Appendix S.1 Attainment TestTABLE OF CONTENTS

I. Attainment Demonstration................................................................................................... .....................1

II. Modeled Attainment Test........................................................................................................ .............1 III. Additional Corroborative Analyses And Weight Of Evidence Determination......................................4


### A. Alternative DVF Calculation ................................................................................................ 4
B Air Quality Modeling Metrics................................................................................................ 7
C. Air Quality Modeling Results From Other Studies............................................................. 14
D. Air Quality Trends and Additional Reductions in Emissions............................................. 15

E. Local Measures not Modeled .............................................................................................. 17
F. Weight of Evidence Conclusions ........................................................................................ 19
IV Unmonitored Area Analysis .................................................................................................. ...............20LIST OF FIGURES

Figure L-1: Charts the number of days greater than 90 degree F versus the 4th highest 8-hour ozone value

for the Metr olina area......................................................................................................... ..................6
Figure L-2: Area for which the air quality metrics were applied............................................................... ..8
Figure L-3: Persistence and Se verity for the Metrolina Area. .................................................................. ...9
Figure L-4: Daily AQI count s for the Metr olina Area........................................................................... ....10
Figure L-5: Hourly AQI C ount for the Metrolina Area. .......................................................................... ..11
Figure L-6: Percent Occurrence of Daily Maximum Code Yellow and Code Orange Grid Cells for the

Metrolina Area. ................................................................................................................ ..................12
Figure L-7: Percent Occurrence of Hourly Maximum Code Yellow and Code Orange Grid Cells for the

Metrolina Area. ................................................................................................................ ..................13
Figure L-8: Location and size of the Duke Energy facilities located in the vicinity of the Metrolina

nonattainment area. ............................................................................................................ ................16
Figure L-9: Ozone Monitors a nd 2009 Modeled Spatial Field ..................................................................21
Figure L-10: Ozone Monitors a nd 2012 Modeled Spatial Field ................................................................21

### LIST OF TABLES

Table L-1: USEPA’s Recommendati on for Defining “Nearby” Cells.........................................................2

Table L-2: Metrolina Attainment Test Results for 2009......................................................................... .....3

Table L-3: Metrolina Attainment Test Results for 2011......................................................................... .....4
Table L-4: Five-Year Average Alternativ e Attainment Test Results for 2009............................................5
Table L-5: Five-Year Average Alternativ e Attainment Test Results for 2011............................................6
Table L-6: Total number of grid cells for the AQI Categories 2002 vs 2009............................................14
Table L-7: Total number of grid cells for the AQI Categories 2002 vs 2011............................................14

Table L-8: Metrolina DVF s based on EAC Modeling............................................................................... 14

Table L-9: Metrolina DVFs based on the USEPA’s CAIR Modeling.......................................................15
Table L-10: Design Values (ppb) for the North Carolina Monitors in the Metrolina Area.......................15
Table L-11: Utility NOx Emission Reductions since 2006 Ozone Season................................................161 ATTAINMENT 

### TEST

I. Attainment Demonstration

This Appendix summarizes the procedures that were used to demonstrate attainment of the 8-hour ozone NAAQS in this SIP package. The modeling exer cises for the 2011 attainment year were performed by the NCDAQ, with the results revi ewed in close collaboration with th e SCDHEC. As described in the USEPA’s April 2007 Final Guidance On The Use Of Models And Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze (“ Attainment Guidance ”), an attainment demonstration consists of: (a) analyses which estimate whether selected emissions reductions will result in ambient concentrations that meet the NAAQS, and (b) an identified set of control measures which will result in the required emissions reductio ns. The necessary emission reductions for both of these attainment demonstration components may be de termined by relying on results obtained with air quality models.

Section 3.0 of the Attainment Guidance recommends applying both a modeled attainment test and a subsequent screening test to the air quality mode ling results to determine if the 8-hour ozone NAAQS will be met. Additional technical or corroboratory analyses may also be used as part of a “weight of evidence” determination to supplement the mode led attainment test and to further support a demonstration of attainment of the NAAQS.

The modeled attainment test, additional corrobo rative analyses and weight of evidence, and unmonitored area analysis are described in further de tail in the remaining portions of this Appendix, detailing how the respective test or analysis was perfo rmed and applied to the a ttainment demonstration.

II. Modeled Attainment Test

The modeled attainment test is the practice of usi ng an air quality model to simulate baseline (i.e., current) and future air quality. For the 8-hour ozon e NAAQS, the baseline and future model estimates are used in a “relative” rather than “abso lute” sense. Specifically, the ratio of the air quality model’s future to baseline predictions is calculated at each ozone moni toring site. These monitoring site-specific ratios are called relative response factors (RRF). Future ozon e design values (DVF) are then estimated at each monitor by multiplying the monitor-specific baseline ozone design value (DVB) by the modeled relative response factor for each monitor. If the resulting pr edicted site-specific DVFs are < 82 parts per billion (ppb), a clear demonstration of predicted attain ment is shown. If the predicted DVFs are > 82 ppb and < 87 ppb, then a weight of evidence demonstration mu st be submitted that suppor ts a demonstration of attainment. For DVFs > 87ppb, the Attainment Guidance states that more qualitative results are less likely to support a conclusion differing from the outcome of the modeled attainment test. Equation L-1 presents the modeled attainment test, applied at monitoring site “x” as described in Section 4.0 of the Attainment Guidance

. Future Design Value Equation:

(DVF) = (RRF) x (DVB)

Where (DVB) = the baseline design value monitored at site “x,” ppb = the average (of the three) design value periods which include the baseline inventory year (i.e. the average of the 2000-2002, 2001-2003, and 2002-2004 design values periods for the 2002 baseline inventory year).2 (RRF) = the ratio of the future 8-hour dail y maximum concentration predicted “nearby” a monitor (averaged over each day of the epis ode) to the current 8-hour daily maximum concentration predicted “nearby” the monito r (averaged over each day of the episode).

