BART DETERMINATION FOR INTERSTATE PAPER

Interstate Resources Incorporat ed owns and operates paper fac ility called Interstate Paper located in Riceboro, Georgia. Interstate Pape r is located within 100 Km of Wolf Island

Class I area and Okefenokee Wilderness Class I area.

To be BART eligible a source must fall w ithin one of the 26 BART eligible source categories included in Clean Air Act, The s ource must have been in existence on August 7, 1977 and must have began operation after August 7, 1962 and the source must have potential emissions of visibility impairing po llutant of 250 tons per year or more. Three of Interstate Paper’s units sa tisfy these criteria and hence are BART eligible. These three units are Power Boiler (F1), Recovery Boiler (F3), and Lime Kiln (F4).

INTRODUCTION TO BART ANALYSIS

The Best Available Retrofit Technology (BAR T) analysis follows the “five factor” approach. The basic steps of a “five factor” analysis are as follows:

1. Cost of Controls 2. Energy and non-air quality environmental impacts 3. Existing controls at the source 4. Remaining useful life of the source 5. Visibility improvement reasonabl y expected from the controls

A detailed description of cost of controls fo r BART-subject units at Interstate Paper, LLC mill in Riceboro, Georgia is given in the BART engineering analysis section. Most of the

control costs were obtained from AirCont rolNET-4.1. Fuel switching cost was based on the facilities fuel usage and the cost of fuel in 2007 based on number provided by the facility itself. This section also gives an in-depth description a nd usage of the existing

controls at the source. There are no known energy and non-air quality environmental impacts related to BART determined controls for Interstate paper, LLC. Remaining useful life of the source is

BART Determination – Interstate Paper 1known to be at least 10 years. Visibility improvement reasonably expected from application of the contro ls is described in the modeling analysis section.

Georgia EPD performed the five steps for each visibility-affecting pollutant emitted from the BART-subject units. Relevant pollu tants are only: su lfur dioxide (SO 2 ), nitrogen oxides (NO x ) and particulate matter (PM 10 ). The following sections provide detailed engineering and modeling analysis for each BART-subject unit.

1.0 ENGINEERING ANAL YSIS METHODOLOGY

The Best Available Retrofit Technology (BART) engineering analysis in this application follows the “top-down” approach. The “top- down” approach starts with the most stringent control tec hnology alternative that has been applied to similar sources and provides a basis for rejecting this alternative in favor of the next most stringent technology or proposing it as BART. The basic steps of a “top-down” analysis are as

follows: 1. Identify all control strategies 2. Eliminate technically infeasible options 3. Rank remaining control strategies by control effectiveness or efficiency 4. Eliminate economically infeasible ones

5. Evaluate most effective controls and document results for BART recommendation

Georgia EPD performed the five steps for each visibility-affecting pollutant. Georgia EPD has determined that the relevant pollutants are only: sulfur dioxide (SO 2 ), nitrogen oxides (NO x ) and particulate matter (PM 10 ). The following sections provide a detailed e ngineering analysis for each BART-eligible

unit.

2.0 BART ENGINEERING ANALYS IS FOR RECOVERY BOILER

2.1 SOURCE DESCRIPTION

BART Determination – Interstate Paper 2The Recovery Boiler (F3) is a low odor, indire ct contact evaporator design. It fulfills the following essential functions:

1. Evaporates the residual moistu re from the black liquor solids. 2. Burns the organic constituents.

3. Produces steam.

4. Produces sodium carbonate and sodium sulfides in molten form Black liquor with more than 68% solids is fired into the reco very boiler where the organics from the black liquor are burned off in a reducing atmosphere generating steam,

molten sodium carbonate and sodium sulfides.

Air pollutants emitted from the recovery boiler include all the three BART relevant pollutants i.e. sulfur dioxide (SO 2 ), 2.46 tons/yr, nitrogen oxides (NO x ), 349.92 tons/yr, and particulate matter (PM 10 ), 0.5 tons/yr. Emissions of the Recovery Boiler currently pass through a venturi scrubber.

2.2 PARTICULATE MATTER

Step 1.0-Identification of Control Technologies Emission control equipments that may be considered to control particulate matter emissions from recovery boilers include ESP’s, baghouses and high efficiency wet scrubbers. Each of these types of control equi pments is capable of significantly reducing particulate matter emissions.

Step 2.0-Technical feasibility Analysis of the identified Control Technologies While baghouses can achieve high levels of pa rticulate matter control, the exhaust gas streams from recovery boilers have relativ ely high moisture contents that cause the particulate matter to be hydroscopic in nature. These characteristics of the gas will result in clogging up of the bag filters in the baghous e. This indicates that baghouses are not a good control option for recovery boilers. Ther efore, baghouses are not considered further as part of this BART analysis.

BART Determination – Interstate Paper 3ESP’s and wet scrubbers are feasible t echnologies for reducing particulate matter emissions from recovery boilers, with ESP’ s having 99+% of control efficiency and wet scrubbers having 98+% of control efficiency.

Step 3.0-Control Efficiency and Cost Evaluation An ESP has a slightly better control efficiency as compar ed to wet scrubber but the recovery boiler at the facility already uses a venturi scr ubber to control PM emissions. Thus it is economically infeasible to install an ESP for a control efficiency enhancement of about 1% and incur an expenditure of about $ 68,239,64 (includes capital investment, installation, maintenance, and cost per ton of reduction achieved). Approximately similar control efficiency can be obtained without any additional cost.

Step 4.0-Control Technology Selected for BART The unit already utilizes a ve nturi scrubber to control particulate matter emissions, no additional controls are proposed.

2.3 NITROGEN OXIDES

Step 1.0-Identification of Control Technologies Emission control equipments that may be cons idered to control nitrogen oxide emissions from recovery boilers include combustion modification techniques and post-combustion

controls.

Combustion Modification Techniques

A number of combustion modification t echniques are available for reducing NO x emissions from boilers in general. These include:

• Staged air combustion

• Low NO x burner with flue gas recirculation system

• Oxygen trim and water injection

The combustion modification t echniques listed above reduce NO x by minimizing its formation in the combustion chamber of the boiler or by using less oxygen than is stoichiometrically required for complete combustion of the fuel.

BART Determination – Interstate Paper 4Post-Combustion Controls The technologies for post-combustion control include:

• Selective non-catalyt ic reduction (SNCR)

• Selective catalytic reduction (SCR)

Step 2.0-Technical feasibility Analysis of the identified Control Technologies

• Staged air combustion is integral to the operation of most rec overy boilers, is the most effective strategy for minimizing NO x formation in a recovery boiler hence, is technically feasible. As such, it is also integral to th e operation of most recovery boilers. The recovery boiler at the Riceboro mill currently employs staged air combustion with primary, sec ondary and tertiary combustion air. A fourth level of staged air combustion ca nnot be added, as it would require a new recovery boiler and cannot be cons idered as a retrofit control.

