1 

BART Five-Factor Analysis for Holcim (US) Inc., 

Trident Portland Cement Plant, Three Forks, MT 

US EPA Region 8 Air Program 

March 20, 2012

Executive Summary

This five factor analysis documents the basis for determination of the Best Available Retrofit 

Technology (BART) for control of Sulfur Dioxide (SO2) and Nitrogen Dioxide (NO2) emissions 

at the Holcim (US) Inc., Trident facility which manufactures Portland cement. The facility is 

located approximately five miles northeast of Three Forks, near the headwaters of the Missouri 

River. The plant is located in Section 9, Township 2 North, Range 2 East in Gallatin County, 

Montana, with approximate UTM coordinates of the facility of Zone 12, Easting 464 km, and 

Northing 5,088 km. The site elevation is approximately 4,200 feet above sea level. 

This analysis is based on the following submittals by Holcim: 

→ BART analysis by Holcim for Trident Cement Plant, Three Forks, MT, July 6, 2007. 

(“Holcim Initial Response”) 

→ Responses to EPA comments on BART analysis for Trident Cement Plant, January 25, 

2008. (“Holcim 2008 Responses”) 

→ BART analysis by Holcim for low-NOx burners for Trident Cement Plant, June 9, 2009. 

(“Holcim Additional Response, June 2009”) 

→ Response to EPA letter regarding Confidential Business Information (CBI) claims on 

BART analysis for Trident Cement Plant, August 12, 2009. (“Holcim Additional 

Response, August 2009”) 

→ Response to EPA request for NOx and SO2 emissions data for 2008-2011, June 16, 2011. 

(“Holcim 2011 Response”) 

→ Response to EPA request for emissions and clinker production, pursuant to CAA section 

114(a), March 2, 2012. (“Holcim 2012 Response”) 

Holcim currently employs a “wet kiln” to produce Portland cement. The U.S. Environmental 

Protection Agency (EPA) Region 8 identified this facility as Best Available Retrofit Technology 

(BART) source based on modeling that showed the facility has a 98th percentile of the visibility 

impacts greater than 0.5 ∆dv (deciview) of natural background for one of the class I areas. 

Although Holcim listed 12 emission units selected for BART analysis due to their significant 

emission rates, many of these are Particulate Matter (PM) emission sources. The kiln is the only 

SO2 and NOx emitting unit subject to BART analysis. Therefore, this analysis focuses primarily 
2 

on the kiln as a source of SO2 and NOx emissions and their control to improve visibility 

impairment attributable to Holcim’s Trident facility at Three Forks, MT. 

The kiln currently does not employ any specified control technology other than inherent 

scrubbing and use of low sulfur coal as a component of the fuel mix for SO2 control and good 

combustion practices for NOx control. The kiln is also permitted with a maximum production 

limit of 425,000 tons of clinker during any rolling 12-month period, under Montana Operating 

Permit #0982-10. 

In its March 2, 2012 response to EPA’s request for emissions and clinker production pursuant to 

CAA section 114(a), Holcim listed the NOx emissions at 998 tons for 2009, 1,175 tons for 2010, 

and 1,164 tons for 2011. The average was 1,112 tons. In the same response, Holcim listed the 

SO2 emissions at 53.9 tons for 2009, 64.1 tons for 2010, and 33.1 tons for 2011. The average 

was 50.2 tons. EPA has used 1,112 tons/yr of NOx and 50.2 tons/yr of SO2 as the baseline 

emissions for this BART analysis. 

EPA conducted a five step analysis, with step four incorporating the five factor analysis, in 

accordance with BART guidelines,1 by doing the following: 

Step 1 -- Identify all available technologies 

Step 2 -- Eliminate technically infeasible options 

Step 3 -- Evaluate control effectiveness of remaining control technology 

Step 4 -- Evaluate impact on emissions and document the results 

Factor 1: Costs of compliance 

Factor 2: Energy and non air quality impacts 

Factor 3: Any existing pollution control technology in use at the source 

Factor 4: Remaining useful life 

Factor 5: Evaluate visibility impacts

Step 5 – Select BART 

Based on the above outlined five step process, Holcim proposed no new requirement for 

reduction of SO2 and Low NOx Burners (LNB) for reduction of NOx emissions from the kiln as 

BART. EPA followed the same five step process and proposes no additional control for SO2 

control and Selective Non-Catalytic Reduction (SNCR) with LNB for NOx control. 

I. Nitrogen Oxide

Step 1: Identify All Available Technologies 

EPA has identified the following control technologies as being available for reducing NOx

emissions from Holcim’s Trident cement kiln: 

1. Selective Catalytic Reduction (SCR) 

2. Selective Non-Catalytic Reduction (SNCR) with Low NOx Burners (LNB) 

3. Selective Non-Catalytic Reduction (SNCR) 

 

1

 July 6, 2005 BART guidelines, 40 CFR 51, Regional Haze Regulations and Guidelines for Best Available Refit 

Technology (BART) Determinations. 
3 

4. Low-NOx Burners (LNB) 

5. Mid-Kiln Fuel (MKF) Injection of Scrap Tires 

6. Flue Gas Recirculation (FGR) 

These technologies are listed from the most to the least effective, based on potential for 

emissions reduction from current baseline emissions. 

Low-NOx Burners

LNBs use stepwise or staged combustion and localized exhaust gas recirculation (i.e., at the 

flame). Staging of combustion air as achieved by such burners is an available control technology 

for NOx reduction in cement kilns. In the first stage, fuel combustion is carried out in a high 

temperature fuel-rich environment and the combustion is completed in the fuel-lean low 

temperature second stage. By controlling the available oxygen and temperature, LNBs attempt 

to reduce NOx formation in the flame zone. LNBs have been used by the cement industry for 

nearly 30 years and are designed to reduce flame turbulence, delay fuel/air mixing, and establish 

fuel-rich zones for initial combustion. LNBs can be used in combination with SNCR to achieve 

even greater emissions reduction. 

Mid-Kiln Injection

MKF is a form of secondary combustion where a portion of the fuel is fired in a location other 

than the burning zone. A common fuel used for mid kiln firing is scrap tires (tire-derived fuel, or 

TDF). By adding fuel mid-kiln, MKF changes both the flame temperature and the flame length. 

This reduces thermal NOx formation by burning part of the fuel at a lower temperature by 

creating reducing conditions at the mid-kiln fuel injection point which may destroy some of the 

NOx formed upstream in the kiln burning zone. In addition, the entrained secondary fuel acts to 

reduce the temperature of the primary combustion products. TDF combustion also lowers the 

amount of fuel-bound nitrogen introduced to the kiln and thereby lowers NOx emissions through 

another mechanism. 

Flue Gas Recirculation

 

FGR involves the use of oxygen-deficient flue gas from some point in the process as a substitute 

for primary air in the main burner pipe in the rotary kiln. FGR lowers the peak flame 

temperature and develops localized reducing conditions in the burning zone by reducing the 

oxygen content of the primary combustion air. The intended effect is to decrease both thermal 

and fuel NOx formation in the rotary kiln. 

Selective Non-Catalytic Reduction

In SNCR systems, a reagent such as ammonia (NH3) or urea is injected into the flue gas at a 

suitable temperature zone, typically in the range of 1,600 to 2,000°F and at an appropriate ratio 

of reagent to NOx. SNCR system performance depends on temperature, residence time, 

turbulence, oxygen content, and other factors specific to the given gas stream. SNCR can be 

used in combination with LNBs to achieve even greater emissions control. 

