## APPENDIX D

TO NEW MEXICO’S REGIONAL HAZE SIP UNDER 40 C.F.R. § 51.309(g)



# New Mexico Environment Department Air Quality Bureau

Revised BART Determination

Public Service Company of New Mexico San Juan Generating Station

, Units 1

- 4

May 21 , 2013
Revised June 27, 2013San Juan Generating Station

BART A ssessment Page 2

PREFACE

This document is a revised version of the BART Determination for Public Service Company of New

Mexico (PNM) S an Juan Generating Station Units 1

- 4 that was attached as Appendix D to New Mexico’s June 2011 Regional Haze S tate I mplementation P lan (SIP)

, submitted pursuant to 40 CFR § 51.309(g). As explained with in, it has been revised to incorporate new information su bmitted by PNM in April 2013 . The new information was submitted in accordance with the terms of a tentative agreement between NMED, EPA, and PNM , which when fully implemented would resolve a dispute over the determination of Best Available Retrofit Technol ogy ( BART ) for Nitrogen
Oxides (NOx) for the San Juan Generating Station.San Juan Generating Station

BART A ssessment Page 3

Regulatory Background and Introduction:

In 1999, the U.S. Environmental Protection Agency ( EPA ) published a final rule to address a type of visibility impairment known as regional haze (6 4 FR 35714, July 1, 1999). This rule requires States to submit state implementation plans (SIPs) to address regional haze visibility impairment in 156 Federally

pr otected parks and wilderness areas. The 1999 rule was issue d 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 CA A , the EPA included in the final regional haze rule a requirement for B est

A vailable R etrofit T echnology (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 50.3 01.

The BART

- eligible sources are those sources which (1) have the potential to emit 250 tons per year o r more of a visibility impairing air pollutant ; (2) were put in place between August 7, 1962 and August 7,

1977 ; and (3) 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 visibil ity 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 publish ed 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 anal ysis of the degree of visibility improvement resulting from the use of control technology at BART

- subject sources; (2) revised certain other BART provisions; (3) included new BART Guidelines contained in a new Appendix Y to Part 51 (Guidelines) ; and (4) ad ded 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 SO 2 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 gene rating capacity greater than 750

MW , unless it is determined that an alternative control level is justified based on consideration of the statutory factors . The presumptive limits for NOx are based on coal type, boiler type and whether SCR or

SNCR are alr eady 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 ex istence” 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 source s as
BA RT

- eligible sources as part of this review

. 2San Juan Generating Station

BART A ssessment Page 4

T he 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 (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 Cl ass I area. New Mexico opted to perform an initial screening model on each of the se BART

- eligible sources to determine whether e a ch source did cause or contribute to any visibility impairment. The Guidelines direct S tates 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 guidelines pr ovide that the threshold for determining whether a source “contributes” to visibility impairment should be set no higher than 0.5
deciview (dv).

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. V isibility impacts due to emissions of SO 2 , NOx and primary PM emissions were

calculated

. PM emissions were modeled as PM 2.5

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

Natural Conditions

.

Initial m odeling was performed for the 11 source complexes in New Mexico to assess visibility impacts

from SO 2 , NOx, and PM em issions.

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

due to combined SO 2 , NOx, and PM emissions exceeded the 0.5 dv threshold

. This source was PNM San Juan Generating Station

, Boilers #1

- 4 (“SJGS”)

. Of the 10 other source complexes, none exceed a 0.33 dv impact . Therefore, for the SJGS only, the separate contribution to visibility at Class I areas was

assessed for SO 2 alone (SO 4 ), NOx alone (NO 3 ), PM alone (PMF)

, and combined NOx plus PM emissions
(NO 3 + PMF). 2

On November 9, 2006 , the Department informed PNM that the modeling performed by the WRAP indicated the visibility impairment from the SJGS was over the 0.5 dv threshold, and SJGS 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 SJGS.

SJGS Source Description:

Th e 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 isSan Juan Generating Station

BART A ssessment Page 5

supplied to the electric power grid for sale. Coal for the units is supplied by the adjacent San Juan Mine

a nd is delivered to the facility by conveyor.

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 opera te in a forced draft mode. The

SJGS Bo iler Units 3 and 4 each have a unit capacity of 544 MW and are equipped with 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 Trus t, 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/ MM B tu ) (measured using
EPA Reference Method 5) , and a 0.30 lb/ MM B tu emission rate for NOx ( daily rolling, thirty day average) , for each of Units 1, 2, 3, and 4 . As a result, PNM installed 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

SO 2 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 an d 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

T he determination of BART for fossil

- fuel power plants having a total generating capacity in excess of 750 megawatts must be made pursuant to the G u idelines

. 1San Juan Generating Station

BART A ssessment Page 6

PNM’s BART Analysis for NOx and PM :

PNM submitted a 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, 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 project ed from the 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 Te chnically 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) Rem aining useful life Step 5

– Evaluate Visibility Impacts

In response to the Department ’ s requests, PNM submitted multiple amendments to the original June 2007 BART Analysi s application

. What follows is a summary of the original and additional submittals:

June 6, 2007 The original BART analysis application includ ed 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 const ant 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 cont rol technologies analyzed were the SCR and SNCR/SCR Hybrid. 3

March 29 , 2008

PNM submitted an additional d iscussion 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 representati ve of ammonia chemistry of the area, was based on the November 6, 2007 refinements which included using nitrate repartitioning methodology and monthlySan Juan Generating Station

BART A ssessment Page 7

variable background ammonia co ncentrations. The other analysi s included nitrate repartitioning and a

con stant 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 S N CR 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 analysi s used nitra te repartitioning methodology and constant background ammonia concentration.

It should be noted that PNM modeled all variants of SNCR together (including Fu el Tech and Nalco
Mobotec) as one technology called SNCR. This is the same approach that is used f or 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 a t the SJGS

.

August 29, 2008 Three modeling analyses were performed to provide SJGS plant

- wide and unit specific regional haze

v isibility 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, 20 07 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 technolog y, 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 Cl ass 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

SO 3 removal of the SO 3 formed from the catalyst oxidation of SO 2 to SO 3

. 3

February 15, 2011 A revised analysis of SNCR technology was submitted after PNM received a lower vendor

- guaranteed
emission rate from Fuel Tech, a vendor of S NCR technology. The analysis also included updated cost estimates for SCR, SNCR/SCR Hybrid, ROFA/Rotamix, Rotamix (SNCR), ROFA, and SNCR (Fuel Tech) technologies

.

The submittal further included a ratepayer impact analysis which estimated the cost impac t to residential

ratepayers from installation of SNCR and SCR technologies.

