# BEST AVAILABLE RETROFIT TECHNOLOGY (BART) ANALYSIS

Holcim (US) Inc.

Prepared for:


## Holcim (US) Inc.

4070 Trident Road Three Forks, Montana 59752

Prepared by:



### Bison Engineering, Inc. 1400 11 th 

### Avenue Helena, MT 59601 (406) 442-5768 www.bison-eng.com

July 6, 2007HCM Air Quality Issues \BART 7/6/07 pg. ii Project #: HCM207541 

## TABLE OF CONTENTS

1.0 INTRODUC TION............................................................................................... 1-1 1.1 Summa ry ................................................................................................ 1-1 1.2 Background and Purpose ....................................................................... 1-3 1.3 Site Location and Descriptio n ................................................................. 1-4

2.0 PROCESS D ESCRIPTION ............................................................................... 2-1

3.0 EMISSIONS INVENTORY AND BAR T ANALYSIS SOURCE SELECTION...... 3-1 3.1 Initial BART Em ission Su mmary ............................................................. 3-1 3.2 SO 2 Applicable Units Emissions ............................................................ 3-3 3.3 NO X Applicable Unit s Emissi ons............................................................. 3-3 3.4 PM Applicable Un its Emissi ons ............................................................. 3-3

4.0 BEST AVAILABLE RETROFIT TECHNOLOGY REVIEW................................. 4-1 4.1 Summa ry ................................................................................................ 4-2 4.1.1 Affect ed Units ............................................................................... 4-2 4.1.2 Applicable Pollutant s.................................................................... 4-2 4.2 BART Analysi s Methodol ogy .................................................................. 4-3 4.3 SO 2 BART Analysis fo r the K iln .............................................................. 4-4 4.3.1 Step 1 – Ident ify All Available SO 2 Retrofit Control Te chnologie s ................................................................... 4-5 4.3.2 Step 2 – Eliminate Technically Infeasible SO 2 Control Options.... 4-7 4.3.3 Step 3 – Evaluate Cont rol Effectiveness of Remaining Control Te chnologie s ................................................................... 4-9 4.3.4 Step 4 – Evaluate Impacts and Document Re sults .................... 4-10 4.3.5 Step 5 – Evaluate Visibility Im pacts ........................................... 4-11 4.3.6 Select SO 2 BART ....................................................................... 4-12 4.4 NOx BART Analysis for the Kiln ........................................................... 4-12 4.4.1 Step 1 – Identify A ll Available NOx Retrofit Control Tec hnologies ................................................................. 4-13 4.4.2 Step 2 – Eliminate Te chnically Infeasible NOx Control Options .......................................................................... 4-18 4.4.3 Step 3 – Evaluate Cont rol Effectiveness of Remaining NOx Control Te chnologies ......................................................... 4-22 4.4.4 Step 4 – Evaluate Impacts and Document the Results .............. 4-22 4.4.5 Step 5 – Evaluate NO x Visibility Im pacts ................................... 4-24 4.4.6 Select NOx BART ...................................................................... 4-25 4.5 BART Analysis for PM 10 from the K iln .................................................. 4-25 4.5.1 Step 1 – Identify Available Pa rticulate Control Technologies ..... 4-25 4.5.2 Step 2 – Eliminate Techni cally Infeasible Options...................... 4-27 4.5.3 Step 3 – Evaluate Contro l Effectiveness of Remaining PM 10 Control Techno logies ........................................................ 4-27HCM Air Quality Issues \BART 7/6/07 pg. iii Project #: HCM207541 4.6 BART Analysis for PM 10 from the Clinker Cooler .................................. 4-28 4.6.1 Step 1 - Identify Available Particulate Cont rol Technologies...... 4-28 4.6.2 Step 2 – Eliminate Techni cally Infeasible Options...................... 4-29 4.6.3 Step 3 - Evaluate Contro l Effectiveness of Remaining PM 10 Control Techno logies ........................................................ 4-29 4.7 BART Analysis for PM 10 Emissions from Material Handling Syst ems................................................................................. 4-29 4.7.1 Step 1 - Identify Av ailable Particulate Cont rol Technologies...... 4-30 4.7.2 Step 2 – Eliminate Technica lly Infeasible Options...................... 4-31 4.7.3 Step 3 - Evaluate Contro l Effectiveness of Remaining PM 10 Control Techno logies ........................................................ 4-31



## LIST OF TABLES

Table 1-1: Sources Addressed by Holcim BART Analysis ....................................... 1-1 Table 1-2: Summary of BART Select ions and Visibi lity Impac ts .............................. 1-3 Table 3-1: Potential BART-E ligible Emitti ng Units .................................................... 3-2 Table 3-2: Initial EPA BART Mo deled Sources and Emissions ................................ 3-3 Table 3-3: PM 10 Sources Analyz ed for BAR T .......................................................... 3-4 Table 4-1: Summary of SO 2 Control Technology Efficien cy................................... 4-10 Table 4-2: Summary of SO 2 Cost Anal ysis ............................................................ 4-11 Table 4-3: Summary of SO 2 Visibility Im pacts........................................................ 4-12 Table 4-4: Summary of Remaining NOx Control Technology Efficiency................ 4-22 Table 4-5 Summary of NO x Cost Impac ts ............................................................ 4-24 Table 4-6: Summary of NO x Visibility Im pacts....................................................... 4-25 Table 4-7: Kiln PM/PM 10 Control Technology Effectivenes s .................................. 4-27 Table 4-8: Clinker Cooler PM/PM 10 Control Technology E ffectiveness ................. 4-29 Table 4-9: Listing of Material Transfer Emissi on Points ......................................... 4-30 Table 4-10: Material Transfer PM/PM 10 Control Technology Effectiveness ............. 4-31



## APPENDICES

Appendix A: EPA letter to Holcim of February 27, 2007 Appendix B: Visibility Impacts Modeling Appendix C : BART Cost AnalysesHCM Air Quality Issues /BART 7/6/07 pg. 1-1 Project #: HCM207541 

## 1.0 INTRODUCTION

1.1. Summary

Holcim (US) Inc. (Holcim) is submitting a Best Available Retrofit Technology (BART) analysis to the U.S. Envir onmental Protection Agency R egion VIII office (EPA). EPA submitted a letter to Holcim on February 28, 2007, regarding the preparation of a BART analysis for their cement manufacturing fa cility (Trident) located near Three Forks, Montana. The February letter notified Holcim that EPA had [through Western Regional Air Partnership (WRAP)] completed visibi lity modeling and determined that Holcim was a BART-eligible source due to the possibilit y that Holcim could cause visibility degradation in nearby Class I areas (Yellows tone National Park and Gates of the Mountains Wilderness Area). The notification requires Holcim to submit a BART analysis within 90 days of the February letter. 1 The letter also noted that if Holcim chooses not to perform an engineering analysi s, then EPA will develop the analysis instead. Holcim chose to analyze the EPA modeling results and prepare a BART engineering analysis to submit to EPA.

Holcim analyzed the existing em ission units for specific BART eligibility, and determined that there is one sulfur dioxide (SO 2 ) emission source, one nitrogen oxides (NOx) emission source and twelve particulate matte r with an aerodynamic di ameter equal to or less than 10 microns (PM 10 ) sources which must be addressed by a BART analysis. Table 1-1 lists those sources.



### Table 1-1: Sources Addresse d by Holcim BART Analysis

PTE (Ton/year) Emission Unit NO x SO 2 PM 10 BART Analysis Performed (Yes or No)

005 – Xfer-convey-screen Nil 1 Nil 1 15.89 Yes

010 – 013 Raw material silos 1-7 Nil 1 Nil 1 19.52 Yes
015 and 018 Coal and coke xfer, crush, store, (un)load & grinding Nil 1 Nil 1 33.1 Yes

021 Kiln 6,868 2 543.1 2 163.6 3 Yes

022 Clinker cooler Nil 1 Nil 1 75.09 Yes

026 Cement kiln dust silo unload Nil 1 Nil 1 16.92 Yes

032a Clinker xfer to #2 finish mill Nil 1 Nil 1 17.72 Yes

047 Cement load/unload at silos 14- 25 Nil 1 Nil 1 20.12 Yes

1 Nil means that emissions of this pollutant from this emitting unit are un-quantifiably small and deser ve no further consideration.

2 Value is from Section II.C.1.c of Permit #0982-10 (see also Page 11 of the Permit Analysis).

3 Value is from Section II.C.1.a of Permit #0982-10 (0.77 lb/ton * 425,000 tons/year * 1 lb/2,000 tons = 163.63 tons/year).

1 An extension of this deadline to June 29, 2007, was granted by an EPA lette r from Cynthia Cody on May 3, 2007. A verbal extension to July 6, 2007, was granted on June 29, 2007, by Ms. Cody.HCM Air Quality Issues /BART 7/6/07 pg. 1-2 Project #: HCM207541 Holcim determined that the kiln is t he only BART-eligible source of SO 2 . Holcim performed a BART analysis on the kiln for SO 2 , and determined that there is no add-on control or process alteration which achieves a significant visibili ty improvement that meets the definition of best av ailable retrofit technology. S ee Section 4.3 of this report for the SO 2 BART analysis.

Holcim determined that the kiln is the onl y BART-eligible source of NOx. Holcim performed a BART analysis on the kiln for NO x, and determined that there are control and process alterations that m eet the definition of best av ailable retrofit technology which can, in total, achieve a 20% reducti on in NOx and have an associated modeled 15% visibility improvement. T he selected NOx technologies wh ich will be applied to the kiln are: process alterations including a fi xed inlet on the clinker cooler and a low-NOx burner. Along with the equipment changes, Holcim selected a more stringent NOx emission limitation for the k iln of 1,254 lbs/hour in a ro lling 30-day period. This new emission limit represents a 20 % reduction in NOx emissions from the existing permit limitation of 1,568 lbs/hour in a rolling 30-day period. See Se ction 4.4 of this report for the detailed NOx BART analysis . A summary of the expect ed visibility improvement estimated by the modeling analysis is shown in Table 1-2 below.

Holcim determined that there are tw elve BART-eligible sources of PM 10 at the facility. The sources are the kiln, the clinker cooler and ten materials handl ing and processing sources. Holcim performed a BART analysis on the kiln, clin ker cooler and materials handling and processing sources for PM 10 , and determined that there are no add-on controls or process alterations that meet the definition of bes t available retrofit technology. Holcim determined that add-on controls with the highest level of PM 10 control were already installed on these ten sources. See Sectio n 4.5 for the kiln PM 10 BART analysis, Section 4.6 for the clinker cooler PM 10 BART analysis and Section 4.7 of this report for the ten mate rials handling and processing sources PM 10 BART analysis.

Table 1-2 below briefly summarizes the BART controls selected by Holcim, and the resulting visibility improvem ents modeled on the Gates of the Mountains Wilderness Area, the closest and most impacted Cla ss I area to Holcim. See Appendix B for complete modeling results.HCM Air Quality Issues /BART 7/6/07 pg. 1-3 Project #: HCM207541 

### Table 1-2: Summary of BART Se lections and Visibility Impacts

Gates of the Mountains

Pollutant Control Technology Approximate Control Efficiency Modeled Emission Rate (lb/hour) Modeled Deciviews Modeled Deciview Improvement (above baseline) % Improvement

in Visibility (from baseline)

SO 2 No Additional Controls 0% 340 1.56 0.00 0%

Process Alterations (including installation of

fixed inlet on clinker cooler) 3% 1,521 1.49 0.04 3%

Low-NOx Burner 17% 1,301 1.32 0.21 13% NOx

Total NOx Improvement: 20% 1,254 1.28 0.24 15%

PM 10 No Additional Controls 0% 23 1.56 0.00 0%

The remainder of this report details all of the BART steps and analyses performed for the Holcim Trident facility.



### 1.2. Background and Purpose

Congress amended the Federal Cl ean Air Act in 1977 to incl ude a new Section 169A and 169B for the purpose of protecting visibi lity in certain scenic areas. The areas afforded this visibility protection are ident ified as “Mandatory Class I Federal Areas.” 2 The rules EPA promulgated to implement these actions of the Act are generally found in 40 CFR 51, Subpart P.

Specific to this doc ument, EPA promulgated 40 CFR 51.308(e) which requires certain types of existing stationary sources to instal l best available retrof it technology (BART). The term BART is defined in §301 as follows:

Best Available Retrofit Tec hnology (BART) means an emission limitation based on the degree of reduction achievable through the application of the best system of continuous emission reduction for each pollutant which is emitted by an existing stationary facility. The emission limitation must be estab lished, on a case-by-case basis, taking into consideration the tec hnology available, the costs of compliance, the energy and nonair qua lity environmental impacts of compliance, any pollution control equipm ent in use or in existence at the source, the remaining useful lif e of the source, and the degree of

2 These areas are identified in 40 CFR 81.401 et seq . Those areas within Montana and Wyoming are found in §417 and §436, respectively.HCM Air Quality Issues /BART 7/6/07 pg. 1-4 Project #: HCM207541 improvement in visibility which may reasonably be anticipated to result from the use of such technology

. As noted in Section 1.1 above, EPA has identifi ed the Holcim Trident plant as a ‘existing stationary source’ 3 which is subject to the BART requirements. EPA has further identified guidelines for ident ifying BART-eligible sources and suggested methodologies to be employed for conducting a BART analysi s. These guidelines are codified in 40 CFR 51, Appendix Y.

It is the purpose of this document to fulf ill the requirements for conducting a BART analysis for the Holcim Tri dent facility. The remainder of this document conducts a BART analysis for each unit and pollutant subject to the regulation [40 CFR 51.308(3)]. The methodologies and guidelines found in 40 CFR 51, Appendix Y were used to develop this BART document.



### 1.3. Site Location and Description

The Holcim Trident facility (Trident) is appr oximately five miles northeast of Three Forks, near the headwaters of the Missouri River. The plant site is located in Section 9, Township 2 North, Range 2 Ea st in Gallatin County, M ontana, with appr oximate UTM coordinates of the facilit y of Zone 12, Easting 464 km , and Northing 5,088 km. The elevation is approximately 4,200 feet above sea level. Maps of the Holcim facility are on file with the Mont ana Department of Envi ronmental Quality (MDEQ ). Site description information is also on file with MDEQ. C opies of the maps and descriptions are available upon request.

