Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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For the Portion of DeSoto County, Mississippi included in the TN‐MS‐AR

Marginal Nonattainment Area for the 2008 Ozone NAAQS  

MISSISSIPPI

DEPARTMENT OF

ENVIRONMENTAL

QUALITY

Redesignation Request and Maintenance Plan

for DeSoto County, Mississippi, Adopted

December 2, 2015
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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Contents

INTRODUCTION.............................................................................................................................................5

Request for Redesignation........................................................................................................................ 5

Ground‐Level (Tropospheric) Ozone......................................................................................................... 5

National Ambient Air Quality Standards (NAAQS).................................................................................... 5

2008 8‐Hour Ozone NAAQS ...................................................................................................................... 6

2008 8‐Hour Ozone Designations............................................................................................................. 6

Clean Air Act Redesignation Criteria......................................................................................................... 6

AIR QUALITY..................................................................................................................................................8

Geography and Topography ..................................................................................................................... 8

Ozone Design Value Trend........................................................................................................................ 8

Meteorology ...........................................................................................................................................10

PERMANENT AND ENFORCEABLE REDUCTIONS IN EMISSIONS ................................................................. 16

MAINTENANCE PLAN ..................................................................................................................................18

DeSoto County, Mississippi Maintenance Plan....................................................................................... 18

Established Control Measures ................................................................................................................ 19

Federal Control Measures................................................................................................................... 19

Emissions Inventory ................................................................................................................................20

Types of Emission Inventories............................................................................................................. 21

Maintenance Demonstration.................................................................................................................. 23

Summary of Emissions........................................................................................................................ 23

Contingency Plan ....................................................................................................................................26

Overview .............................................................................................................................................26

Contingency Plan Trigger .................................................................................................................... 26

Contingency Measures........................................................................................................................ 27

Action Resulting from Trigger Activation............................................................................................ 27

Tracking for Ongoing Maintenance .................................................................................................... 27

Motor Vehicle Emissions Budgets and Safety Margin ............................................................................ 29

Safety Margin......................................................................................................................................29

Motor Vehicle Emissions Budgets....................................................................................................... 29
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DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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APPENDIX A: POINT SOURCE EMISSIONS ................................................................................................... 31

Point Sources ..........................................................................................................................................32

APPENDIX B: NON‐POINT SOURCE EMISSIONS........................................................................................... 34

Non‐Point Sources ..................................................................................................................................35

APPENDIX C: NON‐ROAD MOBILE EMISSIONS............................................................................................ 37

Non‐Road Mobile Sources ...................................................................................................................... 38

MOVES Model Inputs.............................................................................................................................. 39

APPENDIX D: ON‐ROAD MOBILE EMISSIONS .............................................................................................. 41

Introduction ............................................................................................................................................43

Latest Planning Assumptions.................................................................................................................. 43

Latest Emissions Estimation Model ........................................................................................................ 44

Methodology...........................................................................................................................................44

MOVES ....................................................................................................................................................45

Travel Demand Modeling........................................................................................................................ 45

Model Data Adjustments.................................................................................................................... 46

Pre‐Processing.....................................................................................................................................48

Post‐Processing...................................................................................................................................48

MOVES Runspec......................................................................................................................................49

Description..............................................................................................................................................49

Scale ........................................................................................................................................................49

Time Spans..............................................................................................................................................49

Geographic Bounds.................................................................................................................................49

Vehicles/Equipment................................................................................................................................49

Road Type ...............................................................................................................................................50

Pollutants and Processes ........................................................................................................................ 50

Miscellaneous Strategies ........................................................................................................................ 50

Output.....................................................................................................................................................50

County Data Manager............................................................................................................................. 50

Meteorology Data Importer.................................................................................................................... 50

Source Type Population Importer........................................................................................................... 50
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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Age Distribution Importer....................................................................................................................... 51

Vehicle Type VMT and VMT Fractions.................................................................................................... 51

HPMS Vehicle Class VMT .................................................................................................................... 51

Daily VMT Fraction.............................................................................................................................. 51

Monthly VMT Fraction........................................................................................................................ 51

Hourly VMT Fraction........................................................................................................................... 51

Average Speed Distribution Importer..................................................................................................... 52

Road Type Distribution Importer............................................................................................................ 52

Ramp Fraction Importer.......................................................................................................................... 52

Fuel Formulation and Fuel Supply Importer........................................................................................... 52

Fuel Type and Technologies Importer .................................................................................................... 52

Inspection and Maintenance (I/M) Importer.......................................................................................... 52

Summary Results and Conclusions ......................................................................................................... 52

   
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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List of Tables  

Table 1: Ozone Monitoring Data for the Memphis Metropolitan Statistical Area .............................................................................. 8

Table 2: 2012 Departures from Daily Average Temperature .......................................................................................................... 10

Table 3: 2013 Departures from Daily Average Temperature .......................................................................................................... 11

Table 4: 2014 Departures from Daily Average Temperature .......................................................................................................... 11

Table 5: 2015 Departures from Daily Average Temperature .......................................................................................................... 12

Table 6: Average Summer Day Nitrogen Oxide Emissions for DeSoto County .............................................................................. 23

Table 7: Average Summer Day Volatile Organic Compounds Emissions for DeSoto County ........................................................ 23

Table 8: List of Contingency Measures for DeSoto County ............................................................................................................ 27

Table 9: Safety Margin for an Average Summer Day for DeSoto County ....................................................................................... 29

Table 10: On-road Motor Vehicle Emission Budgets for DeSoto County ....................................................................................... 30

Table 11: Average Summer Day Nitrogen Oxide Emissions for DeSoto County ............................................................................ 33

Table 12: Average Summer Day Volatile Organic Compounds Emissions for DeSoto County ...................................................... 33

Table 13: Average Summer Day Nitrogen Oxide Non-Point Emissions for DeSoto County ........................................................... 35

Table 14: Average Summer Day Volatile Organic Compounds Non-Point Emissions for DeSoto County ..................................... 36

Table 15: Average Summer Day Nitrogen Oxide Non-Road Mobile Emissions for DeSoto County ............................................... 40

Table 16: Average Summer Day Volatile Organic Compounds Non-Road Mobile Emissions for DeSoto County ......................... 40

Table 17: MOVES Runspec Parameters ........................................................................................................................................ 44

Table 18: MOVES County Data Manager Parameters ................................................................................................................... 45

Table 19: Annual VMT by Year, DeSoto County Non-Attainment Area .......................................................................................... 48

Table 20: Summary of Total Mobile Source Emissions .................................................................................................................. 53

Table 21: Total NOx Emissions (grams) by Source Type and Analysis Year ................................................................................. 53

Table 22: Total VOC Emissions (grams) by Source Type and Analysis Year ................................................................................ 54

List of Figures

Figure 1: Ozone Design Value Trends for monitors in the Memphis CSA ........................................................................................ 9

Figure 2: Total NOX and VOC Emissions for TN-MS-AR Marginal Nonattainment Area .................................................................. 9

Figure 3: Average Wind Roses for Memphis International Airport .................................................................................................. 13

Figure 4: 2012 Ozone Season Wind Roses for Memphis International Airport .............................................................................. 13

Figure 5: 2103 Ozone Season Wind Roses for Memphis International Airport .............................................................................. 14

Figure 6: 2014 Ozone Season Wind Roses for Memphis International Airport .............................................................................. 14

Figure 7: 2015 Ozone Season Wind Roses for Memphis International Airport .............................................................................. 15

Figure 8: Average Summer Day Nitrogen Oxide Emissions for DeSoto County ............................................................................ 24

Figure 9: Average Summer Day Volatile Organic Compounds Emissions for DeSoto County ....................................................... 25

Figure 10: DeSoto County Ozone Non-Attainment Area ................................................................................................................ 47
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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INTRODUCTION

Request for Redesignation

The Mississippi Department of Environmental Quality, representing the Governor of the State

of Mississippi formally requests the portion of DeSoto County, MS that was designated as

nonattainment for the 2008 National Ambient Air Quality Standard (NAAQS) for ozone (O3) be

redesignated to attainment pursuant to Section 107(d)(3) of the 1990 Clean Air Act

Amendments (CAA).

Ground‐Level (Tropospheric) Ozone

Ozone is a colorless gas that occurs naturally in the atmosphere and can be found in the air we

breathe.   Ozone is composed of three atoms of oxygen, one more than the common oxygen

molecule (O2) we need to breathe to sustain life.    The additional oxygen atom makes ozone

extremely reactive.   Ozone in the Earth’s upper atmosphere, known as stratospheric ozone,

shields the Earth from the harmful effects of the sun’s ultraviolet rays.   Ozone found in the

atmosphere closer to the Earth’s surface (tropospheric ozone) is considered a harmful air

pollutant due to its adverse impacts on human health and welfare.

Tropospheric ozone is commonly referred to as ground‐level ozone and sometimes called smog.  

Ozone is not emitted directly by the combustion of fuels.  Ozone is formed in the atmosphere

by the reaction of volatile organic compounds (VOC) and oxides of nitrogen (NOX) in the

presence of sunlight.  These air pollutants, often referred to as ozone precursors, are emitted

by many types of pollution sources, including on‐road and off‐road motor vehicles and engines,

power plants and industrial facilities, and smaller sources, collectively referred to as area

sources.    Ozone is predominately a summertime air pollutant.    Changing weather patterns

contribute to yearly differences in ozone concentrations from region to region.  Ozone and the

pollutants that form ozone also can be transported into an area from pollution sources found

hundreds of miles upwind.

National Ambient Air Quality Standards (NAAQS)

The Clean Air Act (CAA) requires the United States Environmental Protection Agency (EPA) to

set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public

health and the environment.   National primary and secondary ambient air quality standards

under Section 109 of the CAA are set forth in Title 40 of the Code of Federal Regulations, Part

50.   NAAQS are subject to revision, and additional primary and secondary standards may be

promulgated as the EPA deems necessary to protect the public health and welfare.  The EPA

has promulgated primary and secondary NAAQS for carbon monoxide (no secondary standard

for carbon monoxide), lead, nitrogen dioxide, particulate matter, sulfur oxides, and ground‐

level ozone.  The EPA calls these pollutants “criteria” air pollutants because it regulates them by

developing human health‐based and/or environmentally‐based criteria (science‐based
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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guidelines) for setting permissible levels.    For each pollutant, a health‐based or “primary”

standard has been set to protect public health in general, and a welfare‐based or “secondary”

standard may be set to protect quality of life and the environment.  Primary standards set limits

to protect public health, including the health of “sensitive” populations such as asthmatics,

children, and the elderly.    Secondary standards set limits to protect public welfare, including

protection against decreased visibility, and damage to animals, crops, vegetation, and buildings.