(DVF) = the estimated future design value, ppb.

It is important to consider an array of cells “near by” a monitor rather than focusing on the individual cell containing the monitor. This allows for varia tions in the model performance where the peak ozone may not occur in the grid cell that contains the monito r but rather nearby the monitor. Table L-1 provides the USEPA’s recommendations for defining “nearby” cells for grid systems having cells of various sizes. Since the attainment demonstration modeling was perform ed using a 12-kilometer grid resolution, the size of the array for “nearby” cells was 3 x 3.

Table L-1: USEPA’s Recommendati on for Defining “Nearby” Cells
Size of Cell (km) Size of the Array of “Nearby” Cells

< 5 7 x 7 >5-8 5 x 5 >8-15 3 x 3 >15 1 x 1

The RRF is calculated by taking the ratio of the mean future year modeling 8-hour ozone daily maximum to the mean baseline year modeling 8- hour ozone daily maximum “near” the monitor.

Relative Response Factor Equation:

RRF = mean future yr. 8-hr daily max “near” monitor “x” mean baseline yr. 8-hr daily max “near” monitor “x”

Section 14.1.1 of USEPA’s Attainment Guidance outlines the process for determining which days are used in the RRF calculation. The day selection process starts by identifying all the days in the baseline modeling that has a modeled daily maximum 8-hour average ozone equal to or greater than 85 ppb. If there are 10 or more days greater than 85 ppb, then 85 ppb is used as the cutoff in the RRF calculation. If there are fewer than 10 days with a modeled daily maximum 8-hour average ozone equal to or greater than 85 ppb, then the threshold is re duced by 1 ppb until there are at least 10 days identified for use. If there are fewer than 10 days with a m odeled daily maximum 8-hour average ozone equal to or greater than 70 ppb, then all days at 70 ppb and high er are used in the RRF calculation and consideration of modeling another episode should be explored.

The DVB, for purposes of the modeled attainment test, is defined in the Attainment Guidance by one of four methods:

1. The design value period (i.e. the average 4th highest value for the 3-year period used to designate an area “nonattainment,” for this nonattainment designation, the period from 2001 to 2003);3 2. The average 4th highest value for the 3-yr period straddling the baseline inventory year (e.g., the 2001-2003 design value period for the 2002 baseline inventory year);

3. The highest of the three design value periods whic h include the baseline inventory year (e.g., the 2000-2002, 2001-2003, 2002-2004 design value periods for a 2 002 baseline inventory year); and

4. The average of the three design value periods whic h straddle the baseline inventory year (e.g., the average of the 2000-2002, 2001- 2003, and 2002-2004 design valu e periods for a 2002 baseline inventory year).

The USEPA recommends the fourth method (average of the three design value periods straddling the baseline year), which is the DVB shown in Table 2-2 and Table 2-3 at each ozone monitoring site in the Metrolina region.

As mentioned earlier in this document, the mandate d attainment date for the Metrolina nonattainment area is June 15, 2010, which requires the 1997 8-hour ozone standard to be attained by the end of 2009. Since the NCDAQ and the SCDHEC believe that it may be necessary to request two one-year extensions of the attainment date, the expected attainment y ear is 2011. The results for both years have been calculated. Table L-2 lists the attainment test re sults for 2009 by monitor in the Metrolina area. Similarly, Table L-3 lists the attainment test results for 2011. In both tables, the first column is the monitoring site, then the county of the monitoring s ite’s location, followed by the DVB used for the attainment test. The next series of columns are th e number of days used in the calculation, the ozone level threshold needed to reach at least 10 days for RRF, the calculated RRF, and finally the resulting DVF for the 2009 and 2011 attainment years, respectiv ely. The bold italicized DVFs are values that fall within the range where additional weight of evidence is needed to demonstrate attainment. Based on the 2009 modeling, half of the monitors in the Metrolina nonattainment area have pr edicted DVFs that fall below 82 ppb and the other half fall between 82 ppb and 87 ppb. By 2011, only two of the monitors are predicted to have DVFs that fall between 82 ppb and 87 ppb with the ot her six sites falling below 82 ppb. With either the 2009 or the 2011 modeling predictions , additional weight of evidence is required to demonstrate attainment. The NCDAQ and the SCDHEC believe that the weight of evidence presented in Section 3 fully supports a de monstration of attainment.

Table L-2: Metrolina Attainment Test Results for 2009

Monitoring Site County DVB (ppb) Number of Days used in RRF Ozone Threshold (ppb) RRF DVF (ppb)
Arrowood Mecklenburg 84.7 18 85 0.883 74 County Line Mecklenburg 97.3 12 85 0.875 85 Crouse Lincoln 90.7 10 84 0.867 78 Enochville Rowan 97.0 12 85 0.870 84 Garinger (Plaza) Mecklenburg 95.3 20 85 0.888 84 Monroe Union 87.0 11 79 0.884 76 Rockwell Rowan 97.3 12 83 0.861 83 York York, SC 83.0 10 82 0.861 714 Table L-3: Metrolina Attainment Test Results for 2011

Monitoring Site County DVB (ppb) Number of Days used in RRF Ozone Threshold (ppb) RRF DVF (ppb)
Arrowood Mecklenburg 84.7 15 85 0.854 72 County Line Mecklenburg 97.3 12 85 0.846 82 Crouse Lincoln 90.7 10 83 0.829 75 Enochville Rowan 97.0 13 85 0.837 81 Garinger (Plaza) Mecklenburg 95.3 20 85 0.862 82 Monroe Union 87.0 12 78 0.858 74 Rockwell Rowan 97.3 10 83 0.837 81 York York, SC 83.0 13 81 0.841 69

III. Additional Corroborative Analyses And Weight Of Evidence Determination

As part of the weight of evidence determina tion, the following analyses will be evaluated:

• Alternative DVFs calculations,

• Metrics of air quality modeling results,

• Air quality modeling results from other studies,

• Observed air quality trends and a dditional reductions in emissions, and

• Local measures not modeled.