• Use of a low NOx burner is of minimal value for NOx reduction because the primary fuel of the recove ry boiler is black liquor.

• Flue Gas Recirculation has not been co mmercially applied to Babcock & Wilcox furnaces. Furthermore, the reducing atmosphere needed to convert sulfate compounds to sulfide compounds in the lower furnace tends to preclude FGR in the lower furnace. In other words, FGR wouldn't provide any measurable NOx reduction on the recovery boile r, if applied to the lowe r furnace. Use of FGR may also unreasonably restrict throughput and cr eate safety issues due to anticipated smelt bed control problems, if applied to the lower furnace. There may be some benefit to FGR application above the ter tiary air level but such has not been commercially applied.

• Kraft recovery boilers already employ some method of oxygen trim due to the reduction atmosphere demanded by the proce ss itself. Interstate Paper typically targets 3 to 4 % excess oxygen at the ec onomizer, which trims air combustion in response. The use of more advanced oxyge n trim methods probably won’t provide any measurable impact on NOx. Thus use of further oxygen trim is not technically

feasible.

BART Determination – Interstate Paper 5• Water injection cannot be considered due to its' inherently dangerous nature for Kraft recovery furnaces. Thus water injecti on is technically infeasible and will not be further considered for BART analysis

• SNCR as a control option for flue gas trea tment is technically not very feasible based on the fact that SNCR systems work by injecting ammonia or urea into the combustion chamber of the boiler, thereby converting NO x to elemental nitrogen, carbon dioxide, and water vapor. The rec overy boiler is a co mplete, chemical reaction system and any disruption of the delicate chemistry could possible damage the boiler, impact the quality of the product, or otherwise affect the system unacceptably. The injection of ammonia gas or urea solution would have a detrimental effect upon the chemistry inside the boiler. Thus usage of SNCR as a NOx control for recovery boilers is infeasible and will not be further considered for BART analysis.

• The technical feasibility of a SCR system for treatment of flue gases generated from recovery boiler is questionable. Th e toxic metals present in the flue gas exhaust are of sufficient quantity to build up on the surface of the catalyst bed and poison the catalyst within a relatively s hort period of time. Thus SCR is also technically infeasible for a recovery boile r and will not be further considered for BART analysis.

Step 3.0-Control Efficiency and Cost Evaluation No control technology was technically feasible.

Step 4.0-Control Technology Selected for BART No additional BART controls are proposed.

2.4 SULFUR DIOXIDE

Step 1.0-Identification of Control Technologies Emission control equipments that may be cons idered to control sulf ur dioxide emissions from recovery boilers include any number of absorption (i.e., scrubbi ng) processes, flue

BART Determination – Interstate Paper 6gas desulfurization (FGD), combustion cont rol and usage of high black liquor solid

content.

Step 2.0-Technical feasibili ty Analysis of the iden tified Control Technologies

• Gas absorption systems are designed to maximize contact between the gas and liquid in order to permit interphase diffusion of the SO 2 . Absorbers found to adequately disperse the liquid include packed towers, plate or tr ay towers and tray

chambers. SO 2 emission reductions of 90-98% can be expected by usage of gas absorption systems. However if the polluta nt concentration entering the absorber is relatively low, then SO 2 removal efficiency will be much lower. Thus gas absorption systems are feasible cont rol equipments for reduction of SO 2 emissions.

• Combustion control and high black liquor solids content are effective means to

control SO 2 emissions from recovery boilers. SO 2 emissions are formed by the oxidation of reduced sulfur compounds in recovery boilers. These emissions vary depending upon the sulfur content of the black liquor being burned, the quantity of oxygen available in the combustion chamber and the black liquor solids content. Higher black liquor so lids content, yields lower SO 2 emissions. Thus combustion control and black liquor so lid contents are feasible control technologies for SO 2 emissions from the recovery boiler.

• Flue gas desulfurization technology is used on coal-fired boilers and works in one of the two ways. The first method work s by injecting dry limestone into the combustion chamber of the boiler, where limestone reacts with sulfur dioxide gases to form calcium sulfate. Injection of chemicals into the combustion chamber of the recovery boiler as a means to control SO 2 emissions will interfere with the recovery process that is taking place insi de the boiler. For this reason flue gas desulfurization using “dry limestone” method is not considered technically

feasible for reduction of SO 2 . Additionally, there are no known recovery boilers in the U.S utilizing this particular type of SO 2 control. The second method works by adding a wet slurry of limestone into a sc rubber that is cont rolling the flue gas

from the boiler. Limestone reacts to form calcium sulfate in the slurry form. Usage of wet limestone outside the boiler is technically feasible and would lead to

BART Determination – Interstate Paper 7a removal efficiency of 90% or higher depending on the SO 2 content in the flue

gas.

Step 3.0-Control Efficiency and Cost Evaluation

• Gas absorption systems are technically f easible control systems involving high capital investment and installati on costs of about $166,5000. These systems usually have high-pressure drops in the ra nge of 6-8 inches w.c. This may require additional expenditure for a new fan, whic h should be designed to handle that pressure drop. These systems also requi re routine maintenance and hence would also involve high maintenance cost. Thus they cannot be considered as BART

controls because of their economic infeasibility.

• Combustion control along with being a tech nically feasible means of controlling

SO 2 emissions is also inherent in the de sign of a recovery boiler due to the chemical reactions that take place inside of the combustion chamber when black liquor is combusted. Black liquor normally contains a number of sulfur-bearing compounds when it is generated from th e Kraft pulping process. When black liquor is oxidized, most of the oxidize d sulfur compounds are converted into sulfides. These inorganic compounds, pr imarily sodium sulfide and sodium sulfate, recovered in molten form at the bottom of the bed, are referred as “smelt”.The smelt is drained through the bottom of the recovery boiler into a smeltdissolving tank. The majority of the sulfur compounds th at leave the smelt bed as sodium fume from the reduction process are tied up with boiler bottom ash as sodium sulfate, there by reducing SO 2 emissions discharged from the boiler. The capture of SO 2 is primarily dependent upon the boiler bed temperature. An increase in the dry solids content raises the temperature at th e bottom part of the furnace thus reducing SO 2 emissions. Thus a control efficiency of 99+% can be obtained without the usage of any additional control technology. Hence combustion control with high solids content is economically feasible control for

SO 2 emissions from the recovery boiler.

• Flue gas desulfurization technique with wet limestone slurry is technically

feasible but would involve additiona l equipment capital, installation and maintenance cost of about $ 290,6000 and lead to SO 2 removal efficiency of

BART Determination – Interstate Paper 8about 90% which is less than what ca n be achieved by combustion control and high black liquor solids cont ent. Hence it’s not considered to economically feasible and will not be further considered for BART analysis of the recovery

boiler.

