Arizona Regional Haze Technical Support Document – Page 1 of 80 

Arizona Regional Haze 

Technical Support Document 

Prepared and Reviewed by: 

Margaret Alkon, Scott Bohning, Eugene Chen, Francisco Dóñez, Steve Frey, 

Colleen McKaughan, Thomas Webb, Charlotte Withey 

July 2012 

Table of Contents

I. Definitions and Acronyms 2

II. Introduction and Background 4

A. Relationship of this TSD to our Proposal 4

B. Background on Regional Haze and BART Requirements 4

C. Affected Class I Areas 5

III. EPA’s Evaluation of Arizona’s BART Determinations 8

A. Arizona’s Identification of BART Sources 8

1. ADEQ’s Analysis 8

2. EPA’s Evaluation 9

B. Arizona’s BART Control Analysis 9

1. ADEQ’s Analysis 10

2. EPA’s Evaluation 10

C. Arizona’s BART Determinations 12

1. AEPCO Apache Generating Station Unit 1 13

2. Apache Units 2 and 3 18

3. Cholla Units 2, 3 and 4 24

4. Coronado Units 1 and 2 28

D. Enforceability of BART Limits 34

IV. Technical Information for EPA’s Proposed FIP Actions 35

A. EPA’s BART Analysis for NOx 35

1. Cost of Compliance 35

2. Energy and Non-air Environmental Impacts 37

3. Pollution Control Equipment in Use at the Source 38

4. Remaining Useful Life of the Source 38

5. Degree of Improvement in Visibility 38

B. EPA’s BART Determinations45

1. Apache Units 2 and 3 45

2. Cholla Units 2, 3 and 4 53

3. Coronado Units 1 and 2 61

C. Enforceability Requirements 71

V. Appendix A: Listing of Modeling-Related Files 76

VI. Appendix B: Visibility Impact and Benefit Tables 80
Arizona Regional Haze Technical Support Document – Page 2 of 80 

I. Definitions and Acronyms

(1) The words or initials Act or CAA mean or refer to the Clean Air Act, unless the 

context indicates otherwise. 

(2) The initials ADEQ mean or refer to the Arizona Department of Environmental 

Quality. 

(3) The initials AEPCO mean or refer to Arizona Electric Power Cooperative. 

(4) The initials AFUDC mean or refer to allowance for funds used during construction. 

(5) The initials APS mean or refer Arizona Public Service Company. 

(6) The words Arizona and State mean the State of Arizona. 

(7) The initials BART mean or refer to Best Available Retrofit Technology. 

(8) The term Class I area refers to a mandatory Class I Federal area.

1

(9) The initials CBI mean or refer to Confidential Business Information. 

(10) The initials CEMS mean or refer to continuous emission monitoring system. 

(11) The initials COFA mean or refer to close-coupled overfire air. 

(12) The initials CY mean or refer to Calendar Year 

(13) The initials EGU mean or refer to Electric Generating Unit. 

(14) The initials ESPs mean or refer to electrostatic precipitators. 

(15) The words EPA, we, us or our mean or refer to the United States Environmental 

Protection Agency. 

(16) The initials FGD mean or refer to flue gas desulfurization. 

(17) The initials FGR mean or refer to flue gas recirculation. 

(18) The initials FIP mean or refer to Federal Implementation Plan. 

(19) The initials FLMs mean or refer to Federal Land Managers. 

1 Although states and tribes may designate as Class I additional areas which they consider to have visibility as an 

important value, the requirements of the visibility program set forth in section 169A of the CAA apply only to 

“mandatory Class I Federal areas.” 
Arizona Regional Haze Technical Support Document – Page 3 of 80 

(20) The initials IMPROVE mean or refer to Interagency Monitoring of Protected Visual 

Environments monitoring network. 

(21) The initials IPM mean or refer to Integrated Planning Model. 

(22) The initials LNB mean or refer to low-NOx burners. 

(23) The initials LTS mean or refer to Long-Term Strategy. 

(24) The initials MW mean or refer to megawatts. 

(25) The initials NEI mean or refer to National Emission Inventory. 

(26) The initials NH3 mean or refer to ammonia. 

(27) The initials NOx mean or refer to nitrogen oxides. 

(28) The initials NP mean or refer to National Park. 

(29) The initials OC mean or refer to organic carbon. 

(30) The initials OFA mean or refer to over fire air. 

(31) The initials PM mean or refer to particulate matter. 

(32) The initials PM2.5 mean or refer to fine particulate matter with an aerodynamic 

diameter of less than 2.5 micrometers. 

(33) The initials PM10 mean or refer to particulate matter with an aerodynamic diameter of 

less than 10 micrometers (coarse particulate matter). 

(34) The initials PNG mean or refer to pipeline natural gas. 

(35) The initials ppm mean or refer to parts per million. 

(36) The initials PSD mean or refer to Prevention of Significant Deterioration. 

(37) The initials RAVI mean or refer to Reasonably Attributable Visibility Impairment. 

(38) The initials RMC mean or refer to Regional Modeling Center. 

(39) The initials RP mean or refer to Reasonable Progress. 

(40) The initials RPG or RPGs mean or refer to Reasonable Progress Goal(s). 

(41) The initials RPOs mean or refer to regional planning organizations. 

(42) The initials SCR mean or refer to Selective Catalytic Reduction 
Arizona Regional Haze Technical Support Document – Page 4 of 80 

(43) The initials SIP mean or refer to State Implementation Plan. 

(44) The initials SNCR mean or refer to Selective Non-catalytic Reduction 

(45) The initials SO2 mean or refer to sulfur dioxide. 

(46) The initials SOFA mean or refer to separated over fire air. 

(47) The initials SRP mean or refer to Salt River Project Agricultural Improvement and 

Power District. 

(48) The initials tpy mean tons per year. 

(49) The initials TSD mean or refer to Technical Support Document. 

(50) The initials VOC mean or refer to volatile organic compounds. 

(51) The initials WA mean or refer to Wilderness Area. 

(52) The initials WEP mean or refer to Weighted Emissions Potential. 

(53) The initials WFGD mean or refer to wet flue gas desulfurization. 

(54) The initials WRAP mean or refer to the Western Regional Air Partnership. 

II. Introduction and Background

A. Relationship of this TSD to our Proposal

EPA is proposing to partially approve and partially disapprove portions of the Arizona 

Regional Haze State Implementation Plan (SIP) submitted by the Arizona Department of 

Environmental Quality (ADEQ) on February 28, 2011. Specifically, EPA’s proposed action 

pertains to Best Available Retrofit Technology (BART) for three electric generating stations in 

Arizona: Apache Generating Station, Cholla Power Plant and Coronado Generating Station. EPA 

is also proposing a Federal Implementation Plan (FIP) to replace the portions of the SIP it is 

proposing to disapprove. EPA will propose to address other facilities and other elements of the 

Arizona SIP in a later action. 

This technical support document (TSD) is not meant to be a complete rationale for our 

proposed decisions; further discussion is included in the Federal Register notice for this proposed 

action. The TSD provides additional information concerning some of the technical bases for our 

proposed actions; additional information and analysis is contained in the docket. Information in 

this document may suggest we have made a final determination. However, all aspects of our 

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

other information we may receive during our public comment period. 

B. Background on Regional Haze and BART Requirements

Good visibility is important to the enjoyment of national parks and scenic areas. Regional 

haze is air pollution that is transported long distances, causing reduced visibility in national parks 
Arizona Regional Haze Technical Support Document – Page 5 of 80 

and wilderness areas. This haze is composed of small particles that absorb and scatter light, 

affecting the clarity and color of what we see. The pollutants that create this haze are sulfates, 

nitrates, organic carbon, elemental carbon and soil dust. Human-caused (anthropogenic) sources 

include industry, motor vehicles, agricultural and forestry burning, and windblown dust from 

roads and farming practices. 

There are 156 national parks and wilderness areas that have been designated by Congress 

as “mandatory federal Class I areas” (referred to herein as Class I areas). The Clean Air Act 

contains a national goal of reducing man-made visibility impairment in all Class I areas. To meet 

this goal, the Environmental Protection Agency (EPA) adopted the Regional Haze Rules in July 

1999. These rules complement and are in addition to “Phase I” visibility rules adopted by EPA in 

1980. 

Our proposal regarding the Arizona RH SIP contains a general discussion of regional 

haze and EPA’s Regional Haze Rule (RHR), including BART. The RHR provides the following 

six factors that a BART determination must take into account (40 CFR 51.308(e)(1)(ii)(A)): 

· the available technology to control emissions and the technical feasibility of each 

technology; 

· the cost of compliance for the technically feasible control technologies; 

· the energy and non-air quality impacts of the control technologies; 

· any existing air pollution control technologies at the source; 

· the remaining useful life of the source; and 

· the degree of visibility improvement which may reasonably be anticipated to result from 

the various control technologies. 

All but the first of these factors are also expressly required to be taken into account under 

Section 169A(g)(2) of the Clean Air Act (CAA), 42 U.S.C. § 7491(g)(2). Although we list six 

factors, the first factor is not always explicitly stated and the remaining factors are frequently 

referred to as the “five-factor analysis” for the RHR BART determination. 

C. Affected Class I Areas

Arizona has twelve mandatory Class I areas, as shown in Table 1. Figure 1 shows each of 

the three facilities addressed by this proposed action, as well as the Class I areas located within 

300 kilometers (km) of each facility. EPA’s Regional Haze guidance specifies the 300 km 

distance as an acceptable proxy for identifying Class I areas possibly affected by emissions from 

a facility. In addition to the many Class I areas in Arizona affected by these facilities’ emissions, 

there are several Class I areas in other states that potentially affected by these three facilities. 

Apache Generating Station (Apache) is within 300 kilometers of Gila Wilderness Area in New 

Mexico. Cholla Power Plant (Cholla) is within 300 kilometers of Capitol Reef National Park in 

Utah, Mesa Verde National Park in Colorado, and the Gila Wilderness Area in New Mexico. 

Coronado Generating Station (Coronado) is within 300 kilometers of Mesa Verde National Park 

in Colorado and the San Pedro Parks Wilderness Area, the Bandelier Wilderness Area, Bosque 

del Apache Wilderness Area, and the Gila Wilderness Area in New Mexico. 
Arizona Regional Haze Technical Support Document – Page 6 of 80 

Table 1 - Arizona Class I Areas

Class I Area Acreage 

Chiricahua National Monument 11,985 

Chiricahua Wilderness 87,700 

Galiuro Wilderness 76,317 

Grand Canyon National Park 1,218,375 

Mazatzal Wilderness 252,390 

Mount Baldy Wilderness 7,000 

Petrified Forest National Park 93,532 

Pine Mountain Wilderness 20,061 

Saguaro National Park 84,000 

Sierra Ancha Wilderness 20,850 

Superstition Wilderness 160,200 

Sycamore Canyon Wilderness 55,937 
Arizona Regional Haze Technical Support Document – Page 7 of 80 

Figure 1 - Arizona Class I Areas and Initial Proposal BART Facilities 
Arizona Regional Haze Technical Support Document – Page 8 of 80 

III. EPA’s Evaluation of Arizona’s BART Determinations

A. Arizona’s Identification of BART Sources

1. ADEQ’s Analysis

In the first step of the BART process, ADEQ identified all the BART-eligible sources 

within the jurisdiction of the State and local agencies, and applied the three eligibility criteria in 

the RHR (40 CFR 51.301) to these facilities. The criteria are: 1) one or more emission units at 

the facility are classified in one of the 26 industrial source categories listed in the BART 

Guidelines; 2) the emission unit(s) did not operate before August 7, 1962, but was in existence 

on August 7, 1977; and 3) the total potential to emit of any visibility impairing pollutant from the 

subject emission units is greater or equal to 250 tons per year. ADEQ determined that Apache, 

Cholla and Coronado have emissions units that meet these criteria. 

In a second step, ADEQ identified those BART-eligible sources that may reasonably be 

anticipated to cause or contribute to visibility impairment at any Class I area. The BART 

Guidelines allow states to consider exempting some BART-eligible sources from BART review 

in the event that they may not reasonably be anticipated to cause or contribute to any visibility 

impairment in a Class I area. For states using modeling to determine the applicability of BART 

to single sources, the BART Guidelines note that the first step is to set a contribution threshold to 

assess whether the impact of a single source is sufficient to cause or contribute to visibility 

impairment at a Class I area. Further, the BART Guidelines state that, “[a] single source that is 

responsible for a 1.0 deciview change or more should be considered to ‘cause’ visibility 

impairment.”2 The BART Guidelines also state that “the appropriate threshold for determining 

whether a source contributes to visibility impairment’ may reasonably differ across states,” but, 

“[a]s a general matter, any threshold that you use for determining whether a source ‘contributes’ 

to visibility impairment should not be higher than 0.5 deciviews.” For determining whether a 

source is subject to BART, ADEQ used a contribution threshold of 0.50 dv. 

The WRAP’s Regional Modeling Center (RMC) developed a modeling protocol, entitled 

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

the Western United States.”3 The protocol specified the use of CALPUFF version 6.112 and 

CALMET version 6.211, which were the accepted model versions at the time.4 The WRAP RMC 

used this protocol to perform CALPUFF modeling for each of the western states. ADEQ then 

relied on the RMC’s modeling to assess the potential of BART-eligible sources to cause or 

contribute to Class I visibility impairment. The visibility impacts of Apache, Cholla and 

Coronado are each well above the 0.5 dv “contribution” threshold as well as the 1.0 dv 

“causation” threshold.5 As a result, ADEQ determined that emissions units at the Apache, Cholla, 

and Coronado facilities are subject to BART as listed in Table 2. 

2

70 FR 39104, 39161 

3

See Docket Item B-15. 

4

 EPA subsequently required the uses of CALPUFF and CALMET version 5.8 for new modeling applications. 

However, EPA is accepting BART modeling performed according to a previously approved protocol, as was the 

case for the WRAP protocol. 

5

See Docket Item No. B-12. Visibility impacts as listed in “Summary of WRAP RMC BART Modeling for 

Arizona” Draft No. 5, May 7, 2005. Initial draft released on April 4, 2005. 
Arizona Regional Haze Technical Support Document – Page 9 of 80 

Table 2 - Sources Subject to BART

Facility BART Emission 

Units 

Source Category Pollutants 

Evaluated 

WRAP 

Modeled 

Impacta

AEPCO Apache 

Generating Station 

Units 1, 2, and 3 Fossil-fuel fired 

steam electric plants 

of more than 250 

million British 

thermal units per 

hour heat input 

NOx, SO2, PM10 1.95 dv 

APS Cholla Power 

Plant 

Units 2, 3, and 4 NOx, SO2, PM10 2.88 dv 

SRP Coronado 

Generating Station 

Units 1 and 2 NOx, SO2, PM10

3.32 dv 

a Average of the 98th percentile across 2001, 2002 and 2003 for the most affected Class I Area. 

2. EPA’s Evaluation 

We are proposing to approve ADEQ’s determination that Apache, Cholla, and Coronado 

are eligible for and subject to a BART control analysis. Each of the three facilities addressed in 

this notice (Apache, Cholla and Coronado) agreed with ADEQ’s determination that they are 

subject to BART. While we do not agree with all aspects of the process by which ADEQ 

identified its eligible-for-BART and subject-to-BART sources, we do agree with ADEQ that the 

three facilities in this notice are eligible for and subject to BART. Since our action today focuses 

on only the three facilities, we will address ADEQ’s other subject-to-BART determinations in a 

separate action at a later date. 

B. Arizona’s BART Control Analysis

 The third step of the BART evaluation is to perform a five-factor BART analysis as the 

basis for making a BART control determination. In performing this analysis, 40 CFR 

51.308(e)(1)(ii)(A) requires that states consider the following factors on a pollutant-by-pollutant 

basis: (1) The costs of compliance of each technically feasible control technology, (2) the energy 

and non-air quality environmental impacts of compliance of the control technologies, (3) any 

existing pollution control technology in use at the source, (4) the remaining useful life of the 

source, and (5) the degree of improvement in visibility which may reasonably be anticipated to 

result from the use of such technology. These factors are frequently referred to as the “five-factor 

analysis” for the RHR BART determination. 

The BART Guidelines recommend that a BART analysis include the following five steps. 

The Guidelines provide detailed instructions on how to perform each of these steps.6

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,7and 

Step 5—Evaluate Visibility Impacts. 

6

40 CFR Part 51, Appendix Y, § IV.D. 

7

Step 4 includes evaluating the cost of compliance, energy impacts, non-air quality environmental impacts, and 

remaining useful life. 
Arizona Regional Haze Technical Support Document – Page 10 of 80 

1. ADEQ’s Analysis

ADEQ’s BART analyses mostly followed this approach, with the addition of a step to 

identify existing control technologies and a step concluding “selection of BART.”8 Thus, 

ADEQ’s analyses included the following seven steps: 

Step 1: Identify the Existing Control Technologies in Use at the Source 

Step 2: Identify All Available Retrofit Control Options 

Step 3: Eliminate All Technically Infeasible Control Options 

Step 4: Evaluate Control Effectiveness of Remaining Technologies 

Step 5: Evaluate the Energy and Non-Air Quality Environmental Impacts and Document Results9

Step 6: Evaluate Visibility Impacts 

Step 7: Select BART 

2. EPA’s Evaluation

We find that this overall approach to the five-factor analysis is generally reasonable and 

consistent with the RHR and the BART Guidelines. With respect to the three sources covered by 

this action, we find that ADEQ’s implementation of the first four steps of its approach is 

generally reasonable and consistent with the RHR and the BART Guidelines. However, we do 

not agree with ADEQ’s analysis in steps 5 through 7.10 In particular, under step 5, we find that 

the costs of control were not calculated in accordance with the BART Guidelines; under step 6, 

we find that the visibility impacts were not appropriately evaluated and considered; and under 

step 7, we find that ADEQ did not provide a sufficient explanation and rationale for its 

determinations. While we find these problems in all of ADEQ’s BART analyses for the three 

sources, they do not appear to have had a substantive impact on ADEQ’s selection of controls for 

SO2 and PM10. With respect to ADEQ’s NOx BART determinations, however, we find that these 

problems resulted in control determinations that are inconsistent with the RHR and the BART 

Guidelines. We summarize below how ADEQ applied the five factors and identify a number of 

issues common to the three relevant sources.

a) Cost of Compliance

ADEQ included information relating to costs of compliance in its RH SIP, including 

information on total annualized costs, cost per ton of pollutant removed, and incremental cost per 

ton of pollutant removed for the various control options considered. Cost calculations were 

prepared by consulting firms on behalf of the facilities as part of their BART analyses that relied 

on a combination of vendor quotes, facility data, and internal cost calculation methodology. 

These BART analyses were subsequently submitted to ADEQ. Upon review, ADEQ requested 

certain clarifying information from the facilities regarding these cost calculations, including 

greater detail on the underlying assumptions and additional supporting documentation. ADEQ 

received responses of varying detail to these requests, and included this information as part of its 

RH SIP. As described in further detail in the discussion of each facility, there are certain aspects 

8 Arizona Regional Haze SIP, pp. 138-143. 

9 We note that, while ADEQ refers to its Step 5 as an evaluation of energy and non-air quality environmental 

impacts, this step also includes consideration of the costs of compliance and the remaining useful life of the source, 

consistent with the BART Guidelines, 40 CFR Part 51, Appendix Y, § IV.D.4. 

10 We do not believe that ADEQ appropriately used “the most stringent emission control level that the technology is 

capable of achieving” for SCR per the BART Guidelines at 40 CFR Part 51, Appendix Y, § IV.D.3. This issue is 

addressed on a source-by-source basis under the cost and visibility factors of our evaluation in section VI.C. 
Arizona Regional Haze Technical Support Document – Page 11 of 80 

of these cost calculations that we find inconsistent with the BART Guidelines and EPA’s Control 

Cost Manual. We also disagree with the manner in which ADEQ interpreted the cost-related 

information included in its RH SIP. 

b) Energy and Non-air Quality Environmental Impacts

In its BART analyses, ADEQ identified only minor energy and non-air quality impacts 

for SO2 or PM10 control strategies. Regarding NOx emissions, ADEQ’s BART analyses point out 

that the various control options will incur increased energy usage by any electric generating unit 

(EGU) where they are installed. In particular, Selective Catalytic Reduction (SCR) retrofit will 

cause an additional pressure drop in the flue gas system due to the catalyst, increasing power 

requirements. Additionally, ADEQ’s SIP submission asserts that ammonia levels in fly ash due 

to Selective Non-catalytic Reduction (SNCR) and SCR installations could affect the decision of 

facility managers to sell or dispose of fly ash.11 Finally, the Arizona SIP notes that SNCR and 

SCR may involve potential safety hazards associated with the transportation and handling of 

anhydrous ammonia.

12 However, ADEQ did not cite any of these potential energy and non-air 

impacts as the basis for eliminating any otherwise feasible control strategies for NOx. EPA 

concurs that these impacts do not warrant elimination of any of the control options. 

c) Existing Pollution Control Technology

The presence of existing pollution control technology is reflected in the BART analysis 

in two ways: first, in the consideration of available control technologies (step 1 of ADEQ’s 

analysis), and second, in the development of baseline emission rates for use in cost calculations 

and visibility modeling (steps 5 and 6 of ADEQ’s analysis). As described in greater detail in the 

discussion for each facility, AEPCO, APS, and SRP used baseline time periods that varied from 

2001 to 2007. The respective baseline emissions and existing pollution control technology used 

in the BART analyses reflect the levels of control in place at the time. EPA considers ADEQ’s 

approach to be reasonable and generally consistent with the RHR and the BART Guidelines. 

d) Remaining Useful Life of the Source

The remaining useful life of the source is usually considered as a quantitative factor in 

estimating the cost of compliance. With the exception of Apache Generating Station Unit 1, 

ADEQ used the default 20-year amortization period in the EPA Cost Control Manual as the 

remaining useful life of the facilities in its RH SIP. Without commitments for an early shut down 

of an EGU, it is not appropriate to consider a shorter amortization period in a BART analysis. 

e) Degree of Visibility Improvement

ADEQ assessed the degree of improvement in visibility from candidate BART 

technologies using models and procedures generally in accord with EPA guidance. ADEQ relied 

on visibility analysis performed by the facilities, which used the WRAP RMC’s modeling 

protocol. However, ADEQ’s use of the modeling results in making BART decisions is 

problematic in several respects. First, ADEQ appears to have considered the visibility benefit of 

controls at only a single Class I area for each facility, even though there are nine to seventeen 

Class I areas nearby, depending on the facility. Since the facilities’ modeling results indicated 

that controls would contribute to visibility improvement in multiple Class I areas, consideration 

11 Arizona Regional Haze SIP, Appendix D, p. 63. 

12 See, e.g. id. p. 53. 
Arizona Regional Haze Technical Support Document – Page 12 of 80 

of the benefits in additional areas is warranted. Although the RHR and the BART Guidelines do 

not prescribe a particular approach to calculating or considering visibility benefits across 

multiple Class I areas, overlooking significant visibility benefits at additional areas considerably 

understates the overall benefit of controls to improve visibility. A more complete assessment of 

the degree of visibility improvement for candidate BART controls would include consideration 

of the number of areas affected and the degree of visibility improvement expected in all areas. 

One could conduct this type of analysis by summing the benefits over the areas, or by some other 

quantitative or qualitative procedure.13 The procedure followed by ADEQ is not a sufficient basis 

for making BART determinations for sources with substantial benefits across many Class I areas. 

Second, ADEQ appears to have considered benefits from controls on only one emitting 

unit at a time. However, because the plumes from individual units overlap more or less 

completely by the time they reach a Class I area, the visibility benefits from controls on multiple 

units would be approximately additive. This issue of additive unit benefits could be addressed in 

some way without modeling all the units together, but ADEQ does not appear to have done this, 

and therefore underestimated the degree of visibility improvement from controls. 

Finally, the ammonia background concentration assumed for Cholla and Coronado may 

be too low, ranging from 1 ppb to as low as 0.2 ppb. Nitrogen oxides and SO2 emissions affect 

visibility after chemically transforming into particulate ammonium nitrate and ammonium 

sulfate, respectively. This process is limited by the amount of ammonia present, so modeling 

with a low assumed ammonia background may underestimate visibility impacts and thus the 

visibility benefit of controls. Ambient ammonia measurements for use as input to modeling are 

scarce, and measurements that include it in the form of ammonium even scarcer. In the absence 

of compelling ammonia background estimates, EPA guidance recommends the use of a 1 ppb 

ammonia background for areas in the west.14

C. Arizona’s BART Determinations

Our evaluation of ADEQ’s BART determinations is organized by source, unit and 

pollutant with a focus on the cost and visibility factors of the BART analysis. A summary of the 

State’s BART determinations for the three sources is in Table 3. ADEQ’s BART determinations 

for NOx consist of combustion controls, either in the form of low-NOx burners (LNB) with flue 

gas recirculation (FGR), or LNB with overfire air (OFA) or separated overfire air (SOFA). For 

PM10, ADEQ’s BART determinations consist of fuel switching to pipeline natural gas (PNG) for 

Apache Unit 1, and add-on particulate controls such as electrostatic precipitators (ESPs) or fabric 

filters for the remaining units. For SO2, ADEQ’s BART determinations consist of fuel-switching 

to PNG for Apache Unit 1, and wet flue gas desulfurization (FGD) systems that are either 

already in place or planned for the remaining units. 

13 Note that the issue here is not whether an individual in a given time and place would perceive the deciview 

benefits occurring at different Class I areas and under possibly different meteorological conditions. Rather, the issue 

is accounting in some way for the full set of expected visibility benefits. A national program for addressing regional 

haze must inherently address the multiple areas that occur in a region. 

14 Interagency Workgroup On Air Quality Modeling (IWAQM) Phase 2 Summary Report And Recommendations 

For Modeling Long Range Transport Impacts (EPA-454/R-98-019), EPA OAQPS, December 1998, 

http://www.epa.gov/scram001/7thconf/calpuff/phase2.pdf
Arizona Regional Haze Technical Support Document – Page 13 of 80 

Table 3 - Summary of Arizona's BART Determinations

Unit Size 

(MW) 

Fuel NOx PM10 SO2

Control 

Technology 

Emission 

Limit* 

Control 

Technology 

Emission 

Limit* 

Control 

Technology 

Emission 

Limit* 

Apache 1 75 Natural 

Gas 

LNB w/ 

FGR, PNG 

use 

0.056 PNG use 0.0075 PNG use 0.00064 

Apache 2 195 Coal LNB w/ 

OFA 0.31 ESP (upgraded) 0.03 Wet FGD (existing) 0.15 

Apache 3 195 Coal LNB w/ 

OFA 0.31 ESP (upgraded) 0.03 Wet FGD (existing) 0.15 

Cholla 2 305 Coal LNB w/ 

SOFA 0.22 Fabric filter 0.015 Wet FGD (existing) 0.15 

Cholla 3 305 Coal LNB w/ 

SOFA 0.22 Fabric filter (existing) 0.015 Wet FGD (existing) 0.15 

Cholla 4 425 Coal LNB w/ 

SOFA 0.22 Fabric filter 

(existing) 0.015 Wet FGD 

(existing) 0.15 

Coronado 1 411 Coal LNB w/ 

OFA 0.32 Hot-side 

ESP 0.03 

Wet FGD 

(per Consent 

Decree) 

0.08 

Coronado 2 411 Coal LNB w/ 

OFA 0.32 Hot-side 

ESP 0.03 

Wet FGD 

(per Consent 

Decree) 

0.08 

*Emission limits are in lb/MMBtu 

1. AEPCO Apache Generating Station Unit 1

Apache consists of seven EGUs with a total plant-wide generating capacity of 560 

megawatts. Unit 1 is a wall-fired boiler with a net unit output of 85 MW that burns pipelinequality natural gas as its primary fuel, but also has the capability to use No. 2 through No. 6 fuel 

oils. At present, no emissions control equipment is installed on Unit 1. ADEQ’s BART analyses 

for Apache Unit 1 relied largely on data and analyses provided by AEPCO and its contractor. 

These data and analyses are summarized below, along with ADEQ’s determinations for each 

pollutant and EPA’s evaluations of these analyses and determinations. 

a) BART for NOx

(1) ADEQ’s Analysis

Unit 1 currently operates with no NOx controls. In its BART analysis submitted to 

ADEQ, AEPCO developed baseline emissions for multiple fuel-use scenarios including natural 

gas, and No. 2 and No. 6 fuel oil usage. Baseline natural gas emissions were based on the highest 

75 percent load 24-hour NOx emission levels reported in EPA’s Acid Rain Database for 2006. 

Since the only fuel burned in 2006 was natural gas, baseline emissions for No. 2 or No. 6 fuel oil 

usage could not be developed based on data from 2006. As a conservative simplifying 

assumption, baseline No. 2 fuel oil NOx emissions were assumed to be equal to natural gas 
Arizona Regional Haze Technical Support Document – Page 14 of 80 

usage. Baseline emissions for No. 6 fuel oil usage were estimated using AP-42 emission 

factors.15 A summary of baseline emissions for various fuels is provided in Table 4.

Table 4 - Apache Unit 1: Arizona's Baseline Emission Factorsa

Pollutant Natural Gas 

(lb/MMBtu) 

No. 2 Fuel Oil No. 6 Fuel Oil 

NOx 0.147 0.147 0.301 

PM10 0.0075 0.014 0.0737 

SO2 0.00064 0.051 0.906 

a

See Docket Item B-02 (Table 3-1 of AEPCO Apache 1 BART Analysis) 

AEPCO examined multiple control technologies and options for Apache Unit 1, including 

combustion controls, post combustion add-on controls, and fuel-switching. A summary of cost of 

compliance and degree of visibility improvement for these options is in 

Table 5. These cost and visibility improvement values are based on baseline and control 

case emissions corresponding to No. 6 fuel oil usage, which of the three fuels considered is the 

fuel type that generates the greatest NOx emissions.

Table 5 - Apache Unit 1: Arizona's Cost and Visibility Analysis for NOx

In its cost calculations for Apache Unit 1, AEPCO used a capital recovery factor based on 

a 7.10 percent interest rate, and a plant remaining useful life of eight years.16 The plant’s 

remaining useful life was based upon Apache Unit 1 operating until 2021, and an assumed 

15 See Docket Item B-2. Page 2-1 of AEPCO Apache 1 BART Analysis 

16 See Docket Item B-02. Appendix A (Economic Analysis) of AEPCO Apache 1 BART Analysis. 

Control Optionb Emission 

Rate 

(lb/MMBtu) 

Emissions 

Removed 

(tons/yr) 

Annualized 

Cost 

($/year) 

Cost-effectivenessd

($/ton) 

Visibility Improvementc

(dv) 

Average Incremental 

(from 

previous) 

Total (from 

base case) 

Incremental 

(from 

previous) 

Baseline 0.301 -- -- -- -- -- -- 

LNB + FGR 0.15 297 551,982 1,859 -- 0.194 -- 

ROFA 0.16 278 939,093 3,378 -20,374 0.256 0.062 

SNCR with LNB + 

FGR 0.11 376 1,079,389 2,871 1,432 0.24 -0.016 

ROFA w/ Rotamix 0.11 376 1,505,825 4,005 NAa0.24 NAa

SCR with LNB + 

FGR 0.07 455 5,704,798 12,538 53,152 0.409 0.169 

a The previous option, SNCR with LNB + FGR has the same emission rate, making an incremental comparison invalid. 

b

Per ADEQ's and AEPCO's analyses, control options are ranked here by cost, not by emission rate 

c Visibility improvement at Chiricahua Wilderness Area, the Class I area exhibiting the highest impact 

d Cost-effectiveness values obtained from Table 10.3, Appendix D (TSD) of Arizona RH SIP. See Docket Item B-01. 
Arizona Regional Haze Technical Support Document – Page 15 of 80 

BART implementation date of 2013.17 AEPCO eliminated many control options, including SCR, 

based on high cost-effectiveness ($/ton), and primarily examined the LNB w/ FGR and ROFA 

control options. AEPCO noted that LNB with FGR resulted in larger incremental visibility 

improvement than ROFA, and proposed LNB with FGR, burning either natural gas or fuel oil, as 

BART for NOx at Apache Unit 1. 

In order to evaluate AEPCO’s BART analysis, ADEQ requested supporting information 

explaining assumptions used in the economic analysis, baseline emissions, and control 

technology options. Based on this additional information, as well as on AEPCO’s original 

analysis, ADEQ accepted the company’s proposed BART recommendation of LNB with FGR 

for Unit 1, but added a fuel restriction to allow only the use of natural gas. This determination 

corresponds to a BART emission limit for NOx at Apache Unit 1 of 0.056 lb/MMBtu.

18

(2) EPA’s Evaluation

We disagree with multiple aspects of the analysis for Apache Unit 1. We consider the use 

of eight years for the plant’s remaining useful life in the control cost calculations as unjustified in 

the absence of documentation that the unit will shut down in 2021. We also note that control cost 

calculations include costs that are disallowed by EPA’s Control Cost Manual, such as owner’s 

costs and AFUDC. Both of these elements have the effect of inflating cost calculations and thus 

the cost-effectiveness of the various control options considered. In addition, we do not consider 

using identical baseline emissions for No. 2 fuel oil and natural gas appropriate, although this 

likely did not affect either AEPCO’s or ADEQ’s BART determination, which was informed 

primarily by emission estimates based on No. 6 fuel oil, the highest emitting fuel. 

