Federal Register / Vol. 74, No. 9 / Wednesday, January 14, 2009 / Rules and Regulations 1903 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this rule does not have 

tribal implications as specified by 

Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the state, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this action and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by March 16, 2009. 

Filing a petition for reconsideration by 

the Administrator of this final rule does 

not affect the finality of this action for 

the purposes of judicial review nor does 

it extend the time within which a 

petition for judicial review may be filed, 

and shall not postpone the effectiveness 

of such rule or action. This action may 

not be challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2).) 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Carbon monoxide, 

Incorporation by reference, 

Intergovernmental relations, Lead, 

Nitrogen dioxide, Ozone, Particulate 

matter, Reporting, Emission inventory 

and recordkeeping requirements, Sulfur 

oxides, Volatile organic compounds. 

Dated: November 24, 2008. 

Stephen S. Tuber, 

Acting Regional Administrator, Region 8. 

PART 52—[AMENDED] 

■ 1. The authority citation for Part 52 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

Subpart TT—Utah 

■ 2. Section 52.2320 is amended by 

adding paragraph (c)(68) to read as 

follows: 

§ 52.2320 Identification of plan. 

* * * * * 

(c) * * * 

(68) On September 7, 1999 and 

December 1, 2003 the State of Utah 

submitted revisions to its State 

Implementation Plan (SIP) to 

incorporate the requirements of the 

Consolidated Emission Reporting Rule 

(CERR). The revisions update the State’s 

emission reporting rules so that they are 

consistent with the revisions EPA made 

to the CERR on June 10, 2002. 

(i) Incorporation by reference. 

(A). Title R307 of the Utah 

Administrative Code, Rule 307–221 

EMISSION STANDARDS: EMISSION 

CONTROLS FOR EXISTING 

MUNICIPAL SOLID WASTE 

LANDFILLS, Rule 307–221–1, Purpose 

and Applicability. Effective January 7, 

1999. Published in the Utah State 

Bulletin, Volume 98, Number 22, 

November 15, 1998. 

(B). Title R307 of the Utah 

Administrative Code, Rule 307–150 

EMISSION INVENTORIES, Rule 150–1, 

Purpose and General Requirements; 

Rule 150–2 Definitions; Rule 150–3 

Applicability; Rule 307–150–5 Sources 

Identified in R307–150–3(2); Rule 307– 

150–6 Sources Identified in R307–150– 

3(3); Rule 307–150–7 Sources Identified 

in R307–150–3(4). Effective December 

31, 2003. Published in the Utah State 

Bulletin, Volume 23, Number 23, 

December 1, 2003. 

(ii) Additional Material. 

(A) October 15, 2002 letter from 

Richard Long, EPA Region VIII to Rick 

Sprott, Director, Utah Division of Air 

Quality (UDAQ) notifying UDAQ of the 

June 10, 2002 publication of the 

Consolidated Emission Reporting Rule 

(40 CFR Part 51, Subpart A) and the 

need for the State to update its emission 

inventory reporting requirements. 

[FR Doc. E9–520 Filed 1–13–09; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R06–OAR–2007–0524; FRL–8758–7] 

Approval and Promulgation of Air 

Quality Implementation Plans; Texas; 

Attainment Demonstration for the 

Dallas/Fort Worth 1997 8-Hour Ozone 

Nonattainment Area 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule; conditional approval 

and full approval. 

SUMMARY: The EPA is conditionally 

approving the Dallas/Fort Worth (DFW) 

1997 8-hour ozone State 

Implementation Plan (SIP) revisions 

submitted on May 30, 2007 and 

November 7, 2008, as supplemented on 

April 23, 2008. This final conditional 

approval action is for the attainment 

demonstration SIP, which includes the 

2009 attainment Motor Vehicle 

Emissions Budgets (MVEBs), the 

Reasonably Available Control Measures 

(RACM) demonstration, and the failureto-attain contingency measures plan. 

The approval is conditioned upon Texas 

adopting and submitting to EPA prior to 

March 1, 2009, a complete SIP revision 

to limit the use of Discrete Emission 

Reduction Credits (DERCs), beginning in 

March 2009. If the State meets its 

commitment to submit the DERC SIP 

revision, EPA will undertake additional 

rulemaking action on the approvability 

of the DERC SIP revision and, if EPA 

approves that SIP revision, the 

conditional approval of the attainment 

demonstration will be converted to a 

full approval at that time. 

We are fully approving two local 

control measures relied upon in the 

attainment demonstration, the 

Voluntary Mobile Source Emission 

Reduction Plan (VMEP) and 

Transportation Control Measures 

(TCMs). We are also fully approving the 

DFW area SIP as meeting the 

Reasonably Available Control 

Technology (RACT) requirement for 

volatile organic compounds (VOCs) for 

both the 1-hour and 1997 8-hour ozone 

standards. These actions will result in 

emissions reductions in the DFW 8-hour 

ozone nonattainment area and meet 

section 110 and part D of the Act and 

EPA’s regulations. 

DATES: This final rule is effective on 

February 13, 2009. 

ADDRESSES: EPA has established a 

docket for this action under Docket No. 

EPA–R06–OAR–2007–0524. All 

documents in the docket are listed on 


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the www.regulations.gov Web site. 

Although listed in the index, some 

information is not publicly available, 

e.g., CBI or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically through 

www.regulations.gov or in hard copy at 

the Air Planning Section (6PD–L), 

Environmental Protection Agency, 1445 

Ross Avenue, Suite 700, Dallas, Texas 

75202–2733. The file will be made 

available by appointment for public 

inspection in the Region 6 FOIA Review 

Room between the hours of 8:30 a.m. 

and 4:30 p.m. weekdays except for legal 

holidays. Contact the person listed in 

the FOR FURTHER INFORMATION CONTACT

paragraph below or Mr. Bill Deese at 

214–665–7253 to make an appointment. 

If possible, please make the 

appointment at least two working days 

in advance of your visit. There will be 

a fee of 15 cents per page for making 

photocopies of documents. On the day 

of the visit, please check in at the EPA 

Region 6 reception area at 1445 Ross 

Avenue, Suite 700, Dallas, Texas. 

The State submittal, which is part of 

the EPA record, is also available for 

public inspection at the State Air 

Agency listed below during official 

business hours by appointment: Texas 

Commission on Environmental Quality, 

Office of Air Quality, 12124 Park 35 

Circle, Austin, Texas 78753. 

FOR FURTHER INFORMATION CONTACT: Ms. 

Carrie Paige, Air Planning Section 

(6PD–L), Environmental Protection 

Agency, Region 6, 1445 Ross Avenue, 

Suite 700, Dallas, Texas 75202–2733, 

telephone (214) 665–6521; fax number 

214–665–7263; e-mail address 

paige.carrie@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document, ‘‘we,’’ ‘‘us,’’ 

and ‘‘our’’ means EPA. 

Table of Contents 

I. Background 

II. What Action Is EPA Taking? 

A. What Is EPA Conditionally Approving 

in This Action? 

B. What Is EPA Fully Approving in This 

Action? 

III. What Happens if the State Fails To Meet 

the Condition? 

IV. What Other Elements Must Be Approved 

To Allow This Final Conditional 

Approval of the Attainment 

Demonstration SIP? 

V. Comments 

A. What Comments Did EPA Receive on 

the July 14, 2008 Rulemaking for DFW? 

B. General Comments 

C. Comments on the Texas Emissions 

Reduction Plan (TERP) 

D. Comments on Photochemical Modeling, 

Weight of Evidence Analyses, and 

Assessment of Demonstration of 

Attainment 

E. Comments on Discrete Emission 

Reduction Credits (DERCs) 

F. Comments on Reasonably Available 

Control Measures (RACM) 

G. Comments on the Failure-to-Attain 

Contingency Measures Plan 

H. Comments on the Attainment Motor 

Vehicle Emission Budgets (MVEBs) 

I. Comments on the Voluntary Mobile 

Source Emission Reduction Program 

(VMEP) 

VI. Final Action 

VII. Statutory and Executive Order Reviews 

I. Background 

On July 14, 2008, 73 FR 40203, EPA 

proposed conditional approval of the 

DFW area’s 1997 8-hour ozone 

attainment demonstration SIP revision, 

including the attainment MVEBs, RACM 

demonstration, and failure-to-attain 

contingency measures plan. We 

proposed to fully approve two local 

control measures relied upon in the 

attainment demonstration—the VMEP 

and TCMs. We also proposed to fully 

approve the DFW area SIP as meeting 

the RACT requirement for VOCs for 

both the 1-hour ozone standard and the 

1997 8-hour ozone standard. 

The proposed approval of the 

attainment demonstration SIP is 

conditioned upon Texas adopting and 

submitting to EPA by March 1, 2009, a 

complete SIP revision that includes an 

enforceable mechanism that would 

allow no more than 3.2 tons per day 

(tpd) of DERCs to be used in 2009 in the 

DFW area. If Texas intends to allow for 

more than 3.2 tpd of DERCs to be used 

beginning January 1, 2010, then the SIP 

revision must also provide appropriate 

limits on the use of DERCs and a 

detailed justification explaining how the 

future adjustments to the allowed DERC 

usage will be consistent with continued 

attainment of the 8-hour ozone 

standard. The justification must provide 

sufficient detail such that the public can 

be assured that attainment will continue 

to be projected in future years. If Texas 

meets the commitment to submit the 

DERC SIP revision, EPA will undertake 

rulemaking to determine whether to 

approve the revision and, if approved, 

EPA would convert the conditional 

approval of the attainment 

demonstration to a full approval. 

We also proposed that final 

conditional approval of the attainment 

demonstration SIP was contingent upon 

Texas submitting to EPA a complete and 

approvable SIP revision for the 

attainment demonstration SIP’s failureto-attain contingency measures plan that 

meets section 172(c)(9) of the Act. EPA 

specifically identified in the proposal 

the elements such submission must 

contain. The failure-to-attain 

contingency measures plan was 

submitted to EPA on November 7, 2008, 

and we have determined that the plan 

is consistent with the elements 

established in our proposed rule (73 FR 

40203) and meets section 172(c)(9) of 

the Act. Because the State submitted a 

complete failure-to-attain contingency 

measures plan that relies upon three 

VOC SIP rules for Offset Lithographic 

Printing, Degassing or Cleaning of 

Stationary, Marine, and Transport 

Vessels, and Petroleum Dry Cleaning, as 

well as fleet turnover from mobile 

sources after 2009, EPA can proceed 

with a final conditional approval. (See 

page 40205, third column, of the 

proposed action.) 

Our July 14, 2008, proposal provides 

a detailed description of the revisions 

and the rationale for EPA’s proposed 

actions, together with a discussion of 

the opportunity to comment. The public 

comment period for these actions closed 

on August 13, 2008. See the Technical 

Support Documents (TSDs) and our 

proposed rulemaking at 73 FR 40203 for 

more information. 

II. What Action Is EPA Taking? 

A. What Is EPA Conditionally 

Approving in This Action? 

EPA is conditionally approving the 

DFW 1997 8-hour ozone attainment 

demonstration SIP and, as part of this 

attainment demonstration SIP, the 2009 

attainment MVEBs, RACM 

demonstration, and failure-to-attain 

contingency measures plan, submitted 

to EPA on May 30, 2007 and November 

7, 2008, as supplemented on April 23, 

2008. 

Our conditional approval is based on 

our determination that, the modeling 

and weight-of-evidence show that the 

DFW area will attain the 8-hour ozone 

standard by its attainment date, as a 

result of the control strategies relied 

upon in this plan. In making this 

determination, we have considered the 

comments that we have received on our 

proposal. We have also considered the 

air quality monitoring information 

gathered since the proposal, the impact 

of the Clean Air Interstate rule (CAIR) 

vacatur, and the progress in 

implementing control measures. As the 

area approaches the attainment date, 

recent monitoring data becomes more 

important as an indicator of potential 

success. The preliminary data from 2008 

shows 18 of the 20 monitors had fourth 

highs at 84 ppb or below and only two 


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monitors were slightly above attainment 

levels at 85 ppb. 

With more emissions reductions to 

occur before the beginning of the 2009 

attainment year ozone season, we 

believe these data provide strong 

support that the area will attain the 

standard by its attainment date of June 

2010. 

As described in the proposed rule, the 

condition that must be met for EPA to 

fully approve the attainment 

demonstration is that the TCEQ must 

adopt and submit to EPA a complete SIP 

revision by March 1, 2009, that includes 

an enforceable mechanism that provides 

a 3.2 tpd restriction on the amount of 

DERCs available for use in DFW 

beginning March 1, 2009. The SIP 

revision may provide that the amount of 

DERCs available for use beginning 

January 1, 2010, could increase above 

3.2 tpd if the revision provides an 

enforceable mechanism and a 

justification that the increase is 

consistent with attainment and 

maintenance of the 1997 8-hour ozone 

standard. In a letter dated June 13, 2008, 

TCEQ committed to meeting this 

condition (the letter is in the docket for 

this rulemaking). 

If Texas intends to allow for more 

than 3.2 tpd of DERCs to be used 

beginning January 1, 2010, then the SIP 

revision must also provide appropriate 

limits on the use of DERCs and a 

detailed justification explaining how the 

future adjustments to the allowed DERC 

usage will be consistent with continued 

attainment of the 8-hour ozone 

standard. The justification must provide 

sufficient detail such that the EPA and 

the public can be assured that 

attainment will continue to be projected 

in future years. The justification and 

methodology for any increase in 

allowable DERC usage must be fully 

identified in the TCEQ rulemaking and 

SIP submittal process. 

The SIP revision submitted by March 

1, 2009, must adequately provide for 

continued attainment, and include the 

justification and/or methodology used 

by TCEQ to increase the amount of 

DERCs allowed for use in DFW starting 

in calendar year 2010. The justification 

provided by TCEQ must satisfy section 

110(l) of the Act by demonstrating that 

the increase will not interfere with 

attainment or any other applicable 

measure of the Act. The analysis to 

satisfy section 110(l) will need to 

address both quantity and spatial 

allocation impacts of increased DERC 

usage on ozone levels. 

B. What Is EPA Fully Approving in This 

Action? 

EPA is fully approving two local 

control measures relied upon in the 

attainment demonstration: The VMEP 

and TCMs. We are also fully approving 

the DFW area SIP as meeting the RACT 

requirement for VOCs for both the 1- 

hour ozone standard and the 1997 8- 

hour ozone standard. 

III. What Happens if the State Fails To 

Meet the Condition? 

If Texas fails to adopt and submit to 

the EPA a complete DERC SIP revision 

by March 1, 2009, EPA will issue a letter 

to the State converting the conditional 

approval of the 1997 8-hour ozone DFW 

attainment demonstration SIP to 

disapproval. Such disapproval will start 

the 18-month clock for sanctions in 

accordance with section 179(b) and 40 

CFR 52.31 and the 2-year clock for a 

Federal Implementation Plan (FIP) 

under section 110(c). EPA would 

publish in the FR a notice announcing 

the disapproval of the SIP and the start 

of sanctions and FIP clocks for the DFW 

area, and would revise the provisions in 

the Code of Federal Regulation (CFR) to 

reflect the disapproval of the SIP. 

The State proposed the DERC SIP 

revision for public review on August 6, 

2008 and the comment period closed 

September 12, 2008; final adoption of 

the revision was on December 10, 2008, 

in order to meet the condition to submit 

a complete DERC SIP revision to EPA by 

March 1, 2009, and implement the 

DERC SIP revision by March 1, 2009. As 

described in the proposed rule (73 FR 

40203), if the State adopts and submits 

to EPA by March 1, 2009, a complete 

DERC SIP revision, and EPA determines 

through rulemaking that the submitted 

DERC SIP revision is approvable, we 

will simultaneously convert the 

conditional approval of the attainment 

demonstration SIP to a full approval. If 

EPA cannot fully approve the SIP 

revision concerning the use of DERCs in 

the DFW area, EPA will undertake 

rulemaking to disapprove the submitted 

DERC SIP revision and to convert the 

conditional approval of the attainment 

demonstration SIP for the DFW area to 

a disapproval. In such case, the 18- 

month clock for sanctions and the 2- 

year clock for a FIP would start on the 

effective date of final disapproval. 

Today’s final conditional approval of 

the attainment demonstration SIP 

remains in effect until EPA either 

determines that the State has not 

submitted a complete DERC SIP revision 

by March 1, 2009 or EPA completes 

rulemaking action either approving or 

disapproving a complete submitted 

DERC SIP submission and simultaneous 

with action on the DERC SIP submission 

takes final action to convert the 

conditional approval to a full approval 

or disapproval of the attainment 

demonstration. 

IV. What Other Elements Must Be 

Approved To Allow This Final 

Conditional Approval of the Attainment 

Demonstration SIP? 

In our proposal, we discussed the 

elements that must be approved if we 

are to finalize the conditional approval 

of the attainment demonstration. In 

order to finalize conditional approval of 

the DFW 1997 8-hour ozone attainment 

demonstration SIP, EPA must fully 

approve all of the control measures 

relied upon in the attainment 

demonstration and the DFW RFP Plan 

with the RFP MVEBs and RFP 

contingency measures. We approved the 

DFW RFP Plan with the RFP MVEBs 

and RFP contingency measures on 

October 7, 2008 at 73 FR 58475. 

The State committed to submit a rule 

restricting DERC usage by March 1, 

2009. In addition, EPA reviewed all 

DERC Notice of Intent to Use Forms that 

the TCEQ Executive Director approved 

as of November 30 for use in 2009, to 

ensure that the total amount of DERCs 

approved for use beginning on March 1, 

2009 does not exceed 3.2 tpd. 

Table 1 below lists the status of EPA 

action on the control measures relied 

upon in the attainment demonstration. 

The Table documents that, as of this 

final action, all control measures and 

reductions relied upon to demonstrate 

attainment have been reviewed and 

approved by EPA in this or other 

Federal Register Actions. 

TABLE 1—STATUS OF EPA REQUIRED ACTION ON CONTROL STRATEGIES BEFORE FINALIZING CONDITIONAL APPROVAL OF

THE ATTAINMENT DEMONSTRATION SIP 

Measure Status 

The April 9, 2003 Alcoa Federal Consent Decree ................................... Approved August 15, 2008 (73 FR 47835). 

The DFW Energy Efficiency Measures Program ..................................... Approved August 15, 2008 (73 FR 47835). 

NOX rules for IC engines in DFW ............................................................ Approved August 15, 2008 (73 FR 47835). 


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TABLE 1—STATUS OF EPA REQUIRED ACTION ON CONTROL STRATEGIES BEFORE FINALIZING CONDITIONAL APPROVAL OF

THE ATTAINMENT DEMONSTRATION SIP—Continued 

Measure Status 

2002 Base Year Emissions Inventory ...................................................... Approved August 15, 2008 (73 FR 47835).

The VOC rules adopted by Texas on 11/15/06 ....................................... Approved July 17, 2008 (73 FR 40972). 

1-hour attainment determination .............................................................. Approved October 16, 2008 (73 FR 61357). 

East Texas Combustion Sources (i.e., the rich burn gas-fired engine 

rule in the 33 counties east of DFW).

Approved December 3, 2008 (73 FR 73562). 

The DFW major source rule ..................................................................... Approved December 3, 2008 (73 FR 73562). 

The DFW minor source rule ..................................................................... Approved December 3, 2008 (73 FR 73562). 

The DFW gas-fired engine rule ................................................................ Approved December 3, 2008 (73 FR 73562). 

The DFW EGUs rule ................................................................................ Approved December 3, 2008 (73 FR 73562). 

The DFW non-EGUs rule ......................................................................... Approved December 3, 2008 (73 FR 73562). 

The Auxiliary steam boilers rule in the 5 counties ................................... Approved December 3, 2008 (73 FR 73562). 

The Stationary gas turbines rule in the 5 counties .................................. Approved December 3, 2008 (73 FR 73562). 

The Cement kiln rules .............................................................................. Approved simultaneously in today’s Federal Register. 

The VMEP and its emission reductions ................................................... Approved in this rulemaking. 

The TCMs and the associated emission reductions ................................ Approved in this rulemaking. 

The TERP emission reductions ................................................................ Approved in this rulemaking as submitted in the DFW 5% IOP Plan 

and the DFW 1997 8-hour ozone attainment demonstration SIP. 

V. Comments 

A. What Comments Did EPA Receive on 

the July 14, 2008 Proposed Rulemaking 

for DFW? 

We received 26 comment letters on 

the proposed rulemaking. These 

comments are available for review in the 

docket for this rulemaking. The 

comment letters came from the 

following sources: 

1. August 6, 2008 letter from Linda Koop, 

City of Dallas Councilmember, District 11, 

Chair of the Transportation and Environment 

Committee. 

2. August 12, 2008 letter from Ramon 

Alvarez, PhD, for Environmental Defense 

Fund. 

