[Federal Register Volume 71, Number 172 (Wednesday, September 6, 2006)]
[Rules and Regulations]
[Pages 52670-52698]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-7412]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2005-TX-0018; FRL-8216-1]


Approval and Promulgation of Air Quality Implementation Plans; 
Texas; Revisions to the Ozone Attainment Plan for the Houston/
Galveston/Brazoria Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is approving revisions to the Texas State Implementation 
Plan (SIP) as it applies to the Houston/Galveston/Brazoria (HGB) ozone 
nonattainment area. These SIP revisions result from more recent 
information on ozone formation in the HGB area indicating that a 
combination of controls on nitrogen oxides (NOX) and highly 
reactive volatile organic compounds (HRVOCs) should be more effective 
in reducing ozone than the measures in the previously approved 2001 HGB 
attainment demonstration plan which relied almost exclusively on the 
control of NOX. Approval of these revisions incorporates 
these changes into the federally approved SIP.
    The approved revisions include a 1-hour ozone standard attainment 
demonstration, motor vehicle emissions budgets, a demonstration that 
all reasonably available control measures have been adopted for the HGB 
area and revisions to satisfy the enforceable commitments contained in 
the previously approved SIP. These revisions present a new mix of 
controlled strategies in order to achieve attainment. These revisions 
include changes to the industrial NOX rules, reducing the 
stringency from a nominal 90 percent to 80 percent control and 
revisions to the Texas Inspection and Maintenance (I/M) rules that drop 
three counties from the I/M program.
    As part of the approved revisions to the HGB attainment 
demonstration, Texas has adopted new control measures which EPA has 
approved or is approving concurrent with this action. The new control 
measures are increased control of HRVOC emissions and control of 
emissions from portable gasoline containers. Also, in separate actions 
in today's Federal Register, EPA is concurrently approving the 
following emissions trading programs that relate to the HGB attainment 
demonstration: revisions to the Mass Emissions Cap and Trade Program 
for the HGB area, the Highly Reactive Volatile Organic Compound 
Emissions Cap and Trade Program for the HGB area, the Emissions Credit 
Banking and Trading Program, and the Discrete Emissions Credit Banking 
and Trading Program.
    The SIP revisions to the HGB attainment demonstration addressed in 
this rulemaking along with the HRVOC rules and emissions trading 
programs being concurrently approved, will provide for timely 
attainment of the 1-hour ozone standard in HGB as demonstrated through 
the modeling analysis. Additionally, Texas has shown that these 
revisions will not interfere with any applicable requirement concerning 
attainment and reasonable further progress, or any other applicable 
requirement of the Clean Air Act. (Section 110(l) demonstration).

DATES: This rule is effective on October 6, 2006.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-R06-2005-TX-0018. All documents in the docket are listed on the 
www.regulations.gov Web site. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically through 
www.regulations.gov or in hard copy at the Air Planning Section (6PD-
L), Environmental Protection Agency, 1445 Ross Avenue, Suite 700, 
Dallas, Texas 75202-2733. The file will be made available by 
appointment for public inspection in the Region 6 FOIA Review Room 
between the hours of 8:30 a.m. and 4:30 p.m. weekdays except for legal 
holidays. Contact the person listed in the FOR FURTHER INFORMATION 
CONTACT paragraph below or Mr. Bill Deese at 214-665-7253 to make an 
appointment. If possible, please make the appointment at least two 
working days in advance of your visit. There will be a 15 cent per page 
fee for making photocopies of documents. On the day

[[Page 52671]]

of the visit, please check in at the EPA Region 6 reception area at 
1445 Ross Avenue, Suite 700, Dallas, Texas.
    The State submittal, which is part of the EPA record, is also 
available for public inspection at the State Air Agency listed below 
during official business hours by appointment:
    Texas Commission on Environmental Quality, Office of Air Quality, 
12124 Park 35 Circle, Austin, Texas 78753.

FOR FURTHER INFORMATION CONTACT: Erik Snyder, Air Planning Section 
(6PD-L), Environmental Protection Agency, Region 6, 1445 Ross Avenue, 
Suite 700, Dallas, Texas 75202-2733, telephone 214-665-7305; fax number 
214-665-7263; e-mail address [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, wherever ``we'', 
``us'', or ``our'' is used, we mean the EPA.

Table of Contents

I. Final Action
    A. What Is The Background for This Action?
    B. What Action Is EPA Taking?
    C. What Other SIP Elements Did We Need To Take Final Action on 
Before We Could Approve the Revised Attainment Demonstration?
II. What Revisions to State Implementation Plan Are Being Approved 
Here or in Other Concurrent Actions?
    A. One Hour Ozone Attainment Demonstration
    B. New Control Measures
    C. Control Measures Have Been Revised or Repealed
    D. Reasonably Available Control Measures
    E. Section 110(l) Analysis
    F. Enforceable Commitments
    G. Motor Vehicle Emission Budgets
III. What Is EPA's Response to Comments Received on the October 5, 
2005 Proposed Rulemaking for This Action?
    A. What Comments Were Received?
    B. Response to Comments on the Attainment Demonstration
IV. Statutory and Executive Order Reviews

I. Final Action

A. What Is the Background for This Action?

    On October 5, 2005, we proposed approval of the revisions to the 
SIP as it applies to the HGB ozone nonattainment area (70 FR 58119). 
The proposal provided a detailed description of these revisions and the 
rationale for our proposed actions, together with a discussion of the 
opportunity to comment. The proposed HGB attainment demonstration 
revisions relies upon four separate actions that EPA proposed for 
approval on October 5, 2005: Highly Reactive Volatile Organic Compound 
Emissions Cap and Trade Program for the HGB Ozone Nonattainment Area 
(70 FR 58138), Discrete Emission Credit Banking and Trading Program (70 
FR 58154), Emissions Banking and Trading Revisions for the Mass 
Emissions Cap and Trade Program for the HGB Ozone Nonattainment Area 
(70 FR 58112), and a Emission Credit Banking and Trading Program (70 FR 
58146). The public comment period for these proposed actions closed on 
November 4, 2005. One adverse comment letter and one comment letter 
supporting our action were received. The proposed SIP revision also 
relies upon a separate action that EPA proposed for approval on April 
7, 2005 (70 FR 17640) that included HRVOC rules requiring sources to 
monitor and control HRVOCs. For more information, see the Technical 
Support Documents or the proposal notices for the attainment 
demonstration or the five other notices. This SIP revision also relies 
upon a separate action that included measures controlling emissions 
from portable gasoline containers that EPA approved on February 10, 
2005 (70 FR 7041).
    The following submissions from Texas which requested revision of 
the HGB SIP were considered for this action:
    January 28, 2003: This submission responded to the State's 
settlement agreement to provide an accelerated evaluation of whether 
the industrial NOX controls could be substituted with 
controls on HRVOCs. Based on the study, the commission adopted rules 
substituting controls on NOX emissions from industrial 
sources with new controls on HRVOCs. Texas also adopted a number of 
minor revisions to the general VOC rules. Finally, the State also 
provided a demonstration that Texas Emission Reduction Program (TERP) 
emission reductions would be sufficient to achieve 25 percent of the 
NOX reductions needed to demonstrate attainment, i.e., about 
14 tons per day (tpd).
    October 16, 2003: This submission delayed compliance for the I/M 
program in Chambers, Liberty and Waller Counties. (Docket EPA-R06-OAR-
2005-TX-0035.)
    October 6, 2004: This submission repealed the I/M program in 
Chambers, Liberty and Waller Counties. (Docket EPA-R06-OAR-2005-TX-
0035.)
    November 16, 2004: This submission repealed a ban on morning 
operations of lawn service contractors.
    December 17, 2004: This submission met the State's commitment to 
provide a mid-course review SIP. Based on the updated analysis, the 
State further tightened controls on HRVOCs in Harris county and revised 
or repealed a number of NOX control measures including, the 
vehicle idling prohibition, the speed limit strategy, the voluntary 
mobile emissions program and the commitment to achieve NOX 
reductions beyond the initial 25 percent provided in January 2003 
(i.e., revoked the State's enforceable commitment to achieve 42 tpd of 
the NOX reductions that was included as part of the prior 
attainment demonstration).

B. What Action Is EPA Taking?

    We are approving the following revisions to the 1-hour ozone 
attainment plan for the HGB area:
     TCEQ's revised demonstration, submitted December 17, 2004, 
that the 1-hour ozone standard will be achieved in 2007, as required by 
the Texas State Implementation Plan, even though the ozone 1-hour NAAQS 
was revoked in June 2005.
     The revised motor vehicle emissions budgets associated 
with the revised attainment demonstration. The revised 2007 budgets are 
89.99 tons per day (tpd) for volatile organic compound emissions and 
186.13 tpd for NOX emissions.
     TCEQ's revised demonstration that all reasonably available 
control measures have been adopted for the HGB area.
     Revisions to satisfy the enforceable commitments contained 
in the previously approved SIP (November 14, 2001, 66 FR 57160). With 
respect to its original enforceable commitment to reduce NOX 
emissions, TCEQ has instead substituted reductions in HRVOCs for a 
portion of these NOX reductions and shown that the HRVOC 
reductions provide equivalent air quality benefits in reducing ozone 
levels.
     Revisions to the industrial NOX rules submitted 
January 28, 2003, which included several miscellaneous changes and the 
reduction in stringency from a nominal 90 percent to 80 percent 
control.
     Revisions to the Texas I/M rules that drop three counties 
from the I/M program. In addition, several miscellaneous changes are 
approved.
     Repeal of the vehicle idling rule.
     Repeal of the Small Spark Engine Operating Restrictions.
     Revisions to the Speed Limit Strategy.
     Revisions to the voluntary mobile emissions program.
    Our proposal to approve the revisions was published in the Federal 
Register on October 5, 2005 (70 FR 58119). Table 1 lists the revised 
elements of the HGB ozone SIP we are approving in this action.

[[Page 52672]]



  Table 1.--Revised Elements of the HGB Ozone SIP Being Approved by EPA
------------------------------------------------------------------------
                                 Date submitted
            Element                  to EPA              Comments
------------------------------------------------------------------------
1-hour standard attainment             12/17/04  Please see our proposed
 demonstration revisions.                         action and technical
                                                  support document for
                                                  more information.
Revised motor vehicle emissions        12/17/04  Revised budgets are
 budgets for 2007.                                89.99 tpd for volatile
                                                  organic compounds and
                                                  186.13 tpd for NOX.
Reasonably available control           12/17/04  Please see our proposed
 measures demonstration.                          action and technical
                                                  support document for
                                                  more information.
Revisions to satisfy the               12/17/04  Please see our proposed
 enforceable commitments                          action and technical
 contained int he previouisly                     support document for
 approved SIP (November 14,                       more information.
 2001, 66 FR 57160).
Revisions to the industrial NOX         1/28/03  Revisions to 30 TAC
 rules which included several                     Chapter 117, Sections
 misceallaneous changes and the                   117.10, 117.105-
 reduction in stringency from a                   117.108, 117.113-
 nominal 90% to 80% control.                      117.116, 117.119,
                                                  117.131, 117.135,
                                                  117.138, 117.141,
                                                  117.143, 117.149,
                                                  117.203, 117.205-
                                                  117.207, 117.213-
                                                  117.216, 117.219,
                                                  117.223, 117.301,
                                                  117.309, 117.311,
                                                  117.313, 117.319,
                                                  117.321, 117.401,
                                                  117.409, 117.411,
                                                  117.413, 117.419,
                                                  117.421, 117.463,
                                                  117.465, 117.473,
                                                  117.475, 117.478,
                                                  117.479, 117.510,
                                                  117.512, 117.520, and
                                                  117.534.
                                                 Repeal of 30 TAC
                                                  Chapter 117, Sections
                                                  117.104, 117.540, and
                                                  117.560.
Revisions to the Texas I/M              10/6/04  Revisions to 30 TAC
 rules that drop three counties                   Chapter 114,
 from the I/M program and make                    Sections114.1, 114.2,
 several misceallaneous changes.                  114.50, 114.52, and
                                                  114.53.
Repeal of the vehicle idling           12/17/04  Repeal of 30 TAC
 rule.                                            Chapter 114, Sections
                                                  114.500, 114.502,
                                                  114.507, and 114.509.
Repeal of the Small Spark              11/16/04  Repeal of 30 TAC
 Engine Operating Restrictions.                   Chapter 114, Sections
                                                  114.452 and 114.459.
Revisions to the voluntary             12/17/04  Please see our proposed
 mobile emissions program.                        action and technical
                                                  support document for
                                                  more information.
------------------------------------------------------------------------

    Texas has adopted a revised attainment demonstration that includes 
the following new control measures:
     Hourly (short-term) limit and Annual Cap on HRVOC 
emissions.
     Improved requirements for HRVOC Leak Detection and Repair 
Program for fugitive emissions and flare monitoring.
     Requirements for portable gasoline containers. (EPA 
approved February 10, 2005.)
    We approved the measure controlling emissions from portable 
gasoline containers on February 10, 2005 (70 FR 7041). The SIP 
revisions addressed in this rulemaking in conjunction with the new 
HRVOC rules, will provide for timely attainment of the 1-hour ozone 
NAAQS as demonstrated through the modeling analysis. In addition, Texas 
has shown that these revisions will not interfere with any applicable 
requirements concerning attainment and reasonable further progress, or 
any other applicable requirement of the Clean Air Act, (Section 
110(l)).

C. What Other SIP Elements Did We Need To Take Final Action on Before 
We Could Approve the Revised Attainment Demonstration?

    In our proposed action we explained that we could not finalize 
approval of the revised attainment demonstration for HGB until we 
finalized approval of several related actions. These actions are 
discussed below. In a separate rulemaking published in this issue of 
the Federal Register we are approving the new measures to control HRVOC 
emissions as part of the basis for this approval of revisions to the 
HGB attainment SIP. In this action, when we refer to this program as 
``the HRVOC rule'' or ``the HRVOC control program'', we are speaking of 
the entire rule package entitled ``Control of Highly Reactive Volatile 
Organic Compound Controls''. (Docket ID No. EPA-R06-OAR-2005-TX-0033.)
    The HRVOC rules were adopted by TCEQ based on recent findings that 
certain highly reactive chemicals (ethylene, propylene, 1,3 butadiene 
and butenes) contribute disproportionately to the ozone problem in the 
HGB area. EPA previously issued a proposed approval of the HRVOC rules 
on April 7, 2005 (70 FR 17640).
    In separate rulemakings published in today's Federal Register we 
are approving additional measures related to the Revised 1-hour ozone 
Attainment Demonstration for HGB. These rules include the HRVOC 
Emissions Cap and Trade Program for the HGB ozone nonattainment area, 
Discrete Emission Credit Banking and Trading Program (conditional 
approval), Emissions Banking and Trading Revisions for the Mass 
Emissions Cap and Trade Program for the HGB ozone nonattainment area, 
and an Emissions Credit Banking and Trading Program. These actions are 
further discussed in Section II.B. of this notice.

II. What Revisions to the State Implementation Plan Are Being Approved 
Here or in Other Concurrent Actions?

A. One Hour Attainment Demonstration

    As required by the Clean Air Act, Texas has used photochemical grid 
modeling in its demonstration that the control strategy for the HGB 
area will achieve attainment of the 1-hour ozone NAAQS by 2007. Also, 
as allowed for under EPA policy, TCEQ has introduced other evidence, 
referred to as weight of evidence, to supplement the modeling analysis. 
The modeling provided in the mid-course review SIP revision builds on 
modeling performed for the January 2003 SIP revision which TCEQ 
submitted in support of reducing the stringency of the industrial 
NOX rules and adopting measures for the control of HRVOCs.
    This SIP revision actually relies on two sets of modeling analyses. 
First, it relies on modeling performed by the TCEQ that is intended to 
simulate the routine emissions that occur in the HGB area and determine 
the level of routine emissions that can be allowed in the area yet 
still provide for attainment. Second, the SIP relies on modeling that 
was provided through a collaborative effort (known as project H13) of 
the Houston Advanced Research Center, the TCEQ, the University of Texas 
and the University of North Carolina. The project H13 report was 
entitled,

[[Page 52673]]

``Variable Industrial VOC Emissions and Their Impact on Ozone Formation 
in the Houston Galveston Area,'' April 16, 2004. This second modeling 
effort was used to estimate the impact of non-routine emission events 
on ozone levels. This two-pronged approach is consistent with 
observations that indicate that Houston's air quality problems stem 
from the combination of two phenomena, normal routine emissions and 
large non-routine releases of HRVOC emissions. For a more complete 
description of the modeling procedures and EPA's evaluation of these 
procedures, see the Technical Support Document (TSD) in the Docket for 
this action (RO6-OAR-2005-TX-0018) and the FR proposal notice October 
5, 2005 (70 FR 58119).

B. New Control Measures

    TCEQ has adopted the following new control measures since the 
previously approved SIP revision:
     Hourly (short-term) limit and Annual Cap on HRVOC 
emissions.
     Improved requirements for HRVOC Leak Detection and Repair 
Program for fugitive emissions and flare monitoring.
     Requirements for portable gasoline containers. (EPA 
approved February 10, 2005).
1. Hourly (Short-Term) Limit and Annual Cap on HRVOC Emissions
    As discussed in the proposal notice (70 FR 58119) and Technical 
Support Document (TSD), Texas relied primarily on two sets of modeling 
in developing its control strategy. One set of modeling, performed by 
TCEQ, is largely a traditional model formulation that examines the 
routinely variable emissions which occur in the HGB area. Through this 
modeling, TCEQ established that NOX emissions would not have 
to be reduced as much as previously planned and routine emissions of 
highly-reactive VOC emissions would have to be reduced. Through the 
second set of modeling, examining the impact of large non-routine 
releases of HRVOCs, it was established that the frequency and magnitude 
of large non-routine releases of HRVOCs should also be reduced.
    Using both sets of modeling, TCEQ developed a key feature of the 
HGB attainment strategy: Routine HRVOC emissions are targeted and 
reduced through an annual cap-and-trade program, while the non-routine 
emissions from emission events, maintenance, start-up and shutdown are 
controlled through a short-term limit of 1200 lbs/hour. In a related 
rulemaking in today's Federal Register, EPA is concurrently approving 
the Highly-Reactive Volatile Organic Compound Emissions Cap and Trade 
Program to control routine emissions of HRVOCs (see EPA-R06-OAR-2005-
TX-0033). Unique to the HGB attainment strategy, exceedances of the 
short-term limit are not counted toward compliance with the annual cap 
but are still subject to enforcement as a violation of the short-term 
limit.
    Again, EPA recognizes that the approach of providing this partial 
exclusion for emissions above the short-term limit is a departure from 
practices in other cap and trade programs such as the acid rain program 
and our guidance. We currently believe this approach is only warranted 
in consideration of the Houston area's unique situation that combines 
an extensive petrochemical complex and the availability of the 
extensive data and analysis that were generated by the intensive ozone 
study, TxAQS 2000 and in conjunction with a short-term limit. 
Consideration of this novel approach is warranted in order to balance 
the need to reduce both routine and upset emissions of HRVOC, but also 
recognizes that large upset emissions are difficult to control in the 
petrochemical industry and one significant event could result in a 
facility consuming more than a month's emission allotment.
2. Improved Requirements for HRVOC Leak Detection and Repair Program 
for Fugitive Emissions and Flare Monitoring
    TCEQ has implemented a number of new requirements for leak 
detection and repair of components in HRVOC service. The changes 
include, among other things, the following improvements:
     Inclusion of connectors in the program.
     Inclusion of other non-traditional potential leak sources 
such as heat exchanger heads and man-way covers.
     Elimination of allowances for skipping leak detection 
periods for valves.
     Requirements for third party audits to help insure that 
effective leak surveys and repairs are conducted.
     Requirements that ``extraordinary'' efforts be used to 
repair valves before putting them on the delay of repair list.
    For purposes of estimating emissions for compliance with the Short-
term and annual caps, TCEQ adopted rules requiring companies to assume 
specific flare destruction efficiencies for properly operating flares 
and for when a flare operates outside the parameters of 40 CFR 60.18. 
EPA is approving the estimates used for flare destruction efficiency 
for use in the attainment demonstration because the estimates are based 
on the best information available. We, however, remain concerned about 
the uncertainty created in the attainment demonstration by having a 
significant source of emissions which cannot be directly measured.
    We note that some operating parameters for flares such as steam and 
air assist ratios are not covered specifically by 40 CFR 60.18 but some 
studies have indicated these parameters can impact flare efficiency. 
Because of the prevalence of flares in the HGB area, we believe Texas 
should strongly consider, for both flares in HRVOC service and general 
VOC service, requirements for monitoring steam and air assist ratios to 
insure that operators maintain these parameters, not covered by 40 CFR 
60.18, in a range to insure optimum combustion. We also encourage TCEQ 
to pursue new technology such as the Fourier Transform Infrared 
Spectrophotometer which would eventually allow the direct measurement 
of destruction efficiency in the field.
    For a full discussion of the improvements to these programs, see 
the Proposal Notice and Technical Support Document for this action. EPA 
is approving the emission reductions that have been projected for the 
improved leak detection and repair rules. Our approval is based on the 
improvements to the fugitive rule and Texas' commitment to perform a 
rule effectiveness study and use improved emission inventory techniques 
to estimate future emissions to confirm the effectiveness of the 
program.
3. Requirements for Portable Gasoline Containers
    TCEQ has adopted standards for portable fuel containers sold in the 
State which provide requirements to prevent leaks and spills. EPA 
approved the TCEQ rules on February 10, 2005 (70 FR 7041). TCEQ 
projected 2.9 tons/day of VOC emission reductions that are included in 
the revised attainment demonstration modeling.

