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Citation: 66 Fed. Reg. 57160 2001

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### 57160 Federal Register/Vol. 66, No. 220/Wednesday, November 14, 2001/Rules and Regulations

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Part 52

[TX-126-1-7477; FRL-7092-2]
Approval and Promulgation of Implementation Plans; Texas; Houston/Galveston Nonattainment Area; Ozone
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.

SUMMARY: The EPA is fully approving the Texas one-hour ozone attainment demonstration State Implementation Plan (SIP) for the Houston/Galveston (HG)severe nonattainment area with an attainment date ofNovember 15, 2007. Also, being published in today's Federal Register are seven additional actions, approving various measures that support the attainment demonstration.

In this action, the EPA is approving the following related SIP elements: The following local measures relied on in the attainment demonstration: speed limit reduction, voluntary mobile emission programs (VMEP) and transportation control measures (TCM); the Post 1999 Rate ofProgress (ROP) plans for the time periods November 15, 1999 toNovember 15, 2002, November 15, 2002 to November 15, 2005 and November 15, 2005 toNovember 15, 2007; the Motor Vehicle Emissions Budget (MVEB) contained in the attainment demonstration SIP and the Post 1999 ROP plans; the 15% ROP Plan (Conversion ofconditional interim approval to a full approval); certain enforceable commitments to adopt additional measures andperform additional analyses; revisions to the 1990base year inventory; and the HG area's SIP as meeting the reasonably available control measures (RACM) requirement.
DATES: This final rule iseffective on December 14, 2001. ADDRESSES: Copies ofdocuments relevant to this action are available for public inspection during normal business hours at the Environmental Protection Agency, Region 6, Air Planning Section (6PD-L), 1445 Ross Avenue, Dallas, Texas 75202-2733; and, the Texas Natural Resource Conservation Commission, Office ofAir Quality, 12124 Park 35 Circle, Austin, Texas 78753.
FOR FURTHER INFORMATION CONTACT: Guy R. Donaldson, Air Planning Section (6PD-L), 1445 Ross Avenue, Dallas, Texas 75202-2733. Telephone Number (214) 665-7242, E-mail Address: Donaldson.Guy@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document "we," "us," and "our" means EPA.
Table ofContents
I.Final Action

A. What Elements ofthe Texas SIPAre We

Approving? B.What are the MotorVehicle Emissions

Budgets beingApproved in this Action? C.What Are the Key SIP Submissions

Being Approved inthis Action? D.WhatPrevious Action hasEPA Taken? E. What Changes Have Been Made in

Response to Comment on the EPAand TNRCC Parallel Proposals? II.What SIPElements DidWe Need toTake Final Action onBefore We Could Approve theAttainment Demonstration? III. Comments

A. What Comments Were Received? i. Whatcomments Were Received on the

December 1999 Proposed Approval/ Proposed Disapproval? ii. What Comments Were Received on the

July 28, 2000 Supplemental Proposal Concerning MVEBs? iii. What Comments Were Received onthe

July 12, 2001 Proposed Approval? B.Response to Comments on Attainment

Demonstration 1.General Comments 2.Comments onPhotochemical Modeling

a. Model Performance b. Model Inputs

c.Weight ofEvidence Analysis 3. Comments onControl Strategies 4. Comments onEnforceable Commitments 5.Comments onMotor Vehicle Emissions

Budgets

a. Comments on July 12, 2001 Proposal b. Comments onJuly 28, 2000

Supplemental Notice Proposal 6.Comments onRACM

a. Comments on December 16, 1999

Proposal b. Comments onJuly 12, 2001 Proposal C.Response to Comments on Local

Measures 1.Comments on SpeedLimits 2.Comments onVIEP 3.Comments onTCMs D.Responseto Comments on Post 1999

Rate ofProgress Plans E. Response to Comments on

Administrative Record IV. Administrative Requirements

I. Final Action

A. WhatElements ofthe TexasSIPAre We Approving?

We are fully approving the one-hour

ozone attainment demonstration SIP for the HG nonattainment area as meeting the attainment demonstration requirements of182(c)(2) and (d) ofthe Clean Air Act (the Act). We proposed this action onJuly 12, 2001 (66 FR 36655). This demonstration shows, through photochemical modeling and other evidence, that through a combination of adopted measures, recentlegislation, and commitments to adopt additional measures the HG area will attain the one-hour ozone standard by November 15, 2007.

As an integral part ofthe attainment demonstration, we are approving and finding adequate the associated MVEBs onlyuntil these emission budgets have been revised pursuant to the State's enforceable commitments to use MOBILE6 and to adopt additional

measures necessary for attainment and

we have found the revised budgets adequate for the purposes of transportation conformity.

Before approving an attainment demonstration SIP, we must approve all ofthe control measures relied on in the demonstration. The majority ofthe control measures relied on in the attainment demonstration have been approved in other Federal Register notices. (See Section II for a listing of related Federal Register notices.) We are approving in today's action, certain

measures relied upon in the attainment demonstration and which were submitted December 20, 2000: the Speed Limit Reductions, the VMEP, and the TCMs. We are also approving the following related SIP elements:

* 15% ROP Plan, * The Post 1999 ROP Plans and their associated contingency measures;

* Ademonstration thatall RACM havebeen adopted forthe HG nonattainment area; and

* Revisions to the 1990 Base Year Inventory.

The revisions to the Post 1999 ROP plans and the RACM analysis that we

are approving today were parallel processed. (See Section I.E. for a discussion ofparallel processing.)

In addition, we believe that for the HG

area to be successful in attaining the one-hour ozone standard, the State must be committed to certain future actions relating to adopting additional measures and to future evaluations ofthe inputs
to the plan. To that end, Texas has included the following enforceable commitments intheir State Implementation Plan which we are approving:

* The State's enforceable commitment to perform a mid-course review (including evaluation ofall modeling, inventory data, and other tools and assumptions used to develop this attainment demonstration) and to submit a mid-course review SIP revision, with any recommended midcourse corrective actions, to the EPAby May 1, 2004.

* The State's enforceable commitment to perform new mobile

source modeling for the HG area, using

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### Federal Register/Vol. 66, No. 220/Wednesday, November 14, 2001/Rules and Regulations 57161

MOBILE6, our on-road mobile emissions factor computer model, within 24 months ofthe model's official release; that ifa transportation conformity analysis is to be performed between 12 months and 24 months after the MOBILE6 official release, transportation conformity will not be determined until Texas submits an MVEB which is developed using MOBILE6 and which we find adequate.

* An enforceable commitment to adoptrules that achieve at least the additional 56 tons/day ofNOx emission reductions thatare needed for the area to show attainment ofthe one-hour

ozone standard and as supported by identified measures that could potentially be adopted and could achieve the reductions without requiring additional limits on highway construction.

* An enforceable commitment to adopt and submitthe EPAby December 1, 2002 measures to achieve 25% ofthe 56 tons/day.

* An enforceable commitment to adopt and submitto EPAby May 1, 2004 measures for theremaining needed additional NOx reductions.

* An enforceable commitment that the rules needed for the additional NOx reductions willbe adopted as expeditiously as practicable and the compliance dates willbe expeditious.

* An enforceable commitment to concurrently revise the MVEBs and submitthem to EPA as a revision tothe attainment SIP ifadditional control

measures reduce the motor vehicle emissions budget (MVEB).

This action also satisfies the last two elements of section 182(d)(1)(A) ofthe Act to adopt TCMs as necessary to comply with the reasonable further
progress and attainment demonstration requirements ofthe Act. The first requirement to offset growth in emissions from growth in vehicle miles traveled (VMT) or number ofvehicle trips is addressed in a corresponding action published separately in today's Federal Register. Please see Section III.C.3 for additional discussion regarding the second and third elements. For additional discussion regarding the first element, see the corresponding separate action in today's Federal Register regarding the VMT Offset Plan.

For more discussion on therationale for the actions being approved here, see the proposed approvals with their associated Technical Support Documents (TSD) and ourresponse to comments found in Section II. B. WhatAre theMotorVehicle EmissionsBudgetsBeingApprovedin ThisAction?

Rate ofProgress Budgets

The MVEBs established bythe Post 1999 Rate ofProgress plans and thatwe

are approving today are contained in Table 1. We find the MVEBs consistent with all ROP SIP requirements. In addition, we are finding these budgets adequate for transportation conformity
purposes pursuant to the criteria in 40 CFR 93.118(e)(4) as part ofour action on the SIP rather than using the web posting process because we have moved forward onthis SIP in a quick manner

as described in GuidanceonMotor Vehicle EmissionsBudgets in One-Hour OzoneAttainmentDemonstrations dated November 3, 1999.

TABLE 1.- ROP SIP MOTOR VEHICLE EMISSIONS BUDGETS [Tons per day]

Pollutant 2002 2005 2007

VOC

................ 100.07 68.52 79.51 NOx

................ 260.85 185.48 156.6

The new 2007 budgets are taken from the attainment demonstration modeling rather than directly from the ROP calculations. Emissions estimates used
to demonstrate transportation conformity will be derived using the assumptions used to develop these emissions budgets for the 2007 attainment SIP MVEBs, pursuant to40 CFR 93.122(a)(6). We find such MVEBs consistent with ROP.

Attainment Budgets

Table 2 contains the MVEBs established by the attainment plan. We

are approving these budgets today and finding them adequate for transportation conformity purposes pursuant to the criteria in 40 CFR 93.118(e)(4) as limited below.

TABLE 2.-2007 ATTAINMENT YEAR MOTOR VEHICLE EMISSIONS BUDGETS [Tons per day]

Pollutant 2007

V

OC

.............................................. 7 9.51 N

O

x .............................................. 156.6 0

We find the MVEBs consistent with allpertinent SIP requirements and, as described in ourproposals, the MVEBs

are approved and adequate for conformity purposes onlyuntil these emission budgets have been revised pursuant tothe State's enforceable commitments to use MOBILE6 andto adopt additional measures necessary for attainment and we have found the revised budgets adequate for the
purposes oftransportation conformity.

All States whose attainment demonstration includes the effects of EPA'sTier II/Low Sulfur program have committed to revise and resubmit their budgets after EPAreleases MOBILE6.(MOBILE6 is the latest version ofthe EPA model for estimating mobile emissions. Its official release is expected in the near future.) The State committed inits April 2000 submission
to perform new mobile source modeling for the HG area using MOBILE6 within 24 months ofthe model's official release. Iftransportation conformity analysis is tobe performed between 12 and 24 months ofthe official release of MOBILE6, transportation conformity will notbe determined until the State submits a newbudget which is developed using MOBILE6 and which

we find adequate. The State has informed the transportation agencies of this commitment. Texas also commits to concurrently revise the MVEB if adoption of any shortfall measure affects the MVEB and submit the revision to EPA as a revision to the attainment SIP.

We are limiting the duration ofour approval as described above because we

are only approving the attainment demonstrations and MVEBs because the States have committed to revise them. Therefore, once we have confirmed that revised budgets are adequate, they will be more appropriate thanthe budgets

we are approving today.

C. WhatAre theKey SIPSubmissions BeingApprovedin ThisAction?

There have been a number ofState submissions in response to the attainment demonstration requirements ofthe Act. In this notice, the key State submissions being considered were providedby the Governor inletters dated December 20, 2000, and October 4, 2001. The items in the October4, 2001 submission havebeen parallel processed.Parallel processing means thatEPAproposes action on a state rule before it becomes final under state law. Our July 12, 2001 proposal details the history of State andEPA actions that preceded these submissions (66 FR 36655).

D. WhatPrevious Actions HasEPA Taken?

There are three proposals related to this action. First, on December 16, 1999 (64 FR 70548), we issued aproposed approval/proposed disapproval ofthe HG ozone attainment demonstration plan (the 1998 plan). This action outlined the actions we believed were

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necessary for the State to develop a fully approvable plan. Second, onJuly 28, 2000 (65 FR 46383), we issued a notice ofproposed rulemaking regarding how the adequacy of attainment MVEBs would be handled for the one-hour

ozone nonattainment areas. Finally, on July 12, 2001 (66 FR 36655), we proposed approval ofthe HG ozone attainment demonstration plan (the December 2000 plan as proposed tobe revised bythe State and finally adopted and submitted in a letter dated October 4, 2001) and several related actions. In today's notice, we have addressed all of the comments received onthe three proposals.

E.What ChangesHaveBeen Madein Response to CommentonEPA and TNRCCParallel Proposals?

In aletter dated June 15, 2001, the Governor ofTexas submitted several items for parallel processing. These items were: certain commitments; recent legislative changes with their impacts

on andrevisions to the proposed control strategy for the HG area; the corrections and modifications tothe Post 1999 ROP plans; a demonstration that all RACM have been adopted for the HG nonattainment area; and amodification
to the attainment demonstration and MVEB to revise the emission projection for Heavy Duty Diesel vehicles.

Under parallel processing, EPA takes final action on itsproposal ifthe final, adopted state submission is substantially unchanged from the submission on which the proposed rulemaking was based, or ifsignificant changes in the final submission are anticipated and adequately described in EPA's proposed rulemaking or result from needed corrections determined by the State to be necessary through review ofissues described in EPA's proposed rulemaking. Several minor changes were made by the State in response to comment.
Enforceable Commitments

Texas made the following changes to the language oftheir enforceable commitments. Italicized text has been added.

The commission commits to adopt

measures necessary to achieve atleast 56 tpd ofNOx emission reductions in the HGA area aboveandbeyondthose reductionsalreadyidentifiedbythe controlmeasureslistedin Chapter6, Table 6.1-2.

To demonstrate progress towards the 56tpdthat commitment, the commission intends to evaluate the following measures andto adopt,by November 2002, sufficient measures in order to achieve atleast 25% ofthe estimated 56 tpd needed.

TNRCC also in response to comments

nowlists all ofthe enforceable commitments for the HG area in a single location inChapter 7.

We agree thatthese changes arenot significant in that they clarifythe intent ofthe enforceable commitments and therefore, remain approvable. No further notice is necessary since these changes do not substantively change the State's proposal. Changes to the Rate ofProgress Plan

TNRCC also revised the tables in the Post 1999 Rate ofProgress Plans in
response to EPA comments thatthe Tables did not reflect therevised implementation schedules for the point

source NOxrules. This issue was discussed in our proposed approval which was based on conservative estimates ofthe emission reductions. The revised tables in the October 4, 2001 SIP reflect the new implementation schedule. No further notice is required since the State made changes as discussed byEPA in the proposal notice. The following summary table isbased onthe revised estimates.

TABLE 1.- NOx RATE OF PROGRESS

M

ilestone Year

............................... 2002

.............................................. 2005

.............................................. 2007

. T

arget Level

................................... 1127.08

......................................... 1011.33

....................... ........ 935.67. Projected emissions after controls 1115.76

......................................... 630.05

........................................... 444.04. Measures

....................................... Tier I NLEV RFG I/M Small En- Tier 1/11 I/M HDDV Standards

....... Tier 1/11 HDDV Standards gine HDDV Standards. NOx Point Source controls

........... NOx Point Source controls.

II. What SIPElements DidWe Need To Take FinalAction on Before We Could Approve the Attainment Demonstration?

In ourproposed action onJuly 13, 2001, we explained that we could not finalize approval ofthe attainment demonstration for the HG area until we finalize approval ofseveral related actions. These actions are listed below along with the status oftheir final approval.

1.Vehicle I/M program (30 TAC 114). Final approval published separately in this issue ofthe Federal Register.
2.Revised emission specifications in the HG area for NOx Point Sources (30 TAC 117). Final approval published separately in this issue ofthe Federal Register.
3.NOx Cap and Trade program (30 TAC 101). Final approval published separately in this issue ofthe Federal Register. 4. Low emission diesel fuel (30 TAC 114). Final approval published separately in this issue ofthe Federal Register. 5.Non-Road Large Spark-Ignition (LSI)Engines (30 TAC Chapter 114). Final approval published separately in this issue ofthe Federal Register. 6. Agreed Orders with Continental and Southwest Airlines andthe City of Houston. Final approval published separately in this issue ofthe Federal Register.

7.Reasonably Available Control Technology (RACT) rules regulating VOCs from Batch Processes (30 TAC 115) and Offset Lithographers (30 TAC 115). Direct final action was published July 16, 2001 (66 FR 36913). No
comments were received andthis action became effective September 14, 2001. 8. A determination thatthe HG SIP includes allReasonably Available Control Measures. Final approval in this action. 9. The 15% ROP Plan. Final approval in this action.

10. The Post 1999 ROPPlans and contingency measures. Final approval in this action.

11. The revisions tothe 1990 base
year inventory. Final approval in this action.

12. The speed limit reductions, the VMEP and the TCMs. Final approval in this action.

13. Lawn service equipment operating restrictions (30 TAG 114.452-459). Final approval published separately in this issue ofthe Federal Register.

14. Vehicle Miles Traveled (VMT) Offset Plan submitted August 25, 1997 and with minor, non-substantive revisions submitted on May 17, 2001. Final approval published separately in this issue ofthe Federal Register for the first element of 182(d)(1)(A). The last
two elements of 182(d)(1)(A) are satisfiedby this action.

15. Motor Vehicle Idling Limitations (30 TAG 114.500-509). Final approval

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published separately in this issue of the Federal Register. 16. Stationary Diesel Generator rule (30 TAC 117.206). Final approval published separately in this issue of the Federal Register. 17. The Post 1996 ROP Plan and contingency measures. Direct final action was published April 25, 2000, 66 FR 20746. No comments were received andthis rule became effective June 26, 2000.

III. Comments

A. What Comments WereReceived?

i. What Comments Were Received on the December 1999 Proposed Approval/ Proposed Disapproval?

The following comment letters were received on the December 1999 proposal: (1)February 14, 2000 letter from Robert E. Yuhnke, Attorney for Environmental Defense. (2)February 14, 2000 letter from Jeffrey Saitas, Executive Director TNRCC. (3)July 31, 2000 letter from James 0. Bartholomew, ELM Packaging.

ii. What Comments Were Received on the July 28, 2000 Supplemental Proposal Concerning MVEBs?

The following comment letter was received on this supplemental proposal. (1)August 28, 2000 letter from Environmental Defense.

iii. What Comments Were Received on the July 12, 2001 Proposal?

We received the following 13
comment letters on the July 12, 2001 proposal. (1)Letter from D. Marrach, M.D. dated July 2, 2001. (2)August 10, 2001 letter from Patrick Gallagher, Sierra Club. (3)August 13, 2001 letter from John Wilson andFrank Blake, the GalvestonHouston Association ofSmog Prevention (GHASP). (4)August 13, 2001 letter from B.C. Carmine, Reliant Energy. (5)August 13, 2001 letter from Ramon Alvarez, PhD, Environmental Defense. (6) August 8, 2001 letter from Jack Steele, Houston Galveston Area Council.

(7)August 13, 2001 letter from Nelly Rocha, Baker and Botts for the Business Coalition for Clean Air Appeal Group. (8) August 10, 2001 letter from Albert Axe, Jr., Jenkens &Gilcrest for TXI Operations.

(9) August 13, 2001 letter from John R. Evans, Lyondell. (10) August 13, 2001 letter from T. Hefgott, Enterprise Products. (11) August 3, 2001 letter from Howard Runser, private citizen. (12) August 8, 2001 letter from Brant Mannchen, Houston Regional Group of the Sierra Club. (13) August 13, 2001 letter from John D. Walke, Senior Attorney, NRDC.

No comments were received on the proposed approval ofthe 15% ROP plan

orthe proposed approval ofrevisions to the 1990 Base Year Inventory. These actions are being approved with out further discussion.

B. Responseto Commentson AttainmentDemonstration

1.General Comments

Comment:Several commenters urged EPA to disapprove the attainment plan because theybelieve theplan does not include complete modeling, enforceable versions ofall Reasonably Available Control Measures (RACM) and a control strategy sufficient to achieve attainment. One commenter went on to say because they believe theplan shouldbe disapproved and, under the consent decree in NRDCv. Browner,Civ. No. 99-2976, EPA must commence promulgation ofaFederal Implementation Plan (FIP). One
commenter supported theproposed approval.

Response:Inthe following responses,

we address the specific concerns raised by the commenters in more detail. We believe the plan providedby the State ofTexas is fully approvable under the Act andwill provide for attainment as expeditiously aspracticable which isby November 15, 2007 and theplan includes allreasonably available control

measures. Therefore, we are finalizing

our approval in this action. Furthermore, because we are fully approving theplan asmeeting the requirements of182(c)(2) and (d) ofthe Act, itis unnecessary to commence development ofaFIP.

Comment:TNRCC has not provided modeling that shows attainment in 2007. (Really 2005 since 4 exceedences in that year ensures failure to meet the three-year standard.) A commenter also
states thatthere is no demonstration of maintenance ofthe ozone standard below the 0.12 ppm one-hour standard beyond 2007.

Response:EPA has taken the position that for nonattainment areas subject to the requirements of subpart 2 ofpart D ofthe Act, thatthe area needs to demonstrate thatin the attainment year, the area will have air quality such that the area couldbe eligible for the two one-year extensions provided under section 181(a)(5) ofthe Act. Under section 181(a)(5), an area that does not have three-years ofdata demonstrating attainment ofthe ozone NAAQS, but has complied with all ofthe statutory requirements andthat has nomore than

one exceedance ofthe NAAQS in the attainment year, may receive a one-year extension ofits attainment date. Assuming those conditions are met the followingyear, the area may receive an additional one-year extension. Ifthe

area has no more than one exceedance in thisfinal extension year, then itwill havethree-years ofdata indicating that ithas attained the ozone NAAQS.

This position is consistent both with EPA'smodeling guidance and with the
structure of subpart 2 ofthe Act. Under EPA'smodeling guidance, states model air quality for the attainment year-they do notmodel air quality for the threeyear period preceding the attainment year. This is largely a function ofhow the model operates that the data produced onlypredicts the air quality for one year. EPA'smodeling guidance has existed for many years andhas been relied on bynumerous areas for demonstrating attainment ofthe ozone standard.

Moreover, EPAbelieves this approach is consistent with the statutory structure ofsubpart 2. Under subpart 2,many of the planning obligations for areas were notrequired to be implemented until the attainment year. Thus,Congress did
not assume that all measures needed to attain the standard wouldbe implemented three years prior to the area's attainment date. For example,

areas classified asmarginal-which had

an attainment date ofthree years following enactment ofthe 1990 Clean AirAct amendments were required to adopt and implement RACT andI/M "fix-ups" that clearly could not be implemented three years prior to their attainment date. Similarly, moderate

areas were required to implement RACT by May 1995, only 18 months prior to their attainment date ofNovember 1996. Also, the ROP requirement for moderate and above areas, including the 15% planfor reductions byNovember 1996, applies through the attainment year. Thus, EPAbelieves thatCongress did
notintend thatthese additional mandatory reductions be in excess of what is needed to achieve three-years of "clean data." For these reasons, EPA does not agree with the commenter that the State's attainment demonstration needs to demonstrate that the area will havethree years ofdata showing attainment inthe attainment year. However, EPA does believe thatthe Act requires and thatitis prudent for States
to implement control as expeditiously

as practicable. EPA alsobelieves that for the HG area, all measures are being implemented as expeditiously as practicable and thatthe area has Federal Register/Vol. 66,

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demonstrated attainment consistent with EPA's modeling guidance.

A plan for maintenance ofthe Standard is not necessary for the attainment demonstration to be approved. A State isnot required by the Act to provide amaintenance plan until the State petitions for an area to be redesignated to attainment which will
not occur until the HG area has three
years ofdata showing compliance with the Standard.

While itis not necessary for the State
to provide for maintenance ofthe standard at this time, we dobelieve emissions in the HG area will continue
to decrease after 2007 due to on and off road vehicle emission control programs that will continue toprovide additional reductions as the fleet continues to turnover after 2007. So there isreason to believe that air quality will continue
to improve after the attainment date.
Comment:Two commenters suggested the plan should address other air pollution concerns in addition to attainment ofthe one-hour standard. One commenter suggested the plan shouldprovide as much progress as possible toward implementing the 8- hour standard as therequirements ofthe Act and EPA's implementing regulations allow. Another commenter said that ozone reduction shouldbe used as a spur in reducing toxic emissions and particulate matter as well.

Response:As an initial matter, these
comments are outside the scope ofthis rulemaking. EPA's review here is focused on whether the submitted plan
meets the statutory requirements for attainment ofthe one-hour ozone standard. Nevertheless, EPAbelieves the reductions in ozone precursors in this plan will provide reductions both toward attainment ofthe one-hour standard and substantial progress toward the 8-hour standard. Furthermore, NOx emissions are a precursor to particulate matter formation. So the large NOxemissions reductions in the plan should provide improvements in particulate matter levels. In addition, while the focus of the plan is on reducing NOx emissions, VOC emissions will alsobe reducedby approximately 40% from 1993 levels. Some ofthese VOCs are also air toxics. Again, while EPAbelieves these additional air quality benefits will result from the implementation ofthis plan, the approval ofthe plan depends, as a legal matter, only on whether the plan will result in attainment ofthe one-hour

ozone standard. 2.Comments on the Photochemical Modeling

a. Model Performance

Comment: The photochemical modeling is fundamentally flawed and shouldnot be used asproposed. The

ozone plots prepared byTNRCC as part ofits graphical performance analysis show significant subregional biases in the model with systematic under predictions and over predictions. The
commenter states thatthe graphical analysis provides far more insight into the performance ofthe model than any othertype ofperformance measure. The statistical measures distort the
appearance ofmodel performance by averaging outthe subregional biases.

Response:EPA does not agree that the graphical analysis provides more insight into model performance than any other performance measures. EPA believes all model performance measures shouldbe considered. There is no rigid criterion for model acceptance or rejection in assessing model simulation results for the performance evaluation. As recommended byEPA, the State's model performance evaluations for the selected episode included diagnostic and sensitivity analyses, and graphical and statistical performance measures. TNRCC used these performance

measures in conjunction with one another to evaluate the performance of the model. Diagnostic and sensitivity analyses consisted oftesting the response ofmodeled ozone to changes in the various model inputs (i.e., meteorology, emission inventory, and initial &boundary conditions). The model performance evaluation was based upon graphical measures consisting ofcomparing time series of monitored and modeled ozone and

ozone precursor concentrations, and comparing modeled ozone concentration contours with monitored

ozone data. The model performance evaluation was also based upon statistical measures consisting of comparing the modeled versus monitored ozone. The "Unpaired Peak Accuracy," "Normalized Bias," and, "Gross Error" were all within the suggested limits in the EPA Guideline.