3. August 12, 2008 letter from Bill Cox, 

citizen. 

4. August 12, 2008 letter from Margaret 

DeMoss, public health consultant and 

citizen. 

5. August 12, 2008 letter from Ed Soph, 

citizen. 

6. August 12, 2008 letter from Bob 

Fusinato, citizen. 

7. August 12, 2008 letter from Ramsey 

Sprague, citizen. 

8. August 13, 2008 letter from Jon Mamula, 

citizen. 

9. August 13, 2008 letter from Kerrie 

Kimberling, citizen. 

10. August 13, 2008 letter from Cindy 

Crutch, citizen. 

11. August 13, 2008 letter from Becky 

Bornhorst, clean air advocate. 

12. August 13, 2008 letter from Barbara 

Downey, citizen. 

13. August 13, 2008 letter from Ricky 

Pearce, Ryan Whaley Coldiron Shandy PC, 

for Holcim LP. 

14. August 13, 2008 letter from Neil 

Carman, for Sierra Club, Lone Star Chapter. 

15. August 13, 2008 letter from Gina Hall, 

citizen. 

16. August 13, 2008 letter from Molly 

Rooke, citizen. 

17. August 13, 2008 letter from Marc 

Chytilo, for Downwinders At Risk and the 

Lone Star Chapter of the Sierra Club. 

18. August 13, 2008 letter from April 

Johnson, citizen. 

19. August 13, 2008 letter from Wendi 

Hammond, for KIDS 4 Clean Air and Clean 

Air Institute of Texas. 

20. August 13, 2008 letter from Willem and 

Paula Noteboom, citizens. 

21. August 13, 2008 letter from Susan 

Waskey, citizen. 

22. August 13, 2008 letter from Matthew 

Kuryla, Baker and Botts for the BCCA Appeal 

Group. 

23. August 13, 2008 letter from Matthew 

Kuryla, Baker and Botts for the 8-Hour Ozone 

SIP Coalition. 

24. August 13, 2008 letter from Lon 

Burnham, State Representative, District 90, 

Fort Worth, Texas. 

25. August 14, 2008 letter from Anna 

Albers, citizen. 

26. August 14, 2008 letter from Sandra 

Soria, citizen. 

B. General Comments 

Comment: Several commenters urge 

EPA to finalize conditional approval of 

the attainment demonstration SIP. One 

supports EPA’s proposed rule, 

recognizes the efforts of the local 

community, and lists some of the clean 

air initiatives implemented by the City 

of Dallas. 

Response: We appreciate the support 

expressed in these comment letters. We 

applaud the actions taken by the local 

community and commend the local 

leaders and implementation staff; their 

work has and will continue to assist the 

area in reducing NOX and VOCs, the 

precursors for ambient ozone pollution. 

EPA encourages local governments to 

continue to be involved in these and 

future local emissions reductions 

programs. 

Comment: Two commenters disagree 

with EPA’s position taken in the 

proposal that because the DFW area has 

an attainment deadline of June 15, 2010, 

air quality monitoring data for the years 

2007, 2008, and 2009 would be used to 

make an attainment determination. 

Rather, using the years 2008, 2009, and 

2010 would be most consistent with the 

Act’s requirements for attainment 

determination. They note that the Act 

mandates the attainment determination 

be made within 6 months after the 

attainment date, including any 

extensions thereof, and be based on the 

area’s design value as of the attainment 

date. Although the Phase 1 Rule defines 

the ‘‘attainment year ozone season’’ as 

the ozone season immediately preceding 

the attainment date, they contend that 

that regulatory definition can be read as 

requiring controls timely for attainment 

in the attainment year, as required by 

the statute. They do not see the 

definition as relevant to the timing or 

content of an attainment determination. 

EPA’s regulations do not specify that the 

attainment determination is to be 

conducted using data from the years 

prior to the attainment date, without 

considering data from the ozone season 

that includes the attainment date. They 

believe such a determination would be 

inconsistent with the statutory directive 

that the attainment determination be 

‘‘based on the area’s design value (as of 

the attainment date).’’ 

Response: As an initial matter, EPA 

set forth its interpretation on this issue 

in the preambles to the proposed and 

final Phase 1 Rule. See 68 FR 32802, at 

32817 (June 2, 2003) (In ‘‘determining 

whether an area actually attains the 

NAAQS at the time of the attainment 

date, EPA would use the ambient air 

quality data for the three ozone seasons 

prior to the attainment date. As an 

example, if the effective date of the 


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nonattainment designations is May 15, 

2004, the maximum attainment date for 

an area classified marginal would be 

May 15, 2007. In this example, EPA 

would consider the 8-hour ozone data 

for the three previous ozone seasons— 

2004, 2005 and 2006.’’); 69 FR 23951, at 

23989 (Apr. 30, 2004) (noting that the 

ozone seasons from 2007, 2008 and 

2009 would be considered for an 

attainment date in May 2010). However, 

as noted by the commenter, the statute 

clearly specifies that a determination of 

attainment must be ‘‘based on the area’s 

design value (as of the attainment date). 

The attainment date for the DFW area is 

June 15, 2010 and the design value ‘‘as 

of the attainment date’’ must be 

determined using the last three full 

years of ozone data, i.e., 2007, 2008 and 

2009. We see no argument that the 

design value ‘‘as of the attainment date’’ 

could be determined based on air 

quality data that would not represent a 

complete ozone season and thus be 

incomplete as of June 15, 2010. 

Comment: We received many 

comment letters stating that the plan 

does not reflect recommendations made 

by the North Texas Clean Air Steering 

Committee. 

Response: We agree that the plan 

submitted by the State does not reflect 

all of these recommendations. The 

resolutions were submitted to the State 

and addressed by the TCEQ in the SIP 

package adopted on May 23, 2007, 

which is in the docket for this 

rulemaking. The U.S. Supreme Court 

has consistently held that under the Act, 

initial and primary responsibility for 

deciding what emissions reductions will 

be required from which sources is left 

to the discretion of the States. Whitman 

v. Am. Trucking Ass’ns, 531 U.S. 457 

(2001); Train v. NRDC, 421 U.S. 60 

(1975). The State has discretion under 

the Act to determine the emissions 

reductions measures to be included in 

its attainment demonstration and 

exercised this authority for this plan. 

The State’s role is to determine which 

particular emissions reductions 

measures are appropriate for the 

nonattainment area in order to comply 

with the requirements of the Act. As a 

matter of law, EPA is required to 

approve a SIP revision if it meets the 

Act’s requirements, regardless of the 

State’s choices. It is not EPA’s role to 

rule out the State’s choice of 

components of its SIP submittal so long 

as the plan is adequate to meet the 

standards mandated by EPA. See Train 

at 79–80 and Union Electric v. EPA, 427 

U.S. 246 (1976). The EPA’s role in 

reviewing SIP submittals is to approve 

state choices, if they meet the criteria of 

the Act. EPA disapproves a SIP 

submittal only if it fails to meet the 

statutory requirements. Seabrook v. 

Costle, 659 F.2d 1349 (5th Cir. 1981). 

Federal inquiry into the reasonableness 

of state action is not allowed under the 

Act (see, Union Electric Co. v. EPA, 427 

U.S. 246, 255–266 (1976); 42 U.S.C. 

7410(a)(2)). As provided in the analyses 

accompanying this rulemaking, we have 

explained why we believe the submitted 

plan meets the requirements of the 

CAA. 

Comment: Many commenters claimed 

that the SIP sanctions ozone pollution 

levels above the 1997 standard yet this 

standard has been determined not to be 

protective of human health by the EPA 

and is being replaced. 

Response: The Act contemplates the 

possibility that scientific advances 

would require amending the ozone 

NAAQS. As such, Section 109(d)(1) of 

the Act requires EPA to review the 

ozone standard every five years based 

on the current science, and make any 

revisions that are appropriate in light of 

the current science. Today’s actions are 

being taken in the context of the ozone 

standard that was promulgated on July 

18, 1997, based on the best available 

scientific evidence at the time. 

The 2008 revised 8-hour ozone 

standard does not replace the 

requirements for ozone nonattainment 

areas to meet the 1997 8-hour ozone 

standard by their applicable attainment 

date. The measures implemented in this 

attainment demonstration SIP will assist 

the DFW area in progressing toward the 

2008 revised 8-hour ozone standard, 

ensuring progress continues during the 

time between the designations for the 

2008 standard and the submission date 

for the associated SIP revisions. These 

measures cannot be removed from the 

SIP. South Coast Air Quality 

Management Dist. v. EPA, 472 F.3d 882 

(DC Cir. 2006). 

Comment: A commenter stated that 

TCEQ approved a permit revision 

allowing TXI cement kilns in Ellis 

County to burn tires as fuel, questioned 

whether the change would result in a 

decrease in NOX emissions, and 

expressed concerns about other 

pollutants, which result from tire 

burning. TXI said there would be NOX

reductions but they based this by 

comparing kilns that were not similar to 

the ones TXI would use. TCEQ allows 

TXI to self-report, but the checks on the 

reporting are poor, and TXI also knows 

when the inspectors are coming. 

Response: Each cement plant in Ellis 

County must comply with both its 

permits’ limits and the State’s revised 

chapter 117 rules for cement kilns relied 

upon in the DFW attainment 

demonstration, whichever is stricter. In 

a related rulemaking in today’s Federal 

Register, EPA is concurrently approving 

the revised chapter 117 rules for cement 

kilns. The revised cement kiln rules 

establish a NOX source cap for each of 

the three cement plants in Ellis County. 

We disagree that there will be no 

decreases in NOX emissions. The 

revised NOX rules for cement kilns 

should result in at least 9.7 tpd of 

reduction in NOX emissions for the 

DFW area regardless of the fuel used 

including tires. We note also that all of 

the cement plants are required to 

operate continuous emissions monitors 

for NOX that must meet rigorous quality 

assurance and quality control criteria. 

Because these stack monitors must 

operate continuously, compliance does 

not rely solely on periodic inspections. 

As a consequence, EPA is confident that 

compliance with the NOX limits in these 

rules will be well monitored. 

The commenter’s concerns regarding 

increases of other pollutants besides 

NOX, TXI’s reliance upon non-similar 

kilns to claim NOX reductions, selfreporting, and TCEQ’s inspection 

program are not pertinent to today’s 

action; the issue in this action is 

whether the State has shown that the 

DFW area will attain the 1997 standard 

by June 15, 2010. 

Comment: The public is 

disadvantaged by ‘‘conditional 

approval’’ comment periods. Comments 

concerning the adequacy of Texas’ plan 

depend upon how Texas fulfills the 

requisite conditions, but the public will 

not know this information until 

sometime in the future after the current 

comment period has passed. After Texas 

adopts and submits its final plans 

concerning DERCs and the other 

‘‘conditions’’ to EPA, EPA should allow 

additional public comment regarding 

the adequacy of the DFW SIP attainment 

demonstration. 

Response: Congress provided for 

conditional approval as a type of SIP 

processing. The Congress added section 

110(k)(4) to the Act in the 1990 

amendments to codify the EPA’s 

authority to conditionally approve SIPs. 

Section 110(k)(4) provides that EPA may 

conditionally approve a plan based on 

a commitment from the State to adopt 

specific enforceable measures by a date 

certain, but not later than one year after 

the date of the final conditional 

approval action. In this case, if the State 

submits by March 1, 2009 (the date 

certain), a complete DERC SIP revision 

submittal (the specific enforceable 

measures), EPA must reevaluate the 

approvability of the DFW attainment 

demonstration SIP, as revised by this 

DERC SIP revision submittal. EPA will 

perform such an evaluation through 


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1See the Settlement Agreement and letters dated 

March 22, 2006, March 24, 2006 and April 6, 2006 

in the docket for this rulemaking. 

notice-and-comment rulemaking and 

the public will have another 

opportunity to comment upon the 

adequacy of the DFW plan as affected by 

the DERC changes. 

Comment: A number of commenters 

are concerned that cities within the 

DFW nonattainment area continue to be 

given more time to attain the standard 

instead of requiring them to clean the 

air now. If the State had met its 

responsibilities to submit a timely and 

approvable 1-hour attainment 

demonstration SIP, then this SIP would 

be incrementally stronger and have been 

submitted and implemented sooner. 

There is a contention that Texas has not 

submitted a complete approvable 

attainment demonstration SIP for the 

DFW area for over thirty years. 

Moreover, monitoring began in the early 

1970’s and the DFW area has never 

attained the 84 parts per billion (ppb) 

standard and remains years from doing 

so. 

Response: The lack of approvability of 

past SIP submittals for the DFW area is 

not relevant to the requirement for an 

area to submit a 1997 8-hour ozone 

attainment demonstration. The State 

submitted this SIP revision on May 30, 

2007, fifteen days before the June 15, 

2007 required submission date. The 

State was on schedule to submit this SIP 

revision even earlier, but received 

requests from several stakeholders for 

an expanded timeline that would allow 

for a more robust stakeholder discussion 

and development of additional technical 

support.1

This 8-hour ozone attainment 

demonstration was submitted on time 

and deemed complete by operation of 

law (40 CFR part 51, Appendix V). 

Moreover, the attainment date for the 

1997 8-hour ozone standard for the 

DFW area is June 15, 2010. The State 

has not requested additional time for the 

area to attain this standard, nor has 

additional time been granted. EPA is 

finding today that the control measures 

relied upon in this plan, in combination 

with Federal Measures, and building on 

measures already approved in the SIP 

will ensure that the DFW area attains 

the 1997 8-hour ozone standard by the 

applicable attainment date of June 15, 

2010. 

While past efforts to comply with 

CAA requirements have not been 

without flaws, we note that there have 

been extensive efforts and significant 

progress made over the years in the fast 

growing DFW area. These past efforts 

have built the foundation for the plan 

being approved today. They include the 

15% Rate of Progress (ROP) plan, the 

post-1996 ROP plan, the MVEBs, and 

the extensive control measures adopted 

by the State and approved by EPA into 

the Texas SIP for the DFW area to meet 

the 1-hour ozone standard. The control 

measures in these approved plans 

included among other things: 

Reformulated gasoline, enhanced I/M, 

and controls on power plants locally 

and in the Central and East Texas 

Region. 

Moreover, we note that the area is 

continuing to look for further ways to 

address ozone levels and may submit 

additional revisions to the SIP in the 

future. Three of the largest cities 

(Arlington, Dallas and Fort Worth) have 

passed ordinances addressing the 

purchase of green cement, which may 

yield an additional 1 tpd of NOX

reductions; and local city and county 

officials have increased their 

enforcement of Inspection and 

Maintenance rules by performing site 

inspections, which will yield additional 

reductions through 2009. 

The measures discussed above have 

resulted in significant improvements in 

air quality. The DFW area now is 

meeting the 1-hour standard and has 

made significant progress toward 

meeting the 1997 8-hour ozone 

standard. As a moderate nonattainment 

area, the attainment date for the DFW 

area is June 15, 2010 and we believe the 

area will meet the attainment date. 

Comment: The plan should require 

more mass transit and industry to install 

the latest in air pollution reduction 

equipment. Airplane engines and 

related equipment should be less 

polluting. 

Response: As explained in an earlier 

response, the CAA places responsibility 

on the State to determine the mix of 

controls that will bring an area into 

attainment with a particular standard 

and EPA is delegated to reviewing 

whether the State’s plan will meet the 

statutory attainment requirement. 

Therefore, EPA does not have the 

authority to require the State of Texas to 

submit a plan for the DFW area that 

requires more mass transit or imposes 

the latest in pollution control 

equipment on industry. 

We note, however, the expansion of 

mass transit is ongoing in the DFW area 

and can be viewed at http:// 

www.DART.org. Appendix H of the 

DFW SIP submittal identifies emission 

reduction measures for airplanes and 

related equipment, which are part of the 

Voluntary Mobile Source Emission 

Reduction Program (VMEP) we are 

approving today. These include: 

Additional electrification of ground 

support equipment; gate electrification 

to eliminate use of aircraft auxiliary 

power units; ground tugs for pushback 

to minimize use of reverse thrust from 

main aircraft engines; de-peaking of 

airline flight schedules; and 

implementation of airport surface 

detection equipment to improve 

efficiency during taxi. Furthermore, the 

local community has implemented 

clean air initiatives that include: 

Outreach for the TERP and 

AirCheckTexas programs; reducing 

environmental impacts by purchasing 

hybrids and alternative fueled vehicles 

when possible; purchasing 40% of their 

electric power from renewable 

resources; green building policies; 

development of sustainability policies; 

developing purchasing policies for 

cleaner cement; and passing an 

ordinance prohibiting vehicles over 

14,000 pounds from idling for more 

than 5 minutes. 

In addition to the measures in 

Appendix H, TCEQ submitted a 

Supplement with more accurate and 

updated data for Love Field and the 

DFW International Airport, including 

data on activities and fleet mix. There 

were more new aircraft engines and the 

related equipment was less polluting 

than previously recognized. This 

information is provided in the docket 

for this rulemaking. 

C. Comments on the Texas Emissions 

Reduction Plan (TERP) 

Comment: Commenters express 

significant concerns about whether the 

projected emissions reductions from 

TERP will occur, as predicted. They 

believe that the projections are overly 

optimistic. They provide the following 

reasons for their concern about the 

projections being too optimistic: 1. 

Actual TERP reductions have not met 

previous projected reductions, and the 

methodology for calculating the 

projected TERP reductions may not take 

into account that in the future, there 

will be fewer emissions reductions per 

dollar spent (cost-effectiveness 

assumption). 2. Although it is clear that 

TERP emissions reductions occur, there 

does not seem to be a satisfactory way 

to confirm the projected reductions will 

actually occur or not. 3. EPA relies upon 

the State’s assumption that 70% of 

TERP funds will be used in the DFW 

area, but since there is no mechanism 

for ensuring the specified percentage of 

funding will be met, the projections are 

not enforceable; the projections should 

not be relied upon in the attainment 

demonstration; the 70% assumption 

should be reduced; and the SIP should 

include a contingency component to 

address a potential shortfall. 


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Federal Register / Vol. 74, No. 9 / Wednesday, January 14, 2009 / Rules and Regulations 1909 

2The Carl Moyer Program 2006 Status Report is 

in the docket for this rulemaking and can be viewed 

at http://www.arb.ca.gov/msprog/moyer/status/ 

2006status_report.pdf. 

3The TCEQ fiscal year runs from September 1 

through August 31. 

4Using the revised SIP credit methodology, each 

ton costs (6000 × 250 × 7) = $10,500,000. Therefore, 

14.2 × 10,500,000 = $149,100,000. 

5Using the revised SIP credit methodology: 3.75 

tpd × $10,500,000 = $39,375,000 to correct the IOP 

SIP shortfall. 

6Per the TERP Biennial Report to the Texas 

Legislature December 2008 draft, dated September 

22, 2008. This draft was prepared using data from 

mid-summer. The final report, due in December 

2008, will incorporate all of the contracts awarded 

or pending to date. See the docket for this 

rulemaking. 

Response: We agree that for the 

Increment of Progress SIP revision, the 

amount of actual TERP reductions was 

less than the projections. Because of this 

experience, we worked with the State to 

revise the methodology for estimating 

emission reductions in this attainment 

demonstration SIP. The revised 

methodology uses assumptions that are 

more conservative. Specifically, the 

average project life was increased by 

40% and the cost effectiveness was 

reduced by slightly more than 51%. The 

formula now relies upon the following 

assumptions: $6000/ton, 250 days/yr 

operation and a 7-year project life. 

Using these revised assumptions, the 

TERP emission reduction projections 

relied upon in the demonstration 

modeling and the WOE are greatly 

reduced. Increasing the project life has 

the effect of reducing the emission 

reductions assumed in any given year. 

The cut in the revised cost-effectiveness 

assumption is intended to address, 

among other things, the commenters’ 

concerns about there being fewer 

reductions per dollar spent each 

succeeding year. 

For comparison, on January 26, 2007, 

the cost effectiveness of TERP projects 

completed in DFW averaged $3730.24/ 

ton; by September 23, 2007, DFW 

projects averaged $3743.59/ton; and by 

April 2, 2008, DFW projects averaged 

$3959/ton. California’s experience with 

the Carl Moyer program 2 has achieved 

emissions reductions at an average cost 

of $3900/ton through October 2006. We 

believe the revised cost effectiveness of 

$6000/ton provides room for the 

increase in cost/ton that we are seeing 

in the DFW area. 

In its May 2007 SIP revision, TCEQ 

indicated as a weight of evidence (WOE) 

measure that additional TERP 

reductions were possible if additional 

monies were appropriated by the 

legislature for the 2008/2009 legislature. 

