## ATTACHMENT I

November 30, 2007 revised SO2 BART proposal

(cover letter dated 12/05/07 )

## B EST 

## A VAILABLE 

## R ETROFIT 

## T ECHNOLOGY 

## D ETERMINATION 

## O-N M INERALS 

## (C HEMSTONE 

## )  S TRASBURG 

## , V IRGINIA

A DDENDUM TO A DDRESS U PDATED SO 2 E MISSION R ATES

Prepared by:

T RINITY C ONSULTANTS 5320 Spectrum Drive Suite A Frederick, MD 21703 (240) 379-7490

November 2007

Project 062101.0055SO 2 BART Determination Adde ndum i Trinity Consultants O-N Minerals (Chemstone) 

## T ABLE OF 

## C ONTENTS



### 1. E XECUTIVE 

### S UMMARY 

### ........................................................................................ 1-1

2. I NTRODUCTION AND 

### B ACKGROUND 

### .................................................................... 2-1

3. R EVISED 

### BART E XEMPTION 

### M ODELING 

### ........................................................... 3-1

4. SO 2 B ART 

### E VALUATION 

### ..................................................................................... 4-1 4.1 F ORMATION OF 

### SO 2 FROM 

### L IME 

### K ILNS 

### ................................................................ 4-1 4.2 BART D ETERMINATION FOR 

### SO 2 FROM THE 

### R OTARY 

### K ILN 

### ................................. 4-2 4.2.1 S TEP 1: I DENTIFICATION OF A VAILABLE R ETROFIT SO 2 C ONTROL T ECHNOLOGIES ................................................................................................................4-2 4.2.2 S TEP 2: E LIMINATE T ECHNICALLY I NFEASIBLE SO 2 C ONTROL T ECHNOLOGIES 4-3 4.2.3 S TEP 3: R ANK OF T ECHNICALLY F EASIBLE SO 2 C ONTROL O PTIONS BY E FFECTIVENESS ................................................................................................................4-3 4.2.4 S TEP 4: E VALUATE F EASIBLE SO 2 (T OP -D OWN ) ...............................................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 S TEP 5: E VALUATION OF V ISIBILITY I MPACT OF F EASIBLE SO 2 C ONTROLS ......4-5 4.2.6 C OMPARISON TO D ATA FROM O THER P REHEATER R OTARY L IME K ILNS ..........4-6 4.2.7 P ROPOSED BART FOR SO 2 .................................................................................4-8 

### 4.3 BART D ETERMINATION FOR 

### SO 2 FROM THE 

### C ALCIMATIC 

### K ILN 

### .......................... 4-8 4.3.1 S TEP 1: I DENTIFICATION OF A VAILABLE R ETROFIT SO 2 C ONTROL T ECHNOLOGIES ................................................................................................................4-8 4.3.2 S TEP 2: E LIMINATE T ECHNICALLY I NFEASIBLE SO 2 C ONTROL T ECHNOLOGIES 4-8 4.3.3 S TEP 3: R ANK OF T ECHNICALLY F EASIBLE SO 2 C ONTROL O PTIONS BY E FFECTIVENESS ................................................................................................................4-9 4.3.4 S TEP 4: E VALUATE F EASIBLE SO 2 (T OP -D OWN ) ...............................................4-9 4.3.5 S TEP 5: E VALUATION OF V ISIBILITY I MPACT OF F EASIBLE SO 2 C ONTROLS ......4-9 4.3.6 P ROPOSED BART FOR SO 2 .................................................................................4-9



### A PPENDIX 

### ASO 2 BART Determination Adde ndum ii Trinity Consultants O-N Minerals (Chemstone) 

## L IST OF 

## T ABLES

T ABLE 3-1: E MISSION R ATES FROM C HEMSTONE ’ S O PERATIONS ......................................................3-2

T ABLE 3-2: V ISIBILITY IMPACTS AT S HENANDOAH N ATIONAL P ARK A SSOCIATED WITH C HEMSTONE ’ S O PERATIONS ...................................................................................................3-3

