1

Technical Support Document for

North Carolina Regional Haze SIP Submittal

January 2012

U.S. EPA – Region 4 Atlanta, GA
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Technical Support Document (TSD) for 

North Carolina Regional Haze SIP Submittal

Table of Contents

I. Background

II. Summary of EPA’s Action

III. Evaluation of State Regional Haze Submittal

A. Identification of Areas

B. Reasonable Progress Goals Development

1. Calculations of Baseline Visibility Conditions

2. Calculations of Natural Visibility Conditions

3. Uniform Rate of Progress (UROP or “Glidepath”) for 

Reasonable Progress

C. Long Term Strategy

1. Technical Basis for Strategy

2. Identification of Sources and Factors to be Considered

3. Source or Source Category Specific Analyses for 

Reasonable Progress

4. Enforceability of Reasonable Progress Measures

D. Best Available Retrofit Technology (BART) Requirements

1. Identification of all BART Eligible Sources

2. Modeling or other Demonstrations for BART Exempt 

Sources

3. Identification of Sources Addressed by Clean Air 

Interstate Rule (CAIR)

4. Source Specific BART Determinations

5. Enforceability of BART

E. Coordination of Regional Haze and RAVI Requirements

F. Monitoring Strategy and Other Implementation Requirements

G. Emission Inventory

IV. Conclusion

__________________________________________________________________

Note: Italicized text in this document that appears under the “State Regional Haze Submittal” 

headings are excerpts from relevant portions of the North Carolina regional haze submittal as 

cited. Figure and table citations under these headings reflect the actual references as listed in the 

State’s SIP submittal. Page numbers refer to the SIP Narrative, unless otherwise specified.
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TSD for North Carolina Regional Haze SIP Submittal

I. Background

In Section 169A of the 1977 Amendments to the Clean Air Act (CAA), Congress set forth a 

program for protecting visibility in Federal Class I areas which calls for the “prevention of any 

future, and the remedying of any existing, impairment of visibility in mandatory Federal Class I 

areas which impairment results from manmade air pollution.” Congress adopted the visibility 

provisions to protect visibility in 156 Federal Class I areas, which include certain national parks, 

memorial parks, and wilderness areas over a certain size, and all international parks. These areas 

are defined at 40 CFR 81.400, and listed by state at 40 CFR 81.401-81.437. On December 2, 

1980, EPA promulgated regulations to address visibility impairment that is “reasonably 

attributable” to a single source or small group of sources. 45 FR 80084. These regulations 

represented the first phase in addressing visibility impairment and deferred action on regional 

haze that emanates from a variety of sources until monitoring, modeling and scientific knowledge 

about the relationships between pollutants and visibility impairment improved. 

In the 1990 Amendments to the CAA, Congress added Section 169B and called on EPA to issue 

Regional Haze rules. The regional haze rule (RHR) that EPA promulgated on July 1, 1999 (64 FR 

35713) revised the existing visibility regulations to integrate provisions addressing regional haze

visibility impairment and establish a comprehensive visibility protection program for Federal 

Class I areas. States are required to submit state implementation plans (SIPs) to EPA that set out 

each state’s plan for complying with the RHR, including consultation and coordination with other 

states and with Federal Land Managers (FLMs). States must submit a regional haze SIP to EPA 

within three years after the date of designation of areas under the National Ambient Air Quality 

Standard (NAAQS) for fine particulate matter (PM2.5). EPA promulgated PM2.5 designations 

on December 17, 2004, and thus, regional haze SIPs were to be submitted to EPA by December 

17, 2007, which is also specified at 40 CFR 51.308(b).

The RHR addressed the combined visibility effects of various pollution sources over a wide 

geographic region. Consequently, all 50 states, including those without Class I areas, 

Washington, D.C., and the Virgin Islands, are required to submit Regional Haze SIPs. 40 CFR 

51.300(b)(3). EPA designated five Regional Planning Organizations (RPOs) to assist with the 

coordination and cooperation needed to address the visibility issue. The RPO that makes up the 

southeastern portion of the contiguous United States is known as VISTAS (Visibility 

Improvement – State and Tribal Association of the Southeast). VISTAS members include: the 

Eastern Band of the Cherokee Indians, other Federally Recognized Tribes and Local Air 

Programs within the geographic area, and the following states: Alabama, Florida, Georgia, 

Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia. 

The State of North Carolina through the North Carolina Division of Air Quality (NCDAQ) chose 

to participate in VISTAS to develop the technical analyses needed to fulfill the requirements of 

the RHR.
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Figure 1. Geographical Areas of Regional Planning Organizations 

 

 Figure 2. Class I Areas in the VISTAS Region 
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II. Summary of Action

EPA is proposing a limited approval of a revision to the North Carolina state implementation plan 

(SIP) submitted by the State of North Carolina through the North Carolina Department of 

Environment and Natural Resources, Division of Air Quality (NCDAQ), on December 17, 2007, 

that addresses regional haze for the first implementation period. This revision addresses the 

requirements of the Clean Air Act (CAA) and EPA’s rules that require states to prevent any 

future and remedy any existing anthropogenic impairment of visibility in mandatory Class I areas 

(national parks and wilderness areas) caused by emissions of air pollutants from numerous 

sources located over a wide geographic area (also referred to as the “regional haze program”). 

States are required to assure reasonable progress toward the national goal of achieving natural 

visibility conditions in Class I areas. EPA is proposing a limited approval of this SIP revision to 

implement the regional haze requirements for North Carolina on the basis that the revision, as a 

whole, strengthens the North Carolina SIP. In a separate action, EPA has proposed a limited 

disapproval of the North Carolina regional haze SIP because of deficiencies in the State’s 

regional haze SIP submittal arising from the remand by the U.S. Court of Appeals for the District 

of Columbia Circuit (D.C. Circuit) to EPA of the Clean Air Interstate Rule (CAIR). 

Consequently, EPA is not proposing to take action in this rulemaking to address the State’s 

reliance on CAIR to meet certain regional haze requirements.
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III. Evaluation of State Regional Haze Submittal

A. Identification of Areas 

The SIP must identify each mandatory Class I Federal area located within the State and in each 

mandatory Class I Federal area located outside the State that may be affected by emissions from 

within the State. Where a mandatory Class I Federal area is in multiple states, a description of 

how the states have assigned responsibilities for the area needs to be included.

State Regional Haze Submittal

NC SIP Narrative, Page 4:

North Carolina has five mandatory Class I Federal areas within its borders. These are Great 

Smoky Mountains National Park;

Joyce Kilmer-Slickrock Wilderness Area; 

Linville Gorge Wilderness Area,

Shining Rock Wilderness Area; and 

Swanquarter Wildlife Refuge.

The North Carolina Division of Air Quality (NCDAQ) in the North Carolina Department of 

Environment and Natural Resources is responsible for developing the Regional Haze SIP. The 

Great Smoky Mountains and Joyce Kilmer-Slickrock are located in both Tennessee and North 

Carolina. For the Great Smoky Mountains, both states are sharing the lead for setting goals and 

for Joyce Kilmer-Slickrock, North Carolina is the lead.

Figure 3. North Carolina’s Class I areas

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision. 
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III. Evaluation of Regional Haze Submittal

B. Reasonable Progress Goals Development 

B.1.Calculations of Baseline Visibility Conditions: ((40 CFR 51.308(d)(2)(i))

The period for establishing baseline visibility conditions is 2000 to 2004. For each mandatory 

Class I Federal area located within the State, the State must determine the average degree of 

visibility impairment (expressed in deciviews) for the most impaired and least impaired days (i.e. 

the 20% most impaired days and 20% least impaired days) for each of these years. Baseline 

conditions are the average of these annual values. For each mandatory Class I Federal area 

located within the State, the SIP needs to calculate the number of deciviews by which baseline 

conditions exceed natural visibility conditions for the most impaired and least impaired days.

Where onsite monitoring is not available the baseline visibility conditions must be established 

using the most representative monitoring available for the 2000-2004 period in consultation with 

EPA.

State Regional Haze Submittal

NC SIP Narrative, Page 9:

Baseline visibility conditions at each North Carolina Class I area are estimated using sampling 

data collected at IMPROVE monitoring sites at four of the five Class I areas in North Carolina.

A five-year average (2000 to 2004) was calculated for each of the 20% worst and 20% best 

visibility days in accordance with 40 CFR 51.308(d)(2) and Guidance for Tracking Progress 

Under the Regional Haze Rule, EPA-454-03-004, September, 2003. IMPROVE data records for 

Great Smoky Mountains and Linville Gorge for the period 2000 to 2004 meet the USEPA 

requirements for data completeness (75 percent for the year and 50 percent for each quarter).

Shining Rock and Swanquarter had missing data in more than one year from 2000 to 2004. Data 

records for these sites were filled using data substitution procedures outlined in Appendix B.1. 

IMPROVE does not operate a monitor at Joyce Kilmer Wilderness and considers the IMPROVE 

monitor at Great Smoky Mountains to be representative of visibility in the Joyce Kilmer area. The 

light extinction and deciview visibility values for the 20% worst and 20% best visibility days at 

the Class I areas are based on data and calculations included in Appendix B.1 of the SIP 

submittal.
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Figure 4. Baseline Visibility Conditions for North Carolina Class I Areas (2002-2004)

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision. EPA proposes to concur that the use of data from the Great Smoky Mountains 

IMPROVE site is appropriate for establishing baseline conditions for the Joyce Kilmer –

Slickrock wilderness area.

Class I area Average for

20% Worst

Days

(deciviews)

Average for

20% Best

Days

(deciviews)

Average for

20% Worst

Days

Bext (Mm-1)

Average for

20% Best

Days

Bext (Mm-1)

Great Smoky 

Mountains 

30.3 13.6 216.3 40.2

Joyce KilmerSlickrock 30.3 13.6 216.3 40.2

Linville Gorge 28.8 11.1 183.6 31.2

Shining Rock 28.5 7.7 182.2 22.3

Swanquarter 24.7 12.0 123.9 33.7
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III. Evaluation of Regional Haze Submittal

B. Reasonable Progress Goals Development 

B.2. Calculations of Natural Visibility Conditions: ((40 CFR 51.308(d)(2)(iii))

For each mandatory Class I Federal area located within the State, natural visibility conditions 

must be calculated by estimating the degree of visibility impairment existing under natural 

conditions for the most impaired and least impaired days, based on available monitoring 

information and appropriate data analysis techniques as specified in EPA-454/B-03-005,

Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Program or an 

approved alternative technique. 

State Regional Haze Submittal

NC SIP Narrative, Page 8:

Procedures for calculating natural background visibility are delineated in “Guidance for 

Estimating Natural Visibility Conditions Under the Regional Haze Program”, EPA-454/B-03-

005, September 2003. In the 2003 guidance, the USEPA also provided that states may use a 

“refined approach” to estimate the values that characterize the natural visibility conditions of the 

Class I areas. The purpose of such a refinement would be to provide more accurate estimates 

with changes to the extinction algorithm that may include the concentration values, factors to 

calculate extinction from a measured particular species and particle size, the extinction 

coefficients for certain compounds, geographical variation (by altitude) of a fixed value, and the 

addition of visibility pollutants.

In 2005, the IMPROVE Steering Committee made recommendations for a refined equation that 

modifies the terms of the original equation to account for the most recent data. The choice 

between use of the old or the new equation for calculating the visibility metrics for each Class I 

area is made by the state in which the Class I area is located.

The new IMPROVE equation accounts for the effect of particle size distribution on light 

extinction efficiency of sulfate, nitrate, and organic carbon. The mass multiplier for organic 

carbon (particulate organic matter) is increased from 1.4 to 1.8. New terms are added to the 

equation to account for light extinction by sea salt and light absorption by gaseous nitrogen 

dioxide. Site-specific values are used for Rayleigh scattering to account for the site-specific 

effects of elevation and temperature. Separate relative humidity enhancement factors are used for 

small and large size distributions of ammonium sulfate and ammonium nitrate and for sea salt. 

The elemental carbon (light-absorbing carbon), fine soil, and coarse mass terms do not change 

between the original and new IMPROVE equation. 

Natural background conditions using the new IMPROVE equation are calculated separately for 

each Class I area. The calculation starts with the annual average values for natural background 

for each component of PM2.5 mass from the EPA 2003 guidance (default values). The annual 

frequency distribution of values of each PM2.5 component for current conditions (2000-2004) is 

then defined. This species-specific frequency distribution is applied to the default annual average 

values for that PM2.5 component to calculate natural conditions on the 20% worst days. The 

current variability in each component is retained while also retaining the same annual average 
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background condition for that component as defined in the 2003 guidance. The new calculation of 

natural background allows Rayleigh scattering to vary with elevation. Current sea salt values are 

used for natural background levels of sea salt.

The VISTAS states chose to use the new IMPROVE equation as the basis for the conceptual 

description because it takes into account the most recent review of the science and because it is 

recommended by the IMPROVE Steering Committee.

The specific values used by NCDAQ are based on a report prepared for VISTAS by: Air Resource 

Specialists, Inc., 1901 Sharp Point Drive, Suite E, Fort Collins, Colorado 80525 and are documented 

in Appendix B.1.

Class 1 area Average for

20% Worst

Days

(deciviews)

Average for

20% Best

Days

(deciviews)

Average for

20% Worst

Days

Bext (Mm-1)

Average for

20% Best

Days

Bext (Mm-1)

Great Smoky 

Mountains

11.1 4.5 30.8 15.8

Joyce KilmerSlickrock11.1 4.5 30.8 15.8

Linville Gorge 11.2 4.1 30.9 15.1

Shining Rock 11.5 2.5 34.9 12.1

Swanquarter 11.5 5.5 32.6 17.3

Figure 5. Natural Background Conditions for North Carolina Class I Areas

NC SIP, Appendix L.8:

On March 19, 2007, in a letter from Keith Overcash to James I. Palmer, Regional Administrator, US 

EPA Region 4, NCDENR requested approval for the use of the VISTAS methodology for the new 

IMPROVE equation.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision. In a May 11, 2007, letter from James I. Palmer, Regional Administrator, EPA Region 

4, to B. Keith Overcash, NCDAQ, EPA Region 4 approved the use of the new IMPROVE 

equation (NC Regional Haze SIP, Appendix L.8, page 37). 
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III. Evaluation of Regional Haze Submittal

B. Reasonable Progress Goals Development 

B.3. Uniform Rate of Progress (UROP or “Glidepath”) for Reasonable Progress: (40 CFR 

51.308(d)(1) and (40 CFR 51.308(d)(1)(i)(B))

For each mandatory Class I Federal area located within the State, the State must establish goals 

(expressed in deciviews) that provide for reasonable progress towards achieving natural visibility 

conditions. For each Class I area within the State, the State must analyze and determine the rate 

of progress needed to attain natural visibility conditions by the year 2064 and determine the 

uniform rate of visibility improvement (measured in deciviews) that would need to be maintained 

during each implementation period in order to attain natural visibility conditions by 2064. The 

State must show that the reasonable progress goal for each mandatory Class I Federal area 

represents at least as much visibility improvement as is expected to result from implementation of 

other requirements of the CAA during the applicable planning period (40 CFR 51.308(d)(1)(vi)).

The reasonable progress goals must provide for an improvement in visibility for the most 

impaired days over the period of the implementation plan and ensure no degradation in visibility 

for the least impaired days over the same period.

State Regional Haze Submittal

NC SIP Narrative, Pages 16-18:

The SIP presents glidepaths for the 20% most impaired days for Great Smoky Mountains 

National Park, Joyce Kilmer-Slickrock Wilderness Area, Linville Gorge Wilderness Area, Shining 

Rock Wilderness Area, and Swanquarter Wildlife Refuge, assuming uniform rate of progress 

toward regional haze goals (figures 3.1-1 to 3.1-5 [figures 6-10 below] ) with values calculated 

every five years starting at the 2004 base year and continuing to natural background in 2064. 

Natural background visibility at all four sites is predicted to be between 11 and 12 dv. The Class 

I areas with the steepest slope from baseline to natural background conditions are Great Smoky 

Mountains and Joyce Kilmer-Slickrock, while Swanquarter currently has the shortest path from 

the baseline level of visibility impairment to natural conditions.
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Figure 6. Uniform Rate of Progress Glidepath for 20% worst days at Great Smoky

Mountains National Park.

Figure 7. Uniform Rate of Progress Glidepath for 20% worst days at Joyce KilmerSlickrock Wilderness Area.
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Figure 8. Uniform Rate of Progress Glidepath for 20% worst days at Linville Gorge

Wilderness Area.

Figure 9. Uniform Rate of Progress Glidepath for 20% worst days at Shining Rock

Wilderness Area.
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Figure 10. Uniform Rate of Progress Glidepath for 20% worst days at Swanquarter

Wildlife Refuge.

NC SIP Narrative, Pages 51-56:

Using 2000 - 2004 IMPROVE monitoring data, the deciview values for the 20% best days in each 

year are averaged together, producing a single average deciview value for the best days. 

Similarly, the deciview values for the 20% worst days in each year are averaged together, 

producing a single average deciview value for the worst days. The average values represent the 

current visibility conditions.

The predicted visibility improvement is calculated by comparing the 2002 typical year modeling 

results for the 12-km grid to the 2018 12-km modeling results to develop a relative reduction 

factor. This factor is then applied to the current visibility condition values to estimate the future 

visibility. Detailed discussions about how the relative reduction factors are calculated can be 

found in Appendix G.

Visibility improvements for the 20% worst days in all five Class I areas in North Carolina, are 

expected to be better than the uniform rate of progress by 2018 based solely on reductions from 

existing and planned emissions controls (figures 7.2.4-1 to 7.2.4-10). For example, at Great 

Smoky Mountains, a 4.5 dv improvement in visibility would meet uniform rate of progress in 

2018; expected emissions reductions by 2018 are projected to achieve a 6.6 dv improvement. The 

predicted percentage of the target reduction achieved for the North Carolina Class I areas, using 

the new IMPROVE equation, is between 140% and 180%. This means that the amount of 

visibility improvement expected from the modeled control programs is 40% to 80% more than 

what the uniform rate of progress would be for 2018 (figure 7.4.2-11).
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In addition to improving visibility on the 20% worst visibility days, states are also required to 

protect visibility on the 20% best days at the Class I areas. Visibility on the 20% best days is 

projected to improve in 2018 at all VISTAS Class I areas as a result of the emissions reductions 

expected from federal and state control programs (figures 7.2.4-6 to 7.2.4-10). The percentage of 

the target achieved for the North Carolina Class I areas is about -10% (figure 7.2.4-12). Zero 

percent change would mean no change in visibility; -10% means that visibility is better than no 

change, or a 10% improvement (values lower than current conditions).

