## ANALYSIS FOR BEST AVAILABLE RETROFIT TECHNOLOGY –
EXEMPTION ANALYSIS
GEORGIA-PACIFIC CEDAR SPRINGS LLC

August 1, 2008 (Revised)Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc ii 1.0 INTRODUCTION

................................................... ................................................... ....... 3 1.1. Overview of the Regional Haze BART Process

................................................... ............ 3 1.2. Organization of the Report

................................................... ............................................ 5
2.0 SITE DESCRIPTION AND EMISSION INVENTORY .............................................. 6
3.0 VISTAS CONTRIBUTION TO CALPUFF MODELING ......................................... 13
4.0 MODEL DISCUSSION

................................................... ............................................... 14
4.1 General Procedures

................................................... ................................................. 14
4.2 CALPUFF Configuration

................................................... ........................................ 14
5.0 RESULTS AND DETERMINATION OF IMPAIRMENT ........................................ 20
5.1 Impact Threshold

................................................... ................................................... .. 20
5.2 Presentation of Modeling Results

................................................... ........................... 20Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 3 

### 1.0 INTRODUCTION

1.1. Overview of the Regional Haze BART Process
Under regional haze regulations, the Environmental Protection Agency (EPA) has issued final guidelines dated July 6, 2005 for Best Availa ble Retrofit Technology (BART) determinations (70 FR 39104-39172). The regional h aze rule includes a requirement for BART for certain large stationary sources, such as Georgia-Pacific Cedar Springs LLC’s (GP) pulp & paper facility in Cedar Springs, Georgi a. Sources are BART-eligible if they meet three criteria concerning (1) potential emissi ons of visibility-impairing pollutants, (2) the date when the source was put in operation, and (3) whether they fall within one of the source categories listed in the guidance. The guidance requires a BART engineering evaluation using five statutory factors for any BAR T-eligible source that can be reasonably expected to cause or contribute to impai rment of visibility in any Class I areas protected under the regional haze rule. (Note that , depending on the five factors, the evaluation may result in no control.) Air quality modeling is an important tool available
to the States to determine whether a source can be reasonably expected to contribute to visibility impairment in a Class I area.
The process of making a BART determination consists of four steps:

1) Identify whether a source is “BART-eligible” bas ed on its source category, when it was put in service, and the magnitude of its emi ssions of one or more “visibilityimpairing” air pollutants. The BART guidelines lis t 26 categories of stationary sources that are BART-eligible. Sources must have been put in service between August 7, 1962 and August 7, 1977. Finally, a sour ce is eligible for BART if potential emissions of visibility-impairing air pol lutants are greater than 250 tons per year. Qualifying pollutants include primary pa rticulate matter (PM 10 ) and gaseous precursors to secondary fine particulate ma tter, such as SO 2 and NO x . Georgia Environmental Protection Division (EPD) has determined that neither ammonia nor volatile organic compounds (VOCs) shoul d be included as visibilityimpairing pollutants for BART eligibility.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 4 2) Determine whether a BART-eligible source can be excluded from BART controls by demonstrating that the source cannot be reasonably expected to cause or contribute to visibility impairment in a Class I ar ea. The preferred approach is an assessment with an air quality model such as CALPUF F or other appropriate model followed by comparison of the estimated 24-hour vis ibility impacts against a
threshold above estimated natural conditions to be determined by the States. The threshold to determine whether a single source “cau ses” visibility impairment is set at 1.0 deciview (dv) change from natural conditions over a 24-hour averaging period in the final BART rule (70 FR 39118). The g uidance also states that the proposed threshold at which a source may “contribut e” to visibility impairment should not be higher than 0.5 dv although, dependin g on factors affecting a specific Class I area, it may be set lower than 0.5 dv. The test against the threshold is “driven” by the contribution level, since if a sour ce “causes”, by definition it
“contributes”.
3) Determine BART controls for the source by consi dering various control options and selecting the “best” alternative, taking into c onsideration:

a) Any pollution control equipment in use at the s ource (which affects the availability of options and their impac ts),
b) The costs of compliance with control options,
c) The remaining useful life of the facility,

