ATTACHMENT I

November 30, 2007 revised SO2 BART proposal

(cover letter dated 12/05/07)
BEST AVAILABLE RETROFIT TECHNOLOGY DETERMINATION

O-N MINERALS (CHEMSTONE)  STRASBURG, VIRGINIA

ADDENDUM TO ADDRESS UPDATED SO2 EMISSION RATES

Prepared by: 

TRINITY CONSULTANTS

5320 Spectrum Drive 

Suite A 

Frederick, MD 21703 

(240) 379-7490 

November 2007 

Project 062101.0055 
SO2 BART Determination Addendum i Trinity Consultants 

O-N Minerals (Chemstone) 

TABLE OF CONTENTS

1. EXECUTIVE SUMMARY ........................................................................................ 1-1

2. INTRODUCTION AND BACKGROUND.................................................................... 2-1

3. REVISED BART EXEMPTION MODELING........................................................... 3-1

4. SO2 BART EVALUATION ..................................................................................... 4-1

4.1 FORMATION OF SO2 FROM LIME KILNS................................................................ 4-1 

4.2 BART DETERMINATION FOR SO2 FROM THE ROTARY KILN ................................. 4-2 

4.2.1 STEP 1: IDENTIFICATION OF AVAILABLE RETROFIT SO2 CONTROL 

TECHNOLOGIES ................................................................................................................4-2

4.2.2 STEP 2: ELIMINATE TECHNICALLY INFEASIBLE SO2 CONTROL TECHNOLOGIES4-3

4.2.3 STEP 3: RANK OF TECHNICALLY FEASIBLE SO2 CONTROL OPTIONS BY 

EFFECTIVENESS................................................................................................................4-3

4.2.4 STEP 4: EVALUATE FEASIBLE SO2 (TOP-DOWN) ...............................................4-3

4.2.4.1 Wet Scrubbing with Lime ...................................................................4-3

4.2.4.2 Inherent Dry Scrubbing (Process) .......................................................4-4

4.2.4.3 Semi –Wet Scrubbing (Spray Dryer Absorber)...................................4-4

4.2.5 STEP 5: EVALUATION OF VISIBILITY IMPACT OF FEASIBLE SO2 CONTROLS ......4-5

4.2.6 COMPARISON TO DATA FROM OTHER PREHEATER ROTARY LIME KILNS..........4-6

4.2.7 PROPOSED BART FOR SO2 .................................................................................4-8

4.3 BART DETERMINATION FOR SO2 FROM THE CALCIMATIC KILN .......................... 4-8 

4.3.1 STEP 1: IDENTIFICATION OF AVAILABLE RETROFIT SO2 CONTROL 

TECHNOLOGIES ................................................................................................................4-8

4.3.2 STEP 2: ELIMINATE TECHNICALLY INFEASIBLE SO2 CONTROL TECHNOLOGIES4-8

4.3.3 STEP 3: RANK OF TECHNICALLY FEASIBLE SO2 CONTROL OPTIONS BY 

EFFECTIVENESS................................................................................................................4-9

4.3.4 STEP 4: EVALUATE FEASIBLE SO2 (TOP-DOWN) ...............................................4-9

4.3.5 STEP 5: EVALUATION OF VISIBILITY IMPACT OF FEASIBLE SO2 CONTROLS ......4-9

4.3.6 PROPOSED BART FOR SO2 .................................................................................4-9

APPENDIX A
SO2 BART Determination Addendum ii Trinity Consultants 

O-N Minerals (Chemstone) 

LIST OF TABLES

TABLE 3-1: EMISSION RATES FROM CHEMSTONE’S OPERATIONS......................................................3-2

TABLE 3-2: VISIBILITY IMPACTS AT SHENANDOAH NATIONAL PARK ASSOCIATED WITH 

CHEMSTONE’S OPERATIONS...................................................................................................3-3

TABLE 4-1: EXISTING HIGHEST ACTUAL SO2 EMISSION RATES ........................................................4-1

TABLE 4-2: AVAILABLE SO2 CONTROL TECHNOLOGIES....................................................................4-2

TABLE 4-3: RANKING OF TECHNICALLY FEASIBLE KILN SO2 CONTROL TECHNOLOGIES BY 

EFFECTIVENESS – ROTARY KILN............................................................................................4-3

TABLE 4-4: SUMMARY OF EMISSION RATES MODELED IN SO2 CONTROL VISIBILITY IMPACT 

ANALYSIS ...............................................................................................................................4-5

TABLE 4-5: SUMMARY OF MODELED IMPACTS FROM SO2 CONTROL VISIBILITY IMPACT ANALYSIS –

ROTARY KILN ONLY @ HIGHEST ACTUAL VALUE................................................................4-6

TABLE 4-6: SUMMARY OF MODELED IMPACTS FROM SO2 CONTROL VISIBILITY IMPACT ANALYSIS –

ROTARY KILN ONLY @ PROPOSED LIMITATION....................................................................4-6

TABLE 4-7: RBLC SEARCH RESULTS FOR ROTARY LIME KILNS ........................................................4-7

TABLE 4-7: AVAILABLE SO2 CONTROL TECHNOLOGIES....................................................................4-8

TABLE 4-8: RANKING OF TECHNICALLY FEASIBLE KILN SO2 CONTROL TECHNOLOGIES BY 

EFFECTIVENESS – CALCIMATIC KILN.....................................................................................4-9
SO2 BART Determination Addendum 1-1 Trinity Consultants 

O-N Minerals (Chemstone) 

1. EXECUTIVE SUMMARY

O-N Minerals (Chemstone) operates a lime manufacturing facility in Strasburg, Virginia (Strasburg 

facility). This report provides a revised sulfur dioxide (SO2) Best Available Retrofit Technology 

(BART) determination report. As we have discussed with the Virginia Department of Environmental 

Quality (DEQ), Chemstone has proactively reevaluated SO2 emissions from the rotary kiln. Prior 

submittals and discussions regarding BART for our facility were based on prior testing which had 

indicated that the facility would meet the de minimis emissions criteria for SO2. However, recent 

stack test data obtained in October 2007 indicates that the facility does not qualify as a de minimis 

BART source for SO2. Therefore, a determination of BART for this pollutant is provided in this 

report. 