Class I Area Baseline 

Visibility for 

20% Worst 

Days 

Reasonable 

Progress Goal -

20% Worst Days 

(Improvement)

Baseline 

Visibility for 

20% Best 

Days

Reasonable 

Progress Goal -

20% Best Days 

(Improvement)

Great Smoky

Mountains National

Park

30.3 23.7 (6.6) 13.6 12.2 (1.4)

Joyce KilmerSlickrock Wilderness

Area

30.3 23.7 (6.6) 13.6 12.2 (1.4)

Linville Gorge

Wilderness Area 28.8 22.0 (6.8) 11.1 9.6 (1.5)

Shining Rock

Wilderness Area 28.5 22.1 (6.4) 7.7 6.9 (0.8)

Swanquarter Wildlife

Refuge 24.7 20.4 (4.3) 12.0 11.0 (1.0)

Figure 11. North Carolina 2018 Reasonable Progress Goals (in deciviews) 
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Figure 12. Reasonable progress assessment compared to Uniform Rate of Progress for 20% 

worst days at Great Smoky Mountains National Park.

Figure 13. Reasonable progress assessment compared to Uniform Rate of Progress for 20% 

worst days at Joyce Kilmer-Slickrock Wilderness Area.
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Figure 14. Reasonable progress assessment compared to Uniform Rate of Progress for 20% 

worst days at Linville Gorge Wilderness Area.

Figure 15. Reasonable progress assessment compared to Uniform Rate of Progress for 20% 

worst days at Shining Rock Wilderness Area.

Figure 16. Reasonable progress assessment compared to Uniform Rate of Progress for 20% 

worst days at Swanquarter Wildlife Refuge.
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Figure 17. Reasonable progress assessment for 20% best days at Great Smoky

Mountains National Park.

Figure 18. Reasonable progress assessment for 20% best days at Joyce KilmerSlickrock Wilderness Area.
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Figure 19. Reasonable progress assessment for 20% best days at Linville Gorge

Wilderness Area.

Figure 20. Reasonable progress assessment for 20% best days at Shining Rock

Wilderness Area.
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Figure 21. Reasonable progress assessment for 20% best days at Swanquarter Wildlife 

Refuge.

NC SIP, Appendix G, Pages G-5 to G-13:

Reasonable Progress Goals

For each Class I area, there are three metrics of visibility that are part of the determination of 

reasonable progress:

1) Natural conditions,

2) Baseline conditions

3) Current conditions.

Each of the three metrics includes the concentration data of the visibility impairing pollutants as 

different terms in the light extinction algorithm, with respective extinction coefficients and 

relative humidity factors. Total light extinction is then converted to deciviews, and an average 

value for both the 20 percent best and 20 percent worst visibility days is calculated.

After the natural, baseline, and current conditions are calculated, a uniform rate of progress, or 

glidepath, can be created for the 20% worst days for each Class I area. Next, an analysis of 

potential control measures is performed to determine what level of control would be achievable 

in the given timeframe and what the potential improvement to visibility would be as a result of 

these controls. After the potential control analysis, reasonable progress goals for the Class I 

areas are determined after consultation with surrounding states. The entire RPG determination 

for North Carolina Class I areas is described in Appendix H.

Model Application
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The purpose of a modeling assessment of uniform rate of progress is to determine if a proposed

control strategy will result in uniform rate of progress being met when measured concentrations 

of particulate matter are used to estimate visibility impairment at some future date. The modeling 

is applied in a relative sense, similar to the fine particulate matter (PM25) attainment test. The 

following sections outline the process to determine 2018 projections from regional modeling, as 

suggested in the “Guidance on the Use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze”(from this point forward, 

referred to as “Attainment Guidance”).

3.1 Determination of 20% Best and worst Days

The first step in developing model projections is to rank visibility (in deciviews) on each day with 

observed speciated PM2.5 data for each of the 5 years comprising the base period (2000-

2004) for each Class I area. Day-specific observations for mass associated with sulfate (SO4), 

nitrates (NO3), organic carbon (OC), elemental carbon (EC), soil, and coarse matter (CM), 

should be used to calculate bext for each day using climatological relative humidity adjustment 

factor(s) (f(rh)). Total light extinction (bext) for all components should be converted to deciviews 

for each day to get a daily deciview value.

3.2 Determine Baseline Conditions

The ranked visibility days from the first step are then used to calculate the average baseline 

deciviews for the 20% best and worst days. First, the mean deciview value for the identified 20% 

worst- and best visibility days in each year is calculated (dv current). The 5 year mean deciview 

values reflecting mean visibility on the days with best visibility and then averaged to determine 

the baseline values for the best days, or the dv baseline values. Then the 5 year mean deciview 

values reflecting worst visibility are averaged together. This represents the value subject to 

improvement to meet the glidepath for regional haze.

For each of the North Carolina Class I areas, the baseline visibility conditions were estimated 

using sampling data collected at Interagency Monitoring of Protected Visual Environments 

(IMPROVE) monitoring sites at four of the five Class I areas in North Carolina. A five year 

average (2000 to 2004) was calculated for each of the 20 percent worst and 20 percent best 

visibility days in accordance with 40 CFR 51.308(d)(2) and the USEPA‟s Guidance for Tracking 

Progress Under the Regional Haze Rule. IMPROVE data records for Great Smoky Mountains 

and Linville Gorge for the period 2000 to 2004 meet the USEPA‟s requirements for data 

completeness (75 percent for the year and 50 percent for each quarter). Shining Rock and 

Swanquarter had missing data in more than one year between 2000 and 2004. Data records for 

these sites were filled using data substitution procedures outlined in Appendix B. IMPROVE does 

not operate a monitor at Joyce Kilmer Wilderness Area and considers the IMPROVE monitor at 

Great Smoky Mountains to be representative of visibility in the Joyce Kilmer Wilderness Area. 

The light extinction and deciview visibility values for the 20 percent worst and 20 percent best 

visibility days at the Class I areas are based on data and calculations included in Appendix B of 

this SIP. Table 3.2-1 summarizes the mean yearly visibility conditions and the baseline visibility 

conditions for North Carolina Class I areas on both the 20% best and 20% worst days.
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3.3 Relative Response Factor Calculation

The next step is to use base year and future year modeling results to estimate a relative response

factor (RRF) for each component of PM2.5 on the 20% best and worst monitoring days. Simply

put, the RRF is the average future year concentration near the monitor divided by the average

base year concentration or:

RRF = Average Modeled Future Year Concentration/Average Modeled Base Year Concentration

To accomplish this step, concentration for each component of PM2.5 and coarse matter (the

difference between particles less than 10 micrometers in diameter (PM10) and PM2.5) are

extracted from the base year and future year modeling output near IMPROVE monitoring sites

for the monitored best and worst days. The component concentrations are then averaged to

develop base and future year average component concentrations. The future year average

component concentrations are then divided by their respective base year component

concentrations to develop RRFs for each component of PM2.5 and coarse matter.

For a numerical example, consider Table 3.3-1, which has all the pertinent data for the GSMNP1

IMPROVE monitor. Looking at the top table, the first column identifies the 20% best days

identified in step 1 (Section 3.1). The next six columns have the 12km modeled base year (2002

concentration values near the monitor corresponding to the 20% best days. The next six columns

have the 12km modeled future year (2018) component concentrations near the monitor for the

same set of days. The final six columns contain the daily RRF values for each component species, 

which is simply the future concentration divided by the base year concentration. The bottom row 

of the table contains the average values for the base year components, the future year

components, and the RRFs for each of the average component values. The bottom table contains

the same data for the 20% worst days. Tables of for each of the IMPORVE monitors of interest to 

North Carolina are provided, and abide by the same format.
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24
25
26
27

3.4. Future Year Daily Concentration Calculation

The fourth step in using model output to estimate the future visibility impairment is to multiply the 

relative response factors (determined in the previous step, Section 3.3) by the measured species 

concentration data during the base period (for the measured 20% best and worst days). This 

results in daily future year species concentrations data.

This is similar to the final step in the ozone attainment test, where base year concentrations, or

the current year design value (DVC) is multiplied by the RRF to determine the future design value 

(i.e. DVF = RRF * DVC). For regional haze, this calculation is performed for each best and 

worst day for the five-year base line period (calculated in step 2, Section 3.2) using an RRF for 

each PM component, for both the best days and the worst days. This produces future

concentration estimates for SO4, NO3, OC, EC, Soil and CM, for each of the “worst” and “best”

visibility days.

3.5. Future Year Daily bext Calculation

Once future year concentrations are calculated (Section 3.4) the future daily extinction

coefficients are then calculated for the 20% best and 20% worst visibility days in each of the five

base years. This is achieved by applying the new IMPROVE equation (see Appendix B for a more 

information on the new IMPROVE equation):

bext ≈ 2.2 * fs(RH) * [Small Sulfate] + 4.8 * fL(RH) * [Large Sulfate]

+ 2.4 * fs(RH) * [Small Nitrate] + 5.1 * fL(RH) * [Large Nitrate]

+ 2.8 * {Small Organic Mass] + 6.1 * [Large Organic Mass]

+ 10 * [Elemental Carbon]

+ 1 * [Fine Soil]

+ 1.7 * fss(RH) * [Sea Salt]

+ 0.6 * [Coarse Mass]

+ Rayleigh Scattering (site specific)

+ 0.33 * [NO2 (ppb)]

Model estimated daily concentrations are used with the corresponding base line daily relative

humidity adjustment factor(s) (f(rh)) identified in step 1 (Section 3.1).

3.6. Future Mean Deciview Values Calculation

The final step is to calculate daily deciview values from the total daily extinction calculated in the 

previous step, and then compute the future average mean deciviews for the worst and best day for 

each year. The 5 years are then averaged together to get the final future mean deciview value for 

the worst and best days.

The first step in this process is to convert the total daily bext for each day (calculated in the

previous step, Section 3.5) to deciviews. This future year daily deciview value for each of the best 

and worst days is then averaged to determine the future deciview value for the “worst” and

“best” visibility days for each year. This leads to 5 future estimated mean deciview values for the

Modeling Results & Supplemental Analysis “worst” and 5 future estimated mean deciview values 

for the “best” visibility days. The five yearly values for the best and worst days are then averaged 

to produce the final future mean deciview value, or dv future. Table 3.6-1 displays the yearly 
28

daily deciview value for each year in the baseline period for both the 20% worst days (center 

column) and the 20% best days (right column). The last row in the table displays the final future 

mean deciview value, or dv future.

The resulting dv future values for the “worst” and “best” visibility days can be compared to the

dv baseline values calculated in step 2 (Section 3.2). If the resulting change in deciviews is a

negative number (future - base), this represents an improvement in visibility. Table 3.6-2

summarizes these calculation for the IMPROVE monitors associated with North Carolina Class I

areas. From the table, it is apparent that all North Carolina Class I areas are showing visibility

improvement on both the 20% best and 20% worst days

.

These changes in visibility can also be compared to the previously calculated (in Appendix B

uniform rate of progress values for each Class I area (Figures 3.6-1 through 3.6-4). When plotted 

against the glidepath, one can see the change in deciview between the baseline and future shows 

an improvement that is well below the uniform rate of progress for all Class I monitoring sites in 

North Carolina.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision. North Carolina’s reasonable progress goals for Great Smoky Mountain National Park 

and Joyce Kilmer-Slickrock Wilderness Area differ from those submitted by Tennessee. North 

Carolina confirmed in a February 16, 2010 letter from Keith Overcash, NCDAQ, to Stanley 

Meiburg, EPA Region 4 that the Tennessee values reflect the latest modeling completed after 

North Carolina completed its submittal and are the more appropriate targets. NCDAQ commits to 

revise their RPGs for these areas in the next five year submittal. EPA proposes to find this 

approach acceptable. 
29

III. Evaluation of Regional Haze Submittal

C. Long-Term Strategy 

C.1. Technical Basis for Strategy (40 CFR 51.308(d)(3)(iii))

The SIP must document the technical basis, including modeling, monitoring and emissions 

information, on which the State is relying to determine its apportionment of emission reduction 

obligations necessary for achieving reasonable progress in each mandatory Class I Federal area it 

affects. The State may meet this requirement by relying on technical analyses developed by the 

regional planning organization and approved by all State participants. 

Modeling is not used to determine reasonable progress goals and does not determine whether 

reasonable progress has been met. Modeling is one part of the reasonable progress analysis. The 

modeling results are used to compare progress made through emission reductions with future year 

visibility at Class I areas. Note that the emission inventory requirements under 40 CFR 

51.308(d)(4)(v) are addressed in this section.

EPA Outline of Long Term Strategy Components:

The RHR at 51.308(d) requires states to demonstrate reasonable progress toward meeting the goal 

of a return to natural visibility conditions by 2064. The RHR then requires states to establish 

RPGs for visibility improvement at each affected Class I area covering each approximately 10-

year period until 2064. Appendix H provides an overview of this first LTS. Appendix L includes 

a discussion of the State’s strategy for assessing the BART requirements.

The North Carolina LTS contains the following components:

I. Emission inventory applying all controls required or expected under all federal and 

state regulations by 2009 and 2018.

II. Modeled expected visibility improvement and comparison of modeling results for 

2018 to the uniform rate of progress, or “glidepath” for each Class I area. (See also 

EPA TSD Section III.B.3)

III. Discussion of emissions sensitivity model runs to help determine which pollutants and 

source categories are contributing the most to visibility impairment at Class I areas 

(runs conducted by the Georgia Institute of Technology).

IV. Examination of sulfur dioxide (SO2) area of influence (AOI) projections for each of 

North Carolina’s Class I areas, and also for any surrounding states’ Class I areas 

whose AOI includes any part of North Carolina, to determine which specific sources 

are most likely to be impairing visibility at specific Class I areas.

V. Application of the four “statutory factors” listed in 40 CFR 51.308(d)(1)(i)(A) to those 

sources identified in the previous step. (See also EPA TSD Section III.C.3)

VI. Using the results of the four factor analyses, identification of control determinations 

for specific sources.

VII. Identification of BART-eligible sources. (See also EPA TSD Section III.D.1)

VIII. BART exemption modeling for BART-eligible sources. (See also EPA TSD Section 

III.D.2)
30

IX. BART determinations for sources subject to BART. (See also EPA TSD Section 

III.D.3)

X. Modeling demonstration of visibility improvement after inclusion of BART and 

reasonable control measure determinations.

XI. Determination of RPGs based on the visibility improvement expected by 2018.

State Regional Haze Submittal

Federal and State Control Requirements (NC SIP Narrative, Pages 45-59)

CAIR. CAIR will permanently cap emissions of SO2 and NOx from EGUs in the eastern United 

States by 2015. When fully implemented, CAIR will reduce SO2 emissions from EGUs in these 

states by more than 70%, and NOx emissions by more than 60%, from 2003 levels.

NOx SIP Call. Phase I of the NOx SIP call applies to certain EGUs and large non-EGUs, 

including large industrial boilers and turbines, and cement kilns. Those states affected by the 

NOx SIP call in the VISTAS region have developed rules for the control of NOx emissions that 

have been approved by the USEPA. The NOx SIP Call has resulted in a 68% reduction in 

summertime NOx emissions from large stationary combustion sources in North Carolina. For 

this analysis, we capped the emissions for NOx SIP call-affected sources at 2007 levels, and 

carried forward the capped levels for the 2009 and 2018 future year inventories.

North Carolina Clean Smokestacks Act (CSA). Under the CSA, enacted in 2002, coal-fired power 

plants in North Carolina must achieve a 77-percent cut in NOx emissions by 2009 and a 73-

percent cut in SO2 emissions by 2013. This legislation establishes annual caps on both SO2 and 

NOx emissions for the two primary utility companies in North Carolina, Duke Energy and 

Progress Energy. These reductions must be made in North Carolina, and allowances cannot be 

sold.

Georgia Multi-pollutant Bill. Georgia enacted regulations in summer 2007 to require coal fired 

power plants in Georgia to reduce SO2 by approximately 90%, NOx by approximately 50%, and 

mercury by an estimated 75-85% by 2015. Reductions will affect 21 units at seven facilities. The 

rule requires specific controls on specific units according to a specific schedule. This is not a cap 

and trade rule, thus there are no allowances to be banked, sold or traded. 

Consent Agreements.

Under a settlement agreement, by 2008, Tampa Electric will install permanent emissions-control 

equipment to meet stringent pollution limits; implement a series of interim pollution-reduction 

measures to reduce emissions while the permanent controls are designed and installed; and retire 

pollution emission allowances that Tampa Electric or others could use, or sell to others, to emit 

additional NOx, SO2, and PM.

Virginia Electric and Power Company agreed to spend $1.2 billion by 2013 to eliminate 237,000 

tons of SO2 and NOx emissions each year from eight coal-fired electric generating plants in 

Virginia and West Virginia. 
31

A 2002 agreement calls for Gulf Power to upgrade its operation to cut NOx emission rates by 

61% at its Crist generating plant by 2007, with major reductions beginning in early 2005. The 

Crist plant is a significant source of NOx emissions in the Pensacola area.

In October 2007, American Electric Power agreed to spend $4.6 billion dollars to eliminate 

72,000 tons of NOx emissions each year by 2016 and 174,000 tons of SO2 emissions each year by 

2018 from sixteen coal-fired power plants located in Indiana, Kentucky, Ohio, Virginia and West 

Virginia.

One-hour ozone SIPs (Atlanta / Birmingham / Northern Kentucky). New SIPs have been 

submitted to the USEPA to demonstrate attainment of the one-hour ozone NAAQS. These SIPs 

require NOx reductions from specific coal fired power plants and address transportation plans in 

these cities.