d) The energy and non air-quality environmental im pacts of compliance, and
e) The degree of improvement in visibility that ma y reasonably be anticipated to result from the use of such technolo gy.
If a source agrees to apply the most stringent cont rols available to BART-eligible units, the BART analysis is essentially complete an d no further analysis is necessary (70 FR 39165).Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 5 4) Incorporate the BART determination into the Sta te Implementation Plan for Regional Haze.
Step 2 described above reflects 40 CFR Part 51 Appe ndix Y which states that an eligible
source “ can use dispersion modeling to determine that an in dividual source cannot reasonably be anticipated to cause or contribute to visibility impairment in a Class I area and thus is not subject to BART .” (70 FR 39162) This “individual source attributi on approach” determines if a BART-eligible source ( i.e., collection of eligible emission units at a source) is predicted to cause or contribute to visibility impairment in a Class I area. As mentioned above, a predicted impact of 1.0 dv ch ange or more is considered to “cause” visibility impairment, and a predicted impa ct of 0.5 dv change or more is considered to “contribute”. Any source determined t o cause or contribute to visibility impairment in any Class I area is subject to BART a nd will also complete additional visibility impact analyses.
1.2. Organization of the Report
Section 2 presents facility-specific information. Section 3 presents the contribution by VISTAS for the BART analyses. Section 4 summarizes the modeling approach, and model configuration. Section 5 presents the criteria and processing of model results to demonstrate what impairment, if any, the facility i s predicted to create in the Class I areas. The CALPUFF model input and output files are provid ed on electronic media enclosed with this report, a file index for which is present ed in the appendix.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 6 

### 2.0 SITE DESCRIPTION AND EMISSION INVENTORY
GP operates the Cedar Springs Mill in Early County. The facility is located in the southwestern portion of Georgia, approximately two miles west of the intersection of Highways 370 and 273, along the east bank of the Ch attahoochee River. The facility manufactures unbleached linerboard and corrugating medium with virgin pulp using both the Kraft and neutral sulfite semi-chemical (NSSC) processes. Additional pulp is produced from recycled fiber sources, specifically old corrugated containers (OCC) and double-lined Kraft clippings (DLK). The facility i s located in a rural area, with almost no residential areas are near the Mill. Figure 1 depi cts the location of the Mill and illustrates the adjacent terrain. Table 1 presents the BART-el igible emission unit inventory for the BART exemption analysis.

Table 1. Model Parameters for BART-Eligible Source s at GP Cedar Springs
LLC (km) ref: VISTAS Permit ID Source Description Stack Ht (ft) East North Elevation (ft) Stack Diameter (ft) Exit Velocity (ft/sec) Exit

Temp (deg F) R402N Recovery Boiler No. 3 247 1133.484 -905.071 1 17.1 9 44.7 413 R402S Recovery Boiler No. 3 247 1133.483 -905.075 1 17.1 9 44.7 413 R406 Smelt Dissolving Tank No. 3 247 1133.500 -905. 074 117.1 6 23.1 157 U500 Power Boiler No. 1 350 1133.491 -905.178 117.1 14.5 34.1 140 U501 Power Boiler No. 2 350 1133.501 -905.179 117.1 14.5 34.1 128 L600 Lime Kiln No. 1 82 1133.574 -904.843 117.1 6 3 1.7 170 L601 Lime Kiln No. 2 90 1133.558 -904.835 117.1 6 3 1.7 170

Table 2 presents the worst-case 24-hour average emi ssions for worst case 24-hr actual for existing sources submitted to EPD in July 2007. Em ission rates for the smelt dissolving tank and recovery boiler reflect actual operating h istory during the baseline years evaluated by the Mill. Other sources have been mod ified since the baseline period as
follows:

• Power Boiler 1 and 2 completed modifications in 200 7 and 2008 for an overfire air system (by Mobotec), new Foster&Wheeler Low-NOx burners and wetCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 7 scrubber improvements under existing permits. The Mill installed Continuous Emission Monitors (CEM) for sulfur dioxide and nitr ogen oxides on Power Boiler 1 and 2 over the past 24 months.

• Lime Kiln 1 and 2 completed modifications with a li me mud dryer in June 2007.
The mill installed a new wet scrubber on Lime Kiln 2 and accepted lower PM 10 emission rates for both kilns.

680500 681500 682500 683500 684500 685500 686500 UTM NAD83 E (m) Zone 16 Figure 1, Topographic Map of Cedar Springs and Vic inity

3446000 3447000 3448000 3449000 3450000 3451000 3452000UTMNAD83N(m)Zone16

The Mill has operated a CEM on Recovery Boiler No. 3 for sulfur dioxide periodically since November 2004 and nitrogen oxides for approxi mately 30 days in December 2006.
Short-term emissions of SO 2 ranged from near zero to above 250 parts per milli on (ppm). For periods when black liquor is fired continuously at capacity, the average daily
emission rates are lower.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 8 Table 2. Base Case Emissions Inventory of Cedar Spr ings Mill BART Sources, Prepared July 2007

