MIDDLE TENNESSEE

110(a)(1) MAINTENANCE PLAN

July, 2010

Pre-Hearing Draft

Prepared by:

Metro Nashville/Davidson County

Pollution Control Division Office

Lentz Public Health Center

Room 208

311 23rd Avenue North

Nashville, TN 37203

and

Tennessee Department of Environment and Conservation

Division of Air Pollution Control 

9th Floor L&C Annex

401 Church Street 

Nashville, TN 37243
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page i

TABLE OF CONTENTS

1.0 Background ........................................................................................................... 1

2.0 Attainment Inventory.............................................................................................. 2

3.0 Maintenance Demonstration.................................................................................. 2

3.1 Point Source Emissions......................................................................................... 3

3.2 Area Source Emissions ......................................................................................... 4

3.3 Onroad Mobile Source Emissions ......................................................................... 5

3.4 Nonroad Source Emissions ................................................................................... 6

4.0 Ambient Air Quality Monitoring .............................................................................. 9

5.0 Contingency Plan ................................................................................................ 10

6.0 Verification of Continued Attainment ................................................................... 11

7.0 Conclusion........................................................................................................... 12
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page ii

LIST OF APPENDICES

Appendix A: Point Source Emissions Inventory 

Appendix B: Area Source NOx and VOC Emissions for Davidson, Rutherford, Sumner, 

Williamson and Wilson Counties

Appendix C: Onroad Mobile Source NOx and VOC Emissions for Davidson, Rutherford, 

Sumner, Williamson and Wilson Counties

Appendix D: Nonroad Source NOx and VOC Emissions for Davidson, Rutherford, 

Sumner, Williamson and Wilson Counties

Appendix E: Public Notice

Appendix F: Comments Received
110(a)(1) MAINTENANCE PLAN

FOR THE 1997 8-HOUR OZONE NAAQS FOR THE

MIDDLE TENNESSEE 8-HOUR OZONE MAINTENANCE AREA

1.0 Background

This document contains the 110(a)(1) maintenance plan for the 1997 Middle Tennessee 

Early Action Compact (EAC) maintenance area. This maintenance plan is being 

submitted in accordance with, and to satisfy, the requirements of the EPA guidance 

document Maintenance Plan Guidance Document for Certain 8-Hour Ozone Areas 

Under Section 110(a)(1) of the Clean Air Act, May 20, 20051. 

On July 18, 1997, the U.S. Environmental Protection Agency (EPA) revised the National 

Ambient Air Quality Standard (NAAQS) for ground-level ozone from a 0.12 ppm (parts 

per million) 1-hour standard to a 0.085 ppm 8-hour average standard. The Middle 

Tennessee area was not attaining the more stringent standard on April 15, 2004, 

therefore, the Greater Nashville Area was faced with a pending designation of 

nonattainment.

The EPA offered a new option of reaching attainment earlier than would be required by 

the Clean Air Act’s (CAA) conventional nonattainment route. Certain areas were 

allowed to opt into a voluntary program called an Early Action Compact (EAC). The 

EPA offered to defer the effective date of air quality nonattainment designations for 

these areas if they met the qualifications to participate in the EAC. Specifically, the area 

had to develop a plan to bring the area’s ozone design value to an attaining level by 

2007. This plan had to contain a modeling demonstration that the area’s projected 

emissions inventory in 2007 would lead to attaining the 8-hour Ozone NAAQS. 

Davidson, Rutherford, Sumner, Williamson and Wilson Counties chose to participate in 

the Early Action Compact. Through the region’s efforts to proactively address ozone air 

quality, a demonstration was made that the area was expected to attain the new 

standard by 2007. As a result of the proactive effort, the Middle Tennessee area met 

the EAC requirements, demonstrating attainment with the 8-hour NAAQS of 0.085 ppm.

The primary intent of this 110(a)(1) maintenance plan submittal is to demonstrate that 

the projected emissions through 2018 do not exceed those of the attainment year, 2007. 

If this demonstration can be made, it can then be concluded that the region should be 

able to maintain the 1997 8-hour ozone NAAQS through the maintenance period.