2008 8‐Hour Ozone NAAQS

In 2008, the EPA revised the NAAQS for ground‐level ozone, setting the standard at 0.075 parts

per million (ppm) averaged over an 8‐hour period.  Hourly average concentrations are recorded

in ppm.  Running 8‐hour averages are computed from the hourly ozone concentration data for

each hour of the year.  The daily maximum 8‐hour concentration for a given calendar day is the

highest of the 24 possible 8‐hour average concentrations computed for that day.  The design

value is the statistic to compare the 2008 8‐hour ozone NAAQS and is a three‐year average

using the three most recent, consecutive calendar years of monitoring data.  A violation of the

2008 8‐hour ozone NAAQS occurs when the computed design value is greater than 0.075 ppm.

2008 8‐Hour Ozone Designations

CAA requires the EPA to designate areas as attaining or not attaining that NAAQS.  The EPA area

designations were generally based on air quality monitoring data collected during the 2009,

2010, and 2011 ozone seasons.    The highest monitor design value in an area was used to

determine its designation.   The CAA then specifies requirements for areas based on whether

such areas are or are not attaining the NAAQS.  

Because of EPA’s belief that it was contributing to ozone nonattainment for the Memphis area,

that portion of DeSoto County, Mississippi within the Memphis Urban Area Metropolitan

Planning Organization (MPO) was designated nonattainment.  At that time, the monitor in the

Crittenden County, Arkansas had a design value above the 2008 8‐hour ozone NAAQS.  

However, the monitor located in DeSoto County had a design value of 0.073 ppm, which is

below the 2008 8‐hour ozone NAAQS.  The TN‐MS‐AR Nonattainment Area for the 2008 Ozone

NAAQS was classified as a Subpart 2 marginal nonattainment area.

Clean Air Act Redesignation Criteria

Section 107(d)(3)(E) of the CAA, as amended, states an area can be redesignated to attainment

if the following conditions are met:

 The EPA has determined that the NAAQS have been attained. For ozone, the areas must

show that the average of the 4th highest 8‐hour ozone values from three (3) complete,

consecutive calendar years of quality‐assured air quality monitoring data must be equal

to or below 0.075 ppm.
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DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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 The applicable implementation plan has been fully approved by the EPA under section

110(k).

 The EPA has determined that the improvement in air quality is due to permanent and

enforceable reductions in emissions.    To demonstrate this, the State should estimate

the percent reduction (from the year used to determine the design value for designation

and classification) achieved from federal, state, and local measures.

 The EPA has fully approved a maintenance plan, including a contingency plan, for the

areas under section 175A.  

 The State has met all applicable requirements for the area under section 110 and Part D.

In the sections to follow, the MDEQ will provide the technical data necessary to show that the

portion of DeSoto County, MS within the Memphis MPO designated as a moderate

nonattainment area for the 2008 8‐hour ozone NAAQS as part of the TN‐MS‐AR Marginal

Nonattainment Area has attained and is expected to maintain the 2008 8‐hour ozone NAAQS,

and has met the requirements for redesignation set forth above.

   
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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AIR QUALITY

Geography and Topography

The Mississippi counties in the Memphis Metropolitan Statistical Area (MSA) are located in

northwestern Mississippi.   DeSoto and Tunica counties border the Mississippi River.   DeSoto

and Marshall Counties border Tennessee while Tate is directly south of DeSoto County.    The

topography of the area ranges from the flat lowland of the Mississippi Delta in the west to

rolling hills in the central and eastern part of the MSA.  Therefore, geography and topography

should not have a significant effect on DeSoto County contribution to violations of the ozone

standard in Shelby County, TN or Crittenden County, AR.  

Ozone Design Value Trend

Table 1 shows the 4th maximum concentrations for the years of 2011‐2014, as well as the

2011‐2013 and 2012‐2014 design values.  DeSoto County has attained the standard for the last

five years.  Figure 1 shows a downward trend in ozone values for all of the monitors in the area.  

Figure 2 shows the annual emissions for the entire TN‐MS‐AR Marginal Nonattainment Area for

the years 2005, 2008 and 2011, which are the last three years that complete emissions

inventory data is available.  Lower ozone design values have coincided with lower emissions

throughout the non‐attainment area.

County Site

4th Annual Maximum

8‐hour Ozone

3‐Year

Average

2011‐

2013

3‐Year

Average

2012‐

2014

3‐Year

Average

2013‐

2015* 2011 2012 2013 2014 2015*

DeSoto, MS Hernando 73 75 65 67 59 70 69 63

Shelby. TN Frayser 79 83 69 67 65 77 73 67

Shelby, TN Orgill Park 77 84 63 65 64 74 70 64

Shelby, TN Shelby Farms 81 86 69 66 66 78 73 67

Crittenden, AR Marion 82 79 67 67 66 76 71 66

* Incomplete Data 

Table 1: Ozone Monitoring Data for the Memphis Metropolitan Statistical Area
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Final, Adopted December 2, 2015

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* Incomplete Data

Figure 1: Ozone Design Value Trends for monitors in the Memphis CSA 

Figure 2: Total NOX and VOC Emissions for TN-MS-AR Marginal Nonattainment Area 

60

65

70

75

80

85

90

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015*

Design Value (ppb)

Year

Memphis Area 8-Hour Ozone Data 2005-2015

DeSoto Shelby - Orgill Shelby - Frayser

Shelby - Shelby Farms Crittenden

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

2005 2008 2011

Emissions (tons/year)

Year

NOX

VOC
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DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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Meteorology

Weather is inextricably linked to emissions in the production of ground level ozone.    The

Department conducted an analysis intended to compare the design value attainment years

(2012‐2014) to the 30‐year average for the area to determine if any unusual weather patterns

could have had an unexpected influence in producing lower O3 concentrations. Weather

conditions that have been linked to high levels of ground‐level ozone concentrations include

high temperatures, increased solar radiation, low humidity, and light winds.    Comparable

weather conditions have generally continued to occur in the area while ozone concentrations

have fallen.  As shown in Table 2, 2012 average monthly highs and lows were over 2 degrees F

higher than the 30‐year averages.  In addition, Tables 3, 4, and 5 show 2013, 2014, and 2015

monthly highs and lows near 30‐year averages.  Because these average temperatures are not

significantly lower than long‐term averages, this could not explain reduced ozone

concentrations.  Also, Figure 3 shows the long‐term average wind rose for the period of 1970 –

2014.  A comparison of Figures 4, 5, 6, and 7 shows that average wind speeds for those years

were lower than the long‐term average. Thus, the average temperatures were near the long‐

term averages and the wind speeds were below the long‐term average.  Therefore, analyses of

the temperature and wind data indicate that meteorology has not had a significant role in the

steady decline in ozone concentrations witnessed in the area, but that the primary reason is

due to reductions in precursor emissions.

2012 Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Seasonal

Average

30 Year

Average

Monthly High

64 73 81 89 92 91 85 74 81.125

30 Year

Average

Monthly Low

44 53 62 70 74 73 65 54 61.875

2012 Monthly

High 75.2 76.5 86 91 95 92.7 84.7 71.4 84

2012 Monthly

Low 54.5 55.5 66 70 76 72.7 65.9 51.4 64.025

Temp. Diff.

High 11.2 3.5 5.4 1.6 2.5 1.7  ‐0.3  ‐2.6 2.875

Temp. Diff.

Low 10.5 2.5 4.1  ‐0.1 2.2  ‐0.3 0.9  ‐2.6 2.15

Table 2: 2012 Departures from Daily Average Temperature 

   
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DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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2013 Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Seasonal

Average

30 Year

Average

Monthly High

64 73 81 89 92 91 85 74 81.125

30 Year

Average

Monthly Low

44 53 62 70 74 73 65 54 61.875

2013 Monthly

High 57.8 71.7 79 89 89 89.6 87.4 73.7 79.6125

2013 Monthly

Low 39.2 50.6 61 71 72 72.5 68.9 55.6 61.225

Temp. Diff.

High ‐6.2  ‐1.3  ‐2.3  ‐0.1  ‐2.9  ‐1.4 2.4  ‐0.3  ‐1.5125

Temp. Diff.

Low ‐4.8  ‐2.4  ‐1.4 0.6  ‐2.2  ‐0.5 3.9 1.6  ‐.065

Table 3: 2013 Departures from Daily Average Temperature 

2014 Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Seasonal

Average

30 Year

Average

Monthly High

64 73 81 89 92 91 85 74 81.125

30 Year

Average

Monthly Low

44 53 62 70 74 73 65 54 61.875

2014

Monthly High 60.6 72.3 81 88 87 91.7 85.6 75.7 80.0875

2014

Monthly Low 38.4 51.7 62 71 70 73.4 66.7 55.3 61.0125

Temp. Diff.

High ‐3.4  ‐0.7  ‐0.2  ‐1.5  ‐5.5 0.7 0.6 1.7  ‐1.0375

Temp. Diff.

Low ‐5.6  ‐1.3 0 1.1  ‐4.5 0.4 1.7 1.3  ‐0.8625

Table 4: 2014 Departures from Daily Average Temperature 

   
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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2015 Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Seasonal

Average

30 Year

Average

Monthly High

64 73 81 89 92 91 NA NA 81.67

30 Year

Average

Monthly Low

44 53 62 70 74 73 NA NA 62.67

2015

Monthly High 62.4 74.5 81.6 89.9 92.7 90.4 NA NA 81.9

2015

Monthly Low 43.0 55.8 64.1 71.5 76.4 71.0 NA NA 63.6

Temp. Diff.

