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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
 

REGION 8
 

1595 Wynkoop Street 

DENVER, CO 80202-1129 

Phone 800-227-8917 

http://www.epa.gov/region08 

FEB 2 8 2007 

Ref: 8P-AR 

Joe Scheeler 

Ash Grove Cement Company 

100 Highway 518 

Clancy, MT 59634-9701 

Re:	 Results of "Subject to" Visibility Modeling for Best Available Retrofit Technology 

(BART) and Request to Conduct a BART Analysis for BART-Eligible Units at Ash 

Grove Cement Company 

Dear Mr. Scheeler: 

On June 19,2006, EPA received a letter from the Montana Department of Environmental 

Quality that stated it was withdrawing its efforts to meet the requirements of the Regional Haze 

Rule (RHR) specified at 40 CFR 51.308. On September 27,2006, EPA Region 8 sent a letter 

notifying you that we would be conducting modeling to determine which sources in Montana are 

"subject to" the Best Available Retrofit Technology (BART) requirements in the RHR as part of 

our effort to address the requirements of that rule. Since it was determined that Ash Grove 

Cement Company (Ash Grove) was BART eligible, we informed you that Ash Grove would be 

included in the modeling and asked you to certify the data that would be used for this modeling. 

EPA Region 8, with the assistance of the Western Regional Air Partnership (WRAP), has 

now completed the visibility modeling for determining those Montana sources subject to BART. 

Based on the modeling, EPA Region 8 has determined that your facility is subject to BART. 

Accordingly, we are requesting that you submit a BART Analysis for Ash Grove within 90 days 

of this letter, as explained below. 

In modeling Ash Grove's visibility impacts, EPA Region 8 followed the approach for 

determining if a source is subject to BART, including the specifics on how the modeling should 

be performed, set out in the final RHR and EPA's "Guidelines for Best Available Retrofit 

Technology Determinations" (BART Guidelines). See 70 FR 39104, July 6, 2005. The BART 

Guidelines can be found at Appendix Y to 40 CFR Part 51. EPA Region 8's visibility modeling 

also generally followed the protocol outlined in the document "Draft CaipuffBART Modeling 

Protocol for Federal Mandatory Class 1 Areas" (Montana Department of Environmental Quality, 

September 2006). An electronic copy of this protocol is located on EPA Region 8's website at 

http://www.epa.gov/region8/air/mtregionalhaze.html. Where necessary, we made slight 

variations to the protocol, such as instances where meteorological data was not available for a 

certain site. 
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States (or EPA) have several options for determining whether a source is subject to 

BART, including the use of dispersion modeling to determine whether an individual source may 

be reasonably anticipated to cause or contribute to any visibility impairment in any Class I area. 

When dispersion modeling is used, part ofthe process of determining whether a source is subject 

to BART is the selection of a deciview threshold against which to measure the visibility impact 

of a source. For its analysis of Montana sources, EPA Region 8 has established a threshold of 

0.5 deciviews as the appropriate threshold based on the number and distribution of sources 

impacting Class I areas in and around Montana. If dispersion modeling predicts that a source 

will have visibility impacts of0.5 deciviews or more at a Class I area on the 98th percentile of 

values, EPA Region 8 considers that source to be subject to BART. Further information 

regarding this approach to determining whether a source is subject to BART can be found in 

section lILA ofthe BART Guidelines. 

For Ash Grove, the modeling results show a maximum 98th percentile impact within a 

Class I area of2.70 deciviews, which exceeds the threshold of 0.5 deciviews. Since Ash Grove 

exceeds the 0.5 deciview threshold, and thus may reasonably be anticipated to cause or contribute 

to visibility impairment in one or more Class I areas, EPA Region 8 has concluded that Ash 

Grove is subject to BART. 

A summary of the BART modeling results is enclosed. The enclosure provides a 

summary of the 98th percentile predictions for the three years modeled for Ash Grove at all 

federal Class I areas in the vicinity of the plant. More detailed modeling results, including the 

electronic CALPUFFICALMET files, are available on the WRAP website at 

http://pah.cert.ucr.edu/agrn/308/bart.shtml. 