By including a natural gas-only fuel restriction, ADEQ’s BART determination of LNB 

with FGR results in a NOx emissions limit of 0.056 lb/MMBtu, which is more stringent than any 

of the control options that AEPCO and ADEQ considered in conjunction with No. 6 or No. 2 

fuel oil. Neither AEPCO’s nor ADEQ’s analysis, however, included visibility modeling for 

control options on a natural gas-only basis. The absence of such information does not allow us to 

fully evaluate if options more stringent than LNB with FGR are appropriate on a natural gas-only 

basis. Nevertheless, we are proposing to approve ADEQ’s NOx BART determination of LNB 

with FGR (natural gas usage only) with an emission limit of 0.056 lb/MMBtu for Apache Unit 1. 

b) BART for PM10

(1) ADEQ’s Analysis

Apache Unit 1 currently operates with no PM10 controls. In its BART analysis submitted 

to ADEQ, AEPCO developed baseline emissions for multiple fuel use scenarios including 

natural gas, and No. 2 and No. 6 fuel oil usage. Baseline PM10 emissions for all fuels were 

calculated based on AP-42 emission factors.19 A summary of these emissions is in Table 4.

AEPCO examined multiple control options for PM10 at Apache Unit 1, including add-on controls 

and fuel switching. A summary of cost of compliance and degree of visibility improvement for 

17 See Docket Item B-02. Page 2-1 of AEPCO Apache 1 BART Analysis 

18 See Docket Item B-01. Emission rate as specified in Table 10.2, Appendix D (Technical Support Document) of 

Arizona Regional Haze SIP 

19 See Docket Item B-02, Page 2-1 of AEPCO Apache 1 BART Analysis. 
Arizona Regional Haze Technical Support Document – Page 16 of 80 

these options is summarized in Table 6. These cost and visibility improvement values are based 

on baseline and control case emissions corresponding to No. 6 fuel oil usage, which of the three 

fuels considered generates the greatest PM10 emissions. In its BART analysis, AEPCO cited high 

costs of compliance and minimal visibility improvements for the PM10 control options, and 

proposed no PM10 controls as BART for PM10, using either natural gas or No. 2 fuel oil. Based 

on the data and analysis provided by AEPCO, ADEQ determined that BART for PM10 at Apache 

Unit 1 is no additional controls, but also determined that a fuel restriction to allow only the use 

of natural gas was appropriate. This corresponds to a PM10 BART emission limit for Apache 

Unit 1 of 0.0075 lb/MMBtu.

20

Table 6 - Apache Unit 1: Arizona's Cost and Visibility Analysis for PM10

Control Option Emission 

Rate 

(lb/MMBtu) 

Emissions 

Removed 

(tons/yr) 

Annualized 

Cost 

($/year) 

Cost-effectivenessa

($/ton)

Visibility Improvementb

(dv) 

Average Incremental 

(from 

previous) 

Total (from 

base case) 

Incremental 

(from 

previous) 

Baseline 0.0737 -- -- -- -- -- -- 

Fabric Filter 0.015 116 3,615,938 31,172 -- 0.010 -- 

Fuel switch to 

PNG 

0.0075 -- 0 -- -- -- -- 

a Cost-effectiveness values as reported in Table 10.6, Appendix D (TSD) of Arizona RH SIP. See Docket Item B-01. 

b As summarized in Table 5-12, AEPCO Apache 1 BART Analysis. See Docket Item B-02. Visibility improvement at 

Chiricahua Wilderness Area, the Class I area exhibiting the highest impact 

(2) EPA’s Evaluation

ADEQ’s PM10 analysis includes many of the same issues we noted in its NOx analysis, 

including the use of an eight-year plant remaining useful life, and inclusion of costs that are 

disallowed by EPA’s Control Cost Manual. Although we do not agree with elements of ADEQ’s 

PM10 BART analysis for Apache Unit 1, we find that its conclusion is reasonable, given the 

small visibility improvement projected to result from PM10 reductions at this Unit. Thus, we are 

proposing to approve ADEQ’s PM10 BART determination for Apache Unit 1. 

c) BART for SO2

(1) ADEQ’s Analysis

Apache Unit 1 currently operates with no SO2 controls. In its BART analysis submitted 

to ADEQ, AEPCO developed baseline emissions for multiple fuel use scenarios including 

natural gas, and No. 2 and No. 6 fuel oil. Baseline natural gas emissions were based upon the 

highest 75 percent load 24-hour SO2 emission levels reported in EPA’s Acid Rain Database for 

2006. Since the only fuel burned in 2006 was natural gas, baseline emissions for No. 2 or No. 6 

fuel oil usage could not be developed based on data from 2006. Baseline emissions for No. 2 and 

20 See Docket Item B-01. Emission rate as specified in Table 10.5, Appendix D (Technical Support Document) of 

Arizona Regional Haze SIP 
Arizona Regional Haze Technical Support Document – Page 17 of 80 

No. 6 fuel oil usage were estimated using AP-42 emission factors.

21 A summary of these 

emissions is summarized in Table 4. 

AEPCO also examined multiple control options for SO2 on Apache 1, including add-on 

controls and fuel-switching. A summary of cost of compliance and degree of visibility 

improvement for these options is summarized in Table 7. These cost and visibility improvement 

values are from baseline and control case emissions corresponding to No. 6 fuel oil usage, which 

is the fuel type that generates the greatest SO2 emissions. In its BART analysis, AEPCO cited 

high costs of compliance and minimal visibility improvements for the SO2 control options, and 

proposed no additional SO2 controls, using either natural gas or No. 2 fuel oil, as BART for SO2. 

ADEQ determined that BART for SO2 is no additional controls, but added a fuel restriction to 

allow only the use of natural gas. This corresponds to an SO2 BART emission limit for Apache 

Unit 1 of 0.00064 lb/MMBtu. 

22

Table 7 - Apache Unit 1: Arizona's Cost and Visibility Analysis for SO2

Control 

Option 

Emission 

Rate 

(lb/MMBtu) 

Emissions 

Removed 

(tons/yr) 

Annualized 

Cost 

($/year) 

Cost-effectivenessa

($/ton) 

Visibility Improvementb

(dv) 

Average Incremental 

(from 

previous) 

Total (from 

base case) 

Incremental 

(from 

previous) 

Baseline 0.906 -- -- -- -- -- -- 

Fuel switch to 

low-sulfur 

fuel oil 

0.051 -- -- -- -- -- -- 

Spray dryer 

absorber (dry 

FGD)1

0.10 1,587 3,881,706 2,446 -- 0.765 -- 

Fuel switch to 

PNG 

0.00064 -- 0 -- -- -- -- 

a Cost-effectiveness values as reported in Table 10.8, Appendix D (TSD) of Arizona RH SIP. See Docket Item B01. 

b As summarized in Table 5-12, AEPCO Apache 1 BART Analysis. See Docket Item B-02. Visibility improvement 

at Chiricahua Wilderness Area, the Class I area exhibiting the highest impact. 

(2) EPA’s Evaluation 

The SO2 analysis includes many of the same issues we noted in the NOx analysis, 

including the use of an eight-year plant remaining useful life, and inclusion of costs that are 

disallowed by EPA’s Control Cost Manual. ADEQ’s BART determination, requiring the use of 

only natural gas, results in an SO2 emission limit of 0.00064 lb/MMBtu. This emission rate is 

more stringent than any of the control options that ADEQ considered in conjunction with No. 6 

fuel oil. We are proposing to approve ADEQ’s BART determination for SO2 as an emission limit 

of 0.00064 lb/MMBtu at Apache Unit 1. 

21 See Docket Item B-02. Page 2-2 of AEPCO Apache 1 BART Analysis 

22 See Docket Item B-01. Emission rate as specified in Table 10.7, Appendix D (Technical Support Document) of 

Arizona Regional Haze SIP 
Arizona Regional Haze Technical Support Document – Page 18 of 80 

2. Apache Units 2 and 3

Apache Units 2 and 3 are both dry-bottom, Riley Stoker turbo-fired boilers, each with a 

gross unit output of 204 MW. Both units are BART-eligible and are coal-fired boilers operating 

on sub-bituminous coal. Although there are physical differences between the two units, ADEQ 

found that the overall differences are minimal and therefore considered both units together in its 

BART analysis. As with Apache Unit 1, ADEQ’s analysis relied largely on information provided 

by AEPCO and its contractor. This information is summarized below, along with ADEQ’s 

determinations for each pollutant and EPA’s evaluation. 

While the following sections describe both ADEQ’s and EPA’s evaluations based on the 

information in the record, we note that we received additional information from AEPCO on June 

29, 2012, related to the affordability of NOx controls at Apache. AEPCO states that affordability 

is affected by its small size, the low income profiles of AEPCO’s service area, and AEPCO’s 

ability to access financing. While this information came in too late to be evaluated as part of this 

proposed rulemaking, EPA has put the information in the docket and will evaluate it during the 

public comment period.23

a) BART for NOx

(1) ADEQ’s Analysis

AEPCO developed baseline NOx emissions by examining the average NOx emissions 

from 2002 to 2007, a time period in which both units were equipped with OFA as NOx emission 

controls.

24 AEPCO examined several NOx control technologies, including combustion controls 

and add-on post-combustion controls. A summary of Arizona’s costs of compliance and 

visibility impacts associated with these options is presented in Table 8. ADEQ relied on this 

information from the facility to develop its RH SIP.25 Estimates of control technology emission 

rates were developed based on a combination of vendor quotes, contractor information, and 

internal AEPCO information regarding environmental upgrades.26 Annual emission reductions 

were calculated based on the emission rate estimates combined with annual capacity factors as 

specified by AEPCO.27 Control costs were developed based on a combination of vendor quotes 

and contractor information. These cost calculations provided line item summaries of capital costs 

and annual operating costs, but did not include further supporting information such as detailed 

equipment lists, vendor quotes, or the design basis for line item costs. 

23 See Docket Item C-16, Letter from Michelle Freeark ( AEPCO) to Deborah Jordan (EPA), AEPCO’s Comments 

on BART for Apache Generating Station, June 29, 2012. 

24 See Docket Item B-03 and B-04, AEPCO Apache BART Analyses, page 2-2. 

25 See Docket Item B-03 and B-04, AEPCO Apache BART Analyses. This information is also summarized in 

Docket Item B-01, Arizona Regional Haze SIP, Appendix D, Tables 10.10 through 10.13 

26 As listed in Table 3-2, Docket Items B-03 and B-04, AEPCO Apache BART Analyses. 

27 As listed in Table 2-1, Docket Items B-03 and B-04. Annual capacity factors used for each unit are 92% (Apache 

2), and 87% (Apache 3) 
Arizona Regional Haze Technical Support Document – Page 19 of 80 

Table 8 - Apache Units 2 and 3: Arizona's Cost and Visibility Summary

Control Option Emission 

Rate 

(lb/MMBtu) 

Emissions 

Removed 

(tons/yr) 

Annualized 

Cost 

($/year) 

Cost-effectiveness 

($/ton) 

Visibility Improvementa

(deciviews) 

Cost per Total 

Deciview 

Improvement 

($/dv) 

Average Incremental 

(from 

previous) 

Total 

(from 

baseline) 

Incremental 

(from 

previous) 

Apache Unit 2 

OFA (baseline) 0.47 -- -- -- -- -- -- -- 

LNB + OFA 0.31 1,305 $533,000 $408 -- 0.267 -- $1,996,000 

ROFA 0.26 1,710 $1,664,000 $973 $305 0.359 0.092 $4,636,000 

SNCR + LNB + 

OFA 

0.23 1,953 $1,738,000 $890 $1,860 0.416 0.057 $4,532,000 

ROFA w/ Rotamix 0.18 2,358 $2,225,000 $944 $866 0.491 0.075 $4,177,000 

SCR + LNB + OFA 0.07 3,250 $6,102,000 $1,878 $4,346 0.676 0.185 $9,028,000 

Apache Unit 3 

OFA (baseline) 0.43 -- -- -- -- -- -- 

LNB + OFA 0.31 926 $532,808 $575 -- 0.206 -- $2,586,000 

ROFA 0.26 1,312 $1,643,241 $1,252 $322 0.298 0.092 $5,484,000 

SNCR + LNB + 

OFA 

0.23 1,543 $1,717,633 $1,113 $1,920 0.356 0.058 $5,004,000 

ROFA w/ Rotamix 0.18 1,929 $2,181,833 $1,131 $873 0.436 0.080 $4,825,000 

SCR + LNB + OFA 0.07 2,778 $6,062,301 $2,182 $4,571 0.633 0.197 $9,577,000 

a At the Class I area exhibiting the greatest baseline visibility impact, Chiricahua Wilderness Area 
Arizona Regional Haze Technical Support Document – Page 20 of 80 

Regarding visibility impacts, ADEQ relied on visibility modeling submitted by AEPCO 

to evaluate the visibility improvement attributable to each of the NOx control technologies that it 

considered. This visibility modeling was performed using three years of meteorological data 

(2001 to 2003), and was generally performed in accordance with the WRAP modeling protocol. 

The average of the three 98th percentiles from the modeled years 2001 to 2003 was used as the 

visibility metric for each emission scenario and Class I area. For assessing the degree of visibility 

improvement, ADEQ considered only the visibility benefits at the area with the highest base case 

(pre-control) impact: Chiricahua National Monument and Chiricahua Wilderness Area (two 

nearby Class I areas served by one air monitor). For each control, ADEQ listed visibility 

improvement in deciviews, and cost in millions of dollars per deciview improvement.28 Results 

are comparable for both units, with Unit 2 showing somewhat higher visibility benefits and 

somewhat lower cost per improvement than Unit 3. Unit 2 visibility improvements range from 

0.27 dv for LNB to 0.68 dv for SCR, while the costs per deciview range from $2 million for 

LNB to over $9 million for SCR. ADEQ concluded that LNBs with the existing OFA systems 

represent BART for Units 2 and 3, though no explicit reasoning is provided for the selection. 

In making this determination, ADEQ did not provide adequate information regarding its 

rationale or weighing of the five factors. ADEQ stated only that “(A)fter reviewing the 

company’s BART analysis, and based upon the information above, ADEQ has determined that, 

for Units 2 and 3 BART for NOx is new LNBs and the existing OFA system with a NOx

emissions limit of 0.31 lb/MMBtu...” 29

(2) EPA’s Evaluation

We disagree with several aspects of the NOx BART analysis for Apache Units 2 and 3. 

The control cost calculations included line item costs not allowed by the EPA Control Cost 

Manual, such as owner’s costs, surcharge, and AFUDC. Inclusion of these line items has the 

effect of inflating the total cost of compliance and the cost per ton of pollutant reduced. 

Regarding visibility improvement, as shown in Table 8, ADEQ chose LNB as BART, 

which provides the lowest visibility benefit of any of the controls modeled. By contrast, SCR 

would provide an improvement of more than 0.5 dv at a single Class I Area, and a substantial 

incremental benefit relative to the next more stringent control, ROFA-Rotamix. Multiple Class I 

areas have comparable benefits. The visibility benefits are larger than those listed, if both Units 2 

and 3 are considered together. (See Tables 20 and 21 below for EPA’s visibility results.) The 

SCR cost per deciview of improvement is lower than those for Cholla and Coronado, as 

indicated below in their respective sections.

ADEQ provides little explicit reasoning about the visibility basis for the BART selection. 

For example, there is no weighing of visibility benefits and visibility cost-effectiveness for the 

various candidate controls and the various Class I areas. The modeling results show that controls 

more stringent than LNB appear to be needed to give substantial visibility benefits. Visibility 

impacts at eight nearby Class I areas were not considered, and the visibility benefits of 

simultaneous controls on both units were not considered. For these reasons, EPA believes that 

28 Arizona SIP submittal, "Appendix D: Arizona BART – Supplemental Information", p.65. 

29 Docket Item B-01, Arizona Regional Haze SIP, Appendix D, Page 65. 
Arizona Regional Haze Technical Support Document – Page 21 of 80 

ADEQ gave insufficient consideration to the visibility benefits of the various NOx control 

options available at Apache Units 2 and 3. 

In summary, we find that ADEQ has not provided an adequate justification for adopting 

LNB with OFA as the “best” level of control.30 Although ADEQ has developed information 

regarding each of the five factors, there are problems in both its cost and visibility analyses as 

described above. Moreover, ADEQ’s BART analysis does not explain how it weighed these 

factors. For example, ADEQ did not indicate whether or not it considered any cost thresholds to 

be reasonable or expensive in analyzing the costs of compliance for the various control options. 

We note that ADEQ has made similar NOx BART determinations of LNB with OFA at other 

facilities, such as Cholla Power Plant. Although ADEQ’s BART determinations for these other 

facilities implied that cost of compliance was an important consideration, it does not provide a 

rationale for this selection of NOx BART.31 Thus, we are proposing to disapprove ADEQ’s 

BART determination for NOx at Apache Units 2 and 3, since it does not comply with 40 CFR 

51.308(e)(1)(ii)(A). 

b) BART for PM10

(1) ADEQ’s Analysis

The existing PM10 controls on Apache Units 2 and 3 are hot-side Electrostatic 

Precipitators (ESPs).32 AEPCO and ADEQ considered three potential retrofit control options for 

PM10: 

· Performance upgrades to existing hot-side ESP, 

· Replacement of current ESP with a fabric filter, and 

· Installation of a polishing fabric filter after ESP. 

ADEQ found that all of these options are technically feasible and estimated their associated 

emission rates as shown in Table 9. 

Table 9 - Apache Units 2 and 3: Arizona's Controls and Emission Rates for PM10

Control Technology Expected PM10 Emission Rate 

ESP Upgrades 0.03 lb/MMBtu 

Full Size Fabric Filter 0.015 lb/MMBtu 

Polishing Fabric Filter 0.015 lb/MMBtu

ADEQ found that a fabric filter, whether in addition to or as replacement for the ESP, would 

require additional energy, but did not identify any non-air environmental impacts from any of the 

30 See BART Guidelines, § IV.E.2. 

31 We do note, however, that AEPCO does provide some additional analysis on this position in the Apache BART 

analyses it submitted to ADEQ. Aside from stating that it reviewed AEPCO’s analysis, ADEQ did not specifically 

reference or include any aspects of AEPCO’s analysis in the RH SIP. As a result, we are not assuming that ADEQ 

necessarily agrees with AEPCO’s rationale, and have therefore not provided an evaluation of it. 

32 See Appendix D, pages 65-69 for ADEQ’s BART Analysis for PM10 at Apache Units 2 and 3. See AEPCO 

Apache Unit 2 BART Analysis. 
Arizona Regional Haze Technical Support Document – Page 22 of 80 

three options. The cost of compliance and degree of visibility improvement for each of these 

options, as analyzed by ADEQ, are summarized in Table 10 and Table 11. 

Table 10 - Apache Unit 2: Arizona's Control Cost of Visibility Reduction for PM10

Control Deciview 

Reduction 

Total Annualized 

Cost 

(Million $) 

Cost per Deciview 

Reduced 

(Million $/dv) 

Average Cost 

($/ton) 

ESP 

Upgrades 

Unknown Unknown Unknown Unknown 

Polishing 

Fabric Filter 

0.085 $2.217 $26.09 $9,121 

Full Size 

Fabric Filter 

0.085 $2.888 $33.98 $11,880 

Table 11 - Apache Unit 3: Arizona's Control Cost of Visibility Reduction for PM10

Control Deciview 

Reduction 

Total Annualized 

Cost 

(Million $) 

Cost per Deciview 

Reduced 

(Million $/dv) 

Average Cost 

($/ton) 

ESP 

Upgrades 

Unknown Unknown Unknown Unknown 

Polishing 

Fabric Filter 

0.094 $2.192 $23.32 $9,471 

Full Size 

Fabric Filter 

0.094 $2.869 $30.52 $12,390 

Based on its analysis of the five BART factors, as summarized above, ADEQ found 

BART for PM10 is upgrades to the existing ESP and a PM10 emissions limit of 0.03 lb/MMBtu 

for Units 2 and 3. In particular, ADEQ referred to installation of a flue gas conditioning system, 

improvements to the scrubber bypass damper system, and implementation of programming 

optimization measures for ESP automatic voltage controls as potential upgrades. ADEQ also 

noted that “PM10 emissions will be measured by conducting EPA Method 201/202 tests.” 

(2) EPA’s Evaluation

As noted above, AEPCO’s and ADEQ’s control cost calculations include costs that are 

disallowed by EPA’s Control Cost Manual, such as owner’s costs and AFUDC.33 In addition, 

AEPCO’s and ADEQ’s analyses do not demonstrate that all potential upgrades to the existing 

ESP were fully evaluated. Nonetheless, based on the small visibility improvement associated 

with PM10 reductions from these units (e.g., less than 0.1 dv improvement from the most 

stringent technology), we conclude that additional analyses of control options would not result in 

a different BART determination. As a result, we propose to approve ADEQ’s PM10 BART 

determination at Apache Units 2 and 3. 

33 See AEPCO BART Analysis Technical Memorandum dated July 8, 2009, page 12. 
Arizona Regional Haze Technical Support Document – Page 23 of 80 

However, we are seeking comment on whether test methods other than EPA Method 201 

and 20234 (chosen by ADEQ) should be allowed or required for establishing compliance with the 

PM10 limits that we are approving. In particular, as explained below, use of SCR35 at these units 

is expected to result in increased condensable particulate matter in the form of sulfuric acid mist 

(H2SO4). In effect, the emission limit would be more stringent than intended by ADEQ and 

would likely not be achievable in practice. In order to avoid this result, while still assuring proper 

operation of the particulate control devices, we are requesting on comment on whether to allow 

compliance with the PM10 limit to be demonstrated using test methods that do not capture 

condensable particulate matter, namely EPA Methods 1 through 4 and Method 5 or Method 5e.36

Method 201 is very rarely used for testing. The typical method used for filterable PM10 is 

Method 201A, “constant sampling rate procedure,” which is similar to Method 201, but is much 

more practical to perform on a stack. 

c) BART for SO2

(1) ADEQ’s Analysis

Apache Units 2 and 3 currently have wet limestone scrubbers installed for SO2 removal.37

Under the BART Guidelines, a state is not required to evaluate the replacement of the current 

SO2 controls if their removal efficiency is over 50 percent, but should consider cost-effective 

scrubber upgrades designed to improve the system's overall SO2 removal efficiency. Relying 

upon the BART analysis submitted by AEPCO,38 ADEQ found that the following potential 

upgrades to the scrubbers are technically feasible: 

· Elimination of bypass reheat, 

· Installation of liquid distribution rings, 

· Installation of perforated trays, 

· Use of organic acid additives, 

· Improved or upgraded scrubber auxiliary system equipment, and 

· Redesigned spray header or nozzle. 

ADEQ found that any upgrades likely would not increase power consumption, but would 

increase scrubber waste disposal and makeup water requirements, and would reduce the stack 

gas temperature. These three factors are the normal outcome of treating more of the exhaust gas 

and removing more of the SO2 (increased scrubber waste disposal) and should not be given much 

weight in selecting a BART emission limit. ADEQ also noted that AEPCO had already made the 

following upgrades to the scrubbers: elimination of flue gas bypass; splitting the limestone feed 

34 See 40 CFR Part 51 Appendix M. 

35 EPA is proposing SCR as BART for all of the coal-fired units. See Section VII. 

36 See 40 CFR Part 60 Appendix A. 

37 See Arizona Regional Haze SIP, Appendix D, pages 69-71 for ADEQ’s BART Analysis for SO2 at Apache Units 

2 and 3. 

38 See AEPCO Apache Unit 2 BART Analysis 
Arizona Regional Haze Technical Support Document – Page 24 of 80 

to the absorber feed tank and tower sump; upgrade of the mist eliminator system; installation of 

suction screens at pump intakes; automation of pump drain valves, and replacement of scrubber 

packing with perforated stainless steel trays. In addition, AEPCO tried using dibasic acid 

additive, but found that it did not result in significantly higher SO2 removal. ADEQ did not 

evaluate the cost or visibility impacts of any additional upgrades to the scrubbers, but determined 

that BART for SO2 emissions was no new controls and an emission limit of 0.15 lb/MMBtu on a 

30-day rolling average basis. 

(2) EPA’s Evaluation

We are proposing to approve ADEQ’s SO2 BART determination for Apache Units 2 and 

3. Although ADEQ has not demonstrated that it fully considered all cost effective scrubber 

upgrades, as recommended by the BART Guidelines, ADEQ conducted a five-factor BART 

analysis and its final SO2 BART determination for Apache Units 2 and 3 is consistent with the 

presumptive BART limit of 0.15 lb/MMBtu for utility boilers.39 We have no evidence that 

additional analysis would have resulted in a lower emission limit. Therefore, we are proposing to 

approve the SO2 emission limit of 0.15 lb/MMBtu (30-day rolling average) for Apache Units 2 

and 3. 

However, we note that Apache can receive coal from a number of different mines that 

can have differing sulfur content and potential for SO2 emissions.40 Therefore, we are seeking 

comment on whether additional cost-effective scrubber upgrades are available that would 

warrant a lower emission limit. We are also requesting comment on whether requiring 90 percent 

control efficiency in addition to the lb/MMBtu limit would better assure proper operation of the 

upgraded scrubbers when burning some types of low-sulfur western coal. If we receive 

information establishing that a lower limit is achievable or that a control efficiency requirement 

is needed, then we may disapprove the SO2 emissions limit set by ADEQ and promulgate a 

revised limit for one or both of these units. 

3. Cholla Units 2, 3 and 4

Cholla Power Plant consists of four primarily coal-fired electricity generating units with a 

total plant-wide generating capacity of 1,150 megawatts. Unit 1 is a 125 MW tangentially-fired, 

dry-bottom boiler that is not BART-eligible. Units 2, 3 and 4 have capacities of 300 MW, 300 

MW and 425 MW, respectively, and are tangentially-fired, dry-bottom boilers that are each 

BART-eligible. Based on information provided by APS, the Cholla units operate on a blend of 

bituminous and sub-bituminous rank coals from the Lee Ranch and El Segundo mines.

41

a) BART for NOx

(1) ADEQ’s Analysis

APS submitted a BART analysis to ADEQ in January 2008. At the time of submittal, 

Cholla Units 2, 3 and 4 were equipped with close-coupled overfire air (COFA) as NOx controls. 

APS developed baseline NOx emissions by examining the highest 24-hour average emissions 

39 See BART Guidelines § IV.E.4. 

40 See, e.g. Apache Unit 2 BART Analysis, Table 3-1. 

41 A copy of the coal contract, including obligation amounts and coal quality, can be found in Docket Item B-09, 

“Additional APS Cholla BART response”, Appendix B. 
Arizona Regional Haze Technical Support Document – Page 25 of 80 

from 2001 to 2003.42 APS examined several NOx control technologies, including combustion 

controls and add-on post combustion controls. A summary of the costs of compliance and 

visibility impacts associated with these options is presented in Table 12. 

This information is contained in the Cholla BART analyses for each unit, and was relied 

upon by ADEQ in developing its RH SIP.43 Estimates of control technology emission rates were 

developed based on a combination of vendor quotes, contractor information, and internal APS 

information regarding environmental upgrades.

44 Annual emission reductions were calculated 

based upon the emission rate estimates combined with annual capacity factors as reported in 

CAMD data from 2001 to 2006.45 Control costs were also developed based on a combination of 

vendor quotes and contractor information. These cost calculations provided line item summaries 

of capital costs and annual operating costs, but did not provide further supporting information 

such as detailed equipment lists, vendor quotes, or the design basis for line item costs. 

As part of its BART analysis, APS performed visibility modeling in order to evaluate the 

visibility improvement attributable to each of the NOx control technologies that it considered. 

This visibility modeling was performed using three years of meteorological data (2001 to 2003), 

and was generally performed in accordance with the WRAP protocol, with a few exceptions. For 

example, rather than using a constant monthly ammonia background concentration of 1.0 ppb as 

specified in the WRAP protocol, APS used a variable monthly background ammonia 

concentration that varied from 0.2 ppb to 1.0 ppb. 

For assessing the degree of visibility improvement, ADEQ considered only the visibility 

benefits at the area with the highest base case (pre-control) impact, the Petrified Forest National 

Park. For each control, ADEQ listed visibility improvement in deciviews, and visibility costeffectiveness, (Arizona SIP submittal, “Appendix D: Arizona BART – Supplemental 

Information”, p.77) as in the comparable section for Apache. For Unit 2, improvements range 

from 0.19 dv for LNB with SOFA to 0.29 dv for SCR. Costs per deciview range from $3.4 

million for LNB to and $33.5 million for SCR. Benefits for Unit 3 are about 20 percent lower 

(0.13 to 0.23 deciview), and for Unit 4 are about 20 percent higher (0.21 to 0.41 deciview), with 

percent differences increasing with more stringent control. For Unit 3, costs per deciview range 

from $5 million for LNB with SOFA to $41.6 million for SCR (about 30 percent higher than for 

Unit 2). For Unit 4, costs range from $4 million for LNB with SOFA to $32.4 million for SCR 

(about 20 percent higher except that SCR has a slightly lower cost per deciview). 

ADEQ concluded (ibid, p.79) that LNBs with new SOFA systems represent 

BART for all three units, noting that for all scenarios the visibility benefits were less than 0.5 dv. 

ADEQ also stated that SCR, the most expensive option, provides only about 0.1 dv benefit more 

than LNB with SOFA, the least expensive option. This statement appears to apply only to Units 

2 and 3; the comparable benefit for Unit 4 is 0.2 dv. 

42 See Docket Item B-06 through -08, APS Cholla BART Analyses, page 2-2. 

43 See Docket Item B-06 through -08, APS Cholla BART Analyses. This information is also summarized in Docket 

Item B-01, Arizona Regional Haze SIP, Appendix D, Tables 11.3 through 11.5. 

44 As described in Table 3-2, Docket Items B-06 through -08, APS Cholla BART Analyses. 

45 As listed in Table 2-1, Docket Items B-06 through -08. Annual capacity factors used for each unit are 91 percent 

(Cholla 2), 86percent (Cholla 3), and 93 percent (Cholla 4). 
Arizona Regional Haze Technical Support Document – Page 26 of 80 

Table 12 - Cholla Units 2, 3, and 4: Arizona's Cost and Visibility Summary for NOx 

Control Option Emission 

Rate 

(lb/MMBtu) 

Emissions 

Removed 

(tons/yr) 

Annualized 

Cost 

($/year) 

Cost-effectiveness 

($/ton) 

Visibility Improvementa

(deciviews) 

Cost per total 

deciview 

improvement 

($/dv) 

Average Incremental 

(from previous) 

Total (from 

baseline) 

Incremental 

(from 

previous) 

Cholla 2 

COFA (baseline) 0.50 -- -- -- -- -- -- -- 

LNB + SOFA 0.22 3,314 $635,000 $192 -- 0.187 -- $3,400,000 

SNCR + LNB + 

SOFA 0.17 3,900 $2,175,000 $558 $2,628 0.218 0.031 $9,980,000 

ROFA 0.16 4,017 $2,297,000 $572 $1,043 0.232 0.014 $9,900,000 

ROFA w/ Rotamix 0.12 4,485 $3,384,000 $755 $2,323 0.261 0.029 $12,970,000 

SCR + LNB + 

SOFA 0.07 5,071 $9,625,000 $1,898 $10,650 0.287 0.026 $33,540,000 

Cholla 3 

COFA (baseline) 0.41 -- -- -- -- -- -- -- 

LNB + SOFA 0.22 2,096 $635,000 $303 -- 0.13 -- $5,040,000 

SNCR + LNB + 

SOFA 0.17 2,648 $2,157,000 $815 $2,757 0.16 0.038 $13,150,000 

ROFA 0.16 2,758 $2,243,000 $813 $782 0.17 0.005 $13,270,000 

ROFA w/ Rotamix 0.12 3,200 $3,308,000 $1,034 $2,410 0.20 0.029 $16,710,000 

SCR + LNB + 

SOFA 0.07 3,751 $9,569,000 $2,551 $11,363 0.23 0.032 $41,610,000 

Cholla 4 

COFA (baseline) 0.42 -- -- -- -- -- -- 

LNB + SOFA 0.22 3,390 $820,000 $242 -- 0.21 -- $3,960,000 

SNCR + LNB + 

SOFA 0.17 4,259 $2,852,000 $670 $2,338 0.27 0.058 $10,760,000 

ROFA 0.16 4,433 $3,179,000 $717 $1,879 0.28 0.016 $11,310,000 

ROFA w/ Rotamix 0.12 5,129 $4,537,000 $885 $1,951 0.34 0.055 $13,500,000 

SCR + LNB + 

SOFA 0.07 5,998 $13,230,000 $2,206 $10,003 0.41 0.072 $32,430,000 

a At the Class I area exhibiting the greatest baseline visibility impact, Petrified Forest National Park 
Arizona Regional Haze Technical Support Document – Page 27 of 80 

In evaluating APS’ BART analysis, ADEQ requested supporting information explaining 

certain assumptions used in the economic analysis, baseline emissions, and control technology 

options. Based on this additional information as well as APS’ original BART analysis, ADEQ 

determined that LNB with SOFA is BART for NOx at Cholla Units 2, 3 and 4. In making this 

determination, ADEQ relied almost exclusively on the degree of visibility improvement. ADEQ 

cited small visibility improvement on a per-unit basis, stating that “the change in deciviews 

between the least expensive and most expensive NOx control technologies [...] is only 0.104 

deciviews.”46 ADEQ’s determination suggests that total capital costs may have been a 

consideration, although it is not clear to what extent this may have informed ADEQ’s decision 

making, with the RH SIP simply stating, “[t]he corresponding capital costs are $5.4 million for 

LNB/SOFA and $82.8 million for SCR with LNB/SOFA.”47

(2) EPA’s Evaluation

We disagree with several aspects of the analyses performed for Cholla Units 2 3 and 4. 

