Appendix L

Attainment TestTABLE OF CONTENTS



### I. ATTAINMENT DEMONSTRATION.......................

**................................................... ............. 1** 

**II. MODELED ATTAINMENT TEST.......................**

**................................................... ................ 2** 

**II. ADDITIONAL CORROBORATIVE ANALYSES AND WEIGHT O F EVIDENCE**  **DETERMINATION ......................................**

**................................................... .............................. 4** 
**A. Alternative DVF Calculatation ..................**

**................................................... ........................ 4**  **B. Air Quality Modeling Metrics...................**

**................................................... ......................... 6**  **C. Air Quality Modeling Results From Other Studies**

**................................................... .......... 10**  **D. Air Quality Trends and Additional Reductions in Emissions.........................................**  **.... 12 E. Local Measures not Modeled .....................** 

**................................................... ...................... 14**  **F. Weight of Evidence Conclusions .................**

**................................................... .................... 16** 

**IV. UNMONITORED AREA ANALYSIS.....................**

**................................................... ......... 17** 
**ATTACHMENTS TO APPENDIX l..........................**

**................................................... ................19** LIST OF TABLES



### Table L-1: USEPA’s Recommendation for Defining “Ne **arby” Cells ........................................ .. 2**  **Table L-2: Metrolina Attainment Test Results for 2 009 ................................................**  **............... 3 Table L-3: Five-Year Average Alternative Attainmen**  **t Test Results for 2009 ............................ . 5**  **Table L-4: Total number of grid cells for the AQI Categories. ........................................**  **........... 10 Table L-5: Metrolina DVFs based on EAC Modeling...** 

**................................................... ........... 11**  **Table L-6: Metrolina DVFs based on the USEPA’s CAI R Modeling.........................................**  **11 Table L-7: Design Values (ppb) for the North Carol**  **ina Monitors in the Metrolina Area........... 12 Table L-8: Utility NO**  **x** 

### Emission Reductions since 2006 Ozone Season ....... **............................. 14**LIST OF FIGURES



### Figure L-1: Number of days greater than 90oF versu **s the 4 th**  

### highest 8-hour ozone value for the **Metrolina area. ....................................**

**................................................... ................................. 6**  **Figure L-2: Area for which the air quality metrics were applied. .....................................**  **............ 8 Figure L-3: Persistence and Severity for the Metro**  **lina Area .......................................... .............. 9**  **Figure L-4: Daily AQI counts for the Metrolina Are a..................................................**  **................. 9 Figure L-5: Hourly AQI Count for the Metrolina Are**  **a.................................................. ............. 10**  **Figure L-6: Location and size of the Duke Energy f acilities located in the vicinity of the**  **Metrolina nonattainment area. ......................**

**................................................... ..................... 13**  **Figure L-7: Ozone Monitors and with Respect to the VISTAS 12 km Grid ............................... 18** **1**

I. ATTAINMENT DEMONSTRATION

**This Appendix summarizes the procedures that were used to demonstrate attainment of the 8-hour**  **ozone National Ambient Air Quality Standard (NAAQS) in this State Implementation Plan (SIP)**  **package. As described in the US Environmental Prot ection Agency’s (USEPA’s) September 2006 draft**  **final Guidance On The Use Of Models And Other Analy ses for Demonstrating Attainment of Air Quality**  **Goals for Ozone, PM 2.5**  **, and Regional Haze (“**  Attainment Guidance **”), an attainment demonstration consists of (a) analyses which estimate whether sel**  **ected emissions reductions will result in ambient concentrations that meet the NAAQS, and (b) an iden**  **tified set of control measures which will result in the**  **required emissions reductions. The necessary emiss ion reductions for both of these attainment**  **demonstration components may be determined by relyi ng 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 modeled a ttainment test and to further support a**  **demonstration of attainment of the NAAQS.**

**The modeled attainment test, additional corroborat ive analyses and weight of evidence, and**  **unmonitored area analysis are described in further detail in the remaining portions of this Appendix,**  **detailing how the respective test or analysis was p erformed and applied to the attainment demonstratio**  **n. 2** 

