Technical Analysis for Arizona and Hawaii Regional 

Haze FIPs: Report on Identification of Sources Subject

to BART

Work Assignment: 5-12

Contract No: EP-D-07-102

Task No. 6

Version 4

Prepared for: Thomas Webb

Air Planning Office

U.S. EPA Region 9

75 Hawthorne Street

San Francisco, CA 94105

Prepared by: Uma Shankar, Liz Adams, Mohammad Omary, 

 Brian Naess, and Sarav Arunachalam

Institute for the Environment

University of North Carolina at Chapel Hill

Date delivered: July 20, 2012
EMAQ LOE (EPA Contract EP-D-07-102) WA 5-12, Task 6: BART Subject Determination Report

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Contents

Document Change Record ..........................................................................................................iii

1 Introduction............................................................................................................................ 1

2 Work Performed and Deliverable Summary ...................................................................... 1

2.1 CALPUFF Model Setup ................................................................................................. 3

2.1.1 Stack Parameters .................................................................................................5

2.1.2 Emissions Inputs..................................................................................................5

2.2 POSTUTIL Processing ................................................................................................... 6

2.3 CALPOST Setup............................................................................................................. 6

3 Results..................................................................................................................................... 7

4 Conclusions............................................................................................................................. 9

References.................................................................................................................................... 10
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Document Change Record

Revision Date Remarks

0.1 March 26, 2012 First version submitted to EPA

2.0 March 30, 2012 Ver. 2 submitted to EPA- corrected Sec. 3 and 4 

3.0 April 7, 2012 Ver. 3 submitted to EPA - used POSTUTIL and 

CALPOST v6.221, corrected sections 2, 3 and 4 

4.0 July 20, 2012 Ver. 4 submitted to EPA – corrected Sections 3 and 

4 to reflect speciated PM input corrections in 

CALPUFF.
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1 Introduction

Work Assignment (WA) 5-12 under EPA contract EP-D-07-102 states the following objective

for the regional haze rule (RHR) assessments to be performed for emission sources in Arizona:

The technical analysis for Arizona’s Regional Haze FIP is focused on performing a 

Best Available Retrofit Technology (BART) analysis and a reasonable progress (RP) 

analysis, and on identifying reasonable progress goals (RPGs) for four Class I Areas 

(CIAs) out of twelve that receive visibility protection under RHR. 

Of particular interest in this WA are large emission sources that could adversely impact visibility 

at four Southern Arizona CIAs, namely, Chiricahua National Monument, Chiricahua Wilderness, 

Saguaro Wilderness and Galiuro Wilderness. Several of the first nine tasks in the WA are aimed 

at assessing the incremental visibility impairment due to selected large emission sources in 

Arizona, through a combination of their emission strength and proximity, at any CIA within a 

300-km radius of each. A visibility impact relative to background visibility by more than a 0.5-

deciview (dv) threshold at any such CIA, assessed through dispersion modeling in Task 6 of this 

WA, would identify the emitting facility as subject to BART. EPA had already identified two 

facilities as eligible for the Task 6 analysis when the WA was issued: Tucson Electric Power 

(TEP) Sundt (Irvington) Generating Station, and Arizona Portland Cement Company. Task 3 of 

the WA involved identifying additional facilities eligible for BART analysis based on their 

exceedance of an emissions threshold of 250 tons per year (TPY) in any of the visibilityimpairing pollutants (NOx, SO2, and speciated or unspeciated particulate matter [PM]). UNC 

identified 28 such facilities, including the two listed above, based on annual emissions data from

the Western Regional Air Partnership (WRAP) planning inventory for 2002. UNC presented the 

facilities list in a memo and delivered it, along with documentation of the emissions inventory

data used, to the EPA on December 9, 2011. In Task 4 of the WA UNC further screened these

facilities by comparing their Q/D ratios against a threshold value of 10 TPY/km, where Q is the 

total emission rate in TPY from a facility, and D is its nearest distance in kilometers to any CIA 

within a 300-km radius. EPA eliminated a number of these facilities from further BART analysis 

due to a combination of the age of the facility and its Q/D value. In subsequent modifications to 

the WA’s analysis tasks, EPA selected only one facility among those remaining—TEP Sundt 

(Irvington) Generating Station, Unit 4—for the Task 6 dispersion modeling for the years 2001-

2003. The purpose of this modeling is to compare the incremental impact of this unit’s NOx, SO2

and PM emissions on visibility at all CIAs within a 300-km radius, against the threshold of 0.5 

dv. This report summarizes the analysis performed for this unit in this task.