In preparing this determination, Chemstone has followed DEQ regulations found in 9 VAC 5 Chapter 

40 Article 52 to determine BART for SO2 emissions from the Rotary Kiln, which already 

incorporates a baghouse. Sulfur dioxide emissions from the other SO2 BART source at the facility, 

the Calcimatic Kiln, although very small, are also addressed in this report. Specifically, Chemstone 

conducted a five-step analysis to determine BART for SO2 that included the following: 

1. Identifying all available retrofit control technologies; 

2. Eliminating technically infeasible control technologies; 

3. Evaluating the control effectiveness of remaining control technologies; 

4. Evaluating impacts and documenting the results; 

5. Evaluating visibility impacts 

Based on the five-step analysis, Chemstone proposes the following as BART for SO2: 

Rotary Kiln: Chemstone proposes to comply with a BART emission limit of 79.3 lb/hr based on 

discrete testing using Method 6 (or other method approved by DEQ). We should illustrate that 

the proposed limitation of 79.3 lb/hr is a 77 percent reduction from the rotary kiln’s currently 

allowed SO2 emissions rate of 356.4 lb/hr.1

 The tested average value of at least three 8-hour valid 

test runs would be compared to the proposed BART limitation. Testing shall be conducted on an 

annual basis, unless three successive tests show compliance with a margin of 10 percent or more. 

Then, testing may be reduced to once every three years until such time as test run average 

results show a margin of less than 10 percent. 

Calcimatic Kiln: Chemstone proposes that the BART emission limit be 7.52 lb/hr using the 

existing scrubbing device currently in place. This emission rate is the same one currently 

contained in the Strasburg plant’s Title V operating permit. 

 1 Global Stone Chemstone Corporation (currently O-N Minerals), Statement of Legal and Factual Basis, Permit 

No. VRO80252, page 18. 
SO2 BART Determination Addendum 2-1 Trinity Consultants 

O-N Minerals (Chemstone) 

2. INTRODUCTION AND BACKGROUND

O-N Minerals (Chemstone) operates a lime manufacturing facility in Strasburg, Virginia (Strasburg 

plant). Chemstone is currently operating in accordance with Virginia Department of Environmental 

Quality (DEQ) Title V operating permit VRO80252, issued on July 30, 2002. The current Title V 

permit expires July 30, 2007.2

 The Strasburg plant is considered eligible for the application of Best 

Available Retrofit Technology (BART) as part of EPA’s Regional Haze Rule. 

Chemstone submitted an initial source-specific BART Applicability Modeling Protocol on August 30, 

2006 and, subsequently, a BART Applicability Analysis in September 2006. The results of this 

refined modeling analysis indicated that visibility impacts from this facility are quite low and only 

slightly greater than the Visibility Improvement State and Tribal Association of the Southeast 

(VISTAS) exemption thresholds. An initial BART Determination report for the applicable calcimatic 

and rotary kilns was subsequently submitted in February 2007 addressing all of the significant 

Visibility Impairing Pollutants (VIPs). 

Since the initial submittal, recent stack testing at the Strasburg plant has shown SO2 emission are not 

de minimis requiring Chemstone to submit this addendum to the BART determination filed earlier 

this year. Accordingly, Chemstone has re-examined the BART Determination for SO2 as provided in 

this report. 

 2 The facility has filed a timely Title V operating permit renewal application and will continue to operate under 

the current Title V permit until the permit is renewed. 
SO2 BART Determination Addendum 3-1 Trinity Consultants 

O-N Minerals (Chemstone) 

3. REVISED BART EXEMPTION MODELING

A BART-eligible source is subject to BART if the source is “reasonably anticipated to cause or 

contribute to visibility impairment in any federal mandatory Class I area.” EPA has determined that a 

source is reasonably anticipated to contribute to visibility impairment if the 98th percentile of the 

visibility impacts from the source is greater than 0.5 ∆dv when compared against a natural 

background. Refined air quality modeling was conducted using the VISTAS 4-km meteorological 

domain 5 and the VISTAS version of CALPUFF to predict the existing visibility impairment 

attributable to the Strasburg plant in Shenandoah National Park. 

Based on this modeling, it was concluded that the Strasburg plant was subject to BART since the 

visibility impacts attributable to the Rotary and Calcimatic kilns were greater than 0.5 ∆dv when 

compared against a natural background for both Class I areas. However, the previous modeling 

analysis stack testing that was performed showed more SO2 emissions from operation of the rotary kiln

than originally expected. As such, the previous refined BART modeling was updated based on the 

revised emissions determined from the October 2007 stack testing. Note that per guidance from the 

FLM and DEQ, Chemstone conducted the revised modeling using the same version of CALPUFF and 

meteorological data.3

 Table 3-1 shows the revised (highest actual) emission rates from Chemstone’s 

operations, while Table 3-2 depicts the visibility impacts at Shenandoah due to these emissions. 