EPA did not dismiss any measures or analyses used byTNRCC for their model performance evaluation, nor should EPA weigh the graphical performance

more heavily than the other performance measures. As indicated in the State's modeling results for the selected episode, the model responded generally as expected to the diagnostic/ sensitivity analyses for the primary episode day (9/8/93). Overall, these analyses did not reveal any flaws in the CAMx model formulation. In addition, the statistical performance ofthe model for the primary episode indicated the model performed well. For all days modeled, the graphical performance for the majority ofthe monitor siteswas very good. For instance, the time-series plots developed for each monitoring station in the HG area indicated no significantbias within the diurnal cycle

as well as good agreement between the timing ofthe predicted and observed

ozone maxima.

EPA has recognized, however, the graphical model performance for the primary episode day of9/8/93 indicates the model at some locations underestimated ozone and at other areas the ozone was overestimated. Also, at

some locations, there are no ozone monitors to substantiate the model's performance. The ozone plume peaks

were simulated in different locations than occurred with the monitored results. EPAbelieves that most ofthe

error can be best explained by the meteorological model having some difficulty inreplicating the wind speed and direction. Discrepancies in wind speed and direction not surprisingly result in the model not predicting the maximum ozone concentration in precisely the right location, apossibility notedby the commenter.

TNRCC has spent considerable effort
to better understand the land/sea breeze phenomenon which has added alevel of complexity to the HG analysis not seen any where else in the country (withthe exception ofsome lake breeze effects in the Lake Michigan area). Emissions in the HG area are emitted into the local atmosphere where ozone formation begins, later emissions and ozone formed are transported out over the

warm air over the GulfofMexico where the warmer temperatures further activate the chemistry to formmore

ozone which is then transported back inland over the area. Current meteorological models havehad difficulty in simulating this process. We believe our understanding ofthe process is sufficient, however, to interpret the photochemical model results.

TNRCC and EPAintend to continue evaluating how to more accurately simulate the HG area's meteorological conditions in the available models. The need for further studies does not mean, however, that the modeling relied upon today was unable to estimate the
amount andtype ofemission reductions needed for attainment. EPAbelieves because the diagnostic/sensitivity tests reveal no flaws in model formulations and the model generally predicts the rightmagnitude ofthe peak which is confirmed by the statistical measures, 57164 Federal Register/Vol. 66,

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that the model does provide an acceptable tool for estimating the
amount ofemissions reduction. It is EPA's technical opinion thatbased on the weight-of-evidence andthe modeling, the State's control strategy shouldprovide for attainment by November 15, 2007.

Any new information derived from the further studies and evaluation will be incorporated byTexas into the SIP revision modeling tobe submitted to EPA byMay 1,2004. Comment:EPA previously expressed its persistent concern about the model's
poor graphical performance. Now,EPA has simply ignored the concern. The
commenter quoted aprevious EPA
comment letter sent tothe TNRCC duringthe State's August 1999 public
commentperiod for itsproposed SIP revision. EPA's comment letter stated that "due tothe model's poor graphical performance caution is warranted in assessing the model's projected ozone reduction due to NOx control strategies."

Response:EPA disagrees that the discrepancies in graphical performance have been ignored. Texas made

numerous enhancements to its August 1999 proposed SIP attainment demonstration modeling,based upon EPA's comments. TNRCC has used a

new version ofCAMx (i.e., version 2.03), which offers several enhancements over the originalversion, for the current modeling relied upon in the submitted attainment demonstration SIP revision. Also, major improvements have been made to the base year emission inventory. For instance, biogenic emissions and the emissions for diesel-powered construction equipment, commercial marine vessel emissions, airport ground support equipment emissions, and industrial equipment emissions havebeen updated with more accurate information. As a result, for all days modeled, the graphical performance, has been improved. Forinstance, the time-series plots indicate the model performance improved ata number of monitoring stations in the HG area (i.e., Galveston site, HRM sites 3and 4, Texas City site and Clinton site). In addition, the statistical model performance for the
current modeling which was similar to that for the past modeling base case indicated the model performed well. All ofthe statistical parameters are within the EPA suggested limits for the primary episode day. EPA continues to believe, taken together, the diagnostics, sensitivity, statistical and graphical performances ofthe model indicate the base case model performance is acceptable for assessing control strategy effectiveness.

Further, in EPA's letter where we said that caution is warranted in assessing the projected ozone reduction to NOx control strategies, EPAwas cautioning TNRCC that sufficient NOxreductions shouldbe provided to account for this uncertainty in the model. We were not saying that the graphical performance
meant the model was unacceptable for assessing control strategy effectiveness. Rather, we were advising the State to take into account the graphical performance, i.e., by ensuring the control strategy took amore conservative approach and erred on the side ofcaution, in the amount of required NOx reductions. Comment:One commenter believes that the modeling fails to account for

ozone spikes. The TNRCC's failure to account forthese spikes necessarily

means that the control strategy will not attain the standard. Further, this results in significant over estimates ofNOx emission reductions needed for attainment. The commenter asserts that the spikes are causedby highly reactive VOCs, a theory itbelieves to be supported bypreliminary data and findings ofthe Texas 2000 Air Quality Study.

Response:Monitors measure concentration at a point in space, and in reality, these concentrations canvary significantly over a grid cell or an area. This is true especially for ozone ifit is contained in a narrow plume. Inevitably, a grid type model will smooth some natural phenomena because natural conditions are averaged

over the volume ofeach grid cell. For instance, model outputrepresents a volume average, typically 4km x 4kmby 50 meter column. As a result,reasonable comparisons between model predictions and monitor observations are not expected tomatch exactly. With reasonable performance, time series typically show similar diurnal cycles but not exact concentration levels. As a result, itis very difficult to obtain a precise equalitybetween modeled concentration and monitored concentration. This is to be expected and does not necessarily call into question the model's utility as a toolto predict the level ofemission reductions needed toreach attainment. As statedin previous comments, EPA believes the model provides reasonable predictions ofozone levels as confirmed by comparisons with monitoring data and therefore can provide an acceptable estimate ofthe amount ofemissions needed for attainment. Certainly, any difficulty the model has in replicating rapid increases in ozone, does not indicate thatthe model is calling for an "overestimate" ofthe amount ofNOx emission reductions needed for attainment. Furthermore, even ifthe model is shown during the mid-course review to be overestimating the amount ofNOx emission reductions needed for attainment, a State is always free to adopt a control strategy thatis more stringent. See UnionElectricv. EPA, 427 U.S. 246 (1976); Trainv. NRDC,421 U.S 60 (1975).

EPA is following with interest the findings being presented from the Texas 2000 Air Quality Study, particularly the information on concentrations ofhighly reactive VOCs foundin the ambient air in the HG area. We understand Texas intends to incorporate, as much as possible,the findings ofthis study into its next modeling effort, which is currently underway and they expect to submitby the end of2002. This study may improve ourpresent understanding ofozone formation in the HG area and result in an improved effectiveness of the control strategy being implemented by the TNRCC. Nevertheless, based
upon all available evidence, the State's control strategy shows attainment for the HG area by the statutory deadline and thatthe NOx emission reductions

are needed for attainment.

Comment:The 2007 post-control strategy peak concentration is 141 ppb
at amonitoring site where the model underestimated the monitored peakby 27 ppb during the validation run. Thus, ifthe control strategy had been in effect during the episode usedfor validating the model, the actual ozone concentration would likely have been higher than 141 ppb.

Response:EPA disagrees. As is always the case in a photochemical modeling exercise, there are areas within the simulation that do not correspond exactly with observations. As discussed in other comments, in this case, the modeled wind fields tended to move the

ozone plumes formed on allfour days away fromthe areas where the highest concentrations were observed. Although the modeled peak onthe primary episode day (i.e., September 8, 1993)

was pushed west ofthe observed peak, the results ofthe State's model performance evaluation analyses for that day indicate overall the model performed well for the majority ofthe monitoring sites. Misplacing the peak does not necessarily meanthe model is providing inaccurate results or predicting less ozone on that day. In addition,this tendency does not, by itself,mean thatthe model is not useful for developing control strategies. Therefore, again, we feel the model provides a reasonable estimate ofthe

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emission reductions needed for attainment.

Comment:A commenter criticized the State model's inability toreplicate

ozone levels on September 8, 1993 and recommends thatTNRCC estimate the magnitude ofemission reductions needed for attainment from the modeling results ofSeptember 10 and 11, 1993. One commenter believes the best way to manage the risks ofmaking the wrong decision on the magnitude of the needed controls is to base HG's control strategy on the modeling simulations that have the least uncertainty. Though all four days ofthe September 8-11, 1993 base case simulation are characterized by poor graphical performance, the greatest uncertainties byfar exist for September 8 and 9, 1993. Therefore, the commenter believes that the control strategy should be based onmodeling results from September 10 or 11, 1993.

Response:EPA disagrees. As discussed in previous comments, we believe the model performance is acceptable on all four days. Furthermore, EPA guidance recommends that aminimum ofthree episode days representing different meteorological regimes be modeled(Guideline for the Regulatory Application ofthe Urban Airshed Model, July 1991). With only four days (i.e., Sept. 8-11), the number ofepisode daysbeing used byTNRCC for control strategy development is only marginally above the recommendation. Removing days would not provide an appropriate number ofmodeling days. EPAbelieves that the September 8, 1993 episode day chosen byTNRCC presents a reliable and accurate modeling scenario for

ozone attainment demonstration in the HG area. September 8, 1993 is the controlling daybecause the meteorological conditions experienced that day require the mostcontrol to reach attainment. September 8, 1993 alsohad the highest observed ozone duringthe 4 day episode. Though observed and predicted concentrations donot match exactly, plausible inputs resulted in plausible predictions. The overall model performance for the September 8, 1993 episode day meets EPA criteria. Model performance on September 11, 1993 was similar to that observed on September 8, 1993, but is
not suitable to design control strategies, since it was a Saturday. Controls based

onthat day would still need to be shown to be effective in controlling

ozone on a weekday, since the Saturday emissions from mobile and area sources differ considerably from their weekday counterparts. In addition, during episode selection, TNRCC used a modification ofthe Predominant Wind Direction (PWD) method to analyze each potential episode day. The wind analysis is based

onmorning winds and afternoon winds. The largest category was calm/calm with 10 of71 cases where most frequent wind pattern for high ozone days occurred in the HG region. The second

was calm/SSE with 9 cases. September 11, 1993 is in this category. The third category was calm/ESE with 8 cases. September 8, 1993 is in this category. The PWD for September 10, 1993 is NNW/ESE, which had one case. Meanwhile, the PWD for September 9, 1993 isNNW/NNW, which had none. Therefore, each ofthese episode days

covers different meteorological conditions that are correlated with high

ozone levels in the HG area. To remove
one or more ofthe four episode days would remove conditions that shouldbe evaluated to provide assurance thatthe controls adopted in the SIP would be expected to show attainment ofthe NAAQS for potential meteorological conditions conducive to ozone formation in the HG area. In addition, September 10, 1993 had an observed peak value that was significantly lower than the design value. Control strategies based on absolute model predictions on this day may not be sufficient to bring the area into attainment. Therefore, no days should be dropped from the State's attainment demonstration.

Comment:Evaluating the equations used to estimate the shortfall for September 10 and 11, 1993, results in gaps of21 tpd and 37 tpd, respectively, for which could be filled (with surplus) from the list ofgap measures given in Table 6.1-2 ofthe proposal.

Response:As stated in previous responses, September 8, 1993 must be considered in the control strategy to have confidence that the HG area will attain under acommonly observed meteorological condition. In any case, afterrevisions to the inventory, modeling now indicates that the additional reductions estimated for attainment on September 8, 1993 and September 10, 1993 is 90.9 tpd and 93.7 tpd NOx, respectively; thus even on September 10, 1993 the State has a shortfall because Texas has onlybeen able to adopt measures to achieve 38 tons/day of additional measures. Comment:TNRCC haspresented no evidence thatthe model is accurately simulating NOx orVOC levels, or other intermediate chemical species in the vicinity ofthe modeled peaks.

Response:EPA disagrees. There is no monitoring data in the area where the modeled peak occurred toindicate one way or the otherhow well the model compared to measurements ofNOx, VOC andintermediate species. As a part ofthe 1993 COAST study, VOC concentrations were measured at two locations in the HG nonattainment area, and comparisons havebeen made between modeled and monitored concentrations. Similarly, for each of the locations where NOxwas monitored, comparisons havebeen madebetween modeled and monitored concentrations. All ofthese comparisons are included and discussed in the '98 and '99 SIPs submitted to EPA. Therefore, the attainment demonstration we are approving relies
upon evidence thatthe model provided results in areasonable agreement with the measurements considering thatthe comparison is between a point
measurement and a simulated volumetric average.

Monitors measure the concentration
at apoint in space, and in practice, these concentrations can vary significantly from avolume average that is 4km square and up to 50 meter high. Thisis true for VOC and NOx precursors, and is especially true for precursors emittedby point sources. The comparisons that havebeen made indicate reasonable agreement between monitored and modeled concentrations given the considerations cited above (see Appendix B entitled "Time Series Plots ofObserved, CAMx and UAM-V Ozone Precursors Over the H/G Modeling Domain for The Base Case Simulation") ofthe Appendix B (entitled "Modeling the Houston/ Galveston Ozone Attainment Demonstration")) ofthe December 2000 SIP revision. Besides, the CAMx photochemical model, which is an

ozone model, was developed and optimized for thatpurpose. As expected, some other chemical species will not compare as well with ambient data as does ozone. As mentioned above, there are no monitoring datafor intermediate species, which have not been recommended for use invalidating model results since they are not reliable. Instead, these are often used to validate model inputs (i.e., emission inventory), iftheybecome available.

Comment:Because ofdoubts regarding the accuracy ofthe model predictions, commenters recommend thatnew emission controls be based on proven cost-effective technology and that stakeholders be given asmuch time
to implement controls asthe Act allows. The model simulations andbasic science that are the foundations ofthe commission's control strategy are currently not strong enough to support the unproven, technically infeasible, or

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economically challenging measures in the State's adopted control strategy.

Response:As described in previous comments, we believe that the model performance is acceptable andprovides

an appropriate assessment ofthe
amount ofemission reductions needed for the HG area to attain. TNRCC and its
contractors have used state-of-thescience approaches to support the adopted control strategy. All appropriate and pertinent data submitted duringthe State's comment periods toimprove the model were incorporated or addressed bythe State. As discussed in our RACM and the shortfall enforceable commitment
responses, itis EPA's position that the control measures in the HG control strategy are feasible. Therefore, it is our position thatthe controls thathave been adopted by Texas have been shown to be needed for the HG area to attain by the statutory deadline. These controls

are being implemented as expeditiously

aspracticable as required by the Act.

Comment:A commenter believes that the TNRCC must address the risk that the modeling uncertainties may have led the commission to a wrong estimate ofthe magnitude ofemission reductions needed to attain the ozone NAAQS.

Response:In the earlier submitted SIPs, the effect ofthe uncertainty ofthe emissions relative to the reductions needed to attain the NAAQS was addressed. This involved developing an alternate emissions inventory that reflected uncertainties, evaluating base

case model performance, and the effect

onthe reductions needed to attain the NAAQS with the future 2007 emissions. This modeling showed that the control path needed to attain the NAAQS did
not change (a NOxrather than VOCdirected control strategy), and thatthe order ofmagnitude ofthe required reductions did not change much. This reinforced the necessity ofobtaining the level ofNOx and VOC reductions contained in this SIP revision.

The current approach does not show attainment ofthe NAAQS at all locations on all days that were modeled, but uses modeling in combination with weight ofevidence to show thatthis level ofNOx and VOC reductions are adequate to attain the standard. Furthermore, the mid-course evaluation

canbe used by Texas to reassess the level ofcontrols needed to attain the NAAQS and ensure that timely progress isbeing made toward attainment ofthe standard.

Comment:One commenter supports the recent contract commissioned by Harris County with Environ. This work will re-run the model with an alternate meteorological simulation model in a further attemptto address the nonperformance ofthe grid cells in question.

Response:EPA understands that TNRCC has worked with Harris County andEnviron on the alternate meteorological simulation ofthe episode modeled by the commission.It takes substantial time and effort to develop meteorological datato be run in the photochemical model. After the data

are developed, the model results must be evaluated for adequate meteorological model performance. Then the data must be used in the photochemical model to evaluate basecase model performance with the new data set. Ifthe revised base case modeling meets the performance requirements, then the model will be applied to the future 2007 emissions, and various control scenarios modeled. Ifthese efforts provide abetter representation ofmeteorological conditions in the HG area, then Texas would address them in the mid-course review. Comment:Because ofthe model's performance one commenter disagrees with the following proposals: (1)The model activities were performed as outlined in the Protocols. (2)The model activities were performed according tothe Guideline For Regulatory Application ofUAM. (3)Thatthe model performed within EPA's recommended ranges. (4) Thatthe base case model is suitable for control strategy testing.

(5)The proposal to accept the base

case model as abasis for attainment demonstration modeling.

(6) The implicit finding that the TNRCC validated theperformance ofthe base case modeling. (7)Thatthe simulated ozone contour plots from the base case model depict the area ofozone tobe only "somewhat
at odds geographically" withthe monitors. (8) The implicit finding that thebase

case model fails only to "precisely predict" the position ofthe cloud of

ozone geographically.

(9) Thatthe base case model's predicted position ofthe cloud ofozone does not byitself, mean thatthe base

case model is not acceptable for control strategy development.

(10) Thatthe statistical measures from the base case model are within EPA recommended limits for all days of September 8-11, 1993.

(11) Thatthe results ofthe statistical

measures are within EPA recommended
ranges. (12) Thatthe spatial and temporal patterns ofozone generated by the base case model indicate itis acceptable for

use in the Attainment Demonstration.

(13) The diagnostic, sensitivity, statistical and graphicalperformance of the base case model indicate itis acceptable for use in the Attainment Demonstration.

(14) That reductions ofNOx will be
mosteffective inbringing HGA into attainment.

(15) That the quadratic equation used by the TNRCC to determine the additional amount ofadditional emission reductions isconsistent with the 1999 guidance.

(16) That the quadratic equation is an improvement over the 1999 guidance.

(17) That an additional 96 tons/day of NOx emission reduction are necessary to bring the HG area into attainment.

Response:As discussed in previous comments, we believe the model performed acceptably foruse in control strategy development. Therefore, we disagree with the commenter and continue to support the findings in the conclusions from ourproposed approval that are cited above.

b. Model Inputs
Comment:Off-road shipping emissions may be underestimated based

on preliminary results from the Texas Air Quality 2000 Study.

Response:The State conducted a study of actual shipping activity in the HG area and applied EPA emission factors to the activity to calculate the shipping emissions. This site-specific methodology is approved by EPA and provides thebest estimate ofemissions
atthis time. The results from the Texas Air Quality Study 2000 arejust now being made available for analysis. The results were not available to the State at the time the SIP was prepared, andthe State needs additional time to evaluate the data. Itis hoped thatthe data can be usedby Texas forits mid-course review.However, there isno evidence presently before EPA showing that offroad shipping emissions were underestimated by the State.

Comment:Industrial VOC emissions

are understated based on the preliminary results ofthe Texas 2000 Air Quality Study.

Response:As discussed above, TNRCC has followed EPA approved methodologies in preparing its emissions inventory. They have goneto substantial effort to characterize allthe categories, including the industrial emissions. This has included detailed inventories from all ofthe major emitters and inclusion ofepisodic releases that were reported during the 1993 episode. We believe thatthe emissions inventory isbased on the best

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available techniques and data and meets allEPA criteria and requirements.

TNRCC is continuing to work to improve the inventory. This is amajor emphasis ofthe Texas 2000 Air Quality study.We are aware some ofthe preliminary findings ofthis study indicate that industrial VOC emissions may be understated. This indication is based upon onlypreliminary findings at this time, however. Texas hasreached

no final conclusions. EPA will work with TNRCC and other stakeholders to address improvements to the inventory

so thatthe mid-course review modeling incorporates any new and appropriate data.

Comment:The commission and its
contractors have worked commendably
to develop what may be, in many respects, the most accurate emissions inventory ever used in photochemical modeling. But major uncertainties still existin other respects and in the model's representation ofthe chemical reactions and meteorological processes that determine the location, time, and magnitude ofhigh ozone levels in Houston-Galveston.

Response:EPA disagrees that there

are major uncertainties with the modeling. As discussed above in previous responses, it is EPA's technical position thatthe modeling adequately represents the meteorological processes for the HG area to allow its use for control strategy purposes. Further, the modeling is acceptable in its representation ofthe chemical reactions in the HG area. TNRCC and its
contractors have used state-of-thescience modeling approaches for development ofthe meteorological parameters used in the modeling.

The chemical algorithms used in the modeling reflect the latest developments in the state-of-the-science today. TNRCC is currently investigating various alternate chemical mechanisms, and they plan to continue this activity with analyses on the Texas 2000 study results. Ifenhancements are identified for the chemical algorithms, they can be utilized in the mid-course evaluation, and Texas would include them in the mid-course review SIP. Comment:It was noted that the 91 tpd increase in point source NOxemissions produced daily maximum ozone increases ranging from 1.5 ppb (on September 10) to 6.1 ppb (onSeptember 11). The commenter also noted thatthe 91 tpd decrease in on-road mobile and non-road mobile source NOx emissions produced ozone decreases, relative to HRM Strategy 1,ranging rom 6.9 ppb (onSeptember 11) to 10.8 ppb (on September 8). From this, the commenter

sees relatively smallbenefits from the commission's 90% point source control proposal relative to a 75% point control level, but sees greaterbenefits ifthe

same amount ofincremental emissions

was reduced from mobile sources. Itwas also noted that mobile source emission reductions ranged from 1.1 to 7.0 times

more effective than point source NOx reductions at reducing ozone levels (giventhe ratio ofmobile source to point source NOx effectiveness). From this, itfollows that mobile source NOx emission reductions are onaverage 3 times more effective atreducing ozone levels than are point source emission reductions.

Response:Itis quite possible that mobile source controls may be more effective in reducing ozone levels for certain nonattainment areas. The State, however, analyzed the ensemble of emission reductions modeled for the SIP development for the HG area based on

an analysis ofpotential reductions available from all ofthe various source categories. As discussed in other sections, Texas has adopted all RACM for mobile aswell as stationary sources. It is not EPA's role to disapprove the State's choice ofcontrol strategies ifthat strategy will result in attainment ofthe one-hour standard and meets all other applicable statutory requirements. See UnionElectricv EPA,427 U.S. 246 (1976); Trainv. NRDC,421 U.S 60 (1975).

Comment:One commenter states that the modeled control strategy contained in the Attainment Demonstration includes measures that were modified

orremoved from the SIP. The State did
not remodel to determine the impact of these changes. Particularly, one measure that was modified was a relaxation in utility controls from 93% to 90%.

Another commenter supported the changes to the required emission rates for utilities because these revisions will be offsetby emission reductions from grandfathered facilities in attainment counties surrounding the HG area.

Response:Duringthe State's settlement negotiations and trial court proceedings this summer in BCCA Appeal Group,etal. v. Texas Natural Resource ConservationCommission,et al.in the District Court ofTravis County, Texas 250th Judicial District, Cause No. GN1-00210, TNRCC determined that the amount ofcontrol for utilities should be reduced from 93% control to 90% control. Due to time constraints andthe necessity for submitting an approvable attainment demonstration in time for EPA action before the NRDC consent decree deadline ofOctober 15, 2001 for proposing aFIP in the absence ofa fully approved SIP, the revised utility controls were not modeled by TNRCC. TNRCC believes, and EPA agrees, that any potential loss in ozone benefit from reducingthe utility point source requirement willbe deminimis,based
upon a review ofcertain information gathered from the 2000 Texas Air Quality Study. The information inthe Studyindicates that Reliant Energy's Parish power plant, located inthe HG

area has an ozone production efficiency which is 3to 5times smaller than the

ozone production efficiency expected for the grand-fathered utility and nonutility sources based on Southern Oxidant Studyresults for the Memphis

area. Ozone production efficiency is a

measure ofthe efficiency that a particular NOxplume generates ozone and is an indication ofthereactivity of the VOCs with which the NOx plume

comes in contact. The Parish plant is located outside the central urban area and apparently notin an area ofhighly reactive biogenic emissions. The remaining units affected by the reduced control requirement are mainly peaking units which deliver their increased emissions during the hot afternoon hours. Modeling for the construction ban and lawn-care activities has consistently shown that emissions in the afternoon contribute less to ozone formation in the HG area than emissions generated in the morning.

To counterbalance the reduced controls on utilities in the HG area, Texas will control grandfathered

sources in East andCentral Texas by 50% as required by recent State legislation. These controls are in addition to controls on utility sources, Alcoa and Texas Eastman that are already included in the model results. These new controls would apply to all non-utility sources, particularly pipeline compressor station emissions wouldbe reduced by 50%. These emission reductions canbe expected to achieve an ozone benefit in the HG area to counterbalance the loss inNOx reductions from the change in utilities from 93-90% control.

Because the impact ofthe emission increases for utilities in the HG area will be small and there is aprogram to offset these deminimisincreases, EPA believes itis appropriate to acceptthe modeling and weight ofevidence as showing that attainment canbe achieved in the HG area bythe statutory deadline.

TNRCC currently intends to conduct modeling based on the data results of the Texas 2000 Air Quality Study, in 2002. Pursuant tothe State's mid-course review enforceable commitment, Texas will submit arevised attainment demonstration SIP by May 1, 2004 that

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will include modeling thatincorporates all scientific advancements made since the recent SIP revisions, as appropriate. Comment:As required by recent legislation, the TNRCC repealed the time-of-day construction ban. To provide for the benefits that would have been achieved bythe construction ban, the Texas legislature adopted a diesel emission reduction incentive program. However, TNRCC failed tomodel the control strategy with the diesel engine incentive program replacing the morning construction ban. EPA may not approve the photochemical modeling andthe subsequent gap calculation because these emission reductions were revised and not modeled.