24-hour Average Emission Rate (lb/hr) Emission Unit SO 2 NO x PM / PM 10 Lime Kiln Nos. 1 and 2 30 30.93 29.8 Recovery Furnace No. 3 120 85 52.2 Smelt Dissolving Tank 14.1 2.6 15.2 Power Boiler No. 1 1377 262 63 Power Boiler No. 2 1377 262 63
Total 2918 642.5 223.2

Since early 2007, the Mill has been developing cons truction plans and an air permit application for the evaporator and recovery areas. The list of modified equipment includes the evaporation stage prior to the recover y boiler. In considering recovery boiler physical modifications, the Mill reviewed the BACT limits for its other two existing recovery boilers. The current air permit limits SO 2 emissions for Recovery Boiler Nos. 1 and 2 to 300 ppm. In addition, the Mill has contin ued to operate a SO 2 CEM for Recovery Boiler No. 3. The additional CEM data sho ws that the maximum daily emissions in the current operations can exceed 200 ppm. However, the mill expects that after the proposed evaporator are repairs are compl eted, that the boiler will be consistently run with higher solids content and thu s more controllable for SO 2 emissions.

After discussions with EPD in September 2007, the M ill reviewed the hourly CEM data and the CALPUFF analyses. The Mill has determined that two operating scenarios are feasible following modifications to the evaporator, recovery and power boiler areas. These scenarios represent the range of SO 2 emission rates from the Recovery Boiler No. 3 and Power Boilers Nos. 1 and 2 that are being evaluated to demonstrate that the BART-eligible source at CSO does not cause or contr ibute to visibility impairment.

Scenario 1 - Improve evaporation and add caustic to existing wet scrubbers: Limit daily average Recovery Boiler No. 3 SO 2 emissions to 350 ppm whenCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 9 liquor is in the boiler. Limit daily average Power Boiler Nos. 1 and 2 SO 2 emissions to 135 lbs/hr each.

Scenario 2 – Improve combustion on Recovery Boiler No. 3 and add caustic to existing wet scrubbers: Limit daily average Recovery Boiler No. 3 SO 2 emissions to 90 ppm when liquor
is in the boiler Limit daily average Power Boiler Nos. 1 and 2 SO 2 emissions to 350 lbs/hr each.

Table 3 summarizes the emission rates for the two s cenarios.
Table 3. Alternate Operating Scenarios: Emissions Inventory of Cedar Springs Mill SO 2 Model ID (lbs / hr) Scenario 1: Power Boiler No. 1 U500 135 Power Boiler No. 2 U501 135 Recovery Boiler No. 3 – North Stack R402N 411 Recovery Boiler No. 3 – South Stack R402S 411 Subtotal 1,091

Scenario 2: Power Boiler No. 1 U500 350 Power Boiler No. 2 U501 350 Recovery Boiler No. 3 – North Stack R402N 106 Recovery Boiler No. 3 – South Stack R402S 106 Subtotal 911

Optional equipment modifications for Scenario 1 inc lude repaired concentrator sets, a new caustic day tank and control system with CEM fo r Power Boilers Nos. 1 and 2, and a new lift station to connect power boiler scrubber b lowdown to the waste water treatment system.

Optional equipment modifications for Scenario 2 inc lude new concentrator sets (potentially new evaporators and a crystallizer), a new multi-level air system for Recovery Boiler No. 3, a new caustic day tank and c ontrol system with CEM for PowerCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 10 Boilers Nos. 1 and 2, and a new lift station to con nect power boiler scrubber blowdown to the waste water treatment system. For normal opera ting times when liquor is in the boiler, Recovery Boiler No. 3 typically achieves th e emission rates under Scenario 2 using the existing equipment.

Tables 4 and 5 summarize the emission rates modeled in the two BART exemption scenarios on a tons per year and pound per hour bas is, respectively. SO 2 emissions represent potential emissions after the previously described modifications to the Recovery Boiler No. 3 and Power Boilers Nos. 1 and 2. SO 4 emissions are estimated as a percentage of the SO 2 mass emission rate based no the characteristics of fuel combusted
in each emission unit. NO X and PM 10 emissions represent allowable emissions established by enforceable Emission Caps, Federal R ule Standards, and SIP Rule Standards in the current Title V Operating Permit N o. 2631-099-0001-V-02-0 (February 21, 2007) and V-02-2 (April 18, 2007). A llowable emissions were modeled
instead of actual emissions to confirm that these o perating scenarios do not cause or contribute to visibility impairment and are therefo re exempt from BART.