 
4 

Selective Catalytic Reduction

 

SCR uses either ammonia (NH3) or urea in the presence of a metal based catalyst to selectively 

reduce NOx emissions. SCR is used in the electric utility industry to reduce NOx emissions from 

boilers and has been used on three cement kilns in Europe. SCR is capable of reducing NOx

emissions by about 80%. 

Step 2: Eliminate Technically Infeasible Options

FGR is used in the electric utility industry, but is not transferrable to cement kilns. For cement 

kilns, a hot flame is required to complete the chemical reactions that form the clinker minerals 

from the raw materials. The long/lazy flame that would be produced by FGR would result in the 

production of unacceptable quality clinker. Clinkering reactions must take place in an oxidizing 

atmosphere in the burning zone to generate clinker that can be used to produce acceptable 

cement. FGR would tend to produce localized or general reducing conditions that also could 

detrimentally affect clinker quality. Adding FGR to a burner that is already designed for 

optimum flame shaping and control would distort the thermal profile of the kiln, such that 

product quality would be unacceptably compromised.2

 For these reasons, FGR was not 

considered further. 

SCR has been used on three kilns in Europe; two are preheater kilns, and one kiln is a Polysius 

Lepol technology kiln, which is a traveling grate preheater kiln. 73 FR 34079 (June 16, 2008). 

Although we find that SCR is technically feasible for cement kilns, we have not analyzed it 

further because of the uncertainty regarding control effectiveness and costs. We note that EPA 

has acknowledged, in the context of establishing the NSPS for Portland Cement Plants, 

substantial uncertainty regarding the control effectiveness and costs associated with the use of 

SCR at such plants. See 75 FR 54995 (September 9, 2010). SCR for cement kilns will be reevaluated in subsequent reasonable progress (RP) planning periods. 

Step 3: Evaluate Control Effectiveness of Remaining Control Technology

For LNB on Holcim’s kiln, it is appropriate to assume a control effectiveness of 15%.3

 For 

MKF, a control effectiveness of 30% is appropriate.4

 For SNCR, in evaluating the technology, a 

control effectiveness of 50% is appropriate, and for LNB+SNCR a control effectiveness of 58% 

is appropriate. EPA calculated 58% reduction based on 15% reduction by LNB and 50% 

reduction of the remaining NOx emissions by SNCR, using the formula below: 

[1 - (1 - 0.15)(1 - 0.50)] x 100 = 57.5% (rounded to 58%) 

The following discussion is an explanation of why EPA considers 50% control effectiveness an 

appropriate estimate for SNCR at long wet kilns, such as Holcim’s Trident kiln. Ash Grove 

Cement has used SNCR at similar wet kilns in Midlothian, TX. Emissions data submitted by 

 

2

 Holcim Initial Response, p. 4-19. 

3

 EPA provided an example of LNB on a long wet kiln with a control effectiveness of 14% in NOx Control 

Technologies for the Cement Industry, Final Report, September 2000, p. 61. 

4

 Holcim Initial Response, p. 4-16. 
5 

Ash Grove to the Texas Commission on Environmental Quality (TCEQ) show that Ash Grove 

was able to achieve emission rates in the range of 1.6 to 2.9 lb/ton of clinker from June through 

August 2008 when using SNCR.5

 The emissions reports submitted to the TCEQ indicate that 

Ash Grove had been using SNCR in 2007 on one of their kilns at Midlothian; however, since the 

report doesn’t specify the exact timeframe, EPA does not know whether the 2007 data can be 

compared to the June through August 2008 data. 

Because the emission report data submitted to the TCEQ for SNCR use in 2007 is from an 

unknown time, EPA used 2006 emission data from the same three months as the 2008 data – 

June through August to assess the performance of the SNCR.6 Table I-1 summarizes emission 

from the Midlothian kilns using the 2006 and 2008 data. 

Table I-1 

 NOx Emissions for 2006 and 2008 for Ash Grove Cement, Midlothian, TX 

June through August 2006 

Emission Rate (lb/ton clinker) 

June through August 2008 

Emission Rate (lb/ton clinker) 

Percentage 

Reduction 

June July August Average June July August Average (%) 

Kiln 1 5.2 5.0 4.5 4.9 1.7 1.6 2.2 1.8 62.5 

Kiln 2 5.0 4.1 3.9 4.4 2.7 2.6 2.8 2.7 37.7 

Kiln 3 5.0 4.4 4.2 4.5 2.9 2.6 2.5 2.7 40.5 

When the control effectiveness (percent reduction) on all three kilns are averaged together, a 

47.5% reduction was achieved. This is within the range of control effectiveness values that have 

been demonstrated at other kilns.7

,

8

,

9

Concentration of baseline NOx emissions is one parameter affecting control effectiveness. The 

percentage of control effectiveness is greater when initial NOx concentrations are greater. The 

reaction kinetics decrease as the concentration of reactants decreases. This is due to thermo-

 

5

 See the document received from TCEQ available in the docket: Ash Grove Texas, L.P. – Midlothian Plant 2008 

Actual Emission Rate Calculations – Kilns, Ash Grove Texas, L.P. – Midlothian Plant 2008 Actual Emission Rate 

calculations – Input Data. 

6

 See the documents received from TCEQ available in the docket: Ash Grove Texas, L.P. – Midlothian Plant 2006 

Actual Emission Rate Calculations – Kilns; Ash Grove Texas, L.P. – Midlothian Plant 2006 Actual Emission Rate 

Calculations – Input Data; Ash Grove Texas, L.P. – Midlothian Plant 2008 Actual Emission Rate Calculations – 

Kilns, Ash Grove Texas, L.P. – Midlothian Plant 2008 Actual Emission Rate calculations – Input Data. 

7

 EPA has stated previously that, “[o]n average, SNCR achieves approximately a 35 percent reduction in NOX at a 

ratio of NH3-to-NOX of about 0.5 and a reduction of 63 percent at an NH3-to-NOX ratio of 1.0” in the Federal 

Register notice proposing New Source Performance Standards for Portland cement plants. 73 FR 34078 (June 

16, 2008). 

8

 The Cadence brochures available at: http://cadencerecycling.com/sncr.html and 

http://www.cadencerecycling.com/Resources/6-PageComplete.pdf state that control efficiencies of up to 50% 

can be achieved on long wet kilns. See also Enhancing SNCR Performance by Induced Mixing, Eric Hansen and 

Fred Lockwood, December 2006 available at http://www.cadencerecycling.com/Resources/ICRFormatted2006.pdf. 

9

 EPA has stated that, “there are numerous examples of SNCR systems achieving emission reductions greater than 

50 percent and as high as 80 percent or more” in the Federal Register notice proposing New Source Performance 

Standards for Portland cement plants. 73 FR 34079 (June 16, 2008). 
6 

dynamic considerations that limit the reduction process at low NOx concentrations.10 The 

baseline NOx emissions of the Holcim Trident kiln, in pounds per ton of clinker produced (lb/ton 

clinker) are significantly higher than those at Ash Grove’s Midlothian kilns in Texas, indicating 

that SNCR on the Holcim kiln would be expected to achieve even greater control effectiveness 

when compared to SNCR on the Midlothian kilns. Information provided to EPA by Holcim on 

NOx emissions at the Trident cement plant from 2008 through 2011 indicate that the mean 30-

day rolling average emission rate was 9.7 lb/ton clinker,11 much higher than Midlothian’s preSNCR emission rate, which is between 4.5 and 4.9 lb/ton clinker. A summary of the emissions 

projections for the NOx control options is provided in Table I-2. 

