03-005, September 2003), were used to 

determine the natural background conditions representative of the Annual Average Natural Visibility 

Conditions in each Class I area used as a reference for determination of the modeled Δdv change. Table 

21 provides the Average Natural Levels of Aerosol Components. 
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Table 21: Average Annual Natural Background Levels(a) 

Component Average Annual Natural 

Background (μg/m3) 

Ammonium Sulfate 0.12 

Ammonium Nitrate 0.10 

Organic Carbon Mass 0.47 

Elemental Carbon 0.02 

Soil 0.50 

Coarse Mass 3.00 

(a)Table 2-1 of the EPA’s Guidance for Estimating Natural 

Visibility Conditions under the Regional Haze Rule.

Modeling Results

From the air dispersion modeling methodology outlined in the previous section, a CALPUFF model run 

was conducted for the following control technologies for each unit during the BART engineering 

analysis, including the pre-consent decree: Consent Decree, Rotamix, ROFA/Rotamix, ROFA, 

SCR/SNCR Hybrid (SCR/SNCR Hybrid with Inherent SO3 Removal), SCR with Sorbent (SCR with 

Inherent SO3 Removal and Sorbent Injection), PJFF, and WESP. To simplify the quantity of the 

modeling results, total visibility impacts at all 16 Class I areas were used to make comparisons of each 

control technology’s performance. 

For both the facility-wide and unit-by-unit modeling analysis conducted with the 2001-2003 years of 

meteorological data, the expected degree of visibility impact for each control technology was determined 

by the difference between the visibility impaired by the facility sources and annual average natural 

visibility conditions for each receptor at each of the 16 Class I area which is indicative of delta-deciview 

(delta-dv). 

 

Visibility Impact of NOx Control Technology

The results of the facility-wide analysis indicate the installation of SCR with sorbent control technology 

results in maximum visibility improvement at all of the 16 Class I areas when compared to the impact of 

the other control options. It is important to note that SCR with sorbent control technology improves 

visibility more significantly than the other control options at Mesa Verde National Park, which is the 

closest Class I area to the facility. 

Similar to the results seen in the facility-wide analysis, the visibility improvement at Mesa Verde National 

Park for each of the four units is maximized with SCR with sorbent control technology as shown in 

Figure 7. The results also indicate that by adding SCR with sorbent injection, visibility improvement is 

maximized at all the Class I areas over the three years of the modeled period. 

The results of the visibility modeling for Unit 1, Unit 2, Unit 3, and Unit 4 for each of the NOx control 

technologies are illustrated in Attachment A, Tables 1-28. These tables summarize the 98th percentile 

visibility impact for the pre-consent decree, baseline, and control scenarios, and the average and 

maximum number of days exceeding 0.5 dv threshold estimated at each of the Class I areas. 
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A summary of each graph representing the results of the visibility modeling is provided as follows: 

Figure 4 illustrates the maximum visibility deciview impact for each NOx control technology seen at 

each Class I area for the years 2001-2003 on a facility-wide basis. 

Figure 5 illustrates the maximum visibility deciview impact for each NOx control technology seen at 

each Class I area for the years 2001-2003 on a unit-by-unit basis. 

Figure 6 illustrates the maximum visibility deciview impact for each NOx control technology seen at 

Mesa Verde National Park for the years 2001-2003 on a facility-wide basis. 

 

Figure 7 illustrates the maximum visibility deciview impact for each NOx control technology seen at 

Mesa Verde National Park for the years 2001-2003 on a unit-by-unit basis. 

Visibility Impact of PM Control Technology

The visibility modeling performed for the WESP control option was performed on a facility-wide and 

unit-by-unit basis. The results of the facility-wide analysis demonstrate a net improvement of 0.62 dv at 

Mesa Verde National Park and 0.14 dv improvement at San Pedro Parks Wilderness. The amount of 

visibility improvement at all other Class I areas was equal to or less than 0.1 dv improvement. 