2 Work Performed and Deliverable Summary

Figure 1 displays the Arizona CIAs in the vicinity of Irvington Generating Station, a four-unit 

plant of which Unit 4 is the only coal-fired unit; the three other smaller units are natural-gas 

fired. UNC used a GIS software tool to determine the nearest distance D (km) to the boundaries

of all the CIAs within a 300-km radius of the major facilities, including Irvington Generating 

Station. In determining D, it was found that more than one near-distance was possible to certain 

CIAs (e.g., Saguaro Wilderness), depending on how their geographic extent was specified in the 

GIS database. In these instances, all available distances to that CIA were recorded. The domain 
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description and Lambert Conformal grid specifications needed for this determination came from 

the CALPUFF meteorological inputs from the CALMET model provided by EPA. Table 1 lists 

the CIAs within 300 km of Irvington Generating Station at which the incremental visibility 

impact would need to be determined, along with their Q/D values as determined in Task 4; in 

that screening task , Q was the combined total emission per year from all pollutants (SO2, NOx, 

and PM) emitted by this facility using data from the WRAP planning inventory for 2002. 

Figure 1. Area map of Arizona CIAs in the vicinity of TEP Sundt (Irvington) Generating Station.

CIAs within a 300-km radius are shown in purple; green dots are nearest-distance 

points from the facility to the CIA boundary .

. 
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Table 1. Q/D Values at CIAs Affected by Irvington Generating Station 

(Q = 5920.54 TPY) Compared to a Threshold of 10 TPY/km.

2.1 CALPUFF Model Setup

Meteorological inputs as well as monthly background ozone data for CALPUFF were provided 

by EPA, and were generated through a prior contract with ENSR Corporation for the 2001-2003 

modeling period for BART analysis of the Tucson Electric Power Navajo Generating Station 

(ENSR, 2009). Thus, the modeling domain specifications for CALPUFF were taken from the 

CALMET input data. Figure 2 displays the modeling domain from the ENSR modeling that is 

used in the analysis described here.

As stated in the modeling protocol, we used the following versions of the modeling components:

a) CALMET Version 5.8 level 070623

b) CALPUFF version 5.8 level 070623

Class I Area (CIA) 

Within 300 km

Abbreviation D (km) Q/D 

(TPY/km)

Saguaro Wilderness sagu 15.84 373.79

Saguaro Wilderness " 24.29 243.76

Saguaro Wilderness " 28.28 209.38

Saguaro Wilderness " 29.21 202.68

Saguaro Wilderness " 31.75 186.50

Galiuro Wilderness gali 62.69 94.44

Superstition Wilderness supe 136.14 43.49

Chiricahua Wilderness chrw 140.43 42.16

Chiricahua NM WildernessNot Studied

chir 143.94 41.13

Chiricahua NM WildernessDesignated Wilderness

" 143.67 41.21

Chiricahua NM WildernessDesignated Wilderness

" 145.69 40.64

Chiricahua NM WildernessDesignated Wilderness

" 145.40 40.72

Sierra Ancha Wilderness sian 178.17 33.23

Mazatzal Wilderness maza 201.26 29.42

Gila Wilderness gila 230.79 25.65

Mount Baldy Wilderness mobo 231.16 25.61

Pine Mountain Wilderness pimo 246.41 24.03
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c) POSTUTIL version 1.56 level 070627

d) CALPOST version 6.221

Figure 2. BART modeling domains for this task (blue boundary) and for 

WRAP’s 2007 BART Subject modeling for Arizona (red boundary). 