Regarding the control cost calculations, we note that certain line item costs not allowed by the 

EPA Control Cost Manual were included, such as owner’s costs, surcharge, and AFUDC. 

Inclusion of these line items has the effect of inflating the total cost of compliance and the cost 

per ton of pollutant reduced. As a result, we are proposing to find that ADEQ did not follow the 

requirements of section 51.308(e)(1)(ii)(A) by not properly considering the costs of compliance 

for each control option. 

Regarding ADEQ’s analysis of visibility impacts, the modeling procedures relied on by 

ADEQ for assessing the visibility impacts from Cholla were generally in accord with EPA 

guidance, but the use of the modeling results in evaluating the BART visibility factor was 

problematic. As was the case for Apache, ADEQ appears to have considered benefits from 

controls on only one emitting unit at a time. EPA believes that ADEQ's use of this procedure 

substantially underestimates the degree of visibility improvement from controls. ADEQ also 

overlooked comparable benefits at seven Class I areas besides Petrified Forest, thereby 

understating the full visibility benefits of the candidate controls. Using the default 1 ppb 

ammonia background concentration would also have increased estimated impacts and control 

benefits. For these reasons, EPA proposes to find that the ADEQ selection of LNB for Cholla 

under the degree of visibility improvement BART factor is not adequately supported, and that 

more stringent control may be warranted. 

b) BART for PM10

(1) ADEQ’s Analysis

As of May 2009, Cholla Units 3 and 4 were both equipped with fabric filters for PM10

control, while Cholla Unit 2 was equipped with a mechanical dust collector and a venturi 

scrubber.48 In its BART analysis, ADEQ noted that the facility had committed to install a fabric 

filter at Unit 2 by 2015. Because fabric filters are the most stringent control available for 

reducing PM10 emissions, ADEQ did not conduct a full BART analysis, but concluded that fabric 

filters and an emission limit of 0.015 lb/MMBtu are BART for control of PM10 at Units 2, 3 and 

46 Docket Item B-01, Arizona Regional Haze SIP, Appendix D, Page 79. 

47 Id. 

48 See Arizona Regional Haze SIP, Appendix D, pages 79-81 for ADEQ’s BART Analysis for PM10 at Cholla Units 

2, 3 and 4. 
Arizona Regional Haze Technical Support Document – Page 28 of 80 

4. ADEQ also noted that “PM10 emissions will be measured by conducting EPA Method 201/202 

tests.” 

(2) EPA’s Evaluation

Given that ADEQ has chosen the most stringent control technology available and set an 

emissions limit consistent with other units employing this technology, we are proposing to 

approve this BART determination of an emission limit of 0.015 lb/MMBtu for PM10 at Cholla 

Units 2, 3 and 4. 

c) BART for SO2

Cholla Units 2, 3 and 4 are all equipped with wet lime scrubbers for SO2 control. 

49

Specifically, Unit 2 is equipped with four venturi flooded disc scrubbers/absorber with lime 

reagent, capable of achieving 0.14 lb/MMBtu to 0.25 lb/MMBtu of SO2. Units 3 and 4 were 

retrofitted in 2009 and 2008, respectively, with scrubbers capable of achieving 0.15 lb/MMBtu 

of SO2.

(1) ADEQ’s Analysis

Based on a limited five-factor analysis, ADEQ determined BART for SO2 at Cholla Unit 

2 is upgrades to the existing scrubber that would achieve a limit of 0.15 lb/MMBtu. Because the 

BART analysis submitted by APS was conducted prior to installation of the scrubbers on Units 3 

and 4, it included an analysis of other potential control technologies, namely, dry flue gas 

desulfurization and dry sodium sorbent injection. However, APS had already installed the wet 

lime scrubbers by the time ADEQ conducted its own BART analysis. Therefore, ADEQ did not 

consider SO2 controls other than wet lime scrubbers for Units 3 and 4, but determined BART as 

use of these scrubbers with an associated emission limit of 0.15 lb/MMBtu of SO2. 

(2) EPA’s Evaluation

We are proposing to approve ADEQ’s BART determination for SO2 at Cholla Units 2, 3 

and 4. Although ADEQ did not fully consider all cost-effective scrubber upgrades as 

recommended by the BART Guidelines, we have no basis for concluding that additional analysis 

would have resulted in a lower emission limit. Therefore, we are proposing to approve the SO2

emission limit of 0.15 lb/MMBtu (30-day rolling average) for Cholla Units 2, 3 and 4. However, 

we are seeking comment on whether additional cost-effective scrubber upgrades are available 

that would warrant a lower emission limit. If we receive comments establishing that a lower limit 

is achievable, then we may disapprove the SO2 emissions limit set by ADEQ and promulgate a 

revised limit for one or more of these units. 

4. Coronado Units 1 and 2

Coronado Generating Station consists of two EGUs with a total plant-wide generating 

capacity of over 800 MW. Units 1 and 2 are both dry-bottom, turbo-fired boilers, each with a 

gross unit output of 411 MW. Both units are BART-eligible and are coal-fired boilers operating 

on primarily Powder River Basin sub-bituminous coal. 

49 See Arizona Regional Haze SIP, Appendix D, pp. 81-83, for ADEQ’s BART Analysis for SO2 at Cholla Units 2, 

3 and 4. 
Arizona Regional Haze Technical Support Document – Page 29 of 80 

SRP entered into a consent decree with EPA in 2008.50 This consent decree resolved 

alleged violations of the CAA which occurred at Units 1 and 2 of the Coronado Generating 

Station, arising from the construction of modifications without obtaining appropriate permits 

under the Prevention of Significant Deterioration (PSD) provisions of the CAA, and without 

installing and applying best available control technology. The consent decree resolved the claims 

alleged by EPA in exchange for SRP’s payment of a civil penalty and SRP’s commitment to 

perform injunctive relief including: 1) installation of pollution control technology to control 

emissions of NOx, SO2, and PM --including flue gas desulfurization devices to control SO2 on 

Units 1 and 2 at the Coronado Station and installation of SCR to control NOx on one of the units 

(Unit 2); 2) meet specified emission rates or removal efficiencies for NOx, SO2, and PM; 3) 

comply with a plant-wide emissions cap for NOx; and 4) perform $ 4 million worth of mitigation 

projects. The consent decree is not a permit, and compliance with the consent decree does not 

guarantee compliance with all applicable federal, state, or local laws or regulations. The emission 

rates and removal efficiencies set forth in the consent decree do not relieve SRP from any 

obligation to comply with other state and federal requirements under the CAA, including SRP’s 

obligation to satisfy any State modeling requirements set forth in the Arizona SIP. 

a) BART for NOx

(1) ADEQ’s Analysis

ADEQ’s BART analysis relied in large part on an analysis submitted by SRP in February 

2008. In its analysis, SRP developed baseline NOx emissions by examining continuous emission 

monitoring system (CEMS) data from 2001 to 2003.51 SRP examined several NOx control 

technologies, including combustion controls and add-on post combustion controls. A summary 

of the costs of compliance and visibility impacts associated with these options is presented in 

Table 13. This information was contained in the SRP Coronado BART analysis, and was relied 

on by ADEQ in developing its RH SIP. Estimates of control technology emission rates were 

developed based on information provided by equipment vendors.52 SRP’s analysis did not 

provide an estimate of annual emissions. 

50 See Docket Item G-01, Consent Decree between United States and Salt River Project Agricultural Improvement 

and Power District. 

51 See Docket Item B-10, SRP Coronado BART Analysis, page 3-1. 

52 See Docket Item B-10, SRP Coronado BART Analysis, p 4-5. 
Arizona Regional Haze Technical Support Document – Page 30 of 80 

Table 13 - Coronado Units 1 and 2: Arizona's Cost and Visibility Summary for NOx

Control 

Option 

Emission Rate 

(lb/MMBtu) Total 

Emissions 

Removeda 

(tons/yr) 

Total 

Annualized 

Cost 

($/year) 

Cost-effectivenessb 

($/ton) 

Visibility Improvementc

(deciviews) 

Cost per total 

deciview 

improvementd 

($/dv) 

Improvement in 

Visibility Indexe 

(deciviews) 

Unit 1 Unit 2 Average Incremental 

(from 

previous) 

Total 

(from 

baseline) 

Incremental 

(from 

previous) 

Total 

(from 

base 

case) 

Incremental 

(from 

previous) 

OFA 

(baseline) 0.433 0.466 -- -- -- -- -- -- -- -- -- 

Full 

LNB+OFA 0.32 0.32 5,838 $1,227,000 $210 -- 0.12 -- $10,225,000 

0.11 -- 

Full 

SNCR+LNB

+OFA 

0.22 0.22 10,195 $4,654,000 $456 $787 0.16 0.04 $29,087,500 0.19 0.080 

Partial 

SCR+LNB+

OFAf

0.32 0.08 11,003 $8,557,000 $778 $4,830 0.24 0.12 $35,654,167 0.22 0.030 

Full 

SCR+LNB+

SOFA 

0.08 0.08 16,730 $17,090,000 $1,022 $1,490 0.39 0.27 $43,820,513 0.34 0.120 

a

SRP did not provide estimates of annual emissions in its BART analysis. These values are summarized from the Arizona RH SIP. 

b Cost-effectiveness was not presented in the Arizona RH SIP. These values are calculated from the emission removal and annualized costs that were 

included in the RH SIP. 

c Visibility improvement at the Class I area exhibiting the greatest baseline visibility impact, Petrified Forest National Park, from the SRP Coronado 

BART Analysis. 

d Cost per total deciview improvement was not presented in the Arizona RH SIP. These values are calculated from the annualized costs that were 

included in the RH SIP, and the visibility improvement at Petrified Forest National Park, from the SRP Coronado BART Analysis. 

e Visibility index used in the Arizona RH SIP is the average of the impacts over the nine closest Class I areas. 

f This control option examined LNB+OFA on Unit 1 and SCR on Unit 2.
Arizona Regional Haze Technical Support Document – Page 31 of 80 

Control costs for the various options considered were developed by Sargent and Lundy, 

the engineering firm retained by SRP for emission control projects at Coronado. In its BART 

analysis and subsequent additional response to ADEQ, SRP provided summaries of total control 

costs, such as total annual operating and maintenance costs and total annualized capital cost, but 

did not provide cost information at a level of detail that included line item costs. 53

As part of its BART analysis, SRP performed visibility modeling in order to evaluate the 

visibility improvement attributable to each of the NOx control technologies that it considered. 

This visibility modeling was performed using three years of meteorological data (2001 to 2003), 

and relied partially on the WRAP protocol with certain revisions based on EPA and Federal 

Land Manager guidance that became available in the intervening period. For example, the 

WRAP protocol used CALPUFF model version 6, whereas SRP used the current EPA-approved 

CALPUFF version 5.8. 

For assessing the degree of visibility improvement, ADEQ considered a visibility index, 

defined as the average of the visibility benefits at the closest nine Class I areas. The average 

included the five areas with the highest baseline impacts. This metric is unlike that used for 

Apache and Cholla, for which the benefits at the single area with maximum baseline impact were 

used. Since it is an average, it is somewhat similar to the sum of benefits over the nine areas, a 

cumulative metric used in other analyses, except it is divided by nine to compute the average. 

(Typically the sum would be computed over all 17 Class I areas impacted by the Coronado 

facility.) For each control, ADEQ listed the average visibility improvement in deciviews, and 

cost in millions of dollars per average deciview improvement.54 Improvements in the visibility 

index ranged from 0.11 dv for LNB with OFA to 0.34 dv for SCR. Costs per deciview for the 

index ranged from $11.1 million for LNB with OFA to $50.3 million for SCR. (These values are 

not shown in Table 13 above nor in the plan submittal. For LNB, $1,227,000 / 0.11 dv = $11.1 

million/dv; for SCR, $17,090,000 / 0.34 dv = $50.3 million/dv.) 

While an average of the visibility benefits over the nearest areas is an informative 

number, it is not directly comparable to the more typical metrics of the maximum benefit seen at 

any area, and sum over the areas. Moreover, neither the ADEQ RH SIP nor the facility’s report 

(BART Analysis for the Coronado Generating Station Units 1 & 2, Document No. 05830-012-

200, ENSR Corporation, February 2008) include control benefits for individual Class I areas. 

Thus, the maximum area benefit cannot be read from either document. However, the benefits can 

be computed from the individual area impacts that are provided in SRP’s report, including for 

Petrified Forest National Park, which had the highest baseline impact. Figures that are 

comparable to those for Apache and Cholla are included in Table 13. Coronado’s maximum area 

visibility benefits range from 0.12 dv for LNB to 0.39 dv for SCR. The costs per deciview range 

from $10.2 million for LNB with OFA to $43.8 for SCR. 

In evaluating SRP’s BART analysis, ADEQ requested additional supporting information 

from SRP regarding control cost calculations, and for further explanation regarding SRP’s 

recommendation for BART for NOx. In developing its Regional Haze SIP, ADEQ determined 

that LNB with OFA constitutes BART for NOx at Coronado Units 1 and 2. In making this 

53 See Docket Item B-11, Additional SRP Coronado response 

54 Arizona RH SIP, Appendix D, p.112. 
Arizona Regional Haze Technical Support Document – Page 32 of 80 

determination, ADEQ did not provide adequate information regarding its rationale or weighing 

of the five factors, stating only “[a]fter reviewing the BART analysis provided by the company, 

and based upon the information above, ADEQ has determined that BART for NOx at Coronado 

Units 1 and 2 is advanced combustion controls (Low NOx burners with OFA) with an associated 

NOx emission rate of 0.32 lb/MMBtu [..]” 55

(2) EPA’s Evaluation

We disagree with several aspects of the BART analysis for Coronado Units 1 and 2. 

Regarding the control cost calculations, we note that SRP did not provide ADEQ with control 

cost calculations at a level of detail that allowed for a comprehensive review. Without such a 

level of review, we do not believe that ADEQ was able to evaluate whether SRP’s control costs 

were reasonable. As a result, we are proposing to find that ADEQ did not follow the 

requirements of section 51.308(e)(1)(ii)(A) because ADEQ did not properly consider the costs of 

compliance for each control option. 

The modeling procedures relied on by ADEQ for assessing the visibility impacts from 

Coronado were generally in accord with EPA guidance. Coronado Units 1 and 2 were modeled 

together, and the modeling was done with the current regulatory version 5.8 of the CALPUFF 

modeling system.56 However, the use of the modeling results in evaluating the BART visibility 

factor was problematic. The modeling results show that, of the controls considered, only SCR 

would provide substantial visibility benefits; the other controls options would provide roughly 

half the 0.5 dv contribution benchmark. ADEQ did not consider the typical visibility metrics of 

benefit at the area with maximum impact, nor benefits summed over the areas. Using the default 

1 ppb ammonia background concentration would also have increased estimated impacts and 

control benefits. For these reasons, EPA proposes to find that the ADEQ selection of LNB with 

OFA for Coronado under the degree of visibility improvement BART factor is not adequately 

supported, and that more stringent control may be warranted. ADEQ provided little reasoning 

about the visibility basis for the Coronado BART selection. For example, there is no weighing of 

the visibility benefits and visibility cost-effectiveness for the various candidate controls and the 

various Class I areas. 

In addition to the problems noted above, we find that overall ADEQ has not documented 

its evaluation of the results of its five-factor analysis, as required by 51.308(e)(1)(ii)(A) and the 

BART Guidelines. Although ADEQ has developed information regarding each of the five 

factors, its selection of BART does not cite or interpret information from its analyses. ADEQ 

does not, for example, indicate whether or not it considered any cost thresholds to be reasonable 

or expensive in analyzing the costs of compliance for the various control options. We note that 

ADEQ has made similar NOx BART determinations of LNB with OFA at other facilities, such as 

Cholla Power Plant. Although ADEQ’s BART determinations for these other facilities implied 

that cost of compliance was an important consideration, it does not provide a rationale for the 

determination of NOx BART at Coronado.57 Therefore, we propose to determine that ADEQ did 

55 Docket Item B-01, Arizona Regional Haze SIP, Appendix D, Page 112. 

56 Arizona Regional Haze SIP, Appendix D, p. 112. 

57 We do note, however, that SRP does provide some additional analysis on this position in the BART analysis it 

submitted to ADEQ and in the responses it provided to ADEQ’s additional questions. Aside from stating that it 

reviewed SRP’s analysis, ADEQ did not specifically reference or include any aspects of SRP’s analysis in the RH 
Arizona Regional Haze Technical Support Document – Page 33 of 80 

not follow the requirements of section 51.308(e)(1)(ii)(A). We propose to disapprove ADEQ’s 

selection of LNB with OFA as BART for NOx at Coronado Units 1 and 2. 

b) BART for PM10

Emissions of PM10 from Coronado Units 1 and 2 are currently controlled by hot-side 

ESPs.58 Under the terms of the Consent Decree described above, SRP is required to optimize its 

ESPs to achieve a PM10 emission rate of 0.030 lb/MMBtu.

59

(1) ADEQ’s Analysis

ADEQ conducted a streamlined PM10 BART analysis for Coronado Units 1 and 2. In 

particular, ADEQ found that “BART for similar emissions units with similar emissions controls 

was determined to be 0.03 lb/MMBtu.” ADEQ concluded that because Coronado Units 1 and 2 

are already meeting a limit of 0.03 lb/MMBtu, “further analysis was determined to be 

unnecessary.” 

EPA’s Evaluation: ADEQ’s analysis does not demonstrate that all potential upgrades to 

the existing ESPs were fully evaluated. However, we have no evidence that additional reductions 

in PM10 emissions would be achievable or cost-effective, or that such reductions would yield 

substantial visibility benefits. Therefore, we propose to approve ADEQ’s PM10 BART 

determination at Coronado. However, we are seeking comment on whether additional costeffective upgrades to the existing ESPs are available that would warrant a lower emission limit. 

If we receive comments establishing that a lower limit is achievable, then we may disapprove the 

PM10 emissions limit set by ADEQ and promulgate a revised limit for one or both of these units. 

Finally, we are seeking comment on whether test methods other than EPA Method 201 

and 20260 (chosen by ADEQ) should be allowed or required for establishing compliance with the 

PM10 limits that we are approving. In particular, as explained below, use of SCR at these units is 

expected to result in increased condensable particulate matter in the form of H2SO4. In effect, the 

emission limit would be more stringent than intended by ADEQ and would likely not be 

achievable in practice. In order to avoid this result, while still assuring proper operation of the 

particulate control devices, we are requesting on comment on whether to allow compliance with 

the PM10 limit to be demonstrated using test methods that do not capture condensable particulate 

matter, namely EPA Methods 1 through 4 and Method 5 or Method 5e.61 Method 201 is very 

rarely used for testing. The typical method used for filterable PM10 is Method 201A, “constant 

sampling rate procedure,” which is similar to Method 201, but is much more practical to perform 

on a stack. 

SIP. As a result, we are not assuming that ADEQ necessarily agrees with SRP’s rationale, and have therefore not 

provided an analysis of it. 

58 See Arizona Regional Haze SIP, Appendix D, p. 112 for ADEQ’s BART Analysis for PM10 at Coronado Units 1 

and 2; and BART Analysis for Coronado Generating Station Units 1 and 2 (February 2008) for SRP’s analysis. 

59 Docket Item G-01, Consent Decree between United States and Salt River Project Agricultural Improvement and 

Power District, § V. 

60 See 40 CFR Part 51 Appendix M. 

61 See 40 CFR Part 60 Appendix A. 
Arizona Regional Haze Technical Support Document – Page 34 of 80 

c) BART for SO2

Emissions of SO2 at Coronado Units 1 and 2 are currently controlled with the use of lowsulfur coal and partial wet flue gas.62 However, the consent decree between EPA and SRP 

described above requires installation of wet flue gas desulfurization (WFGD) systems at either 

Unit 1 or Unit 2 by January 2012, and at the remaining unit by January 1, 2013. Both units must 

achieve and maintain a 30-day rolling average SO2 removal efficiency of at least 95.0 percent or 

a 30-day rolling average SO2 emissions rate of no greater than 0.080 lb/MMBtu. 

(1) ADEQ’s Analysis

Because WFGD is the most effective control technology available for controlling SO2 

emissions, ADEQ did not evaluate other control options. Table 14 summarizes Arizona’s 

assessment of the compliance costs and visibility improvements expected to result from 

installation of WFGD at both units. Based on this information, ADEQ determined SO2 BART for 

both units is the installation of WFGDs and an emission rate of 0.08 lbs/MMBtu on 30-day 

rolling average basis. 

Table 14 - Coronado Units 1 and 2: Arizona's BART Summary for SO2

Option 1, Baseline Option 2, WFGD 

Reduction in Emission 

(tpy) - 25,753 

Annualized Cost - $44,353,330 

Visibility Index (dv) 2.66 1.28 

Improvement in 

Visibility Index (dv) - 1.38 

Incremental Costeffectiveness ($ per dv) - $32,140,094 

(2) EPA’s Evaluation

We are proposing to approve ADEQ’s SO2 BART determination for Coronado Units 1 

and 2. Although we do not necessarily agree with the underlying cost and visibility analyses 

performed by SRP, we have no evidence that additional analysis would have resulted in a lower 

emission limit. Therefore, we propose to approve ADEQ’s SO2 emission limit of 0.08 lb/MMBtu 

(30-day rolling average) for Coronado Units 1 and 2. However, we are seeking comment on 

whether a lower emission limit may be achievable when the units are burning a lower-sulfur 

coal. If we receive comments establishing that a lower limit is achievable, then we may 

disapprove the SO2 emissions limit set by ADEQ and promulgate a revised limit for one or both 

of these units. 

D. Enforceability of BART Limits

Regional Haze SIPs must include requirements to ensure that BART emission limits are 

enforceable. In particular, the RHR requires inclusion of (1) a schedule for compliance with 

BART for each source subject to BART; (2) a requirement for each BART source to maintain 

62 See Arizona Regional Haze SIP, Appendix D, pp. 113-15 for ADEQ’s BART Analysis for PM10 at Coronado 

Units 1 and 2; and Docket No. B.10, BART Analysis for Coronado Generating Station Units 1 and 2 (Feb. 2008) for 

SRP’s analysis. 
Arizona Regional Haze Technical Support Document – Page 35 of 80 

the relevant control equipment; and (3) procedures to ensure control equipment is properly 

operated and maintained.63 General SIP requirements also mandate that the SIP include all 

regulatory requirements related to monitoring, recordkeeping and reporting for the BART 

emissions limitations.64 ADEQ did not include any of these elements in its Regional Haze SIP.65

Therefore, we are proposing to disapprove this aspect of the Regional Haze SIP for these three 

sources and to promulgate a FIP to ensure the emission limits are enforceable. 

IV. Technical Information for EPA’s Proposed FIP Actions

A. EPA’s BART Analysis for NOx

EPA conducted a new five-factor BART analysis for NOx at each of the three facilities in 

order to evaluate Arizona’s RH SIP, and to document the technical basis for proposing BART 

determinations in our FIP. Because EPA generally concurs with ADEQ’s BART analyses in 

Steps 1 and 2 (Identify All Available Retrofit Control Technologies and Eliminate Technically 

Infeasible Options), we focused our technical analysis on Steps 3, 4 and 5 (Evaluate Control 

Effectiveness of Remaining Control Technologies, Evaluate Impacts and Document Results, and 

Evaluate Visibility Impacts). We relied on contractor assistance from the University of North 

Carolina Institute for the Environment to evaluate control effectiveness, perform cost 

calculations, and conduct new visibility modeling for each of the units at the three facilities, 

except Apache Generating Station Unit 1 for which this level of analysis was unnecessary. Our 

approach to each of these factors is explained below, followed by our BART determinations for 

the three sources in the next section. 

1. Cost of Compliance

Cost Estimates and Calculations: In estimating the costs of compliance, we have relied 

on facility data from a number of sources including ADEQ, the Energy Information 

Administration (EIA), and EPA’s Control Cost Manual. As discussed previously, ADEQ, in 

developing its RH SIP, requested certain clarifying information from the facilities regarding their 

control cost calculations, including greater detail regarding the underlying assumptions. ADEQ 

received responses of varying detail to these requests. Although in some cases the facilities 

provided summaries of certain broad line item costs, in no case does the supporting information 

that is available provide detail at a level that allows for critical review. In the case of SRP 

Coronado Generating Station, ADEQ received only a broad summary of control costs without 

itemized breakdowns of specific costs. 

As a result, we have used EPA’s Integrated Planning Model (IPM) to calculate the 

capital costs and annual operating costs associated with the various NOx control options. EPA’s 

Clean Air Markets Division (CAMD) uses IPM to evaluate the cost and emissions impacts of 

proposed policies to limit emissions of SO2, NOx, carbon dioxide (CO2), and mercury (Hg) from 

the electric power sector. Developed by ICF Consulting, Inc. and used to support public and 

63 40 CFR 51.308(e)(1). 

64 See, e.g. CAA section 110(a)(2) (F) and 40 CFR 51.212(c). 

65 As described above, ADEQ did specify a test method for PM10 for each of the relevant sources (Method 201/202). 

However, we are proposing to also allow the use of test methods that do not capture condensable particulate matter, 

namely EPA Methods 1 through 4 and Method 5 or Method 5e. 
Arizona Regional Haze Technical Support Document – Page 36 of 80 

private sector clients, IPM is a multi-regional, dynamic, deterministic linear programming model 

of the U.S. electric power sector. EPA has used IPM in rulemakings such as the Mercury and Air 

Toxics Standard and the Cross-State Air Pollution Rule. For the purposes of this BART 

determination, we specifically used only the NOx emission control technology cost 

methodologies contained in EPA’s IPM Base Case v4.10 (August 2010).66 For Base Case v4.10, 

EPA’s Clean Air Markets Division contracted with engineering firm Sargent and Lundy to 

perform a complete bottom-up engineering reassessment of the cost and performance 

assumptions for SO2 and nitrogen oxides NOx emission controls. Summaries of our control cost 

estimates for the various control technology options considered for each unit are included below. 

We used publicly available information to estimate that AEPCO is a small utility. EPA 

requested information from AEPCO on the economics of operating Apache Generating Station 

and what impact the installation of SCR may have on the economics of operating Apache 

Generating Station. Specifically, EPA is seeking information on the ability of AEPCO to recover 

the cost of pollution control technology through rate increases and the impact those rate increases 

may have on AEPCO’s customers. If we receive comments sufficiently documenting that 

installation of SCR may have a severe impact on the economics of operating Apache Generating 

Station, we may incorporate such considerations in our selection of BART. Our impact analysis 

and request for comment is discussed in more detail below, under EPA’s BART Determinations 

for Apache Units 2 and 3. 

Control Effectiveness: The evaluation of control effectiveness is an important part of a 

five-factor analysis because it influences both cost-effectiveness and visibility benefits. The 

BART Guidelines note that for each technically feasible control option: 

“It is important . . . that in analyzing the technology you take into account the 

most stringent emission control level that the technology is capable of achieving. 

You should consider recent regulatory decisions and performance data (e.g., 

manufacturer's data, engineering estimates and the experience of other sources) 

when identifying an emissions performance level or levels to evaluate.”67

In general, our estimates of LNB and SNCR control effectiveness differ slightly from the 

control effectiveness levels considered by ADEQ. In the case of LNB, for example, this 

is the result of the fact that actual emissions data for LNB performance were available for 

certain units at the time of our analysis. ADEQ’s analysis was performed at an earlier 

date when these emissions data were not available. More detailed information regarding 

these differences is in our discussion of individual facilities in the following sections of 

this TSD. 

In particular, we find that ADEQ did not adequately support its estimate of SCR control 

effectiveness. SCR, as an add-on control technology, can be installed by itself as a standalone 

option or in conjunction with burner upgrades. In cases where units can be upgraded with 

combustion control technology such as low-NOx burners, SCR is commonly installed as an addon post-combustion control. When evaluating control options with a range of emission 

66 http://www.epa.gov/airmarkt/progsregs/epa-ipm/BaseCasev410.html#documentation

67 40 CFR Part 51, Appendix Y § IV.D.3. 
Arizona Regional Haze Technical Support Document – Page 37 of 80 

performance levels, the BART Guidelines indicate that “in analyzing the technology you take 

into account the most stringent emission control level that the technology is capable of 

achieving.”68 Existing vendor literature and technical studies indicate that SCR systems are 

capable of achieving a 0.05 lb/MMBtu emission rate (approximately 80-90% control efficiency) 

and that this emission rate can be achieved on a retrofit basis, particularly when combined with 

combustion control technology such as LNB. 

69

For control options involving the installation SCR in conjunction with LNB, ADEQ 

considered the achievable emission rate to be between 0.07 lb/MMbtu (for Apache and Cholla) 

and 0.08 lb/MMbtu (for Coronado). These emission rates are within a range of SCR performance 

that has been considered by other western states in preparing RH SIPs, and may possibly be an 

appropriate estimation of the site-specific level of SCR performance for coal-fired units at 

Apache, Cholla, and Coronado. We note that the BART Guidelines indicate that, “In assessing 

the capability of the control alternative, latitude exists to consider special circumstances pertinent 

to the specific source under review [...]. However, you should explain the basis for choosing the 

alternate level (or range) of control in the BART analysis.”70 Although the alternate levels of 

emission control considered by ADEQ for SCR in conjunction with LNB were stated in each 

respective facility’s BART analysis, these emission rates were not further supported by any 

calculations, engineering analysis, or documentation. We do not believe that AEPCO, APS, and 

SRP have provided adequate supporting analysis to justify these emission rates. As mentioned in 

the Federal Register notice for this action, we are seeking comment on whether it is appropriate 

to consider an emission rate less stringent than 0.05 lb/MMBtu when evaluating the installation 

SCR in conjunction with LNB at Apache, Cholla, and Coronado. 

In the absence of source-specific considerations warranting a less stringent control level, 

we presume that an emissions limit of 0.05 lb/MMBtu is achievable by these units through the 

use of SCR in addition to advanced combustion controls. We have recently received information 

from AEPCO and SRP regarding potential NOx controls at their facilities. This information 

arrived too late to be fully evaluated for this proposed rulemaking, and EPA will need additional 

documentation from the utilities to support the information that they have provided to date. We 

have put the utility information in the docket for public review, and we will evaluate the 

information, and any additional information that the utilities may want to provide prior to 

making our final BART determinations.71 If we receive additional comments that sufficiently 

document source-specific considerations justifying the use of an emission rate less stringent than 

0.05 lb/MMBtu, we may incorporate such considerations in our selection of BART. 

2. Energy and Non-air Environmental Impacts

Energy Impacts: With respect to the potential energy impacts of the BART control 

options, we note that SCR incurs a draft loss that will increase parasitic loads, and that other 

emissions controls may also have modest energy impacts. The costs for direct energy impacts, 

68 70 FR 39166 

69 See Docket Items G-04, “Emissions Control: Cost-Effective Layered Technology for Ultra-Low NOx Control” 

(2007), Docket Item G-05 “What’s New in SCRs” (2006), and Docket Item G-06 “Nitrogen Oxides Emission 

Control Options for Coal-Fired Electric Utility Boilers” (2005) 

70 40 CFR Part 51, Appendix Y § IV.D.3. 

71 Docket Items C-15 “Letter from Kelly Barr (SRP) to Deborah Jordan (EPA)” and C-16 “Letter from Michelle 

Freeark (AEPCO) to Deborah Jordan (EPA).” 
Arizona Regional Haze Technical Support Document – Page 38 of 80 

i.e., power consumption from the control equipment and additional draft system fans from each 

control technology, are included in the cost analyses and are not considered further in this 

section. Indirect energy impacts, such as the energy to produce raw materials, are not considered, 

consistent with the BART guidelines. 

Ammonia Adsorption: Ammonia adsorption (resulting from ammonia injection from SCR 

or selective non-catalytic reduction—SNCR) to fly ash is generally not desirable due to odor but 

does not impact the integrity of the use of fly ash in concrete. However, other NOx control 

technologies, including LNB, also have undesirable impacts on fly ash. LNBs increase the 

amount of unburned carbon in the fly ash, also known as Loss of Ignition (LOI), which does 

affect the integrity of the concrete. Commercial scale technologies exist to remove ammonia and 

LOI from fly ash. Moreover, the impact of SCR on fly ash is smaller than the impact of LNB on 

fly ash, and in both cases, the adverse effects can be mitigated.72 We conclude that the ability of 

the relevant facilities to sell fly ash is unlikely to be affected by the installation of SCR and 

SNCR technologies. 

Safety: SCR and SNCR may involve potential safety hazards associated with the 

transportation and handling of anhydrous ammonia. Since each of the relevant facilities is served 

by a nearby railroad line, EPA concludes that the use of ammonia does not pose any additional 

safety concern as long as established safety procedures are followed. 

Thus, EPA proposes to find that potential energy and non-air quality impacts do not 

warrant elimination of any of the otherwise feasible control options for NOx at any of the 

sources. 

3. Pollution Control Equipment in Use at the Source

The presence of existing pollution control technology at each source is reflected in our 

BART analysis in two ways: first, in the consideration of available control technologies, and 

second, in the development of baseline emission rates for use in cost calculations and visibility 

modeling. As noted above, we largely agree with ADEQ’s consideration of available control 

technologies. However, because several of the affected units have had new controls installed in 

the last several years, we have adjusted the baseline emissions periods to reflect current control 

technology at the sources, as described further below in our proposed BART determinations. 