The basic maintenance plan requirements included in the Maintenance Plan Guidance 

Document for Certain 8-Hour Ozone Areas Under Section 110(a)(1) of the Clean Air Act

are:

1. Development of an attainment inventory (Section 2);

2. Development of a maintenance demonstration (Section 3);

 

1US EPA, Lydia Wegman, May 20, 2005. Memorandum and Guidance Document: Maintenance Plan 

Guidance Document for Certain 8-hour Ozone Areas Under Section 110(a)(1) of Clean Air Act.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 2

3. Commitment to continue air quality monitoring (Section 4);

4. Development of a contingency plan (Section 5; and,

5. Verification of continued attainment (Section 6).

2.0 Attainment Inventory

The attainment inventory should be an inventory for a “typical summer day” for 

emissions of oxides of nitrogen, or NOx and volatile organic compounds, or VOCs. The 

attainment year was 2007. A comprehensive and up-to-date analysis of emissions in 

the Middle Tennessee area was conducted for 2007. This analysis included an update 

of the emission inventories including updated county-specific emissions data with the

use of the latest EPA tools for estimating onroad mobile and nonroad emissions.

Data aggregated to the categories of point, area, onroad, nonroad and ALM (Aircraft, 

Locomotive and Commercial Marine) emissions for 2007 are summarized in Table 1

and Table 2, below. 

Table 1. 2007 NOx Emissions in Middle Tennessee.

Point Area Onroad Nonroad ALM Total

Davidson 11.52 0.62 45.70 9.57 3.35 70.76

Rutherford 0.33 2.79 17.29 5.45 1.26 27.11

Sumner 18.74 0.24 6.07 2.57 0.78 28.41

Williamson 0.06 0.86 12.60 3.58 1.36 18.47

Wilson 0.00 1.23 13.12 2.19 0.15 16.68

Total 30.65 5.75 94.79 23.36 6.90 161.44

--- NOx emissions (tons/day) ---

Table 2. 2007 VOC Emissions in Middle Tennessee.

Point Area Onroad Nonroad ALM Total

Davidson 5.05 20.98 17.73 15.06 0.60 59.42

Rutherford 5.97 11.02 6.65 4.44 0.20 28.28

Sumner 0.97 6.78 3.53 2.68 0.08 14.05

Williamson 0.31 6.00 5.05 2.64 0.07 14.06

Wilson 0.00 4.88 3.32 4.80 0.05 13.04

Total 12.31 49.66 36.27 29.62 1.00 128.85

--- VOC emissions (tons/day) ---

3.0 Maintenance Demonstration

A key element of a maintenance plan is a demonstration of how the area will remain in

compliance with the 8-hour ozone standard for the 10 year period following the effective 

date of designation as attainment. Emissions for several interim years are estimated to 

illustrate the trend between the attainment year and the final year of the maintenance 

plan. These interim years are illustrated to demonstrate that emissions are not 

expected to increase, above those for 2007, before the final year of the maintenance 
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 3

plan. The results for 2010 and 2014 show additional reductions in the ozone precursors 

compared to 2007. The expected emission reductions (reflecting local and national 

measures) provide for further improvement in ozone air quality and maintenance of the

0.085 ppm 1997 8-hour ozone NAAQS in the Middle Tennessee area.

The maintenance demonstration is made for an area when the expected future 

emissions from all sources in the same geographic area are less or equal throughout 

the maintenance period as compared to the attainment year (in this case 2007). Each 

source sector’s emissions are estimated and projected using the latest tools available, 

and the most current planning assumptions available at the time of the analysis. Each 

sector; point, area, onroad, nonroad and ALM are evaluated individually.

3.1 Point Source Emissions

The 2007 point source emissions for Rutherford, Sumner, Williamson, and Wilson 

Counties were developed from the State of Tennessee’s 2007 Annual Emission 

Inventory. The Annual Emission Inventory is based on information provided by each of 

the companies as per division rules to supply requested data. Davidson County’s 2007 

point source emissions were developed from the SEMAP (Southeastern Modeling, 

Analysis and Planning) inventory, which is based on data supplied by the Metropolitan 

Nashville/Davidson County Public Health Department, Pollution Control Division. 