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 oz one NAAQS, the baseline and future model estimates**  **are used in a “relative” rather than “absolute” sense.**  **Specifically, the ratio of the air quality model’s future to**  **baseline predictions is calculated at each ozone mo nitoring site. These monitoring site-specific rati**  **os are called relative response factors (RRF). Future ozo**  **ne design values (DVF) are then estimated at each monitor by multiplying the monitor-specific baselin**  **e ozone design value (DVB) by the modeled relative response factor for each monitor. If the resulting**  **predicted site-specific DVFs are < 82 parts per bi llion**  **(ppb), a clear demonstration of predicted attainmen t is shown. If the predicted DVFs is >**  **82 ppb and < 87 ppb, then a weight of evidence demonstration mus**  **t be submitted that supports 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 o**  **utcome of the modeled attainment test. Equation L- 1**  **presents the modeled attainment test, applied at mo nitoring site “x” as described in Section 4.0 of th**  **e** Attainment Guidance

**. (DVF) = (RRF) x (DVB)**  Equation L-1

**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, 2001-200 3, and 2002-2004 design vales**  **periods for the 2002 baseline inventory year).**

**(RRF) = the ratio of the future 8-hr daily maximum concentration predicted "nearby" a monitor**  **(averaged over each day of the episode) to the curr ent 8-hr daily maximum**  **concentration predicted "nearby" the monitor (avera ged over each day of the episode).** 

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

**It is important to consider an array of cells “nea rby” a monitor rather than focusing on the**  **individual cell containing the monitor. This allow s for variations in the model performance where the**  **peak ozone may not occur in the grid cell that cont ains the monitor but rather nearby the monitor. Ta**  **ble L-1 provides the USEPA's recommendations for defini**  **ng “nearby” cells for grid systems having cells of various sizes. Since the attainment demonstration**  **modeling was performed using a 12-kilometer grid resolution, the size of the array for “nearby” cell**  **s was 3 x 3.**

Table L-1: USEPA’s Recommendation for Defining “Ne arby” 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 m ean future year modeling 8-hour ozone daily**  **maximum to the mean baseline year modeling 8-hour o zone daily maximum “near” the monitor.**  **(Equation L-2). 3** 

**RRF = mean future yr. 8-hr daily max “near” monitor “x”**  Equation L-2 **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 with thos e days**  **used in the RRF calculation. If there are fewer th an 10 days with a modeled daily maximum 8-hour**  **average ozone equal to or greater than 85 ppb, then the threshold is reduced by 1 ppb until there are**  **at least 10 days identified for use. If there are few**  **er than 10 days with a modeled daily maximum 8-hour average ozone equal to greater than 70 ppb, then al**  **l days at 70 ppb and higher are used in the RRF calculation and consideration of modeling another e**  **pisode should be explored.**

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

**1. The design value period (e.g., the average 4th high**  **est value for the 3-yr period used to designate an area “nonattainment”, here the period from 2001**  **to 2003)**

**2. The average 4th highest value for the 3-yr period s**  **traddling 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 which**  **include the baseline inventory year (e.g., the 2000-2002, 2001-2003, 2002-2004 design value period**  **s for a 2002 baseline inventory year)**

**4. The average of the three design value periods which**  **straddle the baseline inventory year (e.g., the average of the 2000-2002, 2001-2003, and 2002-2004**  **design value 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 L-2 at each ozone monitoring site in the Metrolina**  **region.**

**Table L-2 lists the attainment test results by mon itor in the Metrolina area. The first column is**  **the monitoring site, then the county the monitor is located in, followed by the DVB used for the test.**  **The next series of columns are the number of days used**  **in the calculation, the ozone level threshold neede d to**  **reach at least 10 days for RRF, the calculated RRF and the resulting DVF for the attainment year, 2009** 

**. The bold italicized DVFs are values that fall withi**  **n the range where additional weight of evidence is needed to demonstrate attainment. Half of the moni**  **tors in the Metrolina nonattainment area have predicted DVFs that fall below 82 ppb and the other**  **half fall between 82 ppb and 87 ppb. Therefore, additional weight of evidence is required to demons**  **trate attainment. The North Carolina Division of A ir**  **Quality (NCDAQ) and the South Carolina Department o f Health and Environmental Control (SCDHEC)**  **believe that the weight of evidence presented in Se ction III supports a demonstration of attainment.** 

Table L-2: Metrolina Attainment Test Results for 2 009

**Monitoring Site County DVB**  **(ppb) Number of** 

**Days used in RRF**  **Ozone**

**Threshold (ppb)**  **RRF DVF**  **(ppb) 4** 

**Arrowood Mecklenburg 84.7**  **18 85**  **0.892 75**  **County Line Mecklenburg 97.3**  **13 85**  **0.874** 85 **Crouse Lincoln 90.7**  **10 84**  **0.868 78**  **Enochville Rowan 97.0**  **13 85**  **0.870** 84 **Garinger (Plaza) Mecklenburg 95.3**  **19 85**  **0.883** 84 **Monroe Union 87.0**  **10 81**  **0.884 76**  **Rockwell Rowan 97.3**  **10 84**  **0.862** 83 **York York, SC 83.0**  **11 84**  **0.861 71** 

