1

BEFORE THE ADMINISTRATOR

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

In the Matter of: )

)

FINAL RULE, )

AIR QUALITY DESIGNATIONS ) EPA-HQ-OAR-2008-0476;

FOR THE 2008 OZONE NATIONAL ) FRL-9668-2, RIN 2060-AP37

AMBIENT AIR QUALITY STANDARDS, )

77 FED. REG. 30,088 (MAY 21, 2012) )

)

)

ANDERSON COUNTY, TENNESSEE, )

BLOUNT COUNTY, TENNESSEE, and )

KNOX COUNTY, TENNESSEE )

)

Petitioners. )

PETITION FOR RECONSIDERATION BY

ANDERSON COUNTY, BLOUNT COUNTY, AND KNOX COUNTY, TENNESSEE

Pursuant to Section 307 of the Clean Air Act (“CAA”), 42 U.S.C. §7607, Anderson 

County, Tennessee (“Anderson County”), Blount County, Tennessee (“Blount County”), and 

Knox County, Tennessee (“Knox County”) (collectively, “Counties”), through the undersigned 

counsel, file this Petition for Reconsideration and request that the Administrator of the United 

States Environmental Protection Agency (“EPA”) convene a proceeding to reconsider the “Air 

Quality Designations for the 2008 Ozone National Ambient Air Quality Standards,” 77 Fed. Reg. 

30, 088 (May 21, 2012) (the “Final Rule”). As described below, this petition is based upon new 

information of central relevance not available during the public comment period for the Final 

Rule. 

INTRODUCTION

The Counties allege that EPA’s promulgation of the Final Rule was arbitrary and 

capricious because, despite EPA’s decision (made on April 10, 2010) to accept and use 2009-
2

2011 air monitoring data instead of 2008-2010 data, EPA nevertheless designated Anderson 

(partial), Blount, and Knox Counties nonattainment based on the 2009-2011 data. This action 

was made after the Final Rule’s public comment period expired on February 3, 2012. EPA’s 

arbitrary and capricious action designating Anderson (partial), Blount, and Knox Counties 

nonattainment for ozone violates the CAA and its implementing regulations, as well as EPA’s 

written policies. EPA’s decision to designate Anderson (partial) and Knox Counties--each of 

which had only attaining monitors using 2009-2011 data--and Blount County--in which the sole 

nonattaining monitor is located at high elevations and affected chiefly by long range transport, 

and thus not addressable by local actions--was an arbitrary and capricious action and an abuse of 

discretion because EPA failed to consider a boundary recommendation analysis submitted by the 

State of Tennessee and the Counties. Had EPA considered this analysis, it likely would not have 

made nonattainment designations for any of the Counties. Thus, the failure to consider this 

analysis is of central relevance to the outcomes in the Final Rule. 

FACTUAL AND PROCEDURAL BACKGROUND

The designation process for the 2008 ozone national ambient air quality standard began 

on December 4, 2008, when EPA issued guidance to the states regarding governors’ 

requirements to provide EPA with a list of all areas in the state and recommendations as to 

whether each area meets the ozone standard. “Air Quality Designations for the 2008 Ozone 

National Ambient Air Quality Standards,” 77 Fed. Reg. 30, 088, 30,090 (May 21, 2012). This 

guidance identified important factors which EPA recommended the governors use in making 

their recommendations. Although EPA initially intended to make final designations by March 

12, 2010, it announced its intent to reconsider the 2008 ozone standard on September 16, 2009. 

Id. EPA signed the proposed reconsideration on January 6, 2010. Id. Because EPA did not take 
3

final action on this reconsideration, the standard of 0.075 parts per millions remained in effect 

for purposes of final designations for the 2008 standard. Id. at 30,091. A settlement between 

EPA and WildEarth Guardians required EPA to issue its final designations by May 31, 2012. Id. 

On September 22, 2011, EPA notified its Regional Air Division Directors that it was 

“proceeding with initial area designations under the 2008 [ozone] standard, starting with 

recommendations states made in 2009 and updating them with the most current, certified air 

quality data.” EPA Memorandum to Air Division Directors, “Implementation of the Ozone 

National Ambient Air Quality Standard” (Sept. 22, 2011). EPA stated that in implementing the 

2008 ozone standard, it would be “mindful of the President’s and Administrator’s direction that 

in these challenging economic times, EPA should reduce uncertainty and minimize the 

regulatory burdens on the States.” Id. at 1. 