Step 4.0-Control Technology Selected for BART Presence of black liquor solids content of up to 68% or more along with inherent design of the recovery boiler satisfies the require ment of combustion control technology thus leading to a control efficien cy of 99+%. Thus no additional BART control is suggested.

3.0 BART ENGINEERING A NALYSIS FOR LIME KILN

3.1 SOURCE DESCRIPTION The lime kiln dries and processes lime mud from the causticizing system by burning fuel oil with sulfur content no greater than 2.5% . The lime kiln is permitted to burn natural gas, No. 6 fuel oil, or limited quantities of us ed oil. It is equipped with a venturi scrubber to control particulate matter emissions. The lime kiln also serves as a back-up combustion device for low-volume, high con centration (LVHC) non- condensable gases (NCGs) generated in the pulp mill.

Air pollutants emitted from the Lime Kiln incl ude all the three BART relevant pollutants i.e. sulfur dioxide (SO 2 ), 9.50 tons/yr, nitrogen oxides (NO x ), 149.16 tons/yr, and particulate matter (PM 10 ), 127.56 tons/yr. Emissions of the Lime Kiln currently pass through a venturi scrubber.

3.2 PARTICULATE MATTER Step 1.0-Identification of Control Technologies Emission control equipments that may be c onsidered for particulate matter control are baghouses, cyclonic separators, venturi scrubbe rs, other wet scrubbers and a combination

of a venturi scrubber and ESP.

BART Determination – Interstate Paper 9Step 2.0-Technical feasibility Analysis of the identified Control Technologies All the above-listed technologies other than baghouses are techni cally feasible for removal of particulate matter from the lime kiln exhaust gas.

Step 3.0-Control Efficiency and Cost Evaluation

Table 1.0 ranks all the technica lly feasible control technolo gies based on top control efficiency values. The lime kiln at Intersta te paper is currently equipped with a venturi

scrubber. The venturi scrubber primarily uses fresh water as the scrubbing media. As shown in Table 1.0, the control efficiency that can be achieved with a venturi scrubber is about 98-99%. Cyclones are not considered b ecause their control efficiencies are lesser than that of a Venturi scrubber. A venturi scrubber along with an ESP shows an increase in the control efficiency by about 1%. Installa tion of an ESP in combination to the venturi scrubber would approximately cost $5,495,014/yr. Hence it’s economically infeasible to endure such a high expense for an effi ciency increase of about 1% only.

Table 1.0. Ranking of Particulate Matter Cont rol Equipments for Existing lime kilns Control Technology Removal Efficiency

Venturi Scrubber and ESP 99.9%+

Venturi Scrubber 98-99%

Dry/Wet ESP 98-99%

Packed Bed Wet Scrubber 85+% Cyclone Separator 25-95%

Step 4.0-Control Technology Selected for BART

A venturi scrubber is the second most e ffective technology for removing particulate

matter from lime kiln exhaust. Because the unit already utilizes a venturi scrubber to control particulate matter emissions, no additional controls are proposed.

3.3 NITROGEN OXIDES

BART Determination – Interstate Paper 10Step 1.0-Identification of Control Technologies Emission control equipments that can be c onsidered for control of nitrogen oxide

emissions from the lime kiln are low NO x burners, SNCR-NH 3 based, SNCR-urea based

and SCR.

Step 2.0-Technical feasibility Analysis of the identified Control Technologies

All the above-mentioned contro l equipments are technically feasible for removal of nitrogen oxide from the lime kiln exhaust.

Step 3.0-Control Efficiency and Cost Evaluation Table 2.0 ranks all the technica lly feasible control technolo gies based on top control efficiency values.

Table 2.0. Ranking of Nitrogen Oxide Control Te chnologies for Existing Lime Kilns

Cost Evaluation Control Technology Removal Efficiency Capital + Operation

Cost ($) Cost/ton of NO x reduction ($/ton) Total

Annual cost ($)

SCR 80% 208,793,6 4,450 424,647 Fuel Switch to burning

of Natural Gas only 73% 0 4,320 105,027.5

Low NO x burner 50% 144,242 740 26,461

SNCR-Urea based 50% 174,006 1,017 60,641

SNCR-NH 3 based 30% 263,593 1,123 66,942

The low-NOx burner control option and the tw o SNCR control options are considered to be economically feasible. However, they are not considered further as retrofit controls because of the relatively small benefit to visibility of NOx controls. Comparison of the visibility benefits of SO2 control versus NOx control is presented in Section 5.0.

Step 4.0-Control Technology Selected for BART All the above-mentioned technologies are economically infeasible and cannot be considered as retrofit controls. Hence, no a dditional BART controls are suggested for the

NOx emissions of the lime kiln at the Riceboro mill.

BART Determination – Interstate Paper 113.4 SULFUR DIOXIDE Step 1.0-Identification of Control Technologies Emission control equipments that can be consid ered for control of sulfur dioxide are gas absorption with caustic scrubber; wet scrubb er with lime mud; a nd use of low sulfur

fuels.

Step 2.0-Technical feasibility Analysis of the identified Control Technologies

All the above-mentioned control equipments are technically feas ible for removal of sulfur

dioxide from the lime kiln exhaust.

Step 3.0-Control Efficiency and Cost Evaluation The control efficiency of a gas absorber with caustic scrubbing is similar to that of a wet

scrubber with lime mud. Each of these techno logies can reduce sulfur dioxide emissions by up to 95%. Reducing the oil from 2.5% sulfur content to a low-sulfur fuel will show a control efficiency of approximately 50%.

Step 4.0-Control Technology Selected for BART The lime kiln at Interstate Paper utilizes a venturi scrubber (wet sc rubber) for particulate

matter control. This scrubbe r further augments the SO 2 removal process since the scrubbing solution becomes alkaline from the captured lime dust, consequently the lime kiln emits a very low level of SO 2 . Hence, no additional SO 2 controls are proposed.

4.0 BART ENGINEERING ANAL YSIS FOR POWER BOILER

4.1 SOURCE DESCRIPTION The Power Boiler at Interstate Paper was in stalled in 1968 and has a maximum heat input of 400 MMBTU/hr. It fires natural gas and No. 6 fuel oil. The power boiler, along with the lime kiln, is used as a backup control device and it burns non-condensable gases too. Air pollutants emitted from the Power Boiler include all the three BART relevant pollutants i.e. sulfur dioxide (SO 2 ), 300.49 tons/yr, nitrogen oxides (NO x ), 409.24 tons/yr, and particulate matter (PM 10 ), 19 tons/yr.

BART Determination – Interstate Paper 124.2 PARTICULATE MATTER Step 1.0-Identification of Control Technologies Emission control equipments and technologies that may be considered for particulate matter controls are ESP, fabric filt er and fuel switch to natural gas.