II. ADDITIONAL CORROBORATIVE ANALYSES AND WEIGHT O F EVIDENCE DETERMINATION

**As part of the weight of evidence determination, t he following analyses will be evaluated:** 

**• Alternative DVF calculations,**

**• Metrics of air quality modeling results,**

**• Air quality modeling results from other studies,**

**• Observed air quality trends and additional reduct ions in emissions, and** 

**• Local measures not modeled.**

**The weight of evidence determination is a suppleme nt to the modeled attainment test and further**  **supports that the area will attain the NAAQS for 8- hour ozone by June 15, 2010.** 

A. Alternative DVF Calculatation

**The NCDAQ/SCDHEC used the USEPA recommended method of calculating the DVB in its**  **modeled attainment test. However, the NCDAQ has co mmented several times on various draft versions**  **of the attainment guidance that it does not believe that a weighted DVB is appropriate and that a DVB**  **calculated using a straight average minimizes the i mpacts of any abnormally hot/dry or cool/wet**  **meteorological conditions. As part of the weight o f evidence demonstration, the NCDAQ/SCDHEC**  **propose an alternative method to calculate the DVB and presents the modeled attainment test results wi**  **th this alternative DVB.** 

**The USEPA recommends calculating the DVB by averag ing the three design value periods that**  **straddle the baseline inventory year. This methodo logy results in a center weighting of annual 4**  **th highest**  **ozone concentrations around the baseline inventory year because the three design value periods average**  **d contain overlapping data. When simplified, the rec**  **ommended DVB calculation for this SIP modeling exercise can be seen in Equation L-3.** 

**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)**  Equation L-3 **9 5** 

**The weighting scheme of annual 4 th**  **highest ozone concentrations in the recommended DV B**  **calculation weights the center, or third, year thre e times more than that of the first or last year an**  **d one and a 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 meteorological conditi ons and resulting air quality conditions will be**  **amplified upward or downward in the modeled attainm ent exercise.** 

**To minimize potential impacts of any abnormal mete orological conditions while still considering**  **ozone conditions across a 5-year span, an alternati ve DVB calculation--that does not weigh any of the**  **years more than another but is a straight average o f annual 4**  **th highest ozone concentrations for the 5-year**  **span centered on the baseline inventory year--was c onsidered (Equation L-4).** 

**2000 4 th**  **Highest + 2001 4 th**  **Highest + 2002 4 th**  **Highest DVB = 2003 4**  **th Highest + 2004 4**  **th Highest**  Equation L-4 **5**

**When the five-year straight average DVB is applied to the remainder of the Modeled Attainment**  **Test equations, the resulting DVFs are shown in Tab le L-3 at each monitoring site in the Metrolina**  **region.**

Table L-3: Five-Year Average Alternative Attainmen t Test Results for 2009

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

**Arrowood Mecklenburg 83.4 0.892 74 County Line Mecklenburg 95.6 0.874**  83 **Crouse Lincoln 89.2 0.868 77 Enochville Rowan 94.4 0.870**  82 **Garinger (Plaza) Mecklenburg 93.8 0.883** 82 **Monroe Union 84.6 0.884 74 Rockwell Rowan 94.6 0.862 81**  **York York, SC 79.8 0.861 68**

**In comparison to the respective DVF values found i n Table L-2, the DVF values in Table L-3 are**  **slightly lower at each monitoring site. These diff erences were expected, as 2002 was an abnormally ho**  **t and dry year throughout the Southeast resulting in**  **ozone concentrations that were higher than in the surrounding years of 2000, 2001, 2003, and 2004. F**  **igure L-1 below illustrates this by charting the number of days with temperatures greater than 90o F**  **versus the maximum fourth highest 8-hour ozone value for the Metrolina area. Comparing 2002 to th**  **e surrounding years used in the DVB (2000, 2001, 2003, and 2004), 2002 had significantly more days w**  **ith greater than 90oF temperatures. Similarly, the maximum fourth highest 8-hour ozone value was ~5 pp**  **b higher than the surrounding years used in the DVB.** **6**

Figure L-1: Number of days greater than 90oF versu s the 4 th highest 8-hour ozone value for the Metrolina area.

