February 29,2012Al Armendariz, Ph.D.

Regional Administrator

U.S. Environmental Protection Agency (EPA), Region 6

1445 Ross Avenue, Suite 1200

Dallas, Texas 75202-2133Dear Dr. ArmendarizI'm writing in response to your December 9,2011, proposal to modify the state'srecommendation for designation of areas in Texas with regard to the 2008 National Ambient Air

Quality Standard (NAAQS) for eight-hour ozone of 0.075 parts per million. I respectfully

request that you not enact the planned designation of Hood, Matagorda, and Wise counties as

ozone nonattainment areas,

The enclosed analysis performed by the Texas Commission on Environmental Quality (TCEQ),

submitted pulsuant to Section i07(dX1XB) of the Federal Clean Air Act, demonstrates there isinsuffrcient scientific justification for EPA's proposed modification of the state's

recommendation for these three counties. These counties do not measure nonattainment at a

federal regulatory monitor, nor do they significantly contribute to elevated ozone measurementsat any violating monitors in the adjacent counties. In fact, EPA has always designated Hood,Matagorda, and'Wise counties as attainment/unclassifiable for ozone.TCEQ's analysis indicates that significant reductions in nitrogen oxide (NOx) emissions have

occurred in Hood, Matagorda, and Wise counties in the past eight years. Current permitting and

rule requirements, combined with technological advancements in industrial equipment, are

anticipated to continue this downward trend in NOx emissions without the need for theimposition of further rules and programs on citizens and businesses in the three counties. A

nonattainment designation for these three counties will undoubtedly stifle economic growthwhile providing little, if any, environmental benefit.

We have worked hard in Texas to strike abalance between meaningful environmental regulationand economic growth, and designating these counties as nonattainment is not a decision that

should be taken lightly, especially during these tough economic times. I thank you for your

Posr ornce B,ox 1.2428 Ausrn, Trrus 787t1 (512)463-2000 (voIce)/Dtx 7-1'-1 ron R¡mv SenvlcBs

Vrsn wwv.Tn<¡,sO¡u¡¡re.co[r rrr¡ Orncnr Wes SITE or tt¡r Smru or Tnx¡s
consideration of this issue. If you have any questions or need additional information, please feel

free to contact TCEQ Chairman Bryan Shaw at (512) 239-5510.

Sincerely,

H

Rick Perry

Governor

RP:jhp

Enclosures

cc Bryan W. Shaw, Ph.D

?*l
,,

 

The Honorable Rick Perry

Governor ofTexas

State CapitolP. O, Box tz4z9

Austin, TXTBTtt-z4zB

Dear Governor Perry:

In a December g, zoLi.lettel, the Unitecl States Bnvironmental Protection Agency (EPA)said it intencls to expand the Dallas-Fort Worth (DFW) and Houston-Galveston-Brazoria

(HGB) ozone nonattainment areas. This plan is inconsistent with the Texas

nonattainment designation recommenclaiion you submitted to the EPA in October zort,

I ¡ecommend you ask the EPA to teverse this plan, because there is insufficient scientific

justification for the EPAs ploposed expansion of these two ozone nonattainment areas.

Errclosed for your consideration is a comprehensive technical analysis that supports the

Texas position as well as a draft transmittal letter for your signature. State responses tothe EPA are due no later than February 29, zo7z,

The federal air quality standard. at issue is the EPA s zooB National Ambient Air. Quality Standard for eight-hour ozone of o.o7g parts per million. The BPA has said it intends to fÏnalize zoo8 eight-hour ozone nonattainment area designations by May gr, zor2.

Section toZ(dXtXB) of the Federal Clean Air Act plovides states the opportunity todemonstrate why the EPA's modifications to state nonattainment area reeommendationsare not appropriate, The technical analysis provided here is an expansion of the

response already submitted to the BPA on this matter on January rg, 2orz,by the Texas

Commission on Environmental Qualify during a brief EPA puÌ:iic comment períocl

announced, in the Federal Register on December 20, zo1t, over lhe holidays.

The counties at issue are Hood and Wise Counties in th,e DFW area and Matagorda

County in the HGB area. Thesethree counties neither fiìeasure nonattainment at a

fecleral regulatory ozone monitor for the years in question, zooB through zoro, nor do

they significantþ contribute to elevated ozone n'r.easurements ¿rt violating ozone

monitors in acljacent counties. In addition, these three counties have always beendesignatecl by the EPA as attainment/unclassified for [he federal ozone standards.

Thank you for youtsupport in this matter, If I can be of any assistance in submitting a

Texas response by the February zg due cìate, pìease contact me at (5rz) 289-SS1o.

.Síncerely, 3qn'6fi'd c*;u,^uû Shaw, Ph.D.

Chairman

Enclosures

P.O. Box r3oB7 Austin, Texas 787tt4oï7 . E1z-239-1ooo ' www,tccq.texas,gov

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U,S. Environmental Protection Agency

Mail Code 6rozT

tzoo Pennsylvania Avenue, N.W.

Washington, D.C. 20460Attn: Docket ID No. EPA-HQ-OAR-zoo8-o476

Re: United States Environmental Protection Agency (trPA)

Responses to State and Tl'ibal 2ooB Ozone Designation Recommendations: Notice

of AvaiiabiLity and Public Comment Period

Dear Sir or Madam:

The Texas Courmission on Bnvironmental Quality (TCEQ) provides the following comments on

EPA's response to the Texas recommendation for eooB ozone nonattainment designations. 'Iheavailability of a public comment period was published in the Decernber zo, 2otl, Ferlerql

Register (26 FR ZBBfz), The EPA's tirning of the 3o-day cotnment period during the holiday

season severeþ restricted the TCEQ's abilit¡r to provide thorough cornments within thestipulated time period.In sholt, the TCEQ believes that the EPA should reverse its plan to expand Texas nonattainment

areas in Houston and Dallas because there is no scientific justification for the proposed

expansion. The counties in question neither measure nonattainment at a federal r:egulatoryrnonitor nor do they significantly transporl. ozone precursors to vioìating rnonitors,

Background. For its zorz implernentation of the 2oo8 ozone stanclard, the EPA said in a

Decernber g, zoLr,ietter sent to the governor that it woulcl expancì. the Houston-GalvestorrBrazoria (HGB) and Dallas-Fofi Worth (DFW) ozone nonattainment areas. These areas were

established in zoo4 to implernent the LggT ozone standard. In particular, the EPA said itintends to add: Matagorcì.a County to the HGB eight-county nonattainment atea, and Hood anclWise Counties to the DFW nine-county nonattainment area. (The governor hacl recornnrendedthat the HGB area remain eight counties and the DFW area remain nine counties.)'Iire BPA reliecl significantly on meteorology (weather'/transport paLterns) to justify the inclusion

of the three counties as nonattainment. The TCBQ believes that the use of the National Oceanicand Atmospheric Administration Single ParLicle Lagrangian Integratecl Tlajectory Model

