1 

### Dallas

- Fort Worth, Texas

Final Area Designations f or the

20 08 Ozone National Ambient Air Q uality Standard s

This is the Technical Support Document (TSD) for the final area designations in the Dallas

- Fort Worth (DFW) area for the 2008 ozone national ambient air quality standard s (20 08 ozone NAAQS)

. 1 Through

out this document “we,” “our,” and “us” means the United States Environmental Protection Agency (EPA).

Table 1 below identifies counties in Texas that EPA is designating as no n attain ment for the 2008 o zone NAAQS as part of the DFW , Texas nonattainment area. In accordance with section 107(d) of the Clean Air Act, EPA must designate an area “nonattainment” if it is violating the 2008 ozone NAAQS or if it is contributing to a violation of the 2008 oz one NAAQS in a nearby area . EPA is designating two nonattainment areas within the state of Texas, the DFW nonattainment area and the Houston

- Galveston

Brazoria (HGB) nonattainment area. The technical analysis supporting the designation and boundaries

for t he DFW nonattainment area is provided below. This TSD includes our evaluation of information submitted by the State of Texas and the public. The formal responses to comments received are provided in the 2008 ozone designation response to comments document which can be found in the electronic

docket for this action, identified as EPA

- HQ

- OAR

- 2008

- 0476 at www.regulations.gov

.

Table 1. Counties in Texas Included in the Dallas

- Fort Worth 2008 Ozone Nonattainment Area

Area Texas’ Recommended

Nonattainment Counties EPA’s Designated

Nonattainment Counties

Dallas

- Fort Worth, TX Collin

Dallas

Denton

Ellis

Johnson

Kaufman

Parker

Rockwall

Tarrant Collin

Dallas

Denton

Ellis

Johnson

Kaufman

Parker

Rockwall

Tarrant

Wise

EPA is designating as “ unclassifiable/ attainment ” for the 2008 ozone NAAQS the remaining counties in

Texas that are not included in the table above or in the H GB nonattainment area (see the separate TSD

for th e HGB area).

The analysis below provides the basis for designated nonattainment area boundar ies

. It relies on our analysis of whether and which monitors are violating the 20 08 o zone NAAQS

, based on certified air quality monitoring data from 2008

- 2010 and on an evaluat ion of whether nearby areas are contributing

to such violations

. EPA has evaluated contribution s from nearby areas based on a weight

- of

- evidence analysis considering the factors identified below. EPA issued guidance on December 4, 2008 that

identified these factors as cr iteria EPA would consider in determining nonattainment area boundaries

1 The primary 8

- hour ozone standard, set to protect human health, was revised on March 27, 2008 (73 FR 16436) from 0.08 parts per million (ppm) to 0.075 ppm. The secondary ozone standard, set to protect human welfare and the environment, was revised to be consistent with the primary ozone standard.2 and recommend ed that s tates consider these factors in making their designations recommendations to

EPA

. 2

1. A ir quality data ( including the design value calculated for each Federal Reference Method ( FRM ) or Federal Equivalent Method ( FEM ) 3 monitor in the area ) ; 2. Emissions and emissions

- related data ( including location of sources and population , amount of

emissions and emissions controls , and urban growth patterns) ; 3. M eteorology (weather/transport patterns) ; 4. G eography and topography (mountain ranges or other basin boundaries) ; 5. J urisdictional boundaries (e.g., counties, air districts, existing nonattainment areas, Indian

country , metropolitan planning organizations (MPOs))

Ground

- level ozone generally is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight

. NOx and VOC emissions from a broad range of sources over a wide area typically contribute to

violations of the ozone standard s

. Accordingly, EPA chose to examine the 5 factors with respect to the larger of the Combined Statistical Area (CSA) or Core Based Statistical Area (CBSA) associated with

the air monitors th at are measuring violations of the 2008 ozone NAAQS (the “ violating monitor(s) ”)

. 4
All data and information used by EPA in this evaluation are the latest available to EPA and/or provided to EPA by the State of Texas

.

In EPA’s designations guidance for the 2008 ozone NAAQS EPA recommend s examining jurisdictional boundaries, thus we consider the larger boundaries of CSA s /C B SA s to establish the initial geographic scope for counties to be evaluated for their potential to contribute to violations of the NAAQS i n nearby areas. In addition, certain factors used to establish CSAs and C B SAs are similar to the factors EPA is using in this technical analysis to determine if a nearby area is contributing to a violation of the 20 08

o zone NAAQS

. Each CSA/CBSA consists of counties containing at least one urban core plus adjacent counties that have a high degree of social and economic integration with the urban core(s) as measured by commuting ties. Congress required a similar approach in 1990 for areas classified as seriou s or above

for the 1

- hour ozone standard and EPA used the same basic approach in the designation process for the

1997 o zone NAAQS

. Where a violating monitor is not located in a CSA or C B S A, EPA ’s guidance

recommend s using the boundary of the county contain ing the violating monitor as the starting point for considering the nonattainment area boundary.

2 The December 4, 2008 guidance memorandum “Area Designations for the 2008 Revised Ozone National Ambient Air Quality Standards” refers to nine factors

. In this TSD we have grouped the emissions

- related factors together under the heading of “Emissions and Emissions

- Related Data

, ” which results in five categories of factors.

3 FRM monitors utilize a chemi

- luminescent technique to measure ozone, while many FEM monitors use a technique involving ultraviolet photometry. FEM methods began to be developed in the late 1970s / early1980s and are now the most widely utilized methods for monitoring ozone levels. Refer to 40 CFR Part 53 for a more detailed description of FEM and

FR M methods. http://www.epa.gov/ttnamti1/files/ambient/criteria/reference

- equivalent

- methods

- list.pdf

4 Lists of CBSAs and CSAs and their geographic compo nents are provided at www.census.gov/population/www/metroareas/metrodef.html

. The lists are periodically updated by the Office of Management and Budget

. EPA used the most recent up date, based on 2008 population estimates, issued on December 1, 2009 (OMB

Bulletin No. 10

- 02).3 Technical A nalysis for Dallas

- Fort Worth , TX

Figure 1 is a map of the DFW designated nonattainment area for the 2008 ozone standard

. The map provides other relevant information

, including the locations and design values of air quality monitors

, county and other jurisdictional boundaries

, relevant statistical area boundaries, the nonattainment area boundary for the 1997 ozone NAAQS, and major transportation arteries

. The DFW CSA is comprised of

seven CBSAs , all within Texas : (1) the Athens Mic ropolitan Statistical Area (Henderson County) , (2)

the Bonham Micropolitan Statistical Area (Fannin County) ; (3) the Dallas

- Fort Worth

- Arlington

Met ropolitan Statistical Area (Collin, Dallas, Delta, Denton, Ellis, Hunt, Johnson, Kaufman, Parker, Rockwall, Tarrant and Wise Counties) ; (4) the Gainesville Mic ropolitan Statistical Area (Cooke County) ; (5) the Granbury Mic ropolitan Statistical Area (Hood and Somervell Counties ) ; (6) the Mineral

Wells Mic ropolitan Statistical Area (Palo Pinto County) ; and (7) the Sherman

- Denison Met ropolitan

Statistical Area (Grayson County)

. For this technical analysis, EPA evaluated all 19 counties in the

DFW CSA, as well as five counties outside (to the south/southeast) of the CSA: Freestone, Limestone, McLennan, Navarro and Robertson.