O ne modeling analysis was performed to provide SJGS plant

- wide and unit specific regional haze visibility impacts at 16 Class I areas assuming the revised SNCR control technology on all four units. 3

April 1, 2013

T his submittal compares new information as contained in a non

- binding term sheet signed by the EPA, NMED and PNM on February 15, 2013. This update considers the emissions reductions and economic analysis of three specific control scenarios at SJGS, as contained in the EPA’s Federal ImplementationSan Juan Generating Station

BART A ssessment Page 8

Plan, issued August 22, 2011 (SCR on all four units, or 4 SCR) ; the State of New Mexico’s State Implementation Plan, approved by the State Environmental Improvement Board on June 2, 2011 (SNCR
on all four units, or 4 SNCR) ; and an alternative entitled the State Alternative Plan , not previously analyzed , which considers the voluntary retirement of Units 2 and 3 (SNCR on Units 1 and 4 and the
shutdown of Units 2 and 3, or 2 SNCR/2 Shutdown)

.

An updated cost analysis of installing SCR control on all four units, SNCR control on all four units, and

insta lling SNCR on Units 1 and 4 wa s prepared by Sargent & Lundy (S& L ) at the request of PNM. This analysis reflect ed the approach described in the EPA’s Control Cost Manual.

An updated visibility analysis based on the installation of SCR on all four units, SNCR on all four units,

and SNCR on Units 1 and 4 and a two

- unit shut down scenario was also submitted. This analysis is included in addition to the previous modeling analy sis and is presented as the Updated Visibility Modeling Assessment Submitted April 1, 2013 of Step 5 of this document.

The updated visibility analysis for the installation of SCR on all four units and SNCR on all four units incorporated the SO 2 and total particulate matter (TPM) emission rates of 0.15 lb/MM B tu and 0.034

lb/MM B tu, respectively, from the current NSR Permit issued August 31, 2012. The updated visibility analysis for the installation of SNCR o n Units 1 and 4 and a two

- unit retirement incorpor ated the new

TPM emission rate of 0.034 lb/MM B tu and an SO 2 emission rate of 0.10 lb/MM B tu. This new SO 2 emission rate will be incorporated into the facility’s NSR Permit as a federally

- enforceable permit

condition should this scenario be determined as BART for the source.

Step 1 of the BART Analysis: Identification of All Available Retrofit Emissions Cont rol 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 temperatu re s, and 2) post

- combustion treatment

of the flue gas to rem ove NOx. PNM and B&V identified the following available NOx control technologies and a discussion of each of the technologies:

1) Low NOx Burners, Over fire 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 the primary combustion zone with the remaining (overfire) air added higher in the furnace to compl ete combustion. Neural Networ k provide s improvements in the heat rate and reduce s
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 mol ecule into molecular nitrogen and water

vapor . A nitrogen based reducing agent (reagent), such as ammonia or urea, is injected into the post combustion f lue gas. The reduction with NO is favored over other chemical reaction processes at temperatures ranging between 1600F and 2100F (870C to 1150 C), therefore, it is

considered a select ive chemical process

. 4

3) Selective Catalytic Reduction (SCR)San Juan Generating Station

BART A ssessment Page 9

Th e 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

thro ugh 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

Sorbent injection removes SO 3 in the flue gas by reaction of the SO 3 with an alkaline sorbent

materi al 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 l ow ammonia slip

inherent in the catalyst of SCR systems. 3

SNCR/SCR Hybrid plus Sorbent Injection

Sorbent injection removes SO 3 in the flue gas by reaction of the SO 3 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 combus ts auxiliary natural gas, along with coal, in the boiler. Three separate combustion zones in the boiler are manipulated to reduce NOx emissions. 4

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 othe r 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 red uction 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 toSan Juan Generating Station

BART A ssessment Page 10

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 ECO syste m 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 (SO 2 ), nitrogen oxides (NO x ), oxidized mercury, and fine particulate matter. 3

10) Phenix Clean Combustion

The Phenix Clean Combustion System is an advanced hybrid coal gasification/combustion process that prevents the formation of NOx and SO 2 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 SO 3 or ammonia. These compounds combine with the moisture in the flue gas and are deposited o n 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. Clean ing 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) Compac t 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 remo ved. 3

4) Max

- 9 Electrostatic Fabric FilterSan Juan Generating Station

BART A ssessment Page 11

The Max

- 9 filter is essentially a high

- efficiency PJFF utilizing a dis charge 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/ MM B tu for dry bottom

, wall

- fired boilers burning sub

- bituminous

coal . A vendor estimated that the technology could only achieve 0.24 lb NOx/ MM B tu . 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 B ART analysis required by the

Guidelines on SNCR. PNM submitted the five

- factor analysis of SNCR in a subsequent submittal dated May 30, 2008 , an updated analysis of Fuel Tech’s SNCR on February 11, 2011

, and an additional updated analysis on April 1, 2013

.

2) Natural Gas Reburn

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

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

limitations.

3) Nalco Mobotec 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 coal

fired boilers equivalent to 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 tec hnically infeasible.

Therefore

, the Department requested PNM perform the complete 5

- factor analysis for ROFA and Rotamix. PNM performed the analysis and submitte d the analys is in two subsequent submittals dated March 29, 2008 and August 29, 2008.San Juan Generating Station

BART A ssessment Page 12

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 bo ilers firing sol i d 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 demonstrate d 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 deter mined 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 typ e and is not technically feasible.

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 de monstrated 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 rat e

, the technology does not need to undergo the three additional factors of the five factor analysis.

2) Compact Hybrid Particulate Collector

T he 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 una ble toSan Juan Generating Station

BART A ssessment Page 13

guarantee a lower emission rate

, the technology does not need to undergo the three addition al 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 si milar 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 , t he Department request ed PNM to perf orm a complete five

- f actor 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 a report in a subsequent submittal dated August 28, 2008.

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

PN M contracted with B&V and S&L to determine the control effec tiveness 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 Table s 2

– 5 , and the control efficiencies of the PM control technologies

are summarized i n Table s 6

– 9.

Table 2 : NOx Control Effectiveness for Unit 1

Control Technology Control Efficiency
( % ) Baseline

Emissions (tpy) Emissions

Reduction (tpy) Controlled

Emission Rate

(lb/ MM B tu ) 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

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 83 4140 3 450 0.0 5 690San Juan Generating Station

BART A ssessment Page 14

Table 3: NOx Control Effectiveness for Unit 2

Control Technology Control Efficiency
(%) Baseline

Emissions (tpy) Emissions

Reduction (tpy) Controlled

Emission Rate

(lb/ MM B tu ) Controlled

Emission Rate (tpy)

Pre

- Consent Decree
(Pre

- CD) NA NA NA 0.45 6179

CD 33 6179 2060 0.30 4119

ROFA 13 4 119 549 0.26 35 70
Rotamix (SNCR) 23 41 19 96 1 0.23 31 58

SNCR 23 4119 961 0.23 3158

ROFA/Rotamix 3 3 41 19 13 73 0.20 27 46
SCR/SNCR Hybrid 40 41 19 16 48 0.18 24 71