Source: ENSR (2009).
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The CALPUFF model setup for Irvington Generating Station followed the guidance of the 

modeling protocol for Tasks 6, 7, and 8 of this WA, which was delivered to EPA on March 19, 

2012, as a Task 5 deliverable. This modeling protocol invokes almost all the model input settings 

provided in the CALMET/CALPUFF Protocol for BART Exemption Screening Analysis for 

Class I Areas in the Western United States (hereafter WRAP BART Protocol [WRAP, 2006], 

provided in the WA 5-12 modeling protocol’s Appendix A). Differences in model setup from the 

recommendations of the WRAP BART Protocol due to the CALPUFF version used, or to 

direction from the EPA, are noted in the WA 5-12 modeling protocol. UNC verified and 

reconciled any discrepancies in the CALPUFF inputs through a series of test runs. Of note, 

CALPUFF modeling used a constant value of 1 ppb throughout for ammonia, per EPA guidance. 

Further details specific to the Irvington Generating Station CALPUFF modeling are provided in 

the following sections.

2.1.1 Stack Parameters

The stack parameter data for Irvington’s Unit 4 were obtained from the EPA National Emissions 

Inventory (NEI) 2008 version 2, the latest inventory available to us. An examination of the 

WRAP planning inventory used in obtaining emissions data for previous screening calculations 

on this unit showed an unrealistically low stack velocity (0.29 m/s). The 2008 NEI had a value 

(24.08 m/s) much closer to the value of 16.8 m/s used in the previous BART analysis by WRAP.

Table 2 summarizes the stack parameters for all four units of Irvington; Unit 4 is the one of 

relevance for the Task 6 inputs to CALPUFF.

Table 2. Stack Parameters for Irvington Generating Station.

Data sources: WRAP BART Analysis for stack elevation; 2008 NEI Version 2 for other parameters.

2.1.2 Emissions Inputs

Emissions inputs for the CALPUFF modeling for Irvington Generating Station, Unit 4, are given 

in Table 3. EPA provided guidance on the emissions data sources for all of the BART sources

analyzed in this WA; these data sources are documented for each applicable facility and unit in 

Table B-1 of the WA 5-12 modeling protocol. Per this guidance, the input emissions for 

Irvington’s Unit 4 were obtained from the following data sources:

 The EPA Clean Air Markets Division’s (CAMD’s) Continuous Emission Monitoring 

System (CEMS) database for SO2 and NOx, chosen individually as the maximum 24-h 

average hourly emission rate from the years 2008-2010 during periods of steady-state 

operation

LON LAT

deg deg ft m ft m ft m F K ft/s m/s

Unit 1 -110.90490 32.16011 130.00 39.62 2608.00 794.92 10.52 3.21 260.00 399.67 29.00 8.84

Unit 2 -110.90490 32.16011 130.00 39.62 2608.00 794.92 10.82 3.30 260.00 399.67 27.00 8.23

Unit 3 -110.90490 32.16011 144.00 43.89 2608.00 794.92 12.31 3.75 246.00 391.89 29.00 8.84

Unit 4 -110.90490 32.16011 248.00 75.59 2608.00 794.92 10.28 3.13 287.00 414.67 79.00 24.08

FACILITY Exit Velocity

UNIT #

Stack Height Stack Elevation Stack Diameter Stack Temperature
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 The WRAP BART analysis inputs of 2007 for total (unspeciated) PM

 The National Park Service spreadsheet data for filterable PM speciation for a Pulverized 

Coal Dry Bottom Boiler with Fabric Filter to better represent the visibility impacts of the 

constituent species (see 

http://www.nature.nps.gov/air/Permits/ect/docs/coalBoiler/2006FinalDryBottomPC_FFp

mSpeciationProfile.xls)

o U.S. Energy Information Administration (EIA) data on coal heating value, sulfur 

content, and coal ash content for Routt County, Colorado, coal needed as inputs to 

the PM speciation spreadsheet above

Test runs with the speciated PM inputs revealed that the CALPUFF version 5.8 code requires an 

input name “SOA” for organic carbon, even when it may be primary organic carbon (from 

filterable PM). Also note that we have converted the spatial coordinates of the facility from 

latitude/longitude to Lambert Conformal Conic projection below.