NOx RACT in 8-hour Nonattainment Area SIPs. The NCDAQ‟s SIP for the 

Charlotte/Gastonia/Rock Hill nonattainment area includes Reasonable Achievable Control 

Technology (RACT) for NOx for two facilities located in the nonattainment area: Philip Morris 

USA and Norandal USA. These controls were also modeled in 2018. Additional RACT controls 

may be realized as other companies subject to RACT complete the determination, but RACT-level 

controls were assumed for just these two sources. 

Heavy Duty Diesel (2007) Engine Standard (for on-road trucks and buses). The USEPA set a PM 

emissions standard for new heavy-duty engines of 0.01 grams per brake-horsepower-hour (g/bhphr), to take full effect for diesel engines in the 2007 model year. This rule also includes standards 

for NOx and non-methane hydrocarbons (NMHC) of 0.20 g/bhp-hr and 0.14 g/ bhp-hr, 

respectively. These NOx and NMHC standards will be phased in together between 2007 and 

2010, for diesel engines. Sulfur in diesel fuel must be lowered to enable modern pollution control 

technology to be effective on these trucks and buses. The USEPA will require a 97 percent 

reduction in the sulfur content of highway diesel fuel from its current level of 500 parts per 

million (low sulfur diesel, or LSD) to 15 parts per million (ultra-low sulfur diesel, or ULSD). 

Tier 2 Tailpipe (On-road vehicles). The USEPA mobile source rules include the Tier 2 fleet 

averaging program, modeled after the California LEV II standards. Manufacturers can produce 

vehicles with emissions ranging from relatively dirty to zero emissions, but the mix of vehicles a 

manufacturer sells each year must have average NOx emissions below a specified value. Tier 2 

standards became effective in the 2005 model year. Large Spark Ignition and Recreational 

Vehicle Rule. The USEPA has adopted new standards for emissions of NOx, hydrocarbons, and 

carbon monoxide from several groups of previously unregulated nonroad engines. Included in 

these are large industrial spark-ignition engines and recreational vehicles. Nonroad sparkignition engines are those powered by gasoline, liquid propane gas, or compressed natural gas 

rated over 19 kilowatts (kW) (25 horsepower). These engines are used in commercial and 

industrial applications, including forklifts, electric generators, airport baggage transport 

vehicles, and a variety of farm and construction applications. Nonroad recreational vehicles 

include snowmobiles, off-highway motorcycles, and all-terrain-vehicles. These rules were 

initially effective in 2004 and will be fully phased-in by 2012.
32

Nonroad Diesel Rule. This rule sets standards that will reduce emissions by more than 90 

percent from nonroad diesel equipment, and reduce sulfur levels by 99 percent from current 

levels in nonroad diesel fuel starting in 2007. This step will apply to most nonroad diesel fuel in 

2010 and to fuel used in locomotives and marine vessels in 2012. 

Industrial Boiler/Process Heater MACTs. The USEPA issued final rules to substantially reduce 

emissions of toxic air pollutants from industrial, commercial and institutional boilers and process 

heaters. These rules reduce emissions of a number of toxic air pollutants, including hydrogen 

chloride, manganese, lead, arsenic and mercury by 2009. This rule also reduces emissions of SO2 

and PM in conjunction with the toxic air pollutant reductions. The applied Maximum Achievable 

Control Technology (MACT) control efficiencies were 4 percent for SO2 and 40 percent for PM10 

and PM2.5. The USEPA‟s industrial boiler MACT rules were vacated on June 8, 2007. The 

VISTAS states decided to leave these controls in the modeling since it is believed that by 2018 the 

USEPA will have re-promulgated a boiler MACT rule or states will have addressed the issue 

through state rule making.

Combustion Turbine and Reciprocating Internal Combustion Engines MACTs. The projection 

inventories do not include the NOx co-benefit effects of the MACT regulations for Gas Turbines 

or stationary Reciprocating Internal Combustion Engines, which the USEPA estimates to be 

small compared to the overall inventory.

VOC 2-, 4-, 7-, and 10-year MACT Standards. Various point source MACTs and associated 

emission reductions were implemented. Reductions occurring before 2002 were assumed to be 

accounted for in the 2002 base year inventory.

Modeling System

NC SIP Narrative, Pages 25-32:

Modeling for regional haze was performed by VISTAS for the ten southeastern states, including 

North Carolina. Chapter 5 outlines the methods and inputs used by VISTAS for the regional 

modeling. The modeling analysis is a complex technical evaluation that begins by selection of the 

modeling system. VISTAS decided to use the following modeling system:

• Meteorological Model: The Pennsylvania State University/National Center for

Atmospheric Research (PSU/NCAR) Mesoscale Meteorological Model (MM5) is a

nonhydrostatic, prognostic meteorological model routinely used for urban- and regional scale 

photochemical, fine particulate matter, and regional haze regulatory modeling studies.

• Emissions Model: The Sparse Matrix Operator Kernel Emissions (SMOKE) modeling system is 

an emissions modeling system that generates hourly gridded speciated emission inputs of mobile, 

nonroad mobile, area, point, fire and biogenic emission sources for photochemical grid models.

• Air Quality Model: The USEPA‟s Models-3/ Community Multiscale Air Quality

(CMAQ) modeling system is a „One-Atmosphere‟ photochemical grid model capable of 

addressing ozone, particulate matter (PM), visibility and acid deposition at regional scale. The 
33

photochemical model selected for this study was CMAQ version 4.5. It was modified with a 

module for Secondary Organics Aerosols (SOA) (Appendix F).

CMAQ modeling of regional haze in the VISTAS region for 2002 and 2018 was carried out on a 

grid of 12x12 km cells that covers the VISTAS states (AL, GA, FL, MS, SC, NC, TN, KY, VA, WV) 

and states adjacent to them. This grid is nested within a larger national CMAQ modeling grid of 

36x36 km grid cells that covers the continental United States, portions of Canada and Mexico, 

and portions of the Atlantic and Pacific Oceans along the east and west coasts. 

Transport of pollution from the national domain into the VISTAS modeling domain is reflected in 

hourly-varying boundary conditions around the VISTAS domain, which are derived from the 

CMAQ simulations in the 36 km national domain. The national domain incorporates emissions 

from northern Mexico and southern Canada, and therefore explicitly calculates the effects of 

these international emissions on concentrations at the boundaries of the VISTAS modeling 

domain.

Effects of emissions from more distant sources that are outside of the 36 km national domain 

were estimated using outputs from a global air pollution model. VISTAS elected to use the 

outputs of the GEOS-CHEM global air pollution model, which also contains a detailed 

representation of ozone-NOx-VOC-PM chemistry. The application and model performance 

evaluation of the GEOS-CHEM model is described in detail in Appendix G of Appendix F on 

pages 1051-1061.

The coarse 36-km horizontal grid domain was also used as the outer grid for MM5 

meteorological modeling with the CMAQ domain nested within the MM5 domain. Figure 5.4.1-1 

shows the MM5 horizontal domain as the outer most, blue grid with the CMAQ 36-km domain 

nested in the MM5 domain. Figure 5.4.1-2 shows the 12-km grid, modeling domain for the 

VISTAS region.
34

Figure 22. The MM5 horizontal domain is the outer most, blue grid, with the CMAQ 36-km 

domain nested in the MM5 domain.

Figure 23. A more detailed view of the 12-km grid over the VISTAS region
35

Modeling Episodes

The USEPA‟s 2007 modeling guidance recommends modeling an entire year or at a 

minimum several days in each quarter of a year to adequately represent the range of 

meteorological conditions that contribute to elevated levels of fine particulate matter. The year 

2002 was selected by VISTAS as the modeling year for this demonstration. Meteorological inputs 

were developed for 2002 using the meteorological model. Emission inventories were also 

developed for 2002 and processed through the emissions model. These inputs were used in the air 

quality model to predict fine particle mass and visibility. The model results for 2002 were 

compared with observed meteorological and air quality data to evaluate model performance. 

Several configurations of the meteorological and air quality model were evaluated to select a 

configuration that gave the best overall performance for the VISTAS region.

Model Performance Evaluation 

NC SIP Narrative, Pages 33-44:

A model performance evaluation of the CMAQ and MM5 models was developed for the 2002 

current year using graphical and statistical assessments. In keeping with the one-atmosphere 

objective of the CMAQ modeling platform, the air quality model performance was evaluated 

based on measured ozone, fine particles, and acid deposition from various monitoring networks 

and databases. 

The model performance evaluation methodology was fully consistent with current EPA guidance 

and science community consensus on how fine particulate/regional haze and ozone models should 

be evaluated with contemporary surface and aloft monitoring databases. Key to this evaluation 

is that the model was evaluated separately for each component of particulate matter (PM), 

including sulfate (SO4), nitrate (NO3), elemental carbon (EC), organic carbon (OC), other fine 

particulate (PM2.5) and coarse particulate (PM10), as well as important gaseous species (e.g., 

ozone, nitrogen oxides (NOx), carbon monoxide (CO), ammonia (NH3) and nitric acid (NH4)). 

The CMAQ model was evaluated using both daily averages and longer-term (e.g., monthly, 

seasonal and annual) averages for SO2, SO4, NO3, EC, OC, PM2.5, and PM10. 

Figure 24. Model Performance Goals
36

VISTAS‟s evaluation of the 2002 modeling year considered several statistical performance 

measures and displays (see Appendix F.2). VISTAS established model performance goals and 

criteria for components of fine particle mass (Table 6.1-1) based on previous model performance 

for ozone and fine particles. The USEPA‟s 2007 modeling guidance for fine particulate matter at 

the time noted that PM models might not be able to achieve the same level of performance as 

ozone models. VISTAS‟s evaluation considered several statistical performance measures and 

displays. Fractional bias and mean fractional error were selected as the most appropriate 

metrics to summarize model performance; other metrics were also calculated and are included 

for IMPROVE monitors in the full model performance evaluation. A full list of air quality model 

performance statistics is found in Appendix F.2. 

For example, in the analyses, mean fractional bias (error) was used in lieu of mean bias (error), 

to prevent low observations and model predictions from skewing the metrics. The soccer and 

bugle plots for the all of the VISTAS IMPROVE monitors are included here for summary 

purposes. The goal and criteria levels used for regional haze model performance were 30% and 

60%, respectively, for mean fractional bias and 50% and 75%, respectively, for mean fractional 

error. The soccer plots of monthly concentrations (Figures. 6.2-1 and 6.2-2) show that values for 

nitrate generally fall outside of criteria performance thresholds (red box). Sulfates and organic 

carbon generally fall within goal thresholds (green box), with a couple of months falling just 

outside the goal thresholds but well within the criteria thresholds. In these figures, each point 

represents a month. Figure 6.2-3 contains separate soccer plots for each season. The seasonal 

plots emphasize poorer nitrate performance in the summer, when observed nitrate is quite low 

and predicted nitrate is even lower. 

Figure 6.2-1: Soccer plot depicting both the mean fractional error and fractional bias for 

component concentration for all VISTAS sites.

Figure 25. Soccer Plot for all VISTAS sites

Figure 6.2-2: A zoomed view of the soccer plot depicting both the mean fractional error and 

fractional bias for component concentration for all VISTAS sites.
37

Figure 26. Soccer Plot for all VISTAS sites – zoomed view

Figure 6.2-3: Seasonal soccer plots for all VISTAS IMPROVE monitors.

Figure 27. Soccer Plot for all VISTAS sites – Seasonal

The model performance for North Carolina‟s Class I areas shows varied, though acceptable 

agreement when using a stacked bar chart of observed fine particulate matter composition and 

modeled fine particulate matter composition on the 20% Worst and Best days. This allows a side 
38

by side comparison of the each day‟s observed and modeled compositional and total light 

extinction. See pages 39-44.

Model performance for 2002 was deemed adequate and acceptable for use in modeling future 

predictions for ozone, PM2.5 and regional haze. The one-atmosphere modeling performed by the 

VISTAS contractors is representative of conditions in the southeastern states and is applicable for 

use in analyzing future strategies for regional haze for the Class I areas. The 2002 current and 

2018 future year emissions were processed through the SMOKE emissions model. The air quality 

modeling results are used in a relative manner to determine a relative reduction in future 

visibility impairment.

More detailed discussions of the modeling protocol, quality assurance report, procedures, models 

and data used in the regional haze analysis can be found in Appendices C, E, F, and G.

There are significant control programs being implemented between the baseline period and 2018. 

Emission reductions from these control programs are projected to achieve substantial visibility 

improvement by 2018 in the North Carolina Class I areas. These programs are described in more 

detail below.

Sources and Pollutants relied on for LTS (NC SIP Narrative, Pages 61-77) 

An important step toward identifying further reasonable progress measures is to identify the key 

pollutants contributing to visibility impairment at each Class I area. To understand the relative 

benefit of further reducing emissions from different pollutants, source sectors, and geographic 

areas, VISTAS engaged the Georgia Institute of Technology to perform emission sensitivity model 

runs using CMAQ. Emissions in 2009 were reduced by 30 percent for each pollutant sensitivity 

run. The pollutant contributions that were evaluated were: 

SO2 from EGU sources in each VISTAS state, other RPOs in the VISTAS 12 km grid, and 

Boundary Conditions from outside the 12 km domain. 

SO2 from non-EGU point sources in each VISTAS state, other RPOs, and Boundary 

Conditions

NOx from ground level sources (on-road plus off-road plus area) in each VISTAS state 

and other RPOs. In the VISTAS states, these reductions were only applied to specific 

counties that were of concern for 8-hour ozone nonattainment.

NOx from point (EGU plus non-EGU) sources in each VISTAS state and other RPOs 

NH3 from all sources in VISTAS and other RPOs

Volatile Organic Compounds from anthropogenic and biogenic sources in the 12 km 

modeling domain

Primary Carbon from all ground level sources in each VISTAS state and other RPOs. In 

the VISTAS states, these reductions were only applied to specific counties that were of 

concern for PM2.5 nonattainment.

Primary Carbon from all point sources in each VISTAS state and other RPOs 

Primary Carbon from all fires in each VISTAS state and other RPOs
39

Results are shown in Figures 7.4-1 through 7.4-4 below for the average of the 20% worst 

visibility days for each of four North Carolina Class I areas. Responses for 20% worst days were 

calculated by averaging the responses of the 20% worst days that were modeled in the two 

episodes. For the North Carolina sites, responses on five to six of the 20% worst visibility days 

were included in these graphics.

Figure 28. -Figure 7.4-1. CMAQ projections of visibility responses on 20% worst days at 

Great Smoky Mountains to 30 % reductions from a 2009 inventory for visibility-reducing 

pollutants in different source categories and geographic areas.
40

Figure 29. - Figure 7.4-2. CMAQ projections of visibility responses on 20% worst days at 

Shining Rock to 30% reductions from a 2009 inventory for visibility-reducing pollutants in 

different source categories and geographic areas.
41

Figure 30. Figure 7.4-3. CMAQ projections of visibility responses on 20% worst days at 

Linville Gorge to 30% reductions from a 2009 inventory for visibility-reducing pollutants in 

different source categories and geographic areas.
42

Figure 31. - Figure 7.4-4. CMAQ projections of visibility responses on 20% worst days at 

Swanquarter to 30% reductions from a 2009 inventory for visibility-reducing pollutants in 

different source categories and geographic areas.

As Figures 7.4-1 through 7.4-4 illustrate, the greatest visibility benefits on the 20% worst days 

for the North Carolina Class I areas are projected to result from further reducing SO2 from 

EGUs. At the mountain Class I areas, benefits are projected from SO2 reductions from EGUs in 

several VISTAS states including Alabama, Georgia, Kentucky, North Carolina, South Carolina, 

Tennessee, Virginia, and West Virginia. Contributions from other RPOs and from the boundary 

conditions are comparatively small and the greatest benefits would likely be from further EGU 

reductions within the VISTAS states. In contrast, at Swanquarter, reductions from EGUs in North 

Carolina and South Carolina would have the greatest benefits and the contributions from other 

VISTAS states are comparatively small. MANE-VU states also contribute, as do SO2 and SO4 

coming into the modeling domain from outside the boundary (e.g. Atlantic Ocean).

Additional, smaller benefits are projected from additional SO2 emission reductions from 

nonutility, industrial point sources. The pattern of relative SO2 contributions from non-EGUs 

among the various VISTAS states is similar to the pattern of relative SO2 contributions from 

EGUs.

Because ammonium nitrate is a small contributor to PM2.5 mass and visibility impairment on the 

20% worst days at the mountain Class I areas, the benefits of reducing NOx and NH3 emissions 

at these sites are small. Some of the 20% worst days at Swanquarter, and other coastal sites in 

the VISTAS states, occur in the winter when ammonium nitrate has a somewhat larger 

contribution to visibility impairment. As shown in Figure 7.4-4, reducing ammonia emissions 

would be more beneficial for reducing ammonium nitrate contributions to visibility impairment in 

wintertime than further reducing nitrogen oxide emissions from either ground or point sources.

For Swanquarter, the numerous hog farms in eastern North Carolina are the likely primary 

emission sources for ammonia. VOC emissions do contribute to visibility impairment, but as 

shown in the charts above, this contribution is from biogenic sources such as vegetative 

emissions. Controlling anthropogenic sources of VOC emissions has little if any visibility benefit 

at the Class I areas. Reducing primary carbon from point sources, ground level sources or fires 

are projected to have small to no visibility benefit. This is consistent with the monitoring data that 

shows that most of measured organic carbon is secondary in origin and primary carbon is only a 

small fraction of the total measured carbon (Appendix B). The sensitivities were not useful in 

analyzing reductions carbon from fires because there was little fire activity at these sites on the 

days modeled. However, looking at the 2000 – 2004 reconstructed extinction, using the new 

IMPROVE equation, for the 20% worst days it is clear that the number of days where fires played 

a role in visibility impairment was approximately 2% to 3% of the days in the entire baseline 

period (see Appendix B). Therefore, although the emission reduction sensitivities did not include 

many days influenced by fires, this should not impact the ultimate results of the sensitivities. 