Response:Texas legislation, enacted in May, 2001, established a diesel emission reduction incentive program andrequired TNRCC to repeal its rules for amorning construction ban and accelerated purchase ofdiesel equipment. Due to time constraints and the necessity for submitting an approvable attainment demonstration in time for EPA actionbefore the NRDC
consent decree deadline ofOctober 15, 2001 for proposing a FIP in the absence ofa fully approved SIP, the State could
not specifically model the diesel engine incentive program in their attainment demonstration. The TNRCC had, however, conducted numerous control scenario modeling runs, which combined federal, state and local
measures, designed to provide significant ozone reductions in the area. The results ofone control scenario modeling run indicated that the benefit ofthe construction ban was approximately 3ppb ofozone. Based on the quadratic curve, TNRCC estimated that this 3ppb reduction in the ozone concentration level was equivalent to a 6.7 tpd reduction ofNOxemissions. EPA believes the State used acceptable procedures for determining this estimate. As discussed in other
responses to comments regarding the diesel engine incentive Program, EPA believes that this program will achieve greater NOx emission reductions in the HG area than 6.7 tpd. EPA and State calculations project thatthis new program will coverthe loss in reductions from the construction ban andthe accelerated purchase rules, and also fill a portion ofthe shortfall. EPA believes that the incentive program will likely produce somewhat greater benefits than the morning construction banbecause itcan achieve emission reductions not only from construction diesel equipment but also from additional categories such as tug/tow boats which are located in the portion ofthe HG area where the highest ozone levels often occur. In addition,TNRCC currently intends to conduct modeling based onthe data results ofthe 2000 Texas Air Quality Study, in 2002. Pursuant tothe State's mid-course review enforceable commitment, Texas will submit arevised attainment demonstration SIP by May 1, 2004 that will include modeling thatincorporates all scientific advancements made since the recent SIP revisions, as appropriate. Comment:TNRCC has not correctly estimated point source growth in attainment counties ofEast and Central Texas. The commenter provided Public Utility Commission estimates ofnew capacity.

Response:As noted bythe commenter, Appendix H ofthe SIP contains documentation ofthe projected newly permitted growth. Texas examined all ofthe permits issued by TNRCC for the 8 county HG area andthe counties within 100 miles ofthe HG

area. Permitted projects in this area
were included in the model's future base inventory. EPAbelieves that Texas used areasonable method ofestimating the growth for the area most likely to impact the HG area's air quality. Comment:One commenter stated the attainment andrate ofprogress demonstrations are flawed because they

assume afleet mixthat does not accurately reflect the growing proportion ofsport utility vehicles and gasoline trucks. EPA and the states have
not followed a consistent practice in updating SIP modeling to account for changes in vehicle fleets. EPA cannot rationally approve SIPs that are based

on suchmaterially inaccurate assumptions. Continued use ofoutdated assumptions is inconsistent with the duty imposed by the Act section 182(a)(3) to triennially update the emission inventory. Ifthe motor vehicle inventory has not been updated in preparing the current SIP submission, the SIP shouldbe disapproved. One
commenter compared the numbers from the Dallas/Fort Worth area to the HG

area and provided theresults ofa Contractor Study ofvehicle registration datato support its claims that the portion ofSUVs in the Houston fleet are understated.

Response:The November 1999 HG

area attainment demonstration SIP's associated mobile source budgets were based onfleet mixinformation updated based on aDecember 1998 Texas Transportation Institute (TTI)Report, "Development ofGridded On-road Inventory for the Houston/Galveston Ozone Nonattainment Area," found in Appendix G ofthe November 1999 SIP revision. TTIrelied on vehicle classification count datarecorded on roadways throughout the 8-county area by Texas Department ofTransportation (TxDOT)personnel utilizing automatic vehicle classification (AVC) equipment. This equipment is set up alongthe roadway and iscalibrated to classify all ofthe passing vehicles into thirteen vehicle types. Due to the fact that AVC equipment cannot distinguish vehicle fuel type onthe roadway, the various vehicle categories are then separated out into theirgasoline and diesel classifications, based on a combination ofMOBILE5 defaults and county vehicle registration data. The fleet mix information was based onvehicle
counts that were amix of 1996 data for week days, and 1993 and 1998 datafor weekends. This was the most recent data available when Texas submitted the attainment demonstration SIP for the HG area in November 1999.

The December 2000 SIP included data providedby TTIfrom the mostrecently available observed AVC data which was from 1997, 1998, and 1999. In order to avoid year-to-year fluctuations in the data set, TTI averaged the AVC data fromthese three years in order to obtain

a more recent VMT mix, which was usedin the revised 2007 inventory. This data was used to update the modeling provided in December 2000. Atthe time the TNRCC modeling for the December 2000 SIP was being completed, this data
set was the most recent data available. The data used for the modeling ismore recentthan the mostrecently completed periodic inventory (1996). The 1999 inventory is expected to be completed

soon andinclude the more recent data.

EPA requires the most recent available data to be used, but we donot require ittobe updated on a specific schedule. Therefore, different SIPs base theirfleet mix on different years ofdata. Our guidance does not suggest that SIPs shouldbe disapproved on thisbasis. Nevertheless, we do expect that revisionsto these SIPs that are submitted usingMOBILE6 (asrequired in those cases where the SIP isrelying

on emissions reductions fromthe Tier 2 standards) will use updated vehicle registration data appropriate for use with MOBILE6, whether itis updated local data or the updated national default data that will be part of MOBILE6.

In the November 3, 1999, "Guidance

on Motor Vehicle Emissions Budgets in One-Hour Ozone Attainment Demonstrations," we state that, when developing motor vehicle emissions budgets, the MOBILE inputs (including vehicle fleet characteristics) shouldbe appropriate and up-to-date as outlined in EPA's guidance on SIP inventories and the MOBILE user's guide. The SIP Federal Register/Vol. 66,

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has been based on the most recent information and meets the intended
purpose ofthe existing guidance.

A particular concern raised by a commenter was thatregistration data from the TXDOT data base indicate that 13.2% ofthe vehicles registered in the 8 county area are light duty gas trucks
two (LDGT2) ascompared to the VMT mix figures provided by TTI which project this category atonly 4.5% of the mix. The commenter also pointed out that LDGT2 were estimated as 11.4% of the mixfor the Dallas/Fort Worth area SIP and the EPA national default is 8.8%. The LDGT2 category includes large SUV andpickups. The percentage ofmiles traveledby these vehicles is important because they currently have higher emission standards than passenger cars.

The EPAbelieves thatvehicle registration data alone does not necessarily represent the most accurate estimation offleet mix characteristics that actually exist on the current transportation network system. The best possible approach wouldbe touse a combination ofboth AVC and conventional registration data. However, EPA believes that field AVC data of vehicles traveling on theroadways throughout the 8-county area provide a reasonable estimate ofthe types of vehicles and distance these vehicles are driven. This is because vehicles from

some categories are driven more than other categories. Heavy Duty Diesel Trucks, in particular, account for more miles than the values thatmay be reflected bythe vehicular registration
process. Registration distribution is different than VMT mix and actual data is the best possible information. In addition, while one might expect the numbers tobe similar between DFW and Houston, they are two different cities with many different social and economic variables. One cannot presume Houston tobe the same as DFW when the location specific data does not support this conclusion.

It isworth noting that the Tier II standards will eliminate the difference between (i) passenger car and (ii)larger truck and SUV emissions standards. Therefore, as Tier II vehicles become

more widespread, possible discrepancies in the percentage of trucks and SUVs willbecome less important for air quality planning purposes. The Tier II standards begin taking affect in new vehicle manufactured in 2004.

The EPAhas encouraged and required

use ofthe latest assumptions and data in forecasting the on-road mobile source emissions whenever possible. Updating the data and using the latest information is a continuous planning process which does not end with this SIP and will continue in the future for emissions inventory updates, SIP development, and for conducting conformity determinations. In addition, the refinements in the emissions inventory procedures and use ofthe MOBILE6 model will further enhance not only the VMT mix issue but also other parametric inputs in computing the onroad mobile source emissions. However, it must be recognized thatbecause of
many constraints associated with availability andtiming ofnew information, the process ofupdating the vehicular and other data does not necessarily follow the SIP development cycle, and thus there islikely to be a lag time. The EPA is committed to ensure that the best available data are used in any air quality analysis and this SIP is

no exception. Therefore, based on the information documented in the SIP and the EPA's current guidance, the EPA believes that Texas has made reasonable assumptions and has utilized the most recent available data in determining the on-road mobile source emissions.

Comment:The model's failure to account for episodic emissions events is

a serious flaw. The commenter cited a description in the SIP ofa butadiene release asevidence ofthis problem.

Response:TNRCC made every effort
to account for episodic emissions in the model. It surveyed companies to determine ifany specific events occurred duringthe modeling episode, including reported upset events. The reported episodic emissions were included in the modeling. Consequently, we believe Texas used the best information available to address episodic emissions andtherefore, the SIP is approvable.

The growing availability of ambient VOC datafrom the Photochemical Assessment Monitoring Stations (PAMS)network, however, indicates that more may need tobe done in this

area. The butadiene release citedby the
commenter is a case in point. In addition,the Texas 2000 Air Quality Studyis providing a wealth of information thatis justbeing analyzed. This data, itis hoped, will shed more light on the impact ofepisodic emissions on ozone levels. The midcourse review SIP, due to EPAin May 2004, will contain the most recent data available for thatSIP's planning.

Comment:EPA should investigate the impact onthe plan ofany changes being considered in the EPA's 90-day review ofthe New Source Review (NSR) progam. The commenter is concerned that relaxed NSR requirements may affect the level ofemissions from point

sources in the Region.

Response:The 90-day review ofthe NSRprogram is not complete at this time. It is expected that any modifications to the Federal NSR provisions will include provisions for strict caps for the pollutants and therefore should be as stringent as the presentNSR rule. Moreover, any changes made through this review will
not affectthe NSR rules approved for the HG area in the current SIP. IfTexas determines that the HG area rules shouldbe modified in response to the 90-day review, Texas will need to submit those changes as a SIP revision and under Section 110(1) ofthe Act, EPAwill need to consider the effect of those changes on the HG area's attainment demonstration.

c. Weight ofEvidence Analysis

Comment:Several commenters stated thatthe weight ofevidence approach does not demonstrate attainment or meet CAArequirements for amodeled attainment demonstration. Commenters added several criticisms ofvarious technical aspects ofthe weight of evidence approach, including certain specific applications ofthe approach to particular attainment demonstrations. These comments are discussed in the following response.

Response:Under section 182(c)(2) and (d) ofthe Act, serious and severe ozone nonattainment areas were required to submitby November 15, 1994, demonstrations ofhow they would attain the one-hour standard. Section 182(c)(2)(A) provides that "[t]his attainment demonstration must be based

on photochemical grid modeling or any other analytical method determined by the Administrator, in the Administrator's discretion, to be at least

as effective." As described in more detail below, the EPA allows states to supplement their photochemical modeling results, with additional evidence designed to account for uncertainties in the photochemical modeling, to demonstrate attainment. This approach isconsistent with the requirement ofsection 182(c)(2)(A) that the attainment demonstration "be based

on photochemical grid modeling," because the modeling results constitute the principal component ofEPA's analysis, with supplemental information designed to account foruncertainties in the model. This interpretation and application ofthe photochemical modeling requirement of section 182(c)(2)(A) finds furtherjustification in the broad deference Congress granted EPAto develop appropriate methods for 

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determining attainment, as indicated in the last phrase ofsection 182(c)(2)(A).

The flexibility granted to EPAunder section 182(c)(2)(A) is reflected in the regulations EPApromulgated for modeled attainment demonstrations. These regulations provide, "The adequacy ofa control strategy shall be demonstrated by means ofapplicable air quality models, data bases, and other requirements specified in (40 CFR part 51, Appendix W) (Guideline on Air Quality Models)."' 40 CFR 51.112(a)(1). However, the regulations further provide, "Where an air quality model specified in appendix W. * * *is inappropriate, the model maybe modified or another model substituted (withapproval by EPA, and after) notice and opportunity for public comment. * * *." Appendix W, in turn, provides that, "The Urban Airshed Model (UAM) is recommended for photochemical or reactive pollutant modeling applications involving entire urban areas," but further refers to EPA's modeling guidance for data requirements and procedures for operating the model. 40 CFR part 51, Appendix W, section 6.2.1.a. The modeling guidance discusses the data requirements and operating procedures, as well as interpretation ofmodel results as they relate to the attainment demonstration. This provision references guidance published in 1991, but EPA envisioned the guidance would change as we gained experience withmodel applications, which is why the guidance is referenced, but does not appear, in Appendix W. With updates in 1996 and 1999, the evolution ofEPA's guidance has ledus to useboth the photochemical grid model, and additional analytical methods approved by EPA.

The modeled attainment test compares model predicted one-hour daily maximum ozone concentrations in all grid cells for the attainment year to the level ofthe NAAQS. The results may be interpreted through either oftwo modeled attainment or exceedance tests: A deterministic test or a statistical test. Under the deterministic test, a predicted concentration above 0.124 parts per million (ppm)ozone indicates thatthe

area is expected to exceed the standard in the attainment year and a prediction
ator below 0.124 ppm indicates that the

area is expected to not exceed the standard. Under the statistical test, attainment is demonstrated when all

1 The August 12, 1996 version of "Appendix W
to Part51-Guideline on air QualityModels" was the rule in effect for these attainment demonstrations. EPA is proposing updates to this rule which will notbe in effect until the new rule is promulgated. predicted (i.e., modeled) one hour ozone concentrations inside the modeling domain are at, orbelow, an acceptable
upper limit above the NAAQS permitted under certain conditions (depending on the severity ofthe episode modeled).2

In 1996, EPA issued guidances to update the 1991 guidance referenced in 40 CFR part 50, App. W, tomake the modeled attainment test more closely reflect the form ofthe NAAQS (i.e., the statistical test described above), to consider the area's ozone design value andthe meteorological conditions accompanying observed exceedances, andto allow consideration ofother evidence to address uncertainties in the modeling databases and application. When the modeling does not conclusively demonstrate attainment, EPA has concluded that additional analyses may be presented tohelp determine whether the area will attain the standard. As with other predictive tools, there are inherent uncertainties associated with air quality modeling and its results. The inherent imprecision ofthe model means thatit
may be inappropriate to viewthe specific numerical result ofthe model as the only determinant ofwhether the SIP controls are likely to lead to attainment. The EPA's guidance recognizes these limitations, andprovides a means for considering other evidence to help

assess whether attainment ofthe NAAQS is likely tobe achieved. The
process bywhich this is done is called

aweight ofevidence determination. Under a weight ofevidence determination, the state can rely on, and EPA will consider in addition to the results ofthe modeled attainment test, otherfactors such as othermodeled output (e.g., changes in the predicted frequency and pervasiveness ofonehour ozone NAAQS exceedances, and predicted change in the ozone design value); actual observed air quality trends (i.e. analyses ofmonitored air quality data); estimated emissions trends; andthe responsiveness ofthe model predictions to further controls.

In 1999, EPA issued additional guidance 45thatmakes further use of

2Guidance on the Use OfModeled Results to Demonstrate Attainment of the Ozone NAAQS. EPA-454/B-95-007, June 1996.

3Ibid.
45 "Guidance for Improving weight ofEvidence Through Identification of AdditionalEmission Reductions, NotModeled." U.S. Environmental Protection Agency,Office ofAirQuality Planning and Standards, Emissions, Monitoring, and Analysis Division, Air Quality Modeling Group, Research Triangle Park, NC 27711. November 1999. Web site: http://www.epa.govlttnlscram.http:// www.ncdc.noaa.gov/ol/climate/research/1999/ perspectives.html and "Regional Haze and Visibility in the Northeast U.S.", NESCAUM at http://www.nescaum.org/pdf/pubslist.pdf model results for base case andfuture emission estimates to predict afuture design value. This guidance describes the use ofan additional component of the weight ofevidence determination, which requires, under certain circumstances, additional emission reductions that are or willbe approved into the SIP, but that were not included in the modeling analysis, that will further reduce the modeled design value. An area is considered tomonitor attainment ifeach monitor site has air quality observed ozone design values (4thhighest daily maximum ozone using the three most recent consecutive years ofdata) at or belowthe level ofthe standard. Therefore, itis appropriate for EPA, when making a determination that

a control strategy will provide for attainment, to determine whether or not the model predicted future design value is expected to be at or belowthe level ofthe standard. Since the form ofthe one-hour NAAQS allows exceedances, it did not seem appropriate for EPAto require the test for attainment tobe "no exceedances" inthe future model predictions. The method outlined in EPA's 1999 guidance uses the highest measured design value from all sitesin the nonattainment area for each ofthree
years. 6The three year "design value" represents the air quality observed during the time period used to predict

ozone for the base emissions. This is appropriate because the model is predicting the change in ozone from the base period to the future attainment date. The three yearly design values (highestacross the area) are averaged to account for annual fluctuations in meteorology. The result is an estimate of

an area's base year design value. The base year design value is multiplied by

a ratio ofthe peak model predicted

ozone concentrations in the attainment year (i.e., average ofdaily maximum concentrations from all days modeled)
to the peakmodel predicted ozone concentrations in thebase year (i.e., average ofdaily maximum

6A commenter criticized the 1999 guidance as flawed on grounds that itallows the averaging of the three highest air quality sites across a region, whereas EPA's 1991 and 1996 modeling guidance requires that attainment be demonstrated ateach site. This has the effect of allowinglower air quality concentrations to be averaged against higher concentrations thus reducing the total emission reduction needed to attain at the higher site. The commenter's concern is misplaced. EPA relies on this averaging only for purposes of determining one component, i.e.,-the amount ofadditional emission reductions notmodeled-ofthe weight of evidence determination. The weight ofevidence determination, inturn, is intended to be a qualitative assessment ofwhether additional factors (includingthe additional emissions reductions not modeled), taken as a whole, indicate that the area is more likely than notto attain.

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concentrations from all days modeled). The result is an attainment year design value based on the relative change in peak model predicted ozone concentrations from the base year to the attainment year. Modeling results also show that emission control strategies designed toreduce areas ofpeak ozone concentrations generally result in similar ozone reductions in allcore

areas ofthe modeling domain, thereby providing some assurance ofattainment
atall monitors.

In the event thatthe attainment year designvalue is above the standard, the 1999 guidance provides a method for identifying additional emission reductions, not modeled, which at a minimum provide an estimated attainment year designvalue at the level ofthe standard. This step uses a locally derived factor which assumes a relationship between ozone and the
precursors.

Although a commenter criticized this technique for estimating ambient improvement because it does not incorporate complete modeling ofthe additional emissions reductions, the regulations do not mandate nor does EPA guidance suggest that States must model all control measures being implemented. Moreover, a component ofthis technique-the estimation of future design value, shouldbe considered amodel predicted estimate. Therefore, results from this technique

are an extension of "photochemical grid" modeling and are consistent with section 182(c)(2)(A). Also, a commenter believes EPA has not provided sufficient opportunity to evaluate the calculations used to estimate additional emission reductions. EPA provided a 60-day period for comment on the methodology and calculations in December 1999 and

a 30-day comment period in July 2001

onthe HG area's calculated shortfall. Texas also provided a public comment period and public hearings in September, 2000 on this issue.

A commenter states that application ofthe method of attainment analysis used for the December 16, 1999 NPRs will yield a lower control estimate than ifwe relied entirely on reducing maximum predictions in every grid cell
to less than or equal to 124 ppb on every modeled day. However, the commenter's approach may overestimate needed controls because the form ofthe standard allows up to 3 exceedances in 3years in every grid cell. Ifthe model over predicts observed concentrations, predicted controls may be further overestimated. EPA has considered other evidence, as described above through the weight ofevidence determination. When reviewing a SIP, the EPA must make a reasonable determination that the control measures adopted more likely than not will lead to attainment. Under theWeight ofevidence determination, EPAhas made this determination for the HG area based on all ofthe information presented by the State and available to EPA. The information considered includes model results for the majority ofthe control

measures. Though allmeasures were not modeled, EPA reviewed the model's response to changes in emissions as well as observed air quality changes to evaluate the impact of additional
measures, not modeled. EPA's decision

was further strengthened bythe State's commitment to check progress towards attainment in 2004 and to adopt additional measures, ifthe anticipated
progress is not being made.

A commenter further criticized EPA's technique for estimating the ambient impact ofadditional emissions reductions not modeled ongrounds that EPA employed arollback modeling technique that, according tothe commenter, isprecluded under EPA regulations. The commenter explained that 40 CFR part 51, App. W, section 6.2.1.e. provides, "Proportional (rollback/forward)modeling is not an acceptable procedure for evaluating

ozone control strategies." Section 14.0 ofappendix W defines "rollback" as "a simple model that assumes thatif emissions from each source affecting a given receptor are decreased by the

same percentage, ambient air quality concentrations decrease proportionately." Under this approach if 20% improvement in ozone isneeded for the area to reach attainment, it is assumed a 20% reduction in VOC would be required.

The "proportional rollback" approach is based on a purely empirically/ mathematically derived relationship. EPA did not rely on this approach in its evaluation ofthe attainment demonstrations. The prohibition in Appendix W applies to the use ofa rollback method which is empirically/ mathematically derived and independent ofmodel estimates or observed air quality and emissions changes as the sole method for evaluating control strategies. For the demonstrations, EPA used a locally derived (as determined by the model and/or observed changes in air quality) relationship ofthe change in emissions
to change in ozone to estimate additional emission reductions to achieve an additional increment of ambient improvement in ozone. For example, ifmonitoring ormodeling results indicate that ozone was reduced by 25 ppb during a particular period, and thatVOC and NOx emissions fell by 20 tons per day and 10 tons per day respectively during thatperiod, EPA developed a relationship for ozone improvement related to reductions in VOC andNOx. This formula assumes a quadratic relationship between the
precursors and ozone for a small
amount ofozone improvement, but it is
not a "proportional rollback" technique. Further, EPAuses these locally derived adjustment factors as a component to estimate the extent to which additional emissions reductions-not the core control strategies-would reduce ozone levels and thereby strengthen the weight ofevidence test.EPAuses the UAM to evaluate the core control strategies. This limited use ofadjustment factors is

more technically soundthan the unacceptable use ofproportional rollback to determine the ambient impact ofthe entire set ofemissions reductions required underthe attainment SIP. The limited use of adjustment factors is acceptable for practical reasons: It obviates the need to expend more time and resources to perform additional modeling. In addition,the adjustment factoris a locally derived relationship between

ozone andits precursors based on air quality observations and/or modeling which is more consistent with recommendations referenced to in Appendix W and does not assume a direct proportional relationship between

ozone andits precursors. In addition, the requirement that areas perform a mid-course review (acheck ofprogress toward attainment) provides a margin of safety.

A commenter expressed concerns that EPAused a modeling technique (proportional rollback) that was expressly prohibited by40 CFR part 51, Appendix W,without expressly proposing to do so in anotice of proposed rulemaking. However, the
commenter is mistaken. As explained above, EPA did notuse or rely upon a proportional rollback technique in this rulemaking, but used UAM to evaluate the core control strategies and then applied its WOE guidance. Therefore, because EPA did notuse an "alternative model" to UAM, it did not trigger an obligation tomodify Appendix W. Furthermore, EPA did propose to use the November 1999 guidance, "Guidance for Improving Weight of Evidence Through Identification of Additional Emission Reductions, Not Modeled," in the December 16, 1999 NPR andhas responded to all comments received on the application ofthat guidance elsewhere inthis document.

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A commenter also expressed concern that EPA applied unacceptably broad discretion in fashioning and applying the WOE determinations. For all ofthe attainment submittals proposed for approval in December 1999 concerning serious and severe ozone nonattainment
areas, EPA first reviewed the UAM results. In all cases, the UAMresults did
not pass the deterministic test.In two cases-Milwaukee and Chicago-the UAM results passed the statistical test; in the rest ofthe cases, the UAM results failed the statistical test.The UAM has inherent limitations that, in EPA's view,

were manifest in all these cases. These limitations include: Only selected time periods were modeled, not the entire three-year period used as the definitive

means for determining an area's attainment status. Also, there are inherent uncertainties in the model formulation and model inputs such as hourly emission estimates, emissions growth projections, biogenic emission estimates, and derived wind speeds and directions. As a result, for all areas, even Milwaukee and Chicago, EPA examined additional analyses toindicate whether additional SIP controls wouldyield meaningful reductions in ozone values. These analyses did not point tothe need for additional emission reductions for Springfield, Greater Connecticut, Metropolitan Washington DC, Chicago andMilwaukee, but did point to the need for additional reductions, in varying amounts, in the other areas. As

aresult, the other areas submitted control requirements to provide the indicated level ofemissions reductions. EPA applied consistent methodologies in these areas, but because ofdifferences in the application ofthe model to the circumstances ofeach individual area, the results differed on a case-by-case basis.

The commenter also complained that EPA has applied the WOE determinations to adjust modeling results onlywhen those results indicate nonattainment, and not when they indicate attainment. First, we disagree with thepremise ofthis comment: EPA does not apply the WOE factors to adjust model results. EPA applies the WOE factors as additional analysis to compensate for uncertainty in the air quality modeling. Second, EPA has applied WOE determinations to all of the attainment demonstrations proposed for approval in December 1999. Although for mostofthem, the air quality modeling results by themselves indicated nonattainment, for two metropolitan areas-Chicago and Milwaukee, including parts ofthe States ofIllinois, Indiana, and Wisconsin, the air quality modeling did indicate attainment onthe basis ofthe statistical
test.

For the HG area, the primary evidence, in addition to the modeled control strategy thatthe HG area will attain the standard, isthe estimation of the ozone benefits from the emission reductions thatwere not modeled (i.e., approximately 90.9 tpd). Additional evidence for the HG area isprovided by the good model performance which lends credence tothe results. Further evidence isthe substantial reduction in the area ofnonattainment projected for the control strategy case. The State showed the modeled control strategy resulted in a93.6% reduction in grid cells over the standard. Finally, the state's commitment to perform amidcourse review provides further confidence that the State's overall plan will result in attainment by 2007. Collectively, the above information supported EPA's decision. These determinations were made based on EPA's best understanding ofthe problem andrelied on a qualitative
assessment as well as quantitative
assessments ofthe available information.