Table 4. Summary of BART Exemption Scenarios Emission Rate (tpy) Scenario SO 2 SO 4 NO X PM 10 Base Case 12,781 569 2,814 978 Alternative Scenario 1 5,104 164 2,824 1,238 Alternative Scenario 2 4,136 166 2,824 1,238Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 11

Table 5. Summary of Modeled BART Exemption Alterna tive Scenarios 24-hour Average Emission Rate (lb/hr) Source SO 2 SO 4 * NO X PM 10 Smelt Dissolving Tank No. 3 47.0 0 2.6 45.0 Lime Kiln No. 1 13.54 0.32 14.06 29.8† Lime Kiln No. 2 16.25 0.36 16.87 29.8† Subtotal 76.8 0.68 33.53 104.6

Scenario 1 Recovery Boiler No. 3 – North 410.6 12.46 45 26.0 Recovery Boiler No. 3 – South 410.6 12.46 45 26.0 Power Boiler No. 1 135.0 5.94 262 63.0 Power Boiler No. 2 135.0 5.94 262 63.0

Scenario 2 Recovery Boiler No. 3 – North 105.6 3.20 45 26.0 Recovery Boiler No. 3 – South 105.6 3.20 45 26.0 Power Boiler No. 1 350.0 15.4 262 63.0 Power Boiler No. 2 350.0 15.4 262 63.0

Total Scenario 1 1167.9 37.5 647.5 282.6 Total Scenario 2 987.9 37.9 647.5 282.6
* SO 4 emissions are estimated as a fixed percentage of t he SO 2 mass emission rate based on the
characteristics of fuels combusted. The SO 4 /SO 2 fractions utilized are approximately 2.3% for lime kilns, 3.0% for recovery boilers, and 4.4% for power boilers. † PM 10 emissions from each lime kiln were conservatively modeled as the total allowable emission rate from both lime kilns (i.e., 17.62 lb/ hr for Lime Kiln No.1 and 12.28 lb/hr for Lime Kiln No. 2).

The analysis applied PM 10 speciation profiles provided by National Council f or Air & Stream Improvement 1 and the National Park Service 2 to determine emission rates for all other visibility affecting pollutants modeled in CA LPUFF. Table 6 presents speciated
emission rates for each emission unit. Note that t he speciation profile was applied using
the POSTUTIL module to the total PM 10 emission rate that was modeled in CALPUFF.

1 NCASI guidance document.

2 National Park Service PM 10 Speciation Profile for Utility Oil Boiler with Scr ubber, http://www.nature.nps.gov/air/permits/ect/ectOilFir edBoiler.cfmCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 12 Table 6. Characteristic PM 10 Speciation Profiles Source PMC PMF EC SOA Smelt Dissolving Tank 10.8% 81.3% 3.4% 4.2% Lime Kiln 8.9% 82.8% 3.4% 4.6% Recovery Boiler 27.3% 63.8% 2.7% 6.3% Power Boiler 3.6% 79.3% 6.3% 10.8%

Within 300 kilometers of the Mill two Class I Areas have been identified with visibility as an important air quality related value:

1. St. Marks National Wilderness Area (112 km from Mil l)
2. Okefenokee National Wilderness Area (244 km from Mi ll) Figure 2 presents a simplified map in the UTM NAD27 projection with the arrangement
of the Mill and the two Class I areas.

700 750 800 850 900 950

UTM East (km) Figure 2. Mandatory Class I Area Receptors within 300km of GP Cedar Springs

3350 3400 3450UTMNorth(km) CSO

Okefenokee

St. MarksCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 13 

### 3.0 VISTAS CONTRIBUTION TO CALPUFF MODELING For this application of BART Modeling, VISTAS and E PD have made available the following data bases developed by the VISTAS Techni cal Contractor:

• VISTAS version of the CALPUFF modeling system, main tained on the
VISTAS Technical Contractor website.

• 4-km CALMET output files for 2001, 2002, and 2003 p roduced as described
in the VISTAS Common Protocol.

• CALMET with a software modification to allow the me teorological data inputs into CALMET to be used to generate finer gri d CALMET files without having to go back to the original MM5 output files

• File with CALPUFF model configuration and settings sufficient to replicate CALPUFF modeling done for VISTAS using 12 km CALMET

.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 14 

### 4.0 MODEL DISCUSSION
4.1 General Procedures GP is beginning with the most refined dataset avail able from VISTAS. The fine grid analyses use the 98th percentile impact value for t he 24-hr average at each Class I area. The analysis will use either the 8th highest day in each year or the 22nd highest day in the 3-year period, whichever is more conservative.