Figure 1. Dallas

- Fort Worth Designated Nonattainment Area

The boundary for the nonattainment area for the 1997 o zone NAAQS included the en tire counties of Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwell, and Tarrant.4 In March 2009

, 5 Texas recommended that the same counties as those designated nonattainment under

the 1997 ozone standard , plus Hood County, be designated as nonattainment for the 2008 ozone NAAQS b ased on air quality data from 200 5

- 200 7 and uncertified data for 2008

. Texas provided an update to the original recommendation in October 2011 6 based on air quality data from 2008

- 2010

. The

State’s recommendations ar e based on data from FEM monitors sited and operated in accordance with

40 CFR Part 58 and an analysis by the Texas Commission on Environmental Quality (TCEQ)

.

On December 9, 2011, EPA initiated the 120

- day consultation process by notifying Texas that based on EPA’s technical analysis of the DFW CSA the EPA intended to add Hood and Wise Count ies to the nine

count ies Texas recommended be designated as the DFW ozone nonattainment area and r equest ing that if the State wished to provide additional information to EPA regarding the intended designation s
, it should do so by February 29, 2012. EPA also provided the public a 30

- day opportunity to submit comments on
EPA’s intended designations in a December 20, 2011

, announcement in the Federal Register (76 FR 78872). In January , EPA extended t he public comment period to February 3, 2012 (January 19, 2012, 77 FR 2677). The p ublic comments we received are provided in the electronic docket , identified as EPA

HQ

- OAR

- 200 8

- 0476 and located at www.regulations.gov. On February 29, 2012, Texas submitted

comments and additional technical information to EPA. 7 We also received comments from over 40 organizations and individuals.

After considering the State’s original recommendation s as well as additional information provided by the state of Texas and others during the public comment period, and b ased on EPA's technical analysis described below, EPA is designating ten counties in Texas (identified in T able 1 above ) a s

“ nonattainment ” for the 20 08 o zone NAAQS as part of the DFW nonattainment area . The ten counties include the nine counties recommended by the State of Texas and Wise County. EPA is designating Hood County as “unclassifiable/attainment

. ”

Factor Assessment



### Factor 1 : Air Q uality D ata

For this factor , we considered 8

- hour o zone design values (in ppm ) for air quality monitors in counties

in the DFW CSA based on data for the 2008

- 2010 period (i.e., the 2010 design value, or DV) , which are the most recent years with certified air quality data

. A monitor’s DV is the metric or statistic that

indicates whether that monitor meets or attains a specified air quality standard

. The 2008 o zone NAAQS

are met at a monitor when the annual f ourth

- highest daily maximum 8

- hour average concentration, averaged over 3 years is 0.075 ppm or less

. A DV is valid only if minimum data completeness criteria

are met

. See 40 CFR part 50 App endix P

. Where several monitors are located in a county (or a designated nonattainment area or maintenance area ), the DV for the county or area is determined by the monitor with the highest DV

.

The 2010 DVs for the o zone NAAQS for counties in the DFW CSA and five additional counties outside

the CSA are provided in Table 2 below

.

5 Initial 2008 ozone NAAQS designation recommendation letter from Governor Perry to Acting Regional Administrator

Starfield, dated March 10, 2009.

6 Updated 2008 ozone NAAQS designation recommendation letter from Governor Perry to Regional Administrator

Armendariz, dated October 31, 2011.

7 Letter from Governor Perry to Regional Administrator Armendariz, dated February 29, 2012

.5 Table 2

. Air Quality Data

.

County State Recommended Nonattainment? 2008

- 2010 D esign V alue ( p arts per million or p pm )

Collin Yes 0.0 77

Cooke No

-- Dallas Yes 0.0 78

Delta No

-- Denton Yes 0.0 80

Ellis Yes 0.0 72

Fannin No

-- Grayson No

-- Henderson No

-- Hood No 0.0 75

Hunt No 0.0 64

Johnson Yes 0.0 80

Kaufman Yes 0.0 67

Palo Pinto No

-- Parker Yes 0.0 75

Rockwall Yes 0.0 74

Somervell No

-- Tarrant Yes 0.0 86

Wise No

-- Counties outside

of the DFW CSA

Freestone No

-- Limestone No

-- McLennan No 0.070

Navarro No

-- 8

Robertson No

-- Counties with design values exceeding the NAAQS are indicated in bold typeface.

Air quality monitors in Collin, Dallas, Denton, Johnson, and Tarrant C ounties indicate a violation of the

2008 o zone NAAQS , t herefore these counties are inclu ded in the nonattainment area

. A county (or partial county) must also be designated nonattainment if it contributes to a violation in a nearby area

. E ach county without a violating monitor that is located near a county with a violating monitor has been

evaluated , as discussed below, based on the five factors

.

The Eagle Mountain Lake ozone monitor (48

- 439

- 0075) in Tarrant County, which is less than 1⁄2 mile

from Wis e County, violates the 2008 ozone NAAQS wit h a 2008

- 2010 DV of 0.085 ppm. The 2008

- 2010 DV for the Hood County ozone monitor (48

- 221

- 0001) was 10 parts per billion (ppb) lower, with a DV of 0.075 ppm, which meets the 2008 ozone NAAQS.

Freestone, Limestone , McLennan, Navarro and Robertson counties do not all have air quality monitors. Those that do however, are not showing a violation of the 2008 ozone standard. In addition, these five counties are not adjacent to , or nearby

, a county with a violating monit or.

8 The monitor in Navarro County beg an operation in June 2009 and thus does not have a design value for 2008

- 2010.6 

### Factor 2: Emissions and Emissions

- Related Data

EPA evaluated emissions of ozone precursors ( NO x and VOC ) and other emissions

- related data that provide information on areas contributing to violating monitors. The emissions and emissions

- related

data we are evaluating include data from the 2008 National Emissions Inventory (NEI); the Barnett Shale Special Inventory provided by the TCEQ; population density and degree of urbanization; traffic data; and worker data. Each of these factors is described bel ow.

Emissions Data

Significant emissions levels in a nearby area indicate the potential for the area to contribute to monitored

violations of the NAAQS

. EPA evaluated county

- level emission data for NO x and VOC derived from (1) the 200 8 NEI, version 1.5, (2) a 2009 emissions inventory of oil and gas activities in the Barnett Shale, and (3) emissions inventory updates provided by Texas. ( See the February 29 , 2012, letter from Texas Governor Perry and http://www.epa.gov/ttn/chief/net/2008inventory.html )

. Based on information we received from Texas, we revised the 2008 VOC emissions inventory for Hood and Wise Counties. The revised 2008 VOC emissions inventory for Hood County is 8, 7 39 tons per y ear (tpy), down from 9,547 tp y reported in NEI version 1.5. The revised emissions inventory for Wise County is 17,609 tpy, down from the 23,657 tpy reported in NEI version 1.5. These reductions in the VOC emissions for Hood

and Wise Counties are due to revised oil and gas sector pneumatic emissions for 2008 that Texas

submitted to the NEI in October 2011. This revised data was not reflected in NEI version 1.5.