High ‐1.6 1.5 0.6 0.9 0.7  ‐0.6 NA NA 0.23

Temp. Diff.

Low ‐1.0 2.8 2.1 1.5 2.4  ‐2 NA NA 0.93

Table 5: 2015 Departures from Daily Average Temperature 
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

Figure 3: Average Wind Roses for Memphis International Airport 

Figure 4: 2012 Ozone Season Wind Roses International Airport 
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

Figure 5: 2103 Ozone Season Wind Roses for Memphis International Airport 

Figure 6: 2014 Ozone Season Wind Roses International Airport    
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DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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Figure 7: 2015 Ozone Season Wind Roses for Memphis International Airport

   
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Final, Adopted December 2, 2015

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PERMANENT AND ENFORCEABLE REDUCTIONS IN EMISSIONS   

Federal measures have been enacted in recent years that are resulting in permanent and

enforceable emissions reductions.    A list of those measures are stated below and more fully

described in the Maintenance Plan section.   

• Tier 2 vehicle standards: Implementation began in 2004 and will require all passenger

vehicles in any manufacturer’s fleet to meet an average standard of 0.07 grams of NOX per

mile.    The Tier 2 rule also reduced the sulfur content of gasoline to 30 ppm starting in

January of 2006.  Tier 3 standards apply beginning in model year 2017 and are phased in

through 2025.  Sulfur content of gasoline will be further reduced to 10 ppm by January 1,

2017, and NOX emissions are estimated to be reduced by 25% by 2030 relative to 2014

levels.

• Heavy‐duty gasoline and diesel highway vehicle standards: EPA standards designed to

reduce NOX and VOC emissions from heavy‐duty gasoline and diesel highway vehicles

commenced implementation in 2004.  A second phase of standards and testing procedures,

which began in 2007, is reducing particulate matter from heavy‐duty highway engines and

has reduced highway diesel fuel sulfur content to 15 ppm.    In addition, the Heavy‐Duty

National Program reduces criteria pollutant emissions as a co‐benefit of lower CO2

emissions.    This program applies to the 2014‐2018 model years, and will be further

extended beyond model year 2018.

• Light Heavy‐Duty OBD: Established OBD monitoring requirements for heavy‐duty chassis

certified vehicles and for engines certified for use in heavy‐duty vehicles between 8,500

and 14,000 pounds gross vehicle weight rating (GVWR) beginning in 2004.

• Heavy‐Duty Engines OBD Rule: New OBD monitoring requirements for engines certified for

use in heavy‐duty vehicles above 14,000 pounds GVWR began in 2010.

• Light‐duty National Program for greenhouse gas emissions and fuel standards: The first

phase applies to model years 2012‐2016 and is being extended to the second phase

applicable to model years 2017‐2025.  By 2025, these programs are expected to increase

the industry fleet‐wide level to an equivalent of 54.5 miles per gallon if achieved exclusively

through fuel economy requirements.    As with the Heavy‐Duty National Program, the

reduction in ozone‐forming criteria pollutants such as NOX is a co‐benefit of the CO2

reductions targeted by the regulation.

• Non‐road spark‐ignition (SI) engines: Became effective in 2003 and will reduce NOX and
Mississippi State Implementation Plan Revision

DeSoto County, Mississippi Redesignation Request and Maintenance Plan

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hydrocarbon emissions.    For non‐road compression‐ignition engines, Tier 4 exhaust

emission standards will apply to the largest engines (>900 kW) beginning in 2015.

o Construction and Agriculture

 Tier 3/Interim Tier 4: Established more stringent emission standards for

engines between 37 and 560 kilowatts (50 and 750 hp), beginning in 2006.

 Tier 4 Non‐road Diesel Rule: Established more stringent emissions standards

for all engines greater than 19 kilowatts (25 hp) and lowered non‐road diesel

fuel sulfur to 15 ppm maximum, beginning in 2010.

o Marine Diesel: Control of emissions from SI engines and equipment, beginning in

2010.    Established first federal exhaust emission standards for stern‐drive and

inboard marine SI engines and increased the stringency of exhaust emission

standards for outboard and personal watercraft engines.    It also established new

evaporative emission standards for all marine SI engines.

   
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DeSoto County, Mississippi Redesignation Request and Maintenance Plan

Final, Adopted December 2, 2015

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MAINTENANCE PLAN

DeSoto County, Mississippi Maintenance Plan

Mississippi’s plan for maintaining compliance with the 2008 8‐hour ozone NAAQS in the DeSoto

County, Mississippi portion of the TN‐MS‐AR Marginal Nonattainment Area includes three major

parts: established control measures, a maintenance demonstration, and a contingency plan.  The

established control measures consists of the current federal and state control measures already in

effect, as well as the future benefits of the cleaner engine programs, and Transport Rule.

For the maintenance demonstration, the base year of 2012 was chosen since it is one of the most

recent 3 years (2012, 2013 and 2014) for which the Memphis area has clean air quality data for the

2008 8‐hour ozone NAAQS.  The interim years chosen are 2017 and 2020.  The final year of the

maintenance demonstration is 2027, since the CAA requires maintenance for at least ten years

after redesignation.  The maintenance demonstration consists of a comparison between the 2012

baseline emissions inventory and the projected emissions inventories (for 2017, 2020, and 2027),

which consider economic and population growth.  The comparison shows that the total emissions

in each of the interim years and the final year will be lower than in the base year, demonstrating

maintenance of the 2008 8‐hour ozone NAAQS.    The reductions in emissions are due to the

established control measures outlined below.

The Mississippi contingency plan involves tracking and triggering mechanisms to determine when

contingency measures are needed and a process of implementing appropriate control measures.  

In conjunction with the Mississippi maintenance plan, the Shelby County Health Department has

developed its own separate maintenance plan for the Shelby County portion of the TN‐MS‐AR

Marginal Nonattainment Area.
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Established Control Measures

Federal Control Measures

Tier 2 and Tier 3 Vehicle Standards

Federal Tier 2 vehicle standards require all passenger vehicles in a manufacturer’s fleet, including

light duty trucks and sport utility vehicles (SUVs), to meet an average standard of 0.07 grams of

NOX per mile.

Implementation began in 2004, with full compliance required by 2007.  The Tier 2 standards also

cover passenger vehicles over 8,500 pounds gross vehicle weight rating (the larger pickup trucks

and SUVs), which were not covered by Tier 1 regulations.  For these vehicles, the standards were

phased in beginning in 2008, with full compliance in 2009.  The new standards require vehicles to

be 77 percent to 95 percent cleaner than those made prior to these dates.  The Tier 2 rule also

reduced the sulfur content of gasoline to 30 ppm starting in January of 2006.  Most gasoline sold in

Mississippi prior to January 2006 had a sulfur content of about 300 ppm.  Sulfur occurs naturally in

gasoline but interferes with the operation of catalytic converters on vehicles, resulting in higher

NOX emissions.    Lower‐sulfur gasoline is necessary to achieve the Tier 2 vehicle emission

standards.  Tier 3 standards apply beginning in model year 2017 and are phased in through 2025.  

Sulfur content of gasoline will be further reduced to 10 ppm by January 1, 2017, and NOX

emissions are estimated to be reduced by 25 percent by 2030 relative to 2014 levels.    EPA is

setting new tailpipe standards for the sum of non‐methane organic gases (NMOG) and nitrogen

oxides (NOX), presented as NMOG+NOX, and for particulate matter (PM) that apply to all light‐duty

vehicles and some heavy‐duty vehicles.  Tier 3 standards also reduce evaporative emissions thus

lowering VOCs.

Heavy‐Duty Gasoline and Diesel Highway Vehicles Standards

New EPA standards designed to reduce NOX and VOC emissions from heavy‐duty gasoline and

diesel highway vehicles commenced implementation in 2004.  A second phase of standards and

testing procedures, which began in 2007, reduces particulate matter from heavy‐duty highway

engines and has reduced highway diesel fuel sulfur content to 15 ppm.    The total program for

these new engines using ultra‐low sulfur diesel is expected to achieve a 90 percent reduction in

PM emissions and a 95 percent reduction in NOX emissions (as compared to existing engines using

higher‐content sulfur diesel).  Gradual fleet turnover has caused many engines built before these

rules were in place to be retired and replaced with newer, less emitting engines.    This fleet

turnover will inevitably continue throughout the region.

Large Non‐road Diesel Engines Rule

In May 2004, the EPA promulgated new rules for large non‐road diesel engines (such as those used

in construction, agricultural, and industrial equipment) to be phased in between 2008 and 2014.  
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The non‐road diesel rules also reduce the allowable sulfur in non‐road diesel fuel by over 99

percent.  At that time, non‐road diesel fuel averaged about 3,400 ppm in sulfur.  The rule limited

non‐road diesel sulfur content to 500 ppm in 2006 and 15 ppm in 2010.  The combined engine and

fuel rules have reduced NOX and PM emissions from large non‐road diesel engines by over 90

percent.  For non‐road diesel engines, Tier 4 exhaust emission standards will apply to the largest

engines (>900 kW) beginning in 2015.

Non‐road Spark‐Ignition Engines and Recreational Engines Standard

This standard, effective in July 2003, regulates NOX, hydrocarbons (HC), and carbon monoxide (CO)

for groups of previously unregulated non‐road engines.  Tier 1 of this standard was implemented

in 2004, and Tier 2 in 2007.  It applies to all new engines imported into or sold within the United

States after implementation and regulates large spark‐ignition engines (e.g. forklifts and airport

ground service equipment), recreational vehicles (e.g. off‐highway motorcycles and all‐terrain‐

vehicles), and recreational marine engines.  The regulation varies based upon the type of engine or

vehicle.

The large spark‐ignition engines contribute to ozone formation and ambient CO and PM levels in

urban areas.  Like the large spark‐ignition, recreational vehicles contribute to ozone formation and

ambient CO and PM levels.  Recreational marine diesel engines over 37 kilowatts (used in yachts,

cruisers, and other types of pleasure craft) contribute to ozone formation and PM levels, especially

in marinas.  For certain recreational marine diesel engine sizes, the standard began to be phased‐

in in 2006.