SCR 83 41 19 3432 0.05 687

Table 4: NOx Control Effectiveness for Unit 3

Control Technology Control Efficiency
(%) Baseline

Emissions (tpy) Emissions

Reduction (tpy) Controlled

Emission Rate

(lb/ MM B tu ) Controlled

Emission Rate (tpy)

Pre

- Consent Decree
(Pre

- CD) NA NA NA 0.42 9004

CD 29 9004 2 573 0.30 6431

ROFA 13 6431 857 0.26 5574
Rotamix (SNCR) 23 6431 1500 0.23 4931

SNCR 23 6431 1500 0.23 4931

ROFA/Rotamix 3 3 6431 2144 0.20 4287
SCR/SNCR Hybrid 40 6431 2572 0.18 3859

SCR 83 6431 5359 0.05 1072

Table 5 : NOx Control Effectiveness for Unit 4

Control Technology Control Efficiency
(%) Baseline

Emissions (tpy) Emissions

Reduction (tpy) Controlled

Emission Rate

(lb/ MM B tu ) Controlled

Emission Rate (tpy)

Pre

- Consent Decree
(Pre

- CD) NA NA NA 0.42 8833

CD 29 8833 2524 0.30 6309

ROFA 15 6309 841 0.26 5468
Rotamix (SNCR) 2 3 6309 1472 0.23 4837

SNCR 2 3 6 309 1472 0.23 4837

ROFA/Rotamix 3 3 6309 2103 0.20 4206
SCR/SNCR Hybrid 4 0 6309 2524 0.18 3786

SCR 83 6309 5257 0.0 5 1052

Table 6: PM Control Effectiveness for Unit 1

Control Technology Control Efficiency
(%) Baseline

Emissions (tpy) Emissions

Reduction (tpy) Controlled

Emission Rate

(lb/ MM B tu ) 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 138San Juan Generating Station

BART A ssessment Page 15

Table 7: PM Control Effectiveness for Unit 2

Control Technology Control Efficiency
(%) Baseline

Emissions (tpy) Emissions

Reduction (tpy) Controlled

Emission Rate

(lb/ MM B tu ) 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/ MM B tu ) 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/ MM B tu ) 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 cost

effectiveness of each additional control technology and allow comparisons to be made between the remaining controls

. B &V pe rformed an impact analysis for the remaining NOx and PM control technologies in accordance with the Guidelines

.

B&V and S&L prepared the design parameters and developed estimates of capital and annual costs for applications of SCR, SNCR, 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, SCR and SNCR equipment vendors, EPA cost manuals, engineering and performance data, and B&V’s own in

- house engineering estimates.

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

SCR , SNCR and SCR/SNCR Hybrid technology, the non

- air quality environmental impacts included the consideration of water usage and waste generat ed 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

u sef ul life was defined as 20 years , except for the 2013 analysis for 4 SCR, 4 SNCR and 2 SNCR/2San Juan Generating Station

BART A ssessment Page 16

Shutdown which used a remaining useful life of 30 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 impac t analysis for SCR , SNCR, ROFA, Rotamix and WESP, and for further consideration of inherent and

additional control of SO 3 from both the SCR and SCR/SNCR Hybrid technology.

SCR Costs

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

PNM 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 analysi s for SCR technology and submitted

it to the De partment 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.

In April, 2013, PNM submitted an update d cost an alysis of SCR prepared by S&L

. PNM contracted with S&L to prepare a conceptual design, project cost estimate and technical portions of an Engineer, Procurement, and Construction p lan. S&L used budgetary quotes from equipment vendors for the major components and S&L’s i n

- house database of equipment and material costs for similar projects. For the revised 2013 analysis for 4 SCR, 4 SNCR, and 2 SNCR/2 Shutdown, t he capital cost estim ates are stated

in 2013 dollars. The previously submitted cost analyses for other alternatives used 2010 dollars. Because the rate of inflation between 2013 and 2010 was minimal (1.07 percent), the costs are comparable.

Consideration of SO 3 Control PNM’s initial analysis of SCR and SCR/SNCR technology took into consideration additional oxidation of

SO 2 to SO 3 across the SCR catalyst bed. The Department requested PNM to consider inherent removal of

SO 3 emissions from existing air pollution control equipment , and removal of SO 3 emissions th r ough installation of sorbent injection. PNM responded with an amended submittal addressing both inherent

and add

- on removal of SO 3 . PNM’s submittal provided cost estimates of the sorbent injection system and upd ated visibility modeling for both SCR and SCR/SNCR Hybrid technologies.

The updated 2013 analysis of 4 SCR, 4 SNCR, and 2 SNCR/2 Shutdown uses EPA estimates of SO 3 emissions from the 2011 EPA Federal Implementation Plan (FIP) 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

. Please refer to the Chronology of Submissions located earlier

in this document for an overview of the specific updates to these technologies.San Juan Generating Station

BART A ssessment Page 17

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

Control Technology Emission

Performance

Level
(lb/ MM B tu ) Expected

Emission Rate (tpy) Expected

Emission

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
(FIP) 0.0 5 690 3, 450 1 80,862 22,165 6,425 6,749 746 NA 1

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, 39 2 5,400 5,590 80 43 NA 1

ROFA 0.26 3,588 552 19,256 3,549 6,429

-- 1,363 NA 1

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

Pre

- CD 0.43 5,394 NA NA NA NA NA NA NA 1



## Unit 2

SCR + sorbent
(FIP) 0.05 687 3, 43 3 203,360 24,562 7, 157 7,755 729 NA 1

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 17,39 2 5,400 5,618 80 43 NA 1

ROFA 0.26 3,570 549 19,256 3,549 6,462

-- 1,363 NA 1

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

Pre

- CD 0.45 6,179 NA NA NA NA NA NA NA 1



## Unit 3

SCR + sorbent
(FIP) 0.05 1, 072 5,359 2 6 4,208 32,585 6, 080 6,313 1,107 NA 1

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 NA 1

ROFA 0.26 5,574 857 22,081 5,231 6,100

-- 2,725 NA 1

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

Pre

- CD 0.42 9,004 NA NA NA NA NA NA NA 1



## Unit 4

SCR + sorbent
(FIP) 0.05 1,05 2 5,257 2 35,940 2 9,508 5, 613 5,623 1,102 NA 1

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 NA 1

ROFA 0.26 5,468 841 22,081 5,231 6,218

-- 2,725 NA 1

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

Pre

- CD 0.42 8,833 NA NA NA NA NA NA NA 1

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 A ssessment Page 18

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

1 PNM performed an impact analysis for these technologies and incorporate d any monetized energy or non

- air environmental impacts

into the cost analysis

.