**Thus, the recommended DVB calculation weighted the higher air quality conditions several times**  **more than in the NCDAQ alternative DVB calculations . The NCDAQ firmly believes that the non**  **weighted or straight five-year average approach to the DVB calculation is more appropriate and**  **minimizes dramatic fluctuations in meteorological a nd air quality conditions from year to year. This**  **would be the case whether the center weighted year was an abnormally hot/dry year or a cool/wet year.** 

**While none of the monitoring sites in the Metrolin a region had DVF values at or above 85 ppb in**  **Table L-3 using the NCDAQ alternative DVB calculati on, there are still three monitors that have DVFs**  **that fall between 82 ppb and 87 ppb. This continue s to indicate that some additional weight of eviden**  **ce 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 observationa l**  **datasets are described. A series of three addition al air quality modeling outputs or metrics is**  **recommended to provide assurance the modeled attain ment demonstration indicates attainment. These**  **metrics look at the relative change between the bas eline and future years modeling and help to**  **demonstrate how widespread the improvement in air q uality is expected in the future. Although the fin**  **al guidance did not recommend percentage cut points th**  **at corresponds to supportive weight of evidence, an earlier draft version of the**  Attainment Guidance **recommends that the metrics should be at least 80% or**  **higher.**

**As described in Section 7.1 of the** Attainment Guidance **, the collected modeling data from the 2002 and 2009 modeling output masks were applied to**  **the following metrics:**



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

4th Highest

0 10 20 30 40 50 60

19961997199819992000200120022003200420052006# Days Hi Temp≥90FMay-Sep

0.080 0.085 0.090 0.095 0.100 0.105 0.110 0.115Max 4th Highest

# Days Temperature >90F Max 4th Highest**7**

**1. Relative change in surface grid-hours greater th an 84 ppb**  **. This metric is termed Persistence-Hour and is defined as the number of gr**  **id-cells in a given region with predicted hourly 8-hour ozone concentrations greate**  **r than 84 ppb. The relative change in Persistence-Hour is presented as a percen**  **t reduction computed for the modeling period May through September from the base**  **line year case to the future year case.** 
**2. Relative change in the number of grid cells with predicted 8-hr daily maxima greater**  **than 84 ppb. This metric is termed Persistence-Daily metric an**  **d is similar to Persistence-Hr, but uses the modeled daily maximum**  **8-hour ozone concentrations greater than 84 ppb instead of the hourly 8-hour oz**  **one concentrations. The relative change in Persistence-Daily is also presented as a**  **percent reduction computed for the modeling period May through September from the base**  **line 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 predicted hourly 8-hour ozone concentrations greater than 84 ppb. G**  **iven the definition of Persistence, this Severity could be considered as a weighted for**  **m of the Persistence metric. The relative change in Severity is also presented as a**  **percent reduction computed for the modeling period May through September from the base**  **line 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 addit ional metrics are:** 

**4. Relative change in the sum of the predicted 8-hr daily maxima greater than 84 ppb** 

**. Severity-Daily metric is similar to Severity-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 perio**  **d 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**  **grid-cells with predicted maximum 8-hour ozone conc entrations sorted within each**  **of the Code Green, Yellow, Orange and Red categorie s, as defined by the USEPA's**  **AQI Index. As with the persistence and severity me trics, the AQI counts metric can**  **be applied to both hourly and daily maximum 8-hour ozone concentrations. AQI**  **Counts are presented as percentages of the total nu mber of grid-cells within the study**  **region.**

**The metrics described above were applied to the mo deling results for just of the nonattainment**  **area. Below, Figure L-2 depicts the region for whi ch this modeling data was extracted for both the 20**  **02 baseline and the 2009 attainment year modeling runs** 

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

**The results from each of the five air quality mode ling metric calculations demonstrated**  **significant reductions of greater than 85% in the 2 009 future year air quality modeling for days that**  **modeled above the NAAQS in the Metrolina nonattainm ent area. Each metric demonstrated very large**  **relative reductions for 2009. It is important to n ote that the relative reductions in all metrics wel**  **l surpassed the draft version of the**  Attainment Guidance **recommendation of 80% for these particular calculations.** 