Future year growth for the Middle Tennessee point sources was based on the EGAS

(Economic Growth Analysis System 5.0) projections where growth potential existed. 

The EGAS projections were applied at the SCC (Source Code Classification) level for 

point sources.

Future-year emissions were projected for 2010, 2014 and 2018, using 2007 emissions 

and economic growth factors from EPA’s Economic Growth and Analysis System 

(EGAS 5.0). Growth factors were determined using the Default REMI 6.0 SCC 

Configuration and user-selected base and future years.

In 2009, E. I. du Pont de Nemours and Company located in Davidson County closed

down large parts of the facility. This resulted in decreases in VOC emissions and a 

large decrease in plant steam requirements. The corresponding reduction in steam 

production meant it would no longer be efficient for the facility to burn coal in their large 

boilers. These changes to their method of operation will result in further Davidson 

County point source actual emission decreases of 4.3 tons of NOx and 0.4 tons of VOC 

per ozone season day. This additional decrease in emissions further supports the fact 

that the Middle Tennessee area will continue to maintain the 8-hour ozone NAAQS well 

into the future.

Table 3 illustrates point source emissions by county projected through 2018 for both 

NOx and VOC.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 4

Table 3. Point Source Emissions for Middle Tennessee

NOx VOC NOx VOC NOx VOC NOx VOC

Davidson 11.52 5.05 11.15 4.95 12.34 5.19 12.26 5.64

Rutherford 0.33 5.97 0.34 6.26 0.36 6.68 0.39 7.40

Sumner 18.74 0.97 18.79 0.98 18.83 1.01 18.90 1.13

Williamson 0.06 0.31 0.06 0.30 0.05 0.30 0.06 0.33

Wilson 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Total 30.65 12.31 30.33 12.49 31.59 13.18 31.61 14.50

2007 2010 2014 2018

County --- tons/typical summer day ---

3.2 Area Source Emissions

The 2007 State of Tennessee area source emissions estimates for Rutherford, Sumner, 

Williamson, and Wilson Counties were largely based on published or locally available 

energy or fuel consumption data for 2007. The area source emission inventory was 

developed using EPA Nonpoint files located on EPA’s CHIEF Emission Inventory 

website for the 2008 NEI and from Appendix A of the documentation for the Final 2002 

Nonpoint Sector (February 2006 version) National Emission Inventory for Criteria and 

Hazardous Air Pollutants. Davidson County area source emissions estimates were 

developed from the SEMAP (Southeastern Modeling, Analysis, and Planning) inventory, 

which is based on data supplied by the Metropolitan Nashville/Davidson County Public 

Health Department, Pollution Control Division.

Future-year emissions were projected for 2010, 2014, and 2018 using 2007 emissions 

and EGAS growth factors. Growth factors obtained from EGAS were multiplied by the 

2007 emission values to calculate emissions for future years.

It should be noted that Davidson County has historically used a very low cutpoint to 

distinguish point sources from area (nonpoint) sources. Davidson County routinely 

permits sources with permitted emissions at or below one ton per year. For these 

sources, actual emissions are often lower. For this reason Davidson County includes 

many sources in the point source emissions inventory that might otherwise be include in 

an area (nonpoint) source inventory.

Table 4 illustrates area source emissions projected through 2018 for NOx and VOCs for 

the Middle Tennessee Maintenance Area.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 5

Table 4. Area Source Emissions for Middle Tennessee.