On December 8, 2011, EPA Region 4 notified Tennessee Governor Bill Haslam of its 

intended designations for Tennessee. Letter from Regional Administrator Gwendolyn Keyes 

Fleming to Governor Bill Haslam (Dec. 8, 2011). In this letter, EPA said that it had 

“preliminarily concluded that the following counties should be included as part of the KnoxvilleSevierville-La Follette nonattainment area: Anderson, Blount, Knox, Loudon and Sevier 

Counties, in their entirety, and a portion of Cocke County.” Id. at 2. EPA also stated that it “will 

continue to work with State officials regarding the appropriate boundaries for . . . the counties in 

the Knoxville-Sevierville-La Follette Area. Id. EPA also said that Tennessee could submit 

additional information for use in making this boundary determination if it did so prior to 

February 29, 2012. Id. 

By publication in the Federal Register on December 20, 2011, EPA announced a public 

comment period for its intended designations. “EPA Responses to State and Tribal 2008 Ozone 
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Designation Recommendations: Notice of Availability and Public Comment Period,” 76 Fed. 

Reg. 78,872. The public comment period ended on February 3, 2012. 77 Fed. Reg. 30,088, 

30,091. 

By letter dated February 27, 2012, Tennessee Department of Environment and 

Conservation Commissioner Bob Martineau amended recommendations for the Counties, based 

on ambient air monitoring data from 2009-2011. Letter from Commissioner Robert J. Martineau, 

Jr., to Regional Administrator Gwendolyn Keyes Fleming (Dec. 22, 2012). As explained in this 

letter, at the time there was a question whether 2011 monitoring data completeness requirements 

for Knox County monitors had been met. If the Knox County data were deemed acceptable 

(EPA concluded the data were acceptable on April 10, 2012), TDEC recommended “limit[ing] 

the nonattainment area to that portion of Blount County that contains the Great Smoky 

Mountains National Park.” Id. at 1. 

Commissioner Martineau submitted recommendations again on April 5, 2012. . Letter 

from Commissioner Robert J. Martineau, Jr., to Regional Administrator Gwendolyn Keyes 

Fleming (Apr. 5, 2012). He reiterated that EPA should designate the Counties, other than “[t]hat 

portion of Blount County that contains the Great Smoky Mountains National Park,” attainment 

because using 2009-2011 data, “only the monitor located at Look Rock in Blount County 

exceeds the standard of 0.075 parts per million with a calculated design value of 0.077 parts per 

million. This is a high elevation site located within the Great Smoky Mountains National Park 

which we believe is predominately influenced by long range transport.” Id. at 1.

EPA published the Final Rule on May 21, 2012, and the Counties now petition for 

reconsideration of the Final Rule due to EPA’s arbitrary and capricious action designating two 

Counties with attaining monitors (Anderson (partial) and Knox) nonattainment and designating 
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all of Blount County nonattainment based on one high elevation monitor influenced significantly 

by elevation and long range transport. 

STATUTORY FRAMEWORK FOR PETITION

Under CAA section 307, the EPA Administrator shall convene a proceeding for 

reconsideration of a rule if a person raising objection to that rule can demonstrate that it was 

impracticable to raise such objection during the period for public comment or “if the grounds for 

such objection arose after the period for public comment (but within the time specified for 

judicial review)” and “if such objection is of central relevance to the outcome of the rule.” 42 

U.S.C. § 7607(d). 

Here, the grounds for the Counties’ petition arose after the period for public comment 

and within the time specified for judicial review. As noted above, the public comment period for 

the Final Rule expired on February 3, 2012. The Counties base this petition on the grounds that 

EPA’s acceptance of the 2009-2011 data was not made until after the close of comment period, 

and despite accepting these data, EPA nevertheless designated Anderson (partial), Blount, and 

Knox Counties nonattainment on May 21, 2012. The Counties’ petition for reconsideration is 

therefore timely under 42 U.S.C. § 7607(d).