3 As defined in 40 CFR 51.301.HCM Air Quality Issues /BART 7/6/07 pg. 2-1 Project #: HCM207541 

## 2.0 PROCESS DESCRIPTION

The production of Portland cem ent begins at the quarry. Most of the raw material used in the cement process is combined high and low-grade lime stone quarried from Holcim’s quarry. Limestone rock and other ra w materials are blasted and loaded onto trucks and transported to the cr usher or to stockpiles.

The raw materials are conveyed from the pr imary crusher to the storage bins. From the storage bins, the raw materials are conveyed to the ball mill where they are ground with water to form slurry, which is then sent to storage tanks. In the tanks, the slurry is blended thoroughly before entering the kiln.

The slurry is pumped to the uphill end of t he kiln where it is heated. The water (H 2 O) evaporates from the slurry and natural minera ls from the raw materials recombine to form clinker in the kiln. The plant uses a combination of natural gas, coal and/or petroleum coke as fuel sources for the clinker production.

When the clinker leaves the kiln, it is cooled , then transported to the finish mill feed bins or other storage. From the fi nish mill feed bins, clinker, gypsum, and other additives are transported to the “finish” ball mills, where it is ground to produc e Portland cement. The final cement product is conveyed to storage silos where it is loaded into railroad cars or bulk trucks.HCM Air Quality Issues /BART 7/6/07 pg. 3-1 Project #: HCM207541 

## 3.0 EMISSIONS INVENTORY AND BART ANALYSIS SOURCE SELECTION

3.1 Initial BART Emission Summary

In a series of letters MDEQ requested that Holcim submit a list of the BART-eligible sources at the Trident facility and supply sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), and particulate matter less than 10 microns (PM 10 ) emission data for the BART-eligible sources. Holcim concluded 29 emitting units (a s provided in the Title V permit) from the Trident facility qualify as BART-eligible. The emission data requested was for annual potential to emit (PTE) and the highest 24 -hour emission rates occurring during the three year period of 2001, 20 02, and 2003. An nual emissions were based on the permitted limits in Holcim’s Operating Permit #0982-10. The highest 24-hour NO x and SO 2 emissions for the cement kiln were det ermined from continuous emissions monitor (CEM) data collected during the specified 3 y ears. It should be noted that the highest 24-hour SO 2 emission rate of 340 pounds per hour (lb/hr) is significantly greater than the permitted 30-day rolling average SO 2 emission rate of 124 lb/hr. However, the facility did not exceed it s permitted emission rate.

Table 3-1 below lists the original 29 BART-eligible emitting units and their corresponding emission rates. Table 3-1 al so shows the 12 emission units selected for BART analysis due to their significant emission rates.HCM Air Quality Issues /BART 7/6/07 pg. 3-2 Project #: HCM207541 

### Table 3-1: Potential Bart-Eligible Emitting Units

PTE (Ton/year)

Emission Unit NO x SO 2 PM 10 Eligible for Detailed BART Analysis (Yes or No)
005 – Xfer-convey-screen Nil 1 Nil 1 15.89 Yes
008/009 – Primary crusher/screen Nil 1 Nil 1 10.96 No 4

010 – 013 Raw material silos 1-7 Nil 1 Nil 1 19.52 Yes

014 Coal/coke unload Nil 1 Nil 1 7.88 No 4

015 and 018 Coal and coke xfer, crush, store, (un)load & grinding Nil 1 Nil 1 33.1 Yes

016 Coal outside storage pile Nil 1 Nil 1 0.28 No 4

017 Coke outside storage piles Nil 1 Nil 1 0.28 No 4

019 Coal silo loading and unloading Nil 1 Nil 1 3.00 No 4

020 Coke silo loading and unloading Nil 1 Nil 1 1.13 No 4

021 Kiln 6,868 2 543.1 2 163.6 3 Yes

022 Clinker cooler Nil 1 Nil 1 75.09 Yes

023 Inside clinker xfer from cooler Nil 1 Nil 1 5.26 No 4

025 Cement kiln dust silo load Nil 1 Nil 1 2.25 No 4

026 Cement kiln dust silo unload Nil 1 Nil 1 16.92 Yes

027 Emergency clinker bins loading Nil 1 Nil 1 4.13 No 4

028-031 Emergency clinker storage silos 1-4 Nil 1 Nil 1 0.09 No 4

032a Clinker xfer to #2 finish mill Nil 1 Nil 1 17.72 Yes

047 Cement load/unload at silos 14-25 Nil 1 Nil 1 20.12 Yes

049-050 Bulk cement railcar xfer loadouts 1 & 2 Nil 1 Nil 1 1.80 No 4

051 Bulk cement rail xfer loadout Nil 1 Nil 1 0.00 No 4

1 Nil means that emissions of this pollutant from this emitting unit are un-quantifiably small and deser ve no further consideration.

2 Value is from Section II.C.1.c of Permit #0982-10 (see also Page 11 of the Permit Analysis).

3 Value is from Section II.C.1.a of Permit #0982-10 (0.77 lb/ton * 425,000 tons/year * 1 lb/2,000 tons = 163.63 tons/year).

4 Under 40 CFR 51 Appendix Y, EPA establishes de minimis levels of emissions under whic h a source is not BART-eligible.HCM Air Quality Issues /BART 7/6/07 pg. 3-3 Project #: HCM207541 For purposes of BART applicability determi nation only, EPA modeled emitting units #21 and #22, the kiln and the clinker cooler, respectively. Table 3-2 summarizes the SO 2 and NO X emissions and PM 10 speciated emissions for the two sources EPA modeled (via the University of California Riverside) in the initial BART applicability determination.



### Table 3-2: Initial EPA BART Modeled Sources and Emissions

Total Emission Rate a (lbs/hr)
Emitting Unit SO 2 SO 4 NO x HNO 3 NO 3 SOA b EC b PMC b PMF b

Kiln 340 7.215 784 - - 0.01 0.01 0.093 9.31 Clinker Cooler 0.01 0.01 0.01 - - 0.01 0.01 0.137 13.7

a Emissions obtained from documents on WRAP Regional Modeling Center website http://pah.cert.ucr.edu/aqm/308/bart.shtml.

b The abbreviations are as follows: SOA = Sulfur-Oxidizing Activity, EC = Elemental Carbon, PMC = Condensable Particulate Matter, and PMF = Filterable Particulate Matter.

Although EPA only modeled the two source s above, Holcim’s analysis was conducted for all potential BART-eligible sour ces identified in Table 3-1 above



### 3.2 SO 2 

### Applicable Units Emissions

The kiln is the only SO 2 emitting unit subject to BART analysis. The PTE (federally enforceable permit limit) for SO 2 from the kiln is 124 lbs/ hr on a rolling 30-day average (543 tons/yr). To remain consistent wit h the BART modeling analysis performed by EPA, Holcim has performed the BART analysis with the highest 24-hour SO 2 emission rate of 340 lbs/hr as recorded by Holcim’s CEM during the 3-year period of 2001-2003.



### 3.3 NO
x 

### Applicable Units Emissions

The kiln is also the only NO x emitting unit subject to BART analysis. The PTE (federally enforceable permit limit) for NO X from the kiln is 1,568 lbs/ hr on a rolling 30-day average (6,868 tons/yr). The BART modeling analysis performed for Holcim used the permitted NO x PTE to establish the baseline visibi lity impacts used in this analysis.



### 3.4 PM Applicable Units Emissions

As listed in Table 3-1, there are a total of 12 emission sources of PM 10 to be analyzed for BART comprising a total of 362 tons/yr of PM 10 . The largest (potential) emitters of PM 10 are the kiln (164 tons/yr) and the clin ker cooler (75 tons/yr) which compose approximately 66% of the total PM 10 emissions.

Table 3-3 provides a summary of the 12 emi tting units subject to further BART analysis. The table also shows the current emissions control associated with those units.HCM Air Quality Issues /BART 7/6/07 pg. 3-4 Project #: HCM207541 

### Table 3-3: PM 10 

### Sources Analyzed for BART

Source Current Source Control 005 – Xfer-convey-screen Baghouse 010 – 013 Raw material silos 1-7 Baghouse 015 and 018 Coal and coke xfer, crush, store, (un)load & grinding Baghouse

021 Kiln Electrostatic Precipitator 022 Clinker cooler Baghouse 026 Cement kiln dust silo unload Dustless Unloader and Baghouse 032a Clinker xfer to #2 finish mill Baghouse 047 Cement load/unload at silos 14-25 BaghouseHCM Air Quality Issues /BART 7/6/07 pg. 4-1 Project #: HCM207541 

## 4.0 BEST AVAILABLE RETROFIT TECHNOLOGY REVIEW

The Clean Air Act (CAA), in section 169(a)(2), requires that State Implementation Plans (SIPs) for visibility protection must apply BART to certain large-emitting sources. BART is required for s ources that meet all of the following criteria:

1. The source is in one of 26 s pecific listed source categories; 4

2. The source was in existence as of August 1977, but was not in operation in August of 1962; 5

3. The facility has the potent ial to emit 250 tons per year of any visibility-impairing pollutant; and

4. The BART-eligible source emits an air pollutant that “may reasonably be anticipated to cause or contribute to any impairment of visibilit y in any mandatory Class I federal area, . . .” 6

The term Best Available Retrof it Technology (BART ) is defined in 40 CFR 51.301 and

means:

“an emission limitation based on t he degree of reduction achievable through the application of the best system of continuous emission reduction for each pollutant which is emitted by an existing stationary facility. The emission limitation mu st be established, on a case-by-case basis, taking into consideration the te chnology available, the costs of compliance, the energy and nonair qua lity environmental impacts of compliance, any pollution control equipment in use or in existence 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 such technology.”

Appendix Y further explains how to identify sources subject to BART:

“Once you have determined that your s ource or sources are subject to BART, you must conduct a visibility improvement determination for the source(s) as part of the BART determination. When making this determination, we believe you have flexibility in setting absolute thresholds, target levels of improvement, or de minimis levels since the deciview improvement must be weighed among the five factors, and you are free to determine the weight and significance to be assigned to each factor.”

4 The 26 source categories are found in the definition of “Existin g stationary facility” found in 40 CFR 51.301.

5 The terms “in existence” and “in operation” are defined in 40 CFR 51.301.

6 40 CFR 51.308(e).HCM Air Quality Issues /BART 7/6/07 pg. 4-2 Project #: HCM207541 

### 4.1 Summary

The CAA, in section 169(a)(2) requires that SIPs for visi bility protection must apply BART to certain large-emitting sources. EPA identified Holcim as a possible BARTeligible source because it is a Portland cement plant, which is one of the 26 BART source categories under 40 CFR Part 51.301 under the definition of “E xisting stationary source.” The Holcim facility has emitting units that meet the time frames specified in item 2 above. In addition, the entire complex has a potential to emit greater than 250 tons per year.

EPA has completed initial visibility modelin g through the WRAP program. As a result of those investigations EPA has determined that Holcim is subject to a BART analysis in accordance with the BART prov isions of 40 CFR 51.308. The EPA documentation of this requirement and conclusion is foun d in a letter from EPA Region VIII dated February 27, 2007, addressed to Mr. Ned Petti t of Holcim. A copy of that letter and conclusion is found in Appendi x A of this document.

In accordance with the February 27, 2007 letter, Holcim has conducted a BART analysis using EPA-recommended methodol ogies and dispersion modeling recommendations found in 40 CFR 51, Appendi x Y, more specifically the CALPUFF dispersion model, to assist with the proposed BART determination. The purpose of the modeling analysis is to determine the visibi lity improvement expected at Class I areas from the potential BART control technol ogy applied to the source. The modeling analysis is found in Appendix B of this document.

4.1.1 Affected Units

There are a total of 29 emitting units at the Holcim facility that have been identified as potentially “BART–eligible.” These units have received that designation since they meet the definition of BART-eligible since they were “in existence” 7 as of August 1977, but not “in operation” 8 in August of 1962 and havin g (collectively) the potential to emit 250 tons per year of an air pollutant that could cause visibility degradation in a Class I area (applicable pollutants are listed in Section 4.1.2 below). See Table 3-1 for a list of potential BART-eligible emitting units.

Of the units subject to a BART engineering analysis, the kiln and clinker cooler comprise the majority of inte rest for BART purposes. The ot her ten units which are also subject to a BART engineering analysis are those units shown in Table 3-3 above.

4.1.2 Applicable Pollutants

The visibility impairing pollutants analyzed in this BART analysis are:

7 As defined by 40 CFR 51.301

8 Ibid.HCM Air Quality Issues /BART 7/6/07 pg. 4-3 Project #: HCM207541 y Sulfur dioxide (SO 2 ),

y Nitrogen oxides (NO x ), and

y Particulate matter less than 10 microns (PM 10 ).

PM 10 is used as an indicator for particu late matter. As emissions of PM 10 include the components of PM 2.5 as a subset, there is no need to have separate 250 ton thresholds for PM 10 and PM 2.5 ; 250 tons of PM 10 represents at most 250 tons of PM 2.5 , and at most 250 tons of any individual particulate sp ecies such as elemental carbon, crustal material, etc.



### 4.2 BART Analysis Methodology

In general terms, EPA has identified a metho dology for conducting a BART analysis that is similar to the Best Available Contro l Technology analyses co nducted under the PSD permitting program (40 CFR 51.166 and elsew here). For BART, the methodology is more refined to include pollutants related to visibility impairment and to include an analysis of the impacts the proposed technol ogy has on the visibility directly.

The BART methodology is a case-by-case procedure. The BART methodology chosen for this analysis follows the guidelines est ablished by EPA in 40 CFR 51, Appendix Y. Hereafter, these guidelines wi ll be referred to as either the “Appendix Y Guideline” or simply “Appendix Y.” Appendix Y suggests that the case-b y-case BART analysis should follow the five steps below (S ection IV.D of Appendix Y).

Case-by-Case Five Step BART Analysis:

Step 1 - Identify all 9 available retrofit control technologies; Step 2 - Eliminate techni cally infeasible options; Step 3 - Evaluate control effectiveness of remaining control technologies; Step 4 - Evaluate impacts and document the results; and Step 5 - Evaluate visibility impacts.