C. What Control Measures Have Been Revised or Repealed?

    Texas has revised a number of control strategies that were included 
in the previously approved SIP. A brief description of the revisions 
that EPA is approving follows. More details are provided in the 
proposal notice (70 FR 58119) and Technical Support Document (TSD) 
materials.
    Industrial NOX Controls: Texas revised its NOX rules to 
reduce the controls from a nominal 90 percent control to 80 percent 
control. We are approving the revisions to industrial NOX 
controls in the HGB area.

[[Page 52674]]

    Vehicle Inspection and Maintenance Program in Three Rural Counties: 
TCEQ has dropped the requirement for I/M in Waller, Liberty and 
Chambers Counties. We are approving the removal of the I/M program in 
these three counties.
    Removal of Small, Spark-Ignition Engine Operating Restrictions: 
TCEQ has dropped this requirement which would have prohibited 
commercial lawn services from operating during the morning hours. We 
are approving the removal of these operating restrictions on small, 
spark-ignition engines.
    Speed Limit Strategy from a 55 mph Maximum Speed Limit to a 5 Mile 
Reduction in Speed Limits from Previous Levels: The Texas legislature 
repealed TCEQ's authority to implement speed limits for environmental 
purposes. Texas Department of Transportation had already reduced speeds 
in the HGB area by 5 mph from 70 mph to 65 mph and from 65 to 60. These 
reductions in speed limits of 5 mph remain in place, but the reductions 
that would have been achieved by reducing speed limits on all roads 
further to 55 mph will not be achieved.
    Removal of the Vehicle Idling Restriction: This measure that would 
have prohibited prolonged idling of heavy duty diesel vehicles has been 
repealed. We are approving the repeal of this rule.
    Revision to Delay the Compliance Date for Gas Fired Water Heaters 
and Small Boilers: This rule is not being repealed, but its compliance 
date has been delayed from December 31, 2004 to January 1, 2007. This 
rule requires new water heaters sold in Texas to achieve lower 
NOX emission rates.
    We are not approving changes to the rules for control of water 
heaters at this time. It is a Statewide rule and the changes to the 
rule impact other areas of the State and we have not yet analyzed the 
above issues in areas of the State other than Houston. We note only 
that the changes to the water heater rules do not impact the 
approvability of the Houston mid-course review SIP revision.
    Revisions to the Voluntary Measures: Texas has revised the 
voluntary mobile emissions program (VMEP) portion of the SIP. The VMEP 
portion of the SIP that was approved in 2001, and was projected to 
achieve 23 tpd of emissions reductions through various voluntary and 
often innovative measures. TCEQ has recalculated the benefits as 
yielding 7 tpd of NOX emission reductions. We are approving 
the revisions to the VMEP.

D. Reasonably Available Control Measures

    A brief description of the Reasonably Available Control Measures 
(RACM) revisions follows, for more details see the proposal notice (70 
FR 58119) and Technical Support Document (TSD) materials.
    In EPA's November 14, 2001 notice approving the plan for the HGB 
nonattainment area, EPA approved the analysis showing the plan was 
implementing all Reasonably Available Control Measures. The 
NOX reduction requirements of that plan were so substantial 
no additional RACM measures could be identified in time for adoption as 
a part of that plan and the State had to make an enforceable commitment 
to adopt additional NOX measures which were expected to be 
feasible in the near future. Now, based on the findings of the mid-
course review, Texas has determined that the NOX reductions 
necessary for attainment, while still substantial, are not as great and 
that control of HRVOCs is a more effective way of reducing ozone. Both 
NOX and HRVOC controls, necessary for attainment, will be 
fully implemented the last year of the strategy. In the last year of 
the strategy, the point source controls alone will achieve an estimated 
39 tpd of NOX reductions (based on review of the TCEQ's Mass 
Cap-and-Trade Registry). Reductions in on- and off-road emissions will 
also occur. Therefore, to advance attainment, additional reductions on 
the order of 39 tpd would have to be achieved before the ozone season 
of 2006. In Section 5.4 of the State Implementation Plan, Texas 
explains why even with the repeal and revision of the measures, Texas 
believes the RACM requirement is still being met. What follows is a 
brief summary of EPA's evaluation of each of the revisions being 
approved.
    Industrial NOX Controls: TCEQ has relaxed the 
NOX rules for a number of NOX point source 
categories. The original controls achieved a nominal 90% reduction in 
point source emissions, with some categories reducing more than 90% and 
some less than 90%. The new rules, being approved here today, achieve a 
nominal 80% control. It is a convenient short hand to refer to the 
control levels as 90% or 80% even though this does not accurately state 
the level of reduction for individual source categories. TCEQ has 
argued that the 90% controls would not advance attainment because the 
current 80% control levels are scheduled to be implemented in 2007 and 
it would not be reasonable to expect that a more stringent 90% control 
could be implemented faster to advance attainment. EPA previously 
agreed that the most expeditious schedule for the 90% controls would be 
by 2007. EPA continues to believe that to be the case so that 
implementation of 90% controls would not advance attainment. Even at 
the 80% control level, the TCEQ rules are still similar in stringency 
to the control levels implemented in California which have generally 
been considered the most stringent in the country.
    Repeal of the I/M Program in 3 Rural Counties: Texas has chosen to 
reduce the scope of its I/M program from eight counties to five 
counties. The three counties that are being dropped are Chambers, 
Liberty and Waller Counties which are the most rural counties in the 
nonattainment area. The program was scheduled to be implemented in 
2005. Using Mobile6, Texas has estimated that the program would achieve 
0.87 tpd of emission reductions which is a smaller reduction estimate 
than the Mobile 5 estimate included in the 2000 SIP and is less than 
0.2% of the projected emissions for the area in 2007. Because of the 
small amount of emission reductions, implementation of I/M in these 
three counties would not be expected to advance attainment and 
therefore should not be considered RACM.
    Removal of Small Spark Operating Restrictions: This measure would 
prohibit lawn and garden service contractors for operation in the 
morning hours from 6 am to 10 am. This measure was due to be 
implemented in 2005. Texas decided that attainment could be reached 
without the implementation of this measure. The measure was estimated 
to achieve the equivalent of 7.7 tons/day of NOX emission 
reductions. As such, its implementation would not advance the 
attainment date. Therefore, EPA believes the morning lawn service ban 
should not be considered a reasonably available control measure for the 
HGB area.
    Speed Limit Strategy: The previously approved SIP provides for the 
speed limits in the eight county area to be reduced to 55 mph. Later, 
TCEQ decided to delay the implementation of the 55 mph until 2005, but 
would implement speed limits that are 5 mph lower than the previous 
speed limits, lowering 70 mph speed limits to 65 mph and 65 mph limits 
to 60 mph starting in 2001. In the 2004 SIP revision, TCEQ decided to 
make permanent the interim limits and forgo lowering the speed limits 
to 55 mph. Based on Mobile6, lowering speeds all the way to 55 mph 
would be expected to reduce emissions 2-3 tons/day. This is a lower 
estimate

[[Page 52675]]

of emission reductions than predicted by Mobile5 in the 2000 SIP 
revision. This small amount of emission reduction would not advance 
attainment in the Houston area and therefore this measure is not 
considered RACM.
    Vehicle Idling Restriction: Texas is dropping a rule that prohibits 
idling of heavy duty vehicles for more than five minutes in the Houston 
area. The measure was estimated to reduce NOX emissions by 
0.48 tpd. Texas decided that attainment could be reached without the 
implementation of this measure. This small amount of emission reduction 
would not advance attainment for the area and therefore should not be 
considered RACM.
    Delay in Compliance for the Water Heater Rule: In this case, TCEQ 
still intends to implement the rule, but has delayed compliance until 
2007. Since the adoption of the current rule, two American National 
Standards Institute (ANSI) standards (the flammable vapor ignition 
resistance standard and the lint, dirt, and oil standard); the United 
States Department of Energy (DOE) energy efficiency standard; and the 
EPA insulation foam ban have been implemented. The ANSI lint, dirt, and 
oil standard and the flammable vapor ignition resistance standard were 
effective on July 1, 2003, and were established for gas-fired water 
heater safety reasons. The DOE energy efficiency standard was effective 
on January 20, 2004. The EPA foam ban was effective on January 1, 2003, 
and affects gas-fired water heaters, as water heater manufacturers have 
historically used hydrochlorofluorocarbon as a blowing agent for 
creating foam insulation. The implementation of these standards has 
delayed the progression of the water heater technology and design. 
Therefore, a design that meets the 10 ng/J emission limit in the Texas 
rule will not be available for sale in the market by the January 1, 
2005 compliance date.
    Because the new federal standards affect the design of new water 
heaters and have made it impractical for the industry to meet Texas's 
NOX limits for water heaters in a timely manner, EPA agrees 
that this measure is being implemented as expeditiously as is 
technically practicable. In other words, earlier implementation is not 
technically practicable and therefore, since it would be infeasible, it 
would not advance attainment.
    We have reviewed these changes in RACM that are summarized above 
and discussed these changes in greater detail in our TSD. We are 
approving these changes to RACM as part of the approval of this 
attainment demonstration revision approval and determining that TCEQ 
has satisfied the RACM requirements.

E. Section 110(l) Analysis

    A brief description of the 110(l) analysis follows, for more 
details see the proposal notice (70 FR 58119) and Technical Support 
Document (TSD) materials. Section 110(l) of the Clean Air Act says:

Each revision to an implementation plan submitted by a State under 
this Act shall be adopted by such State after reasonable notice and 
public hearing. The Administrator shall not approve a revision of a 
plan if the revision would interfere with any applicable requirement 
concerning attainment and reasonable further progress (as defined in 
section 171), or any other applicable requirement of this Act.

    As previously discussed, Texas has developed a revised strategy 
which relies on fewer reductions of NOX and more reductions 
of VOC. Texas determined that the revisions will not interfere with 
attainment or reasonable further progress or any other applicable 
requirement under the Act and after careful review, EPA agrees. Texas 
has completed the revised attainment demonstration with respect to the 
1-hour standard which is being approved today. Attainment 
demonstrations for the 8-hour standard are not required until June 
2007.
    Prior to the time that attainment demonstrations are due for the 8-
hour ozone standard, it is unknown what suite of control measures a 
State will choose to adopt for a given area to attain that standard. 
During this period, to demonstrate no interference with the 8-hour 
NAAQS, EPA believes it is appropriate to allow States to substitute 
equivalent emission reductions (to compensate for control measures 
being removed) which result in equal or greater air quality benefit 
than those reductions being removed from the approved SIP. EPA believes 
that preservation of the status quo in air quality during the time in 
which new attainment demonstrations are being developed for the 8-hour 
ozone NAAQS will prevent interference with the States' obligations to 
develop timely attainment demonstrations and to attain as expeditiously 
as practicable.
    To show that the compensating emission reductions are equivalent, 
modeling or adequate analysis must be provided. The compensating 
emission reductions must provide actual, new emission reductions 
achieved in a contemporaneous time frame in order to preserve the 
status quo. In addition, the emission reductions must be permanent, 
enforceable, quantifiable, and surplus to be approved into the SIP. EPA 
has determined that the revised HGB SIP has met each of these 
requirements. See the proposal notice (70 FR 58119) and Technical 
Support Document (TSD) materials.
    Contemporaneous: While contemporaneous is not defined in the Clean 
Air Act, a reasonable interpretation is that the compensating control 
measures be implemented within one year of the time frame for the 
control measure being replaced. In this case, the new control measures 
being used as substitutes are being implemented in virtually the same 
time frames as the measures being replaced. The new measures have the 
following compliance dates: tighter controls on HRVOC fugitive 
emissions by March 31, 2004, monitoring for the HRVOC cap by 2005, 
compliance with the HRVOC cap starting in 2006, and gas can rule 
implementation in 2007. The measures being replaced, which are listed 
previously in this notice, with the exception of the vehicle idling 
ban, all had compliance dates in the approved SIP of 2005 or later. In 
particular the largest emission reduction change by far, the difference 
between 90 percent and 80 percent control on NOX, was not 
scheduled to be fully realized until 2007. The enforceable commitment 
measures only provided that the measures would be adopted by May 2004 
and compliance would be achieved as expeditiously as possible but no 
later than the beginning of the ozone season in 2007. Therefore, it can 
be assumed the emission reductions from the NOX enforceable 
commitments, had they been implemented, would not have occurred before 
the 2005-2006 time frame, a time frame similar to that for the measures 
to control HRVOCs which Texas has adopted a substitute. With regard to 
the vehicle idling restrictions, the compliance date for this rule was 
May of 2001. It was projected to achieve 0.48 tpd of NOX 
emission reductions. It was discontinued effective December 23, 2004. 
The improved HRVOC fugitive controls which began implementation in 
March of 2004, more than offset the small reductions lost by the 
discontinuation of the motor vehicle idling program after December 23, 
2004.
    Equivalent: To demonstrate that the emission reductions were 
equivalent, the TCEQ used the photochemical model to demonstrate that 
the total collection of strategies in the current SIP revision is 
equivalent or better in 8-hour ozone reduction effectiveness as 
compared with the total collection of strategies in the SIP that was 
approved in 2001, including the reductions that

[[Page 52676]]

would have occurred due to measures to meet the enforceable 
commitments. Several 8-hour ozone metrics were calculated. EPA believes 
that the new strategy and the old strategy are approximately equivalent 
in 8-hour ozone benefit, with the new strategy slightly more effective 
in reducing the peak ozone values and the old strategy slightly more 
effective in reducing the predicted area of exceedances. Taking all of 
the metrics into consideration and recognizing the uncertainties in the 
modeling, we believe that Texas has demonstrated that the new strategy 
is equivalent to the old strategy in 8-hour ozone benefit.
    Permanent: The emission reductions from the HRVOC rules are 
permanent as sources will have to maintain compliance with new measures 
indefinitely.
    Enforceable: EPA has reviewed the enforceability of the substitute 
measures in separate rules.
    The Portable Fuel Container Rule was approved: February 10, 2005, 
70 FR 7041. EPA is also approving concurrently in a separate notice the 
fugitive emission controls and improved monitoring requirements for 
HRVOCs (proposal on April 7, 2005, 70 FR 17640). Finally, concurrent 
with this Federal Register notice EPA is approving the HECT program. In 
each of these rulemakings, EPA has evaluated whether the substitute 
rules are enforceable, considering such issues as whether the rules 
have adequate test methods, monitoring requirements, record keeping 
requirements and whether the State has adequate enforcement authority 
to ensure the limits are achieved. By our approval elsewhere in the 
Federal Register today, these substitute rules are federally 
enforceable and enforceable by the public through citizen suit.
    In summary, we believe the substitute measures result in equivalent 
8-hour benefit and that the new measures are contemporaneous, 
enforceable and permanent. Therefore, we believe approval of these 
revisions to the approved SIP will not interfere with attainment of the 
8-hour standard.
    The 1-hour standard was revoked on June 15, 2005 for the HGB area. 
The approved SIP, however, committed the State to adopt control 
measures of 56 tpd of NOX, unless the State could show that 
these NOX reductions were not needed for attainment of the 
1-hour standard. We have discussed elsewhere in this notice (and in the 
proposal and TSD), EPA's evaluation of the revised 1-hour attainment 
demonstration and are approving these revisions.
    Texas submitted, and EPA has approved, revisions to the rate of 
progress (ROP) plan (February 14, 2005, 70 FR 7407) based on the 
revised strategy. These revisions will ensure that 1-hour ROP is met 
for each three year period out to the 1-hour attainment date of 
November 15, 2007.
    Other than for ozone, the HGB area currently meets all other 
National Ambient Air Quality Standards. The plan revisions being 
considered would not be expected to impact compliance with the CO, 
SO2 or Lead NAAQS as these pollutants are not affected by 
these rules.
    The revisions to the NOX rules do affect emissions of 
NO2 and thus could potentially impact attainment with the 
NO2 standard. The HGB area, however, meets the 
NO2 standard at today's level of NO2 emissions 
and the revised plan will reduce NO2 emissions dramatically 
from existing levels and thus will not interfere with maintenance of 
the NO2 standard.
    Similarly, the HGB area currently meets the NAAQS for 
PM2.5. NOX and VOCs are precursors to the 
formation of PM2.5. Although the revised plan does not 
reduce NOX emissions as much as the previous attainment 
demonstration SIP revision approved by EPA in November 2001, the 
revised plan will result in additional NOX and VOC 
reductions beyond today's levels (emission levels at the time of this 
notice). Therefore, the revised plan will not interfere with the 
continued attainment of the PM2.5 standard.
    Section 110(l) applies to all requirements of the Clean Air Act. 
Below are requirements potentially affected by TCEQ's rule change and a 
brief discussion of EPA's analysis.
    Reasonably Available Control Technology (RACT) requirements: EPA 
has previously approved the NOX and VOC rules in the HGB 
area as meeting the CAA's RACT requirements. The revised NOX 
rules remain substantially more stringent than the previously approved 
RACT requirements. The new HRVOC rules build on the previously approved 
RACT requirements. In addition, these revisions do not impact the major 
sources applicability cutoffs. Therefore, these revisions do not 
interfere with the implementation of RACT.
    Inspection and maintenance programs (I/M): This revision drops 
three counties from the I/M program. These counties are not included in 
the urbanized area as defined by the Census Bureau. Thus, I/M is not 
required to be implemented in these counties and these revisions do not 
interfere with meeting the I/M requirements of the CAA.
    Air Toxics: There are no Federal ambient standards for air toxics 
and these rules do not interfere with implementation of any federal 
MACT standards, therefore, these rule revisions do not interfere with 
compliance with any air toxics standards under sections 112 or 129 of 
the CAA. We note that air toxic levels of butadiene and formaldehyde 
are expected to decrease as a result of the revised plan, because the 
HRVOC rules directly regulate emissions of butadiene and ethylene. 
Formaldehyde is formed from ethylene in the photochemical reactions 
leading to ozone.