The results of the unit-by-unit impact analysis demonstrate a 0.21 dv improvement for Units 3 and 4 at 

Mesa Verde National Park. However, all other impact analyses show less than a 0.1 dv improvement at 

any of the Class I areas for Units 1-4. 
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Figure 4: Total Amount of the Visibility Impacts at All 16 Class I Areas Using 2001-2003 Meteorological 

Data (facility-wide impact) 
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Figure 5: Total Amount of the Visibility Impacts at All 16 Class I Areas Using 2001-2003 Meteorological 

Data (units 1, 2, 3, and 4) 
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Figure 6: Visibility Impact at Mesa Verde National Park Using 2001-2003 Meteorological Data (facilitywide impact) 
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Figure 7: Visibility Impact at Mesa Verde National Park Using 2001-2003 Meteorological Data (units 1, 

2, 3, and 4) 

Department Selection of BART for NOx and PM 

In accordance with Section 169A(g)(7) of the Clean Air Act, the Department considered the following 

five statutory factors in the BART analysis for the SJGS: (1) the costs of compliance; (2) energy and nonair 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 by anticipated to result from the use of such technology. 

PM BART Determination

Based on the five factor analysis, the Department has determined that BART for Units 1-4 for PM is 

existing PJFF technology and the existing emission rate of 0.015 lb/MMbtu. The Department’s 

determination of BART was based on the following results of the full five factor analysis: 

1) Each of Units 1-4 is equipped with PJFF and is subject to a federally-enforceable emission limit of 

0.015 lb PM/MMbtu. 
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2) The Department reviewed both the cost-effectiveness and incremental cost-effectiveness of 

additional control technology (WESP) and found these costs to be excessive. See Table 11. 

3) There are additional energy impacts associated with the WESP technology and the Department 

considers these costs to be reasonable. 

4) The Department reviewed the visibility improvement that resulted from the installation of the 

consent decree technology (PJFF and LNB/OFA) and that would result from the addition of 

WESP technology. The Department determined that on a facility-wide basis the visibility 

improved by 1.06 deciviews (dv) from the installation of the consent decree technology at Mesa 

Verde National Park (Mesa Verde). The installation of WESP would result in a facility-wide 

improvement of 0.62 dv at Mesa Verde. Improvements on a unit-by-unit basis at all Class I areas 

showed very minor improvements, usually less than 0.1 dv. 

NOx BART Determination

Based on the five factor analysis, the Department has determined that BART for Units 1-4 for NOx is 

SCR plus sorbent injection and an emission rate between 0.03 and 0.07 lb/MMbtu. The Department’s 

determination of BART was based on the following results of the five factor analysis: 

1) The PNM cost-effectiveness of SCR + sorbent technology ranges from $5,946/ton for Unit 4 to 

$7,398/ton for Unit 2, and the incremental cost-effectiveness of SCR + sorbent ranges from 

$1,691/ton for Unit 4 to $4,431/ton for Unit 2. Although the Department finds these values 

acceptable, they are conservative as demonstrated by the following evidence. These values are 

based on: (a) implementing the SCR projects separately at each unit (expected synergies between 

the construction projects should lower these costs); (b) incorporating the cost of SCR bypass at 

each unit without sufficient justification for why alternative fuels cannot be considered thus 

eliminating the need of the bypass altogether, or why the bypass for Units 3 and 4, two baseload 

units, could not be retrofitted with a catalyst that could accommodate occasional startups, 

eliminating their bypass; (c) including the cost of a full balanced-draft conversion at each unit 

without sufficient justification of the 10 inches of additional pressure drop; (d) including labor 

costs at the rates reflective of pre-recession 2007 values; (e) including the cost of purchase power 

for 5 full weeks at each unit, despite lack of detailed schedule provided by PNM; (f) PNM’s 

inclusion of various over-head and other factors without appropriate basis; and (g) an SCR 

removal efficiency of 77%, which significantly underestimates the tons of NOx that can be 

removed (SCR can typically achieve 90% removal efficiency). Additionally, PNM assumed that 

SO2 to SO3 conversion of 1% due to the SCR catalyst. Lower conversion catalysts are available, 

leading to lower sorbent and capital costs. 

The Department does not necessarily agree with the cost-estimates supplied in the impact analysis 

and finds some of the costs have not been fully justified. Cost estimates for SCR supplied by the 

NPS were consistently three to over four times lower than the cost estimates supplied by PNM. 