**Figure L-3 below presents the relative reductions calculated in the first four metrics described**  **above. The left 2 bars are the Persistence-Hour an d Persistence-Daily reductions, and the right 2 bar**  **s are the Severity-Hour and Severity-Daily reductions. T**  **he results demonstrate a 91.2% reduction in persistence of hourly maximum ozone and 88.7% reduc**  **tion in persistence of daily maximum ozone. The severity reductions are on a similar scale of 91.6%**  **and 89.1% reduction for hourly and daily maximum ozone, respectively.** **9** Figure L-3: Persistence and Severity for the Metro lina Area **Equating the 89.1% relative reduction in the daily maximum ozone to AQI counts, Figure L-4**  **demonstrates a drop from 257 grid cells in the Code Orange and Red levels in the 2002 baseline modelin**  **g to only 29 grid cells in the 2009 future modeling.**  **Furthermore, the number of grid cells in the Code Yellow and above (>65 ppb) is reduced by over half,**  **from 3,352 grid cells in 2002 to 1,536 grid cells in**  **2009.**

Figure L-4: Daily AQI counts for the Metrolina Are a



### % Reduct ion in Persistence (# Grid Cells) and Severity (Sum C ij_85 

### ) of Hourly & Daily Max O 3



### 60 65 70 75 80 85 90 95 100

Persistence Severity Hourly Daily% Reduction



### Daily 8-hr AQI Counts

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

Daily 2002 Daily 2009% Grid Cells in Region
Yellow

Orange

Green**10**

**The hourly AQI counts are equally encouraging. Fi gure L-5 displays the 91.2% relative**  **reduction in hourly persistence in terms of the AQI counts. It corresponds to a reduction from 988 ho**  **urly grid cells in the Code Orange and Red levels in the**  **baseline modeling to only 86 hourly grid cells in the**  **attainment year modeling. Looking at all hourly gr id cells Yellow and above, the count is reduced fro**  **m 25,890 hourly grid cells to 9,140, which translates**  **to a 64.7% reduction. Table L-4 contains all the grid**  **cell counts for both the Hourly and Daily AQI count analysis.** 

Figure L-5: Hourly AQI Count for the Metrolina Are a

Table L-4: Total number of grid cells for the AQI Categories.

C. Air Quality Modeling Results From Other Studie s
**Another recommended weight of evidence analysis is to review other air quality modeling results**  **that included the Metrolina nonattainment area to d etermine how other modeling results compare to the**  **attainment demonstration. There are two air qualit y modeling studies to which results are available f**  **or the Metrolina area.** 

**The first is the Early Action Compact (EAC) modeli ng that the NCDAQ performed for the EAC**  **areas within North Carolina. Since the modeling do main for this analysis covered the majority of Nort**  **h Carolina, including the Metrolina nonattainment are**  **a, the modeling results can be easily compared to t he**  Grid Cells Grid Cells Daily 2002 Daily 2009 Hourly 2002 Hourly 2009 Green 7181 9543 250856 268576 Yellow 4107 2039 26900 10365 Orange 340 46 1316 131 total 11628 11628 279072 279072



### Hourly 8-hr AQI Counts

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

Daily 2002 Daily 2009% Grid Cells in Region



### Orange Yellow Green**11**

**attainment demonstration. There are some differenc es 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, but there are results for 2007 and 2012. Table L-5 displays the EAC modeling results**  **for the Metrolina monitors for both of these future years.** 

Table L-5: 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 the re 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 Po int EAC area, the EAC attainment test results**  **predicted the highest monitor in the area to be at 83 ppb in 2007. However the current 2004-2006 desi**  **gn value for that area is 80 ppb, below what was proje**  **cted and a year earlier.**

**Another air quality modeling exercise that contain ed results for the Metrolina nonattainment area**  **is the USEPA’s modeling for the Clean Air Interstat e Rule (CAIR). The Technical Support Document for**  **the final CAIR (March 2005) provided modeling resul ts with and without the implementation for the**  **CAIR. Differences between the USEPA’s modeling and the attainment demonstration are: (1) the**  **meteorology was for 2001, (2) the DVB was the weigh ted design values the 1999-2003 period, and (3)**  **the modeling results were for 2010. These modeling results are listed in the table below.** 

Table L-6: Metrolina DVFs based on the USEPA’s CAI R 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 monitor i n a county where more than one monitor is**  **located. The USEPA’s modeling results predicts tha t the Metrolina nonattainment area should be below**  **the 8-hour ozone standard by 2010. Although this i s one year later than the attainment year for the**  **Metrolina area, the USEPA’s 2010 CAIR DVFs are 3 to 4 ppb lower than what the NCDAQ/SCDHEC** **12**