T ABLE 4-1: E XISTING H IGHEST A CTUAL SO 2 E MISSION R ATES ........................................................4-1

T ABLE 4-2: A VAILABLE SO 2 C ONTROL T ECHNOLOGIES ....................................................................4-2

T ABLE 4-3: R ANKING OF T ECHNICALLY F EASIBLE K ILN SO 2 C ONTROL T ECHNOLOGIES BY E FFECTIVENESS

– R OTARY K ILN ............................................................................................4-3

T ABLE 4-4: S UMMARY OF E MISSION R ATES M ODELED I N SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

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

T ABLE 4-5: S UMMARY OF M ODELED I MPACTS FROM SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

– R OTARY K ILN O NLY @ H IGHEST A CTUAL V ALUE ................................................................4-6

T ABLE 4-6: S UMMARY OF M ODELED I MPACTS FROM SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

– R OTARY K ILN O NLY @ P ROPOSED L IMITATION ....................................................................4-6

T ABLE 4-7: RBLC S EARCH R ESULTS FOR R OTARY L IME K ILNS ........................................................4-7

T ABLE 4-7: A VAILABLE SO 2 C ONTROL T ECHNOLOGIES ....................................................................4-8

T ABLE 4-8: R ANKING OF T ECHNICALLY F EASIBLE K ILN SO 2 C ONTROL T ECHNOLOGIES BY E FFECTIVENESS

– C ALCIMATIC K ILN .....................................................................................4-9SO 2 BART Determination Addendum 1-1 Trinity Consultants O-N Minerals (Chemstone) 

## 1. E XECUTIVE 

## S UMMARY

O-N Minerals (Chemstone) operates a lime manufactur ing facility in Strasburg, Virginia (Strasburg facility). This report provides a revised sulfur dioxide (SO 2 ) Best Available Retrofit Technology (BART) determination report. As we have discussed with the Virginia Department of Environmental Quality (DEQ), Chemstone has proactively reevaluated SO 2 emissions from the rotary kiln. P rior submittals and discussions regarding BART for our facility were based on prior testing which had indicated that the facility would meet the de minim i s emissions criteria for SO 2 . However, recent stack test data obtained in October 2007 indicates that the facility does not qualify as a de minim i s BART source for SO 2 . 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 SO 2 emissions from the Rotary Kiln, which already incorporates a baghouse. Sulfur dioxide emissions from the other SO 2 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 SO 2 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 SO 2 :

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 per cent reduction from the rotary kiln’s currently allowed SO 2 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. Th is emission rate is the same one currently contained in the Strasburg plant’s Title V operating permit.

1 Global Stone Chemstone Corporation (cur rently O-N Minerals), Statement of Legal and Factua l Basis, Permit No. VRO80252, page 18.SO 2 BART Determination Addendum 2-1 Trinity Consultants O-N Minerals (Chemstone) 

## 2. I NTRODUCTION AND 

## B ACKGROUND

O-N Minerals (Chemstone) operates a lime manufactur ing facility in Strasburg, Virginia (Strasburg plant). Chemstone is currently operating in accord ance 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 Anal ysis 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 t esting at the Strasburg plant has shown SO 2 emission are not de minim i s requiring Chemstone to submit this addendum to the BART determination filed earlier this year. Accordingly, Chemstone has re-examined the BART Determination for SO 2 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.SO 2 BART Determination Addendum 3-1 Trinity Consultants O-N Minerals (Chemstone) 

## 3. R EVISED 

## BART E XEMPTION 

## M ODELING

A BART-eligible source is subject to BART if th e 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 98 th 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 c onducted 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 SO 2 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 m odeling 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, date d November 13, 2007 to Ian Donaldson, Trinity Consultants. Note that none of the CALPUFF model options have been altered from the previously conduct ed modeling. Only the emission rates were updated.SO 2 BART Determination Addendum 3-2 Trinity Consultants O-N Minerals (Chemstone) T ABLE 3-1: E MISSION R ATES FROM C HEMSTONE ’ S O PERATIONS