Table I-2 

Summary of NOx BART Analysis Control Technologies for Holcim 

Control 

Option 

Control 

Effectiveness 

(%) 

Emissions 

Reduction 

(tpy) 

Remaining 

Emissions 

 (tpy) 

LNB+SNCR 58 645 467 

SNCR 50 556 556 

MKF 30 334 778 

LNB 15 167 945 

No Controls 

(Baseline) 0 0 1,112 1

1

 Holcim 2012 Response. (Holcim lists NOx emissions at 998 tons for 2009, 

 1,175 tons for 2010, and 1,164 tons for 2011. The average is 1,112 tons.) 

Step 4: Evaluate Impact on Emissions and Document the Results

Factor 1 – Costs of Compliance

LNB

On June 9, 2009, Holcim submitted a revision and replacement of their 2007 cost analysis for 

LNB. In the revised analysis, Holcim calculated the capital cost at $4,958,209 and the total 

annual cost at $846,061, both in 2006 dollars. EPA relied on the cost estimates supplied by 

Holcim for capital costs and annual costs,12 but with two exceptions. EPA used a capital cost 

estimate of $4,385,307.13 Also, EPA used a Capital Recovery Factor (CRF) consistent with 20 

years for the useful life of the kiln. EPA has determined that the default 20-year amortization 

period is most appropriate to use as the remaining useful life of the facility. Without 

commitments for an early shut down, EPA cannot consider a shorter amortization period in its 

 

10 EPA-OAQPS Control Cost Manual, p. 1-10. 

11 Holcim 2012 Response. (Holcim lists the mean 30-day rolling average NOx

 emission rate for 2008-2011 at 9.7 

lb/ton clinker.) 

12 Holcim Additional Response, June 2009. 

13 Holcim applied a 1.5 multiplier to the direct installation costs, for “retrofit installation.” EPA did not. 
7 

analysis. In order to calculate the annualized capital cost, EPA multiplied the capital cost by the 

CRF. 14

The capital cost estimate of $4,385,307 includes the cost of converting from a direct to an 

indirect firing system to accommodate LNB, including installation of a baghouse, additional 

explosion prevention, pulverized coal storage, and dosing equipment.15 By comparison, the LNB 

cost analysis by Ash Grove Cement for BART contains a capital cost estimate of $266,309 and 

total annual cost estimate of $158,630.16 These figures are much lower than the estimate for 

Holcim because Ash Grove did not factor in the cost of any kiln modifications to convert from 

direct to indirect firing. 

The annual O&M cost of $300,657 listed below for LNB is the total of all direct and indirect 

annual costs listed by Holcim, excluding the annual cost of capital. EPA calculated the average 

cost effectiveness from the total annual cost and a 15% reduction from the baseline actual 

emissions. Costs are presented in Table I-3 below. 

TABLE I-3

Cost Analysis for LNB 

Capital 

Cost ($) 

Annual Cost 

of Capital 

(CRF=0.0944) 

Annual 

O&M 

Cost ($) 

Total 

Annualized 

Cost ($) 

Baseline 

Actual 

Emissions, 

Tons/Year 

Control 

Efficiency 

Tons per 

Year 

Reduced 

 Average Cost 

Effectiveness, 

$/Ton Reduced 

4,385,307 413,972 300,657 714,629 1,112 15% 167 4,279 

MKF

EPA relied on cost estimates supplied by Holcim for annual costs.17 No separate calculation of 

capital cost was presented by Holcim, as this has been included in the annual cost. Total annual 

cost of MKF was provided from an EPA publication,18 for MKF conversion for a 50 tons-perhour long wet kiln, scaled up by Holcim from 1997 dollars to 2006 dollars, using a 1.25607 

Consumer Price Index (CPI) multiplier.19 EPA calculated the cost effectiveness from the total 

annual cost and a 30% reduction from the baseline actual emissions. Costs are presented in 

Table I-4. 

As explained in Holcim’s BART analysis, the use of tire-derived fuel for MKF cannot be 

ensured within the five-year timeline required in the BART program. Holcim is not permitted by 

 

14 CRF is 0.0944 and is based on a 7% interest rate and 20 year equipment life. Office of Management and Budget, 

Circular A-4, Regulatory Analysis, http://www.whitehouse.gov/omb/circulars_a004_a-4/. 

15 Holcim Additional Response, June 2009. 

16 BART submittal by Ash Grove Cement, January 23, 2009. 

17 Holcim Initial Response, p. 4-25. 

18 NOx

 Control Technologies for the Cement Industry: Final Report, September 19, 2000, EPA-457/R-00-002, Table 

6-10, estimated an annual cost of $370,000 in 1997 dollars, for MKF at a 50-ton-per-hour long wet kiln. 

19 Holcim Initial Response, p. 4-23. 
8 

the State of Montana to use tires as a fuel source in its kiln until the State issues a final air quality 

permit allowing such use and any legal appeals are concluded.20

TABLE I-4 

 Cost Analysis for MKF 

Capital Cost ($) 

Annual Cost 

of Capital 

(CRF=0.0944) 

Annual 

O&M 

Cost ($) 

Total 

Annualized Cost 

($) 

Baseline 

Actual 

Emissions. 

Tons/Year 

Control 

Efficiency 

Tons per 

Year 

Reduced 

 Average Cost 

Effectiveness, 

$/Ton Reduced 

Not calculated 

separately, but 

included in total 

annualized cost 

N/A N/A 473,738 1,112 30% 334 1,418 

SNCR

EPA relied on cost estimates supplied by Holcim for capital costs and annual costs, with the 

exception of the CRF used.21 EPA used a CRF consistent with 20 years for the useful life of the 

kiln. EPA has determined that the default 20-year amortization period is most appropriate to use 

as the remaining useful life of the facility. Without commitments for an early shut down, EPA 

cannot consider a shorter amortization period in its analysis. In order to calculate the annualized 

capital cost, EPA multiplied the capital cost by the CRF. 22

EPA analyzed only for commercial SNCR. In its January 25, 2008 submittal to EPA, Holcim 

discussed (at pages 11-12) an alternative form of SNCR, which Holcim refers to as “dust scoops” 

SNCR. This version of SNCR would use a solid pelletized form of urea, which could be 

mechanically introduced into the existing “dust scoops” mechanism. In its August 12, 2009 

submittal to EPA, Holcim presented cost spreadsheets which estimated substantially less cost for 

“dust scoops” SNCR than for commercial SNCR ($716,800 capital cost versus $1,312,800 

capital cost). However, Holcim’s 2008 submittal indicated that neither type of SNCR was being 

considered by Holcim on anything more than a trial basis. Therefore, EPA has chosen to use the 

commercial SNCR cost estimate in its analysis, rather than the “dust scoops” SNCR cost 

estimate. 

The annual O&M cost listed below for commercial SNCR of $147,288 is adopted from Holcim’s 

August 12, 2009 submittal, as the total of all direct and indirect annual costs, excluding the 

annual cost of capital. 

EPA calculated the average cost effectiveness from the total annual cost and a 50% reduction 

from the baseline actual emissions. Costs are presented in Table I-5. 