Note that these results from the emission sensitivity runs are consistent with the conclusions 

drawn from the 2000-2004 baseline monitoring data (see Section 2.4 of the SIP NArrative). The 

results indicate that sulfate is the dominant contributor to visibility impairment on the 20% worst 
43

days at all sites, and that ammonium nitrate may be important for sites where the 20% worst days 

occur in the winter. The NCDAQ concluded that reducing SO2 emissions from EGU and nonEGU point sources in the VISTAS states would have the greatest visibility benefits for the North 

Carolina Class I areas. Contributions from the Midwest RPO and MANE-VU are greater at the 

Class I areas bordering these RPOs. Contributions from outside the VISTAS 12-km modeling 

domain are more important for the coastal Class I areas. These results are consistent with the 

CMAQ model results indicating that contributions from international emissions to visibility 

impairment at VISTAS Class I areas are greater closer to the boundaries of the modeling domain 

(see Appendix H for further discussions).

EPA Note: More detailed discussions of the modeling protocol, quality assurance report, 

procedures, models and data used in the regional haze analysis can be found in Appendices C, E, 

F and G. The archival and acquisition of data and modeling input and output files are discussed 

in Appendix I. 

EPA Findings: In accordance with 40 CFR 51.308(d)(3), EPA proposes to find that the State of 

North Carolina provided the appropriate supporting documentation for all required analyses used 

to determine the State’s LTS. The technical analyses and modeling used to develop the glidepath 

and to support the LTS are consistent with EPA’s RHR and interim and final EPA Modeling 

Guidance. EPA proposes to accept the VISTAS technical modeling to support the LTS and to 

determine visibility improvement for the uniform rate of progress because the modeling system 

was chosen and simulated according to EPA Modeling Guidance. EPA proposes to agree with 

the VISTAS model performance procedures and results, and that the CMAQ is an appropriate

tool for the regional haze assessments for the North Carolina LTS and regional haze SIP. 

CAIR is also an element of North Carolina’s LTS. CAIR rule revisions were approved into the 

North Carolina SIP in 2007 and 2009. See 72 FR 56914 (October 5, 2007); 74 FR 62496 

(November 30, 2009). North Carolina opted to rely on CAIR emission reduction requirements to 

satisfy the BART requirements for SO2 and NOX from EGUs. See 40 CFR 51.308(e)(4). 

Therefore, North Carolina only required its BART-eligible EGUs to evaluate PM emissions for 

determining whether they are subject to BART, and if applicable, for performing a BART control 

assessment. Additionally, North Carolina concluded that no additional controls beyond CAIR are 

reasonable for reasonable progress for SO2 for its EGUs for this first implementation period. 

Prior to the remand of CAIR, EPA believed the State’s reliance on CAIR for specific BART and 

reasonable progress provisions affecting its EGUs was adequate. The regional haze provisions 

specify that a state may not adopt a RPG that represents less visibility improvement than is 

expected to result from other CAA requirements during the planning period (40 CFR 

51.308(d)(1)(vi)). As such, North Carolina took into account emissions reductions anticipated 

from the CAIR in determining its 2018 RPGs. 

The RHR allows states to implement an alternative program in lieu of BART so long as the 

alternative program can be demonstrated to achieve greater reasonable progress toward the 

national visibility goal than would BART. Under regulations issued in 2005 revising the regional 

haze program, EPA made just such a demonstration for CAIR. See 70 FR 39104 (July 6, 2005). 

EPA’s regulations provide that states participating in the CAIR cap-and trade program under 40 
44

CFR part 96 pursuant to an EPA-approved CAIR SIP or which remain subject to the CAIR 

Federal Implementation Plan in 40 CFR part 97 need not require affected BART-eligible 

electrical generating (EGUs) to install, operate, and maintain BART for emissions of SO2 and 

NOx. See 40 CFR 51.308(e)(4). Because CAIR did not address direct emissions of PM, states 

were still required to conduct a BART analysis for PM emissions from EGUs subject to BART 

for that pollutant. Challenges to CAIR, however, resulted in the remand of the rule to EPA. See 

North Carolina v. EPA, 550F.3d 1175 (D.C. Cir. 2008). 

EPA issued a new rule in 2011 to address the interstate transport of NOx and SO2 in the eastern 

United States. See 76 FR 48208 (August 8, 2011) (“the Transport Rule,” also known as the 

Cross-State Air Pollution Rule). On December 30, 2011, EPA proposed to find that the trading 

programs in the Transport Rule would achieve greater reasonable progress towards the national 

goal than would BART in the states in which the Transport Rule applies. See 76 FR 82219. 

Based on this proposed finding, EPA also proposed to revise the RHR to allow states to substitute 

participation in the trading programs under the Transport Rule for source-specific BART. EPA 

has not yet taken final action on that rule. Also on December 30, 2011, the D.C. Circuit issued an 

order addressing the status of the Transport Rule and CAIR in response to motions filed by 

numerous parties seeking a stay of the Transport Rule pending judicial review. In that order, the 

D.C. Circuit stayed the Transport Rule pending the court’s resolutions of the petitions for review 

of that rule in EME Homer Generation, L.P. v. EPA (No. 11-1302 and consolidated cases). The 

court also indicated that EPA is expected to continue to administer CAIR in the interim until the 

court rules on the petitions for review of the Transport Rule. 

In a separate action, EPA has proposed a limited disapproval of the North Carolina regional haze 

SIP because of deficiencies in the State’s regional haze SIP submittal arising from the remand by 

the D.C. Circuit to EPA of CAIR. See 76 FR 82219. Consequently, EPA is not taking action in 

this proposed rulemaking to address the State’s reliance on CAIR to meet certain regional haze 

requirements.

In addition, on July 30, 2007, the D.C. Circuit mandated the vacatur and remand of the Industrial 

Boiler MACT Rule. Notwithstanding the vacatur of this rule, the VISTAS states, including North 

Carolina, decided to leave these controls in the modeling for their regional haze SIPs since it is 

believed that by 2018, EPA will have re-promulgated an industrial boiler MACT rule or the states 

will have addressed the issue through state-level case-by-case MACT reviews in accordance with 

section 112(j) of the CAA. 

EPA proposes to find that this approach acceptable for the following reasons. Effective July 30, 

2007, the D.C. Circuit mandated the vacatur and remand of the Industrial Boiler MACT Rule.1 

This MACT was vacated since it was directly affected by the vacatur and remand of the 

Commercial and Industrial Solid Waste Incinerator Definition Rule. EPA proposed a new 

Industrial Boiler MACT rule to address the vacatur on June 4, 2010, (75 FR 32006) and issued a 

final rule on March 21, 2011 (76 FR 15608). The VISTAS modeling included emissions 

reductions from the vacated Industrial Boiler MACT rule, and North Carolina did not redo its 

modeling analysis when the rule was re-issued. Even though North Carolina’s modeling is based 

on the vacated Industrial Boiler MACT limits, the State’s modeling conclusions are unlikely to be 

 

1

See NRDC v. EPA, 489 F.3d 1250 (D.C. Cir. 2007).
45

affected because the expected reductions due to the vacated rule were relatively small compared 

to the State’s total SO2, PM2.5, and coarse particulate matter (PM10) emissions in 2018 (i.e., 0.1 to 

0.4 percent, depending on the pollutant, of the projected 2018 SO2, PM2.5, and PM10 inventory). 

Thus, EPA does not expect that differences between the vacated and final Industrial Boiler 

MACT emissions limits would affect the adequacy of the existing North Carolina regional haze 

SIP. If there is a need to address discrepancies between projected emissions reductions from the 

vacated Industrial Boiler MACT and the Industrial Boiler MACT issued March 21, 2011 (76 FR 

15608), EPA expects North Carolina to do so in the State’s five-year progress report.

References used in the EPA review: 

1. Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air 

Quality Goals for Ozone, PM2.5, and Regional Haze, April 2007, EPA-454/B-07-002.

http://www.epa.gov/scram001/guidance/guide/final-03-pm-rh-guidance.pdf. 

2. “(Draft) Guidance for Demonstrating Attainment of Air Quality Goals for PM2.5 and Regional 

Haze”, EPA, (2001), http://www.epa.gov/ttn/scram/guidance_sip.htm. 

3. 2002 Base Year Emission Inventory SIP Planning: 8-hr Ozone, PM2.5 and Regional Haze, 

EPA memorandum from Lydia Wegman to Peter Tsirigotis, November 18, 2002.

4. July 15, 2008, e-mail from Laura Boothe, NCDAQ, to Brenda Johnson, EPA. Subject: Fwd: 

Re: question about MACT reductions.

5. CAA §§112(j)(2), (3), (5), and (6).

6. CAA §505 specifies procedures for notification to the Administrator and affected states.
46

III. Evaluation of Regional Haze Submittal

C. Long-Term Strategy 

C.2. Identification of Sources and Factors to be Considered: (40 CFR 51.308(d)(3)(iv-v)) 

The State must identify all anthropogenic sources of visibility impairment considered by the State 

in developing its long-term strategy. The State should consider major and minor stationary 

sources, mobile sources, and area sources. The State must consider, at a minimum, the following 

factors in developing its long-term strategy: (A) emission reductions due to ongoing air pollution 

control programs, including measures to address reasonably attributable visibility impairment; (B) 

measures to mitigate the impacts of construction activities; (C) emissions limitations and 

schedules for compliance to achieve the reasonable progress goal; (D) source retirement and 

replacement schedules; (E) smoke management techniques for agricultural and forestry 

management purposes including plans as currently exist within the State for these purposes; 

measures to mitigate the impacts of construction activities; (F) enforceability of emission 

limitations and control measures; and the (G) anticipated net effect on visibility due to projected 

changes in point, area, and mobile source emissions over the period. 

State Regional Haze Submittal

NC SIP Narrative, Pages 85-88:

The following summarizes the process for determining reasonable progress for North Carolina 

sources. A detailed discussion of the reasonable progress assessments for all units with a 

contribution of greater than one percent to visibility impairment at any Class I area in North 

Carolina or in neighboring states is in Appendix H.

Step 1: Determine pollutants of concern.

VISTAS evaluated the species contribution on the 20% worst visibility days in the baseline period 

and concluded that sulfate accounted for greater than 70% of the visibility impairing pollution. 

The VISTAS States concluded that controlling SO2 emissions was the appropriate step in 

addressing the reasonable progress assessment for 2018. 

Step 2: Determine which source sectors should be evaluated for reasonable progress.

Since the pollutant of primary concern was determined to be SO2, the emissions inventory was 

assessed to determine the source categories that contribute the most SO2 emissions. Point source 

emissions in 2018 are projected to represent greater than 95% of the total SO2 emissions 

inventory, the VISTAS States concluded that the focus should be on electric generating unit 

(EGU) and non-EGU point sources of SO2 emissions.

Step 3: Determine if the Clean Air Interstate Rule is sufficient for reasonable progress for subject 

EGUs. The NCDAQ evaluated the amount of SO2 reduction from the EGU sector resulting from 

the implementation of the North Carolina Clean Smokestacks Act (CSA) and CAIR. The EGUs in 

North Carolina are expected to reduce their SO2 emissions by greater than 80% between 2002 

and 2018. Much of that reduction is the result of CSA requirements which are directly 

enforceable and which must be satisfied by actual emission reductions as opposed to buying 

banked Title IV allowances to meet the system-wide emissions caps. The NCDAQ intends to reevaluate the IPM predictions of SO2 reductions for CAIR at the time of its next periodic report in 
47

2012 to ensure that the reductions are in fact taking place where they were predicted. Based on 

the controls required by CSA, and predicted by IPM under CAIR, the NCDAQ has concluded that 

at this time these existing regulatory programs constitute reasonable control measures for North 

Carolina EGUs during this first assessment period (between baseline and 2018).

Step 4: Determine which emission units would be evaluated based on impact. The NCDAQ 

calculated the fractional contribution from all emission units within the SO2 Area of Influence for 

a given Class I area and identified those emission units with a contribution of one percent or 

more to the visibility impairment at that Class I area. A full description of this process and a list 

of sources considered in the reasonable progress evaluation can be found in Appendix H.

The following table shows, in tabular form, the relative contributions of point source SO2 

emissions from nearby states to North Carolina‟s Class I area. These percentages were estimated 

by multiplying the maximum residence time to the emissions over distance. 

Figure 32. 2018 Point Source SO2 Contribution to NC Class I Areas by State

Spreadsheets were developed for each Class I area source with Q/d > 5 or Q/d2 > 0.03, 

indicating the plant name, industry description, emissions projections for 2018, current control 

efficiency (CE%), distance from Class I area, Q/d, Q/d2, RT average, RT maximum, Q/d*RT, the 

fraction a single source contributes to the total Q/d*RT for a Class I area. CE% is important 

because it gives a sense of which facilities are already controlled by what percent and which may 

be controlled further. Tables 5-2 through 5-6, show the analysis for the North Carolina Class I 

areas for sources that met the above criteria. The full spreadsheets containing all VISTAS Class I 

area results can be found in Attachment H-1b.
48

Figure 33. Linville Gorge - Point Source SO2 Contribution to NC Class I Areas 

Figure 34. Shining Rock - Point Source SO2 Contribution to NC Class I Areas 
49

Figure 35. Swanquarter - Point Source SO2 Contribution to NC Class I Areas 

Figure 36. Great Smokies - Point Source SO2 Contribution to NC Class I Areas 
50

Figure 37. Joyce Kilmer-Slickrock - Point Source SO2 Contribution to NC Class I Areas 

Step 5: Evaluate the four factors.

Each emission unit identified in Step 4 above was evaluated using the statutory and regulatory 

factors of 1) cost of compliance, 2) time necessary for compliance, 3) the energy and non-air 

quality environmental impacts of compliance, and 4) the remaining useful life of the emissions 

unit. If any control measure for an emission unit was found reasonable after assessing the four 

factors, modeling would be performed to determine if the controls would result in a visibility 

improvement at any Class I area.

For the limited purpose of evaluating the cost for the reasonable progress assessment in this first 

regional haze SIP, the NCDAQ believes it is not equitable to require non-EGUs to bear a greater 

economic burden than EGUs for a given control strategy. The NCDAQ used the capital and 

operating costs provide by Duke Energy and Progress Energy for the CSA compliance plans to 

establish a cost/ton of SO2 removed threshold. During the current reasonable progress 

assessment, no units in North Carolina were identified for additional control since no measures 

were found to be below the cost threshold. 

NC SIP Narrative, Pages 91-93:

Section 308(d)(3)(v) of the regional haze rule lists several factors that must be addressed in each 

SIP. These factors include the role of fire at Class I areas and status of state planning for smoke 

management, the role of dust and fine soil at Class I areas and status of state plans to mitigate 
51

emissions from construction activities and the role of NH3 and potential benefits if emissions 

from agricultural sources were mitigated.

As discussed in Section 2.4 and demonstrated in Figures 2.4-1 and 2.4-2, elemental carbon 

(sources include agricultural burning, prescribed wildland fires, and wildfires) is a relatively 

minor contributor to visibility impairment at the Class I areas in North Carolina. However, the 

NCDAQ is currently working with the North Carolina Division of Forest Resources to develop a 

smoke management program that utilizes basic smoke management practices and addresses the 

issues laid out in the USEPA‟s 1998 Interim Air Quality Policy on Wildland and Prescribed 

Fires. Additionally, the NCDAQ is working with the North Carolina Department of Agriculture to 

develop a Memorandum of Understanding regarding agricultural burning. The NCDAQ 

anticipates that the resulting smoke management program and Memorandum of Understanding 

should be sufficient to satisfy the directive in 40 CFR 51.308(d)(3)(v)(E).

Also as discussed in Section 2.4 and demonstrated in Figures 2.4-1 and 2.4-2, fine soils are a 

relatively minor contributor to visibility impairment at the Class I areas in North Carolina. 

Nevertheless, in regard to construction activities, the NCDOT Division of Highways has issued 

regulations addressing control of erosion, siltation, and pollution from construction activities.

Section 107-13(E) of the Division of Highways General Contract Specifications, Division 1 

General Requirements, reads as follows:

(E) Dust Control

The Contractor shall control dust throughout the life of the project within the project area 

and at all other areas affected by the construction of the project, including, but not 

specifically limited to, unpaved secondary roads, haul roads, access roads, disposal sites, 

borrow and material sources, and production sites. Dust control shall not be considered 

effective where the amount of dust creates a potential or actual unsafe condition, public 

nuisance, or condition endangering the value, utility, or appearance of any property. The 

Contractor will not be directed compensated for any dust control measures necessary, as 

this work will be considered incidental to the work covered by the various contract items.

In addition, the NCDAQ has recently promulgated a new rule, effective on September 1, 2007, 

intended to control particulates from fugitive dust emission sources generated within plant 

boundaries from activities such as “unloading and loading areas, process areas, stockpiles, stock 

pile working, plant parking lots, and plant roads (including access roads and haul roads).”

Note that benefits from neither the new rule nor the NCDOT dust ordinance have been included 

in the VISTAS modeling runs. Copies of the dust ordinance and the NCDAQ rule are attached to 

Appendix H.

In regard to agricultural ammonia, the NCDAQ, as a continuation of the CSA, initiated the 

Climate Action Planning Advisory Group (CAPAG) to develop widespread and specific options 

for the reduction of greenhouse gas emissions in North Carolina. The CAPAG is comprised of 

leaders from agricultural, industrial, local and state governmental and environmental sectors in 

North Carolina. This collaborative effort developed mitigation options through a consensus 

process to simultaneously address the goal of reducing green house gas emissions and improve 
52

the quality of life in North Carolina. Agriculture and waste in North Carolina is one of the major 

areas being developed to reduce greenhouse gases. Since North Carolina is second in the nation 

in production of pork, one of the options being developed promotes increased use of the energy 

content of hog and cattle waste through the expansion of biodigesters.

To accomplish the expanded utilization of methane (a greenhouse gas) from hog/cattle waste for 

energy, the report supports expanded research, regulatory actions, and grant guarantees as key 

implementation tools. Inherent to the success are improved waste management practices. With 

increased support and improved management a co-benefit will be the reduction of ammonia 

emissions from animal waste. As less ammonia will be applied to soils, lower direct emissions of 

ammonia will occur and lower emissions of nitrous oxide (N2O), a potent greenhouse gas, from 

soils will occur. The exact benefits from the reduction in ammonia emissions have not been 

quantified.