NOx VOC NOx VOC NOx VOC NOx VOC

Davidson 0.62 20.98 0.67 21.87 0.70 23.10 0.73 24.61

Rutherford 2.79 11.02 2.83 11.40 2.91 11.96 2.98 12.80

Sumner 0.24 6.78 0.25 7.00 0.26 7.35 0.28 7.89

Williamson 0.86 6.00 0.88 6.20 0.91 6.50 0.94 6.89

Wilson 1.23 4.88 1.24 5.00 1.28 5.22 1.31 5.57

Total 5.75 49.66 5.88 51.48 6.07 54.14 6.25 57.77

County 

2007 2010 2014 2018

--- tons/typical summer day ---

3.3 Onroad Mobile Source Emissions

The onroad mobile source emissions were prepared using MOBILE6.2. The Tennessee 

Department of Transportation provided 2007 county-level daily Vehicle Miles Traveled 

(VMT) by functional classes. Vehicle Miles Traveled for 2018 were provided by the 

Nashville Metropolitan Planning Organization. VMT for 2010 and 2014 were 

interpolated by functional class between 2007 and 2018. More detailed information on 

how onroad emissions were estimated is contained in Appendix C.

Seasonal adjustment factors (contained in Appendix C) were applied to daily average 

vehicle miles traveled to estimate summer season travel activity. Appendix C contains 

the seasonally adjusted daily vehicle miles travelled for 2007 and 2018.

The most current version of the MOBILE model (MOBILE6.2) was used with locally 

specific inputs in order to generate an onroad mobile emission inventory for Middle 

Tennessee. VMT mix fractions used in the model runs were provided by the Tennessee 

Department of Transportation for each roadway type. Average speed by facility type 

was provided by the Nashville Metropolitan Planning Organization. Seasonal summer 

adjustment factors were used to adjust the Annual DVMT (Daily Vehicle Miles Traveled) 

to summer DVMT as illustrated in Table 5. Local inspection and maintenance program 

inputs are used to represent the effects of the local Motor Vehicle Inspection Program. 

Table 5. 2007 Seasonally Adjusted Daily Vehicle Miles Traveled.

2007 County Total

County (miles/typical summer day)

Davidson 22,860,287

Rutherford 7,866,899

Sumner 4,114,823

Williamson 6,098,989

Wilson 4,270,673

Total 45,211,670
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 6

Table 6 illustrates a drastic decrease in onroad emissions for both NOx and VOCs from 

the five county Middle Tennessee Maintenance Area. Oxides of nitrogen (NOx) are 

expected to decrease nearly seventy percent from 2007 through 2018, while volatile 

organic compounds (VOCs) are expected to decrease over fifty percent during the 

same period.

Table 6. Onroad Emissions for Middle Tennessee.

NOx VOC NOx VOC NOx VOC NOx VOC

Davidson 45.70 17.73 36.38 14.78 26.46 10.75 11.51 6.91

Rutherford 17.29 6.65 14.34 5.54 10.43 4.03 6.46 2.59

Sumner 6.07 3.53 4.93 2.94 3.59 2.13 1.91 1.35

Williamson 12.60 5.05 10.44 4.36 7.59 3.17 4.66 2.52

Wilson 13.12 3.32 10.63 2.82 7.73 2.05 3.98 1.48

Total 94.79 36.27 76.72 30.43 55.79 22.13 28.53 14.84

County 

2007 2010 2014 2018

--- tons/typical summer day ---

3.4 Nonroad Source Emissions

Middle Tennessee county-level emission estimates for the majority of nonroad mobile 

source emissions were developed using EPA’s NONROAD2008 model. Emissions 

from Aircraft, Locomotives and Commercial Marine (ALM) sources were obtained from 

E. H. Pechan & Associates, Inc., the contractor for the Southeastern Modeling, 

Analysis, and Planning (SEMAP) project. Future year ALM sources were developed by 

growing the base year 2007 emissions by the appropriate EGAS growth factors. 

Table 7 contains the projected inventory for nonroad mobile sources including 

construction, agriculture, pleasure marine and lawn care equipment. Both NOx and 

VOCs are expected to decrease nearly fifty percent from 2007 through 2018 as 

projected by EPA’s Nonroad emissions model.

Table 7. Nonroad Emission for the Middle Tennessee.