 3

 Per email from Mike Kiss, VaDEQ, dated November 13, 2007 to Ian Donaldson, Trinity Consultants. Note that 

none of the CALPUFF model options have been altered from the previously conducted modeling. Only the emission rates 

were updated. 
SO2 BART Determination Addendum 3-2 Trinity Consultants 

O-N Minerals (Chemstone) 

TABLE 3-1: EMISSION RATES FROM CHEMSTONE’S OPERATIONS

Pollutant 

Modeled 

Size 

Range 

Rotary 

Kiln 

Calcimatic 

Kiln 

Category (μm) (lb/hr) (lb/hr) 

PMC 6-10 0.07 0.23 

 2.5-6 0.11 0.37 

PMF 1.25-2.5 0.10 0.31 

 1.0-1.25 0.03 0.08 

 0.625-1.0 0.05 0.16 

 0.5-0.625 0.06 0.20 

PIC 0.625-1.0 0.002 0.006 

(nonsulfate) 0.5-0.625 0.002 0.006 

POC 0.625-1.0 4.8E-05 1.6E-04 

 0.5-0.625 4.8E-05 1.6E-04 

EC 1.25-2.5 0.004 0.025 

 1.0-1.25 0.001 0.007 

 0.625-1.0 0.002 0.013 

 0.5-0.625 0.002 0.016 

SO4 -- 0.13 0.28 

NOX -- 80.2 7.20 

SO2 -- 66.10 0.04 
SO2 BART Determination Addendum 3-3 Trinity Consultants 

O-N Minerals (Chemstone) 

TABLE 3-2: VISIBILITY IMPACTS AT SHENANDOAH NATIONAL PARK ASSOCIATED WITH 

CHEMSTONE’S OPERATIONS

 

Natural Background 

Method 

Ranked 

2001 ∆dv 

Ranked 

2002 ∆dv 

Ranked 

2003 ∆dv 

Maximum 8th-High ∆dv 

(Total Days > 1.0 dv, > 0.5 dv) 

Annual Average 

2.028 

1.582 

1.003 

0.873 

0.869 

0.784 

0.777 

0.751 

1.390 

1.291 

0.824 

0.806 

0.738 

0.727 

0.677 

0.667 

1.225 

1.115 

1.090 

0.885 

0.843 

0.833 

0.826 

0.803 

0.8034

(8, 45) 

 

 

 4

 At the proposed SO2 emission limitation the maximum 8th high total impact is estimated to be 0.837 dv. This 

new impact was determined by conservatively assuming that the additional SO2 will become sulfate by the time the modeled 

plume reaches Shenandoah and scaling the portion of the visibility impact due to sulfates. 
SO2 BART Determination Addendum 4-1 Trinity Consultants 

O-N Minerals (Chemstone) 

4. SO2 BART EVALUATION

The section of the report provides the step-by-step analysis of the case-specific BART determination 

for SO2 emission units at the Strasburg plant. As discussed in the initial BART determination report, 

the SO2 emissions from the raw material calcimatic kiln system are very small compared to the SO2

emissions from the rotary kiln as shown in Table 4-1. Therefore, the focus of visibility improvement 

opportunities should be focused on the rotary kiln. 

TABLE 4-1: EXISTING HIGHEST ACTUAL SO2 EMISSION RATES

Equipment Maximum Annual 

Average Emission Rate 

(lb/hr) 

Maximum Annual 

Emission Rate 

(tpy) 

Rotary5 66.1 289.5 

Calcimatic6 7.52 31.7 

4.1 FORMATION OF SO2 FROM LIME KILNS

Sulfur dioxide (SO2) is emitted from the kilns as a result of the combustion of fuel which contains 

sulfur and from volatilization of trace amounts of sulfur from the limestone. Fuel is burned in the lime 

kilns to provide the necessary heat for the reaction of converting limestone (calcium carbonate, 

CaCO3) to lime (calcium oxide, CaO) and carbon dioxide (CO2). The reaction is characterized as follows: 

CaCO3 → CaO + CO2

Sulfur present in the fuel is oxidized to form SO2. Lime and limestone present in the kiln act as a 

natural scrubber for sulfur dioxide. Most commercially available wet and dry SO2 scrubbing systems 

use either lime or limestone as the reactive agent in the scrubber design – obviously lime and 

limestone is inherently present in generous portions in a lime kiln. The following is a typical reaction 

in a lime system: 

CaO + SO2 → CaSO3 + 1⁄2 O2 → CaSO4 

In essence, the entire kiln acts as a dry scrubber for SO2. Absorption of the SO2 onto the solid 

particles occurs mainly in the kiln and the particulate matter is collected in the baghouse. Inherent dry 

scrubbing in the lime production process typically reduces SO2 emissions by greater than 90 percent 

for new preheater kiln systems. 

 

 5

 Rotary kiln emissions are based on stack testing performed October 30, 2007. 

 6

 Calcimatic kiln emissions are based on current Title V Operating Permit limitations. 
SO2 BART Determination Addendum 4-2 Trinity Consultants 

O-N Minerals (Chemstone) 

SO2 emissions are not only impacted by the sulfur in the fuel, but also by the sulfur in the limestone 

feed. For example, the rotary kiln will process approximately 1,200 tons of limestone per day7. The 

limestone is approximately 0.02 percent sulfur; hence, about 20 pounds of sulfur per hour will enter 

the system from the limestone, and about 150 pounds of sulfur per hour will enter the system with the 

fuel (assuming coal sulfur content is 1.5 percent). Another factor impacting the amount of sulfur 

emitted is the amount of oxidation of the lime. Strong oxidation in the kiln will drive the oxidation of 

sulfur to monosulfate (SO3) rather than SO2. SO3 more readily reacts with lime and lime kiln dust 

(LKD), hence results in more sulfur being retained in the product and the LKD. 

At Chemstone, in addition to the preheater rotary kiln, the site possesses a second kiln which is an 

unusual kiln type – a calcimatic kiln. This kiln does not have the benefits of SO2 removal like a 

preheater rotary kiln. However, Chemstone’s calcimatic kiln is equipped with a scrubbing device that 

helps reduce SO2 emissions. 

Even with this understanding, kilns are dynamic process devices. As such, it will be important that 

any BART permit limit include some compliance margin to allow for such variation over time in its 

limitation design. 

4.2 BART DETERMINATION FOR SO2 FROM THE ROTARY KILN

The rotary kiln system at Chemstone consists of two BART-eligible emissions units: the Rotary kiln 

and a Product Cooler.8

 As SO2 emissions do not occur from the Product Cooler, the Rotary kiln is the 

emission unit being reviewed in this section. The rotary kiln at Strasburg is a preheater-type kiln that 

is controlled by a positive pressure, multi-stack baghouse. 

