52670 Federal Register / Vol. 71, No. 172 / Wednesday, September 6, 2006 / Rules and Regulations 

EPA-APPROVED REGULATIONS IN THE TEXAS SIP—Continued 

State citation Title/subject 

State 

approval/submittal 

date 

EPA approval date Explanation 

* * * * * * * 

Subchapter F: Standard Permits 

* * * * * * * 

Section 116.610 ............................... Applicability ...................................... 03/07/01 [Insert date of FR 

publication] [Insert 

FR page number 

where document 

begins].

The SIP does not include subsection 

116.610(d). 

* * * * * * * 

Section 116.615 ............................... General Conditions .......................... 03/07/01 [Insert date of FR 

publication] [Insert 

FR page number 

where document 

begins].

* * * * * * * 

[FR Doc. 06–7411 Filed 9–5–06; 8:45 am] 

BILLING CODE 6560–50–P 

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. 

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 


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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 

snyder.erik@epa.gov. 

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. 


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TABLE 1.—REVISED ELEMENTS OF THE HGB OZONE SIP BEING APPROVED BY EPA 

Element Date submitted to EPA Comments 

1-hour standard attainment demonstration 

revisions.

12/17/04 Please see our proposed action and technical support document for more information. 

Revised motor vehicle emissions budgets 

for 2007.

12/17/04 Revised budgets are 89.99 tpd for volatile organic compounds and 186.13 tpd for 

NOX. 

Reasonably available control measures 

demonstration.

12/17/04 Please see our proposed action and technical support document for more information. 

Revisions to satisfy the enforceable commitments contained int he previouisly 

approved SIP (November 14, 2001, 66 

FR 57160).

12/17/04 Please see our proposed action and technical support document for more information. 

Revisions to the industrial NOX rules 

which included several misceallaneous 

changes and the reduction in stringency from a nominal 90% to 80% control.

1/28/03 Revisions to 30 TAC Chapter 117, Sections 117.10, 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, 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 rules that drop 

three counties from the I/M program 

and make several misceallaneous 

changes.

10/6/04 Revisions to 30 TAC Chapter 114, Sections114.1, 114.2, 114.50, 114.52, and 

114.53. 

Repeal of the vehicle idling rule ............... 12/17/04 Repeal of 30 TAC Chapter 114, Sections 114.500, 114.502, 114.507, and 114.509. 

Repeal of the Small Spark Engine Operating Restrictions.11/16/04 Repeal of 30 TAC Chapter 114, Sections 114.452 and 114.459. 

Revisions to the voluntary mobile emissions program.12/17/04 Please see our proposed 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, 


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‘‘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 nonroutine 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 nonroutine 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 HighlyReactive 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 shortterm limit. 

Again, EPA recognizes that the 

approach of providing this partial 

exclusion for emissions above the shortterm 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. 


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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 


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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 


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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 midcourse 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 midcourse 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 onroad 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 


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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 onroad 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 GalvestonHouston 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 


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

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

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 

• 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

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 Severe17 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 


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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 onehour 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. 

§ 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 


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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-ofevidence, 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 


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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 


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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 twopronged 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 


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ppb) or 55 ppb (75 ppb–20 ppb) of peak 

ozone formation are not properly 

modeled, the challenge to the weight-ofevidence 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 topranked 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 


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(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 × 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 


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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 underpredict 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 shortterm 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 


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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 selfreported 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 underreported 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 nonroutine 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 nonroutine 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 


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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 (nonhighly 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 


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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 noninterference 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 


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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 heavyduty 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 onroad 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 


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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 traveldemand 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 


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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 


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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 


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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. 

■ 40 CFR part 52 is amended as follows: 

PART 52—[AMENDED] 

■ 1. The authority citation for part 52 

continues to read as follows: 

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

Subpart SS—Texas 

■ 2. Section 52.2270 is amended as 

follows: 

■ a. The table in paragraph (c) entitled 

‘‘EPA Approved Regulations in the 

Texas SIP’’ is amended as follows: 

■ 1. By revising entries for Sections 

114.1 and 114.2 under Chapter 114 (Reg 

4), Subchapter A. 

■ 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. 

■ 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. 

■ 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. 

■ 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. 

■ 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. 

■ 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. 

■ 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. 


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■ 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. 

■ 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: 

§ 52.2270 Identification of plan. 

* * * * * 

(c) * * * 

EPA-APPROVED REGULATIONS IN THE TEXAS SIP 

State citation Title/subject 

State 

approval/ 

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 Definitions.09/05/04 09/06/06 [Insert FR 

page number 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 Requirements.09/05/04 09/06/06 [Insert FR 

page number where 

document begins].

