AVA 

NCDENR 

North Carolina Department of Environment and Natural Resources 

Pat McCrory 

Governor 

Heather McTeer Toney 

Regional Administrator 

USEP A Region 4 

Atlanta Federal Center 

61 Forsyth Street, SW 

Atlanta, GA 30303-8960 

September 18, 2015 

Donald R. van der Vaart 

Secretary 

Subject: 2010 1-Hour Sulfur Dioxide Boundary Recommendation for Brunswick County 

and New Hanover County 

Dear Ms. Toney: 

Pursuant to the requirements of the federal Clean Air Act and on behalf of Governor Pat 

McCrory, I am submitting to you and your colleagues at the U.S. Environmental Protection 

Agency (EPA), the State ofNorth Carolina's recommendation concerning the boundaries within 

Brunswick County and New Hanover County that attain or do not attain the June 2, 2010, 1-hour 

National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (S02). Our 

recommendation is in response to the EPA letter to the Department of Environment and Natural 

Resources (DENR) that identified CPI Southport, Brunswick County as being subject to the 

Agency's next round of designations based on a consent decree entered into the U.S. District 

Court for the Northern District of California on March 2, 2015. 

I will reiterate North Carolina's position that ambient monitoring data should be the basis 

of designations, and that modeling should not be relied on to designate areas as nonattainment. It 

should be noted that the models have been shown to over-predict ambient air quality 

concentrations. The Indiana Department of Environmental Management, Office of Air Quality 

recently completed a case study of the accuracy of American Meteorological Society/EPA 

Regulatory Model (AERMOD) regarding S02 concentrations when compared to actual 

monitoring data. The study concluded that "Direct comparisons of predicted and observed S02 

levels indicate that AERMOD significantly over-predicts by more than a factor of two." The 

study is included as an attachment to the recommendation package. Despite the concerns 

regarding modeling accuracy, and due to the timeline required by the consent decree, modeling 

information was considered along with monitoring data from the New Hanover County site, and 

emissions data from the region to characterize air quality near the CPI Southport facility. 

1641 Mail Service Center, Raleigh, North Carolina 27699-1641 

Phone: 919-707-8400\ Internet: www.ncdenr.gov 

An Equal Opportunity\ Affirmative Action Employer- Made in part by recycled paper 
Heather McTeer Toney 

September 18, 2015 

Page2 

CPI Southport operates an electric power generating station in Brunswick County. Air 

dispersion modeling analysis of CPI Southport and two nearby facilities was performed 

according to EPA's guidance contained in the "S02 NAAQS Designations Modeling Technical 

Assistance Document (TAD)." The modeling indicates a maximum 1-hour concentration impact 

(i.e. design concentration) level of 183.3 )lg/m3

, which occurs just over 500 meters to the west of 

CPI Southport. Adding the representative background concentration of7.9 )lg/m3, obtained from 

the New Hanover County S02 monitor, to the modeled impact level gives a maximum S02 

concentration of 191.2 )lg/m3, which is less than the 1-hour S02 NAAQS of 196.3 )lg/m3 (75 

parts per billion). Based on this source specific air quality modeling, DENR is concluding that 

the area currently meets the S02 NAAQS, and no other sources cause or contribute to a NAAQS 

violation in the vicinity of CPI Southport. 

New Hanover County is located adjacent to Brunswick County. The S02 monitor in New 

Hanover County continues to measure S02 concentrations well below the 2010 1-hour S02 

NAAQS. The 99th percentile concentration for 2014 was 3 ppb and the 3-year design value 

(2012 -2014) was 32 ppb. The most recent monitored data shows a 99th percentile concentration 

of 4 ppb for 2015. This dramatic decline in measured S02 concentrations at the New Hanover 

County monitor is due to the retirement/closing of three S02 emitting sources (Sutton Steam 

Station, DAK Americas and Southern States). 

