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PREFACE 

 On 6 July 2005, the U.S. Environmental Protection Agency (EPA) published final amendments 

to its 1999 Regional Haze Rule in the Federal Register, including Appendix Y, the final guidance for 

Best Available Retrofit Technology (BART) determinations (70 FR 39104-39172). ). The BART rule 

requires the installation of BART on emission sources that fit specific criteria and “may reasonably be 

anticipated to cause or contribute” to visibility impairment in any Class I area. Air quality modeling is 

the preferred method for determining which emission sources cause or contribute to visibility 

impairment. 

 This document establishes guidelines for performing dispersion modeling analyses in support 

of BART determinations for sources located within the CENRAP domain. Largely consistent with 

EPA guidelines, these CENRAP BART Modeling Guidelines cover the many assumptions, data base 

elements, model configurations and analytical methods that CENRAP states and/or source operators 

should consider using in their assessments of whether BART eligible sources are indeed ‘subject to 

BART’, or may be exempted. For those sources determined to be subject to BART, these guidelines 

provide for a common and consistent methodology for estimating the visibility improvements 

associated with BART emissions reductions. 

 Each state is required to develop a BART Modeling Protocol setting forth the required steps in 

assessing the levels of controls needed on sources subject to BART. At the same time, the five (5) 

Regional Planning Organizations (RPOs) are addressing the requirement of the Regional Haze Rule in 

a generally consistent manner, with some exceptions for how BART is treated. The Midwest RPO for 

example, is expected to conduct most of the BART modeling for sources within its region. In the 

VISTAS states, the BART modeling is expected to be a shared exercise between VISTAS and the 

states. In the central states, the states themselves will take the lead in the BART modeling, but 

CENRAP will provide assistance in the form of modeling guidance (this document) and readilyavailable modeling data bases (delivered separately) that can be used by states and/or source operators 

to conduct their analyses. 

 Deferring to the states and RPO’s, EPA has placed the responsibility of preparing modeling 

protocols with the groups who will actually be performing the modeling, rather than developing a 

prescriptive protocol covering all states and sources. EPA has provided so-called BART modeling 

guidelines (EPA, 2005) which set for the general framework for performing the analyses. It is up to 

the states and RPO’s to develop the modeling protocols governing the BART modeling activities 

within their jurisdictions. 

 Several BART modeling protocols have been developed within the past year prior to and in 

parallel with these CENRAP BART Modeling Guidelines. In the interest of providing consistency in 

the selection, use, and interpretation of models and analytical methods, we have attempted to 

synthesize key unifying elements of these protocols and weave them into a consistent set of modeling 

procedures for the CENRAP region, paying attention to the unique characteristics of this region and 

the sources located within. At the same time, EPA guidance on how the BART modeling analyses will 

be judged has evolved and many protocols as well as this guideline document have been refined to 

reflect EPA’s clarifications. 

 Several modeling protocols developed by other RPOs and State agencies are particularly 

relevant to CENRAP’s effort to develop consistent guidelines for the Central states. Six BART 

protocols are especially significant: 
 

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 > “VISTAS Protocol for the Application of the CALPUFF Model for Analyses of Best 

Available Retrofit Technology (BART)”, (VISTAS, 2005). Prepared by the Visibility 

Improvement State and Tribal Association of the Southeast (VISTAS) Technical 

Analysis Work Group (TAWG), and Earth Tech, Inc. 

> “CALPUFF Modeling Protocol in Support of Best Available Retrofit Technology 

Determinations”, (Johnson, 2005). Prepared by the Iowa Department of Natural 

Resources, Air Quality Bureau, Des Moines, IA. 

 > “Best Available Retrofit Technology (BART) Modeling Protocol to Determine Sources 

Subject to BART in the State of Minnesota”, (MPCA, 2005). Prepared by the Minnesota 

Pollution Control Agency, St. Paul, MN. 