The following paragraphs will evaluate BART for each source or source group emitting any of the pollutants noted above as being re leased in significan t quantities. BART for NO x and SO 2 emissions from the kiln, essentiall y the only source of these compounds, will be addressed first. BART for the various s ources of particulate emissions will be addressed at the end of this section.

As suggested by Appe ndix Y, Holcim reviewed the Ne w Source Performance Standards (NSPS) Subpart K for cement kilns to determine if any control technologies or emission restrictions were applicable to new facilities. This review showed that NSPS for cement kilns applies only to particula te emissions and opacity.

9 Appendix Y notes that the term “all” refers to iden tifying the most stringent option and a reasonable set of options for analysis that reflect a comprehensiv e list of options. It is not necessary (according to Appendix Y) to list all permutations of avail able control levels for a given technology.HCM Air Quality Issues /BART 7/6/07 pg. 4-4 Project #: HCM207541 To facilitate the following BART determinat ions, Holcim queried the EPA RACT-BACTLAER Clearinghouse (RBLC) database for listi ngs of pollutant em ission limits and required control technologies at other ce ment manufacturing facilities across the country. The information generated by these quer ies serves as a helpful guideline to indicate expected emission rate ranges and control technologies that may have been successfully applied at facilities similar to the Holcim cement plant. When reviewing specific emission limits applied at other kilns, it is import ant to recognize that cement manufacturing operations and their associat ed emissions characteristics can vary significantly from one facility to another, and ev en within a single fac ility. Some of the inherent differences will be addressed in succeeding pa ragraphs. Further, the database is not always well maintained and includes some outdated information. In some cases, for instance, an owner may have accepted a stringent emission limit or an unproven control technology only to find the limit or the technology was inappropriate for the particular operation, leading to a permit change that may not be reflected in the database.

Another factor that must be kept in mind when compar ing emission limits across facilities is that the averaging period associ ated with the limit signi ficantly affects the source’s ability to comply. A source may be able to comply with a particular emission limit over a rolling 30-day averaging period for example, but find it impossible to consistently comply with the same limit applied to a one-hour averaging period.

In following the five-step BART analysis, Holcim initially reviewed all available retrofit technologies, and then condensed this list to only include those te chnologies that are applicable to a long wet kiln. For example, technologies may be only available for dry or preheater/precalciner kilns, but are not appropriate to consider for a long wet kiln, such as the Trident plant.



### 4.3 SO 2 

### BART Analysis for the Kiln

SO 2 forms during coal combustion as sulfur in the coal is lib erated and subsequently oxidized by the oxygen present in the combus tion air. Sulfur in the feed limestone can also contribute signific antly to the kiln’s SO 2 emissions. SO 2 emissions can be reduced by capturing and converting it once it has formed. It is possible to limit SO 2 formation both by limiting the amount of sulfur fed to the kiln system and by controlling the conditions necessary to oxidize su lfur. Capture and c onversion of SO 2 in the exhaust stream through add-on controls is generally accomplished by mixing the exhaust gas stream with an alkaline reagent, facilitat ing the chemical conversion of SO 2 to a neutral salt. The salt is solid at system conditi ons and can be removed by physical means. The control equipment that accomplishes this is commonly referred to as a gas scrubber. Cement kiln systems inherently act as large gas scrubbers with varying degrees of effectiveness depending, in part, on the excess alka li (e.g., Na and/or K) or alkali earth (e.g., Ca) compounds available to co mbine with sulfur to remove SO 2 as described. Holcim’s Trident plant has an excess of alka li compounds to sulfur input indicating a capacity to absorb much more sulfur in its kiln system.HCM Air Quality Issues /BART 7/6/07 pg. 4-5 Project #: HCM207541 4.3.1 Identify All Available SO 2 Retrofit Control Technologies – Step 1

In accordance with Step 1 described in Secti on 4.2 above, Holcim has sought to identify all “available” retrofit technologies. To that end, EPA’s RBLC describes several permitted cement kiln installations and lists t heir pollutant emission limits and the control technologies approved to achiev e those limits. Another sour ce of information regarding potentially applicable SO 2 control technology for cement kilns is EPA’s AP-42 for Portland cement manufacturing (Chapter 11, Section 6). T he following were identified as potentially applicable for controlling SO 2 from cement manufacturing:

(i) Proper kiln design and operation (baseline); (ii) Process alterations; (iii) Hot meal injection; (iv) Spray dryer absorber; (v) Wet SO 2 scrubber.

Control Technology Description:

(i) Proper Kiln Design and Operation Sulfur is present in coal and limestone as organic sulfur compounds and as minerals pyrite or iron sulfide. In these forms it is readily volatilized and then oxidized to SO 2 under calcining conditions. Sulfur may al so be homogeneously pres ent in limestone as calcium sulfate. This form of sulfur does not normally volatilize at calcining temperatures and tends to remain in the lime. In fac t, lime reacts under dry conditions with SO 2 to form calcium sulfate (CaSO 4 ) as follows: 10

) sulfate calcium ( 2 1 ) lime ( 4 2 2 CaSO O SO CaO ↔ + +

Similar reactions with sodium and potassium also reduce SO 2 in the kiln. All three of these elements are in excess supply in Triden t raw materials, available for reaction. To the degree thermodynamic an d kinetic factors allow the reverse reaction (i.e., conversion of sulfate to lim e), a lack of oxygen, or a r educing atmosphere, will favor a desulfurization of the limestone. Converse ly, increasing oxygen will cause the equilibrium to shift toward increased formation of sulfate. This is where a balance must be struck between product quality and emissions of SO 2 . If specifications call for low levels of sulfur, and especially if the limestone feed contains relatively high proportions of sulfur, kiln conditions must be established that inhibit SO 2 absorption within the kiln. Neither is the case for Holcim’s Trident Plan t. If such is not the case, it may be possible to operate the kiln under conditions that favor sulfur oxidation.

(ii) Process Alterations The process alteration that Holcim evaluated was changing their fuel to a low sulfur fuel in order to reduce their sulfur emissions. In many cases, the fuel used to fire the kiln is the primary source of su lfur, and ultimately, of SO 2 . One method to “control” SO 2

10 “Chemistry and Technology of Lime and Limesto ne,” Second Edition, 1980, R.S. Boynton, pg. 181.HCM Air Quality Issues /BART 7/6/07 pg. 4-6 Project #: HCM207541 emissions is to “control” the sulfur in the native fuel. For example, natural gas contains very little sulfur. Coal may vary from 0.7% to over 5% sulfur. Petroleum coke typically contains 3% to 6% sulfur.

(iii) Hot Meal Injection Another possibility is the hot-m eal bypass in a preheater/preca lciner kiln system, where calcined hot meal is, in part, discharged in front of the kiln entrance after the precalcining process. The ty pe of hot meal produced varies by facility. Different hot meal materials have different therma l content and pollutant emissions.

(iv) Spray Dryer Absorber The term Spray Dryer Absorber (SDA) here refers to those technologies that use a dry, semi-dry or semi-wet alkaline material to control SO 2 emissions from the postcombustion gases. While there are a number of injection methods and designs, it is generally understood that an SDA provides a high degree of controls ( within this group) and represents a fair characterization of this class of control device.

A spray dryer absorber is an SO 2 scrubbing process that in volves both acid gas and particulate matter control. In a typica l SDA system, hot combustion gases enter a reactor where atomized hydrated lime slurry (o r near slurry) is introduced at a controlled velocity. Upon injection, the water in the li me slurry quickly evaporates which cools the flue gas. The acid gas constituents (primarily SO 2 ) quickly react with the reagent (CaOH, etc.). The result is a dried product that is removed from the exhaust stream by a particulate control device. In general, SD As are used in combination with either electrostatic precipitators or fabric filter baghouses.

(v) Wet SO 2 Scrubber A wet SO 2 scrubber is one that uses an aqueous chemical system. These systems have been successfully employed in various industries to remove SO 2 from concentrated waste streams. These systems use aqueous solutions or slurries as the contact and reaction media. A typical installation uses spray tower scrubbers to introduce a reagent slurry as atomized droplets through the spray nozzles at the top of, or in stages within, the scrubber. The SO 2 -laden gas enters at the botto m of the column and travels upward through the tower in a countercurr ent flow, though horizontal spray towers which use a crosscurrent design also exist. In most cases the sorbent is an alkaline slurry, commonly limestone, slaked lime, or a mixture of slaked lime and alkaline fly ash, though many other sorbent proce sses exist. Absorption of SO 2 is accomplished by the contact between the gas and the reagent slurry. The sulfur oxides react with the sorbent, forming a wet mixture of calcium sulfite and sulfate.

The slurry combines with the SO 2 -laden waste gas to form a waste slurry in the bottom of the scrubber. The sludge is removed from the scrubber and, depending upon the reagent or sorbent used to react with the SO 2 , the waste reacted sludge is disposed of, recycled or regenerated, or, in some case s, sold as a salable product.HCM Air Quality Issues /BART 7/6/07 pg. 4-7 Project #: HCM207541 4.3.2 Eliminate Technically Infeasible SO 2 Control Options – Step 2

The following discusses the feasibility or inf easibility of each technology identified in Section 4.3.1 above. The decision regardi ng whether a particular technology was deemed “technically feasible” was based on discussions found in 40 CFR 51, Appendix Y. Appendix Y describes guidelines for BA RT determinations under the regional haze rule. Hereafter, the document will be refe rred to as the “Appendix Y Guideline.”

The issue of feasibility is found in Section IV.2.STEP 2 of the Appendix Y Guideline. The guideline states that control technolog ies are technically feasible if either:

“(1) they have been installed and operated successfully for the type of source under review under similar conditions, or

(2) the technology could be applied to the source under review.”

The Appendix Y Guideline goes on to descri be these circumstances further and discuss the meaning of “available” and “applicability” within the meaning of BART. As a general rule, “available” means that the owner of the facility may obtain the technology through commercial channels. In the alternative, the technology is “available” within the common-sense meaning of that term.

Commercially available is further discuss ed in the Appendix Y Guideline as having attained either stage (5) or (6) of the following stages of bringing a control technology to reality as a commercial product:

(1) Concept stage; (2) Research and patenting; (3) Bench scale or laboratory testing; (4) Pilot scale testing; (5) Licensing and commercial demonstration; and (6) Commercial sales. Also of note in the Appendix Y Guid eline is the following statement:

Similarly, we do not expect a source owner to conduct extended trials to learn how to apply a technology on a totally new and dissimilar source type. Consequently, you would not consider technologies in the pilot scale testing stages of development as “available” for purposes of BART review.

The reader is referred to further discussion in the Appendix Y Guideline on this matter.

Using the Appendix Y Guidelin es above, infeasible tec hnologies are rejected where appropriate. Those technologies deemed infeas ible are no longer discussed in further sections of this BART analysis.HCM Air Quality Issues /BART 7/6/07 pg. 4-8 Project #: HCM207541 (i) Proper Kiln Design and Operation Proper design and operation of kilns is clearly feasible and serves as the baseline case.

Conclusion: Proper kiln des ign and operation is considered feasible for purposes of Step 2 in this BART analysis.

(ii) Process Alterations Holcim has identified fuel se lection as a process altera tion which can possibly reduce SO 2 emissions. Fuel selection as a means to “control” SO 2 emissions is technically feasible. However, Holcim believes that the kiln currently has excess capacity for SO 2 absorption due to the alkali natur e of the kiln interior. Ther efore, Holcim believes that switching fuels will no t significantly reduce SO 2 emissions because the kiln will remain an effective SO 2 scrubber regardless of fuel type used.

Appendix Y Guideline ex plicitly addresses this issue. Specifically, STEP 1: How do I identify all available retrofit emission control techniques? of the guideline contains the following statement:

“...........note that it is not our int ent to direct States to switch fuel forms, e.g. from coal to gas.”

Given this statement, it is clear that it is not the intent of EPA to use fuel switching as a form of BART control.

Conclusion: This process alteration is c onsidered infeasible for purposes of Step 2 in this BART analysis. No further discu ssion of this technology will be presented.

(iii) Hot Meal Injection As previously stated, hot meal is produced in a preheater/pre calciner kiln. Holcim does not have a preheater/precalciner kiln design from which hot meal can be obtained; therefore, this is not a f easible option for Holcim.

Conclusion: This technology is considered infeasible for purposes of Step 2 in this BART analysis. No further discussion of this technology will be presented.

(iv) Spray Dryer Absorber This type of technology is not considered to be effective for large sources with relatively dilute SO 2 concentrations. The kiln and baghouse system acts as a large dry scrubber mixing gaseous SO 2 with active lime and alkali surfac es to create and capture sulfate salts. Adding a separate spray dry scrubber would only provide additional lime with which SO 2 can react. Supplemental scrubbing by an SDA is expected to provide no more than inefficient redundancy. The perfo rmance of a lime sp ray dry scrubber is sensitive to operating conditions. A “close approach” to adiab atic saturation temperature is required to maximize the removal of SO 2 . However, excess moisture causes the wetHCM Air Quality Issues /BART 7/6/07 pg. 4-9 Project #: HCM207541 solids to deposit on the absorber and downst ream equipment. In spray dry systems, the flue gas must be cooled to a temperat ure range of 10°C to 15°C (20°F to 35°F) below saturation temperature. This temper ature range avoids wet solids deposition and plugging on the downstream particulate control device. An evaporative cooler, or a heat exchanger is typically used to cool the gas, as flue gas with high temperature reduces the performance of the scrubber.

The SDA must be designed in conjunction with the particulate control device as a system. Therefore, to retrof it the existing process wit h an ESP will likely involve substantial modifications to the ESP.

Conclusion: Although there are serious conc erns with this technology, it will be presumed that it remains technically feasible for purposes of Step 2 in this BART analysis.