Table 3 indicates emissions of NO x and VOC ( expressed in tpy ) for violating and nearby countie s that

we considered for inclusion in the Dallas

- Fort Worth CSA

.7 Table 3. Total 2008 NO x and VOC Emissions *

County State Recommended

Nonattainment? NOx (tpy) VOC (tpy)

Collin Yes 10,322 14,503

Cooke No 3,853 5,790

Dallas Yes 51,023 63,473

Delta No 1,016 462

Denton Yes 17,421 24,932

Ellis Yes 15,768 6,543

Fannin No 2,165 1,207 Grayson No 5,919 7,401

Henderson No 3,573 6,067

Hood No 5,515 8, 7 39

Hunt No 3,688 3,765

Johnson Yes 31,769 10,163

Kaufman Yes 5,868 3,510

Palo Pinto No 3,348 7,464

Parker Yes 9,550 11,708

Rockwall Yes 1,859 2,047

Somervell No 698 921

Tarrant Yes 56,408 49,021

Wise No 11,911 17,609

Area

- wide: 241,674 245,3 25

* W ith VOC emissions revisions for Hood and Wise Counties submitted by TCEQ

. Counties with monitors indicating a violation of the NAAQS are indicated in bold

.

Subsequent to development of the 2008 NEI, the TCEQ prepared an emissions inventory of NOx and VOC emissions resulting from Bar nett Shale oil and gas production, transmission, processing, and

related activities during calendar year 2009. 9 Table 4 below presents an updated Barnett Shale Area Special Inventory of NOx and VOC emissions from oil and gas production activities for the c ounties in

the Dallas

- Fort Worth CSA. EPA also considered the additional contribution of NOx and VOC emissions from Barnett Shale area oil and gas production activities in its evaluation of emissions for the

DFW CSA counties.

9 http://www.tceq.texas.gov/airquality/point

- source

- ei/psei.html#barnett2 . Reference B arnett Shale Area Special Inventory,

Phase Two.8 Table 4. TCEQ 2009 Barnett Shale Area Special Inventory.

County State Recommended

Nonattainment? NOx (tpy) VOC (tpy)

Collin Yes

Cooke No 76 490

Dallas Yes 0 5

Delta No

Denton Yes 429 3,523

Ellis Yes 120 49

Fannin No Grayson No

Henderson No

Hood No 6,903 2,113

Hunt No

Johnson Yes 1,101 1,614

Kaufman Yes

Palo Pinto No 1,226 833

Parker Yes 743 2,420

Rockwall Yes

Somervell No 1,119 221

Tarrant Yes 415 1,083

Wise No 2,520 6,032

Area

- wide: 14,652 18,383 Counties with monitors indicating a violation of the NAAQS are indicated in bold

.

The counties in the DFW CSA with the highest emissions of NOx and VOC are Collin, Dallas, Denton, Ellis, Johnson, Parker, Tarrant, and Wise. Together, these counties accoun t for 84 percent of the NOx emissions and 81 percent of the VOC emissions for the entire ar ea for 2008

.

Wise County also has comparatively high emissions of NOx and VOC. Based on just the adjusted 2008 NEI data, Wise County’s emissions of VOC at 17,609 tp y are the 4 th highest in the 19

- county CSA, and Wise County’s NOx emissions are the 6 th highest of the counties in the CSA.

In addition to providing updated 2008 emissions inventory data for Hood and Wise Counties, Texas provided information indicating th at : Hood County NOx emissions from point sources decreased from 5,964 tpy in 2002 to 1,178 tpy in 2010; and that Wise County NOx emissions from point sources decreased from 2,895 tpy in 2002 to 2,163 tpy in 2010

.

EPA also received comments and information regarding current emissions from oil and gas activities from Hood County representatives. 10 This information indicates that well exploration and development within Hood County has declined significantly since 2009 , when TCEQ’s special inventory was

conducted

.

10 These letters and all other comments received are in the docket for this action, identified as EPA

- HQ

- OAR

- 2008

- 0476 at www.regulations.gov.9 Additionally, EPA received comments concerning the impact of emissions from five counties outside the DFW CSA, Freestone, Limestone, McLennan, Navarro, and Robertson Counties, on air quality in

the core CSA counties. These counties are south and southeast of the DFW nonattainment area. The

NOx and VOC emissions from these counties are presented in Table 5 below.

Table 5. Total 2008 NO x and VOC Emissions from the 2008 NEI, version 1.5 for five counties outside

of the DFW CSA.

County State Recommended

Nonattainment? NOx (tpy) VOC (tpy)

Freestone No 18,773 10,595

Limestone No 19,214 5,749

McLennan No 10,616 6,980

Navarro No 5,920 4,457

Robertson No 11,528 4,893

The five counties in Table 5 above have comparatively high levels of emissions of NOx and VOC and thus have the potential to contribute to monitored violations, but these counties are not in

, or nearby

, a county with a violating monitor.

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of the probable location and magnitude of non

- point source emissions . These include ozone precursor emissions from on

- road and off

- road vehicles and engines, consumer produ cts, residential fuel combustion, and consumer services. Areas of dense population or commercial development are an indicator of area source and mobile source NO x and VOC emissions that may contribute to ozone

formation that contributes to nonattainment in the area. Rapid growth in population or vehicle miles traveled ( VMT ) in a county on the urban perimeter signifies increasing integration with the core urban area, and indicates that it may be appropriate to include such perimeter area(s) as part of the

no nattainment area. Table 6 presents the population, population density, and population growth

information for each county in the area.10 Table 6. Population and Growth.

County State

Recommended

Nonattainment? 2010 Population 2010 Population Density (1000 pop /sq mi) Absolute change in population (2000

- 2010) Population % change (2000

- 2010)
Collin Yes 782,341 0.88 282,143 56.4

Cooke No 38,734 0.04 1,979 5 .4

Dallas Yes 2,368,139 2.6 142,691 6.4

Delta No 5,231 0.02

– 106

– 2 .0

Denton Yes 662,614 0.69 223,647 50.9

Ellis Yes 149,610 0.16 37,228 3 3. 1

Fannin No 33,915 0.04 2,575 8 .2 Grayson No 120,877 0.12 9,891 8.9

Henderson No 78,532 0.08 4,990 6.8

Hood No 51,182 0.12 9,719 23.4

Hunt No 86,129 0.10 9,199 12.0

Johnson Yes 150,934 0.21 22,967 17 .9

Kaufman Yes 103,350 0.13 31,268 43.4

Palo Pinto No 28,111 0.03 1,028 3. 8

Parker Yes 116,927 0.13 27,690 31.0

Rockwall Yes 78,337 0.53 34,457 78.5

Somervell No 8,490 0.04 1,660 2 4. 3

Tarrant Yes 1,809,034 2.01 354,603 2 4

. 4

Wise No 59,127 0.06 9,727 1 9 .7

Area

- wide: 6,731,614 0.46 1,207,356 21.9

Source s : U.S. Census Bureau population estimates for 20 10 as of August 4, 2011 ( http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTP L2.STO5&prodType=table )

Count ies with monitors indicating a violation of the NAAQS are indicated in bold

.