Pollutant Modeled Size Range Rotary Kiln Calcimatic Kiln Category ( μ m) (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

SO 4 -- 0.13 0.28
NO X -- 80.2 7.20
SO 2 -- 66.10 0.04SO 2 BART Determination Addendum 3-3 Trinity Consultants O-N Minerals (Chemstone) T ABLE 3-2: V ISIBILITY IMPACTS AT S HENANDOAH N ATIONAL P ARK A SSOCIATED WITH C HEMSTONE ’ S O PERATIONS

Natural Background Method Ranked 2001 ∆ dv Ranked 2002 ∆ dv Ranked 2003 ∆ dv Maximum 8 th -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 0.803 4 (8, 45)

4 At the proposed SO 2 emission limitation the maximum 8 th high total impact is estima ted to be 0.837 dv. This new impact was determined by conservatively assuming that the additional SO 2 will become sulfate by the time the modeled plume reaches Shenandoah and scaling the portion of the visibility impact due to sulfates.SO 2 BART Determination Addendum 4-1 Trinity Consultants O-N Minerals (Chemstone) 

## 4. SO 2 

## B ART 

## E VALUATION

The section of the report provides the step-by-step analysis of the case-specific BART determination for SO 2 emission units at the Strasburg plant. As di scussed in the initial BART determination report, the SO 2 emissions from the raw material calcimatic kiln system are very small compared to the SO 2 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.

T ABLE 4-1: E XISTING H IGHEST A CTUAL SO 2 E MISSION R ATES

Equipment Maximum Annual Average Emission Rate (lb/hr) Maximum Annual Emission Rate (tpy)

Rotary 5 66.1 289.5

Calcimatic 6 7.52 31.7



## 4.1 F ORMATION OF 

## SO 2 FROM 

## L IME 

## K ILNS
Sulfur dioxide (SO 2 ) is emitted from the kilns as a result of the combustion of fuel which contains sulfur and from volatilization of trace amounts of sulf ur from the limestone. Fuel is burned in the lime kilns to provide the necessary heat for the reac tion of converting limest one (calcium carbonate, CaCO 3 ) to lime (calcium oxide , CaO) and carbon dioxide (CO 2 ). The reaction is characterized as follows:

CaCO 3 → CaO + CO 2

Sulfur present in the fuel is oxidized to form SO 2 . Lime and limestone present in the kiln act as a natural scrubber for sulfur dioxide. Most commercially available wet and dry SO 2 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 + SO 2 → CaSO 3 + 1⁄2 O 2 → CaSO 4

In essence, the entire kiln acts as a dry scrubber for SO 2 . Absorption of the SO 2 onto the solid particles occurs mainly in the kiln and the particul ate matter is collected in the baghouse. Inherent dry scrubbing in the lime production process typically reduces SO 2 emissions by greater than 90 percent for new preheater kiln systems.

5 Rotary kiln emissions are based on st ack testing performed October 30, 2007.

6 Calcimatic kiln emissions are based on current Title V Operating Permit limitations.SO 2 BART Determination Addendum 4-2 Trinity Consultants O-N Minerals (Chemstone) SO 2 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 pro cess approximately 1,200 tons of limestone per day 7 . 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. Str ong oxidation in the kiln will drive the oxidation of sulfur to monosulfate (SO 3 ) rather than SO 2 . SO 3 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 se cond kiln which is an unusual kiln type – a calcimatic kiln. This kiln does not have the benefits of SO 2 removal like a preheater rotary kiln. However, Chemstone’s calcima tic kiln is equipped with a scrubbing device that helps reduce SO 2 emissions.