Using EPA's "Updated Guidance for Area Designations for the 2010 Primary Sulfur 

Dioxide NAAQS," DENR has evaluated other permitted sources located in Brunswick and New 

Hanover Counties. All sources are located at sufficient distances that would limit contributions 

to S02 exceedances. Additionally, each source emitted less than 100 tons per year of S02 in 

2013, which is well below the 2,000 tons per year threshold specified in EPA's recently 

promulgated Data Requirements Rule. Subsequently, additional air quality assessments 

associated with these sources are not necessary. 

Based on the collective review of dispersion modeling results, air quality measurements 

data, emissions records, and other factors, DENR is concluding that all townships within 

Brunswick and New Hanover Counties be designated attainment for the 2010 1-hour S02 

NAAQS. Due to the short averaging time of the 2010 S02 NAAQS, we are requesting township 

level designations. Development and submittal of the State's recommendations on appropriate 

boundaries are the first steps in the process of addressing the revised S02 NAAQS. We 

understand that if the EPA intends to designate areas that differ from the State's 

recommendations, the EPA is required to notify the State by no later than 120 days prior to the 

final designations. 

DENR recognizes the health impact of S02. Historically, North Carolina has 

demonstrated its commitment to clean air, and has taken proactive steps to ensure compliance 

with the NAAQS. All five ambient air quality monitors are measuring below the 2010 1-hour 

S02 NAAQS. The State has and will continue to use its statutory authority to implement 

controls in the State as warranted. 
Heather McTeer Toney 

September 18,2015 

Page3 

North Carolina is committed to protecting the health of our citizens, our environment, 

and our economy. Improving and maintaining air quality is critical to the health of our citizens, 

our future growth, prosperity and quality of life. We look forward to discussing these boundary 

recommendations with you. More detailed information and supporting data are included in the 

enclosed recommendation package. 

SCH/ssm 

Enclosure 

cc: The Honorable Pat McRory 

Ms. Sheila C. Holman 

Ms. Leslie Rhodes 

Mr. David Brigman 

Mr. Minor Barnette 

---B~tmma R. van der Vaart, Secretary 

NCDENR 

State ofNorth Carolina's 

Recommendation on Boundaries 

For the 20 1 0 1-Hour Sulfur Dioxide 

National Ambient Air Quality Standard 

September 18, 2015 

Governor Pat McCrory 
(This Page Is intentionally Blank) 
Table of Contents 

Purpose ............................................................................................................................................ 1 

Background ..................................................................................................................................... 1 

Boundary Recommendations: Brunswick County and New Hanover County .............................. 2 

1. CPI Southport Dispersion Modeling ................................................................................ 2 

2. Ambient Air Quality Monitoring ..................................................................................... 4 

3. Emissions Related Data .................................................................................................... 5 

4. Meteorology, Topography and Geography ...................................................................... 6 

5. Jurisdictional Boundary .................................................................................................... 6 

Conclusions ..................................................................................................................................... 7 

Attachment A: CPI Southport S02 Modeling 

Attachment B: DAQ Revised S02 Modeling 

Attachment C: Indiana Department of Environmental Management, Office of Air Quality Study 

of AERMOD Accuracy 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18, 2015 
Purpose 

The purpose of this document is to provide the State ofNorth Carolina's recommendation on 

boundaries for the 2010 1-hour sulfur dioxide (S02) National Ambient Air Quality Standard 

(NAAQS) for the CPI Southport facility in Brunswick County, North Carolina. The document 

also provides recommendation on boundaries for New Hanover County, North Carolina which is 

located adjacent to Brunswick County. 

Background 

On June 22, 2010, the United States Environmental Protection Agency (EPA) promulgated a new 

1-hour standard of 75 parts per billion (ppb ), measured as a three-year average of the annual 99th 

percentile of 1-hour daily maximum concentrations ( 40 CFR 50.17). The EPA also revoked the 

primary annual and 24-hour S02 NAAQS. On August 5, 2013, the EPA promulgated 

nonattainment designations in 16 states where existing monitoring data from 2009-2011 

indicated violations ofthe 1-hour S02 standard (78 FR 47191). All five air quality monitors in 

North Carolina were measuring attainment; but the EPA indicated in its letter, dated February 6, 

2013, that it was deferring designations for North Carolina to a later date. 