Step 5 of the BART Analysis: Visibility Impacts An alysis 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). B ased o n the results of the WRAP screening modeling, PNM SJGS was required to conduct a refined BART analysis that included CALPU FF 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 CALPUFF modeling system is described below, followed by a description of the modeling analysis performed in 2011, and, finally, by a description of the updated modeling performed in 2013 that takes Control Technology Emission

Performance

Level
(lb/ MM B tu ) 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 NA 1

PJFF
(CD) 0.015 207 483 67,072 10,427 NA 21,588 4,488 NA 1

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 NA 1

PJFF
(CD) 0.015 207 480 69,840 10,764 NA 22,425 4,488 NA 1

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 NA 1

PJFF
(CD) 0.015 322 750 72,696 12,454 NA 16,605 6,895 NA 1

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 NA 1

PJFF
(CD) 0.015 315 737 73,328 12,527 NA 16,997 6,895 NA 1

Pre

- CD 0.050 1052 NA NA NA NA NA NA NASan Juan Generating Station

BART A ssessment Page 19

into consideration the State Alter native (2 SNCR/2 Shutdown), and compares it to the state’s 2011 NOx

BART determination of 4 SNCRs and the EPA FIP BART determination of 4 SCRs

.

CALPUFF System The CALPUFF modeling system consists of a meteorological data pre

- processor (CALMET), an air

dis persion model (C A LPUFF), 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 po llutant transport,
transformation, and removal.

CALMET is a diagnostic wind model that develops hourly wind and temperature fields in a three

dimensional, gridded modeling domain. Meteorological inputs to CALMET can include surface and

upper

- air observat ions 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

- di mensional 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 three

dimensional wind fields developed by the CALMET model (refined mode), or by data from a single surface and up per

- 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 comple ted using the

CALPUFF model in the refined mode.

CALSUM is a post

- processing p rogram that can operate on multiple CALPUFF output files to combine the results for further post

- processing. POSTUTIL is a post

- processing program that combines the concentrations, wet and dry deposition flux files created by CALPUFF to calculate the total nitrogen and total sulfur deposition fluxes from nitrogen dioxide (NO 2 ), nitrates (NO 3 - ), nitric acid (HNO 3 ), sulfur
dioxide (SO 2 ) and sulfates (SO 4 2

- )

. CALPOST is a post

- processing program that can read the CALPUFF (or POSTUTIL or CALSUM) output files and calculate the impacts to visibility.

The 2011 refined CALPUFF modeling was conducted with the version of the CALPUFF system recommended by the WRAP BART modeling protocol. The 2013 refined CALPUFF modeling was conducted with the version of the CALPUFF system recommended by the EPA Version designations of the key programs listed in Table 12

.

Table 12: CALPUFF System Used

2011 Modeling 2013 Modeling

Version Level Version Level

CALMET 6.211 060414 5.8 070623

CALPUFF 6.112 060412 5.8 070623

POSTUTIL 1.52 060412 1.56 070627

CALSUM 1.33 051122 1.33 051122

CALPOST 6.131 060410 6.221 080724San Juan Generating Station

BART A ssessment Page 20

Meteorological Data Processing (CALMET)

T he CALMET model was used to construct an initial three

- dimensional 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 variabl es 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 for the 2011 analysis. In the 2013 updated analysis, surface, upper air, precipitation, and MM5 data were provided by EPA. Locations of the observations that were input to

CALMET for both the 2011 analysis and the 2013 analysis , including surface and pr ecipitation sta tions, are shown in Figures 1 and 2 . Default settings were used in the CALMET input files for most of t he technical options. Table 13 lists the key user

- defined CALMET settings that were selected.

Figure 1 : Surface StationsSan Juan Generating Station

BART A ssessment Page 21

Figure 2 : Precipitation StationsSan Juan Generating Station

BART A ssessment Page 22

Table 13 : Key User

- Defined CALMET Settings

Variable Description Value

2011 Analysis 2013 Analysis

PMAP Map projection LCC LCC

DGRIDKM Grid spacing (km) 4 4

NZ Number of layers 11 11

ZFACE Cell face heights (m) 0, 20, 100, 200, 350,
500, 750, 1000,
2000, 3000, 4000,

5000 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 0

IEXTRP Extrapolate surface wind obs to upper level 1

- 4

RMIN2 Minimum distance for extrapolation 4 4

IPROG Use gridded prognostic model output 14 14

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

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

TERRAD Radius of influence for terrain (km) 10 10

R1 Relative weighting of first guess wind field and
observation (km) 100 50

R2 Relative weighting aloft (km) 200 100

ITPROG 3D temperature from observations or from

MM5 1 0

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 SO 2 and NOx to

SO 4 and NO 3 , respectively. In the 2011 analysis, f or ozone, t he 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 sa me monthly average background ozone value of 80 ppb that

w as used in the initial modeling was used in this modeling for times when hourly ozone data were not

availab le. In the 2013 analysis, the hourly ozone concentrations files that came directly from EPA were

used and the o zone concentration of 80 ppb was used for the missing hours in the ozone data files.

For ammonia, in the 2011 analysis, the monthly variable background ammonia concentr ations were used for the BART modeling analysis. They are as follows:San Juan Generating Station

BART A ssessment Page 23

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

In the 2013 analysis, a constant ammonia background concentration of 1.0 ppb was used.

There are many Class I areas within and surrounding New Mexico. On the basis of distance from BART applicable sources, topography, and meteorology

, th e screening modeling conducted by WRAP RMC

determi ned that 16 Cl ass I areas need ed to be addressed in the BART analysi s. The applicable Class I

areas included in the BART analysis are located within 300 km of the SJGS facility. As shown in Fi gure
3 , the nearest Class I area is Mesa Verde National Park

, located approximately 4 0 km north of the facility

and the most distant Class I area is Grand Canyon National Park

, located approximately 300 km west of the facility . All Class I area distances from the facility fall within the range recommended for CALPUF F application. The 16 Class I a reas are identified in Table 15 and an illustration of the receptors used in the

2011 and 2013 modeling analys e s for each Class I area is provided in Appendix B. The CALPUFF 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 : Locati on of SJGS and the Class I AreaSan Juan Generating Station

BART A ssessment Page 24

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)

8. Petrified Forest National Park (PEFO) 15. Maroon Bells

- Snowmass Wilderness

(MABE)

16. Grand Canyon National Park (GRCA)

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 s hown in Tables 16 through 19

.