4.2.1 STEP 1: IDENTIFICATION OF AVAILABLE RETROFIT SO2 CONTROL 

TECHNOLOGIES

Step 1 of the BART determination is the identification of all available retrofit SO2 control 

technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air 

Technology Center, publicly-available air permits, applications, and technical literature published by 

the U.S. EPA, state agencies, and Regional Planning Organizations (RPOs). The available retrofit 

SO2 control technologies are summarized in Table 4-2. 

TABLE 4-2: AVAILABLE SO2 CONTROL TECHNOLOGIES

SO2 Control Technologies 

Wet Scrubbing with Lime 

Inherent Dry Scrubbing (Process) 

Semi-Wet Scrubbing (Spray Dryer Absorber) 

 7

 This average throughput is based on the 50 ton per hour stone throughput listed in the current Title V operating 

permit. 

8 Per Chemstone’s letter to VA DEQ dated January 17, 2006, which identifies BART-eligible emission units from 

the Strasburg plant.
SO2 BART Determination Addendum 4-3 Trinity Consultants 

O-N Minerals (Chemstone) 

4.2.2 STEP 2: ELIMINATE TECHNICALLY INFEASIBLE SO2 CONTROL TECHNOLOGIES

Step 2 of the BART determination is to eliminate technically infeasible SO2 control technologies that 

were identified in Step 1. Each technology was reviewed for its technical feasibility on the Rotary 

kiln at the Strasburg plant. Each of the aforementioned technologies is technically feasible. 

4.2.3 STEP 3: RANK OF TECHNICALLY FEASIBLE SO2 CONTROL OPTIONS BY 

EFFECTIVENESS

The third step in the BART analysis is to rank the technically feasible options according to 

effectiveness. Table 4-3 presents potential SO2 technically feasible control technologies for the kiln 

and the associated SO2 emission levels. 

TABLE 4-3: RANKING OF TECHNICALLY FEASIBLE KILN SO2 CONTROL TECHNOLOGIES BY 

EFFECTIVENESS – ROTARY KILN

Pollutant Control Technology 

Expected 

Control 

Efficiency 

Wet Scrubbing with Lime Up to 98% 

SO Inherent Dry Scrubbing (Process, Base Case) 75 to 92% 2

Semi-Wet Scrubbing (Spray Dryer Absorber) Up to 90% 

4.2.4 STEP 4: EVALUATE FEASIBLE SO2 (TOP-DOWN) 

Step four for the BART analysis procedure is the impact analysis. The BART determination 

guidelines list the four factors to be considered in the impact analysis: 

• Cost of compliance 

• Energy impacts 

• Non-air quality impacts; and 

• The remaining useful life of the source 

Chemstone has conducted an impact analysis for the technically feasible control options. For the 

rotary kiln, the remaining useful life factor for the source is not an issue. 

4.2.4.1 WET SCRUBBING WITH LIME

Wet SO2 scrubbers operate by flowing the flue gas upward through a large reactor vessel 

that has an alkaline reagent (that is, limestone or lime slurry) flowing down from the top. 

The scrubber mixes the flue gas and alkaline reagent, using a series of spray nozzles to 

distribute the reagent across the scrubber vessel. The calcium in the reagent reacts with the 

SO2 in the flue gas to form calcium sulfite and/or calcium sulfate that is removed from the 

scrubber with the sludge and is disposed. Most wet scrubbing systems utilize forced 

oxidation to assure that only calcium sulfate sludge is produced. 
SO2 BART Determination Addendum 4-4 Trinity Consultants 

O-N Minerals (Chemstone) 

The sludge from the scrubber creates a solid waste handling and disposal problem. This 

sludge must be handled in a manner that does not result in groundwater contamination. 

Also, the sludge disposal area needs to be permanently set aside from future surface uses 

since the disposed sludge cannot bear any weight from such uses as buildings or cultivated 

agriculture. 

Disadvantages associated with wet limestone or lime scrubbers includes the creation of a 

visible wet stack with a visible plume of water droplets, generation of particulate matter by 

the scrubbing process causing elevated opacity, water consumption, and wastewater and 

sludge disposal issues. Finally, a wet system will cost about $7,226 per ton of SO2

removed.9 The detailed cost analysis is included in Appendix A. Therefore, based on the 

unacceptable environmental and economic impacts, wet scrubbing will not be considered 

further and does not constitute BART. 

4.2.4.2 INHERENT DRY SCRUBBING (PROCESS) 

Inherent dry scrubbing in the lime production process normally provides around 90 percent 

removal (in new modern preheater kilns) of SO2 at no further energy, environmental, or 

economic impacts, since it occurs naturally in the system proposed. In a lime kiln, SO2 that 

is released during the lime formation process will react with the lime. The amount of SO2 

absorbed in the system is a function of not only the sulfur in the fuel, but also the amount 

of sulfur in the stone feed, the amount of sulfur in the product, and the degree of calcium 

oxidation that takes place in the kiln (greater oxidation generally results in more sulfur 

removal). Inherent dry scrubbing can provide control efficiencies greater than 90 percent 

for new preheater lime kilns and efficiency data from Chemstone shows removal levels of 

between 70% and 99+%. Because inherent dry scrubbing is an integral part of the process 

system, it is considered the base case for BART. 

4.2.4.3 SEMI –WET SCRUBBING (SPRAY DRYER ABSORBER) 

Spray dryer systems operate by injecting a moist sorbent into the scrubber. As the hot flue 

gas mixes with the sorbent, water is evaporated. This process is sometimes referred to as 

semi-wet scrubbing. The sorbent is normally lime or calcium hydroxide. The surfaces that 

are exposed to the solid sorbent react with SO2. The process forms a dry waste product that 

is collected in a baghouse. The performance of the semi-wet system is sensitive to 

operating conditions and its performance cannot be assured without additional temperature 

control devices. The optimum temperature is 20-50°F below saturation temperature.10 

Flue gas with high temperatures reduces the performance of the scrubber.11 The semi-wet 

scrubber would need to be located prior to the rotary kiln baghouse, where the gas 

temperature is approximately 500°F. 