House Bill 1 signed by the Governor on 

July 15, 2007, appropriated to TCEQ, 

TERP funds of $297,144,243 for fiscal 

years (FYs) 2008/2009. In the April 23, 

2008 submittal, relying upon these 

additional appropriated monies, TCEQ 

projected that the TERP could 

potentially achieve an additional 14.2 

tpd of NOX emissions reductions. Since 

these emissions reductions were not 

available early enough to include as 

control measures in the modeling, their 

impact on the DFW area’s air quality 

was instead predicted by EPA, using 

sensitivity modeling runs, to estimate 

the ppb change on the monitors in the 

modeling-based weight of evidence 

(WOE) analysis. 

To achieve the projected additional 

14.2 tpd of NOX emissions reductions 

from TERP, using the revised TERP 

methodology, the Texas legislature 

needed to appropriate to the TCEQ, 

sufficient FY2008 and FY2009 3 TERP 

funds for the TCEQ to allocate a total of 

$149,100,000 4 to the DFW area for 

TERP Emission Reduction Incentive 

Grant (ERIG) projects; this amount does 

not include the funds required to 

achieve the IOP shortfall.5 TCEQ 

received a sufficient amount of TERP 

monies to have available $188,475,000 

to achieve the IOP SIP shortfall 

($39,375,000) and achieve an additional 

14.2 tpd ($149,100,000) in 2008 and 

2009. 

In the April 2008 submittal, the TCEQ 

posited that it could achieve the 

additional 14.2 tpd of TERP NOX

reductions by spending in the DFW area 

50% of the FY2008 TERP funds and 

70% of the FY2009 TERP funds. 

Whether funds are spent in exactly 

these percentages each year however, is 

not the issue; the essential point is that 

TCEQ enters into TERP grant contracts 

worth at least $149,100,000 in the DFW 

area for projects to achieve 14.2 tpd in 

calendar years 2008 and early 2009. 

TCEQ roughly split in half for each 

fiscal year, the $297,144,243 

appropriated TERP funds— 

$148,572,121.50. Of this 

$148,572,121.50 ‘‘split,’’ TCEQ used 

approximately $40 million for other 

TERP programs, including rebate grants 

and FY2007 unfunded TERP 

applications, including the IOP SIP 

shortfall. EPA notes that the IOP 

shortfall has now been met. Considering 

the factors meant that TCEQ had 

approximately $106,000,000 FY2008 

TERP monies for the FY2008 to achieve 

additional reductions beyond those 

considered in the May 2007 SIP 

submission through ERIG projects in 

TERP-eligible counties. Applications 

submitted to TCEQ during the FY2008 

round of project applications totaled 

approximately $94.5 million for the 

DFW area. Of these applications 

however, it appears from the draft 

September Report that $51,532,511.79 

have been selected for funding.6

As a result, to achieve the 14.2 tpd 

projection, TCEQ needs to enter into 

FY2009 TERP grant contracts worth 

$97,567,488.21 ($149,100,000 ¥ 

51,532,511.79 = $97,567,488.21). In 

summary, after accounting for the tpd of 

TERP NOX emissions reductions 

obtained by the FY2008 grant contracts, 

to obtain the remaining tpd of TERP 

NOX emissions reductions to achieve a 

total of 14.2 tpd as projected as part of 

the WOE, the TCEQ would need to enter 

into TERP grant contracts with DFWarea applicants worth $149,100,000 for 

projects to be completed as early as 

possible in calendar 2009. Due to a 

number of factors, including Hurricane 

Ike, the TCEQ will begin its first round 

of requests for funding from FY2009 

TERP grant monies in December 2008. 

For more information concerning the 

timing of FY2009 TERP projects due to 

Hurricane Ike, please see the 

Supplemental TSD dated December 

2008. 

TERP has safeguards to ensure that 

when funds are provided to grantees, 

they must achieve the associated 

reductions. Grantees are required to 

track usage and report to the TCEQ 

every six months; they must meet the 

reporting requirements delineated in 

their specific grant contract. TERP is 

enforceable against the grant recipient. 

Over the activity life of each TERP 

grant-funded activity, the grant recipient 

commits the generated emissions 

reductions to the SIP. The recipient is 

responsible for achieving the annual 

and total NOX emissions reductions 

within the eligible areas as defined in 

the contract. Recipients will be required 

to return all or a pro rata share of the 

grant funds to the TCEQ if the emissions 

reductions are not achieved. 

EPA continues to carefully review the 

biennial reports that TCEQ is required 

to submit to the Legislature pursuant to 

Texas Health and Safety Code, 386.057 

and 386.116(d). The draft September 

TERP Biennial Report to the Texas 

Legislature indicates that 488 projects 

have been selected for funding in the 

DFW area, totaling $51,532,511.79 to 

reduce an estimated 3.72 tpd in NOX

emissions beyond what was included in 

the May 2007 modeling. Based upon the 

draft September Report, the average 

cost/ton for these projects increased to 

$6710.13, versus the revised 

methodology of $6000/ton. At this rate, 

to achieve the 14.2 tpd in NOX

emissions reductions, the TCEQ must be 


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7 (6710.13 × 250 × 7) = $11,742,727.50 × 10.4786 

= $123,047,344.38. 

able to allocate at least $123 million 7 to 

the DFW area for TERP projects early in 

calendar 2009. As this report is in draft, 

these numbers are subject to change but 

it now seems likely that approximately 

70% of these TERP emission reductions 

will occur before the core ozone season 

of 2009. We have evaluated the impact 

of this change on the attainment 

demonstration modeling and WOE; this 

evaluation is in Subsection D, below. 

In summary, EPA believes that the 

TERP program is achieving significant 

reductions in NOX. Consistent with its 

experience in implementing the 

program, the State has adjusted its 

assumptions used in projecting 

emission reductions to be more 

conservative. EPA believes these revised 

assumptions begin to address many of 

the commenters concerns. Although 

delays in opening the request for 

applications mean the reductions based 

on FY2009 funds will be delayed, many 

reductions can still occur before the 

peak of the ozone season. Achieving the 

14.2 tpd of reductions from TERP will 

require substantial continued efforts. 

See also Subsection D below, in 

particular the last Response, Comment 

MC–15. 

D. Comments on Photochemical 

Modeling, Weight of Evidence Analyses, 

and Assessment of Demonstration of 

Attainment 

EPA received a number of comments 

about the photochemical modeling, the 

Weight of Evidence Analyses, and our 

proposed determination that the area 

would attain the standard by its 

attainment date of June 15, 2010. EPA 

has reviewed all the comments on these 

topics and provided responses below. 

The discussion below summarizes our 

evaluation of the modeling and 

evidence, the comments we received, 

and other factors such as the State’s 

progress in implementing control 

strategies, and recent air quality trends. 

EPA believes that as the attainment date 

becomes closer, measured air quality 

and planned additional emission 

reductions become more important as a 

predictive tool (compared to modeling) 

and the monitoring data should be given 

additional weight, more so than in 

situations where the attainment date is 

still years away. In 2008, the 

preliminary data shows 18 of the 20 

monitors have measured attainment 

levels with fourth high 8-hour values of 

84 ppb or less. The remaining two 

monitors were only slightly higher than 

an attainment level measuring fourth 

high values of 85 ppb. EPA believes 

additional significant reductions in 

emissions will occur before the 2009 

ozone season such that the area can 

attain the standard based on 2007–2009 

ambient data or at least qualify for a 1- 

year extension of the attainment date by 

having each monitor’s 4th high ozone 

concentration in 2009 below 85 ppb. 

We evaluated many factors in our 

WOE evaluation. These items included 

reductions not included in the modeling 

based projections (energy efficiencies), 

unquantifiable measures 

(AirCheckTexas, Dallas Sustainable 

Skyline Initiative, etc.), meteorological 

analyses of severity of ozone seasons 

(both the base period and recent years 

including 2007), most recent monitoring 

in 2007 (a 4th high of 89 ppb at two 

monitors and the other 18 monitors had 

4th high values of 87 ppb or less), the 

court’s vacatur of CAIR, progress in 

implementing the TERP program, and 

progress in implementing the early 

compliance incentive on natural gas 

compressor engines outside the DFW 

area. EPA has also considered 

preliminary 2008 ozone monitoring data 

(4th high values of 85 ppb at two 

monitors and at the other 18 monitors 

the value was 84 ppb or less) and 

whether that data supports a trend 

toward attainment for the area. We 

considered that over half of the NOX

estimated emissions reductions between 

2007 and 2009 that are estimated to 

yield a 3–4 ppb drop in ozone levels in 

the DFW area, are slated to occur 

between the 2008 ozone season and the 

2009 ozone season. We also expect 

further ozone reductions in 2009 and 

beyond. 

After consideration of all of these 

analyses, EPA has determined that the 

State has demonstrated that the DFW 

nonattainment area will attain the 1997 

8-hour ozone standard by its attainment 

date. 

Comment (MC–1): A commenter states 

that the WOE analysis underestimates 

the impact of emission increases from 

facilities outside the DFW 

nonattainment area, upon the DFW area. 

This underestimate occurs because the 

TCEQ issues PSD permits to facilities 

outside the DFW area that will affect the 

ozone concentration level in the DFW 

area and says they should address these 

ozone impacts in the DFW attainment 

demonstration SIP. The commenter does 

not believe that this DFW attainment 

demonstration accounts for the impacts 

from these sources that have been and 

will be permitted outside of the DFW 

area. There also appears to be no 

correlation or tracking of these 

permitted emission increases in relation 

to the projected point source emissions 

inventories in this DFW attainment 

demonstration. 

Response (MC–1): The Texas SIP at 

Section 166.160 (a) (which incorporates 

40 CFR 52.21(k) by reference) requires a 

new source or modification subject to 

PSD to demonstrate that emissions from 

the facility will not cause or contribute 

to a violation of any NAAQS. The Texas 

PSD SIP permitting program also 

provides for an opportunity for notice 

and comment, as well as state court 

judicial review, of each permitting 

action. 

EPA disagrees with the commenter 

that this SIP revision does not account 

for the impact of potential emissions 

increases. In this final action on the 

DFW attainment demonstration, we 

reviewed the analysis to insure that 

sources impacting the DFW 

nonattainment area were included in 

the baseline and future case modeling 

demonstrations. EPA’s modeling 

guidance (‘‘Guidance on the Use of 

Models and Other Analyses for 

Demonstrating Attainment of Air 

Quality Goals for Ozone, PM2.5, and 

Regional Haze’’, EPA–454/B–07–002, 

April 2007; and earlier modeling 

guidance) and emission inventory 

guidance (‘‘Emissions Inventory 

Guidance for Implementation of Ozone 

and Particulate Matter National 

Ambient Air Quality Standards 

(NAAQS) and Regional Haze 

Regulations’’, EPA–454/R–05–001, 

August, 2005, updated November 2005) 

indicate that a combination of specific 

projections and general growth 

estimates should be utilized to attempt 

to obtain a best estimate for the future 

year inventory. Future case emissions 

must be projected to account for growth 

and control throughout the modeling 

domain, which includes states outside 

of Texas and the attainment areas of 

Texas (including the new proposed 

sources raised by the commenter). EPA’s 

guidance has been that new permitted 

sources, including likely to be permitted 

sources based on applications that have 

been received when the future year EI 

is being generated, should be included 

in the future year modeling if they are 

expected to be emitting in the future 

attainment year. As a practical matter, 

the focus has usually been to include 

expected new very large sources (such 

as electric generating units (EGUs)) and 

use economic based growth factors to 

account for growth in emissions from 

other industrial source categories. 

Overall, EPA’s guidance is to provide 

the best estimate of the future year 

emission inventory given the limitations 

with estimating emissions several years 

in the future. Texas’ emission 

projections to the future years are very 


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Federal Register / Vol. 74, No. 9 / Wednesday, January 14, 2009 / Rules and Regulations 1911 

8For example, if the 4th high value for each of 

three years was as follows: 2006—87 ppb; 2007— 

85 ppb; 2008—81 ppb, the average over the three 

year period would be 84 ppb, which is below the 

level of the standard. 

9 2008 preliminary monitoring data is from EPA’s 

AQS and AirNow databases and has to undergo 

final Quality Assurance and Quality Control. 

detailed and the methods utilized are 

discussed in the MOAAD TSD and in 

TCEQ’s DFW SIP submittal, including 

Appendix B. In nonattainment areas, 

major new sources are required to 

obtain offsets larger than the proposed 

source so there is a net decrease in 

emissions, so no growth is estimated for 

these sources in nonattainment areas. 

Therefore, within Texas the only areas 

that point source growth is estimated is 

in the areas that are in attainment and 

our discussion will briefly explain the 

methodology for future year estimates of 

major point sources in attainment areas 

of Texas. 

For existing EGUs in Texas, the State 

used 2005 continuous emission 

monitoring data and assumed that there 

would be no emissions changes. Texas 

projected increases in emissions 

because of new EGUs that were 

expected to be emitting in 2009 (these 

were included in Table 2–8 of Appendix 

B of TCEQ’s submittal). For all other 

industrial point source emissions (nonEGUs) in Texas’ attainment areas, TCEQ 

started with the 1999 reported emission 

inventory and projected growth in point 

source emissions using point source 

growth projections derived from the 

Emissions Growth Analysis System 

version 4.0 (EGAS 4.0), an EPAapproved methodology. It is worth 

noting that the EGAS system for 

projecting emissions tends to overstate 

future emissions since the system relies 

principally on economic growth for the 

projections, and does not include 

reductions from regulatory or permit 

controls. 

In conclusion, we have reviewed the 

methodologies that TCEQ utilized to 

grow EGUs and non-EGUs outside of the 

DFW area and conclude that the 2009 

level emissions of these sources have 

been appropriately estimated using 

acceptable methods and contrary to the 

commenter’s concerns the attainment 

demonstration appropriately accounts 

for the potential for new source growth 

by 2009. 

Comment (MC–2): Commenters state 

that ozone exceedances continue to 

occur in the DFW area and show there 

still is a serious problem. Specifically, 

14 exceedances have been measured at 

eight of the monitors through August 12, 

2008 and eight of which are 90 to 99 

ppb. The commenter concluded that 

this 2008 monitoring data does not seem 

to support the WOE. 

Response (MC–2): EPA has reviewed 

the ozone monitoring data through 

November 1, 2008 in response to this 

comment. While a number of 

exceedances of the 1997 8-hour ozone 

standard occurred during the 2008 

ozone season by August 12, 2008, it is 

very important to note that the standard 

is a statistically based standard. The 

statistical nature of the standard allows 

each monitor to have up to 3 days with 

exceedance levels at each monitor (with 

potentially multiple 8-hour exceedances 

for each of the three days) and all the 

monitors in the area could still have a 

4th high value less than 85 ppb 

(attainment level). The standard is an 

average of the daily 4th high value at a 

monitor for each year of a consecutive 

3-year period. Therefore, it is even 

possible to have a 4th high value for one 

or even two years at a specific monitor 

be above the standard, but the 3-year 

average value to be below 85 ppb and 

thus, in attainment.8 Furthermore, each 

monitor in the area could have up to 3 

exceedances at each monitor on 

differing days. Given 20 monitors in the 

DFW area, a total of 60 exceedances 

could theoretically occur in the DFW 

area with all 4th high values at each 

monitor still less than 85 ppb. This is a 

theoretical worse-case situation but this 

demonstrates that having several 

exceedances does not automatically 

yield a nonattainment determination. 

Since the standard is statistically 

based, the relevant metric to examine 

for determining compliance with the 

NAAQS is the annual 4th high values at 

each monitor. We therefore evaluated 

the recent 4th high values for the DFW 

area 8–Hour Ozone Season (March 1– 

October 31 for the 85 ppb standard). The 

4th high monitoring data from 2008 

indicates that the area is near attainment 

levels (2008 monitoring data is 

preliminary and awaiting QA/QC9). The 

2008 preliminary data shows the DFW 

area had 4th high values of 85 ppb at 

two monitors and at the other 18 

monitors the value was 84 ppb or less. 

The 2008 preliminary data indicates the 

2006–2008 DV is 91 ppb (down from 95 

ppb using 2005–2007 data). For the 

monitor that has the highest average 

2007 and 2008 4th high values and is 

likely to be the controlling monitor (or 

one of the highest monitors) for 

determining if the area reaches 

attainment based on 2007–2009 data, 

the monitor’s DV for the 2007–2009 

period would have to be less than 85 

ppb. For this to occur the monitor 

(Denton monitor) would have to have a 

4th high value of 82 ppb or less to reach 

attainment in 2009. It is important to 

note that this monitor had a preliminary 

4th high value in 2008 of only 84 ppb. 

In comparison with ozone monitoring 

levels in 2007, the preliminary 2008 

monitoring data is lower than the 2007 

data. Contrary to the commenters 

concerns, EPA believes that the 2008 

preliminary data is consistent with 

achieving attainment, especially 

considering that much of the DFW SIP 

reductions are still to occur and another 

year of fleet turnover will happen. EPA 

also believes that even if the area does 

not attain the standard based on 2007– 

2009 data, it is very likely to qualify for 

a one year extension under sections 

172(a)(2)(C) and 181(a)(5) of the Act (see 

40 CFR 51.907) by having fourth high at 

84 ppb or below at every monitor. 

Comment (MC–3): Commenters 

believe that we should impose a 2009 

mid-course review (MCR) obligation 

upon the State, triggered by exceedances 

at the monitors or a violation of the 

standard in 2009. 

Response (MC–3): There is no MCR 

requirement at this time for the 8-hour 

ozone SIP. In our Phase 2 

Implementation Rule, we provided that 

we would assess the need for MCR for 

areas with an attainment date beyond 6 

years after the effective date of the area’s 

designation (Final Rule To Implement 

the 8–Hour Ozone National Ambient Air 

Quality Standard, Phase 2 (70 FR 71612, 

71629). The attainment date for DFW is 

June 15, 2010, which is not more than 

6 years beyond the effective date of the 

area’s designation. A mid-course review 

is for the purpose of assessing whether 

an area is on-track for attainment and 

would typically be performed several 

years before the attainment year. This is 

because a MCR performed several years 

before the attainment year would give 

the area sufficient time to make 

corrections to the plan if it was not 

performing as anticipated. A review as 

suggested by the commenter would not 

be ‘‘mid-course’’ because it would be 

performed in the middle of the 

attainment year ozone season. At that 

point in time, there would be no steps 

that the DFW area could take to move 

the area back on track to achieve 

attainment by the required date. 

Comment (MC–4): Commenters stated 

that in the DFW area, there are two 

monitors critical to the attainment 

demonstration, one in Frisco and one in 

Denton. The commenters, relying upon 

a February 22, 2006 Memorandum from 

ENVIRON, state that there is no 

measurable impact on these two critical 

monitors from the TCEQ’s chosen 

controls for the Ellis County cement 

plants. The commenters contend that 

TCEQ has not performed any analysis 

showing that the chosen level of 


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10The RRF is used to calculate the change in 

model projected values between the basecase and 

future case modeling projections and determine if 

modeling is projecting attainment in the future. For 

further explanations of both the EPA guidance 

method for calculating RRFs and TCEQ’s RRF 

calculation method see Section 4.11 of the MOAAD 

TSD. 

controls on the Ellis County cement 

plants would assist the DFW area into 

coming into compliance with the ozone 

standard. 

Response (MC–4): As noted in a 

previous response, the Act gives the 

State the primary authority to determine 

the mix of control measures necessary to 

demonstrate attainment. One of the 

measures that TCEQ selected in support 

of its attainment demonstration is 

controls at cement plants in Ellis 

County. EPA evaluated the plan, as a 

whole, and agrees that the State has 

demonstrated that the area will attain 

the standard by its attainment date. 

Thus, EPA does not have authority to 

second-guess the mix of controls 

selected by the State and, in this case, 

its decision to further control the 

cement kilns in Ellis County. 

Although we cannot second-guess the 

controls selected by the State, we note 

that we agree with TCEQ that cement 

kiln NOX reductions are an important 

element of the reductions necessary to 

bring the entire DFW area into 

attainment and the reductions are 

expected to reduce high ozone levels 

and the frequency of ozone exceedances 

in the DFW area. The record for this 

action includes the information that was 

evaluated by the State and EPA and that 

supports the conclusion that additional 

NOX controls on cement kilns are a 

critical component to reducing ozone 

exceedance levels in the DFW area so 

that the area can timely attain the 1997 

8-hour ozone standard. It is clear from 

evaluating the SIP, its reports and 

appendices that TCEQ has performed 

numerous analyses concerning the 

impact of the cement kilns NOX and 

VOC emissions on the ozone 

concentrations levels of the DFW area. 

Moreover, contrary to the commenters’ 

assertion, the chosen strategy has an 

impact on the Frisco and Denton 

monitors, as well as a significant benefit 

to the western portion of the 

nonattainment area, especially in 

Tarrant County. For further details, see 

the TCEQ’s Response to Comments 

document, the MOAAD TSD, and the 

Supplemental TSD. 