NOx VOC NOx VOC NOx VOC NOx VOC

Davidson 9.57 15.06 8.72 13.06 6.79 10.22 5.22 8.63

Rutherford 5.45 4.44 4.81 3.92 3.66 3.10 2.66 2.53

Sumner 2.57 2.68 2.31 2.23 1.81 1.61 1.39 1.27

Williamson 3.58 2.64 3.25 2.29 2.53 1.80 1.87 1.57

Wilson 2.19 4.80 1.99 4.37 1.59 3.53 1.23 2.71

Total 23.36 29.62 21.08 25.87 16.38 20.27 12.37 16.70

County 

2007 2010 2014 2018

--- tons/typical summer day ---

Table 8 contains estimates for the more commercial and industrial nonroad mobile 

types of equipment including all aircraft, locomotives and commercial marine vessels. 

Slight increases are potentially expected from these sources, although they are a 

relatively small component of the overall inventory.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 7

Table 8. Aircraft, Locomotive and Commercial Marine (ALM) Emissions for Middle Tennessee.

NOx VOC NOx VOC NOx VOC NOx VOC

Davidson 3.35 0.60 3.66 0.66 4.10 0.74 4.54 0.82

Rutherford 1.26 0.20 1.15 0.21 1.07 0.22 0.99 0.24

Sumner 0.78 0.08 0.72 0.09 0.67 0.09 0.63 0.09

Williamson 1.36 0.07 1.25 0.06 1.15 0.06 1.07 0.05

Wilson 0.15 0.05 0.14 0.05 0.13 0.06 0.13 0.07

Total 6.90 1.00 6.93 1.07 7.12 1.17 7.36 1.27

County 

2007 2010 2014 2018

--- tons/typical summer day ---

3.5 Total Projected Emissions

Comparing the 2007 inventory and the projected future inventories clearly supports

continued maintenance of the 1997 8-hour ozone standard. Table 9 and Table 10

tabulate the total emissions of NOx and VOCs in Middle Tennessee from 2007 through 

2018. Figure 1 and Figure 2 illustrate this trend graphically.

Table 9. Total Projected NOx Emissions for Middle Tennessee.

2007 2010 2014 2018

Point 30.65 30.33 31.59 31.61

Area 5.75 5.88 6.07 6.25

Onroad 94.79 76.72 55.79 28.53

Nonroad 23.36 21.08 16.38 12.37

ALM 6.90 6.93 7.12 7.36

Total 161.44 140.93 116.95 86.11

--- NOx emissions (tons/day) ---

Table 10. Total Projected VOC Emissions for Middle Tennessee.

2007 2010 2014 2018

Point 12.31 12.49 13.18 14.50

Area 49.66 51.48 54.14 57.77

Onroad 36.27 30.43 22.13 14.84

Nonroad 29.62 25.87 20.27 16.70

ALM 1.00 1.07 1.17 1.27

Total 128.85 121.34 110.88 105.07

--- VOC emissions (tons/day) ---

Through the span of approximately ten years beginning in 2007, reductions in NOx are 

expected to decrease by nearly half, most of which is expected to come from the onroad 

mobile sector. Volatile organic compounds are expected to decrease nearly twenty 

percent during the same period.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 8

Figure 1. Projected NOx Emissions for Middle Tennessee.

0

2 0

4 0

6 0

8 0

100

120

140

160

180

2007 2010 2014 2018

NOx emissions (tons/day)

Middle Tennessee NOx Emissions

Total NOx

Onroad

Point

Nonroad

Area

ALM

Figure 2. Projected VOC Emissions for Middle Tennessee.

0

2 0

4 0

6 0

8 0

100

120

140

2007 2010 2014 2018

VOC emissions (tons/day)

Middle Tennessee VOC Emissions

Total VOC

Area

Onroad

Nonroad

Point

ALM

Per the EPA section 110(a)(1) guidance document, the key element of a maintenance 

plan is a demonstration of how the area will remain in compliance with the 8-hour ozone 

NAAQS for the 10 year period following the effective date of designation to attainment. 

As can be seen from the above tables and figures, emissions of both ozone precursors, 

NOx and VOCs are expected to decrease considerably during the maintenance period. 

These expected reductions in ozone forming pollutants ensure continued maintenance 

of the ozone standard.