Table 3. CALPUFF Emission Inputs for Irvington Generating Station.

LCC - X 

(km)

LCC - Y 

(km)

SO2

(g/s)

SO4

(g/s)

NOx

(g/s)

HNO3

(g/s)

NO3

(g/s)

PMF

(g/s)

PMC 

(g/s)

EC 

(g/s)

SOA 

(g/s)

-1305.701 -768.586 117.985 2.561 70.364 0.0 0.0 0.0365 1.007 0.970 0.642

2.2 POSTUTIL Processing

This document revision (v3) includes the changes made to the visibility modeling based upon 

EPA’s recent guidance concerning CALPUFF Version 5.8. According to this guidance, this 

version does not adequately partition condensable nitrate between gas-phase HNO3 and particle 

phase NO3, which occurs due to the presence of ambient ammonia. This would have implications 

for the visibility assessments as aerosol nitrate has comparable extinction efficiency to that of 

sulfate. To better estimate this gas-particle partitioning of nitrate using the ammonia limitation 

method (ALM), the post-processor POSTUTIL, version 1.56 level 07062 was used with a setting 

of MNITRATE = 1. This option calculates the partitioning using the total concentrations of SO4, 

HNO3, NO3 and NH3 from all sources. Ammonia is set to a constant background concentration 

of 1 ppb per EPA guidance. The resulting concentration file is input to CALPOST for the 

visibility calculations. We downloaded and compiled the POSTUTIL code after the necessary 

modifications needed for the Linux platform, and post-processed the CALPUFF outputs for 

2001-2003. We also combined the 3 years’ outputs from POSTUTIL using the APPEND postprocessor for calculating the 98th percentile visibility impairment in all three years combined.

2.3 CALPOST Setup

As with the CALPUFF modeling, the WA 5-12 modeling protocol primarily relied on the WRAP 

BART Protocol (WRAP, 2006) and notes differences from that protocol as needed. Of note, 
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postprocessing of CALPUFF output with CALPOST used both IMPROVE Method 6 and 

Method 8 (submode 5) for calculation and comparison of the incremental visibility impairment 

(Δ-dv) relative to background at the affected CIAs. Each method used two sets of background 

visibility conditions in these assessments, corresponding to the annual-average background 

visibility, and the background visibility on the 20%-best-visibility days at the CIAs. For both 

Method 6 and the submode option 5 chosen for Method 8, CALPOST uses the input values of 

monthly-average relative humidity adjustment factor f(RH), rather than the hourly f(RH) values 

input in the VISB.DAT file generated by CALPUFF. We refer the reader to the modeling 

protocol for the actual data such as annual average background visibility, site-specific 

background concentrations of PM constituents for the 20% best visibility days, monthly f(RH), 

etc. used in our processing

This document revision includes changes to the results due to the CALPOST code version used. 

At the start of this task the version recommended by EPA, Version 6.221 was not available for 

download from the CALPUFF website. Since the Work Plan calls out the use of this code 

version, EPA provided the source code, which we then modified for the Linux platform and 

compiled. We also modified all the inputs to conform to the code version used, and did some test 

runs to determine the direction of the change in the results. Overall, the combined effect of using 

POSTUTIL and CALPOST v6.221 is a moderate decrease in the incremental visibility change 

(Δ-dv) at all the CIAs in all years and for all cases compared to the previous results.

3 Results

Table 4 provides the model results extracted by the POSTCALPOST utility developed by UNC 

for the incremental visibility impairment relative to background at the CIAs listed in Table 1. 