For the other comments specific to the 

cement kiln NOX rule itself, not the 

attainment demonstration SIP, we 

provide the comments and our 

responses in our final rule for the 

Control of Emissions of Nitrogen Oxides 

from Cement Kilns, concurrently 

published in today’s Federal Register. 

Comment (MC–5): The commenter 

asserted that EPA should not accept 

TCEQ’s revised Relative Response 

Factor (RRF) calculation.10 The 

commenter indicated that contrary to 

the proposal, a 1 ppb difference between 

EPA’s RRF guidance and TCEQ’s 

revised RRF is significant. The 

commenter referred to 73 FR 40211, 

stating that TCEQ RRF calculation did 

not make significant differences in the 

future design values (FDVs) with 

truncation. The commenter wrote that 

TCEQ’s methodology is merely a paper 

exercise to obtain additional emission 

credits, and EPA should not approve of 

such tactics. 

Response (MC–5): We recognize the 

TCEQ’s method of projecting the future 

design value differs from the method 

provided for in EPA’s guidance. EPA’s 

guidance for projecting the future design 

value is not a legally binding 

substantive rule. Therefore, other 

methods of design value projections 

may be evaluated on a case-by-case 

basis and used to determine whether an 

area will meet the standard. Whatever 

method is used for a specific 

demonstration—either that from EPA’s 

Guidance or another method—is subject 

to comment during the State and EPA 

public participation processes and all 

substantive concerns about the method 

would be addressed in responding to 

any comments. 

TCEQ shared their RRF method with 

EPA during their SIP development 

process. EPA reviewed the alternate 

RRF method at the time and indicated 

to TCEQ that we would utilize both 

EPA’s method and TCEQ’s method and 

weigh the results in our review of the 

modeling projections. We have 

continued to follow this approach in our 

review of this SIP. For details on how 

both the TCEQ and EPA RRF methods 

are calculated and results from the two 

methods, please see the MOAAD TSD 

starting in Chapter 4. 

In this specific case, TCEQ’s method 

yields projected values that when 

compared to values with EPA’s method 

are more conservative at some monitors 

and less conservative at other monitors. 

EPA does not consider the TCEQ RRF 

method to be superior to EPA’s method, 

just a different way to perform the 

calculation and yield another set of 

projected results to consider in our 

review. We do not believe that either 

method is biased towards a particular 

result. As described below, and 

documented in our MOAAD TSD for 

this action, we have reviewed 

projections using both RRF techniques. 

Both the TCEQ projection and the EPA 

projection are consistent with the 

conclusion that the area will meet the 

standard in 2009. 

The results for both RRF (EPA and 

TCEQ) methods are contained in tables 

of the MOAAD TSD that have FDV 

projections, including Tables in Chapter 

6 (the Summary Chapter). EPA reviewed 

the FDVs for all modeling based 

projections using both RRF techniques 

and for most monitors, the TCEQ RRF 

based FDV calculations make minor 

differences of only one or two tenths of 

a ppb (compared to EPA’s RRF method) 

and generally do not change the final 

modeling projected value. Specifically, 

for the nine monitors that are assessed, 

the difference between the two RRF 

techniques ranges from minus 0.22 ppb 

to +0.19 ppb for 8 of the 9 monitors and 

is +0.59 ppb for the other monitor. See 

Table 5 of the proposal notice. As the 

final step of calculating modeling 

projections, EPA guidance recommends 

truncating the tenths digit and only 

reporting integer ppb values to match 

with the monitored attainment 

demonstration procedures that truncate 

to integer ppb levels. Due to this 

truncation procedure, modeling 

projection changes of a few tenths do 

not generally impact the final FDV 

value. There were a few cases where the 

different RRF methods yielded a 1 ppb 

difference in the final FDV value due to 

this truncation process (for the 

Midlothian monitor’s data, the different 

RRF methods yield modeling values of 

82.83 ppb and 83.05 ppb and truncation 

yields final FDVs of 82 ppb and 83 ppb). 

We continue to believe that the 

difference in the results of these two 

techniques is small overall. As 

discussed in another response below, 

we considered the results of both RRF 

methods (including the few times that 

the truncated FDV differed by 1 ppb) 

and determined that both the TCEQ 

projection and the EPA projection are 

consistent with the conclusion that the 

area will meet the standard in 2009. 

Comment (MC–6): The commenter 

indicated it is unclear whether the 

Photochemical Dispersion Modeling 

Reanalysis 2009 (PDMR 2009) 

evaluation uses TCEQ’s revised RRF or 

EPA’s guidance. The commenter 

indicated that it appears as though it 

uses only TCEQ’s RRF and the public 

should be afforded an opportunity to 

know the PDMR 2009 FDV under EPA’s 

guidance. The commenter asserted that 

considering that even with the more 

lenient TCEQ revised RRF, the modeling 

still projects a worse air quality picture, 

and thus the EPA guidance projection 


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will most likely be even worse. The 

commenter indicated that without this 

information, the public is unable to 

meaningfully review and comment not 

only on the overall demonstration, but 

also on whether using the TCEQ revised 

RRF is even proper. 

Response (MC–6): There were five 

tables that included modeling 

projections in the proposal notice. 

Tables 2, 3, and 5 had projections for 

the PDMR 2009 modeling scenario and 

were marked as TCEQ RRF in the FDV 

columns. The proposal notice included 

calculations of modeling projections 

using both the TCEQ’s RRF method and 

the RRF method from EPA’s guidance 

for the modeling run Combo 10 in Table 

1. In referring to values in Table 1 of the 

proposal notice, EPA stated on page 

40211 ‘‘Since the TCEQ RRF calculation 

method did not make significant 

differences in the FDVs and with the 

truncation to whole numbers, we have 

used the TCEQ RRFs for the final 

assessment with consideration of the 

FDVs using EPA’s RRF method. The 

results of EPA’s RRF method are 

contained in the MOAAD TSD.’’ From 

that point forward in the proposal 

notice, EPA did not include the results 

from EPA’s RRF method in the Federal 

Register notice. Tables 2, 3, and 5, 

including the analyses of PDMR 2009 

only include the TCEQ RRFs as the 

commenter indicates. This was done to 

try to minimize confusion in the notice. 

EPA did note in the proposed notice 

that the results from the EPA RRF 

method are contained in the MOAAD 

TSD. The results for both RRF (EPA and 

TCEQ) methods were contained in 

tables of the MOAAD TSD that had 

Future Design Value projections, 

including Tables in Chapter 6 (the 

Summary Chapter). EPA reviewed the 

FDVs for all modeling based projections 

using both RRF techniques. 

Examination of the modeling results, 

which include some WOE adjustments 

contained in Table 6–3 of the MOAAD 

TSD, reveals that the TCEQ RRF based 

FDV calculation makes only minor 

differences of only one or two tenths of 

a ppb (compared to EPA’s RRF method) 

for most monitors and did not change 

the final modeling projected value 

except for one monitor. 

Comment (MC–7): A commenter 

asserted that full credit for the NOX

reductions from gas compressors in 33 

East Texas counties seems overly 

optimistic. The commenter indicated 

that their understanding is that owners 

or operators of compressor engines 

requested a small portion of the $4 

million in incentives. The commenter 

remains skeptical that the full 

reductions assumed in Combo 10 will 

be achieved by 2009. The commenter 

asserted that the attainment modeling 

thus overstates the ozone reductions 

from the control strategy and indicated 

that EPA should consider this effect as 

part of the Weight of Evidence analysis, 

and should give more weight to the 

PDMR 2009. 

Several commenters indicated that the 

2.4 tpd of NOX reductions from point 

sources in the DFW area that have 2010 

compliance dates are not likely to be in 

place by the beginning of the 2009 

ozone season. These commenters also 

indicated that EPA assumes too much 

by relying on the predictions that early 

compliance will occur for certain 

control measures with 2010 

implementation dates. They claim that 

because of this reliance, the attainment 

modeling overstates the ozone 

reductions from the control strategy. 

The commenters indicated that EPA 

should consider this effect as part of the 

WOE analysis, and should give more 

weight to the PDMR 2009. Furthermore, 

a commenter wrote that if any control 

measure emission reduction will not be 

enforceable until after the 2009 

compliance date, then those emission 

reductions cannot be used to justify 

EPA’s approval. 

Response (MC–7): Combo 10 modeling 

run was the official attainment 

demonstration modeling run submitted 

by TCEQ to EPA in the SIP revision 

submittal. Because of our concerns 

stemming from the inclusion of 

reductions from measures with 2010 

compliance dates, it was not the only 

modeling run considered by EPA in our 

evaluation of whether the DFW area 

would attain the standard by the 

deadline. There was another modeling 

run available in the TCEQ’s public 

record on its proposed action for EPA to 

review; in the proposal and TSDs, we 

label this additional modeling scenario 

the PDMR 2009. We evaluated this 

PDMR 2009 modeling run as a worstcase projection of the 2009 modeling 

picture because it did not project any 

reductions from the rules with 2010 

compliance dates. For example, it did 

not include the 2.4 tpd of NOX

reductions projected from the major and 

minor Point Source rules in the DFW 

area and any projected reductions from 

the East Texas Compressor Engines 

rules that have 2010 compliance dates. 

Thus, PDMR 2009 provides an upper 

boundary of projected ozone FDVs in 

the attainment year. 

The Texas legislature made available 

to compressor engine owner and 

operators $4 million to assist in early 

compliance. As the commenter points 

out, however, the full $4 million was 

not requested by owners and operators 

of compressor engines. Since some 

requests were made, some early 

compliance should occur, but the 

commenter is correct that the level of 

reductions in East Texas by the 2009 

ozone season is probably closer to the 

PDMR 2009 emission reduction level 

than the Combo 10 emission reduction 

level. As a result of this information, 

EPA is putting more weight on the 

PDMR 2009 results than on Combo 10. 

We have evaluated the modeling 

outputs based on an approach that looks 

at the PDMR 2009 outputs, which 

predict ozone levels that are slightly 

worse than what is likely to occur, as 

well as the Combo 10 outputs, which 

predict ozone levels that are more 

optimistic. This evaluation of PDMR 

2009 sets the upper bound of model 

predictions for the FDV in 2009 and the 

Combo 10 run sets the lower bound. In 

making our determination that the State 

had demonstrated that the DFW area 

would attain the 1997 ozone NAAQS by 

its attainment date, we consider the 

TCEQ’s official attainment 

demonstration modeling run (Combo 

10), the results from the PDMR 2009 

modeling, and information that some 

early compliance would occur by the 

2009 ozone season as well as other 

weight of evidence analyses. The model 

projections in Table 6.3 of the MOAAD 

TSD give the non-truncated values for 

the final modeling with some WOE 

adjustments for both the modeling runs 

and both RRF techniques. The 

difference between the PDMR 2009 and 

the Combo 10 run for each monitor is 

0.30 ppb or less when using either the 

TCEQ or EPA RRF technique. EPA’s 

modeling guidance recommends the 

truncation of the decimal places and 

reporting of only integer values for the 

final modeling based projection values. 

When the truncation is done to the 

MOAAD TSD Table 6.3 values 

(Modeling-based assessment with some 

WOE elements included), the results are 

identical for both the PDMR 2009 and 

the Combo 10 modeling runs. Using the 

EPA RRF procedure, both runs result 

with 7 monitors attaining, one monitor 

at 87 ppb, and one monitor at 88 ppb. 

Using the TCEQ RRF procedure, both 

runs result with 7 monitors attaining, 

one monitor at 87 ppb, and one monitor 

at 88 ppb. 

We have considered both the PDMR 

2009 and Combo 10 modeling results 

and put less weight on the Combo 10 

projections because of concerns over the 

inclusion of measures with 2010 

compliance dates. As discussed above, 

however, when EPA’s procedures for 

projecting the future design value are 

followed, there is little difference in the 

results particularly if one considers that 


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a small amount of early compliance will 

occur. Therefore, as further discussed in 

response to other comments, the 

combination of the Modeling 

projections and other WOE elements 

were considered and support the 

conclusion that the area will attain by 

the area’s attainment date. 

Comment (MC–8): The commenter 

indicated that TCEQ intends to reduce 

the amount of DERC values included in 

the modeling because using the entire 

balance of the DERC bank is ‘‘overly 

conservative based on past usage of 

DERCs.’’ The commenter asserted that 

DFW’s past air quality violations 

occurred under scenarios of less DERC 

usage. The commenter concluded that 

this belies a Weight of Evidence (WOE) 

‘‘trend’’ of improving air quality because 

in the future projection nothing is really 

changing from the past when violations 

occurred. 

Response (MC–8): DERCs are banked 

emission credits generated by reducing 

emissions beyond required levels that 

sources can use to exceed certain 

emission limits on a temporary basis. 

EPA guidance discusses why emission 

credits that are being carried in an 

emissions bank ought to be included in 

modeled projections. It can be important 

because these banked emissions come 

back in to the air if the banked credits 

are used. As a result, if these banked 

emissions are not accounted for in the 

future projections, the modeling would 

under-predict future ozone levels if 

some or all of the banked credits are 

used. EPA guidance advises a 

conservative approach in which all 

banked emissions are included in the 

modeled future projections. This 

conservative approach assumes that the 

entire bank would be depleted during 

the attainment year. The TCEQ Bank 

held 20.4 tpd of NOX DERCs when 

TCEQ reviewed the level of credits in 

the bank and included the banked 

DERCs in their future year modeling. 

After finalizing the future year 

modeling, TCEQ reevaluated the 

inclusion of all of the banked DERCs in 

the future projections. TCEQ believed 

that the inclusion of the entire balance 

of the DERC bank was overly 

conservative based on past usage of 

DERCs. They wished to include 3.2 tpd, 

rather than 20.4 tpd, of banked DERCs 

in the future projections. As discussed 

previously, Texas committed to adopt a 

restriction on DERC usage to ensure that 

no more than 3.2 tpd of banked DERCs 

will be used in 2009 and as a result 

preventing 17.2 tpd of potential 

emissions growth. This approval is 

conditioned on TCEQ’s adoption and 

submittal of a complete SIP revision. 

Consequently, in order for EPA to fully 

approve the SIP, the State will need to 

have an enforceable rule in place that 

would not allow 17.2 tpd of the 20.4 tpd 

banked DERCs currently modeled in the 

state’s 2009 Combo 10 and PDMR 2009 

modeling, to be used beginning March 

1, 2009. 

The modeling submitted May 30, 

2007 did include 20.4 tpd of banked 

DERCs in the 2009 future projections. 

Relying upon the State’s commitment to 

revise the DERC rule to limit the use of 

banked credits to 3.2 tpd in 2009, it is 

appropriate to reduce the 2009 future 

modeling projections to 3.2 tpd in 2009. 

(For the calendar years after 2009, there 

will be an enforceable mechanism to 

equate to the limit of 3.2 tpd.) EPA 

therefore adjusted the modeling 

projections in Table 3 of the proposal 

(also included in the MOAAD TSD) to 

assess the impacts of the revised future 

projections. This was done to provide a 

modeling projection that reflected the 

inclusion of banked DERCs of 3.2 tpd in 

2009. This approach is consistent with 

what would have been projected if 

TCEQ had redone the SIP modeling 

with 3.2 tpd for the banked DERCs 

instead of the 20.4 tpd that was 

included in the Combo 10 and PDMR 

2009 modeling. EPA then used the 

revised 2009 modeling projections in 

conjunction with other modeling based 

analysis and WOE considerations in our 

review of the entire attainment 

demonstration. 

The commenter is correct in the 

assessment that DERCs have not been 

used in the past and past air quality 

exceedances did not include any impact 

from DERC usage (since DERCs have not 

been used in the DFW area). Now, with 

the commitment to adopt a restriction 

on DERC use, it is not appropriate to 

continue with the assumption that all of 

the DERCs in the bank will be used in 

the attainment year in the future year 

modeling. 

Because DERC use did not impact 

past exceedances (again because DERCs 

have not been used in the past), EPA did 

not consider the banked DERCs 2009 

usage restriction, as part of our 

emissions and ambient trends analysis 

that we performed in our WOE 

evaluation; rather, it is only in the 

modeling where it was considered. 

Consistent with the commenters 

concerns, EPA was careful in our WOE 

evaluations and review to not consider 

the revised 2009-banked DERCs usage 

restriction in our emission trends 

analysis and monitoring trends analysis. 

For example in Table 5–11 of the 

MOAAD TSD, estimating the actual 

emission reductions between 2007 and 

2009, EPA did not include any 

reductions due to the restriction on 

DERC usage. Therefore, EPA believes 

that we have appropriately considered 

the revised banked DERCs tpd usage 

restriction in adjusting assumptions 

about possible future emissions growth 

in the modeling but consistent with the 

commenter’s concerns, we have not 

considered it in evaluating emissions 

and monitoring trends (analysis 

included in the WOE analysis). For a 

full discussion of DERCs and 

conditional approval, see the DERCs 

comments section below. 

Comment (MC–9): The commenter 

indicated that EPA’s reliance upon the 

low 2007 monitor readings is misplaced 

since extremely unusual weather, rain 

and low temperatures, dominated the 

2007 DFW ozone season. The 

commenter continued that the first 100+ 

°F temperature day was not reached 

until late August. The commenter 

concluded that EPA should not give 

TCEQ credit for something achieved 

only by the grace of God. 

Response (MC–9): We rely on the 2007 

monitored air quality levels as part of 

our Weight of Evidence analysis. We 

investigated the 2007 meteorology to 

determine how it compared with the 

DFW normal ozone season meteorology. 

To help account for all the different 

variables that impact the frequency of 

ozone we utilized a Meteorological 

Adjusted Trends analysis that was done 

by EPA personnel at Office of Air 

Quality Planning and Standards 

(OAQPS) for the DFW area to assess the 

ozone conduciveness of the 2007 ozone 

season. OAQPS’s analysis utilizes 

temperature and precipitation data in 

addition to several other factors. The 

results of this analysis were included in 

our proposal, and indicated that overall 

2007 was near the normal meteorology 

for DFW’s ozone season. See Chapter 5, 

section 5.15 and Chapter 6, section 6.3 

in the MOAAD TSD. 

The commenter asserts that the 2007 

ozone season was biased low due to the 

influence of more rain than normal and 

less 100 °F days than normal. EPA 

reviewed monthly meteorological 

National Climatic Data Center 2007 data 

for DFW International Airport (for the 

DFW ozone season months of March 1– 

October 31). We evaluated average 

monthly temperature, monthly average 

maximum temperature, and monthly 

precipitation. Looking at this 

temperature information and 

precipitation data, EPA’s assessment is 

that, while for several months the 

precipitation was above average, the 

ozone season and the core ozone 

months (June–September) were near 

normal overall. For more information, 

see the Supplemental TSD. Ozone 

formation is affected by a number of 


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meteorological parameters and just 

looking at these three parameters does 

not give a complete evaluation of the 

ozone conduciveness of the 2007 ozone 

season. 

The commenter was concerned that 

the meteorology was unusually 

nonconductive for generation of ozone 

exceedances in 2007. In light of this, 

EPA also reviewed ozone exceedance 

data for 2007, and found that the first 

exceedance occurred April 28th, and a 

number of exceedance days occurred 

starting in late July (7/24) and the last 

exceedance occurred on October 4th. In 

all, there were 12 days with 

exceedances at one or more monitors in 

the DFW area in 2007. This is below the 

long-term normal trend of 

approximately 30 exceedance days per 

year. The limitation of just evaluating 

the number of exceedance days to 

determine if meteorology was normal or 

below normal is that exceedance days 

are a combination of meteorology and 

emissions. Emissions decreases due to 

fleet turnover among other things could 

also explain part or all of a lower than 

normal number of exceedance days in 

2007. 

Finally, we note that one reason we 

evaluate attainment of a NAAQS based 

on three years of data is that use of 

several years tends to mitigate any 

unusual meteorology that occurs during 

a specific year. The year 2007 is the first 

of the three years of data (2007–2009) 

that will be used for determining if the 

DFW area reaches attainment in 2009. 

The 2007 4th high maximums were all 

in the 80s ppb range or less for monitors 

that are typically near the area’s design 

value. This is significantly lower than 

other recent years. Meteorological 

Trends analysis indicates that 2007 was 

closer to normal than 2005 and 2006. 

Therefore, the 2007 data is important 

from both a trends perspective as well 

as being the first of three years utilized 

in determining if the area reaches 

attainment in 2009. 

Comment (MC–10): The commenter 

indicated the DFW emissions inventory 

has gaps and that EPA knows that there 

are hundreds of industrial sources 

involved in the gas well drilling and gas 

pipeline operations that were not 

modeled by the TCEQ and which TCEQ 

assumed to be insignificant. The 

commenter asserted that without 

modeling these significant sources of 

NOX emissions, the attainment 

demonstration may be in greater 

jeopardy than EPA or TCEQ admits. 

Response (MC–10): The TCEQ 

projected the future emissions inventory 

for the industrial sources involved in 

the gas well drilling and gas pipeline 

operations with the most recent 

information available at the time of the 

emissions inventory development. 