 

> “Modeling to Support BART”, (Baker, 2005). Prepared by the Midwest Regional 

Planning Organization and the Lake Michigan Air Directors Consortium, Des Plaines, 

IL. 

> “CALMET/CALPUFF BART Protocol for Class I Federal Area Individual Source 

Attribution Visibility Impairment Modeling Analysis”, (CDPHE, 2005). Prepared by the 

Air Pollution Control Division, Colorado Department of Public Health and 

Environment, Denver, CO. 

 > “Screening Analysis of Potentially BART-eligible Sources in Texas”, (ENVIRON, 

2005). Prepared for the Texas Commission on Air Quality, Austin, TX. 

All of these protocols address a common subject; thus, there is substantial overlap in the discussions of 

numerous topics such as Federal requirements, EPA guidance, CALMET/CALPUFF model 

descriptions, and recommended modeling procedures and so on. There are differences, of course, due 

to local meteorology, topography, location of Class I areas, the mix of BART-eligible sources, and 

established modeling procedures within the state, local and federal land manager (FLM) groups. 

 To promote consistency in BART modeling applications across the central and eastern U.S., in 

preparing these CENRAP Guidelines, we have incorporated common elements of existing protocols 

where possible. The VISTAS protocol deserves special mention. It was prepared jointly by members 

of the VISTAS Technical Analysis Work Group (TAWG) led by Ms. Pat Brewer, VISTAS’ Technical 

Advisor Dr. Ivar Tombach, and Mr. Joe Scire of Earth Tech, Inc. The VISTAS protocol represents 

the culmination of several draft versions and considerable public discussion and input. At least two 

public workshops were convened in the autumn of 2005 to solicit comments and suggestions on draft 

versions and to receive input from EPA staff on evolving agency guidance. Details of these public 

discussions may be found at: http://www.vistas-sesarm.org/BART/BARTComments.asp. Because the 

VISTAS protocol reflects the work of a large number of organizations, we have incorporated a number 

of the recommendations set for the therein..

 In summary the CENRAP BART Modeling Guidelines presented in this document represent 

the integrated writing efforts of many groups, especially the modelers and regulatory decision-makers 

instrumental in developing the VISTAS, MRPO, Iowa, Minnesota, Texas, and Colorado BART 

Modeling Protocols. The authors are indebted to the contributions of these groups, and assume 
 

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responsibility for any misstatements or errors in incorporating written descriptions from the 

aforementioned documents. 

ACKNOWLEDGMENTS 

The authors wish to acknowledge specifically the assistance and, in several cases, written 

contributions by the following individuals in the preparation of this guidance document: 

Mr. Chris Arrington, West Virginia Department of Environmental Protection; Mr. Bret 

Anderson, U.S. EPA; Dr. Kirk Baker, Lake Michigan Air Directors Consortium; Ms. Pat 

Brewer, VISTAS Technical Coordinator; Mr. Chad Daniels, Iowa Department of Natural 

Resources; Dr. Bright Dornblaser, Texas Commission on Environmental Quality; Mr. 

Todd Hawes, EPA/OAQPS; Ms. Cyndi Huber, U.S. Forest Service; Mr. Matthew 

Johnson, Iowa Department of Natural Resources; Ms. Margaret McCourtney, Minnesota 

Pollution Control Agency; Mr. Bruce Polkowsky, National Park Service; Mr. Tom 

Rodgers, Florida Department of Environmental Protection; Ms. Rosalina Rodriguez, 

North Carolina Department of Natural Resources; Mr. Joe Scire, Earth Tech, Inc.; Dr. 

Ivar Tombach, VISTAS Technical Advisor; Mr. John Vimont, National Park Service; and 

Ms. Lee Warden, Oklahoma Department of Environmental Quality. 

Particular recognition is due Mr. Ralph Morris of ENVIRON International Corporation who served as 

an independent technical reviewer throughout the course of this study and provided many useful 

suggestions, insightful recommendations and key text.