In addition, the North Carolina Legislature approved a bill on July 26, 2007 that permanently 

bans new hog lagoons and orders state regulators to set environmental standards for new 

systems. The new legislation creates a phase-out of waste lagoons used by hog farmers, replacing 

them with more environmentally friendly systems paid for in part by taxpayer-funded grants. The 

bill is included as an attachment to Appendix H.

VISTAS is working on a modeling run that will include the cumulative benefits from the emission 

controls discussed in Section 7.2.1, any controls resulting from BART determinations within the 

other VISTAS states and any controls resulting from the other states within VISTAS to address 

reasonable control measures. These modeling results were not completed in time to be included 

with this Regional Haze SIP. Additionally, not all states within VISTAS have completed their 

reasonable control measures analysis and the modeling does not include controls resulting from 

BART determinations or reasonable control measures from states located outside the VISTAS 

region. Since it may take a significant amount of time to have a modeling run completed that 

incorporates all of these measures, the NCDAQ has decided that it will incorporate these types of 

results in the first periodic review in 2012.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision. Prior to the remand of CAIR, EPA believed the State’s reliance on CAIR for specific 

BART and reasonable progress provisions affecting its EGUs was adequate. The regional haze 

provisions specify that a state may not adopt a RPG that represents less visibility improvement 

than is expected to result from other CAA requirements during the planning period (40 CFR 

51.308(d)(1)(vi)). As such, North Carolina took into account emissions reductions anticipated 

from the CAIR in determining its 2018 RPGs. 

In a separate action proposing limited disapproval of the regional haze SIPs of a number of states, 

EPA noted that these states relied on the trading programs of CAIR to satisfy the BART 

requirement and the requirement for a LTS sufficient to achieve the state-adopted RPGs. See 76 

FR 82219 (December 30, 2011). In that action, EPA proposed a limited disapproval of North 

Carolina’s regional haze SIP submittal insofar as the SIP relied on CAIR. For that reason, EPA is 

not taking action on that aspect of North Carolina’s regional haze SIP in this action. 
53

III. Evaluation of Regional Haze Submittal

C. Long-Term Strategy 

C.3. Source or Source Category Specific Analyses for Reasonable Progress: (40 CFR 

51.308(d)(1)(i)(A)

For the significant sources and source categories located within the State and determined to be 

significantly impacting a mandatory Class I Federal area, the State must document that it 

considered the costs of compliance, the time necessary for compliance, the energy and non-air 

quality environmental impacts of compliance, the remaining useful life of any potentially affected 

sources, and how these factors were taken into consideration in establishing the reasonable 

progress goal.

State Regional Haze Submittal

NC SIP Narrative, Pages 84-85:

The regional haze rule requires that states consider the following factors and demonstrate how

these factors were taken into consideration in selecting the reasonable progress goal:

• the costs of compliance

• the time necessary for compliance

• the energy and non-air quality environmental impacts of compliance, and

• the remaining useful life of any potentially affected sources.

Cost of Compliance:

As defined in Section 7.6.5, coal-fired electric utilities and coal-fired industrial boilers were the

largest source categories contributing to SO2 in 2018 in the Areas of Influence defined for the

North Carolina Class I areas. Industrial boilers using oil and commercial and institutional 

boilers using coal or oil had small contributions to SO2 in 2018.

Sulfur dioxide emissions from utility, industrial, commercial, or institutional boilers can be

controlled either by switching the fuel source to a lower sulfur fuel content or by installing postcombustion controls. Costs vary by fuel source; boiler type and boiler size and require source

specific analyses for accuracy. Bituminous coal is commonly burned in boilers in the eastern US. 

Switching to another bituminous coal with lower sulfur content or blending bituminous coals can 

reduce SO2 emissions with least impact to boiler performance. While sub-bituminous coal has 

lower sulfur content than bituminous coal, it also has lower heat content and so more coal has to 

be burned to generate the same energy output. For boilers that are designed for bituminous coal, 

only a small fraction of the fuel can be switched to low sulfur sub-bituminous coal without 

adversely affecting boiler operations. Boiler modifications to accommodate low sulfur subbituminous coal may not be cost-effective. Contract initiation and termination costs, differential 

fuel prices and heat contents, transportation costs, and modification to boiler operations, fuel 

handling and waste handling systems will have to be considered specific to each source.

Flue-gas desulfurization is the common post-combustion control for coal-fired boilers. Flue gas

is passed through an absorbent for sulfur dioxide (generally limestone or lime) in a wet scrubber, 

dry scrubber, or spray dryer. A calcium sulfate by-product is produced that may be further 

processed to produce gypsum as a commercial byproduct. Costs of flue-gas desulphurization

include initial capital costs and ongoing operational and maintenance costs for the absorber 
54

tower, sorbent handling, and waste product handling facilities. Costs per ton of SO2 removed 

vary with boiler size, type, and available space for retrofit control devices. For oil-fired boilers, 

lower sulfur oil may be an option. Costs need to consider differential fuel prices and heat content, 

boiler modifications, fuel handling costs, and maintenance costs. Conceptually, post-combustion 

controls can be used for oil boilers, but there is little precedence for such installations.

Time Necessary for Compliance:

For fuel switching, the time necessary to terminate existing fuel contracts and initiate new

contracts needs to be considered. Generally two to three years may be required. Installation of

post-combustion controls will require 3 or more years depending on market availability of labor

and materials and utility system-wide priorities. Time necessary for compliance will need to be

refined for specific sources.

Energy and Non-Air Environmental Impacts:

Switching to lower sulfur fuel or installing post-combustion controls may reduce boiler heat rate

and energy output. Scrubbers and spray dryers will require additional safeguards for fuel

handling and waste handling systems to avoid additional non-air environmental impacts such as

increased effluents in waste water discharges and storm water runoff. These factors will need to

be considered specific to individual sources. Carbon dioxide is emitted as a by-product of flue

gas desulfurization, therefore impacts of increased carbon emissions will need to be considered,

particularly if carbon emissions are limited in the future under climate change mitigation

strategies.

Remaining Useful Life:

The useful remaining life is specific to the unit for which controls are considered.

NC SIP Narrative, Pages 88-91:

Results of four-factor analysis:

The following is a brief summary of the four-factor analysis. More detail is included in Appendix 

H. The NCDAQ used the cost of compliance as a screening tool to determine the universe of 

sources to perform the full four-factor evaluation. Therefore, the summary is focused on the cost 

of control. The dollar per ton of SO2 removed that the NCDAQ used to determine if the cost was 

reasonable was based on the facility-by-facility and system wide EGU costs for implementing 

CSA and are included as Attachment 2 to Appendix H. The facility-by-facility costs ranged from 

912 to 1,922 dollars per ton of SO2 removed, and the average costs per system ranged from 

1,231 to 1,375 dollars per ton of SO2 removed. The CSA controls will reduce SO2emissions at 

North Carolina EGUs by more than 80 percent between 2002 and 2018.

For non-EGUs, the NCDAQ found that emissions from the following facilities contributed one 

percent or more to visibility impairment in a Class I area, and therefore focused the reasonable 

progress assessments on specific units at these facilities:

Blue Ridge Paper Products

PCS Phosphate

Weyerhaeuser Plymouth
55

Weyerhaeuser New Bern

Congentrix Kenansville

Additionally, two units at Ecusta Business Development Center contributed more than one 

percent to visibility impairment at Shining Rock Wilderness Area. However, this facility has since 

closed and therefore was not evaluated for reasonable progress.

The NCDAQ also looked at what sources in North Carolina may be impacting Class I areas 

located outside of the State, as well as what sources located outside of North Carolina may be 

impacting the North Carolina Class I areas. Letters were sent to the states (see Appendix J) 

identifying which sources in North Carolina may impact their Class I areas and what the 

NCDAQ had deemed as reasonable control measures. Additionally, the letters requested 

information on what each state had deemed as reasonable control measures for their sources 

impacting North Carolina‟s Class I areas.

The only North Carolina source that was identified, outside of facilities listed above, was the 

Duke Power Dan River facility, which may impact James River Face Wilderness in Virginia. 

Since this facility is subject to CAIR, the NCDAQ had deemed no additional controls would be 

required.

Blue Ridge Paper Products

Some of the units at Blue Ridge Paper Products were subject to BART. These units were

analyzed for BART and are addressed in Appendix L. Since the BART a determination takes into 

consideration many of the same factors as for reasonable progress, the BART subject units were 

not re-evaluated in the reasonable progress review. The NCDAQ evaluated switching to lower 

sulfur content coals. Currently, the company is using 0.75% sulfur coal in one boiler regulated 

by NSPS. The NCDAQ did cost calculations for the following scenario: if 0.75 percent sulfur 

content coal was required across the mill for the boilers that currently use about one percent 

sulfur coal. This measure could result in 1400 tons SO2 per year reduced. Based on information 

from the company, the lower sulfur coal is $75-90 per ton and the other coal (one percent sulfur) 

on site is $65 per ton. The cost is $10-25 per ton difference. The company burned 277,214 tons of 

one percent sulfur coal in 2005; switching to lower sulfur coal (0.75%) would cost ~ $2,772,140 -

$6,930,350 extra per year. If 1400 tons of SO2 were reduced, costs would be in the range of 

$1980 - $4950 per ton, with an average cost of $3,465per ton.

Add-on control technology for these units cost in the range of $12,055 to $100,961 per ton of SO2 

removed. The NCDAQ concludes that there are no cost-effective controls available for these units 

at this time within the cost threshold established for this reasonable progress assessment. 

Although the NCDAQ has concluded that for this reasonable progress period there are no costeffective controls, the agency acknowledges that the emissions from Blue Ridge Paper Products 

do have impacts on the Class I areas located in the mountains. The NCDAQ has notified the 

company that although additional controls are not being required this planning period, futureplanning periods may require controls to be installed. The NCDAQ is committed to work with this 

company over the next review period and to encourage the company to modernize some of its 

processes with more efficient, less polluting equipment.

PCS Phosphate
56

Some of the units at PCS Phosphate were subject to BART. These units were analyzed for

BART and are addressed in Appendix L. Since the BART determination takes into consideration 

many of the same factors as for reasonable progress, the BART subject units were not reevaluated in the reasonable progress review. No control options were listed in the VISTAS‟s 

control cost spreadsheet for any of the four units at this facility. The two PCS Phosphate units not 

subject to BART currently utilize dual absorption systems with a vanadium catalyst. Other 

technologies reviewed included sodium bisulfite scrubbing, molecular sieve, ammonia scrubbing, 

and dual absorption process with cesium-promoted catalyst. The first 3 options were rejected 

because they have not been commercially demonstrated to reliably meet current NSPS and state 

permit limits. The fourth was found to cost $3,433/ton to $3,457/ton SO2 reduced based on a 

reduction of sulfur emissions from 3.8 to 3.5 lb SO2/ton sulfuric acid. Therefore, the NCDAQ 

concludes that there are no cost-effective controls available for these units at this time within the 

cost threshold established for this reasonable progress assessment. The NCDAQ has notified the 

company that although additional controls are not being required this planning period, future 

planning periods may require controls to be installed. In addition, PCS Phosphate has submitted 

a Prevention of Significant Deterioration application to the NCDAQ. The company plans to shut 

down the two sulfuric acid plants subject to BART and build one new plant. 

Weyerhaeuser Plymouth

Weyerhauser Plymouth contains two boilers burning a combination of fuels. There were no 

controls suggested for the Boiler 1 or 2 in the VISTAS Control Cost Spreadsheet. For the Riley 

Boiler, the control suggested by VISTAS Control Cost Spreadsheet is an FGD at a cost of 

$20,460 per ton of SO2 removed. Therefore, the NCDAQ concludes that there are no cost 

effective controls available for these units at this time within the cost threshold established for 

this reasonable progress assessment.

Weyerhaeuser New Bern

Weyerhaeuser New Bern contains one residual oil-fired boiler. The control suggested by

VISTAS Control Cost Spreadsheet is an FGD at a cost of $17,317 per ton of SO2 removed. 

Therefore, the NCDAQ concludes that there are no cost-effective controls available for these 

units at this time within the cost threshold established for this reasonable progress assessment.

Cogentrix Kenansville

Congentrix Kenansville is currently burning unadulterated wood (pure wood with up to 5% 

impurities). The company retains coal as a permitted fuel on the permit, with no immediate plans 

to use it. They are currently burning wood and their new business plan is to continue just burning 

wood as part of the "green power" movement here in North Carolina. The 2005 actual SO2 

emissions for this unit were 23.25 tons, whereas the projected 2018 SO2 emissions were 1,833.8 

tons based on using coal. The NCDAQ is sending the company a letter indicating that they are 

currently on the list of sources contributing greater than one percent contribution to visibility 

impairment at Swanquarter Wildlife Refuge based on the estimated emissions from burning coal. 

The letter will suggest that they change their permit to remove coal as a possible fuel source for 

this unit.

Summary:
57

During the current reasonable progress assessment no units in North Carolina were identified for 

additional control since no measures were found to be below the cost threshold discussed in Step 

5. In addition to costs, the statutory factors include time necessary for compliance, remaining 

useful life of the facility, and energy and non-air environmental impacts of the control 

installation. However, since no cost effective control measures were identified for the specific 

sources with contributions to North Carolina or neighboring States‟ Class I areas, the NCDAQ 

did not invest in an exhaustive review of the remaining three factors beyond that described in 

section 6.4 for control options for major SO2 source sectors. 

Neither the time necessary for compliance nor the energy and non-air quality environmental 

impacts of compliance appear to be out of the ordinary for any of these facilities. A likely short 

remaining useful life for two units was noted in one case, but a longer remaining useful life would 

not alter that particular determination.

It should be noted that, in order to show continued progress past 2018, the criteria will likely be 

different in the next reasonable progress assessment in order to maintain a continuous downward 

glidepath toward natural background conditions by 2064. The facilities in North Carolina that 

have units that contribute at least one percent to visibility impairment at any Class I area in the 

State, or in neighboring States, were sent letters from the NCDAQ indicating that while no 

additional controls were identified during this reasonable progress assessment, the sources 

should be evaluating possible SO2 reduction strategies for the next round of regional haze SIP 

development. Those letters are contained in Appendix H.3.

EPA Findings: NCDAQ identified 34 emission units at eight facilities in North Carolina as 

having a significant contribution because they fell within the sulfate AOI of any Class I area and 

had a one percent or greater contribution to the sulfate visibility impairment to at least one Class I 

area. Sixteen of the 34 emission units identified for a reasonable progress control analysis are 

EGUs subject to CAIR. As identified in the submittal (Carolina Power & Light and L V Sutton 

are now part of the Progress Energy system), these units are:

Carolina Power & Light Asheville Steam E-1 and E-2; 

Duke Energy Corporation - Buck Steam Station G-4 and G-5;

Duke Energy Corporation – Dan River Station G-21;

Duke Energy Corporation - Cliffside Steam G-86, G-87, and G-88; 

Duke Energy Corporation - Marshall Steam G-1 and G-2;

Duke Energy Corporation - Riverbend Steam G-17, G-19, and G-20; 

L V Sutton Steam Electric Plant G-188;

Progress Energy - F Lee Plant G-2 and G-3. 

Prior to the CAIR remand by the Court, EPA believed the State’s demonstration that no 

additional controls beyond CAIR for SO2 for affected EGUs for the first implementation period to 

be acceptable. However, as explained in Section III.C.1–EPA Findings, the State’s demonstration 

regarding BART and reasonable progress for its EGUs, and other provisions in this SIP revision, 

are based on CAIR. In a separate action, EPA has proposed a limited disapproval of the North 

Carolina regional haze SIP because of deficiencies in the State’s regional haze SIP submittal 

arising from the remand by the D.C. Circuit to EPA of CAIR. See 76 FR 82219. Consequently, 
58

EPA is not taking action in this proposed rulemaking to address the State’s reliance on CAIR to 

meet certain regional haze requirements.

NCDAQ identified the following 18 emission generating units at six non-EGU facilities that fall 

within the sulfate AOI of any Class I area and contribute one percent or more to visibility 

impairment: 

Blue Ridge Paper Products - Canton Mill G-24, G-25, G-26, G-31, G-32, G-65 and G-66;

Cogentrix Kenansville Gen1;

PCS Phosphate Company Inc. - Aurora G-1032, G-1033, G-1034, G-1035;

Weyerhaeuser Company - New Bern G-42; 

Weyerhaeuser Company – Plymouth.

Two of the units at PCS Phosphate are subject to BART. These two units are being shut down 

and replaced by a larger unit. The Permit for the facility requires these units to shut down once 

the new unit is fully operating. The two units at the Ecusta Business Development Center shut 

down prior to the SIP being submitted.

NCDAQ has concluded that, at this time, the application of BART constitutes reasonable progress 

for three units at Blue Ridge Paper and thus, is not requiring any additional controls for 

reasonable progress. As discussed in EPA’s Reasonable Progress Guidance document, since the 

BART analysis is based, in part, on an assessment of many of the same factors that must be 

addressed in establishing the RPG, EPA believes it is reasonable to conclude that any control 

requirements imposed in the BART determination also satisfy the RPG-related requirements for 

source review in the first RPG planning period.2 Thus, EPA proposes to agree with the State’s 

conclusions that the BART control evaluations satisfy reasonable progress for the first 

implementation period for these three units. NCDAQ has concluded that there are no costeffective controls available for the remaining units at this time, and therefore, is not requiring any 

of these non-EGU facilities to install additional controls for reasonable progress.

In general, EPA also proposes to find North Carolina’s evaluation of the four statutory factors for 

reasonable progress to be reasonable. EPA believes that the North Carolina SIP ensures 

reasonable progress. EPA notes that given the emissions reductions resulting from CAIR, North 

Carolina’s CSA, and the measures in nearby states, the visibility improvements projected for the 

affected class I areas are in excess of that needed to be on the glidepath for each of the five Class 

I areas in the State.