The Dallas

- Fort Worth area is a large metropolitan area with a population approaching 7 million people. For the purposes of determining the boundary of the 2008 ozone nonattainme nt area, EPA evaluated 22 counties in the greater DFW area with a combined population of 6,731,614 people and an average population density of 460 people per square mile.

Dallas and Tarrant Counties have the highest and most dense populations. Dallas Coun ty has approximately 2.4 million people and a population density of 2,600 people per square mile, and Tarrant County has approximately 1.8 million people and a population density of 2,010 people per square mile. Two other counties, Collin and Denton are al so densely populated; each has more than 500,000 people and a population density exceeding 500 people per square mile.

There are eight additional counties in this area with populations exceeding 50,000 people and/or population densities exceeding 100 peop le per square mile. These counties include: Ellis, Grayson, Hood, Johnson, Kaufman, Parker, and Rockwall. These counties are characterized by population counts that range between approximately 50,000 and 150,000 people and/or population densities that rang e from 120 to 530 people per square mile.

Ten of the counties in this area experienced population growth between 2000 and 2010 in excess of approximately 10,000 people. The population of four of these counties grew by more than 100,000 people during the p ast decade: Collin County (+282,143 people), Dallas County (+142,000 people), Denton County (+223,647 people), and Tarrant County (+354,603 people). Six additional counties11 experienced population growth that ranged from approximately 10,000 to 50,000 peopl e: Ellis, Johnson, Kaufman, Parker, Rockwall, and Wise Counties.

A final population and growth metric evaluated by EPA was the percent change in population during the period from 2000 to 2010. During this decade, eight of the 22 counties experienced a per cent change in population that exceeded 10 percent: Collin (+18.5%), Denton (+18.7%), Ellis (+13.5%), Kaufman (+17.6%), Parker (+15.4%), Rockwall (+25.7%), Somervell (+14.4%), and Tarrant (+12.2%) Counties.

The attachment to this document includes Figure 2

, Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network, with Population Density; and Figure 3 , Population Density Change in Percentage

Between the 2000 and 2010 Census for the Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network, which present graphical information on population density and growth for the DFW area

.

Table 7 below presents population data for the five outlying counties that EPA also evaluated for

inclusion in the DFW nonattainment area.

Table 7. Population and Growth for the five counties outside of the DFW CSA

County State

Recommended

Nonattainment? 2010 Population 2010 Population Density (1000 pop/sq mi) Absolute change in population (2000

- 2010) Population % change (2000

- 2010)

Freestone No 19,816 0.02 1,949 10.9

Limestone No 23,384 0.02 1,333 6

McLennan No 234,906 0.22 21,389 10

Navarro No 47,735 0.04 2,611 5.8

Robertson No 16,622 0.01 622 3.9

McLennan County has a population greater than 50,000 and a population density greater than 100 people per square mile; and Freestone and McLennan counties have experienced population growth of at least 10 percent, indicating the potential to contribute to violations. However, as indicated earlier in this TSD, the five counties listed in Table 7 do not have vio lating monitors, nor are they nearby violating

monitors.

Traffic data

EPA evaluated the total VMT for each county . In combination with the population/population density data and the location of main transportation arteries (see above), this information helps identify the probable location of non

- point source emissions. A county with high VMT is generally an integral part
of an urban area and indicates the presence of motor vehicle emissions that may contribute to ozone

formation that contributes to nonattainment in the area. Rapid population or VMT growth in a county on the urban perimeter signifies increasing integra tion with the core urban area, and indicates that such perimeter area(s) may be appropriate to include in the nonattainment area . Table 8 shows traffic data, including 2008 VMT and VMT growth for each county in the DFW CSA

.12 Table 8. Traffic Data

.

Texas County State Recommended

Nonattainment? 2008 VMT* (million miles) % Change in VMT (2002

– 2008)

Collin Yes 6,198 +33

Cooke No 636 +16

Dallas Yes 26,625 +14

Delta No 72

- 4

Denton Yes 5,507 +27

Ellis Yes 1,893 +49

Fannin No 334 +9 Grayson No 1,364 +3

Henderson No 768 +30

Hood No 443 +46

Hunt No 1,046 +26

Johnson Yes 1,432 +47

Kaufman Yes 1,548 +38

Palo Pinto No 397 +3

Parker Yes 1,280 +41

Rockwall Yes 676 +15

Somervell No 121 +27

Tarrant Yes 16,741 +17

Wise No 969 +16

Area

- wide: 68,050

---- * MOBILE model VMTs are those inputs into the 2008 NEI version 1.5. Counties with monitors indicating a violation of the NAAQS are indicated in bold

.

The VMT is an important metric as an indicator of potential contribution to ground level ozone concentrations. Commuters in the DFW area traveled a total of approximately 68 billion miles during calendar year 2008. Four counties in the DFW area, Collin, Dallas, Denton, and Tarrant Counties, each

have total VMT for calendar year 2008 in excess of 5 billion miles. Dallas and Tarrant Counties have particularly high VMT of approximately 27 and 18 billion miles, respectively. An additional seven counties have 2008 VMT in the range of approximately 1

– 2 billion miles; th ese counties are Ellis, Grayson, Hunt, Johnson, Kaufman, Parker, and Wise Counties.

Most of the counties in the DFW area have experienced growth in VMT for the period from 2002

– 2008. The growth in VMT for 15 of these counties exceeds 10 percent, and for 10 of those counties the growth rate exceeded 25 percent. Five counties in particular have comparatively high VMT growth for this period: Ellis County (+49%), Hood (+46%), Johnson County (+47%), Kaufman County (+38%), and Parker County (+41%). However, of the 19 counties listed in Table 8, Ellis, Kaufman, Johnson and

Parker counties rank 5 th , 6 th , 7 th and 9 th in absolute VMT, respectively, while Hood ranks 15 th

.

Table 9 below provides the VMT data for the five outlying counties that EPA evaluated for inclusion in the DFW nonattainment area. These counties have VMT that is comparatively lower than that of the counties recommended by Texas for inclusion in the nonattainment area, with the exception of Rockwall County.13 Table 9. Traffic Data for the Five Counties Outside of the DFW CSA

Texas County State Recommended

Nonattainment? 2008 VMT* (million miles) % Change in VMT (2002

– 2008)

Freestone No 650 +13

Limestone No 315 +18

McLennan No 275 +12

Navarro No 800

– 37

Robertson No 345 +17

In addition to VMT, we have evaluated worker data collected by the US Census Bureau 11 for the nine counties recommended by Texas for inclusion in the nonattainment area and two additional counties, Hood and Wise, that EPA considered for inclusion in the nonatt ainment area to inform our designations decisions. The data in Table 10 below are 2010 data and reflect an analysis of work destinations (all jobs) for residents in these 11 counties.