 9

 Annualized costs would be approximately $6,030 based on the proposed permit limit. 10 EPA Fact Sheet, Flue Gas Desulfurization, EPA-452/F-03-034. 11 Ibid. 
SO2 BART Determination Addendum 4-5 Trinity Consultants 

O-N Minerals (Chemstone) 

Therefore, the system would provide for a removal efficiency lower than the inherent 

scrubbing of the lime kiln system or the flue gas would need to be cooled prior to entering 

the spray dryer system. Environmental disadvantages of this system include the production 

of dry waste, which requires landfill disposal and water usage. 

A cost estimate was prepared to evaluate the economic feasibility of a semi-wet (dry) 

scrubber for the kilns. The detailed cost analysis is provided in Appendix A. The 

calculated cost effectiveness for a spray dryer system is $10,831 per ton of SO2 removed.12

This cost is above what is considered reasonable. Therefore, semi-wet scrubbing is 

considered economically infeasible for SO2 control and is not BART. 

4.2.5 STEP 5: EVALUATION OF VISIBILITY IMPACT OF FEASIBLE SO2 CONTROLS 

An impact analysis was conducted to assess the visibility improvement of the proposed emission rates 

versus the emission rates at two potential control ranges (which may or may not be continuously 

achievable at Chemstone). The proposed emission rates and the emission rates when one of the two 

control levels were modeled using CALPUFF. The SO2 emission reductions from the base case and 

then the base case with 80 and 90 percent removal applied (from the 2007 test results) are evaluated 

here. The emission rates, which are summarized in Table 4-4, are based on the estimated control 

efficiencies that may represent vendor guaranteed emission control levels. 

TABLE 4-4: SUMMARY OF EMISSION RATES MODELED IN SO2 CONTROL VISIBILITY IMPACT 

ANALYSIS 

Emission Rate Scenario 

SO2 Emission Rate 

Highest Actual 

(lb/hr) 

SO2 Emission Rate 

Proposed Limitation

(lb/hr) 

Inherent Dry Scrubbing (Process, Base Case) 66.1 79.3 

90% Control 6.6 7.9 

80% Control 13.2 15.9 

Comparisons of the visibility impacts based on existing conditions with the two control scenarios are 

provided in Tables 4-5 and 4-6. Table 4-5 depicts “real” reductions that could be expected based on 

the highest actual emissions and Table 4-6 shows “theoretical” reductions as if the kiln emitted at the 

proposed permit limit continuously. The visibility improvement associated with these options is also 

provided in the same table. This value was calculated as the difference between the existing visibility 

impairment and the visibility impairment for the controlled emission rates as measured by the 98th

percentile modeled visibility impact. 

 12 Annualized costs would be approximately $9,026 based on the proposed permit limit. 
SO2 BART Determination Addendum 4-6 Trinity Consultants 

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TABLE 4-5: SUMMARY OF MODELED IMPACTS FROM SO2 CONTROL VISIBILITY IMPACT 

ANALYSIS – ROTARY KILN ONLY @ HIGHEST ACTUAL VALUE

Scenarios 

98% 

Impact 

(∆dv) 

Absolute 

Improvement from 

Base Case (∆dv) 

Percent 

Improvement from 

Base Case 

Inherent Dry Scrubbing 

(Process, Base Case) 

0.80 — — 

After 90% Control 0.76 0.05 6% 

After 80% Control 0.76 0.04 5% 

TABLE 4-6: SUMMARY OF MODELED IMPACTS FROM SO2 CONTROL VISIBILITY IMPACT 

ANALYSIS – ROTARY KILN ONLY @ PROPOSED LIMITATION13

Scenarios 

98% 

Impact 

(∆dv) 

Absolute 

Improvement from 

Base Case (∆dv) 

Percent 

Improvement from 

Base Case 

Inherent Dry Scrubbing 

(Process, Base Case) 

0.84 — — 

After 90% Control 0.78 0.06 7% 

After 80% Control 0.78 0.06 6% 

As shown in Table 4-5, installation of controls capable of reducing emissions by 90 percent on SO2

could potentially result in a 5.5 percent improvement to the existing visibility impairment. Similarly, 

an 80 percent control level would result in a 5.2 percent improvement to the existing visibility 

impairment. Therefore, implementation of either control strategy would result in a minuscule 

visibility improvement of no more than 0.04 ∆dv (about 90% less than the established federal BART 

exemption threshold). This minimal visibility improvement was expected due to the low contribution 

of sulfates to the existing visibility impairment when compared to nitrates from this source. 

4.2.6 COMPARISON TO DATA FROM OTHER PREHEATER ROTARY LIME KILNS

To further evaluate potential BART options and applicability, Chemstone compared tested actual 

lb/ton emission limits to limits obtained from other facilities through a recent RBLC database query. 

Regarding the Strasburg plant, the Rotary kiln’s SO2 emission rate is approximately 2.6 lb/ton of lime 

and 1.3 lb/ton of stone.14 Table 4-6 details the results of the RBLC database search conducted in 

November 2007. It should be noted that the values presented in the RBLC cannot necessarily be 

completely verified as to whether the limits are for stone feed or lime produced. 