The VISTAS Common Modeling Protocol consistently re commends conservative assumptions. Individual States ultimately have res ponsibility to determine which, if any, BART controls are recommended in their State Implem entation Plans (SIPs). The VISTAS protocol presents additional detailed inform ation on the meteorological fields, and specific settings for CALPUFF and CALPOST (see section 4.33 of the VISTAS Common Modeling Protocol).



### 4.2 CALPUFF Configuration Source emissions should be defined using the maximu m 24-hour actual emission rate during normal operation for the most recent 3 or 5 years. If maximum 24-hr actual emissions are not available, continuous emissions d ata, permit allowable emissions, potential emissions, and emissions factors from AP- 42 source profiles may be used as available. As described in Section 2 of this repor t, GP used allowable emissions to demonstrate that two alternative operating scenario s neither cause nor contribute to visibility impairment.

GP completed the analysis with the Domain #4 4-km r efined grid meteorological datasets provided by VISTAS. Figure 3 presents the modeling domain, the Class I Area model receptors and Mill.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 15

800 900 1000 1100 1200 1300 1400 1500 1600 1700 LCC East (km) Figure 3. CALPUFF Modeling Domain, Source and Rece ptors, GP Cedar Springs BART Analyses

-1200 -1100 -1000 -900 -800 -700 -600 -500 -400 -300 -200LCCNorth(km) Snow/Ice

Tundra

Barren

Wetland

Water

Forest

Range

Agriculture

Urban/Built-Up

Land Use 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 . .

. . GP Mill

St. Marks Okefenokee

The major features and options of the meteorologica l and dispersion model are
summarized and discussed in the VISTAS Common Model ing Protocol. Specific configuration settings presented in the VISTAS Comm on Modeling Protocol are listed
below:

• Use default data provided by VISTAS for background concentrations of SO 4 and
total NO 3 (HNO 3 + NO 3 ). GP utilized the more conservative default appro ach and also implemented the “ammonia limiting method” (ALM) with the POSTUTIL post-processor to re-partition the distrib ution of HNO 3 and NO 3 concentrations at each Class I area as a function o f the temperature, relative humidity, and free ammonia during each hour. ALM r e-partitioning using the default ammonia background level of 0.5 ppb was con ducted in refined analyses.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 16 • Use spatially- and temporally-variable hourly ozone data for observation stations within Domain 4 as prepared by VISTAS. A represent ative background value of 50 ppb was entered into CALPUFF to substitute durin g hours for which no valid ozone concentrations were measured throughout the d omain.

• Use the Pasquill-Gifford dispersion method.

• In CALPOST, use Method 6 with monthly average relat ive humidity for calculating extinction, as recommended by the EPA. Class I-area specific values of the relative humidity adjustment function were o btained from the U.S. EPA’s Guidance for Estimating Natural Visibility Conditio ns under the Regional Haze
Rule (EPA-454/B-03-005), October 2003.

• Use EPA default calculations of light extinction un der average background conditions. The annual average natural background conditions were obtained from Appendix B of U.S. EPA’s Guidance for Estimating Natural Visibility Conditions under the Regional Haze Rule and were used to calculate the monthly equivalent fine particle (as soil) background conce ntration for each of Okefenokee and St. Marks as shown in the following equations.

Okefenokee for Mm 40. 11 Mm 10 Mm 40.1 2 10 61.7 exp 10 1 1 1

− − − = ⇒ + = + = =      

= soil soil soil ray back b b b b b

Marks St. for Mm 53. 11 Mm 10 Mm 53.1 2 10 67.7 exp 10 1 1 1

− − − = ⇒ + = + = =      

= soil soil soil ray back b b b b b

CALPOST calculates the 24-hour average visibility i mpairment as a function of the concentration of visibility-affecting pollutants us ing the default IMPROVE light extinction formula, which is summarized in the foll owing equation.