F. Enforceable Commitments

    In the SIP approved in November 2001, there were enforceable 
commitments to achieve additional NOX reductions and 
enforceable commitments to incorporate the latest information into the 
SIP. This section contains a brief summary of the enforceable 
commitments which were approved in the November 2001 Federal Register 
and a short discussion of how they were met or are being revised.
    Commitment: To perform a mid-course review (including evaluation of 
all modeling, inventory data, and other tools and assumptions used to 
develop this attainment demonstration) and to submit a mid-course 
review SIP revision, with recommended mid-course corrective actions, to 
the EPA by May 1, 2004.
    Discussion: Texas provided, in the December 2004 submission, a mid-
course review that included new modeling with new more recent episodes 
(including updated emissions) based on the Texas 2000 study. The State 
submitted control measures that, based on the demonstration, will 
result in attainment of the 1-hour standard as expeditiously as 
practicable. Therefore, EPA believes the commitment for a mid course 
review has been satisfied.
    Commitment: To perform new mobile source modeling for the HG area, 
using Mobile6, EPA's on-road mobile emissions factor computer model, 
within 24 months of the model's release.
    Discussion: The mid-course review modeling employed Mobile6 for the 
on-road mobile source inputs satisfying this commitment.
    Commitment: If a transportation conformity analysis is to be 
performed between 12 months and 24 months after the Mobile6 release, 
transportation conformity will not be determined until Texas submits an 
MVEB which is developed using MOBILE6 and which we find adequate.
    Discussion: This commitment was not applicable because 
transportation

[[Page 52677]]

conformity was not performed during the time period.
    Commitment: To adopt rules that achieve at least the additional 56 
tpd of NOX emission reductions that are needed for the area 
to show attainment of the 1-hour ozone standard, including the adoption 
of measures to achieve 25% (14 tpd) of the needed additional reductions 
(56 tpd), and to submit those adopted measures to EPA as a SIP revision 
by December 2002. To adopt measures for the remaining needed additional 
reductions and submit these adopted measures to EPA as a SIP revision 
by May 1, 2004.
    Discussion: In the January 28, 2003 submission, TCEQ provided the 
demonstration that the TERP program meets EPA's requirements as an 
economic incentive program and will achieve the required 14 tons/day of 
emissions reductions. EPA has approved the TERP program in a separate 
Federal Register action which discusses how the TERP program meets the 
EIP requirements (August 19, 2005, 70 FR 48647). Through the attainment 
year of 2007, 38.8 tons/day of emission reductions are projected for 
the TERP program based on a $5,000/ton cost effectiveness. The total 
obligation for emission reductions from TERP is 32.9 tpd. TERP 
originally replaced two measures: a morning construction ban (6.7 tpd 
NOX equivalent) and accelerated introduction of Tier II/III 
equipment (12.2 tpd). After allocating 18.9 tpd from TERP to replace 
these two measures, the program still is projected to produce an 
additional 19.9 tpd of reductions which is sufficient to provide the 
additional 14 tpd of emissions reductions needed to meet the 
enforceable commitment. Thus, EPA believes the enforceable commitment 
to achieve 25% of the 56 tpd of NOX reductions has been 
satisfied.
    We note two developments with the program. The average cost 
effectiveness of TERP projects, to date, is $5500/ton and the Texas 
legislature moved to cut some of the funding for the program in the 
last session. TCEQ may have to shift some of the TERP funding from 
other areas such as Corpus Christi or Victoria, which currently meet 
the 8-hour ozone standard, to the HGB area to insure that the emission 
reduction targets are met.
    For the rest of the enforceable commitments to adopt and submit 
rules to achieve the remaining 42 tpd NOX reductions due by 
May 1, 2004, Texas determined that these additional NOX 
reductions would not be necessary for the area to attain. Instead, as 
discussed elsewhere in this document and the proposed approval notice 
(70 FR 58119), TCEQ has instead adopted and has begun implementing a 
strategy to reduce emissions of HRVOCs. EPA believes that the new 
strategy will attain the one-hour standard. This is further discussed 
in other sections of this notice, the proposal notice, and the TSD.
    Commitment: That the rules will be adopted as expeditiously as 
practicable and the compliance dates will be expeditious.
    Discussion: TCEQ adopted its measures for the control of HRVOC 
first in 2002 and has revised them three times since then. The 
compliance dates in the rules are based on the need to develop 
monitoring plans, quality assurance/quality control programs, install 
the monitors, and develop control plans based on the monitoring 
results. EPA believes that the implementation of these new measures is 
as expeditious as practicable.
    Commitment: That the State would concurrently revise the Motor 
Vehicle Emissions Budgets (MVEBs) and submit as a revision to the 
attainment SIP if additional control measures reduce on-road motor 
vehicle emissions. Texas stated that measures which could limit future 
highway construction, such as growth restrictions, may not be included.
    Discussion: Texas has revised the mobile source budget to account 
for TERP reductions and other adjustments to the mobile source 
emissions estimates.
    Summary: Based on the above analysis, we have determined that TCEQ 
has satisfied the requirements of the enforceable commitments contained 
in the approved Houston/Galveston SIP.

G. Motor Vehicle Emissions Budgets

    The MVEBs established by this plan and that EPA is approving are 
contained in Table 2. The development of the MVEBs are discussed in 
section 3.5 of the SIP and were reviewed in the TSD. We are approving 
the new MVEB because we find the budget to be consistent with the 
attainment plan.

     Table 2.--2007 Attainment Year Motor Vehicle Emissions Budgets
                             [Tons per day]
------------------------------------------------------------------------
                          Pollutant                               2007
------------------------------------------------------------------------
VOC..........................................................      89.99
NOX..........................................................     186.13
------------------------------------------------------------------------

III. What Is EPA's Response to Comments Received on the October 5, 2005 
Proposed Rulemaking for This Action?

A. What Comments Were Received?

    The following comment letters were received on the October 5, 2005 
proposal:
    (1) November 4, 2005 letter from John D. Wilson, Executive Director 
of Galveston-Houston Association for Smog Prevention for the Galveston-
Houston Association for Smog Prevention, Environmental Defense (Texas 
Office), Lone Star Chapter of the Sierra Club, and Public Citizen 
(Texas Office). Comments from this group will be referred to as 
``(Wilson)''.
    (2) November 4, 2005 letter from Matthew L. Kuryla of Baker Botts 
LLP on behalf of BCCA Appeal Group. Comments from this group will be 
referred to as ``commenter (BCCAAG)''. Commenter BCCAAG included a list 
of BCCA Appeal Group members as follows: Air Products, L.P.; Dynegy, 
Inc.; Entergy Gulf States, Inc.; Enterprise Products Operating, L.P.; 
Exxon Mobil Corporation; Greater Fort Bend Economic Development 
Council; Lyondell Chemical Company; Reliant Energy, Inc.; Shell Oil 
Company; Texas Genco; Texas Instruments Incorporated; Texas 
Petrochemicals, L.P.; and Valero Refining-Texas, L.P.

B. Response to Comments on Attainment Demonstration

    In general the commenter (BCCAAG) indicated that they support 
approval of the proposed attainment demonstration revisions and did not 
have any adverse comments on this SIP revision. They indicated that the 
revisions represent the most effective, technically and scientifically 
robust plan yet advanced for achieving air quality goals in the HGB 
airshed and the revised control strategy will bring the area into 
attainment. They continued by indicating that the revised plan is 
already reducing the number of days that ozone exceedances occur and 
the magnitude of the high and second high ozone value at regulatory 
monitors has decreased substantially in the last three years. Commenter 
(BCCAAG) supported the proposed approval indicating that the revised 
plan did meet RACM and the revised control strategy would reach 
attainment.
1. General Comments
    Comment GC1: A commenter (Wilson) indicated that the proposed plan 
fails to adequately demonstrate that its implementation, maintenance, 
and enforcement will lead to attainment of

[[Page 52678]]

the 1-hour national air ambient quality standards (NAAQS) for ozone in 
the Houston-Galveston-Brazoria (HGB) area. State ambient monitoring 
results show that the HGB area already has failed the test for 
attainment of the 1-hour ozone standard by the statutory deadline of 
November 15, 2007, further demonstrating that the SIP revision is 
``substantially inadequate to attain'' the ozone NAAQS by the deadline 
established in the Clean Air Act (CAA). Thus, as demonstrated in these 
comments, the EPA Administrator must find that:
     Texas has failed to satisfy the minimum criteria under 
section 110(k); \1\ and
---------------------------------------------------------------------------

    \1\ 42 U.S.C. 7509(a)(1) and (2).
---------------------------------------------------------------------------

     The plan is substantially inadequate.
Then, based on these findings, the Administrator must require that the 
TCEQ submit a revised plan demonstrating attainment within no more than 
18 months.\2\
---------------------------------------------------------------------------

    \2\ 42 U.S.C. 110(k)(5).
---------------------------------------------------------------------------

    Commenter (Wilson) also urged EPA to disapprove the attainment plan 
because they believe the plan does not include complete modeling, 
enforceable versions of all Reasonably Available Control Measures 
(RACM) and a control strategy sufficient to achieve attainment. The 
commenter (Wilson) went on to say because they believe the plan should 
be disapproved, EPA must commence promulgation of a Federal 
Implementation Plan (FIP).
    Response GC1: In the following responses, we address the specific 
concerns raised by the adverse comments in more detail. We believe the 
revised plan provided by the State of Texas is fully approvable under 
the Act, as we have documented in this notice and will provide for 
attainment as expeditiously as practicable which is by November 15, 
2007, and that the revised plan includes all reasonably available 
control measures. Therefore, we are finalizing our approval in this 
action. Furthermore, because we are fully approving the plan as meeting 
the requirements of 182(c)(2) and (d) of the Act, it is unnecessary to 
commence development of a FIP.
    Comment GC2: Commenter (Wilson) indicated TCEQ has not provided 
modeling that shows attainment by 2007. The commenter also indicated 
that six monitors in the area have already had four to six exceedances 
of the 1-hour ozone NAAQS and the area has already failed to attain by 
November 17, 2007 based on monitoring data for 2005. The commenter also 
contended that two one-year extensions are specifically restricted to 
the dates listed in Table 1 of Section 7511(a)(1), and that they do not 
apply to the Severe-17 area deadlines set in Section 7511(a)(2). 
Therefore, the commenter argues, these extensions cannot change the 
attainment date of Severe-17 areas such as Houston. The commenter also 
states that there is no demonstration of maintenance of the ozone 
standard below the 0.12 ppm one-hour standard beyond 2007.
    Response GC2: EPA has taken the position that for nonattainment 
areas subject to the requirements of subpart 2 of Part D of the Act, 
the area needs to demonstrate that in the attainment year, the area 
will have air quality such that the area could be eligible for the two 
one-year extensions provided under Section 181(a)(5) of the Act. See 66 
FR 57160, 57163-64 (November 14, 2001). EPA disagrees that Severe-17 
areas such as Houston are not entitled to the extensions provided in 
Section181(a)(5). It is our interpretation that the Severe category in 
Table 1 of Section 181(a)(1) encompasses both Severe-17 and Severe-15 
areas. Table 1 sets an attainment date of 15 years for severe areas 
with a 1988 ozone design value between .180 and .280 ppm. However, 
Section 181(a)(2) of the Act modifies Table 1 to provide an attainment 
date of 17 years for severe areas with a design value of between .190 
and .280 (``Severe-17 areas''). For those areas with a design value 
above .190, Congress plainly intended to allow two years longer to 
attain than the remainder of the severe areas included in Table 1. 
Table 1 in Section 181(a)(1) cannot be read in isolation, and must be 
read in conjunction with Section 181(a)(2). EPA thus interprets Section 
181(a)(5) as providing for attainment date extensions for all severe 
areas, including those whose attainment date in Table 1 is modified by 
Section 181(a)(2).
    EPA interprets Section 181(a)(2) as simply recognizing that Severe 
areas with a higher design value will need additional time to reach 
attainment and thus is simply extending the date in Table 1 for severe 
areas with high design values. There is nothing in Section 181 that 
directly excludes Severe-17 areas from the extensions provided for in 
Section181(a)(5). The commenter seems to suggest that even though 
Congress recognized that Severe-17 areas would need more time to reach 
attainment, they are not entitled to the extensions in Section 
181(a)(5). This interpretation would result in the Severe-17 areas 
getting no more time to attain than Severe-15 areas that potentially 
could qualify for the two one-year extensions. This would be an absurd 
result. Under the commenter's interpretation, all areas, including 
those designated ``Extreme'', would be entitled to attainment date 
extensions, with the sole exception of Severe-17 areas. This would mean 
that severe areas with design values under .190 would be allowed two 
one-year extensions, providing them with an attainment period of up to 
17 years, while the Severe-17 areas, which were intended to have two 
years longer to attain than the other severe areas, would be held to 
their initial 17-year attainment period, thereby eliminating the very 
distinction between the areas that Congress intended in section 
181(a)(2). The better reading is that Severe-17 areas should be 
eligible for the 2 one-year extensions (if they qualify for them) 
provided for in Section181(a)(5). EPA has consistently taken this 
position. Indeed, in the approval of the full attainment demonstration 
SIP for the Houston area in our November 14, 2001 (66 CFR 57160, 
57163), we indicated in a response to a comment (that the modeling 
should show attainment in 2005) that EPA's modeling guidance provided 
for modeling to demonstrate attainment in the last year (2007 in this 
case) such that it would be eligible or clean data extensions in 
accordance with Section 181(a)(5). It has been EPA's opinion at least 
since 2001 that Houston, a Severe-17 area, was entitled to the 
extensions in question. If the commenter's interpretation was applied 
(interpret 181(a)(5) as not applying to Severe-17 areas), three years 
of data (2005-7) would be needed to yield attainment in 2007 and to 
yield those monitor levels, EPA would have had to modify modeling 
guidance and required TCEQ to model 2005 future year for Houston and 
show no exceedances in the SIP revisions EPA approved in 2001. Once 
again, if the commenter's assertion were correct, Severe-17 areas would 
not be eligible for clean data extensions with the end result being an 
attainment date not much different than if the area had been designated 
a Severe-15 area.
    In addition, under EPA's interpretation, a Severe-17 area does not 
automatically get the extensions. They have to demonstrate significant 
progress towards attainment. Nonattainment areas subject to the 
requirements of subpart 2 of part D of the Act, need to demonstrate 
that in the attainment year, the area will have air quality such that 
the area could be eligible for the two one-year extensions provided 
under section 181(a)(5) of the Act. Under section 181(a)(5), an area 
that does not have three years of data demonstrating

[[Page 52679]]

attainment of the ozone NAAQS, but has complied with all of the 
statutory requirements and that has no more than one exceedance of the 
NAAQS in the attainment year, may receive a one-year extension of its 
attainment date. Assuming those conditions are met the following year, 
the area may receive an additional one-year extension. If the area has 
no more than one exceedance in this final extension year, then it will 
have three-years of data indicating that it has attained the ozone 
NAAQS. There is no reason to believe that Congress did not intend for 
Severe-17 areas to exercise this option.
    Moreover, EPA believes this approach is consistent with the 
statutory structure of subpart 2. Under subpart 2, many of the planning 
obligations for areas were not required to be implemented until the 
attainment year. Thus, Congress did not assume that all measures needed 
to attain the standard would be implemented three years prior to the 
area's attainment date. For example, areas classified as marginal--
which had an attainment date of three years following enactment of the 
1990 Clean Air Act Amendments--were required to adopt and implement 
RACT and I/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 of November 1996. Also, the ROP requirement for 
moderate and above areas, including the 15% plan for reductions by 
November 1996, applies through the attainment year. Thus, EPA believes 
that Congress did not intend that these additional mandatory reductions 
be in excess of what is needed to achieve three years of ``clean 
data.'' EPA does not require areas to demonstrate that the area will 
have three years of data (2005-2007) showing attainment in the 
attainment year. However, EPA does believe that the Act requires and 
that it is prudent for States to implement controls as expeditiously as 
practicable. As discussed elsewhere in this notice, additional 
reductions are being made in the Houston area after the 2005 ozone 
season, so it is still possible for the additional measures to result 
in the area reaching attainment by 2007. For these reasons, EPA does 
not agree with the commenter that the State's attainment demonstration 
is inadequate because of the exceedances that occurred at six monitors 
in 2005.
    A plan for maintenance of the NAAQS is not necessary for the 
attainment demonstration to be approved. A State is not required by the 
Act to provide a maintenance plan until the State petitions for an area 
to be redesignated to attainment. While it is not necessary for the 
State to provide for maintenance of the standard at this time, we do 
believe emissions in the HGB area will continue to decrease after 2007 
due to on- and off-road vehicle emission control programs that will 
provide additional reductions as the fleet continues to turnover after 
2007. TCEQ is also required to provide an 8-hour ozone attainment SIP 
for the HGB area that will likely require a new mixture of control 
measures to demonstrate future attainment of the 8-hour ozone standard. 
So there is reason to believe that air quality will continue to improve 
after the 1-hour attainment date.
    Comment GC3: Commenter (Wilson) suggested the plan should address 
other air pollution concerns such as reasonable further progress of the 
8-hour standard in addition to attainment of the one-hour standard. The 
commenter suggested the plan should provide as much progress as 
possible toward implementing the 8-hour standard as the requirements of 
the Act and EPA's implementing regulations allow.
    Response GC3: EPA established submission dates for 8-hour SIPS in 
its Phase 2 ozone implementation rule (70 FR 71611). SIPs addressing 
reasonable further progress and attainment of the 8-hour standard are 
due in 2007 and are not the subject of this rulemaking. EPA's review 
here is focused on whether the submitted plan meets the statutory 
requirements for attainment of the one-hour ozone standard, and doesn't 
interfere with attainment of the 8-hour NAAQS. In reviewing the 1-hour 
attainment SIP, EPA did consider consistent with section 110(l) whether 
this SIP revision would interfere with attainment of the 8-hour NAAQS. 
Section 110(l) requires that any plan revision not interfere with any 
applicable requirement concerning attainment and reasonable further 
progress, or any other applicable requirement of the Act 42 U.S. C. 
Sec.  7410(l). As provided in Section II.E, EPA concludes that these 
revisions will not interfere with attainment or progress toward 
attainment of the 8-hour ozone NAAQS.
    Comment GC4: The commenter (Wilson) indicated the EPA should reject 
the TCEQ claim that the SIP revision is likely to lead to attainment 
because it is based on a model analysis that is systematically biased 
towards under predicting unhealthy levels of ozone, both in the base 
case and future conditions. The commenter continues that TCEQ wrongly 
claims the only significant reason for this under prediction is the 
under reporting of short-term emissions by industry and that other 
factors exist for the under prediction bias. The commenter continues 
that because the TCEQ did not recognize the other factors that lead to 
the under prediction bias in their model, that the plan being 
considered by EPA lacks remedies for each of these factors. The 
commenter gives the example that TCEQ did not adopt measures to 
regulate VOCs other than HRVOCs and that TCEQ even repealed some 
general VOC control measures even though evidence suggests that Other 
VOCs (OVOCs) are a factor in the under prediction bias. The commenter 
summarizes that since such additional control measures are lacking, 
that EPA should disapprove the revisions.
    Response GC4: While EPA agrees that a general under prediction bias 
exists in the base case and future year modeling, we disagree that this 
is grounds for disapproving the revisions. EPA believes all model 
performance measures should be considered and there is no rigid 
criterion for model acceptance or rejection in assessing model 
simulation results for the performance evaluation. As recommended by 
EPA, the State's model performance evaluations for the selected episode 
included diagnostic and sensitivity analyses, and graphical and 
statistical performance measures. The model performance evaluation 
included statistical measures consisting of comparing the modeled 
versus monitored ozone that were mostly within the suggested limits in 
EPA's guidance. In addition, the graphical performance of the model for 
the episode indicated the model performed fairly well. For all days 
modeled, the combination of statistical and graphical performance was 
deemed sufficient for this revision package.
    Sufficient evidence exists that the episodic emissions that occur 
in the Houston area do impact the model's capacity to replicate ozone 
and are a plausible reason for much, if not all of the ozone under 
prediction in the model. While some evidence exists that an under 
estimation of emissions of Other VOCs (OVOCs = VOCs other than HRVOCs) 
may exist and that this may be responsible for some modeling under 
prediction, the research to answer the level of under/over estimation 
of OVOCs and how to allocate such adjustment in the model were not 
available when TCEQ was conducting the modeling for these revisions. 
Furthermore, modeling analyses indicate that HRVOC emission releases 
(in addition to the normal inventory) could result in higher ozone 
levels that would be as high as monitored values