In addition, EPA proposes to find that North Carolina fully evaluated, in terms of the four 

reasonable progress factors, appropriate control technologies available at the time of its analysis 

and applicable to these facilities. EPA also proposes to find that North Carolina consistently 

applied its criteria for reasonable compliance costs, and where appropriate, the State included 

justification for the other factors influencing the control determination. 

 

2 Memorandum from William L. Wehrum, Acting Assistant Administrator for Air and Radiation, to EPA Regional 

Administrators, EPA Regions 1-10, Guidance for Setting Reasonable Progress Goals under the Regional Haze 

Program 4.2-4.3 (July 1, 2007).,
59

The State also adequately presented its basis for considering certain CAIR sources as part of its 

reasonable progress analysis. However, as explained in Section III.C.1–EPA Findings, the State’s 

demonstration regarding BART and reasonable progress for its EGUs, and other provisions in this 

SIP revision, are based on CAIR. Prior to the CAIR remand by the Court, EPA believed the 

State’s demonstration that CAIR satisfies BART for SO2 and NOx for affected EGUs for the first 

implementation period to be acceptable. In a separate action, EPA has proposed a limited 

disapproval of the North Carolina regional haze SIP because of deficiencies in the State’s 

regional haze SIP submittal arising from the remand by the D.C. Circuit to EPA of CAIR. See 76 

FR 82219. Consequently, EPA is not taking action in this proposed rulemaking to address the 

State’s reliance on CAIR to meet certain regional haze requirements.
60

III. Evaluation of Regional Haze Submittal

C. Long-Term Strategy 

C.4. Enforceability of Reasonable Progress Measures: The SIP needs to provide enforceable 

emissions limitations and schedules for compliance for each newly adopted measure needed to 

achieve the reasonable progress goals. 

State Regional Haze Submittal

EPA Note: No newly adopted source specific measures were required to achieve the reasonable 

progress goals so no new rules or permits were included in this submittal. 

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision.

The following attachments were included in the submittal but were not relied upon for the 

reasonable progress demonstration and thus, were not assessed for enforceability: Attachment H.4 

- North Carolina Department of Transportation Rule to Control Particulate Matter; and 

Attachment H.5 - North Carolina Hog Waste Legislation.
61

III. Evaluation of Regional Haze Submittal

D. Best Available Retrofit Technology (BART) Requirements

D.1 Identification of all BART Eligible Sources: The SIP should include a list of all BARTeligible sources within the State.

State Regional Haze Submittal

NC SIP Narrative, Page 77:

Section 169A of the CAA directs States to assess certain large emission sources for additional 

controls in order to address visibility impacts. States are directed to conduct BART 

determinations for such sources in specific source categories, and which contribute to visibility 

impairment in Class I areas. The 1999 regional haze rule includes the BART requirement, and 

directs States to include BART in their regional haze SIPs. On July 6, 2005, the USEPA published 

a revised final rule, including Appendix Y to 40 CFR Part 51, the Guidelines for BART 

Determinations Under the Regional Haze Rule (hereinafter referred to as the “BART 

Guidelines”) that provides guidance to states on determining which of these sources should be 

subject to BART, and how to determine BART for each source.

A BART-eligible source is one which has the potential to emit 250 tons or more of a visibility

impairing air pollutant, was put in place between August 7, 1962 and August 7, 1977, and whose 

operations fall within one or more of 26 specifically listed source categories. Under the CAA, a 

BART determination is required for any BART-eligible source that a State determines „„emits any 

air pollutant which may reasonably be anticipated to cause or contribute to any impairment of 

visibility in any such area.‟‟

For those sources subject to BART, Section 169A(g)(7) of the CAA requires that States must 

consider the following factors in making BART determinations: (1) the costs of compliance, (2) 

the energy and non-air quality environmental impacts of compliance, (3) any existing pollution 

control technology in use at the source, (4) the remaining useful life of the source, and (5) the 

degree of improvement in visibility which may reasonably be anticipated to result from the use of 

such technology.

The following is a list of facilities with BART-eligible sources in North Carolina. See

Appendix L for a detailed description of each BART-eligible emission unit:

• Alcoa, Inc.-Badin Works

• Blue Ridge Paper Products – Canton Mill

• DAK Americas – Cape Fear

• DAK Americas – Cedar Creek

• Duke Energy – Belews Creek Steam Station

• Duke Energy – Cliffside Steam Station

• Duke Energy – Marshall Steam Station

• Elementis Chromium

• International Paper – Riegelwood Mill

• International Paper – Roanoke Rapids
62

• Invista, S.A.R.L.

• PCS Phosphate Company Inc. – Aurora

• Progress Energy – Asheville Plant

• Progress Energy – Roxboro Steam Electric Plant

• Progress Energy – Sutton Plant

• Weyerhaeuser Company – Plymouth

• Weyerhaeuser Company – New Bern

The BART-eligible sources were identified using the methodology in the BART Guidelines.

• One or more emissions units at the facility fit within one of the 26 categories listed in the 

BART Guidelines;

• The emission unit(s) were in existence on August 7, 1977 and began operation at some

point on or after August 7, 1962; and

• The potential emissions considering enforceable limits from all emission units identified 

in the previous two bullets emission units were 250 tons or more per year of any of these 

visibility-impairing pollutants: SO2, NOx, and PM10.

The BART Guidelines recommend addressing these visibility-impairing pollutants: SO2, NOx, 

and particulate matter, and suggest that States use their best judgment in determining whether to 

address VOC or ammonia emissions. The NCDAQ addressed SO2 and NOx, and used particulate 

matter less than 10 microns in diameter (PM10) as an indicator for particulate matter to identify 

BART-eligible units, as the BART Guidelines recommend. As discussed in detail in Appendix L, 

VISTAS modeling demonstrated that VOCs and ammonia from point sources are not visibilityimpairing pollutants. For this reason, the NCDAQ did not evaluate emissions of VOCs and 

ammonia in BART determinations.

NC SIP, Appendix L, Page 6:

The USEPA provided guidance for identifying BART-eligible sources in 40 CFR Part 51

Appendix Y. North Carolina followed this guidance in identifying its BART-eligible sources. The 

North Carolina 2002 air emissions inventory was reviewed to determine the population of BART 

Related Documentation potential BART-eligible sources. The data were initially queried for any 

sources emitting SO2, NOx, PM10, VOC, or NH3. The data set was refined based on emissions, 

whether emission units fit in any of the twenty-six listed source categories for BART, and 

available date information obtained through review of permit and inspection reports and 

discussion with the NCDAQ‟s Permits Section and Regional Office staff familiar with the 

facilities. An information packet on BART was sent to and additional information was collected 

from the remaining sources regarding potential emissions and BART eligibility from the 

standpoint of source category and date criteria. Through this iterative review process, the list of 

potential BART-eligible sources was pared down to the seventeen BART-eligible sources 

presented below.

The facilities are scattered throughout the state with closest facility proximity to Class I areas

ranging from 9.5 kilometers (km) to 186.8 km. The facilities include one primary aluminum

facility, five pulp and paper facilities, six electric utilities, four chemical manufacturers, and one
63

phosphate fertilizer manufacturer. One of the utilities, Progress Energy Asheville in Buncombe

County, resides under the Western North Carolina local program jurisdiction.

Figure 38. Figure 3-1. North Carolina BART-Eligible Sources and Class I Areas.

Note: Labels represent facility status as of the time the map was created and reflects the first 

round of proposed exemptions. An additional seven of the seventeen facilities, including six 

utilities, were proposed for exemption in a second public notice in August 2007.

Note: During this process some facility names have changed. International Paper is now 

KapStone and Weyerhaeuser Plymouth is now Domtar. Facilities denoted as CP&L are now 

Progress Energy.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision.
64

III. Evaluation of Regional Haze Submittal

D. Best Available Retrofit Technology (BART) Requirements

D.2. Modeling or Other Demonstrations for BART Exempt Sources: For each BART-eligible 

source in the State exempted from BART a demonstration, using an acceptable approach, that the 

source or group of sources does not violate the established threshold. The established exemption 

threshold for determining if a BART-eligible source contributes to regional haze cannot exceed 

0.5 deciviews.

State Regional Haze Submittal

Identification of BART Source

NC SIP Narrative, Pages 67-70:

Under the BART Guidelines, the NCDAQ may consider exempting some sources from BART if it 

is determined that they do not cause or contribute to visibility impairment in a Class I area. In 

accordance with the BART guidelines, the NCDAQ chose to perform source-specific analyses to 

determine which sources cause or contribute to visibility impairment using the CALPUFF model. 

The CALPUFF modeling protocol used for determining which facilities are subject to BART is 

included in Appendix L. In accordance with the Guidelines, a contribution threshold of 0.5 dv 

was used for determining which sources were subject to BART. Detailed discussions about how a 

threshold of 0.5 dv meets the USEPA‟s BART guidelines can be found in Appendix L.

All of North Carolina‟s BART-eligible sources submitted exemption-modeling demonstrations. 

Utilities subject to the CAIR Rule were only required to model for PM10. 

All remaining sources were required to model for SO2, NOx and PM10. Fifteen of the seventeen 

sources were able to demonstrate exemption. Additional details are available in Appendix L. 

Facilities found to be subject to BART must complete a BART analysis.

The facilities that were able to demonstrate exemption from BART based on CALPUFF modeling 

conducted using the VISTAS modeling protocol and the old IMPROVE equation were:

• Alcoa, Inc.-Badin Works

• DAK Americas – Cape Fear

• DAK Americas – Cedar Creek

• Elementis Chromium

• International Paper – Riegelwood Mill

• International Paper – Roanoke Rapids

• Invista, S.A.R.L.

• Progress Energy – Asheville Plant

• Progress Energy – Sutton Plant

• Weyerhaeuser Company – Plymouth

The facilities that were able to demonstrate exemption from BART based on CALPUFF modeling 

conducted using the VISTAS modeling protocol and the new IMPROVE equation were:

• Duke Energy – Belews Creek Steam Station

• Duke Energy – Cliffside Steam Station
65

• Duke Energy – Marshall Steam Station

• Progress Energy – Roxboro Steam Electric Plant

• Weyerhaeuser Company – New Bern

The NCDAQ has proposed to exempt all of the units and no significant adverse comments were 

received during the public comment periods. For further details about the BART exemption 

modeling, please refer to Appendix L.

There were two sources that failed to model below the 0.5 dv threshold for exemption. 

• Blue Ridge Paper Products – Canton Mill

• PCS Phosphate Company Inc. – Aurora

For the exemption modeling, both sources were required to model for SO2, NOx and PM10. PCS 

Phosphate used the new IMPROVE equation for their modeling; whereas Blue Ridge Paper used 

the old IMPROVE equation.

The following table provides the exemption modeling results for the North Carolina BARTeligible sources:

Source Class I Areas Distance 

to Class I 

Area 

(km)

Impact change 

(dv) – old 

IMPROVE 

Impact change 

(dv) – new 

IMPROVE 

Alcoa, Inc –Badin Works Linville Gorge

James River Face

Cape Romain

Great Smoky Mountains

Shining Rock

164

242

265

264

241

0.260

0.175

0.135

0.113

0.109

Blue Ridge Paper 

Products-Canton 

Shining Rock

Great Smoky Mountains

Linville Gorge

Joyce Kilmer-Slickrock

Cohutta

11

22

89

99

161

2.887

0.764

0.155

0.134

0.095

DAK Americas-Cape 

Fear

Swanquarter

Cape Romain

187

182

0.19

0.16

DAK Americas-Cedar 

Creek

Swanquarter

Cape Romain

Linvelle Gorge

James River Face 

219

216

295

291

0.08

0.06

0.05

0.04

Duke Energy-Belews 

Creek

Linville Gorge

James River Face

Shenandoah

Great Smoky Mountains

Shining Rock

180

140

215

290

280

0.31 0.26

0.24

0.20

0.09

0.09

Duke Energy-Cliffside Linville Gorge

Shining Rock

Great Smoky Mountains

Cohutta

Joyce Kilmer-Slickrock

60

105

130

265

205

0.29 0.25

0.13

0.09

0.05

0.05

Duke Energy-Marshall Linville Gorge 95 0.52 0.46
66

James River Face

Shining Rock

Great Smoky Mountains

Joyce Kilmer-Slickrock 

240

180

200

280

0.15

0.15

0.11

0.07

Elementis Chromium Swanquarter

Cape Romain

170

200

0.185

0.129

International PaperRiegelwood Swanquarter

Cape Romain

210

150

0.112

0.109

International PaperRoanoke RapidsSwanquarter

Shenandoah

James River Face

164

204

200

0.305

0.248

0.234

Invista, S.A.R.L Swanquarter

Cape Romain

184

187

0.286

0.215

PCS Phosphate 

Company-Aurora

Swanquarter 32 1.319 0.976

Progress EnergyAsheville Shining Rock

Great Smoky Mountains

Linville Gorge

Joyce Kilmer-Slickrock

Cohutta

26

50

68

125

185

0.372

0.265

0.143

0.042

0.031

Progress EnergyRoxboroJames River Face

Shenandoah

Linville Gorge

Swanquarter

Dolly Sods

113

168

257

264

265

0.58 0.483

0.304

0.214

0.152

0.069

Progress Energy-Sutton Swanquarter

Cape Romain

185

183

0.156

0.148

Weyerhaeuser CompanyPlymouthSwanquarter

Shenandoah

James River Face

73

300

300

0.336

0.087

0.068

Weyerhaeuser CompanyNew BernSwanquarter

Cape Romain

65

300

0.722

0.211

0.367

Figure 39. BART Exemption Modeling Results 

In total, fifteen of North Carolina‟s seventeen BART-eligible sources were able to demonstrate 

that they did not cause or contribute to visibility impairment in any Class I area within 300 km of 

the source. Six sources used the new IMPROVE equation in efforts to demonstrate exemption. 

(Additional information related to the BART modeling is presented in Appendix L.)

NC SIP, Appendix L, Page 6: 

North Carolina‟s BART-eligible sources were presumed to be subject to BART but were provided 

the opportunity to submit modeling demonstrations showing that they did not contribute to 

visibility impairment, i.e., had less than 0.5 dv impact, on any Class I area within 300 km and 

thus could be exempt.

Use of the New IMPROVE Algorithm and Sea Salt (NC SIP, Appendix L, Page L-25)

During the regional haze SIP development process, the IMPROVE Steering Committee made 

recommendations for a new IMPROVE equation to determine background conditions. VISTAS 

contracted Dr. Ivar Tombach to develop a post processor to allow CALPOST outputs to be used 
67

with the new IMPROVE equation. A discussion of the rationale for use of the new IMPROVE 

equation follows is included in Appendix B. 

Data Access – EPA Note: Due to the excessive size of data and modeling files that constitute the 

BART modeling developed by the sources, the archival and access of this data is made available 

to the public upon request and is discussed in Appendix I of the SIP submittal.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed the 

development of technical analyses to support the BART assessment provision. North Carolina 

requested that its sources follow the VISTAS modeling protocol in development of their site 

specific protocols and explain any deviations that they proposed to use. In the site-specific 

modeling demonstrations submitted by North Carolina’s BART-eligible sources, the CALPUFF 

model incorporating three years of pre-processed MM5 meteorological data was used to evaluate 

the deciview change compared to natural background conditions at each of the Class I areas 

within 300 km of the source. Both the 4 km and 12 km MM5 datasets prepared by VISTAS were 

used. Facilities submitted site-specific modeling protocols and subsequent modeling 

demonstrations based upon the VISTAS modeling protocol. The site-specific protocols are found 

in Attachment H-5 and the demonstrations are found in Attachment L-4 of the SIP submittal. The 

protocols and demonstrations were reviewed by the State of North Carolina. The individual 

facility modeling demonstrations were shared with both EPA and FLMs for their review and 

comment. The resulting comments were in turn shared with the facilities. The State worked 

throughout the process to resolve many of the issues and concerns reflected in their comments. 

Sources demonstrating less than a 0.5 deciview impact were considered exempt. Sources 

contributing 0.5 deciview impact or greater were considered subject to BART and were required 

to proceed to an analysis of what control measures, if any, constitute BART for the source.

EPA proposes to find that the State adequately identified the BART-eligible sources and those 

sources subject to BART controls. EPA proposes to find that the State successfully developed 

and provided the technical analyses to support the BART assessment provision for the non-CAIR 

sources, and that the State appropriately identified the BART-eligible sources and those sources 

subject to BART controls. The State developed and provided the technical analyses to support 

the BART assessment provision for the non-CAIR sources. However, North Carolina opted to 

have CAIR satisfy BART for SO2 and NOx for affected CAIR EGUs, as allowed under the 

Regional Haze regulations. As explained in Section III.C.1–EPA Findings, the State’s 

demonstration regarding CAIR and reasonable progress for its EGUs, and other provisions in this 

SIP revision, are based on CAIR. In a separate action proposing limited disapproval of the 

regional haze SIPs of a number of states, EPA noted that these states relied on the trading 

programs of CAIR to satisfy the BART requirement and the requirement for a LTS sufficient to 

achieve the state-adopted RPGs. See 76 FR 82219 (December 30, 2011). In that action, EPA 

proposed a limited disapproval of North Carolina’s regional haze SIP submittal insofar as the SIP 

relied on CAIR. For that reason, EPA is not taking action on that aspect of North Carolina’s 

regional haze SIP in this action. 

CALPUFF MODELING
68

EPA proposes to find that the CALPUFF3 modeling system was appropriately applied by 

NCDAQ in the assessment of visibility impairment in Class I areas for specific sources subject to 

the BART regulations. The BART regulations indicate that CALPUFF or other appropriate 

models can be used to determine if an individual source is anticipated to cause or contribute to 

impairment of visibility in Class I areas. The current regulatory niche for the CALPUFF 

modeling system in 40 CFR, part 51, Appendix W: Guideline on Air Quality Models (Appendix 

W) is for compliance with non-attainment New Source Review (NNSR)/ and Prevention of 

Significant Deterioration (PSD) permitting requirements for long range transport (i.e., greater 

than 50 KM) applications at Class I areas. There is no preferred model for assessing visibility 

impact under BART. However, it is appropriate for the State of North Carolina to use the 

CALPUFF modeling system for its BART exemption and control determination modeling. 