Even with this understanding, kilns are dynamic proc ess 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 D ETERMINATION FOR 

## SO 2 FROM THE 

## R OTARY 

## K ILN
The rotary kiln system at Chemstone consists of two BART-eligible emissions units: the Rotary kiln and a Product Cooler. 8 As SO 2 emissions do not occur from the Produc t Cooler, the Rotary kiln is the emission unit being reviewed in this section. The rota ry kiln at Strasburg is a preheater-type kiln that is controlled by a positive pressure, multi-stack baghouse.



### 4.2.1 S TEP 

### 1: I DENTIFICATION OF 

### A VAILABLE 

### R ETROFIT 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES
Step 1 of the BART determination is the identification of all available retrofit SO 2 control technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air Technology Center, publicly-availabl e air permits, applications, and technical literature published by the U.S. EPA, state agencies, and Regional Planning Organizations (RPOs). The available retrofit SO 2 control technologies are summarized in Table 4-2.

T ABLE 4-2: A VAILABLE SO 2 C ONTROL T ECHNOLOGIES

SO 2 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-e ligible emission units from the Strasburg plant.SO 2 BART Determination Addendum 4-3 Trinity Consultants O-N Minerals (Chemstone) 

### 4.2.2 S TEP 

### 2: E LIMINATE 

### T ECHNICALLY 

### I NFEASIBLE 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES
Step 2 of the BART determination is to eliminate technically infeasible SO 2 control technologies that were identified in Step 1. Each technology was re viewed for its technical feasibility on the Rotary kiln at the Strasburg plant. Each of the aforementioned technologies is technically feasible.



### 4.2.3 S TEP 

### 3: R ANK OF 

### T ECHNICALLY 

### F EASIBLE 

### SO 2 

### C ONTROL 

### O PTIONS BY 

### E FFECTIVENESS
The third step in the BART analysis is to rank the technically feasible options according to effectiveness. Table 4-3 presents potential SO 2 technically feasible control technologies for the kiln and the associated SO 2 emission levels.

T ABLE 4-3: R ANKING OF T ECHNICALLY F EASIBLE K ILN SO 2 C ONTROL T ECHNOLOGIES BY E FFECTIVENESS

– R OTARY K ILN

Pollutant Control Technology Expected Control Efficiency

Wet Scrubbing with Lime Up to 98%
Inherent Dry Scrubbing (Process, Base Case) 75 to 92% SO 2 Semi-Wet Scrubbing (Spray Dryer Absorber) Up to 90%



### 4.2.4 S TEP 

### 4: E VALUATE 

### F EASIBLE 

### SO 2 

### (T OP 

### -D OWN 

### )
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 f actor for the source is not an issue.



### 4.2.4.1 W ET 

### S CRUBBING WITH 

### L IME

Wet SO 2 scrubbers operate by flowing the flue g as 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 r eagent, using a series of spray nozzles to distribute the reagent across the scrubber vessel. The calcium in the reagent reacts with the SO 2 in the flue gas to form calcium sulfite a nd/or calcium sulfate that is removed from the scrubber with the sludge and is disposed. Most wet scrubbing sy stems utilize forced oxidation to assure that only calcium sulfate sludge is produced.SO 2 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 wei ght 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 wate r droplets, generation of particulate matter by the scrubbing process causing elevated opacity, water consumption, and wastewater and sludge disposal issues. Finally, a wet syst em will cost about $7,226 per ton of SO 2 removed. 9 The detailed cost analysis is included in Appendix A. Therefore, based on the unacceptable environmental and economic imp acts, wet scrubbing will not be considered further and does not constitute BART.



### 4.2.4.2 I NHERENT 

### D RY 

### S CRUBBING 

### (P ROCESS 

### )
Inherent dry scrubbing in the lime produc tion process normally provides around 90 percent removal (in new modern preheater kilns) of SO 2 at no further energy, environmental, or economic impacts, since it occurs naturally in the system proposed. In a lime kiln, SO 2 that is released during the lime formation process will react with the lime. The amount of SO 2 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 scr ubbing is an integral part of the process system, it is considered the base case for BART.