[[Page 52680]]

and would seem to resolve much of the modeling under prediction bias 
issues. While an under estimation of OVOCs may also be part of the 
reason for the under prediction bias in the model, sufficient analyses/
evidence do not exist to specifically quantify any level of bias due to 
wrongful estimation of OVOCs. While TCEQ did not implement additional 
controls on OVOCs, it is EPA's technical opinion that based on the 
weight-of-evidence and the modeling, the State's revised control 
strategy provides for attainment by November 15, 2007.
    Comment GC5: The commenter (Wilson) indicated that the plan is not 
likely to lead to attainment because several of the control strategies 
are not likely to be as effective as TCEQ claims. The commenter 
continues that EPA should not approve some of the control strategy 
revisions (relaxation of NOX controls) in order to maintain 
a higher level of pollution control in the Houston area. In other parts 
of the commenter's package, the commenter indicated that the 
NOX rule revisions should not be approved.
    Response GC5: It is EPA's technical opinion that based on the 
modeling results and the additional weight-of-evidence, the State's 
revised control strategy provides for attainment of the 1-hour ozone 
NAAQS by November 15, 2007. We have addressed other specific comments 
from the commenter on issues related to why the control strategies may 
not be as effective as TCEQ claims elsewhere in the response to 
comments. The Clean Air Act gives the State the primary authority to 
prepare a SIP that provides for implementation, maintenance and 
enforcement of the NAAQS in each air quality control region and to 
determine the mix of control measures to achieve that goal, as long as 
they show attainment and the demonstration meets 110(l) requirements. 
EPA's responsibility is to review SIPs that the State provides and 
either approve or disapprove the revisions based on their meeting the 
requirements of the Act. EPA has reviewed the revised SIP and has 
determined that the revisions (including the NOX rule 
revisions) demonstrate attainment by November 15, 2007.
    Comment GC6: The commenter (Wilson) indicates that although the 
TCEQ has exercised sound scientific judgment in responding to many 
issues that have arisen, the SIP revision is also characterized by a 
pattern of avoiding unwanted findings by withholding data, applying 
standards selectively, reaching inconsistent conclusions, failing to 
conduct critical research, and unreasonably dismissing comments. The 
commenter continues that these actions undermine the technical 
credibility of the SIP revision and prejudice its findings. The 
commenter indicates that EPA should conduct its own analysis of 
available data and apply a health-protective bias whenever more than 
one argument is supported by the available data.
    Response GC6: EPA is satisfied with the technical credibility of 
TCEQ's finding. As discussed in the response to comment GC5, TCEQ is 
responsible for developing an acceptable implementation plan. TCEQ 
continues to have an open stakeholder process (both periodic technical 
and planning meetings and special meetings). EPA encourages TCEQ to 
continue having an open stakeholder process and to continue to share as 
much information (analyses, modeling, proposed regulations, etc.) as 
possible with the public/stakeholders and allow for comments/feedback 
to be considered in the SIP development process. EPA conducted a 
detailed review of the proposed revisions prior to proposing approval 
and provided detailed review of the modeling and weight-of-evidence 
analysis in the proposal and TSD. EPA has also considered the comments 
received during the proposal's comment period and has determined that 
the SIP revisions are acceptable and EPA is approving these revisions 
to TCEQ's SIP.
    Comment GC7: A commenter (Wilson) indicated that TCEQ has failed to 
include contingency measures in the HGB ozone SIP. The commenter 
continues that TCEQ has claimed they satisfy this requirement with the 
measures to be implemented in 2008, since the measures are above and 
beyond those modeled in the proposed revision and include additional 
TERP reductions. The commenter contends that these measures are not 
sufficient because TCEQ has not substantiated how they are sufficient 
to advance attainment.
    Response GC7: TCEQ included contingency measures in the SIP 
revision for 23.57 tpd reduction in NOX and 10.84 tpd of VOC 
in 2008. EPA has reviewed the proposed contingency measures and 
concluded that they meet the level of reductions necessary. 
Historically, EPA has recommended that contingency measures achieve an 
additional 3 percent reduction in emissions. (57 FR 13511) The purpose 
of contingency measures is to ensure continued progress while the area 
moves forward to adopt additional controls needed for attainment and we 
believe an additional 3 percent achieves that purpose. (57 FR 13511) We 
are uncertain what the commenter is referring to when it suggests that 
contingency measures must be ``sufficient to advance attainment'' but 
note that term is not used in the statute nor has EPA ever suggested 
that as the test for determining the adequacy of contingency measures. 
While we find that TCEQ has adequately satisfied the contingency 
measure requirement, ultimately we note that contingency measures for 
failing to attain the 1-hour standard will not apply. As noted in the 
Phase 1 Rule to Implement the 8-hour ozone NAAQS, EPA did not retain 1-
hour contingency measures as an applicable requirement that would 
continue to apply after the 1-hour standard is revoked (i.e., June 15, 
2005 for the HGB nonattainment area). EPA also further noted that once 
the 1-hour standard was revoked, EPA would no longer make 
determinations whether an area had met or failed to meet that revoked 
standard and thus contingency measures would not be triggered even if 
adopted. (70 FR 30592, May 26, 2005 at page 30599.)
    Comment GC8: A commenter (Wilson) indicated EPA should not 
disregard the 1-hour ozone standard in light of the new 8-hour 
standard. The commenter indicated that an analysis of the historical 
record demonstrates that if Houston meets the 1-hour standard, the 
public will be protected from air pollution exposures that would be 
allowed under the 8-hour standard. The commenter iterated that it is 
likely to be true that for much of the rest of the country the 8-hour 
standard can reasonably supplant the 1-hour standard and in Houston the 
8-hour standard is clearly superior to the 1-hour standard in terms of 
public health benefits. The commenter continued that the 1-hour 
standard has a special role in Houston for the protection of public 
health. The commenter indicated that TCEQ data suggest that failing to 
attain the 1-hour standard will leave Houston residents with exposure 
to ozone at levels that the EPA once sought to prevent. According to 
the commenter's analysis of days when either the 1-hour and/or the 8-
hour standard were exceeded during 2000-2003, the one-hour standard was 
the only standard breached on about 7 percent of the days 
(approximately 6 days/year). The commenter also indicated the AQI 
reaches a higher value based on the one-hour standard on a similar 
number of days. The commenter continued by indicating a singular focus 
on the 8-hour standard (and not addressing the 1-hour standard) could 
leave Houston residents

[[Page 52681]]

breathing unhealthy air about 6 days per year even after the 8-hour 
standard is attained.
    The commenter continued that controlling short-term exposures to 
ozone is important as many scientific studies based on the 1-hour ozone 
standard report increased use of asthma medication, increased emergency 
room visits and hospitalization for respiratory problems, even at 
levels below 0.12 ppm for just one or two hours with affects continuing 
for days or months afterwards.
    The commenter continues that EPA has always viewed the 1-hour and 
8-hour standards as adequate alternative methods for protecting public 
health, and gave consideration to establishing a standard that combined 
both 1-hour and 8-hour measurements. The commenter indicates the basis 
for revoking the 1-hour ozone standard dates back to a 1996 report 
(EPA, Review of National Ambient Air Quality Standards for Ozone: 
Assessment of Scientific and Technical Information, June 1996) issued 
by EPA staff that concluded from a public health perspective, a 1-hour, 
an 8-hour or a combined standard could be set at a level that would 
adequately protect public health. The commenter continues that the 
report did not explicitly reject a combination of the 1-hour and 8-hour 
standards, but did firmly endorse an 8-hour standard. The commenter 
indicates the record isn't entirely clear as to why a combined standard 
was not the initial recommendation of staff in the report, but it seems 
to turn on the word ``efficient.''
    The commenter continues that EPA concluded later that year in a 
report (US EPA, ``Responses to Significant Comments on the 1996 
Proposed Rule on the National Ambient Air Quality Standards for 
Ozone''; December 13, 1996), based on modeling of ozone exposures, 
``that an 8-hour 0.08 ppm averaging time does effectively limit both 1- 
and 8-hour exposures of concern. The commenter continues that 
subsequent EPA decisions recognize that the 8-hour standard might not 
effectively protect the public from 1-hour health effects, and sought 
to retain the 1-hour ozone standard until attainment, and then revoke 
it on an area-by-area basis. The commenter indicates that this would 
have been consistent with full protection of public health and 
administrative efficiency.
    The commenter continued that the EPA decided for legal reasons to 
go ahead and revoke the 1-hour standard nationwide while California's 
current review of its state ozone standards is likely to lead to a 1-
hour standard of 0.09 ppm, compared to the current 0.12 ppm standard 
used by EPA.
    The commenter concluded if the plan EPA proposes to approve fails, 
Houston could still have serious public health effects due to ozone 
smog even if the TCEQ leads Houston to attainment of the 8-hour 
standard.
    Response GC8: As we noted in the final Phase 1 Rule, we determined 
in the 1997 NAAQS rulemaking (69 FR 23951) that we did not need to 
retain the 1-hour standard to protect public health. Thus, in the 1997 
NAAQS rulemaking, EPA concluded that the 8-hour standard would replace 
the 1-hour standard. The issue of whether the 1-hour standard is needed 
to protect public health has not been reopened here and, indeed, should 
be considered only in the context of a national rulemaking reviewing 
the NAAQS.
2. Comments on the Photochemical Modeling
    Comment M1: Commenter (Wilson) comments that EPA modeling guidance 
(1996) indicates that weight of evidence analysis included to 
supplement the deterministic and statistical modeling attainment 
demonstrations needs to be compelling to overcome the results from the 
photochemical grid model. The commenter continues to cite EPA guidance 
indicating that ``If the results of corroborative analyses are also 
consistent with the conclusion that a strategy will be insufficient to 
meet the NAAQS by the statutory date, attainment would not be 
demonstrated.'' The commenter continues that the SIP revision does not 
meet EPA guidance for demonstrating attainment because: (1) The plan 
fails the deterministic test as indicated by the use of weight of 
evidence (WOE) to justify dropping the August 31 from the modeling 
episode. (2) The databases, in particular emission inventories, used in 
the modeling have a number of problems including the failure of TCEQ to 
reconcile their own findings about the under-reporting of other VOCs. 
The analysis and WOE exhibit a selective approach to the examination of 
relevant data that distorts the WOE guidance and results in relaxation 
of WOE requirements. (3) The episode days used to evaluate the control 
strategy do not include days with observations near, but slightly 
above, the design value and meteorological ozone forming potential 
likely to be exceeded about once per year as advised by EPA guidance. 
(4) The TCEQ's corroborative analyses are also consistent with the 
conclusion that the strategy is insufficient to demonstrate attainment.
    The commenter summarizes that a thorough and skeptical 
consideration of TCEQ's technical analysis must result in the EPA 
finding that the SIP revision does not demonstrate attainment of the 1-
hour ozone standard. The commenter continues to indicate: (1) The 
modeling has a systematic ozone underprediction bias at levels above 
120 ppb. (2) TCEQ's attainment demonstration has failed to address this 
shortcoming in the WOE and the plan does not include control measures 
to adequately control emissions on ``level purple'' ozone days that are 
representative of the region's design value. (3) The control measures 
included in the plan are inadequate to meet even the expectations of 
the TCEQ. The commenter then indicates that EPA should not approve the 
SIP revision, and instead find that TCEQ has failed to submit a plan 
providing for implementation, maintenance, and enforcement of the ozone 
NAAQS for the HGB area.
    Response M1: As also discussed in other responses, EPA did not 
dismiss any measures or analyses used by TCEQ for their model 
performance evaluation, nor did EPA disagree with TCEQ's conclusion, 
based on the modeling and in conjunction with the WOE analyses, that 
this SIP revision should result in the HGB area attaining the 1-hour 
ozone standard by November 15, 2007. EPA's analysis included evaluating 
model performance and model reaction on the August 31st episode day in 
conjunction with the additional WOE materials that TCEQ provided for 
this day, as well as the rest of the attainment demonstration period. 
The commenter raised a number of specific issues that are addressed in 
this comment or more specifically addressed in separate comments, but 
the combination of the comments do not sway EPA's technical opinion 
that the modeling and the combined Design Value (DV) approach predicts 
the area will reach attainment by the end of 2007.
    EPA also reviewed modeling sensitivities conducted by TCEQ 
including rough adjustments to OVOCs, but concurred with TCEQ that the 
body of supporting material to conduct a refined adjustment for OVOCs 
did not currently exist. EPA encourages TCEQ to continue to research 
this issue to address this uncertainty in the future and further 
address this issue in the 8-hour ozone SIP. EPA believes that most of 
the error can be best explained by uncertainties in the amount of HRVOC 
that were actually emitted and the spatial allocation of the HRVOC 
adjustment and meteorological model issues. TCEQ chose an average value 
for the adjustment factor for the HRVOCs

[[Page 52682]]

and adjusted the same level over the entire Houston/Galveston/Brazoria 
area, even though field study data indicates that a range existed that 
was many times higher than the value utilized in TCEQ's modeling in 
some cases. The TCEQ and EPA agree that there is simply not enough data 
available at this time to precisely locate all of the sources of non-
inventoried HRVOC emissions. The TCEQ is pursuing several areas of 
research that will use additional monitoring data and other data to 
improve the spatial and temporal allocation of HRVOC emissions, and is 
simultaneously pursuing bottom-up methods to improve emissions 
inventories. These efforts will allow a much more refined treatment of 
``extra'' hydrocarbon emissions in future modeling. TCEQ should 
continue to strive to yield better estimates in HRVOC and OVOC 
emissions from industrial facilities in HGB and this should continue to 
be one of the focus areas for the second TEXAQS study in 2005-2006. EPA 
agrees that TCEQ made an appropriate estimate of how the emission 
inventory for HRVOCs should be adjusted without sufficient data to 
conduct a higher level of adjustment with spatial variability. TCEQ 
tried to gather more data through a special inventory request of over 
80 industrial facilities in the HGB area, but was not able to collect 
all of the data required to conduct a more accurate HRVOC adjustment. 
We believe our understanding of the process is sufficient, however, to 
interpret the photochemical model results and determine that this SIP 
revision is approvable.
    EPA previously reviewed and agreed that the episode (8/21-9/6/2000) 
was appropriate for this SIP revision. The episode did include several 
days (8/25, 8/30, 8/31, and 9/5) that included surface level monitored 
data greater than 175 ppb and several days near the area's design value 
at the time of the episode and the episode did have the benefit of 
intensive data collected during this period. Given the historical 
difficulty with obtaining acceptable photochemical model performance in 
the HGB area, EPA recognizes the importance of selecting days from a 
field study period in preference to other non-field study days. On 
these high ozone level days (>175 ppb) the commenter is correct that 
the model had an under prediction bias of the domain peak and at many 
monitors (values above 120 ppb). But this is thought to be largely the 
result of many issues (HRVOC adjustments and the two-pronged design 
value approach, meteorological issues, general modeling issues, etc.) 
discussed above and in other responses, but was determined acceptable 
in this SIP revision due to the inclusion of HRVOC rules that will 
remove much of the variability in HRVOC emissions and result in 
significantly lower HRVOC emission levels. It should also be noted that 
on these four high ozone level days ( >175 ppb monitored), EPA's three 
primary ozone statistic metrics were within EPA guidance parameter for 
all four days (including the August 31st) with the exception of the 
Peak Prediction accuracy metric on the August 30th (see TSD Tables G.1-
1 to G.1-3 and Texas SIP materials for details).
    The need for further studies does not mean, however, that the 
modeling relied upon today was unable to estimate the amount and type 
of emission reductions needed for attainment. EPA believes because the 
diagnostic/sensitivity tests do not reveal serious flaws in model 
formulations and the model generally predicts the right magnitude of 
the peak which is confirmed by the statistical measures and graphical 
analysis, that the model does provide an acceptable tool for estimating 
the amount of emissions reductions needed. It is EPA's technical 
opinion that based on the modeling and the weight-of-evidence, the 
State's control strategy should provide for attainment by November 15, 
2007.
    TCEQ and others have provided significant amounts of modeling 
sensitivities, monitoring analyses, etc. as part of the corroborative 
analyses that were evaluated in the decision to propose approval of the 
SIP revisions. While some components of the corroborative analysis seem 
to indicate that the SIP revision plan may not succeed, a majority of 
the components indicate that the plan will succeed. EPA has weighed 
many different analyses from TCEQ and others (including the HARC H12 
and H13 project results) and concluded that the SIP revision plan will 
attain by the attainment date. TCEQ has agreed to conduct further 
refinements to the emission inventory and meteorology of this episode 
in development of the 8-hour ozone SIP. TCEQ and others are also 
conducting another field study in 2005 and 2006. TCEQ has indicated 
that they will attempt to weigh any new information derived from the 
further studies and evaluations, and incorporate the information into 
the HGB 8-hour Ozone SIP to be submitted to EPA by June 15, 2007.
    Comment M2: The commenter (Wilson) commented that they are 
concerned with final episode selection and with the modeling results 
for that episode. The commenter continued by conjecturing that the 
episode included in the modeling does not contain enough days with 
observations near, but slightly above, the design value and with 
meteorological ozone forming potential that is likely to be exceeded 
about once per year as is advised by EPA guidance. The commenter also 
indicated that the SIP revision adequately addresses Air Quality Index 
(AQI) level ``Orange'' ozone days and not ``Purple'' level ozone days 
when the HGB area has a AQI level ``Purple'' ozone problem.
    The commenter continued, the 2003 design value for the 1-hour ozone 
standard was 0.175 ppm and for the period 2000-2003, air pollution 
monitors recorded an average of 9 days per year with a 1-hour ozone 
measurement over 0.165 ppm, and about 1 additional day per year 
measured over 0.205 ppm. The commenter summarized this data as on 
average during the HGB area has 10 AQI level ``Red'' and ``Purple'' 
days per year during the 2000-2003 period.
    The commenter also indicated that according to ground-level 
monitoring data used by the TCEQ in its plan, the episode used for 
control strategy evaluation in the proposed SIP does not provide ozone 
formation conditions that are close to the region's design value, and 
that it does not resemble the character of the region's serious ozone 
problems. The commenter provided a graph to illustrate that the plan's 
best effect is shown by reducing several AQI level ``Orange'' days near 
the 1-hour ozone standard of 0.12 ppm, but no AQI level ``Red'' or 
level ``Purple'' days. The commenter also indicated that aircraft data 
and Williams tower data did include higher AQI levels of ``Red'' and 
``Purple'' in some of the areas that do not have ground monitoring 
stations with the caveat that some of this data was of shorter duration 
period.
    The commenter continued that: ``The TCEQ estimates the effect of 
the undocumented emission releases by calculating an alternative design 
value of 144 ppb for comparison to the actual design value of 182 ppb 
for the 1999-2001 period.'' The commenter further indicated that 
another perspective is suggested by comparing the model variability in 
peak ozone to actual variability and concludes that routine variability 
on days conducive to ozone formation is limited to only about 20 ppb, 
compared to about 75 ppb of actual variability in ozone formation 
observed at ground monitors. The commenter concludes that regardless of 
whether one concludes that 38 ppb (182 ppb-144

[[Page 52683]]

ppb) or 55 ppb (75 ppb-20 ppb) of peak ozone formation are not properly 
modeled, the challenge to the weight-of-evidence analysis is clearly 
substantial.
    Response M2: The original episode selection of August 19-September 
6, 2000 was selected by TCEQ with EPA review and comment on the 
selection of the episode. This TexAQS 2000 episode was selected because 
it includes a 19-day window with both weekday and weekend events, a 
suite of wind directions, and daily ozone peaks measured in several 
different areas of the city reflecting the net surface transport during 
each day. When combined with the additional meteorological and 
precursor data collected during the TexAQS 2000 study period, this 
extended ozone episode includes a better than normal monitored data set 
and a fairly representative mix of HGB area episode types. Given the 
historical difficulty with obtaining acceptable photochemical model 
performance in the HGB area, EPA recognized (as allowed by EPA modeling 
guidance) the importance of selecting days from a field study period in 
preference to other non-field study days during the episode selection 
process with TCEQ. EPA's modeling guidance for the 1-hour ozone NAAQS 
(``GUIDELINE FOR REGULATORY APPLICATION OF THE URBAN AIRSHED MODEL''; 
U.S. EPA; July 1991; pg. 11) includes the following text:

In choosing from among the top-ranked episode days, consider the 
availability and quality of air quality and meteorological data 
bases, the availability of supporting regional modeling analyses, 
the number of monitors recording daily maximum ozone concentrations 
greater than 0.12 ppm (i.e., pervasiveness), number of hours for 
which ozone in excess of 0.12 ppm is observed, frequency with which 
the observed meteorological conditions correspond with observed 
exceedances, and model performance (discussed in Chapter 5). For 
example, the top-ranked episode day within a meteorological regime 
may have only routine air quality and meteorological data bases 
available for use in the modeling. The third-highest day, however, 
may have occurred during an intensive field study, so that a more 
comprehensive data base is available. Thus, the third-highest day 
may be more desirable for modeling than the top-ranked day.