(v) Wet SO 2 Scrubber This type of technology is not considered to be effective for large sources with relatively dilute SO 2 concentrations. The kiln and baghouse system acts as a large dry scrubber mixing gaseous SO 2 with active lime and alkali surfac es to create and capture sulfate salts. Adding a separate wet scrubber would onl y provide additional alkali solution with which SO 2 can react. Adding a wet scrubber is expected to provide no more than inefficient redundancy. Scrubbing effectiveness is not linearly related to additional removal media concentration. At some optimal lime concentration, a point of diminishing returns is reached after which incremental effe ctiveness rapidly decreases. This effect is hastened by decreasing SO 2 concentrations. The kiln system is expected to inherently provide excess desulfurization media. Ad ding further excess with a supplemental scrubber cannot be expected to appreciably increase control efficiency. Aqueous chemical absorption cannot be considered appl icable to the proposed project but is technically feasible.

Conclusion: Although there are serious conc erns with this technology, it will be presumed that it remains technically feasible for purposes of Step 2 in this BART analysis.

4.3.3 Evaluate Control Effectiveness of Rema ining Control Technologies – Step 3

Of the alternative SO 2 control technologies identified above, proper kiln design and operation, SDA, and wet SO 2 scrubbers remain as technically feasible options. Proper kiln design and operation is t he baseline case for this analysis. Other control methods will be evaluated for their potential to impr ove upon this basis. Table 4-1 summarizes the control effectiveness of the remaining control technologies.HCM Air Quality Issues /BART 7/6/07 pg. 4-10 Project #: HCM207541 

### Table 4-1: Summary of SO 2 

### Control Technology Efficiency

Control Option Efficiency (%) SO 2 Emissions

(lbs/hr) SO 2 Emissions (tpy) Tons Removed

Wet SO 2 Scrubber 95% 6.20 27 516 Spray Dry Absorber 90% 12.40 54 489
Baseline 0% 124 543 0

4.3.4 Evaluate Impacts and Document Results – Step 4

(a) Spray Dry Absorbers Impacts

Spray Dry Absorbers Economic Impacts

Holcim has calculated the cost-effec tiveness for employing an SDA for SO 2 control, with the results presented in Table 4-2 below. Ho lcim has utilized the EPA’s Air Pollution Cost Control Manual to estimate costs of SD A control. The manual provides the EPA’s recommended methodology for estimating the co sts for add-on control technology. To calculate the cost-effectiveness of a contro l technology in dollars per ton ($/ton), the following factors are used:

Cost-effectiveness ($/ton) = [(total capital investment x capital recovery factor {CRF}) + Direct Annual Cost + Indirect Annual Cost]/(tons SO 2 controlled)

Capital Recovery Cost (= total capital investment x CRF)

• Total capital investment = direct and indirect costs for purchasing and installing control equipment.

• Capital recovery factor (CRF) = mult iplier to determine the uniform end-ofyear payment necessary to repay an investment in n years with an interest rate of i.

o Control system life, n = 10 to 20 years, typically

o Interest rate, I = 7% recommended interest rate For this BART analysis, CRF = 10 years @ 7% = 0.142 Direct Annual Cost (utilities, labor, taxes) Indirect Annual Cost (overhead, insurance, taxes)

Table 4-2 summarizes the cost-effectiveness for each of the technically feasible control options, compared against a base line of proper kiln design and operatio n. Details of the SDA cost analysis can be found in Appendix C.

Spray Dry Absorbers Energy Impacts

EPA Publication EPA-542/F-03- 034 states that modern sp ray dry absorber designs result in an energy penalty of less than 1% of the total plant energy consumption. This is a minor energy impact which is considered in the economic analysis.HCM Air Quality Issues /BART 7/6/07 pg. 4-11 Project #: HCM207541 (c) Wet SO 2 Scrubber Impacts

Wet SO 2 Scrubber Economic Impacts

Holcim has calculated the cost-effectiv eness for employing a wet scrubber for SO 2 control, with the results presented in Tabl e 4-2 below. The table summarizes the costeffectiveness for each of the technically feas ible control options, compared against a baseline of proper kiln desig n and operation. De tails of the wet scrubber cost analysis can be found in Appendix C.

Wet SO 2 Scrubber Energy Impacts

EPA Publication EPA-542/F-03-034 st ates that modern wet scrubber designs result in an energy penalty of less than 1% of the total pl ant energy consumption. This is a minor energy impact which is only further c onsidered in the economic analysis.

Alternatives Analysis Summary

For the purposes of this cost analysis, it has been assumed that the remaining life of all of the equipment is at least the 10 y ears used to calculate the annualized costs.



### Table 4-2: Summary of SO 2 

### Cost Analysis

As shown in Table 4.2, the cost per ton for the wet SO 2 scrubber and the SDA are substantial, both higher t han what is generally consi dered BACT in Montana. The annualized costs of both options are cost-prohibitive. In additi on, the incremental cost of $498,491 per ton SO 2 removed by the wet scrubber versus the SDA is enormous.

4.3.5 Evaluate Visibility Impacts – Step 5

Holcim has performed modeling using the CALPUFF model to predict visibility impacts of the identified pot entially applicable SO 2 control technologies, using the 98 th percentile visibility result as recommended by EPA. T he results of the modeling are shown in Table 4-3 below. The results are only pr esented for the Gates of the Mountains Wilderness Area, as it is the closer, and more impacted Class I Area. Details of the modeling are found in Appen dix B to this document. Control Option Annualized Cost Efficiency (%) SO 2 Emissions

(lbs/hr) SO 2 Emissions (tpy) Tons SO 2 Removed Cost Effectiveness ($/ton) Incremental Cost Effectiveness ($/ton)
Wet SO 2 Scrubber $19,607,665 95% 6.20 27 516 $38,011 $498,491 Spray Dry Absorber (includes baghouse) $6,070,650 90% 12.40 54 489 $12,422 --
Baseline $0 0% 124.00 543 0 -- --HCM Air Quality Issues /BART 7/6/07 pg. 4-12 Project #: HCM207541 

### Table 4-3: Summary of SO 2 

### Visibility Impacts a

Gates of the Mountai ns Wilderness Area

Control Option Annualized Cost Efficiency (%) SO 2 (lbs/hr) Visibility Impact (deciview) Visibility Improvement

(deciviews 24 hr) Cost ($/deciview) Incremental Cost ($/deciview)

Wet SO 2 Scrubber $19,607,665 95% 6.20 1. 291 0.269 $15,185,614 $2,990,183,225

Spray Dry Absorber (includes baghouse) $6,070,650 90% 12.40 1.296 0.264 $4,683,421 --
Baseline $0 0% 124 1.56 0.000 -- --

a Deciviews at each % reduction for the Gates of the Mountains are calculat ed using the equation: y = 0.001x + 1.2862 derived from using the best fit tr endline of the average 98th percentile modeling values.

4.3.6 Select SO 2 BART

Based upon the modeling results, the addition of add-on controls , in practice, will result in minimal visibility improv ement. The 340 lbs/hr of SO 2 utilized in t he models as a worst-case 24-hour value is approximately ten times higher than normal levels of SO 2 emissions. Even when using this larger fi gure in the models, the deciview change accomplished by employing the best contro l technology (wet scrubber) at 95% control has only a 0.269 deciview impact on visibility. Holcim believes this change is well below the human eye’s ability to detect.

The costs of the add-on controls are deemed to be unjustifiable in terms of dollars spent per ton of SO 2 removed and per deciview of im provement. Even worse are the incremental dollar per ton and dollar per deciview values in moving up to the best control. At the lesser 90% control level, the cost per deciview of improvement is over 4.7 million dollars. Holcim believes this amount is excessive, especially considering the minimal visibility improvements achieved. A co st of over 6 million dollars per year to achieve an undetectable visibility impr ovement seems unjustified and outside the intention of the BART program.

Of the alternative SO 2 control technologies identified above, none is feasible at the Trident facility. Holcim proposes to continue to employ the baseline of proper kiln design and operation and comply with the existing SO 2 emission limitation (124 lbs/hour on a rolling 30-day basis). Therefor e, no new requirements for SO 2 are proposed under the BART program.



### 4.4 NO
x 

### BART Analysis for the Kiln

Most of the NO x formed within a rotary cement k iln is classified as thermal NO x . Thermal NO x results when the heat from fuel com bustion causes atmospheric nitrogen to combine with atmospheric oxyg en. Virtually all thermal NO x is formed in the region of the flame at the highest temperatures, approximately 3000°F to 3600°F. A small proportion of NO x emissions results from nitrogen that is liberated from the fuel and reacts with oxygen in the air.HCM Air Quality Issues /BART 7/6/07 pg. 4-13 Project #: HCM207541 Theoretically, the following principl es can be employed to reduce NO x formation:

• Reduce peak flame zone temperatures,

• Reduce fuel residence time in the flame zone,

• Reduce mixing of fuel and combustion air,

• Reduce oxygen concentrations in the flame zone, and

• Reduce excess air in the combustion process.

There are also post-combustion NO x control technologies which remove NOx from the flue gas after formation, using technologies t hat chemically convert it to nitrogen and
water.

4.4.1 Identify All Available NO x Retrofit Control Technologies – Step 1

EPA’s RBLC describes several permitted cem ent kiln installations and lists their pollutant emission limits and the control tec hnologies approved to achieve those limits. Other sources of information regarding potentially applicable NO x control technology for cement kilns incl ude EPA’s 2000 NO x Control Technologies for Cement Kilns, and the Assessment of NO x Emissions Reduction Strategies for Cement Kilns – Ellis County, TX. First, Holcim evaluated all NO x control technologies for cement manufacturing using the documents stated above, and then identified the contro l technologies that were potentially applicable to long, wet kilns. T he technologies that were identified as potentially applicable for controlling NO x from Holcim’s cement kiln are divided into three categories: process modifications, fuel and raw material substitutions and postcombustion control technologie s. These are detailed below.

(i) Proper kiln design and operation (baseline), (ii) Process modifications

• Increased thermal efficiency, and

• Combustion system modifi cations including low-NO x burner (LNB) (iii) Fuel and raw material substitutions

• Mid-kiln fuel injection, and

• CemStar process, (iv) Post-combustion control technologies

• Selective non-catalytic reduction (SNCR).

• Selective catalytic reduction (SCR), and

• LoTOx TM

The following is a brief discussion of each of the control technologies.

(i) Proper Kiln Design and Operation Many interdependent and sometimes compet ing factors must be considered in the design and operation of a cement kiln. Primary among them are product quality requirements, operating costs, an d pollution mitigation. Burner operation is central to all three. Product quality is cr itically dependent upon flam e temperature and kilnHCM Air Quality Issues /BART 7/6/07 pg. 4-14 Project #: HCM207541 atmosphere composition. Both of these c onditions are also primary factors in the production of NO x . Low temperatures reduce the production of NO x . Temperatures that are too high, besides aggravating NO x production, can result in over-burned clinker. A specific concentration of oxygen in the kiln is required to properly control combustion and oxidize the limestone and other minerals. Some of that oxygen is supplied with the combustion air and strongly affects fuel combustion characteristics such as temperature.

Fuel costs are a major portion of the cost of cement production. Consequently, every effort is made to conserve heat and thereby reduce costs. Efforts to maximize fuel efficiency also serve to reduce pollutant em issions; increasing the amount of cement produced per unit of fuel decreases the amount of combustion-related pollutants emitted per unit of product.

Fuel selection can influence NO x production in two ways: the amount of chemically bound nitrogen in the fuel helps determine t he fuel’s direct contribution to NO x emissions, and the fuel’s combustion char acteristics help determine the amount of thermal NO x created. Natural gas kilns produc e approximately three times more NO x on an equivalent production basis than coal-fired kilns. Although coal contains more fuelbound nitrogen than natural gas, it burns at lower temperatures and so produces less thermal NO x . Petroleum coke may produce less NO x than coal because it contains less nitrogen per unit of heat value and burns with a lower flame temperature. 11 Holcim currently uses coal and coke as the main f uel source, using natural gas only for start-up and shut-down.

In some cases, reducing emissions of a par ticular pollutant can cause an increase in emissions of another. This is especially true of the relationship between NO x and CO. CO is generally produced as a result of in complete combustion of organic materials. Attempts to achieve more complete com bustion typically involve increasing oxygen concentration and flame temperatures, tw o factors that lead to increased NO x production.

Cement kiln operation is designed to balanc e and optimize the above parameters for a specific set of external constraints such as feed quality, product quality requirements, pollutant emissions restrictions, and fuel av ailability. The design includes operational monitoring and control systems that allo w the maintenance of optimum operating conditions.

(ii) Proces s Modifications There are many process modifications whic h could be made to a cement production facility in order to reduce NOx emissions. Thes e modifications are very site-specific and must factor in existing equipment, processes, fuels and raw materials, etc. Holcim has

11 USEPA “Alternative Control Techniques Document – NO x Emissions from Cement Manufacturing,” EPA-453/R-94-004, Office of Air and Radiation, Offi ce of Air Quality Planni ng Standards, March 1994, page 5-4.HCM Air Quality Issues /BART 7/6/07 pg. 4-15 Project #: HCM207541 identified the following process modifications as feasible at the Trident facility, with potential to significantly reduce NOx emissions.

Increased Thermal Efficiency One process modification Holcim has reviewed to improve the thermal efficiency of the Trident kiln is the installation of a fixed inlet at the clinker cooler. A fixed inlet modification to the clinker cooler improves the heat recovery to the kiln inlet and the overall efficiency of clinker cooler operation. With increased cooler efficiency, a greater amount of heat in the clinker is recove red, which increases the secondary air temperature of the kiln/cooler system. C onsequently, the amount of fuel required in the kiln can be reduced because more heat ha s been captured from the cooler and does not need to be supplied by the combustion system . With the reduction in fuel usage, a proportional reduction of thermal NOx from the combusti on process is achieved. A 0 to 5% reduction in NO x emissions can be expect ed from the installation of the fixed inlet on the clinker cooler.

Combustion System Modifications Including Low-NOx Burner (LNB) Another process modification Holcim believes is applicabl e in reducing NOx emissions at the Trident facility is addition of a low NOx burner in c onjunction with other combustion system modifications. T he addition of an LNB will reduce NO x formation by controlling the mixing of fuel and air to provi de low-excess-air firing or off-stoichiometric combustion. These burners are designed to reduce peak flame temperature and/or reduce the residence time at hi gh temperature. The most common LNBs include staged air burners or staged fuel burners.