(HYSPLIT) was unsoundly applied as corloborative support for expanding the FIGB and DIW

nonattainrnent areas, I-IYSPLIT cannot provide evidence directly linking emissions frorn one

area to ozone formation in another area. Furtherrnole, I-IYSPLIT does not have the ability tocalculate poìlutant concentra[ions, Lhe types of pollutants added along the transport path from

P,O, Box t3oBT . Austin, Texas787u1o87 . 512-239-1ooo . www,tceq.texas.gov

How is our customer scrvíce? v¡ww.tceq,texirs.gov/goto/custornelsurvey

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could at times impact violating monitors. The TCEQ clisaglees with this analysis becauseernissions are in fact substantially lower than those cited by the BPA and because TCEQ's

technical analysis shows that very few wind trajectories thal travel through Matagorda

County impact violating monitors. Furthermole, Matagorda County does uol have a

federal regulatory ozone monitor, does not significantly contribute mobile- or areasource emissions to the HGB nonattainment area, and is outside the julisdictional

boundary of the Houston area's Metropolitan Planning Organization. Matagorda

County's eoro population, which has declinecl by S% between eooo and 2010, isapproximaLely 37,ooo residents cornpared to the HGB nonattainment area population ofapproximately 6 million residents.

Regarding emissions, the EPA December 9 letter cited high ernissions that

included non-road source emissions calculated frorn BPA-derived sulrogate.s.

However, in May zo1o, the TCBQ submitted locally obtained non-road emissions

data from commercial rnar"ine vessels and locomotives to the EPAfor-the PeriodicBmissions Inventory that lesult in z,9z8 tons pel year fewet" nitrogen oxides

(NOx) emissions. This corlection is a 42% r'eduction from the total emissions of

TooT lorLs per year cited by the EPA.

a

r Regarding wind patterns, the BPA cÍted back trajectory analysis that shows "at

times" emissions from Matagorda County could Ímpact violating rnonítors in the

HGB area. However, a review conducted by TCEQ technical experts created bacì<

trajectories for lìve years, i.e., eoo6 through 2o1o, fol days measuring gleatelthan 76 parts per billion at the Manvel Croix, Texas City, and Wallisville monitors

shows that at most only r,B% of the trajectory endpoints actually traverseMatagorda County, On the few days when Matagorda Countywas upwind of a

violating monitor, the back trajectolies routinely crossecl counties with far gleater

emissions, Again, a back trajectory traversing Matagorda County cloes notnecessariþ mean that emissions from Matagorda County have a significantimpact on ozone forrnatiorr.

Hoocl County. The EPA stated that Hood County should be designated nonattainment

because of considerable growth in emissions from oil and gas development, a wind

pattern that indicates emissions could at times impact violating monitors, aud a highpopulation growth. Although the most recent census data indicate that there has beensome population growth in Hood County, the TCBQ disagrees with this analysis because

emissions are iu fact substantially lower than those cited by the EPA and because TCEQ's

technical analysis shows very few wind trajectories that may irnpact violating monitors,

Furthermore, Hood County's design value for zoo8 through zoro measutes 75 parts per

billion, i.e., attainment of the zooB ozone standard,
g

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rnonitor, the EPA cited back trajectory analysis that shows at times emissions

from Hood County could irnpact a violating rnonitor'. Howevet, TCBQ's technical

experts indicate that at most 2.SS% of the trajectory endpoints from Hood County

irnpact violating monitors. The TCBQ's anaìysis of the days with the highest

ozone concentration do not indicate that Hood Countyemissions routineþirnpact DFW monitors.

Wise County, The BPA stated that Wise County should be desígnated nonattainmentbecause of its proxirnity to violating monitors, growth in emissions from Barnett Shaie

gas ploduction, a wind pâttern that indicates emissions could at times iurpact violatingmonitors, and growth in population. Although Wise County is ìocated near some

violating rnonitors ancl the most recent cerlsus clata indicate that there has been some

population growth in Wise County, the TCEQ disagrees with dris analysis because

emissions are in fact substantially iower than those cited by the EPA and because Texas

technical anaþsis shows that few wind trajectories would irnpact violating monitors,

Furtherrnore, Wise County does not have a federal regulatory ozone monitor and is

primarily a rulal county with a low population density,

' Regarding growth in emissions from Barnett Shale gas production, dre emissions citecl by the EPA did not include the TCEQ revision to oil ancl gas

sector pneumatic emissions submitled October 2011 to the EPA for the PeriodicEmissions Inventory, which results in 6,o48 tons per year feuter VOC emissions

than those cited by the BPA.

. Regarding wind patterns and proximity of emissions to a violating

rnonitor, the EPA cited backtrajectory analysis that shows at times ernissionsfrom Wise County could impact a violating monitor. However, TCBQ's technical

experts indicate that at most z.B7%o of the trajectory endpoints from Wise County

impact violating monitors.

Conclusion. In conclusion, EPA has not provided an adequate justification for the expansionof the HGB and DF'W nonattainment areas for implementation of the zoo8 ozone standard.

Furthermore, the TCEQ believes there would be no justifTcation for the associated imposition of

rrrles and programs on citizens and businesses in these counties associated with such anonattainment designation. Given the lack of evidence in all cases, it appears EPA cherrypicked data for the sole purpose of adding these counties to nonattainment areas. Therefore, the

TCEQ specifically requests that the EPA reverse its plan to clesignate Hood, Matagorda, andWise Counties as nonattainment counties.
R.Vickery, P.G.,

Texas Commission on Quality
Evaluation of the EPA's Factor z: Emissions and Emissions-Related Data

The BPA is proposing that Matagorda County should be designated nonattainment because of the

amount of emissions and their belief that these emissions may, at times, impact violating ozone

monitors in Brazoria and Harris Counties. The TCEQ analysis of current emission data indicates

emissions in Matagorda County are in fact substantially lower than those cited by the EPA. The EPA's

December g, zorr,letter cited emissions that included non-road source emissions calculated from EPAderived sun'ogates. However, in May zoro, the TCEQ submitted locally obtained non-road emissionsdata from commercial marine vessels and locomotives to the EPA for the Periodic Emissions Inventory

that result in z,9z9 tons per year fetuer nitrogen oxides (NOx) emissions in Matagorda County. This

correction is a 4z% reduction from the total NOx emissions of 7,oo7 tons per year cited by the EPA.

The EPA's technical support document stated that population and urban growth patterns were also

considered in their evaluation of emissions related data. Matagorda County's 201o population, which

has decline dby g% between eooo and 2o1o, is approximately 37,ooo residents compared to the

Houston-Galveston-Br azoria (HGB) nonattainment area population of approximately 6 millionresidents. The EPA's analysis also points out that Matagorda County only has 343 million vehicle miles

travelled OnViT) compared with an area-wide VMT of 96, B7B million miles. In fact, Matagorda County

is the only county in the area with a decrease in VMT, i.e., r%o,between the zooz to zoo8 time periodreviewed by the EPA. The EPA's technical support document states that "Total VMT is an importantmetric as an indicator of potential contribution to ground level ozone concentrations."