    As EPA's guidance indicates, days with not quite as high ozone 
exceedances may be chosen over the highest ozone day if they occurred 
during an intensive field study. Given the difficulties and 
uncertainties with modeling the Houston area, EPA approved the 
selection of the field study period as the episode period to be modeled 
in accordance with EPA's guidance. It should be noted that the 1-hour 
ozone design value is calculated for each monitor in the domain and is 
the 4th highest 1-hour ozone value in a three year period (see EPA's 
memo titled ``Ozone and Carbon Monoxide Design Value Calculations''; 
June 18, 1990). Therefore the design value for the area is usually 
lower than the 1st high value as the commenter indicated, and for the 
limited time period (2000-2003) that the commenter analyzed, the HGB 
area design value was not a ``Purple'' level AQI day, but a mid ``Red'' 
level AQI day.
    Based on model performance issues, the original episode was reduced 
to August 25, 26, August 29-September 4, and September 6, 2000. As TCEQ 
identified in their response to comments, it is important to note that 
six 1-hour ozone exceedance days were included in the ten day modeling 
period (August 25-September 1), and the average of those peaks was 
168.3 ppb. This modeled period of the episode did include several days 
(8/25, 8/30, 8/31, and 9/5) that included surface level monitored data 
greater than 175 ppb and several days near the area's design value at 
the time of the episode and the episode did have the benefit of 
intensive data collection that occurred during this period. The 
September 5th day was dropped due to model performance issues. On these 
high ozone level days (>175 ppb) the commenter is correct that the 
model had an under prediction bias of the domain peak and at many 
monitors (values above 120 ppb), but this is thought to be largely the 
result of many issues (HRVOC adjustments and the two-pronged 
alternative design value approach, meteorological issues, general 
modeling issues, etc.). As discussed in other responses, the modeling 
was determined to have an acceptable model performance. Even with an 
under-prediction bias, six of the Base 5b episode days had values 
greater than 150 ppb in the basecase modeling which is higher than the 
Alternate Design Value (ADV) of 144 ppb that TCEQ used (and 7 days 
above 144 ppb, see TSD Table H-3). In evaluating the TSD tables, the 
modeling episode included three monitored ``Red'' AQI level days, with 
two of the days near ``Purple'' levels (8/25 and 8/30). With the 
combined strategy of reducing emission events and routine emissions, 
EPA would not expect the basecase modeling (utilizing a routine 
emission approach) to include ozone levels above the design value. 
Furthermore, TCEQ did include many days that were above the 144 ppb ADV 
that they used and thus we weighted this fact as a conservative WOE 
element. We also concurred with the selection of this episode and that 
it included enough high ozone value days with values near the design 
value to be the basis for attainment demonstration modeling.
    Comment M3: Commenter (Wilson) comments that the episode used for 
control strategy evaluation in the proposed SIP does not provide ozone 
formation conditions that are close to the region's design value, and 
do not resemble the character of the region's ozone problems with the 
under prediction of the peaks and the modeled peak 1-hour ozone levels 
only varying approximately 20 ppb for each day between the base and 
future attainment demonstration modeling. The commenter then continues 
that TCEQ's response is the under prediction of the peaks is likely due 
to unreported or under-reported releases of HRVOCs and that EPA 
concurred in this assessment of the model performance with citations 
from EPA's Technical Support Document. The commenter continues that 
TCEQ estimated the effects of undocumented releases by estimating an 
Alternative Design Value (ADV) of 144 ppb compared to the actual design 
value of 182 ppb for the 1999-2001 period. The commenter then discusses 
an alternate approach to an ADV based on the routine variability of 
only 20 ppb in the modeling. The commenter summarizes that the two 
approaches yield either a 38 ppb or a 55 ppb level of peak ozone that 
is not modeled properly and that the challenge to the WOE is 
substantial.
    The commenter continued that EPA properly expressed some skepticism 
that under-reported, short-term emission releases should explain the 
entire under-prediction of peak ozone levels, with a cite from EPA's 
TSD. The commenter concludes that EPA should further conclude that 
several other factors are equally likely causes of the under-prediction 
of ozone peaks by model analysis: Failure to use superfine grid, under-
reporting of OVOCs (both routine and short-term), and underestimation 
of emissions from ports and heavy duty diesel trucks. The commenter 
also indicated that the drop in ozone design values over the last 
several years is due to the implementation of NOX RACT and 
favorable meteorology.
    Another commenter (BCCAAG) commented in favor of the ADV approach 
and the ADV value of 144 ppb as utilized by TCEQ. The commenter 
continued that the strength of TCEQ's WOE demonstration is bourne out 
by the recent decreases in ozone values

[[Page 52684]]

(Design values,  of days of exceedances,  of 1st and 
2nd High values) in HGB. The commenter continues that this occurred 
despite an increase in ozone monitors and economic growth in the 
region.
    Response M3: As previously discussed in the response on M2, EPA 
concurred that this was a reasonable episode for this SIP revision and 
that it included enough days with high ozone levels. The commenter is 
correct in indicating that for most days the modeled change between 
base and 2007 future controlled level is less than the difference 
between the daily monitored peak and 124 ppb, but the daily difference 
value ranges from 14.7-37.6 ppb with an average of approximately 27.5 
ppb (not 20 ppb). EPA conducted further analysis of TSD tables G.1-2 
and G.1-3 in preparing response to this comment. The original episode 
had 19 days with 13 exceedance days with an average of 1-HR daily 
maximum ozone of 160 ppb (36 ppb above attainment) and a range of 
exceedances from 125 to 200 ppb for the exceedance days. This SIP 
included a shorter period due to model performance issues that included 
nine exceedances with an average of 159 ppb and a range from 125 to 200 
ppb (based on surface measurements).
    The commenter lists a number of issues--failure to use superfine 
grid, under-reporting of OVOCs (both routine and short-term); and 
underestimation of emissions from ports and heavy duty diesel trucks--
that may be part of the reason for the under-prediction bias and did 
consider these issues in the TSD that was the basis for our proposal. 
We discuss these specific issues in other responses in this notice, but 
we believe that these issues, in conjunction with other issues 
(including under/unreported emissions) that we have discussed in other 
responses, covers most of the issues that may be causing the under-
prediction bias. Specifically, we have concluded that one of the 
greatest components of uncertainty in the modeling system is the 
variability and under/unreported emissions issue. The measures included 
in this revision will help to resolve the level of uncertainty in this 
area. As noted elsewhere in this document, we have reviewed the model 
performance, including bias issues, and have determined the modeling 
demonstration to be acceptable.
    Comment M4: Commenter (Wilson) comments that the TCEQ should have 
developed a robust method of relating one- and five-second interval 
ozone data collected by moving aircraft to one hour ozone estimates 
measured by stationary ground monitors so that airborne monitoring data 
may be used to estimate 1-hour ozone values in areas of the HGB area 
that are far from ground monitoring stations.
    Response M4: EPA agrees that such a methodology would be a useful 
analytical tool and TCEQ did initiate a study with the Pacific 
Northwest National Laboratory to discuss and illustrate problems 
associated with comparing observations from an airborne monitoring 
platform to results from photochemical model grids (which might be used 
with ground based monitoring data). Developing such a methodology is a 
complex issue since the methodology must take into account temporal 
differences in the data (i.e. one second interval for airborne data 
versus a five minute interval for ground data), spatial differences in 
the monitors (differences in location and elevation), and environmental 
differences for the monitoring equipment (temperature, humidity, solar 
radiation, etc.) and potentially varying levels of sensitivity/accuracy 
between the different instruments utilized.
    Monitors measure concentration at a point in space and in reality, 
these concentrations can vary significantly over a grid cell or an 
area. This is true especially for ozone if it is contained in a narrow 
plume. Inevitably, a grid type model will smooth some natural phenomena 
because natural conditions are averaged over the volume of each grid 
cell. For instance, model output represents a volume average, typically 
4 km x 4 km by 50 meter column. As a result, reasonable comparisons 
between model predictions and monitor observations are not expected to 
match exactly. With reasonable performance, time series typically show 
similar diurnal cycles but not exact concentration levels. As a result, 
it is very difficult to obtain a precise equality between modeled 
concentration and monitored concentration. This is to be expected and 
does not necessarily call into question the model's utility as a tool 
to predict the level of emission reductions needed to reach attainment. 
As stated in previous comments, EPA believes the model provides 
reasonable predictions of ozone levels as confirmed by comparisons with 
monitoring data and therefore can provide an acceptable estimate of the 
amount of emissions reductions needed for attainment.
    Comment M5: Commenter (Wilson) commented that aircraft data were 
excluded from the model performance evaluation. The commenter also 
commented that the TCEQ should have revised the base case model 
performance evaluation section to include qualitative evaluation of 
model performance based on aircraft data, including reconsideration of 
alternative model approaches that may appear more favorable in light of 
these data.
    The commenter then indicated that TCEQ had performed a comparison 
of model results to aircraft data, but inadvertently omitted this 
comparison from Appendix B of TCEQ's proposal. Due to this omission 
during TCEQ's proposal, the commenter indicates that they have reviewed 
the TCEQ's analysis and are providing comments on TCEQ's Appendix B 
analysis.
    The commenter then indicates that they calculated a value of 89 
percent as the difference between 1-hour and 5-minute peaks at the Deer 
Park Monitor on October 7, 1999 (30 ppb difference). The commenter's 
analysis then utilized this 89 percent factor to scale aircraft data to 
1-hour ozone values for comparisons on August 25-30, and September 1, 
3, 4, and 6th.
    The commenter then continued to give specific analyses of aircraft 
observations to model predictions for each of these days. The commenter 
utilized the 89 percent factor to indicate that August 25, 30, and 
September 1st were days that aircraft and surface monitoring data 
showed levels well above those achieved in the model. The commenter 
also utilized the 89 percent factor to indicate that aircraft data 
showed ozone levels above both the surface monitoring data (maximum of 
146 ppb) and model performance data (maximum of 151 ppb) for August 
29th.
    The commenter also utilized the 89 percent factor to conjecture 
that TCEQ incorrectly assessed that the model over-predicted ozone 
formation on August 27 and 28 and that the aircraft data suggests that 
the model does accurately predict ozone levels. The commenter then 
continued on that the model under-predicts high ozone levels above 120 
ppb.
    Response M5: TCEQ did include the Appendix B materials in the SIP 
submitted to EPA and EPA reviewed the Appendix B as part of the review 
conducted for the proposal notice. Aircraft observations can be useful 
in assessing model performance, but must be done with care, due to the 
many issues outlined in Response M4. Due to these technical concerns it 
is difficult to utilize aircraft data other than in a qualitative/
directional sense for comparing aircraft observational data to 4 km 
hourly grid modeling predictions.
    The commenter did not provide the data utilized to calculate the 89 
percent conversion value to convert aircraft data into an estimate of 
1-hour ozone concentrations. The commenter did indicate that this value 
was calculated

[[Page 52685]]

using only one day of data at one monitor in the HGB area for a day 
that is not during the modeled episode period and for a day (October 7, 
1999) that is not even during the main period of ozone season in the 
HGB area. No analysis was provided to document that this was a typical 
day, or a typical data set to estimate the 89 percent conversion factor 
nor was an effort made to make sure the data sample set for this 
calculation was appropriate. This 89 percent value seems high from 
discussion within EPA Region 6 including monitoring staff that 
typically review the 5-minute data and 1-hour data. Furthermore the 
commenter has made several assumptions in their analysis that they 
utilize to support their comment, that actually weakens their analysis. 
The commenter assumed that 5-minute data is the approximate length of 
time that is representative of the aircraft data in comparison to a 
model grid square, although no basis was given. The method does not 
resolve that an aircraft would be a line sample through a model grid 
square at an altitude that does not have hourly monitored data and 
would not be the same sampling as a single monitor (if you could have 
one at the altitude of the aircraft). The commenter did not adjust for 
a model that calculates a large volume average versus an aircraft that 
is a shorter duration line sample through multiple grid cells that may 
be several hundreds of meters thick for the layer of the model that the 
aircraft would be flying. Due to all of these issues including the very 
limited data set that the 89 percent was generated, we have to discount 
any assessments that utilized the 89 percent factor.
    While the commenter is correct that comparing ground observations 
to modeled values, the model does under-predict ozone concentrations 
above 120 ppb for some of the days. As discussed in response to 
comments elsewhere in this notice, this is expected and was fully 
reviewed and determined to be approvable for this SIP revision.
    Comment M6: The commenter (Wilson) indicates that the exclusion of 
one kilometer resolution modeling is arbitrary and unreasonably biases 
the results in favor of an attainment finding. The commenter continues 
by disagreeing with EPA's proposed action and requests that EPA 
evaluate the one kilometer resolution modeling as useful evidence that 
the attainment demonstration is insufficient. The commenter argues that 
the TCEQ has failed to present a compelling technical argument for 
excluding one kilometer resolution from the base case and control 
strategy evaluations. The commenter included language from TCEQ emails, 
that were included in the materials that were reviewed by EPA while 
developing the proposal and TSD for this action. The commenter asserts 
that TCEQ made the decision to exclude one kilometer modeling prior to 
attempting to develop an technical justification for the decision. The 
commenter indicates that peak ozone levels are often higher for one 
kilometer modeling, but other model performance statistics are 
relatively unchanged when the one kilometer modeling output is compared 
to the four kilometer average of the one kilometer resolution output. 
The commenter concluded that the one kilometer resolution modeling made 
attainment demonstration more difficult and therefore EPA should 
consider that statistics do not degrade and the peak ozone levels are 
better represented with the one kilometer modeling, that EPA should not 
approve the demonstration because the one kilometer grid modeling 
predicts nonattainment on several days for control strategy 
evaluations.
    Response M6: While the commenter asserts that EPA should reconsider 
our analysis of the appropriateness of the one kilometer resolution 
modeling, no new information was provided that was not previously 
considered in our review during the development of the proposal and TSD 
for this action. We would like to point out that a full model 
performance analysis (including statistics, graphical plots, and 
emissions sensitivities) were not provided for the one kilometer 
resolution modeling by the commenter or in the TCEQ SIP revisions, so 
that a full model performance analysis could be compared with four 
kilometer model performance analysis. Without such an analysis, it is 
difficult to ascertain whether one kilometer resolution modeling is 
actually better performing (as the commenter claims) than four 
kilometer resolution modeling or just yielding higher peak ozone 
values.
    As was discussed in the TSD, concerns have been raised by the 
academic community that while the CAMx model will give model 
predictions at 1 km, it has never been fully evaluated for correct 
performance at this scale in the HGB area and that the uncertainties 
associated with these concerns may undermine the credibility of the 
model runs upon which the control strategy was based. Some of the 
parameters within CAMx which raised concerns include 
horizontal and vertical diffusivities and assumptions within 
CAMx that apply to the hydrostatic equilibrium of horizontal 
and vertical transport may begin to break down at a finer grid 
resolution.
    TCEQ indicated in their response to comments that continued 
evaluation and peer review of these uncertainties is necessary before 
the model can routinely be applied at a finer resolution to replicate 
all conditions of ozone formation.
    For further discussion of technical concerns with utilizing the one 
kilometer resolution modeling and EPA's thoughts and review of the 
issue please see the proposal and TSD for this action.
    Comment M7: The commenter (Wilson) comments that while short-term 
HRVOC emission events are surely a frequent and significant cause of 
ozone formation in the Houston area, the TCEQ overstates their role. 
The commenter continues that TCEQ failed to consider specific problems 
with its data, and then TCEQ made broad statements that are not 
supported by their analysis. The commenter then indicates that a more 
rigorous analysis would support a smaller, yet still significant, role 
in the SIP.
    The commenter then commented on a TCEQ analysis of August 30 
indicating that it demonstrated an example of how the TCEQ failed to 
identify weaknesses in its control strategy by inconsistent analysis. 
The commenter stated that TCEQ suggests that the gap between the 
modeled peak of 0.137 ppm and the observed peak of 0.200 ppm on August 
30 could be explained by the evidence that one or more emission events 
not accurately represented in the modeling inventory occurred on this 
day. The commenter continued, that on the other hand, the TCEQ 
conducted a sensitivity analysis with a hypothetical upset included on 
August 30, but the model peak only increased to 0.145 ppm. The 
commenter further indicated that TCEQ minimized the importance of 
emission events on ozone formation by finding that ``emission 
variability of roughly 1000 lb/hr should be expected in the regions 
upwind of peak, region wide ozone concentration at least once per year 
and that releases over approximately a two to three hour period can 
lead to increases of 2-3 ppb in peak ozone concentration per 1000 lb of 
additional HRVOC emissions. The commenter concluded that although two 
different TCEQ approaches to modeling short-term emission events 
suggest that the hypothesized releases of August 30 could be expected 
to cause 4 ppb to 9 ppb of additional ozone, the TCEQ appears to 
consider this an acceptable explanation for the 43 ppb gap between the 
model and measured peak ozone levels.
    The commenter also indicated that TCEQ failed to properly analyze 
the