## ( ) Ray ap Coarse Soil OC NO SO background ext b b b b b b b Mm b + + + + + + = − 3

4 1

, , whereCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 17 

### ( ) 

### [ ] ( ) 

### [ ] ( ) 

### [ ] [ ] [ ] [ ] 

## ( ) ( ) 

### [ ] 3 1 3 4 3 4

2 4 4

m

μ g in ion Concentrat Function

Humidity Relative default by Mm 10 Scattering Rayleigh EC 10 Mass Coarse 6.0 Soil 1 OC 4 NO NH 3 SO NH 3

= = = = = = = = =

−
RH f b b b b b RH

f b RH

f b

Ray ap Coarse Soil OC NO SO 

### ( ) 

### [ ] [ ] [ ] [ ] [ ] [ ]
molecules air to due scattering is Scattering Rayleigh carbon elemental of ion concentrat the denotes EC dusts coarse of ion concentrat the denotes Mass Coarse soils fine of ion concentrat the denotes Soil carbon organic of ion concentrat the denotes OC ion concentrat nitrate ammonium the denotes NO NH ion concentrat sulfate ammonium the denotes SO NH

3 4 4 2 4

As noted in the VISTAS BART Modeling Protocol, the U.S. EPA and the Regional Planning Organizations (including VISTAS) are evalu ating whether refinements are
warranted to the methods recommended in U.S. EPA’s guidance to calculate estimates of natural background visibility. For the purposes of calculating current, future, and natural background visibility at Class I areas as part of i ts reasonable progress analyses, VISTAS intends to present regional air quality modeling re sults using both the default and the newly revised IMPROVE light extinction formula. GP applied the revised IMPROVE formula to the analysis of visibility impairment at St. Marks to calculate a more refined
result.

In December 2005, the IMPROVE workgroup issued a re port describing an alternative to
the default formula used to estimate extinction fro m particle concentration measurements (referred to as the “2005 IMPROVE Report” hereafter ). A final report was issued in March 2006 to present a thorough survey of estimate s of mass scattering efficiencies from recent peer-reviewed literature and provisiona l recommendations for refinements to the IMPROVE equation (referred to as the “2006 IMPR OVE Report” hereafter).
Refinements in the revised IMPROVE formula include:

• Distinguishing the size (i.e., age) of secondary po llutants and growth factors for different sizes of particle species

• Adding a site-specific Rayleigh scattering term to the formula to represent the dependence of Rayleigh scattering on air density (i .e., elevation)Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 18 • Adding a sea salt term, including a growth factor d ue to relative humidity

• Adding a term for visibility impairment resulting f rom gaseous nitrogen dioxide (NO 2 )

The revised IMPROVE light extinction algorithm take s the following form:

≈ ext b 

### ( ) ( )



### [ ] ( ) ( )



### [ ] ( ) 

### [ ] ( ) 

### [ ] [ ] [ ] [ ] [ ] [ ] ( ) 

### [ ] [ ] 2 Scattering Rayleigh specific Site Large Small Large 3 4 Small 3 4 Large 2 4 4 Small 2 4 4

NO 33.0 Salt Sea 4.1 PMC 6.0 PMF 1 EC 10 OC 1.6 OC 8.2 NO NH 1.5 NO NH 4.2 SO NH 8.4 SO NH 2.2

+

+ +

+ + + + +

+ + +

− b RH f RH f RH f RH f RH f

SS L S L S

To facilitate the use of the revised IMPROVE algori thm for assessing BART applicability, the VISTAS Technical Contractor deve loped and distributed a spreadsheet tool to implement the revised IMPROVE light extinct ion algorithm, designated as the CALPOST-IMPROVE Processor Version 2 (September 29, 2006). This processor calculates the reconstructed light extinction using the revised IMPROVE algorithm and output from the current version of the CALPOST post processor. To implement the CALPOST-IMPROVE tool, three additional data points are required: background concentration of gaseous NO 2 , Rayleigh scattering parameter corrected for site- specific elevation, and an estimate of the average backgroun d sea salt aerosol concentration.

Although other anthropogenic (stationary and mobile ) sources contribute to background
levels of NO 2 at Class I areas, for the purposes of this analysi s, the background NO 2 concentration was assumed to be attributable only t o BART-eligible sources at the CSO. The 24-hour average NO 2 concentration for each day and receptor was calcul ated by separate CALPOST processing analyses, and converted from units of μ g/m 3 (default model output) to parts per billion as required by t he tool. The NO 2 concentration entered
into the CALPOST-IMPROVE tool for each 24-hour aver age visibility impacts corresponded to the day and receptor at which the v isibility impact occurs. CALPOST analyses for NO 2 are included on the electronic media provided with this updated report.
The NO 2 /NO X ratio was conservatively entered as 1.0 in the CAL POST-IMPROVE tool.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 19 The 2005 IMPROVE Report describes the justification for using a site-specific Rayleigh scattering parameter in the revised light extinctio n algorithm. Rayleigh scattering refers to the scattering of light from the molecules of th e air and is therefore dependent on the air density, which varies with temperature and pres sure. Site-specific Rayleigh scattering was calculated using the standard atmospheric press ure corresponding to the monitoring site elevation and an estimated annual mean tempera ture. The temperature data were
obtained from the nearest weather stations for time periods encompassing ten to thirty years and were interpolated to the monitoring site location. The 2005 IMPROVE Report tabulated site-specific values of Rayleigh scatteri ng for locations at which IMPROVE monitors visibility, including St. Marks for which a value of 11 Mm -1 was calculated. Compared to the default Rayleigh scattering value o f 10 Mm -1 , the corrected values
reflect the near-sea level elevation of Class I are a evaluated in this analysis.