The EPA is proposing that Hood County should be designated nonattainment in part due to

considerable growth in emissions from oil and gas development. Howevet, the emissions cited by theEPA did not include the TCEQ revision to oil and gas sector pneumatic emissions submitted October

2011 to the EPA for the Periodic Emissions Inventory, which results in BoB tons per year fetuer volatile

organic compound (VOC) emissions in Hood County than those cited by the EPA.

The BPA is proposing that Wise County should be designated nonattainment in part due to

considerable growth in emissions from Barnett Shale gas production. However, the emissions cited by

the EPA did not include the TCEQ revision to oil and gas sector pneumatic emissions submitted

October 2011 to the EPA for the Periodic Emissions Inventory, which results in 6,o48 tons per yeal

feuer VOC emissions in Wise County than those cited by the EPA.

Wise County's 2o1o population is 59,tz7 residents compared to the Dallas-Fort Worth (DFW)

nonattainment area population of approximalely 6.2 million. The Wise County's zoo8 VMT was 969million miles compared with an area-wide \rtvlT of 6r,9oo million miles.

Emissions from Oil and Gas Development

Non-combustion sources account for approximately gg% of zoo8 oil and gas area source VOC

emissions in Hood, Matagorda, and Wise Counties. VOC emissions from non-combustion emission

sources in the oil and gas industry are generally alkanes and would not be expected to significantly

contribute to ozone formation due to their low reactivity. The EPA's technical analysis has notdemonstrated that these VOC emissions have had a significant impact on area ozone formation. TheEPA should carefully analyze the chemical composition of VOC emissions for each county and

Page r
None of the lab analyses for these sites reported detectable quantities of highly reactive volatile organic

compounds as defined by go Texas Administrative Code (TAC) Chapter rr5. Similarly, the EPA

SPECIATE software's emissions profile for oil and gas production activities does not contain thesecompounds. Therefore, the TCEQ would not expect these emissions to significantly contribute to ozone

formation in these counties based upon currently available data.

Since the zooz periodic inventory year, Matagorda County condensate and gas production peaked in

2ooB and has declined to levels beìow zooz production levels. Matagorda County's zoro production

levels for gas and condensate represent a nine-year low in pro<luction (zooz through zoro). Comparedto zoo8 peak levels, 2o1o gas production declined by g60/o and zoro condensate production declined by

49%.YOC area source emission estimates from oil and gas production have declined accordingly,4o%from zoo8 to 2o1o.

Since zoo8 represents an atypical, outlier year for both gas and condensate production, and since zoro

VOC emissions from oil and gas production have declined below both zoo5 and zoo8 emissions

estimates, the outlier zoo8 data should not be used either to evaluate the impact of VOC emissions

from oil and gas operations in Matagorda County or to potentially designate the county as

nonattainment for ozone. See Table t for more detail.Table 1: Matagorda County Gas, Condensate, and Oil Production

Condensate

(bbl)

%" of zooSCondensateProduction

oil (bbl)

o/" of zooSoilProduction

Year Total Gas (mscÐ %o of zoo8 Gas Production

2002 38,927,7t7 B+% Bz7,Bt6 77% t,245,863 358%

2O03 32,391,351 70% 6zg,6tB 59% 1,325,355 SBt%

2OO4 27,65t,4o6 59% 666,5oo 6z% 6t9,565 tTBo/o2OO5 31,538,651 6B% 665,t56 6z% 527,52r t5z%zoo6 40,879,756 BB% 773,314 72% 45r,840 t3o%2007 37,OO4,320 Bo% 849,957 79% 374,064 toB%

zooB 46,5t4,2o7 TOOo/o t,o69,z4B too%o 347,868 too%o

20O9 40,723,331 BB% 757,8r7 70% 331,112 95%

2010 29,736,754 6+% 6o6,zzo 57% 4oo,786 u5%

Source: Texas Railroad Commission, January 13,2ol2Supplemental Analysis on the EPA's Factor z: Emissions and Emissions RelatedDataIndustrial emissions sources located in Hood, Wise, and Matagorda Counties are currently subject toseveral state rules, which are listed below, limiting the ozone precursor emissions of VOC and NOx as ameans to control ozone pollution. Many emissions sources in Hood, Wise, and Matagorda Counties are

Page z
NOx emissions has occurred while these counties have been classified as attainment and demonstrates

that reclassification of these counties to nonattainment is not warranted to continue these emission

reductions. Permitting and rule requirements combined with technological advancements in industrial

equipment are anticipated to continue this downward trend in NOx emissions from major industrial

sources in Hood, Matagorda, and Wise counties.Table 2: Percent Change in Point Source NOx Emissions in Tons Per Year (tpy)

2010',NOx tpy, Pércent Change from 2002 To:20L0

Hood

Matagorda

Wise

5,964

2,044

2,895

L,178

972 ,

2,163

-80%

-s2%

-2s%

The specific state rules and general permitting requirements applicable to Hood, Wise, and Matagolda

Counties and other attainment areas are listed below.Current State Rules Applicable in Hood and Wise Counties

The following state rules were adopted to reduce VOC emissions:

. Low Emission Fuels (Gasoline Volatility) - these rules establish volatility requirements for gasoline

and diesel fuels intended to power engines (go TAC Chapter rr4, Subchapter H, Division r).

. Loading and Unloading of VOC - these rules control VOC emissions and by establishing control, _ inspection, testing, and monitoring requirements for general VOC loading, disposal of transported

vapors, gasoline terminals, gasoline bulk plants, and marine terminals (Chapter u5, Subchapter C,

Division r).

r Filling of Gasoline Storage Vessels (Stage I) for Motor Vehicle Fuel Dispensing Facilities - these

rules establish control requirements for the transfer of gasoline at a vehicle dispensing facility

(Chapter rr5, Subchapter C, Division z).

. Control of VOC Leaks from TransportVessels - these rules provide the inspection, testing, and

recordkeeping requirements for tank-trucks that will be filled with gasoline or non-gasoline VOCwith a certain vapor pressure (Chapter u5, Subchapter C, Division 3)'

The following state rules were adopted to reduce NOx emissions:

. Nitric Acid Manufacturing - these rules apply to production units of any nitric acid production unit

and establish emission specifications during manufacturing (3o TAC Chapter ll7, Subchapter F,

Division 3).

. Small Boilers, Process Heaters, and Water Heaters - these rules establish emission specifications

for boilels, heaters, and water heaters operating under a specific capacity threshold (Chapter rr7,

Subchapter E, Division 3).

Page 3
. Diesel Emission Reduction Incentive Program for On-Road and Non-Road Vehicles (Hood County)

- these rules offer grant opportunities for on-road and non-road diesels to reduce diesel emissions

(Chapter rr4, Subchapter K, Division 3).