4. Remaining Useful Life of the Source

We are considering each source's “remaining useful life” as one element of the overall 

cost analysis as allowed by the BART Guidelines. Since we are not aware of any federally- or 

State-enforceable shut-down date for any of the affected sources, we have used the default 20-

year amortization period in the EPA Cost Control Manual as the remaining useful life of the 

facilities considered in this proposed action. 

5. Degree of Improvement in Visibility

EPA estimated the degree of visibility improvement expected from a BART control 

based on the difference between baseline visibility impacts prior to controls and visibility 

72 See docket item G-13, “Impact of Ammonia in Fly Ash on its Beneficial Use,” Memorandum from Nancy Jones 

and Stephen Edgerton, EC/R Incorporated, to Anita Lee, U.S. EPA/Region 9, August 31, 2010. 
Arizona Regional Haze Technical Support Document – Page 39 of 80 

impacts with controls in operation. EPA used the CALPUFF model version 5.873 to determine 

the baseline and post-control visibility impacts for all three facilities. EPA followed the modeling 

approach recommended in the BART Guidelines. We developed a modeling protocol, used 

maximum daily emissions as a baseline, applied estimated percent reductions for alternative 

control technologies, and used the CALPUFF model to estimate visibility impacts at Class I 

areas within 300 kilometers. 

a) Modeling Protocol

A modeling protocol was developed by our contractor74 at the University of North 

Carolina (UNC) that is based largely on the WRAP protocol,75 although there are a few 

differences between our protocol and that of the WRAP. Both protocols used meteorological 

inputs for 2001, 2002, and 2003 based on the Mesoscale Model version 5 (MM5) prognostic 

meteorological fields..... EPA meteorological inputs differed from the WRAP’s in that the 

WRAP incorporated upper air data, as recommended by the Federal Land Managers, and also 

values for some parameters that enabled smoother and more realistic wind fields. These 

CALMET inputs were developed by the ENSR Corporation for modeling of emissions at the 

Navajo Generating Station.76 Another key difference was EPA’s use of the current regulatory 

version of the CALPUFF modeling system, version 5.8. Facility stack parameters, such as stack 

height and exit temperature, were generally the same as those provided by WRAP member states 

to the WRAP, except that in some cases updated parameters were provided by the facilities at 

EPA’s request. 

We performed separate CALPUFF modeling runs using baseline emissions, and using the 

emissions remaining after each candidate control technology was applied to the baseline. For 

baseline PM emissions, EPA used the WRAP’s estimates. However, following procedures 

developed by the National Park Service,77 EPA divided those emissions into separate chemical 

species, and into separate coarse and fine particle fractions, to reflect better their varying 

visibility impacts. 

73 EPA relied on version 5.8 of CALPUFF because it is the EPA-approved version promulgated in the Guideline on 

Air Quality Models (40 CFR 51, Appendix W, section 6.2.1.e; 68 FR 18440, April 15, 2003. It was also the 

approved version when EPA promulgated the BART Guidelines (70 FR 39122-39123, July 6, 2005). EPA updated 

the specific version to be used for regulatory purposes on June 29, 2007, including minor revisions as of that date; 

the approved CALPUFF modeling system includes CALPUFF version 5.8, level 070623, and CALMET version 5.8 

level 070623. At this time, any other version of the CALPUFF modeling system would be considered an “alternative 

model”, subject to the provisions of Guideline on Air Quality Models section 3.2.2(b), requiring a full theoretical 

and performance evaluation.

74 Docket item E-01: Technical Analysis for Arizona Regional Haze FIPs: Modeling Protocol for Subject-to-BART 

and BART Control Options Analyses, EP-D-07-102 WA5-12 Task 5, Institute for the Envir,onment, University of 

North Carolina at Chapel Hill (initial draft received March 14, 2012, final draft received July 16, 2012). 

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

States, Western Regional Air Partnership (WRAP); Gail Tonnesen, Zion Wang; Ralph Morris, Abby Hoats and 

Yiqin Jia, August 15, 2006. Available on UCR Regional Modeling Center web site, BART CALPUFF Modeling, 

http://pah.cert.ucr.edu/aqm/308/bart.shtml . 

76 Docket item G-16: Revised BART Analysis for the Navajo Generating Station Units 1-3, ENSR Corporation, 

Document No. 05830-012-300, January 2009, Salt River Project – Navajo Generating Station, Tempe, AZ. 

77 “Particulate Matter Speciation”, National Park Service, 2006. 

http://www.nature.nps.gov/air/Permits/ect/index.cfm
Arizona Regional Haze Technical Support Document – Page 40 of 80 

Although costs and emission reductions for each candidate BART control technology 

must necessarily be calculated separately for each emitting unit of a facility, emissions from all 

the units will be emitted into the air simultaneously. EPA modeled all units (stacks) and 

pollutants simultaneously. That is, even though only NOx BART alternatives were evaluated, 

SO2 and PM10 emissions were also included in the modeling. Modeling all emissions from all the 

units accounts for the chemical interaction between multiple plumes, and between the plumes 

and the background concentrations. This also accounts for the facts that deciview benefits from 

individual units are not linearly additive, and that each EPA BART proposal is for the facility as 

a whole. Additional details on the modeling may be found in the UNC report prepared for EPA.78

EPA used the current regulatory version of the CALPUFF modeling system, which 

comprises the following source code versions: 

· CALMET Version 5.8, Level: 070623 

· CALPUFF Version 5.8, Level: 070623 

· POSTUTIL Version 1.56. Level: 070627 

· CALPOST Version 6.221, Level 080724 

The projection and coordinate system used was the same as used by the WRAP for 

Arizona modeling: 

· Projection: Lambert Conformal Conic (LCC) 

· Projection origin (lat, long): 40°, -97° 

· Standard parallels: 33°, 45° 

· False easting and northing: 0 m, 0 m 

· Projection ellipsoid: “NWS-84”, 6370 km radius sphere 

The CALMET modeling domain was identical to the WRAP Arizona domain: 288 x 225 

grid cells (X & Y), each 4 km, total size 1152 x 900 km; southwest corner at LCC coordinates -

1944 km, -900 km. The CALPUFF domain was the same as the CALMET domain. 

The CALPUFF and CALPOST inputs were prepared using the WRAP’s input files as a 

starting point, from the WRAP Regional Modeling Center’s “BART CalPuff Modeling” web site 

(http://pah.cert.ucr.edu/aqm/308/bart.shtml ). Changes were made to the CALPUFF inputs to 

accommodate the facilities’ locations, stack parameters, and emission rates for the base case and 

control scenarios. POSTUTIL inputs are not available on the WRAP web site, but input 

preparation was straightforward for HNO3/NO3 partitioning (MNITRATE = 1) and a constant 1 

ppb ammonia background concentration per the IWAQM Phase 2 guidance, cited above. 

Changes to the CALPOST inputs were made to accommodate the natural background 

concentrations and relative humidity adjustment factors specific to each Class I area and the 

various visibility calculation methods, discussed below.

78 Docket item E-02: Technical Analysis for Arizona Regional Haze FIPs: Task 8: Five-Factor BART Analysis for 

AEPCO Apache, APS Cholla and SRP Coronado, EP-D-07-102 WA5-12 Task 8, Institute for the Environment, 

University of North Carolina at Chapel Hill (initial draft received June 28, 2012, final draft received July 16, 2012). 
Arizona Regional Haze Technical Support Document – Page 41 of 80 

Table 15 - Class I Areas within 300 km of Apache, Cholla, and Coronado

abbreviation 

Class I Area State 

Managing 

Agency 

Within 300 km of 

band Bandelier NM NM NPS Coronado 

bosq Bosque del Apache Wilderness NM FWS Coronado 

care Capitol Reef NP UT NPS Cholla 

chir Chiricahua NM AZ NPS Apache, Coronado 

chrw Chiricahua Wilderness AZ USFS Apache, Coronado 

gali Galiuro Wilderness AZ USFS All three 

gila Gila Wilderness NM USFS All three 

grca Grand Canyon NP AZ NPS Cholla, Coronado 

maza Mazatzal Wilderness AZ USFS All three 

meve Mesa Verde NP CO NPS Cholla, Coronado 

moba Mount Baldy Wilderness AZ USFS All three 

pefo Petrified Forest NP AZ NPS Cholla, Coronado 

pimo Pine Mountain Wilderness AZ USFS Cholla, Coronado 

sagu Saguaro NP AZ NPS All three 

sape San Pedro Parks Wilderness NM USFS Coronado 

sian Sierra Ancha Wilderness AZ USFS All three 

supe Superstition Wilderness AZ USFS All three 

syca Sycamore Canyon Wilderness AZ USFS Cholla, Coronado 

b) Baseline Emissions

Baseline NOx and SO2 emissions for the facilities were generally based on the maximum 

daily emissions from recent data in EPA’s CAMD database, with data examined for 2008 to 

2011. The CAMD data derive from Continuous Emissions Monitoring in place at the facilities, 

and give the actual emissions that occurred. However, in cases where EPA is proposing to 

approve the BART emissions limits submitted by ADEQ, EPA used emission rates based on 

those limits, in lb/MMBtu, in combination with the maximum daily heat rate in MMBtu/hour 

from the CAMD data79. The baseline emissions used by EPA reflect current fuels and control 

technologies in place at the facilities, as well as regulatory requirements the facilities will be 

required to meet independent of EPA’s BART determination. This results in a more realistic 

estimate of current visibility impacts, and of the improvements that one would expect to result 

from implementation of EPA’s proposed BART controls. 

c) Emission Reductions for Alternative Controls

For the CALPUFF modeling to assess visibility after application of a control technology, 

the percent control expected from the technology was applied to the baseline maximum daily 

emissions just described, as recommended in the BART Guidelines. As discussed elsewhere, 

LNB and SNCR each were assumed to reduce NOx by 30 percent, and SCR was assumed to 

reduce NOx by 90 percent. However, for SCR, we used a lower bound of 0.05 lb/MMBtu NOx, 

an emission rate that we have confidence is achievable, as discussed above under “Control 

Effectiveness”. The percent reduction actually applied to the maximum daily emissions was 

whatever was required to reduce the CAMD annual average emission factor down to this 0.05 

79 These data and the choice of maximum emission dates are in UNC’s spreadsheet “AZ_BART_sources_all-Task7-

8_2012-06-10.xls”, supplemented by EPA’s “AZ Max Emission Dates.xlsx” 
Arizona Regional Haze Technical Support Document – Page 42 of 80 

lb/MMBtu NOx. For the various emitting units at the facilities, this ranged from 80 to 89 percent, 

instead of a full 90 percent reduction. 

Finally, in modeling the visibility impact of SCR for Apache and Coronado, EPA 

accounted for the increased sulfuric acid emissions that occur when the SCR catalyst oxidizes 

SO2 present in the flue gas, using an estimation procedure developed by the Electric Power 

Research Institute80 (EPRI). (Estimating Total Sulfuric Acid Emissions from Stationary Power 

Plants, Version 2010a, 1020636, Technical Update, Electric Power Research Institute, April 

2010) This side effect of SCR’s NOx reduction increases sulfate emissions and decreases the 

visibility benefits of SCR by around 5 percent. This effect was not included for Cholla, because 

the existing baghouses would reduce the resulting sulfate particulate by 99%, making it 

negligible in comparison with other particulate emissions from the Cholla units. 

In the EPRI method, the SO4 emissions added for modeling due to the conversion of SO2

via oxidation by the SCR catalyst are calculated as follows. 

SO4 emissions = (Mass of coal) ¥ (S fraction) 

¥ (Conversion to SO2 & then to SO3/H2SO4) 

¥ (Effect of controls) 

¥ (H2SO4 per S) ¥ (SO4 per H2SO4) 

where (table and page numbers are from the cited EPRI 2010 document): 

Mass of coal, lb/hr = 

(106¥ heat rate for max day, MMBtu/hr)/ ¥ (heating value of fuel, Btu/lb) 

S fraction = % sulfur content of coal / 100 = [%S]/100 

Conversion to SO2 & then to SO3/H2SO4: 

S to SO2

0.95 equation 4-2b, for bituminous coals (p.4-3) 

SCR catalyst SO2 to SO3/H2SO4

0.67% EPA, FCPP proposal, based on Hitachi guarantee81

Effect of Controls: product of penetration factors for each control 

hot-side ESP + Air Preheater (APH) + Wet Flue Gas Desulfurization (WFGD or scrubber) 

control before SCR: hot-side ESP, p=0.63 = 1 - 37% 

0.63 Table 4-4, all coals (p.4-20) 

other after SCR: APH, p=0.50 = 1 - 50% 

0.50 Table 4-3, for low-sulfur eastern bituminous coal (p.4-18) 

control after SCR: WFGD, p=0.47 = 1 - 53% 

0.47 Table 4-5, Wet: Spray Tower for eastern bituminous coal (p.4-22) 

80 Docket item G-14: Estimating Total Sulfuric Acid Emissions from Stationary Power Plants, Version 2010a, 

1020636, Technical Update, Electric Power Research Institute, April 2010 

81 Docket item F-01: EPA Technical Support Document for "Source Specific Federal Implementation Plan for 

Implementing Best Available Retrofit Technology for Four Corners Power Plant: Navajo Nation", 75 FR 64221, 

October 19, 2010; based on Hitachi guarantee on conversion using CX series catalyst 
Arizona Regional Haze Technical Support Document – Page 43 of 80 

Express as SO4, using ratio of molecular weights of S and SO4: 

(H2SO4 per S) ¥ (SO4 per H2SO4), to express calculated S as SO4

(98.079/32.065) ¥ (96.06/98.079) = 96.06/32.065 

The product of all these is 

SO4 lb/hr emissions = (106¥ heat rate MMBtu/hr / coal heating value Btu/lb) 

¥ (%S/100) ¥ 0.95 ¥ 0.0067 

¥ (0.63 ¥ 0.50 ¥ 0.47) 

¥ 96.06/32.065 

This formula is noted under table A-1(b) of Appendix A to the UNC Task 8 report, and is used in 

UNC’s emission calculation spreadsheet (AZ_BART_sources_all-Task7-8_2012-06-

10.xls, illustrated in the UNC Task 8 report, Appendix A). 82

d) Visibility Impacts

Text and spreadsheet files used in EPA’s visibility modeling are listed in Appendix A of this 

TSD and located in docket folder G-15. All of EPA’s visibility modeling results are included in 

Appendix B of the TSD. 

CALPUFF Modeling: EPA followed the BART Guidelines in assessing visibility 

impacts. For each Class I area within 300 km of a facility, the CALPUFF model is used to 

simulate the baseline visibility impact of each facility and the impacts resulting after alternative 

controls are applied. However, certain aspects of assessing visibility with CALPUFF are not 

fully addressed in the Guidelines. These aspects include which “98th percentile” from the model 

to use, the visibility calculation method (old vs. revised IMPROVE equation), and natural 

background concentrations (annual average versus best 20 percent of days). Additional model 

outputs are available in the docket in the form of Excel spreadsheets; the actual CALPUFF 

model input and output files are also available on request. The full list of files available appears 

at the end of this TSD. 

 98th Percentile from Model: As recommended in the BART Guidelines, the 98th 

percentile daily impact in deciviews is used as the basic metric of visibility impact. (For a given 

Class I area, and for each modeled day, the model finds the maximum impact. From among the 

365 maximum daily values, the 98th percentile is chosen, that is, the 8th highest.) Since multiple 

years of meteorology are modeled, there are at least three ways to use the model results: the 

maximum from among the 98th percentiles for the individual years 2001, 2002, and 2003 

(“maximum”); the average of these three (“average”), or a single 98th percentile computed from 

all three years of data together (“merged” or “All Years”, the 22nd high among 1095 daily 

values). The average and merged values are both unbiased estimates of the true 98th percentile; 

for this proposal EPA has used the merged value. The more conservative maximum value would 

82 Docket item E-02: Technical Analysis for Arizona Regional Haze FIPs: Task 8: Five-Factor BART Analysis for 

AEPCO Apache, APS Cholla and SRP Coronado, EP-D-07-102 WA5-12 Task 8, Institute for the Environment, 

University of North Carolina at Chapel Hill (initial draft received June 28, 2012, final draft received July 16, 2012). 
Arizona Regional Haze Technical Support Document – Page 44 of 80 

be appropriate for a screening purpose, such as for determining whether a source is subject to 

BART. 

Visibility Calculation Method: The visibility calculation method relied on by EPA 

differed from that used by ADEQ. Visibility impacts may be simulated with CALPUFF using 

either the old or the revised IMPROVE equation for translating pollutant concentrations into 

deciviews; these are respectively CALPUFF visibility methods 6 and 8 (implemented in the 

CALPOST post-processor). Many BART assessments were performed before method 8 was 

incorporated into CALPUFF, so method 6 was generally for past assessments. However, in this 

proposal EPA is primarily relying on method 8. Method 8 is currently preferred by the Federal 

Land Managers; since the revised IMPROVE equation performs better at estimating visibility.

83

For the facilities examined in this proposal, baseline impacts using method 6 would average 

about 10 percent higher than those using method 8 (with a range of 18 percent lower to28 

percent higher depending on facility and Class I area; the effect for areas showing the largest 

benefit from control was similar to the average).

Natural Background Conditions: Another CALPUFF choice is whether to calculate 

visibility impacts relative to annual average natural conditions, or relative to the best 20 percent 

of natural background days; these may be referred to as “a” and “b”. For both “a” and “b”, 

background concentrations for each Class I area are available in a Federal Land Managers’ 

document.84 EPA Guidance allows for the use of either “a” or “b.”,85 Since the annual average 

has worse visibility and higher deciviews than the best days do, a given facility impact will be 

smaller relative to the average than it is relative to the best days. That is, a facility’s impact will 

stand out less under poorer visibility conditions. Thus, modeled facility impacts and control 

benefits appear smaller when “a” is used than when “b” is used. In this proposal, EPA is relying 

on “b”, best 20 percent, consistent with initial EPA recommendations for BART assessments. 86

For the facilities examined in this proposal, baseline impacts would average about 20 percent 

lower using background “a” than those using background “b” (with a range of 17 percent to 28 

percent lower depending on facility and Class I area; the effect for areas showing the largest 

benefit from control was similar to the average). 

Considering visibility method and choice of background together, the BART visibility 

assessments relied on by ADEQ used method “6a”, the old IMPROVE equation, and impacts 

relative to annual average natural conditions. This is a valid approach, and is consistent with 

EPA guidance.87 However, for this proposal, EPA considered all four combinations of 

IMPROVE equation version and natural background: 6a, 6b, 8a, and 8b. EPA primarily relied on 

method “8b”, that is, the revised IMPROVE equation, and impacts relative to the best 20 percent 

83 Pitchford, Marc, 2006, “New IMPROVE algorithm for estimating light extinction approved for use”, The 

IMPROVE Newsletter, Volume 14, Number 4, Air Resource Specialists, Inc.; web page: 

http://vista.cira.colostate.edu/improve/Publications/news_letters.htm

84 Federal Land Managers’ Air Quality Related Values Work Group (FLAG) Phase I Report—Revised (2010), U.S. 

Forest Service, National Park Service, U.S. Fish and Wildlife Service, October 2010. Available on web page 

http://www.nature.nps.gov/air/Permits/flag/

85 “Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations”, 

memorandum from Joseph W. Paisie, EPA OAQPS, July 19, 2006, p.2 

86 BART Guidelines, 70 FR 39125, July 6, 2005. “Finally, these final BART guidelines use the natural visibility 

baseline for the 20 percent best visibility days for comparison to the ‘cause or contribute’ applicability thresholds.” 

87 Additional Regional Haze Questions”, September 27, 2006 Revision, EPA OAQPS 
Arizona Regional Haze Technical Support Document – Page 45 of 80 

of natural background days. This is most consistent with our current understanding of how best 

to assess source specific visibility impacts. Combining the differences in visibility method and 

chosen background, for the facilities examined in this proposal, baseline impacts would average 

about 15 percent lower using method “6a” than those using method “8b” (with a range of 1 

percent to 37 percent lower depending on facility and Class I area; the effect for areas showing 

the largest benefit from control was similar to the average). 

B. EPA’s BART Determinations

1. Apache Units 2 and 3

a) Costs of Compliance

Our general approach to calculating the costs of compliance is described in III.A.1, while issues 

unique to Apache Units 2 and 3 are described herein. As mentioned in the Federal Register 

notice for this proposal, control costs were developed by our contractor using the Integrated 

Planning Model (IPM) Base Case v4.10 (August 2010). The specific parameters and assumptions 

used in developing these costs are included in our contractor’s report and its associated 

spreadsheet. A summary of capital and operating costs is included in Table 16.

Table 16 - Apache 2 and 3: EPA's Control Cost Estimates

Apache 2 Apache 3

LNB+OFA

SNCR+ 

LNB+OFA

SCR+ 

LNB+OFA LNB+OFA

SNCR+ 

LNB+OFA

SCR+ 

LNB+OFA

Unit Output (MW) 204 204 204 204 204 204

Capacity Factor 0.62 0.62 0.62 0.71 0.71 0.71

Capital Cost 10,543,189 14,623,189 44,779,657 10,543,189 14,623,189 43,812,028

Capital Recovery Factor 0.094 0.094 0.094 0.094 0.094 0.094

Annualized Rate ($/yr) 995,202 1,380,326 4,226,883 995,202 1,380,326 4,135,546

Fixed O&M ($/year) 70,288 173,235 432,688 70,288 173,235 432,688

$/MW-yr 345 505 1,776 345 505 1,776

Variable O&M ($/year) 77,558 1,100,321 1,210,656 88,816 1,413,298 1,532,869

$/MWh 0.07 0.92 1.02 0.07 1.04 1.14

Annual O&M ($/year) 147,845 1,273,555 1,643,344 159,104 1,586,532 1,965,557

Total Annual Cost 

($/year) 1,142,120 2,652,841 5,869,299 1,153,378 2,968,611 6,103,078

The capital recovery factor (0.094) listed above is based upon an interest rate of 7% over a 20 

year equipment lifetime. Please note that this value does not include property tax (0.90%) and 

insurance (0.30%), which were included by our contractor in their calculation of capital recovery 

factor. As a result, the annualized rate ($/yr) and total annual cost ($/yr) listed in the table above 
Arizona Regional Haze Technical Support Document – Page 46 of 80 

are lower than the cost values summarized in our contractor’s cost calculation deliverable.88

Estimates of the annual emission rates used in cost calculations are summarized in Table 17. 

Table 17 - Apache 2 and 3: EPA's Annual Emission Estimates

Control Option Percent

Emission 

Factor Heat Rate

Annual 

Capacity Emission Rate

Reduction (lb/MMBtu) (MMBtu/hr) Factor (lb/hr) (tpy)

Apache 2

Baseline (OFA) -- 0.371 2,316 0.62 859 2,333

LNB+OFA 30% 0.26 2,316 0.62 601 1,633

SNCR+LNB+OFA151% 0.18 2,316 0.62 421 1,143

SCR+LNB+OFA 87% 0.05 2,316 0.62 116 314

Apache 3

Baseline (OFA) -- 0.438 2,223 0.71 974 3,028

LNB+OFA 30% 0.31 2,223 0.71 682 2,120

SNCR+LNB+OFA151% 0.21 2,223 0.71 477 1,484

SCR+LNB+OFA 89% 0.05 2,223 0.71 111 346

1

SNCR control effectiveness is based upon a 30% incremental reduction from LNB emission rates 

In particular, we highlight below certain aspects of our analysis of this factor that differ 

from ADEQ’s and AEPCO’s analysis. 

(1) Selection of Baseline Period 

AEPCO’s BART analysis used a 2002 to 2007 time period in order to establish its 

baseline NOx emissions. In our analysis, we decided to make use of the most recent Acid Rain 

Program emission data reported to CAMD, which, at the time that we began our analysis in 

2011, was the three-year period from 2008 to 2010. Based on CAMD documentation, no new 

control technology beyond the existing OFA system has been installed on either Apache Unit 2 

or 3. We consider the use of this more recent baseline period to be a realistic depiction of 

anticipated future emissions.89

(2) SCR Control Efficiency 

In determining the control efficiency of SCR, we have relied upon an SCR level of 

performance of 0.05 lb/MMBtu, which is more stringent than the level of performance used by 

ADEQ in its SIP. In the Apache BART analyses submitted to ADEQ, AEPCO indicated an SCR 

level of performance of 0.07 lb/MMBtu, but did not provide site-specific information describing 

how this emission rate was developed or discussing why a more stringent 0.05 lb/MMBtu level 

of performance could not be attained. Our control cost calculations for the SCR and LNB with 

OFA control options are based upon the control efficiency of SCR (combined with LNB) 

summarized in Table 18. 

88 See Appendix C of WA5-12 Task 8 Deliverable (Apache-Cholla-Coronado BART Analysis Report).docx 

89 BART Guidelines, 40 CFR Part 51, Appendix P, Section IV.D.4.d 
Arizona Regional Haze Technical Support Document – Page 47 of 80 

Table 18 - Apache 2 and 3: EPA's SCR (Combined with LNB) Control Efficiency

Unit Baseline 

Emission 

Rate1 

(lb/MMBtu)

SCR 

Emission 

Rate 

SCR 

Control 

Efficiency 

(percentage) 

Apache 2 0.371 0.05 87% 

Apache 3 0.438 0.05 89% 

1

 This baseline emission rate represents operation of 

OFA only. 

(3) Capacity Factor 

As noted previously, AEPCO calculated annual emission estimates for its control 

scenarios, in tons per year, using annual capacity factors developed internally over an 

unspecified time frame.90 The annual capacity factors AEPCO used for each unit were 92 percent 

(Apache 2), and 87 percent (Apache 3). We have also calculated annual emission estimates for 

our control scenarios using capacity factors, but have used information developed from CAMD 

information, and over a more recent 2008 to 2011 time frame. The annual capacity factors we 

have used for each unit are 62 percent (Apache 2), and 71 percent (Apache 3). We recognize that 

these capacity factors are lower than those used by AEPCO, and that by using these lower 

capacity factors, our estimates of total annual emissions (and correspondingly, the annual 

emission reductions) for each control scenario are lower than AEPCO’s estimates.91 Since costeffectiveness ($/ton) is calculated by dividing annual control costs ($/year) by annual emission 

reductions (tons/year), the use of emission reductions based on lower capacity factors will 

increase the cost per ton of pollutant reduced. 

We have elected to use the capacity factors specified above, as based on a 2008 to 2011 

time frame, in order to remain consistent with the time frame used to develop baseline annual 

emissions for Apache and the other power plants that are the subject of today’s proposed action. 

(4) Summary of Control Cost Estimates 

A summary of our control cost estimates for the various control technology options 

considered for Apache Units 2 and 3 is in Table 19.

Table 19 - Apache Units 2 and 3: EPA's Control Cost Summary

Control Option Emission 

Factor 

Emission Rate Emissions 

Removed 

Annual Cost Cost-effectiveness ($/ton) 

90 As listed in Table 2-1 in Docket Items B-03 and B-04, Apache BART Analyses 

91 We note that there are multiple reasons why our annual emission estimates (and estimates of emission removal) 

are lower than AEPCO’s and ADEQ’s estimates. We are not implying that the use of capacity factor is the sole, or 

even dominant, reason for this difference, simply that the use of lower capacity factors will result in lower annual 

emission estimates. 
Arizona Regional Haze Technical Support Document – Page 48 of 80 

(lb/MMB

tu) 

(lb/hr) (tpy) (tpy) ($/yr) Ave Incremental 

(from previous) 

Apache 2 

OFA (baseline) 0.371 859 2,333 -- -- -- -- 

LNB+OFA 0.26 601 1,633 700 1,142,120 1,632 -- 

SNCR+LNB+OFA 0.18 421 1,143 1,190 2,652,841 2,230 3,084 

SCR+LNB+OFA 0.05 116 314 2,019 5,869,299 2,908 3,881 

Apache 3 

OFA (baseline) 0.438 974 3,028 -- -- -- -- 

LNB+OFA 0.31 682 2,120 908 1,153,378 1,270 -- 

SNCR+LNB+OFA 0.22 477 1,484 1,544 2,968,611 1,922 2,854 

SCR+LNB+OFA 0.05 111 346 2,683 6,103,078 2,275 2,754 

As seen in Table 19, our calculations indicate that the SCR-based control options have 

average cost-effectiveness values of $2,275/ton to $2,908/ton, which falls in a range that we 

consider cost-effective. In addition, our calculations indicate that the SCR-based control options 

have an incremental cost-effectiveness of $2,754/ton to $3,881/ton, which is also in a range that 

we would consider cost-effective. As a result, our analysis of this factor indicates that the costs 

of compliance (average or incremental) are not sufficiently large to warrant eliminating any of 

the control options from consideration. 

b) Visibility Improvement

The overall visibility modeling approach was described above; aspects of the modeling 

specific to Apache are described here. EPA is proposing a NOx BART determination only for 

Apache units 2 and 3, but Unit 1 was also included in the modeling runs for greater realism in 

assessing the full facility’s visibility impacts.92 For Unit 1’s NOx emissions, ADEQ’s emission 

factor of 0.56 lb/MMBtu was combined with the maximum MMBtu/hr heat rate from EPA's 

CAMD database for 2008 to 2010. The baseline emissions used for these units were the 

maximum daily emissions in lb/hr from 2008 to 2010; the maxima occurred in early 2008. The 

base case reflects only OFA as the control in place. 

EPA evaluated LNB, SNCR (including LNB), and SCR (including LNB) applied to both 

Units 2 and 3; as mentioned above the SCR simulation accounted for the increase in sulfuric acid 

emissions due to catalyst oxidation of SO2. SCR was assumed to give a control effectiveness of 

87 percent and 89 percent for Units 2 and 3, respectively (less than 90 percent due to the 0.05 

lb/MMBtu NOx lower limit assumed for SCR). The nine Class I areas within 300 km of Apache 

were modeled; they are in the states of Arizona and New Mexico. The 98th percentile of delta 

deciviews over all three years of data was computed for each area and emission scenario. Table 

20 shows the impact for the base case, and the improvement from that baseline impact when 

92 Apache Unit 4, which consists of four simple-cycle gas turbines, was not included in the modeling because its 

NOx emissions are less than 1 percent of the emissions of units 2 and 3, and are therefore expected to have a de 

minimis effect on modeled visibility impacts. 
Arizona Regional Haze Technical Support Document – Page 49 of 80 

controls are applied, all in deciviews, for each area.93 Note that in all cases the deciview impacts 

are the “delta deciviews” from the CALPUFF model, that is, the impairment added (the “delta”) 

when pollution from the facility is added to natural background conditions. The Class I area 

types are National Monument (NM), Wilderness Area (WA), and National Park (NP). Also 

shown are the cumulative deciviews, the simple sum of impacts or improvements over all the 

Class I areas, and the number of areas with a baseline impact or improvement of at least 0.5 dv. 

The “Max. area number of days >= 0.5 dv” row shows the number of days that visibility 

impairment was greater than or equal to 0.5 dv, for the area having the greatest modeled 

impairment; the next row is comparable but uses 1.0 dv as the day-counting threshold. (Note that 

the “Improvement” columns shows the difference between a) the number of days over 0.5 that is 

the highest among all the areas before controls, and b) the number of days highest among the 

areas after controls; the highest number of days may occur at different areas before and after 

controls. The improvements within a single given area are shown in the other table.) 

Finally, the table includes two “dollars per deciview” 94 measures of cost-effectiveness, 

both of which take the annual cost of the control in millions of dollars per year, and divide by an 

improvement in deciviews. For the first metric, “$/max dv”, cost is divided by the deciview 

improvement at the Class I area with the greatest improvement. The second metric, 

“$/cumulative dv”, divides cost by the cumulative deciview improvement. In assessing the 

degree of visibility improvement from controls, EPA relied heavily on the maximum dv 

improvement and the number of areas showing improvement, with cumulative improvement 

providing a supplemental measure that combines information on the number of areas and on 

individual area improvement. The dollars per deciview metrics provided information 

supplemental to the dollars per ton that was considered in the cost factor. 

Table 2195 shows the number of days each area experiences modeled visibility 

impairment greater than or equal to 0.5 dv, and also the “cumulative” number of days. This is 

just the sum of the individual area values, and may not actually represent distinct calendar days. 

In its comments on Arizona’s proposed Regional Haze SIP, the National Park Service 

noted that: 

Compared to the typical control cost analysis in which estimates fall into the 

range of $2,000 - $10,000 per ton of pollutant removed, spending millions of 

dollars per deciview (dv) to improve visibility may appear extraordinarily 

expensive. However, our compilation of BART analyses across the U.S. reveals 

that the average cost per dv proposed by either a state or a BART source is $14 - 

$18 million.96

93 The deciview impacts are copied from the spreadsheet “AZRHFIP_TSD_vis_summ_tables.xlsx”, which in turn 

relies on the spreadsheet “aep_az_unit2-3_dollarperdv_analysis_finalwithplots2.xls” prepared by UNC. 

94 The costs used in $/dv rely on the spreadsheet “EGU BART Costs_Apache_Cholla_Coronado_FINAL2.xlsx” also 

prepared by UNC. Note that the costs in the latter are slightly different than those in the cost tables in this TSD, 

which as noted above do not include property tax and insurance. 

95 The number of days above 0.5 and 1.0 dv are from the spreadsheet “AZRHFIP_TSD_Apache_visx.xlsx” 

96 Arizona Regional Haze SIP, Appendix E, Public Process, NPS General BART Comments on ADEQ BART 

Analyses (November 29, 2010), p. 4. 
Arizona Regional Haze Technical Support Document – Page 50 of 80 

While we do not necessarily consider $14 to $18 million/dv as being a reasonable range in all 

cases, we note that for all of the NOx control options, including SCR, both the $/max dv and the 

$/cumulative dv are well below this range. 