**are showing in the attainment demonstration, and su pports weight of evidence that the Metrolina area w**  **ill attain the 8-hour ozone standard by its attainment**  **year of 2009.**

D. Air Quality Trends and Additional Reductions i n Emissions

**Since the 8-hour ozone designation for the Metroli na 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 o**  **f the seven North Carolina monitors in the area were**  **violating the NAAQS. Each year since, the design values have decreased and/or the number of violatin**  **g monitors in the region has decreased. With the latest design value period, 2004-2006, the highest**  **violating monitor has a value of 88 ppb and there a re**  **only three monitors that exceed the NAAQS (See Tabl e L-7)** 

Table L-7: Design Values (ppb) for the North Carol ina Monitors in the Metrolina Area
**Monitoring Site County 2001-2003 2002-2004 2003-200 5 2004-2006**  **Arrowood Mecklenburg 84 81 78 80**  **County Line Mecklenburg** 98 92 87 88 **Crouse Lincoln** 92 86 **81 79**  **Enochville Rowan** 99 91 85 85 **Garinger (Plaza) Mecklenburg** 96 91 86 88 **Monroe Union** 88 85 **79 78**  **Rockwell Rowan** 100 94 88 **83 York York, SC 84 81 75**  **76**

**The current ozone design values are very close to the predicted attainment year design values;**  **however, there are still significant nitrogen oxide s (NO**  **x ) emission reductions that are expected between**  **now and the attainment year 2009. Although most of these expected NO**  **x**

**emission reductions have been included in the attainment demonstration modeling,**  **it does not appear the model is responsive enough t o**  **expected emission reductions.**

**The NCDAQ/SCDHEC have estimated that there will be approximately 8.5 tons per day of NO**  **x emissions reduced each year from the mobile sector.**  **These reductions are the result of Federal motor vehicle and equipment standards for both highway ve**  **hicles and off-road equipment. As the older vehicles in the fleet are retired and replaced with**  **newer vehicles meeting the Federal standards, the NO**  **x emissions continue to decrease, even though vehicle**  **miles traveled continue to increase. Similarly, a s**  **newer off-road equipment is purchased and older equ ipment is retired, the NO**  **x emissions see a downward**  **trend.**

**Another source of NO x**  **emission reductions that are expected to occur bet ween now and the**  **attainment year are from the electric generating fa cilities located in and near the Metrolina nonattai**  **nment area. The Clean Smokestacks Act requires the two l**  **arge North Carolina utilities to meet annual NO x**  **emission budgets for 2007 and a tighter budget for 2009. Several of the Duke Energy units are still**  **expected to have controls installed over the next t wo years. Figure L-6 displays the location and siz**  **e of the Duke Energy facilities located in the vicinity**  **of the Metrolina nonattainment area. Table L-8 lis ts the**  **units that are near the Metrolina area and shows bo th the year the controls are expected to come on-li**  **ne and the estimated amount of NO**  **x emission reductions for the ozone season.** **13**

Figure L-6: Location and size of the Duke Energy f acilities located in the vicinity of the Metrolina nonattainment area.**14** Table L-8: Utility NO x

Emission Reductions since 2006 Ozone Season

**Facility County Technology Operational**  **Date Ozone Season** 

**Reductions (tons/season)**  **Allen Steam Station Unit 2**  **Unit 3 Gaston**  **SNCR SNCR**  **Spring 2007**

**Fall 2007 ~300** 

**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 mobile source and utility N O**  **x emission reductions that are expected in**  **the Metrolina area between the end of the 2006 ozon e season and before the beginning of the attainment**  **year 2009 is significant. Since the 2004-2006 desi gn values are just above the standard, the addition**  **al NO**  **x emission reductions in the area should ensure that**  **the Metrolina area would attain the NAAQS by the prescribed attainment year.** 

E. Local Measures not Modeled

**As discussed in Section III of the Attainment Demo nstration narrative, the Metrolina**  **nonattainment area is a NO x**  **-limited area, and the largest source of NO x**  **emissions in this region come from mobile sources and electric generating facilit**  **ies. A significant source of NO x**  **emission reductions that has not been included in the modeling is the a**  **ddition of an SCR unit at Marshall Unit 3. When th e**  **modeling was started, Duke Energy had installed an 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 Ac t**  **annual budget for this company, Duke Energy has ann ounced its intent to install an SCR unit in order t**  **o provide a safety margin in meeting the Clean Smokes**  **tack Act NO x**  **budget. As can be seen in Figure L-6 in the previous section, the Marshall Steam Station**  **is located directly north and adjacent to the Metr olina**  **nonattainment area. The additional NO x**  **emission reductions expected at this facility will have an impact**  **on the ozone formation in the Metrolina area on day s when the winds are coming from the**  **north/northwest and on days when there is recircula tion occurring. This SCR unit should be installed**  **the Fall of 2008 and will be operational before the beg**  **inning of 2009. A copy of the 2007 compliance plan for Duke Energy documenting this planned installati**  **on of the SCR at Marshall Unit 3 can be found in Appendix M.** 

