# AVA NCDENR North Carolina Department of Environment and Natural Resources Pat McCrory

Governor

HeatherMcTeerToney Regional Administrator USEPA 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 SulfurDioxideBoundaryRecommendation for Brunswick County and NewHanoverCounty DearMs. Toney: Pursuant to the requirements ofthe federal Clean AirAct and onbehalfofGovernor Pat McCrory, I am submittingto 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 NewHanover Countythat attain ordo not attain the June 2, 2010, 1-hour National AmbientAir Quality Standard (NAAQS) for sulfur dioxide (S02). Our recommendation is inresponse to the EPA letter to the Department ofEnvironment and Natural Resources (DENR) that identified CPI Southport, Brunswick County as being subject to the Agency's next round ofdesignations based on a consent decree entered into the U.S. District Court for the Northern District ofCalifornia on March 2, 2015. I will reiterate North Carolina's position that ambient monitoring data should be the basis ofdesignations, and that modeling should not be relied onto designate areas as nonattainment. It should be noted that the modelshavebeen shown to over-predict ambient air quality concentrations. The Indiana Department ofEnvironmental Management, Office ofAir Quality recently completed a case study ofthe accuracy ofAmerican Meteorological Society/EPA Regulatory Model (AERMOD) regarding S02 concentrations when compared to actual monitoring data. The study concludedthat "Direct comparisons ofpredicted and observed S02 levels indicatethat AERMOD significantly over-predictsby more than a factor oftwo." The study is included as an attachment to the recommendationpackage. Despite the concerns regardingmodeling accuracy, and dueto the timeline requiredbythe consent decree, modeling information was considered alongwithmonitoring data from the New Hanover County site, and emissions data from the region to characterize air quality nearthe 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 paperHeather McTeerToney September 18, 2015 Page2 CPI Southport operates an electricpowergenerating station in Brunswick County. Air dispersion modeling analysis ofCPI Southport and two nearby facilities was performed according to EPA's guidance contained in the "S02NAAQS 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 occursjust 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 perbillion). Based onthis source specific air qualitymodeling, 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 ofCPI Southport. New Hanover Countyis located adjacent to Brunswick County. The S02 monitorin New Hanover County continues to measure S02 concentrations well below the 2010 1-hour S02 NAAQS. The 99thpercentile 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 of4 ppb for 2015. This dramatic decline in measured S02 concentrations at theNew Hanover County monitor is due to the retirement/closing ofthree S02 emitting sources (Sutton Steam Station, DAKAmericas and Southern States). Using EPA's "Updated Guidance for Area Designations for the 2010 Primary Sulfur Dioxide NAAQS," DENR has evaluated otherpermitted 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 ofS02 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 onthe collective review ofdispersion 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 ofthe 2010 S02 NAAQS, we are requesting township level designations. Development and submittal ofthe State's recommendations on appropriate boundaries are the first steps in the process ofaddressing the revised S02 NAAQS. We understand that ifthe EPA intends to designate areas that differ from the State's recommendations, the EPA is required to notify the Statebyno later than 120 days priorto the final designations. DENR recognizes the health impact ofS02. Historically, North Carolinahas demonstrated its commitment to clean air, and has taken proactive steps to ensure compliance with the NAAQS. All five ambient air quality monitors are measuringbelow the 2010 1-hour S02 NAAQS. The Statehas 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 ofour citizens, our environment, and our economy. Improving and maintaining air qualityis critical to the health ofour citizens, ourfuture growth, prosperity and quality oflife. We look forward to discussing these boundary recommendations with you. More detailed information and supporting data are included in the enclosed recommendationpackage.