Photochemical modeling is a very 

complex process and the emissions from 

natural gas production in the DFW area 

were rapidly changing during the last 

two years of modeling and SIP 

development and continue to do so. 

Improving emission estimates and 

projections is one of the elements of 

photochemical modeling that always 

requires an agency to balance the need 

to incorporate new information with the 

time available to complete the 

photochemical modeling tool for SIP 

development, and still meet the 

submittal deadline. 

TCEQ’s basecase and future year 

(2009) SIP modeling did include 

estimates for emissions from industrial 

sources involved in gas well drilling 

and pipeline operations. During the 

commissioners meeting when the TCEQ 

adopted the DFW attainment 

demonstration SIP in May 2007, there 

were industry comments indicating 

emission estimates from natural gas 

compressor engines should be higher 

than were in the current modeling. 

Although the commissioners moved 

forward to adopt and timely submit the 

DFW 8-Hour Ozone attainment 

demonstration SIP, they also directed 

TCEQ staff to research the accuracy of 

the emissions inventories for these 

sources that were relied on in the 

attainment demonstration modeling. 

TCEQ staff subsequently conducted an 

additional survey to re-evaluate the 

number of stationary, gas-fired engines 

and other NOX emission sources that are 

common at natural gas production and 

gathering (P&G) facilities, in the ninecounty DFW area. TCEQ provided that 

information to EPA as supplemental 

WOE in a letter dated April 23, 2008, 

which EPA has considered in its 

decision on whether to approve the 

attainment demonstration SIP. Details of 

this survey, the results, and explanation 

of how this information was utilized in 

EPA’s review were included in the 

proposal package (Proposal FRN, 

MOAAD TSD, etc.). 

The survey collected data on existing 

NOX sources and expected additional 

installations by 2009 so that a 

comparison to estimated levels in the 

2009 SIP modeling could be conducted. 

The survey also collected data on when 

the NOX emitting sources were 

installed. The survey indicated that P&G 

operations grew much more rapidly 

than projected in the SIP. Based on the 

survey results, TCEQ concluded that the 

majority of emissions growth would 

come from the increase in compressor 

engines and not from other facets of 

P&G operations. TCEQ therefore 

provided new estimates for the 

compressor engines’ emissions growth. 

The survey indicated that almost all 

of the rapid growth that created the 

underestimation of additional engines 

and other related NOX sources from 

natural gas P&G emission sources had 

occurred after the 1999 base year. 

Fortunately, TCEQ put in place 

regulations that will control rich and 

lean burn natural gas fired compressor 

engines in the DFW area. TCEQ also 

controlled some engines involved with 

drilling operations in the Increment of 

Progress SIP. 

From the modeling perspective, using 

the new survey’s results, the 

underestimation in the growth of 

emissions is greatly mitigated by 

TCEQ’s implementation of NOX controls 

on emission sources in this industry 

group in Chapter 117 rules adopted as 

part of the May 30, 2007 SIP 

submission. While mitigated to a large 

extent, the new survey data indicate that 

emissions in the demonstration 

modeling, i.e., the 2009 Combo 10 

modeling, from these natural gas P&G 

sources would add 3.3 tpd based on our 

analysis of the TCEQ survey data. Using 

modeling sensitivity runs, we accounted 

for this approximate increase of 3.3 tpd 

in the projected emissions inventory, 

and we were able to estimate the effect 

on the modeled ozone levels. See Table 

4 in the proposal. In considering the 

underestimation from a ’real world’ 

standpoint, it is important to note that 

due to TCEQ’s adopted regulations, a 

much larger amount of actual reductions 

of NOX emissions (estimated as 35.7 

tpd) will occur between 2007 and 2009 

from the regulations on compressor 

engines and these extra reductions will 

help reduce DFW area ozone levels. 

While these emissions were not fully 

accounted for in the initial 

photochemical modeling, TCEQ had 

developed the emission inventory for 

this industry group consistent with 

EPA’s guidance. EPA appreciates the 

additional survey information that 

TCEQ provided and, EPA considered 

the emissions in reviewing the 

attainment demonstration and found 

that TCEQ’s revised emission estimates 

were acceptable. This information was 

clearly presented as part of the proposed 

rulemaking action and the commenter 

has not identified any substantive flaws 

with that analysis. 

Comment (MC–11): The commenter 

indicated that the emissions inventory 

appears flawed, in part from the 

observation that the latest VOC area 

source emissions inventory was 

unaffected despite the substantial 

revisions to the gas drilling/compressor 

engine count, as reflected in revised 


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NOX area source inventory revisions. 

The commenter further indicated that 

VOC emissions from the engine stacks, 

and fugitive emissions from the piping 

and valves that connect the engines, 

appear not to have been incorporated 

into the emissions inventory, and more 

importantly, not to have been 

considered in the photochemical 

modeling. The commenter asserted that 

the absence of these emissions in the 

revised inventory placed additional 

doubt on to the accuracy of the 

photochemical modeling to predict 

ozone levels in the western part of the 

nonattainment area. 

Response (MC–11): The commenter is 

correct that the VOCs from P&G 

facilities in the DFW area may be 

underestimated, since the number of 

P&G facilities and related NOX sources 

had a large underestimation. As 

provided above, there are inherent 

uncertainties with emissions 

inventories. Unlike the NOX emission 

discussed previously, however, the VOC 

emissions from natural gas production 

are largely compounds that are not 

significantly reactive in the formation of 

ozone. EPA defines ‘‘Volatile Organic 

Compounds’’ (VOCs) per 40 CFR Part 

51.100(s) (as amended through January 

18, 2007) and specifically lists Methane 

and Ethane as organic compounds that 

have been determined to have negligible 

photochemical reactivity. Methane and 

ethane are typically 85–90% or more of 

the compounds present in natural gas 

from gas wells so emissions from 

natural gas production would be 

expected to have a small impact on 

ozone production. In addition, modeling 

sensitivity analyses have shown that 

large reductions in all VOC emissions in 

the DFW area result in only very small 

changes in the area’s ozone 

concentration level. Therefore, an 

underestimation of P&G VOC emissions 

would not change the Combo 10 and 

PDMR 2009 modeling projections 

significantly. See Section 4.2 of 

ENVIRON’s ‘‘Ozone Benefits in DFW 

from Emission Controls in the 2009 and 

2012 Future Years,’’ September 2006, 

included as a reference to Chapter 2 of 

the TCEQ TSD. 

TCEQ did not collect data on VOC 

sources in the 2007 survey that they 

conducted of natural gas P&G facilities 

in the DFW area. TCEQ focused on NOX

emission sources in their survey since 

numerous photochemical modeling 

analyses had shown that elevated ozone 

levels in the DFW area were much more 

sensitive to changes in NOX emissions 

than VOC emissions. For these same 

reasons, EPA does not believe that 

uncertainty in the natural gas P&G VOC 

emissions would result in a significant 

change in modeling projections or 

change our conclusion that the DFW 

area will attain the 1997 ozone standard 

by its attainment date. 

Comment (MC–12): The commenter 

indicated that the Base Case Monitoring 

Data is skewed because it relies on the 

1999 episode and, focusing on the 

Frisco Monitor, misrepresents the 

greater and more current problems 

associated with monitoring data from 

monitoring stations to the northwest 

and west. The commenter continued 

that the use of this 10-year old base case 

set results in under-emphasis of the 

effect of the numerous sources, 

including the Ellis County cement kilns, 

Barnett Shale natural gas and oil 

drilling, and EGU’s to the south of the 

metroplex which often have their plume 

carried in southeasterly winds into 

Tarrant County. The commenter 

asserted that the 1999 data set is flawed 

due to the unusual meteorological 

conditions as well as its overall lack of 

representativeness and that Texas must 

be directed to develop additional base 

case data sets for SIP planning efforts. 

Response (MC–12): EPA does not 

agree with the commenters’ assertions 

for several reasons. As discussed in 

Section 2.3 of EPA’s MOAAD TSD, EPA 

reviewed this 1999 episode and found it 

to be acceptable and representative of 

the combination of meteorology and 

emissions that generate ozone 

exceedance levels near the DV of the 

area at the time episodes were being 

selected for development of this SIP. 

The 2009 modeling projections evaluate 

ozone levels at all the monitors in the 

DFW area and, for this episode, both the 

Denton and Frisco monitors had the 

highest FDVs; therefore, the emphasis 

was not just on the Frisco monitor as the 

commenter asserts. 

Photochemical grid modeling takes 

several years to develop and thus, at the 

time of submittal of a SIP, the episodes 

are typically several years old. Selection 

of episodes to model for SIP planning is 

a balance of finding historical periods 

with several days of exceedances that 

are representative of the conditions that 

generate ozone near the design value for 

the area and developing acceptable base 

case modeling in time to allow for a 

timely submittal of an attainment 

demonstration. At the time that TCEQ 

proposed the DFW attainment 

demonstration SIP in December 2006, 

the episode was just over 7 years old, 

not 10 years old as the commenter 

indicated. 

Chapter 2 of the MOAAD TSD 

included sections that detailed EPA’s 

guidance on episode selection, how the 

episode was originally chosen and 

further discussion and review that 

occurred in 2005 about the adequacy of 

this episode and the potential benefits 

of other episodes The DFW area 

monitors that have been DV monitors or 

had values near the area’s DV for the 

period 1999–2005 (the period that was 

reviewed for potential episodes was 

1998–2004) indicates that all of these 

monitors have been either north of the 

DFW area (Frisco monitor) or in the 

northwest sector (Tarrant and Denton 

Counties monitors). EPA has done a 

detailed review of both TCEQ’s analyses 

and EPA’s analyses of the conceptual 

model for high ozone in DFW and what 

monitors are the DV monitors. In years 

when light winds are more 

predominantly from the south, the 

northern monitors (Denton and Frisco) 

are the DV monitors. Other years, the 

winds and frequency of light winds are 

predominantly from the southeast, 

resulting in the Tarrant and Denton 

Counties monitors becoming the DV 

monitors. The location of the DFW 

area’s DV monitor depends on the 

distribution of the frequency of wind 

directions during ozone conducive 

meteorology, but it is consistently on 

the downwind side of the DFW area. In 

fact, assuming the preliminary 

monitoring data through October 31, 

2008 does not change, the Denton 

monitor will be the DV monitor for the 

2006–2008 period. Preliminary data also 

indicate that the Denton monitor may be 

the DV monitor for the period 2007– 

2009 (based on 2007 and 2008 

monitoring data). Approximately 70% 

of the local NOX emissions that lead to 

high ozone levels are emitted from 

mobile (On-Road and Nonroad emission 

sources) and the highest ozone levels 

typically occur downwind of the core 

DFW emissions area. Figures 3 & 5 of 

TCEQ’s Appendix B of their SIP 

submittal illustrate the distribution of 

NOX emissions from On-Road and 

Nonroad emissions. Modeling, 

monitoring, and aircraft flights confirm 

that the highest levels of ozone occur 

downwind of the core DFW emissions 

area. As discussed above, the Frisco and 

Denton monitors are often downwind of 

the core DFW emissions area. Therefore, 

EPA does not agree that this episode, 

the control strategy, and the SIP overall 

are biased by the Frisco monitor being 

one of the highest ozone monitors in the 

base year. 

The commenter asserted that using 

the 1999 episode results in underemphasis of the effect of the numerous 

sources, including the Ellis County 

cement kilns, Barnett Shale natural gas 

and oil drilling, and EGU’s to the south 

of the DFW metroplex which often have 

their plume carried in southeasterly 


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winds into Tarrant County. As 

discussed elsewhere in this response 

and in EPA’s MOAAD TSD, EPA 

conducted a thorough review of EPA’s 

episode selection guidance, conceptual 

model for high ozone events in DFW, 

and episodes available for modeling at 

the time of episode selection and EPA 

determined that this episode was 

appropriate and acceptable. EPA does 

not recommend episode selection be 

based on trying to target specific 

industry/emission sources but should 

weigh a number of factors in selecting 

episodes for photochemical grid 

modeling to be utilized for SIP 

development as was done in this 

situation. 

Afternoon wind from the southeast is 

one of the more prevalent wind 

directions for high ozone in the DFW 

area. In TCEQ’s conceptual model 

description for high ozone events in the 

DFW area, morning winds out of the 

south or southwest often occur and then 

transition to out of the southeast or east 

in the afternoon. Therefore, the sources 

mentioned can impact the Denton and 

Frisco monitors for some of the hours of 

the day (that contribute to a high 8-hour 

ozone value). This episode has two days 

with winds from the southeast in the 

afternoon (8/17 and 8/22). August 17th 

had winds out of the southwest in the 

morning that transitioned to winds out 

of the southeast in the afternoon. 

Forward wind trajectories for the 17th 

indicate the emissions from the Ellis 

County cement kilns were carried over 

the Frisco and Denton monitors. On the 

17th, it is also likely that emissions from 

the other sources mentioned would also 

be carried over the Denton and 

potentially Frisco monitors. Even on 

days that the winds do not take 

emissions from these sources over the 

Frisco and Denton monitors, the 

modeling still utilizes these emissions 

(and changes in these emissions) in 

projecting ozone levels in the modeling 

domain. Among modeling analyses that 

can be impacted by emission reductions 

at these sources are changes in ozone 

exceedance metrics, such as number of 

grid cell 8-hour ozone exceedances 

predicted and other metrics that 

consider the level of exceedances 

predicted for each grid cell. 

In summary, EPA has reviewed the 

episode and determined that the 

episode is representative of the 

conditions most often associated with 

high eight-hour ozone in the DFW area. 

Comment (MC–13): Commenters 

indicated that the future case attainment 

demonstration modeling included NOX

reductions from Phase I Clean Air 

Interstate Rule (CAIR) controls for EGUs 

outside of Texas. Commenters indicated 

that since these reductions are now 

unlikely to occur, at least on the original 

timeframe, the anticipated ozone air 

quality benefits will be reduced. 

Commenters asserted that EPA should 

consider this effect on the modeling and 

the WOE analysis. 

Response (MC–13): The EPA has 

considered the impact of a CAIR vacatur 

and determined that even an immediate 

vacatur of CAIR would not change our 

conclusion that the modeling and 

weight of evidence show that the DFW 

area will attain the 1997 8-hour ozone 

standard by the deadline. The principal 

reasons for this conclusion are: (1) 

Chapter 117 rules in the Texas SIP 

implemented in the entire eastern half 

of Texas are equivalent to the Phase I 

rules of CAIR; (2) evaluation of controls 

already installed in the nearest States 

impacted by CAIR, Arkansas and 

Louisiana, show that significant 

reductions will still be implemented; (3) 

many of the more distant states 

impacted by the CAIR vacatur are also 

subject to the NOX SIP call so much of 

CAIR Phase I NOX reductions will 

remain in place; and (4) available 

modeling shows that loss of CAIR only 

has a small impact on the DFW area. 

Texas implemented NOX controls on 

EGUs in the entire eastern half of Texas 

that are approved into the Texas SIP, are 

enforceable, and are equivalent to 

reductions from CAIR Phase I for East 

Texas EGUs. The rules can be found in 

Texas Administrative Code Title 30 Part 

1 Chapter 117 Subchapter E Division 1 

(117.3000–117.3056). Therefore, the 

level of NOX reductions from EGUs 

within the entire eastern half of Texas 

for the 2009 period is not related to the 

status of the CAIR rules. With regard to 

EGU emissions in the western half of 

Texas, EPA has concluded that 

emissions from these sources would 

rarely be transported to the DFW area 

during periods of high ozone in DFW. 

Thus, any changes in emissions from 

Texas EGUs related to a vacatur of CAIR 

are not expected to impact DFW ozone 

exceedance levels prior to the 

attainment date. 

In fact, the main change in emissions 

in the DFW photochemical modeling 

domain due to a CAIR vacatur is for 

CAIR states that were not part of the 

NOX SIP call and were outside of Texas. 

Of these states, Louisiana and Arkansas 

are the closest upwind states to DFW 

and would be expected to have the 

largest potential impact on ozone level 

changes in DFW due to the CAIR 

vacatur. We have reviewed EPA’s Clean 

Air Market’s Division National Electric 

Energy Data System database (July 2008 

version) that tracks equipment that has 

been installed to meet the CAIR 

requirements for the EGUs in these two 

states. Our evaluation of controls 

installed at facilities in Arkansas and 

Louisiana considered whether installed 

controls were integral to operation of 

the unit (example: Low NOX Burners), 

or if the controls could be shut-off 

(Example: Over-fire Air) or potentially 

bypassed (SCR). We have also conferred 

with Louisiana and Arkansas 

Departments of Environmental Quality 

in an attempt to confirm the information 

in the database. 

Our analysis of Louisiana major 

EGU’s indicates that most controls are 

based on Over-Fire Air or SCR (based on 

discussions with LDEQ (September/ 

October 2008)). However, the Dolette 

Hills is the closest large Louisiana coalfired EGU that is outside Texas and has 

the highest potential to impact DFW 

area ozone levels of any coal-fired EGU 

outside of Texas. It is often upwind of 

the DFW area when the DFW area has 

elevated ozone levels. Low NOX burners 

and Over-Fire air have been installed at 

the Dolette Hills unit to reduce NOX

emissions. In the absence of CAIR, it is 

possible that the utilization of Over-Fire 

air could cease, but the Low NOX

burners are integral to the boiler 

operation and cannot be bypassed. 

Therefore, even if the Over-Fire Air 

were not operated there would still be 

permanent large NOX reductions on the 

order of 2000 to 3000 tpy of NOX (based 

on Discussions with LDEQ) compared to 

4000 to 5000 tpy of NOX with Over-Fire 

Air and Low NOX Burners. 

Our analysis of EGUs in Arkansas 

indicates that for the coal-fired EGU’s, 

most are being controlled with OverFire Air, but one 523 MW unit is being 

controlled with Low NOX burners that 

have been installed and should remain 

installed. For the gas-fired EGUs, most 

are being controlled with Dry Low NOX

burners in combination with SCR. The 

Low NOX Burners are integral to the 

operation. The SCR, however, 

conceivably could be turned off. Dry 

Low NOX burners can achieve up to a 

30% reduction by themselves so 

significant reductions will still occur. 

Therefore, even with a vacatur of 

CAIR, significant reductions will still 

occur in Arkansas and Louisiana 

including at the closest, upwind plant, 

Dolette Hills. As for the reductions in 

other States impacted by a CAIR 

vacatur, many of these States were part 

of the NOX SIP call. The NOX SIP call 

reduction requirements remain in place. 

States affected by the NOX SIP call 

include: Alabama, Connecticut, 

Delaware, Georgia, Illinois, Indiana, 

Kentucky, Maryland, Maine, Michigan, 

Missouri, New Jersey, New York, North 

Carolina, Ohio, Pennsylvania, Rhode 


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Island, South Carolina, Tennessee, 

Virginia, West Virginia and the District 

of Columbia. While some states’ rules 

implementing the NOX Budget Trading 

Program (established by the NOX SIP 

call) have a sunset provision in 

anticipation of being replaced by the 

CAIR ozone-season trading program, 

EPA expects the majority of controls to 

remain in place. EPA has asked States 

with sunset provisions to move quickly 

to address this concern. 

We believe that it is reasonable to 

consider that the reductions identified 

above will occur because the previously 

installed controls are integral to the 

operation of the EGUs and are not likely 

to be bypassed or circumvented or are 

required to comply with regulations 

implementing the NOX SIP call. 

EPA also considered available 

modeling evidence in considering the 

impact of a CAIR vacatur. First, the 

photochemical modeling upon which 

the CAIR rule itself was based did not 

result in any other State being included 

in the CAIR rules because of its impact 

on the DFW area. In other words, no 

state was included in CAIR because of 

its impact on the DFW area. 

No modeling exists that directly 

evaluates the impact of a CAIR vacatur 

on the modeling episodes used in the 

final DFW SIP modeling so it is not 

possible to directly evaluate the impact 

on Combo 10 or PDMR 2009 control 

strategy runs. EPA has found two 

modeling analyses that help to evaluate 

the potential impact of the CAIR vacatur 

on DFW ozone levels. 

We also have reviewed sensitivity 

modeling that evaluated potential CAIR 

impacts conducted on an earlier version 

of DFW modeling. This modeling was 

included in the HARC 35 Project Phase 

II Report (‘‘Dallas/Fort Worth CAMx 

Modeling: Improved Model Performance 

and Transport Assessment Project H35, 

Phase 2’’; ENVIRON; August 2005). The 

H35 Phase II report evaluated the 

impact of the CAIR emission reductions 

throughout the Eastern U.S. on DFW 

ozone levels in 2010. The report 

included a bar chart (Figure 10–4), 

showing episode average contributions 

to high 8-hour ozone in the DFW 9- 

county NAA by source region and 

emissions group. Side-by-side bars show 

the subtle changes due to the CAIR EGU 

controls. Controls expected from CAIR 

reduced episode average high ozone in 

the DFW NAA by 0.3 ppb. The episode 

peak ozone was also lowered 0.3 ppb 

over DFW from the CAIR controls. This 

early modeling did not include some of 

the later emission inventory and 

meteorological refinements, but a new 

evaluation with the modeling submitted 

with the attainment demonstration 

would not be expected to yield 

significantly differing results. 