Step 2.0-Technical feasibility Analysis of the identified Control Technologies

All the above-mentioned contro l technologies are technically feasible for removal of particulate matter from the exha ust gases of th e power boiler.

Step 3.0-Control Efficiency and Cost Evaluation

Table 3.0 ranks all the technica lly feasible control technolo gies and their total annual

cost.

Table 3.0. Ranking of Particulate matter Contro l Technologies for Existing Power Boilers

Cost Evaluation Control Technology Removal Efficiency Capital + Operation

Cost ($) Cost/ton of PM

reduction

($/ton) Total Annual cost ($)

Fuel Switch to

Natural Gas 99% 0 5,705 102,000

ESP 98-99% 4,129,230 19,364 1,705,983

Fabric Filter 98-99% 3,355,180 79,470 1,782,035

ESP and fabric filter are t echnically feasible controls for PM emission reduction, but there are high capital and maintenance co sts which cause them to be economically

infeasible for BART and hence will not be further considered for BART analysis.

Step 4.0-Control Technology Selected for BART The fuel switch to natural gas gives a particul ate matter removal efficiency of more than 99%. The cost that the facility will incur for su ch a fuel switch is also relatively less than

BART Determination – Interstate Paper 13the addition of control equipment. Along w ith reduction in PM emissions, reduction in

NO x and SO 2 will also be achieved therefore fuel sw itch to natural gas is an economically feasible option. Hence in the power boiler at the Riceboro mill, it is recommended to burn natural gas only, other than during pe riods of curtailment (i.e. reduction or discontinuance of natural gas supply).

4.3 NITROGEN OXIDES

Step 1.0-Identification of Control Technologies Emission control equipments and technologies that may be considered for nitrogen oxide

controls are low NO x burner, low NO x burner with flue gas re circulation, SCR, SNCR and fuel switch to natural gas.

Step 2.0-Technical feasibility Analysis of the identified Control Technologies

All the above-mentioned contro l technologies are technically feasible for removal of nitrogen oxides from the exhaus t gases of the power boiler.

Step 3.0-Control Efficiency and Cost Evaluation

Table 4.0 ranks all the technica lly feasible control technolo gies and their total annual

cost. Table 4.0. Ranking of Nitrogen Oxide Control Technologies for Existing Power Boilers

Cost Evaluation Control Technology Removal Efficiency Capital + Operation

Cost ($) Cost/ton of

NO x reduction ($/ton) Total Annual cost ($)

SCR 80% 304,095 1,955 30,241

Low NO x Burner

+ Flue Gas

Recirculation 60% 104,006 1,479 17,163

Low NO x Burner 50% 30,838 528 5,108

SNCR 50% 313,418 3,407 32,948

BART Determination – Interstate Paper 14Fuel Switch to

Natural Gas 13% 0 29,800 102,000

SCR, Low NO x burner; Low NO x burner with flue gas re circulation are economically

feasible controls for NO x emission reduction. However, th ey are not considered further for BART analysis because of th e relatively small benefit to visibility of NOx controls. Comparison of the visibility benefits of SO 2 control and NOx control is presented in

Section 5.0. Step 4.0-Control Technology Selected for BART Along with reduction in NO x emissions, reduction in PM and SO 2 emissions can also be achieved by “fuel switch to natu ral gas” thus, it is an economically feasible option. Therefore, it is recommended that only natu ral gas be permitted as fuel in the power boiler at Riceboro mill, other than during periods of curtailment (i.e. during reduction or discontinuance of supply in natural gas).

4.4 SULFUR DIOXIDE

Step 1.0-Identification of Control Technologies Emission control equipments and technologies th at may be considered for sulfur dioxide

controls are venturi scrubbers with caustic addition, sp ray dry scrubbers, dry scrubbers and fuel switch to natural gas.

Step 2.0-Technical feasibility Analysis of the identified Control Technologies

All the above-mentioned contro l technologies are technically feasible for removal of

sulfur dioxide from the exhaus t gases of the power boiler.

Step 3.0-Control Efficiency and Cost Evaluation

Table 5.0. Ranking of Sulfur Dioxide Contro l Technologies for Existing Power Boilers

Control Removal Cost Evaluation

BART Determination – Interstate Paper 15Technology Efficiency Capital +

Installation +

Operation

Cost ($) Cost/ton of

SO 2 reduction ($/ton) Total Annual cost ($)

Fuel Switch to

Natural Gas 99+% 0 370.00 102,000

Wet Scrubber w/ caustic? (venturi) 90% 2,377,636 1,630 528, 246

Spray Dry

Scrubber 80-90% NA NA NA

Dry Scrubber 50 to 80% NA NA NA

Fuel switch and wet scrubbe r are technically feasible . The cost per ton of SO 2 emission

reduction of each alternative is well within the range that EPA considers economically feasible. Hence both the techniques will be further considered for BART analysis.

Step 4.0-Control Technology Selected for BART Both the above-mentioned technologies are ec onomically feasible. Natural gas has higher control efficiency at lower cost as comp ared to a wet scrubber. Therefore it is recommended that power boiler at Riceboro mill burn natural gas only, other than during curtailment periods (i.e., during reduction or discontinuance of supply in natural gas).

5.0 COMPARISON OF IMPACTS OF SO2 AND NOX CONTROLS ON

VISIBILITY

Georgia Tech performed a study for EPD th at compared the impacts of statewide reductions of point SO2 and point NOx emissi ons on visibilities at the Wolf Island and Okefenokee Class I areas (see Appendix A). Th e metric used for visibility improvement was light extinction (specifically reduction of light extincti on), expressed in units of inverse megameters (Mm -1 ). The study found that a statewide reduction of one ton per year of point SO2 emissions would effect estimated light extinction reductions of 1.97 x

10 -5 Mm -1 at Wolf Island and 2.59 x 10 -5 Mm -1 at Okefenokee. A one-ton-per-year

BART Determination – Interstate Paper 16reduction of point NOx emissions (statewide) would achieve estimated reductions in light

extinction of 0.319 x 10 -5 Mm -1 at Wolf Island and 0.159 x 10 -5 Mm -1 at Okefenokee. The ratios of light extincti on reduction from SO2 reduction to light extinction reduction

from NOx reduction are then 6.2 at Wolf Is land and 16.4 at Okefenokee. SO2 reductions are therefore expected to provide substant ially more visibility improvement than NOx

reductions at both of these Class I areas.

Sections 3.3, 4.3, and 4.4 evaluate potential BA RT control options for Interstate Paper’s

Lime Kiln and Power Boiler emissions. Usi ng the results of the Georgia Tech study and EPD’s calculations of visibility impacts due to SO2 reductions at specific emissions sources, it is possible to estimate the total visibility improvements for the potential control technologies. The visibility impr ovements are presented only for Wolf Island since it has been determined (S ection 7.1) that the benefits of Interstate Paper emissions controls on visibility at Okef enokee are too small to be considered. The SO2 visibility impact (0.000076 Mm -1 /tpy) used in this calculation is based on site-specific modeling performed by EPD of the impact of Intersta te Paper’s SO2 emissions on light extinction at Wolf Island (Appendix N.1, Table 1). This is believed to be a more accurate estimate of the impact than the SO2 impacts determ ined from the statewide emissions impact study.