Table 10

. Worker Data

County State

Recommended

Nonattainment? Number of County Residents

who Work Number of County

Residents who Work in

Counties with Violating Monitors Percent of County

Residents who Work in Counties with Violating

Monitors

Collin Yes 364,301 320,714 88.0%

Dallas Yes 975,350 852,017 87.3%

Denton Yes 300,910 265,220 88.1%

Ellis Yes 63,773 37,071 58.1%

Hood No 18,133 6,932 38.2%

Johnson Yes 65,252 51,883 79.5%

Kaufman Yes 46,344 28,491 61.4%

Parker Yes 48,779 28,260 57.9%

Rockwall Yes 34,716 22,255 64.1%

Tarrant Yes 785,269 696,283 88.6%

Wise No 22,650 10,374 45.8%

Area

- wide: 2,725,477 2,319,500 85.1%
Counties with monitors indicating a violation of the NAAQS are indicated in bold

.

For each of the 11 counties shown in Table 10 above, a significant fraction of residents work in the

counties with violating monitors, thus contributing to mobile source emissions. This high percentage of workforce interchange indicates integration with the urban core counties.

Table 11 below provides the worker data for the five outlying counties that EPA evalua ted for inclusion

in the DFW nonattainment area.

11 The worker data can be accessed on the internet at http://onthemap.ces.census.gov/ . Please see Appendix 1 in the

Attachment for instructions to access the worker data.14 Table 11

. Worker Data for the five counties outside of the DFW CSA

County State

Recommended

Nonattainment? Number of County Residents

who Work Number of County

Residents who Work in

Counties with

Violatin g Monitors Percent of County

Residents who Work in Counties with Violating

Monitors

Freestone No 7,681 1,781 23.1%

Limestone No 8,720 1,805 20.6%

McLennan No 96,116 10,730 11.1%

Navarro No 19,865 5,174 26.0%

Robertson No 7,188 258 3.5%

For each of the five counties shown in Table 11 above, a smaller fraction of county residents work in the counties with violating monitors, which suggests that at this time there is little, if any integration with

the urban core counties.



### Factor 3 : Meteorology (weather/transport patterns)

EPA evaluate d available meteorological data to help determine how meteorological conditions, such as weather, transport patterns and stagnation conditions, would affect the fate and transport of precursor

emissions c ontributing to ozone formation. Based on past research by EPA and TCEQ the DFW area is generally characterized as having ozone exceedances with lower wind speeds and winds from many directions but the more frequent directions are easterly through southwe sterly winds. Light winds with weak frontal passages and conversion zones also are a common meteorological condition that often leads to high ozone in the DFW area. EPA’s analysis of meteorology is focused on the meteorology and transport phenomena that re sults in transport of air emissions to monitors in the DFW area that have

monitored exceedances of the 2008 ozone standard.

The attachment to this document includes Figure 2

, Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network, with Populatio n Density, which provides locations of major stationary sources and locations of ambient monitors with their design values.

EPA has performed 24

- hour wind back trajectories (an analysis of meteorological/transport patterns) specifically on days when certa in monitors (identified below) in the DFW area measured an exceedance of the 2008 NAAQS. These analyses were conducted to better understand the area’s meteorological transport conditions using the National Oceanic and Atmospheric Administration Hybrid Sing le Particle Lagrangian Integrated Trajectory Model (NOAA HYSPLIT or HYSPLIT). The HYSPLIT model yields an estimate of the path an air mass has traveled before reaching a monitor at a specific location and time. Specifically, the model provides the centerli ne of the probable path

. By knowing where an air mass has traveled before reaching a monitor where an exceedance has occurred, one can consider what potential

areas and emission sources could have contributed to the exceedance

.

The HYSPLIT trajectories f or 2008

- 2010 exceedance days at the Keller monitor in Tarrant County were conducted and the resulting trajectories were overlaid on Figure 2 in the attachments and are shown in Figure 4. We focused on the Keller and Eagle Mountain Lake monitors in Tarrant County and the Parker County monitor because the Keller and Eagle Mountain Lake monitors have recorded some of the highest ozone levels in the region, and inclusion of the Parker County monitor provided a good cross

section of the monitors in the western D FW area that experienced exceedances in the 2006

- 2010 period.15 In analysis of the DFW conceptual model for ozone exceedances, these monitors also seemed to have the most potent to be impacted by emissions from Hood or Wise Counties. Since the 2008

- 2010 data for the Keller monitor is only for three years, we evaluated additional years to better understand the meteorological transport conditions that exist during ozone exceedances. When we are developing a conceptual model for understanding what types of meteo rology are present when ozone exceedances occur in an area we evaluate 5 to 10 years worth of meteorological data. By considering a longer period of time, we have greater assurance that the most representative weather conditions are considered and

control strategies and decision making are not driven by unusual meteorology.

There are three additional figures in the attachment that include a zoom view for each of the Keller, Eagle Mountain Lake and Parker County monitors. These are labeled as Figures 5a through 5c. These

zoom views are HYSLPIT 24

- hour back trajectories for each of these moni tors on days when they had exceedances of the 75 ppb standard. Evaluation of the back trajectories for the Keller, Eagle Mountain Lake, and Parker County monitors indicates that the areas upwind of the monitors prior to an ozone

exceedance include all the counties in the 1997 8

- hour DFW nonattainment area ( Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwall and Tarrant counties ) , and also Wise and Hood

Counties. The additional back trajectories for the Eagle Mountain Lake and Parker County mo nitors further support that air that is transported from Hood and Wise counties ends up in the area of the

monitor when ozone exceedances are observed.

We did receive comments that we should not consider potential impacts at the Parker monitor from

Hood C ounty emissions since the Parker monitor’s 2010 DV (2008

- 2010 data) is attaining the standard with a 75 ppb. We evaluated the Parker monitor because it is part of the existing 9

- county DFW

nonattainment area for the 1997 8

- hour ozone NAAQS and Parker Count y was recommended by Texas to be part of the DFW nonattainment area for the 2008 8

- hour ozone NAAQS. In review of the 2006

- 2010 HYSPLIT back trajectories for the Parker County monitor ozone exceedances, some of the trajectories pass through the Hood County area. However, since the Parker monitor is attaining the 2008 NAAQS

, we did not put significant weight on the back trajectories for the Parker County monitor.

TCEQ SOURCE APPORTIONMENT MODELING

The TCEQ has developed CAMx photochemical modeling for prev ious ozone attainment

demonstrations

. The TCEQ did additional modeling using these CAMx databases to provide source apportionment modeling that assessed the potential contribution of Hood and Wise c ounty emissions to modeled high ozone values in the DFW ar ea

. The TCEQ’s analysis was performed for a period of a month in early 2006 summer (May 31 to July 1) for three monitors that EPA had performed back trajectories

. They al so evaluated this base episode with a future year analysis of 20 12 (2006 meteorology

w ith 201 2 emission estimates). In summarizing this work

, they provided average and maximum impacts to daily 8

- hour modeled exceedances in the base case (2006) and 201 2

. The TCEQ indicated the impacts were small and supported not including Hood or Wise c ounties

.16 EPA Assessment: Source apportionment analysis can be a good tool to combine the meteorology/transport of air parcels during high ozone days with the emissions of specific areas to evaluate potential impact on ozone levels from emissions in specifi c source areas, Hood and Wise County emissions in this case

. The EPA appreciates the efforts of TCEQ to provide the modeling to aid in decisions on designations

.