Subsection 

114.50(b)(2) is 

NOT part of the 

approved SIP. 

* * * * * * * 

Section 114.52 ................................. Early Participation Incentive Program.09/05/04 09/06/06 [Insert FR 

page number where 

document begins].

Section 114.53 ................................. Inspection and Maintenance Fees .. 09/05/04 09/06/06 [Insert FR 

page number where 

document begins].

Division 3: Early Action Compact Counties 

* * * * * * * 

Subchapter I—Non-Road Engines 

* * * * * * * 

Section 114.429 ............................... Affected Counties and Compliance 

Schedules.

12/06/00 11/14/01, 66 FR 

57222.

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 


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Federal Register / Vol. 71, No. 172 / Wednesday, September 6, 2006 / Rules and Regulations 52695 

EPA-APPROVED REGULATIONS IN THE TEXAS SIP—Continued 

State citation Title/subject 

State 

approval/ 

submittal 

date 

EPA approval date Explanation 

* * * * * * * 

Section 117.103 ............................... Exemptions ...................................... 09/26/01 114/14/01, 66 FR 

57244.

Section 117.105 ............................... Emission Specifications for Reasonably Available Control Technology 

(RACT).

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.106 ............................... Emission Specifications for Attainment Demonstrations.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

The SIP does not 

include section 

117.106(d). 

Section 117.107 ............................... Alternative System Emission Specifications.12/13/02 09/06/06 [Insert FR 

page number 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 Compliance.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.114 ............................... Emission Testing and Monitoring for 

the Houston-Galveston Attainment Demonstration.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.115 ............................... Final Control Plan Procedures for 

Reasonably Available Control 

Technologies.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.116 ............................... Final Control Plan Procedures for 

Attainment Demonstration Emission Specifications.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

Section 117.119 ............................... Notification, Recordkeeping, and 

Reporting Requirements.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

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 where 

document begins].

The SIP does not 

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 Compliance 12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.143 ............................... Continuous Demonstration of Compliance.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

Section 117.149 ............................... Notification, Recordkeeping, and 

Reporting Requirements.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

Section 117.203 ............................... Exemptions ...................................... 12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.205 ............................... Emission Specifications for Reasonably Available Control Technology 

(RACT).

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].


sroberts on PROD1PC70 with RULES
52696 Federal Register / Vol. 71, No. 172 / Wednesday, September 6, 2006 / Rules and Regulations 

EPA-APPROVED REGULATIONS IN THE TEXAS SIP—Continued 

State citation Title/subject 

State 

approval/ 

submittal 

date 

EPA approval date Explanation 

Section 117.206 ............................... Emission Specifications for Attainment Demonstration.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

The SIP does not 

include section 

117.206(e). 

Section 117.207 ............................... Alternative Plant-wide Emission 

Specifications.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

Section 117.213 ............................... Continuous Demonstration of Compliance.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.214 ............................... Emission Testing and Monitoring for 

the Houston-Galveston Attainment Demonstration.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.215 ............................... Final Control Plan Procedures for 

Reasonably Available Control 

Technologies.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.216 ............................... Final Control Plan Procedures for 

Attainment Demonstration Emission Specifications.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

Section 117.219 ............................... Notification, Recordkeeping, and 

Reporting Requirements.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

* * * * * * * 

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 Compliance 12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.313 ............................... Continuous Demonstration of Compliance.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.319 ............................... Notification, Recordkeeping, and 

Reporting Requirements.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.321 ............................... Alternative Case Specific Specifications.12/13/02 09/06/06 [Insert FR 

page number 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].


sroberts on PROD1PC70 with RULES
Federal Register / Vol. 71, No. 172 / Wednesday, September 6, 2006 / Rules and Regulations 52697 

EPA-APPROVED REGULATIONS IN THE TEXAS SIP—Continued 

State citation Title/subject 

State 

approval/ 

submittal 

date 

EPA approval date Explanation 

Section 117.411 ............................... Initial Demonstration of Compliance 12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.413 ............................... Continuous Demonstration of Compliance.12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.419 ............................... Notification, Recordkeeping, and 

Reporting Requirements.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.421 ............................... Alternative Case Specific Specifications.12/13/02 09/06/06 [Insert FR 

page number 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 where 

document begins].

The SIP does not include section 

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, and Reporting Requirements.12/13/02 09/06/06 [InsertFR 

page number where 

document begins].