[[Page 52686]]

impact of short-term events on ozone formation because of TCEQ's 
failure to question whether the inventory of emissions caused by short-
term releases is accurate in light of the many problems with emissions 
inventories. The commenter continues that self-reported upset data are 
estimated using methods that have been called into question for many 
sources, including flares, cooling towers, storage tanks and fugitive 
leaks. The commenter gives the example that flare emissions are 
routinely calculated assuming flare performance is at optimal levels, 
an assumption that has been questioned by the TCEQ in its technical 
analysis (e.g., the ``big smoky'' August 30th flaring event) and by the 
EPA.
    The commenter then criticizes TCEQ for TCEQ's remarks on an absence 
of evidence available at this time to warrant a correction factor for 
under-reported upset emissions and as a result, TCEQ decided to not 
conduct a speculative sensitivity analysis. The commenter continued 
that on the other hand TCEQ indicated that unreported/underreporting of 
short term releases of HRVOCs is responsible for the underprediction 
bias in the modeling on some days.
    The commenter concludes that TCEQ's failure to assess the accuracy 
of the upset inventory causes EPA to speculate on the implications of 
this omission and exactly how much of the underprediction bias is due 
to unreported/underreported emission events.
    Response M7: As we discussed in our proposal and TSD, the 
attainment strategy is based on a two-pronged approach: control of 
routine emissions and a short-term limit to control emission events. 
The TCEQ indicated that the influence from short-term releases must be 
removed from the area's design value to determine the design value 
based on routine emissions. This alternative design value theoretically 
will more closely correspond to the routine urban ozone formation 
captured by the model. To remove influence of short-term releases, TCEQ 
applied Blanchard's technique on the 1999-2001 AIRS data. This 
technique uses a threshold of a 40 ppb rise in ozone concentration in 
one hour to distinguish sudden rises from the more typical case where 
ozone increases more gradually. Removing all days with identified 
sudden ozone concentration increases (SOCI), an alternate design value 
of 144 ppb was calculated by TCEQ. Final base case (i.e., Base 5b) 
includes seven days with modeled peak ozone greater than 144 ppb, so 
the modeled peaks in fact, represent very well the TCEQ estimated (non-
SOCI) design value.
    EPA considers the alternative design value approach a reasonable 
tool in evaluating the possible impact of non-routine emission 
releases, particularly releases of HRVOCs on the design value. By 
removing the days that have rapid ozone formation and therefore are 
possibly the result of large releases, it is possible to get a sense of 
the impact of emission releases on the design value. We are not 
convinced that all occasions where ozone rises by 40 ppb from one hour 
to the next are caused by releases. Some of these events could be 
caused by continuous plumes of ozone sweeping across a monitor as winds 
shift direction. These issues take some of the benefit away. In 
addition, other studies (including H13) of the frequency of reported 
emission events have indicated that the occurrence of reported events 
in the right location at the right time in order to impact peak ozone 
levels only occurs with a small percentage of non-routine releases. 
Still, we agree that emission events do impact the design value to some 
degree. Therefore, we agree that considering the alternative non-SOCI 
design value provides additional evidence that the future design value 
will reach the standard in the future case.
    We disagree with the commenter's criticism of TCEQ's analysis of 
August 30th. The 30th had a large flaring event that was likely 
underestimated even with the hypothetical run by TCEQ as the 
photographs indicate the flare was not completely combusting the 
emissions. TCEQ considered a hypothetical situation and was 
conservative (both TCEQ and EPA's TSD include this evaluation) in 
estimating the true level of emissions present. TCEQ's analysis does 
indicate that their hypothetical event would impact the ozone levels 
significantly and if actual emissions data were available to model, it 
would likely show a much larger impact. TCEQ's analysis was to support 
that at a minimum, the ``big smoky'' flare event could have a 
significant impact on the 30th and other such events would yield 
similar results. Furthermore, the flare sensitivity does not have to 
explain all of the underprediction bias on the 30th as many other 
factors (meteorology, emissions from other sources, etc.) also can 
result in such a bias.
    Furthermore, without the additional monitoring of units in HRVOC 
service that is included in this SIP revision, it is impossible to 
determine the absolute accuracy of HRVOC emission estimates from flares 
and similar emission sources. Therefore neither TCEQ nor EPA, could 
completely assess the full extent to which that HRVOC emission events 
impact daily ozone levels. TCEQ has required monitoring and restriction 
of HRVOC emissions that will reduce the chance of these types of 
emissions impacting ozone exceedances levels.
    As we indicated in the TSD for this notice, other studies 
(including H13) of the frequency of reported emission events have 
indicated that the occurrence of reported events in the right location 
at the right time in order to impact peak ozone only occurs with a 
small percentage of non-routine releases. The H13 study relied on 
reported emission events that are likely underreported and also should 
be considered a conservative estimate of potential impacts from short-
term HRVOC emission events since some events are larger than the levels 
modeled and ozone formation is not linear. TCEQ determined, and EPA 
concurs, that it is necessary to reduce the frequency of emission 
events so that emission events do not interfere with attainment of the 
1-hour NAAQS, which only allows an average of one exceedance per year. 
Based on our review, we believe the hourly emission limit will achieve 
this goal. Because facilities would be expected to take action to avoid 
emissions events exceeding the short-term limit of 1,200 lbs/hr, we 
anticipate that the frequency of such events in the future will be 
lower than in the past and therefore less than one event per year 
impacting peak ozone should be expected. Even though emission levels 
above 1,200 lbs/hr do not count towards the Annual Cap, the Annual Cap 
level is low enough that a source could not operate at a 1,200 lb/hr 
rate for extended periods without severely impacting its Annual cap 
level that is on the order of 2,000 lbs/day or less for most facilities 
(maximum cap is 2,419 lbs/day). For more details about the relationship 
of the short-term limit and annual cap, please see the response for 
comment M8, the proposal and TSD materials.
    The commenter criticizes TCEQ for not estimating the level of under 
reporting and unreported emissions, but without flow monitors and other 
monitoring requirements on HRVOC emissions (that are being approved as 
part of this revision), it would be pure speculation by TCEQ without 
any strong basis.
    Comment M8: The commenter (Wilson) comments that TCEQ 
inappropriately assumed that upset emissions will not occur in the 
future. The commenter continues that TCEQ should have considered the 
chance for upset emission events to occur in the

[[Page 52687]]

future in its weight-of-evidence analysis.
    Response M8: While the structure of the HECT and the HRVOC rules 
anticipates that emission events will not be completely eradicated, EPA 
believes that in combination these programs provide sufficient 
disincentives that sources will reduce the frequency and magnitude of 
large emissions events such that emission events would not be expected 
to impact peak ozone levels. The University of Texas report ``Variable 
Industrial VOC Emissions and Their Impact on Ozone Formation in the 
Houston Galveston Area,'' April 16, 2004, estimated from historic 
information that it is probable that at least one event will occur 
annually at a time and location to impact peak ozone. It is therefore 
necessary to reduce the frequency of emission events so that emission 
events do not interfere with attainment of the 1-hour NAAQS, which only 
allows an average of one exceedance per year. Based on this study, we 
believe the hourly emission limit will achieve this goal. Because 
facilities would be expected to take action to avoid non-routine 
emissions events exceeding the short-term limit of 1,200 lbs/hr, we 
anticipate that the frequency of such events in the future will be 
lower than in the past and therefore less than one event per year 
impacting peak ozone should be expected.
    Based on the final HECT allocation scheme updated March 20, 2006, 
the largest allocation is 441.9 tons. This allocation is approximately 
equivalent to 100.9 lb/hr, assuming the facility will operate with the 
allocation as an hourly average to represent routine emissions. 
Therefore, the largest HECT allocation will be approximately twelve 
times smaller than the 1200 lb/hr short-term limit. For every other 
source under the HECT, the disparity would be even greater. Based on 
this difference between the short-term limit and presumed routine 
emissions levels, no source would be able to operate at the hourly 
limit for an extended period of time without pushing its emissions 
total close to or above the annual cap. Therefore, as discussed in our 
proposal, only truly non-routine emissions are expected to exceed the 
hourly limit. Furthermore, all exceedances of the 1200 lb/hr limit are 
subject to enforcement, which should act as a further deterrent to 
excess emissions events.
    Comment M9: The commenter (Wilson) commented that EPA should not 
approve the TCEQ's approach to less reactive VOCs, but should assume 
that the failure to analyze and develop control strategies for Other 
VOCs (non-highly reactive volatile organic compounds) will lead to 
higher levels of ozone formation than is represented by the TCEQ 
modeling analysis. The commenter continues that there is evidence that 
Other VOCs (OVOCs) are underestimated in the inventory and are a source 
of uncertainty. The commenter cites to a study by Environ ``Top Down 
Evaluation of the Houston Emissions Inventory Using Inverse Modeling'' 
(Yarwood et al., 2003) which indicated that about the right amount of 
reactivity had been added to the model and that further adjustment is 
not warranted. The commenter reiterated EPA's TSD by stating that the 
report indicates that about the right amount of reactivity had been 
added to the model by TCEQ with scaling of olefin to NOX 
emissions and that further adjustment to the inventory is not 
warranted. The commenter indicates that the Yarwood study is not 
conclusive on the point of assuming a linear function of emissions from 
each of the source categories and further cites from the study ``this 
finding does not rule out the possibility of achieving more significant 
improvements in model performance if just the right combination of 
relatively large adjustments were applied to the inventory.'' The 
commenter continues by further citing from the Yarwood report and 
indicates that statistically significant improvements in model 
performance were seen by increasing VOCs from area and mobile sources 
near and inside Beltway 8, and point sources located in the west end of 
the Houston Ship Channel. The commenter also indicated that the report 
indicated that the underestimation of VOCs in the Ship Channel sub-
region is particularly severe. The commenter concluded that TCEQ did 
not conduct a balanced evaluation of the Yarwood study and its OVOC 
modeling effort when TCEQ adopted the SIP revision.
    The commenter indicated that TCEQ's one base case modeling 
sensitivity with an adjusted OVOC inventory improved model performance 
including the performance of the peak predicted value.
    The commenter indicates that the case for adjusting OVOC emissions 
is also supported when evaluating the composition of model cell box in 
Channelview area to the long-term Auto Gas Chromatograph (GC) data from 
Channelview and Deer Park monitors. The commenter continues that the 
Ethylene and Olefin portions are a larger percent of total VOC compared 
to the monitoring data. The commenter also indicates that the OVOCs 
portions are underestimated by the box model compared to the long-term 
monitoring data.
    The commenter also presented information on TCEQ's future year 
modeling sensitivity with the OVOCs imputed and then compared future 
year peak values with the CS06a run and a control of all VOCs run 
(these runs were in TCEQ's TSD). The commenter comments that the 
imputing of OVOCs raises peak ozone values 2-30 ppb for the days of the 
episode.
    Response M9: The TCEQ was reluctant to make any inventory 
adjustments which could be viewed as arbitrary for modeling purposes. 
Even though there exists some data that OVOCs may be under reported, 
TCEQ decided that they did not have sufficient data to justify a 
particular emission inventory adjustment to OVOCs. EPA has also 
commented in the past that TCEQ should investigate OVOC adjustments and 
in our TSD and proposal we indicated that OVOC underreporting concern 
is an issue of uncertainty. At this time though, we recognize that TCEQ 
did not think they had enough data to develop a control strategy 
including a inventory that had imputed OVOCs. We agree with the 
commenter that the Yarwood report has some interesting sensitivities 
and potential impacts, but the body of data to support an OVOC adjusted 
inventory was not present when TCEQ developed the SIP in 2004. While 
the peak modeling values increased in the basecase with the imputed 
OVOCs, a full model performance analysis including statistics, time 
series, graphical, and responses to variations in EIs inputs was not 
done, so EPA does not conclude that overall model performance was 
better with the imputed OVOCs. A full modeling analysis would need to 
be conducted with the items listed to determine if the imputed OVOCs 
was getting the right answer for the right reason. TCEQ conducted model 
performance analysis of this level with both the base inventory and 
then with the HRVOC imputed inventory in order to support that the 
HRVOC imputed inventory was actually an improvement in the modeling. We 
will continue to encourage TCEQ to investigate OVOCs in the development 
of their future HGB SIPs. A separate study by Yarwood (H6E.2002 report) 
cited in our TSD included analysis showing that the Olefin to 
NOX imputing factor that TCEQ utilized produces 
approximately the correct amount of reactivity in the model. The 
olefin-to-NOX adjustment was applied only after a large body 
of peer reviewed research showed conclusively that such a discrepancy

[[Page 52688]]

affected emissions of certain HRVOCs from industrial sources. The 
bibliography included in TCEQ's TSD includes a list of many of the peer 
reviewed studies considered by TCEQ and reviewed by EPA.
    In TCEQ's response to comments on their HGB proposal in June 2004 
they agreed that there is some evidence that OVOCs may be 
underestimated in the modeling inventory, but the evidence to justify 
adjusting emissions of OVOC is much less conclusive and open to debate. 
TCEQ's response continued, that at that time, few in-depth analyses of 
aircraft observations had been conducted comparing OVOC concentrations 
with those expected based on the reported emissions. The TCEQ compared 
ambient concentrations of OVOC with the reported inventories at the 
Clinton Drive and Deer Park monitoring locations and used this data to 
conduct the OVOC modeling sensitivity. The study suggested that OVOC 
may be underreported by a factor of 4.8. The scope of this study was 
limited however, because in 2004 only these two TCEQ sites had 
collected continuous, multi-year speciated hydrocarbon data in the Ship 
Channel industrial district. We encourage TCEQ to continue to evaluate 
the Auto GC data and utilize the data in developing future SIPs.
    Based on our comments above on the need for a full base case model 
performance to justify the OVOC adjustment as an improvement in the 
modeling, we do not concur with commenter's comment that the future 
year model predictions with additional OVOCs included are of enough 
concern that EPA should not approve these SIP revisions. The future 
year sensitivity modeling is speculative and the base modeling was not 
verified to actually be a better performing modeling system with the 
OVOC imputation.
    In TCEQ's response to comments on their June 2004 proposal, they 
indicated that if the OVOC emissions are indeed underestimated 
substantially, then additional reductions may be necessary. We 
encourage TCEQ to continue to evaluate OVOCs in their development of 
the 8-hour SIP for HGB.
    Comment M10: The commenter (Wilson) commented that the 8-hour ozone 
non-interference demonstration is inadequate and biased, and that 
furthermore, may be based on a faulty emissions inventory since OVOCs 
were not adjusted and errors in simulating the CS-2001 control strategy 
occurred. The commenter concludes that EPA must find that the non-
interference demonstration is inadequate and disapprove the relaxation 
of control measures that if kept, could contribute to progress towards 
attaining the 8-hour standard.
    The commenter continues that the 8-hour modeling results presented 
in TCEQ's TSD shows that the proposed 1-hour strategy falls short of 
making reasonable progress towards 8-hour attainment. The commenter 
continues that the plan backslides in comparison to the 2001 approved 
plan because six of the 16 monitors show higher 8-hour Design Values 
and the area of exceedances is larger on 6 of the 10 days with the new 
SIP revisions. The commenter also comments the average of the relative 
reduction factors is essentially unchanged (0.7 percent lower after 
implementation of the proposed control strategy as compared to the EPA-
approved control strategy) and that significant additional reductions 
will be necessary to attain the 8-hour ozone standard.
    The commenter indicated that in addition to excluding the analysis 
of adjustments to the OVOC inventory, the TCEQ made a number of other 
assumptions that tend to bias the non-interference demonstration in 
favor of the proposed control strategy.
    The commenter indicated that the use of updated activity data as 
the basis for the CS-2001 may add as much as 20 tpd more NOX 
than would be allowed by the SIP revision that EPA is proposing to 
approve. The commenter did recognize that TCEQ had made several 
technical updates by using Mobile 6 that were acceptable. The commenter 
commented that a 13 percent increase in VMT that was included for the 
2000 motor vehicle emissions budget (MVEB) should have been restricted 
to the old VMT and that the inclusion of the additional VMT is 
inappropriate. The commenter continued that they were concerned with 
the use of a revised/updated 2007 Traffic Demand Model as the basis for 
the CS-2001 inventory because this included the new activity data, 
which results in as much as 20 tpd. The commenter continued that the 
old activity data should be used unless EPA approves a new MVEB.
    The commenter indicated that if EPA approves the use of updated 
activity data for the baseline model, then the MVEB is not a binding 
constraint. The commenter urged EPA to reconsider our guidance on the 
noninterference test and conduct our own analysis in a manner 
consistent with their comments.
    Response M10: EPA disagrees with the assertion that the non-
interference demonstration is inadequate and biased, and that it 
represents backsliding. As indicated in more detail in the proposal 
notice and TSD for this action, it was our observation that while 
individual monitors may have increases in ozone, overall the modeling 
metrics indicated either an even benefit or a slight increased benefit 
for the 8-hour ozone NAAQS. EPA gave the State guidance that non-
interference and equivalence can be demonstrated by showing through an 
air quality analysis, that the new strategy will not create more 8-hour 
ozone exceedances, higher 8-hour ozone concentrations, or higher 
cumulative exposure levels than the old strategy.
    The 8-hour demonstration process uses the model in a relative sense 
using Relative Reduction Factors (RRFs), so 8-hour modeling may show 
attainment with RRF analysis but still have grid cells over the 
standard in the model predictions. The results indicated that CS-08 is 
slightly more effective in reducing 8-hour ozone levels than CS-2001 in 
both average relative reduction factor (0.931 vs. 0.940) and in future 
design value (107 vs. 108 ppb), even though some stations fare slightly 
worse under the new control strategy as the commenter indicated. In 
weighting the 110(l) analysis, the closest thing to the attainment test 
is the change in RRFs and the change in Future design values between 
the old and new strategies. This is the brightest line test, so a 
reduction in these is a good indicator of non-interference. For most of 
the design values, they decrease with the new strategy (See Table I-3 
on page 76 of EPA's TSD). It is also important to realize that all of 
the higher design values (>95 ppb) decrease with the new strategy and 
with the exception of the Bayland Park (BAYP) monitor (which dropped 1 
ppb), they dropped a significant value (5-8 ppb).
    In addition, for both peak 8-hour ozone concentration and exposure 
metrics, benefits of the new strategy exceed those of the old strategy 
for every day that was modeled except September 6, where the old 
strategy performs slightly better. For the area of exceedance however, 
the comparison is less clear-cut. As the commenter indicated for area 
of exceedance, the older strategy shows more of a benefit on six of ten 
days and the new strategy shows a greater benefit on three days and on 
one day both strategies are equivalent. Even though more grid cell area 
per day were predicted to be in nonattainment, when the level of ozone 
above nonattainment was weighted with the grid cells predicted to be in 
nonattainment, the ozone exposure metric showed improvement for the 
majority of the days. EPA's guidance for demonstrating attainment for 
the 8-hour ozone NAAQS is to use the RRFs average for all the days that 
monitors