The area with the greatest dv improvement was the Chiricahua Wilderness Area; the 

improvement from LNB was 0.5 dv, from SNCR was 1 dv, and from SCR was 1.6 dv. Any of 

these improvements would contribute to improved visibility, with SCR being the superior option 

for visibility. The corresponding cumulative improvements are 2.1, 3.8, and 6.5. Both SNCR and 

SCR give improvements exceeding 0.5 dv at four areas, but for SCR the improvements at those 

areas also exceed a full 1 dv. As shown in Table 21, the number of days per year with impacts 

above 0.5 dv decreases by 10 for LNB, by 23 for SNCR, and by 42 for SCR (considering the 

area where the decrease is the greatest, Chiricahua National Monument). The improvements 

from SCR are substantially greater than for the other candidate controls. The modeled degree of 

visibility improvement supports SCR as BART for Apache. 
Arizona Regional Haze Technical Support Document – Page 51 of 80 

Table 20 - Apache Units 2 and 3: EPA's Visibility Improvement from NOx Controls

base ctrl1_r ctrl2_r ctrl3s 

Class I Area Baseline 

impact 

(dv) 

Improvement 

from LNB 

(dv) 

Improvement 

from SNCR 

(dv) 

Improvement 

from SCR 

(dv) 

Chiricahua NM 3.41 0.44 0.82 1.51 

Chiricahua WA 3.46 0.53 1.00 1.59 

Galiuro WA 2.22 0.39 0.65 1.10 

Gila WA 0.63 0.14 0.22 0.37 

Mazatzal WA 0.28 0.05 0.09 0.14 

Mount Baldy WA 0.28 0.07 0.11 0.18 

Saguaro NP 2.49 0.38 0.66 1.16 

Sierra Ancha WA 0.29 0.06 0.10 0.14 

Superstition WA 0.61 0.10 0.19 0.31 

Cumulative dv 13.67 2.14 3.83 6.51 

# areas >= 0.5 6 1 4 4 

Max. area number of days 

>= 0.5 dv

128 10 23 42 

Max. area number of days 

>= 1.0 dv

75 12 25 40 

$/max dv, millions $4.8 $6.0 $8.2 

$/cumulative dv, millions $1.2 $1.6 $2.0 

Table 21 - Apache Units 2 and 3: EPA's Visibility Improvement Days from NOx Controls

Base ctrl1_r ctrl2_r ctrl3s 

Class I Area Baseline 

impact 

(days) 

Improvement 

from LNB 

(days) 

Improvement 

from SNCR 

(days) 

Improvement 

from SCR 

(days) 

Chiricahua NM 128 10 21 42 

Chiricahua WA 116 8 23 39 

Galiuro WA 46 7 10 20 

Gila WA 12 5 8 11 

Mazatzal WA 3 2 3 3 

Mount Baldy WA 2 1 1 2 

Saguaro NP 80 6 13 19 

Sierra Ancha WA 2 1 1 2 

Superstition WA 9 2 5 8 

Cumulative #days 

>= 0.5 

398 41 85 146 

c) EPA’s BART Determination

In considering the results of the five-factor analysis, we note that the remaining useful 

life of the source, as indicated previously by the plant economic life of Apache Units 2 and 3, is 

incorporated into control cost calculations as a 20-year amortization period. In addition, the 

presence of existing pollution control technology is reflected in the cost and visibility factors as a 

result of selection of the baseline period for cost calculations and visibility modeling. For 

Apache Units 2 and 3, a baseline period (2008 to 2010) was selected that reflects the currently 

existing pollution control technology (OFA). In examining energy and non-air quality impacts, 

we note certain potential impacts resulting from the use of ammonia injection associated with the 
Arizona Regional Haze Technical Support Document – Page 52 of 80 

SNCR and SCR control options, but do not consider these impacts sufficient enough to warrant 

eliminating any of the available control technologies. 

Our consideration of degree of visibility improvement focuses primarily on the 

improvement from base case impacts associated with each control option. While each of the 

available NOx control options achieves some degree of visibility improvement, we consider the 

improvement associated with the most stringent option, SCR with LNB and OFA, to be 

substantial. Our consideration of cost of compliance focuses primarily on the cost-effectiveness 

of each control option, as measured in cost per ton and incremental cost per ton of each control 

option. Despite the fact that the most stringent option, SCR with LNB and OFA, is the most 

expensive of the available control options, we consider it cost-effective on an average basis as 

well as on an incremental basis when compared to the next most stringent option, SNCR with 

LNB and OFA. 

As a result, we consider the most stringent available control option, SCR with LNB and 

OFA, to be both cost-effective and to result in substantial visibility improvement, and that the 

energy and non-air quality impacts are not sufficient to warrant eliminating it from consideration. 

Therefore, the results of our five-factor analysis indicate that NOx BART for Apache Units 2 and 

3 is SCR with LNB and OFA. 

However, we note that the BART guidelines state that: 

Even if the control technology is cost-effective, there may be cases where the installation 

of controls would affect the viability of continued plant operations. [...]You may take 

into consideration the conditions of the plant and the economic effects of requiring the 

use of a control technology. Where these effects are judged to have a severe impact on 

plant operations you may consider them in the selection process, but you may wish to 

provide an economic analysis that demonstrates, in sufficient detail for public review, the 

specific economic effects, parameters, and reasoning.”97

As explained in Section IX.C of the Federal Register notice for this proposed action, 

because AEPCO is a “small entity”, as defined under the Regulatory Flexibility Act, we have 

conducted an initial assessment of the potential adverse impacts on AEPCO of requiring SCR 

with LNB and OFA. Using publicly available information, EPA estimates that the annualized 

cost of requiring SCR in Units 1 and 2 would likely be in the range of 3 percent of AEPCO’s 

assets and between 6 and 7 percent of AEPCO’s annual sales. The projected costs of SCR with 

LNB and OFA are approximately $12 million per year. This exceeds AEPCO’s net margins of 

$9.5 million in 2010 and $1.9 million in 2011.98 See Table 22 for more information. 

97 70 FR 39171 

98 See Docket Item G-12Arizona Electric Power Cooperative, Inc. Annual Report Electric for Year 

Ending December 31, 2011 submitted to Arizona Corporation Commission Utilities Division, also 

available at 

http://www.azcc.gov/Divisions/Utilities/Annual%20Reports/2011/Electric/Arizona_Electric_Power_Coo

perative_Inc.pdf.
Arizona Regional Haze Technical Support Document – Page 53 of 80 

Table 22 - Relationship between Emission Control Costs and AEPCO Financial Data

Cost of controls (SCR option) 

Apache 2: $5,870,227 

Apache 3: $6,101,103 

Total: $11,971,330 

AEPCO 

Financials 2010 2011 

Total 

Revenue:* $207,377,079 $169,668,330 

Net Margin:* $9,503,556 $1,855,188 

Total Assets:* $350,634,866 

cost/revenue 5.8% 7.1% 

cost/assets 3.4% 

net margincost $(2,467,774) $(10,116,142) 

*From Docket Item H-1- Arizona Electric Power Cooperative, Inc. Annual Report Electric for Year 

Ending December 31, 2011 submitted to Arizona Corporation Commission Utilities Division

In addition to conducting this initial economic impact assessment, we requested 

information from AEPCO on the economics of operating Apache Generating Station and what 

impact the installation of SCR may have on the economics of operating Apache Generating 

Station. On June 29, 2012, we received a description of plant conditions and potential economic 

effects and are placing this information in the docket for this action.99 We will consider this 

information and any additional information received during the comment period as part of our 

final action. If our analysis of this information indicates that installation of SCR will have a 

severe impact on the economics of operating Apache Generating Station, we will incorporate 

such considerations in our selection of BART. 

Nonetheless, based on the available control technologies and the five factors discussed 

above, EPA is proposing to require Apache Generating Station to meet an emission limit for NOx

on Units 2 and 3 of 0.050 lb/MMBtu. Each of these emission limits is based on a rolling 30-

boiler-operating-day average. 

2. Cholla Units 2, 3 and 4

a) Costs of Compliance

Our general approach to calculating the costs of compliance is described in section 

III.A.1 above. Issues unique to Cholla Units 2, 3 and 4 are explained herein. As mentioned in the 

Federal Register notice for this proposal, control costs were developed by our contractor using 

99 Docket Item C-16, Letter from Michelle Freeark (AEPCO) to Deborah Jordan (EPA), AEPCO’s Comments on 

BART for Apache Generating Station, June 29, 2012. 
Arizona Regional Haze Technical Support Document – Page 54 of 80 

the Integrated Planning Model (IPM) Base Case v4.10 (August 2010). The specific parameters 

and assumptions used in developing these costs are included in our contractor’s report and its 

associated spreadsheet. A summary of capital and operating costs is included in Table 23.

The capital recovery factor (0.094) listed above is based upon an interest rate of 7% over 

a 20 year equipment lifetime. Please note that this value does not include property tax (0.90%) 

and insurance (0.30%), which were included by our contractor in their calculation of capital 

recovery factor. As a result, the annualized rate ($/yr) and total annual cost ($/yr) listed in the 

table above are lower than the cost values summarized in our contractor’s cost calculation 

deliverable.100 Estimates of the annual emission rates used in cost calculations are summarized in 

Table 24. 

100 See Appendix C of WA5-12 Task 8 Deliverable (Apache-Cholla-Coronado BART Analysis Report).docx 
Arizona Regional Haze Technical Support Document – Page 55 of 80 

Table 23 - Cholla 2, 3, and 4: EPA's Control Cost Estimates

Cholla 2 Cholla 3 Cholla 4

SNCR SCR SNCR SCR SNCR SCR 

Unit Output (MW) 290 290 312 312 414 414

Capacity Factor 0.74 0.74 0.75 0.75 0.72 0.72

Capital Cost 5,778,000 53,939,914 6,246,000 60,563,867 8,280,000 73,858,811

Capital Recovery Factor 0.094 0.094 0.094 0.094 0.094 0.094

Annualized Rate ($/yr) 545,402 5,091,546 589,578 5,716,801 781,573 6,971,749

Fixed O&M ($/year) 120,277 363,780 124,352 362,052 144,686 362,400

$/kW-yr 0.41 1.25 0.40 1.16 0.35 0.88

$/MW-yr 415 1,254 399 1,160 349 875

Variable O&M ($/year) 1,816,639 2,019,701 1,816,580 2,034,278 2,258,790 2,560,647

$/MWh 0.97 1.07 0.89 0.99 0.87 0.98

Annual O&M ($/year) 1,936,916 2,383,481 1,940,933 2,396,330 2,403,476 2,923,047

Total Annual Cost 

($/year) 2,482,318 7,475,028 2,530,511 8,113,131 3,185,049 9,894,796

Table 24 - Cholla 2, 3, and 4: EPA's Annual Emission Estimates

Control Option Percent

Emission 

Factor Heat Rate

Annual 

Capacity Emission Rate

Reduction (lb/MMBtu) (MMBtu/hr) Factor (lb/hr) (tpy)

Cholla 2

Baseline (LNB+OFA) -- 0.295 3,022 0.74 892 2,890

SNCR+LNB+OFA 30% 0.21 3,022 0.74 624 2,023

SCR+LNB+OFA 83% 0.05 3,022 0.74 151 490

Cholla 3

Baseline (LNB+OFA) -- 0.254 3,480 0.75 885 2,908

SNCR+LNB+OFA 30% 0.18 3,480 0.75 620 2,036

SCR+LNB+OFA 80% 0.05 3,480 0.75 174 572

Cholla 4

Baseline (LNB+OFA) -- 0.260 4,399 0.72 1144 3,609

SNCR+LNB+OFA 30% 0.18 4,399 0.72 801 2,526

SCR+LNB+OFA 81% 0.05 4,399 0.72 220 694
Arizona Regional Haze Technical Support Document – Page 56 of 80 

There are several aspects of our analysis of this factor that differ from ADEQ’s and APS’ 

analysis and we discuss the most important of these below. 

(1) Selection of Baseline Period 

APS’ BART analysis used a 2001-03 time period in order to establish its baseline NOx

emissions. As noted previously, the NOx control technology present on Cholla Units 2 through 4 

during that time period was close-coupled over fire air (COFA). APS has since installed lowNOx burners with separated over fire air (SOFA) on Cholla Units 2 through 4. In order to 

properly consider the second BART factor (pollution control equipment in use at the source) and 

to ensure that actual conditions at the plant were reflected in our baseline NOx emissions, we 

decided to make use of the most recent Acid Rain Program emission data reported to CAMD, 

which, at the time that we began our analysis in 2011, was the three-year period from 2008 to 

2010. Based on CAMD documentation, the low-NOx burners were installed on the Cholla units 

at different times during 2008 and 2009, making it necessary for us to clearly distinguish 

between the pre-LNB and post-LNB periods of emission data for each unit. 

The use of a 2008 to 2010 baseline was, however, complicated by the fact that the Cholla 

plant operates under a new coal contract for Lee Ranch/El Segundo coal, which is a higher NOxemitting coal than what was previously used.101 This coal contract indicates that steadily 

increasing minimum quantities of coal shall be delivered, starting with 325,000 tons in 2006 and 

up to 3,700,000 tons in 2010. This gradual transition to the newer, higher-NOx emitting coal 

source made it difficult to determine the extent to which a particular year’s emissions were 

representative of anticipated annual emissions. In the absence of more detailed fuel usage records 

on a per-unit basis, it was not possible for us to identify which units may have operated using the 

newer coal during the 2006 to 2010 transition period to the newer coal type. We note, however, 

that the coal contract specifically states that, for 2010 to 2024, no later than July 1 of each year, 

the buyer shall indicate the annual tonnage for the following calendar year, and that in no case 

shall the annual tonnage be less than 3,700,000 tons. As a result, 2011 represents the first 

complete calendar year at which we can be certain that the Cholla plant operated at the new coal 

contract’s “full” minimum purchase quantity of 3,700,000 tons per year. 

Since 2011 Acid Rain Program emission data became available during the intervening 

time between the start of our analysis and our proposed action today, we have selected 2011 as 

the time period for establishing baseline annual NOx emissions. Although this represents only a 

single year of data, we believe the use of this more recent baseline period represents the most 

realistic depiction of anticipated annual emissions, as it is the only time period that ensures each 

of the Cholla units is operating using the new coal and LNB with SOFA. 

(2) SCR Control Efficiency 

In determining the control efficiency of SCR, we have relied upon an SCR level of 

performance of 0.05 lb/MMBtu, which is more stringent than the level of performance used by 

ADEQ in its SIP. In the Cholla BART analysis submitted to ADEQ, APS indicated an SCR level 

of performance of 0.07 lb/MMBtu, but did not provide site-specific information describing how 

101 A copy of the coal contract, including obligation amounts and coal quality, can be found in Docket Item B-09, 

“Additional APS Cholla BART response”, Appendix B. 
Arizona Regional Haze Technical Support Document – Page 57 of 80 

this emission rate was developed or discussing why a more stringent 0.05 lb/MMBtu level of 

performance could not be attained. Our control cost calculations for the SCR and LNB with OFA 

control options are based upon the SCR control efficiencies summarized in Table 25. These 

control efficiencies reflect the emission reductions associated with controlling from an annual 

average baseline emission rate that represents LNB with OFA (as described previously) down to 

an SCR emission rate of 0.05 lb/MMBtu. 

Table 25 - Cholla Units 2, 3, and 4: EPA's SCR Control Efficiency

Unit Baseline 

Emission 

Rate1 

(lb/MMBtu)

SCR 

Emission 

Rate 

SCR Control 

Efficiency 

(percentage) 

Cholla 2 0.295 0.05 83% 

Cholla 3 0.254 0.05 80% 

Cholla 4 0.260 0.05 81% 

1 As noted previously, this baseline emission rate 

reflects the installation of LNB+OFA 

(3) Capacity Factor 

As noted previously, APS calculated annual emission estimates for its control scenarios, 

in tons per year, using annual capacity factors based on Acid Rain Program data from CAMD 

over a 2001 to 2006 time frame.102 The annual capacity factors APS used for each unit were 91 

percent (Cholla 2), 86 percent (Cholla 3), and 93 percent (Cholla 4). We have also calculated 

annual emission estimates for our control scenarios using capacity factors developed from 

CAMD information, but have instead used a more recent 2008 to 2011 time frame. The annual 

capacity factors we have used for each unit are 74 percent (Cholla 2), 75 percent (Cholla 3), and 

71 percent (Cholla 4). We recognize that these capacity factors are lower than those used by 

APS, and that by using these lower capacity factors, our estimates of total annual emissions (and 

correspondingly, the annual emission reductions) for each control scenario are lower than APS’ 

estimates.103 Since cost-effectiveness ($/ton) is calculated by dividing annual control costs 

($/year) by annual emission reductions (tons/year), the use of emission reductions based on 

lower capacity factors will increase the cost per ton of pollutant reduced. 

We have elected to use the capacity factors specified above, as based on a 2008 to 2011 

time frame, in order to remain consistent with the time frame used to develop baseline annual 

102 As listed in Table 2-1 in Docket Items B-06 through B-08, Cholla BART Analyses 

103 We note that there are multiple reasons why our annual emission estimates (and estimates of emission removal) 

are lower than APS’ and ADEQ’s estimates. We are not implying that the use of capacity factor is the sole, or even 

dominant, reason for this difference, simply that the use of lower capacity factors will result in lower annual 

emission estimates. 
Arizona Regional Haze Technical Support Document – Page 58 of 80 

emissions for Cholla and the other power plants that are the subject of today’s proposed 

action.104

(4) Summary of Control Costs 

A summary of our control cost estimates for the various control technology options 

considered is included in Table 26. 

Table 26 - Cholla Units 2, 3, and 4: EPA's Control Cost Summary

Control Option Emission 

Factor 

(lb/MMBtu) 

Emission 

Rate 

Emissions 

Removed 

(tpy) 

Annual Cost 

($/yr) 

Cost-effectiveness ($/ton) 

(lb/

hr) 

(tpy) Ave Incremental 

(from previous) 

Cholla 2 

OFA NA; LNB+OFA is the currently installed technology 

LNB+OFA 

(baseline) 

0.295 892 2,890 -- -- -- -- 

SNCR+LNB+OFA 0.21 624 2,023 867 2,482,318 2,863 -- 

SCR+LNB+OFA 0.05 151 490 2,400 7,475,028 3,114 3,257 

Cholla 3 

OFA NA; LNB+OFA is the currently installed technology 

LNB+OFA 

(baseline) 0.254 885 2,908 -- -- -- -- 

SNCR+LNB+OFA 0.18 620 2,036 872 2,533,432 2,904 -- 

SCR+LNB+OFA 0.05 174 572 2,337 8,113,131 3,472 3,811 

Cholla 4 

OFA NA; LNB+OFA is the currently installed technology 

LNB+OFA 

(baseline) 0.260 1144 3,609 -- -- -- -- 

SNCR+LNB+OFA 0.18 801 2,526 1,083 3,185,822 2,943 -- 

SCR+LNB+OFA 0.05 220 694 2,915 9,894,796 3,395 3,661 

104 We recognize that there are more aggressive approaches we could adopt that could justify the use of higher 

capacity factors, which would thereby lower the cost per ton of pollutant reduced. For example, instead of using 

historical data to develop a capacity factor value for each unit, we could use a single capacity factor value for each 

unit, one that represented a reasonable depiction of anticipated annual baseload operations. Alternately, we could 

also use the capacity factor estimates from APS’ Cholla BART analyses, as based on a 2001-06 time frame, or 

develop new capacity factors based on a longer 2001 to 2011 time frame. 
Arizona Regional Haze Technical Support Document – Page 59 of 80 

As indicated in Table 26, our calculations indicate that the SCR-based control options 

have average cost-effectiveness values of $3,114/ton to $3,472/ton, which falls in a range that we 

would consider cost-effective. In addition, our calculations indicate that the SCR-based control 

options have an incremental cost-effectiveness of $3,257/ton to $3,811/ton, which is also in a 

range that we would consider cost-effective. As a result, our analysis of this factor indicates that 

the costs of compliance (average or incremental) are not sufficiently large to warrant eliminating 

any of the control options from consideration.

b) Visibility Improvement

The overall visibility modeling approach was described above; aspects of the modeling 

specific to Cholla are described here. EPA made a NOx BART determination for Cholla Units 2, 

3 and 4, but Unit 1 (which is not BART-eligible) was also included in the modeling runs for 

greater realism in assessing the full facility’s visibility impacts. For Unit 1’s NOx emissions, the 

maximum daily emissions from EPA's CAMD database for 2008 to 2010 were used; the 

maximum occurred in early 2008. LNBs were installed on Units 2 and 4 early in 2008, and on 

Unit 3 in mid-2009; for a realistic base case, the baseline emissions used for these units were the 

maximum daily emissions in lb/hr from 2008-2010 occurring after the respective LNB 

installation dates. The maximum for unit 2 occurred in mid-2009, and the maxima for Units 2 

and 3 occurred in late 2010. The base case reflects LNB as the control in place. 

EPA evaluated SNCR (including LNB) and SCR (including LNB) applied to Units 2, 3 

and 4. SCR was assumed to give a control effectiveness of 83 percent, 80 percent, and 81 percent 

for units 2, 3 and 4, respectively (less than 90 percent due to the 0.05 lb/MMBtu NOx lower limit 

assumed for SCR). For Cholla, the increase in sulfuric acid due to SCR was not simulated, 

because the baghouse (fabric filter) installed for particulate matter control would reduce this 

increased sulfate by 99 percent, resulting in a negligible effect on the visibility estimate. The 13 

Class I areas within 300 km of Cholla were modeled; they are in the states of Arizona, Colorado, 

New Mexico, and Utah. The 98th percentile delta deciview using all three years of data together 

was computed for each area and emission scenario. 

Table 27105 and Table 28 show baseline visibility impacts and the visibility improvement 

when controls are applied; the various table entries are described above in the discussion of the 

comparable tables for Apache Generating Station. The area with the greatest dv improvement 

was the Petrified Forest National Park; the improvement from SNCR was just under 0.5 dv and 

from SCR was 1.3 dv. Either of these improvements would contribute to improved visibility, 

with SCR being the superior option for visibility. The corresponding cumulative improvements 

are 2.7 and 7.2. Only SCR gives improvements exceeding 0.5 dv, and it does so at eight areas, 

two of which have improvements above a full 1 dv. The number of days per year with impacts 

above 0.5 dv decreases by 7 for SNCR, and by 21 for SCR (considering the area where the 

105 The deciview impacts are copied from the spreadsheet “AZRHFIP_TSD_vis_summ_tables.xlsx”, which in turn 

relies on the spreadsheet “cho_az_unit2-3_dollarperdv_analysis_finalwithplots2.xls” prepared by UNC. The costs 

used in $/dv rely on the spreadsheet “EGU BART Costs_Apache_Cholla_Coronado_FINAL2.xlsx” also prepared by 

UNC. Note that the costs in the latter are slightly different than those in the cost tables in this TSD, which as noted 

above do not include property tax and insurance. The number of days above 0.5 and 1.0 dv are from the spreadsheet 

“AZRHFIP_TSD_Cholla_visx.xlsx”. 
Arizona Regional Haze Technical Support Document – Page 60 of 80 

decrease is the greatest, Mesa Verde). The modeled degree of visibility improvements supports 

SCR as BART for Cholla.

Table 27 - Cholla Units 2, 3, and 4: EPA's Visibility Improvement from NOx Controls

base ctrl1_r ctrl2_r2 

Class I Area Baseline 

impact 

(dv) 

Improvement 

from SNCR 

(dv) 

Improvement 

from SCR 

(dv) 

Capitol Reef NP 1.46 0.27 0.76 

Galiuro WA 0.45 0.05 0.14 

Gila WA 0.70 0.09 0.22 

Grand Canyon NP 2.22 0.37 1.06 

Mazatzal WA 1.19 0.16 0.43 

Mesa Verde NP 1.34 0.26 0.70 

Mount Baldy WA 1.21 0.27 0.52 

Petrified Forest NP 4.53 0.47 1.34 

Pine Mountain WA 0.85 0.12 0.31 

Saguaro NP 0.30 0.02 0.05 

Sierra Ancha WA 1.36 0.20 0.51 

Superstition WA 1.27 0.17 0.51 

Sycamore Canyon WA 1.42 0.27 0.68 

Cumulative dv 18.30 2.71 7.21 

# areas >= 0.5 11 0 8 

Max. area number of days 

>= 0.5 dv

252 7 21 

Max. area number of days 

>= 1.0 dv

213 8 29 

$/max dv, millions $17.8 $20.8 

$/cumulative dv, millions $3.1 $3.8 

Table 28 - Cholla Units 2, 3, and 4: EPA's Visibility Improvement Days from NOx Controls

base ctrl1_r ctrl2_r2 

Class I Area Baseline 

impact (days) 

Improvement 

from SNCR 

(days) 

Improvement 

from SCR 

(days) 

Capitol Reef NP 19 1 8 

Galiuro WA 5 1 3 

Gila WA 17 4 10 

Grand Canyon NP 28 3 9 

Mazatzal WA 35 5 16 

Mesa Verde NP 33 7 21 

Mount Baldy WA 29 4 14 

Petrified Forest NP 252 6 20 

Pine Mountain WA 19 4 11 

Saguaro NP 4 2 3 

Sierra Ancha WA 41 5 16 

Superstition WA 26 3 10 

Sycamore Canyon WA 24 5 12 

Cumulative #days >= 0.5 530 50 152 
Arizona Regional Haze Technical Support Document – Page 61 of 80 

c) EPA’s BART Determination

As noted above, the remaining useful life of the source is incorporated into control cost 

calculations as a 20-year amortization period. In addition, the presence of existing pollution 

control technology is reflected in the cost and visibility factors as a result of selection of the 

baseline period for cost calculations and visibility modeling. For Cholla Units 2, 3, and 4, a 

baseline period (2011) was selected that reflects the currently existing pollution control 

technology (LNB with OFA). In examining energy and non-air quality impacts, we note certain 

potential impacts resulting from the use of ammonia injection associated with the SNCR and 

SCR control options, but do not consider these impacts sufficient enough to warrant eliminating 

any of the available control technologies. 

Our consideration of degree of visibility improvement focuses primarily on the 

improvement from base case impacts associated with each control option. While each of the 

available NOx control options achieves some degree of visibility improvement, we consider the 

improvement associated with the most stringent option, SCR with LNB and OFA, to be 

substantial. 

Our consideration of cost of compliance focuses primarily on the cost-effectiveness of 

each control option, as measured in cost per ton and incremental cost per ton of each control 

option. Despite the fact that the most stringent option, SCR with LNB and OFA, is the most 

expensive of the available control options, we consider it cost-effective on average basis as well 

as on an incremental basis when compared to the next most stringent option, SNCR with LNB 

and OFA. 

As a result, we consider the most stringent available control option, SCR with LNB and 

OFA, to be both cost-effective and to result in substantial visibility improvement, and that the 

energy and non-air quality impacts are not sufficient to warrant eliminating it from consideration. 

Therefore, we propose to determine that NOx BART for Cholla Units 2, 3, and 4 is SCR with 

LNB and OFA, with an associated emission limit for NOx on each of Units 2, 3, and 4 of 0.050 

pounds per million British thermal units (lb/MMBtu), based on a rolling 30-boiler-operating-day 

average. 

3. Coronado Units 1 and 2

a) Costs of Compliance

Our general approach to calculating the costs of compliance is described in section 

III.A.1 above, while considerations unique to Coronado Units 1 and 2 are explained herein. As 

mentioned in the Federal Register notice for this proposal, control costs were developed by our 

contractor using the Integrated Planning Model (IPM) Base Case v4.10 (August 2010). The 

specific parameters and assumptions used in developing these costs are included in our 

contractor’s report and its associated spreadsheet. A summary of capital and operating costs is 

included in Table 29.
Arizona Regional Haze Technical Support Document – Page 62 of 80 

Table 29 - Coronado 1 and 2: EPA's Control Cost Estimates

Coronado 1 Coronado 2

SNCR SCR 

SCR (0.08 

lb/MMBtu)

SCR (0.05 

lb/MMBtu)

Unit Output (MW) 411 411 411 411

Capacity Factor 0.81 0.81 0.89 0.89

Capital Cost 8,218,000 56,980,624 53,330,450 53,416,253

Capital Recovery Factor 0.094 0.094 0.094 0.094

Annualized Rate ($/yr) 775,721 5,378,568 5,034,017 5,042,116

Fixed O&M ($/year) 144,105 362,488 362,488 362,488

$/kW-yr 0.35 0.88 0.88 0.88

$/MW-yr 351 882 882 882

Variable O&M ($/year) 2,905,730 3,574,257 3,325,130 3,588,511

$/MWh 1.00 1.23 1.04 1.12

Total Annual O&M ($/year) 3,049,835 3,936,745 3,687,619 3,950,999

Total Annual Cost ($/year) 3,825,556 9,315,313 8,721,636 8,993,116

The capital recovery factor (0.094) listed above is based upon an interest rate of 7% over 

a 20 year equipment lifetime. Please note that this value does not include property tax (0.90%) 

and insurance (0.30%), which were included by our contractor in their calculation of capital 

recovery factor. As a result, the annualized rate ($/yr) and total annual cost ($/yr) listed in the 

table above are lower than the cost values summarized in our contractor’s cost calculation 

deliverable.106 Estimates of the annual emission rates used in cost calculations are summarized in 

Table 30. 

106 See Appendix C of WA5-12 Task 8 Deliverable (Apache-Cholla-Coronado BART Analysis Report).docx 
Arizona Regional Haze Technical Support Document – Page 63 of 80 

Table 30 - Coronado 1 and 2: EPA's Annual Emission Estimates

Control Option Percent

Emission 

Factor Heat Rate

Annual 

Capacity Emission Rate

Reduction (lb/MMBtu) (MMBtu/hr) Factor (lb/hr) (tpy)

Coronado 1

Baseline (LNB+OFA) -- 0.303 4,316 0.81 1,308 4,639

SNCR+LNB+OFA 30% 0.21 4,316 0.81 915 3,248

SCR+LNB+OFA 83% 0.05 4,316 0.81 216 766

Coronado 2

SCR (0.08 lb/MMBtu) -- 0.08 3,984 0.89 319 1,242

SCR (0.05 lb/MMBtu) -- 0.05 3,984 0.89 199 776

There are several aspects of our analysis of this factor that differ from ADEQ’s and SRP’s 

analysis and we describe the most important elements below. 

(1) Selection of Baseline Period and Baseline Control

Technology

SRP’s BART analysis used a 2001-03 time period in order to establish its baseline NOx

emissions. Since that time period, SRP has since installed LNB with OFA on Coronado Units 1 

and 2. In order to ensure that actual conditions at the plant are reflected in our baseline NOx

emissions, we decided to make use of the most recent Acid Rain Program emission data reported 

to CAMD, which, at the time that we began our analysis in 2011, was the three-year period from 

CY2008-10. Based on CAMD documentation, the low-NOx burners were installed on Coronado 

Unit 1 on May 16, 2009, making it necessary for us to clearly distinguish between the pre-LNB 

and post-LNB periods of emission data for Coronado Unit 1. In our analysis, we have decided to 

make use of CAMD emission data corresponding to the post-LNB period extending from May 

16, 2009 to December 31, 2010. We believe the use of this more recent baseline period 

represents the most realistic depiction of anticipated annual emissions, as it reflects operation of 

Coronado Unit 1 with LNB and OFA. 

For Coronado Unit 2, we note that a consent decree between SRP and EPA requires the 

installation of SCR and compliance with an emission limit of 0.080 lb/MMBtu (30-day rolling 

average) by June 1, 2014.107 Although we realize this SCR system has not yet been installed on 

Coronado Unit 2, this limit is federally enforceable and represents a realistic depiction of 

anticipated future emissions.108 As a result, we consider 0.080 lb/MMBtu to be the baseline 

emission rate in our BART analysis and are examining only one control scenario in our analysis 

for Unit 2, SCR at a more stringent emission rate of 0.050 lb/MMBtu.

109

107 See Docket Item G-01, “Consent Decree Between U.S. and SRP (final as entered).” See also ADEQ Title V 

Permit Renewal Number 52639, SRP – Coronado Generating Station, section II.E.1.a.iii (December 06, 2011). 

108 See 40 CFR Part 51, Appendix Y, Section IV.D.4.d. 

109 A discussion of our rationale for considering SCR at an emission rate of 0.05 lb/MMBtu can be found in Section 

VII.A.2 (Control Effectiveness) of this notice. 
Arizona Regional Haze Technical Support Document – Page 64 of 80 

(2) SCR Control Efficiency 

In determining the control efficiency of SCR in our BART analysis, we have relied upon 

an SCR level of performance of 0.05 lb/MMBtu, which is more stringent than the level of 

performance used by ADEQ in its SIP, or by SRP in its Coronado BART analysis. In the 

Coronado BART analysis submitted to ADEQ, SRP indicated an SCR level of performance of 

0.08 lb/MMBtu, and noted that “If inlet NOx concentrations are less than 250 ppmvd, SCR can 

achieve NOx control efficiencies ranging only from 70 to 80 percent.”110 Our control cost 

calculations for the SCR control option at Coronado Unit 1 are based upon the SCR control 

efficiency summarized in Table 31. This control efficiency reflects the emission reductions 

associated with controlling from an annual average baseline emission rate that represents 

LNB+OFA (as described previously) down to an SCR emission rate of 0.05 lb/MMBtu. 

