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 d etermination of the Best Available Retrofit Technology (BART) for control of Sulfur Dioxide (SO 2 ) and Nitrogen Dioxide (NO 2 ) emissions at the Holcim (US) Inc., Trident facility which man ufactures 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 fa cility of Zone 12, Easting 464 km, and Northing 5,088 km. The site elevation is approxima tely 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 Tri dent Cement Plant, January 25, 2008. (“Holcim 2008 Responses”)

→ BART analysis by Holcim for low-NO x burners for Trident Cement Plant, June 9, 2009. (“Holcim Additional Response, June 2009”)

→ Response to EPA letter regarding Confidential Busi ness Information (CBI) claims on BART analysis for Trident Cement Plant, August 12, 2009. (“Holcim Additional Response, August 2009”)

→ Response to EPA request for NO x and SO 2 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 Po rtland cement. The U.S. Environmental Protection Agency (EPA) Region 8 identified this fa cility as Best Available Retrofit Technology (BART) source based on modeling that showed the fac ility has a 98 th 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 f or BART analysis due to their significant emission rates, many of these are Particulate Matte r (PM) emission sources. The kiln is the only SO 2 and NO x emitting unit subject to BART analysis. Therefore, this analysis focuses primarily2

on the kiln as a source of SO 2 and NO x emissions and their control to improve visibility impairment attributable to Holcim’s Trident facilit y at Three Forks, MT.

The kiln currently does not employ any specified co ntrol technology other than inherent scrubbing and use of low sulfur coal as a component of the fuel mix for SO 2 control and good combustion practices for NO x control. The kiln is also permitted with a maximu m 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 NO x emissions at 998 tons for 2009, 1,175 tons for 201 0, and 1,164 tons for 2011. The average was 1,112 ton s. In the same response, Holcim listed the SO 2 emissions at 53.9 tons for 2009, 64.1 tons for 201 0, and 33.1 tons for 2011. The average was 50.2 tons. EPA has used 1,112 tons/yr of NO x and 50.2 tons/yr of SO 2 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 remaini ng 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 technolog y 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, Holc im proposed no new requirement for reduction of SO 2 and Low NO x Burners (LNB) for reduction of NO x emissions from the kiln as BART. EPA followed the same five step process and proposes no additional control for SO 2 control and Selective Non-Catalytic Reduction (SNCR ) with LNB for NO x control.



### I. Nitrogen Oxide

Step 1: Identify All Available Technologies

EPA has identified the following control technologi es as being available for reducing NO x emissions from Holcim’s Trident cement kiln:

1. Selective Catalytic Reduction (SCR) 2. Selective Non-Catalytic Reduction (SNCR) with Low N O x 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-NO x 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-NO

x Burners

LNBs use stepwise or staged combustion and localize d exhaust gas recirculation ( i.e. , at the flame). Staging of combustion air as achieved by s uch burners is an available control technology for NO x reduction in cement kilns. In the first stage, fu el combustion is carried out in a high temperature fuel-rich environment and the combustio n is completed in the fuel-lean low temperature second stage. By controlling the avail able oxygen and temperature, LNBs attempt to reduce NO x formation in the flame zone. LNBs have been used by the cement industry for nearly 30 years and are designed to reduce flame tu rbulence, delay fuel/air mixing, and establish fuel-rich zones for initial combustion. LNBs can b e used in combination with SNCR to achieve even greater emissions reduction.

Mid-Kiln Injection

MKF is a form of secondary combustion where a porti on 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 th e flame temperature and the flame length. This reduces thermal NO x formation by burning part of the fuel at a lower t emperature by creating reducing conditions at the mid-kiln fuel i njection point which may destroy some of the NO x formed upstream in the kiln burning zone. In addit ion, the entrained secondary fuel acts to reduce the temperature of the primary combustion pr oducts. TDF combustion also lowers the amount of fuel-bound nitrogen introduced to the kil n and thereby lowers NOx emissions through another mechanism.