Staged air burners consist of a two-stage com bustion process. Combustion initiates under fuel-rich, oxygen-deficient conditions in the primary combustion zone. These conditions allow attainment of the requi red flame temperature while reducing the formation of fuel and thermal NO x. They also lead to incomplete fuel combustion. In the secondary zone, relatively cool additional air (staged air) is introduced to complete the combustion process. The cooler temperatures resulting from introduction of the staged air suppress NO x formation in this stage.

Staged fuel burners mix all of the air and a portion of the fuel to create a fuel-lean environment in the primary combustion chamber. This leads to lower flame temperatures and, consequently, reduced NO x production. The remaining fuel is then injected at high pressures into the secondar y combustion zone where the relative lack of oxygen inhibits NO x formation. Staged fuel burners are compatible only with gas-fired combustion units.

LNBs can also create oxygen-deficient co nditions in a primary combustion zone by recycling a portion of the kiln exhaust gas to the burner, eit her in the primary air that accompanies the injected coal or directly into the flame. This is referred to as flue gas recirculation (FGR). This effect can also be achieved by creating a low-pressure zone at the center of the burner. T he low-pressure zone tends to draw in oxygen-poor combustion gases that mix with the fuel and primary combustion air. Using an FGRHCM Air Quality Issues /BART 7/6/07 pg. 4-16 Project #: HCM207541 would result in unacceptabl e cement product quality and has not been applied at a cement kiln.

LNB control technology typically has reductions between 15 and 30% in NO x emissions.

(iii) Fuel and Raw Material Substitutions

Mid-Kiln Fuel Injection
During mid-kiln injection, ty pically, a combustible material such as tire-derived fuel (TDF) or other lump fuel, is in troduced near the center of the kiln. This addition of a heat source midway through the calcining proce ss reduces the temperature required in the primary combustion chamber, thereby reducing the formation of thermal NO x . Reductions in NO X occur as a result of the radiative transfer of heat from the primary combustion zone prior to reaching the se condary combustion zone. In addition, the entrained secondary fuel acts to reduce the temperature of the primary combustion products. NOx is reduced in the kiln combus tor by following simplified reactions:

**NO + C** → **N + CO**

**and**

**NO + CO** → **N + CO 2** 

TDF combustion also lowers the amount of fuel-bound nitrogen in troduced to the kiln and thereby lowers NO X emissions through another mec hanism. Some fuels, such as TDF also introduce material to the cement clinker (such as steel) that may add beneficial qualities to the final product.

EPA, Environment Canada, and many US R egional Air Agencies documents have identified combustion of TDF, especially mid-kiln intro duction of tires, as an NO x control technology. **12**
, **13** This technology typically has reductions between 30 and 50% in NO x emissions.

CemStar Process CemStar is a patented process developed by TXI industries that can reduce NO x emissions by the addition of st eel slag to the feed end of t he kiln. Steel slag has a low melting temperature and desirabl e chemical components of cl inker in its material. The slag is directly added to the ce ment clinker manufacturing proc ess. Due to the chemical composition of the steel slag, the material requires less fuel to convert it into cement slag, potentially resulting in lower total f uel consumption. The decreased need for limestone calcination per unit product and impr oved thermal efficiency of the process can lead to lower thermal NO x emissions.

12 Assessment of NO X Emission Control Technologies for Cement and Lime Kilns. April 1995.

13 EPA-453/r-94-004, March 1994.HCM Air Quality Issues /BART 7/6/07 pg. 4-17 Project #: HCM207541 (iv) Post Combusti on Control Technologies

Selective Non-Catalytic Reduction (SNCR) SNCR is a proven technology in the cement industry for preheater/precalciner kilns to efficiently reduce NOx emissions. Li ke SCR technology, SNCR reduces NO X to nitrogen and water, but it does so without the use of a catalyst. It injects a nitrogenous reducing agent, typically ammonia or urea, into the upper reaches of the furnace. Because a catalyst is not used to drive the reaction, a temperature of 1600 to 2100 o F is required for the reduction reaction to proceed.

NO X removal efficiency is dependent on inlet NO X concentrations, fluctuating flue gas temperatures, residence time, amount and type of nitrogenous reducing agent, mixing effectiveness, and the presence of interfering chemical substances in the gas stream.

In the past, SNCR technology was only cons idered feasible for preheater/precalciner type kilns and not for long wet or dry kilns. The reason is the difference in design between preheater/precalciner k ilns and long wet or dry kiln s. Preheater/precalciner kilns, which are shorter than long kilns, have the optimal te mperature range (1600 o F to 2100 o F) for the necessary reaction to take place at the end of the ki ln, without having to inject ammonia- or urea-based r eagents into the rotating kiln itself. In long kiln designs (both wet and dry), the optimal temperature range to make an SNCR effective occurs in the middle of the kiln; theref ore, mid-kiln injection of the ammonia- or urea-based reagents would have to be incorporated into the kiln design. Until recently, this has made the installation of an SNCR technically infeasible because the injection of the reagents was not continuous and not effective.

Selective Catalytic Reduction (SCR) SCR is a post-combustion gas treatment techni que that uses a catalyst to reduce NO and NO 2 to molecular nitrogen, water, and oxygen. Ammonia (NH 3 ) is commonly used as the reducing agent. Ammonia is vaporized and injected into the flue gas upstream of the catalyst bed, and combines with NO X at the catalyst surface to form an ammonium salt intermediate. The amm onium salt intermediate then decomposes to produce elemental nitrogen and water. The catalyst lowers the temperature required for the chemical reaction between NO X and ammonia.

In general, the installations of SCRs are o perated in clean gas circuits; i.e., dust and heavy metals are separated from the exhaust stream before the catalyst in order to prevent rapid wear and deactivation of t he catalysts through catalyst poisons.

Technical factors that impact the effectivene ss of this technology include the catalyst reactor design, operating temper ature, type of fuel fired, sulfur content of the raw material, design of the ammonia injection syst em, and potential for catalyst poisoning.

An SCR characteristic common to all cataly st types is the narrow window of acceptable system inlet temperatures. Below the mi nimum acceptable temperature of about 575 ° F, the NO x reduction reaction will not proceed, while operation above the maximumHCM Air Quality Issues /BART 7/6/07 pg. 4-18 Project #: HCM207541 acceptable temperature of about 750 ° F results in shortened cata lyst life and can lead to the oxidation of NH 3 to nitrogen oxides, thereby actually increasing the NO x emissions, or possibly generating explosive levels of ammonium nitrate in the exhaust gas.

Another critical factor affe cting SCR performance, especially in an ap plication such as coal-fired lime and cement kilns, is related to SO 2 in the exhaust gas . The SCR catalyst will oxidize SO 2 to SO 3 , which can form ammonium bisulfate and sulfuric acid. Ammonium bisulfate is a sticky solid that causes clogging within the catalyst, while sulfuric acid can cause corrosion within t he system and result in increased visible emissions.

LoTOx TM
LoTOx TM is a patented technology that uses ozone to selectively oxidize NO X to higher forms of oxides of nitrogen, which become so luble and can be easily removed by a wet scrubber. This technology may require re heating of the gas stream and has a high electrical energy consumption which would raise the power consumption of Holcim’s facility. Furthermore, there is potential to create new wast e streams like waste water or sludge that require further tr eatment. There are no known LoTOx installations in the cement industry.

According to TCEQ’s ASSESSMENT OF NOx EM ISSIONS REDUCTION STRATEGIES FOR CEMENT KILNS – ELLI S COUNTY, FINAL REPORT (dated 7/14/06) 14 Section 4.3.2, states:

“The large gas volumes, high moisture levels and large quantities of dilution air ne eded to reach the operating temperature range in some systems may limit the applicability of the LoTOx TM system.”

4.4.2 Eliminate Technically Infeasible NO x Control Options – Step 2

The methodology used to eliminate technica lly infeasible contro l technologies for NOx was described in Section 4.3.2 above. The reader is referred to that section for details of this process.

(i) Proper Kiln Design and Operation Proper design and operati on of cement kilns is clearly feasible and serves as the baseline case. Holcim’s kiln design includes control system s for balancing primary and secondary combustion air flow rates and ve locities. This will enable operators to optimize fuel and air mixing and ratios for minimal NO x formation.

14 The final report itself (dated on 7/14/06) may be found at: http://www.tceq.state.tx.us/implem entation/air/sip/BSA_settle.html.HCM Air Quality Issues /BART 7/6/07 pg. 4-19 Project #: HCM207541 Conclusion: This technology is considered feasible for purposes of Step 2 in this BART analysis.

(ii) Process Modifications

Increased Thermal Efficiency Holcim has identified a process modification that has the potentia l to increase thermal efficiency of the kiln and reduce NOx emissions. The process alteration involves adding a fixed inlet to the clinker cooler, which wi ll increase thermal efficiency of the kiln, and thereby reduce fuel consumption and reduce thermal NO x formation in the kiln.

Conclusion: This technology is considered feasible for purposes of Step 2 in this BART analysis.

Combustion System Modifi cations Including Low-NO x Burner (LNB) Control of NO x emissions using methods employed by LNBs such as staged air combustion, though extremely limit ed in practice, is technically feasible for a coal-fired rotary kiln. As noted above, cement producti on requires balancing many combustion parameters to optimize cement quality and ener gy efficiency while limiting emissions of multiple air pollutants. The cement produc tion system must be capabl e of adjusting and responding quickly to changes in external condi tions. Because of these requirements, some LNB technologies, such as staged fuel combustion units, may not be practical or effective when applied to Holcim’s kiln.

FGR in conjunction with an LNB has not been dem onstrated in kiln applications to provide better NO x reduction than can be achieved by controlling primary and secondary combustion air in a properly designed and operated kiln . Adding FGR to a burner that is already design ed for optimum flame shaping a nd control would distort the thermal profile of the ki ln such that product qua lity would be unacceptably compromised. Such a flame profile would also reduce kiln efficiency and potentially result in increased NO x emissions.

Holcim believes a carefully selected LNB in conjunction with pr oper combustion system modifications can achieve approximatel y a 17% NOx emission reduction.

Conclusion: This technology is consider ed technically feasible for purposes of Step 2 in this BART analysis.

(iii) Fuel and Raw Ma terial Substitutions

Mid-kiln Fuel Injection Holcim has previously identified mid-kiln inje ction of tires as a desirable process to add to the facility. In 2001, Ho lcim applied for an air qualit y permit from the Montana Department of Environmental Qua lity to authorize the addition of a mid-kiln tire injection system. To date, there has not been any fi nal action taken on that application.HCM Air Quality Issues /BART 7/6/07 pg. 4-20 Project #: HCM207541 Conclusion: This technology is consider ed technically feasible for purposes of Step 2 in this BART analysis.

CemStar Process Holcim is not aware of any source of steel slag for use in the CemStar Process within a reasonable distance of the Holcim facility. T herefore, there is no commercially available source of steel slag for the kiln that would be considered “available” to Holcim for purposes of BART.

Conclusion: This technology is considered technically infeasible for purposes of Step 2 in this BART analysis. No further discussion of this technology will be presented.

(iv) Post-Combustion Control Technologies

Selective Non-Catalytic Reduction (SNCR)

In the past, SNCR technology was only cons idered feasible for preheater/precalciner type kilns and not for long wet or dry kilns. More recently, there has been a trial installation of an SNCR system on a wet kiln in France. This installation was a trial run conducted over a f our-month period.

The Holcim Trident facility believes there is very limited experienc e with the application of SNCR to a long, wet kiln. T herefore, the Holcim Trident facility believes it is currently an emerging technology and the application of SNCR is not an available BART technology.

Holcim has investigated the feas ibility of adding urea into t he existing mid-kiln injection system, the dust scoops mechanism. The dus t scoops are a mechanism which recycles cement kiln dust by injecting it into the kiln as it rotates. By addi ng urea to the dust scoops during normal operations, the r eagent would be injected into the postcombustion zone of the kiln. The downfall of this application is that the temperature profile of the kiln sh ows a temperature of 1400 o F at the location of the dust scoop mechanism. This is below the range of temperatures (1600 o F to 2100 o F) necessary for the NOx reduction reaction to take place and be effective. The other drawback to this application is that the short physical dist ance from the dust scoops downstream to the radiative cooling section of t he kiln would give the flue gas a very short residence time. Thus, the mixing of reagent and flue gas w ould likely be incomplete. Holcim believes these two factors combined woul d either substantially reduc e or completely eliminate the SNCR reaction and NOx reduct ions would not be achieved.

Conclusion: Holcim believes SNCR is not available to the Trident facility for purposes of Step 2 in this BART anal ysis. No further di scussion of this technology will be presented.HCM Air Quality Issues /BART 7/6/07 pg. 4-21 Project #: HCM207541 Selective Catalytic Reduction (SCR) SCR is not feasible for application to the Ho lcim cement kiln for the following reasons.

● First, SCRs are not sufficiently develop ed to make them commercially available in the U.S.; therefore, it should not be considered a feasible control technology. Although this technology has been used in coal-fired power plants, its commercial application to the cement industr y is limited to two cement plants in the world, one in Solnhofen, Germany, and one in Di Monselice, Italy. The Solnhofen Portland cement pl ant located in southern Germany started operating an SCR system in 2001 and, after seven year s of trials, the facility has not been able to finalize its design and resolve a ll its operational issues. During this period, the facility has worked on probl ems associated with catalyst design, sizing, and plugging. App lication of SCR at Solnhof en has been a long, drawn out pilot-test, not a full-scale commercial success. Due to the operational problems, the SRC technology is no longer being used as an NOx control technology at Solnhofen. The plant in Di Monselice, Italy, installed SCR approximately a year ago, and at this time there is not enough experience and information from this installation to evaluate its performance or draw any conclusions. Consequently, its reliability and effectiveness in this application are unknown.

The Texas Commission on Environmental Quality (TCEQ) adopted new rules on May 23, 2007, to control NO x emissions from cement kilns in the Dallas-Fort Worth ozone non-attainment area. Based on TCEQ’s study, in Chapter 117 – Control of Air Pollution from Nitrogen Compounds, pg 256 :

“...........however, neither SCR nor LoTOx has been applied to wet process cement kilns, and only SCR has even been attempted on dry process cement kilns with results that are in question and that cannot necessar ily be transferred to the kilns in Ellis County.”