The weight of evidence determination is a supplem ent to the modeled attainment test and further supports that the area will attain the NAAQS for 8-hour ozone by the attainment date. Based on the air quality measurements for 2007 through 2009, a monitor in the Metrolina nonattai nment area has a design value above the 1997 8-hour ozone standard. However, the Metrolina area does have clean data for 2009 and meets the requirements to request a one-year extens ion of the attainment date. Since the ambient air quality measurements for 2008 were high, the NCDAQ believes that it may be necessary to request a second one-year extension of the attainment date.

A. Alternative DVF Calculation

The NCDAQ used the USEPA recommended met hod of calculating the DVB in its modeled attainment test. However, the NCDAQ has commented several times on various draft versions of the attainment guidance that they do not believe that a weighted DVB is appropriate and that a DVB calculated using a straight average minimizes the impacts of any abnormally hot/dry or cool/wet meteorological conditions. As part of the weight of evidence demonstration, the NCDAQ proposes an alternative method to calculate the DVB and presents the modeled attainment test results with this alternative DVB.5 The USEPA recommends calculating the DVB by averaging the three design value periods that straddle the baseline inventory year. This methodology results in a center weighting of annual 4 th highest ozone concentrations around the baseline inventory year because the three design value periods averaged contain overlapping data. The simplified recommen ded DVB calculation for this SIP modeling exercise is shown below.

Recommended Baseline Design Value Equation:

1*(2000 4 th Highest) + 2*(2001 4 th Highest) + 3*(2002 4 th Highest) DVB = + 2*(2003 4 th Highest) + 1*(2004 4 th Highest) 9

The weighting scheme of annual 4 th highest ozone concentrations in the recommended DVB calculation weights the center, or third, year three times more than that of the first or last year and one and half times more than that of the second or forth year. If this third year is an abnormally hot/dry or cool/wet period, the unusual me teorological conditions and resulti ng air quality conditions will be amplified upward or downward in th e modeled attainment exercise.

To minimize potential impacts of any abnormal me teorological conditions while still considering ozone conditions across a five-year span, an alternativ e DVB calculation that does not weight any of the years more than another, but is a straight average of annual 4 th highest ozone concentrations for the fiveyear span centered on the baseline inventory year was considered.

Recommended Baseline Design Value Equation:

2000 4 th Highest + 2001 4 th Highest + 2002 4 th Highest DVB = 2003 4 th Highest + 2004 4 th Highest 5

The results of applying the five-year straight average DVB to the remainder of the Modeled Attainment Test equations, at each monitoring site in the Metrolina region are shown in Table L-4 and Table L-5.

Table L-4: Five-Year Average Alternative Attainment Test Results for 2009

Monitoring Site County DVB 5-Year Straight Average 2000-2004 (ppb) RRF DVF (ppb)

Arrowood Mecklenburg 83.4 0.883 73 County Line Mecklenburg 95.6 0.875 83 Crouse Lincoln 89.2 0.867 77 Enochville Rowan 94.4 0.870 82 Garinger (Plaza) Mecklenburg 93.8 0.888 83 Monroe Union 84.6 0.884 74 Rockwell Rowan 94.6 0.861 81 York York, SC 79.8 0.861 686 Table L-5: Five-Year Average Alternative Attainment Test Results for 2011

Monitoring Site County DVB 5-Year Straight Average 2000-2004 (ppb) RRF DVF (ppb)

Arrowood Mecklenburg 83.4 0.854 71 County Line Mecklenburg 95.6 0.846 80 Crouse Lincoln 89.2 0.829 73 Enochville Rowan 94.4 0.837 79 Garinger (Plaza) Mecklenburg 93.8 0.862 80 Monroe Union 84.6 0.858 72 Rockwell Rowan 94.6 0.837 79 York York, SC 79.8 0.841 67

In comparison to the respective DVF values found in Table L-2 and Table L-3, the DVF values in Table L-4 and Table L-5 are slightly lower at each monitoring site. These differences were expected, as 2002 was an abnormally hot and dry year throughout the Southeast with ozone concentrations that were higher than in the surrounding years of 2000, 2001, 2003 , and 2004. Figure L-1 below illustrates this by charting the number of days with temperatures greater than 90 degrees F versus the maximum fourth highest 8-hour ozone value for the Metrolina area. Comparing 2002 to the surrounding years used in the DVB (2000, 2001, 2003 and 200 4), 2002 had significantly more days with greater than 90 degrees oF temperatures. Similarly, the maximum fourth high est 8-hour ozone value was approximately five ppb higher than the surrounding years used in the DVB.

0.080 0.085 0.090 0.095 0.100 0.105 0.110 0.115

0 10 20 30 40 50 60 70 80Max 4th Highest# Days Hi Temp≥90F May-Sep 

### Metrolina 8-hour Ozone - # Days Hi ≥ 90F vs Max 4th Highest

# Days Temperature >90F Max 4th Highest

Figure L-1: Charts the number of days greater than 90 degree F versus the 4th highest 8-hour ozone value for the Metrolina area.7 Thus, the recommended DVB calculation weighted the higher air quality conditions several times more than in the NCDAQ alternative DVB calcul ations. The NCDAQ firmly believes that the nonweighted or straight five-year average approach to the DVB calculation is more appropriate and minimizes dramatic fluctuations in meteorological and air quality conditions from year to year. This would be the case whether the center weighted year w as an abnormally hot/dry year or a cool/wet year.