 

20 Id., p. 4-25. 

21 Holcim Additional Response, August 2009, Appendix C. 

22 CRF is 0.0944 and is based on a 7% interest rate and 20 year equipment life. Office of Management and Budget, 

Circular A-4, Regulatory Analysis, http://www.whitehouse.gov/omb/circulars_a004_a-4/. 
9 

TABLE I-5 

 Cost Analysis for Commercial SNCR 

Capital 

Cost ($) 

Annual Cost 

of Capital 

(CRF=0.0944) 

Annual 

O&M 

Cost($) 

Total 

Annualized 

Cost ($) 

Baseline 

Actual 

Emissions, 

Tons/Year 

Control 

Efficiency 

Tons per 

Year 

Reduced 

 Average Cost 

Effectiveness, 

$/Ton Reduced 

1,312,800 123,928 147,288 271,216 1,112 50% 556 488 

 LNB + SNCR

EPA calculated the cost effectiveness of LNB + SNCR by dividing the sum of the annual cost of 

the two technologies described above ($714,629 plus $271,216) by the 58% emissions reduction 

from baseline actual emissions that would be achieved. Costs are presented in Table I-6. 

TABLE I-6 

 Cost Analysis for LNB + SNCR 

Capital 

Cost ($) 

Annual Cost 

of Capital 

(CRF=0.0944) 

Annual 

O&M 

Cost ($) 

Total 

Annualized 

Cost ($) 

Baseline 

Actual 

Emissions. 

Tons/Year 

Control 

Efficiency 

Tons per 

Year 

Reduced 

 Average Cost 

Effectiveness, 

$/Ton Reduced 

5,698,107 537,900 447,946 985,845 1,112 58% 645 1,528 

 

Factor 2 -- Energy and Non Air Quality Impacts

LNBs are not expected to have any significant negative energy impacts23 and are not expected to 

have any non-air quality environmental impacts. SNCR systems require electricity to operate the 

blowers and pumps. The generation of the electricity will most likely involve fuel combustion, 

which will cause emissions. While the required electricity will result in emissions, these 

emissions should be small compared to the reduction in NOx that would be gained by operating 

an SNCR system.24 Transporting the chemical reagents for SNCR would use natural resources 

for fuel and would have associated air quality impacts. The chemical reagents would be stored 

on site and could result in spills to the environment while being transferred between storage 

vessels or if containers were to fail during storage or movement. The environmental impacts 

associated with proper transportation, storage, and/or disposal should not be significant. 

Therefore, the non-air quality environmental impacts did not warrant eliminating LNB or SNCR. 

Factor 3 -- Any existing pollution control technology in use at the source

Holcim currently uses proper kiln design and operation for NOx control.

 

23 Holcim Initial Response, p. 4-23. 

24 Holcim Initial Response, pp. 5-13, 14. 
10 

Factor 4 -- Remaining useful life

EPA has determined that the default 20-year amortization period is most appropriate to use as the 

remaining useful life of the facility. Without commitments for an early shut down, EPA cannot 

consider a shorter amortization period in our analysis. 

Factor 5 -- Evaluate visibility impacts

EPA conducted modeling for Holcim as described in section V.C.3.a. of the Federal Register

notice for the proposed regional haze FIP rule. Section V.C.3.a., titled “Visibility Improvement 

Modeling,” reads as follows: 

The fifth factor to consider under EPA’s BART Guidelines is the degree of visibility improvement 

from the BART control options. See 59 FR 39170 (August 1, 1994). The BART Guidelines

recommend using the CALPUFF air quality dispersion modeling system to estimate the visibility 

improvements of alternative control technologies at each Class I area, typically those within a 

300 km radius of the source, and to compare these to each other and to the impact of the 

baseline (i.e., current) source configuration. The CALPUFF modeling system is comprised of 

the CALMET data which is used to pre-process meteorological data; the CALPUFF model 

which is used to simulate the conversion of pollutant emissions to PM2.5 and the transport and 

fate of PM2.5; and the CALPOST processor which is used to calculate visibility impairments at 

receptors sites. 

The BART Guidelines recommend comparing visibility improvements between control options 

using the 98th percentile of 24-hour delta deciviews, which is equivalent to the facility’s 8th

highest visibility impact day. The 98th percentile is recommended rather than the maximum 

value to allow for uncertainty in the modeled impacts and to avoid undue influence from unusual 

meteorological conditions. The ‘‘delta’’ refers to the difference between total deciview impact 

from the facility plus natural background, and deciviews of natural background alone, so ‘‘delta 

deciviews’’ is the estimate of the facility’s impact relative to natural visibility conditions. 

Visibility is traditionally described in terms of visual range in kilometers or miles. However, the 

visual range scale does not correspond to how people perceive visibility because how a given 

increase in visual range is perceived depends on the starting visibility against which it is 

compared. Thus, an increase in visual range may be perceived to be a big improvement when 

starting visibility is poor, but a relatively small improvement when starting visibility is good. 

The “deciview” scale is designed to address this problem. It is linear with respect to perceived 

visibility changes over its entire range, and is analogous to the decibel scale for sound. This 

means that a given change in deciviews will be perceived as the same amount of visibility change 

regardless of the starting visibility. Lower deciview values represent better visibility and greater 

visual range, while increasing deciview values represent increasingly poor visibility. In the 

BART Guidelines, EPA determined that “a 1.0 deciview change or more from an individual 

source to would cause visibility impairment, and a change of 0.5 deciviews would contribute to 

impairment. Generally, 0.5 deciviews is equivalent to a 5% change in perceived visibility and is 

the amount of change that will evoke a just noticeable change in most landscapes.”25

 

 

25 BART Guidelines, 70 FR 39120 (July 6, 2005). 
11 

Converting a 5% change in light extinction to a change in deciviews yields a change of 

approximately 0.5 deciviews. 

Under the BART Guidelines, the improved visibility in deciviews from installing controls is 

determined by using the CALPUFF air quality model. CALPUFF, generally, simulates the 

transport and dispersion of emissions, and the conversion of SO2 to particulate sulfate and NOx 

to particulate nitrate, at a rate dependent on meteorological conditions and background ozone 

concentration. These concentrations are then converted to delta deciviews by the CALPOST 

post-processor. The CALPUFF modeling system is available and documented at EPA's Model 

Distribution webpage.26

The “delta deciviews” for control options estimated by the modeling represents a BART source’s 

impact on visibility at the Class I areas under different control scenarios. Each modeled day 

and location in the Class I area will have an associated delta deciviews for each control option. 

For each day, the model finds the maximum visibility impact of all locations (i.e., receptors) in 

the Class I area. From among these daily values, the BART Guidelines recommend use of the 

98th percentile, for comparing the base case and the effects of various controls. 

 

As part of the FIP development efforts, EPA determined that CALPUFF modeling was needed to 

evaluate emissions scenarios that would be consistent with the application of controls for 

Montana sources that were subject to BART.27 EPA contracted with the University of North 

Carolina and its subcontractor, Alpine Geophysics, to perform CALPUFF model simulations for 

BART sources in Montana. The University of North Carolina developed a modeling protocol 

that EPA approved. The protocol outlines the data sets, models and procedures that were used 

in the new CALPUFF modeling for BART sources.28 The evaluated Class I areas that were 

included in the modeling domain for each BART source are listed in Table 2 of the modeling 

protocol. The final report from this modeling effort is available in the docket.29 

The BART determination guidelines recommend that visibility impacts should be estimated in 

deciviews relative to natural background conditions. CALPOST uses background 

concentrations of various pollutants to calculate the natural background visibility impact. EPA 

used background concentrations from Table 2–1 of “Guidance for Estimating Natural Visibility 

Conditions Under the Regional Haze Rule.” Although the concentration for each pollutant is a 

single value for the year, this method allows for monthly variation in its visibility impact, which 

changes with relative humidity.