When all of the non‐road spark‐ignition engines and recreational engines standards are fully

implemented, overall reductions of 72 percent in HC, 80 percent in NOX, and 56 percent in CO

emissions are expected by 2020.    These controls will help reduce ambient concentrations of

ozone, CO, and fine PM.

Emissions Inventory

There are two basic approaches used to demonstrate continued maintenance.    The first is the

comparison of a projected emissions inventory with a baseline emissions inventory.  The second

approach involves complex analysis using gridded dispersion modeling.  The approach used by the

MDEQ is the comparison of emissions inventories for the years 2012 and 2027.

The maintenance demonstration is made by comparing the 2012 baseline emissions inventory to

the 2027 projected emissions inventory.  The base year of 2012 was chosen since it is a year that

falls within the attaining design value period of 2012‐2014, and some emissions inventory data

was already developed for this year.    The baseline emissions inventory represents an emission

level for a period when the ambient air quality standard was not violated, 2012‐2014.    If the
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projected emissions remain at or below the baseline emissions, continued maintenance is

demonstrated and the ambient air quality standard should not be violated in the future.    In

addition to comparing the final year of the plan, all of the interim years are compared to the 2012

baseline to demonstrate that these years are also expected to show continued maintenance of the

2008 8‐hour ozone NAAQS.

The emissions inventories are comprised of four major types of sources: point, non‐point, on‐road

mobile, and non‐road mobile.    The projected emissions inventories have been estimated using

projected rates of growth in population, traffic, economic activity, and other parameters.  

Naturally occurring, or biogenic, emissions are not included in the emissions inventory

comparison, as these emissions are outside the State’s span of control.

The Shelby County Health Department has developed a maintenance plan for the Tennessee

portion of the Memphis nonattainment area.  For emissions summaries for the Tennessee portion

of the Memphis nonattainment area, refer to the Redesignation Demonstration and Maintenance

Plan submitted by Shelby County Health Department.

Types of Emission Inventories

There are four different man‐made emission inventory source classifications: (1) Point, (2) Non‐

Point, (3) On‐Road Mobile, and (4) Non‐Road Mobile sources.  

Point sources are those larger industrial or commercial stationary facilities, including those that

must have Title V permits issued by the MDEQ Air Division.  These sources have the potential to

emit more than 100 tons of NOX or VOC.  The source emissions are tabulated from data collected

by direct on‐site measurements of emissions or mass balance calculations utilizing approved

emission factors.    There are usually several emission sources for each facility.    Emission data is

collected for each point source at a facility and the data is entered into an in‐house database

system.  For the projected year’s inventory, point sources are adjusted by growth factors based on

NAICS codes.  A complete description of how these inventories were developed is given in detail in

Appendix A.

Non‐Point sources are those stationary sources whose emissions are relatively small, but due to

the large quantities, the collective emissions could be significant (i.e., smaller industrial facilities,

dry cleaners, service stations, etc.).  For these sources, emissions are estimated by multiplying an

emission factor by some known indicator of collective activity such as production, number of

employees, or population.  The emission factors used were obtained from the EIIP Tech Reports,

the Procedures document or the USEPA's AP 42 Compilation of Air Pollutant Emission Factors,

Fifth Edition, referred to as AP 42, and the ERTAC collaboration. These types of emissions are

estimated on the county level.    Various sources of data, such as population growth, energy
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consumption by sector, and county business patterns from the Census, were used to determine

the growth projections.  A complete description of how these inventories were developed is given

in detail in Appendix B.

Non‐road mobile sources are equipment that can move but do not use the roadways, i.e., lawn

mowers, construction equipment, agricultural equipment, etc.  The emissions from this category

are calculated using the non‐road part of EPA’s MOVES2014 mobile model.  Railroad locomotive

emissions are not calculated included in the non‐road portion of the MOVES2014 model, so the

emissions need to be calculated differently.  A complete description of how these inventories were

developed is given in detail in Appendix C.  The MOVES2014 model expresses VOC emissions as

Total Gaseous Hydrocarbons (TGH).

For on‐road mobile sources, the EPA mobile model MOVES2014 is used to generate emissions.  

MOVES can be used to estimate exhaust and evaporative emissions as well as brake and tire wear

emissions from all types of on‐road vehicles.  The estimation of emissions involves multiplying an

activity level by an emission factor, and is all done within the model.  The activity level used by

MOVES2014 is vehicle miles traveled (VMT).    For the future year inventories, the MOVES 2014

mobile model takes into consideration expected federal tailpipe standards, fleet turnover, and

new fuels.  A complete description of how these inventories were developed is discussed in detail

in Appendix D.
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Maintenance Demonstration

As discussed above, maintenance is demonstrated when the future years total man‐made

emissions are less than the 2012 baseline emissions.  The following table summarizes the VOC and

NOX emissions for the DeSoto County portion of the TN‐MS‐AR Marginal Nonattainment Area for

the 2008 Ozone NAAQS.  The difference between the base year (2012) and the final year (2027)

illustrates that the continued maintenance of the 2008 8‐hour ozone NAAQS is expected.

Summary of Emissions

Table 5 contains the estimated NOX emissions from all of the emission source sectors for the

DeSoto County portion of the TN‐MS‐AR Marginal Nonattainment Area for the 2008 Ozone

NAAQS.   

NOx Average Summer Day Emissions (tons)

   2012 2017 2020 2027

Point Source 1.78 1.81 1.83 1.89

Non‐Point Source 1.24 1.25 1.25 1.24

On‐Road Mobile 8.66 5.34 3.53 2.74

Non‐Road Mobile 2.89 2.29 2.06 1.78

Total Emissions 14.57 10.68 8.67 7.65

Table 6: Average Summer Day Nitrogen Oxide Emissions for DeSoto County 

Table 6 lists the estimated VOC emissions from all emission source sectors for the DeSoto County

portion of the TN‐MS‐AR Marginal Nonattainment Area.   

VOC Average Summer Day Emissions (tons)

   2012 2017 2020 2027

Point Source 0.84 0.77 0.77 0.79

Non‐Point Source 6.49 6.57 6.59 6.54

On‐Road Mobile 5.75 3.92 2.51 2.54

Non‐Road Mobile 1.86 1.41 1.33 1.28

Total Emissions 14.94 12.67 11.19 11.15

Table 7: Average Summer Day Volatile Organic Compounds Emissions for DeSoto County 

   
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Figure 6 shows the estimated NOX emissions trends for the duration of the 10‐year maintenance

plan.   

Figure 8: Average Summer Day Nitrogen Oxide Emissions for DeSoto County 

   

0.0

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Average Summer Day NOX Emissions (tons)

Year

DeSoto County Average Summer Day

NOX Emissions

Non‐Road Mobile

On‐Road Mobile

Non‐Point Source

Point Source
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Figure 7 shows the estimated VOC emissions trends for the duration of the 10‐year maintenance

plan.   

Figure 9: Average Summer Day Volatile Organic Compounds Emissions for DeSoto County 

For emissions summaries for the Tennessee portion of the Memphis nonattainment area, refer to

the Redesignation Demonstration and Maintenance Plan submitted by Shelby County Health

Department.  

0.0

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2012 2014 2016 2018 2020 2022 2024 2026

Average Summer Day VOC Emissions (tons)

Year

DeSoto County Average Summer Day

VOC Emissions

Non‐Road Mobile

On‐Road Mobile

Non‐Point Source

Point Source
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Contingency Plan

Overview

The two main elements of the Mississippi contingency plan are tracking and triggering

mechanisms to determine when contingency measures are needed and a process of developing

and adopting appropriate control measures.

Contingency Plan Trigger

The primary trigger for evaluation of the contingency plan will be a quality assured/quality

controlled (QA/QC) design value that exceeds the 2008 8‐hour ozone NAAQS at any monitor

within the Memphis nonattainment area.  If the QA/QC data indicates a violating design value for

the 2008 8‐hour ozone NAAQS, then the triggering event will be the date of the design value

violation, and not the final QA/QC date.  However, if initial monitoring data indicates a possible

design value violation but later QA/QC indicates that a NAAQS violation did not occur, then a

triggering event will not have occurred, and contingency measures will not need to be

implemented.  In addition, MDEQ will monitor periodic emissions inventory updates and compare

to projected emissions.   

MDEQ has been and will continue proactive efforts including reviewing monitoring data and

evaluating trends in an effort to identify possible violations as early as possible.
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Contingency Measures

The measures that will be considered for adoption upon a trigger of the contingency plan include:

Trigger Contingency Measure

MDEQ forecasts ozone levels

above the 2008 Ozone NAAQS

All open burning permits within the county shall be

suspended until the forecast shows improvement.  During

the summer season, holders of such permits are required to

contact the office on a daily basis to determine if burning

will be allowed.

Ozone Design Value for DeSoto

County exceeds the 2008 Ozone

NAAQS

Implementation of diesel retrofit programs, including

incentives for performing retrofits for fleet vehicle

operations (Programs such as diesel retrofitting may be

dependent on the availability of federal funding).

Voluntary engine idling reduction programs.

MDEQ will work with MDOT to have air quality alerts posted

on the Intelligent Transportation System boards located in

DeSoto County encouraging motorists to take actions to

reduce emissions when forecasted ozone levels will exceed

the 2008 Ozone NAAQS.

Other measures deemed appropriate at the time as a result

of advances in control technologies.

Table 8: List of Contingency Measures for DeSoto County

Action Resulting from Trigger Activation

In the event that the trigger is activated, the MDEQ will begin analyses to include emissions

inventory assessment to determine those emission control measures that will be necessary for

attaining or maintaining the 2008 8‐hour ozone NAAQS.   MDEQ will notify EPA Region 4 of the

proposed schedule and provide sufficient information to demonstrate that the proposed measures

are a prompt correction of the triggering event.    Contingency measures will be implemented

within 18–24 months (after QA/QC of the monitored data) of the ozone design value for DeSoto

County exceeding the 2008 ozone NAAQS.