While none of the monitoring sites in the Metro lina region had DVF values at or above 85 ppb in Table 3.1-1 or Table 3.1-2 using the NCDAQ alternativ e DVB calculation, there are still three monitors in Table 3.1-1 that have DVFs that fall between 82 ppb and 87 ppb. This continues to indicate that some additional weight of evidence should still be included to demonstrate attainment. These results are not inconsistent with what was concluded using all recommended modeled attainment test calculations.

B Air Quality Modeling Metrics

In Section 7.0 of the Attainment Guidance, various aspects of air quality models, modeled performance, and uncertainties associated with the length of modeled episodes and limited observational datasets are described. A series of three additional air quality modeling outputs or metrics is recommended to provide assurance the modeled demons tration indicates attainment. These metrics look at the relative change between the baseline and fu ture years modeling and help to demonstrate how widespread the improvement in air quality is expected to be in the future. Although the final guidance did not recommend percentage cut points that corresponds to supportive weight of evidence, an earlier draft version of the Attainment Guidance recommends that the metrics should be at least 80 percent or higher.

As described in Section 7.1 of the Attainment Guidance , the modeling data for the area displayed in Figure 5.2-1 from the 2002, 2009, and 2011 modeli ng were applied to the following metrics:

1. Relative change in surface grid-hours greater than 84 ppb . This metric is termed PersistenceHour and is defined as the number of grid-cells in a given region with predicted hourly 8- hour ozone concentrations greater than 84 ppb. The relative change in Persistence-Hour is presented as a percent reduction computed for the modeling period May through September from the baseline year case to the future year case.

2. Relative change in the number of grid cells w ith predicted 8-hour daily maxima greater than 84 ppb. This metric is termed Persistence-Daily metric and is similar to Persistence-Hour, but uses the modeled daily maximum 8-hour ozone concentrations greater than 84 ppb instead of the hourly 8-hour ozone concentrati ons. The relative change in Persistence-Daily is also presented as a percent reduction com puted for the modeling period May through September from the baseline year case to the future year case.

3. Relative change in the sum of hourly predictions greater than 84 ppb. This metric is termed Severity-Hour and is defined as the sum of a ll grid-cells with pred icted hourly 8-hour ozone concentrations greater than 84 ppb. Given the de finition of Persistence, this Severity could be considered as a weighted form of the Persis tence metric. The relative change in Severity is also presented as a percent reduction com puted for the modeling period May through September from the baseline year case to the future year case.

In addition to the three recommended metrics, two additional metrics were computed to create a comprehensive corroborative analysis. The two additional metrics are:8 4. Relative change in the sum of the pred icted 8-hour daily maxima greater than 84 ppb

. Severity-Daily metric is similar to Sever ity-Hour, but uses the modeled daily maximum 8- hour ozone concentrations greater than 84 ppb instead of the hourly 8-hour ozone concentrations. The relative change in Severity -Daily is also presented as a percent reduction computed for the modeling period May through September from the baseline year case to the future year case.

5. Air Quality Index (AQI) Counts. The AQI Counts metric is a count of the number of gridcells with predicted maximum 8-hour ozone con centrations sorted within each of the Code Green, Yellow, Orange and Red categories, as de fined by the USEPA’s AQI Index. As with the persistence and severity metrics, the AQI c ounts metric can be applied to both hourly and daily maximum 8-hour ozone concentrations. AQI Counts are presented as percentages of the total number of grid-cells within the study region.

The metrics described above were applied to the mode ling results for just of the nonattainment area. Below, Figure L-2 depicts the region for which this modeling data was extracted for the 2002 baseline and the 2009 and 2011 attain ment year modeling runs.

Figure L-2: Area for which the air quality metrics were applied.

The results from each of the five air quality m odeling metric calculations demonstrated significant reductions of greater than 85 percent in the 2009 future year air quality modeling and greater than 90 percent in the 2011 future year air quality modeling for days that modeled above the NAAQS in the Metrolina nonattainment area. Each metric demons trated very large relative reductions for 2009 and demonstrated more substantial reductions for 2011. It is important to note that the relative reductions in all metrics well surpassed the draft version of the Attainment Guidance recommendation of 80 percent for these particular calculations.

It should be noted that a minor alteration in the sp atial distribution of the emissions inventory in the 2011 air quality modeling required a rerun of the air quality model for the 2002 baseline year to appropriately calculate the 2011 based RRFs without introducing any modeling bias due to the minor emissions inventory spatial distributi on alteration. So, there are subtle differences in the hourly and daily grid cell counts for 2002.

Figure L-3 presents the relative reductions calculated in the first four metrics described above. The left two bars are the Persistence-Hour and Persiste nce-Daily reductions, and the right two bars are the9 Severity-Hour and Severity-Daily reductions. The 2009 modeling r esults demonstrate a 90.0 percent reduction in persistence of hourly maximum ozone a nd 86.4 percent reduction in persistence of daily maximum ozone. The severity reductions for 2009 are on a similar scale of 90.3 percent and 86.9 percent reduction for hourly and daily maximum ozone, respec tively. The 2011 modeling results demonstrate a 97.4 percent reduction in persistence of hourly maxi mum ozone and 95.9 percent reduction in persistence of daily maximum ozone. The sever ity reductions for 2011 are equally on a similar scale of 97.5 percent and 96.1 percent reduction for hourly and daily maximum ozone, respectively.