(1) Emissions l evels (lb/MM B tu) are shown on an annual average basis.
(2) Emissions (lb/hr) calculations were based on the emissions level (lb/MM B tu) and design heat basis.
(3) Emissions levels listed were based on performance guarantees provided by the equipment vendor. (4) For the 2011 analysis, H 2 SO 4 is assumed to be 100 percent of the SO 4 emissions calculated by the NPS Speciation Spreadsheet . The 2013 analysis utilizes the Electric Power Research Institute (EPRI) methodology.San Juan Generating Station

BART A ssessment Page 25

Table 16 : CALPUFF Inputs for Unit 1

Model Input Data 2011 Analysis 2013 Analysis

Pre

Consent

Decree Consent

Decree Rotamix

or ROFA/ ROFA SCR/SNC R Hybrid SCR

with

Sorbent Baseline 4 SCR 4 SNCR 2 SNCR/2

Shutdown SNCR Rotamix

Hourly Heat Input
( MMBtu /hour) 3707 3707 3707 3707 3707 3707 3707 3707 3707 3707 3707

Sulf ur Dioxide
(SO 2 ) (lb/ MMBtu ) 0.24 0.18 0.18 0.18 0.18 0.18 0.18 0.15 0.15 0.15 0.10

Sulf ur Dioxide
(SO 2 ) (lb/hr) 877.8 667.3 667.3 667.3 667.3 667.3 667.3 556.1 556.1 556.1 370.7

Nitr ogen Oxide
(NOx) (lb/ MMBtu ) 0.43 0.33 0.23 0.2 0.26 0.18 0.07 0.30 0.05 0.23 0.23

Nitrogen Oxide
(NOx) (lb/hr) 1592 1223.3 852.6 741.4 963.8 667.3 259.5 1112.1 185.4 852.6 852.6

PM ( lb/ MMBtu ) 0.05 0.015 0.015 0.015 0.015 0.015 0.015 0.034 0.034 0.034 0.034

PM ( lb/hr) 185.4 55.6 55.6 55.6 55.6 55.6 55.6 126.04 126.04 126.04 126.04

SO 3 as Sulfuric
Acid (H 2 SO 4 )
(lb/ MMBtu ) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 4.6E

- 05 0.00026 4.6E

- 05 4.6E

- 05

SO 3 as Sulfuric
Acid (H 2 SO 4 ) (a)

(lb/hr) 50 40.5 40.5 40.5 40.5 114.2 16.1 0.17 0.96 0.17 0.17

Stac k Conditions

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

Stack Exit Diameter
(meters) 6.096 6.096 6.096 6.096 6.096 6.096 6.096 6.10 6.10 6.10 6.10

Stac k Exit Temp

. (Kelvin) 336 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83

Stac k Exit Velocity
(m/s) 22.6 21.34 21.34 21.34 21.34 21.34 21.34 21.34 21.34 21.34 21.34San Juan Generating Station

BART A ssessment Page 26

Table 17 : CALPUFF Inputs for Unit 2

Model Input Data 2011 Analysis 2013 Analysis

Pre

Consent

Decree Consent

Decree Rotamix

or ROFA/ ROFA SCR/SNCR Hybrid SCR

with

Sorbent Baseline 4 SCR 4 SNCR 2 SNCR/2

Shutdown
SNCR Rotamix

Hourly Heat Input
( MMBtu /hour) 3688 3688 3688 3688 3688 3688 3688 3688 3688 3688 3688

Sulf ur Dioxide
(SO 2 ) (lb/ MMBtu ) 0.23 0.18 0.18 0.18 0.18 0.18 0.18 0.15 0.15 0.15 0

Sulfur Dioxide
(SO 2 ) (lb/hr) 844 663.8 663.8 663.8 663.8 663.8 663.8 553.2 553.2 553.2 0

Nitrogen Oxide
(NOx) (lb/ MMBtu ) 0.45 0.33 0.23 0.2 0.26 0.18 0.07 0.30 0.05 0.23 0

Nitr ogen Oxide
(NOx) (lb/hr) 1649.3 1217 848.2 737.6 958.9 663.8 258.2 1106.4 184.4 848.2 0

PM ( lb/ MMBtu ) 0.05 0.015 0.015 0.015 0.015 0.015 0.015 0.034 0.034 0.034 0

PM ( lb/hr) 184.4 55.3 55.3 55.3 55.3 55.3 55.3 125.39 125.39 125.39 0

SO 3 as Sulfuric
Acid (H 2 SO 4 )
(lb/ MMBtu ) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 4.6E

- 05 0.00026 4.6E

- 05 0

SO 3 as Sulfuric
Acid (H 2 SO 4 ) (a)

(lb/hr) 49.7 40.3 40.3 40.3 40.3 113.6 16 0.17 0.96 0.17 0

Stack Conditions

Stack Height
(meters) 121.92 121.92 121.92 121.92 121.92 121.92 121.92 121.92 121.92 121.92 0

Stac k Exit Diameter
(meters) 6.096 6.096 6.096 6.096 6.096 6.096 6.096 6.10 6.10 6.10 0

Stack Exit Temp

. (Kelvin) 338 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 0

Stac k Exit Velocity
(m/s) 23.5 21.34 21.34 21.34 21.34 21.34 21.34 21.34 21.34 21.34 0San Juan Generating Station

BART A ssessment Page 27

Table 18 : CALPUFF Inputs for Unit 3

Model Input Data 2011 Analysis 2013 Analysis

Pre

Consent

Decree Consent

Decree Rotamix

or
SNCR ROFA/

Rotamix ROFA SCR/SNCR Hybrid SCR

with

Sorbent Baseline 4 SCR 4 SNCR 2 SNCR/2

Shutdown

Hourly Heat Input
( MMBtu /hour) 5758 5758 5758 5758 5758 5758 5758 5758 5758 5758 5758

Sulf ur Dioxide (SO 2 )
(lb/ MMBtu ) 0.28 0.18 0.18 0.18 0.18 0.18 0.18 0.15 0.15 0.15 0

Sulfur Dioxide (SO 2 )
(lb/hr) 1591.1 1036.4 1036.4 1036.4 1036.4 1036.4 1036.4 863.7 863.7 863.7 0

Nitr ogen Oxide
(NOx) (lb/ MMBtu ) 0.42 0.33 0.23 0.2 0.26 0.18 0.07 0.3 0.05 0.23 0

Nitrogen Oxide
(NOx) (lb/hr) 2405.5 1900.1 1324.3 1151.6 1497.1 1036.4 403.1 1727.4 287.9 1324.3 0

PM ( lb/ MMBtu ) 0.05 0.015 0.015 0.015 0.015 0.015 0.015 0.034 0.034 0.034 0

PM (lb/hr) 287.9 86.4 86.4 86.4 86.4 86.4 86.4 195.77 195.77 195.77 0

SO 3 as Sulfuric Acid
(H 2 SO 4 ) (lb/ MMBtu ) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 4.6E

- 05 0.00026 4.6E

- 05 0

SO 3 as Sulfuric Acid
(H 2 SO 4 ) (a) (lb/hr) 77.7 62.9 62.9 62.9 62.9 177.3 25 0.26 1.50 0.26 0

Stack Conditions

Stack Height (meters) 121.92 121.92 121.92 121.92 121.92 121.92 121.92 121.92 121.92 121.92 0

Stack Exit Diameter
(meters) 8.534 8.534 8.534 8.534 8.534 8.534 8.534 8.53 8.53 8.53 0

Stack Exit Temp.
(Kelvin) 335 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 0

Stac k Exit Velocity
(m/s) 17.07 17.07 17.07 17.07 17.07 17.07 17.07 17.07 17.07 17.07 0San Juan Generating Station