Tracking for Ongoing Maintenance

As part of a statewide monitoring network, there is one monitoring site which is located in central

DeSoto County. This site was established as a downwind background monitor and is important for

forecasting ozone concentrations in the TN‐MS‐AR Marginal Nonattainment Area.  In addition to

measuring ozone, this site also measures wind speed and wind direction.  Mississippi will continue

operation of an appropriate air quality monitoring network in accordance with 40 CFR Part 58,

Ambient Air Quality Surveillance and associated appendices.
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Mississippi will continue to update its emissions inventory, including DeSoto County, at least once

every three years. In addition to the emissions inventory for 2012, the emissions inventory base

year, and the last year of the maintenance plan, 2027, interim years of 2017 and 2020 were

selected to show a trend analysis for maintenance of the 2008 8‐hour ozone NAAQS.  Tracking the

progress of the maintenance plan also includes performing reviews of the updated emissions

inventories for the area using the latest emissions factors, models, and methodologies.  For these

periodic inventories, MDEQ will review the assumptions made for the purpose of the maintenance

demonstration concerning projected growth of activity levels.

In addition, MDEQ will continue the commitment to work with local stakeholders to maintain the

NAAQS as required.    These stakeholders continue to pursue actions that improve air quality in

general, focusing on multi‐pollutant efforts that reduce emissions contributing to ozone and

particulate matter and that also reduce air toxics and greenhouse gas emissions.    Local

stakeholders continue to be more engaged than ever in air quality issues and understanding how

the decisions made locally impact air quality.    As proven in Mississippi, by taking early action,

states may be able to prevent any actual violations of the NAAQS and, therefore, eliminate the

need on the part of the EPA to redesignate an area to nonattainment.   
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Motor Vehicle Emissions Budgets and Safety Margin

Safety Margin

Under 40 CFR 93.101, the term “safety margin” is the difference between the attainment level

(from all sources) and the projected level of emissions (from all sources) in the maintenance plan.  

The attainment level of the emission is the level of emissions during one of the years in which the

area met the NAAQS for the pollutant of concern.    The safety margin, or portion of the safety

margin, can be allocated to the transportation sector; however, the total emissions must remain at

or below the attainment level.   Attainment level emissions are shown in Tables 5 and 6 in the

Maintenance Demonstration section.  The safety margin for each projected year is listed below in

Table 8.

Safety Margin  

(tons per day)

Year NOX VOC

2012 n/a n/a

2017 3.89 2.27

2020 5.90 3.75

2027 6.92 3.79

Table 9: Safety Margin for an Average Summer Day for DeSoto County 

Motor Vehicle Emissions Budgets

The transportation conformity rule found in 40 CFR Part 93 requires specific emission budgets to

be defined for the on‐road mobile sources portion of the DeSoto County emission inventory.  

These budgets are to be used by transportation authorities to assure that transportation plans,

programs, and projects are consistent with, and conform to, the maintenance of acceptable air

quality in DeSoto County throughout the term of the maintenance plan.  Section 93.118(b) states

in part:

Consistency with the motor vehicle emissions budget(s) must be demonstrated for each year for

which the applicable (and/or submitted) implementation plan specifically establishes motor vehicle

emissions budget(s), for the attainment year (if it is within the timeframe of the transportation

plan), for the last year of the transportation plan's forecast period, and for any intermediate years

as necessary so that the years for which consistency is demonstrated are no more than ten years

apart, ...

If necessary to balance out expected increases and decreases in source category emissions,

different MVEBs (Motor Vehicle Emissions Budgets) may be set for other years over the course of

the maintenance to ensure that no total inventory will exceed the base year attainment inventory.  

However, this is not necessary as the expected significant reductions in total emissions ensure this
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will not occur.  The MVEBs for VOC and NOX for 2027 are presented below in Table 10.   

NOX (tons/day) VOC (tons/day)

2012 Mobile Emissions 8.66 5.75

2027 Mobile Emissions 2.74 2.54

    

2027 Safety Margin 6.92 3.79

Safety Margin applied to 2027 Emissions 5.26 2.46

Remaining 2027 Safety Margin 1.66 1.33

    

2027 Motor Vehicle Emissions Budget 8.00 5.00

Table 10: On-road Motor Vehicle Emission Budgets for DeSoto County

   

The MVEBs are consistent with the plan for maintaining total emissions from all source categories

at or below the 2012 NOx and VOC emissions levels through the year 2027.    Inter‐agency

consultation was utilized to develop the 2027 MVEBs.    For future conformity determinations,

transportation authorities should rely on the above MVEB unless this maintenance plan is revised.
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APPENDIX A: POINT SOURCE EMISSIONS
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Point Sources

Point sources are those larger industrial or commercial stationary facilities, including those that

must have Title V permits issued by the MDEQ Air Division.  These sources have the potential to

emit more than 100 tons of NOX or VOC.  The source emissions are tabulated from data collected

by direct on‐site measurements of emissions or mass balance calculations utilizing approved

emission factors.    There are usually several emission sources for each facility.    Emission data is

collected for each point source at a facility and the data is entered into an in‐house database

system.  For the projected year’s inventory, point sources are adjusted by growth factors based on

NAICS codes.   

Table 10 lists the NOX emissions for facilities within the DeSoto County portion of the TN‐MS‐AR

Marginal Nonattainment Area.   Table 11 similarly lists VOC emissions from point sources within

the county.    The data in the 2012 column was obtained using the 2012 emission inventory

numbers.  The 2012 emissions are the actual emissions reported as point source emissions from

the facility.  These emissions and supporting documents are submitted for Title V Fee purposes.  

The 2012 Airport emission numbers were obtained using the 2011 data.  

For the 2017 projected growth for facilities, the recent transport rule inventory NODA was used to

develop the emission projections.  The 2012 and 2017 data were extrapolated to get the 2020 and

2027 estimated emissions.  The same approach was used to determine 2020 and 2027 emission

projections for the airports.  Guardian Fiberglass shutdown and the Title V permit was revoked in

2015.   

   
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Facility Name 2012 2017 2020 2027

Davis Field 8.82E‐06 8.83E‐06 8.83E‐06 8.85E‐06

Delta Flying Service Inc. 1.36E‐05 1.36E‐05 1.37E‐05 1.37E‐05

Double O Ranch 8.82E‐06 8.83E‐06 8.83E‐06 8.85E‐06

Eagles Ridge 9.42E‐06 9.43E‐06 9.44E‐06 9.45E‐06

Guardian Fiberglass Inc*   7.58E‐03 0.00E+00 0.00E+00 0.00E+00

Hernando Village Airpark Inc. 2.78E‐04 2.79E‐04 2.79E‐04 2.79E‐04

JT Shannon Lumber Company 3.78E‐02 4.74E‐02 5.32E‐02 6.68E‐02

Olive Branch Airport 8.27E‐03 9.22E‐03 9.79E‐03 1.11E‐02

Rexam Beverage Can Company Inc. 1.49E‐02 1.49E‐02 1.49E‐02 1.49E‐02

Rite Hite Products 1.94E‐04 1.94E‐04 1.94E‐04 1.94E‐04

Texas Gas Transmission LLC 1.03E+00 1.04E+00 1.05E+00 1.06E+00

TVA Southaven Combined Cycle plant 6.75E‐01 6.94E‐01 7.06E‐01 7.33E‐01

Vaiden Landing 8.82E‐06 8.83E‐06 8.83E‐06 8.85E‐06

NOx Total tons/day 1.78 1.81 1.83 1.89

Table 11: Average Summer Day Nitrogen Oxide Emissions for DeSoto County 

Facility Name 2012 2017 2020 2027

Davis Field 2.04E‐05 2.04E‐05 2.05E‐05 2.05E‐05

Delta Flying Service Inc. 3.16E‐05 3.16E‐05 3.16E‐05 3.17E‐05

Double O Ranch 2.04E‐05 2.04E‐05 2.05E‐05 2.05E‐05

Eagles Ridge 2.18E‐05 2.18E‐05 2.18E‐05 2.19E‐05

Guardian Fiberglass Inc*   8.25E‐02 0.00E+00 0.00E+00 0.00E+00

Hernando Village Airpark Inc. 6.10E‐04 6.11E‐04 6.11E‐04 6.12E‐04

JT Shannon Lumber Company 4.00E‐02 4.15E‐02 4.24E‐02 4.45E‐02

Olive Branch Airport 1.67E‐02 1.83E‐02 1.92E‐02 2.14E‐02

Rexam Beverage Can Company Inc. 5.30E‐01 5.30E‐01 5.30E‐01 5.30E‐01

Rite Hite Products 7.06E‐02 7.06E‐02 7.06E‐02 7.06E‐02

Texas Gas Transmission LLC 5.13E‐02 5.56E‐02 5.81E‐02 6.40E‐02

TVA Southaven Combined Cycle plant 4.57E‐02 5.00E‐02 5.26E‐02 5.86E‐02

Vaiden Landing 2.04E‐05 2.04E‐05 2.05E‐05 2.05E‐05

VOC Total tons/day 0.84 0.77 0.77 0.79

Table 12: Average Summer Day Volatile Organic Compounds Emissions for DeSoto County 

*Guardian Fiberglass shutdown and the Title V permit was revoked in 2015.
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APPENDIX B: NON‐POINT SOURCE EMISSIONS
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Non‐Point Sources

Non‐Point sources are those stationary sources whose emissions are relatively small, but due to

the large quantities, the collective emissions could be significant (i.e., smaller industrial facilities,

dry cleaners, service stations, etc.).  For these sources, emissions are estimated by multiplying an

emission factor by some known indicator of collective activity such as production, number of

employees, or population.  Non‐Point source emission data is estimated using an assumed growth

factor for the area’s population.  In general, one of the following emissions estimation approaches

is used to calculate the area source emissions: per capita emission factors, employment‐related

emission factors, commodity consumption related emission factors, and level of activity based

emission factors.    The emission factors used were obtained from the EIIP Tech Reports, the

Procedures document or the USEPA's AP 42 Compilation of Air Pollutant Emission Factors, Fifth

Edition, referred to as AP 42, and the ERTAC collaboration.  Below the emissions are categorized

into one of eight groups.    These values are extrapolations based on the 2011 data for DeSoto

County, Mississippi.   