One of EPA’s observations regarding TCEQ’s Source Apportionment Modeling (SAM) is that the

m odeling is not inclusive of an entire ozone season

. Evaluations of the conceptual model for high ozone in DFW by TCEQ, EPA and others indicates that high ozone in DFW is roughly a bimodal distribution with lower peaks in early summer (May

- June) and the hig hest values in mid to late

- summer (July

September) and that the mid to late summer has some different meteorological/transport regimes than the early summer episodes

. Therefore, TCEQ ’ s SAM does not include a large number of days and does

not include all of the meteorology regimes conducive for ozone events in DFW and is missing the events that happen in mid to late

- summer that often set the DFW area’s DV

. As a result, it may be appropriate to place more weight on the maximum estimated impact and the number of days with sizeable impacts on violating monitors as compared to average impact. Another o bservation is that the evaluation used modeled exceedances for contribution and the modeling is underestimating exceedances on many days

and therefore is underestim ating the number of days of potential contribution

. Modeling is significantly under predicting peaks by 5

- 20 ppb at critical monitors; therefore we also looked at contribution at lower

modeled values (70 ppb)

. The EPA analyzed the 2006 and 2012 modeling in formation, but felt the 2012 analysis took into account recent control measures that TCEQ has implemented to lower DFW ozone levels and the 2012 was closer to what emission levels are at the time we are making these designation

decisions. We have summarize d the information provided by TCEQ in the letter from Governor Rick Perry dated February 29, 2012

. This summary of SAM estimates of impacts for Hood and Wise County

emissions is included in Table 12

.17 Table 12

. TCEQ Source Apportionment

– Hood and Wise Cou nty Anthropogenic Emissions Impact (in ppb) on Modeled Ozone exceedances

HOOD WISE

Site Monitor Site AVG MAX AVG MAX

EMTL Eagle M ountain Lake 0.010 0.03 0.520 0.81

KELC Keller 0.010 0.02 0.010 0.03

WTFD Parker

– Weatherford 0.030 0.16 0.670 1.29

In the course of our review, we requested and TCEQ provided additional modeling files that included

SAM results at most of the monitors in DFW

. EPA has reviewed this additional information and did discover some errors/discrepancies in TCEQ’s spreadsheets. 12 EPA shared the errors/discrepancies with TCEQ

. TCEQ had also used the average of the predicted ozone levels in the grid cells around the monitor, and EPA guidance is to use the maximum, so EPA reanalyzed the data using the maximum ozone levels in the grid cells around a monitor.

In analyzing SAM for a specific area for designation we evaluated the average impact, maximum impact, and an additional metric, the number of days where impacts may be high enough that reductions might be beneficial in developmen t of an attainment demonstration

. Often in attainment demonstration modeling, controlling of sources is evaluated and results in only a few tenths of a ppb change, therefore we used a 1% of the standard cut point for days where we would consider Hood or Wi se County’s impact to be significant

. We determined the number of days an impact was over 1% (0.75 ppb) on a modeled exceedance of the 75 ppb standard and also model exceedances greater than 70 ppb

. Also since

this SAM misses the mid to late summer meteorology/transport that results in high ozone and is not a full picture of DFW ozone exceedances, we put more weight on peaks and # of days over 0.75 ppb at area monitors (NA and near NA 2008

- 2010) . The corrected SAM and EPA’s assessment of TCEQ’s

SAM i s included in Table 13 and Table 14

.

12 Additional information has been included in the docket for this action and additional informa tion is included in a zipped file “TCEQ back

- up information.zip and EPA assessment of Matagorda.zip.”18 Table 13

. Corrected TCEQ Source Apportionment with EPA’s assessment

– Hood County Anthropogenic Emissions

HOOD Modeled days >75 ppb (2012)

# of days >0.75 ppb HOOD Modeled days >70 ppb (2012)

# of days >0.75 ppb Site AVG (ppb) MAX (ppb) AVG (ppb) MAX (ppb)

DENT Denton 0.06 0.48 0.06 0.48

EMTL Eagle Mtn. 0.10 0.46 0.19 1.12 1

KELC Keller 0.05 0.25 0.05 0.25

GRAP Grapevine 0.01 0.05 0.01 0.05

FWMC FW NW 0.03 0.17 0.07 0.45

FRIC Frisco 0.01 0.02 0.01 0.02

WTFD 1 Parker

- Weatherford 0.85 2.26 4 0.77 2.26 4

CLEB Cleburne 0.01 0.03 0.01 0.03

ARLA Arlington 0.01 0.02 0.00 0.02

PIPT Pilot Point 0.04 0.23 0.04 0.23

GRAN 1 Granbury (Hood) 2.34 5.77 9 2.63 5.77 9

Total Occurrences

1 Based on most recent certified monitoring data, the Parker and Hood County monitors have a DV of 75 ppb, which is in attainme nt of the

2008 8

- hour ozone NAAQS.19 Table 14

. Corrected TCEQ Source Apportionment with EPA’s assessment

– Wise County Anthropoge nic Emissions

WISE Modeled days >75 ppb (2012)

# of days >0.75 ppb WISE Modeled days >70 ppb (2012)

# of days >0.75 ppb Site AVG (ppb) MAX (ppb) AVG (ppb) MAX (ppb)

DENT Denton 0.13 1.15 1 0.128 1.15 1

EMTL Eagle Mtn. 0.36 0.86 1 0.677 5.03 2

KELC Keller 0.05 0.5 0.360 0.50

GRAP Grapevine 0.07 0.99 1 0.293 3.85 2

FWMC FW NW 0.09 1.08 1 0.104 1.08 1

FRIC Frisco 0.03 0.36 0.031 0.36

WTFD 1 Parker

- Weatherford 0.85 7.48 1 1.217 7.48 2

CLEB Cleburne 0.12 0.88 0.120 0.88 1

ARLA Arlington 0.17 1.72 1 0.124 1.72 1

PIPT Pilot Point 0.03 0.14 0.028 0.14

MDLO Midlothian 0.12 1.09 1 0.111 1.09 1

GRAN 1 Granbury (Hood) 0.33 3.07 1 0.308 3.07 1

GRVL Greenville 0.01 0.03 0.007 0.01

Total Occurrences 6 occurrences over 4 days 9 occurrences over 5 days

1 Based on most recent certified monitoring data, the Parker and Hood County monitors have a DV of 75 ppb, which is in attainme nt of the

2008 8

- hour ozone NAAQS20 In both Table 13 and Table 14 , the Parker and Hood County information is highlighted in green as these monitors are currently in attainment at the time of designation based on 2008

- 2010 data

. As a result, we have put little weight on the impact of emissions on Hood and Parker monitors. Hood County emissions do not have a large contribution on any days using the 75 ppb modeled threshold and only one day above with a contribution over 0.75 ppb using the 70 ppb modeling threshold on current DFW monitors (not including Parker or Hood monitors). Some concerns were raised that the SA M may include higher emissions than are currently present for Hood County sources and thus the SAM may be overestimating Hood County emission impacts

. Even without considering the potential uncertainty in the emissions for Hood County in the modeling, it d oes not appear that the modeling shows significant impacts on monitors that are currently violating the standard

. SAM does show significant impact on Parker C ounty from Hood at times but as mentioned previously, we did not put significant weight on these i mpacts because Parker County is cur rently attaining the standard.