 

26 EPA's Model Distribution Webpage available at: http://www.epa.gov/ttn/scram/dispersion_prefrec.htm#calpuff. 

27 CALPUFF model simulations had previously been performed for some MT BART sources for certain emissions 

scenarios using meteorological data sets for the period 2001-2003 that were developed by the WRAP. 

“CALMET/CALPUFF Protocol for BART Exemption Screening Analysis for Class I Areas in the Western United

States”, available at http://pah.cert.ucr.edu/aqm/308/bart/WRAP_RMC_BART_Protocol_Aug15_2006.pdf 

 The WRAP data sets were developed in 2006 using the CALPUFF model versions and EPA guidance available at 

that time. 

28 “Modeling Protocol: Montana Regional Haze Federal Implementation Plan (FIP) Support”, University of North 

Carolina, Contract EP-D-07-102, November 14, 2011. 

29 Modeling Report: Montana Regional Haze Federal Implementation Plan (FIP) Support, March 16, 2012. 
12 

The following visibility impact analysis is for Holcim specifically: 

Table I-7 presents the visibility impacts of the 98th percentile of daily maxima for each Class I 

area from 2006 through 2008. 

Table I-8 presents the number of days with impacts greater than 0.5 deciviews for each Class 

area from 2006 through 2008.

TABLE I-7 

 Delta Deciview Improvement for NOx Controls on Holcim 

Class I Area 

Baseline 

Impact 

(Delta 

deciview) 

Improvement 

from LNB 

(Delta 

deciview) 

Improvement 

from SNCR 

(Delta deciview)

Improvement 

from LNB + 

SNCR 

(Delta 

deciview) 

Gates of the Mountains 

WA 

0.980 0.125 0.295 0.424

Yellowstone NP 0.411 0.051 0.120 0.171

TABLE I-8 

Days Greater than 0.5 Deciview for NOx Controls on Holcim (Three Year Total) 

Class I Area Baseline 

Days 

Using LNB Using SNCR Using LNB + 

SNCR 

Gates of the Mountains 

WA 

46 39 26 19

Yellowstone NP 13 7 4 3

Modeling was performed at 35% control effectiveness rather than 50% control effectiveness for 

SNCR and at 50% control effectiveness rather than 58% control effectiveness for LNB + SNCR. 

Therefore, visibility improvement from SNCR and LNB+SNCR would be greater than what is 

shown. 

Step 5 -- Select BART

EPA proposes to find that BART for NOx is LNB + SNCR with an emission limit of 5.5 lb/ton of 

clinker (30-day rolling average). Of the five BART factors, cost and visibility improvement 

were the critical ones in EPA’s analysis of controls for this source. 

 
13 

In its BART analysis for NOx at Holcim, EPA considered LNB, SNCR, and LNB + SNCR. The 

comparison between EPA’s LNB, SNCR, and LNB+SNCR analysis is provided in Table I-9. 

 

TABLE I-9 

Summary of NOx BART Analysis Comparison of Control Options for Holcim 

Control 

Option 

Total Capital 

Investment 

Total 

Annual 

Cost 

Average 

Cost 

Effectiveness 

($/ton) 

Incremental 

Cost 

Effectiveness 

($/ton) 

Visibility Impacts1,2

Visibility 

Improvement 

(delta 

deciviews) 

Fewer 

Days > 0.5 

deciview 

LNB+ 

SNCR 6,271,009 985,845 1,528 8,029 0.424 27 

SNCR 1,312,800 271,216 488 -1,140 3 0.295 20 

LNB 4,958,209 714,629 4,279 --

4

 0.125 7 

1 The visibility benefit shown is for Gates of the Mountains WA. 

2

 The visibility improvement described in this table represents the change in the maximum 98th percentile impact 

over the modeled 3-year meteorological period (2006 through 2008) at the Class I area that showed the greatest 

improvement, Gates of the Mountains, WA. Similarly, the number of days above 0.5 deciviews is the total for the 

modeled 3-year meteorological period at Gates of the Mountains WA. 

3The incremental cost effectiveness from LNB to SNCR is a negative number because the numerator in dollars is 

negative (i.e., the total annual cost of SNCR is less than LNB) but the denominator in tons is positive (i.e., SNCR 

achieves more tons of emission reduction than LNB).

4

Incremental cost and impact is not applicable to the option that has the lowest emission control effectiveness. 

EPA has concluded that LNB+SNCR is a cost effective control technology and would provide 

substantial visibility benefits. LNB+SNCR has a cost effectiveness value of $1,528 per ton of 

NOx emissions reduced. This is well within the range of values that EPA has considered 

reasonable for BART and that states have considered reasonable for BART. 

EPA has weighed costs against the anticipated visibility impacts for Holcim. Any of the control 

options would have a positive impact on visibility. As compared to LNB alone, LNB + SNCR 

would provide an additional visibility benefit of .299 deciviews and 20 fewer days above 0.5 

deciviews at Gates of the Mountains WA. As compared to SNCR alone, LNB + SNCR would 

provide an additional visibility benefit of 0.129 deciviews and seven fewer days above 0.5 

deciviews at Gates of the Mountains WA. Overall improvement from LNB+SNCR is 0.424 

deciviews. EPA considers this impact to be beneficial, especially in light of the fact that this 

Class I area is not projected to meet the Uniform Rate of Progress (URP). Given the visibility 

improvement associated with LNB + SNCR and the reasonable average cost effectiveness for 

LNB + SNCR, EPA proposes that the NOx BART emission limit for the kiln at Holcim should 

be based on what can be achieved with LNB + SNCR. 
14 

Adopting an output-based standard avoids rewarding a source for becoming less efficient, i.e., 

requiring more feed to produce a unit of product. An output-based standard promotes the most 

efficient production process. 73 FR 34076, June 16, 2008. Thus, for example, the NSPS for 

NOx and National Emission Standards for Hazardous Air Pollutants (NESHAP) for PM are 

normalized by ton of clinker produced. EPA has recognized previously that facilities are 

allowed to measure feed inputs and to use a site-specific feed/clinker ratio to calculate clinker 

production. 75 FR 54990 (September 9, 2010). For these reasons, EPA is proposing to establish 

an emission limit on a lb/ton of clinker basis. 

In proposing a BART emission limit of 5.5 lb/ton clinker, EPA considered the emission rate 

currently being achieved by Holcim in lb/ton clinker, then applied an emission reduction of 

58%.30 This limit allows for a sufficient margin of compliance for a 30-day rolling average limit 

that would apply at all times, including startup, shutdown, and malfunction.31 EPA is also 

proposing monitoring, recordkeeping, and reporting requirements in regulatory text at the end of 

its proposal in the Federal Register. 

Under 40 CFR 51.308(e)(1)(iv), “each source subject to BART [is] required to install and 

operate BART as expeditiously as practicable, but in no event later than 5 years after approval of 

the implementation plan revision.” EPA proposes a compliance deadline of five (5) years from 

the date the final FIP becomes effective, because of the equipment installation and potential kiln 

combustion modifications that will be required. 