SCH/ssm Enclosure

cc: The Honorable Pat McRory Ms. Sheila C. Holman Ms. Leslie Rhodes Mr. David Brigman Mr. Minor Barnette **--- B~tm**  **ma** R. van der Vaart, Secretary NCDENR

# State ofNorth Carolina's Recommendation on Boundaries Forthe 2010 1-Hour Sulfur Dioxide National Ambient Air Quality Standard

September 18, 2015 Governor Pat McCrory(This Page Is intentionallyBlank)

### Table of Contents Purpose............................................................................................................................................ 1 Background ..................................................................................................................................... 1 BoundaryRecommendations: 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 S02Modeling Attachment C: Indiana Department ofEnvironmental Management, Office ofAir Quality Study ofAERMOD Accuracy

North Carolina's 1-Hour S02 BoundaryRecommendations September 18, 2015

### Purpose
The purpose ofthis 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 onboundaries for New Hanover County, North Carolina which is located adjacent to Brunswick County

. 

### Background
OnJune 22, 2010, the United States Environmental Protection Agency (EPA) promulgated a new 1-hour standard of75 parts perbillion (ppb), measured as a three-year average ofthe 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 qualitymonitors in North Carolina were measuring attainment; butthe 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 ofCalifornia 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 ofthe 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 ofS02 and had an emission rate ofat least 0.45 lb S02/MMBtu in 2012 and that has not been announced (as ofMarch 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. DENRhas clearly stated its position that ambient monitoring data should bethe basis of designations, and that modeling should not berelied onto designate areas as nonattainment. 

### It should be noted that the models have been shown to overpredict ambient air quality concentrations. The Indiana Department ofEnvironmental Management, Office ofAir Quality

North Carolina's 1-Hour S02Boundary Recommendations September 18,2015 1recently completed a case study ofthe accuracy ofAmerican Meteorological Society/EPA Regulatory Model (AERMOD) regarding SOz concentrations when compared to actual monitoring data. The study concluded that "Direct comparisons ofpredicted and observed 

### SOz levels indicate that AERMOD significantly overpredicts bymore than a factor oftwo." The studyis included as Attachment C to the recommendationpackage. Despite the concerns regarding modeling accuracy, and due to the timeline requiredbythe consent decree, modeling information is considered along with monitoring data from theNew Hanover County site, and emissions data from the region to characterize air qualitynearthe CPI Southport facility. 

### Boundary Recommendations: Brunswick County and New Hanover County
DENR is recommending that all townships within Brunswick County and New Hanover County bedesignated attainment for the 2010 1-hour S02 NAAQS. In developing this recommendation, DENRutilized theEPA 's Updated GuidanceforAreaDesignations for the 2010PrimarySulfur DioxideNAAQS1
, and conducted an evaluation offive factors specified in the guidance. The results for each ofthe following five factors are discussedbelow: 1) ambient air quality data or dispersion modeling, 2) emissions related data, 3) meteorology, 4) geography and topography, and 5)jurisdictional boundaries. 

### 1. CPI SouthportDispersion Modeling The CPI Southport facility operates an electricpower generating station inBrunswick County (see Figure 1). Its 

### SOz emissions in2012 were 2,923 tons at an average emission rate of0.74lb SOz/MMBtu. Figure 1 illustrates the location ofCPI Southport and other permitted 

### SOz sources inthe vicinity ofBrunswick County. As shown in the figure, CPI Southport is the largest emitter ofSOz in the area. All remaining sources emit less than 100 tons per year. The closest SOz monitor is located in New Hanover County

.