In our evaluation of the Wise County SAM, Wise County emissions have a larger average and maximum contribution than Hood County emissions using the 75 ppb modeled exceedance threshold

. Furt hermore, when using this threshold, Wise County emissions resulted in 6 occurrences (over 4 days) of an impact of more than 0.75 ppb days on DFW monitors (not including Parker or Hood monitors)

. T o

t ak e into account concerns that the modeled period is not inclusive of all conditions that lead to high ozone and the modeling underestimation concerns, we also evaluated contributions to all modeled values of greater than 70 ppb

. This analysis indicated Wise County emissions had even larger impacts of up to 5 pp b on the Eagle Mountain Lake monitor, which is one of the monitors in DFW that sets the DV for

the DFW area

. This analysis also indicated that Wise County emissions resulted in 9 occurrences (over 5 days) that impacts of more than 0.75 ppb occurred at DFW area monitors (not including Parker or Hood

county monitors)

. It does appear that the SAM provides evidence for inclusion of Wise County.



### Factor 4 : Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the air shed and, therefore, the distribution of ozone over the area

. The DFW area does not have any geographical or topographical barriers significantly limiting air pollution transport into or within its air

shed

. Therefore, this factor did not play a significant role in this evaluation

.



### Factor 5 : Jurisdictional boundaries

Once we identified the general areas we anticipated we would recommend be included in the

nonattainment area , we then consider ed existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary and to help identify the areas appropriate for carrying out the air quality planning and enforcement functions for nonattainment areas

. Examples of jurisdictio nal boundaries include existing or prior nonattainment area boundarie s for ozone or other urban

- scale pollutants, count y lines , air district boundaries , township boundarie s, areas covered by a metropolitan planning organization, state lines, Reservation boundarie s, and urban growth boundar ies

. Where existing jurisdictional boundaries were not adequate or appropriate to describe the nonattainment area, other clearly defined and permanent landmarks or geographic c oordinates were considered.

The DFW area has previously established nonattainment boundaries associated with the 1

- hour and

1997 8

- hour ozone N AAQS

. Texas has recommended the boundary for the 2008 ozone NAAQS be the same as that for the 1997 ozone NAAQS

.21 In addition to the CSA boundary, an important boundary is that of the metropolitan planning organization (MPO). In the DFW area, the MPO is the North Central Texas Council of Governments, which is responsible for planning and implementing transportation programs and projects aimed at reducing congestion, enhancing mobility, and improving air quality . Th e 1 0 counties in the DFW 2008 ozone nonattainment area are in the same MPO boundary.

Freestone, Limestone, McLennan, Navarro and Robertson counties are outside of the DFW CSA. While

Navarro County is in side the DFW MPO boundary

, Freestone, Limestone, McLennan and Robertson

counties are not

. Furthermore, Freestone, Limestone and McLennan counties are in an MPO boundary that does not include Robertson County.



### Conclusion

Based on the assessment of factor s described above

, EPA has concluded that the following counties will be included as part of the DFW ozone nonattainment area because they have air quality monitors that

indicate a violation of the 2008 ozone NAAQS

, or because they are contributing to a violation in a nearby area : Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwell, Tarrant, and Wise

Counties

. These are the same counties that were included in the DFW nonattainment area for the 1997

ozone NA AQS , with the addition of Wise Count y

.

The air quality monitors in Collin, Dallas, Denton, Johnson, and Tarrant C ounties indicate violations of the 2008 ozone NAAQS based on the 2010 DVs, therefore these counties are incl uded in the

nonattainment area.

Ellis, Kaufman, Parker, Rockw a ll

, and Wise Counties are nearby counties that do not have monitors indicating ambient ozone concentrations in excess of 75 ppb , but EPA has concluded that these areas

contribute to observed violations of the 2008 ozone standa rd in nearby counties, through emissions from point sources and other

, non

- point sources (e.g., vehicles and other small area sources).

Collin, Dallas, Denton, Ellis, Johnson, Parker, Tarrant, and Wise Counties have among the highest NOx

and VOC emissions in the area. Each of these counties either has a monitor indicating a violation of the 2008 ozone NAAQS or is adjacent to one or more such counties.

Collin, Dallas, Denton, Ellis, Grayson, Hood, Johnson, Kaufma n, Parker, Rockwall, Somervell, Tarrant,

and Wise Counties ranked comparatively high for factors related to population statistics, and Collin, Dallas, Denton, Ellis , Johnson, Kaufman, Parker

, Rockwall , Tarrant, and Wise Counties ranked comparatively high fo r factors related to traffic data

.

EPA’s meteorological assessment when ozone exceedances of the 2008 ozone standard have been

monitored within the DFW area supports the consideration of inclusion of the existing 9

- county nonattainment area (Dalla s, Tarrant, Collin, Denton, Ellis, Johnson, Parker, Rockwall, and Kaufman counties) and Hood and Wise counties.22 Collin County: Recommended for inclusion by Texas and has a violating monito r
, so will be included.

Dallas County: Recommended for inclusion b y Texas and has a violating monitor

, so will be included.

Denton County: Recommended for inclusion by Texas and has a violating monitor

, so will be included.

Ellis County: Recommended for inclusion by Texas; has 2008 NEI emissions of 15, 768 tons of NOx and
6, 543 tons of VOC ; there are 160 people per square mile; has a 2010 population of 149,610 with a growth rate of 13.5 percent between 2000 and 2010; total VMT is 1.9 billion miles

. Winds often flow

from the south , southeast and east, so emis sions from Ellis County often contribute to violations in other

DFW counties. These factors, in conjunction with the number of commuters and growth rate support the

inclusion of Ellis County in the nonattainment area.

Hood County: H as 2008 NEI emissions o f 5,515 tons of NOx and 8 ,7 39 tons of VOC, with TCEQ 2009 Barnett Shale Special Inventory emissions of an additional 6,903 tons of NOx and 2,113 tons of VOC ; there are 120 people per square mile; has a 2010 population of 51,182 with a growth rate of 9.2 percent between 2000 and 2010; total VMT is 443 million miles

. Emissions from this county have grown considerably

, due primarily to oil and gas development. Back trajec tories show that at times Hood

C ounty emissions could potentially contribute to observe d violations in other counties. Much of the emissions from Hood County were based on oil and gas activities. We received information that exploration has dropped dramatically, calling into question whether current emissions are as high as estimated by TCEQ ’s special inventory. As discussed, we are giving little weight to the fact that Hood County emissions contribute to exceedances in Parker County because Parker County is currently monitoring attainment. Hood County is some distance from monitors that are currently violating the 2008 ozone standard. The SAM analysis conducted by TCEQ also does not indicate a significant impact from Hood County on currently violating monitors. Taken together, the amount of emissions, the

distance from the monitor , the popula tion and the VMT do not warrant inclusion of Hood County as part

of the nonattainment area.