[[Page 52689]]

had elevated ozone. So even though some days had larger exceedance 
areas, the ability to attain the 8-hour ozone NAAQS will be more 
heavily weighted by the change in the average RRFs and the monitors 
with the higher design values. Although there are uncertainties with 
comparing the modeled results of the two strategies, EPA believes that 
the new strategy and the old strategy are at least equivalent in 
overall 8-hour ozone benefit with the new strategy slightly more 
effective in reducing the peak ozone values and the old strategy 
slightly more effective in reducing the area of exceedance. In summary, 
both the Future design values and RRFs are lower for the new strategy 
(especially for the higher design values that will be critical in 
future 8-hour attainment SIP development). Furthermore, two of the 
three ozone metrics showed improvement with the new strategy. Taking 
all of these metrics into consideration and recognizing the 
uncertainties in the modeling, we believe that Texas has demonstrated 
that the new strategy will not interfere with attainment of the 8-hour 
standard.
    The EPA agrees that a different mix of control measures may be 
necessary to reach attainment of the 8-hour ozone standard and the 
State will need to address this in their 8-hour ozone attainment SIP 
that is due in June 2007. At that same time, the State will need to 
submit its ``reasonable progress'' SIP for the 8-hour standard. As 
discussed previously in the response to comment for M9 comment, EPA 
determined that the Emission Inventory utilized for this attainment 
demonstration modeling was acceptable. EPA ultimately agreed with TCEQ 
that there was not enough data and studies on OVOCs to warrant imputing 
the inventory for OVOCs. Therefore, it would not have been reasonable 
to make a OVOC adjustment in the 110(l) analysis.
    TCEQ discussed with EPA the best approach to making this 
demonstration. One of the key issues of concern in conducting it was 
the fact that the photochemical modeling is now based on an improved 
August-September 2000 ozone episode rather than the older September 
1993 ozone episode on which the December 2000 SIP was based. 
Recognizing that this was a major change since 2000, the 
noninterference modeling included the control strategies listed in the 
December 2000 SIP together with updated inventories and updated 
methodologies utilizing the 2000 episode.
    The commenter emphasized that the December 2000 SIP MVEB placed a 
``binding constraint'' on how any CS-2000 onroad inventory should be 
developed. It was also suggested that the CS-2000 inventory should have 
coupled updated MOBILE6-based emission rates with the old VMT and other 
associated activity data from the December 2000 MVEB. This suggestion 
is impractical because an onroad emissions inventory which becomes an 
MVEB is a combination of both emission rates (from the MOBILE emissions 
model) and activity data (from a travel demand model). EPA concurs with 
the method that TCEQ conducted the VMT and MVEB for this 110(l) 
analysis.
    The 2007 on-road inventory that was developed for the December 2000 
SIP included an estimate of 129.4 million VMT from the Houston 
Galveston Area Council's (HGAC) travel demand modeling. Since that 
time, new travel networks, demographic data, census data, etc. inputs 
have been added to HGAC's travel demand modeling process, and the 
updated 2007 on-road inventory was developed, 146 million VMT is the 
best available estimate of 2007 activity levels. This inventory was 
developed by following EPA's memo entitled ``Policy Guidance on the Use 
of MOBILE6 for SIP Development and Transportation Conformity'', dated 
January 18, 2002, which can be found at http://www.epa.gov/otaq/m6.htm.
    The test that EPA has to apply to this SIP revision is that the 
revisions demonstrate attainment with the 1-hour ozone standard in 2007 
and that the revisions will not interfere with any other applicable CAA 
standard (including 8-hour ozone). EPA is approving these revisions and 
the revised motor vehicle emission budget in this action.
    Comment M11: The commenter (Wilson) commented that the emissions 
estimates for heavy-duty trucks do not use the best available 
information and cites a memo from Rick Baker of ERG to Hazel Barbour 
(TCEQ) dated August 30, 2003 that indicates the 2007 mobile inventory 
may be underestimated by up to 3.7 tpd of NOX due to heavy-
duty trucks not being reflashed. The commenter also noted that as of 
November 2004, only 12.7 percent of the applicable trucks nationally 
had been reflashed. The commenter also commented that the EPA default 
``reflash'' rate of 90 percent for heavy-duty diesel trucks was 
inappropriate for use in development of the 2007 on-road emissions 
inventory.
    Response M11: The commenter is correct in noting that under a 1998 
consent decree with EPA, manufacturers of diesel truck engines are 
required to install software upgrades (reflash) to engines they sold 
between 1993 and 1998 with ``defeat devices'' that resulted in higher 
NOX emissions than allowed by applicable certification 
standards. All States except California are required to use the latest 
available version of EPA's MOBILE emissions model for on-road SIP 
inventory development purposes. In addition, States are encouraged to 
use EPA guidance when using the MOBILE model for SIP purposes. The 
latest version of the MOBILE6.2 User's Guide (dated August 14, 2003) 
can be found at http://www.epa.gov/otaq/m6.htm. The User's Guide 
indicates that a default effectiveness rate of 90 percent should be 
used, unless good local data is available.
    While the commenter is correct that some local data with estimates 
of how many trucks had been reflashed in 2002 and nationally in 2004 
exists, the consent decree still requires all the trucks to be 
reflashed by 2008. With the compliance date of 2008 for the consent 
decree, EPA has not changed the recommended default value of 90 percent 
for 2007. While reflash rates may have been slow and below expected 
levels in 2002 and 2004, the flash rate did increase from 2 percent in 
2002 to 12 percent in 2004 according to the comment. Furthermore, EPA 
still expects the consent decree to be met in 2008, so a high 
compliance rate in 2007 is thought to be an appropriate estimate. TCEQ 
modeled 2007 emissions with the EPA recommended default rate of 90 
percent reflash rate and decided to utilize EPA defaults. EPA concurred 
at the time that this was an acceptable assumption. Furthermore in 
March 2006, EPA issued a letter to TCEQ confirming that for the 8-hr 
ozone SIP, that TCEQ could use EPA defaults for the MOBILE emission 
estimates for the truck population subject to the reflash requirement.
    Comment M12: The commenter (Wilson) commented that the TCEQ has not 
revised off-road and area emissions to account for operations of two 
permitted container and cruise ship port facilities. The commenter 
indicated that they did not believe the current SIP revision fully 
accounts for operating emissions related to the rapid growth in port 
facilities in the Houston region including ship, train and truck 
emissions that would also increase as a result of the port activity. 
The commenter asks EPA to evaluate whether these ports and the 
associated growth emissions were included in the proposed SIP revision.
    Response M12: The projected 2007 shipping inventory explicitly 
accounts for traffic to/from the new Bayport container and cruise 
terminals. The shipping inventory does not account for

[[Page 52690]]

the Texas City container terminal, which was approved long after the 
current inventory was developed. However, even though the facility 
plans to open in 2006, the level of activity through 2007 will likely 
be fairly modest. The TCEQ plans to revise its shipping inventory to 
include emissions associated with this new port in future modeling 
work.
    Future ship and train emissions are normally accounted for by 
growth factors developed by applying econometric growth forecasts as 
was done in this case. During EPA's review of the Bayport Draft EIS's, 
we reviewed the estimated emissions from increased ship traffic from 
the new ports and the total was less than the growth amount in tpd of 
NOX that TCEQ had included for 2007 modeling in this SIP.
    TCEQ estimated train emissions by growing the area-wide inventory 
according to projected trends. Because there is insufficient 
information available to allocate emissions of locomotives to specific 
track segments, the growth was spread across all the track miles in the 
8 county area equally. TCEQ has a project to improve Texas locomotive 
emissions and it's results should be added to the model for the 8-hour 
SIP.
    Truck emissions are based on travel-demand modeling conducted by 
HGAC, which included the Bayport and Texas City terminals in the 2007 
inventories it generated for TCEQ's future case modeling.
    Comment M13: The commenter (Wilson) indicates that TCEQ continues 
to claim credit for emission reductions from the institution of Federal 
DOE standards on certain appliances even though TCEQ has dropped these 
measures from their attainment modeling. The commenter states that if 
these measures have been dropped, then EPA should provide a reference 
for this change.
    Response M13: In the previous SIP, TCEQ had included the DOE energy 
efficiency benefits as a gap measure but had not modeled the 
reductions. The HGB area is part of a NOX Cap and Trade 
program and any reductions due to increases in energy efficiency, 
including federal appliance energy efficiency programs, could help 
utilities maintain their cap and might not yield actual reductions to 
the HGB airshed. While federal (DOE) appliance energy efficiency 
programs still exist, TCEQ has dropped taking credit for these programs 
in this SIP revision because of the HGB Cap and Trade program. TCEQ did 
not include any potential emission reductions in this SIP revision that 
may occur for other areas of Texas from DOE appliance energy efficiency 
programs.
    Comment M14: The commenter indicates that EPA should not approve a 
plan that fails to require industry to reduce emissions of OVOCs. The 
commenter refers to the comment on OVOC modeling sensitivity to 
substantiate their comment. Furthermore, the commenter refers to 
presentations by TCEQ and a report by TCEQ indicating that large 
amounts of VOC reactivity from OVOC and HRVOCs could yield ozone based 
on analysis of Auto gas chromatographs that are not part of the 
chemicals compounds covered by the HRVOC rules. The presentations and 
reports indicated were: John R. Jolly, Fernando I. Mercado, and David 
W. Sullivan, ``A Comparison of Ambient and Emissions VOC to 
NOX Ratios at Two Monitors in Houston, Texas'' (Texas 
Commission on Environmental Quality, June 2004). Mark Estes et al., 
``Analysis of Automated Gas Chromatograph Data from 1996-2001 to 
Determine VOCs with Largest Ozone Formation Potential'' (TCEQ Technical 
Support Document Attachment 6, December 2002). Mark Estes, ``VOC 
Reactivity Before, During and After TexAQS 2000'' (Presentation to 
TexAQS Science Meeting, February 2004). John Jolly and Elaine 
Schroeder, ``Analysis of HGB Enhanced Industry-Sponsored Monitoring 
(EISM) Data'' (Presentation to EISM Network Stakeholder Meeting, as 
updated April 2004). John Jolly et al., ``An Analysis of VOC Reactivity 
in Houston'' (TCEQ SIP Technical Support Document Appendix GG, January 
23, 2004).
    Response M14: See Response to Comment M9 for EPA's comments on the 
analysis of sensitivity modeling of OVOCs. EPA is approving this 
package because it has demonstrated that the area will attain the 1-
hour ozone standard by November 15, 2007 and that no additional 
reductions were determined to be needed by TCEQ. EPA had previously 
reviewed the presentations and reports that the commenter refers to in 
their comment, prior to our proposed action on these SIP revisions. 
These studies do suggest that more information is needed on the 
imputing of OVOCs, but they do not in and of themselves provide enough 
of a technical basis to take action on imputing OVOCs at this time. EPA 
encourages TCEQ to continue to evaluate OVOCs and other HRVOCs and 
consider regulating sources of these chemical compounds if modeling 
indicates that their control is necessary for attainment of the 8-hour 
ozone NAAQS.
    Comment M15a: The commenter indicates that EPA cannot assume the 
level of control effectiveness claimed by the TCEQ for regulating 
HRVOCs. The commenter indicates that TCEQ failed to provide an estimate 
of rule effectiveness that takes into account that the sources it 
regulates may not sufficiently encompass the major sources of HRVOCs, 
and to address the specific challenges of enforcement and 
implementation. The commenter continued that TCEQ did not consider 
evaporative emissions from rail tank cars and fugitive emissions from 
above ground and underground pipelines carrying petroleum products and 
from barges.
    Response M15a: Aircraft flights and other monitoring during and 
since the TexAQS 2000 study have indicated a significant under-
reporting of emissions of HRVOCs that are emitted primarily from 
industrial sources. As previously discussed in our proposed approval 
notice (70 FR 58119) and the TSD, EPA believes that the field data 
collected in 2000 and since indicates that rule effectiveness has been 
previously overestimated for sources of HRVOCs. TCEQ significantly 
increased the basecase 2000 inventory for industrial sources of HRVOC 
by imputing the inventory to correct for the over estimation of rule 
effectiveness and to bring the 2000 HRVOC rule effectiveness estimate 
in line with the available ambient data that has been collected. EPA 
believes TCEQ's adjustment to the basecase inventory is appropriate 
based on the information available. TCEQ then adopted HRVOC rules to 
reduce emissions of HRVOCs and put in place additional monitoring to 
maintain compliance with the new limits on HRVOCs. Because of these 
changes by TCEQ, EPA finds that rule effectiveness is adequate for the 
HRVOC program.
    Having identified that HRVOC's need to be reduced, as discussed 
elsewhere, TCEQ adopted rules for the control of HRVOC's. As discussed 
elsewhere, TCEQ has implemented an annual HRVOC cap to reduce emissions 
of HRVOCs. TCEQ reduced the annual HRVOC cap levels that were set in 
the regulations by 5 percent compared to modeled levels in setting the 
HRVOC annual cap limits in part to address rule effectiveness and 
emission characterization concerns regarding daily variability in 
emissions and geographical variability of location of emissions. These 
HRVOC rules also incorporated stronger monitoring, recordkeeping, and 
reporting than previous versions of rules for the control of VOCs. 
Therefore EPA believes that

[[Page 52691]]

future rule effectiveness will be much improved over the past.
    Specifically, TCEQ now requires direct continuous measurement of 
flow and heating value of the flow to flares, which is a vast 
improvement over the past practice using engineering estimates and one 
time tests. TCEQ also requires monitoring of flow and concentration to 
cooling towers giving a direct measurement of emissions. When direct 
measurements are used, no rule effectiveness adjustment is necessary. 
Finally for fugitive emissions, TCEQ is requiring third party audits 
that will be used to confirm that the expected rule effectiveness has 
been achieved for the leak detection and repair program. TCEQ has 
agreed to utilize the available data, including the first third party 
audits, to conduct a rule effectiveness study in 2006 and include this 
analysis in development of future SIPs.
    EPA believes that certain past practices are being improved to 
reduce the uncertainty of the estimates. In particular, the uncertainty 
introduced by certain assumptions of control efficiency and rule 
effectiveness is being improved. This approach of reassessing rule 
effectiveness when additional data is available is consistent with 
EPA's guidance on how to address rule effectiveness (EPA memo on rule 
effectiveness from Sally Shaver dated April 27, 1995; and guidance 
document EPA-452/4-94-001, RULE EFFECTIVENESS GUIDANCE: INTEGRATION OF 
INVENTORY, COMPLIANCE, AND ASSESSMENT APPLICATIONS). EPA is approving 
the emission reductions that have been projected for the improved 
fugitive emissions rules because the new measurement and monitoring 
requirements in the adopted rule will result in significantly improved 
accuracy. In addition, Texas has committed to perform a rule 
effectiveness study and use improved emission inventory techniques to 
estimate future emissions and confirm the effectiveness of the program.
    It is EPA's position that VOC emissions and some HRVOC emissions 
could occur from the sources that the commenter mentions and are 
outside the traditional TCEQ regulatory field (evaporative emissions 
from rail cars in transit, barges in transit, pipelines, etc.). TCEQ 
has followed EPA guidelines in estimating emissions from these sources 
in development of the Emission Inventory for this revision. The initial 
field monitoring data that indicated these may be areas underestimated 
by traditional EPA guidelines was only starting to be available in 
2003-2004 time frame as TCEQ was developing this revision. At the time 
TCEQ was developing this revision, there was not a sufficient body of 
data to allow for any estimation of the level of emissions that may 
exist from these sources that are not in the inventory currently. EPA 
believes that the inventory reflects the best estimate of emissions 
that was possible at the time. Inventory analysis is always an ongoing 
process that is constantly needing to be improved. TCEQ will continue 
to investigate and improve emission estimates. Furthermore, the 
investigation into these potential sources of error in the emission 
inventory will lead to better science and planning of effective control 
packages to attain the 8-hour standard. We encourage TCEQ and others to 
continue to use imaging devices and other technologies to help refine 
emission inventories.
    Comment M15b: The commenter indicated that they were concerned with 
HRVOC fugitive rules for leak monitoring that seem to place 
determination of the threshold with the source under TCEQ rules section 
115.781(f). The commenter felt that the rules should specifically state 
that TCEQ retains the discretion to determine monitoring intervals.
    The commenter indicated that EPA should not approve backsliding on 
the fugitive rules for facilities not in HRVOC service in the Houston 
region. The commenter further expressed concern that inspectors and 
enforcement actions would be hindered by the removal of language on: 
(1) Specifying the procedure that must be used to demonstrate that 
leaking components cannot be repaired without a process unit shutdown, 
(2) specifying the requirements for undertaking extraordinary efforts 
to control leaks, (3) requiring the use of electronic data collection 
devices during monitoring, use of an electronic database, and 
documentation of an auditing process to assure proper calibration, 
identify response time failures, and assess pace anomalies. These 
changes were in changes in Texas regulations section 115.352 and 
115.354.
    Response M15b: EPA disagrees with the assertion from the commenter 
that TCEQ rules section 115.78(f) and other parts of the new HRVOC 
rules place determination of threshold with the source. The rules 
(section 115.788 (a-d)) require third party audits of the HRVOC 
monitoring at a facility, including 115.78(f) requirements to be 
conducted and submitted to TCEQ. If these third party audits raise 
deficiencies, section 115.788(e) requires the source to submit a 
corrective action plan to TCEQ. Furthermore, Texas rules section 
115.788(f) allows for TCEQ and EPA to conduct audits. Upon review of 
audit results, Texas rules section 115.788(h) allow the TCEQ to specify 
additional corrective actions. Therefore, EPA believes that TCEQ 
retains authority to determine compliance with section 115 HRVOC rules, 
including section 115.78(f).
    The commenter is correct that some of the minor rule changes on 
sources in fugitive service may be considered a relaxation of previous 
Texas regulations (115.352 and 115.354), but all three changes 
identified were changes that Texas has made to rules they previously 
adopted at the state level in 2002. The rules that were changed were 
never approved into the federal SIP. Therefore these changes are not a 
relaxation of the federally approved SIP. Many other changes to 
regulation 115, regarding VOC controls, strengthen the SIP and are 
considered in the more detail in our TSD. EPA disagrees with the 
commenter and does not consider this a backsliding issue of federally 
approved measures.
    Comment M15c: The commenter concerns about flare efficiency related 
to too much air or steam assist and high winds, and questioned what 
impact these factors can have on a flare's destruction efficiency. The 
commenter indicated that EPA should not approve rule language that may 
discourage research and application of monitoring technology to verify 
destruction efficiencies or the use of remote technology to determine 
destruction efficiencies.
    Response M15c: We are approving the estimates used for flare 
destruction efficiency because the estimates are based on the best 
scientific information available. Like the commenter, we are concerned 
by the uncertainty introduced by having a significant source of 
emissions which cannot be directly measured. We also share concerns 
that several factors can potentially impact flare destruction 
efficiency, including wind speed and volumes to the flare as well as 
how it is operated, but the current estimates are based on the best 
information available at the time these SIP revisions were completed. 
We believe Texas should strongly consider requirements for monitoring 
steam and air assist ratios to insure that operators maintain these 
parameters in a range to insure optimum combustion. We also encourage 
TCEQ to pursue new technology such as the Fourier Transform Infra-red 
Spectrophotometer to eventually be able to directly measure destruction 
efficiency in the field.
    Comment M15d: The commenter indicated that EPA should evaluate if

[[Page 52692]]

interlock devices that regulate the ratio of air (or steam) should be 
considered reasonably available control measures (RACM), and that EPA 
should not approve this SIP unless TCEQ develops regulations requiring 
the use of interlock devices.
    Response M15d: We covered the changes to TCEQ's previously approved 
RACM in detail in the proposal (70 FR 58119) and TSD. EPA determined 
that all reasonably available control measures were being implemented 
in the Houston area. In section II.a. of the TSD (pages 51-56), we 
discuss EPA's analysis that the revised plan will achieve attainment of 
the one-hour standard, based the controls that will be in place by the 
ozone season of 2007. As part of the RACM analysis we estimated that to 
advance attainment more than 39 tpd of additional NOX 
emission reductions would have to be achieved before the ozone season 
of 2006. EPA guidance is that a justification would need to support 
that a measure was not reasonably available for that area and could be 
based on technological or economic grounds.
    The commenter indicated that EPA should consider requiring 
interlock devices as RACM. The commenter did not provide a potential 
quantification of how much emission reductions such a requirement would 
create nor how such a measure would result in ozone reductions such 
that attainment could be achieved earlier than 2007. It is not clear 
that even if such a requirement existed that it would result in enough 
emission reductions to advance attainment. Furthermore, the comment on 
the use of interlock devices was not made during TCEQ's development of 
these rules in 2004 and the first time this issue has been raised was 
in the commenter's letter to EPA received in November 2005. Even if the 
interlock devices could result in enough reductions, it would not have 
been possible for TCEQ to implement a rule requiring the use of 
interlock devices and for the applicable sources to achieve compliance 
with a interlock rule by the beginning of the 2006 ozone season. TCEQ 
rule development alone typically requires at least 9-12 months, so just 
the rule development timing would have made it impossible to advance 
attainment. Since attainment could not be advanced, EPA does not 
consider a requirement for the use of interlock devices to be a 
potential RACM measure. EPA does strongly encourage TCEQ to consider 
the use of interlock devices in the development of the 8-hour 
attainment demonstration for HGB.
    Comment M16: The commenter indicates that EPA should discount any 
emission reduction benefit from the Environmental Monitoring Response 
System (EMRS). The commenter cited a comment from the TSD for this 
action indicating that EPA ``believes the added scrutiny of ambient VOC 
levels will provide feedback to industry on the activities that may be 
causing increased VOC emissions resulting in improved overall program 
effectiveness and possibly identifying previously unknown sources of 
emissions.'' The commenter then commented that TCEQ had recently 
reported that the goal of stopping HRVOC events in real time can not be 
achieved with EMRS. The commenter concludes that EPA should not find 
that the EMRS system will result in emission reductions which have not 
been accounted for in the model.
    Response M16: EPA was aware that TCEQ was trying to stop HRVOC 
events in real time with the EMRS. During the proposal and development 
of the EMRS program and to this date, we were skeptical that this could 
be done considering the meteorology and density of sources in wind 
sectors around the monitors. We do think that the data and continued 
focus on what compounds are emitted and alerting the sources is a 
worthwhile project and should continue to aid in finding new sources or 
issues that will improve the understanding of ozone formation and 
exceedances in the HGB area. We do think that it will also be a tool to 
help determine what facilities or group of facilities should be 
evaluated further in solving HGB's air quality issues.
    Comment M17: The commenter indicates that EPA should not approve 
the NOX emission reduction relaxations as these changes will 
be needed for further progress on the 8-hour.
    The commenter commented that in at least one case the ESAD level 
adopted by Texas was higher than required by California. The commenter 
indicated that the California standard was for gas fired utility 
boilers with a capacity greater than 100 mmBtu/Hr is 0.02-0.03 lbs/
mmBtu, whereas the Texas standard is 0.03 lb/mmBtu. The commenter 
continues that TCEQ should provide an evaluation for each difference in 
ESADs that are being changed with these NOX MECT revisions 
and explain why the lower ESAD was not utilized and until this is 
completed EPA should not approve these revisions.
    Response M17: EPA has reviewed this SIP revision package and 
determined that the package demonstrates attainment of the 1-hour ozone 
NAAQS. As explained above, this submission was not for the purpose of 
addressing reasonable further progress forward and attainment of the 8-
hour NAAQS. Texas is undertaking a significant and intense new air 
study (TexAQS II) in HGB. With this new information coming in and new 
8-hour modeling taking place it is to early to determine what the 
appropriate suite of control measures will be for 8-hour attainment. 
TCEQ is in the process of developing the 8-hour demonstrations which 
are due to EPA on June 15, 2007.
    EPA reviewed the RACM levels as discussed in a previous response 
and in the TSD for this action. The Texas standard is within the range 
(although on the high end) of the ESAD for the California rule and was 
reviewed prior to proposal and determined to be acceptable for RACM. 
EPA conducted a review of the changes to ESAD levels and documented 
California levels for each source category and Texas 90 percent and 80 
percent in Table 6.B-1 of the TSD and determined the levels to be 
acceptable. Furthermore, as indicated in a previous response there are 
no additional measures that could be implemented to advance the 
attainment date sooner than the current attainment date in 2007.