* * * * * * * 

Subchapter E—Administrative Provisions 

Section 117.510 ............................... Compliance Schedule for Utility 

Electric Generation in Ozone 

Nonattainment Areas.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.512 ............................... Compliance Schedule for Utility 

Electric Generation in East and 

Central Texas.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.520 ............................... Compliance Schedule for Industrial, 

Commercial, Institutional Combustion Sources in Ozone Nonattainment Areas.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].

Section 117.534 ............................... Compliance Schedule for Boilers, 

Process Heaters, Stationary Engines, and Gas Turbines at Minor 

Sources.

12/13/02 09/06/06 [Insert FR 

page number where 

document begins].


sroberts on PROD1PC70 with RULES
52698 Federal Register / Vol. 71, No. 172 / Wednesday, September 6, 2006 / Rules and Regulations 

EPA-APPROVED REGULATIONS IN THE TEXAS SIP—Continued 

State citation Title/subject 

State 

approval/ 

submittal 

date 

EPA approval date Explanation 

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

15686.

* * * * * * * 

* * * * * (e) * * * 

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

Name of SIP provision 

Applicable geographic or nonattainment area State submittal/effective 

date 

EPA approval date Comments 

* * * * * * * 

Attainment Demonstration for Houston/Galveston/Brazoria (HGB) One-hour Ozone 

Nonattainment Area Adopting Strategy 

Based on NOX and Point Source HighlyReactive VOC Emission Reductions.

Houston/Galveston, 

TX.

12/01/04 09/06/06 [Insert FR page 

number where document 

begins].

[FR Doc. 06–7412 Filed 9–5–06; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R06–OAR–2005–TX–0006; FRL–8216–

3] 

Approval and Promulgation of State 

Implementation Plans; Texas; 

Emission Credit Banking and Trading 

Program 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: EPA is approving revisions to 

the Texas State Implementation Plan 

(SIP) concerning the Emission Credit 

Banking and Trading Program. 

Additionally, EPA is approving a 

section of Chapter 115 of the Texas 

Administrative Code (TAC) on Control 

of Air Pollution from Volatile Organic 

Compounds that cross-references the 

Emission Credit Banking and Trading 

Program and the Discrete Emission 

Credit Banking and Trading Program. 

We are also approving a subsection of 

Chapter 116 of the TAC, Control of Air 

Pollution by Permits for New 

Construction or Modification, which 

provides a definition referred to in both 

the Emission Credit and the Discrete 

Emission Credit Banking and Trading 

Programs. 

DATE: This rule is effective on October 

6, 2006. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

No. EPA–R06–OAR–2005–TX–0006. 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 Permitting Section (6PD–R), 

Environmental Protection Agency, 1445 

Ross Avenue, Suite 700, Dallas, Texas 

75202–2733. The file will be made 

available by appointment for public 

inspection in the Region 6 FOIA Review 

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

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

holidays. Contact the person listed in 

the FOR FURTHER INFORMATION CONTACT

paragraph below to make an 

appointment. If possible, please make 

the appointment at least two working 

days in advance of your visit. There will 

be a 15-cent per page fee for making 

photocopies of documents. On the day 

of the visit, please check in at the EPA 

Region 6 reception area at 1445 Ross 

Avenue, Suite 700, Dallas, Texas. 

The State submittal related to this SIP 

revision, and which is part of the EPA 

docket, 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: 

Adina Wiley, Air Permitting Section 

(6PD–R), EPA Region 6, 1445 Ross 

Avenue, Dallas, Texas 75202–2733, 

telephone 214–665–2115, 

wiley.adina@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document wherever 

‘‘we,’’ ‘‘us,’’ or ‘‘our’’ is used, we mean 

EPA. 

Outline 

I. What action is EPA taking? 

II. What is the background for this action? 

III. What are EPA’s responses to comments 

received on the proposed action? 

IV. What does Federal approval of a State 

regulation mean to me? 

V. Statutory and Executive Order Reviews 

I. What action is EPA taking? 

EPA is approving the Emission Credit 

Banking and Trading program, also 

referred to as the Emission Reduction 

Credit (ERC) program, enacted at Texas 

Administrative Code (TAC) Title 30, 

Chapter 101 General Air Quality Rules, 

Subchapter H Emissions Banking and 

Trading, Division 1, sections 101.300–

101.304, 101.306, 101.309, and 101.311. 

These sections were submitted as SIP 

submittals dated December 20, 2000 

(state effective date January 18, 2001); 


sroberts on PROD1PC70 with RULES