• Second, the sulfur concentrations in the ra w materials at Trident are much higher than that of the European plants. T hus, the higher concentrations of SO 2 in the kiln exhaust gas could cause sticky dust forma tion, leading to catalyst plugging, poisoning, and shortened lifespan.

• Third, the high particulate l oading of the exhaust stream would require that the unit be located downstream of the ESP. Otherwise, catalyst effectiveness and longevity would be severely limited due to poisoning and plugging. Because the highest exhaust gas temperature is typically near 400°F – well below the optimum SCR inlet temperature range of approximately 575 to 800°F – the gas stream would require reheating. This would increase the cost of controls, generate ad ditional combustion pollutant emissions, and impose s ubstantial energy penalties.

Conclusion: SCRs are not sufficiently devel oped for cement kilns to overcome the potential problems listed above, and are not considered commerciallyHCM Air Quality Issues /BART 7/6/07 pg. 4-22 Project #: HCM207541 available for this purpose. Ther efore, SCR is not considered “available” to Holcim for purposes of BART. This technology is considered technically infeasible fo r purposes of Step 2 in this BART analysis. No further discussion of th is technology will be presented.

LoTOx TM To be thorough in the analysis, Holcim identified LoTOx TM technology as a potential NO x control technology; however , there are no known LoTOx TM installations in the cement industry. Therefore, LoTOx TM is not considered “available” to Holcim for purposes of BART.

Conclusion: This technology is considered technically infeasible for purposes of Step 2 in this BART analysis. No further discussion of this technology will be presented.

4.4.3 Evaluate Control Effectiveness of Remain ing NOx Control Technologies – Step 3

Of the alternative NO x control technologies identifie d above, proper kiln design and operation, process alterations, combustion system modifications including a low-NO x burner and mid-kiln tire injection remain as technically feasible options. Proper kiln design and operation is the baseline case fo r this analysis. Table 4-4 summarizes the control effectiveness of the re maining control technologies.



### Table 4-4: Summary of Remaining NOx Control Technology Efficiency

Control Option Efficiency (%) NOx Emissions

(lbs/hr) NOx Emissions (tpy) Tons NOx Removed Mid-Kiln Injection of Tires 30% 1,098 4,807 2,060 Combustion System Modifications including Low-NOx Burner 17% 1,301 5,700 1,168 Process Alterations (Install fixed inlet on clinker cooler) 3% 1,521 6,662 206 Baseline 0% 1,568 6,868 0

4.4.4 Evaluate Impacts and Document the Results – Step 4

Process Alterations Impacts

Process Alterations Economic Impacts Holcim has calculated the cost-effectivene ss for the process alte rations, including a fixed inlet to the clinker cooler for NOx co ntrol, with the results presented in Table 4-5 below. The table summarizes the cost-effectiv eness for each of the technically feasible NOx control options, compared against a base line of proper kiln design and operation. Details of the process alteration co st analysis can be found in Appendix C.HCM Air Quality Issues /BART 7/6/07 pg. 4-23 Project #: HCM207541 Process Alterations Energy Impacts There are no negative energy impacts associated with installing a fixed inlet on the clinker. A fuel savings through impr oved kiln efficiency is expected.

LNB Impacts

LNB Economic Impacts

Holcim has estimated the cost of com bustion system modifications, including the addition of an LNB based on EPA’s NOx Control Technolo gies for Cement Industry (Table 6-8), which estimates an annualized cost of $398,000 (1997 $) for retrofit LNB installations for a 50 ton/hr long wet kiln. It is assumed this is a representative cost. The cost in 1997 dollars was adjusted to 2006 dollars using the 1.25607 CPI multiplier 15

. The adjusted annualized cost was calculated to be $498,065. The results are presented in Table 4-5 below. Details of the cost analysis can be found in Appendix C.

LNB Environmental Impacts

There are no negative environment al impacts associated with LNB technology. There are, however, heightened safety concerns a ssociated with the LNB fuel delivery system. Because the flow rate of air used to inject pulverized coal is reduced, there is increased risk of combustion occurring within the coal mill system.

LNB Energy Impacts

There are no significant negative energy im pacts associated with the combustion system modifications and an LNB.

Mid-Kiln Fuel Injection Impacts

Mid-Kiln Fuel Injection Economic Impacts Kiln modifications and a tire handling and injection system are required for mid-kiln introduction of TDF. The guidance documen t (EPA NOx Controls for Cement Industry Final Report, Sept. 19, 2000 Table 6-10) estimates an annualiz ed cost of $370,000 (1997 $) for mid-kiln firing conversion for a 50 t on/hr long wet kiln. It is assumed this is a representative cost. The cost in 1997 dollars was adjusted to 2006 dollars using the 1.25607 CPI multiplier. The adjusted annualiz ed cost was calculated to be $473,738. The results are presented in Table 4-5 below. Details of the cost analysis can be found in Appendix C.

Mid-Kiln Fuel Injection Environmental Impacts Holcim has studied the environ mental impacts extensively, as reported in multiple submissions to Montana DEQ. CO emissions are expected to increase slightly. PM

15 The CPI multiplier calculator may be found at: h ttp://www.minneapolisfed.org/research/data/us/calc/.HCM Air Quality Issues /BART 7/6/07 pg. 4-24 Project #: HCM207541 emissions are not expected to show any appreciable change. SO 2 emissions are expected to be unchanged. VOC emissions are expected to decrease slightly. Metal emissions are expected to decrease. Dioxin /furan (D/F) emissions are not expected to change significantly. Holcim believes combus ting TDF in the kiln will have a net environmental benefit by reduci ng the number of tires placed in solid waste landfills, reducing the amount of coal and coke curr ently combusted, reducing the impacts associated with mining the coal, and reducing fossil fuel dependence.

Mid-Kiln Fuel Injection Energy Impacts There are no significant negative energy impac ts associated with the combustion of tires through mid-kiln injection.

Alternatives Analysis Summary

Holcim has identified several NOx reducing techniques which all have acceptable cost, energy and environmental impacts. Table 4-5 bel ow summarizes the cost impacts of the remaining alternatives. For this analysis, it has been assumed that the remaining life of all of the equipment is at least the 10 y ears used to calculate the annualized costs.



### Table 4-5: Summary of NOx Cost Impacts

Control Option Estimated Annualized Cost Efficiency (%) NOx Emissions

(lbs/hr) NOx Emissions (tpy) Tons Removed Cost Effectiveness ($/ton)
Mid-Kiln Injection of Tires $473,738 30% 1,098 4,807 2,060 $230

Combustion System Modifications with Low-NOx Burner $498,065 17% 1,301 5700 1168 $427

Process Alterations (Install fixed inlet to cooler) $448,250 3% 1,521 6662 206 $2,176

Baseline $0 0% 1,568 6868 0 --

The costs per ton for NOx re moval are all in the range of generally what would be acceptable for NOx control in a Montana BA CT analysis. The annual ized costs of all three options are also considered acceptable by Holcim.

4.4.5 Evaluate NOx Visibility Impacts – Step 5

Holcim has performed modeling using the CALPUFF model to predict visibility impacts of the identified potentially applicable NOx control technologies, using the 98 th percentile visibility result as recommended by EPA. T he results of the modeling are shown in Table 4-6 below. The results are only pr esented for the Gates of the Mountains Wilderness Area, as it is the closer and mo re impacted Class I area. Details of the modeling are found in Appen dix B to this document.HCM Air Quality Issues /BART 7/6/07 pg. 4-25 Project #: HCM207541 

### Table 4-6: Summary of NOx Visibility Impacts a

Gates of the Mountai ns Wilderness Area

Control Option Estimated Annualized Cost Efficiency (%) NOx Emissions

(lbs/hr) Visibility Impact (deciview) Visibility Improvement

(deciviews 24 hr) Cost Effectiveness ($/deciview)

Mid Kiln Injection of Tires $473,738 30% 1,098 0.976 0.584 $811,195

Combustion System Modifications with Low-NOx Burner $498,065 17% 1,301 1. 122 0.438 $1,136,097

Process Alterations (Install fixed inlet to clinker cooler) $448,250 3% 1,521 1. 278 0.282 $1,591,797

Baseline $0 0% 1,568 1.560 0 --

a Deciviews at each % reduction for the Gates of t he Mountains are calculat ed using the equation: y = 0.0112x + 0.248 derived from using the best fit tr endline of the average 98th percentile modeling values.

4.4.6 Select NO x BART

SCR, SNCR, LoTOx TM and CemStar technologie s have been eliminated as inappropriate for controlling NO x emissions from the facility’s cement kiln. The remaining options are the baseline cond ition of proper design and oper ation of the kiln, process alterations including a fixed inlet on the clinker cooler, co mbustion system modifications including a Low NOx Burner, and mi d-kiln injection of tires.

Holcim believes that all of the remaining NOx control tec hnologies are effective and economically feasible. However, Holcim cannot ensure the us e of mid-kiln injection of tires within the five year timeline spelled out in the BART program. Holcim cannot use tires as a fuel source unt il the Montana DEQ issues a fi nal air quality permit and any legal appeals are concluded. The current permitting and EIS process has been ongoing for at least six years, and Holcim has no contro l over the timeline or the outcome of the process. More negotiation and li tigation is expected. For t hese reasons, Holcim cannot propose mid-kiln injection of tires as BART.

Therefore, for the purpose of NOx control, Holcim select s a combination of process alterations, including a fixed clinker cool er inlet, and combustion system modifications, including a low NOx burner as BART. Holcim proposes to make the 20% NOx reduction federally enforceable by reducing the curre nt permit limitation of 1,568 lbs/hour on a rolling 30-day basis to 1,254 lbs/hour on a rolling 30-day basis.



### 4.5 BART Analysis for PM 10 

### from the Kiln

4.5.1 Identify Available Particulate Control Technologies – Step 1

EPA’s RBLC describes several permitted cem ent kiln installations and lists their pollutant emission limits and the control tec hnologies approved to achieve those limits. Another source of information regarding potenti ally applicable PM control technology forHCM Air Quality Issues /BART 7/6/07 pg. 4-26 Project #: HCM207541 cement kilns is the EPA’s AP-42 for Port land cement manufacturing (Chapter 11, Section 6). The following tech nologies were identified as potentially applicable for controlling particulate matter from cement manufacturing using a wet process kiln:

(i) Proper kiln design and operation with an electrostatic precipitator (ESP) (baseline), (ii) Fabric filter baghouse, and (iii) Cooling tower, mult iclone, and ESP combination.

Control Technology Description:

(i) Proper Kiln Design and Operation Many interdependent and sometimes compet ing factors must be considered in the design and operation of a cement kiln. Primary among them are product quality requirements, operating costs, an d pollution mitigation. Burner operation is central to all three. Product quality is cr itically dependent upon flam e temperature and kiln atmosphere composition.

Holcim currently operates an ESP to control particulate emi ssions from the kiln. An ESP uses electrical forces to move entrained par ticles onto a collection surface. To remove dust cake from the collection surface, the co llection surface is peri odically “rapped” by a variety of means to dislocate the parti culate, which drops down into a hopper. Particulate-laden air must be able to be collected and ducted to the ESP.

(ii) Fabric Filter Baghouse Directed air flow passes through tightly woven or felted fabric, causin g PM in the flow to be collected on the fabric by sieving and othe r mechanisms. As PM collects on the filter, collection efficiency increases while pressu re drop through the system increases. Bags are intermittently cleaned by shaking the bag, pulsing air through the bag, or temporarily reversing the airflow directi on. Particulate-laden air must be able to be collected and ducted to the baghouse.

(iii) Cooling Tower, Mult iclone, and ESP Combination A multiclone system is an application wh ere many small cyclones are operating in parallel. The small cyclones remove particula te by centrifugal and inertial forces, induced by forcing particulate-laden gas to c hange direction. This type of technology is a part of the group of air pollution controls collectively referred to as “precleaners,” because they are often used to reduce the inlet loading of particulate matter to downstream collection devices by removing larger, abrasive particles.

The cyclones are used to cont rol PM, and primarily particulate matter greater than 10 micrometers ( μ m). However, there are high effici ency cyclones designed to be effective for PM less than or equal to 10 μ m and less than or equal to 2.5 μ m (PM 10 and PM 2.5 ). Although cyclones my be used to co llect particles larger than 200 μ m, gravity settling chambers or simple momentum separators are usually satisf actory and less subject toHCM Air Quality Issues /BART 7/6/07 pg. 4-27 Project #: HCM207541 abrasion. The combination of a multiclone and an ESP can achieve a very high collection efficiency.

4.5.2 Eliminate Technically Infeasible Options – Step 2

All of the control devices li sted for the kiln have been su ccessfully applied to many cement kilns with favorable results in controlling particulate matter.

Conclusion: These technologies are c onsidered technically feasible for purposes of Step 2 in this BART analysis.

4.5.3 Evaluate Control Effectiveness of Remaining PM 10 Control Technologies – Step 3

Table 4-7 lists available tech nologies with their respective efficiencies for controlling PM/PM 10 emissions from a long wet kiln.



### Table 4-7: Kiln PM/PM 10 

### Control Technology Effectiveness

Control Option Efficiency (%) Proper Kiln Design and Operation with ESP (baseline) 99.9% Fabric Filter Baghouse 99.9% Cooling Tower, Multiclone, and ESP Combination 99.9%

Emissions from the kiln are cu rrently controlled by an electros tatic precipitator (ESP). In December of 2004, MDEQ comple ted an analysis titled “Air Quality Technical Analysis Report for the Review of Submittals Supporti ng the Holcim (US) Inc. Tires Combustion Proposal.”

In Section 4.4, paragraph 6 of the analysis, MDEQ concluded:

“Based on the above equation, t he efficiency of a single field of the Holcim ESP would be greater than 99.9%. This calcul ation does not account for the variable including re-entrainment and rapping. The use of two fields in series provides additional particulate removal.”