Source 2012 2017 2020 2027

Miscellaneous Area Sources 0.049079 0.049306 0.049541 0.049726

Mobile Sources 0.750354 0.736188 0.703286 0.662463

Natural Sources 0.575564 0.654621 0.73661 0.801038

Stationary Source Fuel Combustion 0.361831 0.394634 0.428654 0.455387

Waste Disposal, Treatment, and Recovery 0.122751 0.126613 0.130618 0.133766

Total NOX (tons/day) 1.859579 1.961361 2.048709 2.102379

Table 13: Average Summer Day Nitrogen Oxide Non-Point Emissions for DeSoto County 

 
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Source 2012 2017 2020 2027

Industrial Processes 0.017069 0.019414 0.021845 0.023756

Miscellaneous Area Sources 0.086746 0.086746 0.086747 0.086748

Mobile Sources 0.030486 0.030758 0.030432 0.029675

Solvent Utilization 3.19219 3.31349 3.439578 3.537147

Stationary Source Fuel Combustion 0.015402 0.017518 0.019712 0.021436

Storage and Transport 2.919173 2.86946 2.750749 2.602268

Waste Disposal, Treatment, and Recovery 0.232449 0.23422 0.236057 0.237501

Total VOC (tons/day) 6.493515 6.571606 6.58512 6.538531

Table 14: Average Summer Day Volatile Organic Compounds Non-Point Emissions for DeSoto 

County
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APPENDIX C: NON‐ROAD MOBILE EMISSIONS
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Non‐Road Mobile Sources		

This section includes NOX and VOC emissions for non‐road sources in DeSoto County.    These

emissions are from agricultural equipment, airport equipment, commercial equipment,

construction equipment, industrial equipment, lawn and garden equipment, locomotives, logging

equipment, oil field equipment, pleasure craft, railroad maintenance equipment, recreational

vehicles, and underground mining equipment.    The emission numbers were obtained from the

MOVES2014 model using the non‐road mobile source feature.  MOVES2014 was used to estimate

the emissions for years 2012, 2017, 2020, and 2027.  

MOVES2014 non‐road feature does not give emissions for locomotives.    The locomotive data is

based off of the 2011 EPA National Emissions Inventory.  The current emissions were extrapolated

based on the population increase in DeSoto County from 2011 through 2027.

   
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MOVES Model Inputs		

Below are the inputs used in the MOVES2014 model.   

Scale

‐ Model

 Nonroad

‐ Domain/Scale

 National

‐ Calculation Type

 Inventory

TIME SPANS

‐ Time Aggregation Level

 Hour

‐ Years

 2012, 2017, 2020, 2027

‐ Months

 July

‐ Days

 Weekdays

GEOGRAPHIC BOUNDS    

‐ Region

 County

‐ State

 Mississippi

‐ County

 DeSoto County

VEHICLES/ EQUIPTMENT

‐ All fuels and Sector combinations were selected

ROAD TYPE

POLLUTANTS AND PROCESSES

‐ Total Gaseous Hydrocarbons (VOC)

‐ Oxides of Nitrogen (NOx)

STRATEGIES

‐ Rate‐of‐progress

OUTPUT

‐ General Output

 Mass Units: U.S. Ton

 Energy Units: Million BTU

 Distance Units: Miles

‐ Output Emission

 Always: 24 Hour Day by County

 Vehicle/ Equipment Categories: Model Year, Fuel Type, and Emission Process

 Off Road:  SCC, Sector, Engine Tech, and HP Class   
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Classification 2012 2017 2020 2027

Agricultural Equipment .45511 .34553 .28223 .17439

Airport Equipment .00013 .00009 .00006 .00003

Commercial Equipment .07950 .06460 .05896 .05115

Construction Equipment 1.38810 .91452 .70377 .47684

Industrial Equipment .20164 .11809 .10331 .10493

Lawn and Garden Equipment .17499 .14135 .13851 .13972

Locomotives   .53412 .60748 .68357 .74335

Logging Equipment .00093 .00037 .00019 .00012

Pleasure Craft .04805 .08555 .08429 .07955

Railroad Maintenance Equipment   .00796 .00643 .00548 .00362

Recreational   .00368 .00324 .00331 .00346

NOx Total (tons/day) 2.89421 2.28725 2.06368 1.77716

Table 15: Average Summer Day Nitrogen Oxide Non-Road Mobile Emissions for DeSoto County

Classification 2012 2017 2020 2027

Agricultural Equipment .04841 .03716 .03224 .02619

Airport Equipment .00001 .00001 .00001 .00001

Commercial Equipment .11167 .08679 .08670 .09363

Construction Equipment .19359 .15484 .14174 .12792

Industrial Equipment .05823 .02334 .01842 .01808

Lawn and Garden Equipment .82747 .68234 .69642 .76507

Locomotives   .02574 .02927 .03284 .03582

Logging Equipment .00076 .00078 .00081 .00091

Pleasure Craft .57468 .38214 .30026 .19318

Railroad Maintenance Equipment   .00166 .00126 .00110 .00086

Recreational   .01493 .01425 .01455 .01524

VOC Total (tons/day) 1.85715 1.41218 1.32509 1.27691

Table 16: Average Summer Day Volatile Organic Compounds Non-Road Mobile Emissions for 

DeSoto County 
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APPENDIX D: ON‐ROAD MOBILE EMISSIONS

   
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DESOTO COUNTY MOBILE SOURCE EMISSIONS ANALYSIS 

IN SUPPORT OF THE STATE IMPLEMENTATION PLAN (SIP) 

DEVELOPMENT 

 

 

FOR THE 

 

 

 

 

 

 

 

 

 

PREPARED BY: 

KIMLEY-HORN AND ASSOCIATES, INC. 

 

JULY 29, 2015 

MISSISSIPPI DEPARTMENT OF ENVIRONMENTAL QUALITY
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Introduction

On May 21, 2012 the United States Environmental Protection Agency (EPA) designated the portion 

of DeSoto County, MS within the Memphis metropolitan area boundary as a marginal 8-hour ozone 

moderate non-attainment area (77 FR 30088). The 8-hour ozone area designation was effective on 

July 20, 2012. The State of Mississippi appealed this finding, but a ruling posted in 78 FR 925 

(January 7, 2013) stated that appeal was formally denied by the EPA. The non-attainment portion 

of DeSoto County was classified as a marginal area, meaning they must reach attainment status 

within three years. 

The purpose of this emissions analysis is to provide information about anticipated mobile source 

emissions to help establish emissions budgets in the SIP for the precursors of ozone. The emissions 

analysis was performed according to procedures prescribed by the following federal, state and local 

regulations: 69 FR 40004, 40 CFR Parts 51 and 93 (i.e. Transportation Conformity Rule 

Requirements); the Mississippi Transportation Conformity Rules; and Metropolitan Planning 

Organization (MPO) Planning Regulations (23 CFR 450) implementing MAP-21 Requirements. 

Results of this emissions analysis are found in Table 3 of this report. 

This report documents the process used by Kimley Horn for the air quality analysis associated with 

the Desoto County SIP development. EPA’s MOVES2014 model was used to derive emission 

factors as required by the EPA1

. The MOVES input files were created and modified as discussed in 

the preconsensus analysis. The emissions factors are based on a number of inputs including 

temperature, relative humidity, and presence of inspection and maintenance programs, vehicle 

source type mix, vehicle age distribution, temporal distributions, and other roadway attributes. 

Emissions estimates are the product of aggregating the results from the emission rate development 

with average daily vehicle miles traveled (VMT), source type populations, hourly distribution, road 

type distribution, and average speed distribution as part of the MOVES inventory analysis. 

The Memphis and Shelby County MPO Travel Demand Model was used to obtain VMT estimates 

for the portion of DeSoto County in the non-attainment area. For more information on the 

methodology and assumptions utilized in the development of the Travel Demand Model, please 

refer to the Model Documentation in the Memphis MPO Direction 2040 Long Range 

Transportation Plan (LRTP), Appendix G. 

Latest Planning Assumptions

The Memphis and Shelby County MPO Travel Demand Model was developed with consultation 

and input from state and local transportation agencies and the USDOT. The 2040 LRTP provides 

the appropriate level of detail required by 40 CFR 93.106 of the conformity regulations. The 

highway projects in the 2040 LRTP are financially constrained for the entire plan and for each 

horizon year in terms of capital, operations and maintenance costs (See LRTP Chapter 8 – 

Implementation Plan). The emissions analysis is based on assumptions derived from estimates of 

current and future population, employment, travel, and congestion. As part of the 2040 LRTP 

conformity determination, past assumptions have been discussed with various local, state and federal 

                                                            

1 Using MOVES to Prepare Emission Inventories in State Implementation Plans and Transportation Conformity:  

Technical Guidance for MOVES2014, EPA, January 2015.
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agencies for their continued validity and updated whenever necessary. Detailed planning 

assumptions are presented in Section 2 of this report. 

Latest Emissions Estimation Model

Mobile source emissions estimates for the ozone season (summer) were developed using EPA's 

Motor Vehicle Emission Simulator, MOVES2014, and travel estimates from the latest Memphis 

MPO Travel Demand Model. The Mississippi Department of Transportation (MDOT), and 

Tennessee Department of Transportation (TDOT), Tennessee Department of Environment and 

Conservation (TDEC), and the Memphis MPO provided the most current data available for 

emissions calculations. Information from the Federal Highway Administration (FHWA) and EPA's 

Air Planning Branch in Atlanta were used as well. 

Methodology		

The emissions inventory development and emissions projection discussion below identifies 

procedures used to obtain emissions. Table 16 summarizes the settings used in the MOVES run 

specification file. Table 17 lists the assumptions used in the MOVES County Data Manager. 

Further details on the use of MOVES are found in the following sections. 