The 110(a)(1) Maintenance Plan Guidance indicates that the principal mechanism for 

demonstrating continued attainment is a projected future inventory. This emissions 

inventory uses the most current information available to develop and project the base

and future-year emissions inventories. Based on these projections and no direct 

knowledge to the contrary, emissions of NOx and VOC are projected to decrease 

significantly between 2007 and 2018. Oxides of Nitrogen (NOx) is expected to 

decrease approximately fifty percent from 2007 to 2018 for the Middle Tennessee Area 
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 9

(Davidson, Rutherford, Sumner, Williamson and Wilson Counties). Similarly, Volatile 

Organic Compounds (VOCs) are expected to decrease approximately twenty percent 

over the same time frame. The projections of ozone forming precursor pollutants 

convincingly demonstrate that the area will likely maintain the 1997 8–hour ozone 

NAAQS. 

4.0 Ambient Air Quality Monitoring

Ambient air quality monitoring has been conducted at several locations throughout the 

Middle Tennessee Maintenance Area. Air quality has steadily improved (as indicated 

by the three year design value – the official measure of air quality) over time as 

indicated in Table 11. Since 2007, the three year design value has decreased from 84 

parts per billion (ppb) to 78 ppb in 2009. 

Table 11. Middle Tennessee 8-Hour

Ozone Design Value History.

Years

Design Value

(ppb)

1994 – 1996 99

1995 – 1997 99

1996 – 1998 101

1997 - 1999 102

1998 - 2000 100

1999 - 2001 93

2000 - 2002 88

2001 - 2003 86

2002 – 2004 83

2003 – 2005 82

2004 – 2006 83

2005 – 2007 84

2006 – 2008 84

2007 – 2009 78

The three year design values in Table 11 are plotted in Figure 3. Figure 3 illustrates a 

general downward trend in the ozone design value. If this trend is extrapolated linearly, 

a continued downward trend is expected beyond 2018.

Davidson County and the State of Tennessee agree to continue to operate air quality 

monitors in accordance with 40 CFR 58 to verify maintenance of the 8-hour ozone 

NAAQS in the Middle Tennessee Maintenance Area. Any modification to the ambient 

air monitoring network will be accomplished through close consultation with EPA.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 10

Figure 3. Middle Tennessee 8-Hour Ozone Design Value Trend.

6 0

6 5

7 0

7 5

8 0

8 5

9 0

9 5

100

105 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018Ozone Concentration (ppb)

Middle Tennessee 8-Hour Ozone Design Value Trend

Design Value

Linear (Design Value)

5.0 Contingency Plan

Section 110(a)(1) guidance requires the development of a contingency plan that will 

ensure a violation of the 8-hour ozone NAAQS is identified, addressed and corrected in 

an expeditious a manner as possible.

Triggers for implementation of the contingency plan:

1. Quality assured ambient air quality monitoring data showing a violation of the

1997 8-hour ozone NAAQS; or,

2. An increase in ozone precursor emissions of at least 10% over the emissions for 

the attainment year of 2007.

If one of the above triggers occurs, one or more of the following control measures will 

be adopted to reduce ozone precursor emissions:

1. Expand NOx and/or VOC control strategies in the Middle Tennessee 

Maintenance area; 

2. In conjunction with the State of Tennessee, implement mobile source 

transportation controls such as reduced speed limits for heavy duty diesel 

vehicles;

3. Lower major source thresholds; 

4. Expand the open burning ban in Davidson County to include homeowners in the 

General Services area; 

5. Implement anti-idling legislation; and,

6. Any other control measure determined to be appropriate at the time a trigger is 

exceeded.
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 11

Davidson County and the State of Tennessee will use one or more of the following 

parameters to determine the most efficient emissions reduction strategy:

1. The severity and duration of the violation; or, 

2. The cost effectiveness of the controls; or, 

3. The time needed for full implementation; or

4. Any other considerations that may be appropriate at the time. 

Davidson County and the State of Tennessee commit to the adoption and 

implementation of the necessary control measure(s) as expeditiously as practicable. All 

reasonable efforts will be made to complete the process in 24 months or less. 