Because the ESP has an efficiency equal to the highest control available from the other listed control technologies, Holcim proposes that the current ESP control of PM/PM 10 emissions from the kiln is BART, with associated emission ra te limits of 0.10 gr/dscf, and 0.77 lbs/ton of clinker produced.HCM Air Quality Issues /BART 7/6/07 pg. 4-28 Project #: HCM207541 

### 4.6 BART Analysis for PM 10 

### from the Clinker Cooler

4.6.1 Identify Available Particulate Control Technologies – Step 1

EPA’s RBLC describes many clinker cooler installations and lists their pollutant emission limits and the control technologies approved to achieve those limits. Another source of information regarding potentially a pplicable PM control technology for cement kilns is the EPA’s AP-42 for Portland ceme nt manufacturing (Chapt er 11, Section 6). The following technologies were identified as potentially applicable for controlling particulate matter from the clinker cool er at a cement pr oduction facility:

(i) Fabric Filter Baghouse (baseline) (ii) Electrostatic Precipitator (ESP), (iii) Gravel Bed Filter.

Control Technology Description:

(i) Fabric Filter Baghouse (Baseline) Emissions from the clinker cooler are current ly controlled by a fabric filter baghouse. Directed air flow passes through tightly woven or felted fabric, causi ng PM in the flow to be collected on the fabric by sieving and othe r mechanisms. As PM collects on the filter, collection efficiency increases while pressu re drop through the system increases. Bags are intermittently cleaned by shaking the bag, pulsing air through the bag, or temporarily reversing the airflow directi on. Particulate-laden air must be able to be collected and ducted to the baghouse.

(ii) Electrostat ic Precipitator An ESP uses electrical forces to move ent rained particles onto a co llection surface. To remove dust cake from the collection surfac e, the collection surf ace is periodically “rapped” by a variety of means to dislocat e the particulate, which drops down into a hopper. Particulate-laden air must be able to be collected and ducted to the ESP.

(iii) Gravel Bed Filter Gravel bed filters are commonly used to c ontrol particulate emissions from a clinker cooler. Generally, a cyclone is used to pr e-clean the exhaust stream of larger particulate. The exhaust stream is then directed through a bed of gravel, commonly crushed quartz, which capt ures smaller particulate through agglomeration.HCM Air Quality Issues /BART 7/6/07 pg. 4-29 Project #: HCM207541 4.6.2 Eliminate Technically Infeasible Options – Step 2

All of the control devices lis ted for the clinker cooler ha ve been successfully applied in other installations.

Conclusion: These technologies are c onsidered technically feasible for purposes of Step 2 in this BART analysis.

4.6.3 Evaluate Control Effectiveness of Remaining PM 10 Control Technologies – Step 3

Table 4-8 lists available tech nologies with their respective efficiencies for controlling PM/PM 10 emissions from a clinker cooler.



### Table 4-8: Clinker Cooler PM/PM 10 

### Control Technology Effectiveness

Control Option Efficiency (%) Fabric Filter Baghouse (baseline) 99.9% Electrostatic Precipitator 99.9% Gravel Bed Filter 95% (est.)

Emissions from the clinker cooler are current ly controlled by a fabric filter baghouse.

Because the fabric filter baghouse has an efficiency equal to the highest control available from the other listed control tec hnologies, Holcim propos es that the current emission limit and baghouse control of PM/PM 10 emissions from the clinker cooler are BART. No further analysis is needed.



### 4.7 BART Analysis for PM 10 

### Emissions from Mat erial Handling Systems

The facility includes systems for transporting, transferring, and storing limestone, coal, and finished cement product. Emissions asso ciated with these activities occur as a result of transferring the material from one sy stem to another. These transfers, referred to as “drop transfers,” occur, for exampl e, when material is transferred from one conveyor to another or from a chute to a load-out truck.

Table 4-9 lists the 10 material transfer emissi on sources that will be considered in this BART analysis.HCM Air Quality Issues /BART 7/6/07 pg. 4-30 Project #: HCM207541 

### Table 4-9: Listing of Materi al Transfer Emission Points

Source Current Source Control
005 – Xfer-convey-screen Baghouse 010 – 013 Raw material silos 1-7 Baghouse 015 and 018 Coal and coke xfer, crush, store, (un)load & grinding Baghouse

026 Cement kiln dust silo unload Dustless Unloader and Baghouse 032a Clinker xfer to #2 finish mill Baghouse 047 Cement load/unload at silos 14-25 Baghouse

4.7.1 Identify Available Particulate Control Technologies – Step 1

The following technologies were identified as potentially applicable for controlling particulate matter from raw ma terials and product handling in the cement manufacturing
process:

(i) Fabric Filter Baghouse (baseline), (ii) Electrostatic Precipitator (ESP), (iii) Enclosures, and (iv) Wet Suppression.

Control Technology Description:

(i) Fabric Filter Baghouse The Holcim Trident plant currently utilizes baghouses to control PM emissions from the sources in Table 4-9. Direct ed air flow passes through ti ghtly woven or felted fabric, causing PM in the flow to be collected on t he fabric by sieving and other mechanisms. As PM collects on the filter, collection effi ciency increases while pressure drop through the system increases. Bags ar e intermittently cleaned by s haking the bag, pulsing air through the bag, or temporarily reversing the ai rflow direction. Part iculate-laden air must be able to be collected and ducted to the baghouse.

(ii) Electrostat ic Precipitator An ESP uses electrical forces to move ent rained particles onto a co llection surface. To remove duct cake from the collection surfac e, the collection surf ace is periodically “rapped” by a variety of means to dislocat e the particulate, which drops down into a hopper. Particulate-laden air must be able to be collected and ducted to the ESP.HCM Air Quality Issues /BART 7/6/07 pg. 4-31 Project #: HCM207541 (iii) Enclosures Enclosure technology employs structures or underground placement to shelter material from wind entrainment. Enclosures can eit her fully or partially surround the source.

(iv) Wet Suppression A fogging water spray adds water with or without surfactant to material. Emissions are prevented through agglomerate formation by comb ining small dust par ticles with larger aggregate or with liquid droplets. Water re tained by sprayed material prevents emissions from storage piles and downstr eam transfers in a similar manner.

4.7.2 Eliminate Technically Infeasible Options – Step 2

All of the control methods listed for materi als transfers have been successfully applied to many industries with favorable resu lts in controlling particulate matter.

Conclusion: These technologies are c onsidered technically feasible for purposes of Step 2 in this BART analysis.

4.7.3 Evaluate Control Effectiveness of Remaining PM 10 Control Technologies – Step 3

Table 4-10 lists available technologies with their respective efficiencies for controlling PM/PM 10 emissions from the BART-el igible materials transfers.



### Table 4-10: Material Transfer PM/PM 10 

### Control Technology Effectiveness

All of the listed PM/PM 10 emission sources from the ma terials handling analyzed for BART are currently controlled by fabric filter baghouses. The f abric filter baghouses are equivalent to the highest cont rol efficiency of any of the control devices analyzed; therefore, Holcim propos es that the current baghou se control of PM/PM 10 emissions from the materials transfers is BAR T. No further analysis is needed. Control Option Efficiency (%) Fabric Filter Baghouse (baseline) 99.9% Electrostatic Precipitator 99.9% Enclosures 90% Water Suppression 50-90%

## APPENDIX A: EPA LETTER TO HOLCIM

## APPENDIX B: VISIBILITY IMPACTS MODELINGHolcim BART Analysis pg. B-1 Appendix B 

## VISIBILITY IMPACTS

1.1 Introduction and Summary

Holcim has concurred with the initial EPA BART analysis that the Trident facility is a BART-eligible source. The fo llowing sections det ail the modeling an alysis that Bison performed on behalf of Holcim to comply with the intent of 40 CFR 51, Appendix Y. This document describes the methodologie s and results of those analyses.

In conducting the BART modeling analyses, Bison closely followed the Montana Department of Environmental Quality’s (MDEQ) modeling prot ocol for regional modeling in support of the BA RT program, entitled State of Montana Dr aft CALPUFF BART Modeling Protocol For Feder al Mandatory Class I Areas, September 2006 Draft (“Montana BART protocol”). The analysis also relied on guidance in the Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report for Modeling Long Range Transport Impacts (EPA, 1998), and the Federal Land Managers’ Air Quality Related Values Work group (FLAG) Phase I Report, December 2000 (“FLAG document”).

The BART modeling analysis spec ifically requires demonstrations of impacts to visibility at surrounding mandatory federal Class I ar eas. The mandatory federal Class I areas evaluated are:

• Yellowstone National Park, and

• Gates of the Mountains Wilderness Area.

Visibility Impacts: The visibility impacts analysis began with the permitted emissions from the cement kiln and clinker cooler located at the Trident facility. These impacts were developed to establish a visibility baseline to analyze what effects, if any, different control technologies or operat ing practices had on visibilit y at the surrounding Class I

areas.

The visibility impacts analyses in cluded the appropriate potential NO x , SO 2 , and PM 10 emissions from the sources modeled since all three pollut ants contribute to visibility impairment.



### 1.2 Model Selection

Selection of the appropriate di spersion model for assessing visibility impacts in Class I areas is typically based on the distance from the emitting source to the Class I area. Appendix W in 40 CFR Part 51 recommends different models for different applications and identifies appropriate models for short- and long-range impacts.

Since EPA has already established CALPUFF for the visibility analysis, the CALPUFF model was used in the present analyses of Class I visibility impacts.Holcim BART Analysis pg. B-2 Appendix B CALPUFF is a non-steady-state Lagrangian dispersion model that simulates pollutant releases as a continuous series of “puffs.” It includes algorithms for building downwash, pollutant removal due to wet scavenging a nd dry deposition, chemical transformation, and plume fumigation. It is supported by two primary sub-programs, CALMET and CALPOST. CALMET is used in refined analyse s to create three-dim ensional wind fields based on multiple sources of geophysical and meteorological data. The output of the CALPUFF model consists of binary dat a files with information on pollutant concentrations, wet and dry flux rates, and visibility parameters. CALPOST processes these data based on specified input parameters, and reports calculated impact values.

The present CALPUFF analysis utilized the most current version of the following primary programs and pre- and post-processors obt ained from the CALPUFF developer, Atmospheric Studies Group (ASG) at:

http://www.src.com/calpuff/calpuff1.htm

. Geophysical Data Processors

• TERREL (Version 3.311, Level 030709)

• CTGCOMP

• CTGPROC (Version 2.42, Level 030709)

• MAKEGEO (Version 2.22, Level 030709)

Meteorological Preprocessors

• SMERGE (Version 5.31a, Level 040706)

• PXTRACT

• PMERGE (Version 5.31, Level 030528)

• READ62 (Version 5.52, Level 040716)

Main Models

• CALMET (Version 6.211, Level 060414)

• CALPUFF (Version 6.112, Level 060412)

Postprocessors

• CALPOST (Version 6.131, Level 060410)

• PRTMET

• CALSUM

• POSTUTIL

The version and level identifie rs for the major modules used for this project are identified above. Electronic ex ecutable files for the primar y modules and the primary electronic input and output files associated wit h this analysis are available upon request.



### 1.3 Regional Modeling Domain

The regional modeling domain was defined to follow the Montana Protocol. The modeling domain is defined in a Lambert Conformal Conic (LCC) system. The LCC coordinate system for this proj ect has a projection origin at 44.25° N and 109.5° W andHolcim BART Analysis pg. B-3 Appendix B matching parallels of latitude of 44.0° and 49.0° N. The c oordinates of the southwest corner of the domain are 0.000 km easting and 0.000 km northing

. This varies from the WRAP modeling domain which defined matching pa rallels of latitude of 45.0° and 49.0° N.



### 1.4 CALMET

CALMET, the meteorological preprocessor for CALPUFF, was used to compile and process land use data, terrain data, and me teorological data for use in the CALPUFF model program. The CALMET output files defined gridded fields of wind speed, wind direction, mixing heights, stab ilities, micrometeorological pa rameters, and precipitation – all parameters required for input to the CALPUFF dispersion model. The following sections provide a brief description of each of these data sets.

1.4.1 

### Land Use Data

CALMET uses specific land use data deve loped by the U.S. Geological Survey (USGS) 1 . The data files used for this project we re 1:250,000-scale files. Each land use cell, typically 200 meters square, is assi gned a land use code. Using several data processing programs provided by ASG, t he land use data were processed and combined with other geophysical data into a single data se t for input to the CALMET model.

1.4.2 

### Terrain Data

CALMET uses USGS 1:250k Digital Elevatio n Models (DEMs) to determine the terrain elevation in the model domain. The terra in data is preprocessed into a data set recognized by CALMET and used to help cr eate the CALMET output file. Terrain data obtained from www.webmet.com were used to create the appropriate files for CALMET.

1.4.3 

### Meteorological Data

CALMET output files repr esenting meteorological data for the 2001, 2002, and 2003 calendar years were prepared for the analysis in accordanc e with the Montana BART protocol. Input meteorological data consisted of Mesoscale Model (MM) meteorological data, observed hourly surface data, upper air rawinsonde data, and hourly precipitation data.

Mesoscale Model Data

The MM meteorological data for the 2001, 2002, and 2003 calend ar years obtained from the Western Regional Air Partnership (WRAP) are available at the following website: http://pah.cer t.ucr.edu/aqm/308/bart.shtml . These data are generated by Pennsylvania State University/National Cent er for Atmospheric Research mesoscale models. The mesoscale models are limited-area, nonhyd rostatic or hydrostatic, terrainfollowing sigma-coordinate models designed to simulate or predict mesoscale and

1 Available for download from the USGS Earth Re sources Observation and Science (EROS) web site.Holcim BART Analysis pg. B-4 Appendix B regional-scale atmospheric ci rculation. The data are used as a basis for generating an “initial guess field” of multilayer wind vector s in CALMET. The meteorological data for all three years are in the MM5 format. They reflect a spatial resolution of 36 km.

Surface Data

Hourly observed surface data for 2001, 2002, and 2003 were also obtained from the WRAP internet site. In accordance with t he Montana BART protocol, National Weather Service (NWS) hourly surface data for 39 st ations for 2001 and 36 stations for 2002 and 2003 were processed in CALMET. The data file s were provided in the SMERGE format and were ready for input into CALMET.