The NOx visibility impact is then determin ed by applying the ratio (1/6.2) of the NOx impact to the SO2 impact (from the state-wide study) to the site-spe cific SO2 visibility impact, resulting in 0.000013 Mm -1 /tpy. Note that EPD did not directly model the impact of NOx reductions at sp ecific sites on visibility.

These impacts (0.000076 Mm -1 /tpy and 0.000013 Mm -1 /tpy) are then applied to the specific emissions reductions associated with the potential control options. Tables 5.1 and 5.2 show the light extinction reductions a ssociated with the poten tial control options presented in Sections 3 and 4 for the lime kiln and the power boiler. The light extinction reductions from the SO2 control options range from 0.0147 to 0.0225 Mm -1 . The light

extinction reductions from the NOx control options range from 0.0006 to 0.0041 Mm -1

.

BART Determination – Interstate Paper 17Due to the lower extinction reductions (visibility improvements) for the NOx controls they were excluded from further consider ation as feasible BART control options.

Table 5.1. Interstate Paper Lime Kiln – Estimated Impacts of NOx Controls on Visibility at Wolf Island

Control Technology Emissions (tpy) Removal Efficiency (%) Tons Removed (tpy) Mm -1 per TPY* Extinction reduction (Mm -1 )

NOx Controls

. SCR 149.2 80 119.4 0.000013 0.0015 Fuel switch to NG 149.2 73 108.9 0.000013 0.0014 Low NOx burner 149.2 50 74.6 0.000013 0.0009 SNCR - urea based 149.2 50 74.6 0.000013 0.0009 SNCR - NH3 based 149.2 30 44.8 0.000013 0.0006

Table 5.2. Interstate Paper Power Boiler – Esti mated Impacts of SO2 and NOx Controls on Visibility at Wolf Island

Control Technology Emissions (tpy) Removal Efficiency (%) Tons Removed (tpy) Mm -1 per TPY* Extinction reduction (Mm -1 ) SO2 Controls

. Fuel Switch to NG 300.5 99 297.5 0.000076 0.0225 Wet scrubber with caustic 300.5 90 270.5 0.000076 0.0204 Spray dry scrubber 300.5 85 255.4 0.000076 0.0193 Dry scrubber 300.5 65 195.3 0.000076 0.0147

NOx Controls

. SCR 409.2 80 327.4 0.000013 0.0041 Low NOx burner with FGR 409.2 60 245.5 0.000013 0.0031 Low NOx burner 409.2 50 204.6 0.000013 0.0026 SNCR 409.2 50 204.6 0.000013 0.0026 Fuel switch to NG 409.2 13 53.2 0.000013 0.0007

* The estimated light extinction benefit at Wolf Island associated with the reduction of one ton per year of emissions (SO2 or NOx) from the emissions unit.

BART Determination – Interstate Paper 186.0 ENGINEERING ANALYSIS SUMMARY

Table 6.0 summarizes the technically and economically feasible options for the BARTeligible emission units.

Table 6.0. Summary of BART An alysis, Interstate Paper

Emission Unit Pollutant Existing Controls BART Options $/ton Recovery Boiler PM10 Venturi Scrubber Venturi Scrubber 0 Recovery Boiler NO x Staged Air Combustion Staged Air Combustion 0 Recovery Boiler SO 2 Combustion Control Combustion Control 0

Lime Kiln PM10 Wet Scrubber Wet Scrubber 0

Lime Kiln NO x Not Available None Applicable 0

Lime Kiln SO 2 Wet Scrubber Wet Scrubber 0

Power Boiler PM10 Not Available Fuel Switch to natural gas 5,705

Power Boiler NO x Not Available Fuel Switch to natural gas 29,800

Power Boiler SO 2 Not Available Fuel Switch to natural gas 370.00

7.0 BART DETERMINATION VISI BILITY IMPACTS ASSESSMENT

In order to evaluate the potential visibili ty impacts or improvements at Class I areas which may be caused by the implementation of various emissions scenarios at the Interstate Paper mill, CALPUFF air disper sion modeling was conducted. Such modeling was conducted in accordance with the VISTAS Regional Planning Organization’s BART Modeling Protocol, version 3.2, dated August 31, 2006. The impacts of plant emissions

were assessed under three emissions scenarios. The first scenario c onstitutes a baseline of emissions, based on actual plant emissi ons of visibility-aff ecting pollutants as determined from the facility’s 2002 worst-cas e (maximum) actual emissions over any 24- hour period. The second scenario was evalua ted on the basis that the facility’s Power

BART Determination – Interstate Paper 19Boiler would be shut-down, as initially propos ed by the facility. The third scenario was assessed on the basis that the facility’s Power Boiler would operate on natural gas.

The facility is located in Riceboro, Georgia. Three Class I areas ar e within 300 km of the site, the Cape Romain Wildlife Manage ment Refuge (WMR), SC ( 207 km), the Okefenokee WMR, GA (109 km), and the Wolf Island WMR, GA (42 km).

7.1 Baseline Emission Scenario On August 8, 2006, Interstate Paper, LLC subm itted a facility-specific BART exemption modeling protocol to GA EPD. Review of this protocol indicated that the stack coordinates listed in the prot ocol did not compare favorably to coordinates for those stacks used in a 2001 Prevention of Significant Deterioration (PSD) permit application. The coordinates were modified, and the Building Profile Input Program (BPIPPRM, version 04274) was run to develop downwash dimensions. Downwash dimensions were required to be evaluated since the facility is located less th an 50 km from the Wolf Island WMR and since the facility’s stacks are ea ch less than Good Engineering Practice Stack Height (GEP). Also due to the facility’s location within 50 km of the Wolf Island WMR, 4-km grid-based CALMET output files, prepar ed by the VISTAS contractor, were used in all the modeling.

The mill’s emissions data was compiled by the mill’s consultant, Environmental Planning Specialists, Inc (EPS) from stack test, AP-42, and/or NCASI information. The specific data sources were submitted with the Interstate Paper, LLC BART Exemption Modeling Protocol prepared for the facility by EPS. The emission calculations were reviewed by GA EPD permit engineers (see at tached Table 1., prepared by the VISTAS contractor).