**In addition to the Marshall NO x**  **emission reductions, the Metrolina area has a numb er of groups**  **that work towards decreasing emissions. These meas ures are voluntary measures that although may not** **15**

**account for large emission reductions, they are dir ectionally correct. A few of the known measures th**  **at are under way in the Metrolina area are listed belo**  **w. A list of known projects going on in North Caro lina**  **is attached at the end of this Appendix.**

• **I-77 High Occupancy Vehicle (HOV) lane in Mecklenbu rg County.**  **A recent evaluation of the HOV lanes on I-77 through Charlotte, North C**  **arolina reported that there has 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 per**  **cent 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.” Additi**  **onally, the “Average daily patronage on the [Charlotte Area Transit System] CATS express**  **routes using the I-77 HOV facility increased by 63 percent between October 2004 and 20**  **05 ...”. This reduction of vehicle miles traveled in this area was not modeled in the**  **attainment demonstration. Having more people carpooling or using the transit system**  **in Mecklenburg will reduce both VOC and NOx emissions. A copy of the North Carolina De**  **partment of Transportation (NCDOT) evaluation of the I-77 HOV lane can be foun**  **d 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. T his technology provides truckers**  **with electricity and air conditioning, allowing the truckers to turn off their 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 will be**  **created between Rider and Salisbury Transit. This provided an express route between**  **Kannapolis and Salisbury. Having an express route between these two cities will reduce**  **the number of personal cars on the roadways, which in turn will reduce VOC and NO**  **x emissions. This new express route should be in ope**  **ration between 2008 and 2010.**

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

• **Idle Reduction Policies. North Carolina Department of Public Instruction h**  **as issued a policy that all school bus drivers are to refrain f**  **rom idling their buses while waiting to pick up children at the school as well as when the**  **buses are at the transportation yard. Additionally, several cities and businesses have is**  **sued idle reduction policies for their fleet vehicles. This reduces VOC and NOx emissions**  **as well as fine particulate matter. Some of the partners passing idle reduction policie**  **s include: Town of Concord, City of Salisbury, and Duke Power.** 

• **Biodiesel use. A number of cities, counties and businesses have**  **started using biodiesel for their diesel fleet. Most often B-20 is being u**  **sed. B-20 will reduce VOC emissions as well as fine particulate matter. Some of the partn**  **ers using 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 Fi**  **lters (DPFs) on their diesel equipment. The vehicles that have been retrofitted**  **include schools buses, as well as county fleet trucks for solid waste pickup. Althou**  **gh these types of filters are designed to remove fine particulate matter, when used with ultr**  **a low sulfur diesel fuel, NO x**  **and VOC emissions are also reduced. Some of the partners i**  **nstalling DOCs and/or DPFs include: 16** 

**Cabarrus County Schools, Gaston County Schools, Ire dell County Schools, Lincoln**  **County Schools, Mecklenburg County Schools, Rowan C ounty Schools, Salisbury Public**  **Schools, City of Charlotte and Mecklenburg County.**

F. Weight of Evidence Conclusions

**The NCDAQ/SCDHEC believe 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 calcula ted in this section, all of the Metrolina**  **nonattainment area monitors are predicted to be bel ow the 8-hour ozone NAAQS in 2009. Although**  **three of the monitors still fall within the range f or weight of evidence requirements, the monitor DVF**  **s are lower than when a weighted DVB is used.** 

**The air quality modeling metric analyses for the M etrolina nonattainment area demonstrate**  **relative reductions well beyond the recommended 80% mark that is considered appropriate for concluding**  **that a proposed strategy would meet the 8-hour ozon e NAAQS. Additionally, other air quality modeling**  **studies have found that the Metrolina area should a ttain the 8-hour ozone NAAQS by the prescribed**  **attainment year.**