The results are broken down as follows:

 8

th

-highest Δ-dv (98th percentile) at each CIA within 300 km of Irvington Generating 

Station in each of the years 2001, 2002, and 2003 for:

o Method 6, annual-average background conditions 

o Method 8, annual-average background conditions

o Method 6, 20%-best-visibility background conditions

o Method 8, 20%-best visibility background conditions

 22nd-highest Δ-dv (98th percentile) from all three years combined for the same four 

methods as above

Table 4(a) contains all results for Method 6, and Table 4(b), the corresponding results for 

Method 8. The numbers of days of contribution threshold exceedance at each CIA for Method 6 

and Method 8 are summarized in Table 5 (a) and (b) respectively.
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Table 4. 98th-Percentile Changes in Visibility at the CIAs within 300 km of Irvington Generating 

Station using (a) IMPROVE Method 6 and (b) IMPROVE Method 8 (submode 5).

(a)

(b)
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Table 5. Number of days of exceedance of the contribution threshold of 0.5 dv at each CIA for 

(a) Method 6 and (b) Method 8.

(a)

(b)

4 Conclusions

A comparison of the Δ-dv between annual-average and 20%-best-visibility conditions shows 

somewhat greater values overall for the latter set of background conditions. This is because the 

background deciview is lower when considering only the 20%-best-visibility days of the year, 

rather than the average good (background) condition days for the whole year; thus the visibility 

impairment relative to this lower background is greater. The last two columns of Table 4(a) for 

IMPROVE Method 6 show that two CIAs (Saguaro and Galiuro Wilderness Areas, in decreasing 

order of impact) experienced a greater than the 0.5-dv threshold incremental visibility 

impairment due to emissions from Irvington Generating Station, Unit 4 for the three modeled 

years using either set of background conditions. Table 5(a) shows that this exceedance occurred 

over a significant number of days of the year for Saguaro Wilderness. Considering individual 

years, in 2003 the Chiricahua NM Wilderness Area also had the 98th percentile visibility 

impairment near threshold for the 20% best background visibility conditions; -dv values for this 
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CIA and for Chiricahua Wilderness were, respectively the 3rd and 4

th highest among all the CIAs 

in all three years for either set of background visibility conditions.

Table 4(b) shows that compared to Method 6, the incremental impairment in visibility is 

uniformly lower using IMPROVE Method 8, which considers the differential extinction of light 

by small and large particles; the small particles are the most significant contributor to light 

extinction, and there are fewer of them contributing in Method 8 than in Method 6. However, the 

two CIAs in Table 4(b) that show impairment above threshold in all three modeled years are the 

same as for Method 6. Further, as with Method 6, Chiricahua NM Wilderness shows impairment

in visibility nearly at threshold in 2003 under the 20%-best- background visibility conditions. As 

in Table 4(a), -dv values for this CIA and Chiricahua Wilderness were the 3rd and 4

th highest, 

respectively, among all the CIAs, in all three years for either set of background visibility 

conditions. 

Table 5(b) shows not as many days of exceedance for Method 8 as for Method 6; however, for 

either set of background conditions Saguaro wilderness sees many days above the contribution

threshold in all years for either visibility method.

These findings can be summarized as follows: 

 Irvington Generating Station Unit 4’s incremental impact on visibility is significantly 

above the impairment threshold of 0.5 dv for a significant number of days at two out of 

ten CIAs within a 300-km radius of the facility in all the years modeled.

 The visibility impairment is worst at Saguaro, followed by Galiuro Wilderness.

o This applies to both calculation methods, and both sets of background conditions. 

o Greater impacts are seen for Method 6 than for Method 8, and for the 20%-best

background than for the annual average background conditions. 

Conclusion: This unit is found to be subject to BART.

References

ENSR, 2009: 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.

WRAP, 2006: CALMET/CALPUFF Protocol for BART Exemption Screening Analysis for 

Class I Areas in the Western United States. Western Regional Air Partnership Air Quality 

Modeling Forum, Regional Modeling Center, August 15, 2006; 

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