 13 Note that the visibility impacts associated with the proposed limit were determined by conservatively assuming 

that the additional SO2 will become sulfate by the time the modeled plume reaches Shenandoah and scaling the portion of 

the visibility impact due to sulfates. 14 Approximately 3.1 lb/ton lime produced at the proposed limitation. 
SO2 BART Determination Addendum 4-7 Trinity Consultants 

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TABLE 4-7: RBLC SEARCH RESULTS FOR ROTARY LIME KILNS

Facility 

Permit Date 

(from 

RBLC) 

Lime Production 

Capacity (tpd) 

Permitted SO2

Limit (lb/ton) 

State Agency/ 

Personnel Contacted 

CLM-Superior, WI 8/16/2006 650 0.62 RBLC 

Graymont 

Pilot Peak Facility, 

Nevada 

1/27/2006 N/A 14 lb/hr RBLC 

Graymont 

Bellefonte Plant, PA 

7/9/2004 1200 6.1 RBLC 

Graymont 

Bellefonte Plant, PA 

7/9/2004 1050 2.1 RBLC 

Carmeuse Lime 

Maple Grove Facility, 

OH 

10/14/2003 650 34 RBLC 

Vulcan Materials 

Kankakee County, IL 

10/28/2002 1296 2.76 RBLC 

Arkansas Lime 

Company 

Batesville, AR 

5/18/2000 600 2.1 RBLC 

Arkansas Lime 

Company 

Batesville, AR (Kiln 

#1) 

9/14/1999 625 2.5 RBLC 

Texas Lime 

Company - 

Cleburne, TX 

8/02/1999 850 2.6 RBLC/Texas Permit 

No. 5999/PSD-TX-54 

Continental Lime – 

Cricket Mtn., Utah 

(Kiln #2) 

6/22/1997 600 0.9 RBLC 

Chemical Lime 

Company - O'Neal 

Plant, Alabama 

4/29/1996 1350 2.1 RBLC 

Continental Lime - 

Indian Creek 

Operation, Montana 

3/20/1996 500 1.5 RBLC 

Continental Lime – 

Cricket Mtn. Utah 

(Kiln #4) 

1/10/96 1200 0.8 RBLC 

Chemical Lime 

Company 

Ste. Genevieve, MO 

 1350 

(2700 combined) 

1.6 – Hourly 

1.4 - Annual 

RBLC 

As Table 4-6 illustrates, Chemstone’s SO2 limits are within range of existing BACT approved ranges, 

despite the vintage of the rotary kiln when compared to newer rotary lime kilns and regardless of 

whether the value being compared is a limit based on stone feed or lime produced. 
SO2 BART Determination Addendum 4-8 Trinity Consultants 

O-N Minerals (Chemstone) 

4.2.7 PROPOSED BART FOR SO2

Based on the five step analysis outlined by EPA, the base case (inherent scrubbing by the process) is 

BART. The two technically feasible alternatives are not cost-effective and do not result in any 

perceptible improvement in visibility at the subject Class I area. For these reasons, Chemstone 

proposes a BART permit limit as follows. 

The rotary kiln will meet a limit of 79.3 lb/hr of SO2 based on discrete testing using EPA Method 

6 (or other method approved by the Department).15 The test run average of at least three 8-hour 

tests is compared to the BART limit in order to demonstrate compliance. Testing shall be 

conducted on an annual basis, unless three successive tests show compliance with a margin of 10 

percent or more. Then, testing may be reduced to once every three years until such time as test 

run average results show a margin of less than 10 percent. 

4.3 BART DETERMINATION FOR SO2 FROM THE CALCIMATIC KILN

The calcimatic kiln at Chemstone is not currently operating but could operate in the future. This kiln 

is already equipped with a wet scrubber for PM with coincidental SO2 control. 

4.3.1 STEP 1: IDENTIFICATION OF AVAILABLE RETROFIT SO2 CONTROL 

TECHNOLOGIES

Step 1 of the BART determination is the identification of all available retrofit SO2 control 

technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air 

Technology Center, publicly-available air permits, applications, and technical literature published by 

the U.S. EPA, state agencies, and Regional Planning Organizations (RPOs). The available retrofit 

SO2 control technologies are summarized in Table 4-7. 

TABLE 4-7: AVAILABLE SO2 CONTROL TECHNOLOGIES

SO2 Control Technologies 

Wet Scrubbing 

Inherent Dry Scrubbing (Process) 

Semi-Wet Scrubbing 

4.3.2 STEP 2: ELIMINATE TECHNICALLY INFEASIBLE SO2 CONTROL TECHNOLOGIES

Step 2 of the BART determination is to eliminate technically infeasible SO2 control technologies that 

were identified in Step 1. Each technology was reviewed for its technical feasibility on the Calcimatic 

kiln at the Strasburg plant. Each of the aforementioned technologies is technically feasible. 

 15 Based on the available information from the recent testing and study of the process variables available, 

Chemstone believes that a compliance margin of 20% over the recently tested value provides a reasonable limitation for this 

source. 
SO2 BART Determination Addendum 4-9 Trinity Consultants 

O-N Minerals (Chemstone) 

4.3.3 STEP 3: RANK OF TECHNICALLY FEASIBLE SO2 CONTROL OPTIONS BY 

EFFECTIVENESS

The third step in the BART analysis is to rank the technically feasible options according to 

effectiveness. Table 4-8 presents potential SO2 technically feasible control technologies for the kiln 

and the associated SO2 emission levels. 

TABLE 4-8: RANKING OF TECHNICALLY FEASIBLE KILN SO2 CONTROL TECHNOLOGIES BY 

EFFECTIVENESS – CALCIMATIC KILN

Pollutant Control Technology 

Expected 

Control 

Efficiency 

Wet Scrubbing (Base Case) Up to 95% 

SO2 Spray Dryer Adsorber (Semi-Wet Scrubbing) Up to 90% 

Inherent Dry Scrubbing (Process, Base Case) < 80% 

4.3.4 STEP 4: EVALUATE FEASIBLE SO2 (TOP-DOWN) 

Step four for the BART analysis procedure is the impact analysis. As Chemstone already employs the 

“top” technology, it is considered BART and no further analysis is necessary. 

4.3.5 STEP 5: EVALUATION OF VISIBILITY IMPACT OF FEASIBLE SO2 CONTROLS 

As BART is considered the base case, there was no need to conduct further modeling to assess visibility 

improvement. Regardless, the impacts of SO2 from the Calcimatic kiln are trivial as detailed in the 

original BART Applicability Analysis and BART Determination. 