Flue Gas Recirculation

FGR involves the use of oxygen-deficient flue gas f rom some point in the process as a substitute for primary air in the main burner pipe in the rota ry kiln. FGR lowers the peak flame temperature and develops localized reducing conditi ons in the burning zone by reducing the oxygen content of the primary combustion air. The intended effect is to decrease both thermal and fuel NO x formation in the rotary kiln.

Selective Non-Catalytic Reduction

In SNCR systems, a reagent such as ammonia (NH 3 ) or urea is injected into the flue gas at a suitable temperature zone, typically in the range o f 1,600 to 2,000°F and at an appropriate ratio of reagent to NO x . SNCR system performance depends on temperature, residence time, turbulence, oxygen content, and other factors speci fic to the given gas stream. SNCR can be used in combination with LNBs to achieve even great er emissions control.4

Selective Catalytic Reduction

SCR uses either ammonia (NH 3 ) or urea in the presence of a metal based catalyst to selectively reduce NO x emissions. SCR is used in the electric utility in dustry to reduce NO x emissions from boilers and has been used on three cement kilns in Europe. SCR is capable of reducing NO x emissions by about 80%.

Step 2: Eliminate Technically Infeasible Options

FGR is used in the electric utility industry, but i s not transferrable to cement kilns. For cement kilns, a hot flame is required to complete the chem ical reactions that form the clinker minerals from the raw materials. The long/lazy flame that w ould be produced by FGR would result in the production of unacceptable quality clinker. Clinke ring 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 gen eral reducing conditions that also could detrimentally affect clinker quality. Adding FGR t o 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 p reheater kiln. 73 FR 34079 (June 16, 2008). Although we find that SCR is technically feasible f or cement kilns, we have not analyzed it further because of the uncertainty regarding contro l effectiveness and costs. We note that EPA has acknowledged, in the context of establishing th e NSPS for Portland Cement Plants, substantial uncertainty regarding the control effec tiveness 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) pl anning periods.

Step 3: Evaluate Control Effectiveness of Remaining Control Technology

For LNB on Holcim’s kiln, it is appropriate to assu me 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 fo r 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 NO x emissions by SNCR, using the formula below:

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

The following discussion is an explanation of why E PA considers 50% control effectiveness an appropriate estimate for SNCR at long wet kilns, su ch as Holcim’s Trident kiln. Ash Grove Cement has used SNCR at similar wet kilns in Midlot hian, 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 indic ate that Ash Grove had been using SNCR in 2007 on one of the ir kilns at Midlothian; however, since the report doesn’t specify the exact timeframe, EPA doe s not know whether the 2007 data can be compared to the June through August 2008 data.

Because the emission report data submitted to the T CEQ 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 th e SNCR. 6 Table I-1 summarizes emission from the Midlothian kilns using the 2006 and 2008 d ata.

Table I-1 NO x 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 r ange of control effectiveness values that have been demonstrated at other kilns. 7

, 8

, 9

Concentration of baseline NO x emissions is one parameter affecting control effec tiveness. The percentage of control effectiveness is greater when initial NO x 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 t he docket: Ash Grove Texas, L.P. – Midlothian Plant 2008 Actual Emission Rate Calculations – Kilns, Ash Grov e Texas, L.P. – Midlothian Plant 2008 Actual Emissi on Rate calculations – Input Data.

6 See the documents received from TCEQ available in the docket: Ash Grove Texas, L.P. – Midlothian Plan t 2006 Actual Emission Rate Calculations – Kilns; Ash Grov e Texas, L.P. – Midlothian Plant 2006 Actual Emissi on Rate Calculations – Input Data; Ash Grove Texas, L.P. – Midlothian Plant 2008 Actual Emission Rate Calculat ions – Kilns, Ash Grove Texas, L.P. – Midlothian Plant 200 8 Actual Emission Rate calculations – Input Data.

7 EPA has stated previously that, “[o]n average, SNC R achieves approximately a 35 percent reduction in NO X at a ratio of NH 3 -to-NO X of about 0.5 and a reduction of 63 percent at an N H 3 -to-NO X ratio of 1.0” in the Federal Register notice proposing New Source Performance St andards for Portland cement plants. 73 FR 34078 (J une 16, 2008).