Current State Rules Applicable in Matagorda County

The following state rules were adopted to reduce VOC emissions:

. Low Emission Fuels (Gasoline Volatiliry) - these rules establish volatility requirements for gasoline

and diesel fuels intended to power engines (Chapter rr4, Subchapter H, Division t).

¡ Storage of VOC - these rules establish control requirements for VOC storage tanks and condensate

storage tanks (Chapter 115, Subchapter B, Division r).

. Vent Gas Control - these rules establish control requirements for emissions of VOC from process

vents (Chapter 11S, Subchapter B, Division z).

. Water Separation - these rules provide control requirements for VOC water separators (Chapter

u5, Subchapter B, Division 3).

. Loading and Unloading of VOC - these rules estabìish control requirements for general VOC

loading, disposal of transported vapors, gasoline terminals, gasoline bulk plants, and marine

terminals (Chapter rr5, Subchapter C, Division r).

. Filling of Gasoline Storage Vessels (Stage I) for Motor Vehicle Fuel Dispensing Facilities - these

rules establish control requirements for the transfer of gasoline at a vehicle dispensing facility

(Chapter n5, Subchapter C, Division z).

. Control of VOC Leaks from Transport Vessels - these rules establish the inspection, testing, and

recordkeeping requirements for tank-trucks to be filled with gasoline or non-gasoline VOC with a

certain vapor pressure (Chapter rr5, Subchapter C, Division 3).

The following state rules were adopted to reduce NOx emissions:

. Nitric Acid Manufacturing - these rules apply to production units of any nitric acid production unit

and establish emission specifications during manufacturing (Chapter r17, Subchapter F, Division 3).

. Small Boilers, Process Heaters, and Water Heaters - these rules establish emission specifications

and control requirements for boilers, heaters, and waterheaters operating under a specific capacity

threshold (Chapter rr7, Subchapter E, Division 3).

. Low Emission Fuels (Low Emission Diesel) - these rules establish aromatic hydrocarbon and cetane

number requirements for diesel fuels intended to power engines (Chapter rr4, Subchapter H,

Division z).

General New Source Review (NSR) Permit Requirements for an Attainment Area. Public notice requirements.

, Federal requirements in 4o Code of Federal Regulations (CFR) Subparts 60, 6L, and 63, where

applicable, are integrated into permit conditions.

Page 4
. Title V permits are required for major sources and other certain sources.. Standard permits are available for certain industrial classification sources and establish BACT for

each of those industries

. Oil and Gas Handling and Production Facilities Permit by Rule (PBR) (Chapter ro6, Subsection O,

9ro6.gSz) was updated in zorr and applies in the Barnett Shale, which includes Wise and Hood

Counties.

Evaluation of the EPA's Factor 3: Meteorology (weather/transport

patterns) for the DFW Area

Current Understanding of Ozone Formation in the DFWAreaOzone formation in the DFW area, as in most areas, depends largely on interaction of three factors:

local emissions of ozone precursors, ozone-conducive meteorology, and existing or transported

background ozone and precursors. The Dallas-Fort Worth-Arlington area is the fourth largest

metropolitan area in the United States, home to nearly 6.5 million residents as of zoog (United States

Census Bureau, 2o1o), which contribute to the DFW's emission inventories in various ways. Substantialamounts of precursor compounds, chiefly NOx and VOC, are emitted by three major source categories:mobile sources, point sources, and area sources.

Mobile sources include cars, trucks, planes, locomotives, and construction equipment. Point sourcesinclude most industrial equipment, such as cement kilns; boilers; process heaters; gas, diesel, and dualfuel fired stationary engines; stationary gas turbines; duct burners used in turbine exhaust ducts; lime,

brick, and ceramic kilns; metallurgical heat treat and reheat furnaces; lead smelting; reverberatory and

blast furnaces; incinerators; glass, fiberglass, and mineral wool processing facilities; natural gas-fired

heaters, dryers and ovens; and electricity generation facilities. The DFW area hosts all of the above

equipment.

Higher background ozone concentrations in the DFW area are usually observed when winds originate

from the south and southeast, while lower concentrations are observed when winds originate from the

north and west. Background and transport appear at this time to play a secondary, though not

inconsequential, role in DFW ozone photochemistry, at least when compared to local sources. However,

these sources may contribute a greater fraction of the total in the future as local emissions reductions

are implemented.

Meteorology also affects other key processes, such as chemical reaction rates (Banta, et al., zooS). High

ozone concentrations are observed most frequently in the DFW area on days lacking strong synoptic, or

large-scale, pressure gradients. When synoptic (large-scale) weather systems move through the region,

ozone and precursor emissions tend to be diluted and carried out of the city, rather than concentratedin still, stagnating air, to be heated, reacted, and turned into ozone. Days dominated by strong syrroptic

weather systems tend to experience low ozone levels (Banta, et al', zoo5).

Absent dominant synoptic weather systems, smaller-scale local wind patterns govern ozone formation.As precursor emissions are advected across the region, they mix with other local emissions, as well as

compounds transported into the region, to generate elevated concentrations of ozone. On days with

light winds, precursors generated in the morning, along with those remaining from the previous day,

accumulate and then react during the warmest and sunniest portion of the day. Ozone rich air masses

Page 

5
industry, the area produces enough emissions to result in a high ozone day when meteorologicalconditions are favorable.

Analysis of EPA's Modeling for Hood and Wise Counties

The EPA proposed nonattainment designation for Hood and Wise Counties based on their belief thatthe emissions from these counties contribute to observed violations in the area. This section describes

why the tools used by the EPA are not capable of nor appropriate for providing such as determination

and that these counties do not significantly contribute to the highest ozone levels.

The EPA evaluated available meteorological data to help determine how meteorological conditions,

such as weather, transport patterns, and stagnation conditions, would affect the fate and transportprecursor emissions contributing to ozone formation. The EPA used the National Oceanic and

Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory (NOAA

HYSPLIT) Model as its primary modeling tool.

This HYSPLIT analysis is simple in nature and is only capable of giving a qualitative examination of

areas that may influence design value at key ozone monitoring sites. The HYSPLIT model, which creates

back trajectories, is not capable of directly linking ozone or pollutants in one area to another. Hourly

endpoints are the hourly estimates of air parcel location from FfYSPLiT that compose a back trajectory,

The whole back trajectory is the mean-path of an air parcel over space and time. The model uses

meteorological data to estimate hourly positions of wind parcels in space and time. Because the

analyses show large numbers of back trajectories converging on a single fixed point, the model

introduces a built-in bias, which tends to give higher endpoint counts in are¿is near the receptor sites,

such as an ozone monitor.