II. Sulfur Dioxide

Step 1: Identify All Available Technologies 

EPA has identified the following process modification, operation and/or control technologies as 

being available for SO2 reduction from cement manufacturing operations: 

1. Wet Lime Scrubbing 

2. Semi-wet Scrubbing (also known as Spray Dryer Absorber, or SDA) 

3. Fuel Substitution (lower sulfur fuel) 

4. Hot meal injection 

These technologies are listed from the most to the least effective, based on potential for 

emissions reduction beyond current baseline emissions. All options except fuel substitution were 

identified in Holcim’s original BART analysis of July 6, 2007. An analysis of fuel substitution 

(also known as fuel switching) was added in Holcim’s January 25, 2008 submittal, in response to 

EPA’s letter of November 26, 2007, which said that substitution of a lower sulfur content fuel 

should be evaluated as a possible BART option for reducing SO2 emissions. 

 

30 Holcim 2012 Response. (Holcim lists the mean 30-day rolling average NOx

 emission rate for 2008-2011 at 9.7 

lb/ton clinker. The 99th percentile 30-day rolling average was 12.6 lb/ton clinker. Applying 58% reduction to the 

99th percentile figure yields 5.29 lb/ton clinker.) 

31 As discussed in the BART Guidelines, section V (70 FR 39172, July 6, 2005), and Section 302(k) of the CAA, 

emissions limits such as BART are required to be met on a continuous basis. 
15 

Wet Lime Scrubbing

Wet scrubbing involves passing flue gas downstream from the main particulate matter control 

device (PMCD) through a sprayed aqueous suspension of lime or limestone that is contained in a 

scrubbing device. The SO2 reacts with the scrubbing reagent to form calcum sulfate (CaSO4) 

sludge that is collected. The sludge usually is dewatered and disposed of at an offsite landfill. 

Semi-wet Scrubbing (Spray Dry Absorber)

Semi-wet scrubbers, sometimes referred to as spray dry absorbers (SDAs), use lime (CaO) or 

limestone (CaCO3) to react with SO2. This technology involves injecting an aqueous lime or 

limestone suspension in fine droplets into the flue gas. The lime reacts with SO2 in the flue gas 

to create fine particles of calcium sulfite (CaSO3) or calcium sulfate (CaSO4). The moisture 

evaporates from the particles, and the particles are collected in the particulate matter control 

device. 

Limestone absorbent scrubbers have been used for SO2 control on preheater/precalciner kilns, but 

they can be successfully used on long kilns by adding spray nozzles that are made of special 

materials to prevent nozzle clogging. A SDA can achieve an SO2 removal efficiency of 30% to 

60%. Clogging may not be an issue with SDAs that use lime, due to the small size of the lime 

particles (3-10 microns) which allows the particles to dissolve in water droplets quickly and react 

with the gaseous SO2. One manufacturer of these scrubber systems indicates an SO2 removal 

efficiency of greater than 90%.32 

Fuel Switching

Fuel switching is a control alternative. Holcim currently uses a mixture of about 60% low-sulfur 

coal and 40% petroleum coke as the primary fuels for the kiln. The sulfur content of the 

petroleum coke is approximately 5.3% and the sulfur content of the coal is approximately 0.8%. 

If sulfur in fuel input to the kiln were reduced by burning a different blend of coal and coke with 

lower sulfur contents, a reduction in SO2 emissions would be expected. Holcim analyzed for the 

following fuel blends with lower sulfur content than the baseline fuel: 33

Baseline: 40% coke (5.3% S) / 60% coal (0.8% S) 

Option 1: 25% coke (5.3% S) / 75% coal (0.8% S) 

Option 2: 25% coke (3.5% S) / 75% coal (0.8% S) 

Option 3: 25% coke (2.9% S) / 75% coal (0.8% S) 

Option 4: 0% coke / 100% coal (0.8% S) 

Of the four options listed above for fuel switching, EPA analyzed two options. Option 1 would 

use 75% coal with 0.8% sulfur and 25% coke with 5.3% sulfur (same as Holcim’s Option 1 

immediately above). Option 2 would use 100% coal, which has a lower sulfur content (0.8%) 

than coke (same as Holcim’s Option 4 immediately above). EPA did not analyze for the other 

two options listed by Holcim because Holcim’s calculations showed they would be three to eight 

times more expensive, in terms of cost effectiveness, than the two options EPA chose to include 

 

32 Formation and Techniques for Control of Sulfur Dioxide and Other Sulfur Compounds in Portland Cement Kiln 

Systems, by F.M. Miller, G.L. Young and M. von Seebach (PCA R&D Serial No. 2460), p. 46. 

33 Holcim 2008 Responses, p. 6. 
16 

in its own analysis. Further, each of the two options not included in EPA’s analysis would be 

more expensive than the option of switching to 100% coal and would have less control 

effectiveness than switching to 100% coal. 

Hot Meal Injection

Hot meal injection is the hot-meal bypass in a preheater/precalciner kiln system, where calcined 

hot meal produced in the kiln is, in part, discharged in front of the kiln entrance after the 

precalcining process, so that the hot meal can scrub some of the SO2 generated from the kiln 

feed. Achievable SO2 reduction has been estimated at between 0% and 30%.

34

 

Step 2: Eliminate Technically Infeasible Options

Wet lime scrubbing, SDA and fuel substitution are technically feasible for Holcim’s wet kiln. 

Fuel substitution is already employed to some degree by the facility. Holcim’s current Title V 

permit allows this option to mitigate SO2 emissions. Specifically, the permit condition states that 

“Holcim is authorized to burn up to 100% natural gas, up to 100% coal, up to 100% coke, up to 

15% whole tires, or any combination of these fuels within the previously stated limits.”35

Hot meal is produced in a calcined/preheated kiln. Holcim does not have a preheater/precalciner 

kiln design from which hot meal can be obtained. Therefore, hot meal injection is technically 

infeasible. 

Step 3: Evaluate Control Effectiveness of Each Remaining Control Technology

EPA has stated that a well designed and operated wet scrubber can consistently achieve at least 

90% control (75 FR 54995 (September 9, 2010)) and that 95% control efficiency is possible (73 

FR 34080 (June 16, 2008)). Holcim’s analysis used 95% control, which is the upper end of the 

range that is possible.36 EPA used 95% control effectiveness for its analysis of wet scrubbing. 

According to one SDA manufacturer, 90% SO2 control effectiveness is the minimum of the 

range for a SDA with lime absorbent medium. Given the extremely low SO2 emissions from 

Holcim’s kiln (about 50 tpy),37 EPA considers 90% control to be optimistic here; nevertheless, 

relying on information from Holcim’s July 6, 2007 submittal, EPA used 90% control 

effectiveness for its analysis. 

For fuel substitution to 100% coal with 0.8% sulfur content, EPA relied on Holcim’s estimate of 

62% control effectiveness. For fuel substitution to 75% coal with 0.8% sulfur content and 25% 

petroleum coke with 5.3% sulfur content, EPA relied on Holcim’s estimate of 32% control 

effectiveness.38 

 

34 Formation and Techniques for Control of Sulfur Dioxide and Other Sulfur Compounds in Portland cement Kiln 

Systems, pp. 31, 44 and 48. 