Surface data from the follo wing locations were used for the CALMET analysis:

• Badger Peak, MT (2001 only)

• Billings, MT

• Bismarck, ND

• Boise, ID

• Bozeman, MT

• Butte, MT

• Casper, WY

• Coeur d’Alene, ID

• Cut Bank, MT

• Dickinson, ND

• Dillon, MT

• Estevan, SK

• Havre, MT

• Kalispell, MT

• Garfield Peak, MT (2001 only)

• Glacier National Park, MT

• Glasgow, MT

• Great Falls, MT

• Helena, MT

• Havre, MT

• Lander, WY

• Lewistown, MT

• Livingston, MT

• Medicine Hat, AB

• Miles City, MT

• Minot, ND

• Missoula, MT

• Morningstar, MT (2001 only)

• Peabody Coal, MT

• Pocatello, ID

• Rapid City, SDHolcim BART Analysis pg. B-5 Appendix B • Rexburg, ID

• Riverton, WY

• Salmon, ID

• Sheridan, WY

• Spokane, WA

• Spring Creek Coal, MT

• Theodore Roosevelt National Park, ND

• Williston, ND

• Yellowstone National Park, WY

Upper Air Data

The Montana Protocol included the use of upper air data; however, the EPA Protocol specified that upper air data would not be used, and consequently the WRAP modeling omitted this data. Bison followed the Montana modeling protocol and included the upper air station data in the BART modeling analysis.

Upper air rawinsonde data collected by sev en NWS stations were obtained from the rawinsonde data repository maintained by NOAA at http://raob.fsl.noaa.gov/. The data were obtained in the standard FSL data forma t for use in the CALMET system. The seven NWS upper air rawinsonde locati ons used for this project are:

• Bismarck, ND

• Boise, ID

• Glasgow, MT

• Great Falls, MT

• Rapid City, SD

• Riverton, WY

• Spokane, WA

Upper air data substitution and extrapolation were accomplished as needed according to ASG’s FAQ 2.3.4, which re commends temporal substitution (for example, substituting an afternoon sounding with the previous or succeeding afternoon so unding) or spatial substitution from a nearby location if s oundings are missing. For in-sounding values flagged by READ62, the data values were corrected using an in-house computer program (Fix6201.exe) developed for this pur pose. Nearly all of these flagged values were due to either (1) the pressure remaini ng constant or rising with height, or (2) the elevation remaining constant or decreasing with height. These were corrected by the inhouse program by changing the flagged values by a small amount so that the pressure decreased with height or the el evation increased with height as appropriate. For spatial substitutions, another in-house program (A djUa.exe) was used to adjust for the difference in elevation between the two lo cations. Temporal substitutions were accomplished manually using a text edit or. All raw and proce ssed data and data processing algorithms ar e available upon request.Holcim BART Analysis pg. B-6 Appendix B Precipitation Data

The use of precipitation data was refe renced in the Montana and EPA Modeling Protocols. The WRAP modelin g omitted this precipitation data. Bison followed the modeling protocols and includ ed the precipitation station data in the BART modeling analysis.

Hourly precipitation data in NCDC’s TD-3240 format were obtained from the data set developed by MDEQ for their BA RT modeling analysis effort. All precipitation stations located within the CALMET mo deling domain were extracted from the data set and were used in the CALMET analysis. A total of 286 stat ions were selected for each of the three modeled years. A complete list of precipitation stations is included as an attachment to this report.

No precipitation data inter polation or substitution was required for this project.



### 1.5 Ozone

The ozone data provided on the WRAP websit e contained all the ozone sites in the United States and for the y ear 2002 the number of ozone sites exceeded the number of stations allowed in the CALPUFF model. Bison obtained ozone data for the following three ozone stations in the modeling domain:

• Yellowstone National Park

• Glacier National Park

• Theodore Roosevelt National Park



### 1.6 CALPUFF

CALPUFF applies mathematical algorithms to calculate po llutant concentrations at Class I receptors. CALPUFF r equires CALMET output files, source emissions, and receptor grids to model Class I impacts.

1.6.1 

### CALPUFF Parameters

CALPUFF was run in the refined mode using the MESOPUFF III chemical transformation scheme and dry and wet deposition calculations . Model settings were based on recommendations found in the M ontana BART protocol. The table below summarizes the model control file settings used for this analysis. Complete CALPUFF input files will be provided upon request.Holcim BART Analysis pg. B-7 Appendix B 

### CALPUFF Model Control File Settings
Model Parameter/Option Value Number of chemical species 9 Number of chemical species emitted 7 Vertical distribution near field Gaussian Terrain adjustment method Partial plume path adjustment Subgrid-scale complex terrain Not modeled Slug model Not used Transitional plume rise Yes Stack tip downwash Yes Vertical wind shear Yes Puff splitting Yes Chemical mechanism MESOPUFF II scheme Wet removal Yes Dry deposition Yes Dispersion coefficient method PG disp ersion coefficients for rural areas Partial plume penetration – elevated inversion Yes PDF used under convective conditions No CSPEC SO 2 , SO 4 , NO X , HNO 3 , NO 3 , SOA, EC, PMC, PMF Chemical parameters – dry gas deposition Default Size parameters – dry particle deposition Default Reference cuticle resistance (RCUTR) 30 s/cm Reference ground resistance (RGR) 10 s/cm Reference pollutant reactivity (REACTR) 8 Number of particle-size intervals (NINT) 9 Vegetation state in un-irrigated areas (IVEG) 1 Wet deposition parameters Default Ozone data input option 0 Background ozone concentration Ozo ne data: Yellowstone NP, Glacier NP, Theodore Roosevelt NP Background ammonia concentration (values specific to each Class I area analyzed) 1.22, 1.23, 1.6, 1.94, 2.29, 1.63, 1.65, 1.69, 0.98, 1.04, 1.37, 1.06 ppb SYTDEP 550 m MHFTSZ 0 JSUP 5 XSAMLEN 1.0 grid units MXNEW 99 MXSAM 99 Maximum mixing height 3,000 m Minimum mixing height 50 m NSPLIT 2 IRESPLIT Hour 17-22 = 1 ZISPLIT 100 m ROLDMAX 0.25
Notes: ppb = parts per billion s/cm = seconds per centimeterHolcim BART Analysis pg. B-8 Appendix B 1.6.2 

### Receptors

The Air Resources Division (ARD) of the Na tional Park Service (NPS) has developed a database of modeling receptors for all federal Class I areas in the United States. ARD has also developed a file conversion program to convert the data from latitude/longitude to either Lambert Conformal or UTM coordi nates. Receptor grids for each federally mandated Class I area of concern were devel oped using the ARD dat a files converted to the appropriate LCC coordinate system.

1.6.3 

### Modeled Sources - General

The visibility analyses includ ed potential emissions for the Holcim BART-eligible sources and the projected emi ssion reductions for the applicable pollutant controls. The BART-eligible sources that were included in the analysis are:

• Cement Kiln

• Clinker Cooler

1.6.4 

### Modeled Sources - Physical Parameters

The physical parameters for each of the sources included in the models remained consistent with WRAP model inputs.

1.6.5 

### Modeled Sources – Baseline Emission Rates

Class I visibility impacts dem onstrations were performed using the maximum actual emission rates for each modeled eligible source. These emission rates were obtained from Holcim’s current air permits. The follo wing table provides the emission rates used to demonstrate the BART im pacts for regional haze:



### Baseline Modeled Emission Rates

Source ID NOx (lb/hr) SO 2 (lb/hr) PM 10 (lb/hr)

Kiln 1568 340 37.36

Clinker Cooler - - 45.82

To accurately demonstrate the changes in visibility impacts at surrounding mandatory Class I areas, potential kiln and c linker cooler emissions of NO x , SO 2 , and PM 10 emission rates were entered into the CALPUFF models to establish a baseline case for comparison. The current permit limits NO x emissions from the kiln to 1568 lb/hr on an hourly average basis. SO 2 permit limits are 124 lb/hr on a 30-day rolling average; however, the 340 lb/hr highest rate was used in the modeling to be consistent with the WRAP model inputs. The potent ial hourly kiln filterable PM 10 emissions of 37.36 lb/hr are based on the permit limit of 0.77 lb/ton of clinker and t he annual clinker productionHolcim BART Analysis pg. B-9 Appendix B limit of 425,000 tons of clinker per y ear. The clinker cooler filterable PM 10 emissions of 45.82 lb/hr are limited by the process weight rule (E=55.0*P^0. 11-40) and 500,000 tons of clinker per year.

Including particulate matter emi ssions in the model is not as straightforward as including SO 2 or NO x emissions. Particulate matter can be pres ent in different forms, or species, and each species can affect visibility to a different degree. The NPS has provided several spreadsheet templates that speciate PM 10 emissions resulting from various combustion sources. 2 These spreadsheets allow ge neralized specia tion of the PM 10 for a specific source and as such do not necessa rily accurately reflect potential speciated emissions. WRAP did not document the speciation of PM 10 used in the initial BART determination model. Theref ore, Bison relied on the NPS speciation templates.

The following analysis was conduct ed to develop a source-specific PM 10 speciation for visibility impacts modeling. First, t he following general distribution of PM 10 species was generated using an NPS spreadsheet for dry- bottom PC-fired boilers with flue gas desulfurization and fabric filter baghouse emissions controls.



### Guideline PM 10 

### Speciation

Species NPS Kiln Distribution NPS Clinker Cooler

Distribution Coarse (PMC) (a) 19.6% 39.6% Fine Soil (PMF) (b) 57.4% 42.4% Fine Elemental Carbon (EC) 2.2% 1.6% CPM IOR (SO 4 ) (c) 18.3% 14.4% CPM OR (SOA) (d) 2.5% 2.0% Total: 100.0% 100.0% (a) PMC = Particulate Matter, Coar se (filterable PM > 2.5 microns and ≤ 10 microns) (b) PMF = Particulate Matter, Fine (filterable PM ≤ 2.5 microns) (c) IOR = Inorganic (d) CPM = Condensable Particulate Matter; OR = Organic; SOA = Secondary Organic Aerosols

Applying these percent ages to the maximum PM 10 emission rate of 31.3 lb/hr, less estimated H 2 SO 4 emissions, and adding back the estimated SO 4 emission rate yields the following particulate species distribution.

2 See web address: http://www2.natur e.nps.gov/air/Permits/ect/index.cfmHolcim BART Analysis pg. B-10 Appendix B 

### Final PM 10 

### Speciation

Species Kiln Modeled PM 10 Speciation (lb/hr) Clinker Cooler Modeled PM 10 Speciation (lb/hr) Coarse (PMC) 9.2 21.7 Fine Soil (PMF) 27.1 23.2 Fine EC 1.0 0.9 CPM IOR (SO 4 ) 8.6 7.9 CPM OR (SOA) 1.2 1.1 Total: 47.2 54.8

1.6.6 

### Modeled Sources – BART Co ntolled Emission Rates

The BART modeling analysis required that the baseline emissions be adjusted to reflect the predicted emission reductions for each pollutant. The following table shows the proposed emissions used in this second step in the BART modeling analysis.



### BART Controlled Modeled Emission Rates

Source ID NOx (lb/hr) Percent NOx Reduction SO 2 (lb/hr) Percent SO 2 Reduction PM 10 (lb/hr) Percent PM 10 Reduction

Kiln 784 50% 340 0% 37.36 0%

Clinker Cooler - - - 45.82 0%



### 1.7 CALPOST

Data generated by CALPUFF was entered into the CALPOST program to summarize peak Class I visibility impacts as required. For the visibility analysis, CALPOST used modeled sulfate, nitrate, and PM 10 concentration data to dete rmine the light-absorbing and light-scattering effects resulting from the project’s emissions. The method recommended and used for calculating light extinction was “Method 6: Compute extinction from speciated particulate matte r measurements.” The ba ckground extinction coefficients were calculated based on the annual relative humidity factors and data presented in Section 6.1 and Appendices C and D of t he Montana BART Protocol. Inputs to CALPOST for visibilit y processing are summarized in the following table. The attached CD-ROM contains t he CALPOST input files.Holcim BART Analysis pg. B-11 Appendix B 

### CALPOST Visibility Control File Settings
CALPOST Parameter/Option Value Maximum relative humidity (RHMAX) 95% Included species Sulfate, nitrate, coarse particulate (as PM 10 ), and fine particulate (as PM 2.5 ) Coarse particulate extinction efficiency 0.6 (l/Mm per μg/m 3 ) Fine particulate extinction efficiency 1.0 (l/Mm per μg/m 3 ) Ammonium sulfate extinction efficiency 3.0 (l/Mm per μg/m 3 ) Ammonium nitrate extinction efficiency 3.0 (l/Mm per μg/m 3 ) Organic carbon extinction efficiency 4.0 (l/Mm per μg/m 3 ) Soil extinction efficiency 1.0 (l/Mm per μg/m 3 ) Elemental carbon extinction efficiency 10.0 (l/Mm per μg/m 3 ) Method used for background light extinction MVISBK = 6
Relative humidity From *.VIS Files Background extinction coefficients, SO 4 0.120 Background extinction coefficients, NO 3 0.100 Background extinction coefficients, PMC 3.006 Background extinction coefficients, OC 0.471 Background extinction coefficients, soil 0.501 Background extinction coefficients, EC 0.2 Extinction due to Rayleigh scattering 10.0
Notes: NO 3 = Nitrate



### 1.8 Modeling Results

1.8.1 

### Regional Haze (Visibility)

Impacts to natural background visibility, expressed in te rms of percentage change in 24-hour average background extinction ( Δ B ex ) were calculated by CALPOST. The guidelines also reference 40 CFR §51.301(a) in asserting t hat determinations must be made on a “...case-by-case basis taking into account the geographic extent, intensity, duration, frequency and time of visibility impairments....” The 98 th percentile impact results are summarized in the following table.Holcim BART Analysis pg. B-12 Appendix B 

### Summary of BART Selections and Visibility Impacts

Gates of the Mountains

Pollutant Control Technology Approximate Control Efficiency Emission Rate (lb/hour) Modeled Deciviews Modeled Deciview Improvement (above baseline) % Improvement

in Visibility (from baseline)

SO 2 No Additional Controls 0% 340 1.56 0.00 0%

Process Alterations (install fixed inlet on clinker cooler) 3% 1,521 1.49 0.04 3%

Low-NOx Burner 17% 1,301 1.32 0.21 14% NOx

Total NOx Improvement: 20% 1,254 1.28 0.24 17%

PM 10 No Additional Controls 0% 23 1.56 0.00 0%