GROUNDS FOR RECONSIDERATION

In November 2011 the State of Tennessee revised its March 2009 recommendations for 

the designation of counties in the state for attainment and nonattainment with the 2008 ozone 

NAAQS. (Letter from Robert J. Martineau, Jr., to Gwen Keyes Fleming, dated November 8, 

2011.) In that letter, TDEC recommended that for the Knoxville area, the portions of Blount, 

Cocke, and Sevier counties within the boundaries of the Great Smoky Mountains National Park 

(“Park”) be designated nonattainment and that the remaining portions of those counties, as well 
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as the entireties of the other counties in the Knoxville CSA, be designated attainment. This 

recommendation was based on 2009-2011 preliminary design values. Subsequently, EPA 

informed the State of Tennessee that it intended to designate Anderson, Blount, Knox, Loudon, 

and Sevier Counties in their entireties and the portion of Cocke County within the Park boundary 

as nonattainment. (Letter from Gwendolyn Keyes Fleming to the Honorable Bill Haslam, dated 

December 8, 2011.) EPA agreed with the State’s recommendation of attainment with regard to 

the remaining counties in the Knoxville CSA. EPA’s decision was based on 2008-2010 design 

values and a technical analysis of five factors (i.e., an analysis of the so-called “nine factors”).

After the close of the public comment period, EPA accepted the 2011 ozone data for the 

Knoxville CSA as complete, and used the 2009-2011 design values in making its designations 

with the 2008 ozone NAAQS. In April 2012, the State of Tennessee and the Counties submitted 

the following reanalysis of the factors EPA discussed in the attachment to its December 8, 2011 

letter. This document was submitted after the close of the public comment period, and it is not 

clear that EPA considered the reanalysis in its designation decisions. 

The Clean Air Act permits states to resubmit boundary recommendations after EPA 

announces an intent to modify the states’ initial recommendations. 42 U.S.C. § 7407(d)(B)(ii). If 

the statue expressly provides this opportunity for states to submit a second set of 

recommendations, EPA should consider any reanalysis submitted by the states. The State of 

Tennessee (and the Counties) submitted the following analysis of factors after EPA announced 

its intent to vary from Tennessee’s initial recommendations. EPA’s failure to consider this 

analysis was arbitrary, capricious, and an abuse of discretion. 

I. Factor 1: Air Quality Data
7

Figure 1 shows the locations of the nine ozone monitors in the Knoxville CSA and Table 

5 presents the 2009 through 2011 4th highest 8-hour daily maximum ozone concentration as well 

as the 2009-2011 design values for each of the monitors.
8

Figure 1 – Knoxville CSA Ozone Monitor Locations.

Table 5

2009-2011 Knoxville CSA 4th Highest 8-Hour Daily Maximums and Design Values

Monitor County 2009 4th Highest 

8-Hour Daily 

Maximum

(ppb) 

2010 4th

Highest 8-

Hour Daily 

Maximum

(ppb)

2011 4th

Highest 8-

Hour Daily 

Maximum

(ppb)

2009-2011

Design Value

(ppb)

Freels Bend Anderson 65 73 74 70

Cades Cove Blount 62 74 68 68

Look Rock Blount 69 81 82 77

Lost Creek Jefferson 68 77 73 72

Mildred Drive Knox 68 74 74 72

Rutledge Pike Knox 66 70 74 70

Roberts Road Loudon 68 76 75 73

Clingmans Dome Sevier 71 77 79 75

Cove Mountain Sevier 70 78 77 75
9

For the 2009-2011 period only one monitor in the Knoxville CSA exceeded the 2008 zone 

NAAQS: the monitor located in Blount County at Look Rock. The monitors in all of the other 

counties in the Knoxville CSA attained the NAAQS for this period.

II. Factor 2: Emissions and Emissions-Related Data

According to the 2008 National Emissions Inventory (“NEI”) Blount, Loudon, Sevier, 

and Cocke Counties made very small contributions to the area-wide emissions of NOX and 

VOCs, and Anderson County made a very small contribution to VOC emissions. (See

“Emissions and Emissions-Related Data” analysis contained in the attachment to EPA’s 

December 8, 2011 letter to the State of Tennessee.) According to the 2008 NEI, NOX emissions 

in Anderson County were 12,475 tons. Of that total, 8,622 tons were emitted by TVA’s Bull 

Run Power Plant. In the “Conclusion” section to the “Technical Analysis for KnoxvilleSevierville-La Follette” section of EPA’s attachment to its December 8, 2011 letter to the State 

of Tennessee, EPA points out that “while SCR controls were installed at the plant (i.e., Bull Run 

Power Plant), there has been a steady increase in NOX emission levels since 2006.” However, 

since 2008 NOX emissions from Bull Run have declined significantly. Not only have the total 

annual and ozone season emissions declined, but the emission rates have significantly declined 

as well, indicating that the SCR at the plant is effectively controlling NOX emissions. Figure 2 

and Table 6 summarize the NOX emissions from the Bull Run Plant.
10

Figure 2 – NOx Emissions - TVA’s Bull Run Plant, Anderson Co., TN.