On March 2, 2015, the U.S. District Court for the Northern District of California accepted a 

consent decree between the EPA and Sierra Club and Natural Resources Defense Council that 

specified a schedule for the EPA to complete the remaining designations for the rest of the 

country. Among several terms in the Consent Decree, the EPA is required to designate areas 

that contain any stationary sources that emitted more than 16,000 tons ofS02 in 2012 or emitted 

more than 2,600 tons of S02 and had an emission rate of at least 0.45 lb S02/MMBtu in 2012 

and that has not been announced (as of March 2, 2015) for retirement. 

On March 20,2015, the EPA notified the North Carolina Department ofEnvironment and 

Natural Resources (DENR) that CPI Southport in Brunswick County was identified as exceeding 

the criteria established in the Consent Decree. CPI Southport had 2012 SOz emissions level of 

2,923 tons at an average emission rate of0.74lb SOz/MMBtu. The EPA requested that DENR 

submit an updated recommendation and supporting information for the EPA to consider for the 

CPI Southport area by September 18, 2015. 

DENR has clearly stated its position that ambient monitoring data should be the basis of 

designations, and that modeling should not be relied on to designate areas as nonattainment. It 

should be noted that the models have been shown to over predict ambient air quality 

concentrations. The Indiana Department of Environmental Management, Office of Air Quality 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18,2015 

1 
recently completed a case study of the accuracy of American Meteorological Society/EPA 

Regulatory Model (AERMOD) regarding SOz concentrations when compared to actual 

monitoring data. The study concluded that "Direct comparisons of predicted and observed SOz 

levels indicate that AERMOD significantly over predicts by more than a factor of two." The 

study is included as Attachment C to the recommendation package. Despite the concerns 

regarding modeling accuracy, and due to the timeline required by the consent decree, modeling 

information is considered along with monitoring data from the New Hanover County site, and 

emissions data from the region to characterize air quality near the CPI Southport facility. 

Boundary Recommendations: Brunswick County and New Hanover County 

DENR is recommending that all townships within Brunswick County and New Hanover County 

be designated attainment for the 2010 1-hour S02 NAAQS. In developing this recommendation, 

DENR utilized the EPA 's Updated Guidance for Area Designations for the 2010 Primary Sulfur 

Dioxide NAAQS1

, and conducted an evaluation of five factors specified in the guidance. The 

results for each of the following five factors are discussed below: 1) ambient air quality data or 

dispersion modeling, 2) emissions related data, 3) meteorology, 4) geography and topography, 

and 5) jurisdictional boundaries. 

1. CPI Southport Dispersion Modeling 

The CPI Southport facility operates an electric power generating station in Brunswick County 

(see Figure 1). Its SOz emissions in 2012 were 2,923 tons at an average emission rate of0.74lb 

SOz/MMBtu. Figure 1 illustrates the location of CPI Southport and other permitted SOz sources 

in the vicinity of Brunswick County. As shown in the figure, CPI Southport is the largest emitter 

of SOz in the area. All remaining sources emit less than 100 tons per year. The closest SOz 

monitor is located in New Hanover County. 

1 http://epa.gov/airquality/sulfurdioxide/pdfs/20150320S02designations.pdf 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18, 2015 

2 
Marion 

G o 

Rob~son 88 

1 

Georgetown / 

s 

2013 502 Facility Emissions 

Q 

0 .(.() 

-=:::!l!lll=---t:::===---Milee 

5 10 20 30 

Legend 

l Met. Momtor 

S02 Monotoo 

502 Emissions (tpy) 

• <100 

0 100 ·999 

0 1000-2000 

• >2000 

Figure 1. Sources In and Around Brunswick and New Hanover Counties and their 2013 

Annual S02 Emissions 

Using guidance from the SOz NAAQS Designations Modeling Technical Assistance Document 

(TAD), source-specific air dispersion modeling of CPI Southport was performed by Trinity 

Consultants and submitted to DENR for review. Actual hourly SOz emissions from CPI 

Southport were included in the modeling for the 3-year period from 2012-2014. SOz emission 

sources located at a nearby facility, Archer Daniels Midland (ADM) were also included in the 

modeling. The modeling results show concentrations below the 1-hour SOz NAAQS and as 

such, the area around CPI Southport was shown to be in attainment of the 1-hour S02 NAAQS. 