BART A ssessment Page 28

T able 19 : CALPUFF Inputs for Unit 4

Model Input Data 2011 Analysis 2013 Analysis

Pre

Consent

Decree Consent

Decree Rotamix

or
SNCR ROFA/

Rotamix ROFA SCR/SNC R Hybrid SCR

with

Sorbent Baseline 4 SCR 4 SNCR 2 SNCR/2

Shutdown

Hourly Heat Input
( MMBtu /hour) 5649 5649 5649 5649 5649 5649 5649 5649 5649 5649 5649

Sulfur Dioxide (SO 2 )
(lb/ MMBtu ) 0.29 0.18 0.18 0.18 0.18 0.18 0.18 0.15 0.15 0.15 0.10

Sulf ur Dioxide (SO 2 )
(lb/hr) 1662.4 1016.8 1016.8 1016.8 1016.8 1016.8 1016.8 847.4 847.4 847.4 564.9

Nitr ogen Oxide
(NOx) (lb/ MMBtu ) 0.42 0.33 0.23 0.2 0.26 0.18 0.07 0.3 0.05 0.23 0.23

Nitrogen Oxide
(NOx) (lb/hr) 2399.6 1864.2 1299.3 1129.8 1468.7 1016.8 395.4 1694.7 282.5 1299.3 1299.3

PM ( lb/ MMBtu ) 0.05 0.015 0.015 0.015 0.015 0.015 0.015 0.034 0.034 0.034 0.034

PM (lb/hr) 282.5 84.7 84.7 84.7 84.7 84.7 84.7 192.07 192.07 192.07 192.07

SO 3 as Sulfuric Acid
(H 2 SO 4 ) (lb/ MMBtu ) 0.013 0.011 0.011 0.011 0.011 0.031 0.004 4.6E

- 05 0.00026 4.6E

- 05 4.6E

- 05

SO 3 as Sulfuric Acid
(H 2 SO 4 ) (a) (lb/hr) 76.2 61.7 61.7 61.7 61.7 174 24.5 0.26 1.47 0.26 0.26

Stac k Conditions

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

Stack Exit Diameter
(meters) 8.534 8.534 8.534 8.534 8.534 8.534 8.534 8.53 8.53 8.53 8.53

Stack Exit
Temp

. (Kelvin) 331 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83 322.83

Stack Exit Velocity
(m/s) 17.4 16.76 16.76 16.76 16.76 16.76 16.76 16.76 16.76 16.76 16.76San Juan Generating Station

BART A ssessment Page 29

Visibility Post

- Processing (CALPOST)

In the 2011 analysis, visibility (or 98 th percentile delta deciview (dv)) was calculated using Method 6 in

CALP OST and Annual Average Natural C onditions, as recommended by the WRAP RMC protocol.

The 2013 analysis used the revised IMPROVE equation (Method 8) and the A nnual Average Natural

Conditions

, as recommended by EPA. The Annual Average Natural Conditions used in the 2011 and 2013 analyses are shown in Table 2 0 . They are specifically for the western half of the United States,

included in Table 2

- 1 of EPA’s Guidance for Estimating Nat ural Visibility Conditions Under Regional
Haze Rule (EPA

- 454/B

- 03

- 005, September 2003)

.

Table 2 0 : Average Annual Natural Background Levels (a)

Component Average Annual Natural Background ( μg/m 3 )

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 of 2011 Analysis

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

was conducted

, with meteorological data for the years 2001

- 2003

, for the following control technologies

for each unit : for NOx, pre

- consent decree

, Consent Decree, SNCR or Rotami x

, ROFA/Rotamix, ROFA

, SCR/SNCR Hybrid (SCR/SNCR Hybrid with Inherent SO 3 Removal), SCR with Sorbent (SCR with

Inherent SO 3 Removal and Sorbent Injection) ; and for PM, pre

- consent decree, Consent Decree, PJFF,

and WESP

. To simplify the quanti ty 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 c onducted , the expected degree of visibility impact for each control technology was determined as the difference between the projected visibility impact after installation of that control and annual average natural visibility conditions

, for each receptor

at each o f the 16 Class I area s . The difference is given as delta

- deciview (delta

- dv).

Visibility Impact of NOx Control Technology

The results of the visibility modeling for Unit 1, Unit 2, Unit 3, and Unit 4 for each of the NOx control technologies are s ummar ized in Figures 4

- 7:

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

.San Juan Generating Station

BART A ssessment Page 30

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

T he 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 d a net improvement of 0.62 dv at

Mesa Verde National Park and a 0.14 dv improvement at San Pedro Parks Wilderness Area

. 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 uni t

- 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.San Juan Generating Station

BART A ssessment Page 31

Figure 4 : Total Amount of the Visibility Impacts at All 16 Class I Areas Using 2001

- 2003 Meteorological Data (facility

- wide impact) (2011 Analysis)San Juan Generating Station

BART A ssessment Page 32

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) (2011 Analysis)San Juan Generating Station

BART A ssessment Page 33

Figure 6 : Visibility Impact at Mesa Verde National Park Using 2001

- 2003 Meteorological Data (facility

wide impact) (2011 Analysis)San Juan Generating Station

BART A ssessment Page 34

Figure 7 : Visibility Impact at Mesa Verde National Park Using 2001

- 2003 Meteorological Data (uni ts 1,
2, 3, and 4) (2011 Analysis)

Updated Visibility Modeling Assessment Submitted April 1, 2013

PNM submitted updated visibility modeling f or SJGS with revised emission estimates for sulfur dioxide
(SO 2 ), sulfuric acid (H 2 SO 4 ), and total particulate matter (TPM). The modeling analysis compared available nitrogen oxide (NOx) control technologies including selective catalytic reduction (SCR),

selective non

- catalytic reduction (SNCR), as well as unit retirements as an alternative operating scenario

that had not previously been analyzed , as described in Table 21 below

. The previously evaluated alternatives (e.g., Consent Decree, ROFA/Rotamix, SCR/SNCR Hybrid, and ROFA) were not further evaluated in the 2013 analysis. The results of the analysis for those alternatives are included in Steps 1 through 5 above. PNM’s update d BART modeling incorporated SJGS’s new SO 2 and total particulate matter (TPM) emission rates of 0.15 lb/MMBtu and 0.034 lb/MMBtu, respectively, from the current NSRSan Juan Generating Station

BART A ssessment Page 35

permit effective August 31, 2012. These emission limits have been incorporated into the Baseline modeling sc enario, including the EPA’s FIP scenario representing four SCRs, and the NM ED’s 2011 SI P scenario representing four SNCRs. The updated BART modeli ng also incorporated H 2 SO 4 emission rates

of 0.00026 lb/MMBtu and 0.000046 lb/MMBtu for SCR and non

- SCR, respectively, for th e scenarios

detailed in Table 2 1

.