60 65 70 75 80 85 90 95 100

Persistance Severity% Reduction 

### % Reduction in Persistance (# Grid Cells) and Severity (Sum C ij_85 

### ) of Hourly & Daily Max O 3 

### 2002 vs 2009

Hourly Daily

60 65 70 75 80 85 90 95 100

Persistance Severity% Reduction 

### % Reduction in Persistance (# Grid Cells) and Severity (Sum C ij_85 

### ) of Hourly & Daily Max O 3 

### 2002 vs 2011

Hourly Daily

Figure L-3: Persistence and Severity for the Metrolina Area.10 Equating the 86.4 percent relative reduction in the daily maximum ozone persistence to AQI Counts, the top portion of Figure L-4 demonstrates a drop from 339 grid cells in the Code Orange and Red levels in the 2002 baseline modeling to 46 grid cells in th e 2009 future modeling. Furthermore, the number of grid cells in the Code Yellow a nd above (>65 ppb) range is reduced by 51.9 percent from 3,600 grid cells in 2002 to 1,733 grid cells in 2009. When the 2011 future year modeling is considered in the bottom portion of Figure 3.2-3, the 95.9 percent relative reduction in the daily ma ximum ozone persistence translates into a drop from 317 grids cells in the Code Orange and Red levels in 2002 to only 13 grid cells in 2011. Additionally, the number of grid cells Code Yellow and greater is reduced by 65.0 percent from 3,503 grid cells in 2002 to 1,227 grid cells in 2011.

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Daily 2002 Daily 2009% Grid Cells in Region 

### Daily 8-hr AQI Counts (2002 vs 2009)

Orange

Yellow
Green

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Daily 2002 Daily 2011% Grid Cells in Region 

### Daily 8-hr AQI Counts (2002 vs 2011)

Orange
Yellow
Green

Figure L-4: Daily AQI counts for the Metrolina Area.11 The hourly AQI Counts are equally encouraging. For 2009, Figure L-5 (top) displays the 90.0 percent relative reduction in hourly pe rsistence in terms of the AQI count s. It corresponds to a reduction from 1,315 hourly grid cells in the Code Orange a nd Red levels in the base line modeling to only 131 hourly grid cells in the 2009 future year modeling. Looking at all hourly grid cells Code Yellow andgreater, the count is reduced from 24,230 to 8,959, which translates to a 63.0 percent reduction. Figure L5 (bottom) presents the 97.4 percent relative reduction in hourly persistence in terms of the AQI counts for 2011. This reduction translates to a reduction fr om 1,195 hourly grid cells in the Code Orange and Red levels in 2002 to only 31 hourly grid cells in 2011. The reduction in hourly grid cell Code Yellow and greater is equally impressive with a reduction fro m 23,336 to 5,874. This is a 74.8 percent reduction from 2002 to 2011.

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Hourly 2002 Hourly 2009% Grid Cells in Region 

### Hourly 8-hr AQI Counts (2002 vs 2009)

Orange
Yellow
Green

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Hourly 2002 Hourly 2011% Grid Cells in Region 

### Hourly 8-hr AQI Counts (2002 vs 2011)

Orange
Yellow
Green

Figure L-5: Hourly AQI Count for the Metrolina Area.12 The tremendous improvements in air quality from th e 2002 baseline year to the 2009 and 2011 future years can further be illustrated by looking at just the percentage of occurrence of the Code Yellow and Orange grid cells throughout the Metrolina area. Figures L-6 and L-7 present metric for 2009 (top) and 2011 (bottom) in terms of the daily and hourly percentage of occurrence, respectively.

0 5 10 15 20 25 30 35 40 45 50

Daily 2002 Daily 2009% Occurence in Region 

### % Occurence of Daily Max Yellow and Orange (2002 vs 2009)

Orange

Yellow

0 5 10 15 20 25 30 35 40 45 50

Daily 2002 Daily 2011% Occurence in Region 

### % Occurence of Daily Max Yellow and Orange (2002 vs 2011)

Orange

Yellow

Figure L-6: Percent Occurrence of Daily Maximum Code Yellow and Code Orange Grid Cells for the Metrolina Area.13 0 2 4 6 8 10 12 14

Hourly 2002 Hourly 2009% Occurence in Region 

### % Occurence of Hourly Max Yellow and Orange (2002 vs 2009)

Orange

Yellow

0 2 4 6 8 10 12 14

Hourly 2002 Hourly 2011% Occurence in Region 

### % Occurence of Hourly Max Yellow and Orange (2002 vs 2011)

Orange

Yellow

Figure L-7: Percent Occurrence of Hourly Maximum Code Yellow and Code Orange Grid Cells for the Metrolina Area.

Finally, all of the AQI grid cell counts displaye d in Tables L-4 through L-7 are summarized below. Table L-6 contains all of the grid cell counts for both the Hourly and Daily AQI Count analyses for the 2002 baseline and 2009 future year modeling. Similarl y, Table L-7 contains all of the grid cell counts for both the Hourly and Daily AQI Count analyses for the 2002 baseline and 2011 future year modeling.14 Table L-6: Total number of grid cells for the AQI Categories 2002 vs 2009.
Grid Cells Grid Cells Daily 2002 Daily 2009 Hourly 2002 Hourly 2009 Green 4304 6171 165466 180737 Yellow 3261 1687 22915 8828 Orange 339 46 1315 131 total 7904 7904 189696 189696

Table L-7: Total number of grid cells for the AQI Categories 2002 vs 2011. Daily 2002 Daily 2011 Hourly 2002 Hourly 2011 Green 4401 6677 166330 183822 Yellow 3186 1214 22171 5843 Orange 317 13 1195 31 total 7904 7904 189696 189696

C. Air Quality Modeling Results From Other Studies

Another recommended weight of evidence analysis is to review other air quality modeling results that included the Metrolina nonattainment area to determ ine how other modeling results compare to the attainment demonstration. There are two air quality modeling studies to which results are available for the Metrolina area.