The commenter further criticized EPA's application ofthe weight of evidence determination on grounds that EPA ignores evidence indicating that continued nonattainment is likely, such
as, according to the commenter, monitoring data indicate that ozone levels in many cities during 1999 continue to exceed the NAAQS by margins as wide or wider than those predicted by the UAM model. EPA did consider the monitoring data along with otherinformation in these determinations. When reviewing the monitoring data, EPA considered other factors. For example, high monitoring values may have occurred for many

reasons including, fluctuations due to changes in meteorology andlack of emission reductions. The 1999 monitor values donot reflect several control programs, both local andthe regional which are scheduled for implementation in the next several years. And the 1999 meteorology in the Northeast was suchthat July 1999 was

one ofthe warmest (ranked9th) ever experienced since 1895. 7 In addition to the heat,the middle and southern portions ofthe Northeast were also drier than average during this month. This information supports EPA's beliefthat the high exceedances observed in 1999

7http://www.ncdc.noaa.gov/ol/climate/research/ 1999/perspectives.html and "Regional Haze and Visibility in the Northeast U.S.", NESCAUM at http://www.nescaum.org/pdf/pubslist.pdf are not likelyto reoccur frequent enough to cause aviolation, once the controls adopted inthese SIP's are implemented. There is little evidence to support the statement that ozone levels in many cities during 1999 continue to exceed the NAAQS bymargins as wide

or wider than those predicted by the UAM. Since areas did not model 1999

ozone levels using 1999meteorology and 1999 emissions which reflect reductions anticipated by control
measures, that are orwill be approved into the SIP, there is no way to determine how the UAM predictions for 1999 compare to the 1999 air quality. Therefore, we can not determine whether or not the monitor values exceed the NAAQS by awider margin thanthe UAM predictions for 1999. In summary, there is little evidence to support the conclusion thathigh exceedances in 1999 will continue to

occur after adopted control measures are implemented.

In addition, the commenter argued thatin applying the weight ofevidence determinations, EPAignored factors showing that the SIPs under-predict future emissions, and the commenter included as examples certain mobile

source emissions sub-inventories. EPA did not ignore possible under-prediction in mobile emissions. EPA ispresently evaluating mobile source emissions data

as part ofan effort toupdate the computer model for estimating mobile

source emissions. EPA is considering various changes to the model, and isnot prepared to conclude at this time that the net effect ofall these various changes would be toincrease or decrease emissions estimates. For the HG area's attainment demonstration SIP thatrelies on the Tier 2/Sulfur program for attainment (andreflects these programs inits motor vehicle emissions budgets), Texas has committed to revise the motor vehicle emissions budgets after the MOBILE6 model is officially released by EPA. EPA will workwith Texas ifthe new emission estimates raiseissues about the sufficiency ofthe present attainment demonstration. If analysis indicates additional measures

are needed, EPAwill take appropriate action.

Comment:The 1999 Guidance Documentwas criticized ongrounds thatEPA could not apply it,by its terms,to the Houston area because the result ofsuch application would have been absurd. The commenter added that the technique used to estimate the additional needed emission reductions for the Houston area does not identify

a sufficient level ofemission reductions
to reach attainment. In addition, according to the commenter, the 

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technique used for the Houston area is substantially atvariance with the UAM modeling analyses performed by Texas and submitted to EPA as SIP revisions. Specifically, Texas showed in its May 1998 SIP submission that emissions in the Houston area would have to be reduced to 230 tons per day to attain. By contrast, according to the commenter, EPA's combination oftechniques would allow 305 tons per day ofemissions, andyet EPA claims that the area will attain with even this higher level of emissions. The commenters believe that Texas should not be able to use the gap calculation when modeling exists that demonstrates how attainment can be achieved. A commenter also asserted that Texas should not be able to use a gap calculation method that differs from what other areas must use and the gap calculation fails to account for real world chemistry.

Response:Direct application ofthe
two methods discussed in EPA's November 1999 guidance, using available data for the HG area, produced

amathematical impossibility. The results indicated thatall ozone precursor emissions would have tobe reduced to less than zero. Thus, the two methods described in the 1999 guidance

are not directly applicable to Houston. The 1999 guidance describes two techniques for estimating additional levels ofemission reductions. Both techniques (methods) described in the 1999 guidance are based on the assumption thatEPA can estimate the relationship between ozone and its
precursors. EPARegion 6 and TNRCC worked together to develop a revised method that is consistent with the concepts in the 1999 guidance for estimating therelationship, but applicable tothe Houston area's modeling results. The methods in the guidance use a linear extrapolation of model results to determine expected

ozone benefits from additional
precursor reductions. The method for the HG area is also an extrapolation of model results. Because, the method for the HG area extends model results, it does, in fact account for real world chemistry. Instead ofa linear extrapolation, however, a quadratic extrapolation was developed based on the results ofthree ofthe modeling runs. A quadratic extrapolation is necessary because ofthe non-linearity ofthe ozone response to NOxreductions in the HG

area. Therefore, the method is a refinement in the methods described in the 1999 guidance, since itisbased on the mostrecently available modeling for the Houston area. The factors used in the method for the Houston area are based onmodel results for the majority ofthe control measures and, consequently, are scientifically sound for the HG area. We believe this approach is consistent with the intent and criteria ofthe 1999 guidance and, in the case ofthe Houston area, gives a better approximation (than the other
two methods) ofthe amount ofemission reductions thatwill be necessary to achieve the standard. Therefore, this method fulfills the purposes ofthe EPA guidance, and itis as rigorous, ifnot

more rigorous, than the two methods discussed in the 1999 guidance. As a result, EPA concludes thatthe State of Texas used an acceptable method under the November 1999 guidance and applied it correctly.

In the strategy upon which the NOx mobile vehicle emissions budget is based, Texas modeled NOx emissions reduced to a level ofapproximately 396 t/d. Since the model predicted future

ozone design values above the standard, using the refinement ofthe 1999 guidance (discussed above) EPA determined additional emission reductions were needed and the level of
NOx needed for attainment is 305 t/d.

The 230 tons per day emission level in the May 1998 SIP submission was based upon "across-the-board" emission sensitivity modeling andnot specific control measures, as was submitted in the November 1999 attainment demonstration. Thus,the 230 tons per day emission level is not associated with any controlmeasures, and itis not appropriate as a regulatory emission level for an attainment SIP. In addition, there have been many notable changes
to the modeling emissions inventory subsequent to the May 1998 SIP submission. These include revised biogenic emissions, revised non-road emissions, andrevised 2007 future year on-road mobile source emissions.Thus, it is not appropriate to compare the 305 t/d and the 230 t/d, since they are really based upon different applications ofthe model. Further, it isnot correct to say modeling exist that demonstrates how attainment canbe achieved.

With regards to whether the approach used for the HG area sufficiently identifies the expected additional
amount ofemission reductions needed for attainment by the deadline, for the

reasons noted above, webelieve the modeling and weight ofevidence techniques used for the HG area do provide a reasonable estimate ofthe emission reductions necessary for attainment. Furthermore, these emission reductions are quite substantial. The projected attainment level of 305 t/d of
NOx is a 71% reduction from the projected 2007 NOx emissions of 1052 t/d and a 77% reduction from the 1993 NOx emissions of1337 t/d. Thisis a significant amount ofNOxreductions andbased onthe analyses presented, EPAbelieves these level ofreductions willbring the area into attainment.

Comment:Acommenter stated that TNRCC took into account modeling performance concerns in developing a weight ofevidence analysis to support its October 1999 SIP revision and concluded that a modeled control strategy, nearly identical to the one described in its December 2000 SIP revision would produce attainment even though attainment was not conclusively demonstrated by the model. EPA rejected this analysis, however, and prescribed anew methodthat the
commenter goes on to criticize.

Response:EPA did notbelieve that sufficient emission reductions had been identified in the control strategy modeled in the November 1999 episode. EPAproposed its preliminary analysis ofthe November 1999 SIP revision that

a shortfall of 11% NOx emission reduction existed. Significantly, we received no comments at the time of thatproposal that the 11% shortfall was too high.We received comments tothe contrary thatthe needed additional emission reductions were understated.

EPA does not agree with the characterization that EPA "prescribed"

a newmethod. Other weight ofevidence techniques, as described in EPA guidance were still available toTexas and could havebeen considered. We worked with Texas in the development ofthe quadratic method thatwas used

as weight ofevidence for the HG area to provide a method that we and Texas believed gave an accurate estimate of the needed additional emission reductions.

Comment:Acommenter criticizes thatin contrast to the 1999 Guidance, the weight ofevidence method EPA developed for the HGA does not employ

a relative reduction factor or afuture design value calculation. The quadratic extrapolation is neither consistent with

nor an improvement onthe 1999 guideline methods and EPA's description ofit as such is erroneous. The commenter goes onto compare and
contrast specific differences between the method developed for Houston andthe 1999 guidance.

Response:EPA continues tobelieve, in the case ofthe HG area, the method developed is an improvement over the November 1999 guidance. This guidance was developed for estimating the additional reduction needed to support the one-hour ozone NAAQS for those nonattainment areas using a weight ofevidence approach to

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demonstrating attainment. This guidance describes two methods for calculating the amount ofthe additional reductions needed,but does not prohibit the use ofan alternative method. Both methods assume thatthe relationship between ozone and the NOx and VOC precursors canbe estimated. Direct application ofthe two methods discussed in EPA's November 1999 guidance using available datafor the Houston area, produced a mathematical impossibility. The results indicated thatall ozone precursor emissions would have tobe reduced to less than zero. Thus, the two methods described in the 1999 guidance are not directly applicable to Houston. EPA and TNRCC worked together to develop a revised method thatis consistent with the concepts in the 1999 guidance for estimating therelationship, but applicable tothe Houston area's modeling results. The methods in the guidance use a linear extrapolation of model results to determine expected

ozone benefits from additional
precursor reductions. The method for the Houston area is also an extrapolation ofmodel results. Instead ofa linear extrapolation, however, a quadratic extrapolation was developed based onthe results ofthree ofthe modeling runs. A quadratic extrapolation isnecessary because ofthe non-linearity ofthe ozone response to NOx reductions in the Houston area. Therefore, the method developed for the HG area is a refinement the two methods in the 1999 guidance, since these two methods are also based on modeling. The factors used in the method for the Houston area arebased

onmodel results for the majority ofthe control measures and, consequently, are scientifically soundfor the Houston

area.We believe this approach is consistent with the intent and criteria of the 1999 guidance and, in the case of the Houston area, gives abetter approximation ofthe amount of emission reductions that willbe necessary to achieve the standard. Therefore, this method fulfills the
purposes ofthe EPA guidance, and it is

asrigorous, ifnot more rigorous, than the two methods discussed in the 1999 guidance. Furthermore, itcannot be
accurate to characterize the methods in the 1999 guidance as better when, in fact, they produce a mathematical impossibility for the HG area.
3.Comments on Control Strategies

Comment:One commenter stated that the plan should provide evidence that Texas Senate Bill 5 (SB-5) provisions

canbe implemented and will lead to at least 6.7 tons/day ofNOxemission reductions. Another commenter stated EPA should not give credit tothe Texas Emission Reduction Plan created by SB5without assurances oflong-term funding levels and details about longterm funding. They also cite information that the funding for the program might be less than EPA assumed because of legal challenges.

Response:Based on experience in California with the Carl Moyer program, the Diesel Emission Reduction Program provided by the Texas Legislature shouldbe able to provide emissions reduction in therange of$3000-5000/
ton. This is documented in the report "The Carl Moyer Memorial Air Quality Standards Attainment Program (The Carl Moyer Program) GuidelinesApproved Revision 2000, November 16, 2000 California Environmental Protection Agency Air Resources Board." The clear intent ofthe legislation, as stated onthe TNRCC website, is "The highest priority for using the funds under the Emissions Reduction Grants Program will be to replace NOx emissions reductions removed from the State Implementation Plans (SIPs) for the HG area and Dallas/ Fort Worth (DFW)nonattainment areas

as aresult ofS.B. 5. Using an average of$5,000 per ton ofNOx reduced, the TNRCC has determined that itwill require $6.7 million per year in HGA to replace the construction shift and accelerated Tier II/III rules. Another $7.5 million will be required to partially fill (20 tons) the 56 ton gap, making the HG area total $14.2 million."

EPA's estimates arenot as optimistic but we do believe the $24.7 million/yr projected onthe TNRCC website should result in atleast 25 tons/year of emission reductions, an amount sufficient to offsetthe construction shift and accelerated Tier II/III and contribute
to reducing the shortfall. We will work with Texas to refine the estimates of emission reductions. Itis clear that if

more money is needed for the HG area

asthe program isimplemented to make additional reductions in the shortfall, the TNRCC has the discretion to channel more money tothe Houston

area.

With regard to legal challenges to the program's funding mechanisms, EPA will not anticipate a court's findings. If

a courtfinds the funding mechanism illegal, Texas will have to revise the SIP
atthat time to address the loss in emission reductions orfind alternative funding sources. In the absence of timely State actionto address any adverse courtruling, EPA could take action to ensure attainment is not jeopardized. Comment:Commenters questioned the emissions benefit ofthe low emission diesel rule.

Response:The EPA hasjust completed a study ofthe benefits oflow emission diesel fuels, such as the Texas Clean Diesel fuel.EPA determined the Texas fuel will result in NOx reductions. However, it appears thatthe NOxreductions based on thejustcompleted study will be slightly less thanthose projected byTexas. EPA believes, because the emissions impact is expected to be small and because Texas has committed to address any change to the amount ofneeded emission reductions at the mid-course review,the recent study findings do not change the approvability ofthe attainment demonstration. We willwork with Texas to incorporate the findings ofthe study into future SIP revisions.

Comment:One commenter supported the fact that EPA did not take any action

on morning construction ban.

Response:EPA determined not to take action onthe construction ban since the legislature had removed the TNRCC's authority to implement this measure.

Comment:EPAmust discount the emission reduction credit from the AirportGround Support Equipment agreed orders because these orders do
not assign specific budgets to individual airlines and therefore do notinsure the achievement ofany particular ton/day emissions.

Response:The agreed orders require percentage reductions from a 1996 baseline which achieve the same purpose as an emissions limitation.The reductions specified in each order are enforceable against the owner/operator ofthe equipment, thus providing a comfortable degree ofcertainty thatthe reductions will take place.

Comment:The EPA should discount the emission reductions from I/Mbased

on the recently released National Research Council (NRC) Report.

Response:The NRC recommendation provides thatthe models projecting emissions from I/Mprograms shouldbe improved to reflect actual reductions

more accurately. EPA agrees that emission performance ofvehicles has improved since the datathat form the basis ofexisting models were generated. Most ofthe data for MOBILE5 was based

on evaluation ofearly 1980's vehicles.

EPA's soon-to-be-released MOBILE6 model has been substantially updated to better reflect actual emissions and actual I/Mbenefits. The model has also been made more flexible to better incorporate local data on compliance, technician training, and the inclusion/ exclusion ofvehicles ofcertain ages. As technologies and characteristics ofthe

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fleet change, data collection, analysis, and model improvement will likely continue to be warranted. Texas has committed to revise the Mobile Vehicle Emissions Budget using MOBILE6 no later than 2years after its official release. Ifa transportation conformity analysis is to be performed between 12 months and 24 months after the MOBILE6 official release, transportation conformity will not be determined until Texas submits an MVEB which is developed using MOBILE6 and which

we find adequate. Further, it is our understanding thatTNRCC intends to

use Mobile 6 in the attainment demonstration modeling planned for submission in December 2002.

Comment:The Act requires the SIP to include a program to provide for enforcement ofthe adopted measures. Most plans address this requirement, however, none ofthe plans clearly set outprograms to provide for enforcement. Another commenter said the EPA should take steps to insure adequate enforcement ofpermit standards. Other commenters said the plan includes unenforceable items such

as the restriction on commercial lawn mowing.

Response:State enforcement program elements are contained in SIP revisions previously approved by EPAunder obligations set outin section 110 ofthe Act. Once approved by the EPA, there is no need for states toreadopt and resubmit their enforcement programs with each and every SIP revision generally required by other sections of the Act.

EPA will monitor the effectiveness of the new programs, such as the commercial lawn mowing restriction, and work withTexas torevise the
programs ifnecessary. Comment:The State submittal should include creditable, adequate rules to achieve attainment that should also provide for a margin for error.

Response:EPA generally agrees with the comment. EPA believes thatthe Margin ofError for the HG area plan, while small, is appropriate in lightof the significant level ofreductions in the plan and the commitment to perform the mid-course review and to adopt additional measures as appropriate.

Comment:One commenter stated that there is over crediting ofnational rules for architectural coatings, autorefinishing coatings and consumer products. They state the credit claimed isbased on EPA estimates ofemission reductions from proposed versions of these rules, but the final versions ofthe rules are weaker than the proposed rules. Therefore, the credit claimed for these national rules shouldbe recalculated to reflect onlythe actual emission reductions that can be expected under the final EPA rules.

Response:Architectural Coatings: EPA's March 22, 1995 memorandum 8 indicated EPA's viewthat itwas acceptable for states to claim a 20% reduction in VOC emissions from the AIM coatings category in ROP and attainment demonstration plans based

onthe anticipated promulgation ofa national AIM coatings rule. In developing the attainment SIP for the Houston area, Texas relied on this memorandum to estimate emission reductions from the anticipated national AIM rule. EPA promulgated the final AIM rule in September 1998, codified at 40 CFR part 59, subpart D. In the preamble to EPA's final AIM coatings regulation, EPA estimated that the regulation will result in 20% reduction ofnationwide VOC emissions from AIM coatings categories (63 FR 48855). The estimated VOC reductions from the final AIM rule resulted in the same reductions as those estimated in the March 1995 EPApolicy memorandum. In accordance with EPA's final regulation, Texas has assumed a 20% reduction from AIM coatings source categories in its attainment modeling. AIM coatings manufacturers were required to be in compliance with the final regulation within one year of promulgation, except for certain pesticide formulations which were given an additional year to comply. Thus all manufacturers were required to comply, atthe latest, by September 2000. EPA believes that all emission reductions from the AIM coatings national regulation will occur by 2002 andtherefore are creditable in the attainment plan for the Houston area.

AutobodyRefinish Coatings Rule: According toEPA's guidance 9and proposed national rule, many States have claimed a 37% reduction from this

source category based on a proposed rule. However, EPA's final rule, "National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings," published on September 11, 1998 (63 FR 48806), did
not regulate lacquer topcoats and will result in a smaller emission reduction of around 33% overall nationwide. The

8 "Credit for the 15 Percent Rate-of-Progress Plans
for Reductions from the Architectural and Industrial Maintenance (AIM)Coating Rules," March 22, 1995, from John S. Seitz, Director, Office of Air Quality Planning and Standards to Air Division Directors, Regions I-X.

9"Credit for the 15 Percent Rate-of-Progress Plans for Reductions from the Architectural and Industrial Maintenance (AIM)Coating Rule and the Autobody Refinishing Rule," November 27, 1994, from John S. Seitz, Director, OAQPS, to Air Division Directors, Regions I-X. 37% emission reduction from EPA's proposed rule was an estimate ofthe totalnationwide emission reduction. Since this number was an overall average, itwas not applicable to any specific area. For example, in California the reduction from the national rule is

zerobecause itsrules are more stringent thanthe national rule.

Texas did not rely on the above guidance. Instead, as part ofthe development of their 15% Rate of Progress plan, Texas used data for autorefinishing coating use specific for Texas to estimate the emission reductions from existing state rules. To avoid double counting, forthe purposes ofthe attainment demonstration, they did not assume any additional emission reductions due tothe national rule. Therefore, the Houston area's attainment demonstration SIP relied on state rules, not the national rule for its emission reductions. On EPA's approval ofthe 15% ROP plan, EPA approves the credit Texas is nowrelying on for attainment.

ConsumerProductsRule:According
to EPA's guidance 10 and proposed national rule, States have generally claimed a 20% reduction from this

source category. The final rule, "National Volatile Organic Compound Emission Standards for Consumer Products," (63 FR48819), published on September 11, 1998, will result in a 20% reduction. Therefore the reductions obtained by States from the final national rule are consistent with credit which was claimed.

Comment:One commenter included by reference their comments on the TNRCC proposed rules. They include several comments opposing the Construction Hour shift, Accelerated Tier I/I1, NOx Reduction Systems (a requirement to retrofit off-road equipment), and low sulfur gasoline.

Response:As all ofthese measures havebeen dropped from the State's plan and were not submitted toEPA. Thus,

no response is necessary.
4. Comments on Enforceable Commitments

Comment:Several commenters claim thatEPA shouldnot approve the attainment demonstration for the HG

area because the plan contains, in part, commitments to adopt measures that are necessary to reach attainment. The
commenters contend thatEPA does not have authority to accept enforceable commitments to adopt measures in the

10

"Regulatory Schedule for Consumer and Commercial Products under Section 183(e) ofthe Clean AirAct," June 22, 1995, from John S.Seitz, Director, OAQPS,to AirDivisionDirectors, Regions I-X. 57176 Federal Register/Vol. 66,

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### Federal Register/Vol. 66, No. 220/Wednesday, November 14, 2001/Rules and Regulations 57177

future in lieu of adopted control

measures.

The commenters contend thatthe 56 tpd gap must be closed now. The
commenters are concerned thatTexas has proposed a process that will take three more years-until 2004-to develop and adopt the final control

measures needed for attainment. Deferred adoption and submittal are not consistent with the statutory mandates and are not consistent with the Act's demand that all SIPs contain enforceable measures. EPA does not have authority to approve a SIP ifpart ofthe SIP isnot adequate to meet all
tests for approval. Because the submittal consists in part ofcommitments, Texas has not adopted rules implementing final control strategies, andthe plan includes insufficient reduction strategies to meet the emission reduction goals established by the TNRCC. Thus, Texas has failed to adopt

a SIP with sufficient adopted and enforceable measures to achieve attainment. Forthese reasons, the submittal also does not meet the NRDC's
consent decree definition ofa "full attainment demonstration SIP," which obligates EPA topropose a federal implementation plan ifit does not approve the HG area SIP. For these
reasons, EPA should reject the HG area SIP and impose sanctions on the area andpublish a proposed FIP no later than October 15, 2001.

Response:EPA disagrees with the comments, andbelieves-consistent with pastpractice-that the Act allows approval ofenforceable commitments that are limited in scope where circumstances exist thatwarrant the use ofsuch commitments in place of adopted measures."I Once EPA determines that circumstances warrant consideration of an enforceable commitment, EPAbelieves that three factors shouldbe considered in determining whether to approve the enforceable commitment: (1)Whether

11Thesecommitments are enforcd by the EPA and citizens under, repesetively, sections 113 adn 301 ofthe Act. In the past, EPA has approved enforceable commitments and courts have enforced these actions against states that failed to comply with those commitments. See, e.g., AmericanLung AssociationofNewJerseyv.Kean, 670F.Supp. 1285 (D.N.J 1987), affirmed, 871 F.2d 319 (3rd Cih. 1989); NRDCv.N.Y. StateDept.ofEnvironmental Conservation,668 F. Supp. 848 (S.D.N.Y. 1987); Citizens fora Better Environmentv. Deukmejian, 731 F. Supp. 1448, reconsideration granted inpart, 746F. Supp. 976 (N.D. Cal. 1990); Coalition for CleanAir,et al. v.South CoastAirQuality ManagementDistrict,CARB andEPA, No. CV 97- 6916 HLH, (C.D. Cal. August 27, 1999). Further, if

a statefails to meet its commitments, EPA could make a finding offailure to implement the SIP under Section 179(a), which would start an 18- month period for the State to begin implementation before mandatory sactions areimposed. the commitment addresses alimited portion ofthe statutorily-required program; (2)whether the state is capable offulfilling its commitment; and (3) whether the commitment is for a reasonable and appropriate period of time.

As an initial matter, EPAbelieves that present circumstances for the New York City, Philadelphia, Baltimore and Houston nonattainment areas warrant the consideration ofenforceable commitments. The Northeast states that make up the New York, Baltimore, and Philadelphia nonattainment areas submitted SIPs thatthey reasonably believed demonstrated attainment with fully adopted measures. After EPA's initial review ofthe plans, EPA recommended tothese areas that additional controls would be necessary to ensure attainment. Because these

areas had already submitted plans with many fully adopted rules and the adoption of additional rules would take

some time, EPAbelieved itwas appropriate to allow these areas to supplement their plans with enforceable commitments to adopt and submit control measures to achieve the additional necessary reductions. Forthe HG area, the State has submitted supporting information that EPAhas confirmed indicating thatTexas has adopted for the HG area NOx controls that are as tight or tighter than any other

area including the one extreme areaSouth Coast. Thus, because the State has adopted many strict controls that were included in the submitted plan and needs additional time to consider technologies that are still in the developmental stages, EPA determined that itis appropriate to consider an enforceable commitment for the remaining necessary reductions. For the HG area, EPA has determined that the submission ofenforceable commitments in place of adopted control measures for this limited set ofreductions will not interfere with the area's ability to meet its rate-of-progress obligations.

EPA's approach here ofconsidering enforceable commitments that are limited in scope is not new. EPA has historically recognized that under certain circumstances, issuing full approval may be appropriate for a submission that consists, in part, ofan enforceable commitment. See e.g., 62 FR 1150, 1187 (Jan. 8, 1997) (ozone attainment demonstration for the South Coast Air Basin); 65 FR 18903 (Apr. 10, 2000) (revisions to attainment demonstration for the South Coast Air Basin); 63 FR 41326 (Aug. 3, 1998) (federalimplementation plan for PM-10 for Phoenix); 48 FR 51472 (State Implementation Plan for NewJersey). Nothing inthe Act speaks directly to the approvability ofenforceable commitments.12 However, EPAbelieves thatits interpretation is consistent with provisions ofthe Act. For example, section 110(a)(2)(A) provides that each SIP "shall include enforceable emission limitations and other control measures,

means ortechniques * * * as wellas schedulesandtimetables for compliance,as maybe necessary or appropriate to met the applicable requirement ofthe Act." Section 172(c)(6) ofthe Act requires, as a rule generally applicable tononattainment SIPs, thatthe SIP "include enforceable emission limitations and such other control measures, means or techniques * * * as may be necessary or appropriate to provide for attainment

• * * bythe applicable attainment date

... " (Emphasis added.) The emphasized terms mean that enforceable emission limitations and other control measures do not necessarily need to generate reductions in the full amount needed to attain. Rather, the emissions limitations and other control measures maybe supplemented with other SIP rules-for example, the enforceable commitments EPAis approving today-as long asthe entire package ofmeasures and rules provides for attainment. EPA's interpretation that the Act allows for a approval oflimited enforceable commitments has been upheld bythe
courts ofappeals in some circuits. See CityofSeabrookv.EPA, 659 F.2d 1349 (5th Cir. 1981); ConnecticutFund forthe Environmentv. EPA, 672 F.2d 998 (2d Cir.), cert. denied 459 U.S. 1035 (1982); FriendsoftheEarthv. EPA,499 F.2d 1118 (2dCir. 1974); Kampv. Hernandez,752 F.2d 1444 (9th Cir. 1985).