Because Ash Grove is subject to BART, EPA Region 8 is requesting that Ash Grove 

conduct a BART engineering analysis on the emission units specified on the enclosed 

spreadsheet and submit the analysis to our office. One ofthe requirements ofthe RHR is that 

each regional haze implementation plan contain enforceable emission limits for eligible 

stationary sources based on BART. The BART analysis will be used to identify the best system 

of continuous emissions reduction and corresponding emission limits for each visibility 

impairing pollutant that is emitted by the Ash Grove facility. The Clean Air Act and the RHR 

require that BART be established on a case-by-case basis taking into account the available 

retrofit control options, the costs of compliance, the energy and non-air quality impacts of 

compliance, any pollution control equipment in use at the source, the remaining useful life of the 

source, and the degree of improvement in visibility which may reasonably be anticipated to result 

from the use ofthe technology. 

For purposes ofthe Regional Haze FIP for Montana, EPA Region 8 is intending to follow 

its BART Guidelines from 40 CFR Part 51, Appendix Y. The BART Guidelines are a statement 

of EPA's thinking on how best to meet the requirements of BART in the CAA and RHR. Thus, 

in conducting the Ash Grove BART engineering analysis, you will need to follow the five-step 
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BART analysis process identified in Appendix Y, section IV.D, in order to identify an 

appropriate BART emission limit. The five steps are: 

• Identify all available retrofit control technologies 

• Eliminate technically-infeasible options 

• Evaluate the control effectiveness of remaining control technologies 

• Evaluate impacts and document the results 

• Evaluate visibility impacts 

For each of these five steps, the BART Guidelines provide detailed guidance for 

producing an acceptable BART analysis. In addition, your BART analysis should follow other 

EPA guidance and policies related to BART. 

Based on the above analysis, you will then identify what you believe is BART for your 

facility. You will need to provide ajustification for adopting the technology and the emission 

limits that you select as the best level of control, including an explanation of how the BART 

factors (costs of compliance, energy impacts, non-air quality environmental impacts, remaining 

useful life of the facility, and visibility improvements) were considered (or weighted) in selecting 

one technically feasible control option over the others. 

Your BART analysis should include proposed emission limits for each BART-eligible 

unit at your facility and for each pollutant subject to BART. For Ash Grove Cement we have 

identified sulfur dioxide, nitrogen oxides, and particulate matter as the pollutants that need to be 

analyzed. 

Once you submit the BART analysis and related documentation to EPA Region 8, we will 

review the BART analysis and will notify you of our preliminary BART determination. We will 

provide an opportunity for you to respond to our preliminary BART determination before making 

a final determination. Our final determination will be included as part of our Regional Haze FIP 

for Montana, which will be adopted through notice and comment rulemaking. 

In order to meet regulatory schedules and coordinate with other states, EPA Region 8 is 

requesting that you submit your BART analysis to our offices within 90 days from the date of 

this letter. We understand this is a complicated endeavor, and we are available to answer any 

questions that you may have on the RHR, the BART Guidelines, or the BART analysis. We will 

assist you in any way we can and look fornard to working with you. 

If you choose not to perform or are unable to perform an engineering analysis for Ash 

Grove, EPA will perform the BART engineering analysis. If you will not be performing and 

submitting the BART analysis, we ask that you contact us within 30 days from the date of this 

letter so that we may begin the process of developing the analysis. 

Ash Grove may assert a business confidentiality claim covering part or all of the 

information requested by this letter, in the manner described at 40 CFR 2.203(b). If no such 
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claim accompanies the information when it is received by EPA, EPA may make the information 

available to the public without further notice to Ash Grove. Information subject to a business 

confidentiality claim will be disclosed by EPA only to the extent, and by means ofthe 

procedures, set forth at 40 CFR Part 2, Subpart B. 

Once again, we look forward to working with you. If you have any questions regarding 

the modeling results, please contact Kevin Golden of my staff at (303) 312-6442. For questions 

related to development of the BART analysis, please contact Laurel Dygowski at (303) 312­

6144. 

Sincerely, 

~~rol L. Campberr 

Stephen S. Tuber 

Assistant Regional Administrator 

Office of Partnerships and Regulatory Assistance 

Enclosure 

*Printed on Recycled Paper