The first is the EAC modeling that the NCDAQ perfo rmed for the EAC areas within North Carolina. Since the modeling domain for this analysis covere d the majority of North Carolina, including the Metrolina nonattainment area, the modeling results can be easily compared to the attainment demonstration. There are some differences between the two modeling exercises. One difference is that the EAC modeling was carried out on 4 episodes (one in 1995, two in 1996 and one in 1997) for a total of sixteen days. Another is the DVB is based on the higher of the 1999-2001 or 2001-2003 design values. Finally, the EAC modeling did not model 2009, bu t there are results for 2007 and 2012. Table L-8 displays the EAC modeling results for the Metro lina monitors for both of these future years.

Table L-8: Metrolina DVFs based on EAC Modeling
2007 2012 Monitoring Site County DVB (ppb) RRF DVF (ppb) RRF DVF (ppb) Arrowood Mecklenburg 092 0.891 82 0.848 78 County Line Mecklenburg 101 0.861 87 0.802 81 Crouse Lincoln 92 0.870 80 0.826 76 Enochville Rowan 99 0.879 87 0.818 81 Garinger (Plaza) Mecklenburg 98 0.888 87 0.816 80 Monroe Union 88 0.852 75 0.795 70 Rockwell Rowan 100 0.870 87 0.800 80

As can be seen from the EAC modeling, although th ere are still four monitors slightly above the 8- hour ozone standard in 2007, all of the monitors are well below the standard by 2012. It should be noted that for the Greensboro/Winston-Salem/High Point EAC area, the EAC attainment test results predicted the highest monitor in the area to be at 83 ppb in 2007 and the actual 2005-2007 design value for the area was 83 ppb.15 Another air quality modeling exercise that containe d results for the Metrolina nonattainment area is the USEPA’s modeling for CAIR. The Technical Support Document for the final CAIR, March 2005, provided modeling results with and without the impl ementation of the CAIR. Differences between the USEPA’s modeling and the attainment demonstration are: 1) the meteorology was for 2001, 2) the DVB was the weighted design values the 1999-2003 period, a nd 3) the modeling results were for 2010. These modeling results are listed in Table L-9.

Table L-9: Metrolina DVFs based on the USEPA’s CAIR Modeling DVF (ppb) County DVB (ppb) 2010 Base 2010 CAIR Lincoln 92.3 76.1 74.5 Mecklenburg 100.3 82.5 81.4 Rowan 99.7 81.3 80.1 Union 87.7 71.9 71.1 York, SC 83.3 70.0 68.5

The USEPA’s results were for the highest monito r in a county where more than one monitor is located. The USEPA’s modeling results predict that the Metrolina nonattainment area should be below the 8-hour ozone standard by 2010. Therefore, this modeling supports weight of evidence that the Metrolina area will attain the 8-hour ozone standard by 2011.

D. Air Quality Trends and Additional Reductions in Emissions

Since the 8-hour ozone designation for the Metro lina area, the 8-hour ozone design values have improved significantly. The 2001-2003 design value period had values as high as 100 ppb and six out of the seven North Carolina monitors in the area were violating the NAAQS. Preliminary data indicates that for the latest design value period, 2007-2009, the highest violating monitor, the County-Line monitor in Mecklenburg County, will have a value of 86 ppb a nd only that monitor will exceed the NAAQS (See Table L-10).

Table L-10: Design Values (ppb) for the No rth Carolina Monitors in the Metrolina Area

Monitoring Site County 2001- 2003 2002- 2004 2003- 2005 2004- 2006 2005- 2007 2006- 2008 2007- 2009 Arrowood Mecklenburg 84 81 78 80 83 79 75 County Line Mecklenburg 98 92 87 88 93 94 86 Crouse Lincoln 92 86 81 79 83 82 76 Enochville Rowan 99 91 85 85 90 88 82 Garinger (Plaza) Mecklenburg 96 91 86 88 90 89 82 Monroe Union 88 85 79 78 81 80 76 Rockwell Rowan 100 94 88 83 89 88 83 York York, SC 84 81 75 76 79 77 71

The current ozone design values are very close to th e predicted attainment year design values. The reduction in design values since the area was desi gnated nonattainment is attributed to significant reductions in NO x emissions that have occurred. The emission reductions from the NO x SIP call occurred between 2004 and 2007, the initial Phase I year for CAIR is 2009, and every year the mobile source fleet becomes cleaner and reduces the NO x emissions from the highway and o ff-road mobile source sectors.16 All of these reductions have contributed to the improve ment of the design values. In fact, the air quality measurements for 2009 exhibit clean data, i.e. the four th highest value at each monitor is below the 1997 8-hour ozone standard.

Continued reductions of emissions from the mobile source sector and the utility sector will influence the ozone formation in this region. The NCDAQ has estimated that there will be approximately 7.6 tons per day of NO x emissions reduced each year from the highw ay and off-road mobile sectors. These reductions are the result of federal motor vehicle and equipment engine standards for both highway vehicles and off-road equipment, respectively.

Figure L-8: Location and size of the Duke Energy fa cilities located in the vicinity of the Metrolina nonattainment area.

Additionally, the overall background levels of ozone are expected to decrease as the utilities in the eastern United States put on additional controls to meet CAIR as well as the reduction in emissions of highway and off-road mobile sources throughout the country. For North Carolina, 2009 is the final compliance year for the NO x emission caps for the Clean Smokestacks Act. Figure L-8 displays the location and size of the Duke Energy facilities located in the vicinity of the Metrolina nonattainment area. Table L-11 lists the units that are in and around th e Metrolina area and shows the year the controls recently came on line and the estimated amount of NO X emissions reductions for the ozone season.

