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 

Ned Pettit 

Ho1cim (US), Inc. 

4070 Trident Road 

Three Forks, MT 59752 

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 Ho1cim 

(US), Inc. 

Dear Mr. Pettit: 

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 ofthe 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 Holcim (US), 

Inc. (Holcim) was BART eligible, we informed you that Ho1cim 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 ofthe 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 Ho1cim within 90 days of 

this letter, as explained below. 

In modeling Ho1cim'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 ofthis 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 detennining whether a source is subject to 

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

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

When dispersion modeling is used, part of the process of detennining 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 of 0.5 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 infonnation 

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

section lILA of the BART Guidelines. 

For Holcim, the modeling results show a maximum 98th percentile impact within a Class 

I area of 1.05 deciviews, which exceeds the threshold of 0.5 deciviews. Since Holcim exceeds 

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

visibility impainnent in one or more Class I areas, EPA Region 8 has concluded that Hokim 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 Holcim at all federal 

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

CALPUFF/CALMET files, are available on the WRAP website at 

http://pah.cert.ucr.edulagm/308/bart.shtml. 

Because Holcim is subject to BART, EPA Region 8 is requesting that Holcim conduct a 

BART engineering analysis on the emission units specified on the enclosed spreadsheet and 

submit the analysis to our office. One of the requirements of the 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 Holcim 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 of the 

technology. 

For purposes of the 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 Holcim BART engineering analysis, you will need to follow the five-step 
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accompanies the information when it is received by EPA, EPA may make the information 

available to the public without further notice to Holcim. 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, 

Carol L. Campoell 

Stephen S. Tuber 

Assistant Regional Administrator 

Office of Partnerships and Regulatory Assistance 

Enclosure 

@printed on Recycled Paper 
Summary of Calpuff Modeling Results for Holcim (US) Inc. Trident Plant 

Class I Area 

Minimum 

Distance 98th Percentile for each Year 

98th 

3 Year 

Average 

Max 

Delta-dv 

(dv) 

99th 

(dv) 

98th 

(dv) 

Days 

(km) 2001 2002 2003 > 0.5 dv

yell Yellowstone NP 100 0.33 0.55 0.55 0.48 1.91 0.67 0.52 22 

gamo Gates of the Mountains WA 101 1.05 0.55 0.70 0.77 2.77 1.01 0.61 33 

anac Anaconda - Pintler 132 0.25 0.21 0.20 0.22 0.76 0.36 0.24 8 

redr Red Rock Lakes 141 0.16 0.26 0.16 0.19 1.15 0.36 0.18 6 

scap ScapeQoat 154 0.28 0.28 0.21 0.26 1.51 0.57 0.28 11 

noab North Absaroka Wilderness 157 0.22 0.29 0.45 0.32 1.76 0.45 0.30 9 

boma Bob Marshall 189 0.28 0.25 0.12 0.22 1.38 0.41 0.24 9 

wash Washakie Wilderness 202 0.07 0.09 0.11 0.09 0.36 0.16 0.10 0 

teto Teton Wilderness 214 0.04 0.07 0.08 0.06 0.25 0.10 0.07 0 

selw Selwav-Bitterroot Wilderne ss 217 0.10 0.18 0.15 0.14 1.72 0.24 0.15 2 

mimo Mission Mountains WA 230 0.12 0.12 0.08 0.11 1.54 0.20 0.12 7 

glac Glacier NP 298 0.12 0.09 0.05 0.09 0.57 0.16 0.11 1