8 The Cadence brochures available at: http://cadencerecycling.com/sncr.html and http://www.cadencerecycling.com/Resources/6-PageCom plete.pdf state that control efficiencies of up to 50% can be achieved on long wet kilns. See also Enhanc ing 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 great er than 50 percent and as high as 80 percent or more” in th e Federal Register notice proposing New Source Perf ormance Standards for Portland cement plants. 73 FR 34079 (June 16, 2008).6

dynamic considerations that limit the reduction pro cess at low NO x concentrations. 10 The baseline NO x 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 a chieve even greater control effectiveness when compared to SNCR on the Midlothian kilns. Inf ormation provided to EPA by Holcim on NO x emissions at the Trident cement plant from 2008 th rough 2011 indicate that the mean 30- day rolling average emission rate was 9.7 lb/ton cl inker, 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 NO x control options is provided in Table I-2.

Table I-2 Summary of NO x 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 NO
x emissions at 998 tons for 2009, 1,175 tons for 2010, and 1,164 tons for 2011. Th e 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 re placement of their 2007 cost analysis for LNB. In the revised analysis, Holcim calculated th e 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) co nsistent with 20 years for the useful life of the kiln. EPA has det ermined 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 cons ider a shorter amortization period in its

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

11 Holcim 2012 Response. (Holcim lists the mean 30-d ay rolling average NO x 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 inst allation costs, for “retrofit installation.” EPA d id not.7

analysis. In order to calculate the annualized cap ital cost, EPA multiplied the capital cost by the CRF. 14

The capital cost estimate of $4,385,307 includes th e cost of converting from a direct to an indirect firing system to accommodate LNB, includin g 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 fo r 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 LN B 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 b een 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 d ollars to 2006 dollars, using a 1.25607 Consumer Price Index (CPI) multiplier. 19 EPA calculated the cost effectiveness from the to tal annual cost and a 30% reduction from the baseline a ctual 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 t he BART program. Holcim is not permitted by

14 CRF is 0.0944 and is based on a 7% interest rate a nd 20 year equipment life. Office of Management an d Budget, Circular A-4, Regulatory Analysis, http://www.white house.gov/omb/circulars_a004_a-4/.

15 Holcim Additional Response, June 2009.

16 BART submittal by Ash Grove Cement, January 23, 20 09.

17 Holcim Initial Response, p. 4-25.

18 NO x Control Technologies for the Cement Industry: Fina l Report, September 19, 2000, EPA-457/R-00-002, Tab le 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 qual ity 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 u seful 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. With out commitments for an early shut down, EPA cannot consider a shorter amortization period in it s analysis. In order to calculate the annualized capital cost, EPA multiplied the capital cost by th e CRF. 22

EPA analyzed only for commercial SNCR. In its Janu ary 25, 2008 submittal to EPA, Holcim discussed (at pages 11-12) an alternative form of S NCR, which Holcim refers to as “dust scoops” SNCR. This version of SNCR would use a solid pelle tized form of urea, which could be mechanically introduced into the existing “dust sco ops” mechanism. In its August 12, 2009 submittal to EPA, Holcim presented cost spreadsheet s which estimated substantially less cost for “dust scoops” SNCR than for commercial SNCR ($716,8 00 capital cost versus $1,312,800 capital cost). However, Holcim’s 2008 submittal in dicated 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, rath er than the “dust scoops” SNCR cost estimate.

The annual O&M cost listed below for commercial SNC R of $147,288 is adopted from Holcim’s August 12, 2009 submittal, as the total of all dire ct 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 pres ented 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 a nd 20 year equipment life. Office of Management an d Budget, Circular A-4, Regulatory Analysis, http://www.white house.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 achiev ed. 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 negat ive energy impacts 23 and are not expected to have any non-air quality environmental impacts. SN CR systems require electricity to operate the blowers and pumps. The generation of the electrici ty will most likely involve fuel combustion, which will cause emissions. While the required ele ctricity will result in emissions, these emissions should be small compared to the reduction in NO x 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 impa cts. The chemical reagents would be stored on site and could result in spills to the environme nt while being transferred between storage vessels or if containers were to fail during storag e or movement. The environmental impacts associated with proper transportation, storage, and /or disposal should not be significant. Therefore, the non-air quality environmental impact s did not warrant eliminating LNB or SNCR.