Table L-11: Utility NOx Emission Reductions since 2006 Ozone Season

Facility County Technology Operational Date Ozone Season Reductions (tons/season) Allen Steam Station Unit 2 Gaston SNCR Spring 2007 ~30017 Facility County Technology Operational Date Ozone Season Reductions (tons/season) Unit 3 SNCR Fall 2007 Buck Steam Station Units 3 & 4 Units 5 & 6 Rowan Low NOx Burners SNCR Spring 2007 Fall 2006 ~350

Riverbend Unit 4 Unit 5 Unit 6 Unit 7 Gaston SNCR SNCR & Burners SNCR & Burners SNCR Spring 2007 Spring 2007 Fall 2006 Fall 2006 ~325

Marshall Steam Station Unit 2 Unit 3 Unit 4 Catawba SNCR SCR SNCR Spring 2007 Fall 2008 Fall 2006 ~2,300

Total expected reduction = 3,275 tons/ozone season SNCR = Selective Non-Catalytic Reduction SCR = Selective Catalytic Reduction

The combination of the highway and off-road mobile sources and utility NO x emission reductions that occurred in the Metrolina area between the end of the 2006 ozone season and before the beginning of the attainment year 2009 was significant. The additional NO x emission reductions in the area that resulted in the Metrolina area having clean data for 2009, which will allow the State to request a one-year extension of the attainment date.

E. Local Measures not Modeled

As discussed in Section I of the attainment de monstration narrative, the Metrolina nonattainment area is a NO x limited area and the largest sources of NO x emissions in this region come from mobile sources (highway and off-road) and electric generating facilities. A significant source of NO x emission reductions that has not been included in the 2009 mode ling is the addition of a SCR unit at Marshall Unit 3. When the modeling was started, Duke Ener gy had installed a SNCR unit at Marshall Unit 3. However, since the expected 2009 Duke Energy system-wide NO x emissions is very close to the Clean Smokestack Act annual budget for this company, Duke Energy has announced that they plan to install a SCR unit in order to provide a safety margin in meeting the Clean Smokestack Act NO x budget. As can be seen in Figure L-8 in the previous section, the Ma rshall Steam Station is loca ted north of and adjacent to the Metrolina nonattainment area. The additional NO x emission reductions expected at this facility caused an impact on the ozone formation in the Metr olina area on days when the winds are coming from the North/Northwest and on days when there is reci rculation occurring. This SCR unit was installed in the Fall of 2008 and was operational at the beginning of 2009. The unit was modeled with the expected emissions reductions for the 2011 attainment year. A copy of the 2009 compliance plan for Duke Energy documenting the installation of the SCR at Marshall Un it 3 can be found in Appendix M. In addition to the Marshall NO x emission reductions, the Metrolina area has a number of groups that work towards decreasing emissions. These measures are voluntary measures that, although they may not account for large emission reductions, are directionally correct. A few of the known measures that are under way in the Metrolina area are listed below.18 • I-77 HOV lane in Mecklenburg County. A recent evaluation of the HOV lanes on I-77 through Charlotte, North Carolina reported that there h as been an observed increase of use of the HOV lanes since it has opened. It was reported that in November 2005, “...the HOV lane carried nearly 50 percent of the average number of persons who are traveling in a general-purpose lane in the morning peak hour, but in less than 20 percent of the number of vehicles.” Additionally, the “Average daily patronage on the CATS [Charlotte Area Transit System] express routes using the I-77 HOV facility increased by 63 percent between October 2004 and 2005 ...”. This reduction of vehicle miles traveled in this area was not modeled in the attainment demonstration. Having more people carpooling or using the transit sy stem in Mecklenburg will reduce both VOC and NOx emissions. A copy of the North Caro lina Department of Transportation (NCDOT) evaluation of the I-77 HOV lane can be found at the end of this Appendix.

• Truck Stop Electrification in Rowan County. In 2006, 50 spaces at a truck stop in Rowan County were converted with Idle Aire technology. This technology provides truckers with electricity and air conditioning, allowing the truckers to turn off th eir engines while they rest. This results in a reduction of both NO x and VOC emissions.

• Express Bus Route (Cabarrus/Rowan Counties). A new connecting service was created between Rider and Salisbury Transit. This provided an express route be tween Kannapolis and Salisbury. Having an express route between these two c ities reduces the number of personal cars on the roadways, which in turn will reduce VOC and NO x emissions. This new express route became operational in April 2009.

• Express Bus Route (York/Mecklenburg Counties). CATS has offered an Express Bus Route between Rock Hill and Charlotte since 2001 . Additional service was added in 2008.

• Pedestrian walkways and Bikeways Projects: A number of the communities are creating walkways and bikeways in order to provide safe pa thways for pedestrians and bicyclists to move about busy traffic areas. These types of projects provide safe alternatives to driving in the city.

• Idle Reduction Policies. North Carolina Department of Public Instruction has issued a policy that all school bus drivers are to refrain from idling their buses while waiting to pick up children at the school as well as when the buses are at the trans portation yard. Additionally, several cities and businesses have issued idle reduction policies for their fleet vehicles. This reduces VOC and NO x emissions as well as fine particulate matter. Some of the partners passing idle reduction policies include: Town of Concord, City of Salisbury, and Duke Power.



### • South Carolina’s Breathe Better (B 2 ) Anti-Idling Program for Schools. Several elementary schools in the Rock Hill area started the B 2 program during the 2008-2009 school year



### .

• Biodiesel use. A number of cities, counties and businesses have started using biodiesel for their diesel fleet. Most often B-20 is being used. B-20 will reduce VOC emissions as well as fine particulate matter. Some of the partners us ing biodiesel include: Gaston County Landfill, Town of Matthews, City of Monroe, Union County, NCDOT, and Duke Power.