Each of the three International Paper BART -eligible emission sources were modeled separately in CALPUFF by the VISTAS cont ractor, for each model year. Other than point sources, no other emissions were mode led. Wet and dry deposition losses from the plumes were accounted for. Building downwash dimensions from BPIPPRM were provided, but conservatively, only the BPIP dimensions were assessed for downwash

BART Determination – Interstate Paper 20effects on plume concentrations. Table 2, prep ared by the VISTAS contractor, notes that

all PM10 and H 2 SO 4 emissions were conservatively part itioned into organic condensable species, split equally by particle size class. This specific measure was implemented in POSTUTIL by the use of scaling factors. Pa squill-Gifford dispersion coefficients were used in the modeling, rather than basing the dispersion on co efficients developed from turbulence data. The meteorological grid was set equal in extent to the computational grid, and the cell size of each was 4 km sq. All source and receptor locations were assessed using the Lambert Conformal Conic coordinate system.

CALPUFF modeling was conducted to provide concentrations at Class I area receptors located in the Cape Romain, SC; St. Marks, FL; Okefenokee, GA; and Wolf Island, GA Wildlife Management Refuges. Chemical transformation rates of SO 2 and NOx into

SO 4 -2 , HNO 3 , and NO 3 -1 were assessed using the MESOPUFF II scheme with hourly

ozone concentrations derived from contem poraneous monitoring in the domain, and a constant (uniform) monthly average amm onia concentration of 0.5 ppb throughout the

domain.

POSTUTIL conversion of the CALPUFF concen tration files was implemented to develop the PM10 (and H 2 SO 4 ) emissions into two equal size fractions of PM2.5 condensable organic matter. The Ammonia-Limiting Met hod of limiting ammonium nitrate formation due to the scavenging of atmospheric amm onia to form ammonium sulfate, was not implemented in the POSTUTIL processing. The speciated emissions of each of the three modeled sources were summed, by species, at the Class I area receptors modeled.

The CALPOST processor was implemented to assess, by Method 6, the 24-hour average change from annual average, natural bac kground visibility caused by the facility’s sources, in delta-deciviews ( Δ dV). The FLAG, 2000 proposed relative humidity function, with a maximum value of 95 %, was used to simulate hygoscopic species growth. Extinction coefficients of sulfat e and nitrate (hygroscopic) species were computed using monthly relative humidity adjustme nt factors. The visibility calculations were made using the (original) IMPROVE equation.

BART Determination – Interstate Paper 21The results of the baseline visibility asse ssment of the Interstate Paper, LLC BARTeligible sources is presented in Tables 3 and 4, prepared by the VISTAS contractor. Table 3 indicates these sources to have no impact at either the St. Marks, FL, or the Cape Romain, SC WMRs.

The expanded results shown in Table 4 indicate that, based on the highest 98 th percentile change in visibility (one of the desi gn criteria when modeling using a 4-km computational grid), the impacts of the Inte rstate Paper BART-eligible sources at the

Okefenokee WMR are well below th e BART exemption level of 0.5 Δ dV. The alternate design criteria when modeling with a 4-km computational grid is the highest 22 nd high over the three years modeled. Table 4 indica tes that the BART exemption level of 0.5

Δ dV is met with the 11 th highest impact over the thr ee year period modeled at the

Okefenokee WMR. This indicates that the In terstate Paper BART-eligible sources do not need to consider their impacts at the Okefenokee WMR further.

However, the expanded results indicated on Table 4 for the Wolf Island WMR fail to meet the BART exemption criteria on both the annual and the 3-year period basis, by exceeding the exemption level with the 98 th percentile impact in each of the three modeled years, as well as exceeding th e 3-year period desi gn criterion of 0.5 Δ dV with

the 22 nd highest impact. 7.2 Proposed alternative exemption scenario #1. Interstate Paper proposed to shutdown its Power Boiler, which had by far the greatest impact on the visibility at Wolf

Island. The Power Boiler was modeled as it operates, with no air pollution control equipment. The Power Boiler is permitted to burn #6 fuel oil containing as much as 3 wt. percent sulfur. The VISTAS contractor re-e valuated the remaining two Interstate BARTeligible sources, using the same modeling t echniques as implemented in the baseline modeling. The results are indicated on Ta bles 5 and 6, prepared by the VISTAS contractor. These results show only two 24-hour periods were predicted to have visibility impacts in excess of the BART exemption level over the 3-year period modeled, and those impacts were limited to the Wolf Island WMR. Clearly this is a scenario which, if implemented by the facility, would exempt Interstate Paper from further BART requirements. However, Interstate Pape r declined to pursue this alternative.

BART Determination – Interstate Paper 227.3 Proposed alternative exemption scenario #2. The Georgia Environmental Protection Division (GA EPD) completed a BART Determination assessment of several

alternative scenarios. Based on the detailed BART analysis of cont rol options feasible for each of the BART-eligible sources, GA EP D determined that the most beneficial control option would be to limit the Po wer Boiler to burning natural gas.

In developing appropriate emissions estimates for this scenario, it was noticed that the Power Boiler is permitted as a back-up de vice for controlling non-condensable gases (NCGs). The current Title V application list the SO 2 emission rate due solely to combusting NCGs as 53.8 pounds of SO 2 per hour, and includes a limit of such operation to 1480 hours per year. AP-42 wa s used to calculate the SO 2 and NOx emission rates appropriate for firing the Power Boiler at 100 % capacity. The AP-42 emission rate was increased by the maximum SO 2 emissions due to combustion of NCGs in the Power Boiler. These emissions, indicated in Table 7 and 8, were modeled for this alternative scenario. The modeling was conducted in th e same manner as the other two modeled

scenarios.

The results of modeling the natural gas com bustion scenario are presented in Tables 9 and 10. Only Wolf Island receptors were ev aluated, since the other Class I areas had already been demonstrated to be unaffected by Interstate Paper emissions, or Interstate Paper was able to be exempted from furthe r BART requirements in these other Class I

areas.

In contrast to the baseline scenario, the natu ral gas firing scenario showed a total of 14 occurrences of impacts over 0.5 Δ dV at Wolf Island versus 30 occurrences in the baseline scenario. Thus the 3-yr period impacts de creased below the exemption level on this basis. In 2001, the number of 24-hr average exceedances of 0.5 Δ dV decreased from 8 to 6 per year; in 2002, the number decreased from 12 to 6 per year; a nd in 2003, the number decreased from 10 to 2 per year. Since none of the modeled years in the natural gas firing scenario showed a 98 th percentile high impa ct in excess of 0.5 Δ dV, the facility meets both exemption criteria by implementing this scenario.

BART Determination – Interstate Paper 237.4 BART modeling results summary . The facility has been shown to conform to BART exemption criteria for visibility impacts under the Regional Haze Regulation in

the scenario where the Power Boiler must bur n natural gas (and in selected operational scenarios, NCGs). However, since the f acility went through the BART Determination mechanism to achieve this status, the facility should not be allowed to burn #6 fuel oil in trade for periods in which NCGs are not com busted in the Power Boiler. The combustion

of NCGs should be restricted to periods of emergency only, wh en the Lime Kiln (primary NCG control device) and the Multi-fuel Bo iler (secondary NCG cont rol device) are outof-service. Both the latter two sources have existing SO 2 control devices on their exhaust streams, while the Power Boiler does not.