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

Holcim currently uses proper kiln design and operat ion for NO x 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 amortiz ation period is most appropriate to use as the remaining useful life of the facility. Without com mitments for an early shut down, EPA cannot consider a shorter amortization period in our analy sis.

Factor 5 -- Evaluate visibility impacts

EPA conducted modeling for Holcim as described in s ection V.C.3.a. of the Federal Register notice for the proposed regional haze FIP rule. Se ction V.C.3.a., titled “Visibility Improvement Modeling,” reads as follows:

The fifth factor to consider under EPA’s BART Guide lines 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 t o 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 meteor ological data; the CALPUFF model which is used to simulate the conversion of polluta nt emissions to PM 2.5 and the transport and fate of PM

2.5 ; and the CALPOST processor which is used to calcul ate visibility impairments at receptors sites.

The BART Guidelines recommend comparing visibility improvements between control options using the 98 th percentile of 24-hour delta deciviews, which is eq uivalent to the facility’s 8 th highest visibility impact day. The 98 th percentile is recommended rather than the maximum value to allow for uncertainty in the modeled impac ts 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 deci views of natural background alone, so ‘‘delta deciviews’’ is the estimate of the facility’s impac t relative to natural visibility conditions. Visibility is traditionally described in terms of v isual range in kilometers or miles. However, the visual range scale does not correspond to how peopl e perceive visibility because how a given increase in visual range is perceived depends on th e 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 pr oblem. It is linear with respect to perceived visibility changes over its entire range, and is an alogous to the decibel scale for sound. This means that a given change in deciviews will be perc eived as the same amount of visibility change regardless of the starting visibility. Lower deciv iew values represent better visibility and greater visual range, while increasing deciview values repr esent increasingly poor visibility. In the BART Guidelines, EPA determined that “a 1.0 decivie w 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 noticea ble change in most landscapes.” 25

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

Converting a 5% change in light extinction to a cha nge 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 conv ersion of SO 2 to particulate sulfate and NO x to particulate nitrate, at a rate dependent on mete orological conditions and background ozone concentration. These concentrations are then conve rted to delta deciviews by the CALPOST post-processor. The CALPUFF modeling system is ava ilable 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 dif ferent control scenarios. Each modeled day and location in the Class I area will have an assoc iated delta deciviews for each control option. For each day, the model finds the maximum visibilit y impact of all locations (i.e., receptors) in the Class I area. From among these daily values, t he BART Guidelines recommend use of the 98 th percentile, for comparing the base case and the ef fects of various controls.

As part of the FIP development efforts, EPA determi ned that CALPUFF modeling was needed to evaluate emissions scenarios that would be consiste nt 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 C arolina 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 sourc e are listed in Table 2 of the modeling protocol. The final report from this modeling effo rt is available in the docket. 29

The BART determination guidelines recommend that vi sibility impacts should be estimated in deciviews relative to natural background conditions . CALPOST uses background concentrations of various pollutants to calculate t he natural background visibility impact. EPA used background concentrations from Table 2–1 of “G uidance 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 m onthly variation in its visibility impact, which changes with relative humidity.

26 EPA's Model Distribution Webpage available at: htt p://www.epa.gov/ttn/scram/dispersion_prefrec.htm#ca lpuff.

27 CALPUFF model simulations had previously been perf ormed for some MT BART sources for certain emission s scenarios using meteorological data sets for the pe riod 2001-2003 that were developed by the WRAP. “CALMET/CALPUFF Protocol for BART Exemption Screeni ng Analysis for Class I Areas in the Western United States”, available at http://pah.cert.ucr.edu/aqm/3 08/bart/WRAP_RMC_BART_Protocol_Aug15_2006.pdf The WRAP data sets were developed in 2006 using the CALPUFF model versions and EPA guidance availab le at
that time.