4.3.6 PROPOSED BART FOR SO2

Based on the five step analysis outlined by EPA, the base case (wet scrubbing) is BART. We propose 

that the BART limit for SO2 from the Calcimatic kiln mirror the existing Title V permit requirements. 
SO2 BART Determination Addendum Trinity Consultants 

O-N Minerals (Chemstone) 

APPENDIX A 

ECONOMIC EVALUATION CALCULATIONS 
Strasburg Plant Rotary Kiln at Actuals - Wet Scrubber

SO2 Emissions (tpy) 290

Airflow (acfm) 110456

Current Modeled Visibility Impact (deciview) 0.80

Average Modeled Visibility Improvement (deciview) 0.04

Direct Costs

Purchased Equipment Costs

Wet Scrubber Unit* $3,248,445

Instrumentation (10% of EC) $324,844

Sales Tax (3% of EC) $97,453

Freight (5% of EC) $162,422

Subtotal, Purchased Equipment Cost (PEC) $3,833,165

Direct Installation Costs **Handling and Erection included in wet scrubber cost - Cricket

Foundation (6% of PEC) $229,990

Supports (6% of PEC) $229,990

Electrical (1% of PEC) $38,332

Piping (30% of PEC) $1,149,949

Insulation for Ductwork (1% of PEC) $38,332

Painting (1% of PEC) $38,332

Subtotal, Direct Installation Cost $1,724,924

Site Preparation N/A

Buildings N/A

Total Direct Cost $5,558,089

Indirect Costs

Engineering (8% of PEC) $306,653

Construction Fee (3% of PEC) $114,995

Construction and Field Expense (10% of PEC) $383,316

Start-up (1% of PEC) $38,332

Performance Test (1% of PEC) $38,332

Total Indirect Cost $881,628

Total Direct and Indirect Costs (TDIC) $6,439,717

Contingency (10% of TDIC) $643,972

Total Capital Investment (TCI) $7,083,688

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Actuals - Wet Scrubber

Page (2 of 2)

Direct Annual Costs

Hours per Year (365 days per year, 24 hours per day) 8,760

Operating Labor

Operator (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Supervisor (15% of operator) $1,314

Subtotal, Operating Labor $10,074

Maintenance

Labor (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Material (100% of maintenance labor) $8,760

Subtotal, Maintenance $17,520

Variable O & M 

Electricity

Pump (kW) 422.33

Cost ($/kW-hr) $0.0624

Subtotal, Electricity $230,856

Limestone Slurry

Amount Required (ton/yr) 481

Cost ($/ton) $15.00

Subtotal, Lime $7,209

Subtotal, Variable O & M $238,065

Total Direct Annual Costs $265,659

Indirect Annual Costs

Overhead (60% of sum of operating, supervisor, maintenance labor & materials) $20,882

Administrative (2% TCI) $141,674

Property Tax (1% TCI) $70,837

Insurance (1% TCI) $70,837

Capital Recovery (10 year life, 9 percent interest) $1,103,781

Total Indirect Annual Cost $1,408,010

Total Annualized Cost $1,673,669

Pollutant Emission Rate Prior to Scrubber (tons SO2/yr) 290

Pollutant Removed (tons SO2/yr) assuming 80% removal 232

Cost Per Ton of Pollutant Removed $7,226

Current modeled visibility impact (deciview) 0.80

Average modeled visibility improvement (deciview) 0.04

Cost per deciview improvement $41,841,732

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Actuals - Semi-Wet Scrubber

SO2 Emissions (tpy) 290

Airflow (acfm) 110456

Average Modeled Visibility Improvement (deciview) 0.04

Direct Costs

Purchased Equipment Costs

Dry Scrubber Unit* $2,522,532

Instrumentation (10% of EC) $252,253

Sales Tax (3% of EC) $75,676

Freight (5% of EC) $126,127

Subtotal, Purchased Equipment Cost (PEC) $2,976,587

Direct Installation Costs

Foundation (6% of PEC) $178,595

Supports (6% of PEC) $178,595

Handling and Erection (40% of PEC) $1,190,635

Electrical (1% of PEC) $29,766

Piping (30% of PEC) $892,976

Insulation for Ductwork (1% of PEC) $29,766

Painting (1% of PEC) $29,766

Subtotal, Direct Installation Cost $2,530,099

Site Preparation N/A

Buildings N/A

Total Direct Cost $5,506,687

Indirect Costs

Engineering (10% of PEC) $297,659

General Facilities (10% of PEC) $297,659

Construction and Field Expense (10% of PEC) $297,659

Start-up (1% of PEC) $29,766

Performance Test (1% of PEC) $29,766

Total Indirect Cost $952,508

Total Direct and Indirect Costs (TDIC) $6,459,195

Contingency (10% of TDIC) $645,919

Total Capital Investment (TCI) $7,105,114

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Actuals - Semi-Wet Scrubber

Page (2 of 2)

Direct Annual Costs

Hours per Ye(365 days per year, 24 hours per day) 8,760

Operating Labor

Operator (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Supervisor (15% of operator) $1,314

Subtotal, Operating Labor $10,074

Maintenance

Labor (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Material (100% of maintenance labor) $8,760

Subtotal, Maintenance $17,520

Variable O & M

Electricity

Pump (kW) 422.33

Cost ($/kW-hr) $0.0624

Subtotal, Electricity $230,856

Trona (Reagent)

Amount Required (ton/yr) 3,290

Cost ($/ton) $160.00

Subtotal, Lime $526,454

Subtotal, Variable O & M $757,310

Total Direct Annual Costs $784,904

Indirect Annual Costs

Overhead (60% of sum of operating, supervisor, maintenance labor & materials) $332,429

Administrative (2% TCI) $142,102

Property Tax (1% TCI) $71,051

Insurance (1% TCI) $71,051

Capital Recov(10 year life, 9 percent interest) $1,107,119

Total Indirect Annual Cost $1,723,753

Total Annualized Cost $2,508,657

Pollutant Emission Rate Prior to Scrubber (tons SO2/yr) 290

Pollutant Removed (tons SO2/yr) assuming 80% removal 232

Cost Per Ton of Pollutant Removed $10,831

Average modeled visibility improvement (deciview) 0.04

Cost per deciview improvement $62,716,422

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Proposed Limit - Wet Scrubber