BART Determination – Interstate Paper 24BART Determination – Interstate Paper25INTERSTATE PAPER, LLCGeorgiaVisibility Results for 2001-2003 CALPUFF Screening RunsCALPOST, Method 6Using annual average Haze Index (HI) values in processingTable 1. Stack parameters and emissionsLambert ConformalCoordinatesStackID #LCC EastLCC NorthStackHeightBaseElevationDiameterGas ExitVelocityStackGasExitTemp.SO2EmissionsSO4EmissionsNOxEmissionsPM10EmissionsPM2.5EmissionsNH3Emissionskmkmmmmm/sKg/sg/sg/sg/sg/sg/sPB1470.712-789.03146.044.301.9815.45470.9260.50000.00008.70003.40002.0000LK1470.714-788.89715.243.601.524.96342.090.16000.00002.20000.74000.7200RB1470.714-789.02646.044.202.7413.73353.370.12000.00008.80005.50005.4000Table 2. Particle Speciationparticle speciationCondensableFilterableStack ID#filterablePM10condensable PM10organiccondensable (OC)inorganiccondensableCOARSESoilElemental Carbon (EC)%%0.625-1.0μm(g/s)0.5-0.625μm(g/s)0.625-1.0μm(g/s)0.5-0.625μm(g/s)6-10μm(g/s)2.5-6μm(g/s)1.25-2.5μm(g/s)1.0-1.25μm(g/s)0.625-1.0μm(g/s)0.5-0.625μm(g/s)1.25-2.5μm(g/s)1.0-1.25μm(g/s)0.625-1.0μm(g/s)0.5-0.625μm(g/s)PB1.70001.7000LK0.37000.3700RB2.75002.7500Note: Stack parameters and emission data obtained from “EPD BART Emissions.xls” file.The PM speciation was not provided by thestate. All PM10- H2SO4emissions were equally dividedbetween the two size categories of OC. Thisis a conservative approach since, Organiccondensable have extinction efficiency of4 m2/g.BART Determination – Interstate Paper26Table 3. Summary of Visibility ResultsClass I Area200120022003AnnualaveragebackgroundbextMaximum delta-deciview, (# days>0.5 dv, # days >1 dv)(Mm-1)Cape Romain0.330 (0 0)0.408 (0 0)0.242 (0 0)21.22Okefenokee0.670 (4 0)0.561 (3 0)1.153 (4 1)21.41St Marks0.192 (0 0)0.196 (0 0)0.247 (0 0)21.54Wolf Island1.653 (8 1)0.963 (12 0)0.938 (10 0)21.33Table 4. Visibility Results – 8 highest values200120022003Change inDeciview (dv)DayChange inDeciview (dv)DayChange inDeciview (dv)DayRankOkefenokee0.6700.5790.5200.5140.4310.4310.4310.318Feb 13Nov 19Oct 22Dec 4Jun 20Feb 12Jan 14Oct 230.5610.5160.5000.4620.4610.4560.4010.338Dec 8Oct 22Jan 27Oct 25Dec 18Jan 26Oct 14Feb 31.1530.6300.5230.5000.3910.3410.3360.328Jan 31Dec 27Nov 8Sep 10Nov 21Oct 31Jan 28Nov 1112345678Wolf Island1.6530.8510.7590.7550.6750.6650.5840.573Jan 15Sep 17Jan 10Feb 6Jan 21Sep 9Sep 18Dec 210.9630.9620.9430.8230.7510.7310.6910.650Jan 28Dec 27Nov 26Sep 17Nov 1Dec 30Jan 16Oct 260.9380.7630.7600.7070.6300.6090.5740.565Dec 8Sep 7Sep 8Jul 15Nov 22Oct 15Oct 4Nov 712345678BART Determination – Interstate Paper27Table 5. Summary of Visibility ResultsClass I Area200120022003AnnualaveragebackgroundbextMaximum delta-deciview, (# days>0.5 dv, # days >1 dv)(Mm-1)Cape Romain0.069 (0 0)0.106 (0 0)0.048 (0 0)21.22Okefenokee0.236 (0 0)0.187 (0 0)0.337 (0 0)21.41St Marks0.034 (0 0)0.041 (0 0)0.045 (0 0)21.54Wolf Island0.718 (1 0)0.502 (1 0)0.416 (0 0)21.33Table 6. Visibility Results – 8 highest values200120022003Change inDeciview (dv)DayChange inDeciview (dv)DayChange inDeciview (dv)DayRankWolf Island0.7180.3710.3450.3120.3100.2820.2310.216Jan 15Sep 17Jan 10Feb 6Dec 21Jan 21Dec 30Jan 20.5020.4200.3570.3370.3110.2860.2730.241Dec 27Nov 26Nov 1Jan 16Nov 19Dec 26Oct 26Jan 280.4160.3350.2680.2650.2570.2550.2500.189Dec 8Oct 15Sep 7Nov 30Sep 8Jan 7Jan 5Feb 912345678BART Determination – Interstate Paper28INTERSTATE PAPER, LLCGeorgiaVisibility Results for 2001-2003 CALPUFF Screening RunsCALPOST, Method 6Using annual average Haze Index (HI) values in processingTable 7. Stack parameters and emissionsLambert ConformalCoordinatesStackID #LCC EastLCC NorthStackHeightBaseElevationDiameterGas ExitVelocityStackGasExitTemp.SO2EmissionsSO4EmissionsNOxEmissionsPM10EmissionsPM2.5EmissionsNH3Emissionskmkmmmmm/sKg/sg/sg/sg/sg/sg/sPB1470.712-789.03146.044.301.9815.45470.9260.50000.00008.70003.40002.0000LK1470.714-788.89715.243.601.524.96342.090.16000.00002.20000.74000.7200RB1470.714-789.02646.044.202.7413.73353.370.12000.00008.80005.50005.4000PB*1470.712-789.03146.044.301.9815.45470.926.810.000013.833.40002.0000Table 8. Particle Speciationparticle speciationCondensableFilterableStack ID#filterablePM10condensable PM10organiccondensable (OC)inorganiccondensableCOARSESoilElemental Carbon (EC)%%0.625-1.0μm(g/s)0.5-0.625μm(g/s)0.625-1.0μm(g/s)0.5-0.625μm(g/s)6-10μm(g/s)2.5-6μm(g/s)1.25-2.5μm(g/s)1.0-1.25μm(g/s)0.625-1.0μm(g/s)0.5-0.625μm(g/s)1.25-2.5μm(g/s)1.0-1.25μm(g/s)0.625-1.0μm(g/s)0.5-0.625μm(g/s)PB1.70001.7000LK0.37000.3700RB2.75002.7500PB*1.70001.7000Note: Stack parameters and emission data obtained from “EPD BART Emissions.xls” file.The PM speciation was not provided by thestate. All PM10- H2SO4emissions were equally dividedbetween the two size categories of OC. Thisis a conservative approach since, Organiccondensable have extinction efficiency of4 m2/g.* Power Boiler as modified by GA EPD for Determination modeling toONLYWolf Island. Natural gas PTE includes ability tocombust non-condensable gases at 53.8 #/hr SO2.BART Determination – Interstate Paper29Table 9. Summary of Visibility ResultsClass I Area200120022003AnnualaveragebackgroundbextMaximum delta-deciview, (# days>0.5 dv, # days >1 dv)(Mm-1)Cape Romain0.330 (0 0)0.408 (0 0)0.242 (0 0)21.22Okefenokee0.670 (4 0)0.561 (3 0)1.153 (4 1)21.41St Marks0.192 (0 0)0.196 (0 0)0.247 (0 0)21.54Wolf Island1.653 (8 1)0.963 (12 0)0.938 (10 0)21.33Wolf Island*1.380 (6 1)0.873 ( 6 0)0.773 ( 2 0)21.33BART Determination – Interstate Paper30Table 10. Visibility Results – 8 highest values (asteriskedvalues (*) indicate GA EPD Determination modeling results)Bold format concentrations are >0.5Dv, Bold format dates are different or in different sequence from dates exemption modeled.200120022003Chg. inDeciview(dv)DayChg. inDeciview(dv)DayChg. inDeciview(dv)DayRankOkefenokee0.6700.5790.5200.5140.4310.4310.4310.318Feb 13Nov 19Oct 22Dec 4Jun 20Feb 12Jan 14Oct 230.5610.5160.5000.4620.4610.4560.4010.338Dec 8Oct 22Jan 27Oct 25Dec 18Jan 26Oct 14Feb 31.1530.6300.5230.5000.3910.3410.3360.328Jan 31Dec 27Nov 8Sep 10Nov 21Oct 31Jan 28Nov 1112345678Wolf Island1.6530.8510.7590.7550.6750.6650.5840.573Jan 15Sep 17Jan 10Feb 6Jan 21Sep 9Sep 18Dec 211.380*0.614*0.604*0.559*0.547*0.525*0.396*0.336*Jan 15Sep 17Jan 10Feb 6Jan 21Dec 21Dec 30Jan 20.9630.9620.9430.8230.7510.7310.6910.650Jan 28Dec 27Nov 26Sep 17Nov 1Dec 30Jan 16Oct 260.873*0.786*0.604*0.583*0.548*0.501*0.482*0.457*Jan 28Dec 27Nov 26Sep 17Nov 1Dec 30Jan 16Oct 260.9380.7630.7600.7070.6300.6090.5740.565Dec 8Sep 7Sep 8Jul 15Nov 22Oct 15Oct 4Nov 70.773*0.529*0.463*0.454*0.440*0.438*0.420*0.339*Dec 8Oct 15Nov 30Sep 7Jan 5Sep 8Jan7Feb 912345678BART Determination – Interstate Paper 31 APPENDIX A Impacts of SO 2 , NO x , and Primary Carbon (PC) on Okefenokee and Wolf Island Class I AreasEmission sensitivities were performed by Georgia Tech to examine the impact of SO 2 , NO x , and primary carbon (PC) on Okefenokee and Wolf Island Class I areas. The impacts (Mm -1 ) were normalized by the emissions (tons/year) to show the relative importance of SO 2 , NO x and PC emission reductions by source category and by state (Figures A-1 and A-2). Figures A-3 and A-4 contain the normalized vi sibility responses on 20% worst days at Okefenokee and Wolf Island to reductions fr om the 2009 BaseD inventory for non-EGU point SO 2 emissions and point NO x emissions in Georgia.