Table 17 – MOVES Runspec Parameters 

MOVES Runspec Parameter Settings 

MOVES2014 

Scale County, Inventory Mode 

Time Span Time aggregation = Hour 

1 month representing summer conditions (July) 

All hours of the day selected 

Weekdays only 

Geographic Bounds One partial county (DeSoto County, MS) 

Vehicles/Equipment All valid source types, gasoline and diesel 

Road Type All road types including off-network 

Pollutants and Processes Oxides of Nitrogen (NOx) and Volatile Organic Compounds (VOC) 

General Output Units = grams, joules, miles 

Output Emissions Time = hour, location =county, on-road emissions by road type and 

source use type 

Advanced Performance None 

Table 17: MOVES Runspec Parameters

 
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Table 18 – MOVES County Data Manager Parameters 

County Data 

Manager Input 

Data Source 

Meteorology Data Local information obtained from NOAA data at the Memphis 

International Airport. TDEC provided three-year average data for the 

month of July, including hourly temperatures and humidity. This analysis 

will assume the meteorological data at this location can be applied to the 

entire modeled area. 

Source Type Population Local and state information is currently under development and as such is 

unavailable at this time. As a result, default data was used as a starting 

point for all source type. The MOVES Technical Guidance provides 

guidance on how to adjust default data with local VMT data, a 

methodology that was referenced for all analysis years. 

Age Distribution Use Shelby County, TN-specific data obtained from the UT paper 

“Methodology for Developing Input Datasets for the MOVES Model,” 

August 2014. 

Vehicle Type VMT – 

HPMS Vehicle Type VMT 

Local data obtained from Memphis Travel Demand Model. 

Vehicle Type VMT – 

Monthly VMT Fraction 

Local data is unavailable; therefore, the analysis uses Shelby County, TNspecific data obtained from the UT paper “Methodology for Developing 

Input Datasets for the MOVES Model,” August 2014.

Vehicle Type VMT – 

Daily VMT Fraction 

Local data is unavailable; therefore, the analysis uses Shelby County, TNspecific data obtained from the UT paper “Methodology for Developing 

Input Datasets for the MOVES Model,” August 2014. 

Vehicle Type VMT – 

Hourly VMT Fraction 

Local data obtained from Memphis Travel Demand Model. 

Average Speed Distribution DeSoto County data obtained from the Memphis Travel Demand Model. 

Road Type Distribution DeSoto County data obtained from the Memphis Travel Demand Model. 

Ramp Fraction DeSoto County data obtained from the Memphis Travel Demand Model. 

Fuel Supply/Fuel Formulation Default data for DeSoto County (obtained from the MOVES program) 

Alternative Fuel Vehicle Types There are no fixed-route transit buses operating in DeSoto County at this 

time. The default AVFT data will be modified to reflect only standard fuel 

types. 

I/M Programs No data entered. 

Table 18: MOVES County Data Manager Parameters 

MOVES

The Clean Air Act (CAA) requires US EPA to regularly update its mobile source emission models. 

US EPA continuously collects data and measures vehicle emissions to make sure the Agency has the 

best possible understanding of mobile source emissions. This assessment, in turn, informs the 

development of US EPA’s mobile source emission models. MOVES2014, which represents the 

Agency’s most up-to-date assessment of on-road mobile source emissions, was used for this analysis. 

Travel Demand Modeling

The Memphis Urban Area travel demand model boundary includes all of DeSoto County and Shelby 

County, as well as portions of Tipton, Fayette, and Marshall Counties. Figure 8 shows the DeSoto 

County Non-Attainment Area. Although model approval is a joint process between the MPO and 
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the appropriate state review agencies, the Tennessee Department of Transportation (TDOT) was 

the primary agency responsible for approval of the travel demand model for use in developing the 

Long Range Transportation Plan (LRTP). The travel demand model used for the air quality 

conformity analysis was reviewed and approved for use for long range plan and air quality 

conformity analysis purposes. 

The Memphis Urban Area Travel Demand Model is a four step model. Trip generation, trip 

distribution, mode choice, and trip assignment components are included in the model. The base 

year of the travel demand model used in the development of the Direction 2040 LRTP is 2004. 

Socioeconomic data was forecasted to the year 2040 as a part of the most recent LRTP. Appendix 

G of the Direction 2040 LRTP contains the assumptions and methodology used to develop the 

travel demand model. 

Model Data Adjustments

At the outset of this process, it was important to compare the information in the travel demand 

model to raw data obtained through traffic counts. The 2004 Highway Performance Monitoring 

System (HPMS) data was obtained from the Mississippi Department of Transportation (MDOT) for 

DeSoto County. The annual VMT shown in the HPMS data was compared to the total 2004 

DeSoto County VMT shown in the travel demand model. This comparison yielded a HPMS/TDM 

ratio that was used to scale the VMT output from the model to more closely match documented 

conditions. This scaled VMT was used in the development of the HPMS vehicle type VMT. 

The adjusted annual vehicle miles traveled by MOVES vehicle source type for the study area are 

shown in Table 18. 
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Figure 10: DeSoto County Ozone Non-Attainment Area
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Table 19- Annual VMT by Year, DeSoto County Non-Attainment Area 

Source Type Source 

Type ID 

Source Type VMT 

2010 2012 2017 2020 2027 

Motorcycle 11 3,198,812 3,494,901 4,072,686 4,590,142 5,606,377

Passenger Car 21 818,344,363 894,091,969 1,041,905,439 1,174,284,834 1,434,265,965

Passenger Truck 31 223,469,257 245,192,227 284,900,845 321,025,867 392,036,012

Light Commercial 

Truck 32 58,026,203 62,359,021 73,495,527 82,906,590 101,325,188

Intercity Bus 41 348,218 124,887 145,684 176,339 218,455

Transit Bus 42 127,666 222,520 251,026 304,317 375,870

School Bus 43 452,953 693,037 807,924 978,149 1,203,468

Refuse Truck 51 1,431,042 1,648,785 1,873,808 2,246,818 2,757,364

Single Unit Short-haul 

Truck 52 31,658,583 35,456,326 41,064,973 49,772,288 61,417,522

Single Unit Long-haul 

Truck 53 1,841,695 1,937,017 2,306,018 2,874,735 3,582,270

Motor Home 54 1,145,330 1,369,384 1,543,973 1,767,080 2,070,255

Combination Shorthaul Truck 61 10,362,744 10,334,958 12,943,953 19,523,012 23,810,842

Combination Longhaul Truck 62 34,075,288 36,302,999 40,270,029 56,513,753 65,554,100

Total 1,184,482,156 1,293,228,028 1,505,581,886 1,716,963,924 2,094,223,688

Table 19: Annual VMT by Year, DeSoto County Non-Attainment Area 

Pre‐Processing

Information was gathered from the travel demand model to generate the average speed distribution, 

road type distribution, hourly VMT distribution, HPMS vehicle type VMT, and ramp fraction. To 

streamline this process, a pre-processor was developed. The pre-processor performed many of the 

calculations and disaggregations needed to produce MOVES-ready spreadsheets for each input. 

MOVES spreadsheet templates for each input type were developed for the identified model years. 

Following this, a script was developed to pull the needed data from the model and perform any 

needed calculations. MOVES files generated through this exercise could then be applied directly in 

the County Data Manager. Additional information on the data sources used and needed data 

manipulation is contained in Sections 3 and 4. 

Post‐Processing

The analysis was performed using the inventory method. As a result, post-processing of the data 

was not required to arrive at the overall emissions output. The resulting information was 

summarized by pollutant type for the portion of DeSoto County being analyzed to generate the 

overall emissions in tons per year. Sections 3 and 4 provide additional detail on the data sources 
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gathered, modeling assumptions, and post-processing steps. 

MOVES Runspec

The MOVES2014 software was released by the Environmental Protection Agency in October 2014. 

This software uses a graphical user interface with a set of input categories. A Runspec can be 

developed that stores the input values for these categories. The values and information included in 

the Runspecs developed for this analysis are explained in more detail in the following sections. 

Description

The information in this category is used to distinguish the individual Runspecs. For this analysis, the 

description is used to introduce the purpose for the analysis, the area being studied, and the year of 

analysis (i.e. 2010, 2012, 2017, 2020, and 2027). 

Scale

This input window is used to detail the information needed for the domain/scale of the analysis as 

well as the calculation type. The county level was selected as the domain for this effort, since it is 

the appropriate level for use in SIP and regional conformity analysis. The inventory method was 

chosen for the calculation type. 

Time Spans

The Time Spans input window has a variety of different timescale inputs that are used for 

understanding the level of temporal aggregation being used in the analysis. The time aggregation 

level was specified as hours, based on guidance from EPA/FHWA for the preferred aggregation 

level for conformity runs. The years 2010, 2012, 2017, 2020, and 2027 were chosen for the analysis 

years. Each year was done within a different Runspec. Since the pollutant analysis being conducted 

is for the 8-hour ozone standard, July was chosen as the month to best represent summer 

conditions. Weekdays were selected as the representative day type since they are considered to be 

the worst-case type when compared with weekends. All hours of the day were included in the 

analysis to represent conditions over a full 24-hour period. 

Geographic Bounds		

This analysis consisted of a portion of DeSoto County. This input window also asks for the name 

of the domain input database. A total of five input databases were created during this process, 

reflecting the appropriate Runspec and input data for the analysis years 2010, 2012, 2017, 2020, and 

2027. 

Vehicles/Equipment

This input window allows the user to specify which fuel and vehicle types are present within the 

transportation network. There are thirteen different vehicle classes (referred to as source use types) 

and five different fuel types. This analysis considers the diesel and gas fuel types only. This was 

partly to reflect the lack of compressed natural gas and liquefied petroleum gas vehicles in the 

population, and also to allow for default fuel formulation and fuel supply information to be used in 

the study area. Within this, all possible vehicle and fuel types were considered. Diesel motorcycles, 

gas combination long-haul trucks, and gas intercity buses were removed since they are not 

represented in the vehicle population. 
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Road Type

The MOVES software incorporates five different roadway types: off-network, rural restricted 

access, rural unrestricted access, urban restricted access, and urban unrestricted access. Expressways 

and freeways in the region are considered as restricted access facilities. For this analysis, all five 

roadway types were considered. Off-network emissions are intended to account for vehicle starts 

and evaporative emissions for parked vehicles. While these emissions are not captured through the 

information in the regional travel demand models, default values can be used to assess their impacts. 

Pollutants and Processes

This input window allows the user to specify different pollutants and processes that are desired for 

modeling. Since the purpose of this analysis is to assess emissions relating to the 8-hour ozone 

standard, the Runspec includes Oxides of Nitrogen (NOx) and Volatile Organic Compounds (VOC).