The EPA's argument depends highly on the path a trajectory took before reaching a receptor ozone

rnonitor. Simply looking at back trajectories when the daily maximum ozone is greater than 75 pafts per

billion (ppb) will not establish that these trajectories increase ozone levels at any single ozone monitor.To improve upon EPA's back trajectory analysis, the TCEQ analyzed back trajectories developed by the

EPA to better understand the effects of upwind regions that may affect ozone monitors in the DFWarea.

The TCEQ created HYSPLIT z4-hour backtrajectories during zoo6 through zoro. The HYSPLITtrajectories coincide with days when maximum daily eight-hour ozone was greater than 75 ppb in the

DFW area. These trajectories are at Boo meters in height, well within the mixing layer during the day,

but not too low that the trajectories touch ground level, thereby invalidating the trajectory. This analysisbetter highlights the true extent of trajectories passing through Wise and Hood Counties. The analysis

used three DFW ozone monitors, nameìy Eagle Mountain (Mtn.) Lake, Keller and Parker ozone

monitoring sites. The EPA used a starting height of roo meters, which often left trajectories touchingground level and can result in erroneous back trajectories over time.

The back trajectory hourly endpoints generated from FIYSPLIT were plotted on a map. The backtrajectory hourly endpoints that appeared over Hood and Wise County were counted. One set of backtrajectories and hourly endpoints were plotted for ozone design value sensitive monitors such as the

Parker, Eagle Mtn. Lake and Keller ozone monitors. A lower frequency of endpoints indicates less

Page 6
trajectories shows that some trajectories meander into other counties before terminating at Eagle Mtn.

Lake. A cursory count of endpoints shows the majority of endpoints are within Tarrant County, EagleMtn. Lake's residing county. This is an update of the anaþis noted in the TCEQ's January rL,2orz,response to comment letter that stated at most only z.B7% of the trajectory endpoints actually traverse

Wise County.The number of hourly endpoints leading to the Parker County ozone monitor ís 3.9o% for Wise County

(Figure 3) and z.z7% for Hood County (Figure +). The zoro design value setting monitor for the DFW

area is Keller. The hourly endpoint count for Keller is 2.77% for Wise County (Figure S) and o.69% forHood County (Figure 6). The TCEQ noted in its January !r,2or2, response to comment letter that atmost only 265% of the trajectory endpoints actually traverse Hood County. This slight revision is theresult of further review of trajectory data.

This back trajectory analysis indicates that wind seldom passes over either Wise or Hood County before

reaching ozone monitors on high ozone days. These analyzes and this tool, however, do not indicate if

Hood or Wise County emissions significantly contribute to ozone formation at these ozone monitors.

Figure 1: The map shows trajectory endpoints (in red) in Wise County for receptormonitor Eagle Mtn. Lake (5.75o/o).

t.

i.,, :

l$r.

afe ûndpoiùts

ate endpoirìls irì Wise eo.

Page 7
lti'.

li.r

Hood cor':

Figure 3: The map shows trajectory endpoints (in red) ¡n Wise County for receptormon¡tor Parker County (3.9oolo),

å

Wlse

'-i 

,,ir' i,;''

ìl

,;1..,r' 

,,

dols û16 HYSFL IT 6rì¿poirìl$

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24 TIYSiILIT A.rLi trÉl!cLar;!3 (f.irúili ãîC;r\1

53

1¡6

Page B
I"

Figure 5: The map shows trajectory endpoints (in red) in Wise County for receptormonitor Keller (2.7 7 o/o).

Page 9
Supplernental Analysis on Factors z: Emissions and Emissions Related Data and3: Meteorology (weather/transport patterns) for the DFW Area

The TCBQ utilized an additional modeling tool, Comprehensive Air quality Model with extensions

(CAMx) Anthropogenic Precursor CulpabilityAssessment (APCA), as complementary information to

the meteorology and emissions factors. APCA is a modeling tool that can be used to keep track of the

origin of the NOxand VOC precursors creating the ozone at specified locations during a model run. Theozone can then be apportioned to specific user-defined sources groups and regions. The TCEQ used

APCA to determine the eight-hour ozone contribution from Hood and Wise Counties to specific ozone

monitors in the DFW area for zoo6 and zot2. These APCA luns used the same June zoo6 episodemodel setup (meteorology, emissions, CAMx version, etc.) as the Dallas-Forl Worth Attainment

Demonstrations SIP Revision fol the 1997 Eight-Hour Ozone Standard Nonattainment Area adoptedDecember 7,2orr (zou DFWAD SIP Revision). The June zoo6 episode was shoum to be representativeof typical ozone-conducive conditions in the DtrW area, including impacts from local and non-DFWsource areas vla r¡nnd directions from the east, southeast, and south. Details on the June zoo6 episodecan be found in the episode selection of the DFW modeling protocol atclf#p+le=gz.

The TCEQ did not use the updated oil and gas sector pneumatic emissions submitted October 2011 tothe BPA for the Periodic Emissions Inventory in this modeling and source apportionment analysis,therefore, the VOC emissions from this source category are likely overestimated in the modeling.

Figure 7, Figure B, and Figure 9 display the zore contributions to the Keller, Eagle Mtn. Lake, and

Weatherford (Parker County) ozone monitors from Hood County, Wise County, the initial andboundary conditions (IC/BC), and ali other areas of the modeled domain, including DFW

(DFW+Other). The modeled June zoo6 episode is shown. Throughout most of the episode theDFW+Other and the ICIBC source regions dominate the contributions to total predicted ozone.

oa %

.)t.

Page ro
20L2 Eagle Mounta¡n Lake APCA Contributions

o

a

."ü- ..sþ .".d' ."e" .¡¡ -.*9 .o' "ú" .".." ".$' ,,.$' .,,r' ¡rþ .ef ..s$ .+þ ."+h ..o" -dþ ...1þ .,jru ..d' .,.f ..¡i' "ou .+þ ^+k . o( ".r$ .lÞ .¡1' ¡t' .,*S rf ,tù "ti'- ".ñ uf) o"'- o.r .st' "{,.'ñ.'-.'t',,f)'"r.1'J .,*"' n' "r¡'ño''",$t'"iy'' "c" cd'*¡'s"'.rtrt'C'J,'' "aÈ'.1+t'"t}' ^+'

Figure 8: 2O12 Future Case Eagle Mtn. Lake Eight-Hour Ozone APCA Results

çDFwr0rNer BIC/ãC

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Figure 9= 2OL2 Future Case Weatherford (Parker County) Eight-Hour Ozone APCA Results

2012 Weatherford APCA Contributions iwisc u Hôod

s OFW+Otlr¿r ù lClBC

o

0.00

-."" .df .,rP """' ,.ú "S r." ."é' ..d ...9' "e" ^"s d ."s" ,"""' ,"ó9 .ró" ..."' ,"ô" ."d ,"s" ,"s'' ,.dJ" .d ."s"" ,."ú ,r"" ".o' .r"t" .,f' "{n ..""" .,r'i' ..ro' ñt' ñt' "'-t' ñt" ô"t' .$t' ",-t' .r"t'*'.t'",'-'*'ù'.r-t'"t'-'"r"t" ^"'aat'"r-*'*'^'"**'o;r'o1ù\',ilt'or.$'ntrl'"ttd" J".td'.t¡t.rst' ^¡t"

Page rr
maxima does not correspond to the modeled design value or any specific maximum daily eight

hour

concentration.