Table 31 - Coronado Unit 1: EPA's SCR Control Efficiency

Unit No. Baseline 

Emission 

Rate 

(lb/MMBtu) 

SCR 

Emission 

Rate 

SCR 

Control 

Efficiency 

(percentage) 

Coronado 1 0.303 0.05 83.5% 

(3) Capacity Factor 

SRP did not calculate annual emission estimates for its control scenarios, in tons per year, 

in its BART analysis submitted to ADEQ. In developing its RH SIP, ADEQ estimated annual 

emission reductions based upon 8,760 hours/year of operation (i.e., 100 percent capacity factor). 

We have calculated annual emission estimates for our control scenarios using capacity factors 

developed over a CY2008-11 time frame. The annual capacity factors we have used for each unit 

are 81 percent (Coronado 1), and 89 percent (Coronado 2). We recognize that these capacity 

factors are lower than those used by ADEQ, and that by using these lower capacity factors, our 

estimates of total annual emissions (and correspondingly, the annual emission reductions) for 

each control scenario are lower than ADEQ’s estimates.

111 Since cost-effectiveness ($/ton) is 

calculated by dividing annual control costs ($/year) by annual emission reductions (tons/year), 

the use of emission reductions based on lower capacity factors will increase the cost per ton of 

pollutant reduced. 

We have elected to use the capacity factors specified above, as based on a 2008 to 2011 

time frame, in order to remain consistent with the time frame used to develop baseline annual 

emissions for Coronado and the other power plants that are the subject of today’s proposed 

action.

112

110 See Docket Item B-10, SRP Coronado BART Analysis, page 4-5 

111 We note that there are multiple reasons why our annual emission estimates (and estimates of emission removal) 

are lower than AEPCO’s and ADEQ’s estimates. We are not implying that the use of capacity factor is the sole, or 

even dominant, reason for this difference, simply that the use of lower capacity factors will result in lower annual 

emission estimates. 

112 We recognize that there are more aggressive approaches we could adopt that could justify the use of higher 

capacity factors, which would thereby lower the cost per ton of pollutant reduced. For example, instead of using 
Arizona Regional Haze Technical Support Document – Page 65 of 80 

(4) Summary and Conclusions Regarding Costs of Control 

A summary of our control cost estimates for the various control technology options considered 

for Coronado Units 1 and 2 is in Table 32.

Table 32 - Coronado Units 1 and 2: EPA's Control Cost Summary

Control Option 

Emission 

Factor 

(lb/MMBtu) 

Emission Rate Emissions 

Removed 

(tpy) 

Annual 

Cost 

($/yr) 

Cost-effectiveness ($/ton) 

(lb/hr) (tpy) Average Incremental 

(from previous) 

Coronado 1 

OFA NA; LNB+OFA is the currently installed technology 

LNB+OFA (baseline) 0.303 1,308 4,639 -- -- -- -- 

SNCR+LNB+OFA 0.21 915 3,248 1,392 3,825,556 2,749 -- 

SCR+LNB+OFA 0.05 216 766 3,874 9,315,313 2,405 2,212 

Coronado 2 

SCR@0.08 

lb/MMBtu 

(baseline) 

0.08 319 1,242 -- 8,721,6361-- -- 

SCR@0.05 

lb/MMBtu 0.05 199 776 466 8,993,116 -- 583 

1 Annual cost for the baseline scenario is provided here only to allow calculation of the 

incremental cost associated with a control option of SCR@0.05 lb/MMBtu. 

For Coronado 1, our calculations indicate that the SCR-based control option has an 

average cost-effectiveness value of $2,405/ton and an incremental cost-effectiveness of 

$2,212/ton, both of which we consider cost-effective. As described further below, our analysis 

for Coronado 2 relied upon SCR at an emission rate of 0.08 lb/MMBtu as a baseline scenario. As 

a result, the only control option we examined for Coronado 2 was an SCR-based option at a more 

stringent level of performance, 0.05 lb/MMBtu. Our initial analysis indicates that the incremental 

cost-effectiveness of such an option is $583/ton, making it a control option that we would 

consider cost-effective. However, we received information from SRP indicating that design and 

construction of the SCR system for this unit are well under way. In its letter, SRP states that “if 

SRP were required to abandon the current design, incur procurement losses, possibly remove 

foundations, and undertake new design and procurement, such steps would vastly increase the 

cost of the SCR retrofit.” Since these types of additional costs were not factored into our original 

analysis, the average and incremental cost-effectiveness of requiring Coronado Unit 2 to meet an 

emissions limit of 0.050 lb/MMBtu may in fact be greater than indicated by our analysis. 

historical data to develop a capacity factor value for each unit, we could use a single capacity factor value for each 

unit, one that represented a reasonable depiction of anticipated annual baseload operations. Alternately, we could 

also use a 100% capacity factor, or develop new capacity factors based on a longer 2001 to 2011 time frame. 
Arizona Regional Haze Technical Support Document – Page 66 of 80 

However, we intend to request further documentation in order to determine the extent of these 

costs and how they would affect our cost-effectiveness calculations. We will include all non-CBI 

material received in the docket for this action and will consider it as part of our final action. We 

are specifically interested in information from SRP concerning the number of layers of catalyst 

for the SCR at Unit 2, how they plan to manage replacement of the catalyst, and whether the 

catalyst could be installed and managed to allow Unit 2 to meet a lower emission limit than 0.08 

lb/MMBtu. 

Thus, our initial analysis of this factor indicates that the costs of compliance (average or 

incremental) are not sufficiently large to warrant eliminating any of the control options from 

consideration. However, we note that, based on preliminary information received from SRP, the 

average and incremental costs of achieving an emission rate of 0.050 lb/MMBtu at Unit 2 may 

be greater than our initial analysis suggests. 

b) Visibility Improvement

The overall modeling approach was described above; aspects of the modeling specific to 

Coronado are described here. LNB was installed on Unit 1 in mid-2009, and on Unit 2 in mid2011. For Unit 1’s NOx emissions, the maximum daily emissions in EPA’s CAMD database for 

2008 to 2010 was used; the maximum post-LNB installation emissions occurred in late 2010. For 

unit 2 emissions, the consent decree-mandated NOx emission limit of 0.08 lb/MMBtu was 

combined with the maximum heat rate from 2008-2010 CAMD data, which occurred in late 

2008. Since this limit has a 30-day averaging time, daily emissions may be larger than the 

emissions EPA modeled; the emission and visibility benefit would also be larger. Thus, visibility 

benefits from control applied to the base case may actually be larger than presented here. The 

base case reflects LNB as the control in place on Unit 1, and SCR at 0.08 lb/MMBtu NOx on 

Unit 2. 

EPA evaluated SNCR applied to Unit 1 (“ctrl1_r”), SCR at 0.05 lb/MMBtu on unit 1 

but at 0.08 on unit 2 (“ctrl2_r”) and SCR at 0.05 lb/MMBtu applied to both Units 1 and 2 

(“ctrl5_rs”). SCR was assumed to give a control effectiveness of 83.5 percent for unit 1 (less 

than 90 percent due to the 0.05 lb/MMBtu NOx lower limit assumed for SCR). SCR at 0.05 

lb/MMBtu NOx was assumed to give a control effectiveness of 37.5 percent over the base case 

0.08 lb/MMBtu. As mentioned above, the SCR simulation (“ctrl5_rs”) accounted for the 

increase in sulfuric acid emissions due to catalyst oxidation of SO2 at Unit 2. However, 

originally, the other simulations did not account for this effect. If this additional Unit 2 sulfate 

were accounted for, it could make some background ammonia unavailable to form visibilityaffecting particulate from Unit 1’s NOx emissions, thus reducing the visibility impact and also 

the visibility benefit of controls. We expected this to have very little effect on the estimated 

SNCR visibility benefit, since it was computed relative to an alternative base case that likewise 

did not include the catalyst oxidation effect, but the visibility benefits from SNCR could have 

been slightly less than originally thought. EPA subsequently accounted for this effect by 

simulating the increased sulfate from SCR for the SNCR scenario (“ctrl1_rs”, SNCR on unit 

1, SCR on unit 2), and the scenario with SCR on both units at different control levels 

(“ctrl2_rs”, 0.05 lb/MMBtu for Unit 1, and 0.08 lb/MMBtu for Unit 2). This language in the 

NPRM reflects the situation before these subsequent simulations. However, the updated results 
Arizona Regional Haze Technical Support Document – Page 67 of 80 

fully accounting for SCR catalyst oxidation are reported in the NPRM visibility impact tables, 

and were considered in EPA’s decision-making. 

The emissions basis for these additional simulations is briefly described here, since they 

are not elsewhere documented; they are revised versions of “ctrl1_r” and “ctrl2” covered 

in the UNC report. 

· Scenario “ctrl1_rs” for SNCR on Unit 1 is the same as UNC’s “ctrl1_r”, except 

it includes the added SCR catalyst sulfate for Unit 2. The amount of sulfate added was 

the same as for Unit 2 in “base_rs”. 

· Scenario “ctrl2_rs” for SCR at 0.05 lb/MMBtu on Unit 1 and SCR at 0.08 

lb/MMBtu on Unit 2 is similar to UNC’s “ctrl2”. However, it starts from the revised 

base case using post-LNB installation emissions before applying the 83.5% reduction to 

Unit 1; it also includes the added SCR catalyst sulfate for both units. Thus, Unit 1 

emissions are the same as in “ctrl5_rs”, and Unit 2 emissions are the same as in 

“base_rs”. 

· An additional scenario “ctrl6_rs” portrays SCR at 90% control relative to post-LNB 

installation emissions. For Unit 1, the starting point was “base_rs” (CAMD maximum 

NOx emissions on 11/3/2010 of 16.6 tons/day or 33,208 lb/day; this is 174.3 g/s), 

reduced by 90% to 17.53 g/s for modeling. For Unit 2, the starting point was not 

available from other simulations, which were based directly on 0.08 or 0.05 lb/MMBtu 

NOx. So, the CAMD maximum NOx emissions on 6/2/2011 of 18.859 tons/day were 

used. This is 33,718 lb/day or 198.02 g/s; reducing by 90% gives 19.80 g/s for modeling. 

For both units, the added SCR catalyst sulfate was taken from “ctrl5_rs” (the 

scenario with 0.05 lb/MMBtu on both units). 

Sixteen Class I areas within 300 km of Coronado were modeled; they are in the states of 

Arizona, Colorado, and New Mexico. A 17th area, the Bosque del Apache Wilderness Area in 

New Mexico, was inadvertently omitted from modeling performed by UNC for EPA. Since it is 

in the same general direction from Coronado as the Gila Wilderness Area, but farther away, 

visibility impacts and control benefits at Bosque del Apache are likely to be lower than for Gila, 

so the maximum dv benefit would not be affected by this omission. EPA verified this by 

simulating all the control scenarios for Bosque del Apache; the results for this area are included 

in the tables below, although they were not part of EPA’s decision process in developing the 

NPRM. However, the cumulative impacts and benefits would be higher than reported here since 

Bosque del Apache is omitted from the sum. The 98th percentile delta deciviews over all three 

years of data were computed for each area and emission scenario. 

Table 33 and Table 34113 show baseline visibility impacts and the visibility 

improvement114when controls are applied; the various table entries are described above in the 

113 The deciview impacts are copied from the spreadsheet “AZRHFIP_TSD_vis_summ_tables.xlsx”, which in turn 

relies on the spreadsheet “srp_az_unit2-3_dollarperdv_analysis_finalwithplots2.xls” prepared by UNC. The costs 

used in $/dv rely on the spreadsheet “EGU BART Costs_Apache_Cholla_Coronado_FINAL2.xlsx” also prepared by 

UNC. Note that the costs in the latter are slightly different than those in the cost tables in this TSD, which as noted 

above do not include property tax and insurance. The number of days above 0.5 and 1.0 dv are from the spreadsheet 

“AZRHFIP_TSD_Coronado_visx.xlsx”. 
Arizona Regional Haze Technical Support Document – Page 68 of 80 

discussion of the comparable table for Apache. EPA is proposing SCR at 0.05 lb/MMBtu on 

Unit 1 and SCR at 0.08 lb/MMBtu on Unit 2, shown as scenario “ctrl2_rs”. The area with the 

greatest dv improvement was the Gila Wilderness Area; there is an improvement of 0.2 dv from 

SNCR (ctrl1_rs), 0.7 dv from SCR on unit 1 (ctrl2_rs), and 0.9 dv from SCR at 0.05 lb/MMBtu 

on both units (ctrl5_rs). These improvements are smaller than for the other facilities because the 

benefit from SCR at 0.08 lb/MMBtu on unit 2 is subsumed in the baseline. The cumulative 

improvements corresponding to the three control scenarios are 1.0 dv, 2.8 dv, and 3.1 dv. The 

number of days per year with impacts above 0.5 dv decreases by 6 for SNCR on unit 1, by 16 for 

SCR on unit 1, and by 18 for SCR on both units at 0.05 lb/MMBtu NOx (considering the area 

where the decrease is the greatest, Gila Wilderness Area). The modeled degree of visibility 

improvements supports either SCR scenario as BART for Coronado.

Under baseline conditions the maximum number of days per year with impacts above 0.5 

dv seen at any area is 28 (“Max. area” in Table 33; see additional explanation of this table row in 

the section on Apache visibility improvement). For SNCR (ctrl1_rs), this maximum decreases by 

6, leaving 22 days over 0.5 dv. For EPA’s proposed BART, SCR of 0.05 lb/MMBtu on unit 1 

and 0.08 lb/MMBtu on Unit 2 (ctrl2_rs), it decreases by 16, leaving 12 days over. The decrease 

is slightly more at 18 for SCR on both units at 0.05 lb/MMBtu NOx (ctrl5_rs), leaving 10 days 

over 0.5 dv. 

Table 34 shows the number of days with impairment exceeding 0.5 dv, for each Class I 

area (instead of the maximum among any area that is shown in Table 33), as well as the 

cumulative number of days (sum over the areas). For the baseline condition, Petrified Forest has 

the largest number of such days, the baseline 28 appearing in Table 33. However Gila 

Wilderness Area is has the greatest improvement for all the control scenarios, so its row has the 

same entries as the maximum “Max. area number of days >= 0.5 dv” in Table 33. 

Any of these improvements would contribute to improved visibility, though SNCR on 

unit 2 only marginally so. SCR is the superior option for visibility, with the more stringent SCR 

at 0.05 lb/MMBtu on unit 2 giving a slightly greater benefit than when that limit is applied only 

to unit 1. Only the SCR scenarios give improvements exceeding 0.5 dv. The modeled degree of 

visibility improvements supports either SCR scenario as BART for Coronado. 

114 The table below differs from the corresponding one in the NPRM due to the NPRM’s use of the 23rd high over 

the 2001-2003 period as the 98th percentile visibility impact for the ctrl1_rs and ctrl2_rs scenarios. The table below 

relies on the 22nd high throughout, in accord with standard practice. The changes to the estimates of visibility 

benefit were very small, and the results continue to support EPA’s proposed BART determination. 
Arizona Regional Haze Technical Support Document – Page 69 of 80 

Table 33 - Coronado Units 1 and 2: EPA's Visibility Improvements from NOx Controls

base_rs ctrl1_rs ctrl2_rs ctrl5_rs ctrl6_rs 

Class I Area Baseline 

impact 

(dv) 

Improvement 

from SNCR 

on unit 1 (dv) 

Improvement 

from SCR .05 

on unit 1 (dv) 

Improvement from SCR .05 

on (dv) 

Improvement 

from SCR -

90% on both 

(dv) 

Bosque del 

Apache * 

0.47 0.08 0.20 0.23 0.25 

Bandelier NM 0.37 0.07 0.18 0.20 0.22 

Chiricahua NM 0.20 0.03 0.07 0.08 0.09 

Chiricahua WA 0.21 0.03 0.07 0.09 0.09 

Galiuro WA 0.20 0.02 0.08 0.09 0.09 

Gila WA 1.23 0.22 0.59 0.66 0.73 

Grand Canyon NP 0.24 0.03 0.09 0.11 0.12 

Mazatzal WA 0.20 0.01 0.06 0.07 0.08 

Mesa Verde NP 0.40 0.07 0.19 0.20 0.23 

Mount Baldy WA 0.87 0.16 0.42 0.44 0.50 

Petrified Forest 

NP 

1.22 0.17 0.47 0.56 0.63 

Pine Mountain 

WA 

0.14 0.02 0.04 0.05 0.06 

Saguaro NP 0.12 0.01 0.03 0.04 0.04 

San Pedro Parks 

WA 

0.54 0.11 0.28 0.30 0.34 

Sierra Ancha WA 0.24 0.03 0.06 0.07 0.08 

Superstition WA 0.21 0.02 0.06 0.06 0.07 

Sycamore Canyon 

WA 

0.16 0.01 0.05 0.06 0.07 

Cumulative dv 6.54 1.02 2.74 3.07 3.43 

# areas >= 0.5 4 0 1 2 2 

Max. area number 

of days >= 0.5 dv 

28 6 16 18 20 

Max. area number 

of days >= 1.0 dv 

10 2 8 8 10 

$/max dv, millions $17.7 $16.3 $15.0 $13.5 

$/cumulative dv, 

millions 

$3.9 $3.5 $3.2 $2.9 

* Bosque del Apache is NOT included in cumulative totals above: its simulations were not part of EPA decisionmaking for the NPRM 

Note: Costs of implementing SCR at 0.08 lb/MMBtu on unit 2 are not included. 
Arizona Regional Haze Technical Support Document – Page 70 of 80 

Table 34 - Coronado Units 1 and 2: EPA's Visibility Improvement Days 

from NOx Controls

base_rs ctrl1_rs ctrl2_rs ctrl5_rs ctrl6_rs 

Class I Area Baseline 

impact 

(dv) 

Improvement 

from SNCR 

on unit 1 

(dv) 

Improvement 

from SCR 

.05 on unit 1 

(dv) 

Improvement 

from SCR 

.05 on both 

(dv) 

Improvement 

from SCR -

90% on both 

(dv) 

Bosque del Apache * 6 1 5 5 6 

Bandelier NM 3 2 3 3 3 

Chiricahua NM 1 1 1 1 1 

Chiricahua WA 2 1 2 2 2 

Galiuro WA 2 1 1 2 2 

Gila WA 27 6 16 18 20 

Grand Canyon NP 3 1 2 2 3 

Mazatzal WA 1 1 1 1 1 

Mesa Verde NP 6 1 5 6 6 

Mount Baldy WA 17 2 12 13 15 

Petrified Forest NP 28 4 13 15 18 

Pine Mountain WA 0 0 0 0 0 

Saguaro NP 1 0 0 1 1 

San Pedro Parks WA 8 4 8 8 8 

Sierra Ancha WA 2 1 1 2 2 

Superstition WA 0 0 0 0 0 

Sycamore Canyon WA 0 0 0 0 0 

Cumulative #days >= 

0.5 

100 24 67 74 80 

* Bosque del Apache is NOT included in the cumulative totals above: its simulations were not part of EPA decisionmaking for the NPRM. 

c) EPA’s BART Determination

As noted above, we have considered the remaining useful life of the source by 

incorporating a 20-year amortization period into our control cost calculations. The presence of 

existing pollution control technology is reflected in the cost and visibility factors as a result of 

selection of the baseline period for cost calculations and visibility modeling. For Coronado Unit 

1, a baseline period (May 2009 to December 2010) was selected that reflects the currently 

existing pollution control technology (LNB with OFA). For Coronado Unit 2, a baseline of 0.080 

lb/MMBtu was selected to reflect the requirements of the consent decree decribed above. In 

addition, as noted above, we have received information from SRP indicating that the design and 

construction of SCR at Unit 2 have aleady progressed significantly. To the extent that we receive 

additional documentation establishing the status of this effort, we will take this information into 

consideration under the factors of “costs of compliance” and “existing controls.” 

In examining energy and non-air quality impacts, we note certain potential impacts 

resulting from the use of ammonia injection associated with the SNCR and SCR control options, 

but do not consider these impacts sufficient enough to warrant eliminating any of the available 

control technologies. 
Arizona Regional Haze Technical Support Document – Page 71 of 80 

Our consideration of degree of visibility improvement focuses primarily on the 

improvement from base case impacts associated with each control option. While each of the 

available NOx control options achieves some degree of visibility improvement, we consider the 

improvement associated with the most stringent option, SCR with LNB and OFA, to be 

substantial. Our consideration of cost of compliance focuses primarily on the cost-effectiveness 

of each control option, as measured in cost per ton and incremental cost per ton of each control 

option. Despite the fact that the most stringent option, SCR with LNB and OFA, is the most 

expensive of the available control options, we consider it cost-effective on average basis as well 

as on an incremental basis when compared to the next most stringent option, SNCR with LNB 

and OFA. 

As a result, we consider the most stringent available control option, SCR with LNB and 

OFA, to be cost-effective and to result in substantial visibility improvement, and that the energy 

and non-air quality impacts are not sufficient to warrant eliminating it from consideration. 

Therefore, we propose to determine that NOx BART for Coronado Units 1 and 2 is SCR with 

LNB and OFA. At Unit1 we propose an emission limit for NOx of 0.050 lb/MMBtu, based on a 

rolling 30-boiler-operating-day average. 

At Unit 2, we propose an emission limit of 0.080 lb/MMBtu, which is consistent with the 

emission limit in the consent decree. We acknowledge that the emission limit of 0.080 

lb/MMBtu established in the consent decree was not the result of a BART five-factor analysis, 

nor does the consent decree indicate that SCR at 0.080 lb/MMBtu represents BART. 

Nonetheless, given the compliance schedule established in the consent decree and the 

preliminary information received from SRP regarding the status of design and construction of the 

SCR system, it appears that achieving a 0.050 lb/MMBtu emission rate may not be technically 

feasible. Even if it is feasible, achievement of this emission rate may not be cost-effective. 

Therefore, we are proposing an emission limit of 0.080 lb/MMBtu as BART for NOx at Unit 2. 

However, if we do not receive sufficient documentation establishing that achievement of a more 

stringent limit is infeasible or not cost-effective, then we may determine that a more stringent 

limit for this unit is required in our final action. 

For Coronado Unit 2, we are proposing a compliance date of June 1, 2014 for the NOx

limit, consistent with the consent decree described above. 

Finally, at Coronado Unit 1, we are proposing to require compliance with the NOx limit 

within five years of final promulgation of this FIP consistent with the compliance times for the 

NOx limits at the other units. However, we are seeking comment on whether a shorter 

compliance schedule may be practicable for this unit. 

C. Enforceability Requirements

In order to meet the requirements of the RHR and the CAA and to ensure that the BART 

limits are practically enforeceable, we propose to include the following elements in the FIP: 

1. Requirements for use of continuous emission monitoring systems (CEMS) (and associated 

quality assurance procedures) to determine compliance with NOx and SO2 limits. 
Arizona Regional Haze Technical Support Document – Page 72 of 80 

2. Use of 30-day rolling averaging period and definition of boiler operating day, consistent with 

the BART Guidelines for NOx and SO2. 

3. Requirements for annual performance stack tests and implementation of Compliance 

Assurance Monitoring (CAM) plan to establish compliance with PM emission limits. 

4. Recordkeeping and reporting requirements. 

5. Requirement to maintain and operate the unit including associated air pollution control 

equipment in a manner consistent with good air pollution control practices for minimizing 

emissions. 

The foregoing requirements would apply to all units. 

In addition, we are proposing specific compliance deadlines for each of ADEQ’s BART 

emissions limits that we are proposing to approve. In most instances, the control technologies 

required to meet these limits have already been installed. (See Table 3.) Therefore, we are 

proposing to require compliance with the applicable emissions limits for PM and SO2 within 180 

days of final promulgation of this FIP, except that at Cholla Unit 2, we propose to require 

compliance with the PM limit by January 1, 2015, consistent with ADEQ’s BART 

determination. 

Regarding NOx, we propose to allow up to five years from final promulgation of this FIP 

for each unit subject to an emission limit consistent with SCR, with the exception of Coronado 

Unit 2. This proposal is based on the results of two analyses of SCR installation times, as 

summarized in EPA Region 6’s Complete Response to Comments for NM Regional 

Haze/Visibility Transport FIP.115 An analysis performed by EPA Region 6, based on a review of 

a number of sources, found that the design and installation of SCR took between 18 and 69 

months. A separate analysis performed for the Utility Air Regulatory Group (UARG) found that 

it took 28 to 62 months to design and install the 14 SCRs in its sample.116 In the case of the 

BART FIP for San Juan Generating Station, EPA Region 6 initially proposed to allow a threeyear compliance time frame for design and installation of SCR, but ultimately allowed for a fiveyear compliance schedule.117 We also note that SCR installations often trigger Prevention of 

Significant of Deterioration permitting requirements because they constitute physical changes to 

an existing emission unit that may result in increased emissions of sulfuric acid mist. Therefore, 

we are proposing a five-year compliance time frame, which would provide adequate time for 

SCR design and installation based on the high-end of the range of dates in the analyses cited 

above. For Apache Unit 1, we are approving the state’s NOx BART emission limit, which is 

consistent with LNB with flue gas recirculation (FGR) (natural gas use only), and are also 

propsing a five-year compliance time frame. Although we realize that the design and installation 

required for LNB with FGR is not as complex as for SCR, we note that such an installation may 

be subject to the same timing and scheduling issues as SCR, including the potential to trigger 

115 Available on regulations.gov, docket no. EPA-R06-OAR-2010-0846, pp. 70-72. See also 76 FR at 52408-09 

116 J. Edward Cichanowicz , Implementation Schedule for Selective Catalytic Reduction (SCR) and Flue Gas 

Desulfurization (FGD) Process Equipment (Oct. 10, 2010). 

117 76 FR at 52408-09 
Arizona Regional Haze Technical Support Document – Page 73 of 80 

Prevention of Significant Deterioration permitting requirements as a result of physical changes 

that result in increased carbon monoxide (CO) emissions, 

However, we are seeking comment on whether these compliance dates are reasonable and 

consistent with the requirement of the CAA and the RHR that BART be installed “as 

expeditiously as practicable.” We are specifically seeking comment on whether the outage 

schedule for any of these units may warrant a shorter compliance schedule (up to five years). If 

we receive information during the comment period that establishes that a shorter compliance 

timeframe is appropriate for one or more of these units, we may finalize a different compliance 

date. 

VIII. Summary of EPA’s Proposed Action 

Based on the available control technologies and the five factors discussed in more detail 

below, EPA is proposing to require these facilities to meet NOx, PM10 and SO2 emission limits as 

listed in Table 35. With the exception of Apache Unit 1, the NOx emission limits in Table 35 are 

proposed as part of EPA’s FIP, based on the five factor analyses summarized in Section III.A. 

The PM10 and SO2 emission limits in Table 35 are taken from ADEQ’s BART determinations for 

these facilities, proposed for EPA approval in this action. EPA is seeking comment on alternative 

PM10 and SO2 emissions limits for Apache Generating Station Units 2 and 3; Cholla Power Plant 

Units 2, 3 and 4; and Coronado Units 1 and 2 as described in Section VI.B of the Federal 

Register notice for this proposed action. We are also seeking comment on whether a test method 

other than EPA Method 201/202 should be allowed or required for establishing compliance with 

the PM10 limits that we are proposing to approve. Finally, we are proposing compliance dates 

and specific requirements for monitoring, recordkeeping, reporting and equipment operation and 

maintenance for all of the units covered by this action. Our proposed compliance dates are 

summarized in Table 36. We are seeking comment on whether these compliance dates are 

reasonable and consistent with the requirement of the CAA and the RHR that BART be installed 

“as expeditiously as practicable.” We are also taking comment on whether it would be 

technically feasible and cost-effective for Coronado Unit 2 to meet an emissions limit of 0.050 

lb/MMBtu for NOx.
Arizona Regional Haze Technical Support Document – Page 74 of 80 

Table 35 - Summary of BART Emission Limits

Unit Emission limitation (lb/MMBtu) 

(rolling 30-boiler-operating-day average) 

NOx PM10 SO2

Apache Generating Station Unit 1 0.056 0.0075 0.00064 

Apache Generating Station Unit 2 0.050 0.03 0.15 

Apache Generating Station Unit 3 0.050 0.03 0.15 

Cholla Power Plant Unit 2 0.050 0.015 0.15 

Cholla Power Plant Unit 3 0.050 0.015 0.15 

Cholla Power Plant Unit 4 0.050 0.015 0.15 

Coronado Generating Station Unit 1 0.050 0.03 0.08 

Coronado Generating Station Unit 2 0.080 0.03 0.08 
Arizona Regional Haze Technical Support Document – Page 75 of 80 

Table 36 - Summary of BART Compliance Dates

Unit 

Compliance Date 

NOx PM10 SO2

Apache Generating Station Unit 1 Five years 180 days 180 days 

Apache Generating Station Unit 2 Five years 180 days 180 days 

Apache Generating Station Unit 3 Five years 180 days 180 days 

Cholla Power Plant Unit 2 Five years January 1, 2015 180 days 

Cholla Power Plant Unit 3 Five years 180 days 180 days 

Cholla Power Plant Unit 4 Five years 180 days 180 days 

Coronado Generating Station Unit 1 Five years 180 days 180 days 

Coronado Generating Station Unit 2 June 1, 2014 180 days 180 days 
Arizona Regional Haze Technical Support Document – Page 76 of 80 

V. Appendix A: Listing of Modeling-Related Files

The following files are all located in the docket in folder G-15. 

LISTS 

readme_modeling_files.txt 

contains this list: lists files used in preparing model inputs 

and processing and presenting model output 

c1_area_list_3plants.txt 

list of Class I areas 

AZ_RH_FIP_NPRM_scenarios.txt 

very brief description of modeling scenarios 

lookups.xls 

lookup tables for scenario names and Class I areas; 

includes some additional brief characterization of scenarios 

AZ_NPRM_model_file_names.txt 

CALPUFF etc. file naming convention 

COSTS AND EMISSIONS 

EGU BART Costs_Apache_Cholla_Coronado_FINAL2.xlsx 

Costs, TPY, and % emission reductions calculations 

- costs relied on by both UNC "...dollarperdv_analysis_finalwithplots.xls" 

and by EPA in "TSD_vis_tables.xlsx"; 

- emissions relied for % reduction 

in UNC AZ_BART_sources_all-Task7-8_2012-06-10.xls 

AZ_BART_sources_all-Task7-8_2012-06-10.xls 

"master" spreadsheet of modeling emissions; 

includes some CAMD data for picking max emission day; 

refers to speciation spreadsheets; 

has g/s emission rates for CALPUFF input lines 

AZ Max Emission Dates.xlsx 

maximum daily emissions from CAMD data for modeling 

(prepared by EPA, not UNC) 

2006FinalUncontrolledUtilityResOilBlrpmSpeciationProfile_AEPCO-Unit1-filtPM.xls 

2006FinalDryBottomPC_FGD_ESPpmSpeciationProfile_AEPCO-Unit2-filtPM.xls 

2006FinalDryBottomPC_FGD_ESPpmSpeciationProfile_AEPCO-Unit3-filtPM.xls 

2006FinalDryBottomPC_FGD_FFpmSpeciationProfile_Cholla-Unit1-filtPM.xls 
Arizona Regional Haze Technical Support Document – Page 77 of 80 

2006FinalDryBottomPC_ScrubberpmSpeciationProfile_Cholla-Unit2-filtPM.xls 

2006FinalDryBottomPC_FGD_FFpmSpeciationProfile_Cholla-Unit3-filtPM.xls 

2006FinalDryBottomPC_FGD_FFpmSpeciationProfile_Cholla-Unit4-filtPM.xls 

PM speciation spreadsheets 

referred to by AZ_BART_sources_all-Task7-8_2012-06-10.xls 

MODEL OUTPUTS 

NPR_vis_tables_120702.xls 

summary dv and $/dv tables used in NPRM itself 

AZRHFIP_TSD_vis_summ_tables.xlsx 

UNC and EPA CALPUFF output to support NPRM 

- Summary dv and $/dv tables, and # days >=0.5 dv, used in TSD 

- Differs from NPRM tables in having some updated costs, 

and consistently uses 22nd three-year high for 

"98th percentile" visibility impacts 

(some in results in NPRM used 23rd high) 

AZRHFIP_TSD_Cholla_visx.xlsx 

AZRHFIP_TSD_Coronado_visx.pdf 

AZRHFIP_TSD_Coronado_visx.xlsx 

UNC and EPA CALPUFF output (extracted visibility info) 

- tables of dv and # days over 0.5 and 1.0 dv; 

- bar graphs of 98th percentile impairment 

(graphs only for 8b, MVISBK=8 and 20% best background) 

- % differences between the various visibility 

methods 6a, 6b, 8a, 8b) 

aep_az_unit2-3_dollarperdv_analysis_finalwithplots2.xls 

cho_az_unit2-4_dollarperdv_analysis_finalwithplots.xls 

srp_az_unit1-2_dollarperdv_analysis_finalwithplots.xls 

UNC CALPUFF output; much included in UNC report for WA5-12 Task 8 

- tables of dv, tons/dv, $/dv (calc. for each area & year); 

- bar graphs of 98th percentile impairment and 

benefit (in "area impacts" tabs) 

(NOTE: These do NOT include Coronado "modrev3" results for 

scenarios: ctrl1_rs, ctrl2_rs, ctrl6_rs) 

Coronado_modrev3_n822_visx.xlsx 

Supplemental Coronado results, for scenarios: 

base_q, ctrl1_rs, ctrl2_rs, ctrl6_rs 

(Not really needed since contents already included 

in the above AZRHFIP_NPRM_Coronado_visx.xlsx, 

and base_q scenarion in Coronado_baseq_NPRM.zipx below.) 
Arizona Regional Haze Technical Support Document – Page 78 of 80 

Coronado_bosq_n822_visx.xlsx 

Visibility results for Coronado at Bosque del Apache only 

Not considered for NPRM, but some is in TSD 

CALPUFF MODEL INPUT AND OUTPUT FILES 

These files are too large to include in the electronic docket, but they are available for 

examination in the hard copy of the docket located at the EPA Region 9 office. See the Federal 

Register notice for this proposed action, Section I.B., for more information on accessing the 

hardcopy docket. 