Miscellaneous Strategies

The MOVES software includes input windows where provisions can be specified for specific 

strategies such as on-road retrofit and rate of progress emissions. Since these strategies are not 

being applied in this location, no information was entered for this section. 

Output

Output for the MOVES program is stored in a user-created database. Output databases were 

created for each of the 5 different Runspec conditions. The unit of measure used in the output 

database were grams, joules, and miles. Based on the parameters already established in these 

Runspecs, the time measurement for this analysis was set as hourly, and the location was 

automatically set for the link level. 

County Data Manager	 	

Once all of the base parameters have been established for a given MOVES Runspec, the County 

Data Manager can be used to enter locally-specific data. Input provided in Excel spreadsheet format 

can be referenced using this tool, which converts the data to MySQL format and incorporates it into 

the MOVES analysis. For the DeSoto County portion of the non-attainment area, locally-specific 

data could consist of data used for the entire region, statewide, or county-level data. The following 

sections detail these input criteria, and the methodology and assumptions used to arrive at the 

information entered for each. 

Meteorology Data Importer

 Local information was obtained from NOAA data at the Memphis International Airport. TDEC 

provided three-year average data for the month of July, including hourly temperatures and humidity. 

This analysis assumes the meteorological data at this location can be applied to the entire modeled 

area. 

Source Type Population Importer

This importer provides the user with the opportunity to enter vehicle population data sorted by the 

13 MOVES vehicle source types. The Pre-Analysis Consensus Memorandum indicated that local 

and state information is currently under development and as such is unavailable at this time. As a 

result, default data was used as a starting point for all source types. The MOVES Technical 
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Guidance offers guidance on how to leverage default population and VMT data alongside local 

VMT data to arrive at an estimate of the local population. This methodology was applied for all 

analysis years. A growth rate was not applied, since growth is inherently built in through this 

methodology. 

Age Distribution Importer

The Age Distribution Importer allows the user to provide vehicle age distribution data sorted by the 

MOVES vehicle source types. Vehicle age distribution is divided into 30 years based on vehicle 

model years. For each vehicle type, the sum of all age distributions will equal one. Local data was 

not available; therefore, data was obtained from a study conducted by the University of Tennessee – 

Knoxville. This data was specific to Shelby County, and as such can be reasonably transferred to 

DeSoto County. 

Vehicle Type VMT and VMT Fractions

This data importer asks the user for the VMT in the study area by HPMS vehicle class type, hourly 

VMT distributions, daily VMT distributions, and monthly VMT distributions. The HPMS vehicle 

class VMT is asked for an annual basis. To determine this information, data can be pulled from 

available travel demand models or from regional HPMS data. 

HPMS Vehicle Class VMT

The HPMS vehicle class VMT was determined using the pre-processor developed within the travel 

demand model. The travel demand model classifies vehicles into automobiles, single unit trucks, 

and combination unit trucks. The three vehicle classes in the model were divided into the five 

HPMS vehicle class types through the pre-processor. The five HPMS vehicle class types are 

motorcycles, light duty vehicles, buses, single unit trucks, and combination unit trucks. Since the 

travel demand model produces daily weekday volumes, the EPA conversion tool was used to 

convert these daily VMT numbers to annual values. 

Daily VMT Fraction

Daily VMT Fraction information was obtained from a study conducted by the University of 

Tennessee – Knoxville. This data was specific to Shelby County, and as such can be reasonably 

transferred to DeSoto County. 

Monthly VMT Fraction

Monthly VMT Fraction information was obtained from a study conducted by the University of 

Tennessee – Knoxville. This data was specific to Shelby County, and as such can be reasonably 

transferred to DeSoto County. 

Hourly VMT Fraction

The hourly VMT fraction was determined using the pre-processor developed within the travel 

demand model. To produce the information needed for the MOVES input file, the three vehicle 

classes in the model were expanded to the 13 MOVES vehicle source types. In addition, the four 

time of day periods in the model were expanded to represent each hour of the day. The default mix 

of off-network hourly distribution percentages was used for all vehicle classes. 
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Average Speed Distribution Importer

This importer gives the user the opportunity to enter locally specific average speed data, 

disaggregated by vehicle source type, road type, weekday/weekend, and hour of the day. The 

MOVES model uses 16 speed bins, dividing speed distributions into a fraction of driving within 

each speed bin for each of the criteria listed previously. The average speed distribution was 

determined using the pre-processor developed within the travel demand model. The vehicle classes 

in the model were expanded to the 13 MOVES vehicle source types, and the hourly distribution was 

expanded from the four time periods in the model to each hour of the day. 

Road Type Distribution Importer

The road type distribution importer can be used to incorporate locally-specific roadway distribution 

information. The average speed distribution was determined using the pre-processor developed 

within the travel demand model. The vehicle classes in the model were expanded to the 13 MOVES 

vehicle source types. 

Ramp Fraction Importer

This importer allows the user to input the percentage of traffic on urban restricted and rural 

restricted roadways that is traveling on ramp facilities. The ramp fractions were determined using 

the pre-processor developed within the travel demand model. 

Fuel Formulation and Fuel Supply Importer

The fuel formulation and fuel supply importers are used to input locally-specific fuel properties into 

the model. The pre-analysis consensus memorandum specified that default values would be used 

for this category. 

Fuel Type and Technologies Importer

This importer value considers the alternative vehicle fuels and technologies (AVFT). If no 

information is entered for AVFT, MOVES assumes a default mix of alternative fuels. The MOVES 

default mix assumes a small percentage of compressed natural gas (CNG) transit buses. Since there 

are no alternative fuel vehicles in the transit fleet for DeSoto County, the default value for this file 

was modified to reflect only diesel and gasoline fuel types. 

Inspection and Maintenance (I/M) Importer

This importer would allow local inspection and maintenance data to be entered for the study area. 

The DeSoto County portion of the non-attainment area has no I/M program in place. When 

default data is exported for this, the file indicates there are no I/M programs in place for the area. 

Since this is an accurate representation of the I/M program in the area, no further data was entered. 

Summary Results and Conclusions

Output tables from the MOVES runs were opened in MySQL and exported to spreadsheet form. 

Results from this analysis are summarized in Table 19. Additional detail on the total emissions has 

been provided in Tables 20 and 21. These tables show total emissions for each analysis year by the 

13 MOVES vehicle source types. 

 
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Table 20 – Summary of Total Mobile Source Emissions 

Pollutant Emissions (tons/day) 

2010 2012 2017 2020 2027 

Volatile Organic Compounds (VOC) 6.277 5.754 3.918 2.506 2.544 

Oxides of Nitrogen (NOx) 9.720 8.660 5.339 3.529 2.741 

Table 20: Summary of Total Mobile Source Emissions

Based on the results from the MOVES analysis, the trend is a general reduction in emissions of 

VOC and NOx. There is a slight increase in VOC between 2020 and 2027. The reason for this 

slight increase in VOC in the out analysis year is that the Motor Vehicle Emission Simulator 

(MOVES) air quality model developed by EPA recognizes a benefit in advancing technology to 

reduce mobile source emissions over time. So, if there were no change in VMT, there would be a 

reduction in emissions over time until it leveled out at some minimum level in the future. Because 

VMT is increasing over time, the benefit of emissions reductions due to improved technology is 

eventually overcome by the increase in VMT. 

Table 21 – Total NOx Emissions (grams) by Source Type and Analysis Year 

Source Type Source 

Type ID

Analysis Year 

2010 2012 2017 2020 2027 

Motorcycle 11 8,923 9,273 9,987 10,835 12,743

Passenger Car 21 3,561,709 3,245,427 1,901,864 990,692 816,399

Passenger Truck 31 1,778,368 1,647,034 947,857 442,008 375,346

Light Commercial Truck 32 357,680 313,817 178,213 139,494 75,477

Intercity Bus 41 17,815 5,071 3,053 3,676 1,213

Transit Bus 42 5,595 7,453 4,263 2,413 1,804

School Bus 43 12,079 15,601 12,416 2,325 6,961

Refuse Truck 51 58,490 52,273 31,665 13,397 16,698

Single Unit Short-haul Truck 52 599,504 532,496 309,740 264,426 187,696

Single Unit Long-haul Truck 53 33,564 28,698 16,677 12,584 10,052

Motor Home 54 21,592 21,540 15,243 14,126 9,817

Combination Short-haul Truck 61 544,144 405,436 213,934 201,445 126,483

Combination Long-haul Truck 62 1,818,282 1,572,092 1,198,692 1,104,125 846,013

Total NOx Emissions 8,817,745 7,856,212 4,843,603 3,201,546 2,486,702

Table 21: Total NOx Emissions (grams) by Source Type and Analysis Year

 
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Table 22 – Total VOC Emissions (grams) by Source Type and Analysis Year 

Source Type Source 

Type ID 

Analysis Year 

2010 2012 2017 2020 2027 

Motorcycle 11 40,240 41,884 41,630 39,688 49,189

Passenger Car 21 3,555,709 3,246,568 2,245,261 1,462,338 1,531,601

Passenger Truck 31 1,455,286 1,351,788 856,394 424,777 453,107

Light Commercial Truck 32 232,193 203,763 131,672 108,936 68,893

Intercity Bus 41 1,268 391 233 247 104

Transit Bus 42 443 665 398 153 171

School Bus 43 2,506 3,040 2,047 403 1,214

Refuse Truck 51 4,131 3,949 2,615 1,810 2,006

Single Unit Short-haul Truck 52 157,985 149,648 96,852 75,038 71,797

Single Unit Long-haul Truck 53 8,496 7,750 5,129 3,971 4,123

Motor Home 54 13,730 14,669 11,765 11,061 8,544

Combination Short-haul Truck 61 33,306 25,966 14,238 13,316 10,610

Combination Long-haul Truck 62 189,491 170,180 145,840 131,345 106,817

Total VOC Emissions 5,694,782 5,220,260 3,554,073 2,273,084 2,308,175

Table 22: Total VOC Emissions (grams) by Source Type and Analysis Year