The average modeled contributions of ozone from Hood County emissions to the three ozone monitors

were less than o.r ppb. The average modeled contributions of ozone from Wise County emissions were

less than o.01 at the Keller monitor. At the Eagle Mtn. Lake and Weatherford (Parker County) ozonemonitors, the average modeled contributions of ozone from Wise County emissions were less than o.7ppb.

Figure 1O: 2012 Modeled Ozone Contributions at Keller

2ALZ Keller Modeled Contribution

6s7s (ppb) for Hours > 75 ppb

59.90 W Averrallc Con tri l¡t¡tion

W Maxirrunì Contrìburtion

23.24

1-9,L5

ffi 0.0r- 0.02 0.01 0.03

DFW{"ùthor t-ìoocl Wise IC/BC

Page tz
¡

¡

23.75

20.63

0,01 0.03 0.52 0.81-

DFWi'Othcr l-lood !Visc rc/BC

Figure t2= 2OL2 Modeled Ozone Contributions at Weatherford (Parker County)

åOLZ Weatherford (Parker Co.)

Modeled Contribution (ppb) for

58.95 61.76 HOUfS > 75 ppb MAvcragccorrtribution

W M¡xinLrnr ConLr¡butiÒn

1g.g5 20.22

0.03 0.16 0.61 r,29

Lü.,r ffi#$

tffiffi

DFW tOthcr þlood WiSc IC/BC

Another benefit of the APCA tool is that it determines how NOx and/or VOC emissions create ozone

from each of the defined source categories and regions. At the Weatherford (Parker County) ozone

monitor NOx emissions from Hood and Wise Counties created g7-gg% of the contributed ozone from

these counties, while VOC emissions were only responsible for t-g% of the contributed ozone from these

counties. The availability of biogenic VOC emissions, generally more reactive than local anthropogenic

VOC emissions, most likely influences the importance of anthropogenic NOx emissions.

Using the APCA results, contributions from Hood and Wise Counties to the zotz future design values at

the Keller, Eagle Mtn. Lake, and Weatherford (Parker County) ozone monitors were calculated as

shown in Table 3. The fractions of the relative response factors from Hood and Wise Counties were

Page r3
Bagle Mtn. Lake Keller Future Future

Source Region Future Contribution Contribution Contribution

Hood County

Wise County

DFW+Other

rc/Bc

0.08%0s3%

76.52%22.86%

0.0r%0.o1%

78.O4%

21,.93%

7,25%1.25%

73.L1%

24.37%

APCA DVT too.o% 1.00.0% 100.0%

Nots Thè epCe DVr total may not equal the sum of the soulce regiou contlibutions due to rounding.

As with the APCA results shorvn in Table 3, the contributions from Hood and Wise Counties to the zorz

Keller future design value (DVr) are very small. At the Eagle Mtn. Lake and Weatherford (ParkerCounty) ozone monitors, the contributions are larger since those ozone monitors are closer to Hood and

Wise Counties. The contributions are less than one ppb, which indicates the majority of the zorz designvalue comes from the DFW area and other areas of the modeling domain.

Evaluation of the EPA's Factor 3: Meteorology (weather/transport

patterns) for the Houston-Galveston-Brazoria (HGB) Area

Current Understanding of Ozone Formation in the HGB AreaOzone formation in the HGB area is generally associated with relatively clear skies, light winds,abundant sunshine, and temperatures above Bo to Bb degrees Fahrenheit. Typically, thesemeteorological conditions are associated with high pressure areas that migrate across the United Statesduring the summer season. And just as important, precursor compounds to ozone need to be present

for ozone formation. Houston has all these factors including the presence of millions of people, the

presence of numerous NOx and VOC emissions sources, and meteorological conditions favorable to theformation of ozone from those emissions.

The processes that create emissions in the Houston area typically are continuous, in large amounts, and

present every day. Therefore, meteorological patterns are the controlling force that either dilute andcarry pollution out of the city (Banta, et al., zoo5) or concentrate pollution causing high ozone events.

This concentration of pollution or emissions typically is the result of the land-sea breeze flow reversals

and a shoreline convergence zone, which combine to form a rotational wind pattern that often recirculates emissions over ozone precursor sources, amplifying ozone formation dynamics (Banta, et al.,

2oo5; Nielson-Gammon et al., zoo5b).

Research on the meteorology of the HGB area has found that the highest background ozone transportedinto the HGB area predominately originates from the north and northeast (Nielson-Gammon et al.,

zoo5a). Similarly, a transport study that links measured ozone with a wind direction found that winds

originating from the south tend to have the lowest ozone concentrations (Sullivan, zoog). The higher

background concentrations are associated with winds that originate from the northeast, east or "short"trajectories that represent stagnation. Trajectories from the southwest are not generally associated with

high background ozone levels being transported into the HGB nonattainment area.

Page t4
Analysis of EPA's Modeling for Matagorda County

The EPA evaluated available meteorological data to help determine how meteoroìogical conditions,

such as weather, transport patterns, and stagnation conditions, would affect the fate and transportprecursor emissions contributing to ozone formation. The EPA used the NOAA FrySPLIT Model as itsprimary modeling tool.

The TCEQ performed its own analysis using HYSPLIT and concluded that the EPA's conclusions

regarding potential transport from Matagorda County is unsupportable. The key tool the EPA used toderive its transport argument is the FIYSPLIT model. The back trajectory tool simply calculates airparcel's mean-path movement in space and time. Both the TCEQ and BPA agree that only a few

trajectories traverse Matagorda County before reaching the ozone monitors in the HGB area. The

distinction between the EPA and TCEQ position is that the EPA fails to show on a scientific or statistical

basis that such a small number of trajectories could adversely affect the ozone design values at these

ozone monitoring sites in particular and the HGB nonattainment area in general. The EPA does not

present any scientific or statistical evidence to support its claim of adverse impact from transport nor

does the EPA quantify the number of trajectories passing over Matagorda County and how many would

be required to cause a noticeable or significant effect. The BPA also lacks any corroborating evidence,

such as an ozone monitor in Matagorda County to show that those trajectories in question actually

contain ozone - or at the very least sufficient ozone to adversely impact the HGB nonattainment area.

This cannot be sufficient to lead the EPA to conclude that transport through Matagorda adversely

affects the HGB nonattainment area.Following EPA's back trajectory analysis, the TCEQ analyzed back trajectories to show the frequency

that Matagorda County was upwind of the ozone monitors in the HGB area.