### 4.2.4.3 S EMI 

### –W ET 

### S CRUBBING 

### (S PRAY 

### D RYER 

### A BSORBER 

### )
Spray dryer systems operate by injecting a moist sorbent into the scrubber. As the hot flue gas mixes with the sorbent, water is evaporat ed. 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 SO 2 . 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.SO 2 BART Determination Addendum 4-5 Trinity Consultants O-N Minerals (Chemstone) Therefore, the system would provide for a re moval 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 SO 2 removed. 12
This cost is above what is considered r easonable. Therefore, semi-wet scrubbing is considered economically infeasible for SO 2 control and is not BART.



### 4.2.5 S TEP 

### 5: E VALUATION OF 

### V ISIBILITY 

### I MPACT OF 

### F EASIBLE 

### SO 2 

### C ONTROLS
An impact analysis was conducted to assess the visi bility 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 ra tes and the emission rates when one of the two control levels were modele d using CALPUFF. The SO 2 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.

T ABLE 4-4: S UMMARY OF E MISSION R ATES M ODELED I N SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

Emission Rate Scenario SO 2 Emission Rate Highest Actual (lb/hr) SO 2 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 ex isting 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 “the oretical” reductions as if the kiln emitted at the proposed permit limit continuously. The visibility im provement associated with these options is also provided in the same table. This value was calcul ated as the difference between the existing visibility impairment and the visibility impairment for the controlled emission rates as measured by the 98 th percentile modeled visibility impact.

12 Annualized costs would be approximately $9, 026 based on the proposed permit limit.SO 2 BART Determination Addendum 4-6 Trinity Consultants O-N Minerals (Chemstone) T ABLE 4-5: S UMMARY OF M ODELED I MPACTS FROM SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

– R OTARY K ILN O NLY @ H IGHEST A CTUAL V ALUE

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%

T ABLE 4-6: S UMMARY OF M ODELED I MPACTS FROM SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

– R OTARY K ILN O NLY @ P ROPOSED L IMITATION 13

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 SO 2 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 C OMPARISON TO 

### D ATA FROM 

### O THER 

### P REHEATER 

### R OTARY 

### L IME 

### K ILNS
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 SO 2 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 va lues 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 pr oposed limit were determined by conservatively assuming that the additional SO 2 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 produ ced at the proposed limitation.SO 2 BART Determination Addendum 4-7 Trinity Consultants O-N Minerals (Chemstone) T ABLE 4-7: RBLC S EARCH R ESULTS FOR R OTARY L IME K ILNS

Facility Permit Date (from RBLC) Lime Production Capacity (tpd) Permitted SO 2 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 SO 2 limits are within range of existing BACT approved ranges, despite the vintage of the rotary kiln when compared to newer ro tary lime kilns and regardless of whether the value being compared is a limit based on stone feed or lime produced.SO 2 BART Determination Addendum 4-8 Trinity Consultants O-N Minerals (Chemstone) 

### 4.2.7 P ROPOSED 

### BART FOR 

### SO 2 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 s ubject Class I area. For these reasons, Chemstone proposes a BART permit limit as follows.

The rotary kiln will meet a limit of 7 9

. 3 lb/hr of SO 2 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 test s 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 D ETERMINATION FOR 

## SO 2 FROM THE 

## C ALCIMATIC 

## K ILN
The calcimatic kiln at Chemstone is not currently ope rating but could operate in the future. This kiln is already equipped with a wet scrubber for PM with coincidental SO 2 control.