DENR reviewed the dispersion modeling analysis submitted by CPI Southport and confirmed 

that the analysis was performed according to the TAD. See Attachment A for details regarding 

CPI Southport's dispersion modeling assumptions and results. 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18, 2015 

3 
DENR expanded the modeling submitted by CPI Southport by making three key changes to CPI 

Southport modeling: 1) used maximum 1-hour emission rates for ADM sources, 2) added a small 

unpermitted source for ADM and 3) included an additional facility: Duke Energy Brunswick 

Nuclear Plant. The Brunswick Nuclear Plant and ADM are each about a mile away from CPI 

Southport (see Figure 1) and are the closest substantial S02 emission sources in the vicinity of 

CPI Southport. S02 emissions from both facilities occur on an intermittent basis during periods 

of power curtailment or when exercising emergency generators. DENR made a conservative 

assumption that S02 emissions occur every hour of each year over the 3-year modeled period 

from 2012 through 2014. See Attachment B for details regarding DENR's modeling analysis. 

DENR's revised modeling indicates a maximum 1-hour concentration impact (i.e. design 

concentration) level of 183.3 J.Lg/m3, which occurs just over 500 meters to the west of CPI 

Southport. Adding the representative background concentration of 7.9 J.Lg/m3

, obtained from the 

New Hanover County S02 monitor, to the modeled impact results gives a maximum S02 

concentration of 191.2 J.Lg/m3

, which is less than the 1-hour S~ NAAQS of 196.3 J.Lg/m3 (75 

ppb ). This information is shown in Table 1. 

Table 1. Revised 1-hour S02 Impact near CPI Southport 

Maximum Background Total so2 %of 

Pollutant Averaging Concentration Concentration Concentration NAAQS so2 Period (J1glm3) (pglm3) (J1glm3) (pg/m3) NAAQS 

so2 1-hour 183.3* 7.9 191.2 196.3 97% 

* 3 year average of the High-4th-High Daily Max. 1-hour concentration. 

Based on this source specific air quality modeling, DENR is concluding that the area currently 

meets the S02 NAAQS, and no other sources cause or contribute to a NAAQS violation in the 

vicinity of CPI Southport. 

2. Ambient Air Quality Monitoring 

Since the beginning of2011, the New Hanover monitor has not observed an exceedance ofthe 

2010 1-hour S02 NAAQS. The 99th percentile concentration for 2014 was 3 ppb and the 3-year 

design value (2012 -2014) was 32 ppb. Table 2 shows the annual concentrations (99th percentile) 

recorded at the New Hanover monitor. The most recent data for the New Hanover monitor 

shows a 99th percentile concentration of 4 ppb for 2015. The dramatic decline in measured S02 

concentrations are due to the retirement/closing of three S02 emitting sources (Sutton Steam 

Station, DAK Americas, and Southern States). 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18,2015 

4 
Table 2. New Hanover Monitor S02 l\'lonitoring Data (2012 - 2014) 

3-Year 

:Monitoring 99th Percentile Design 

Site ID Value 

2012 2013 2014 (2012-2014) 

3 7-129-0006 47ppb 45ppb 3 ppb 32ppb 

3. Emissions Related Data 

The air quality modeling analysis discussed above addressed sources within the vicinity of CPI 

Southport that would be capable of impacting downwind S02 concentrations. DENR also 

reviewed more distant sources, and concluded that the physical distance (greater than 10 

kilometers) and low emissions levels will not interfere with the attainment of 1-hour so2 

NAAQS. Table 3 shows 2013 emission rates for all other permitted sources operating in 

Brunswick and New Hanover counties. All sources emitted less than 100 tons per year of S02 