HYSPLIT z4-hour back trajectories were created for zoo6 through zoro. These trajectories are at Boo

meters in height, well within the mixing layer during the day, but not too low that the trajectories touch

ground level, thereby invalidating the trajectory. The EPA's use of too meter height trajectories is

technically faulty. Furthermore these FrySPLIT trajectories coincide with days when maximum daily

eight-hour ozor,e was greater than 75 ppb in the HGB area. The TCEQ's analysis used trajectories

terminating at three HGB ozone monitoring sites, namely Manvel Croix, Texas City, and Wallisville

Road. Please note that the Wallisville ozone monitor is not a regulatory monitor and it was used in the

TCEQ's analysis only because it was used by the BPA in their modeling. There were 4.z24 hourly

endpoints generated using the HYSPLIT model. This analysis was conducted to highlight the true extentof the number of trajectories passing through Matagorda County.

To assess the EPA's HYSPLIT analysis, the TCEQ delineated Matagorda County and then overlaid thetrajectories. A back trajectory is the mean-path of an air parcel over space and time. Back trajectories

are composed of hourly points that track a trajectory's path on an hourly basis. The Manvel Croix,

Wallisville, and Texas City ozone monitors had hourly endpoints that fell in Matagorda County andwere counted. A lower frequency of endpoints indicates a lower probability that an air parceltransported ozone from Matagorda County to an ozone monitor.This analysis is simple in nature and is only intended to give a qualitative indication of areas that may

have been upwind of design value setting monitors. An important distinctiori of the HYSPLIT model,which creates the back trajectories, is that it is not intended to directly link ozone or pollutants in one

Page 15
endpoints actually traverse Matagorda County. This slight revision is the result of further review of

trajectory data. Therefore, Matagorda County emissions would rarely have an opportunity to impact

ozone monitors because they are seldom upwind of the ozone monitors during periods of eìevatedozone. In addition, there are other emission sources between Matagorda County and the ozonemonitors. Note that locally produced ozone can have the greatest impact at the ozone monitor,especially in an area such as Houston, which has a large automobile fleet, is densely populated, and is

highly industrialized.

Figure 13: Map shows hourly trajectory endpoints (in red) in Matagorda County for the

Wallisville ozone monitor (O.43o/o).

it :.t

lrlå1ù{¡ordi Çp: '"^

' -: -., . (}r$y ftût$ iìrr,J l..tyÊf:* lI f.ittú¡*tiì giml doll; ¡rrù y¡|riirrr;r($ r,r l-.l.lrtal Çt¡

:j.t : ì,.! { l j ' ììi,í i l it"!,i t,ri¡)t !;:r.r.r t !¡t:t,! ì 1 ?i.Þj,t ^t: !?r. i;ìt3 q,rj Hí t.!r: ¿.:r 'lììritì;lì,ìj,,rr:!:!,!.¿r,.;i:ar{ii,,i.r,rå,.*:,;lì,j,a"il..f.:-r,.i":.ìiÀii:-

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1¡ I rfjf¡.t¡f,. 1ì,.:,.ì¡r'ì.i ir; ti.åt¡.li¡. r., i:¿r

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¡ èd'

Page 16
:l: t.

t

dtlii ilrù lrYbi¡t-f { (ìrìÕilO(1ll;

OilÈ .li* &Í(]p,i¡n{t rn I'l'rlâû¡ rC¡ C-Ì,

irrìi..¡,rìi-rjiri.:f,ri1..'ìr¡ji4il,!4:i/!1,,f,ií.r..,'. "'iirfll,..,il::!i.1i,*:ì'

I :ìr¡i r.i l.;:¡l 1 i.1rù..1!r i¡r'jjl';lil,rj i:i+îr.ftr (.rjji,/rt].1 r.J tn:\r,ìfr:1,! r:i:1

, ,... t.. , ,.r,:,,,,,...

Figure 15: Map shows hourly trajectory endpo¡nts (in red) in Matagorda County for theNorthwest Harris ozone monitor (0.92olo).

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ir

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j;1fdi..rì(l/rii.i:-tjirtirt,i:rrqllJi:¡;:j1;jl.):ìr¡,¡iìifìr,!irí.;iìí.rù31

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Page 17
Ms

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n

.-..-.. ^ .+" ----.... --,-.--.,

Given that the trajectory count is not large at Matagorda County and the EPA does not presentadditional evidence to support the transport of pollutants or ozone, there is not enough evidence tosuggest that Matagorda County adversely affects ozone design values in the HGB area.Supplemental Analysis on Factors z: Emissions and Emissions Relatcd Data and3: Meteorology (weather/transport patterns) for the HGB Area

The EPA used the NOAA HYSPLIT as its primary modeling tool. The TCEQ utilized an additional

modeling tool, APCA, as complementary information on the meteorology and emissions factors. APCA

is a modeling tool that can be used to keep track of the origin of the NOx and VOC precursors creatingthe ozone at specified locations during a model run. The ozone can then be apportioned to specific userdefined sources groups and regions. The TCEQ used APCA to determine the eight-hour ozone

contribution from Matagorda County to specific ozone monitors in the HGB area for zoo6 and zor8,

although 2006 data will be the focus of this document since eor8 is several years future. These APCA

runs used the same episodes and model setup (meteorology, emissions, CAMx version, etc.) as the

Houston-Galveston-BrazoriaAttainment Demonstration State Implementation Plan Revision for thet997 Eight-Hour Ozone Standard adopted March 10, 2o1o (zoto HGB AD SIP Revision).Figures r7 and rB display the zoo5 and zoo6 contributions of ozone from Matagorda County emissions

to the Manvel Croix ozone monitor and Figures 19 and 20 to the Wallisville ozone monitor, respectively.

Also shown are the ICIBC and all other areas of the modeled domain, including HGB+Other. Separate

charts are provided for the collective zoo5 and zoo6 episodes. Throughout all episodes, the

HGB+Other and the ICIBC source regions dominate the contributions to total predicted ozone. In fact,

it is difficult to see any contribution of ozone from Matagorda County emissions at all. Charts were alsodeveloped for the Northwest Harris County ozone monitor (Figures zr and zz) and the Texas City ozonemonitor (Figures z3 and z4), but contributions of ozone from Matagorda County emissions were even

less notable.