**The observed air quality trends in conjunction wit h further NO**  **x emission reductions expected in**  **the Metrolina area strengthens the argument that th e attainment demonstration is an acceptable**  **demonstration. Finally, given the variety of addit ional emissions reductions that were not included i**  **n the development of this modeling exercise, but will occ**  **ur throughout the surrounding areas before 2009, it is**  **reasonable to conclude that the short lived events portrayed in the future modeled year by an extremel**  **y small number of remaining exceeding grid cells will**  **be below the NAAQS in 2009.**

**The NCDAQ/SCDHEC believe that the weight of eviden ce provided in this section is strong**  **evidence that the Metrolina nonattainment area will attain the 8-hour ozone NAAQS by 2009.** **17**

IV. UNMONITORED AREA ANALYSIS

**The modeled attainment test does not address futur e air quality at locations where there is not an**  **ozone monitor nearby. To guard against the possibi lity that air quality levels could exceed the stand**  **ard in areas with limited monitoring, Section 3.4 of the**  Attainment Guidance **suggest that additional review is “necessary, particularly in nonattainment areas whe**  **re the ozone or PM2.5 monitoring network just meets or minimally exceeds the size of the network requir**  **ed to report data to Air Quality System (AQS).” Th is**  **review is intended to ensure that a control strateg y leads to reductions in ozone at other locations t**  **hat could have baseline (and future) design values exce**  **eding the NAAQS were a monitor deployed there. The test is called an “unmonitored area analysis.”**  **The purpose of the analysis is to use a combinatio n of**  **model output and ambient data to identify areas tha t might exceed the NAAQS if monitors were located**  **there.**
**The NCDAQ, along with Local and Tribal Programs, c urrently operates a network of 41 ozone**  **monitors. Twenty-six of these monitors were establ ished as State and Local Air Monitoring Stations**  **(SLAMS). These SLAMS monitors were selected based on specific monitoring objectives (background**  **concentration, area of highest concentration, high population, source impact, transport, and rural imp**  **act) as required by the USEPA and siting scales (micro,**  **middle, neighborhood, urban, and regional) established by the USEPA. Eight of the network mon**  **itors were further designated as National Air Monitoring Stations (NAMS) by the USEPA and have th**  **e primary objective to provide ozone data from areas of expected highest concentration and populat**  **ion exposure and are used to evaluate trends in national air quality. The remaining 14 monitors ar**  **e Special Purpose Monitors that were established by NCDAQ to evaluate models, study ozone formation and**  **transport, and obtain a better understanding of ozone in North Carolina. The remaining monitor is**  **a Tribal monitor operated by the Eastern Band of Cherokee Nation.** 

**NCDAQ believes that the density of its monitoring network relieves the necessity of applying this**  **additional analysis. With an average of one monito r per 3,077 km**  **2 , this is one of the densest statewide**  **ozone monitoring networks in the nation. Additiona lly, the monitor density across the Metrolina**  **nonattainment area is more than twice that of the s tatewide monitor density (on average a monitor ever**  **y 1,278 km**  **2 ). A map of each ozone monitor and its NCDAQ/VISTA**  **S 12-km modeling grid is provided in Figure L-7. As can been seen by the figure, the sp**  **atial coverage of the monitors, and their resulting “near**  **by” 3x3 arrays, covers the majority of the urban ar eas where ozone tends to be higher.** 
**Despite being confident its monitoring network is robust enough to cover the state, NCDAQ has**  **looked at preliminary results from the “beta” (draf t) version of the “Modeled Attainment Test Software**  **” (MATS) tool. The MATS tool has been developed by t**  **he USEPA to spatially interpolate data, adjust the spatial fields based on model output gradients, and**  **multiply the fields by model calculated RRFs to complete the unmonitored area analysis. The MATS t**  **ool is currently being “beta tested” and peer reviewed, with the release of a guidance document f**  **or the tool still pending. Once the final version of the**  **MATS tool has been released, after sufficient peer review and proper guidance documentation for the**  **analysis of the results is provided, NCDAQ will eva luate the MATS tool output.** **18** Figure L-7: Ozone Monitors and with Respect to the VISTAS 12 km Grid**19** ATTACHMENTS TO APPENDIX L

**Attached to this Appendix is supporting documentat ion for Section III. The following documents**  **are attached:**

• **NCDOT I-77 HOV evaluation report**

• **Spreadsheet of measures from Cabarrus/Rowan Urban A rea Metropolitan Planning Organization** 

• **Spreadsheet of National Diesel Data from the USEPA for North Carolina** 

• **Spreadsheet of Diesel Data from the NCDAQ**

• **Correspondence from Centralina Council of Governmen ts**