As provided above, after concluding thatthe circumstances warrant consideration ofan enforceable commitment-as they dofor the HG area-EPA would consider three factors in determining whether to approve the submitted commitments. First, EPA believes thatthe commitments must be limited in scope. In 1994, in considering EPA's authority under section 110(k)(4)
to conditionally approve unenforceable commitments, the Court ofAppeals for the District ofColumbia Circuit struck down an EPApolicy that would allow

12Section 110(k)(4) provides for "conditional approval" ofcommitments that need notbe enforceable. Under that section, a Statemay commit
to "adopt specific enforceable measures" within
one-year ofthe conditional approval. Ratherthan enforcing such commitments against the State, the Act provides that the conditional approval will
convert to a disapproval if "the State fails to comply withsuch commitment."

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States to submit (under limited circumstances) commitments for entire programs. Natural ResourcesDefense Councilv.EPA,22 F.3d 1125 (D.C. Cir. 1994). While EPA does notbelieve that

case is directly applicable here, EPA agrees with the Court that other provisions in the Act contemplate that

a SIP submission will consist ofmore than a mere commitment. See NRDC, 22. F.3d at 1134.

In the present circumstances, the commitments address only a small portion ofthe plan. Forthe HG area, the commitment addresses only 6% ofthe emission reductions necessary to attain the standard. Already adopted measures include controls to reduce NOx emissions by approximately 90% from industrial sources, amore stringent and expanded I/M program, a Clean Diesel Program, a well-funded incentive program to encourage the early introduction ofcleaner diesel equipment, controls on airport ground support equipment, and several voluntary measures toreduce emissions from mobile sources.

As tothe second factor, whether the State is capable offulfilling the commitment, EPA considered the
current or potential availability of

measures capable of achieving the additional level ofreductions represented by the commitment and whether the State has or iscapable of getting the requisite authority to adopt

measures to achieve those reductions.

For HG area, the SIP submittal already includes substantial reductions, covering every significant NOx source category. The SIP for the HG area already includes NOx control requirements that, overall, are more expensive andtechnologically advanced, and apply to smaller emitters, than those in any other SIP in the nation otherthan the South Coast-the one

area classified as extreme for the 1-hour

ozone standard. Thus, determining

measures that will generate the necessary additional reductions is significantly more complex than for the northeastern States. However, the State has provided EPAwith sufficient information to assure EPAthat itwill be capable of adopting controls to achieve the necessary level ofemission reductions. First, the State has identified advanced technologies and innovative ideas that, in EPA's opinion,

are or will be shortly available and thus couldbe adopted and implemented in sufficient time for the HG area to attain by 2007. Furthermore, the State has identified arange ofemission reductions thatpotentially couldbe achievedby each ofthese advanced technologies and innovative strategies. While at this time the State-in conjunction with EPA-is still working
to assess the appropriate level of reductions thatmay be achieved by these technologies and strategies, EPA believes that the totality ofthe current information is sufficient to assure EPA that Texas canmeet its commitment to adopt measures that will achieve the level ofreductions necessary to meet the HG area's shortfall.

The third factor, EPA has considered in determining to approve limited commitments forthe HG area attainment demonstration is whether the commitment isfor areasonable and appropriate period. EPArecognizes that both the Act and EPAhave historically emphasized the need for submission of adopted control measures in order to

ensure expeditious implementation and achievement ofrequired emissions reductions. Thus, to the extentthat other factors-such as the need to consider innovative control strategiessupport the consideration ofan enforceable commitment in place of adopted control measures, the commitment shouldprovide for the adoption ofthe necessary control

measures on an expeditious, yet practicable, schedule.

Texas is faced with exploring cuttingedge technology, as it has already required extremely stringent controls. Thus, in considering the appropriate
amount oftime for Texas to meet its commitment, EPA considered that Texas needs time to develop and assess the capabilities ofthese technologies in addition to the time itneeds to adopt the measures that will achieve the needed level ofemission reductions. Because some ofthe measures that Texas is considering are further along in the development process, Texas has committed to adopt measures to fill a portion ofthe shortfallin the near term andto adopt theremaining measures by

an intermediate-term date. Thus, Texas has committed to adopt controls to achieve 25% ofthe needed emission reductions byDecember 2002 andto adopt controls to achieve theremaining level ofreduction byMay 1, 2004. EPA believes that this schedule is expeditious in light ofthe types of cutting-edge controls thatTexas needs
to evaluate, develop and then adopt in order to achieve the level ofreductions needed in the HG area. In addition, EPA believes that these adoption dates will
not impede Houston's ability to attain the 1-hour ozone standard by November 15, 2007 nor will it impede Houston's abilityto meet the ROP requirement because the HG area canmeet the ROP requirement with already adopted

measures. The enforceable commitments submitted forthe HG nonattainment
area, in conjunction with the other SIP

measures and other sources ofemissions reductions, constitute the required demonstration of attainment and the commitments will notinterfere withthe area's ability to make reasonable progress under section 182(c)(2)(B) and (d). EPAbelieves thatthe delay in submittal ofthe final rules is permissible under section 110(k)(3) because the State has obligated itselfto submit the rules by specified short-term and intermediate-term dates, and that obligation isenforceable by EPA and the public. Moreover, as discussed in the proposal and TSD, the SIP submittal approved today contains major substantive components submitted as adopted regulations and enforceable orders.

EPA does not agree with the assertion thatthe HG area SIP does not meet the NRDC consent decree definition of a "full attainment demonstration." The
consent decree defines a "full attainment demonstration" as a demonstration according to CAA section 182(c)(2). As a whole, the attainment demonstration-consisting of photochemical grid modeling, adopted control measures, an enforceable commitment with respect to alimited portion ofthe reductions necessary to attain, and other analyses and documentation-is approvable since it "provides for attainment ofthe ozone (NAAQS)by the applicable attainment date." See section 182(c)(2)(A).

Comment:The SIP includes explicit enforceable commitments to consider relaxing regulations on industrial point

sources. EPAmust reject any efforts to relax effective control measures on the books before the TNRCC eliminates the identified shortfall in emission reductions. Proposed changes to the planwould commit the TNRCC to consider steps that willunlawfully increase the gap between predicted emission reductions resultingfrom regulatory measures and the emission reduction goals established by the TNRCC. Further, itisunlawful for the SIP to contain a promise to relax NOx point sources in exchange for implementation ofmeasures to control upset emissions.

Response:The TNRCC has included in Chapter 7ofthe SIP its commitment
to developing an enforceable plan to reduce releases ofreactive hydrocarbon emissions and emissions ofchlorine. Recent findings fromthe Texas 2000 Air Quality Study indicate that highly reactive hydrocarbons and/or chlorine emissions may be primary causes ofthe rapid build-up ofozone in the HG area. 57178 Federal Register/Vol. 66,

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TNRCC goes onto say thatto the extent that the science confirms the benefit from this program then it is the intent ofthe commission toimplement such a program through a SIP revision which would also decrease NOx reductions required from industrial sources down
to 80% control. Atthis time, EPAis not acting on whether this potential, future SIP revision wouldbe approvable. At this time, we are considering only the effective State rulesbefore us that include 90% control on industrial

source NOxemissions. The State's commitment to consider alternative control strategies in the future has no bearing on this approval. The Supreme Court has consistently held thatunder the Act, initial and primary responsibility for deciding what emissions reductions will be required from which sources is left tothe discretion ofthe States. Whitmanv.Am. TmckingAss'ns, 531 U.S. 457 (2001); Trainv. NRDC,421 U.S. 60 (1975). This discretion includes the continuing authority torevise choices about the mix ofemission limitations. Trainat 79. Therefore, EPAbelieves thatit is appropriate and authorized under the Act for a State to continue toupdate its growth projections, inventories, modeling analyses, control strategies, etc., and submit these updates as a SIP revision based onnewly available science and technology.

However, section 110(1) ofthe Act governs EPA's review ofa SIP revision from a state that wishes to make changes
to its approved SIP. This section provides thatEPA may not approve a SIP revision ifit will interfere with any applicable requirement concerning attainment and reasonable further progress orany other applicable requirement ofthe Act.' 3 Therefore, if

we receive an attainment demonstration SIP revision from Texas that contains relaxed control measures or the replacement ofexisting control
measures, we would consider the revised plan's prospects for meeting the
current attainment requirements and other applicable requirements ofthe Act. See, the Act section 110(k)(3), UnionElectricv. EPA,427 U.S. 246 (1976) and Train,421 U.S. at 79.

In summary, the State may choose to submit a SIP revision in 2002 or 2003

as it has suggested itmay do. Ifwe receive aSIP revision thatmeets our completeness criteria, we will review it

13

TheSupreme Courtunder the 1970 CAA, observed thatEPA'sjudgment indetermining the approval ofa SIPrevision is to "measure the existing level ofpollution, compare itwith the national standards, and determinetheeffect onthis comparison ofspecified emission modifications." Train at 93. against the statutoryrequirements of section 110(1). Further, the Act requires

us to publish a notice and toprovide for public comment on ourproposed decision. EPA believes thatit is in the
context ofthat future rulemaking, not EPA's current approval, that the commenter's concern regarding the appropriateness of any replacement

measures adoptedby the State should be considered. Comment:The mid-course review process outlined by TNRCC is not a permissible substitute for a currently complete attainment demonstration or adopted enforceable controlmeasures. The mid-course review will delay final approval ofthe SIP until 2004, 10 years after the SIP was required under the Act.

Response:The mid-course review is
not intended as a replacement for a complete attainment demonstration or

as areplacement for adopted control

measures. As provided elsewhere in the responses to comments, EPA believes the State's commitment to adopt additional measures is appropriate. Itis intended toreflect thereality that the modeling techniques andinputs are uncertain. Thus, theprogress of implementing the plan shouldbe evaluated so that adjustments canbe made to ensure theplan is successful. EPA isfully approving the attainment demonstration based on the information currently available. The mid-course review allows the State and EPA an opportunity to consider additional information closer to the attainment date to assess whether adjustments are necessary.

In the case ofTexas, the State has extensive plans to fully evaluate the inputs to the model and the modeling itselfusing the mostup to date information possible. The State will also be evaluating several new control

measures for inclusion in the SIP. We

are fully supportive ofthis continued evaluation ofthe science supporting the plan to reach attainment. Comment:TNRCC has failed to meet its commitment to provide a plan by July 8, 2001. The TNRCC has reneged on previous commitments to model attainment. These demonstrate reasons for our objection to EPA's reliance on commitments.

Response:We donot agree that TNRCC hasreneged onprevious commitments to model attainment. As discussed in the response to comments

onmodeling, using weight ofevidence in conjunction with the model is an appropriate method ofdemonstrating attainment. Further, Texas has made every effort to adopt all ofthe necessary

measures to demonstrate attainment. Therefore, as discussed previously, EPA believes thatitis acceptable to allow additional time for the development of

new programs or measures for a small percentage ofthe needed reductions.

Comment:Texas provided a comment letter on EPA'sDecember 1999 proposal. Inthis letter, Texas explained theirplans to provide the following elements and enforceable commitments by April 2000: (1)A list ofmeasures that couldbe used to achieve attainment (2)

a commitment toprovide anew mobile

source emissions budget using MOBILE6 by May 2004, (3)a reenforcement oftheir previous commitment to adopt the majority of necessary rules for attainment by December 31, 2000, and to adoptthe remainder ifnecessary by July 31, 2001, and (4) a commitment to perform a midcourse review.

Response:TNRCC adopted these elements in April 2000. We are now approving the commitments that are still relevant. (See the final action section).

Comment:One commenter suggested several specific language changes to the enforceable commitments in the Texas SIP.

Response:EPA and TNRCC met and agreed that somebut not all ofthe language changes should be made. The section on changes from the proposal explain these changes. Other specific language changes proposed by the
commenters are not necessary for approvable enforceable commitments.

5.Comments on Motor Vehicle Emissions Budgets

a. Comments onthe July 12, 2001 Proposal

Comment:The commenters raised several questions concerning the Motor Vehicle Emissions Budgets (thebudgets) established in the Houston attainment demonstration SIP. The commenters statedthat thebudgets submitted in the SIP should not be called adequate or be approved by the EPAbecause the attainment demonstration SIP does not provide for attainment. One commenter specifically pointed to the need for adopted and enforceable control

measures.

Response:The rate-of-progress (ROP) budgets for the year of2007 are 79.5 tpd and 156.7 tpd for VOC and NOx, respectively. The commenters support thesebudgets. In addition,these budgets

are identified asthe budgets for the 2007 attainment demonstration SIP which are being approved by the EPA onlyuntil revised budgets pursuant to the State's commitments relating to MOBILE6 and shortfall measures are Federal Register/Vol. 66,

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submitted andwe have found them adequate for transportation conformity
purposes. Approval ofthe attainment budgets isbased on the current control

measures specified in the SIP and the enforceable commitments made for additional controls which will be implemented in the interim period. Because allmeasures which have not yet been adopted are included in written commitments in the SIP, EPA believes that itcan find the budgets adequate. The EPAbelieves that consistency ofthe budgets related to the emissions inventory, and SIP control strategy are demonstrated and meet the requirements of40 CFR 93.118(e). Therefore, the budgets for the attainment demonstration SIP are adequate for transportation conformity
purposes. Also, it should be noted that the conformity rules allow emission reduction credit to be taken for purposes ofconformity determinations for any

measures that havebeen either adopted by the enforcing jurisdiction, included in the applicable implementation plan, contained in a written commitment in the submitted implementation plan, or promulgated by EPA as a federal

measure. See 40 CFR 93.122(a)(3).

As described in the November 3, 1999 memorandum entitled "Guidance on Motor Vehicle Emissions Budgets in One-Hour Ozone Attainment Demonstrations," from Marylin ZawMon, Office ofMobile Sources, to Air Division Directors, Regions I-VI, there

are circumstances in which the EPA could find a SIP's motorvehicle emissions budgets adequate even though additional emission reductions

are necessary in order to demonstrate attainment. Specifically, the EPA's position is that the motor vehicle emissions budgets could be adequate for conformity purposes ifthe State commits to adopt, for the area, measures that will achieve the necessary additional reductions, and the State identifies a menu ofpossible measures that could achieve thereductions without requiring additional limits on highway construction. The HG area's SIP contains such commitments and such a menu.

We believe that the budgets canbe found adequate and approvable because the budgets will not interfere withthe area's abilityto adopt additional

measures to attain the ozone standard andthey are consistent with the attainment demonstration SIP. While the area is adopting its additional
measures, the SIP's budgets will cap motor vehicle emissions andthereby

ensure that the amount ofadditional reductions necessary to demonstrate attainment will not increase. The budgets are consistent with and clearly related to the emissions inventory and the control measures and consistent with attainment. EPA disagrees that the SIP does not provide for attainment. For further explanation ofhow this attainment demonstration SIP as an overall plan provides for attainment please see otherresponses directly relating to the sufficiency ofthe overall attainment plan, control strategy, enforceable commitments, etc. contained in this final action.

Comment:The commenters asserted that further NOx reductions needed for attainment will require additional onroad mobile source controls and these controls will result in alower motor vehicle emissions budget. The
commenters feltthat the budgets established in the SIP are too high and the NOxbudgets should be reduced by 30 or more tpd.

Response:Agency policy for the areas needing additional emission reductions has provided that, in certain cases, EPA may determine thebudget adequate

even when the SIP includes commitments to additional measures. In

aNovember 3, 1999, Memorandum entitled "Guidance on Motor Vehicle Emissions Budgets in One-Hour Ozone Attainment Demonstrations," EPA issued guidance regarding such commitments inthe ozone attainment demonstrations for the HG area as well

as other areas. We indicated that budgets could be based on potential control measures identified in the SIP that, when implemented, would be expected to achieve the emission reductions necessary for attainment of the standard and a commitment to adopt

measures to achieve the reductions. These measures may not involve additional limits on highway construction beyond therestrictions already imposed under the submitted
motor vehicle emissions budget. As long

asthe additional measures do not involve additional limits onhighway construction, allowing new transportation investments consistent with the submittedbudgets will not prevent the area from achieving the additional reductions thatit needs for attainment. This allows the EPA to consider the budgets adequate for transportation conformity purposes. The HG area SIP contains such commitments and measures. The SIP demonstrates that the budgets will not interfere with the HG area's ability to adopt additional

measures to attain.

The budgets established in the SIP are consistent with the process in 40 CFR 93.118(e), andthe EPA does not consider them too high within the
context ofthe ozone attainment demonstration SIP as described above and further documented inthe SIP and EPA'sTSD. The budgets are consistent with and clearly related to the emissions inventory and the controlmeasures and consistent with attainment. Our approval ofthe budgets islimited until revised budgets are submitted andwe have found them adequate for transportation conformity purposes. Texas has committed to revise the budgets relating to MOBILE6 and the shortfall measures. While the list of potential measures does include

measures thatpertain to motor vehicles,

none ofthe measures involves additional limits on highway construction; therefore, iflower budgets do result, the transportation investments will still be consistent with thebudgets and will notprevent the HG area from achieving attainment.

Comment:The motor vehicle emissions budgets are inadequate because they do not provide for all reasonably available control measures to attain the standard as expeditiously as practicable.

Response:The motor vehicle emissions budgets are adequate. The SIP includes allnecessary RACM and provides for expeditious attainment as explained further in the RACM section ofthis action.

b. Comments on July 28, 2001 Supplemental Notice

Comment:One commenter generally supports a policy ofrequiring motor vehicle emissions budgets to be recalculated when revised MOBILE models are released.

Response:The Phase II attainment demonstrations that rely on Tier 2 emission reduction credit contain commitments to revise the motor vehicle emissions budgets after MOBILE6 isreleased.

Comment:The revised budgets calculated using MOBILE6 will likely be submitted afterthe MOBILE5 budgets have already been approved. EPA's policy is that submitted SIPs may not replace approved SIPs.

Response:This isthereason thatEPA proposed inits July 28, 2000 Supplemental Notice ofProposed Rulemaking (65 FR 46383) that the approval ofthe MOBILE5 budgets for conformity purposes would last only until MOBILE6 budgets had been submitted and found adequate. In this
way,the MOBILE6 budgets can apply for conformity purposes as soon as they

are found adequate.

Comment:Ifa State submits additional control measures that affect the motor vehicle emissions budgets but does not submit revised motor vehicle 57180 Federal Register/Vol. 66,

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emissions budgets, EPA should not approve the attainment demonstration.

Response:EPA agrees. The motor vehicle emissions budgets in the HG

area attainment demonstration reflect the motor vehicle control measures in the attainment demonstration. In addition,Texas wouldbe required to submit anew budget ifany adopted

measures would change thebudget, and Texas has committed to submit a new budget ifthey adopt additional control

measures that reduce on-road vehicle emissions.

Comment:EPA should make it clear that the motor vehicle emissions budgets tobe used for conformity
purposes will be determined from the total motor vehicle emissions reductions required in the SIP, even ifthe SIP does
not explicitly quantify a revised motor vehicle emissions budget.

Response:EPA will not approve SIPs without motor vehicle emissions budgets thatare explicitly quantified for conformity purposes. The HG attainment demonstration contains explicitly quantified motor vehicle emissions budgets which EPAhas found adequate and approvable.

Comment:Ifa state fails to follow through on its commitment to submit the revised motor vehicle emissions budgets using MOBILE6, EPA could make a finding offailure to submit a portion ofa SIP, which would trigger a sanctions clock under section 179.

Response:Ifa state fails to meet its commitment, EPA could make a finding offailure to implement the SIP, which would start a sanctions clock under section 179 ofthe Act.

Comment:Ifthe budgets recalculated using MOBILE6 are larger than the MOBILE5 budgets, then attainment shouldbe demonstrated again.

Response:As EPA proposed in its December 16, 1999 notices, we will work with States on a case-by-case basis ifthe new emissions estimates raise issues about the sufficiency ofthe attainment demonstration.

Comment:Ifthe MOBILE6 budgets are smaller than the MOBILE5 budgets, the difference between the budgets should
not be available for reallocation to other

sources unless air quality data show that the area is attaining, and a revised attainment demonstration is submitted that demonstrates that the increased emissions are consistent with attainment and maintenance. Similarly, the MOBILE5 budgets should not be retained (while MOBILE6 isbeing used for conformity demonstrations) unless the above conditions are met.

Response:EPA agrees thatif recalculation using MOBILE6 shows lower motor vehicle emissions than MOBILE5, then these motor vehicle emission reductions cannot be reallocated to other sources orassigned
to the motor vehicle emissions budget unless the area reassesses the analysis in its attainment demonstration and shows that itwill still attain. In other words, the area must assess howits original attainment demonstration is impacted by using MOBILE6 vs. MOBILE5 before it reallocates any apparent motor vehicle emission reductions resulting from the use ofMOBILE6. In addition, Texas will be submitting new budgets based onMOBILE6 so the MOBILE5 budgets will not be retained in the SIP indefinitely. Comment:We received a comment on whether the grace period before MOBILE6 is required in conformity determinations willbe consistent with the schedules for revising SIP motor vehicle emissions budgets ("budgets") within 1or 2years ofMOBILE6's release.

Response:This comment is not germane to this rulemaking, since the MOBILE6 grace period for conformity determinations is not explicitly tiedto EPA's SIP policy and approvals. However, EPA understands that a longer grace period would allow some areas to better transition to new MOBILE6 budgets. EPA is considering the maximum 2-year grace period allowed by the conformity rule, and EPA will address this in the future when the final MOBILE6 emissions model andpolicy guidance is released. Comment:One commenter asked EPA
to clarify in the final rule whether MOBILE6 will be required for conformity determinations once new MOBILE6 budgets are submitted and found adequate.

Response:This comment is not germane to this rulemaking. However, it is important to note that EPAintends to clarify its policy for implementing MOBILE6 in conformity determinations when the final MOBILE6 model is released. EPA believes thatMOBILE6 shouldbe used in conformity determinations once new MOBILE6 budgets are found adequate. Comment:One commenter did not prefer the additional option for asecond
year before the state has torevise the conformity budgets withMOBILE6, since new conformity determinations and new transportation projects could be delayed in the second year.

Response:EPA proposed the additional option toprovide further flexibility in managing MOBILE6 budget revisions. The supplemental proposal did not change the original option to revise budgets within one year of MOBILE6's release. State andlocal governments can continue to use the 1- year option,ifdesired, or submit anew commitment consistent with the alternative 2-year option. EPA expects that state andlocal agencies have consulted on which option is appropriate and have considered the impact on future conformity determinations. Texas has committed to revise its budgets within 2years of MOBILE6's release for the HG area. Texas has committed thatifa transportation conformity analysis is to be performed between 12 months and 24 months after the MOBILE6 official release, transportation conformity will
notbe determined until Texas submits

an MVEB which is developed using MOBILE6 and which we find adequate.

6. Comments on RACM

a. Comments onDecember 16, 1999 Proposal

Comment:Several commenters stated in response to the December 16, 1999 proposed approval/proposed disapprovals for the severe areas and certain serious areas thatthere is no evidence in several states thatthey have adopted reasonably available control

measures (RACM) orthat the SIPs have provided for attainment as expeditiously aspracticable. Specifically, the lack ofTransportation Control Measures (TCMs) was cited in several comments, but potential stationary source controls were also covered. One commenter stated that mobile source emission budgets in the plans are by definition inadequate because the SIPs donot demonstrate timely attainment or contain the emissions reductions required for all RACM. That commenter claims that EPAmay not find adequate a motor vehicle emission budget (MVEB) thatis derived from a SIP that is inadequate for the purpose for which it is submitted. The commenter alleges thatnone ofthe MVEBs submittedby the states thatEPA is considering for adequacy is consistent with either the level ofemissions achieved byimplementation of all RACM nor are they derived from SIPs thatprovide for attainment. Some
commenters stated that for measures that are not adopted into the SIP, the State mustprovide ajustification why they were determined to not be RACM.

Response:The EPA reviewed the November 1999 submission for the HG

area and determined that it did not include sufficient documentation concerning available RACM measures. For all ofthe severe areas for which EPA proposed approval in December 1999, EPA consequently issuedpolicy guidance memorandum to have these

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States address the RACM requirement through an additional SIP submital. (Memorandum ofDecember 14, 2000, from John S. Seitz, Director, Office of Air Quality Planning and Standards, re: "Additional Submission on RACM from States with Severe 1-hour Ozone Nonattainment Area SIPs."

On May 30, 2001, TNRCC proposed a RACM analysis which we proposed to approve onJuly 13, 2001 through parallel processing. The State finalized its RACM analysis on September 26, 2001. The Governor submitted this final RACM analysis in a letter dated October 4, 2001. Based onthis SIP supplement, EPA concluded thatthe SIP for the HG

area meets the requirement for adopting RACM.

Section 172(c)(1) ofthe Act requires SIPs to contain RACM and provides for

areas to attain as expeditiously as practicable. EPAhas previously provided guidance interpreting the requirements of 172(c)(1). See 57 FR 13498, 13560 (April 16, 1992). In that guidance, EPAindicated its interpretation thatpotentially available

measures that would not advance the attainment date for an area would not be considered RACM. EPA also indicated in that guidance that states should consider allpotentially available

measures to determine whether they

were reasonably available for implementation in the area, and whether they would advance the attainment date. Further, states should indicate in their SIP submittals whether

measures considered were reasonably available or not, and ifmeasures are reasonably available they must be adopted as RACM. Finally, EPA indicated that states could reject

measures as not being RACM because they would not advance the attainment date, would cause substantial widespread and long-term adverse impacts, would be economically or technologically infeasible, or would be unavailable based on local considerations, including costs. The EPA also issued a recent memorandum re-confirming the principles in the earlier guidance, entitled, "Guidance on the Reasonably Available Control Measures (RACM) Requirement and Attainment Demonstration Submissions for Ozone Nonattainment Areas." John S. Seitz, Director, Office ofAir Quality Planning and Standards. November 30, 1999. Web site: http://www.epa.gov/ttnl oarpg/tlpgm.html.

EPA evaluated the Texas RACM demonstration and performed an additional analysis ofTCMs as described in the TSD for the July 12, 2001 proposed approval. Specific
comments on the RACM demonstration are addressed in later responses to comments.

Although EPA does notbelieve that section 172(c)(1) requires implementation of additional measures for the HG area, this conclusion isnot necessarily valid for other areas. Thus,

a determination ofRACM isnecessary

on a case-by-case basis and will depend

onthe circumstances for the individual

area. 14In addition, ifin the future EPA

moves forward to implement another

ozone standard, this RACM analysis would not control what is RACM for these or any other areas for that other

ozone standard.