• Diesel Retrofits. A number of cities, counties and school districts have installed Diesel Oxidation Catalysts (DOCs) or Diesel Particulate Filters (DPFs) on their diesel equipment. The vehicles that have been retrofitted include schools buses, as well as county fleet trucks for solid waste pickup. Although these types of filters are designed to remove fine particulate matter, when used with ultra low sulfur diesel fuel, NO x and VOC emissions are also reduced. Some of the partners installing DOCs and/or DPFs include: Cabarrus C ounty Schools, Gaston County Schools, Iredell County Schools, Lincoln County Schools, Meck lenburg County Schools, Rowan County Schools, Salisbury Public Schools, City of Charlotte and Mecklenburg County.19 • Grants to Replace Aging Diesel Engines (GRADE). Mecklenburg County Air Quality has developed this incentive program to reduce air pollution from off-road construction equipment. GRADE provides incentive funding to owners of o ffroad construction equipment such as loaders, graders, bull dozers etc., who are willing to replace their aging equipment with newer less polluting technology.

• Grants to Replace Aging Diesel Engines Plus (GRADE+). Mecklenburg County Air Quality received a grant under the American Recovery and Reinvestment Act to expand the GRADE program to include 13 North and South Carolina C ounties and also cover on-road and stationary diesel engines.

• Diesel Emissions Reduction Act (DERA). DERA provides new diesel emissions reduction grant authority for EPA. This funding is used to achieve significant reductions in diesel emissions that improve air quality and protect public health. In response to DERA, EPA created grant and funding programs under the National Clean Dies el Campaign (NCDC) to build on the success of its regulatory and voluntary efforts to reduce emissi ons from diesel engines. Through this effort, EPA is working to reduce the pollution emitted fro m the existing fleet by promoting a variety of cost-effective and innovative emission reduction strategies.

• North Carolina Heavy-Duty Vehicle Idling Restrictions. The North Carolina Environmental Management Commission adopted a rule to reduce unnecessary idling of heavy-duty trucks on July 9, 2009. If no appeal is made for legislativ e review, the rule is schedule to become effective on September 1, 2009. This rule generally prevents any person who operates a heavy-duty vehicle to cause, let, permit, suffer or allow idling for a period of time in excess of five consecutive minutes in any 60 minute period.

• Idling Restrictions for Commercial Diesel Vehicles. Section 56-35-10 of the Code of Laws of South Carolina, which became law in May 2008, stipulates that, barring certain exceptions, an operator of a commercial diesel vehicle may not a llow the vehicle to idle for more than ten minutes in any sixty-minute period.

F. Weight of Evidence Conclusions

The SCDHEC agrees with the NCDAQ that it is better to use a five-year straight average DVB in the attainment test since it will normalize the effects of meteorology on design values more so than a weighted DVB. Based on the alternative DVF cal culated in this section, all of the Metrolina nonattainment area monitors are predicted to be below the 8-hour ozone NAAQS in 2009 and 2011. Although the monitors still fall within the range for weight of evidence requirements in 2009, the monitor DVFs are lower than when a weighted DVB is used.

The air quality modeling metric analyses for the Me trolina nonattainment area demonstrates relative reductions well beyond the recommended 80 percent mark that is considered appropriate for concluding that a proposed strategy would meet the 8-hour ozone NAAQS. Additionally, other air quality modeling studies have found that the Metrolina area should a ttain the 8-hour ozone NAAQS on a similar schedule as the air quality modeling presented throughout this attainment demonstration.

The observed air quality trends in conjunction with further NO x emission reductions expected in the Metrolina area strengthens the argument that the attainment demonstration is an acceptable demonstration. Finally, given the variety of addition al emissions reductions that were not included in the development of this modeling exercise, but will o ccur throughout the surrounding areas, it is reasonable to conclude that the short lived even ts portrayed in the future modeled year by an extremely small number of remaining exceeding grid cells will be below the NAAQS in 2011.20 The SCDHEC and the NCDAQ agree that the weight of evidence provided in this section is strong evidence that the Metrolina nonattainment area will attain the 8-hour ozone NAAQS by 2011.

IV Unmonitored Area Analysis

The modeled attainment test does not address future air quality at locations where there is not an ozone monitor nearby. To guard against the possibility that air quality levels could exceed the standard in areas with limited monitoring, Section 3.4 of the Attainment Guidance suggests that additional review is necessary, particularly in nonattainment areas wher e the ozone monitoring network just meets or minimally exceeds the size of the network required. This review is intended to ensure that a control strategy leads to reductions in ozone at other locati ons that could have baseline (and future) design values exceeding the NAAQS were a monitor deployed there. The test is called an “unmonitored area analysis.”. The purpose of the analysis is to use a combination of model output and ambient data to identify areas that might exceed the NAAQS if monitors were located there.

SCDHEC currently operates a network of 18 oz one monitors. Ten of these monitors were established as State and Local Air Monitoring Stations (SLAMS). These SLAMS monitors were selected based on specific monitoring objectives (background con centration, area of highest concentration, high population, source impact, transport, and rural impact) as required by the USEPA and siting scales (micro, middle, neighborhood, urba n, and regional) established by the USEPA. Eight monitors are Special Purpose Monitors that were established by SCDHEC to obtain a better understanding of ozone in South Carolina.

The adequacy of the Metrolina area ozone monitori ng network is further demonstrated when plotted against a projected spatial field of 2009 and 2012 ozone design values. Figures L-9 and L-10 present the 2009 and 2012 future year ozone design value modeling output from the VISTAS/ASIP State Collaborative effort and the location of each ozone monitor in and around North Carolina. The 2009 and 2012 ozone design value spatial fiel ds were created using the USEPA ’s Modeled Attainment Test Software (MATS). It is clear from the MATS analysis that all of the regions of higher, yet attaining, ozone design values have numerous representative ozone monitors. There are no identified ozone hotspots that would require any additional monito ring considerations in the Metrolina area.21 Figure L-9: Ozone Monitors and 2009 Modeled Spatial Field

Figure L-10: Ozone Monitors and 2012 Modeled Spatial Field