35 Air Quality Permit #0982-11, issued by State of Montana to Holcim (US) Inc. for Trident Facility, condition II.B.1. 

36 Holcim Initial Response, p. 4-11. 

37 Holcim 2012 Response (Holcim listed the SO2 emissions at 53.5 tons in 2009, 64.1 tons in 2010, and 33.1 tons in 

2011. The average was 50.2 tons). 

38 Holcim 2008 Responses, p. 6. 
17 

Control effectiveness figures and estimated SO2 emission reductions of the technically feasible 

control options are presented in Table II-1. 

TABLE II-1 

 Summary of SO2 BART Analysis Control Technologies for Holcim 

Control 

Option 

Control 

Effectiveness 

(%) 

Annual 

Emissions 

Reduction

(tpy) 

Remaining 

Annual 

Emissions 

(tpy) 

Wet scrubbing 95 47.7 2.5 

SDA 90 45.2 5.0 

Fuel Switching 

Option 2 (100% 

lower sulfur coal) 

62 31.1 19.1 19.1 31.1

Fuel Switching 

Option 1 (25% 

coke/75% coal) 

32 16.1 34.1 34.1 16.1 

No Controls 

(Baseline) 0 0 50.2

Step 4: Evaluate Impacts and Document the Results

Factor 1 – Costs of compliance

Wet Lime/Limestone Scrubbing

Holcim submitted an original five factor analysis dated July 6, 2007. On January 25, 2008, 

Holcim submitted a revised wet SO2 scrubber cost analysis, in response to EPA’s letter of 

November 26, 2007. In Appendix B of its August 12, 2009 submittal to EPA, Holcim used a 

combination of vendor quotes and the EPA’s control cost manual to estimate different cost 

components. On June 16, 2011, and on March 2, 2012, Holcim submitted information on 

baseline annual SO2 emissions. 

EPA has relied on information in these submittals for this cost analysis, with the exception that 

Holcim used a 10-year equipment life and 7% interest rate as the basis for the capital recovery 

factor (CRF), while EPA used a CRF consistent with 20 years for the remaining useful life of the 

kiln, yielding a CRF of 0.0944, as specified in the Office of Management and Budget’s Circular 

A-4, Regulatory Analysis, available at: 

http://www.whitehouse.gov/omb/circulars_a004_a-4/

EPA has determined that a default 20-year amortization period is most appropriate to use as the 

remaining useful life of the facility. Without commitments for an early shutdown, EPA cannot 

consider a shorter amortization period in its analysis. In order to calculate the annualized capital 

cost, EPA multiplied the capital cost by the CRF. 
18 

The annual O&M cost listed below of $3,453,408 is adopted from Holcim’s August 12, 2009 

submittal, as the total of all direct and indirect annual costs, excluding the annual cost of capital.

Since Holcim presented the capital costs and annual costs in 2002 dollars, then scaled up the 

total annual cost to 2007 dollars using a 1.1582 Consumer Price Index (CPI) multiplier, EPA 

presents the costs in the same manner here.39 

EPA calculated the average cost effectiveness from the total annual cost and a 95% reduction in 

the baseline actual emissions. Costs are presented in Table II-2 below. 

TABLE II-2 

 Cost Analysis for Wet Limestone Scrubber 

Capital 

Cost 

(2002 $) 

Annual Cost 

of Capital 

(20-yr life, 

CRF=0.0944) 

Annual 

O&M 

Cost1

 (2002 $) 

Total 

Annualized Cost 

(2002 $) 

Total 

Annualized Cost 

(2007 $) 

Baseline 

Actual 

Emissions 

(Tons per 

Year) 

Tons per 

Year 

Reduced 

@ 95% 

Efficiency 

Average Cost 

Effectiveness, 

$/Ton 

Reduced 

8,098,489 764,497 3,453,408 4,217,905 4,885,177 50.2 47.7 102,414 

1

 Includes all direct and indirect annual costs, except the annual cost of capital. 

SDA

In Appendix C of its July 6, 2007 submittal, Holcim used a combination of EPA’s cost control 

manual and vendor quotes to establish different components of the SO2 control cost.40 EPA has 

relied on these cost data, with the exception that Holcim used a CRF based on a 10-year 

equipment life and 7% interest rate, while EPA used a CRF consistent with 20 years for the 

remaining useful life of the kiln, yielding a CRF of 0.0944, as specified in the Office of 

Management and Budget’s Circular A-4, Regulatory Analysis, available at: 

http://www.whitehouse.gov/omb/circulars_a004_a-4/

EPA has determined that a default 20-year amortization period is most appropriate to use as the 

remaining useful life of the facility. Without commitments for an early shutdown, EPA cannot 

consider a shorter amortization period in its analysis. In order to calculate the annualized capital 

cost, EPA multiplied the capital cost by the CRF. 

Holcim’s capital cost estimate for a semi-wet scrubber is $22,597,000.41 Although EPA has 

relied on this capital cost estimate, EPA notes that a recent cost analysis for a semi-wet lime 

scrubber (SDA), by Ash Grove Cement for BART for their cement kiln, a slightly smaller kiln 

than Holcim’s, listed a much lower capital cost of $11,644,912.42

 

39 Holcim Additional Response, August 2009, Appendix B. 

40 Holcim Initial Response, Appendix C. 

41 Holcim Initial Response, Appendix C. 

42 BART analysis by Ash Grove Cement for Montana City kiln, January 23, 2009. 
19 

The annual O&M cost listed below of $1,186,133 is adopted from Appendix C of Holcim’s July 

6, 2007 submittal, as the total of all direct and indirect annual costs, excluding the annual cost of 

capital. 

EPA calculated the average cost effectiveness from the total annual cost and a 90% reduction in 

the baseline actual emissions. Costs are presented in Table II-3 below. 

TABLE II-3 

 Cost Analysis for SDA 

Capital 

Cost 

(2002 $) 

Annual Cost of 

Capital 

(20-yr life, 

CRF=0.0944) 

Annual 

O&M 

Cost ($)1

Total 

Annualized 

Cost 

($) 

Baseline Actual 

Emissions 

(tons per year) 

Tons per 

Year 

Reduced @ 

90% 

Efficiency 

Average Cost 

Effectiveness, 

$/Ton Reduced 

22,597,000 2,133,156 1,186,133 3,319,289 50.2 45.2 73,435 

1

 Includes all direct and indirect annual costs, except the annual cost of capital. 

Fuel Substitution

EPA relied on Holcim’s costs for fuel substitution.43 For option 1, EPA calculated the average 

cost effectiveness from the total annual cost of option 1 and a 32% reduction in the baseline 

actual emissions. For option 2, EPA calculated the average cost effectiveness from the total 

annual cost of option 2 and a 62% reduction in the baseline actual emissions. There is no capital 

cost for fuel substitution because there is no equipment to buy or install. However, annual cost 

will increase due to increased fuel cost. Costs are presented in Table II-4 below. 

TABLE II-4 

Cost Analysis for Fuel Substitution

Control Option 

Annualized 

Cost 

($) 

SO2 removal 

efficiency 

(%) 

Baseline Actual 

Emissions 

(tons per year) 

Tons Per Year 

Reduced 

Average Cost 

Effectiveness 

($/ton) 

Option 1: 75% coal with 

0.8% sulfur content and 25% 

coke with 5.3% sulfur content 

240,515 32 50.2 16.1 19.1 114,938 12,592

Option 2: 100% coal with 

0.8% sulfur content 659,651 62 50.2 31.1 34.1 221,211 19,344

 

1

 Reflects 32% reduction from 50.2 tpy baseline emissions. 