Also, EPA has long advocated that States consider the kinds ofcontrol

measures thatthe commenters have suggested, andEPA has indeed provided guidance onthose measures. See, e.g., http://www.epa.gov/otaql transp.htm.In order to demonstrate that they will attain the 1-hour ozone NAAQS as expeditiously aspracticable,

some areas may need to consider and adopt anumber ofmeasures-including the kind that Texas itself evaluated in its RACM analysis-that even collectively do not result in many emission reductions. Furthermore, EPA encourages areas to implement technically available and economically feasible measures to achieve emissions reductions in the short term-even if suchmeasures donot advance the attainment date-since such measures will likely improve air quality. Also,

over time, emission control measures that may notbe RACM nowfor an area may ultimately become feasible for the

same area dueto advances in control technology ormore cost-effective implementation techniques. Thus, areas should continue to assess the state of control technology asthey make progress toward attainment and consider new controltechnologies that
may in fact result in more expeditious improvement in air quality. The mid

course review process outlined by Texas in Chapter 7ofthe SIP contains the State's commitment to continue to evaluate new technologies as potentially RACM, for inclusion later in the plan. The TNRCC adopted an enforceable commitment to submit a revised SIP no later than May 1, 2004, addressing any

new information including an "ongoing
assessment ofnew technologies and innovative ideas toincorporate into the plan."

Because EPA is finding thatthe SIP meets the Clean Air Act's requirement

14See, Oberv.EPA, 84 F.3d 304, 311 (9th cir. 1996) (citing the General Preamble, 57Fed.Reg. at 13560 (April 16, 1992) which held that EPA didnot abuse discretion when changing the interpretation of the RACM provisions ofthe Act. for RACM and thatthere are no additional reasonably available control

measures that can advance the attainment date, EPA concludes thatthe attainment date being approved is as expeditiously aspracticable

EPA previously responded to comments concerning the adequacy of the MVEBs submitted with the November 1999 SIP submission when EPAtook final action determining the budgets (associated with that 1999 plan) adequate and does not address those issues again here. The responses are found athttp://www.epa.gov/omsl transp/conform/pastsips.htm. It should be noted, since thattime, EPAhas found the MVEBs in the November 1999 HG attainment demonstration SIP inadequate. (66 FR 35420, July 5, 2001) We are now approving andfinding adequate through parallel processing the budgets finally submittedby Texas in a letter dated October 4, 2001. The section ofthis notice on MVEBs explains why the budgets are adequate and indicates thatthe budgets are consistent with the conclusion thatthe SIP contains all
necessary RACM for expeditious attainment.

b. Comments on July 12, 2001 Proposal
Comment:EPA cannotinvent rationales forthestates:EPA concedes thatTexas failed to adequately justify rejection ofRACMsidentified as
measures to be considered in the future,

or provides its own rationales for why Texas mighthave rejected other RACMs
notincluded on the list to be considered in the future. The Act andEPA guidance require the State toperform the required RACM analysis. EPA's role is limited to reviewing what the states have submitted, and approving or disapproving it. 42 U.S.C. 7410(k)(3); RiversideCement Co.v. Thomas, 843 F.2d 1246 (9thCir. 1988). EPA "may either accept or reject what the state proposes; but EPA may not take a portion ofwhat the state proposes and amend the proposal ad libitum." Id.If
states are going toreject control
measures, their decision to do so and the rationale therefore must be subject
to notice and hearing atthe state and local level. This comment is essentially the same as a comment provided on EPA's October 12, 2000 Notice of Availability proposing action regarding RACM for the three serious areas of Atlanta, Washington DC and Springfield, MA.

Response:Inthe case ofthe HG SIP, Texas has performed an analysis of whether all RACM were included in the SIP. Basedupon its analysis, the State concluded that one additional measure notincluded in the December 2000 SIP 57182 Federal Register/Vol. 66,

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submission, control ofsmall liquid fired engines, was reasonably available and therefore proposed and adopted a rule
to control these sources. Otherwise, the State concluded all RACM were in place. The public did have a chance to comment at the State level on the State's conclusion that no additional RACM

were required. The EPAbelieves that the State analysis was adequate. We reviewed the State's proposed analysis and discussed our evaluation ofit inthe TSD for our July 2001 proposed action

onthe State's RACM analysis. The EPA did not amend the SIP; EPA evaluated the State's analysis and for transportation control measures, supplemented the State's rationale with additional thoughts on whywe believed the RACM analysis was adequate. We explain in the TSD why we agree with the State thatno additional measures

are RACM for the HG area and therefore the RACM requirement ofthe Act is
met.

The commenter cites Riverside Cementfor the proposition that EPA
cannot perform an analysis ofwhether the State's plan complies with the Act's RACM requirement. The EPAbelieves that the holding ofthat case is inapplicable to these facts. In Riverside Cement,EPA approved a control requirement establishing an emission limit into the SIP and disregarded a contemporaneously-submitted contingency that would allow the State
to modify the emission limit. Thus, the
court concluded that EPA "amended" the State proposal by approving into the SIP something different than what the State had intended. 843 F.2d at 1248. In the present circumstances, EPA did not attempt to modify a substantive control requirement ofthe submittedplan. Rather, EPA evaluated the State's analysis plus performed additional analysis to determine ifthe plan, as submitted, fulfilled the substantive RACM requirement ofthe Act. As a general matter, EPAbelieves thatStates shouldperform their own analyses of RACM (aswell as submitting other supporting documents for the choices they make), which is what Texas did in this instance for the Houston area. The
statute places primary responsibility on the States to submit plans that meet the Act's requirements. However, nothing in the Act precludes EPAfrom performing those analyses, and the Act clearly provides thatEPA must determine whether the State's submission meets the Act's requirements. Under that authority, EPAbelieves thatit is appropriate, though not mandated, that EPA perform independent analyses to evaluate whether a submission meets the requirements ofthe Act ifEPA believes such analysis is necessary. The EPA has not attempted to modify the State's submission by either adding or deleting a substantive element ofthe submittedplan. Byvirtue ofthe State's analysis andEPA's evaluation ofit, and EPA's supplemental RACM analysis for transportation control measures, EPA has concluded thatthe State's submission contains controlmeasures sufficient to meet the RACM requirement. Comment:Inappropriate grounds for rejectingRACM. The commenter claims that EPA's bases for rejecting measures

asRACM areinappropriate considerations: (a) The measures are "likely to require an intensive and costly effort for numerous small area sources"; or (b)the measures "do not advance the attainment dates" for the

areas. 65 FR 61134. Neither ofthese grounds are legally orrationally sufficient bases for rejecting control

measures. This comment is essentially the same as a commentprovided on EPA's October 12, 2000 Notice of Availability proposing EPA's RACM action for the three areas ofAtlanta, Washington D.C. and Springfield, MA.

Response:The EPA's approach toward the RACM requirement is grounded in the language ofthe Act. Section 172(c)(1) states that a SIP for a nonattainment area must meet the following requirement, "In general.- Such plan provisions shall provide for the implementation ofall reasonably available control measures as expeditiously aspracticable (including suchreductions in emissions from existing sources in the area as maybe obtained through the adoption, at a minimum, ofreasonably available control technology) and shall provide for attainment ofthe national primary ambient air quality standards." [Emphasis added.] The EPAinterprets this language astying the RACM requirement to therequirement for attainment ofthe national primary ambient air quality standard. The Act provides thatthe attainment date shall be "as expeditiously aspracticable but

no later than * * *"the deadlines specified in the Act.EPA believes that the use ofthe same terminology in conjunction with the RACM requirement serves the purpose of specifying RACM asthe way of expediting attainment ofthe NAAQS in advance ofthe deadline specified in the Act. As statedin the "General Preamble for the Implementation ofTitle I ofthe Clean Air Act Amendments of1990 (General Preamble)" (57 FR 13498 at 13560, April 16, 1992), "The EPA interprets this requirement toimpose a duty on all nonattainment areas to consider all available control measures and to adopt and implement such

measures as are reasonably available for implementation in the area as components ofthe area's attainment demonstration." [Emphasis added.] In other words, because ofthe construction ofthe RACM language in the Act,EPA does not view the RACM requirement as separate from the attainment demonstration requirement. Therefore, EPAbelieves thatthe Act supports its interpretation that measures may be determined tonot be RACM ifthey do
not advance the attainment date. In addition,EPA believes that itwould be unreasonable to require implementation ofmeasures that would not in fact advance attainment. See 57 FR 13560. EPAhas consistently interpreted the Act

as requiring only such RACM as will provide for expeditious attainment since the agency first addressed the issue in guidance issued in 1979. See 44 FR 20372, 20375 (April 4, 1979).

The term "reasonably available control measure" isnot actually defined in the definitions inthe Act. Therefore, the EPA interpretation thatpotential

measures maybe determined not to be RACM iftheyrequire an intensive and costly effort for numerous small area

sources isbased onthe common sense meaning ofthe phrase, "reasonably available." Ameasure thatis reasonably available is one that is technologically and economically feasible andthat can be readily implemented. Ready implementation also includes consideration ofwhether emissions from small sources are relatively small and whether the administrative burden,
to the States andregulated entities, of controlling such sources was likelyto be considerable. As stated in the General Preamble, EPAbelieves that States can reject potential measures based on local conditions including cost (57 FR 13561). See Oberv.EPA, 84 F3d at 312 (9th Circuit 1996).

Also, the development ofrules for a large number ofvery different source categories of small sources for which little control information may exist will likely take much longer than development ofrules for source categories for which control information exists or that comprise a smallernumber oflarger sources. The longer time frame for development ofrules by the State would decrease the possibility thatthe emission reductions from the rules would advance the attainment date. Texas has determined andwe agree that such additional measures inthe HG area could notbe developed soon enough to advance the attainment date.

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Comment:Failureto quantify reductionsneededto attainsooner: Even ifadvancement ofthe attainment date were a relevant test for RACM, EPA has failed torationally justifyits claim that additional control measures would
not meet thattest. To begin with, neither the Agency nor the states have quantified in amanner consistent with EPA rules and guidance the emission reductions thatwould be needed to attain the standard prior to achievement ofemission reductions required under the NOx SIP call. Nowhere isthere an analysis that shows what it would take
to attain in 2004, 2005, 2006 or 2007. This comment generally repeats a commentprovided on EPA's October 12, 2000 Notice ofAvailability proposing EPA's RACM action for the three areas ofAtlanta, Washington DC and Springfield, MA.

Response:First, note that while the
commenter makes reference to the NOx SIP call, Texas is not included in the mandatory NOx SIP call. However, it should alsobe noted that even though Texas was not included, Texas adopted control measures for regional NOx emissions reductions (includingin attainment areas) as part ofthe HG attainment demonstration SIP, in a

manner similar tothose undertaken by the states included in the NOx SIP call. These regional reductions will occur by May 2003 in Texas. InMichiganv. EPA, 200 WL 1341477 (D.C. Cir. 2000) (order denying motion to stay mandate pending appeal from 213 F.3d 663(D.C. Cir. 2000)) the court held the NOx control measures could not be required by EPA until May 31, 2004 in order to allow sources in subject States 1309 days from the date ofthe court order to implement the measures asprovided in the original rule. These regional

measures in Texas are thus being implemented on a more expeditious schedule and as expeditiously as is practicable.

Further, it wouldbe futile for TNRCC
to attempt to quantify the emission reductions thatcould be possible for the HG area to attain prior to the 2007 deadline. With all ofthe adopted control measures, and with the enforceable commitments to achieve the additional 56 tons/day ofNOx emission reductions needed for attainment, plus the necessary reliance upon Federal
measures, including the amount of cleaner on and off-road vehicles that will enter the fleet, there are simply no additional measures that EPAis aware ofthat are reasonably available or economically feasible that couldbe implemented, much less implemented in time, to achieve attainment in advance ofwhen the measures are being implemented in this plan.

The following respond tothe issue of whether additional specific potentially available measures are RACM for the HG area. Comment:Inadequate RACM analysis: EPA's RACM analysis is grossly inadequate in several key respects. Commenta:EPA's analysis fails to provide the technical basis and calculations bywhich itdeveloped its emission reduction estimates for various

measures. EPAfailed to provide citations to the literature regarding estimates ofemission reductions for various TCMs. EPAfailed to specify the level ofimplementation assumed for

some ofthe TCMs in the analysis.

Responsea:First, note that EPA's analysis contained in the TSD was intended to evaluate andin one instance supplement the TNRCC analysis and conclusion that all RACM hadbeen adopted. We evaluated the TNRCC's technical basis and calculations for the emission reduction estimates for controls possible for all ofthe source categories in the emission inventory. Regarding the TCM category, we provided additional technical analysis and calculations. The commenter apparently believes EPA's analysis of potential TCMs as not being RACM for the HG area is insufficient, however. EPA's technical basis for the supplemental TCMRACM analysis and the assumptions used in the calculation ofestimated emission reductions from additional potential TCMs were derived from areview ofthe literature on the implementation and effectiveness of TCM's. 15 The TCMs evaluated depend
onthe level ofimplementation. Implementation variables, representing levels ofimplementation effort, are implicit in therange ofeffectiveness for each category ofTCM. EPA does not believe it isnecessary, or even practically possible, to evaluate every explicit variation ofTCM's in order to adequately determine ifitis reasonably available. In summary, the technical basis is provided in Appendix B to the TSD and Chapter 7ofTNRCC's SIP. In conclusion, we determined that at a reasonable level ofimplementation, all potential categories ofTCMs taken together would not be sufficient to advance the attainment date.

Commentb:EPA's analysis looks at only a smalluniverse ofpotential

15Transportation Control Measures: State Implementation Plan Guidance, US EPA 1992; Transportation Control Measure Information Documents, US EPA 1992; Costs andEffectiveness of Transportation Control Measures: AReview and Analysis ofthe Literature, National Association of Regional Councils 1994. measures, and does not evaluate all of the measures identified in public
comment and other sources. Several
commenters suggested that avariety of

measures were Reasonably Available and shouldbe included in the SIP.

Responseb:Itis EPA's position that the TNRCC's RACM analysis identified and addressed allpotential categories of stationary and mobile sources inthe HG
area, that could provide additional emission reductions, and measures that might be considered RACM. The EPA believes not only thatTexas identified and addressed allthe potential source categories but that it also addressed identified measures raised by
commenters. The TNRCC considered a wide range ofpotential measures, including all measures adopted in other

severe and serious areas andthe California South Coast's extreme attainment demonstration SIP.

The following addresses specific

measures that were suggested by
commenters.
VOCControlMeasures

Comment:An adequate plan would emphasize reductions in allprecursors notjust one.

Response:The two primary
precursors to ozone are Volatile Organic Compounds (VOCs) and Oxides of Nitrogen (NOx). These classes of chemicals react in the atmosphere in the
presence ofsunlight to form ozone. Under 182(c)(2), States mustbase their attainment demonstration on photochemical modeling or any other analytical method determined by EPAto be atleast as effective. Modeling is generally regarded as the most reliable basis for ascertaining which precursors shouldbe emphasized for control in order to obtain a reduction in ozone concentration levels. In the HG area, the photochemical modeling indicates that NOx emission reductions are much

more effective in reducing ozone and thus, NOx emission reductions have appropriately been the emphasis in the plan's control strategy. As discussed further in the next comment/response, EPA agrees that no additional VOC

measures would advance the attainment date.

Future studiesmay revise the emphasis ofthe control strategy. EPAis

aware that some ofthe preliminary results ofthe Texas Air Quality Study 2000 indicate thatreactive VOC's may need tobe considered for additional control. Further, there is no clear evidence, atthis time, thatindicates that the control of otherpollutants, such as particulate matter, would help in reducingthe ozone concentration levels in the HG area. 

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Comment:A commenter stated that TNRCC has not developed adequate VOC controls. The document presents evidence that categories ofemissions representing the "vast majority" ofpoint

source emissions are regulated but does
not determine whether in fact the facilities are regulated. The commenter felt the proper analysis would present

an inventory ofcontrolled emissions and compare it with total emissions.

Response:EPA believes the analysis in Chapter 7ofthe SIP and in the TSD does demonstrate further VOC controls

are not required as RACMbased on the information currently available. This conclusion isbased on three factors. First, EPA believes Texas has regulated allmajor sources ofVOCs in the HG

area to at least a RACT level. We took action on these RACT rules in separate Federal Register actions. We found that the State had implemented RACT on all major sources in the HG area except those that were tobe covered by postenactment Control Technique Guidelines (CTGs)(60 FR 12437, March 7, 1995). Since thattime many expected CTGs were issued as Alternative Control Technique documents-ACTs. Of the expected CTGs and ACT's, the HG area had major sources in the following categories; batch processing, industrial wastewater, reactors and distillation, and wood furniture. We have approved

measures for all ofthese categories as meeting RACT. Batch Processing-July 16, 2001 66 FR 36913 Industrial Wastewater-December 10, 2000 65 FR 79745 Reactors and Distillation-January 26, 1999, 64 FR 3841 Wood Furniture-October 30, 1996, 61

FR 55894 Further, EPA agrees with the conclusion drawn by Texas in its RACM analysis that the majority ofVOC point

source emissions (whether emitted from major sources or minors) are already regulated by therules contained in Chapter 115 ofthe State Implementation Plan. The State's VOC rules gobeyond RACT level controls for some categories such as fugitive emissions and gasoline loading emissions. EPAhas approved Chapter 115 as meeting the RACT requirements.

Second, because ofthe particular chemistry in the HG area VOC controls

are not nearly as effective as NOx controls in reducing ozone. TNRCC has demonstrated through modeling that 12-15 tons/day ofVOC emission reductions are needed to achieve the

same ozone benefit as one ton/day of NOx emission reductions as shown in Chapter 7ofthe October 2001 SIP revision. Thus, theparticular chemistry in the HG area makes additional ozone benefits very difficult to achieve through VOCreductions. In fact, modeling indicates that ifall manmade VOC's were reduced to zero, the area would not reach attainment.

Third, Texas analyzed the controlled VOC inventory to determine ifany
source categories remained where additional VOC controls couldbe implemented that could advance the attainment datein light ofthe modeling evidence. As discussed previously, EPA does not believe that section 172(c)(1) requires implementation ofpotential RACM measures that will not be sufficient to allow the area to achieve attainment in advance offull implementation of all otherrequired
measures, in this case, full implementation ofthe NOx controls called for in theplan including the 56 tons/day NOxreductions called for by the enforceable commitments. In the TNRCC analysis, aVOC source category had to have at least 12-15 tons per day ofemissions to warrant further analysis. This level was chosen because itmight be theoretically possible to reduce these categories enough to achieve as much as the equivalent ofone ton/day ofNOx reduction. Given that the final 121 tons/ day ofpoint source reductions, out ofa total ofalmost 600 ton/day ofemission reductions, will not be implemented until spring 2007 emission reductions from measures that achieve less than the equivalent one ton/day ofNOx reductions even ifcombined with several measures of similar magnitude
cannot advance the attainment date. The TNRCC presents in the SIP Narrative, Chapter 7, a summary ofthe inventory that reflects the controlled level of emissions. Based onthe above screening level one category, storage tanks, was examined for additional control. Based

on controls in the Alternative Technique Guideline, only 2.2 tpd of additional reduction in VOC could be achieved which is farless than the equivalent ofone ton/day ofNOx reduction and therefore would not advance attainment.

Texas also reviewed allVOC area

source (as opposed to points source) categories to see ifany categories were emitting greater than 11 tons/day in emissions. While some area source categories emitted more than 11 tons/ day, these categories already are subject
to rules. TNRCC did not believe additional controls on already regulated categories would be reasonable in light ofthe amount ofVOC reductions needed to achieve ozone benefits.

In summary, the modeling indicates that ittakes substantial VOC emission reductions to achieve ozone reductions in the HG area. Already allmajor

sources ofVOC's in HG have RACT in place.Emission reductions beyond RACT on major VOC sources maybe achievable but could not achieve sufficient ozone benefit for the HG area to achieve attainment in advance ofthe

measures inthe SIP we are approving today. Significant area source categories

are alsoregulated. Therefore, no emission reduction measures were identified that would achieve attainment in advance ofthe measures contained in the plan.

Comment:For States that need additional VOC reductions, this
commenter recommends a process to achieve these VOC emission reductions, which involves the use ofHFC-152a (1,1 difluoroethane) as the blowing agent in manufacturing ofpolystyrene foam products such as food trays and egg cartons. HFC-152a could be used instead ofhydrocarbons, a known pollutant, as ablowing agent. Use of HFC-152a, which is classified as VOC exempt, would eliminate nationwide the entire 25,000 tons/year ofVOC emissions from this industry.

Response:This comment was not provided to TNRCC. EPAhas met with the commenter and has discussed the technology described by the company to reduce VOC emissions frompolystyrene foamblowing throughthe use ofHFC152a (1,1 difluoroethane), which is a VOC exempt compound, as a blowing agent. Since the HFC-152a isVOC exempt, its use would give aVOC reduction compared tothe use ofVOCs such aspentane or butane as ablowing agent. However, EPA has not studied this technology exhaustively. Itis each State's prerogative to specify which

measures itwill adopt in order to achieve the additional VOC reductions itneeds. In evaluating the use ofHFC152a, States may want to consider claims that products made with this blowing agent are comparable in quality
to products made with otherblowing agents. Also the question ofthe over-all long term environmental effect of encouraging emissions offluorine compounds would be relevant to consider. This is atechnology which States may want to consider, but ultimately, the decision ofwhether to require this particular technology to achieve the necessary VOC emissions reductions must be made by each affected State. Finally, EPA notes that underthe significant new alternatives policy (SNAP) program, created under CAA §612, EPAhas identified acceptable foam blowing agents many of which are not VOCs (http:// www.epa.gov/ozone/title6/snap/).

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In the case ofthe HG area, the analysis in chapter 7did not show this category ofemissions as one with more than 11 tons/day ofemissions so, as discussed in a previous comment, there
cannot possibly be enough emission reductions from this category to achieve sufficient ozone benefit for the HG area to reach attainment in advance ofthe full implementation ofthe measures in this SIP. Comment:Two commenters suggested that a portable gasoline container buy back program shouldbe adopted in the HG area tointroduce gasoline containers meeting the California Air Resources Board (CARB) standards to the HG area. It was estimated based on CARB experience that controls on containers would be able to achieve 23 tpd ofVOC reductions in the HG area.

Response:This measure was suggested to TNRCC as a replacement to their Commercial Lawn Service operating restrictions. TNRCC evaluated the measure and decided the measure would not achieve equivalent reductions tothe operating restrictions.

EPA is aware that CARB has projected significant emission reductions from this measure. This isbased on their studies ofthe emissions from evaporation and spillage from gasoline containers in California. TNRCC in their RACM analysis ofthe HG emission inventory, however, did not identify this source category, i.e., gasoline containers, ashaving the same level of emissions and therefore the potential to achieve the same level ofemission reductions as was found in California. TNRCC used EPA approved methodology to develop its inventory. EPA concludes, based on the record supporting the State's RACM analysis, that Texas used appropriate assumptions for determining emission reductions from this measure. Based on the emission estimates contained in the approved inventory, EPA agrees with Texas thatthis measure cannot be considered RACM atthis time because the measures cannot achieve sufficient

ozone benefit for the HG area to achieve attainment in advance ofthe full implementation ofthe measures in the SIP we are approving today. Future study ofthis portion ofthe inventory utilizing information developed by CARB may indicate thatmore emissions arise from this category in the HG area andthis measure may have tobe revisited. Comment:One commenter pointed to the results ofthe Channelview Source Reduction Project as evidence that significant levels ofVOC emission reductions canbe achieved. The Channelview Project resulted in the following improvements: Additional gas flow meters, reduced flaring ofoff-spec product, elimination offlaring ofextracontractproduct, improved flare systems, and prevention ofunnecessary shutdowns.

Response:The November 14, 2000 "Source Reduction Project, Report on Phase I" documents the cooperative effort between the Community Advisory Panel and Lyondell andEquistar (CAPLE) to reduce air emissions atthese companies. It documents several improvements and significant emission reductions thathave been made atthese plants through focusing on source reduction. It isnot clear from the report, however, whether ornot the measures instituted bythese companies have general applicability within the chemical industry. The measures taken by these companies toreduce emissions have promise asmeasures that can achieve emission reductions throughout the HG area but it will take further study by us and the State to determine ifthey

canbe appliedto other facilities, are technically and economically feasible and achieve reductions that could advance attainment, andthus can be considered potential RACM for the HG

area. Therefore, atthis time, EPA cannot find these measures feasible. EPA agrees with Texas that this type ofproject
cannot currently be considered RACM.

Comment:One commenter suggested that the State shouldreduce fugitive VOC emissions by90%.

Response:The commenter did not suggest howthe 90% emission reduction from fugitive VOC emissions couldbe achieved. EPA isnot aware of
any technology or programs thathave been demonstrated to achieve this level ofreductions. TNRCC already has in place a leak detection andrepair requirement that goes beyond the levels in EPA's control technique guidelines to control refinery and chemical plant fugitive emissions.EPA has approved this requirement for fugitive emissions

asmeeting the RACT requirement for the HG area. Based on the above, EPA concludes thatthis measure is not technically feasible at this time. Upset Emissions
Comment:TNRCC has failed to adopt reasonably available control measures for controlling upset emissions because the TNRCC rules fail to meet at a minimum EPA guidance for upset emissions. The rule violates the requirements regarding creating an affirmative defense because (1)it is a blanket exemption, (2)it covers sources whose individual contributions of pollutants have the potential to cause an exceedence, (3)it covers both penalties and injunctive relief, and (4) it couldbe interpreted as barring citizen and/or EPA enforcement action.

Response:On November 28, 2000, EPAissued a direct final approval of a revision to the Texas SIP addressing

excess emissions from start-up, shutdown, malfunction and maintenance. 65 FR 70792. In that notice, EPA explained thatit determined thatthe rule was consistent with the EPA guidance referenced by the commenter, "State Implementation Plans: Policy Regarding Excess Emissions During Malfunctions, Startup and Shutdown," September 20, 1999. This determination included EPA's conclusion thatthe Texas rule does not provide an exemption from compliance for periods of excess emissions. No adverse comments were received and EPA's approval became effective on January 29, 2001. Throughthe proposed actions onwhich EPAis taking today, EPAis notre-opening its past approval ofSIP requirements. Thus, the
commenters attempt to nowraise issues about whether EPA's approval ofthat rule was appropriate are untimely.

PointSourceNOx Controls

Comment:The Phase II NOxlimits agreed to by OTC States are clearly RACM for all areas, asthey are widely in effect. States thathave not adopted suchmeasures have not adopted enforceable NOxRACT limits for all relevant facilities. It is not sufficient for States to assert thatthey will adopt additional NOx controls ifneeded.