The 2005 IMPROVE Report identified sea salt aerosol s as an important component of natural visibility conditions, particularly in humi d coastal environments such as the Class I areas potentially affected by GP’s CSO. Th e 2006 IMPROVE Report identifies sea salt as a statistically significant component o f fine particle mass at St. Marks. Representative natural background sea salt concentr ations were estimated for implementation in the CALPOST-IMPROVE processor for BART applicability analyses, including a concentration of 0.03 μ g/m 3 for St. Marks.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 20 

### 5.0 RESULTS AND DETERMINATION OF IMPAIRMENT
5.1 Impact Threshold The final BART guidance recommends a threshold valu e of 0.5 dv change from natural
conditions to define whether a source “contributes” to visibility impairment. The
98 th percentile, 24-hour average predicted impact at th e Class I area, as calculated using CALPOST Method 6 (monthly average relative humidity values), is to be compared to this contribution threshold value. For this compar ison, the predicted impact at the Class I area on any day is taken to be the highest 24-hr av erage impact at any receptor in the Class I area on that day. Because three meteorolog ical data years (i.e., 2001 through 2003) were evaluated, VISTAS recommends that the 98 th percentile value be determined as the highest, 8 th -high 24-hour average visibility impairment among t hree years or the
22 nd -highest 24-hour average visibility impairment over three years, whichever result is
more conservative.



### 5.2 Presentation of Modeling Results
Tables 7 and 8 summarize the CALPOST results for th e 98th percentile, 24-hour average visibility impairment at Okefenokee and St. Marks, respectively. Each summary table presents the results from the two operating scenari os evaluated as well as the default and non-default processing methods described in this re port. The default processing method
does not utilize the ALM and utilizes CALPOST for t he default IMPROVE light
extinction calculation. Results for both Class I a reas are also presented using the ALM with the default IMPROVE light extinction calculati on. GP applied the refined IMPROVE equation to calculate refined impacts at St . Marks using the CALPOST results from the ALM analysis.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 21 Table 7. Summary of CALPUFF Results, Okefenokee NW R 98 th Percentile, 24-hour Average Change in Visibility ( ∆ dv)

Model Run 2001- 2003 2001 2002 2003 Operating Scenario 1 Default Processing Without ALM 0.309 0.305 0.288 Processing With ALM 0.30 0.306 0.300 0.281

Operating Scenario 2 Default Processing Without ALM 0.270 0.272 0.248 Processing With ALM 0.266 0.267 0.266 0.241

Table 8. Summary of CALPUFF Results, St. Marks NWR 98 th Percentile, 24-hour Average Change in Visibility ( ∆ dv)

Model Run 2001- 2003 2001 2002 2003 Operating Scenario 1 Default Processing Without ALM 0.495 0.622 0.469 Processing With ALM 0.493 0.487 0.616 0.455 Processing With ALM and Revised IMPROVE 0.408 0.403 0.499 0.368

Operating Scenario 2 Default Processing Without ALM 0.452 0.556 0.422 Processing With ALM 0.463 0.451 0.550 0.404 Processing With ALM and Revised IMPROVE 0.387 0.352 0.446 0.340

The results presented in Tables 7 and 8 confirm GP’ s determination that the Mill is exempt from BART because emissions from the BART-el igible source neither cause nor contribute to visibility impairment at any Class I area when operating in either of the two analyzed operating scenarios.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 22 

### APPENDIX Electronic Media File Index
Electronic media enclosed with this report contain the input and output files from all CALPUFF, POSTUTIL, and CALPOST processing analyses. Each analysis is contained within its own appropriately named compressed file, which includes model executable files and batch files to manage the runstream. A c onsistent file naming convention is used throughout with the following general structur e. Note that refined meteorological data files are not provided due to file size. Note also that path names in input files will need to be modified to represent the user’s directo ry structure when replicating these analyses.
The following processing sequence was used for each meteorological data year:

• CALPUFF was run separately for each source type (i.e., Pow er Boilers Nos. 1 and 2, Recovery Boiler No. 3, Lime Kilns Nos. 1 and 2, and Smelt Dissolving Tank No. 3) because each source has a distinct PM 10 speciation profile.