PNM utilized the EPA

- approved CALPUFF version 5.8, the CALMET data set originally created by

E PA, and modeling input files as modified by EPA to reflect the source specific parameters for the specific modeling scenarios. The modeled CALPUFF domain, receptors, ozone data, and CALMET data used in this analysis came directly from EPA. Additionally, the surface, upper air, and precipitation stations used to make the CALMET files were also directly delivered from the EPA.

The NMED approved the use of all of the input parameters and data compiled by EPA for the update d modeling analysis. The condensable particulate matter (PM) emission rates us ed in the 2013 modeling were based on the facility’s total particulate matter emission limit as established in the NSR permit effective August 31, 2012. PNM utilized the default ammonia background conc entration of 1 ppb and the revised IMPROVE equation (Method 8) to calculate the 98th percentile delta deciview (dv) from modeled pollutant concentrations.

The meteorology used for the SJGS BART analysis followed EPA’s methodology described in the

Techni cal Support Document (TSD) and included with EPA’s proposed 2011 FIP 7

. The modeling analysis was performed on a year

- by

- year basis for the facility

- wide impact for the four scenarios. Ammonia slip (ammonia that is not fully reacted and is emitted to atmosphere) associated with combustion NOx reduction systems may be higher than 1 ppb. However, ammonia slip was not considered in the modeling analysis . Considering the 1 ppb ammonia background and the reductions in NOx, ammonia slip would have a negligib le impact on visibility from any of the scenarios. EPA had

determined in the FIP that ammonia slip would not significantly impact visibility improvement due to

reductions in NOx and SO 2 anticipated in the 4

- SCR scenario . The CALPUFF system used for the 201 1 modeling and the updated modeling is summarized in Table 12. The emissions and stack parameters for the updated modeling are shown in Tables 16 through 19.San Juan Generating Station

BART A ssessment Page 36

Table 2 1 : Target Emissions for Modeling Scenarios

Scenario Operation and Target Emissions

Basel ine Units 1

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

permitted SO 2 and Total Particulate Matter (TPM) emission rates of 0.15

lb/MMBtu and 0.034 lb/MMBtu, respectively.

Sulfuric Acid (H 2 SO 4 ) 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 SO 2 and TPM

emission rates of 0.15 lb/MMBtu and 0.034 lb/MMBtu, respectively.

Sulfuric Acid (H 2 SO 4 ) 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 SO 2 and TPM

emission rates of 0.15 lb/MMBtu and 0.034 lb/MMBtu, respectively.

Sulfuric Acid ( H 2 SO 4 ) emission rate of 0.000046 lb/MMBtu

2 SNCR/2 Shutdown 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 emissio n rate of 0.034 lb/MMBtu, and a reduced SO 2 emission rate of 0.10

lb/MMBtu.

Sulfuric Acid ( H 2 SO 4 ) emission rate of 0.000046 lb/MMBtu

Discussions and Conclusions

PNM remodeled the visibility impacts of SJGS using the revised emission estimates, the EPA

- approved CALPUFF version 5.8, and the meteorological data provided by EPA as previously discussed. PNM provided NMED with all the modeling results performed on a year

- by

- year basis for the facility

- wide impact for the f our scenarios. NMED explored the modeling results to present the visibility improvement

in two ways: 98 th percentile deciview (dv) at each Clas s I area for the four scenarios and deciview improvement at each Class I area with addition NOx control technolo gies on the existing air pollution

control te chnology

.

CALPOST, the postprocessor for CALPUFF, calculates the maximum visibility impacts of all locations (receptors) in the 16 Class I areas for each day. Each modeled day and location ha s an associated delta

deciview

, which is the difference between deciviews and includes the impact at the SJGS and natural background

, and deciviews of the natura l background alone. From these daily values, the value of the

98 th percentile (approximately equivalent to the 8 th highest day) recommended by the BART guidelines is used for comparing the effects of each scenario in improving visibility. The l ine and symbol graph in Figure 8 shows the 98 th percentile at the 16 Class I areas and the impact of each scenario.

As illustrated in Figure 8 , the EPA FIP and State Alternative Plan reduce visibility impairment more than

the NMED SIP submitted in July 2011 for the three years from 2001 through 2003. Mesa Verde National Park shows the highest 98 th percentile among the 16 Class I areas and is the nearest Class I area

, locatedSan Juan Generating Station

BART A ssessment Page 37

approximately 40 km north of the facility. Grand Canyon National Park shows the lowest 98 th percentile

and is located in the most distant area, located approximately 300 km west of the SJGS. When th e frequency of the occurrence of the peak 98 th percentile is compared to each BART technology scenario, the figure depicts that the State Alternative Plan and the EPA FIP more significantly reduce the peak 98 th

percentiles than the NMED SIP scenario does. The 98 th percentile value of the sixteen Class I areas is added up for each scenario separately for the comparison of a general visibility i mprovement, as shown in Figure 9

.

The days exceeding a 0.5 dv threshold are determined at each Class I area for each BART technology scenario for each of the three years. The average and maximum days exceeding the threshold value are

ca lculated and graphed in Figure 10. Figure 10 shows that the State Alternative Plan and the EPA FIP significantly improve visibilit y as compared to the Baseline and NMED SIP scenarios. The State Alternative Plan closely matches the EPA FIP scenario.

The visibility improvement from additional NOx control technologies beyond th e base case is shown in Figure 11 and Table 22 . The res ults indicate that the State Alternative Plan (2 SNCR/2 Shutdown ) and

the EPA FIP (4 SCR) achieve greater visib ility improvement than projected for the NMED SIP scenario

of 4 SNCR . The State Alternative Plan provides for nearly the same visibility improvement as the EPA FIP in improving visibility

. The largest average difference s in visibility improvement from the 4 SCR
(FIP) and 2 SNCR/2 Shutdown (State Alternative) scenarios a re 0. 28 dv at Mesa Verde National Park,

and 0.16 dv at Canyonlands Nation al Park

.San Juan Generating Station

BART A ssessment Page 38

Figure 8: Visibility Impact of the EPA FIP, NMED SIP, and State Alternative Scenarios (2013

Analysis) *

*EPA FIP = 4 SCR; NMED SIP = 4 SNCR; State Alter. = 2 SNCR/2 ShutdownSan Juan Generating Station

BART A ssessment Page 39

Figure 9: Visibility Impact Results (2013 Analysis) *

*EPA FIP = 4 SCR; NMED SIP = 4 SNCR; State Alternative = 2 SNCR/2 ShutdownSan Juan Generating Station

BART A ssessment Page 40

Figure 10: Average and Maximum Days Compared to 0.5 dv (2013 Analysis) *

*EPA FIP = 4 SCR; NMED SIP = 4 SNCR; State Alter. = 2 SNCR/2 ShutdownSan Juan Generating Station

BART A ssessment Page 41

Figure 11: Visibility Improve ment of the EPA FIP, NMED SIP, and State Alternative Scenario s (2013