Response:That the OTC states have implemented the OTC Phase II NOx limits does not automatically prove that these limits are RACM for all areas. EPA concedes thatthe wide-spread adoption ofsuch programs and EPA's own analysis ofNOx control onlarge stationary sources wouldwarrant consideration whether such limits meet the technological and economical feasibility criteria ofRACM and would advance attainment. However, such an analysis is not relevant in the case ofthe HG ozone nonattainment area. Texas has already adopted programs for the HG area to implement limits that are

more stringent than the OTC Phase 11 limits.

Comment:Acommenter suggested energy efficiency improvements are not justfor residential and commercial buildings and suggested savings could be achieved bymore efficient motor and drive systems.

Response:We agree that improved energy efficiency is a desirable method ofreducing air emissions. There are difficulties in including suchmeasures in a SIP because itis not always clear

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where the benefits ofthe reduced electrical demand will occur. The reduced demand couldresult in emission reductions outside the HG

area. There are initiatives in Texas to reduce growth in demand in Texas such

as the State widebuilding codes established by Senate Bill 5.The State ofTexas has committed to further examine the benefits and methods of improving energy efficiency for possible inclusion in the SIP at the mid-course review. EPA concludes that there is not enough information at this time to determine the appropriate emission benefits and therefore energy efficiency
cannot currently be considered RACM.

Comment:Just as Integrated Resource Planning (IRP) for electric utilities resulted in demand side management programs that conserved electricity, IRP for natural gas utilities will have the

same impact on conserving natural gas usage and resulting emissions. A number ofstates have effectively implemented IRP for natural gas.

Response:As noted above, EPA agrees that improved energy conservationregardless ofthe form ofenergy-is a desirable method ofreducing air emissions. Since such measures would likely have to rely on voluntary efforts, the State would have to estimate the effect on emission reductions that would result. Putting in place even a voluntary effort to conserve natural gas that could be quantified in terms ofits emission reduction benefits would likely require a significant amount of time. EPAis aware thatthe State had devoted a tremendous amount of

resources in developing and adopting the number ofcontrol measures thatit did for the HG area's one-hour ozone SIP, and even with thathad to commit
to fill a shortfall of 56 tons/day ofNOx reductions. EPAbelieves itis unlikelygiven the time spent on the bulk of the SIP-that the State had the time to develop such a quantifiable voluntary program that would haveyielded enough NOx reductions to advance the attainment date. Furthermore, it appears unlikely that such a quantifiable program couldbe put into place in sufficient time to advance the attainment date given the resources that the State will have to spend over the
next several years simply developing and adopting the emission controls to achieve the 56 tons/day NOx emission reductions. Therefore, EPA believes that this measure is not RACM, at this time, for the HG area. Comment:StringentStandards for Stationary DieselEngines:The TNRCC should establish the same requirements for new and existing stationary diesel engines in the HG area that are not used exclusively during infrequent emergency orbackup situations.

Response:The State received a similar
comment. In their response they explained thatbased oninformation in the emissions inventory and contact with diesel engine vendors and others familiar with the stationary diesel engines in the HG area, the State is

unaware ofany existing stationary diesel engines that are being operated in situations otherthan generation of electricity in emergency situations or operation for maintenance and testing. The Chapter 117 rule requires that all testing and maintenance be done outside the hours of6 am to 12 am. As discussed in the comments on the modeling inputs, emissions in the morning are the most conducive to

ozone formation. Emissions outside this period are much less conducive to

ozone formation. Therefore, therules for maintenance represent RACM for the HG area.

TNRCC believes and EPA agrees that few existing engines will be moved from
emergency service to routine or peak shaving operations for the following

reasons. Any existing engines at a site with a collective design capacity to emit (fromunits with chapter 117 emission limits) greater than ten tpy ofNOx are subject to the Chapter 101 mass emissions cap and trade program ifthey choose to increase their operation to 100 hours per year ormore (based on a rolling 12-month average) and, in addition to having to comply with the Chapter 117 rules, will onlybe issued NOx emissions allocations based on their historical activity level which would be much lower than 100 hrs/year. Existing engines theoretically couldbe switched to peak shaving service up to 100 hours/year but in reality only about 40 hours/year would be available for this type ofoperation. The remaining time would have to be used for normal routine testing ofthe engines. It is unlikely that the profit from sale of electricity, wouldjustifythe cost ofthe modifications to the switching system for only about 40 hours ofoperation. EPA concludes that additional control beyond the existing program is not economically feasible andtherefore would not represent RACM.

On-RoadControlMeasures

Comment:Two commenters suggested that 15 ppm sulfur gasoline shouldbe adopted in the HG area as a reasonably available control measure.

Response:The Act preempts states from establishing state fuels under section 211(c)(4)(A). Waivers from preemption are possible under section 211(c)(4)(C) ifthe state can show necessity for that fuel to meet the NAAQS, and ifno otherreasonable or practicable non-fuel measures exist that couldbe implemented in place ofa state fuel.For a state to obtain awaiver of preemption, an acceptable demonstration must be submitted to EPAthat can justify the need for a particular state fuel. This provision of the Act was included to discourage the development ofa patchwork offuel requirements from State to State.

Texas considered adopting a 15 ppm sulfur standard in gasoline, but withdrew the proposal once the 30 ppm Federal low sulfur gasoline standard became final. They received comments both for and against theproposal. Comments against cited excessive costs when compared with the emissions benefit, the difficulties in producing a boutique fuel, and anticipated distribution problems and conflicts with on-going efforts to comply with the federal low-sulfur requirements of30
ppm. Texas only projected a 1.15 ton/ day ofemission reduction fromthe institution ofa 15 ppm fuel. The BCCA estimates thatthe cost ofthese reductions is $400,000/ton to refiners. Based onTNRCC cost estimates, the cost is over $500,000/ton to consumers.

Because ofthe general preemption in the Act and the low projected cost effectiveness, EPA does not consider this fuel requirement tobe RACM for the HG area.

Comment:One commenter suggested thatTexas adopt diesel fuel thatmeets

a 15 ppm sulfur standard by 2003.

Response:Texas adopted a low emission diesel fuel inDecember 2000, thatincludes a low sulfur component. The state's low sulfur component phases in beginning May 1, 2002, with 500 ppm sulfur statewide for onhighway use and 110 counties in east and central Texas for non-road use. On June 1, 2006, the sulfur level dropsto 15 ppm in east and central Texas for offhighway use to be consistent with Federal low sulfur diesel fuel for onhighway use.Thus, TNRCC has already adopted a standard more stringentthan the Federal Standards.

In order for Texas to adopt statewide fuel controls that are more stringent thanFederal controls, the state must show necessity to achieve the NAAQS in the nonattainment areas andjustify implementing a fuel measure over nonfuel measures statewide. Texas has requested and EPAis granting in a separate Federal Register a waiver under 211(c)(4)(A) forthis fuel. EPA does not believe the accelerated schedule ofimplementing the low sulfur standard suggested by the
commenter isreasonable or willresult

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in ozone benefits because the low sulfur requirement does not result in NOx emission reductions by itselfbut instead enables catalyst technologies. Under Federal regulations, new vehicles will
not be required tomeet the new emission standard enabled by low sulfur diesel until 2007. Therefore, EPA does
not consider calling for these fuel requirements earlier as suggested bythe
commenter to be RACM.

Comment:Two commenters gave comments that the Inspection and Maintenance Program could be improved. One said that adequate

resources to develop and implement an I/M program mustbe assigned; otherwise, theprogram cannot be considered credible. A second
commenter statedthat theprogram shouldbe established based on where the vehicle owner usually works.

Response:EPA hasreviewed the I/M program developed by the State of Texas. In a separate Federal Register notice, we are approving the State's I/M program. The new program, using the Accelerated Simulation Mode (ASM)
test method will be implemented in all eightcounties ofthe HG nonattainment

area and covers more vehicles than are required bythe Federal I/M rules. Expanding the program to cover vehicles not registered in the program

area isbeyond the scope ofthe Federal rules and would be extremely difficult
to implement and enforce. Further, the prior, less stringent program met the minimum I/Mrequirement for the HG

area. The new program goes beyond those requirements. As such, we believe TNRCC has adopted an I/Mprogram that meets the RACM requirement. We agree that adequate resources will have
to be devoted to the implementation of this program by the Texas Department ofPublic Safety and TNRCC for the goals ofthe program to be achieved. At this time, we have no information to support a determination thatthe program will not be fully implemented. Comment:One commenter suggested that public and large commercial fleets be required to have low emitting vehicles.

Response:Texas adopted Fleet provisions and submitted them toEPA

onAugust 27, 1998 as the Texas Clean Fuel Fleet (CFF) substitute plan. EPA approved this provision on February 7, 2001 (66 FR 9203) as meeting the Clean Fuel Fleet Requirements ofthe Act. These provisions ensure that fleets meet

areasonable level ofcontrol in serious and above nonattainment areas. Texas' CFF substitute plan relies on a State fleet program-the Texas Clean Fleet (TCF)program-supplemented with additional volatile organic compound (VOC) andnitrogen oxide (NOx) emission controls. The emission reductions for Texas' plan greatly exceed the reductions that would have been achieved with the Federal CFF program. Therefore, the State's substitute plan will meet the Federal CFF requirement for VOC and NOx emissions reductions. EPAbelieves that TNRCC has instituted RACM for this

source category.

Comment:One commenter suggested that the State should encourage the early introduction ofTier 2vehicles.

Response:Inthe last session, the Texas legislature passed Senate Bill 5 which includes an incentive program for the purchase ofvehicles thatmeet the more stringentTier II vehicle standards. This program shouldresult in more cleaner vehicles coming into

use in Texas then would be required under the Federal Program. Itis uncertain, however, how much additional emission reduction will come from this program asit apparently isthe first ofitskind in the country. Therefore, EPA concludes that further acceleration ofthis program would not constitute RACM for the HG area.

Comment:A commenter suggested that non-USA registered trucks should be subject to an I/M inspection.

Response:Itis not clear whether the State has the legal authority to require trucks from aforeign country to be inspected. As a practical matter, there

are no proven test methods to employ for Diesel I/M programs. Therefore, this
cannot be considered a reasonably available measure.

Comment:One commenter felt all highway construction in HG area should be limited. The HG area must absorb ongoing expansions atthe airports, medical center plus population andjob growth. There is no room for the above ongoing new emissions generating projects let alone any new large emissions generating projects. The same commenter later said thatthe Transportation Improvement Plan and otherproposed changes toRegional Highway system must demonstrate full conformity with the Act.

Response:EPA agrees thatthe Regional Transportation Plans must demonstrate conformance to the State Implementation Plan consistent with section 176(c) ofthe Act and our transportation conformity rules at40 CFR 93.100; however, these are separate requirements from demonstrating attainment ofthe NAAQs. Transportation conformity is the process whereby the transportation plans have
to be reconciled with and show they are consistent with the plans for attainment. In this SIP, the State has established an emissions budget formotor vehicle emissions consistent with attainment. The Houston/Galveston Area Council will haveto show for allfuture plans, takinginto account existingroads and future growth how they will conform to thesebudgets. Giventhe severe impact

aban on road construction would place

on the HG area, EPA concludes thatthis is not a reasonably available measure.

Comment:One commenter suggested the State institute an auto license fee tiedto actual vehicle NOx emission
rates.

Response:EPAis not aware of anywhere where thismeasure has been instituted.It isnot clear howmuch emission reductions couldbe achieved and atwhat fee levels. Because ofthe lack oflocalized information on the
costs andbenefits ofthis program this
cannot be considered a RACM.

Texas is already instituting a program to provide rebates for the purchase of vehicles meeting the cleanest Tier II standards. This program should influence positively the introduction of cleaner vehicles into the fleet. OffRoadMeasures

Comment:Three commenters recommended measures they felt were appropriate to control emissions from construction equipment. One
commenter felt that all diesel equipment shouldbe required to register. He felt this wouldresult in a 70% reduction in emissions. Two other commenters felt that all State and Local Government
contracts shouldhave requirements that require lower emission equipment be used.

Response:The Texas legislature has passed an incentive program that will pay for the cost ofupgrading diesel equipment to meet cleaner standards. Texas plans to direct 24.7 million dollars/year to the HG area from the Texas Emission Reduction Program passed under Senate Bill 5.Based on experience from similar programs in California, we expect substantial reductions to be achieved. We therefore believe that additional measures to reduce emissions from this category are notRACM.

Comment:One commenter suggested the following measures to achieve additional emission reductions from aircraft operations: (1)Mandatory Powering ofJets at gates with Electric Power (2)Reduced Idling onthe runway (3)Congestion Pricing at Rush Hours at Airports.

Response:First, the State has executed agreed Orders with the major airlines and the City ofHouston to achieve emission reductions from Ground SupportEquipment (GSE) at

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airports in the HGA area. These Orders require aphased-in replacement of
current combustion engine equipment with electric equipment or to achieve equivalent reductions. Equipment powering jets at gates is included in the definition ofGSE; thus, over a period of time jets at gates willbe powered with electric equipment or equivalent emission reductions will be achieved. Second, although planning of airline operations during rush hours to reduce idling on runways to reduce emissions may have merit, the State does not have the authority to impose regulations on airlines torequire this planning. The Federal Aviation Administration has jurisdiction over airline operations once the aircraft leaves the gate and State regulation ispre-empted. Third, since the State has no authority to control airline operations, and congestion is a function ofthe higher level of operations during rush hours, congestion pricing is likely toplace an unnecessary economic burden onthe traveling public with no air quality benefits. State controls on pricing are expressly preempted by the Air Deregulation Act. Therefore, EPA concludes that such measures are not reasonably available. TransportationControl Measuresand Land Use
Comment:Transportation Control Measures as RACM: EPA gives virtually

no consideration to the emission reduction benefits oftransportation
programs, projects and services contained in adopted regional transportation plans (RTPs), or that are clearly available for adoption as part of RTPs adopted for anonattainment area. In addition, it is arbitrary and capricious for EPA not to require as RACM economic incentive measures that are generally available to reduce motor vehicle emissions in every nonattainment area. One commenter provided a report "Studies on the Travel andAir Quality Effects ofTransit, Land Use Intensification, and Auto Pricing Policies." The commenter felt this report contained measures that are RACM.

Response:A similar comment was received in response to the analysis EPA performed as part ofEPA's notice of availability where an analysis of Reasonably Available TCMs was performed for four serious ozone nonattainment areas: Greater Connecticut, Springfield, MA, Washington, DC and Atlanta. In the Technical Support Document for the July 12, 2001 proposal on RACM, EPA performed a similar analysis for the HG

area. This analysis was performed to evaluate the State's conclusion that further TCMs are either economically infeasible or would not advance attainment.

EPA's TSD for the July 12, 2001 proposal on RACM for the HG area does consider transportation programs, projects and services that are generally adopted, or available for inclusion in a nonattainment area's SIP. The RACM analysis includes sevenbroad categories andtwenty-seven subcategories of Transportation Control Measures (TCMs)that represent a range of programs, projects and services. The inclusion of aTCM in an RTP or TIP does not necessarily mean that itmeets EPA's criteria for RACM and must be included in the SIP. The measure must also contribute to expeditious attainment. EPA concluded from its analysis that the State's assertion that further TCMs arenot RACM was appropriate.

Some ofthese TCMs, such as parking cashout,transit subsidies, and parking pricing, are explicitly economic incentive programs. Furthermore, these categories ofTCMs, as well as most of the others, couldbe infinitely differentiated according to criteria, such

asthe method ofimplementation, level ofpromotional effort or market penetration, stringency ofenforcement,
etc. The application ofeconomic incentives to increase the effectiveness ofa TCM is one such criterion. These implementation variables, representing levels ofimplementation effort, are implicit in therange ofeffectiveness for each category ofTCM. EPA does not believe it isnecessary, or even practically possible, to evaluate every explicit variation ofTCM's in order to adequately determine ifitis reasonably available.

From the analysis for the HG area, EPA identified 1.7 to 22.4 tpd ofNOx emission reductions astheoretically achievable from TCMs. The EPA believes that emission reductions which

are in the low-to mid-point range of EPA's analysis are achievable with careful planning, adequate implementation resources, aggressive public information programs and a sustained commitment by the implementing agencies. TNRCC has identified in its SIP the implementation ofa wide range ofTCMs which are projected to achieve 4.86 tpd of emission reductions. The TCM's identified in the HG analysis are in the low- to mid-point range. Additional emission reductions beyond this level that could be reasonably achieved would not advance attainment given that the final 121 tons/day ofNOx emissions reductions from the point source rules will not be achieved until spring of 2007.

There are many important reasons why a state, regional, orlocal planning
agency might implement TCMs in an integrated traffic management plan beyond whatever air quality benefits the TCMs might generate, including preserving open space, water shed protection, avoiding sprawl, mitigating congestion, and "smart growth" planning generally. So the fact that TCMs are being implemented in certain

ozone nonattainment areas does not necessarily lead one to the conclusion that those TCMs represent mandatory RACM when they are analyzed primarily for the purpose ofdetermining whether they would advance the ozone attainment date.

The report, "Studies on the Travel and Air Quality Effects ofTransit, Land Use Intensification, and Auto Pricing Policies," provides case studies from

two areas ofthe country, Portland OR, and Sacramento, CA and aliterature
survey. EPA's analysis included consideration ofmeasures in the same categories as provided in this report. Based onthis analysis, EPA does not believe implementation ofthese

measures would advance the HG area's attainment. Further, as stated in the General Preamble, 57 FR 13560, EPA believes that local circumstances vary to such a degree from city-to-city that a national presumption ofRACM is not appropriate. It is more appropriate for States to consider TCM's on an areaspecific basis and to consider groups of interacting measures, rather than individual measures. Therefore, based

on EPA's analysis, EPA cannot conclude that these measure suggested in the report are RACM for the HG area.

Comment:A number ofspecific TCMs and economic incentive programs to reduce vehicle miles traveled were identified by various commenters. These include: Telecommuting, satellite offices, college/university traffic control

measures, Bike and Walk pathways, Increased Government Use ofthe Web, Voluntary No Drive Days, Trip Reduction Ordinances, Employer Based Transportation Management, Road Pricing, Ride Share Incentives, Insurance Pricing, Commuter Choice, Parking Cashout, Taxes on Paid Parking, Congestion Pricing, Location Efficient Mortgages, Fee Bate on Suburban Mortgages, Tax Incentives forLiving NearPlace ofEmployment, Incentives for Transit Oriented Development and improved incident response.

Response:As stated in the previous
response, EPA does not believe it is
necessary, or even practically possible,

to evaluate every explicit variation of Federal Register/Vol. 66,

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TCM's in order to adequately determine ifitis reasonably available. EPAnotes that many ofthe measures listed above

are being encouraged in the HG area as part ofthe commuter choice program such as telecommuting, ride share incentives, and employer based transportation management. As discussed in the previous comment Texas has identified 4.83 tpd ofNOx emission reductions from reasonably available Transportation Control Measures which, based on the literature survey, falls into the low to midpoint of emission reductions theoretically achievable from these programs. Also,

as noted above, this small amount of emissions reductions would not advance attainment prior tothe implementation of all othermeasures in the plan. Therefore, EPA believes the small amount of additional reductions that could reasonably be achieved would not advance attainment. Comment:EPA's analysis also completely fails to consider the additional benefits likely from combined implementation of complementary TCMS e.g., parking management along with transit improvements. Itis arbitrary and irrational for EPA to assume that these

measures can and will be implemented in complete isolation from one another.

Response:EPA recognizes thatmany control measures, particularly TCMS,

are more effective ifdone in conjunction with others. EPA maintains, however, that itis not practically possible to analyze a seeming infinite set of combinations ofmeasures for possible benefits. The EPA's analysis did lookat allmeasures in various categories at a reasonable level ofimplementation and concluded that as a whole these categories ofmeasures, taken together, would not advance attainment or would otherwise not be reasonably available.

GeneralRACM Comments

Comment:One commenter suggested that the SIP should include enforcement ofNew Source Review such that grandfathered plants would get emissions permits with emission limits that are identical tonew construction as ofJune 2001.

Response:Existing industrial sources in the HG area are required to comply with Chapter 115 for VOC and Chapter 117 for NOx controls regardless of whether the sources are permitted or grandfathered. These rules have been approved as RACT. In addition all
sources, both existing and new, are subject to the NOx mass emissions cap in Chapter 101. Requiring all existing

sources to obtain permits isnot likely to result in any additional emission reductions beyond those achieved by the Chapter 115 andChapter 117 rules.
Comment:One commenter incorporated in their comments to EPA their comment to the TNRCC where they encouraged the State to use Market Incentives to the extentpossible.

Response:Webelieve the State has employed market based incentives in a variety ofprograms. The cap and trade program andthe Texas Emission Reduction Program arethe two main examples ofprograms that use markets
to provide significant flexibility in how emission reductions are achieved.

Comment:STAPPA's 1993 report recommended adoption ofCalifornia or South Coast Air Quality Management District (SCAQMD) controls/limits for various source categories. The
commenter mentions further possible control measures aswell, andnotes that

none ofthe states offered consideration ofthese measures accompanied by reasoned explanations for their rejection.

Response:Texas used the EPA survey "Serious and Severe Ozone Nonattainment areas: Information on Emissions Control Measures Adopted or Planned and Other Available Control Measures" as a basis to determine ifall reasonably available control measures had been implemented. This report includes measures from the STAPPA 1993 report and othermeasures that EPA considers potentially reasonably available. TNRCC did not identify any additional measures that were considered reasonable for the HG area.

Comment:By absorbing ozone and reducing air temperatures, trees actually
account for a smallbut measurable reduction in ozone levels. The EPA shouldwork with TNRCC to encourage public funding for tree planting and local ordinance thatrequire canopy

coverin new private development.

Response:EPA agrees thattree planting canresult in a possible reduction in ozone formation. Unfortunately, atthis time, these benefits are difficult to quantify. Efforts

are currently underway to complete a modeling study to quantify the impacts ofvarious urban heat island mitigation strategies using the photochemical model. It ishoped thatthese studies will provide information that will allow
tree planting strategies to be included as

a creditable portion ofthe SIP at alater date, perhaps for the mid-course review SIP submission. Texas is involved in this effort and intends to incorporate suchprograms in the SIP shouldthey
prove effective and reasonably available. C.Responseto Comments onLocal Measures

1.Comments on Speed Limits

Comment:Three commenters indicated the speed limitmeasure would notbe enforced or was not enforceable and thatEPA shouldnot give credit unless TNRCC develops a mechanism to demonstrate that speeds actually decrease.

Response:The mechanism to enforce reduced speed limits is already in place with the Department ofPublic Safety and local municipalities. EPA acknowledges that itis unlikely that 100% ofvehicles will comply with the

new speeds. The modeling projections

assume that the average speed will be 10% higher than theposted speed limits

on roads that currently have average speeds above the reduced speeds. Thus, the State has made reasonable assumptions to anticipate the level of compliance with this rule. We believe

we can approve these reasonable planning assumptions about speed reductions. Itwould not be appropriate
to wait until Texas proves thatthe speeds have been reduced to give credit for this measurejust as we would not wait until industrial sources have accomplished their emission reductions before approving point source rules. We dobelieve that the effectiveness ofthis
measure, as with all measures, should be monitored. Datais collected in the HG area by Transtar and Texas Department ofTransportation. This data couldbe used to evaluate the efficacy of this measure inreducing speeds.

2.Comments on the VMEP

Comment:The plan includes impermissible reductions for "Voluntary controls." EPA has no legal basis for issuing SIP credit for the VMEP
program; the VMEP measures do not meet the test ofbeing real, permanent, and enforceable to qualify for emission reductions.

Response:EPA disagrees with the comments, and continues to believe that the voluntary measures proposed by Texas for inclusion in the SIP are approvable under the Act.EPA acknowledges that, bythemselves, the

measures wouldnot be approvable, because, as noted bythe commenter, they are not enforceable against the entities producing the emissions reductions and thus do notmeet the enforceability requirement of section 110(a)(2)(A). However, EPA did not propose to approve the measures by themselves. EPA proposed to approve them only in conjunction with an enforceable commitment by the state of Texas to monitor implementation ofthe 

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voluntary measures, determine whether the anticipated reductions from the

measures were in fact achieved, and if
not to either alter the program such that the requisite reductions willbe achieved, adopt substitute measures, or demonstrate thatthe attainment and maintenance goals ofthe ozone SIP can still be met without the reductions from these measures. Thus, EPA did not propose to approve voluntary measures

as satisfying the enforceability requirements of section 110. Rather, EPA proposed to approve the voluntary
programs into the SIP aspart ofthe overall attainment scheme, and proposed to approve the state's enforceable commitment to monitor,
assess, andrectify any shortfall as meeting the enforceability requirements ofthe Act.

EPA continues to believe that this approach is a proper means of encouraging implementation of innovative mobile source control

measures while providing an enforceable SIP backstop measure. Ideally, the voluntary measures will produce the estimated emissions reductions without need for any state backfill or federal or citizen enforcement. However, should any shortfall result, Texas will be bound by the enforceable SIP commitment to rectify the problem and supply the
necessary emissions reductions. Both EPA and private citizens retain all of their rights under sections 113 and 304
to bring appropriate enforcement pressure to bear against the state should Texas fail to monitor, assess or fill any shortfall in emissions reductions resulting from implementation ofthe voluntary measures in the SIP. Contrary
to the commenter's allegations, the emissions reductions associated with the voluntary measures in the HG area SIP are required to be achieved; itis however the state and not the individuals implementing the voluntary

measures who must ultimately produce them. Comment:Two commenters raise

numerous arguments concerning the unenforceability ofthe voluntary

measures.

Response:The commenter makes no mention ofthe enforceable state commitment otherthan to refer to itas insufficient. This statement without further explanation does not give EPA
any guidance on the alleged inadequacy ofthe commitment nor how the
commenter would have EPA improve
upon it. Therefore, EPA continues to maintain thatthe commitment is approvable as meeting the enforceability requirements ofthe Act. In the past, EPA has often approved enforceable state commitments to take future actions under the SIP, and these actions have been enforced by courts against states that have failed to comply with those commitments. 16EPAbelieves that the Texas commitments associated withthe voluntary measures portion ofthe SIP

are similarly enforceable and thus approvable. NRDC alleges thatthe Act requires all control measures to be enforceable against individual polluters and notjust against states. However, many mobile source control measures
are enforceable only against the state or local transit operator, and not the individual entities actually producing the emissions reductions, for instance in the case of state obligations to establish vehicle inspection and maintenance programs orto purchase buses or expand transit systems. The Act does
not require federal enforcement capability against individual vehicle

owners or transit users prior to approval ofsuch programs into the SIP. 15

Comment:A commenter alleges that the public cannot adequately monitor implementation ofthe voluntary

measures nor determine whether the emissions reductions are achieved. The
commenter admonishes the State to committo a solid evaluation or auditing framework to monitor performance of

measures in the VMEP.