Table 6

Bull Run Power Plant NOX Emissions*

Year Annual Emissions

(TPY)

Annual 

Emission Rate

(lbs/mmBTU)

Ozone Season

Emissions

(TPY)

Ozone Season 

Emission Rate

(lbs/mmBTU)

2008 8,622.3 0.372 2,983.8 0.244

2009 1,270.7 0.090 843.5 0.080

2010 1,221.0 0.074 829.5 0.069

2011 912.0 0.070 758.2 0.070

* Source: EPA Air Markets Program Data

III. Factor 3: Meteorology (Weather/Transport Patterns)

In EPA’s attachment to its December 8, 2011 letter to the State of Tennessee, EPA 

mentions an analysis of wind direction and speed for the 2008-2010 ozone season (March 

through October) conducted to better understand the fate and transport of precursor emissions 
11

contributing to ozone formation. EPA’s analysis of the National Weather Service data collected 

at Knoxville McGhee Tyson Airport indicated that southwest and west-southwest winds 

predominate along with a northern component.

Figure 3 – Wind Direction Percentage for Knoxville McGhee Tyson Airport, Ozone Season, 

2009-2011.

Figure 3 shows the results of a similar analysis for the 2009-2011 ozone seasons. 

Disregarding the calms, slightly over fifty percent of the time the wind was from the south to 

west quadrant. There are no significant point sources of NOX or VOC emissions in the counties 

EPA intends to designate nonattainment that are in the south to west quadrant from the Look 

Rock monitor. Again disregarding the calms, only about one-third of the time was the wind from 
12

the west to northeast, the direction from Look Rock in which most of the sources of NOX and 

VOCs emissions are located, as well as the major population centers and transportation corridors.

IV. Factor 4: Geography/Topography (Mountain Ranges or Other Air Basin 

Boundaries)

Section 107(d) of the Clean Air Act requires each state’s governor to provide EPA a list 

of all areas, or portions thereof, in the state designated as nonattainment, attainment, or 

unclassifiable for the ozone national ambient air quality standard. (42 U.S.C. § 7407(d)(1).) 

EPA designation guidance provides that potential ozone nonattainment areas “should be 

evaluated on a case-by-case basis.” (EPA Memorandum: Area Designations for the 2008 

Revised Ozone National Ambient Air Quality Standards 1, dated December 4, 2008.) Further, 

EPA “recognizes that these area-specific analyses conducted by states, tribes, and/or EPA may 

support nonattainment area boundaries that are larger or smaller than the presumptive area 

starting point.” (Id.) In this guidance document, EPA also provided a list of factors that the 

states could consider in making their nonattainment boundary recommendations. One of these 

factors is identified as “geography/topography (mountain ranges or other air basin boundaries).” 

(Id., Attachment 2.)

EPA previously has considered the impact of high elevation areas when making 

nonattainment designations. In North Carolina, EPA agreed to designate only areas above 4,000 

feet as the nonattainment area in the Plott Balsam Mountains because “the State submitted 

information indicating that the violations of the 8-hour ozone standard at the monitors located at 

the high elevations were due to long range transport and the area was not generating emissions 

that caused the violations.” (Letter from Region 4 Administrator to Secretary of North Carolina 

Department of Environment & Natural Resources, Enclosure 2, dated December 3, 2003.) 
13

In EPA’s attachment to its December 8, 2011 letter to the State of Tennessee, EPA 

discusses a number of analyses it conducted based on the 2008-2010 ozone seasons. EPA 

concluded (1) the two high elevation monitors in Sevier County (Clingmans Dome at 6655 feet 

above mean sea level (“MSL”), and Cove Mountain at 4150 feet above MSL) are located at “a 

significantly higher elevation than the Knox County monitors” and thus “measure elevated ozone 

levels overnight due to regional transport of tropospheric ozone formed during the daytime”; (2) 

the urban monitor in Knox County (Mildred Drive) exhibits a diurnal pattern typical of urban 

sites and predominantly impacted by urban and nearby emissions; and (3) the monitor at Look 

Rock (the only monitor measuring a violation of the standard during the 2009-2011 ozone 

seasons) exhibited a diurnal pattern characterized by impacts from both urban and nearby 

emissions as well as regional tropospheric ozone formed during the day, in some cases at the 

same time.