 

2

 Reflects 62% reduction from 50.2 tpy baseline emissions. 

Factor 2 -- Energy and Non Air Quality Impacts

Fuel switching does not have energy or non air quality environmental impacts. Wet scrubbing 

and SDA use additional water and would generate a waste stream that would need to be 

transported and be disposed. Transporting the waste would use natural resources for fuel and 

would have associated air quality impacts. The disposal of the solid waste itself would be to a 

 

43 Holcim 2008 Responses, p. 6. 
20 

landfill and could possibly result in groundwater or surface water contamination if a landfill’s 

engineering controls were to fail. The environmental impacts associated with proper 

transportation and/or disposal should not be significant. 

Wet scrubbing and SDAs require additional electricity to service pretreatment and injection 

equipment, pumps, compressors, and control systems. The additional energy requirements that 

would be involved in installation and operation of the evaluated controls are not significant 

enough to warrant eliminating any of the options evaluated. The cost of the additional energy 

requirements has been included in our calculations.

SDAs that use lime as the absorbent do not have the particulate matter compliance problem 

prevalent in wet scrubbers located downstream of a particulate matter control device (PMCD) 

because, as explained above, the small size of the lime particles (3-10 microns) allows rapid 

dissolution in water droplets creating an ideal reaction surface for SO2 gases. Furthermore, the 

dried lime continues to react with any remaining SO2 in the downstream kiln system and PMCD. 

This control technology is located upstream of the PMCD and does not have any of the technical 

problems associated with a wet scrubber in this configuration. 

Factor 3 -- Any existing pollution control technology in use at the source

The kiln currently uses low sulfur coal as a component of fuel mix and inherent scrubbing for 

SO2 control. The kiln inherently acts as an SO2 scrubber, since some of the sulfur that is 

oxidized to SO2 is absorbed by the alkali compounds in the raw material fed to the kiln. Holcim 

currently uses a mixture of petroleum coke with a sulfur content of 5.3% and coal with a sulfur 

content of 0.8%. 

Factor 4 -- Remaining useful life

EPA has determined that the default 20-year amortization period is most appropriate to use as the 

remaining useful life of the facility. Without commitments for an early shut down, EPA cannot 

consider a shorter amortization period in our analysis. 

Factor 5 -- Evaluate visibility impacts

EPA conducted modeling described in Section I (NOx), Step 4, Factor 5, of this report. For 

Holcim specifically, Table II-5 below presents the visibility impacts of the 98th percentile of 

daily maxima for each Class I area from 2006 through 2008. Table II-6 below presents the 

number of days with impacts greater than 0.5 deciviews for each Class I area from 2006 through 

2008. 
21 

TABLE II-5 

Delta Deciview Improvement for SO2 Controls on Holcim 

Class I Area 

Baseline 

Impact 

(Delta 

deciview) 

Improvement 

from Fuel 

Switching 

Option 1 

(Delta deciview) 

Improvement 

from Fuel 

Switching 

Option 2 

(Delta deciview) 

Improvement 

from SDA 

(Delta deciview) 

Improvement 

from Wet 

Scrubber 

(Delta deciview) 

Gates of the 

Mountains WA 0.980 0.015 0.024 0.044 0.046 

Yellowstone NP 0.411 0.011 0.007 0.020 0.021 

TABLE II-6 

 Days Greater than 0.5 Deciview for SO2 Controls on Holcim (Three Year Total) 

Class I Area Baseline 

(days) 

Using Fuel 

Switching 

Option 1 

Using Fuel 

Switching 

Option 2 

Using 

SDA Using Wet 

Scrubbing 

Gates of the 

Mountains WA 46 45 44 43 43 

Yellowstone 

NP 13 12 12 12 12 

Step 5: Select BART

EPA proposes to find that BART for SO2 is no additional controls at Holcim with an emission 

limit of 1.3 lb/ton clinker. Of the five BART factors, visibility was the critical one in EPA’s 

analysis of controls for this source. The low visibility improvement did not justify requiring 

additional SO2 controls on this source. 

In its BART analysis for SO2 at Holcim, EPA considered wet scrubbing, SDA and fuel 

substitution. The comparison between EPA’s wet scrubbing, SDA and fuel substitution analysis 

is provided in Table II-7 below. 

 
22 

TABLE II-7 

Summary of EPA SO2 BART Analysis: 

Comparison of Wet Scrubbing, SDA and Fuel Switching for Holcim 

Control 

Option 

Total Capital 

Investment 

Total 

Annual 

Cost 

Average 

Cost 

Effectiveness 

($/ton) 

Incremental 

Cost 

Effectiveness 

($/ton) 

Visibility Impacts1,2

Visibility 

Improvement 

(delta 

deciviews) 

Fewer 

Days > 0.5 

deciview 

Wet 

Scrubbing 8,098,489 4,217,905 102,414 408,462 0.046 3 

SDA 22,597,000 3,319,289 73,435 239,607 0.044 3 

Fuel 

Substitution 

Option 2 

--

3

 659,651 19,344 27,942 0.024 2 

Fuel 

Substitution 

Option 1 

--

3

 240,515 12,592 --4 0.015 1 

1 The visibility benefit shown is for Gates of the Mountains WA. 

2

 The visibility improvement described in this table represents the change in the maximum 98th percentile impact 

over the modeled 3-year meteorological period (2006 through 2008) at the Class I area that showed the greatest 

improvement, Gates of the Mountains, WA. Similarly, the number of days above 0.5 deciviews is the total for the 

modeled 3-year meteorological period at Gates of the Mountains WA. 

3Capital cost is not required for fuel switching. 

4

Incremental cost is not applicable to the option that has the lowest effectiveness. 

EPA has concluded that wet scrubbing, SDA and fuel substitution are not cost effective control 

technologies and would not provide substantial visibility benefits. Given the minimal visibility 

improvements associated with SO2 controls, we propose that the SO2 BART emission limit for 

the kiln at Holcim should be based on current emissions, while allowing for a sufficient margin 

of compliance for a 30-day rolling average limit that would apply at all times, including startup, 

shutdown, and malfunction.44 

As explained in Section I, Step 5, of this report, adopting an output-based standard avoids 

rewarding a source for becoming less efficient. Accordingly, EPA is proposing 1.3 lb/ton clinker 

as a BART emission limit for SO2 at Holcim. In proposing this limit, EPA considered the 

emission rate currently being achieved by Holcim in lb/ton clinker.45 EPA is also proposing 

monitoring, recordkeeping, and reporting requirements in regulatory text. 

Under 40 CFR 51.308(e)(1)(iv), “each source subject to BART [is] required to install and 

operate BART as expeditiously as practicable, but in no event later than 5 years after approval of 

the implementation plan revision.” Because EPA is not requiring additional controls to be 

installed, EPA proposes that Holcim must comply with this emission limit within 180 days from 

 

44 As discussed in the BART Guidelines, section V (70 FR 39172, July 6, 2005), and Section 302(k) of the CAA, 

emissions limits such as BART are required to be met on a continuous basis. 

45 Holcim 2012 Response (Holcim lists the mean 30-day rolling average SO2 emission rate for 2008-2011 at 0.37 

lb/ton clinker. The 99th percentile 30-day rolling average was 1.20 lb/ton clinker). 
23 

the date that EPA’s final FIP becomes effective. This will allow time for monitoring systems to 

be certified, if necessary.