### 4.3.1 S TEP 

### 1: I DENTIFICATION OF 

### A VAILABLE 

### R ETROFIT 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES
Step 1 of the BART determination is the identification of all available retrofit SO 2 control technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air Technology Center, publicly-availabl e air permits, applications, and technical literature published by the U.S. EPA, state agencies, and Regional Planning Organizations (RPOs). The available retrofit SO 2 control technologies are summarized in Table 4-7.

T ABLE 4-7: A VAILABLE SO 2 C ONTROL T ECHNOLOGIES

SO 2 Control Technologies

Wet Scrubbing

Inherent Dry Scrubbing (Process)

Semi-Wet Scrubbing



### 4.3.2 S TEP 

### 2: E LIMINATE 

### T ECHNICALLY 

### I NFEASIBLE 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES
Step 2 of the BART determination is to eliminate technically infeasible SO 2 control technologies that were identified in Step 1. Each technology wa s re view ed 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 te sting 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.SO 2 BART Determination Addendum 4-9 Trinity Consultants O-N Minerals (Chemstone) 

### 4.3.3 S TEP 

### 3: R ANK OF 

### T ECHNICALLY 

### F EASIBLE 

### SO 2 

### C ONTROL 

### O PTIONS BY 

### E FFECTIVENESS
The third step in the BART analysis is to rank the technically feasible options according to effectiveness. Table 4-8 presents potential SO 2 technically feasible control technologies for the kiln and the associated SO 2 emission levels.

T ABLE 4-8: R ANKING OF T ECHNICALLY F EASIBLE K ILN SO 2 C ONTROL T ECHNOLOGIES BY E FFECTIVENESS

– C ALCIMATIC K ILN

Pollutant Control Technology Expected Control Efficiency

Wet Scrubbing (Base Case) Up to 95%
Spray Dryer Adsorber (Semi-Wet Scrubbing) Up to 90% SO 2 Inherent Dry Scrubbing (Process, Base Case) < 80%



### 4.3.4 S TEP 

### 4: E VALUATE 

### F EASIBLE 

### SO 2 

### (T OP 

### -D OWN 

### )

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 S TEP 

### 5: E VALUATION OF 

### V ISIBILITY 

### I MPACT OF 

### F EASIBLE 

### SO 2 

### C ONTROLS
As BART is considered the base case, there wa s no need to conduct further modeling to assess visibility improvement. Regardless, the impacts of SO 2 from the Calcimatic kiln are trivial as detailed in the original BART Applicability Analysis and BART Determination.



### 4.3.6 P ROPOSED 

### BART FOR 

### SO 2 Based on the five step analysis outlined by EPA, the base case (wet scrubbing) is BART. We propose that the BART limit for SO 2 from the Calcimatic kiln mirror the existing Title V permit requirements.SO 2 BART Determination Adde ndum Trinity Consultants O-N Minerals (Chemstone) 

## A PPENDIX 

## A

E CONOMIC E VALUATION C ALCULATIONSStrasburg 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 2007Strasburg 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 SO 2 /yr) 290 Pollutant Removed (tons SO 2 /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 2007Strasburg 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 2007Strasburg Plant Rotary Kiln at Actuals - Semi-Wet Scrubber

Page (2 of 2)

Direct Annual Costs Hours per Y e (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 Reco v (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 SO 2 /yr) 290 Pollutant Removed (tons SO 2 /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 2007Strasburg 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 2007Strasburg 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 SO 2 /yr) 347 Pollutant Removed (tons SO 2 /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 2007Strasburg 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 2007Strasburg Plant Rotary Kiln at Proposed Limi t - Semi-Wet Scrubber

Page (2 of 2)

Direct Annual Costs Hours per Y e (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 Reco v (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 SO 2 /yr) 347 Pollutant Removed (tons SO 2 /yr) assuming 80% removal 278 Cost Per Ton of Pollutant Removed $9,026 Avera g e modeled visibilit y im p rovement ( deciview ) 0.06 Cost per deciview improvement $41,810,948

ON Minerals - Strasburg, VA SO2 BART Determination November 2007