(see Figure 1). Since none of these sources are above the 2,000 tons per year threshold specified 

in the EPA's recently finalized Data Requirements Rule, DENR is concluding that (1) further air 

quality assessment is not necessary, and (2) both Brunswick and Ne\v Hanover Counties and 

their townships are in attainment of the 1-hour S02 NAAQS. 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18, 2015 

5 
Table 3. Other nearby S02 Emission Sources in Brunswick and New Hanover Counties 

Facility Name 2013 Actual S02 Emissions 

(tons per year) 

Technical Coating International, Inc. 0.01 

Victaulic Company 0.01 

Wilmington Materials 0.01 

Louisiana-Pacific Corporation 0.01 

Bradley Creek Pump Station 0.01 

Sweeney Water Treatment Plant 0.02 

Axeon Specialty Products- Wilmington Terminal 0.03 

Hewletts Creek Pump Station 0.03 

Novant Health Brunswick Medical Center 0.04 

Apex Oil Company, Inc. 0.05 

Corning Incorporated 0.08 

McKean Maffitt WWTP (aka Southside) 0.08 

New Hanover Regional Medical Center 0.38 

Elementis Chromium 0.43 

Kinder Morgan, Wilmington 0.60 

lnvista, S.a.r.l. 0.67 

Carolina Pole Leland, Inc. 1.33 

James A Loughlin WWTP (aka Northside) 1.98 

Malmo Asphalt Plant 3.83 

S. T. Wooten Corporation 6.78 

Barnhill Contracting Company 7.20 

Fortran Industries LLC 40.59 

Wilbara, LLC 87.67 

Shutdown Facilities (not shown in Figure 1) 

OAK Americas LLC 1 '149.29 

Duke Energy Progress- LV. Sutton Electric Plant 12,131.69 

4. Meteorology, Topography and Geography 

Meteorology and geography were addressed in CPI Southport dispersion modeling. Attachments 

A and B provide additional information. Topography does not play a role in the dispersion 

characteristics at the select sites. 

5. Jurisdictional Boundary 

The EPA guidance requests clearly defined legal boundaries for carrying out the air quality 

planning and enforcement functions. Due to the one hour averaging time of the 2010 S02 

NAAQS, DENR is recommending that attainment designations for Brunswick County and New 

Hanover County be established at the township level as shown in Table 4. 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18, 2015 

6 
Table 4. North Carolina Recommendation for 1-Hour S02 Standard 

Brunswick County 

Lockwoods Folly Township Attainment 

Northwest Township Attainment 

Shallotte Township Attainment 

Smithville Township Attainment 

Town Creek Township Attainment 

Waccamaw Township Attainment -- ~ew Hanover County .. 

Grouped Townships 

Harnett Township Attainment 

Masonboro Township 

Wilmington ~ownshiE 

Individual Townships 

Cape Fear Township Attainment 

Federal Point Township Attainment 

Conclusions 

DENR's five factor analysis using the EPA guidance determined the following: 

1. Air dispersion modeling of CPI Southport and nearby sources demonstrate no violations of 

the 2010 1-hour SOz NAAQS. The modeling shows that the 75 ppb SOz standard will be met 

in the vicinity of CPI Southport. 

2. The most recent SOz design value of the New Hanover monitor is 32 ppb, which is well 

below the 75 ppb NAAQS. 

3. All remaining SOz sources in Brunswick County and New Hanover County emit less than 

100 tons per year, and are significantly below the 2,000 tons per year threshold established in 

EPA's final Data Requirements Rule. Further characterization of air quality around these 

smaller sources is not needed. 

North Carolina's 1-Hour SOz Boundary Recommendations 

September 18, 2015 

7 
Looking at the totality of the information, including the nearby ambient data, the emissions data 

and the modeling analysis, DENR is recommending that all townships within Brunswick and 

New Hanover Counties be designated attainment for the 2010 1-hour S02 NAAQS. 

North Carolina's 1-Hour S02 Boundary Recommendations 

September 18, 2015 

8