The Department expects the actual costs of SCR technology to be between the two cost-estimates 

supplied by PNM and NPS. 

2) The above notwithstanding, the cost-effectiveness and incremental cost-effectiveness of SCR plus 

sorbent technology calculated by PNM is considered reasonable by the Department. These costs 

are in line with acceptable cost-effectiveness values for BACT determinations, which involve a 

similar control technology evaluation process. With the considerations highlighted above, the 

cost-estimates would likely be lower. Thus, the price per ton of NOx removal would be lower. 
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3) The Guidelines state that regulatory agencies should require utility boilers to meet the presumptive 

limits, unless an agency determines that an alternative control is justified based on the 

consideration of statutory factors. The presumptive limit for NOx at Units 1-4 at the SJGS is 0.23 

lb/MMbtu. However, in light of the reasonable cost-effectiveness and incremental costeffectiveness, acceptable energy impacts and non-air quality environmental impacts, and visibility 

improvement resulting from installation of SCR plus sorbent, the Department has determined 

BART as SCR plus sorbent injection. See Table 10 and Visibility Results Section. 

4) Annual NOx emissions from the facility will be reduced by 16,100 tons from SCR plus sorbent, at 

the assumed 0.07 lb/MMbtu value used by PNM. At 0.03 lb/MMBtu, the NOx emissions from the 

facility will be greater still. 

5) The Department reviewed the visibility improvement that resulted from the installation of the SCR 

plus sorbent technology at the 0.07 lb/MMbtu NOx level. The Department determined that on a 

facility-wide basis the visibility improved by 1.34 deciviews (dv) from the installation of SCR 

plus sorbent technology at Mesa Verde, 0.88 dv at San Pedro, 0.75 dv at Bandalier, 0.73 dv at 

Capital Reef, 0.67 dv at Canyonlands, 0.59 dv at Arches, 0.59 dv at Weminuche, 0.52 dv at Black 

Canyon, 0.49 dv at La Garita, 0.49 dv at West Elk, 0.44 dv at Grand Canyon, 0.43 dv at Pecos, 

0.40 dv at Wheeler Peak, 0.34 dv at Petrified Forest, 0.31 at Great Sand Dunes, and 0.28 dv at 

Maroon Bells. Visibility improvements will be greater using a NOx level of 0.03 lb/MMBtu. 

6) Again using a NOx value of 0.07 lb/MMbtu, SCR plus sorbent technology reduced the number of 

days that each Unit exceeded a 0.5 dv impact. For Unit 1, the number of days exceeding 0.5 dv 

was reduced from 46 days to 16 days; Unit 2’s impact decreased from 46 days to 16 days; Unit 3’s 

impact decreased from 68 days to 31 days; and Unit 4’s impact decreased from 67 days to 29 days. 

Impacts would be further reduced at a NOx limit of 0.03 lb/MMBtu. 

7) The installation of SCR plus sorbent technology will result in additional energy impacts and nonair environmental impacts, and the remaining useful life of 20 years did not further impact costs. 

None of the additional energy or non-air environmental impacts prohibit selection of this 

technology. 
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References

1. 40 CFR 51 – Regional Haze Regulations and Guidelines for Best Available Retrofit Technology 

(BART) Determinations 

2. Summary of WRAP RMC BART Modeling for New Mexico (April 21, 2006) 

3. Public Service Company of New Mexico BART Technology Analysis for the San Juan 

Generating Station (June 6, 2007 and submittal updates) 

4. EPA. (2003). Air Pollution Control Technology Fact Sheet (SNCR). Retrieved from 

http://www.epa.gov/ttn/catc/dir1/fsncr.pdf

5. EPA. (2003). Air Pollution Control Technology Fact Sheet (SCR). Retrieved from 

http://www.epa.gov/ttn/catc/dir1/fscr.pdf

6. EPA. (2003). Guidance for Estimating Natural Visibility Conditions under the Regional Haze 

Rule. http://www.epa.gov/ttncaaa1/t1/memoranda/rh_envcurhr_gd.pdf