• The total PM 10 emission rate was modeled in CALPUFF and was subse quently speciated using the POSTUTIL post-processor.

• CALSUM was then used to combine the concentrations of all pollutants (including speciated PM 10 components) into a single concentration file.

• POSTUTIL was run a second time to apply the “ammonia limiti ng method” (ALM), which calculates the HNO 3 /NO 3 re-partitioning. The ALM analyses are run in three, 4-month blocks (A, B, C) due to an in herent limitation in the number of meteorological periods that can be processed whe n the ALM calculations are enabled in POSTUTIL.

• Therefore, the APPEND utility must be run to concatenate the output file s comprising these three blocks of data.

• CALPOST was subsequently run three times for each Class I area 1. Utilizing the “default” concentration output file w ithout ALM processing
2. Utilizing the concentration output file from ALM pr ocessing
3. Computing daily average NO 2 concentrations for use in the revised CALPOST-IMPROVE post-processing tool.Cedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 23 CALPUFF Runstream Files

uu PUFF yy

. fff

uu = PB (Power Boilers Nos. 1 and 2), RB (Recovery Bo iler No. 3), LK (Lime Kilns Nos. 1 and 2), SDT (Smelt Dissolving Tank No. 3) yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively fff = inp denotes input files fff = lst denotes CALPUFF output summary files fff = con denotes CALPUFF output concentration files

Domain 4 Ozone Data Files

4OZ yyyy .dat yyyy = 2001, 2002, and 2003 denotes respective data ana lysis years
PM Speciation POSTUTIL Processing Files

uu UTIL yy

. fff

uu = PB (Power Boilers Nos. 1 and 2), RB (Recovery Bo iler No. 3), LK (Lime Kilns Nos. 1 and 2), SDT (Smelt Dissolving Tank No. 3) yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively fff = inp denotes input files fff = lst denotes POSTUTIL output summary files fff = con denotes POSTUTIL output concentration files
CALSUM Processing Files

CALSUM yy .inp denotes CALSUM processing input file ALLSRC yy .con denotes output concentration files

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectivelyCedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 24 Ammonia Limiting Method POSTUTIL Processing Files
Note that in refined analyses for which the ammonia limiting method (ALM) was run, POSTUTIL is run in two separate steps, the first of which applies PM speciation for analysis in CALPOST, the second of which calculates the HNO 3 /NO 3 re-partitioning. The ALM analyses are run in three, 4-month blocks ( A, B, C) due to an inherent limitation in the number of meteorological periods that can be processed when the ALM calculations are enabled in POSTUTIL. Therefore, t he APPEND utility must be run to concatenate the output files comprising these three blocks of data. CALPOST is subsequently run using this appended file.

ALMUTIL_

yyb

. fff yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively b = A, B, and C denoting 4-month blocks January-Apri l, May-August, SeptemberDecember, respectively fff = inp denotes input files fff = lst denotes POSTUTIL output summary files fff = con denotes POSTUTIL output concentration files

ALMAPPEND yy

.

fff yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively fff = inp denotes input files fff = lst denotes APPEND output summary files

CONCEN

yy .con = Appended POSTUTIL-ALM concentration file for year yy

.
CALPOST Runstream Files

POST_ aa

_

pp

_ yy

. fff yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively fff = inp denotes CALPOST input files fff = lst denotes CALPOST output summary files

aa denotes the Class I areas considered in the analys es: STMK = St. Marks NWR OKEF = Okefenokee NWR

pp denotes the processing method considered in the an alyses: NOALM = processing using concentration files from C ALSUM step without ALM VIS = processing using concentration files from POS UTIL-ALM step with ALM NO2 = processing for daily average NO 2 concentrations for CALPOST-IMPROVECedar Springs Mill BART Exemption Report August 1, 2008 (Revised)

BART Exemption CSO Model Report (80108).doc 25 CALPOST-IMPROVE Microsoft Excel Spreadsheet Analyse s
CALPOST-NewIMPROVE_St_Marks_ yyyy .xls
This spreadsheet comprises the VISTAS Revised CALPO ST-IMPROVE spreadsheet tool calculations using CALPOST outputs for visibility i mpacts and calculated NO 2 concentrations at St. Marks, where yyyy = 2001, 2002, and 2003, for data years 2001, 2001, and 2003, respectively.