In EPA’s analysis it did not mention the characteristics of the diurnal patterns of the other 

monitors in the Knoxville CSA. Some of those monitors are located nearer local emission 

sources and at lower elevations (e.g., Rutledge Pike in Knox County, Freels Bend in Anderson 

County, Lost Creek Road in Jefferson County, and Roberts Road in Loudon County). EPA also 

did not mention the Cades Cove monitor located just nine miles from the Look Rock monitor in 

Blount County at an elevation of 1850 feet above MSL.

A detailed analysis of the diurnal patterns of all the monitors in the Knoxville CSA 

reveals that the characteristics of the Look Rock, Clingmans Dome, and Cove Mountain 

monitors are generally very similar, while all the other monitors in the Knoxville CSA exhibit 

diurnal patterns typical of urban sites, including the monitor located at Cades Cove. Figures 4 
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and 5 provide examples of the diurnal patterns at each monitor during high ozone episodes in the 

Knoxville CSA.

Figure 4 – Ozone Concentrations Across the Knoxville CSA, June 23-26, 2009.

Figure 5 – Ozone Concentrations Across the Knoxville CSA, May 4-8, 2010.

Clearly, concentrations of ozone at the Look Rock monitor exhibit diurnal characteristics 

very similar to those at the Clingmans Dome and Cove Mountain monitors, which are remote, 

high elevation monitors and, as EPA suggests in its analysis, are typically predominantly 

influenced by regional transport of tropospheric ozone, rather than nearby emissions. Also of 

note is that the average 2009-2011 design value for the three high elevation monitors (Look 

0

10

20

30

40

50

60

70

80

90

100

6:00 AM

10:00 AM

2:00 PM6:00 PM

10:00 PM

2:00 AM6:00 AM

10:00 AM

2:00 PM6:00 PM

10:00 PM

2:00 AM6:00 AM

10:00 AM

2:00 PM6:00 PM

10:00 PM

2:00 AM6:00 AM

10:00 AM

2:00 PM6:00 PM

10:00 PM

Ozone

(ppb)

June 23-26, 2009

Look Rock

Cades Cove

Lost Creek Road

Rutlege Pike

Mildred Drive

Roberts Road

Cove Mountain

Clingmans Dome

Freels Bend

0

20

40

60

80

100

0:005:00

10:0015:0020:00

1:006:00

11:0016:0021:00

2:007:00

12:0017:0022:00

3:008:00

13:0018:0023:00

Ozone

(ppb)

May 4-8, 2010

Look Rock

Cades Cove

Lost Creek Road

Rutlege Pike

Mildred Drive

Roberts Road

Cove Mountain

Clingmans Dome

Freels Bend
15

Rock, Clingmans Dome, and Cove Mountain) is 75.7 ppb while the average for the remaining, 

lower elevation monitors is 70.8 ppb (see Table 5).

Because the Cades Cove monitor is located in very close proximity to the Look Rock 

monitor but at a lower elevation, the Counties conducted a detailed analysis of back trajectories 

for the two sites on each day when the maximum 8-hour daily average ozone concentration at 

Look Rock exceeded 75 ppb. The back trajectories were computed using the National Oceanic 

and Atmospheric Administration’s HYSPLIT model. Figures 5-10 are examples of typical pairs 

of back trajectories ending when the ozone concentration was at its maximum at Look Rock, and 

Figures 11-13 are composites of the back trajectories for each of the three years, 2009-2011.
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Figure 6 – NOAA HYSPLIT Backyard Trajectory Ending at 2100 UTC 25 June 2009.
17

Figure 7 – NOAA HYSPLIT Backward Trajectory Ending at 2100 UTC 15 April 2010.
18

Figure 8 -- NOAA HYSPLIT Backward Trajectory Ending at 2100 UTC 6 May 2010.
19

Figure 9 – NOAA HYSPLIT Backward Trajectory Ending at 2000 UTC 8 July 2010.
20

Figure 10 -- NOAA HYSPLIT Backward Trajectory Ending at 1900 UTC 3 June 2011.
21

Figure 11 – NOAA HYSPLIT Backward Trajectory Ending at 2100 UTC 13 July 2011.
22

Figure 12 – NOAA HYSPLIT Model Composite Backward Trajectories for 2009.
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Figure 13 – NOAA HYSPLIT Model Composite Backward Trajectories for 2010.
24

Figure 14 – NOAA HYSPLIT Model Composite Backward Trajectories for 2011.
25

As can be seen from these examples, based only on back trajectories, the two monitors 

should generally be expected to be impacted by emissions from the same general areas. 