Analysis) *

*EPA FIP = 4 SCR; NMED SIP = 4 SNCR; State Alter. = 2 SNCR/2 ShutdownSan Juan Generating Station

BART A ssessment Page 42

Table 22: 2001

- 2003 Average Visibility Improvement for 4 SCR, 4 SNCR and 2 SNCR/2 Shutdown

Scenarios

Class I Area 4 SCR 4 SNCR 2 SNCR / 2

Shutdown Difference Difference 4 SCR

to 2 SNCR / 2

Shutdown 4 SCR to 4

SNCR

Arches 1.06 0.37 0.97 0.69 0.09

Bandelier 0.61 0.23 0.64 0.38

- 0.03

Black Canyon 0.37 0.16 0.41 0.21

- 0.04

Canyonlands 1.54 0.48 1.38 1.06 0.16

Capitol Reef 0.34 0.10 0.42 0.24

- 0.08

Grand Canyon 0.18 0.08 0.25 0.10

- 0.07

Great Sand Dunes 0.73 0.27 0.69 0.46 0.04

La Garita 0.78 0.29 0.73 0.49 0.05

Maroon Bells 0.20 0.07 0.22 0.13

- 0.02

Mesa Verde 2.69 0.55 2.41 2.14 0.28

Pecos 0.70 0.25 0.66 0.45 0.04

Petrified Forest 0.16 0.07 0.25 0.09

- 0.09

San Pedro 1.41 0.49 1.29 0.92 0.12

West Elk 0.45 0.17 0.43 0.28 0.02

Weminuche 1.29 0.41 1.23 0.88 0.06

Wheeler Peak 0.59 0.24 0.58 0.35 0.01

Department Assessment 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 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 by anticipated to result from the us e of such technology.

PM BART Assessment

Based on the 2011 five factor analysis, the Department has determined that BART for Units 1, 2, 3, and 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 , 2, 3 and 4 are equipped with PJFF and are subject to a federally

- enforceable

emission limit of 0.015 lb PM/ MMBtu

.

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

.San Juan Generating Station

BART A ssessment Page 43

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 Me sa Verde. Improvements on a unit

- by

- unit basis at all Class I areas showed very minor improvements, usually less than 0.1 dv.

2011 NOx BART Determination

Based on the five factor analysis, the Department determined in 2011 that

, for the Facility comprising
Units 1, 2, 3, and 4 , BART for NOx is SNCR technology at an emission rate of 0.23 lb/ MMBtu on a 30

- day rolling average . The Department’s determination of BART was based on the following results of the five factor analysis:

1) SNCR te chnology was considered cost

- effect ive at an average cost of $ 3,494 per ton of NOx

removed. SNCR technology will reduce the facility annual NOx emissions by 4,900 tons. (In the updated 2013 analysis, the cost estimate increased to $5,589 per ton. While st ill cost effective, this higher cost makes the State Alternative more attractive

. )

2) The SNCR technology would result in additional energy impacts and non

- air impacts from a new reagent syst em and a reagent storage system. T he Department considered these additional costs in

the review of th e overall cost

- effectiveness of SNCR and found these costs to be reasonable.

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

SNCR technology on Units 1 , 2, 3 and 4 . The Department determined that on a facility

- wide basis the visibility improved by 0.25 dv at San Pedro, 0.22 dv at Mesa Verde, and 0.21 dv at Bandelier.

4) An emission limit of 0.23 lb NOx/M mB tu at each of Units 1 , 2, 3 and 4 equals the EPA’s established presumptive limit for dry

- bottom, wall

- fired boilers burning sub

- bituminous coal.

5) The Department reviewed additional economic information provided by PNM that analyzed the economic impact to ratepayers in New Mexico. The PNM estimates indicate the cost of control technology beyond SNCR would be financially burdensome and cause economic hardship to low

income New Mexicans. According to the US Census Bureau, as of 2009, 18% of New Mexicans were living below the poverty line, as defined by the fe deral poverty standards. PNM estimates a rate increase of $11.50 per year per residential ratepayer from the installation of SNCR versus an estimated rate increase of $82.00 per year from the installation of SCR.

6) The Department has determined that in ligh t of the unreasonable costs of SCR, particularly as reflected in the impact on ratepayers, requiring controls to achieve reductions beyond the most stringent presumptive standard prescribed by the EPA is not justified.San Juan Generating Station

BART A ssessment Page 44

2013 BART Determination

The Depar tment 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 th is 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 SO 2 emission rates at

Units 1 and 4 to 0.10 lb/ MMBtu on a daily rolling 30

- day average basis. These SO 2 emission reductions occur separate ly and apart from the SO 2 backstop trading program that EPA has already approved as satisfying BART. In addition to increased visibility improvement, these SO 2 reductio ns will lead to non

- air quality environmental benefits, such as decreased acid deposition.

3) T he 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 l ess 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 r efined 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 2 3 : 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

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.San Juan Generating Station

BART A ssessment Page 45

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 pollut ant emissions, and acid gas

emissions as detailed i n Table 2 4 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. T he 2 SNCR/2 Shutdown scenario achieves significant visibility improvements as compared to the baseline and installat ion 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. 3 dv impact at

any Class I area ). For the 4 SCR and 2 SNCR/2 Shutdown scenarios, the average difference over three years is 0.28 dv at Mesa Verde and 0.16 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 SCR 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. T he total capital investment of the FIP 4 SCR scenari o 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 e xisting pollution control equipment was evaluated for all 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 relevan ce in selec ting among the control options in this case

.

Weighing all the above considerations as required by CAA § 169A, t he 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 re gulatory requirements of BART.San Juan Generating Station

BART A ssessment Page 46

Tabl e 2 4 : Pollutant Emissions from 2 SNCR/2 Shutdown, 4 S N CR and 4 SCR

Scenario NOx SO 2 PM CO CO 2 VOC Mercury Non

- Hg Acid Gases

Current 21,000 10 ,500 2,380 33,507 14,669,968 210 0.0842 5.4 1,488

2 SNCR/2

Shutdown 8,011 3,483 1,184 18,615 7,314,801 104 0.042 2.7 744

2 SNCR/2

Shutdown %

Reduction 62% 67% 50% 44% 50% 50% 50% 50% 50%

4 SNCR 16,100 10,500 2,380 33,507 14,699,968 210 0.0842 5.4 1,488

4 SNCR

% Reduction 23% 0% 0% 0% 0% 0% 0% 0% 0%

4 SCR 3,502 10,500 2,380 33,507 14,699 ,968 210 0.0842 5.4 1,488

4 SCR

% Reduction 83% 0% 0% 0% 0% 0% 0% 0% 0%

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 (S CR). Retrieved from http://www.epa.gov/ttn/catc/dir1/fscr.pdf

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

Rule

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

7. Technical Support Document; Visibility Modeling for BART Determination: San Juan Generating Station, New Mexico. EPA

- R06

- OAR

- 0846

- 0003