Johnson County: Recommended for inclusion by Texas and has a violating monitor

, so will be included.

Kaufman County: Recommended for inclusion by Texas; has 2008 NEI emissions of 5,868 tons of NOx

and 3,510 tons of VOC ; there are 130 people per square mile; has a 2010 population of 103,350 with a growth rate of 17.6 percent between 2000 and 2010; total VMT is 1.5 billion miles

. Winds often flow

from the south, southeast and east

, so emissions from Kaufman C ounty often contribute to violations

other counties. These factors, in conjunction with the VMT and growth rate support the inclusion of

Kaufman C ounty in the nonattainment area.

Parker County: Recommended f or inclusion by Texas; has 2008 NEI emissions of 9,550 tons of NOx

and 11,708 tons of VOC ; there are 130 people per square mile; has a 2010 population of 116,927 with a growth rate of 15.4 percent between 2000 and 2010; total VMT is 1.3 billion miles

. The comparatively high emission s and population growth rate s indicate that Parker County should be included in the nonattainment area. In addition, at times back trajectories indicate that emissions from Parker C ounty
contribute to observed violations in the a rea

. These factors support the inclusion of Parker County in the

nonattainment area.

Rockw a ll County: Recommended for inclusion by Texas; has 2008 NEI emissions of 1,859 tons of NOx

and 2,047 tons of VOC ; there are 530 people per square mile; has a 2010 p opulation of 78,337 with a23 growth rate of 25.7 percent between 2000 and 2010; total VMT is 676 million miles

. While a small county, its population density and emissions support the inclusion of Rockwall County in the

nonattainment area.

Tarrant County: Re commended for inclusion by Texas and has a violating monitor

, so will be included.

Wise County: H as 2008 NEI emissions of 11,911 tons of NOx and 17 ,6 09 tons of VOC ; there are 60 people per square mile; has a 2010 population of 59,127 with a growth rate of 5.9 percent between 2000 and 2010; total VMT is 969 million

. The close proximity of these comparatively high emissions to violating monitors indicate s that this county should be included in the nonattainment area. T he high growth in t hese emissions is due in large part to growth in emissions from Barnett Shale gas production development, but also due to growth in population. Examination of back trajectories indicates th at at
times emissions from Wise C ounty contribute to observed violations in the area and also to observed violations that have helped set the DFW area DV in the past . Source apportionment modeling for a portion of an ozone season indicates that emissions from Wise County can contribute to observed

violations in the DFW nonattainment area. These factors support the inclusion of Wise County in the

nonattainment area.

McLennan and Navarro cou nties do not have violating monitors , and Freestone, Limestone, McLennan,

Navarro and Robertson counties are not nearby a county with a violating monito r. Freestone, Limestone, McLennan, Navarro and Robertson counties have significant levels of emissions of NOx and VOC and thus have the potential to contribute to monitored violations, but are not in or nearby c ount ies with a violating monitor. McLennan Co unty has a population greater than 60,000 and a population density greater than 100 people per square mile; and Freestone and McLennan counties have experienced population growth of at least 10 percent, indicating the potential to contribute to violations, b ut are not in or nearby counties with a violating monitor. Freestone, Limestone, McLennan, Navarro and Robertson counties have a small fraction of residents that work in the counties with violating monitors, which suggests that at this time there is litt le, if any integration with the urban core counties. Finally, Freestone, Limestone , McLennan, Navarro and Robertson counties are outside of the DFW CSA, and all but Navarro County are outside of the MPO boundary.

Our evaluation of data for Freestone, Limestone, McLennan, Navarro and Roberts on Counties does not support a nonattainment designation for the 2008 ozone standard at this time

. We do not believe these five counties are contributing to violations of the 2008 ozone standard in a nearby area.

Ou r evaluation of data for Cooke, Delta, Fannin, Grayson, Henderson, Hunt and Somervell Counties does not support a nonattainment designation. W e did not receive any comments that these counties

should be included in the DFW nonattainment area.24 

### ATTACHMENTS

A ppendix 1. Accessing Worker Data from http://onthemap.ces.census.gov/

.

Figure 2 . Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network, with Population Density.

Figure 3 . Population Density Change Percentage Between 2000 and 2010 Census for Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network.

Figure 4 . Overlay of 24

- hour HYSPLIT back trajectories of all 75 ppb exceedances at the Keller monitor

for the 2008

- 2010 period.

Figure 5 a. NOAA HYSPLIT MODEL 24

- Hour Back Trajectory Eagle M tn. Lake Exceedances (2006

- 10) (zoom view).

Figure 5 b . NOAA HYSPLIT MODEL 24

- Hour Back Trajectory Parker County Exceedances (2006

- 10)

.

Figure 5 c . NOAA HYSPLIT MODEL 24

- Hour Back Trajectory Parker County Exceedances (2006

- 10) (zoom view).25 A ppendix 1. A ccessing Worker Data from http://onthemap.ces.census.gov/

.

1. Open your internet browser to http://onthemap.ces.census.gov/

.

2. Click on “Text

- Only” in the upper right corner.

3. In the open search box, type the name of the county for which you seek information. Click on “Counties” in the drop

- down box for “Search All Names” and then click the “Go” button. The search results will appear on your screen and click on the appropriate county, even if you are o ffered only one

choice.

4. Analysis settings will appear next on your screen. To gather our worker data, under the Home/Work Area, we clicked on “Home.” Under the Analysis Type, we clicked on “Destination” and then under “Options for Destination: Destinat ion Type” we used the drop

- down box and clicked on “Counties.” We clicked on 2010 for the year, and “All Jobs” for the Job Type. Then scroll down to the bottom of the page and click the “Run Analysis” button.

5. The Work Destination Analysis will appear n ext on your screen. The default setting will show you the top 10 counties where workers are employed. To show additional counties, click on “Top 25” and then click the “Update” button.

6. To run analyses for additional counties, scroll to the top of the s creen and click on “Return to search.”26 Figure 2 . Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network, with Population Density27 Figure 3 . Population Density Change Percenta ge Between 2000 and 2010 Census

for Dallas

- Fort Worth Ozone and Ozone Precursor Monitoring Network28 Figure 4 . Overlay of 24

- hour HYSPLIT back trajectories of all 75 ppb exceedances at the Keller monitor for the 2008

- 2010 period29 Figure 5 a. NOAA HYSPLIT MODEL 24

- Hour Back Trajectory Eagle Mtn. Lake Exceedances (2006

- 10) (zoom view).30 Figure 5 b. NOAA HYSPLIT MODEL 24

- Hour Back Trajectory Parker County Exceedances (2006

- 10)

.31 Figure 5 c. NOAA HYSPLIT MODEL 24

- Hour Back Trajectory Parker County Exceedances (2006

- 10) (zoom view).