We also looked at some earlier 

modeling that was included in Table 

4–1 of the H35 Phase I Report (HARC 

Project H35, Transport Contributions 

From Out-of-State Sources to East Texas 

Ozone, February 2005). The H35 Phase 

I report indicated that controlling a 25% 

NOX reduction on all EGUs in Arkansas, 

Louisiana, Mississippi, Missouri (NOX

SIP call state), Oklahoma (non-CAIR 

state), Tennessee (NOX SIP call state), 

and the Gulf of Mexico (non-CAIR area) 

yielded a 0.1 ppb reduction in ozone on 

average 2007 elevated ozone levels 

(evaluated levels above 75 ppb and 85 

ppb) in DFW area for the DFW’s SIP 

episode. While this analysis is for 2007 

and conservatively includes 25% NOX

reductions in two NOX SIP call states, 

25% reductions in Oklahoma (non-CAIR 

state), and 25% reductions in Gulf of 

Mexico EGUs; all of which are 

additional reductions not related to the 

CAIR Phase I rule. The 2007 modeling 

analysis is further evidence that the 

DFW area is not influenced by out-ofstate EGU emissions at times when 

elevated ozone levels occur in DFW. 

Both of these modeling analyses 

consistently show a picture that out of 

state reductions only have a small 

impact of 0.1 to 0.3 ppb or less on 

model projected design values in the 

DFW area. The two CAIR assessment 

analyses (EPA—Fall 2008 and H35 

Phase II) are conservative because they 

remove all CAIR reductions from the 

modeling. This does not take into 

account that for non-NOX SIP call states, 

some CAIR controls will generate 

reductions because the controls are 

integral to the combustion process and 

will not likely be removed (Low NOX

Burners, etc.). These two CAIR 

modeling analyses also rely on 2010 

EGU projections, which include an 

additional year of EGU growth, 

compared to the growth that would be 

included for a 2009 evaluation. These 

modeling evaluations over predict for 

NOX during the 2009 ozone season 

because many states will still have in 

place NOX controls required by the NOX

SIP call. 

The worst-case assessment of a 0.1 to 

0.3 ppb increase on model projected 

FDVs, in itself, is small enough that for 

most model projections, no change in 

the truncated ppb value would occur. 

Given that the actual impact of a vacatur 

on emissions would be smaller than in 

these worst case analyses, EPA believes 

that the status of the CAIR rules should 

not impact our decision to approve the 

DFW attainment plan. 

We have included further discussions 

of a vacatur of CAIR on the modeling 

and WOE analysis in a separate 

response to comment that addresses 

comments on the adequacy of the WOE 

analysis and the conclusion of whether 

the DFW NAA will reach attainment. 

Comment (MC–14): The commenter 

indicated that the DFW attainment 

demonstration model has considerable 

challenges as detailed in the Notice of 

Proposed Rulemaking. The commenter 

noted that model development is a 

resource intensive process and the state 

simply needs to apply additional 

resources to this process. The 

commenter stated that throughout the 

development of the May 2007 SIP 

revision, the State indicated that it had 

insufficient resources to improve the 

attainment demonstration and 

incorporate alternative and more recent 

ozone episodes. The commenter 

concluded that the State has not 

allocated adequate resources to SIP 

development, including model 

development, to develop models robust 

enough to accurately predict ozone 

concentrations in the attainment year 

and beyond. The commenter then 

concluded that as part of any final 

action, EPA should advise the state that 

failures to program sufficient resources 

to meet CAA requirements in the future 

will not be accepted as justification of 

inadequate or incomplete 

demonstrations of attainment. 

Response (MC–14): All states and 

other entities that conduct 

photochemical modeling must address 

competing priorities and determine 

whether additional work will provide 

significant additional value. They must 

consider several factors including the 

time available for completion of 

modeling of episode(s), updating of 

emissions inventories, the resources 

needed to conduct further refinements 

or additional episodes, and the overall 

benefit of delaying the project to 

conduct additional modeling work. 

The commenter is correct that 

modeling is a very resource intensive 

process. Photochemical modeling 

requires creation of very detailed 

emission inventories and meteorological 

modeling to be used in photochemical 

modeling in an attempt to replicate a 

historical event when ozone 

exceedances have occurred. Once 

photochemical modeling has been 

created that performs sufficiently well, 

the basecase modeling can then be used 

in conjunction with future case 

modeling of the same meteorological 

conditions to test attainment 

demonstration strategies. It often takes 

many iterations of refinement of 

emissions and/or meteorological fields 

to result in basecase photochemical 

modeling that performs sufficiently in 


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11The modeling guidance does not specifically 

preclude the use of WOE when the modeled values 

are higher than the recommended WOE range. 

accordance with TCEQ’s meteorological 

performance metrics and EPA model 

performance metrics. 

As discussed in the proposal and the 

MOAAD TSD, TCEQ did consider and 

complete exploratory work on other 

episodes. But initial analyses indicated 

that the additional episodes would not 

give significantly different results 

compared to the existing episode. As we 

explain in Section 2.3 of the TSD, we 

believe in this case, the one episode is 

acceptable for control strategy 

development. EPA evaluated the 

preliminary analyses of other episodes 

and concurred that it did not appear 

that the additional episodes would alter 

the model projections on what was 

needed to reach attainment. 

EPA believes that the episode 

selection is appropriate, and that the 

modeling was sufficiently robust. The 

demonstration modeling combined with 

the WOE analyses are sufficient to show 

that the DFW area will attain by the 

deadline. 

Comment (MC–15): Commenters 

indicated that the DFW 8-hr ozone SIP 

proposal by TCEQ is significantly 

flawed and fails to support the required 

attainment demonstration by 2010. 

Commenters continued that the DFW 

modeling by TCEQ shows that several 

ozone monitors in 2010 will still exceed 

the rounded-up standard of 84 ppb. A 

commenter asserts that the CAA 

requires that SIPs show clear attainment 

for all ozone monitors in a 

nonattainment area and the reason that 

the air modeling shows exceedances in 

2010 is because the proposed reductions 

by TCEQ are inadequate. 

Commenters also indicated that 

according to Table 5 of the Federal 

Register notice, TCEQ’s plan predicts 

that 2 monitors in the region would not 

meet the 8-hour ozone NAAQS after 

implementation of the control strategy 

(PDMR 2009) and consideration of 

TCEQ’s Weight of Evidence. 

Commenters continued that they are 

aware that EPA’s ozone implementation 

guidance allows a ‘‘Weight of Evidence’’ 

demonstration to supplement the 

modeling analysis required by the CAA 

but assert that this analysis fails to 

overcome the inadequacy of the TCEQ’s 

proposed control strategy to bring the 

DFW area into attainment. 

Commenters indicated that the 

proposal establishes repeatedly that 

ambient air quality is likely to remain 

above the artificial rounded-up standard 

of 84 ppb (Tables 2, 3 and 5). The 

commenters went on to assert that after 

disclosing that state WOE calculations 

fall short of meeting the attainment goal, 

EPA ultimately relies on their 

‘‘simplistic’’ analysis concluding that 

15% of the NOX emissions inventory 

will be reduced by existing measures 

not present in 2007. The commenters 

continued that given the degree to 

which design values have to fall, from 

95 ppb to 84 ppb, and in light of the 

2010 attainment date, EPA should 

consider that the drop in the NOX and 

VOC emissions inventories from 2007 to 

2009 are completely insufficient, 

according to EPA’s own studies and 

guidance, to bring about the drop in DVs 

needed to reach attainment. The 

commenters further continued that 

EPA’s own analysis of the most recent 

TCEQ modeling shows that the State 

was only able to get all the area’s 

predicted DVs below 88 ppb with a nonstandard and non-approved calculation 

of RRF factors and EPA’s own analysis 

with the proper RRF procedure showed 

that monitors were still above the 88 

ppb threshold. 

A commenter indicated that the WOE 

approach by the TCEQ is flawed since 

it fails to show attainment by 2010 and 

EPA needs to reject it as bad science. 

Response (MC–15): We responded to 

comments on the TCEQ and EPA RRF 

methods in a separate response to 

comments above. Overall, EPA 

considered both RRF methods and the 

results of those methods in our review. 

Also, as explained in previous 

responses, we considered the results of 

modeling from both Combo 10 and 

PDMR 2009 modeling runs. 

EPA disagrees with the commenter 

that the modeling alone must 

demonstrate attainment in order for EPA 

to approve the attainment 

demonstration. EPA discussed both in 

the DFW MOAAD TSD and the 

proposal, EPA’s guidance on modeling 

and WOE usage. As with any predictive 

tool, there are inherent uncertainties 

associated with photochemical 

modeling (emission estimates, emission 

projections, meteorological modeling, 

chemical reaction equations and 

simplifications, etc.). EPA’s guidance 

recognizes these limitations and 

provides approaches for considering 

other analytical evidence to help assess 

whether attainment of the NAAQS is 

likely. This process is called a WOE 

determination. EPA’s modeling 

guidance (updated in 1996, 1999, and 

2002) discusses various WOE 

approaches. This was further updated in 

2005 and 2007 for the 1997 8-hour 

ozone attainment demonstration 

procedures to include a WOE analysis 

as an integral part of any attainment 

demonstration due to concerns of 

modeling uncertainties. This guidance 

strongly recommends that all attainment 

demonstrations include supplemental 

analyses beyond the recommended 

modeling. These supplemental analyses 

should provide additional information 

such as monitoring data analyses, and 

emissions and air quality trends, which 

help corroborate the overall conclusion 

from the photochemical modeling. 

EPA’s modeling guidance specifically 

recommends that a WOE analysis be 

included as part of any attainment 

demonstration SIP where the modeling 

results predict FDVs ranging from 82 to 

less than 88 ppb (EPA’s 2005 and 2007 

A.D. guidance documents). It is 

important to note that EPA recommends 

a WOE analysis even if the modeling is 

demonstrating attainment at all the 

monitors. EPA’s interpretation of the 

Act to allow a WOE analysis has been 

upheld. See 1000 Friends of Maryland v. 

Browner, 265 F. 3d 216 (4th Cir. 2001) 

and BCCA Appeal Group v. EPA, 355 

F.3d 817 (5th Cir. 2003). 

In this case, the commenters are 

correct that the final modeling based 

projections show two monitors above 

attainment levels. Prior to conducting 

the model based projections, the highest 

modeling values were 88/89 ppb 

(TCEQ/EPA RRF method), but after 

modeling based adjustments were 

conducted to account for reduced 

airport emissions, DERC usage 

limitations, and back-up generator 

reductions, the highest value using 

either RRF was 88 ppb. EPA specifically 

recommends a WOE analysis be 

performed when modeling values are 

within the range indicated by the DFW 

analysis.11

EPA’s guidance (2005 A.D. Guidance) 

does indicate that a local 30% NOX

reduction may only yield a 3–4 ppb 

change in modeling values. That 

assessment was based on coarser 

resolution photochemical modeling that 

is typically less responsive to emission 

changes than the finer grid modeling 

that was used in DFW. Here, EPA is 

relying on analyses that were done 

employing the DFW modeling to 

determine the potential change in ozone 

due to the additional NOX reductions 

that are estimated to occur by 2009. 

Relying on these DFW analyses, EPA 

estimates that the 25.4% local DFW area 

NOX reductions occurring between 2007 

and 2009 would reduce ozone 

concentrations by approximately 3–4 

ppb. As discussed in detail below, EPA 

is considering much more than just the 

modeling in making our conclusions on 

the adequacy of the attainment 

demonstration and determining that the 

2005–2007 DV of 95 ppb will drop to 

attainment levels (84 ppb) in 2009. 


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EPA evaluated many factors in the 

WOE. These items include reductions 

not included in the modeling based 

projections (energy efficiencies), 

unquantifiable measures 

(AirCheckTexas, Dallas Sustainable 

Skyline Initiative, etc.), meteorological 

analyses of severity of ozone seasons 

(the base period and recent years, 

including 2007), most recent monitoring 

in 2007 (a 4th high of 89 ppb at two 

monitors and the other 18 monitors had 

4th high values of 87 ppb or less), the 

court’s vacatur of CAIR, progress in 

implementing the TERP program, and 

progress in implementing the early 

compliance incentive on natural gas 

compressor engines outside the DFW 

area. The amount of NOX reductions 

quantified in the SIP from the 2007 

period that are estimated to occur by 

2009 are approximately 15% of the 

estimated 2007 EI; these reductions will 

come from the existing federal, state, 

and local measures. When one includes 

the additional reductions due to the 

underestimation of emission reductions 

from compressor engines, the backup 

generators, and the State’s progress in 

implementing TERP, there would be a 

25.4% reduction in NOX emissions 

between 2007 and 2009, which could 

yield approximately a 3–4 ppb drop in 

ozone based on modeling projections. 

In a response above, we concluded 

that 2007 had meteorology similar to 

normal meteorology. We also examined 

whether the 2008 data indicates a trend 

toward attainment for the area. We 

examined the 2008 preliminary data, 

which is awaiting QA/QC. The 2008 

preliminary data show that the DFW 

area had 4th high values of 85 ppb at 

two monitors and at the other 18 

monitors, the value was 84 ppb or less. 

The 2008 preliminary data indicate the 

2006–2008 DV is 91 ppb (down from 95 

ppb in using 2005–2007 monitoring 

data). For the monitor that has the 

highest average 4th high values in 2007 

and 2008 and is likely to be the 

controlling monitor (or one of the 

highest monitors) for determining if the 

area reaches attainment based on 2007– 

2009 data, the monitor’s DV for the 

2007–2009 period would have to be less 

than 85 ppb. It is important to note that 

this monitor (Denton) had a preliminary 

4th high value in 2008 of 84 ppb. 

Considering the 2008 preliminary data 

with most of the 4th highs of 84 ppb or 

less, and that much of the DFW SIP 

reductions and another year of fleet 

turnover are still to occur, the ambient 

air quality trend strongly supports that 

the DFW monitors will reach attainment 

in 2009. EPA believes that the closer an 

area is to its attainment date, the more 

weight should be given to the actual 

ambient data and the expected 

additional reductions in considering 

whether an area will reach attainment. 

We have considered modeling using 

two emission reduction scenarios 

(Combo 10 and PDMR 2009), 

recognizing that the actual emission 

control level would be somewhere in 

between, and two types of RRF 

calculations. We have also considered 

the impact of additional measures and 

reductions documented in the April 23, 

2008 letter. With these adjustments, the 

modeling is demonstrating significant 

reductions of 7–13 ppb in ozone from 

the base period, but is still slightly short 

of attainment. The modeling predicts 

values greater than 84 ppb at two of the 

nine monitors, but we believe, after 

evaluating additional evidence in a 

WOE analysis, that the area will attain 

by its attainment date. Specifically, we 

considered that the model’s underprediction of high ozone levels may be 

biasing the model predictions, and 

therefore potentially underestimating 

the ozone reduction that could occur 

due to the emission reductions achieved 

by local and regional rules. We 

considered the impact of meteorological 

adjustments to the design value 

projection, which would further 

indicate the future projections may be 

too high. We have recognized emission 

reduction efforts that have not been 

quantified and included in the modeling 

and model-based WOE estimates. We 

also considered and gave significant 

weight to non-modeling evidence of 

recent monitoring and projected NOX

emission changes between 2007 and 

2009. 

We have also considered ambient data 

in 2008 and progress in implementing 

control measures in making our final 

conclusion on the DFW area’s 8-hour 

Ozone SIP’s Attainment Demonstration 

adequacy. For example, we weighed a 

vacatur of the CAIR rules and its 

potential impact on the DFW area. As 

discussed in detail in a response above, 

we concluded that the removal of CAIR 

may result in a change in 8-hour ozone 

modeling values of 0.1–0.3 ppb. We also 

considered that fewer engine controls 

were installed using the early 

compliance incentive money that was 

available. 

We have also considered the progress 

in implementing the TERP program. 

This program has achieved all of the 

reductions that were projected in the 

May 30, 2007 submissions. These 

reductions were included in the 

modeling. In its April 2008 letter, Texas 

indicated that an additional 14.2 tpd of 

emission reductions could be achieved 

through the additional funding made 

available by the legislature. EPA relied 

on this projection as part of our weight 

of evidence evaluation in our proposal. 

As discussed in the response to 

comments on the TERP reductions, 

since our proposal notice, additional 

information has become available on the 

status of TERP projects and the State’s 

progress in meeting its WOE projection 

of 14.2 tpd of NOX emissions reductions 

in 2008 and early 2009. Recently TCEQ 

announced they would be delaying the 

2009 TERP grant application cycle, due 

to Hurricane Ike. Due to this unfortunate 

delay (the grant application cycle 

opened December 1, 2008), FY2009 

grant money will be issued later than 

originally thought. Approval of grants 

will not likely occur by the beginning of 

the DFW ozone season (March 1, 2009), 

but approval of grants should start in 

the May to early June timeframe. While 

this is not by the beginning of the ozone 

season, it is soon enough that reductions 

could start occurring before the core 

ozone season and therefore additional 

reductions can be considered as weight 

of evidence. 

This is confirmed by an examination 

of 2004–2007 and preliminary 2008 

monitoring values for the typical design 

value monitors (north and northwest 

sides of the DFW area) which is 

included in the supplemental TSD. It 

shows that the 1st to 4th high 8-hour 

ozone values (values that are utilized in 

setting the area’s DV) are usually set in 

the June through September timeframe. 

Since the approval of FY2009 grants 

should start before or during the 

beginning of the core ozone period for 

the DFW area, some additional 

reductions can be considered as WOE. 

At this point, it seems unlikely that the 

full 14.2 tpd will be achieved even by 

the core ozone season. To evaluate the 

impact, we assumed that TCEQ would 

achieve approximately 70% of the 

originally projected 14.2 tpd; 

consequently, there might be a loss in 

reductions of approximately 4.2 tpd. See 

the Supplemental TSD. Then in looking 

at the modeling based WOE, the 

increase in projected NOX would yield 

approximately an additional 0.10 to 0.22 

ppb at the monitors with the highest 

FDVs. We have also revised our estimate 

of actual reductions between 2007 and 

2009 to consider this potential loss in 

TERP emission reductions. Rather than 

the 26% we considered at proposal, our 

new estimate is a 25.4% reduction of 

the estimated 2007 emission levels. 

Finally, over half of the previously 

discussed 25.4% reductions of NOX

emissions (between 2007 and 2009) in 

the DFW area are slated to occur 

between the 2008 and 2009 ozone 

seasons. Due to these large local 


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reductions, we expect the 2009 ozone 

levels to be lower than 2008 levels. 

In summary, EPA has considered a 

number of factors. As pointed out by 

commenters, some control strategies, 

notably CAIR and TERP, are likely not 

going to achieve the reductions 

originally expected. As discussed above, 

we considered the impact of these 

factors to be relatively small. We believe 

that at this time, with the attainment 

date only months away, we should give 

considerable weight to the recent air 

quality trends and to expected further 

reductions that will occur before the 

2009 core ozone season. Therefore, 

considering all of the factors discussed 

above with the elements we considered 

in the proposal (available modeling, 

evidence, analyses, and adopted control 

strategies) and the comments we 

received, EPA believes the DFW area 

will reach attainment of the 1997 8-hour 

ozone standard by its attainment date. 

E. Comments on Discrete Emission 

Reduction Credits (DERCs) 

Comment: A commenter states that 

EPA’s conditional approval of the DFW 

attainment demonstration does not 

provide for adequate public review and 

comment on the measures TCEQ has 

committed to implement. The 

commenter is concerned that the public 

will not have the opportunity to review 

and comment on the DERC flow control 

limit. 

Response: Section 110(k)(4) of the Act 

authorizes conditional approval of ‘‘a 

plan revision based on a commitment of 

the State to adopt specific enforceable 

measures by a date certain, but not later 

than 1 year after the date of approval of 

the plan revision.’’ Conditional approval 

is authorized when a SIP contains 

substantive, but not fully satisfactory, 

provisions, and the State commits to 

submit specific enforceable measures to 

cure the deficiencies. We have proposed 

to conditionally approve the DFW 

attainment demonstration conditioned 

on the TCEQ submitting a complete SIP 

revision by March 1, 2009, that includes 

an enforceable mechanism providing a 

3.2 tpd restriction on the amount of 

DERCs available for use in the DFW area 

starting March 1, 2009. If the State 

wishes to use more than 3.2 tpd of 

DERCs in the DFW area after 2009, there 

must be an enforceable mechanism that 

provides for increases above 3.2 tpd 

beginning January 1, 2010 as long as this 

increase is consistent with attainment 

and maintenance of the standard. 