At Okefenokee, the light extinction impact due to one ton of non-EGU SO 2 is 2.59E-05 Mm -1 /TPY and the light extinction impact due to one ton of point NO x is 0.159E-05 Mm -1 /TPY. Therefore, the reduction of one ton of SO 2 emissions is 16.4 times more efficien t than the reduction of one ton of NO x emissions at Okefenokee.

At Wolf Island, the light extinction impact due to one ton of non-EGU SO 2 is 1.97E-05 Mm -1 /TPY and the light extinction impact due to one ton of point NO x is 0.319E-05 Mm -1 /TPY. Therefore, the reduction of one ton of SO 2 emissions is 6.2 times more efficien t than the reduction of one ton of NO x emissions at Wolf Island.



## Okefenokee, GA (Worst)

-0.00018

-0.00015

-0.00012

-0.00009

-0.00006

-0.00003

0.00000 SO2_ E

GU

S

O2_ no

nEGU NOx _Ground NOx _P

oi

n t PC_Groun d PC _P

oi

n tΔBext/ΔE (Mm-1/TPY) WV VA TN SC NC MS KY GA FL AL

Figure A-1: CMAQ projections of normalized visibility resp onses on 20% worst days at Okefenokee, GA to reductions from the 2009 BaseD inventory for visibility-reducing po llutants in different source categories and geographic areas.

BART Determination – Interstate Paper 32

## Wolf_Island, GA (Worst)

-0.00010

-0.00008

-0.00006

-0.00004

-0.00002

0.00000 SO2_ E

GU

S

O2_ no

nEGU NOx _Ground NOx _P

oi

n t PC_Groun d PC _P

oi

n tΔBext/ΔE (Mm-1/TPY) WV VA TN SC NC MS KY GA FL AL

Figure A-2 : CMAQ projections of normalized visibility resp onses on 20% worst days at Wolf Island, GA to reductions from the 2009 BaseD inventory for visibility-reducing po llutants in different source categories and geographic areas.



## Okefenokee, GA (Worst)

-0.000030

-0.000025

-0.000020

-0.000015

-0.000010

-0.000005

0.000000 SO2_nonEGU NOx_PointΔBext/ΔE (Mm-1/TPY)

GA

Figure A-3: CMAQ projections of normalized visibility resp onses on 20% worst days at Okefenokee, GA to reductions from the 2009 BaseD invent ory for non-EGU point SO2 emissi ons and point NOx emissions in Georgia.

BART Determination – Interstate Paper 33

## Wolf_Island, GA (Worst)

-0.000025

-0.000020

-0.000015

-0.000010

-0.000005

0.000000 SO2_nonEGU NOx_PointΔBext/ΔE (Mm-1/TPY)

GA

Figure A-4: CMAQ projections of normalized visibility resp onses on 20% worst days at Wolf Island, GA to reductions from the 2009 BaseD invent ory for non-EGU point SO2 emissi ons and point NOx emissions in Georgia.

BART Determination – Interstate Paper 34