Table 12 is an example schedule the Middle Tennessee area would strive to follow 

should additional control measures be required to continue maintenance of the 1997 8-

hour ozone NAAQS.

Table 12. Contingency Measure Implementation Schedule.

Action

Implementation 

Schedule

Trigger – violation of the 1997 8-hour Ozone NAAQS

documented by quality assured data or an increase in emissions 

greater than ten percent over the 2007 projected emissions

Evaluation of available control measures 6 months

Selection of control measures 9 months

Begin rulemaking or initiation of control measure 12 months

Implement new rule or control measure 24 months

6.0 Verification of Continued Attainment

Davidson County and the State of Tennessee will track the progress of the Middle 

Tennessee Maintenance Plan. Since the maintenance demonstration relied on 

modeling that was heavily dependent on a comprehensive and accurate ozone 

precursor emissions inventory, the inventory will be periodically updated.

Table 11 demonstrates that the Middle Tennessee area attained the 1997 8-hour ozone 

NAAQS, and the area’s ozone design value continues to demonstrate maintenance of 

the standard. As shown in Figure 1 and Figure 2, projected levels of VOC and NOx 

emissions continue to decrease during the maintenance period. As stated above, 

Davidson County and the State of Tennessee have no knowledge of any emissions 

occurrence or trend that would indicate any conclusion other than the area will remain in 

attainment with the 8-hour ozone NAAQS to 2018 and for the foreseeable future 

beyond. 

The ozone precursor emissions shown in Table 9 and Table 10 for the interim projection 

years of 2010 and 2014 demonstrate that it is unlikely the area will violate the 1997 8-
MIDDLE TENNESSEE 110(a)(1) MAINTENANCE PLAN Page 12

Hour ozone NAAQS due to increases in emissions. Davidson County and the State of 

Tennessee will monitor regional emissions through the Consolidate Emissions 

Reporting Rule’s (CERR) periodic emissions inventory submissions. If the CERR 

results indicate that the projected emissions in this maintenance plan are significantly 

less than the CERR reveals (more than 10 percent), Davidson County and the State of 

Tennessee will investigate the differences and develop an appropriate strategy for 

addressing these differences. 

Davidson County and the State of Tennessee believe these additional interim year 

evaluations should provide timely documentation of continued maintenance, and, along 

with quality assured ambient air quality monitoring data, ample opportunity to correct a 

violation of the 1997 8-hour ozone NAAQS.

7.0 Conclusion

In reviewing this maintenance plan, Davidson County and the State of Tennessee 

request that EPA consider the following:

1. Total projected VOC and NOx emissions demonstrate a continued downward 

trend from 2007 through 2018; 

2. A significant facility (E.I. DuPont) had a major NOx reduction of 4.3 tons per 

ozone season day in 2009 due to the permanent shutdown of a portion of their 

facility; 

3. The inventory indicates continued maintenance of the 1997 8-hour ozone 

NAAQS. Figure 3 shows the actual and anticipated trend of the Middle 

Tennessee Maintenance Area 8-hour ozone design value through 2018. There 

are certainly no guarantees that the design value will continue to decline at the 

rate indicated by the trend line, however, there is ample evidence to indicate the 

air quality improvements are real and should continue to yield positive results into 

the foreseeable future;

4. Quality assured ambient air monitoring data proves continued attainment of the 

1997 8-hour ozone NAAQS through 2009. Table 11 shows the history of Middle 

Tennessee 8-hour ozone design values demonstrating that the area attained and 

continues to maintain the 8-hour ozone NAAQS of 0.085 ppm; and,

5. Based on historical and projected data, a downward trend in emissions is 

expected, resulting in lower emissions in 2018 as compared to 2007.

This information is submitted as documentation that the Middle Tennessee 1997 8-hour 

Ozone Maintenance Area is currently attaining the 1997 8-hour ozone NAAQS and will 

continue to maintain that standard based on all available information. Based on the 

projected ozone concentration trend shown in Figure 3, ozone levels in the area will 

continue to decrease and monitored ozone air quality data will continue to improve 

through 2018.