Section 110(a)(2) of the Act and 40 

CFR Part 51 require the State to conduct 

a 30-day public comment period and 

hold a public hearing on a proposed SIP 

revision submittal. Further, the State 

must include in the adopted SIP 

revision submittal a response to all the 

received comments. The TCEQ has 

proceeded with a proposed rulemaking 

and held a public comment period, 

pursuant to the requirements of the Act 

and 40 CFR Part 51, from August 6 

through September 12, 2008, on the 

proposed DERC SIP revision to meet the 

condition. Additionally, the State 

published the proposal in the Texas 

Register and held public hearings on 

September 9, 2008, in Dallas, Texas and 

on September 10, 2008, in Arlington, 

Texas. EPA and others provided 

comments. 

Upon receipt from the TCEQ of a 

complete DERC SIP revision, EPA will 

review it and propose action in the 

Federal Register. In this notice, we will 

provide, as required by the Act, an 

opportunity for a 30-day public 

comment period. 

The public is provided with three 

separate opportunities to review and 

comment on the DERC SIP revision— 

during (1) the comment period for EPA’s 

proposed conditional approval of the 

DFW attainment demonstration; (2) the 

comment period for the State’s proposed 

rulemaking; and (3) the comment period 

for EPA’s proposed action on the DERC 

SIP revision. Thus, EPA finds that there 

are ample opportunities for public 

review and comment on the DERC SIP 

revision. 

Comment: A commenter states that 

EPA’s conditional approval of the DFW 

attainment demonstration relies upon 

the DERC rule; yet EPA has only 

conditionally approved the DERC rule 

into the Texas SIP. The commenter 

states that emission credits subject to 

the DERC rule should not be relied upon 

as part of the attainment demonstration 

SIP until EPA fully approves the DERC 

rule. 

Response: As noted in the previous 

response, the Act authorizes conditional 

approval based on a State’s commitment 

to adopt specific enforceable measures 

by a date certain. If the State fulfills its 

commitment with respect to the DERC 

flow control limit and EPA approves the 

submission, we believe the attainment 

demonstration will include all 

enforceable measures necessary to attain 

by the attainment date. The attainment 

demonstration cannot be fully approved 

until the State submits and EPA 

approves the revision to the DERC rule 

providing for the 3.2 TPD flow control 

limit. In the interim, as provided in the 

Act, the plan may be conditionally 

approved with a commitment to submit 

the necessary DERC rule revision. 

As the commenter notes, the DERC 

rule is already conditionally approved 

(see 71 FR 52703, September 6, 2006). 

In our final conditional approval of the 

DERC rule, we stated that a conditional 

approval is treated as a full approval 

until such time that EPA takes action to 

disapprove the rule. Therefore, it is 

acceptable for TCEQ to continue 

allowing DERCs to be used within the 

DFW nonattainment area. 

Further, the terms of the 2006 DERC 

conditional approval do not directly 

impact the DFW attainment 

demonstration and its DERC flow 

control condition. TCEQ committed to 

making the following revisions to the 

DERC rule in their September 8, 2005, 

commitment letter and to comply with 

these commitments during the 2006 

DERCs conditional approval period: 

1. Revise Title 30 Texas 

Administrative Code (30 TAC) § 101.373 

to prohibit the future generation of 

DERCs from permanent shutdowns and 

to allow DERCs generated and banked 

from permanent shutdowns prior to 

September 30, 2002, to remain available 

for use for no more than five years from 

the date of this letter. 

2. The TCEQ will perform a credit 

audit to remove from the emissions 

bank all DERCs generated from 

permanent shutdowns after September 

30, 2002. Even if the shutdown itself 

occurred before September 30, 2002, no 

DERCs can be generated from that event 

after September 30, 2002. 

3. Revise 30 TAC §§ 101.302(f), 

101.372(f)(7) and 101.372(f)(8) to clarify 

that EPA approval is required for 

individual transactions involving 

emission reductions generated in 

another state or nation, as well as those 

transactions from one nonattainment 

area to another, or from attainment 

counties into nonattainment areas. The 

TCEQ further understands that the EPA 

would require a SIP revision prior to 

approving a transaction between 

another state or nation, as well as those 

transactions between counties not 

located within the same nonattainment 

area. 

4. The TCEQ will revise Form DEC– 

1, Notice of Generation and Generator 

Certification of Discrete Emission 

Credits; Form MDEC–1, Notice of 

Generation and Generator Certification 

of Mobile Discrete Emission Credits; 

and Form DEC–2, Notice of Intent to 

Use Discrete Emission Credits, to 

include a waiver to the federal statute of 

limitations defense for generators, and 

users of DERCs and mobile discrete 

emission reduction credits (MDERCs). 

Please be reminded that there is 

currently no applicable state statute of 

limitations in the State of Texas. In 

addition, the TCEQ will maintain its 

current policy of preserving all records 

relating to DERC and MDERC generation 


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12See also EPA’s ‘‘Guidance on the Reasonably 

Available Control Measures (RACM) Requirement 

and Attainment Demonstration Submissions for 

Ozone Nonattainment Areas,’’ John S. Seitz, 

Director, Office of Air Quality Planning and 

Standards, November 30, 1999. 

and use for a minimum of five years 

after the use strategy has ended. 

5. Revise 30 TAC §§ 101.302 and 

101.372 to clarify that a proposed 

quantification protocol may not be used 

if the TCEQ Executive Director receives 

a letter from the EPA objecting to the 

use of the protocol during the 45-day 

adequacy review period or if the EPA 

proposes disapproval of the protocol in 

the Federal Register. 

6. Revise 30 TAC § 101.306 to specify 

that Emission Reduction Credits may be 

used within the highly reactive volatile 

organic compounds Emissions Cap and 

Trade program as an annual allocation 

of allowances as provided under 30 

TAC § 101.399. 

TCEQ submitted revisions to the 

DERC program on October 24, 2006 to 

address the 2006 condition. EPA is 

currently reviewing this SIP revision 

submittal and will take action at a later 

date and in a separate rulemaking on 

whether TCEQ’s revisions to the DERC 

program adequately satisfied the terms 

of the 2006 DERC conditional approval. 

In the meantime, the DERC program can 

continue to be used in Texas, including 

the DFW area. Conditions 1 and 2 

pertain to DERCs generated through 

permanent shutdowns and provide that 

any shutdown DERCs generated prior to 

September 30, 2002, in the DFW area 

would be available for use until 

September 8, 2010. Projected uses of 

these pre-September 30, 2002 shutdown 

DERCs were appropriately modeled and 

accounted for by TCEQ as part of the 

overall DERC usage projections in DFW. 

Emission reductions subject to 

condition 3 do not impact the DFW 

attainment demonstration since EPA has 

not been contacted about using discrete 

emission reductions in the DFW area 

that have been generated in another 

state, nation, nonattainment area, or 

surrounding attainment counties. 

Conditions 4 and 5 modify the DERC 

rule to align the DERC generation and 

use procedures with EPA’s Economic 

Incentive Program Guidance. These 

conditions do not negatively impact the 

projected uses of DERCs that were 

accounted for in the DFW attainment 

demonstration. Condition 6 only applies 

to DERCs used in the Houston/ 

Galveston/Brazoria ozone 

nonattainment area and is therefore not 

applicable to the DFW attainment 

demonstration. 

As discussed previously, TCEQ 

submitted revisions to the DERC 

program on October 24, 2006 to meet 

the 2006 DERC condition. EPA is 

currently reviewing these revisions to 

the Texas SIP and will take action in a 

separate rulemaking. These revisions, as 

noted above, have no impact upon the 

DFW area’s attainment demonstration 

SIP and its reliance upon DERCs. 

Comment: Commenters believe that 

the DERC usage limitation should be 

required every year rather than allowing 

a different approach after 2009. 

Commenters also believe that the 

enforceable flow control mechanism 

lacks specificity, may be backsliding 

(contrary to the Act’s requirements) and 

may not demonstrate continued 

attainment of the 1997 ozone standard 

in the DFW area. 

Response: Commenters will be able to 

address the substance of the DERC flow 

control SIP revision and its effect on the 

attainment demonstration once it is 

submitted to EPA. Until the State adopts 

and submits this revision to the DERC 

rule, it is premature to speculate about 

what the State might choose to do. 

However, we note that so long as the 

State demonstrates that the adopted rule 

will not interfere with attainment by 

June 2010 and maintenance of the 

NAAQS in the following years, EPA 

cannot mandate that the State apply the 

same approach in subsequent years that 

it chooses to apply in 2009. 

In our proposed conditional approval 

of the DFW attainment demonstration, 

we described the requirements of the 

2009 DERC flow control condition and 

the enforceable mechanism that must 

relate it to the DFW attainment 

demonstration. We specifically 

recognized that the DERC usage 

limitation did not need to be required 

every year after 2009. For all years after 

2009, the TCEQ will have the option to 

retain the 3.2 tpd DERCs usage 

restriction or choose to increase the 

amount of tpd of DERCs usage, as long 

as there is an enforceable and replicable 

mechanism in place to ensure the 

increase in tpd of DERCs usage as offset 

by other measures, continues to ensure 

attainment in the area by having the 

same impact as if the 3.2 tpd DERCs 

usage restriction remained in effect. 

This includes the quantity and spatial 

allocation impacts of increased tpd of 

DERCs usage on the ozone levels. 

Therefore there would be no 

backsliding, even if the amount of tpd 

of DERC usage increased. 

In our proposal, we described a 

specific enforceable mechanism that 

would be acceptable concerning the 

substitution of other measures 

beginning January 1, 2010, allowing 

more than 3.2 tpd of DERCs usage in a 

year. As discussed in our DERC 

response to comments number 1, the 

public will receive three opportunities 

to review and comment on the merits 

and nature of the 2009 DERCs limit and 

the after-2009 enforceable mechanism in 

the DFW area—during (1) the comment 

period for EPA’s proposed conditional 

approval of the DFW attainment 

demonstration, (2) the comment period 

for the State’s proposed rulemaking, and 

(3) the comment period for EPA’s 

proposed action on whether the 

condition has been met. 

EPA believes that with the public 

review and comment opportunities 

provided, as well as the specifications 

outlined in our proposed conditional 

approval rulemaking, there will be 

sufficient opportunities to ensure that 

EPA has received relevant comments 

and information to allow EPA to make 

an informed decision on the 

acceptability and enforceability of the 

TCEQ’s DERCs SIP revision submittal. 

Comment: Commenter states that the 

DERC emission reductions relied on in 

the DFW attainment demonstration are 

inadequate. 

Response: While EPA appreciates the 

effort and time of the commenter, the 

commenter has not provided any 

substantive description of why the 

DERC emission reductions relied on are 

inadequate for attainment. 

F. Comments on Reasonably Available 

Control Measures (RACM) 

Comment: Numerous commenters 

note that the cement plants in the DFW 

area are the largest source of industrial 

NOX emissions in the DFW area. They 

claim there is available technology that 

would reduce NOX emissions by 90% 

and the companies should be required 

to install Selective Catalytic Reduction 

(SCR) as NOX RACM. They also note 

that the cement kilns are a large source 

of VOC emissions in the area but only 

one of ten kilns in Midlothian uses 

modern controls to reduce VOC 

emissions by 90%. Further, they claim 

that all Midlothian kilns should be 

required to install this technology, i.e., 

Regenerative Thermal Oxidizers (RTOs), 

as VOC RACM. Moreover, EPA needs to 

conduct an independent RACM 

analysis. 

Response: EPA interprets the Act’s 

RACM requirement to mean that a 

measure is not RACM if it would not 

advance the attainment date (57 FR 

13498, 13560).12 This interpretation has 

been upheld. See Sierra Club v. EPA, 

294 F.3d 155 (DC Cir. 2002) and Sierra 

Club v. United States EPA, 314 F.3d 735 

(5th Cir. 2002). A state must consider all 

potentially available measures to 

determine whether they are reasonably 

available for implementation in the area, 


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13To determine whether a measure would be 

reasonable to require for implementation, we 

calculated the magnitude of emissions reductions 

that would advance the attainment date at the 

monitors with the highest future design values 

(DVs), which are the Denton and Frisco monitors. 

Of these two monitors, the Denton monitor has the 

higher DV (2005–2007) of 94 ppb, although it 

should be noted that the DV for the DFW area for 

2005–2007 is 95 ppb. However, considering the 

Denton monitor, if implementation of a particular 

measure would result in a decrease of 1 ppb at the 

Denton monitor in 2008, we would consider such 

a measure as having the potential to advance the 

attainment date in the DFW area. 

and whether they would advance the 

area’s attainment date. The state may 

reject measures as not meeting RACM, 

however, if they would not advance the 

attainment date, would cause 

substantial widespread and long-term 

adverse impacts, or would be 

economically or technologically 

infeasible. Additionally, potential 

measures requiring intensive and costly 

implementation efforts are not RACM. 

Sierra Club v. EPA at 162–163 (DC Cir. 

2002); Sierra Club v. EPA, 314 F.3d 735 

(5th Cir. 2002); BCCA Appeal Group v. 

EPA, 355 F.3d 817 (5th Cir. 2003). To 

demonstrate measures that advance 

attainment of the ozone standard, the 

emission reductions from the measures 

must occur no later than the start of the 

2008 ozone season—i.e., by March 1, 

2008, in order to advance attainment. 

Because there are no measures that 

could have been adopted and 

implemented by a date that has now 

passed, we believe it is appropriate to 

conclude that additional measures are 

not RACM. 

EPA expects States to prepare a 

reasoned justification for rejection of 

any available control measure. The 

resulting available control measures 

should then be evaluated for 

reasonableness considering their 

technological and economical 

feasibility, and whether they will 

advance attainment. In the case of the 

DFW SIP, TCEQ performed an analysis 

to determine whether all RACM were 

included in the SIP. 

To evaluate RACM for VOC measures, 

the State looked to all available RACM 

analyses and guidance for all the types 

of source categories in the DFW area 

and their potential controls. The State’s 

analysis included evaluation of the 

potential RACM RTO control 

technology for cement kilns in the DFW 

area as VOC RACM. The State’s 

photochemical modeling, however, 

indicated that the implementation of 

RTO technology on cement kilns in the 

DFW area would not advance 

attainment. The State’s analyses 

indicated that it would take extremely 

large reductions of VOC emissions, over 

100 tpd, to reduce the ozone level at the 

Denton monitor 13 in the DFW area by 

1 ppb. Thus only measures that will 

provide approximately 100 tpd of VOC 

emissions reductions will timely 

advance attainment. We were unable to 

identify any potential RACM measures 

in the State’s submittal that would 

provide 100 tpd or more of VOC 

reductions; this review also examined 

the use of RTO in cement kilns. 

In addition to reviewing the State’s 

submittal, EPA reviewed the State’s 

2005 and 2007 Emissions Inventories for 

Point Sources. This review showed that 

the cement kilns do not emit sufficient 

amounts of VOCs to achieve 100 tpd in 

emissions reductions. See the 

Supplemental TSD for more details. 

Consequently, EPA agrees with the State 

that there are no additional RACM for 

stationary source VOC emissions in the 

DFW area. Based upon this review, EPA 

concludes that the use of RTO on 

cement kilns would not advance timely 

attainment. 

While we agree that one of the sources 

in the cement kiln source category uses 

the RTO technology—TXI #5 (Kiln 5), 

we do not extrapolate from this that use 

of the RTO technology on the other 

cement kilns in the DFW area will 

advance attainment of the 1997 ozone 

standard. See our previous comments 

and the Supplemental TSD for 

additional information. 

To evaluate RACM for NOX measures, 

the TCEQ looked to all available RACM 

analyses and guidance for all the types 

of source categories in the DFW area 

and their potential controls. The State’s 

analysis also included evaluation of 

Low Temperature Oxidation 

Technology (LoTOx), SCR and Selective 

Non-Catalytic Reduction (SNCR) as 

potential NOX RACM for cement kilns. 

The State’s modeling analyses indicate 

that reducing on-road mobile and area/ 

non-road sources of NOX is most 

effective in reducing ozone levels at the 

Denton and Frisco monitors. Our 

evaluation of the State’s analyses found 

that reductions of NOX emissions of at 

least 40 tpd would have the potential to 

advance the attainment date. See pages 

2–29 to 2–30 of the TCEQ SIP Narrative. 

Thus, only measures that will provide 

approximately 40 tpd of NOX emissions 

reductions will timely advance 

attainment. Neither the State nor EPA 

was able to identify any potential RACM 

measures that would provide 40 tpd or 

more in NOX emissions reductions. 

TCEQ had additional sensitivity 

modeling performed for cement kilns, 

which showed that the most stringent 

controls on the kilns would not advance 

the attainment date. See the 

Supplemental TSD for more detail. 

The Fifth Circuit in Sierra Club v. 

EPA, 314 F.3d 735, 745 (5th Cir. 2002) 

impressed upon EPA the duty to (1) 

demonstrate that it has examined 

relevant data, and (2) provide a 

satisfactory explanation for its rejection 

of a proposed RACM and why the 

proposed RACM, individually and in 

combination, would not advance the 

area’s attainment date. See Ober, 243 

F.3d at 1195 (quoting American Lung 

Ass’n v. EPA, 134 F.3d 388, 392–93 (DC 

Cir. 1998)). We reviewed the State’s 

analysis and discussed our evaluation of 

it in the July 2008 TSD and the 

December 2008 Supplemental TSD for 

this rulemaking; both TSDs are in the 

docket for this rulemaking. EPA 

evaluated the State’s analysis and 

explained in the TSDs why we agree 

with the State that no additional 

measures are RACM for the DFW area 

and therefore the RACM requirement of 

the Act is met. We performed an 

independent analysis by reviewing all 

available data to determine whether 

RTO and NOX controls achieving 80– 

90% reduction are RACM for cement 

kilns in the DFW area; we agree with the 

State that additional control measures 

would not advance the attainment date. 

G. Comments on the Failure-To-Attain 

Contingency Measures Plan 

Comment: Some commenters merely 

state that the contingency measures are 

insufficient without providing any 

support. Others comment that the four 

failure-to-attain contingency measures 

are insufficient because they will not 

result in demonstrative, verifiable, and 

enforceable emission reductions. 

Response: Some of the comments 

simply allege that the contingency 

measures are insufficient and the 

commenters provide no support, 

rationale or data for their claim. EPA 

explained why we believe the 

contingency measures are sufficient in 

the proposed rule and the commenters 

have not substantively questioned EPA’s 

rationale. Therefore, no further response 

is necessary. 

Other commenters claim that the 

contingency measures will not result in 

demonstrative, verifiable and 

enforceable emission reductions. EPA 

interpreted sections 172 and 182 of the 

Act in the General Preamble (57 FR 

13498, 13510) to require States with 

moderate or above ozone nonattainment 

areas to include contingency measures 

to implement additional emission 

reductions of 3% of the adjusted base 

year inventory in the year following the 

year in which the failure has been 

identified. The state must specify the 


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14 If an area source is controlled, emissions are 

calculated by the following equation: CAE = UAE 

[1 ¥ (CE) (RP) (RE)], where UAE = Uncontrolled 

Area Emissions estimate, and each of the other 

terms is defined above. 

15EPA approved these three Chapter 115 

measures into the DFW 1-hour ozone SIP as part of 

the failure-to-attain contingency measures plan. 

EPA never triggered them to be implemented upon 

a finding of failure to attain the 1-hour standard. 

They remain in the DFW SIP and now the State is 

relying upon them as part of the 8-hour ozone 

failure-to-attain contingency measures plan. They 

are not required to meet the VOC RACT 

requirement for either standard. 

type of contingency measures and the 

quantity of emissions reductions. 

Quantifiable contingency measures 

are ones that are demonstrative and 

verifiable. An EPA-approved 

methodology can be used to calculate 

projected emissions reductions. The 

three VOC control measures in the 

contingency plan (Offset Lithographic 

Printing; Degassing or Cleaning of 

Stationary, Marine, and Transport 

Vessels; and Petroleum Dry Cleaning) 

rely upon long-established 

methodologies for calculation of their 

projected emissions reductions. See 

EPA’s ‘‘Introduction to Area Source 

Emission Inventory Development’’ 

(Emission Inventory Improvement 

Program (EIIP), Volume III, January 

2001). The EIIP was developed to 

estimate the effect of controls and 

acknowledges that regulatory programs 

are less than 100 percent effective for 

most source categories in most areas of 

the country. Specifically, Chapter 4 of 

the EIIP document describes the 

methodology for calculating an emission 

estimate for an area source with 

regulations in place that affect any of 

the individual sources within the source 

category using three factors: control 

efficiency, rule effectiveness, and rule 

penetration. These factors are used to 

develop more accurate emissions 

estimates and are defined as follows: 

(a) Control efficiency (CE) is the 

emission reduction efficiency, and is a 

percentage value representing the 

amount of a source category’s emissions 

that are controlled. These numbers are 

often obtained from EPA’s Control 

Technique Guidance documents. 