VISTAS developed a “Protocol for the Application of CALPUFF for BART Analyses.” The final 

VISTAS BART Modeling Protocol (Revision 3.2, dated Aug. 6, 2006) states that VISTAS will 

use CALPUFF ver. 5.754 and CALMET ver. 5.7 (i.e., the VISTAS version of CALPUFF). No 

formal approval of the CALPUFF VISTAS version (either ver. 5.754 or 5.756) has been made by 

EPA Region 4. However, there has been an implied acceptance of the VISTAS CALPUFF 

version as EPA Region 4 has reviewed and commented on the VISTAS BART Modeling 

Protocol and the source-specific modeling protocols and reports that were developed by the North 

Carolina specific sources performing BART modeling. The VISTAS BART modeling protocol 

underwent an extensive stakeholder development and review process, that involved EPA, FLMs, 

industrial sources, trade groups, lawyers and other interested parties, before the State decided to 

require CALPUFF modeling to evaluate the BART requirements. 

The State required all BART-eligible sources to perform BART exemption modeling and to 

develop source-specific protocols that complied with the VISTAS protocol. EPA Region 4 

provided reviews and comments on the source-specific protocols and their subsequent exemption 

modeling reports. 

New IMPROVE Equation

The CALPUFF model was simulated with the default inputs as recommended in the March 16, 

2006, EPA memorandum, “Dispersion Coefficients for Regulatory Air Quality Modeling in 

CALPUFF.” A new methodology was used by the VISTAS states to process the mass 

concentrations from CALPOST (post-CALPUFF processor) using the new IMPROVE equation 

so that the BART analyses could consider both the old and new IMPROVE equations. EPA 

Headquarters and other EPA regional offices and the Federal Land Managers (FLMs) from the 

National Park Service and the U.S. Fish and Wildlife Service consulted on the VISTAS 

innovative approach that was developed to utilize the new IMPROVE equation in the BART 

assessment and to determine the change in visibility impacts. While these other parties were 

consulted in preparation of EPA Region 4’s response, the response represented the EPA Region 4 

 

3 Note that EPA’s reference to CALPUFF encompasses the whole CALPUFF modeling system, including 

CALMET/CALPUFF/CALPOST and other pre and post processors. The different versions of CALPUFF have

corresponding versions of CALMET, CALPOST, etc. which may not be compatible with previous versions (e.g., the 

output from a newer version of CALMET may not be compatible with an older version of CALPUFF). The different 

versions of the CALPUFF modeling system are available from the model developer on the following website: 

http://www.src.com/verio/download/download.htm. 
69

position on the new methodology. Use of the methodology by BART sources in states located in 

other EPA Regions would require consultation with the appropriate regional office. EPA 

required the State of North Carolina to submit a request to the EPA Region 4 Regional 

Administrator requesting the use of this new methodology for the BART CALPUFF-based 

modeling. A March 19, 2007, letter justifying the need for this approach was sent to EPA, and 

approval from the Regional Administrator was provided to the State on May 11, 2007. The 

methodology and State and Region 4 letters are located in the State’s submittal (Appendix L.8).

The new methodology uses a spreadsheet developed by VISTAS to post-process the visibility 

modeling output from the CALPUFF and CALPOST models. The spreadsheet implements the 

new IMPROVE equation for calculating visibility impacts that was adopted by the IMPROVE 

Steering Committee in December 2005. EPA Region 4 has previously provided comments 

indicating that new methodology is an alternative modeling approach and should meet the 

requirements in Section 3.2 of Appendix W, Guideline on Air Quality Models contained in 40 

CFR, part 51. EPA reviewed the State’s rationale for using the new methodology. This 

demonstration included a rationale for the need to use the new IMPROVE equation, a discussion 

of the performance of the equation versus measured values, a submittal of the modified postprocessing methodology and documentation to support the development of concentrations for the 

different terms in the equation. Based on the demonstration provided in North Carolina’s letter of 

March 7, 2007, EPA approved the State’s request.

Contribution Threshold

With respect to the contribution threshold used in the CALPUFF modeling, the State was also 

required to justify its choice of the 0.5 deciview contribution threshold for exempting sources 

from BART eligibility. North Carolina used a contribution threshold of 0.5 deciview for 

determining which sources are subject to BART. NCDAQ concluded that, considering the results 

of the visibility impacts modeling conducted, a 0.5 deciview threshold was appropriate in this 

situation and a lower threshold was not warranted for the following reasons. The State 

demonstrated that there are a limited number of in and out of state sources that impact the Class I 

areas in the State, and that there are a limited number of sources in close proximity to each of the 

affected Class I areas. Additionally, the majority of the visibility impacts were well below 0.5 

deciview. Also, even though several sources impacted each Class I area, the overall impacts were 

low from the sources. EPA is proposing to agree with North Carolina that the overall impacts of 

these sources are not sufficient to warrant a lower contribution threshold and that a 0.5 deciview 

threshold was appropriate in this instance.

References used in the EPA review: 

1. 40 CFR part 51, Appendix W: Guideline on Air Quality Models.

2. May 11, 2007, letter from James I. Palmer, Regional Administrator, EPA Region 4, to B. 

Keith Overcash, P.E. Director, North Carolina Department of Environmental and Natural 

Resources, re: “Approval for the use of the VISTAS methodology for use of the New 

IMPROVE equation with CALPUFF model results”. 

3. 40 CFR Part 51, Appendix Y: Guidelines for BART Determinations Under the Regional 

Haze Rule.
70

4. IWAQM. 1998. Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 

Summary Report and Recommendations for Modeling Long-Range Transport and Impacts 

on Regional Visibility. EPA-454/R-98-019. U.S. Environmental Protection Agency, 

Office of Air Quality Planning and Standards, Research Triangle Park, NC. 

5. VISTAS, 2006. Tombach, I., P. Brewer, T. Rogers, and C. Arrington, Protocol for the 

Application of the CALPUFF Model for Analysis of Best Available Retrofit Technology 

(BART) Revision 2 – 3/9/06 developed through consultation with EPA, the FLMs, 

VISTAS state and local Agencies and industry stakeholders VISTAS, 2006. Tombach, I., 

P. Brewer, T. Rogers, and C. Arrington, Located at http://www.vistassesarm.org/documents/BARTModelingProtocol_rev3.2_31Aug06.pdf.

6. March 16, 2006, EPA memorandum from Dennis Atkinson to Kay T. Prince on 

Dispersion Coefficients for Regulatory Air Quality Modeling in CALPUFF.

7. Additional Regional Haze Questions, EPA, September 27, 2006 Revision. Answers to 

questions that EPA received from various States and Regional Planning Organizations 

(RPOs) related to the submission of regional haze SIPs under the program described by 40 

CFR 51.308. This document provides guidance to the State air pollution control agencies 

and the general public on meeting the regional haze SIP requirements. 
71

III. Evaluation of Regional Haze Submittal

D. Best Available Retrofit Technology (BART) Requirements

D.3. Identification of Sources Addressed by CAIR: States which adopt the CAIR cap and trade 

program for SO2 and NOx are allowed to apply CAIR controls as a substitute for controls 

required under BART. The SIP should include a list of all BART-eligible sources within the State 

for which the CAIR rule is being applied.

State Regional Haze Submittal

NC SIP Narrative, Page 70:

Six of North Carolina‟s BART-eligible sources are EGUs subject to the North Carolina Clean 

Smokestacks Act. 

• Duke Energy – Belews Creek Steam Station

• Duke Energy – Cliffside Steam Station

• Duke Energy – Marshall Steam Station

• Progress Energy – Asheville Plant

• Progress Energy – Roxboro Steam Electric Plant

• Progress Energy – Sutton Plant

Under the Act, Duke Energy and Progress Energy must reduce their NOx emissions by 77 percent 

by 2009 and SO2 emissions by 73 percent by 2013. These sources have already installed or are 

installing scrubbers to reduce SO2 emissions and to reduce NOx emissions Selective Catalytic 

Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). The EGUs are required by the 

statute to submit annual update to their compliance plans to meet these requirements. The Duke 

Energy and Progress Energy compliance plans from the June 1, 2007 report Implementation of 

the Clean Smokestacks Act summarize the status of control on these EGUs and are attached to 

Appendix L.

The USEPA has determined that, as a whole, the CAIR cap-and-trade program improves

visibility more than implementing BART for individual sources in states affected by CAIR. A State 

that opts to participate in the CAIR program under 40 CFR 96.201-.224 (Subpart AAA through 

EEE) need not require BART-eligible EGUs subject to CAIR to install, operate, and maintain 

BART for SO2 or NOx emissions. Given that all BART-eligible units are installing scrubbers and 

NOx controls, and since North Carolina is participating in CAIR and accepts the US EPA‟s 

overall finding that CAIR “substitutes” for BART for NOx and SO2, North Carolina‟s EGUs 

were allowed to submit BART exemption modeling demonstrations for PM emissions only. All six 

EGUs demonstrated that they do not contribute to visibility impairment in any Class I area.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision. EPA believes that the State has appropriately identified the BART-eligible sources 

and those sources subject to BART controls. However, North Carolina opted to have CAIR 

satisfy BART for SO2 and NOx for affected CAIR EGUs, as allowed under the Regional Haze 

regulations. As explained in Section III.C.1–EPA Findings, the State’s demonstration regarding 

BART and reasonable progress for its EGUs, and other provisions in this SIP revision, are based 

on CAIR. In a separate action, EPA has proposed a limited disapproval of the North Carolina 
72

regional haze SIP because of deficiencies in the State’s regional haze SIP submittal arising from 

the State’s reliance on CAIR to meet certain regional haze requirements. See 76 FR 82219 

(December 30, 2011). EPA is not proposing to take action in this rulemaking on issues associated 

with North Carolina’s reliance on CAIR in its regional haze SIP. 
73

III. Evaluation of Regional Haze Submittal

D. Best Available Retrofit Technology (BART) Requirements

D.4. Source Specific BART Determinations: For each BART-eligible source in the State 

subject to BART, a determination of BART based on an analysis of the best system of continuous 

emission control technology available and associated emission reductions achievable (unless the 

State demonstrates that an emissions trading program or other alternative will achieve greater 

reasonable progress toward natural visibility conditions). To address the requirements for BART, 

the State must take into consideration the technology available, the costs of compliance, the 

energy and non-air quality environmental impacts of compliance, any pollution control equipment 

in use at the source, the remaining useful life of the source, and the degree of improvement in 

visibility that may reasonably be anticipated to result from the use of such technology.

State Regional Haze Submittal

NC SIP Narrative, Page 70:

Two sources, PCS Phosphate in Aurora, North Carolina and Blue Ridge Paper in Canton, North 

Carolina, were unable to demonstrate a contribution of less than 0.5 dv at all Class I areas 

within 300 km from their BART-eligible sources. These two facilities are considered to be 

“subject to BART” and were required to submit permit applications containing their evaluation 

of potential BART options and proposed BART determinations. These facilities submitted permit 

applications including their proposed BART determinations in the Fall of 2006. The proposed 

BART determinations have been reviewed by the NCDAQ (pages L.10-280- 697) and it was 

determined that BART is no additional controls at either facility. For a more detailed discussion 

of the BART determinations, please see Appendix L.10.

EPA Findings: Two BART-eligible sources (i.e., PCS Phosphate and Blue Ridge Paper) failed to 

model below the 0.5 deciview threshold for BART exemption. These two facilities are considered 

to be subject to BART and submitted permit applications including their proposed BART 

determinations in the Fall of 2006. The proposed BART determinations were reviewed by the 

NCDAQ, and the State determined that BART is no additional control at either facility. The 

BART determinations resulted in a new Title V permit with no additional control measures for 

Blue Ridge Paper and a new Title V permit with a Prevention of Significant Deterioration (PSD) 

netting analysis for SO2 for PCS Phosphate.

EPA proposes to find that North Carolina has appropriately addressed this provision for Blue 

Ridge Paper. Subsequent to this submittal, PCS Phosphate submitted a permit request to replace 

the two BART eligible units with a new, larger unit. The facility netted out of PSD review for 

SO2. NCDAQ has modified the PCS Phosphate operating permit allowing them to replace the 

two BART-subject sulfuric acid plants, units 3 and 4, with a new, larger unit, Unit #7. Appendix 

Y of 40 CFR part 51 indicates the shutdown of a source subject to a BART determination should 

be assured by an enforceable restriction preventing further operation. The permit requires PCS 

Phosphate to shut down units 3 and 4 when unit 7 is fully operational. Construction is complete 

on new unit 7 and the two units have been taken out of operation. North Carolina has issued a 

new permit for PCS Phosphate that replaces the BART eligible units. Since the BART eligible 

units will be eliminated and the new unit is not subject to BART, no additional analysis is 

required for BART. 
74

 

III. Evaluation of Regional Haze Submittal

D. Best Available Retrofit Technology (BART) Requirements

D.5. Enforceability of BART: For each BART-eligible source in the State subject to BART, the 

SIP should include emission limitations representing BART and schedules for compliance with 

BART. For each BART-eligible source in the State subject to BART, the SIP must include a 

requirement that each source subject to BART be required to install and operate BART as 

expeditiously as practicable, but in no event later than five years after approval of the 

implementation plan revision and a requirement that each source subject to BART maintains the 

control equipment required by this subpart and establishes procedures to ensure such equipment is 

properly operated and maintained. 

State Regional Haze Submittal

EPA Note: No new limitations were adopted for BART so no new limits were included for 

review.

EPA Findings: The State determined that for Blue Ridge Paper, BART is no control based on its 

evaluation of the five CAA factors. Consequently, the BART process will result in no new 

applicable requirements for the source, and this determination does not need to be reflected in the 

title V permit. EPA proposes to find that the determination is appropriately described in the SIP. 

For PCS Phosphate, the shutdown of units 3 and 4 is enforceable through provisions added to the 

facility’s operating permit.
75

III. Evaluation of Regional Haze Submittal

E. Coordination of Regional Haze and RAVI Requirements

The State must revise its SIP to provide for review and revision of a coordinated long-term 

strategy for addressing reasonably attributable and regional haze visibility impairment.

State Regional Haze Submittal

North Carolina did not explicitly address this requirement regarding a coordinated RAVI and 

regional haze long-term strategy. However, NCDAQ has included provisions in this SIP 

submittal that updated the elements subject to the RAVI long-term strategy requirements 

(including monitoring and new source review (NSR)):

NC SIP Narrative, Pages 95-97:

Monitoring Strategy

The primary monitoring network for regional haze, both nationwide and in North Carolina, is the

IMPROVE network. Given that IMPROVE monitoring data from 2000-2004 serves as the 

baseline for the regional haze program, the future regional haze monitoring strategy must 

necessarily be based on, or directly comparable to, IMPROVE. The IMPROVE measurements 

provide the only long-term record available for tracking visibility improvement or degradation 

and therefore North Carolina intends to rely on the IMPROVE network for complying with the 

regional haze monitoring requirement in the Regional Haze Rule.

There are currently 3 IMPROVE sites in North Carolina (2 at distinctly different locations in the 

mountains and one on the coast). In addition, as Table 9.0-1 shows, an IMPROVE site just across 

the border in Tennessee serves as the monitoring site for both the Great Smoky Mountains 

National Park and Joyce Kilmer-Slickrock Wilderness Area, both of which lie partly in Tennessee 

and partly in North Carolina.

In addition to the IMPROVE measurements, some ongoing long-term limited monitoring 

supported by Federal Land Managers provides additional insight into progress toward regional 

haze goals. North Carolina benefits from the data from these measurements, but is not 

responsible for the funding decisions to maintain these measurements into the future. Such 

measurements include:

• Web cameras operated by the National Park Service at Look Rock, Tennessee and Purchase 

Knob, North Carolina in Great Smoky Mountains National Park and by the United States Forest 

Service at Frying Pan Mountain in the Shining Rock Wilderness Area. 

• An integrating nephelometer for continuously measuring light scattering, operated by the 

National Park Service at Look Rock, Tennessee. 

• A Tapered Element Oscillating Microbalance (TEOM) for continuously measuring PM2.5 mass 

concentration, operated by the National Park Service at Look Rock, Tennessee.

Additional haze-related measurements were made in North Carolina in 2002-2005 as part of 

special monitoring studies by the VISTAS regional planning organization. These studies were 

intended to better understand source contributions to PM2.5 mass and visibility. They included 
76

continuous monitoring of sulfate, nitrate, and carbon to better understand daily trends in PM2.5, 

detailed analyses of carbon collected on filters to identify source contributions to carbon, and 

additional analyses of sodium and ammonium on IMPROVE filter samples. Funding does not 

exist to continue these special studies, however, the equipment has been transferred to the 

NCDAQ.

The continuous nitrate monitor continues to operate at the Millbrook site in Raleigh and the 

NCDAQ intends to operate this monitor as long as funds allow. Additionally, a second continuous 

nitrate monitor is in operation at the Rockwell monitoring site in Rowan County. Again, the 

NCDAQ plans to operate this monitor indefinitely as long as funds allow. The NCDAQ began 

operating a continuous sulfate monitor at the Millbrook in August 2007, and expect to have one 

at the Rockwell sites in January 2008. The NCDAQ is also operating a 5400 R&P monitor for 

organic, total, and elemental carbon at the Millbrook site. The 5400 R&P monitor is near the end 

of its lifecycle, but the NCDAQ plans to operate it as long as it can be kept functional or until 

money is available to purchase a better technology should such a technology become available. 

VISTAS also transferred a 5400 R&P monitor from the Look Rock special studies location, but 

the unit is inoperable. The NCDAQ used it for parts for the Millbrook unit, thus, a 5400 R&P unit 

is not available for the Rockwell site. At this time, the NCDAQ does intend to purchase one to 

place there due to the short lifecycle of the unit and the various operating issues.

In February 2008, the NCDAQ will finish a year-long black carbon study in Hickory with the 

aethalometer that was used at the Millbrook site. Depending on the results of the study, this 

monitor may remain at the Hickory site, return to the Millbrook site, or go to the Rockwell site. 

The NCDAQ will use the continuous speciation data from the sites discussed above to further the 

understanding of both PM2.5 and visibility formation and trends in North Carolina. The NCDAQ 

will operate the units discussed above as long as funds allow.