However, as pointed out above, the Cades Cove monitor is not violating the 2008 ozone 

NAAQS. In fact it has the lowest 2009-2011 design value in the Knoxville CSA. As graphically 

shown in Figures 3 and 4 above, the Cades Cove monitor exhibits a diurnal ozone pattern similar 

to those of the other lower elevation monitors, while the Look Rock monitor exhibits a diurnal 

pattern similar to the other higher elevation monitors. The monitor at Look Rock is being 

significantly impacted by regional transport of tropospheric ozone during the nighttime hours. 

Figure 15 shows a typical comparison of the diurnal ozone patterns at Look Rock and Cades 

Cove.

Figure 15 -- Comparison of Diurnal Ozone Patterns at Look Rock and Cades Cove.

The ozone concentration at Look Rock is already high early on the morning of May 6, 

2010 (67 ppb), while the concentration at Cades Cove is very low (12 ppb) due to the overnight 

deposition and destruction of ozone. As ozone is formed during the day, concentrations increase 

0

10

20

30

40

50

60

70

80

90

Ozone 

Concentration 

(ppb)

May 6, 2010 Time of Day

Look Rock

Cades Cove
26

dramatically at the Cades Cove monitor (to 78 ppb), while concentrations increase much less at 

Look Rock (to 82 ppb). However, with the coming of evening as the concentrations decline at 

Cades Cove, concentrations at Look Rock remain high as regional ozone is transported in and/or 

the nocturnal boundary layer isolates the higher elevations from the ozone destruction (titration) 

processes that occur at lower elevations. Consequently, the 8-hour average concentrations are 

higher at the higher elevations.

The data in Table 7 demonstrates the impact that higher overnight ozone concentrations 

have on the maximum 8-hour average concentration, and thus the ozone design value. At the 

Look Rock monitor the 8-hour average climbs above 75 ppb by 6 pm on May 6 and is still above 

75 the next morning, while the 8-hour average at Cades Cove never exceeds 73 ppb.

Table 7

Diurnal Ozone Concentrations at Look Rock and Cades Cove

May 5-7, 2010

Time Look Rock 

Ozone

(ppb)

Cades Cove 

Ozone

(ppb)

Look Rock 

Running 8-

Hour

Average

(ppb)

Cades Cove 

Running 8-

Hour Average

(ppb)

2300 86 33

0000 84 32

0100 73 40

0200 70 35

0300 69 26

0400 72 21

0500 72 16

0600 67 12 74 26

0700 64 18 71 25

0800 59 22 68 23

0900 60 48 66 24

1000 62 62 65 28

1100 68 69 65 33

1200 80 76 66 40

1300 81 76 67 47

1400 82 77 69 56

1500 79 78 71 63

1600 78 75 73 70
27

1700 77 75 75 73

1800 76 60 77 73

1900 80 50 79 70

2000 79 46 79 67

2100 80 39 78 62

2200 79 36 78 57

2300 76 29 78 51

0000 77 23 78 44

0100 76 18 77 37

0200 76 15 77 32

0300 75 14 77 27

0400 75 11 76 23

0500 76 12 76 19

The impact that this difference has over the course of all three ozone seasons (2009-2011) 

is illustrated by the data in Table 8. For each of the days during the three ozone seasons that the 

daily maximum 8-hour average ozone concentration at Look Rock exceeded 75 ppb, Table 8 lists 

the 6:00 AM ozone concentration for both Look Rock and Cades Cove, the maximum daytime 

hourly ozone concentration, and the daytime increase. The ozone concentration at Cades Cove 

was normally very low in the early morning, averaging only 9.0 ppb, while the early morning 

concentration at Look Rock was normally still high from the preceding day, averaging 64 ppb. 