SO2 Emissions (tpy) 347

Airflow (acfm) 110456

Average Modeled Visibility Improvement (deciview) 0.06

Direct Costs

Purchased Equipment Costs

Wet Scrubber Unit* $3,248,445

Instrumentation (10% of EC) $324,844

Sales Tax (3% of EC) $97,453

Freight (5% of EC) $162,422

Subtotal, Purchased Equipment Cost (PEC) $3,833,165

Direct Installation Costs **Handling and Erection included in wet scrubber cost - Cricket

Foundation (6% of PEC) $229,990

Supports (6% of PEC) $229,990

Electrical (1% of PEC) $38,332

Piping (30% of PEC) $1,149,949

Insulation for Ductwork (1% of PEC) $38,332

Painting (1% of PEC) $38,332

Subtotal, Direct Installation Cost $1,724,924

Site Preparation N/A

Buildings N/A

Total Direct Cost $5,558,089

Indirect Costs

Engineering (8% of PEC) $306,653

Construction Fee (3% of PEC) $114,995

Construction and Field Expense (10% of PEC) $383,316

Start-up (1% of PEC) $38,332

Performance Test (1% of PEC) $38,332

Total Indirect Cost $881,628

Total Direct and Indirect Costs (TDIC) $6,439,717

Contingency (10% of TDIC) $643,972

Total Capital Investment (TCI) $7,083,688

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Proposed Limit - Wet Scrubber

Page (2 of 2)

Direct Annual Costs

Hours per Year (365 days per year, 24 hours per day) 8,760

Operating Labor

Operator (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Supervisor (15% of operator) $1,314

Subtotal, Operating Labor $10,074

Maintenance

Labor (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Material (100% of maintenance labor) $8,760

Subtotal, Maintenance $17,520

Variable O & M 

Electricity

Pump (kW) 422.33

Cost ($/kW-hr) $0.0624

Subtotal, Electricity $230,856

Limestone Slurry

Amount Required (ton/yr) 577

Cost ($/ton) $15.00

Subtotal, Lime $8,651

Subtotal, Variable O & M $239,507

Total Direct Annual Costs $267,101

Indirect Annual Costs

Overhead (60% of sum of operating, supervisor, maintenance labor & materials) $21,747

Administrative (2% TCI) $141,674

Property Tax (1% TCI) $70,837

Insurance (1% TCI) $70,837

Capital Recovery (10 year life, 9 percent interest) $1,103,781

Total Indirect Annual Cost $1,408,875

Total Annualized Cost $1,675,976

Pollutant Emission Rate Prior to Scrubber (tons SO2/yr) 347

Pollutant Removed (tons SO2/yr) assuming 80% removal 278

Cost Per Ton of Pollutant Removed $6,030

Average modeled visibility improvement (deciview) 0.06

Cost per deciview improvement $27,932,936

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Proposed Limit - Semi-Wet Scrubber

SO2 Emissions (tpy) 347

Airflow (acfm) 110456

Average Modeled Visibility Improvement (deciview) 0.06

Direct Costs

Purchased Equipment Costs

Dry Scrubber Unit* $2,522,532

Instrumentation (10% of EC) $252,253

Sales Tax (3% of EC) $75,676

Freight (5% of EC) $126,127

Subtotal, Purchased Equipment Cost (PEC) $2,976,587

Direct Installation Costs

Foundation (6% of PEC) $178,595

Supports (6% of PEC) $178,595

Handling and Erection (40% of PEC) $1,190,635

Electrical (1% of PEC) $29,766

Piping (30% of PEC) $892,976

Insulation for Ductwork (1% of PEC) $29,766

Painting (1% of PEC) $29,766

Subtotal, Direct Installation Cost $2,530,099

Site Preparation N/A

Buildings N/A

Total Direct Cost $5,506,687

Indirect Costs

Engineering (10% of PEC) $297,659

General Facilities (10% of PEC) $297,659

Construction and Field Expense (10% of PEC) $297,659

Start-up (1% of PEC) $29,766

Performance Test (1% of PEC) $29,766

Total Indirect Cost $952,508

Total Direct and Indirect Costs (TDIC) $6,459,195

Contingency (10% of TDIC) $645,919

Total Capital Investment (TCI) $7,105,114

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007
Strasburg Plant Rotary Kiln at Proposed Limit - Semi-Wet Scrubber

Page (2 of 2)

Direct Annual Costs

Hours per Ye(365 days per year, 24 hours per day) 8,760

Operating Labor

Operator (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Supervisor (15% of operator) $1,314

Subtotal, Operating Labor $10,074

Maintenance

Labor (0.5 hr/shift, 3 shifts/day, 365 d/yr, $16/hr) $8,760

Material (100% of maintenance labor) $8,760

Subtotal, Maintenance $17,520

Variable O & M

Electricity

Pump (kW) 422.33

Cost ($/kW-hr) $0.0624

Subtotal, Electricity $230,856

Trona (Reagent)

Amount Required (ton/yr) 3,290

Cost ($/ton) $160.00

Subtotal, Lime $526,454

Subtotal, Variable O & M $757,310

Total Direct Annual Costs $784,904

Indirect Annual Costs

Overhead (60% of sum of operating, supervisor, maintenance labor & materials) $332,429

Administrative (2% TCI) $142,102

Property Tax (1% TCI) $71,051

Insurance (1% TCI) $71,051

Capital Recov(10 year life, 9 percent interest) $1,107,119

Total Indirect Annual Cost $1,723,753

Total Annualized Cost $2,508,657

Pollutant Emission Rate Prior to Scrubber (tons SO2/yr) 347

Pollutant Removed (tons SO2/yr) assuming 80% removal 278

Cost Per Ton of Pollutant Removed $9,026

Average modeled visibility improvement (deciview) 0.06

Cost per deciview improvement $41,810,948

ON Minerals - Strasburg, VA

SO2 BART Determination

November 2007