In addition, the NCDAQ and the local air agencies in the State operate a fairly comprehensive 

PM2.5 network of the filter based Federal reference method monitors, continuous mass monitors 

(TEOMs), filter based speciated monitors and the continuous speciated monitors described 

above. A map of the various locations around the State is included in Figure 9.0-1. These PM2.5 

measurements help the NCDAQ characterize air pollution levels in areas across the state, and 

therefore aid in the analysis of visibility improvement in and near the Class I areas.

NC SIP Narrative, Pages 100-101:

Ten Year Plan and Five Year Plan Update

40 CFR 51.308(f) requires the NCDAQ to revise its regional haze implementation plan and

submit a plan revision to the USEPA by July 31, 2018 and every ten years thereafter. In

accordance with the requirements listed in Section 51.308(f) of the federal rule for regional haze,

North Carolina commits to revising and submitting this regional haze implementation plan by

July 31, 2018 and every ten years thereafter.

In addition, 51.308(g) requires periodic reports evaluating progress towards the reasonable

progress goals established for each mandatory Class I area. In accordance with the requirements
77

listed in 51.308(g) of the federal rule for regional haze, the NCDAQ commits to submitting a

report on reasonable progress to the USEPA every five years following the initial submittal of

the SIP. The report will be in the form of a SIP revision. The reasonable progress report will

evaluate the progress made towards the reasonable progress goal for each mandatory Class I 

area located within North Carolina and in each mandatory Class I area located outside North 

Carolina which may be affected by emissions from within North Carolina.

The requirements listed in 51.308(g) include the following:

1. Description of the status of implementation;

2. Summary of emission reductions achieved thus far, including especially the status of

implementation of the CAIR compliance plans for EGUs compared to the control assumed in the 

modeling. 

3. Assessment of changes in visibility conditions at each Class I area (current vs. baseline),

expressed as 5-year averages of annual values for 20% best and worst days;

4. Analysis of emission changes over the 5-year period, identified by source or activity,

5. Analysis of any significant changes in or out of the State which have impeded progress;

6. Assessment of the sufficiency of the implementation plan to meet Reasonable progress goals;

7. Review and any modifications to our visibility monitoring plan.

All requirements listed in 51.308(g) shall be addressed in the SIP revision for reasonable

progress. In particular, the NCDAQ recognizes that the 2018 projections of EGU controls from

the IPM runs represent one solution to how the CAIR requirements will be met. By the time of the 

first periodic report, the NCDAQ anticipates that the actual compliance strategy for the various 

utility companies will be much more defined. An assessment of those actual compliance plans will 

be done for the first periodic report.

NC SIP Narrative, Page 101:

NSR/PSD

The NCDAQ believes that its New Source Review regulations for both nonattainment areas as 

well as the prevention of significant deterioration will address emissions from new sources that 

may located near a Class I area, or increased emissions from major modifications to existing 

sources. In addition to the NCDAQ regulations that would govern these sources, consultation 

with the FLMs is also required for sources that are subject to the new source review regulations. 

Page 101

Consultation

The NCDAQ also commits to ongoing consultation with the FLMs throughout the implementation 

process, including annual discussion of the implementation process and the most recent 

IMPROVE monitoring data and VIEWS data.. 

EPA Findings: EPA proposes to find that this regional haze submittal adequately supplements 

and augments North Carolina’s RAVI visibility provisions to address regional haze, updating the 

monitoring and LTS provisions as summarized below in this section. Under EPA’s RAVI 

regulations, the RAVI portion of a state SIP must address any integral vistas identified by the 

FLMs pursuant to 40 CFR 51.304. See 40 CFR 51.302. An integral vista is defined in 40 CFR 
78

51.301 as a “view perceived from within the mandatory Class I Federal area of a specific 

landmark or panorama located outside the boundary of the mandatory Class I Federal area.” 

Visibility in any mandatory Class I area includes any integral vista associated with that area. The 

FLMs did not identify any integral vistas in North Carolina. In addition, the Class I areas in 

North Carolina are neither experiencing RAVI nor are any of its sources affected by the RAVI 

provisions. Thus, the December 17, 2007, North Carolina regional haze SIP submittal does not 

explicitly address the two requirements regarding coordination of the regional haze with the 

RAVI LTS and monitoring provisions. North Carolina has, however, previously made a 

commitment to address RAVI should the FLMs certify visibility impairment from an individual 

source.4 EPA proposes to find that this regional haze submittal appropriately supplements and 

augments North Carolina’s RAVI visibility provisions to address regional haze by updating the 

monitoring and LTS provisions as summarized below.

In its December 17, 2007, submittal, NCDAQ updated its visibility monitoring program and 

developed a LTS to address regional haze. Also in this submittal, NCDAQ affirmed its 

commitment to complete items required in the future under EPA’s RHR. Specifically, NCDAQ 

made a commitment to review and revise its regional haze implementation plan and submit a plan 

revision to EPA by July 31, 2018, and every 10 years thereafter. See 40 CFR 51.308(f). In 

accordance with the requirements listed in 40 CFR 51.308(g) of EPA’s regional haze regulations 

and 40 CFR 51.306(c) of the RAVI LTS regulations, NCDAQ committed to submitting a report 

to EPA on progress towards the RPGs for each mandatory Class I area located within North 

Carolina and for each mandatory Class I area located outside North Carolina that may be affected 

by emissions from within North Carolina. The progress report is required to be in the form of a 

SIP revision and is due every five years following the initial submittal of the regional haze SIP. 

See 40 CFR 51.308(g). Consistent with EPA’s monitoring regulations for RAVI and regional 

haze, North Carolina will rely on the IMPROVE network for compliance purposes, in addition to 

any RAVI monitoring that may be needed in the future. See 40 CFR 51.305, 40 CFR 

51.308(d)(4). Also, the North Carolina new source review (NSR) rules, previously approved in

the State’s SIP, continue to provide a framework for review and coordination with the FLMs on 

new sources and major modifications to existing sources subject to the NSR regulations which 

may have an adverse impact on visibility in either form (i.e., RAVI and/or regional haze) in any 

Class I area. 

 

4North Carolina submitted its visibility SIP revisions addressing RAVI on April 15, 1985, which EPA approved on 

January 21, 1986 (51 FR 2695).
79

III. Evaluation of Regional Haze Submittal

F. Monitoring Strategy and Other Implementation Requirements

Monitoring Strategy: The SIP must include a monitoring strategy for measuring, characterizing, 

and reporting of regional haze visibility impairment that is representative of all mandatory Class I 

Federal areas within the State and/or summarize monitoring strategy of states with affected 

mandatory Class I Federal areas. Compliance with this requirement may be met through 

participation in the Interagency Monitoring of Protected Visual Environments (IMPROVE) 

network. 

Other Requirements: The implementation plan must also provide for the following:

A. The establishment of any additional monitoring sites or equipment needed to assess 

whether reasonable progress goals to address regional haze for all mandatory Class I 

Federal areas within the State are being achieved.

B. Procedures by which monitoring data and other information are used in determining the 

contribution of emissions from within the State to regional haze visibility impairment at 

mandatory Class I Federal areas both within and outside the State.

C. The reporting of all visibility monitoring data at least annually for each mandatory Class I 

Federal area in the State. To the extent possible, the State should report monitoring data 

for visibility electronically and use of the Visibility Information Exchange Web System 

(VIEWS) is encouraged.

D. Other elements, including reporting, recordkeeping, and other measures, necessary to 

assess and report on visibility.

State Regional Haze Submittal

NC SIP Narrative, Pages 95-97:

Such monitoring is intended to provide the data needed to satisfy four objectives:

1. Track the expected visibility improvements resulting from emissions reductions 

identified in this SIP.

2. Better understand the atmospheric processes of importance to haze

3. Identify chemical species in the ambient particulate matter and relate them to emissions 

from sources

4. Evaluate regional air quality models for haze and construct relative response factors 

for using those models

The primary monitoring network for regional haze, both nationwide and in North Carolina, is the 

IMPROVE network. Given that IMPROVE monitoring data from 2000-2004 serves as the 

baseline for the regional haze program, the future regional haze monitoring strategy must 

necessarily be based on, or directly comparable to, IMPROVE. The IMPROVE measurements 

provide the only long-term record available for tracking visibility improvement or degradation 

and therefore North Carolina intends to rely on the IMPROVE network for complying with the 

regional haze monitoring requirement in the Regional Haze Rule.

There are currently 3 IMPROVE sites in North Carolina (2 at distinctly different locations in the 

mountains and one on the coast). In addition, as Table 9.0-1 shows, an IMPROVE site just across 

the border in Tennessee serves as the monitoring site for both the Great Smoky Mountains 
80

National Park and Joyce Kilmer-Slickrock Wilderness Area, both of which lie partly in Tennessee 

and partly in North Carolina.

In addition to the IMPROVE measurements, some ongoing long-term limited monitoring 

supported by Federal Land Managers provides additional insight into progress toward regional 

haze goals. North Carolina benefits from the data from these measurements, but is not 

responsible for the funding decisions to maintain these measurements into the future. Such 

measurements include:

• Web cameras operated by the National Park Service at Look Rock, Tennessee and

Purchase Knob, North Carolina in Great Smoky Mountains National Park and by the

United States Forest Service at Frying Pan Mountain, in the Shining Rock Wilderness Area.

• An integrating nephelometer for continuously measuring light scattering, operated by the 

National Park Service at Look Rock, Tennessee.

• A Tapered Element Oscillating Microbalance (TEOM) for continuously measuring

PM2.5 mass concentration, operated by the National Park Service at Look Rock,

Tennessee.

Additional haze-related measurements were made in North Carolina in 2002-2005 as part of 

special monitoring studies by the VISTAS regional planning organization. These studies were 

intended to better understand source contributions to PM2.5 mass and visibility. They included 

continuous monitoring of sulfate, nitrate, and carbon to better understand daily trends in PM2.5, 

detailed analyses of carbon collected on filters to identify source contributions to carbon, and 

additional analyses of sodium and ammonium on IMPROVE filter samples. Funding does not 

exist to continue these special studies, however, the equipment has been transferred to the 

NCDAQ.

The continuous nitrate monitor continues to operate at the Millbrook site in Raleigh and the 

NCDAQ intends to operate this monitor as long as funds allow. Additionally, a second continuous 

nitrate monitor is in operation at the Rockwell monitoring site in Rowan County.

Again, the NCDAQ plans to operate this monitor indefinitely as long as funds allow. The

NCDAQ began operating a continuous sulfate monitor at the Millbrook in August 2007, and 

expect to have one at the Rockwell sites in January 2008. The NCDAQ is also operating a 5400 

R&P monitor for organic, total, and elemental carbon at the Millbrook site. The 5400 R&P 

monitor is near the end of its lifecycle, but the NCDAQ plans to operate it as long as it can be 

kept functional or until money is available to purchase a better technology should such a 

technology become available. VISTAS also transferred a 5400 R&P monitor from the Look Rock 

special studies location, but the unit is inoperable. The NCDAQ used it for parts for the 

Millbrook unit, thus, a 5400 R&P unit is not available for the Rockwell site. At this time, the 

NCDAQ does intend to purchase one to place there due to the short lifecycle of the unit and the 

various operating issues.

In February 2008, the NCDAQ will finish a year-long black carbon study in Hickory with the 

aethalometer that was used at the Millbrook site. Depending on the results of the study, this 

monitor may remain at the Hickory site, return to the Millbrook site, or go to the Rockwell site.
81

The NCDAQ will use the continuous speciation data from the sites discussed above to further the 

understanding of both PM2.5 and visibility formation and trends in North Carolina. The NCDAQ 

will operate the units discussed above as long as funds allow.

In addition, the NCDAQ and the local air agencies in the State operate a fairly comprehensive 

PM2.5 network of the filter based Federal reference method monitors, continuous mass monitors 

(TEOMs), filter based speciated monitors and the continuous speciated monitors described 

above. A map of the various locations around the State is included in Figure 9.0-1. These PM2.5 

measurements help the NCDAQ characterize air pollution levels in areas across the state, and

therefore aid in the analysis of visibility improvement in and near the Class I areas.

Figure 40. PM2.5 Monitoring Sites in NC

The IMPROVE measurements are central to North Carolina‟s regional haze monitoring strategy, 

and it is difficult to visualize how the objectives listed above could be met without the monitoring 

provided by IMPROVE. Any reduction in the scope of the IMPROVE network in North Carolina 

would jeopardize the State‟s ability to demonstrate reasonable progress toward visibility 

improvement in some of its Class I areas. In particular, North Carolina‟s regional haze strategy 

relies on emission reductions that will result from the CAIR and the CSA, which occur

on different time scales and will most likely not be spatially uniform. Monitoring at every Class I 

area is important to document the different air quality responses to the emissions reductions.

Because each of the current IMPROVE monitors in North Carolina represents a different 

airshed, reduction of the IMPROVE network by shutting down one of these monitoring sites 

impedes tracking progress at reducing haze at the affected Class I area. In the event this occurs, 
82

North Carolina, in consultation with the USEPA and relevant Federal Land Managers, will 

develop an alternative approach for meeting the tracking goal, perhaps by seeking contingency 

funding to carry out limited monitoring or by relying on data from nearby urban monitoring sites 

to demonstrate trends in speciated PM2.5 mass.

Data produced by the IMPROVE monitoring network will be used nearly continuously for 

preparing the 5-year progress reports and the 10-year SIP revisions, each of which relies on 

analysis of the preceding five years of data. Consequently, the monitoring data from the 

IMPROVE sites needs to be readily accessible and to be kept up to date. Presumably, IMPROVE 

will continue to process information from its own measurements at about the same pace and with 

the same attention to quality as it has shown in the recent past. The VIEWS web site has been 

maintained by VISTAS and the other Regional Planning Organizations to provide ready access to 

the IMPROVE data and data analysis tools. North Carolina is encouraging VISTAS and the other 

RPOs to maintain VIEWS or a similar data management system to facilitate analysis of the 

IMPROVE data.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision.
83

III. Evaluation of Regional Haze Submittal

G. Emission Inventory (40 CFR 51.308(d)(4)(v) (See also TSD Section III.C.))

The SIP must include a statewide inventory of emissions of pollutants that are reasonably 

anticipated to cause or contribute to visibility impairment in any mandatory Class I Federal area

within the State. The inventory must include emissions for a baseline year, emissions for the most 

recent year for which data are available, and estimates of future projected emissions, and a

commitment to update the inventory periodically.

State Regional Haze Submittal

NC SIP Narrative, Pages 18-24:

Emission Inventory

Chapter 4 discusses the emission inventory. An inventory was developed for the baseline year 

2002 and projected to 2018. The pollutants inventoried include VOCs, NOx, PM2.5, coarse 

particulate (PM10), NH3 and SO2. The baseline emissions inventory for 2002 was developed for 

North Carolina following the methods described in Appendix D. 

There are five different emission inventory source classifications: stationary point and area 

sources, off-road and on-road mobile sources, and biogenic sources. EPA‟s MOBILE6.2 and 

NONROAD2005 emissions models were used to develop the onroad and nonroad emissions and 

the Carnegie Mellon University ammonia models was used in the development of ammonia 

emissions. Stationary point sources are those sources that emit greater than a specified tonnage 

per year, with data provided at the facility level. Electric generating utilities and industrial 

sources are the major categories for stationary point sources. Stationary area sources are those 

sources whose individual emissions are relatively small, but due to the large number of these 

sources, the collective emissions from the source category could be significant (i.e., dry cleaners, 

service stations, agricultural sources, fire emissions, etc.). These types of emissions are estimated 

on a countywide level. Off-road (or non-road) mobile sources are equipment that can move but 

do not use the roadways, i.e., lawnmowers, construction equipment, railroad locomotives, 

aircraft, etc. The emissions from these sources, like stationary area sources, are estimated on a 

countywide level. On-road mobile sources are automobiles, trucks, and motorcycles that use the 

roadway system. The emissions from these sources are estimated by vehicle type and road type 

and are summed to the countywide level. Biogenic sources are the natural sources like trees, 

crops, grasses and natural decay of plants. The emissions from these sources are estimated on a 

countywide level. In addition to the various source classifications, there are also various types of 

emission inventories. The first is the actual base year inventory. This inventory is the base year 

emissions that correspond to the meteorological data used, which for this modeling effort is data 

from 2002. These emissions are used for evaluating the air quality model performance. The 

second type of inventory is the typical base year inventory. This inventory is similar to the actual 

base year inventory, except that for sources whose emissions change significantly from year to 

year, a more typical emission value is used. In this modeling effort, typical emissions were 

developed for the electric generating units (EGUs) and the wildland fire emissions. The air 

quality modeling is run using the typical base year inventory and the future year inventory. The 

results from these two runs are then used to calculate relative reduction factors. These relative 
84

reduction factors are used to estimate the future year visibility estimates that are used to 

demonstrate reasonable progress toward visibility goals. 

The North Carolina state emissions inventory data used in the modeling for 2002 and 2018 are 

presented in the following tables. Reductions related to the BART and reasonable progress 

analyses were not included in the photochemical grid modeling and are not represented in the 

tables. More detailed discussion of the emissions inventory development is contained in 

Appendices D and H.

Figures 41 and 42. North Carolina state emissions inventory data used in the modeling for 

2002 and 2018

NC SIP Narrative, Page 101:

All requirements listed in 51.308(g) shall be addressed in the SIP revision for reasonable

progress. In particular, the NCDAQ recognizes that the 2018 projections of EGU controls from

the IPM runs represent one solution to how the CAIR requirements will be met. By the time of the 

first periodic report, the NCDAQ anticipates that the actual compliance strategy for the various 

utility companies will be much more defined. An assessment of those actual compliance plans will 

be done for the first periodic report.

EPA Findings: EPA proposes to find that North Carolina has adequately addressed this 

provision.
85

IV. Conclusion

EPA is proposing a limited approval of a revision to the North Carolina SIP submitted by the 

State of North Carolina on December 17, 2007, as meeting some of the applicable regional haze 

requirements as set forth in sections 169A and 169B of the CAA and in 40 CFR 51.300-308, as 

described previously in this action.