Although daytime increases at Look Rock averaged less than the daytime increases at Cades 

Cove (20.4 versus 63.3 ppb), the resulting daytime ozone maximum hourly ozone concentration 

at Look Rock ended up much higher than Cades Cove and created an exceedance of the 8-hour 

ozone NAAQS. The exceedances of the 8-hour NAAQS were the result of the effects of the 

elevation of Look Rock.
28

Table 8 

Early Morning Ozone Concentrations at Look Rock and Cades Cove

With Daytime Increases

Date Look 

Rock

6:00 AM

Ozone

(ppb)

Cades Cove

6:00 AM

Ozone

(ppb)

Look 

Rock

Maximum

Daytime

Ozone

(ppb)

Cades 

Cove

Maximum

Daytime

Ozone

(ppb)

Look 

Rock

Daytime

Ozone

Increase

(ppb)

Cades 

Cove

Daytime

Ozone

Increase

(ppb)

6/25/09 65 2 93 73 28 71

4/2/10 68 16 80 84 12 68

4/13/10 69 31 79 79 10 48

4/14/10 72 21 86 81 14 60

4/15/10 66 17 80 76 14 59

5/5/10 65 5 74 64 9 59

5/6/10 67 12 82 78 15 66

7/7/10 49 2 82 74 33 72

7/8/10 62 6 95 80 33 74

9/2/10 60 6 84 77 24 71

9/21/10 53 2 69 62 16 60

10/11/10 62 2 79 69 17 67

6/2/11 53 10 93 70 40 60

6/3/11 72 7 95 79 23 72

6/4/11 77 9 98 72 21 63

6/6/11 48 2 92 66 44 64

6/30/11 63 2 84 69 21 67

7/1/11 80 3 87 65 7 62

7/2/11 74 11 68 64 -6 53

7/13/11 65 31 91 71 26 40

8/3/11 68 5 82 68 14 63

8/12/11 53 1 82 71 29 70

9/2/11 60 3 85 71 25 68

Averages 64.0 9.0 84.3 72.3 20.4 63.3

In its attachment to its December 8, 2011 letter to the State of Tennessee, EPA discussed 

the frequency of ozone hourly values greater than 75 ppb by wind direction and time of day for 

the Look Rock site. In that discussion, EPA presented a graphic (see Figure 4 of the “Technical 

Analysis for Knoxville-Sevierville-La Follette,” page 8) that showed that when hourly ozone 

concentrations exceed 75 ppb during the afternoon hours, the wind is predominantly from the 

north to northwest, while during the overnight hours the wind is predominantly from the
29

southeast to south-southeast. Although in the text of the discussion of this graphic EPA made a 

misstatement and reversed these directions, it drew the conclusion that this difference is further 

evidence that “both downwind urban ozone formation from Knoxville Knox County and high 

elevation regional transport of ozone contribute to NAAQS violations.”

Although EPA did not state what data it used in its analysis, the Counties assume it was 

either 2007-2010 or 2008-2010. Therefore, the Counties repeated the analysis using the 2009-

2011 ozone data for Look Rock. Figure 16 shows the results of that analysis.

Figure 16 – Frequency of Look Rock Ozone Hourly Values Greater Than 75 ppb by Wind 

Direction and Time of Day.

In addition to repeating EPA’s analysis, the Counties also looked at the wind direction by 

time of day for the hours when the ozone concentration at Look Rock was 66-75 ppb. That 

analysis is depicted in Figure 17.
30

Figure 17 – Frequency of Look Rock Ozone Hourly Values 66-75 ppb by Wind Direction 

and Time of Day.

The Counties also constructed a wind rose based on CastNet data for the ozone seasons of 2009-

2011. That wind rose is shown in Figure 18.
31

Figure 18 -- Wind Direction Percentage for Look Rock, Ozone Season, 2009-2011, Daytime 

Only.

Based on all these analyses, the Counties concluded, as EPA did, that there appears to be 

a change in wind direction in the evening with the wind coming from the south-southeast when 

the ozone concentrations exceed 75 ppb. However, from the analyses shown in Figures 17 and 

18, it appears that this same phenomenon not only also occurs when the ozone concentrations are 

66-75 ppb, but also appears to occur almost every day. The Counties attributed this occurrence 

to the settling in the early evening of the nocturnal boundary layer to an elevation below the 

elevation of the Look Rock monitor and the subsequent rush of air down the slope to the northnortheast from the top of the ridge (causing the wind direction to change to “from” the south 

southeast). This behavior is typical of a high elevation site.

0

2

4

6

8

10

12

14

16

18

N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

WD%_n=8744
32

The Counties drew two additional conclusions from the wind rose shown in Figure 18. 

First, examining the predominant wind directions measured at the Look Rock monitor (Figure 

18) and comparing them to the predominant wind directions shown in Figure 2, which were 

measured at the Knoxville McGhee Tyson Airport, one finds that wind directions at Look Rock 

are markedly different. While the primary predominant wind direction measured at the Look 

Rock monitor was from the south-southeast with a secondary predominant direction being the 

northwest to north-northwest, as EPA pointed out in its analysis, the primary predominant wind 

direction for the Knoxville Airport is southwest to west-southwest with a secondary predominant 

direction of north to north-northeast. 