28 “Modeling Protocol: Montana Regional Haze Federal Implementation Plan (FIP) Support”, University of N orth Carolina, Contract EP-D-07-102, November 14, 2011.

29 Modeling Report: Montana Regional Haze Federal Imp lementation Plan (FIP) Support, March 16, 2012.12

The following visibility impact analysis is for Hol cim specifically:

Table I-7 presents the visibility impacts of the 98 th 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 NO x 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 NO x 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 5 8% 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 NO x 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 control s for this source.13

In its BART analysis for NO x at Holcim, EPA considered LNB, SNCR, and LNB + SNC R. The comparison between EPA’s LNB, SNCR, and LNB+SNCR an alysis is provided in Table I-9.

TABLE I-9 Summary of NO x BART Analysis Comparison of Control Options for Ho lcim

Control Option Total Capital

Investment Total

Annual Cost Average

Cost Effectiveness ($/ton) Incremental

Cost Effectiveness ($/ton) Visibility Impacts 1,2

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 Mo untains WA.

2 The visibility improvement described in this table represents the change in the maximum 98 th 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 tot al for the modeled 3-year meteorological period at Gates of th e Mountains WA.

3 The incremental cost effectiveness from LNB to SNCR is a negative number because the numerator in doll ars is negative ( i.e. , the total annual cost of SNCR is less than LNB) b ut 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 th e option that has the lowest emission control effec tiveness.

EPA has concluded that LNB+SNCR is a cost effective control technology and would provide substantial visibility benefits. LNB+SNCR has a co st effectiveness value of $1,528 per ton of NO x 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 visib ility 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 compare d to SNCR alone, LNB + SNCR would provide an additional visibility benefit of 0.129 d eciviews and seven fewer days above 0.5 deciviews at Gates of the Mountains WA. Overall im provement from LNB+SNCR is 0.424 deciviews. EPA considers this impact to be benefic ial, especially in light of the fact that this Class I area is not projected to meet the Uniform R ate of Progress (URP). Given the visibility improvement associated with LNB + SNCR and the reas onable average cost effectiveness for LNB + SNCR, EPA proposes that the NO x 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 NO x and National Emission Standards for Hazardous Air Pollutants (NESHAP) for PM are normalized by ton of clinker produced. EPA has rec ognized previously that facilities are allowed to measure feed inputs and to use a site-sp ecific 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 cl inker, EPA considered the emission rate currently being achieved by Holcim in lb/ton clinke r, then applied an emission reduction of 58%. 30 This limit allows for a sufficient margin of comp liance for a 30-day rolling average limit that would apply at all times, including startup, s hutdown, 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 i n 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 o f 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 modificati on, operation and/or control technologies as being available for SO 2 reduction from cement manufacturing operations:

1. Wet Lime Scrubbing 2. Semi-wet Scrubbing (also known as Spray Dryer Absor ber, 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 emissio ns. All options except fuel substitution were identified in Holcim’s original BART analysis of Ju ly 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 r educing SO 2 emissions.

30 Holcim 2012 Response. (Holcim lists the mean 30-d ay rolling average NO x emission rate for 2008-2011 at 9.7 lb/ton clinker. The 99 th percentile 30-day rolling average was 12.6 lb/ton clinker. Applying 58% reduction to the

99 th 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 me t 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 SO 2 reacts with the scrubbing reagent to form calcum s ulfate (CaSO 4 ) sludge that is collected. The sludge usually is de watered 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 (CaCO 3 ) to react with SO 2 . This technology involves injecting an aqueous li me or limestone suspension in fine droplets into the flue gas. The lime reacts with SO 2 in the flue gas to create fine particles of calcium sulfite (CaSO 3 ) or calcium sulfate (CaSO 4 ). The moisture evaporates from the particles, and the particles ar e collected in the particulate matter control device.