(b) Rule effectiveness (RE) is an 

adjustment to account for failures and 

uncertainties that affect the actual 

performance of the control. A default 

value of 0.80 is recommended unless 

better information is available for a 

particular source category. 

(c) Rule penetration (RP) is the 

percentage of the area source category 

that is covered by the applicable 

regulation or is expected to be 

complying with the regulation. The RP 

is calculated by taking the uncontrolled 

emissions covered by regulation and 

dividing by the total uncontrolled 

emissions. Default values are not 

feasible for RP because it is highly 

category- and location-dependent. 

These three factors are multiplied 

together to estimate the Controlled Area 

source Emissions (CAE).14

For the DFW contingency measures 

plan, Texas estimated emissions for 

each source category using EPA’s EIIP 

methodology. For Offset Lithographic 

Printing, the contingency measures plan 

applies to those sources with emissions 

below 50 tpy; for Degassing or Cleaning 

of Stationary, Marine, and Transport 

Vessels, the plan covers sources which 

are currently exempt from the State’s 

VOC rules for degassing, including 

tanks smaller than 1 million gallons; 

and for Petroleum Dry Cleaning, the 

plan applies to sources using less than 

2,000 gallons of solvent per year. These 

three contingency measures address 

sources that have emissions lower than 

the exemptions in the State’s existing 

VOC RACT rules approved today as 

meeting RACT for both the standards. 

The fourth measure relied on is fleet 

turnover. Fleet turnover occurs each 

year—the model year composition of the 

local motor vehicle fleet changes as new 

vehicles are purchased and enter the 

fleet and old vehicles are scrapped. This 

results in a decrease in fleet average 

NOX and VOC emissions each year as 

older model year vehicles, certified to 

less stringent emission standards, leave 

the fleet and are replaced by newer 

vehicles certified to more stringent 

standards. The emission impacts of fleet 

turnover are calculated using EPA’s 

MOBILE6.2 emission factor model. 

MOBILE6.2 calculates emission factors 

based on the standards that were in 

effect in each of the model years in the 

fleet and the relative fraction of each 

model year expected in the fleet in a 

specific calendar year. The relative 

fraction of each model year in the fleet 

is based on the local age distribution of 

the vehicle fleet, which is a specific 

input in MOBILE6.2 supplied by the 

state or local agency running the model, 

which in this SIP revision is the 

NCTCOG. 

EPA requires that states use 

MOBILE6.2 to estimate motor vehicle 

emissions in a SIP or conformity 

determination. EPA also specifies in 

guidance what types of local inputs are 

appropriate for use in a SIP. For 

example, EPA does not allow a state or 

local agency to project that the motor 

vehicle fleet will be newer in the future 

than it currently is. In SIPs, EPA accepts 

projections of future emissions, 

including the benefits of fleet turnover, 

calculated using MOBILE6.2 using 

inputs that conform to our guidance. 

The NCTCOG used the State vehicle 

registration database from July 2005; 

this conforms to EPA’s guidance, is the 

latest available information and 

provides a more accurate estimation of 

future emissions levels. 

The three VOC measures have been 

approved into the SIP and therefore are 

enforceable by the EPA, the State and 

the public. The fleet turnover measure 

is a Federal rule and as such is 

enforceable by the EPA, the State and 

the public. Today’s action makes the 

fleet turnover measure’s projected SIP 

credits enforceable by the EPA and the 

public. The measures are surplus 

because they are not substitutes for 

mandatory, required emissions 

reductions and they are not being 

counted in any other control strategy.15

Finally, the measures are considered 

permanent because they continue for as 

long as the period in which they are 

used in the failure-to-attain contingency 

measures plan. 

Comment: A commenter states that 

EPA may not approve contingency 

measures into the SIP that are already 

scheduled for implementation and are 

mandatory federal measures. Moreover, 

the attainment demonstration SIP relies 

upon these projected emissions 

reductions from fleet turnover. The 

emissions factors models used for 

projecting the future year’s controlled 

emissions inventory include the 

improved tailpipe emission. The 

emissions reductions will occur 

passively and are not available ‘‘to be 

undertaken’’ in the likely event of a 

failure to attain. Accepting these as 

contingency measures violates the letter 

of the Act and the intended function of 

contingency measures—to step in when 

the SIP’s primary control strategy fails. 

Texas may not rely on tailpipe 

emissions reductions as a contingency 

measure. 

Response: EPA’s position is that the 

Act allows mandatory federal measures 

that are already scheduled for 

implementation to be used as 

contingency measures, as long as their 

emission reductions are beyond those 

needed for attainment or to meet 

reasonable further progress. The 

following are some of EPA’s actions on 

the 1-hour ozone SIPs, approving the 

use of mandatory federal measures as 

part of the contingency measures plan: 

62 FR 15844, (April 3, 1997); 62 FR 

66279, (December 18, 1997); 66 FR 

30811 (June 8, 2001); 66 FR 586 and 66 

FR 634, (January 3, 2001). In the 

preambles for the proposed and final 

Phase 2 Rule, we state that Federal 


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16See Richard D. Wilson, Acting Assistant 

Administrator for Air and Radiation, dated October 

24, 1997, entitled ‘‘Guidance on Incorporating 

Voluntary Mobile Source Emission Reduction 

Programs in State Implementation Plans (SIPs).’’ 

17The state may submit TCMs to EPA under CAA 

176(c)(8). The provision states that TCMs that are 

specified in an approved implementation plan may 

be replaced in the plan with alternate TCMs if the 

substitute measures achieve equivalent or greater 

emissions reductions than the TCM to be replaced. 

The provision also allows new TCMs to be added 

to an approved SIP. In order to substitute TCMs the 

CAA requires that the substitute TCM provide 

equivalent emissions reductions as the TCM that is 

being replaced in the approved SIP. The CAA also 

requires that, if the time for implementing the 

substitute TCM has not passed, the substitute 

measures must be implemented in accordance with 

a schedule that is consistent with the schedule that 

provided for the control measures in the 

implementation plan. Substitute and additional 

TCMs must be accompanied by evidence of 

adequate personnel and funding and authority 

under state/local law to implement, monitor and 

enforce the control measure; the measures must be 

developed in a collaborative process that includes 

participation by representatives of all affected 

jurisdictions, state agency and state/local 

transportation agencies and consultation with the 

EPA; there must be reasonable public notice and 

opportunity to comment; and the metropolitan 

planning organization, State air pollution control 

agency and the EPA concur with the equivalency 

of the substitute TCMs and on the additional TCM. 

Concurrence by the above agencies is required by 

the CAA and once the substitute is adopted, the 

TCM becomes, by operation of law, a part of the SIP 

Continued 

measures that result in additional 

emission reductions beyond those 

needed for attainment or ROP in an area 

could serve as contingency measures for 

a failure to attain or meet the ROP 

requirements. (See Phase 2 Rule, 

proposed in 68 FR 32802 at 32837 (June 

2, 2003), and final in 70 FR 71612 at 

71651 (November 29, 2005)). Therefore, 

the State’s inclusion of the Federal 

Motor Vehicle Control programs 

(FMVCP) occurring after the 2009 ozone 

season, is acceptable. 

The Federal measure in the failure-toattain contingency measures plan is the 

projected emissions reductions from the 

FMVCP occurring after the 2009 ozone 

season, in addition to the alreadyidentified VOC rules described above. 

The FMVCP requires controls on both 

on- and non-road motor vehicles, 

providing emissions reductions as the 

fleet is replaced with newer vehicles 

(turns over). Only the emissions 

reductions projected to occur after 2009 

from the FMVCP are relied upon to meet 

the 3% of the emissions in the adjusted 

1999 base year emissions inventory. 

The modeling relies upon emissions 

reductions from the FMVCP that will 

become effective during the modeling 

period from 1999 to 2009. EPA disagrees 

that the attainment demonstration SIP 

relies upon the projected emissions 

reductions from fleet turnover occurring 

after 2009. Said another way, we 

disagree that the reductions from fleet 

turnover used as contingency measures 

were relied upon in the demonstration 

that the area would attain by 2009. 

H. Comments on the Attainment Motor 

Vehicle Emission Budgets (MVEBs) 

Comment: Commenters state that the 

MVEBs are flawed and are flawed for 

multiple reasons. In addition, in the 

absence of a competent attainment 

demonstration, the MVEBs are not 

approvable or adequate. 

Response: EPA disagrees with the 

commenters that the MVEBs are flawed. 

The Commenters provided no data or 

rationale for their comments. This 

statement, without any further 

explanation does not give EPA any 

guidance on the alleged inadequacy nor 

how the commenter would have EPA 

improve upon it. EPA, however, refers 

the Commenters to our detailed 

response, below. 

As discussed elsewhere, we believe 

that the plan provides for attainment of 

the ozone standard. For further 

explanation of how the attainment 

demonstration SIP provides for 

attainment, please see our responses in 

Section V–D above. Furthermore, we 

believe the budgets in the plan are 

consistent with the attainment plan and 

therefore should be approved. 

Further, the budgets in the SIP were 

established consistent with the process 

in 40 CFR 93.118(e). Under 40 CFR 

93.118, budgets cannot be used for 

conformity until EPA has either found 

the budgets ‘‘adequate’’ or approved the 

SIP in which they are contained. On 

June 28, 2007, the availability of the 

budgets was posted on EPA’s Web site 

for public comment. The comment 

period closed on July 30, 2007, and we 

received no comments. On March 21, 

2008, we published a Notice of 

Adequacy Determination for the 

attainment MVEBs (73 FR 15152) where 

we announced that we found the 2009 

attainment MVEBs ‘‘adequate.’’ In that 

notice we stated that the attainment 

MVEBs must be used in future DFW 

transportation conformity 

determinations. 

I. Voluntary Mobile Source Emission 

Reduction Programs (VMEP) 

Comment: Commenters state that the 

Transportation Emission Reduction 

Measure (TERM) projects are 

inadequate. 

Response: The comment letter 

provides no support, rationale or data 

for its claim that the TERM projects are 

inadequate. EPA explained its rationale 

for proposing approval of the VMEP 

program in the proposed rule and the 

commenter fails to identify any defect in 

EPA’s analysis. Therefore, no further 

response is required. 

Comment: A commenter states that 

EPA proposes to accept a series of 

capacity-increasing traffic projects as 

substitute control measures in the event 

that the VMEP NOX emissions are not 

achieved. The commenter states that the 

proposed TERMs involve roadway and 

highway capacity expansion to allow 

higher vehicle speeds in congested 

areas. The commenter further states that 

higher vehicle speeds result in 

increased NOX emissions and are 

counter productive to the stated purpose 

of supplying emissions reductions when 

VMEP reductions fail, and EPA should 

reject the TERM control measures’ 

inclusion into the SIP. 

Response: EPA finds that the State, 

through the North Central Texas 

Council of Governments (NCTCOG), has 

committed to and is responsible for 

emissions reductions measures that are 

permanent, quantifiable, surplus, 

adequately supported, consistent, 

enforceable and in accordance with the 

Act and EPA guidance. The state, 

through the NCTCOG, also commits to 

monitor, assess, report, and, in the event 

that the NOX reductions are not 

achieved, remedy any shortfall in 

emissions reductions. 

It should be noted that EPA is not 

approving any TERMs, which would 

serve as the remedy to a shortfall of the 

VMEP at this time. The types of TERMs 

the state may use in the case of a 

shortfall are traffic signal improvements, 

Intelligent Transportation Systems 

(ITS), and/or freeway and/or arterial 

bottleneck removal. Because the State 

did not specifically identify or commit 

to using these additional measures, we 

did not review them for approvability. 

In the event of a shortfall, EPA will 

review the additional measures 

provided by the State for inclusion into 

the SIP. If EPA finds, at that time, that 

the measures would cause an increase 

in NOX emissions, we would not find 

them suitable for use to make up for an 

emissions reduction shortfall. 

Finally, the State must account for 

any such shortfall either by modifying 

implementation of the existing program 

to address the shortfall, adopting new 

measures, or revising the VMEP’s 

emissions credits to reflect actual 

emissions reductions achieved, 

provided overall SIP commitments are 

met.16 Additions to the VMEP and 

changes to the VMEP credit in an effort 

to remedy any shortfall would be made 

in the form of a SIP revision. If TCMs 

are used to remedy the shortfall, a SIP 

revision may not be necessary.17


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and federally enforceable. It should be noted that 

consultation with the EPA regional offices serves to 

fulfill the requirement for consultation with the 

EPA Administrator and concurrence on both TCM 

substitutions and additions has been delegated to 

the EPA Regional Administrators. (Delegation of 

Authority 7–158: Transportation Control Measure 

Substitutions and Additions). 

VI. Final Action 

EPA is conditionally approving the 

DFW 1997 8-hour ozone attainment 

demonstration SIP and its 2009 

attainment MVEBs, RACM 

determination, and failure-to-attain 

contingency measures plan, submitted 

by the State of Texas on May 30, 2007 

and November 7, 2008, as supplemented 

on April 23, 2008. EPA is fully 

approving two local control measures 

relied upon in the attainment 

demonstration, the VMEP and TCMs. 

We are also fully approving the DFW 

area SIP as meeting the RACT 

requirement for VOCs for the 1-hour 

ozone standard and the 1997 8-hour 

ozone standard. These revisions meet 

the requirements of the Act and EPA’s 

regulations, and are consistent with 

EPA’s guidance and policy. We are 

taking this action pursuant to section 

110 and part D of the Act and EPA’s 

regulations. 

VII. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

Federal regulations. 42 U.S.C. 7410(k); 

40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, EPA’s role is to approve 

state choices, provided that they meet 

the criteria of the Clean Air Act. 

Accordingly, this action merely 

approves state law as meeting Federal 

requirements and does not impose 

additional requirements beyond those 

imposed by state law. For that reason, 

this action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Order 12866 (58 FR 51735, 

October 4, 1993); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this rule does not have 

tribal implications as specified by 

Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the state, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this action and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by March 16, 2009. 

Filing a petition for reconsideration by 

the Administrator of this final rule does 

not affect the finality of this action for 

the purposes of judicial review nor does 

it extend the time within which a 

petition for judicial review may be filed, 

and shall not postpone the effectiveness 

of such rule or action. This action may 

not be challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2).) 

List of Subjects 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Nitrogen dioxides, Ozone, Reporting 

and recordkeeping requirements, 

Volatile organic compounds. 

Authority: 42 U.S.C. 7401 et seq. 

Dated: December 17, 2008. 

Richard E. Greene, 

Regional Administrator, Region 6. 

■ 40 CFR part 52 is amended as follows: 

PART 52—[AMENDED] 

■ 1. The authority citation for part 52 

continues to read as follows: 

Subpart SS—Texas 

■ 2. In Section 52.2270, the second table 

in paragraph (e) entitled ‘‘EPA 

Approved Nonregulatory Provisions and 

Quasi-Regulatory Measures in the Texas 

SIP’’ is amended by adding four new 

entries at the end. 

The revisions and additions read as 

follows: 

§ 52.2270 Identification of plan. 

* * * * * 

(e) * * * 

* * * * * 


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EPA APPROVED NONREGULATORY PROVISIONS AND QUASI-REGULATORY MEASURES IN THE TEXAS SIP 

Name of SIP 

provision 

Applicable 

geographic or 

nonattainment area 

State submittal/ 

effective date EPA approval date Comments 

* * * * * * * 

Dallas-Fort Worth 1997 8-hour 

ozone Attainment Demonstration SIP and its 2009 attainment MVEBs, RACM demonstration, and Failure-to-Attain 

Contingency Measures Plan.

Collin, Dallas, Denton, Ellis, 

Johnson, Kaufman, Parker, 

Rockwall and Tarrant Counties, 

TX.

May 23, 2007, November 7, 2008.January 14, 2009 [Insert FR page number where document begins].Conditional Approval. 

Transportation Control Measures Collin, Dallas, Denton, Ellis, 

Johnson, Kaufman, Parker, 

Rockwall and Tarrant Counties, 

TX.

May 23, 2007 ............. January 14, 2009 [Insert FR page number where document begins].

VMEP ........................................... Collin, Dallas, Denton, Ellis, 

Johnson, Kaufman, Parker, 

Rockwall and Tarrant Counties, 

TX.

May 23, 2007 ............. January 14, 2009 [Insert FR page number where document begins].

VOC RACT finding for the 1-hour 

ozone NAAQS and the 1997 8- 

hour ozone NAAQS.

Collin, Dallas, Denton, Ellis, 

Johnson, Kaufman, Parker, 

Rockwall and Tarrant Counties, 

TX.

May 23, 2007 ............. January 14, 2009 [Insert FR page number where document begins].

[FR Doc. E9–118 Filed 1–13–09; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R06–OAR–2007–1147; FRL–8758–8] 

Approval and Promulgation of 

Implementation Plans; Texas; Control 

of Emissions of Nitrogen Oxides (NOX) 

From Cement Kilns 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The EPA is finalizing 

approval of revisions to the Texas State 

Implementation Plan (SIP). We are 

approving the rules in 30 TAC Chapter 

117 that the State submitted on May 30, 

2007, concerning control of emissions of 

NOX from cement kilns operating in 

Bexar, Comal, Ellis, Hays, and 

McLennan Counties. We are approving 

the nonsubstantive renumbering of the 

rules for all five counties. We also are 

approving the substantive changes to 

the rules for Ellis County, based on a 

determination that the rules for Ellis 

County meet the NOX Reasonably 

Available Control Technology (RACT) 

requirements for cement kilns operating 

in the Dallas Fort Worth (D/FW) 1997 8- 

hour ozone nonattainment area. We are 

taking this action under section 110 and 

part D of the Federal Clean Air Act (the 

Act, or CAA). 

DATES: This rule will be effective on 

February 13, 2009. 

ADDRESSES: The EPA has established a 

docket for this action under Docket ID 

No. EPA–R06–OAR–2007–0523. All 

documents in the docket are listed on 

the www.regulations.gov Web site. 

Although listed in the index, some 

information is not publicly available, 

e.g., Confidential Business Information 

or other information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

is not placed on the Internet and will be 

publicly available only in hard copy 

form. Publicly available docket 

materials are available either 

electronically through 

www.regulations.gov or in hard copy at 

the Air Planning Section (6PD–L), 

Environmental Protection Agency, 1445 

Ross Avenue, Suite 700, Dallas, Texas 

75202–2733. The file will be made 

available by appointment for public 

inspection in the Region 6 FOIA Review 

Room between the hours of 8:30 a.m. 

and 4:30 p.m. weekdays except for legal 

holidays. Contact the person listed in 

the FOR FURTHER INFORMATION CONTACT

paragraph below to make an 

appointment. If possible, please make 

the appointment at least two working 

days in advance of your visit. There will 

be a 15 cent per page fee for making 

photocopies of documents. On the day 

of the visit, please check in at the EPA 

Region 6 reception area at 1445 Ross 

Avenue, Suite 700, Dallas, Texas. 

FOR FURTHER INFORMATION CONTACT: Mr. 

Alan Shar, Air Planning Section (6PD– 

L), Environmental Protection Agency, 

Region 6, 1445 Ross Avenue, Suite 700, 

Dallas, Texas 75202–2733, telephone 

(214) 665–6691, fax (214) 665–7263, email address shar.alan@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document ‘‘we,’’ ‘‘us,’’ 

and ‘‘our’’ refer to EPA. 

Table of Contents 

I. Background 

A. What are we approving? 

B. Who submitted written comments to us? 

C. How are we responding to those written 

comments? 

D. What sections of the May 30, 2007 

submittal will become part of Texas SIP? 

E. What sections of the May 30, 2007 

submittal will not become a part of 

Texas SIP? 

F. What Texas Counties will this 

rulemaking affect? 

G. What are the NOX control emissions 

requirements that we approved for Texas 

under the 1-hour ozone SIP? 

H. What are the NOX control emissions 

requirements that we are approving for 

Texas under the 8-hour ozone SIP? 

I. What are the compliance schedules for 

NOX emissions from cement kilns that 

we are approving? 

II. Final Action 

III. Statutory and Executive Order Reviews 

I. Background 

A. What are we approving? 

The EPA approved 30 TAC, Chapter 

117, NOX cement kilns rules at 69 FR 

15681 published on March 26, 2004, as 

NOX control emissions requirements for 

Texas under the 1-hour ozone SIP. On 

May 30, 2007, TCEQ submitted rule 

revisions to 30 TAC, Chapter 117, 

‘‘Control of Air Pollution from Nitrogen 

Compounds,’’ as a revision to the Texas 

SIP. On July 11, 2008 (73 FR 39911), we 

proposed approval of the May 30, 2007 


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