The second conclusion drawn from the wind rose shown in Figure 18 is that there are no 

significant sources of emissions in any of the counties EPA intends to designate as nonattainment 

in the south-southeast direction from Look Rock and no major sources of emissions in the 

northwest direction from Look Rock, except the Bull Run Power Plant. As stated earlier (see 

Table 6), the Bull Run Power Plant has state-of-the-art NOX controls (selective catalytic 

reduction) that are reducing emissions significantly. Consequently, there has been a dramatic 

decline in emissions and emission rate since 2008. The major urban centers and transportation 

corridors in the Knoxville CSA are located from north northwest to north northeast of the Look 

Rock monitor.

CONCLUSION

The urban areas and major transportation corridors in the Knoxville CSA are well 

surrounded by ozone monitors: Freels Bend in Anderson County to the west; Lost Creek Road in 

Jefferson County and Rutledge Pike in Knox County to the north; Clingmans Dome and Cove 

Mountain in Sevier County to the east; and Roberts Road in Loudon County and Cades Cove and 
33

Look Rock in Blount County to the south. In addition there is a monitor in the midst of that 

urban and transportation area: Mildred Drive in Knox County. (See Figure 1.)

Based on the 2009-2011 design values (see Table 5) there is only one monitor out of nine 

in the Knoxville CSA that measured an exceedance of the 2008 ozone NAAQS. That monitor 

was the Look Rock monitor in Blount County. The Look Rock monitor is a high elevation, ridge 

top monitor located at an elevation of approximately 2700 feet above MSL.

The Cades Cove monitor is located just nine miles from the Look Rock monitor in the 

same county. The Cades Cove monitor is located at an elevation of approximately 1850 feet 

above MSL. Both monitors are located in remote locations in the Great Smoky Mountains 

National Park. Both monitors have very similar back trajectories on every day when the 

maximum 8-hour ozone concentration at Look Rock exceeded 75 ppb.

Although the two Blount County monitors are located in close proximity and share the 

same back trajectories, their characteristics are very different entirely as a result of the elevation 

at which each monitor is located.

In the late afternoon as the sun begins to set, ozone concentrations at the Cades Cove 

monitor begin to rapidly decline due to surface deposition and ozone destruction. This results in 

a rapid lowering of the 8-hour average ozone concentration. At the Look Rock monitor, on the 

other hand, during the evening hours as the nocturnal boundary layer settles below the elevation 

of the monitor, the air around the monitor is cut off from the titration reactions that destroy 

ozone. Consequently, 8-hour average ozone concentrations remain higher, sometime resulting in 

exceedances of the NAAQS.
34

The diurnal ozone patterns at the Clingmans Dome and Cove Mountain monitors appear 

to be similar to Look Rock, while the diurnal patterns at the remainder of the monitors in the 

Knoxville CSA appear to be similar to Cades Cove.

The major urban areas and primary transportation corridors of the Knoxville CSA, as 

well as all but one of the major stationary sources of emissions are not located in either of the 

predominant wind directions from the Look Rock monitor, making it unlikely that they 

contribute significantly to ozone concentrations at Look Rock.

Eight of the nine monitors in the Knoxville CSA, located within and in a ring around the 

major urban areas and transportation corridors, did not measure an exceedance to the ozone 

NAAQS, and the one monitor that did measure an exceedance the 8-hour daily averages is 

clearly impacted by elevation; therefore, local emissions in the Knoxville CSA are not causing 

exceedances of the ozone NAAQS.

It is clear that the effect of elevation is the primary cause of the higher number of daily 

maximum 8-hour averages exceeding the NAAQS at the Look Rock monitor. It is not 

appropriate, as EPA concluded, to designate all of Anderson, Blount, Knox, Loudon, and Sevier 

Counties and a portion of Cocke County as nonattainment based only on a design value 

exceeding the NAAQS at one monitor that is so strongly influenced by elevation. Therefore, 

Anderson, Blount, and Knox Counties should have been designated attainment, or (2) 

alternatively, only the portion of Blount County within the boundaries of the Great Smoky 

Mountains National Park should have been designated nonattainment. Thus, EPA acted 

arbitrarily, capriciously, and in abuse of its discretion in designating all of Blount County and 

Knox County, as well as a portion of Anderson County, nonattainment.