Limestone absorbent scrubbers have been used for SO 2 control on preheater/precalciner kilns, but they can be successfully used on long kilns by addi ng spray nozzles that are made of special materials to prevent nozzle clogging. A SDA can ac hieve an SO 2 removal efficiency of 30% to 60%. Clogging may not be an issue with SDAs that u se 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 SO 2 . One manufacturer of these scrubber systems indic ates an SO 2 removal efficiency of greater than 90%. 32

Fuel Switching

Fuel switching is a control alternative. Holcim cu rrently uses a mixture of about 60% low-sulfur coal and 40% petroleum coke as the primary fuels fo r 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 SO 2 emissions would be expected. Holcim analyzed for the following fuel blends with lower sulfur content tha n 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 ab ove). EPA did not analyze for the other two options listed by Holcim because Holcim’s calcu lations showed they would be three to eight times more expensive, in terms of cost effectivenes s, than the two options EPA chose to include

32 Formation and Techniques for Control of Sulfur Dio xide and Other Sulfur Compounds in Portland Cement Kiln Systems, by F.M. Miller, G.L. Young and M. von Seeb ach (PCA R&D Serial No. 2460), p. 46.

33 Holcim 2008 Responses, p. 6.16

in its own analysis. Further, each of the two opti ons 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 preh eater/precalciner kiln system, where calcined hot meal produced in the kiln is, in part, discharg ed in front of the kiln entrance after the precalcining process, so that the hot meal can scru b some of the SO 2 generated from the kiln feed. Achievable SO 2 reduction has been estimated at between 0% and 30%

. 34

Step 2: Eliminate Technically Infeasible Options

Wet lime scrubbing, SDA and fuel substitution are t echnically feasible for Holcim’s wet kiln. Fuel substitution is already employed to some degre e by the facility. Holcim’s current Title V permit allows this option to mitigate SO 2 emissions. Specifically, the permit condition stat es that “Holcim is authorized to burn up to 100% natural ga s, 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. T herefore, hot meal injection is technically infeasible.

Step 3: Evaluate Control Effectiveness of Each Rema ining Control Technology

EPA has stated that a well designed and operated we t scrubber can consistently achieve at least 90% control (75 FR 54995 (September 9, 2010)) and t hat 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 analys is of wet scrubbing.

According to one SDA manufacturer, 90% SO 2 control effectiveness is the minimum of the range for a SDA with lime absorbent medium. Given the extremely low SO 2 emissions from Holcim’s kiln (about 50 tpy), 37 EPA considers 90% control to be optimistic here; n evertheless, relying on information from Holcim’s July 6, 2007 s ubmittal, 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 t o 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 Dio xide and Other Sulfur Compounds in Portland cement Kiln Systems, pp. 31, 44 and 48.

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

36 Holcim Initial Response, p. 4-11.

37 Holcim 2012 Response (Holcim listed the SO 2 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 SO 2 emission reductions of the technically feasible control options are presented in Table II-1.

TABLE II-1 Summary of SO 2 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 19.1 31.1

Fuel Switching Option 1 (25% coke/75% coal) 32 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 d ated July 6, 2007. On January 25, 2008, Holcim submitted a revised wet SO 2 scrubber cost analysis, in response to EPA’s lette r 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 SO 2 emissions.

EPA has relied on information in these submittals f or this cost analysis, with the exception that Holcim used a 10-year equipment life and 7% interes t 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 amortizat ion period is most appropriate to use as the remaining useful life of the facility. Without com mitments for an early shutdown, EPA cannot consider a shorter amortization period in its analy sis. 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 a dopted 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 Co nsumer 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 Cost 1 (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, exc ept 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 com ponents of the SO 2 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 o f 0.0944, as specified in the Office of Management and Budget’s Circular A-4, Regulatory An alysis, available at:

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

EPA has determined that a default 20-year amortizat ion period is most appropriate to use as the remaining useful life of the facility. Without com mitments for an early shutdown, EPA cannot consider a shorter amortization period in its analy sis. 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 scrub ber is $22,597,000. 41 Although EPA has relied on this capital cost estimate, EPA notes tha t a recent cost analysis for a semi-wet lime scrubber (SDA), by Ash Grove Cement for BART for th eir 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 a dopted from Appendix C of Holcim’s July 6, 2007 submittal, as the total of all direct and i ndirect 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, exc ept 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 op tion 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 equi pment to buy or install. However, annual cost will increase due to increased fuel cost. Costs ar e presented in Table II-4 below.