AZ_NPRM_zip_file_notes.txt 

Notes about the modeling zip file contents and organization; 

includes model file naming convention 

AZ_NPRM_zip_file_listing.txt 

Full listing of files within the zip files 

Zip files 

Apache_calpost_NPRM.zipx 

Apache_calpuff_NPRM.zipx 

Apache_postcalpost_NPRM.zipx 

Apache_postutil_NPRM.zipx 

Apache_visx_NPRM.zipx 

Cholla_calpost_NPRM.zipx 

Cholla_calpuff_NPRM.zipx 

Cholla_postcalpost_NPRM.zipx 

Cholla_postutil_NPRM.zipx 

Cholla_visx_NPRM.zipx 

Coronado_calpost_NPRM.zipx 

Coronado_calpuff_NPRM.zipx 

Coronado_postcalpost_NPRM.zipx 

Coronado_postutil_NPRM.zipx 

Coronado_visx_NPRM.zipx 

Note that results for Coronado "modrev3", 

that is, ctrl1_rs, ctrl2_rs, and ctrl6_rs (but not base_q) 

are already included in the above. 

Coronado_modrev3_n822_visx.xlsx 
Arizona Regional Haze Technical Support Document – Page 79 of 80 

Extra files (not relied on for NPRM) 

AZ_extra_zip_file_notes.txt 

note on different naming convention for bosq files 

Coronado_baseq_NPRM.zipx 

Coronado_baseq_zip_file_listing.txt 

CALPUFF input and output files for Coronado 

for scenario base_q only (not incl. bosq) 

which has LNB (no SCR) on both units 

Coronado_bosq_NPRM.zipx 

Coronado_bosq_zip_file_listing.txt 

CALPUFF input and output files for Coronado 

impacts at Bosque del Apache only; 

included in TSD but not considered by 

EPA for NPRM. (includes bosq base_q) 
Arizona Regional Haze Technical Support Document – Page 80 of 80 

VI. Appendix B: Visibility Impact and Benefit Tables
AEPCO Apache, Arizona RH FIP, July 2012

98th percentile delta deciviews (Average of 8th highs for 2001, 2002, 2003; 22nd high for 2001-2003)

Visibility Impacts, dv

Visibility method: Control Scenario

vis8, 20best

Class I Area

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

Chiricahua NM 3.33 3.41 2.88 2.97 2.56 2.59 1.81 1.90

Chiricahua Wild. 3.42 3.46 2.91 2.93 2.44 2.47 1.75 1.87

Galiuro Wild. 2.18 2.22 1.81 1.83 1.56 1.57 1.11 1.12

Gila Wild. 0.64 0.63 0.49 0.49 0.38 0.41 0.25 0.26

Mazatzal Wild. 0.27 0.28 0.22 0.23 0.20 0.19 0.15 0.14

Mount Baldy Wild. 0.27 0.28 0.21 0.22 0.16 0.17 0.10 0.10

Saguaro NP 2.50 2.49 2.15 2.12 1.83 1.84 1.34 1.33

Sierra Ancha Wild. 0.29 0.29 0.23 0.23 0.19 0.19 0.15 0.15

Superstition Wild. 0.60 0.61 0.48 0.51 0.41 0.42 0.30 0.30

Maximum 3.42 3.46 2.91 2.97 2.56 2.59 1.81 1.90

Cumulative (sum) 13.49 13.67 11.38 11.53 9.74 9.84 6.95 7.16

Visibility Benefits, dv

Visibility method: Control Scenario

vis8, 20best

Class I Area

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

Chiricahua NM 0.44 0.44 0.77 0.82 1.52 1.51

Chiricahua Wild. 0.51 0.53 0.98 1.00 1.67 1.59

Galiuro Wild. 0.37 0.39 0.62 0.65 1.06 1.10

Gila Wild. 0.15 0.14 0.26 0.22 0.39 0.37

Mazatzal Wild. 0.04 0.05 0.07 0.09 0.12 0.14

Mount Baldy Wild. 0.06 0.07 0.11 0.11 0.16 0.18

Saguaro NP 0.35 0.38 0.67 0.66 1.17 1.16

Sierra Ancha Wild. 0.06 0.06 0.10 0.10 0.14 0.14

Superstition Wild. 0.11 0.10 0.19 0.19 0.30 0.31

Maximum 0.51 0.53 0.98 1.00 1.67 1.59

Cumulative (sum) 2.11 2.14 3.75 3.83 6.53 6.51

Chiricahua Wilderness has the greatest 22nd high impacts for the base case; Chiricahua NM has the greatest for the contro

Chiricahua Wilderness has the greatest benefit in 22nd high for all the control scenarios.

base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4
AEPCO Apache, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 0.5 dv in 2001-2003; Average

Visibility Impacts, # Days m 0.5 dv

Visibility method:

vis8, 20best

Class I Area Sum Avg Sum Avg Sum Avg Sum Avg

Chiricahua NM 383 128 354 118 320 107 257 86

Chiricahua Wild. 349 116 325 108 281 94 231 77

Galiuro Wild. 138 46 118 39 108 36 79 26

Gila Wild. 35 12 21 7 10 3 3 1

Mazatzal Wild. 9 3 3 1 1 0.3 0 0.0

Mount Baldy Wild. 5 2 2 0.7 1 0.3 0 0.0

Saguaro NP 241 80 224 75 203 68 183 61

Sierra Ancha Wild. 7 2 3 1 3 1 1 0.3

Superstition Wild. 28 9 22 7 14 5 3 1

Maximum 383 128 354 118 320 107 257 86

Cumulative (sum) 1195 398 1072 357 941 314 757 252

Visibility Benefits, # Days m 0.5 dv

Visibility method:

vis8, 20best

Class I Area Sum Avg Sum Avg Sum Avg Sum Avg

Chiricahua NM 29 10 63 21 126 42

Chiricahua Wild. 24 8 68 23 118 39

Galiuro Wild. 20 7 30 10 59 20

Gila Wild. 14 5 25 8 32 11

Mazatzal Wild. 6 2 8 3 9 3

Mount Baldy Wild. 3 1 4 1 5 2

Saguaro NP 17 6 38 13 58 19

Sierra Ancha Wild. 4 1 4 1 6 2

Superstition Wild. 6 2 14 5 25 8

Maximum 29 10 68 23 126 42

Cumulative (sum) 123 41 254 85 438 146

Chiricahua NM has the greatest number of days over 0.5 dv for the base case and all control scenarios.

Chiricahua NM has the greatest decrease in number of days over 0.5 dv for all control scenarios,

except SNCR, for which Chircahua Wilderness has the greatest.

base: Base

(OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR;w/SO4

base: Base

(OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR;w/SO4
AEPCO Apache, Arizona RH FIP, July 2012

98th percentile delta deciviews (8th high for each of 2001, 2002, 2003; their Average; and 22nd high for 2001-2003 period)Visibility Impacts, dv

Visibility method: Control Scenario

vis8, 20best base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

Class I Area 2001 2002 2003 Avg 22nd '01-'03 2001 2002 2003 Avg 22nd '01-'03 2001 2002 2003 Avg 22nd '01-'03 2001 2002 2003 Avg 22nd '01-'03

Chiricahua NM 3.21 3.27 3.50 3.33 3.41 2.79 2.89 2.97 2.88 2.97 2.47 2.62 2.60 2.56 2.59 1.63 1.94 1.85 1.81 1.90Chiricahua Wild. 3.40 3.39 3.46 3.42 3.46 2.93 2.91 2.88 2.91 2.93 2.44 2.47 2.42 2.44 2.47 1.87 1.72 1.67 1.75 1.87Galiuro Wild. 1.81 2.11 2.62 2.18 2.22 1.52 1.64 2.27 1.81 1.83 1.29 1.42 1.97 1.56 1.57 0.94 1.06 1.34 1.11 1.12Gila Wild. 0.67 0.75 0.50 0.64 0.63 0.49 0.58 0.40 0.49 0.49 0.36 0.45 0.33 0.38 0.41 0.22 0.30 0.23 0.25 0.26Mazatzal Wild. 0.30 0.27 0.23 0.27 0.28 0.24 0.23 0.20 0.22 0.23 0.22 0.21 0.17 0.20 0.19 0.16 0.16 0.12 0.15 0.14Mount Baldy Wild. 0.29 0.28 0.24 0.27 0.28 0.22 0.23 0.18 0.21 0.22 0.17 0.18 0.14 0.16 0.17 0.09 0.13 0.09 0.10 0.10Saguaro NP 2.30 2.77 2.44 2.50 2.49 1.99 2.38 2.09 2.15 2.12 1.69 2.03 1.77 1.83 1.84 1.21 1.37 1.44 1.34 1.33Sierra Ancha Wild. 0.29 0.30 0.28 0.29 0.29 0.21 0.24 0.22 0.23 0.23 0.19 0.21 0.18 0.19 0.19 0.13 0.16 0.14 0.15 0.15Superstition Wild. 0.61 0.68 0.49 0.60 0.61 0.48 0.56 0.41 0.48 0.51 0.42 0.47 0.34 0.41 0.42 0.30 0.28 0.31 0.30 0.30

Maximum 3.40 3.39 3.50 3.42 3.46 2.93 2.91 2.97 2.91 2.97 2.47 2.62 2.60 2.56 2.59 1.87 1.94 1.85 1.81 1.90

Cumulative (sum) 12.87 13.83 13.76 13.49 13.67 10.86 11.67 11.60 11.38 11.53 9.24 10.05 9.92 9.74 9.84 6.55 7.12 7.19 6.95 7.16

Visibility Benefits, dv

Visibility method: Control Scenario

vis8, 20best base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

Class I Area 2001 2002 2003 Avg 22nd '01-'03 2001 2002 2003 Avg 22nd '01-'03 2001 2002 2003 Avg 22nd '01-'03 2001 2002 2003 Avg 22nd '01-'03

Chiricahua NM 0.43 0.38 0.53 0.44 0.44 0.74 0.65 0.91 0.77 0.82 1.58 1.33 1.66 1.52 1.51Chiricahua Wild. 0.47 0.48 0.58 0.51 0.53 0.96 0.92 1.05 0.98 1.00 1.53 1.67 1.79 1.67 1.59Galiuro Wild. 0.28 0.47 0.35 0.37 0.39 0.52 0.69 0.65 0.62 0.65 0.87 1.05 1.27 1.06 1.10Gila Wild. 0.18 0.18 0.11 0.15 0.14 0.32 0.30 0.17 0.26 0.22 0.46 0.46 0.27 0.39 0.37Mazatzal Wild. 0.06 0.04 0.03 0.04 0.05 0.08 0.06 0.06 0.07 0.09 0.14 0.11 0.11 0.12 0.14Mount Baldy Wild. 0.07 0.05 0.06 0.06 0.07 0.12 0.11 0.10 0.11 0.11 0.19 0.15 0.15 0.16 0.18Saguaro NP 0.31 0.39 0.36 0.35 0.38 0.61 0.74 0.67 0.67 0.66 1.09 1.40 1.00 1.17 1.16Sierra Ancha Wild. 0.07 0.06 0.06 0.06 0.06 0.10 0.09 0.09 0.10 0.10 0.15 0.14 0.14 0.14 0.14Superstition Wild. 0.13 0.12 0.09 0.11 0.10 0.19 0.22 0.15 0.19 0.19 0.31 0.41 0.18 0.30 0.31

Maximum 0.47 0.48 0.58 0.51 0.53 0.96 0.92 1.05 0.98 1.00 1.58 1.67 1.79 1.67 1.59

Cumulative (sum) 2.01 2.16 2.16 2.11 2.14 3.63 3.78 3.84 3.75 3.83 6.33 6.71 6.57 6.53 6.51

Chiricahua Wilderness has the greatest 22nd high impacts for the base case; Chiricahua NM has the greatest for the control scenarios.Chiricahua Wilderness has the greatest benefit in 22nd high for all the control scenarios.
AEPCO Apache, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 0.5 dv; for each of 2001, 2002, 2003; their Sum, and their Average (rounded to integer unless < 1)Visibility Impacts, # Days m 0.5 dv

Visibility method: Control Scenario

vis8, 20best base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Chiricahua NM 130 126 127 383 128 118 120 116 354 118 107 108 105 320 107 85 89 83 257 86Chiricahua Wild. 128 114 107 349 116 113 108 104 325 108 95 98 88 281 94 81 81 69 231 77Galiuro Wild. 47 46 45 138 46 38 39 41 118 39 35 35 38 108 36 25 26 28 79 26Gila Wild. 12 16 7 35 12 7 10 4 21 7 4 6 0 10 3 0 3 0 3 1Mazatzal Wild. 3 5 1 9 3 1 2 0 3 1 0 1 0 1 0.3 0 0 0 0 0.0Mount Baldy Wild. 2 2 1 5 2 1 1 0 2 0.7 1 0 0 1 0.3 0 0 0 0 0.0Saguaro NP 80 83 78 241 80 74 76 74 224 75 64 71 68 203 68 58 59 66 183 61Sierra Ancha Wild. 2 3 2 7 2 2 1 0 3 1 2 1 0 3 1 0 1 0 1 0.3Superstition Wild. 10 11 7 28 9 7 9 6 22 7 5 4 5 14 5 1 1 1 3 1

Maximum 130 126 127 383 128 118 120 116 354 118 107 108 105 320 107 85 89 83 257 86

Cumulative (sum) 414 406 375 1195 398 361 366 345 1072 357 313 324 304 941 314 250 260 247 757 252

Visibility Benefits, # Days m 0.5 dv

Visibility method: Control Scenario

vis8, 20best base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Chiricahua NM 12 6 11 29 10 23 18 22 63 21 45 37 44 126 42Chiricahua Wild. 15 6 3 24 8 33 16 19 68 23 47 33 38 118 39Galiuro Wild. 9 7 4 20 7 12 11 7 30 10 22 20 17 59 20Gila Wild. 5 6 3 14 5 8 10 7 25 8 12 13 7 32 11Mazatzal Wild. 2 3 1 6 2 3 4 1 8 3 3 5 1 9 3Mount Baldy Wild. 1 1 1 3 1 1 2 1 4 1 2 2 1 5 2Saguaro NP 6 7 4 17 6 16 12 10 38 13 22 24 12 58 19Sierra Ancha Wild. 0 2 2 4 1 0 2 2 4 1 2 2 2 6 2Superstition Wild. 3 2 1 6 2 5 7 2 14 5 9 10 6 25 8

Maximum 15 7 11 29 10 33 18 22 68 23 47 37 44 126 42

Cumulative (sum) 53 40 30 123 41 101 82 71 254 85 164 146 128 438 146

Chiricahua NM has the greatest number of days over 0.5 dv for the base case and all control scenarios.Chiricahua NM has the greatest decrease in number of days over 0.5 dv for all control scenarios,
AEPCO Apache, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 1.0 dv; for each of 2001, 2002, 2003; their Sum, and their Average (rounded to integer unless < 1)Visibility Impacts, # Days m 1.0 dv

Visibility method: Control Scenario

vis8, 20best base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Chiricahua NM 72 78 75 225 75 59 65 64 188 63 45 54 52 151 50 26 39 41 106 35Chiricahua Wild. 71 65 67 203 68 64 57 53 174 58 50 42 43 135 45 37 35 29 101 34Galiuro Wild. 26 19 27 72 24 20 18 24 62 21 14 14 18 46 15 6 9 13 28 9Gila Wild. 0 5 0 5 2 0 4 0 4 1 0 3 0 3 1 0 0 0 0 0.0Mazatzal Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Mount Baldy Wild. 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Saguaro NP 51 47 56 154 51 41 42 51 134 45 37 35 42 114 38 19 24 28 71 24Sierra Ancha Wild. 1 1 0 2 0.7 0 1 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0Superstition Wild. 2 2 2 6 2 1 2 0 3 1 1 1 0 2 0.7 0 0 0 0 0.0

Maximum 72 78 75 225 75 64 65 64 188 63 50 54 52 151 50 37 39 41 106 35

Cumulative (sum) 224 217 227 668 223 185 189 192 566 189 147 149 155 451 150 88 107 111 306 102

Visibility Benefits, # Days m 1.0 dv

Visibility method: Control Scenario

vis8, 20best base: Base (OFA) ctrl1_r: LNB ctrl2_r: SNCR ctrl3_s: SCR; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Chiricahua NM 13 13 11 37 12 27 24 23 74 25 46 39 34 119 40Chiricahua Wild. 7 8 14 29 10 21 23 24 68 23 34 30 38 102 34Galiuro Wild. 6 1 3 10 3 12 5 9 26 9 20 10 14 44 15Gila Wild. 0 1 0 1 0 0 2 0 2 1 0 5 0 5 2Mazatzal Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Mount Baldy Wild. 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0Saguaro NP 10 5 5 20 7 14 12 14 40 13 32 23 28 83 28Sierra Ancha Wild. 1 0 0 1 0 1 1 0 2 1 1 1 0 2 1Superstition Wild. 1 0 2 3 1 1 1 2 4 1 2 2 2 6 2

Maximum 13 13 14 37 12 27 24 24 74 25 46 39 38 119 40

Cumulative (sum) 39 28 35 102 34 77 68 72 217 72 136 110 116 362 121

Chiricahua NM has the greatest number of days over 1.0 dv for the base case and all control scenarios.Chiricahua NM has the greatest decrease in number of days over 1.0 dv for all control scenarios.
Chiricahua NM Chiricahua Wild. Galiuro Gila Mazatzal Mount Baldy Saguaro NP Sierra Ancha Superstition

base: Base (OFA) 3.41 3.46 2.22 0.63 0.28 0.28 2.49 0.29 0.61ctrl1_r: LNB 2.97 2.93 1.83 0.49 0.23 0.22 2.12 0.23 0.51

ctrl2_r: SNCR 2.59 2.47 1.57 0.41 0.19 0.17 1.84 0.19 0.42

ctrl3_s: SCR; w/SO4 1.90 1.87 1.12 0.26 0.14 0.10 1.33 0.15 0.30

0.00.51.01.52.02.53.03.54.0

AEPCO Apache 2001-2003 Visibility Impacts, EPA RH FIP July 2012 (dv) Visibility

method: vis8, 20best
Chiricahua NM Chiricahua Wild. Galiuro Gila Mazatzal Mount Baldy Saguaro NP Sierra Ancha Superstition

base: Base (OFA)ctrl1_r: LNB 0.44 0.53 0.39 0.14 0.05 0.07 0.38 0.06 0.10

ctrl2_r: SNCR 0.82 1.00 0.65 0.22 0.09 0.11 0.66 0.10 0.19

ctrl3_s: SCR; w/SO4 1.51 1.59 1.10 0.37 0.14 0.18 1.16 0.14 0.31

0.00.20.40.60.81.01.21.41.61.8

AEPCO Apache 2001-2003 Visibility Benefits, EPA RH FIP July 2012 (dv)

Visibility method: vis8, 20best
APS Cholla, Arizona RH FIP, July 2012

98th percentile delta deciviews (Average of 8th highs for 2001, 2002, 2003; 22nd high for 2001-2003)

Visibility Impacts, dv

Visibility method: Control Scenario

vis8, 20best

Class I Area

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

Capitol Reef NP 1.33 1.46 1.08 1.19 0.60 0.70

Galiuro Wild. 0.44 0.45 0.37 0.40 0.30 0.31

Gila Wild. 0.71 0.70 0.61 0.61 0.47 0.48

Grand Canyon NP 2.49 2.22 2.10 1.85 1.30 1.16

Mazatzal Wild. 1.20 1.19 1.04 1.03 0.75 0.76

Mesa Verde NP 1.33 1.34 1.07 1.08 0.61 0.63

Mount Baldy Wild. 1.20 1.21 0.97 0.95 0.69 0.70

Petrified Forest NP 4.49 4.53 4.06 4.06 3.22 3.19

Pine Mountain Wild. 0.84 0.85 0.72 0.73 0.52 0.54

Saguaro NP 0.30 0.30 0.27 0.28 0.22 0.25

Sierra Ancha Wild. 1.37 1.36 1.16 1.17 0.82 0.85

Superstition Wild. 1.20 1.27 1.04 1.10 0.75 0.76

Sycamore Canyon Wild. 1.36 1.42 1.10 1.15 0.73 0.75

Maximum 4.49 4.53 4.06 4.06 3.22 3.19

Cumulative (sum) 18.26 18.30 15.59 15.59 10.99 11.09

Visibility Benefits, dv

Visibility method: Control Scenario

vis8, 20best

Class I Area

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

'01-'03

Avg

'01-'03

22nd

Capitol Reef NP 0.25 0.27 0.73 0.76

Galiuro Wild. 0.07 0.05 0.14 0.14

Gila Wild. 0.10 0.09 0.25 0.22

Grand Canyon NP 0.39 0.37 1.19 1.06

Mazatzal Wild. 0.16 0.16 0.45 0.43

Mesa Verde NP 0.26 0.26 0.72 0.70

Mount Baldy Wild. 0.23 0.27 0.50 0.52

Petrified Forest NP 0.43 0.47 1.27 1.34

Pine Mountain Wild. 0.12 0.12 0.32 0.31

Saguaro NP 0.03 0.02 0.08 0.05

Sierra Ancha Wild. 0.21 0.20 0.55 0.51

Superstition Wild. 0.16 0.17 0.45 0.51

Sycamore Canyon Wild. 0.26 0.27 0.62 0.68

Maximum 0.43 0.47 1.27 1.34

Cumulative (sum) 2.67 2.71 7.27 7.21

Petrified Forest has the greatest 22nd high impacts for the base case, and for the control scenarios.

Petrified Forest has the greatest benefit in 22nd high for all the control scenarios.

base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR
APS Cholla, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 0.5 dv in 2001-2003; Average

Visibility Impacts, # Days m 0.5 dv

Visibility method:

vis8, 20best

Class I Area Sum Avg Sum Avg Sum Avg

Capitol Reef NP 56 19 52 17 32 11

Galiuro Wild. 15 5 12 4 7 2

Gila Wild. 50 17 39 13 19 6

Grand Canyon NP 84 28 74 25 57 19

Mazatzal Wild. 104 35 89 30 57 19

Mesa Verde NP 99 33 77 26 36 12

Mount Baldy Wild. 86 29 73 24 45 15

Petrified Forest NP 756 252 739 246 696 232

Pine Mountain Wild. 58 19 45 15 25 8

Saguaro NP 11 4 6 2 3 1

Sierra Ancha Wild. 122 41 107 36 74 25

Superstition Wild. 77 26 68 23 47 16

Sycamore Canyon Wild. 73 24 59 20 36 12

Maximum 756 252 739 246 696 232

Cumulative (sum) 1591 530 1440 480 1134 378

Visibility Benefits, # Days m 0.5 dv

Visibility method:

vis8, 20best

Class I Area Sum Avg Sum Avg Sum Avg

Capitol Reef NP 4 1 24 8

Galiuro Wild. 3 1 8 3

Gila Wild. 11 4 31 10

Grand Canyon NP 10 3 27 9

Mazatzal Wild. 15 5 47 16

Mesa Verde NP 22 7 63 21

Mount Baldy Wild. 13 4 41 14

Petrified Forest NP 17 6 60 20

Pine Mountain Wild. 13 4 33 11

Saguaro NP 5 2 8 3

Sierra Ancha Wild. 15 5 48 16

Superstition Wild. 9 3 30 10

Sycamore Canyon Wild. 14 5 37 12

Maximum 22 7 63 21

Cumulative (sum) 151 50 457 152

Petrified Forest has the greatest number of days over 0.5 dv for the base case and all control scenarios.

Mesa Verde has the greatest decrease in number of days over 0.5 dv for all control scenarios.

base_R: Base ctrl1_r: SNCR ctrl2_r2: SCR

base_R: Base ctrl1_r: SNCR ctrl2_r2: SCR
APS Cholla, Arizona RH FIP, July 2012

98th percentile delta deciviews (8th high for each of 2001, 2002, 2003; their Average; and 22nd high for 2001-2003 period)

Visibility Impacts, dv

Visibility method: Control Scenario

vis8, 20best base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

Class I Area 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03

Capitol Reef NP 1.29 0.89 1.81 1.33 1.46 1.03 0.71 1.49 1.08 1.19 0.60 0.39 0.80 0.60 0.70Galiuro Wild. 0.49 0.40 0.43 0.44 0.45 0.42 0.35 0.35 0.37 0.40 0.36 0.30 0.23 0.30 0.31Gila Wild. 0.65 0.73 0.76 0.71 0.70 0.57 0.63 0.64 0.61 0.61 0.39 0.50 0.51 0.47 0.48Grand Canyon NP 3.86 2.10 1.52 2.49 2.22 3.26 1.76 1.29 2.10 1.85 1.92 1.10 0.88 1.30 1.16Mazatzal Wild. 1.24 1.19 1.17 1.20 1.19 1.09 1.01 1.02 1.04 1.03 0.74 0.72 0.79 0.75 0.76Mesa Verde NP 0.97 1.35 1.66 1.33 1.34 0.77 1.08 1.34 1.07 1.08 0.44 0.63 0.75 0.61 0.63Mount Baldy Wild. 1.42 1.24 0.93 1.20 1.21 1.11 1.03 0.77 0.97 0.95 0.70 0.71 0.67 0.69 0.70Petrified Forest NP 4.54 4.06 4.87 4.49 4.53 4.17 3.65 4.37 4.06 4.06 3.23 3.00 3.44 3.22 3.19Pine Mountain Wild. 0.82 1.05 0.66 0.84 0.85 0.70 0.88 0.58 0.72 0.73 0.48 0.61 0.49 0.52 0.54Saguaro NP 0.36 0.26 0.27 0.30 0.30 0.34 0.24 0.23 0.27 0.28 0.30 0.19 0.16 0.22 0.25Sierra Ancha Wild. 1.47 1.44 1.20 1.37 1.36 1.22 1.23 1.04 1.16 1.17 0.81 0.85 0.79 0.82 0.85Superstition Wild. 1.37 1.32 0.93 1.20 1.27 1.16 1.14 0.84 1.04 1.10 0.85 0.77 0.64 0.75 0.76Sycamore Canyon Wild. 1.42 1.65 1.01 1.36 1.42 1.18 1.30 0.81 1.10 1.15 0.72 0.95 0.53 0.73 0.75

Maximum 4.54 4.06 4.87 4.49 4.53 4.17 3.65 4.37 4.06 4.06 3.23 3.00 3.44 3.22 3.19

Cumulative (sum) 19.89 17.68 17.20 18.26 18.30 17.01 14.99 14.76 15.59 15.59 11.54 10.73 10.69 10.99 11.09

Visibility Benefits, dv

Visibility method: Control Scenario

vis8, 20best base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

Class I Area 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03

Capitol Reef NP 0.25 0.18 0.32 0.25 0.27 0.69 0.50 1.01 0.73 0.76Galiuro Wild. 0.07 0.05 0.08 0.07 0.05 0.13 0.10 0.19 0.14 0.14Gila Wild. 0.09 0.10 0.12 0.10 0.09 0.27 0.23 0.25 0.25 0.22Grand Canyon NP 0.60 0.34 0.23 0.39 0.37 1.94 1.00 0.64 1.19 1.06Mazatzal Wild. 0.15 0.18 0.15 0.16 0.16 0.49 0.47 0.38 0.45 0.43Mesa Verde NP 0.20 0.26 0.32 0.26 0.26 0.53 0.71 0.91 0.72 0.70Mount Baldy Wild. 0.31 0.22 0.16 0.23 0.27 0.72 0.53 0.26 0.50 0.52Petrified Forest NP 0.38 0.41 0.50 0.43 0.47 1.31 1.06 1.43 1.27 1.34Pine Mountain Wild. 0.13 0.17 0.07 0.12 0.12 0.35 0.44 0.17 0.32 0.31Saguaro NP 0.02 0.03 0.04 0.03 0.02 0.06 0.07 0.11 0.08 0.05Sierra Ancha Wild. 0.25 0.21 0.15 0.21 0.20 0.66 0.58 0.41 0.55 0.51Superstition Wild. 0.21 0.18 0.09 0.16 0.17 0.51 0.56 0.28 0.45 0.51Sycamore Canyon Wild. 0.24 0.35 0.19 0.26 0.27 0.70 0.70 0.48 0.62 0.68

Maximum 0.60 0.41 0.50 0.43 0.47 1.94 1.06 1.43 1.27 1.34

Cumulative (sum) 2.89 2.69 2.43 2.67 2.71 8.35 6.96 6.51 7.27 7.21

Petrified Forest has the greatest 22nd high impacts for the base case, and for the control scenarios.Petrified Forest has the greatest benefit in 22nd high for all the control scenarios.
APS Cholla, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 0.5 dv; for each of 2001, 2002, 2003; their Sum, and their Average (roundVisibility Impacts, # Days m 0.5 dv

Visibility method: Control Scenario

vis8, 20best base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Capitol Reef NP 27 11 18 56 19 24 10 18 52 17 12 7 13 32 11Galiuro Wild. 5 7 3 15 5 3 7 2 12 4 1 5 1 7 2Gila Wild. 16 17 17 50 17 13 13 13 39 13 5 6 8 19 6Grand Canyon NP 36 26 22 84 28 30 23 21 74 25 23 19 15 57 19Mazatzal Wild. 34 46 24 104 35 28 41 20 89 30 17 24 16 57 19Mesa Verde NP 28 39 32 99 33 17 32 28 77 26 4 15 17 36 12Mount Baldy Wild. 33 31 22 86 29 26 28 19 73 24 14 17 14 45 15Petrified Forest NP 232 256 268 756 252 228 252 259 739 246 213 235 248 696 232Pine Mountain Wild. 18 26 14 58 19 14 19 12 45 15 6 12 7 25 8Saguaro NP 5 5 1 11 4 1 4 1 6 2 0 2 1 3 1Sierra Ancha Wild. 45 44 33 122 41 40 40 27 107 36 29 26 19 74 25Superstition Wild. 31 28 18 77 26 27 26 15 68 23 18 17 12 47 16Sycamore Canyon Wild. 20 29 24 73 24 18 23 18 59 20 12 14 10 36 12

Maximum 232 256 268 756 252 228 252 259 739 246 213 235 248 696 232

Cumulative (sum) 530 565 496 1591 530 469 518 453 1440 480 354 399 381 1134 378

Visibility Benefits, # Days m 0.5 dv

Visibility method: Control Scenario

vis8, 20best base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Capitol Reef NP 3 1 0 4 1 15 4 5 24 8Galiuro Wild. 2 0 1 3 1 4 2 2 8 3Gila Wild. 3 4 4 11 4 11 11 9 31 10Grand Canyon NP 6 3 1 10 3 13 7 7 27 9Mazatzal Wild. 6 5 4 15 5 17 22 8 47 16Mesa Verde NP 11 7 4 22 7 24 24 15 63 21Mount Baldy Wild. 7 3 3 13 4 19 14 8 41 14Petrified Forest NP 4 4 9 17 6 19 21 20 60 20Pine Mountain Wild. 4 7 2 13 4 12 14 7 33 11Saguaro NP 4 1 0 5 2 5 3 0 8 3Sierra Ancha Wild. 5 4 6 15 5 16 18 14 48 16Superstition Wild. 4 2 3 9 3 13 11 6 30 10Sycamore Canyon Wild. 2 6 6 14 5 8 15 14 37 12

Maximum 11 7 9 22 7 24 24 20 63 21

Cumulative (sum) 61 47 43 151 50 176 166 115 457 152

Petrified Forest has the greatest number of days over 0.5 dv for the base case and all control scenarios.Mesa Verde has the greatest decrease in number of days over 0.5 dv for all control scenarios.
APS Cholla, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 1.0 dv; for each of 2001, 2002, 2003; their Sum, and their Average (roundVisibility Impacts, # Days m 1.0 dv

Visibility method: Control Scenario

vis8, 20best base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Capitol Reef NP 12 7 11 30 10 8 7 11 26 9 3 2 6 11 4Galiuro Wild. 0 3 0 3 1 0 1 0 1 0.3 0 0 0 0 0.0Gila Wild. 2 4 4 10 3 1 4 3 8 3 1 1 2 4 1Grand Canyon NP 20 17 13 50 17 19 16 11 46 15 13 8 4 25 8Mazatzal Wild. 13 14 11 38 13 9 8 9 26 9 2 1 2 5 2Mesa Verde NP 5 15 18 38 13 3 9 11 23 8 2 1 3 6 2Mount Baldy Wild. 8 11 6 25 8 8 8 5 21 7 2 5 1 8 3Petrified Forest NP 197 218 225 640 213 188 212 217 617 206 164 199 191 554 185Pine Mountain Wild. 3 8 5 16 5 2 5 3 10 3 0 0 1 1 0.3Saguaro NP 0 1 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0Sierra Ancha Wild. 20 18 9 47 16 14 12 9 35 12 6 3 5 14 5Superstition Wild. 13 13 6 32 11 12 9 4 25 8 3 3 2 8 3Sycamore Canyon Wild. 11 13 8 32 11 8 11 5 24 8 3 7 2 12 4