Response:Texas isrequired byits enforceable commitment to conduct the evaluation and auditmentioned by ED, and shouldmake such assessments available tothe public in the normal

course of administrative practice. The
commenters also claim thatthe state itselfhas raised concerns about the emissions reductions that will be achieved from these measures. Such

concerns may be valid, nevertheless Texas has made a commitment to fill
any shortfall in emissions, which both EPA and citizens can enforce under the Act.

16See, Trustees forAlaskav. Fink,17 F. 3d 1209 (9thCih. 1994); Coalition AgainstColumbusCenter

v. CityofNew York, 967 F. 2d 764 (2d. Cir. 1992); Citizens fora BetterEnvironmentv. Deukmejian, 731 F. Supp. 1448, reconsideration granted inpart, 746 F. Supp. 976 (N.D. Cal. 1990); American Lung Ass'n ofNewJerseyv. Keane, 871 F.2d 319 (3d Cih. 1989); NRDCv. New York StateDepartmentof EnvironmentalConservation,668 F. Supp. 848 (S.D.N.Y. 1987); CouncilofCommuter Organizations v. Gorsuch,683 F.2d 648 (2d Cir. 1982) and FriendsoftheEarthv. EPA, 499F.2d. 1118 (2d. Cir. 1974).

17The Act does require that enhanced I/M
programs include stateenforcement through denial of vehicle registrationwithout proofofcompliance with inspection requirements. However, the enforceable SIPrequirement is to develop a program that includes registration denial, and any enforcement would be against the statefor failing
to denyregistration. The Act does not contemplate enforcement actions against individual vehicle

owners attempting to register their vehicles. Comment:Acommenter makes various arguments about the unacceptability ofthe voluntary

measures program stemming fromthe stationary source permitting program underTitle V ofthe Act.

Response:TitleV is totally irrelevant
to these mobile source programs. The voluntary measures program Texas has included in the HG SIP applies onlyto mobile sources that are not subject to regulation under the Title V stationary

source operating permitprogram.

Comment:EPA can not alter itspast interpretations without completing notice-and-comment rulemaking.

Response:EPAbelieves that this action is consistent with itspast interpretations that enforceable state commitments to take future action are approvable SIP measures. For example,

see EPA actions approving California plans at 62 FR 1150 (January 8, 1997) and 65 FR 18903 (April 10, 2000). In addition,this action is consistent with the guidance that EPAissued in 1997 indicating itsbeliefthat voluntary programs couldbe approved in conjunction with enforceable state commitments to fill any resultant shortfall.' 8The individual SIP approval actions implementing the VMEP guidance constitute the notice-andcomment rulemaking required to effectuate action under the guidance. Thus, this SIP rulemaking satisfies both CAA and APA rulemaking requirements with respect to final interpretations of the Act consistent with the guidance. Further, NRDC alleges thatEPA may not alterinterpretations ofthe Administrator through SIP rulemaking signed by the Regional Administrator. However, the Administrator has properly delegated the authority for SIP rulemakings to the Regional Administrators under Delegation 7-10 dated May 6, 1997, and section 301(a)(1) ofthe Act. Thus, the Regional Administrators are authorized to act for the Administrator with respectto all
matters pertaining to SIP approvals, including interpretations ofthe Act relevant to a given SIP approval.

Comment:Acommenter questions the 30%limit onvoluntary measures, arguing thatthis limit itselfimplicitly acknowledges that suchmeasures are not approvable.

Response:EPA did notimpose the 3% limitbecause itbelieved the measures to be suspect,but rather, as noted in the VMEP guidance, based on the innovative nature ofthe measures and the agency's lack of experience both

1 8 Guidance on Incorporating Voluntary Mobile
SourceEmission Reduction programs in State Implementation Plans (SIPs), October 24, 1997.

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with implementation and calculating appropriate credit for suchmeasures. Therefore, EPA created the 3% limit as

apolicy matter, indicating in the guidance that itdid not think it would be appropriate to approve agreater percentage while the agencybegins to implement the program. EPA further indicated thatit would reassess the limit after several years ofexperience with theprogram. Since all VMEP

measures would be approved only with enforceable state commitments to fill any resultant shortfall, EPA felt confident that including voluntary programs up to 3% ofrequired emissions reductions in SIPs would not jeopardize attainment and maintenance goals during initial implementation under the policy. Further, EPA did not indicate that 3% ofrequired emissions reductions could be considered de minimis,as the commenter implies. EPA agrees with the commenter thatit shouldnot conclude in advance that any given percentage ofemissions reduction could be considered persede minimisfor all areas and types ofSIPs. Any conclusion about the deminimis
nature ofrequired emission reductions shouldbe made in light ofthe specific circumstances ofthe areas and CAA requirements at issue. Therefore, all of the commenter's arguments relating to the availability ofa deminimis exemption and the need for notice-andcommentrulemaking to effectuate it are not relevant to EPA's approval ofthe voluntary measures in the HG area SIP. Comment:The record isinsufficient
to support TNRCC's credit claims.

Response:EPA reviewed the documentation submitted for each

measure ofthe VMEP. We found that for each measure the documentation was acceptable to demonstrate that the criteria for approval were met for each

measure. For each measure the State

was able to show that the measure plus the State commitment was quantifiable, surplus, enforceable, permanent, and adequately supported.

Comment:One commenter pointed
outthat delays may result from identifying andrectifying emissions shortfalls.

Response:EPA acknowledges that reductions willbe somewhat delayed where states must first monitor and

assess implementation and subsequently implement corrections. For this reason EPA indicated in the VMEP guidance that states should fill any shortfalls in a timely fashion. EPA recently issued a companion voluntary

measures policy for stationary sources. See, "Incorporating Voluntary Stationary Source Emission Reduction Programs Into State Implementation Plans-FINAL POLICY," memorandum and attachment dated website January 19, 2001, from John Seitz, Director of the Office ofAir Quality Planning and Standards. In thatpolicy EPAindicated that where voluntarymeasures were included inattainment or rate of progress SIPs, any shortfalls would have
to be filledprior to the relevant attainment orprogress milestone date. EPA believes this is an appropriate interpretation ofthe requirement to fill shortfalls in atimely fashion under the VMEP policy. Comment:EPA putforth different, conflicting explanations for why VMEP

measures purportedly will meet the enforceability requirements of section 110(a)(2) ofthe Act. In the DFW proposed approval we say thatthe

measures willbe enforced bythe State, whereas in the HGA proposed approval

we say that the voluntarymeasures will be enforceable against the State.

Response:As discussed above, courts have upheld the legal authority to enforce state SIP commitments. The language in the DFWnotice was intended toindicate that Texas was to monitor and assess reductions attributable to VMEP and, in case ofa shortfall, implement measures to offset that shortfall. What is enforceable is the commitment to see that reductions in an amount equal to what isproposed in the
VMEP are achieved.Such enforcement is also available against the State, but
not against the individual entities that

are implementing the voluntary

measures. Texas has made similar commitments with respect toboth Dallas/Fort Worth andthe HG area. Comment:EPA improperly redefined the subject ofthe enforceability requirements ofsection 110(a)(2); that what is enforceable against the State is the commitment tomonitor, assess, and timely remedy a shortfall from implementation ofthe measures.

Response:We agree that what is enforceable against the State is the commitment to monitor,assess and timely remedy any shortfall to ensure the claimed VMEP reductions are met. We donot agree that this is improper under the Act and have already cited

case law in support ofthis position.

Comment:One commenter appreciated EPA's approval ofthe VMEP and asked for the State's and EPA's continued support.

Response:We appreciate the
commenters support. EPA will continue
to support the State's VMEP activities as long as they are developed and implemented in accordance with EPA's October 24, 1997, Guidance on Incorporating Voluntary Mobile Source Emission Reduction Programs inState Implementation Plans (SIPs) andthe responses to comments in this rulemaking.

3.Comments on TCMs

Comment:The commenters stated thatthe TCMs are inadequate and do
not satisfythe requirements of section 182(d)(1)(A) ofthe Act.

Response:Section 182(d)(1)(A) directs the State to submit a SIP revision that identifies and adopts specific enforceable transportation control strategies and TCMs to offset any growth in emissions from growth in vehicle miles traveled or number ofvehicle trips in severe nonattainment areas, and
to attain reduction inmotor vehicle emissions as necessary to meet reasonable further progress and attainment requirements ofthe Act. The State submitted SIP revisions to the EPA

on August 25, 1997 and May 17, 2000
to address the VMT Offset provision, the first required element under section 182(d)(1)(A). The EPAproposed approval ofthese SIP revisions onJuly 10, 2001 (66FR 35920, seealso 66 FR 35903), and subsequently received public comments. The EPA's final approval action on this SIP, the VMT Offset Plan, hasbeen taken in a separate concurrent Federal Register action that discusses the emissions growth offset element in detail.

That action also explains thatEPA believes itis appropriate to allow States
to separate the VMT Offset SIP into three elements, each to be submitted at different times: (1)The initial requirement to submit TCMs that offset growth in emissions; (2)the requirement
to comply within the 15 percent periodic reduction requirement ofthe Act; and (3)the requirement to comply with the post-1996 periodic reduction and attainment requirements ofthe Act. Please see the concurrent VMT Offset action referenced above for the first element.

Today's action here satisfies the second and third elements ofsection 182(d)(1)(A). EPAbelieves this SIP action, including its TCMs, demonstrates thatthe HG area will achieve the required ROP and attainment ofthe ozone NAAQS for the

reasons discussed in more detail throughout this final action, and thatthe SIP therefore satisfies the last two elements.

D.Response to Comments onPost1999 RateofProgress Plans

Comment:Texas provided a comment

on EPA'sDecember 1999proposal indicating the April 2000 SIP revision will contain a commitment by the state 57192 Federal Register/Vol. 66,

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to submit a full Post-99 ROP analysis by 12/31/00.

Response:Texas has fulfilled this commitment. EPAis approving this Post-99 ROP plan in this action. Comment:The TNRCC ROP plan shouldbe revised to be consistent with the budget. The required NOxreduction for 2005-2007 should be more than the 6% (3%/year for the 2year period) figure included in Chapter 5.

Response:The EPA acknowledges that the TNRCC has included a 2007 MVEB, which in conjunction with the othermeasures in the plan will result in

more than 6% emission reduction. The Rate ofProgress requirement is to achieve at aminimum 6% emission reduction for the time period 2006-2007

as called forby section 182(b)(2) ofthe Act. The requirement shouldremain 6%, settingthe MVEB lower will only result in more reductions than needed
to achieve the required ROP levels. Comment:One commenter on the December 1999 proposed approval/ proposed disapproval claims that the plans fail to demonstrate emission reductions of3%peryear over each 3- year period between November 1999 andNovember 2002; and November 2002 and November 2005; and the 2- year period between November 2005 andNovember 2007, as required by 42 U.S.C. section 7511a(c)(2)(B). The states have not even attempted to demonstrate compliance with these requirements, andEPA has not proposed to find that they have been met.The EPAhas absolutely no authority to waive the statutory mandate for 3% annual reductions. The statute does not allow EPA to use the NOx SIP call or 126 orders as an excuse for waiving rate-ofprogress (ROP) deadlines. The statutory ROP requirement is for emission reductions-not ambient reductions. Emission reductions in upwind states donot waive the statutory requirement for 3% annual emission reductions within the downwind nonattainment

area.

Response:Under no condition is EPA waiving the statutory requirement for 3% annual emission reductions. In today's action we are approving Texas Post-99 ROP plan as submitted December 2000 andrevised and submitted in October 2001. As provided in this EPA's final action on the ROP plan Texas isrelying on reductions of NOx and VOC within the nonattainment

area for meeting the ROP requirement.

E.Response to Comments on AdministrativeRecord
Comment:A commenter could not find support in the administrative record for the following propositions: The Shortfall Proposition: Identified potential

measures can achieve an additional 56 tons/day NOx emissions reduction without requiring additional limits on highway construction. Support:In Chapter 7,Texas projected thatthe measures being considered for adoption would address the 56 tpd short fall. Examination of these measures reveals thattheir implementation would not result in additional limitations on highway construction. Further, the State has provided a commitment that future

measures willnot rely on limits on highway construction.

Proposition: The State's cited ranges ofpotential reductions from measures being considered to address the shortfall provide a "reasonable assurance" that the State can meet its commitment to submit adopted measures to fillthe shortfall; the State has identified sufficient innovative programs andnew technologies such thatit isreasonable to believe that, in the aggregate, the projected emission reductions from these new programs andtechnologies

canbe achieved and will fill the shortfall andthe measures to be considered for adoption at the midcourse review can achieve the NOx emissions reductions indicated on pp. 23-24 ofthe Technical Support Document. Support:Chapter 7ofthe Texas SIP discusses each ofthe measures andthe State's projected range ofemission reductions. The TSD in Section IV.F. has further discussion ofeach ofthe potential measures and information that exists to support the projected emission reductions.

SB5 andIncentive Programs

Proposition: Texas Emission Reduction Plan (TERP) will provide 130 million dollars per year for incentive
programs to reduce emissions. Support:This estimate was based on fiscal estimates provided bythe State regarding the revenue that will be available from the fees associated with this bill. Chapter 7ofthe adopted SIP cites an estimate of133 million dollars.

Proposition: Incentive programs in SB5 can achieve more reductions than the reductions that were projected to be achieved bythe accelerated purchase of Tier II/III non-road diesel equipment andthe Heavy-duty Diesel Equipment Operating Restrictions measure and can contribute to reducing the shortfall.

Support:This is discussed at Section IV.F. ofthe TSD.

Proposition: It can safely be assumed that at least45% ofthe SB5 funding for clean up ofdiesel engines will go tothe HG area and TERP canreasonably be expected to provide 40 million dollars/
year tothe HG area for reducing emissions from existing diesel equipment.

Support:These assumptions were first developed based on early discussions with TNRCC. We understand as pointed
outby the commenter that only $24.7 million/year are currently being planned for the HG area. As discussed in our response to comment onthis issue, we believe this will still provide sufficient funds to replace the emission reductions from the morning construction ban and Accelerated Tier I/11. clearly, the priority ofTNRCC and the legislation is topreserve the HG and Dallas/Fort Worth SIPs. to that end as discussed in the comments on this control strategy in section III.B.3, Texas has the discretion to provide more money, even more than 40 million, to the HG area ifnecessary.

Proposition: Incentive programs in SB5 can obtain emissions reductions from existing diesel equipment at an average cost on the order of $3,000- 5,000/ton.

Support:As statedin the TSD, this is based on experience with California programs. The actual experience ofthe Carl Moyer Program is a cost effectiveness ofbetter than $3000/ton as statedin "The Carl Moyer Memorial Air Quality Standards Attainment Program (The Carl Moyer Program) GuidelinesApproved Revision 2000, November 16, 2000 California Environmental Protection Agency Air Resources Board."

Proposition: The TERP program for reducing emissions from diesel equipment can achieve between 32 and 40 tons/day ofemissions reductions in the HG area.

Support:This is discussed inIV.F of the TSD. Itis also discussed in Chapter 7ofthe adopted version ofthe Texas SIP and in the responses to comments in this action.

Proposition: The TERP's projected emissions reductions that will be substituted for the Tier II/III non-road diesel equipment measure will achieve 12.2 tons/day. Itis also discussed in Chapter 7ofthe adopted version ofthe Texas SIP submitted in aletter dated October 4, 2001.

Support:This is discussed in Section IV.F ofthe TSD.

Growth Rates

Proposition: Projected growth rates and emissions reductions fromthe

sources subject to the Tier 2Vehicle Emission Standards and Federal Low Sulfur Gasoline, National Low Emitting

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Vehicle Standards, and Heavy-duty Diesel Standards were calculated correctly by the State.

Support:The procedures for calculating the emissions from on-road vehicles are documented in Chapter 3of the SIP. As discussed in Chapter 3, these emissions are based on a report that was included in Appendix G ofthe November 1999 SIP revision. Chapter 3 discusses several refinements and revisions to what was provided in the November 1999 SIP. These were discussed in Appendix A ofthe TSD Section I.F.

Proposition: Growth rates and emission reductions were correctly projected by the State for sources subject to the Federal Measures, including on-road and off-road mobile

source measures and the Act Statutory Requirements. Support:On-road measures were discussed in the previous proposition. Off-road measures are also discussed in I.F. ofAppendix A ofthe TSD.

Proposition: The State has correctly factored growth in emissions due to population and economic growth. Support:These are discussed in Section I.G.4 ofAppendix A ofthe TSD.

Settlement

Proposition: Additional controls at uncontrolled grandfathered facilities in East Texas, which are called forby
recent legislation, will offset the increased emissions from utilities pursuant tothe settlement agreement. Support:This issue is discussed in Chapter 6 ofthe Texas SIP. EPA's review is discussed in the TSD in Section III.K ofthe TSD. The issue is also discussed in the response to comments regarding model inputs.

Proposition: Substitution ofa portion ofthe emissions reductions from the

new TERP measures for the modeled Heavy-duty Diesel Equipment Operating Restrictions along with the change in the NOxpoint source measures are not expected toincrease the modeled ozone reductions. Changes in the Heavy-duty Diesel Equipment Operating Restrictions and rules for utilities will
not "adversely affect the modeling results" or "affect modeling results in a way to increase ozone."

Support:These issues were discussed in III. I. ofthe TSD and in Chapter 7of the adopted SIP revision. Speed Limit Reductions

Proposition: Reductions in the speed limit to 55 mph in the HG area will result in the reductions calculated by TTI. The percentage ofmotorists that TTI projected to exceed the newly proposed speed limits is reasonable. Support:The reduction in speed limit is discussed in detail in TNRCC's SIP and in particular in the State's response to comments in the December 2000 SIP. EPA reviewed and evaluated these documents to draw these conclusions. Also, se the Chapter 3 ofthe December 2000 SIP andAppendix A ofthe TSD.

RACM

Proposition: Texas has established that all reasonable measures that could accelerate the attainment date have been adopted, or will be adopted.

Support:Chapter 7ofthe SIP and Appendix B ofthe TSD extensively discuss this issue.

VOCs

Proposition: The modeling and list of control measures demonstrate that additional VOC controls are not costeffective in reducing ozone in the HG

area and would not advance the attainment deadline.

Support:This issue is extensively discussed in Appendix B. ofthe TSD and Chapter 7ofthe SIP. This issue is discussed further in our response to comments onthis action.

Proposition: RACT isin place for all major sources ofVOC in the HG area. Support:As part ofour action approving VOC requirements, we found that the State had adopted RACT for all major sources, in the HG area except those that were tobe covered by postenactment Control Technique Guidelines (CTG's)(60 FR 12437, March 7, 1995). Since thattime many expected CTGs were issued as Alternative Control Technique documents-ACTs. Ofthe expected CTGs and ACTs, the HG area had major sources in the following categories; batch processing, industrial wastewater, reactors and distillation, and wood furniture. We have approved

measures for all ofthese categories as meeting RACT. Batch Processing-July 16, 2001 66 FR 36913 Industrial Wastewater-December 10, 2000 65 FR 79745 Reactors and Distillation-January 26, 1999, 64 FR 3841 Wood Furniture-October 30, 1996, 61

FR 55894

State's Estimated NOx Reductions

Proposition: The State control

measures andlocal initiatives will provide the NOx reductions indicated in Table 4 ofthe TSD. The State's projection ofexpected emissions reductions from Regional andLocal Measures is correct (thisincludes the adequacy ofthe equivalent NOx reductions credited to the commercial lawn care shift). The NOxreductions for the 2007 attainment year resulting from the State control measures and local initiatives predicted in Table 4 onpg. 18 ofthe TSD are accurate.

Support:First, each ofthe control

measures havebeen approved in separate actions or in this action as listed in Section II ofthis action. These Federal Register actions announce our beliefthat these are permanent, enforceable measures that will achieve emission reductions toward attainment. Regarding theprojected emission reductions from each measure:

Point Source Control reductions are well documented in a table in the State's preamble toNOx rules submitted in December 2000. We reviewed this table in concluding the SIP will achieve the projected reductions frompoint

sources. Also see the EPA's TSDs forits actions onthe point source rule and this action.

The record for reductions for on-road emissions reductions fromI/M, low emissions diesel fuel, speed limit reductions, andvehicle idling are discussed in previous propositions. They are principally discussed in the record inChapter 3ofthe SIP andin Appendix Aofthe TSD.

Off-road measures; Heavy duty diesel operating restriction and Accelerated Tier II/III have been replaced bythe TERP and the potential emission reductions from the TERP are discussed in section IV.F. ofthe TSD. The emissions shifted by small spark operating restrictions are discussed in the State's preamble to therule andin Chapter 6. Airport GSE emissions are discussed in Appendix Aofthe TNRCC December 2000 SIP submission, Heavy equipment gas engines emission reductions are discussed in the State's preamble to the rules submitted in December 2000.

Gas-fired water heaters-EPA reviewed the discussion provided in the State's preamble tothe water heater and smallboiler rule.

VMEP measures and the projected emission reductions are extensively discussed in Appendix K ofthe December 2000 State submission and in section IV ofthe TSD.

Energy Efficiency projections are discussed in Chapter 6 ofthe SIP.

Transportation Control Measure are documented in Appendix Iofthe SIP and discussed in section IV ofthe TSD.

IV.Administrative Requirements

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is
not a "significant regulatory action" and therefore is not subject toreview bythe Office ofManagement and Budget. For this reason, this action is also not

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subject to Executive Order 13211, "Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, orUse" (66 FR 28355, May 22, 2001). This action merely approves state law as meeting Federal requirements and imposes no additional requirements beyond those imposed by
state law. Accordingly, the Administrator certifies thatthis rule will not have a significant economic impact on asubstantial number of small entities under the Regulatory Flexibility Act (5U.S.C. 601 etseq.). Because this rule approves pre-existing requirements under state lawand does not impose any additional enforceable duty beyond that required by state law, it does not contain any unfunded mandate or significantly oruniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub.L. 104-4).

This rule also does not have tribal implications because itwill not have a substantial direct effect on one or more Indian tribes, on therelationship between the Federal Government and Indian tribes, or on the distribution of
power and responsibilities between the Federal Government and Indian tribes,

as specified by Executive Order 13175 (65 FR 67249, November 9, 2000). This action also does not have Federalism implications because it does not have substantial direct effects on the States,

onthe relationship between the national government and the States, or on the distribution ofpower and responsibilities among the various levels ofgovernment, as specified in Executive Order 13132 (64 FR 43255, August 10, 1999). This action merely approves a state rule implementing a Federal standard, and does not alter the relationship or the distribution ofpower andresponsibilities established in the Act. This rule also isnot subject to Executive Order 13045 "Protection of Children from Environmental Health Risks and Safety Risks" (62 FR 19885, April 23, 1997), because itis not economically significant.

In reviewing SIP submissions, EPA's role is to approve state choices, provided that theymeet the criteria of the Act. In this context, in the absence ofa prior existing requirement for the State to use voluntary consensus standards (VCS), EPAhas no authority
to disapprove aSIP submission for failure to use VCS. Itwould thus be inconsistent with applicable law for EPA, when itreviews a SIP submission,
to use VCS in place ofa SIP submission that otherwise satisfies the provisions of the Act. Thus, the requirements of section 12(d) ofthe National Technology Transfer andAdvancement Act of1995 (15 U.S.C. 272 note) donot apply. This rule does not impose an information collection burden under the provisions ofthe Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).

The Congressional Review Act, 5 U.S.C. section 801 etseq., as added by the Small Business Regulatory Enforcement Fairness Act of1996, 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 ofthe Congress andto the Comptroller General ofthe United States. EPA will submit areport containing this rule and other required information tothe U.S. Senate, the U.S. House ofRepresentatives, andthe Comptroller General ofthe United States prior to publication ofthe rule in the FederalRegister. A major rule
cannot take effect until 60 days after it is published in the Federal Register. This actionis not a "major rule" as defined by 5U.S.C. section 804(2). Under section 307(b)(1) ofthe Act, petitions forjudicial review ofthis action must be filed in the United States Court ofAppeals for the appropriate circuit byJanuary 14, 2002. Filing a petition for reconsideration by the Administrator ofthis final rule does not affect the finality ofthis rule for the
purposes ofjudicial review nor does it extend the time within which a petition forjudicial review may be filed, and shall not postpone the effectiveness of suchrule or action. This action may not be challenged later in proceedings to enforce its requirements. (See section 307(b)(2).)

List ofSubjects in 40 CFR Part52

Environmental protection, Air pollution control, Attainment, Hydrocarbons, Nitrogen oxides, Ozone, Incorporation by reference, Reporting and recordkeeping requirements.

Dated: October 15, 2001 GreggA. Cooke, Regional Administrator,Region6.

Part 52, chapter I, title 40 ofthe Code ofFederal Regulations is amended as follows:

PART 52-[AMENDED]

1. The authority citation for part 52 continues to read as follows:

Authority: 42 U.S.C. 7401 etseq. Subpart SS-Texas

2. In §52.2270, entries in the "EPA Approved Nonregulatory Provisions and Quasi-Regulatory Measures in the Texas SIP" table in paragraph (e) are addedto the end ofthe table to read asfollows:
§52.2270 Identificationof plan.

* * * * *



### (e)* * *

EPA APPROVED NONREGULATORY PROVISIONS AND QUASI-REGULATORY MEASURES INTHE TEXAS SIP

State subName of SIP provision Applicable geographic or mittal/effec- EPA approval date Comments nonattainment areadate

Attainment Demonstration for the 1-hour

Ozone NAAQS. Speed Limit Reduction

................................... Voluntary Mobile Emission Program

.............

Texas Senate Bill 5

........................................ Houston/Galveston, TX

......... Houston/Galveston, TX

......... Houston/Galveston, TX

......... Houston/Galveston, TX

......... Transportation Control Measures Appendix I Houston/Galveston, TX

.........
Commitment to Mid-course review

................ Houston/Galveston, TX

......... 112/09/00

12/09/00

12/09/00

9/26/00

12/09/00

4/19/01 [Insert 11/14/01 Federal Register cite]. [Insert 11/14/01 Federal Register cite]. [Insert 11/14/01 Federal Register cite]. [Insert 11/14/01 Federal Register cite]. [Insert 11/14/01 Federal Register cite]. [Insert 11/14/01 Federal Register cite]. Section 6.3.12

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