1http://epa.gov/airquality/sulfurdioxide/pdfs/20150320S02designations.pdf North Carolina's 1-Hour S02 BoundaryRecommendations September 18, 2015 2Marion 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 ofCPI Southport was performedbyTrinity Consultants and submitted to DENR for review. Actual hourly SOz emissions from CPI Southport were included in the modeling for the 3-yearperiod from 2012-2014. SOz emission sources located at a nearby facility, Archer Daniels Midland (ADM) were also included inthe modeling. The modeling results show concentrations below the 1-hour SOz NAAQS and as such, the area around CPI Southport was shown to bein attainment ofthe 1-hour S02 NAAQS. DENRreviewed the dispersion modeling analysis submittedby 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 BoundaryRecommendations September 18, 2015 3DENR expanded the modeling submitted by CPI Southportbymaking three key changes to CPI Southport modeling: 1) used maximum 1-hour emissionrates for ADM sources, 2) added a small unpermitted source for ADM and 3) included an additional facility: Duke Energy Brunswick Nuclear Plant. The BrunswickNuclear 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 intermittentbasis during periods ofpower curtailment orwhen exercising emergency generators. DENR made a conservative assumption that S02 emissions occur every hour ofeach year overthe 3-yearmodeled period from 2012 through 2014. SeeAttachment 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 occursjustover500meters to the west ofCPI Southport. Adding the representative background concentration of7.9 J.Lg/m3
, obtained from the New Hanover County S02monitor, to the modeled impactresults 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 showninTable 1. 

### Table 1. Revised 

### 1-hour S02 Impactnear 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 ofthe High-4th-High DailyMax

. 1-hour concentration

. Based on this source specific air qualitymodeling, DENRis concluding that the area currently meets the S02 NAAQS, and no other sources cause or contribute to a NAAQS violation inthe vicinity ofCPI Southport.


### 2. AmbientAir QualityMonitoring Since the beginning of2011, theNew Hanover monitor has not observed an exceedance ofthe 2010 1-hour S02NAAQS. 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 Hanovermonitor. The most recent data for the New Hanover monitor shows a 99thpercentile concentration of4 ppb for 2015. The dramatic decline inmeasured S02 concentrations are due to the retirement/closing ofthree S02 emitting sources (Sutton Steam Station, DAKAmericas, and Southern States).

North Carolina's 1-Hour S02 BoundaryRecommendations September 18,2015 4Table 2. New Hanover Monitor S02 l\'lonitoring Data (2012

- 2014)
3-Year :Monitoring 99th Percentile Design Site ID Value 2012 2013 2014 (2012-2014) 37-129-0006 47ppb 45ppb 3 ppb 32ppb

3. Emissions Related Data The air qualitymodeling analysis discussed above addressed sources within the vicinity ofCPI Southport that wouldbe capable ofimpacting downwind S02concentrations. DENR also reviewed more distant sources, and concluded that thephysical distance (greater than 10 kilometers) and low emissions levels will notinterfere with the attainment of 1-hour so2 NAAQS. Table 3 shows 2013 emission rates for all otherpermitted sources operating in Brunswick and New Hanover counties. All sources emitted less than 100 tons per year ofS02 (see Figure 1). Since none ofthese 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 ofthe 1-hour S02NAAQS.

North Carolina's 1-Hour S02 BoundaryRecommendations September 18, 2015 5

### Table 3. Othernearby 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 notplaya role inthe dispersion characteristics at the select sites.


### 5. Jurisdictional Boundary TheEPA guidance requests clearly defined legal boundaries for carrying out the air quality planning and enforcement functions. Dueto the onehour averaging time ofthe 2010 S02 NAAQS, DENR is recommending that attainment designations for Brunswick County and New Hanover Countybe established at the township level as shown inTable 4.
North Carolina's 1-Hour S02 BoundaryRecommendations September 18, 2015 6Table 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 FearTownship Attainment Federal Point Township Attainment



### Conclusions
DENR's five factor analysis using the EPA guidance determined the following: 1. Air dispersion modeling ofCPI 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 ofCPI Southport.
2. The most recent SOz design value ofthe 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 significantlybelow the 2,000 tons per year threshold established in EPA's final Data Requirements Rule. Further characterization ofair quality around these smaller sources is not needed.

North Carolina's 1-Hour SOz BoundaryRecommendations September 18, 2015 7Looking at the totality ofthe 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 bedesignated attainment for the 2010 1-hour S02NAAQS.

North Carolina's 1-Hour S02 BoundaryRecommendations September 18, 2015 8