Statutory and Executive Order Reviews

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this 
action is not a ``significant regulatory action'' and therefore is not 
subject to review by the Office of Management and Budget. For this 
reason and because this action will not have a significant, adverse 
effect on the supply, distribution, or use of energy, this action is 
also not subject to Executive Order 13211, ``Actions Concerning 
Regulations That Significantly Affect Energy Supply, Distribution, or 
Use'' (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 that this rule will not have a significant 
economic impact on a substantial number of small entities under the 
Regulatory Flexibility Act (5 U.S.C. 601 et seq.). Because this rule 
approves pre-existing requirements under state law and does not impose 
any additional enforceable duty beyond that required by state law, it 
does not contain any unfunded mandate or significantly or uniquely 
affect small governments, as described in the Unfunded Mandates Reform 
Act of 1995 (Pub. L. 104-4).
    This rule also does not have tribal implications because it will 
not have a substantial direct effect on one or more

[[Page 52693]]

Indian tribes, on the relationship 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, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government, 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 of power and 
responsibilities established in the CAA. This rule also is not subject 
to Executive Order 13045 ``Protection of Children from Environmental 
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997), because 
it is not economically significant.
    In reviewing SIP submissions under the National Technology Transfer 
and Advancement Act of 1995 (15 U.S.C. 272 note), EPA's role is to 
approve state choices, provided that they meet the criteria of the CAA. 
In this context, in the absence of a prior existing requirement for the 
State to use voluntary consensus standards (VCS), EPA has no authority 
to disapprove a SIP submission for failure to use VCS. It would thus be 
inconsistent with applicable law for EPA, when it reviews a SIP 
submission, to use VCS in place of a SIP submission that otherwise 
satisfies the provisions of the CAA. Thus, the requirements of section 
12(d) of the National Technology Transfer and Advancement Act of 1995 
do not apply. This rule does not impose an information collection 
burden under the provisions of the Paperwork Reduction Act of 1995 (44 
U.S.C. 3501 et seq.).
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).
    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by November 6, 2006. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this rule for the purposes of judicial review nor does 
it extend the time within which a petition for judicial review may be 
filed, and shall not postpone the effectiveness of such rule or action. 
This action may not be challenged later in proceedings to enforce its 
requirements. (See section 307(b)(2).)

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Incorporation by reference, Intergovernmental relations, Nitrogen 
dioxide, Ozone, Particulate matter, Reporting and recordkeeping 
requirements, Volatile organic compounds.

    Dated: August 24, 2006.
Richard E. Greene,
Regional Administrator, Region 6.

0
40 CFR part 52 is amended as follows:

PART 52--[AMENDED]

0
1. The authority citation for part 52 continues to read as follows:

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

Subpart SS--Texas

0
2. Section 52.2270 is amended as follows:
0
a. The table in paragraph (c) entitled ``EPA Approved Regulations in 
the Texas SIP'' is amended as follows:
0
1. By revising entries for Sections 114.1 and 114.2 under Chapter 114 
(Reg 4), Subchapter A.
0
2. By revising the heading entitled ``Subchapter B: Vehicle Inspection 
and Maintenance'' under Chapter 114 (Reg 4) to read ``Subchapter C--
Vehicle Inspection and Maintenance; Low Income Vehicle Repair 
Assistance, Retrofit, and Accelerated Vehicle Retirement Program; and 
Early Action Compact Counties''; adding a new centered heading 
``Division 1: Vehicle Inspection and Maintenance'' immediately 
following it; revising entries for Sections 114.50, 114.52, and 114.53; 
and removing the heading entitled ``Subchapter C--Vehicle Inspection 
and Maintenance; Low Income Vehicle Repair Assistance, Retrofit, and 
Accelerated Vehicle Retirement Program; and Early Action Compact 
Counties'' that follows Section 114.53.
0
3. By removing the heading entitled ``Division 6: Lawn Service 
Equipment Operating Restrictions'' under Chapter 114 (Reg 4), 
Subchapter I; and removing entries for Sections 114.452 and 114.459.
0
4. By removing the heading entitled ``Division 1: Motor Vehicle Idling 
Limitations'' under Chapter 114 (Reg 4), Subchapter J; and removing 
entries for Sections 114.500, 114.502, 114.507, and 114.509.
0
5. By revising the heading entitled ``Chapter 117 (Reg 7)--Control of 
Air Pollution from Nitrogen Compounds--Subchapter A'' to read ``Chapter 
117 (Reg 7)--Control of Air Pollution from Nitrogen Compounds''; adding 
a centered heading entitled ``Subchapter A--Definitions'' immediately 
following it; and revising the entry for Section 117.10.
0
6. By revising the heading entitled ``Subchapter B--Division 1--Utility 
Electric Generation in Ozone Nonattainment Areas'' under Chapter 117 
(Reg 7) to read ``Subchapter B--Combustion at Major Sources''; adding a 
centered heading entitled ``Division 1: Utility Electric Generation in 
Ozone Nonattainment Areas'' immediately following it; removing the 
entry for 117.104; and revising entries for Sections 117.105-117.108, 
117.113-117.116, 117.119, 117.131, 117.135, 117.138, 117.141, 117.143, 
117.149, 117.203, 117.205-117.207, 117.213-117.216, 117.219, and 
117.223.
0
7. By revising the heading entitled ``Subchapter C--Division 1--ADIPIC 
Acid Manufacturing'' under Chapter 117 (Reg 7) to read ``Subchapter C--
Acid Manufacturing''; adding a centered heading entitled ``Division 1: 
ADIPIC Acid Manufacturing'' immediately following it; and revising 
entries for Sections 117.301, 117.309, 117.311, 117.313, 117.319, 
117.321, 117.401, 117.409, 117.411, 117.413, 117.419, and 117.421.
0
8. By revising the heading entitled ``Subchapter D--Water Heaters, 
Small Boilers, and Process Heaters'' under Chapter 117 (Reg 7) to read 
``Subchapter D--Small Combustion Sources''; adding a new centered 
heading ``Division 1: Water Heaters, Small Boilers, and Process 
Heaters'' immediately following it; adding a new centered heading 
``Division 2: Boilers, Process Heaters, and Stationary Engines and Gas 
Turbines at Minor Sources'' immediately preceding the entry for Section 
117.471; and revising entries for 117.463, 117.465, 117.473, 117.475, 
117.478, and 117.479.

[[Page 52694]]

0
9. By removing entries for Section 117.540 and 117.560 under Chapter 
117 (Reg 7), Subchapter E; and revising entries for 117.510, 117.512, 
117.520, and 117.534.
0
b. The second table in paragraph (e) entitled ``EPA Approved 
Nonregulatory Provisions and Quasi-Regulatory Measures in the Texas 
SIP'' is amended by adding a new entry at the end to read as follows:


Sec.  52.2270  Identification of plan.

* * * * *
    (c) * * *

                                                        EPA-Approved Regulations in the Texas SIP
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   State  approval/
           State citation                   Title/subject           submittal date           EPA approval date                     Explanation
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           Chapter 114 (Reg 4)--Control of Air Pollution from Motor Vehicles
                                                                Subchapter A--Definitions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 114.1......................  Definitions................           09/05/04  09/06/06 [Insert FR page number
                                                                                      where document begins].
Section 114.2......................  Inspection and Maintenance            09/05/04  09/06/06 [Insert FR page number
                                      Definitions.                                    where document begins].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
 Subchapter C--Vehicle Inspection and Maintenance; Low Income Vehicle Repair Assistance, Retrofit, and Accelerated Vehicle Retirement Program; and Early
                                                                Action Compact Counties
                                                     Division 1: Vehicle Inspection and Maintenance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 114.50.....................  Vehicle Emission Inspection           09/05/04  09/06/06 [Insert FR page number    Subsection 114.50(b)(2) is
                                      Requirements.                                   where document begins].           NOT part of the
                                                                                                                        approved SIP.
 
                                                                      * * * * * * *
Section 114.52.....................  Early Participation                   09/05/04  09/06/06 [Insert FR page number
                                      Incentive Program.                              where document begins].
Section 114.53.....................  Inspection and Maintenance            09/05/04  09/06/06 [Insert FR page number
                                      Fees.                                           where document begins].
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Division 3: Early Action Compact Counties
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                     * * * * * * *
                                                             Subchapter I--Non-Road Engines
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
Section 114.429....................  Affected Counties and                 12/06/00  11/14/01, 66 FR 57222............
                                      Compliance Schedules.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Subchapter J--Operational Controls for Motor Vehicles
                                              Division 2: Locally Enforced Motor Vehicle Idling Limitations
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     * * * * * * *
                                         Chapter 117 (Reg 7)--Control of Air Pollution from Nitrogen Compounds
                                                                Subchapter A--Definitions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 117.10.....................  Definitions................           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Subchapter B--Combustion at Major Sources
                                           Division 1: Utility Electric Generation in Ozone Nonattaiment Areas
--------------------------------------------------------------------------------------------------------------------------------------------------------
 

[[Page 52695]]

 
                                                                      * * * * * * *
Section 117.103....................  Exemptions.................           09/26/01  114/14/01, 66 FR 57244...........
Section 117.105....................  Emission Specifications for           12/13/02  09/06/06 [Insert FR page number
                                      Reasonably Available                            where document begins].
                                      Control Technology (RACT).
Section 117.106....................  Emission Specifications for           12/13/02  09/06/06 [Insert FR page number    The SIP does not
                                      Attainment Demonstrations.                      where document begins].           include section 117.106(d).
Section 117.107....................  Alternative System Emission           12/13/02  09/06/06 [Insert FR page number
                                      Specifications.                                 where document begins].
Section 117.108....................  System Cap.................           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
 
                                                                      * * * * * * *
Section 117.113....................  Continuous Demonstration of           12/13/02  09/06/06 [Insert FR page number
                                      Compliance.                                     where document begins].
Section 117.114....................  Emission Testing and                  12/13/02  09/06/06 [Insert FR page number
                                      Monitoring for the Houston-                     where document begins].
                                      Galveston Attainment
                                      Demonstration.
Section 117.115....................  Final Control Plan                    12/13/02  09/06/06 [Insert FR page number
                                      Procedures for Reasonably                       where document begins].
                                      Available Control
                                      Technologies.
Section 117.116....................  Final Control Plan                    12/13/02  09/06/06 [Insert FR page number
                                      Procedures for Attainment                       where document begins].
                                      Demonstration Emission
                                      Specifications.
 
                                                                      * * * * * * *
Section 117.119....................  Notification,                         12/13/02  09/06/06 [Insert FR page number
                                      Recordkeeping, and                              where document begins].
                                      Reporting Requirements.
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Division 2--Utility Electric Generation in East and Central Texas
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 117.131....................  Applicability..............           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
 
                                                                      * * * * * * *
Section 117.135....................  Emission Specifications....           12/13/02  09/06/06 [Insert FR page number    The SIP does not
                                                                                      where document begins].           include section 117.106(d).
Section 117.138....................  System Cap.................           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
Section 117.141....................  Initial Demonstration of              12/13/02  09/06/06 [Insert FR page number
                                      Compliance.                                     where document begins].
Section 117.143....................  Continuous Demonstration of           12/13/02  09/06/06 [Insert FR page number
                                      Compliance.                                     where document begins].
 
                                                                      * * * * * * *
Section 117.149....................  Notification,                         12/13/02  09/06/06 [Insert FR page number
                                      Recordkeeping, and                              where document begins].
                                      Reporting Requirements.
 
                                                                      * * * * * * *
Section 117.203....................  Exemptions.................           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
Section 117.205....................  Emission Specifications for           12/13/02  09/06/06 [Insert FR page number
                                      Reasonably Available                            where document begins].
                                      Control Technology (RACT).

[[Page 52696]]

 
Section 117.206....................  Emission Specifications for           12/13/02  09/06/06 [Insert FR page number    The SIP does not
                                      Attainment Demonstration.                       where document begins].           include section 117.206(e).
Section 117.207....................  Alternative Plant-wide                12/13/02  09/06/06 [Insert FR page number
                                      Emission Specifications.                        where document begins].
 
                                                                      * * * * * * *
Section 117.213....................  Continuous Demonstration of           12/13/02  09/06/06 [Insert FR page number
                                      Compliance.                                     where document begins].
Section 117.214....................  Emission Testing and                  12/13/02  09/06/06 [Insert FR page number
                                      Monitoring for the Houston-                     where document begins].
                                      Galveston Attainment
                                      Demonstration.
Section 117.215....................  Final Control Plan                    12/13/02   09/06/06 [Insert FR page number
                                      Procedures for Reasonably                       where document begins].
                                      Available Control
                                      Technologies.
Section 117.216....................  Final Control Plan                    12/13/02  09/06/06 [Insert FR page number
                                      Procedures for Attainment                       where document begins].
                                      Demonstration Emission
                                      Specifications.
 
                                                                      * * * * * * *
Section 117.219....................  Notification,                         12/13/02  09/06/06 [Insert FR page number
                                      Recordkeeping, and                              where document begins].
                                      Reporting Requirements.
 
                                                                      * * * * * * *
Section 117.223....................  Source Cap.................           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Subchapter C--Acid Manufacturing
                                                          Division 1: ADIPIC Acid Manufacturing
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 117.301....................  Applicability..............           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
 
                                                                      * * * * * * *
Section 117.309....................  Control Plan Procedures....           12/13/02  09/06/06 [Insert FR page number
                                                                                      where document begins].
Section 117.311....................  Initial Demonstration of              12/13/02  09/06/06 [Insert FR page number
                                      Compliance.                                     where document begins].
Section 117.313....................  Continuous Demonstration of           12/13/02  09/06/06 [Insert FR page number    ................................
                                      Compliance.                                     where document begins].
Section 117.319....................  Notification,                         12/13/02  09/06/06 [Insert FR page number    ................................
                                      Recordkeeping, and                              where document begins].
                                      Reporting Requirements.
Section 117.321....................  Alternative Case Specific             12/13/02  09/06/06 [Insert FR page number
                                      Specifications.                                 where document begins].
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Division 2: Nitric Acid Manufacturing, Ozone Nonattainment Areas
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 117.401....................  Applicability..............           12/13/02  09/06/06 [Insert FR page number    ................................
                                                                                      where document begins].
 
                                                                      * * * * * * *
Section 117.409....................  Control Plan Procedures....           12/13/02  09/06/06 [Insert FR page number    ................................
                                                                                      where document begins].

[[Page 52697]]

 
Section 117.411....................  Initial Demonstration of              12/13/02  09/06/06 [Insert FR page number    ................................
                                      Compliance.                                     where document begins].
Section 117.413....................  Continuous Demonstration of           12/13/02  09/06/06 [Insert FR page number    ................................
                                      Compliance.                                     where document begins].
Section 117.419....................  Notification,                         12/13/02  09/06/06 [Insert FR page number    ................................
                                      Recordkeeping, and                              where document begins].
                                      Reporting Requirements.
Section 117.421....................  Alternative Case Specific             12/13/02  09/06/06 [Insert FR page number    ................................
                                      Specifications.                                 where document begins].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Subchapter D--Small Combustion Sources
                                              Division 1: Water Heaters, Small Boilers, and Process Heaters
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
Section 117.463....................  Exemptions.................           12/13/02  09/06/06 [Insert FR page number    ................................
                                                                                      where document begins].
Section 117.465....................  Emission Specifications....           12/13/02  09/06/06 [Insert FR page number    ................................
                                                                                      where document begins].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                             Division 2: Boilers, Process Heaters, and Stationary Engines and Gas Turbines at Minor Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 117.471....................  Applicability..............           09/26/01  11/14/01, 66 FR 57244............  New.
Section 117.473....................  Exemptions.................           12/13/02  09/06/06 [Insert FR page number    ................................
                                                                                      where document begins].
 
                                                                      * * * * * * *
Section 117.475....................  Emission Specifications....           12/13/02  09/06/06 [Insert FR page number    The SIP does not include section
                                                                                      where document begins].            117.475(i).
Section 117.478....................  Operating Requirements.....           12/13/02  09/06/06 [Insert FR page number    ................................
                                                                                      where document begins].
Section 117.479....................  Monitoring, Recordkeeping,            12/13/02  09/06/06 [InsertFR page number
                                      and Reporting Requirements.                     where document begins].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Subchapter E--Administrative Provisions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 117.510....................  Compliance Schedule for               12/13/02  09/06/06 [Insert FR page number    ................................
                                      Utility Electric                                where document begins].
                                      Generation in Ozone
                                      Nonattainment Areas.
Section 117.512....................  Compliance Schedule for               12/13/02  09/06/06 [Insert FR page number    ................................
                                      Utility Electric                                where document begins].
                                      Generation in East and
                                      Central Texas.
Section 117.520....................  Compliance Schedule for               12/13/02  09/06/06 [Insert FR page number    ................................
                                      Industrial, Commercial,                         where document begins].
                                      Institutional Combustion
                                      Sources in Ozone
                                      Nonattainment Areas.
Section 117.534....................  Compliance Schedule for               12/13/02  09/06/06 [Insert FR page number    ................................
                                      Boilers, Process Heaters,                       where document begins].
                                      Stationary Engines, and
                                      Gas Turbines at Minor
                                      Sources.

[[Page 52698]]

 
Section 117.570....................  Use of Emissions Credits              03/05/03  03/26/04, 69 FR 15686............
                                      for Compliance.
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *
    (e) * * *

                                  EPA Approved Nonregulatory Provisions and Quasi-Regulatory Measures in the Texas SIP
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        State
         Name of SIP provision           Applicable geographic or    submittal/          EPA approval date                       Comments
                                            nonattainment area     effective date
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
Attainment Demonstration for Houston/    Houston/Galveston, TX...        12/01/04  09/06/06 [Insert FR page       ......................................
 Galveston/Brazoria (HGB) One-hour                                                  number where document
 Ozone Nonattainment Area Adopting                                                  begins].
 Strategy Based on NOX and Point Source
 Highly-Reactive VOC Emission
 Reductions.
--------------------------------------------------------------------------------------------------------------------------------------------------------

[FR Doc. 06-7412 Filed 9-5-06; 8:45 am]
BILLING CODE 6560-50-P