Maximum 197 218 225 640 213 188 212 217 617 206 164 199 191 554 185

Cumulative (sum) 304 342 316 962 321 272 302 288 862 287 199 230 219 648 216

Visibility Benefits, # Days m 1.0 dv

Visibility method: Control Scenario

vis8, 20best base_R: Base (LNB) ctrl1_r: SNCR ctrl2_r2: SCR

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg

Capitol Reef NP 4 0 0 4 1 9 5 5 19 6Galiuro Wild. 0 2 0 2 1 0 3 0 3 1Gila Wild. 1 0 1 2 1 1 3 2 6 2Grand Canyon NP 1 1 2 4 1 7 9 9 25 8Mazatzal Wild. 4 6 2 12 4 11 13 9 33 11Mesa Verde NP 2 6 7 15 5 3 14 15 32 11Mount Baldy Wild. 0 3 1 4 1 6 6 5 17 6Petrified Forest NP 9 6 8 23 8 33 19 34 86 29Pine Mountain Wild. 1 3 2 6 2 3 8 4 15 5Saguaro NP 0 1 0 1 0 0 1 0 1 0Sierra Ancha Wild. 6 6 0 12 4 14 15 4 33 11Superstition Wild. 1 4 2 7 2 10 10 4 24 8Sycamore Canyon Wild. 3 2 3 8 3 8 6 6 20 7

Maximum 9 6 8 23 8 33 19 34 86 29

Cumulative (sum) 32 40 28 100 33 105 112 97 314 105

Petrified Forest has the greatest number of days over 1.0 dv for the base case and all control scenarios.Petrified Forest has the greatest decrease in number of days over 0.5 dv for all control scenarios.
Capitol

Reef Galiuro Gila Grand Canyon Mazatzal Mesa Verde Mount Baldy Petrified Forest Pine Mountain Saguaro Sierra Ancha Superstitio n Sycamore Canyon

base_R: Base (LNB) 1.46 0.45 0.70 2.22 1.19 1.34 1.21 4.53 0.85 0.30 1.36 1.27 1.42ctrl1_r: SNCR 1.19 0.40 0.61 1.85 1.03 1.08 0.95 4.06 0.73 0.28 1.17 1.10 1.15

ctrl2_r2: SCR 0.70 0.31 0.48 1.16 0.76 0.63 0.70 3.19 0.54 0.25 0.85 0.76 0.75

0.00.51.01.52.02.53.03.54.04.55

A

.0

PS Cholla 2001-2003 Visibility Impacts, EPA RH FIP July 2012 (dv) Visibility

method: vis8, 20best
Capitol

Reef Galiuro Gila Grand Canyon Mazatzal Mesa Verde Mount Baldy Petrified Forest Pine Mountain Saguaro Sierra Ancha Superstitio n Sycamore Canyon

base_R: Base (LNB)ctrl1_r: SNCR 0.27 0.05 0.09 0.37 0.16 0.26 0.27 0.47 0.12 0.02 0.20 0.17 0.27

ctrl2_r2: SCR 0.76 0.14 0.22 1.06 0.43 0.70 0.52 1.34 0.31 0.05 0.51 0.51 0.68

0.00.20.40.60.81.01.21.41

A

.6

PS Cholla 2001-2003 Visibility Benefits, EPA RH FIP July 2012 (dv) Visibility

method: vis8, 20best
SRP Coronado, Arizona RH FIP, July 2012

98th percentile delta deciviews (Average of 8th highs for 2001, 2002, 2003; 22nd high for 2001-2003)

Visibility Impacts, dv

Visibility method: Control Scenario

vis8, 20best

Class I Area

'01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd

Bandelier NM 0.34 0.37 0.28 0.30 0.19 0.19 0.17 0.17 0.15 0.15

Chiricahua NM 0.20 0.20 0.16 0.16 0.14 0.13 0.12 0.12 0.11 0.11

Chiricahua Wild. 0.22 0.21 0.18 0.18 0.14 0.14 0.13 0.12 0.11 0.11

Galiuro Wild. 0.19 0.20 0.16 0.18 0.11 0.12 0.11 0.11 0.10 0.10

Gila Wild. 1.08 1.23 0.91 1.00 0.63 0.64 0.55 0.57 0.47 0.49

Grand Canyon NP 0.22 0.24 0.19 0.20 0.13 0.15 0.12 0.13 0.12 0.12

Mazatzal Wild. 0.20 0.20 0.18 0.19 0.14 0.14 0.13 0.13 0.13 0.12

Mesa Verde NP 0.39 0.40 0.31 0.33 0.21 0.21 0.19 0.20 0.17 0.17

Mount Baldy Wild. 0.83 0.87 0.68 0.71 0.46 0.46 0.43 0.43 0.37 0.38

Petrified Forest NP 1.28 1.22 1.07 1.05 0.71 0.74 0.65 0.66 0.57 0.59

Pine Mountain Wild. 0.14 0.14 0.13 0.13 0.11 0.10 0.11 0.10 0.10 0.09

Saguaro NP 0.12 0.12 0.11 0.10 0.09 0.08 0.08 0.08 0.07 0.07

San Pedro Parks Wild. 0.49 0.54 0.40 0.43 0.24 0.26 0.23 0.23 0.20 0.20

Sierra Ancha Wild. 0.23 0.24 0.21 0.21 0.18 0.18 0.17 0.18 0.16 0.17

Superstition Wild. 0.21 0.21 0.18 0.19 0.16 0.16 0.15 0.15 0.15 0.14

Sycamore Canyon Wild. 0.17 0.16 0.15 0.15 0.11 0.11 0.10 0.10 0.09 0.09

Maximum 1.28 1.23 1.07 1.05 0.71 0.74 0.65 0.66 0.57 0.59

Cumulative (sum) 6.29 6.54 5.29 5.52 3.74 3.80 3.47 3.47 3.08 3.11

Visibility Benefits, dv

Visibility method: Control Scenario

vis8, 20best

Class I Area

'01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd '01-'03 Avg

'01-'03

22nd

Bandelier NM 0.06 0.07 0.16 0.18 0.17 0.20 0.19 0.22

Chiricahua NM 0.03 0.03 0.06 0.07 0.07 0.08 0.09 0.09

Chiricahua Wild. 0.04 0.03 0.08 0.07 0.09 0.09 0.10 0.09

Galiuro Wild. 0.03 0.02 0.08 0.08 0.09 0.09 0.09 0.09

Gila Wild. 0.17 0.22 0.45 0.59 0.52 0.66 0.60 0.73

Grand Canyon NP 0.04 0.03 0.09 0.09 0.10 0.11 0.11 0.12

Mazatzal Wild. 0.03 0.01 0.06 0.06 0.07 0.07 0.07 0.08

Mesa Verde NP 0.07 0.07 0.18 0.19 0.19 0.20 0.22 0.23

Mount Baldy Wild. 0.14 0.16 0.36 0.42 0.40 0.44 0.46 0.50

Petrified Forest NP 0.20 0.17 0.57 0.47 0.62 0.56 0.70 0.63

Pine Mountain Wild. 0.01 0.02 0.03 0.04 0.03 0.05 0.04 0.06

Saguaro NP 0.01 0.01 0.04 0.03 0.05 0.04 0.05 0.04

San Pedro Parks Wild. 0.09 0.11 0.24 0.28 0.26 0.30 0.29 0.34

Sierra Ancha Wild. 0.03 0.03 0.05 0.06 0.06 0.07 0.07 0.08

Superstition Wild. 0.02 0.02 0.05 0.06 0.05 0.06 0.06 0.07

Sycamore Canyon Wild. 0.02 0.01 0.06 0.05 0.06 0.06 0.07 0.07

Maximum 0.20 0.22 0.57 0.59 0.62 0.66 0.70 0.73

Cumulative (sum) 1.00 1.02 2.55 2.74 2.83 3.07 3.22 3.43

Gila Wilderness has the greatest 22nd high impacts for the base case; Petrified Forest has the greatest for the control scenarios.

Gila Wilderness has the greatest benefit in 22nd high for all the control scenarios.

base_rs: SCR .08 u2

w/SO4

ctrl1_rs: SNCR u1;

w/SO4

ctrl2_rs: SCR .05 u1;

w/SO4

ctrl5_rs: SCR .05

w/SO4

ctrl6_rs: SCR -90%;

w/SO4

base_rs: SCR .08 u2

w/SO4

ctrl1_rs: SNCR u1;

w/SO4

ctrl2_rs: SCR .05 u1;

w/SO4

ctrl5_rs: SCR .05

w/SO4

ctrl6_rs: SCR -90%;

w/SO4
SRP Coronado, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 0.5 dv in 2001-2003; Average

Visibility Impacts, # Days m 0.5 dv

Visibility method:

vis8, 20best

Class I Area Sum Avg Sum Avg Sum Avg Sum Avg Sum Avg

Bandelier NM 10 3 5 2 1 0.3 1 0.3 0 0.0

Chiricahua NM 3 1 1 0.3 0 0.0 0 0.0 0 0.0

Chiricahua Wild. 6 2 3 1 0 0.0 0 0.0 0 0.0

Galiuro Wild. 5 2 3 1 1 0.3 0 0.0 0 0.0

Gila Wild. 80 27 61 20 32 11 25 8 21 7

Grand Canyon NP 8 3 6 2 1 0.3 1 0.3 0 0.0

Mazatzal Wild. 2 0.7 0 0.0 0 0.0 0 0.0 0 0.0

Mesa Verde NP 17 6 14 5 3 1 0 0.0 0 0.0

Mount Baldy Wild. 52 17 46 15 16 5 14 5 8 3

Petrified Forest NP 83 28 70 23 43 14 37 12 29 10

Pine Mountain Wild. 0 0.0 0 0.0 0 0.0 0 0.0 0 0.0

Saguaro NP 2 0.7 2 0.7 1 0.3 0 0.0 0 0.0

San Pedro Parks Wild. 25 8 13 4 1 0.3 1 0.3 1 0.3

Sierra Ancha Wild. 5 2 3 1 1 0.3 0 0.0 0 0.0

Superstition Wild. 1 0.3 0 0.0 0 0.0 0 0.0 0 0.0

Sycamore Canyon Wild. 1 0.3 0 0.0 0 0.0 0 0.0 0 0.0

Maximum 83 28 70 23 43 14 37 12 29 10

Cumulative (sum) 300 100 227 76 100 33 79 26 59 20

Visibility Benefits, # Days m 0.5 dv

Visibility method:

vis8, 20best

Class I Area Sum Avg Sum Avg Sum Avg Sum Avg Sum Avg

Bandelier NM 5 2 9 3 9 3 10 3

Chiricahua NM 2 1 3 1 3 1 3 1

Chiricahua Wild. 3 1 6 2 6 2 6 2

Galiuro Wild. 2 1 4 1 5 2 5 2

Gila Wild. 19 6 48 16 55 18 59 20

Grand Canyon NP 2 1 7 2 7 2 8 3

Mazatzal Wild. 2 1 2 1 2 1 2 0.7

Mesa Verde NP 3 1 14 5 17 6 17 6

Mount Baldy Wild. 6 2 36 12 38 13 44 15

Petrified Forest NP 13 4 40 13 46 15 54 18

Pine Mountain Wild. 0 0 0 0 0 0 0 0.0

Saguaro NP 0 0 1 0 2 1 2 0.7

San Pedro Parks Wild. 12 4 24 8 24 8 24 8

Sierra Ancha Wild. 2 1 4 1 5 2 5 2

Superstition Wild. 1 0 1 0 1 0 1 0.3

Sycamore Canyon Wild. 1 0 1 0 1 0 1 0.3

Maximum 19 6 48 16 55 18 59 20

Cumulative (sum) 73 24 200 67 221 74 241 80

Petrified Forest has the greatest number of days over 0.5 dv for the base case and all control scenarios.

Gila Wilderness has the greatest decrease in number of days over 0.5 dv for all control scenarios.

base_rs: SCR .08

u2 w/SO4

ctrl1_rs: SNCR

u1; w/SO4

ctrl2_rs: SCR .05

u1; w/SO4

ctrl5_rs: SCR .05

w/SO4

ctrl6_rs: SCR -

90%; w/SO4

base_rs: SCR .08

u2 w/SO4

ctrl1_rs: SNCR

u1; w/SO4

ctrl2_rs: SCR .05

u1; w/SO4

ctrl5_rs: SCR .05

w/SO4

ctrl6_rs: SCR -

90%; w/SO4
SRP Coronado, Arizona RH FIP, July 2012

98th percentile delta deciviews (8th high for each of 2001, 2002, 2003; their Average; and 22nd high for 2001-2003 period)

Visibility Impacts, dv

Visibility method: Control Scenario

vis8, 20best base_rs: SCR .08 u2 w/SO4 ctrl1_rs: SNCR u1; w/SO4 ctrl2_rs: SCR .05 u1; w/SO4 ctrl5_rs: SCR .05 w/SO4 ctrl6_rs: SCR -90%; w/SO4

Class I Area 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03

Bandelier NM 0.21 0.37 0.46 0.34 0.37 0.18 0.30 0.37 0.28 0.30 0.14 0.19 0.24 0.19 0.19 0.13 0.17 0.23 0.17 0.17 0.12 0.16 0.19 0.15 0.15Chiricahua NM 0.16 0.21 0.23 0.20 0.20 0.14 0.17 0.18 0.16 0.16 0.13 0.11 0.17 0.14 0.13 0.12 0.10 0.16 0.12 0.12 0.10 0.08 0.15 0.11 0.11Chiricahua Wild. 0.18 0.21 0.25 0.22 0.21 0.15 0.18 0.20 0.18 0.18 0.14 0.11 0.17 0.14 0.14 0.13 0.10 0.16 0.13 0.12 0.12 0.09 0.14 0.11 0.11Galiuro Wild. 0.22 0.21 0.16 0.19 0.20 0.19 0.17 0.14 0.16 0.18 0.12 0.12 0.10 0.11 0.12 0.12 0.11 0.10 0.11 0.11 0.11 0.10 0.09 0.10 0.10Gila Wild. 0.95 1.27 1.01 1.08 1.23 0.79 1.05 0.90 0.91 1.00 0.52 0.66 0.70 0.63 0.64 0.47 0.58 0.61 0.55 0.57 0.40 0.49 0.53 0.47 0.49Grand Canyon NP 0.33 0.20 0.14 0.22 0.24 0.28 0.17 0.12 0.19 0.20 0.18 0.11 0.10 0.13 0.15 0.16 0.11 0.10 0.12 0.13 0.14 0.11 0.10 0.12 0.12Mazatzal Wild. 0.17 0.21 0.22 0.20 0.20 0.14 0.19 0.20 0.18 0.19 0.11 0.15 0.15 0.14 0.14 0.11 0.15 0.14 0.13 0.13 0.11 0.13 0.14 0.13 0.12Mesa Verde NP 0.45 0.37 0.35 0.39 0.40 0.36 0.31 0.28 0.31 0.33 0.21 0.24 0.18 0.21 0.21 0.20 0.21 0.18 0.19 0.20 0.17 0.17 0.17 0.17 0.17Mount Baldy Wild. 0.83 0.87 0.78 0.83 0.87 0.70 0.71 0.65 0.68 0.71 0.48 0.45 0.46 0.46 0.46 0.44 0.39 0.45 0.43 0.43 0.38 0.33 0.40 0.37 0.38Petrified Forest NP 1.22 1.71 0.90 1.28 1.22 1.05 1.40 0.78 1.07 1.05 0.70 0.86 0.58 0.71 0.74 0.66 0.75 0.55 0.65 0.66 0.57 0.66 0.49 0.57 0.59Pine Mountain Wild. 0.11 0.15 0.15 0.14 0.14 0.10 0.14 0.14 0.13 0.13 0.09 0.13 0.12 0.11 0.10 0.09 0.12 0.11 0.11 0.10 0.08 0.11 0.11 0.10 0.09Saguaro NP 0.11 0.16 0.11 0.12 0.12 0.10 0.14 0.10 0.11 0.10 0.08 0.10 0.07 0.09 0.08 0.08 0.09 0.07 0.08 0.08 0.07 0.08 0.07 0.07 0.07San Pedro Parks Wild. 0.34 0.58 0.54 0.49 0.54 0.28 0.47 0.43 0.40 0.43 0.17 0.29 0.27 0.24 0.26 0.16 0.25 0.27 0.23 0.23 0.14 0.22 0.22 0.20 0.20Sierra Ancha Wild. 0.20 0.26 0.24 0.23 0.24 0.18 0.23 0.21 0.21 0.21 0.15 0.20 0.19 0.18 0.18 0.15 0.18 0.19 0.17 0.18 0.15 0.17 0.18 0.16 0.17Superstition Wild. 0.23 0.20 0.19 0.21 0.21 0.20 0.18 0.17 0.18 0.19 0.18 0.14 0.16 0.16 0.16 0.17 0.14 0.15 0.15 0.15 0.16 0.13 0.15 0.15 0.14Sycamore Canyon Wild. 0.14 0.19 0.16 0.17 0.16 0.12 0.16 0.15 0.15 0.15 0.10 0.10 0.12 0.11 0.11 0.09 0.10 0.12 0.10 0.10 0.09 0.09 0.10 0.09 0.09

Maximum 1.22 1.71 1.01 1.28 1.23 1.05 1.40 0.90 1.07 1.05 0.70 0.86 0.70 0.71 0.74 0.66 0.75 0.61 0.65 0.66 0.57 0.66 0.53 0.57 0.59

Cumulative (sum) 5.83 7.15 5.90 6.29 6.54 4.95 5.94 5.00 5.29 5.52 3.49 3.95 3.78 3.74 3.80 3.27 3.55 3.58 3.47 3.47 2.88 3.13 3.22 3.08 3.11

Visibility Benefits, dv

Visibility method: Control Scenario

vis8, 20best base_rs: SCR .08 u2 w/SO4 ctrl1_rs: SNCR u1; w/SO4 ctrl2_rs: SCR .05 u1; w/SO4 ctrl5_rs: SCR .05 w/SO4 ctrl6_rs: SCR -90%; w/SO4

Class I Area 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03 2001 2002 2003 Avg

22nd

'01-'03

Bandelier NM 0.03 0.07 0.09 0.06 0.07 0.07 0.18 0.21 0.16 0.18 0.08 0.20 0.23 0.17 0.20 0.09 0.21 0.27 0.19 0.22Chiricahua NM 0.02 0.04 0.05 0.03 0.03 0.03 0.10 0.06 0.06 0.07 0.04 0.11 0.07 0.07 0.08 0.06 0.13 0.08 0.09 0.09Chiricahua Wild. 0.03 0.04 0.05 0.04 0.03 0.05 0.10 0.09 0.08 0.07 0.05 0.11 0.10 0.09 0.09 0.07 0.12 0.12 0.10 0.09Galiuro Wild. 0.03 0.04 0.03 0.03 0.02 0.10 0.09 0.06 0.08 0.08 0.10 0.10 0.06 0.09 0.09 0.11 0.11 0.07 0.09 0.09Gila Wild. 0.16 0.23 0.12 0.17 0.22 0.43 0.61 0.31 0.45 0.59 0.48 0.69 0.40 0.52 0.66 0.55 0.78 0.48 0.60 0.73Grand Canyon NP 0.06 0.03 0.02 0.04 0.03 0.15 0.09 0.04 0.09 0.09 0.17 0.09 0.04 0.10 0.11 0.19 0.09 0.04 0.11 0.12Mazatzal Wild. 0.03 0.02 0.03 0.03 0.01 0.06 0.06 0.08 0.06 0.06 0.06 0.06 0.08 0.07 0.07 0.06 0.07 0.09 0.07 0.08Mesa Verde NP 0.09 0.06 0.07 0.07 0.07 0.24 0.13 0.17 0.18 0.19 0.25 0.16 0.17 0.19 0.20 0.28 0.19 0.17 0.22 0.23Mount Baldy Wild. 0.13 0.16 0.14 0.14 0.16 0.35 0.42 0.33 0.36 0.42 0.39 0.48 0.33 0.40 0.44 0.45 0.54 0.38 0.46 0.50Petrified Forest NP 0.17 0.31 0.13 0.20 0.17 0.52 0.85 0.33 0.57 0.47 0.56 0.96 0.35 0.62 0.56 0.65 1.04 0.42 0.70 0.63Pine Mountain Wild. 0.01 0.01 0.01 0.01 0.02 0.03 0.02 0.03 0.03 0.04 0.03 0.02 0.04 0.03 0.05 0.03 0.03 0.04 0.04 0.06Saguaro NP 0.00 0.02 0.01 0.01 0.01 0.02 0.06 0.04 0.04 0.03 0.03 0.07 0.04 0.05 0.04 0.03 0.08 0.04 0.05 0.04San Pedro Parks Wild. 0.06 0.11 0.11 0.09 0.11 0.17 0.30 0.27 0.24 0.28 0.17 0.33 0.27 0.26 0.30 0.19 0.36 0.32 0.29 0.34Sierra Ancha Wild. 0.02 0.03 0.04 0.03 0.03 0.04 0.06 0.05 0.05 0.06 0.05 0.08 0.05 0.06 0.07 0.05 0.09 0.06 0.07 0.08Superstition Wild. 0.03 0.02 0.01 0.02 0.02 0.05 0.06 0.03 0.05 0.06 0.06 0.06 0.04 0.05 0.06 0.07 0.07 0.04 0.06 0.07Sycamore Canyon Wild. 0.02 0.03 0.01 0.02 0.01 0.04 0.09 0.04 0.06 0.05 0.05 0.10 0.04 0.06 0.06 0.05 0.11 0.06 0.07 0.07

Maximum 0.17 0.31 0.14 0.20 0.22 0.52 0.85 0.33 0.57 0.59 0.56 0.96 0.40 0.62 0.66 0.65 1.04 0.48 0.70 0.73

Cumulative (sum) 0.89 1.21 0.89 1.00 1.02 2.34 3.20 2.11 2.55 2.74 2.57 3.60 2.32 2.83 3.07 2.95 4.02 2.67 3.22 3.43

Gila Wilderness has the greatest 22nd high impacts for the base case; Petrified Forest has the greatest for the control scenarios.Gila Wilderness has the greatest benefit in 22nd high for all the control scenarios.
SRP Coronado, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 0.5 dv; for each of 2001, 2002, 2003; their Sum, and their Average (rounded to integer unless < 1)

Visibility Impacts, # Days m 0.5 dv

Visibility method: Control Scenario

vis8, 20best base_rs: SCR .08 u2 w/SO4 ctrl1_rs: SNCR u1; w/SO4 ctrl2_rs: SCR .05 u1; w/SO4 ctrl5_rs: SCR .05 w/SO4 ctrl6_rs: SCR -90%; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum AvgBandelier NM 0 3 7 10 3 0 0 5 5 2 0 0 1 1 0.3 0 0 1 1 0.3 0 0 0 0 0.0Chiricahua NM 0 1 2 3 1 0 0 1 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Chiricahua Wild. 1 2 3 6 2 1 0 2 3 1 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Galiuro Wild. 3 1 1 5 2 3 0 0 3 1 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0Gila Wild. 21 40 19 80 27 15 31 15 61 20 8 13 11 32 11 6 9 10 25 8 5 7 9 21 7Grand Canyon NP 6 2 0 8 3 5 1 0 6 2 1 0 0 1 0.3 1 0 0 1 0.3 0 0 0 0 0.0Mazatzal Wild. 0 1 1 2 0.7 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Mesa Verde NP 7 5 5 17 6 4 5 5 14 5 1 1 1 3 1 0 0 0 0 0.0 0 0 0 0 0.0Mount Baldy Wild. 20 17 15 52 17 16 16 14 46 15 5 4 7 16 5 4 4 6 14 5 3 1 4 8 3Petrified Forest NP 40 25 18 83 28 34 22 14 70 23 15 16 12 43 14 12 15 10 37 12 9 14 6 29 10Pine Mountain Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Saguaro NP 2 0 0 2 0.7 2 0 0 2 0.7 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0San Pedro Parks Wild. 3 12 10 25 8 1 6 6 13 4 0 0 1 1 0.3 0 0 1 1 0.3 0 0 1 1 0.3Sierra Ancha Wild. 1 3 1 5 2 0 2 1 3 1 0 1 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0Superstition Wild. 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Sycamore Canyon Wild. 0 1 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0

Maximum 40 40 19 83 28 34 31 15 70 23 15 16 12 43 14 12 15 10 37 12 9 14 9 29 10

Cumulative (sum) 105 113 82 300 100 81 83 63 227 76 32 35 33 100 33 23 28 28 79 26 17 22 20 59 20

Visibility Benefits, # Days m 0.5 dv

Visibility method: Control Scenario

vis8, 20best base_rs: SCR .08 u2 w/SO4 ctrl1_rs: SNCR u1; w/SO4 ctrl2_rs: SCR .05 u1; w/SO4 ctrl5_rs: SCR .05 w/SO4 ctrl6_rs: SCR -90%; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum AvgBandelier NM 0 3 2 5 2 0 3 6 9 3 0 3 6 9 3 0 3 7 10 3Chiricahua NM 0 1 1 2 1 0 1 2 3 1 0 1 2 3 1 0 1 2 3 1Chiricahua Wild. 0 2 1 3 1 1 2 3 6 2 1 2 3 6 2 1 2 3 6 2Galiuro Wild. 0 1 1 2 1 2 1 1 4 1 3 1 1 5 2 3 1 1 5 2Gila Wild. 6 9 4 19 6 13 27 8 48 16 15 31 9 55 18 16 33 10 59 20Grand Canyon NP 1 1 0 2 1 5 2 0 7 2 5 2 0 7 2 6 2 0 8 3Mazatzal Wild. 0 1 1 2 1 0 1 1 2 1 0 1 1 2 1 0 1 1 2 0.7Mesa Verde NP 3 0 0 3 1 6 4 4 14 5 7 5 5 17 6 7 5 5 17 6Mount Baldy Wild. 4 1 1 6 2 15 13 8 36 12 16 13 9 38 13 17 16 11 44 15Petrified Forest NP 6 3 4 13 4 25 9 6 40 13 28 10 8 46 15 31 11 12 54 18Pine Mountain Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Saguaro NP 0 0 0 0 0 1 0 0 1 0 2 0 0 2 1 2 0 0 2 0.7San Pedro Parks Wild. 2 6 4 12 4 3 12 9 24 8 3 12 9 24 8 3 12 9 24 8Sierra Ancha Wild. 1 1 0 2 1 1 2 1 4 1 1 3 1 5 2 1 3 1 5 2Superstition Wild. 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0.3Sycamore Canyon Wild. 0 1 0 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0 1 0.3

Maximum 6 9 4 19 6 25 27 9 48 16 28 31 9 55 18 31 33 12 59 20

Cumulative (sum) 24 30 19 73 24 73 78 49 200 67 82 85 54 221 74 88 91 62 241 80

Petrified Forest has the greatest number of days over 0.5 dv for the base case and all control scenarios.Gila Wilderness has the greatest decrease in number of days over 0.5 dv for all control scenarios.
SRP Coronado, Arizona RH FIP, July 2012

Number of days with delta deciview impacts greater than or equal to 1.0 dv; for each of 2001, 2002, 2003; their Sum, and their Average (rounded to integer unless < 1)

Visibility Impacts, # Days m 1.0 dv

Visibility method: Control Scenario

vis8, 20best base_rs: SCR .08 u2 w/SO4 ctrl1_rs: SNCR u1; w/SO4 ctrl2_rs: SCR .05 u1; w/SO4 ctrl5_rs: SCR .05 w/SO4 ctrl6_rs: SCR -90%; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum AvgBandelier NM 0 0 1 1 0.3 0 0 1 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Chiricahua NM 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Chiricahua Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Galiuro Wild. 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Gila Wild. 7 11 8 26 9 6 9 7 22 7 1 2 2 5 2 1 2 1 4 1 0 1 1 2 0.7Grand Canyon NP 1 0 0 1 0.3 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Mazatzal Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Mesa Verde NP 1 1 2 4 1 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Mount Baldy Wild. 2 4 6 12 4 2 2 5 9 3 0 0 1 1 0.3 0 0 1 1 0.3 0 0 0 0 0.0Petrified Forest NP 11 13 6 30 10 8 11 4 23 8 3 3 1 7 2 2 2 1 5 2 1 0 0 1 0.3Pine Mountain Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Saguaro NP 1 0 0 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0San Pedro Parks Wild. 0 1 1 2 0.7 0 0 1 1 0.3 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Sierra Ancha Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Superstition Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0Sycamore Canyon Wild. 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0 0 0 0 0 0.0

Maximum 11 13 8 30 10 8 11 7 23 8 3 3 2 7 2 2 2 1 5 2 1 1 1 2 1

Cumulative (sum) 24 30 24 78 26 17 22 18 57 19 4 5 4 13 4 3 4 3 10 3 1 1 1 3 1

Visibility Benefits, # Days m 1.0 dv

Visibility method: Control Scenario

vis8, 20best base_rs: SCR .08 u2 w/SO4 ctrl1_rs: SNCR u1; w/SO4 ctrl2_rs: SCR .05 u1; w/SO4 ctrl5_rs: SCR .05 w/SO4 ctrl6_rs: SCR -90%; w/SO4

Class I Area 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum Avg 2001 2002 2003 Sum AvgBandelier NM 0 0 0 0 0 0 0 1 1 0 0 0 1 1 0 0 0 1 1 0.3Chiricahua NM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Chiricahua Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Galiuro Wild. 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0.3Gila Wild. 1 2 1 4 1 6 9 6 21 7 6 9 7 22 7 7 10 7 24 8Grand Canyon NP 0 0 0 0 0 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0.3Mazatzal Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Mesa Verde NP 1 1 2 4 1 1 1 2 4 1 1 1 2 4 1 1 1 2 4 1Mount Baldy Wild. 0 2 1 3 1 2 4 5 11 4 2 4 5 11 4 2 4 6 12 4Petrified Forest NP 3 2 2 7 2 8 10 5 23 8 9 11 5 25 8 10 13 6 29 10Pine Mountain Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Saguaro NP 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0.3San Pedro Parks Wild. 0 1 0 1 0 0 1 1 2 1 0 1 1 2 1 0 1 1 2 0.7Sierra Ancha Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Superstition Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0Sycamore Canyon Wild. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0

Maximum 3 2 2 7 2 8 10 6 23 8 9 11 7 25 8 10 13 7 29 10

Cumulative (sum) 7 8 6 21 7 20 25 20 65 22 21 26 21 68 23 23 29 23 75 25

Petrified Forest has the greatest number of days over 1.0 dv for the base case and all control scenarios.Petrified Forest has the greatest decrease in number of days over 1.0 dv for all control scenarios.
Bandelie

r

Chiricah

ua

Chiricah

ua W. Galiuro Gila Grand Canyon Mazatzal Mesa Verde Mount Baldy Petrified Forest Pine Mountai n Saguaro San Pedro Parks Sierra Ancha Superstit ion Sycamor e Canyon

base_rs: SCR .08 u2 0.37 0.20 0.21 0.20 1.23 0.24 0.20 0.40 0.87 1.22 0.14 0.12 0.54 0.24 0.21 0.16ctrl1_rs: SNCR u1 0.30 0.16 0.18 0.18 1.00 0.20 0.19 0.33 0.71 1.05 0.13 0.10 0.43 0.21 0.19 0.15

ctrl2_rs: SCR .05 u1 0.19 0.13 0.14 0.12 0.64 0.15 0.14 0.21 0.46 0.74 0.10 0.08 0.26 0.18 0.16 0.11ctrl5_rs: SCR .05 0.17 0.12 0.12 0.11 0.57 0.13 0.13 0.20 0.43 0.66 0.10 0.08 0.23 0.18 0.15 0.10ctrl6_rs: SCR -90% 0.15 0.11 0.11 0.10 0.49 0.12 0.12 0.17 0.38 0.59 0.09 0.07 0.20 0.17 0.14 0.09

0.00.20.40.60.81.01.21.4

SRP Coronado 2001-2003 Visibility Impacts, EPA RH FIP July 2012 (dv) Visibility

method: vis8, 20best
Bandelie

r

Chiricah

ua

Chiricah

ua W. Galiuro Gila Grand Canyon Mazatzal Mesa Verde Mount Baldy Petrified Forest Pine Mountai n Saguaro San Pedro Parks Sierra Ancha Superstit ion Sycamor e Canyon

base_rs: SCR .08 u2ctrl1_rs: SNCR u1 0.07 0.03 0.03 0.02 0.22 0.03 0.01 0.07 0.16 0.17 0.02 0.01 0.11 0.03 0.02 0.01

ctrl2_rs: SCR .05 u1 0.18 0.07 0.07 0.08 0.59 0.09 0.06 0.19 0.42 0.47 0.04 0.03 0.28 0.06 0.06 0.05ctrl5_rs: SCR .05 0.20 0.08 0.09 0.09 0.66 0.11 0.07 0.20 0.44 0.56 0.05 0.04 0.30 0.07 0.06 0.06ctrl6_rs: SCR -90% 0.22 0.09 0.09 0.09 0.73 0.12 0.08 0.23 0.50 0.63 0.06 0.04 0.34 0.08 0.07 0.07

0.00.10.20.30.40.50.60.70.8

SRP Coronado 2001-2003 Visibility Benefits, EPA RH FIP July 2012 (dv) Visibility

method: vis8, 20best