TABLE II-4 Cost Analysis for Fuel Substitution

Control Option Annualized Cost ($) SO 2 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 19.1 1 12,592

Option 2: 100% coal with 0.8% sulfur content 659,651 62 50.2 34.1 2 19,344

1 Reflects 32% reduction from 50.2 tpy baseline emis sions.

2 Reflects 62% reduction from 50.2 tpy baseline emis sions.

Factor 2 -- Energy and Non Air Quality Impacts

Fuel switching does not have energy or non air qual ity environmental impacts. Wet scrubbing and SDA use additional water and would generate a w aste stream that would need to be transported and be disposed. Transporting the wast e would use natural resources for fuel and would have associated air quality impacts. The dis posal of the solid waste itself would be to a

43 Holcim 2008 Responses, p. 6.20

landfill and could possibly result in groundwater o r surface water contamination if a landfill’s engineering controls were to fail. The environment al impacts associated with proper transportation and/or disposal should not be signif icant.

Wet scrubbing and SDAs require additional electrici ty 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 ev aluated. 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 rea ction surface for SO 2 gases. Furthermore, the dried lime continues to react with any remaining SO 2 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 con figuration.

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

The kiln currently uses low sulfur coal as a compon ent of fuel mix and inherent scrubbing for SO 2 control. The kiln inherently acts as an SO 2 scrubber, since some of the sulfur that is oxidized to SO 2 is absorbed by the alkali compounds in the raw mat erial fed to the kiln. Holcim currently uses a mixture of petroleum coke with a s ulfur 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 amortiz ation period is most appropriate to use as the remaining useful life of the facility. Without com mitments for an early shut down, EPA cannot consider a shorter amortization period in our analy sis.

Factor 5 -- Evaluate visibility impacts

EPA conducted modeling described in Section I (NO x ), Step 4, Factor 5, of this report. For Holcim specifically, Table II-5 below presents the visibility impacts of the 98 th percentile of daily maxima for each Class I area from 2006 throug h 2008. Table II-6 below presents the number of days with impacts greater than 0.5 decivi ews for each Class I area from 2006 through 2008.21 TABLE II-5 Delta Deciview Improvement for SO 2 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 SO 2 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 SO 2 is no additional controls at Holcim with an emissi on limit of 1.3 lb/ton clinker. Of the five BART fact ors, visibility was the critical one in EPA’s analysis of controls for this source. The low visi bility improvement did not justify requiring additional SO 2 controls on this source.

In its BART analysis for SO 2 at Holcim, EPA considered wet scrubbing, SDA and f uel substitution. The comparison between EPA’s wet scr ubbing, SDA and fuel substitution analysis is provided in Table II-7 below.22 TABLE II-7

Summary of EPA SO 2 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 Impacts 1,2

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 Mo untains WA.

2 The visibility improvement described in this table represents the change in the maximum 98 th 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 tot al for the modeled 3-year meteorological period at Gates of th e Mountains WA.

3 Capital cost is not required for fuel switching.

4 Incremental cost is not applicable to the option th at 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 visi bility benefits. Given the minimal visibility improvements associated with SO 2 controls, we propose that the SO 2 BART emission limit for the kiln at Holcim should be based on current emiss ions, while allowing for a sufficient margin of compliance for a 30-day rolling average limit th at 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. Ac cordingly, EPA is proposing 1.3 lb/ton clinker as a BART emission limit for SO 2 at Holcim. In proposing this limit, EPA considere d the emission rate currently being achieved by Holcim in lb/ton clinker. 45 EPA is also proposing monitoring, recordkeeping, and reporting requiremen ts 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 i n 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 wit h 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 me t on a continuous basis.

45 Holcim 2012 Response (Holcim lists the mean 30-day rolling average SO 2 emission rate for 2008-2011 at 0.37 lb/ton clinker. The 99 th percentile 30-day rolling average was 1.20 lb/ton clinker).23

the date that EPA’s final FIP becomes effective. T his will allow time for monitoring systems to be certified, if necessary.