Page rB
o@c

o

604070

^80 ¡o

o

;60

o

o¿o

5¡rot{zrPo!þlt'iþrt"!þrttþrzo$arr{¡zr{*l{zol{zzl{2atz00u5¡2en$zøPoiþ.rt$*r{æl2o0lrrrxo%plxooTprz0\plz0o5

e! tclBc åS HGB+Other ¡ Matagorda

Figure 18: 2OO6 Baseline Manvel Croix Eight-Hour Ozone APCA Results

MACP 2006 8-Hour APCA (Matagorda Run)

20

0

ss rcl8c lr,{ HGB+Other ¡ N¡atagorda

120

100

u¡:rl{zt2o0f¡oroof¡erd*rr.þrzoþltþrtiir.ltiioru.þrt"þrr.þrz0$zrxo$arro$ortþrz.þrtiixrz$^rz$arr$rrroffçrzo6

Page 19
I

6040

20

eoc

o

o

u¡rur{*r0þt{'",t{rtr{.rrr{.rro%rrt{"el{zor2$zrr$rortoþrtoþrto!þrz$prtt!þrt"'?¡rlz0o5s¡rl2o0l¡rp00I¡tz006

ø tclBc ãf HGB+Other ¡ Matâgorda

Figure 2O: 2OO6 Baseline Wallisville Eight-Hour Ozone APCA Results

WALV 2006 8-Hour APCA (Matagorda Run)

L20100

^80 o

ee;60

o¿o

20

o

,¡rrt2o0åztxooåapo.åorz""f¡orzoþrz.þrtþrt'iþrt'þrttþrt'þrr'þrr0$rrxo$arr$oru"þrz'|þrztiþrz$arz$orz$øltlffonoou

N tclBc & HGB+Other I Matagorda

Page zo
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o

20

6040

20

rt$*rr.$ær.þrt þrt$*r{irr{¡zt{"er2ooueport'þrt"oj*rt$*lr$*rz0116rz$2orlo!]ærxo%rrr?0%¡rlzo\¡stro\¡t2005

M IC/BC !ñ HGB+Other I Matagorda

Figure 22: 2OO6 Baseline Northwest Harris County Eight-Hour Ozone APCA Results

Ì HNWA 2006 8-Hour APCA (Matagorda Run)

!20

100

^80 !

ooo60o

o¿o

u¡,,rxoof¡,r'ooånpooå.*-"ï:;'jÞr"iþr'"ii'.r"þ*'*TiJ:*.Ïzrz$ar{orzoþ""','*:i1'rz$ørz$øræfþrzo06

Page zt
TXCT 2006 8-Hour APCA (rVlaiaeorA" nun)

720

oo60 c

Oao

zo

6r rclBc åã HGB+Other I Mâtagorda

Figure 24= 2OO6 Baseline Texas City Eight-Hour Ozone APCA Results

u¡rot{zlzo$*tt'þrt$rtr{1er{arPo%rrl{rrr{zorz0o.]*r"o$r^rz'$rorz""jptr{"orr$2trzo!]ærtoo!¡rPoo!plzo0!¡sl{¡lz0o5

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u¡r't20$ztxooåorzooåordørzoþrz"þrz.þrt ii*rt'þrztþrttþrz'þrz0$zrzo$orro$orttþrt"iþrt'iixrz$^rr$orx$etzoffrotzo06

tâ rclßc W HGB+Other I Matagorda

Figures z5 through 32 show the average and maximum contributions of ozone from Matagorda Countyemissions to the Manvel Croix, Wallisville, Northwest Harris County, and Texas City ozone monitors in

zoo5 and 2c,c,6. The IC/BC and all other areas of the modeled domain, including HGB+Other, are also

represented. The blue bars exhibit the average contribution of ozone for eight-hour ozone periods

grãater than or equal to ZS ppb, while the red bars exhibit the maximum contribution of ozone during

ihe eight-hour ozone periods greater than or equal to 75 ppb at that ozone monitor. The maxima from

Matagorda, HGB+Other, and ICIBC source areas could have occurred on different days or eight-hourperiods and thus, the sum of the maxima does not correspond to the modeled design value or any

specific maximum daily eight-hour concentration.Of all the ozone monitoring sites evaluated, the Wallisville ozone monitor shows the largest average

contribution of ozone from emission source categories in Matagorda County, although the contribution

is small (o.r8 ppb). The Northwest Harris County ozone monitor had a modeled average contribution of

o.u ppb from Matagorda County emissions.

Page zz
70.1,1,

26.13

L5.84

0.04 0.4I

HGB+Other Matagorda rclBC

Figure 2û 2OO6 Modeled Ozone Contributions at Manvel Croix

2006 MACP Modeled Contribution

(ppb) for Hours > 75 ppb

702.70

w Average Contrìbution

¡ff Maximum Contribut¡on

64.53

29.37

18.40

W

o.10 1.05

HGB+Other Matagorda tc/sc

Page z3
70.68

0.09 0.44

HGB+Other M ata gorda tclBc

Figure 28: 2OO6 Modeled Ozone Contributions at Wallisville

2006 WALV Modeled Contribution

z+.sz (ppb)for Hours > 75 ppb

64.02

¡:a Average Contribut¡onW Maximum Contribution

24.8r

18.1 1

0.18 0.46

HGB+Other Matagorda rclBc

25.28

r+.rz ffii

hffiffi

Page z4
27.L9

0.04 1,26 Wffi

HGB+Other Matagorda IC/BC

Figure 3O: 2OO5 and 2OO6 Modeled Ozone Contributions at Northwest Harris County

2006 HNWA Modeled Contribution

zs.sr(ppb) for Hours > 75 ppb

63.37

ä.1 Average Contr¡but¡on

$s Maximum Contr¡bution

2s.08

18.01

0.11 1.86

HGB+Other Matagorda IC/BC

Page z5
24.4L

17.28

0.05 0.2L

HGB+Other M atagorda rclBc

Figure 32: 2OO6 Modeled Ozone Contributions at Texas City

2006 TXCT Modeled Contribution

g¡.zz(ppb)for Hours > 75 ppb

i* Average Contrìbut¡on

K Maximum Contribution

29.83

16.61

O.rZ 1 63

HGB+Other M atagorda tc/Bc

Using the APCA results, contributions from Matagorda County to the zor8 future design values at theManvel Croix, Northwest Harris County, Texas City, and Wallisville ozone monitors were calculated asshorvn in Table 4. The fractions of the relative response factors from Matagorda County wele multipliedagainst the observed baseline design value to determine the contribution. As with the 2o1o AD HGB SIP

Revision, this methodology followed the EPA modeling guidance for calculating a future design value.

Page z6
APCA DVn 100.00% rc0.00% 100.00% 1,oo.00%

Note: The APCA DVr total may not equal the sum of the soulce }egion cont|ibutions due to t'ounding.

As with the APCA results shown in Figures z5 through 32, the contributions from Matagorda County to

the zor8 design values are very small. Of the ozone monitoring sites evaluated, the Wallisville ozone

monitor receives the largest contribution of ozone from Matagorda County emissions, although even itis exceedingly small (o.zo ppb). AIì of the contributions of ozone from Matagorda County emissions atthese modeled monitoring sites are significantly less than r ppb, which indicates the majority of the

zor8 design value comes from the non-Matagorda County areas of the modeling domain. Based on

these results, the likelihood of ozone and ozone precursors from Matagorda County significantly

impacting the HGB ozone design values is too small to warrant including Matagorda County in the HGB

nonattainment area.

Page z7