[Federal Register Volume 70, Number 192 (Wednesday, October 5, 2005)]
[Proposed Rules]
[Pages 58119-58138]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-19994]
[[Page 58119]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[R06-OAR-2005-TX-0018; FRL-7980-6]
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: Proposed rule.
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SUMMARY: EPA is proposing to approve revisions to the State
Implementation Plan (SIP) for the State of Texas as it applies to the
Houston/Galveston/Brazoria (HGB) Ozone nonattainment area. These plan
revisions result from more recent information on ozone formation in the
Houston/Galveston area indicating that a combination of controls on
oxides of Nitrogen (NOX) and highly reactive volatile
organic compounds (HRVOCs) should be more effective in reducing ozone
than the measures in the previously approved plan which relied almost
exclusively on control of NOX. Approval of these revisions
will incorporate these changes into the federally approved SIP.
DATES: Comments must be received on or before November 4, 2005.
ADDRESSES: Submit your comments, identified by Regional Material in
EDocket (RME) ID No. R06-OAR-2005-TX-0018, by one of the following
methods:
Federal eRulemaking Portal: http://www.regulations.gov.
Follow the on-line instructions for submitting comments.
Agency Web site: http://docket.epa.gov/rmepub/ Regional
Material in EDocket (RME), EPA's electronic public docket and comment
system, is EPA's preferred method for receiving comments. Once in the
system, select ``quick search,'' then key in the appropriate RME Docket
identification number. Follow the on-line instructions for submitting
comments.
U.S. EPA Region 6 ``Contact Us'' Web site: http://epa.gov/region6/r6coment.htm Please click on ``6PD'' (Multimedia) and select
``Air'' before submitting comments.
E-mail: Mr. Thomas Diggs at [email protected]. Please
also cc the person listed in the FOR FURTHER INFORMATION CONTACT
section below.
Fax: Mr. Thomas Diggs, Chief, Air Planning Section (6PD-
L), at fax number 214-665-7263.
Mail: Mr. Thomas Diggs, Chief, Air Planning Section (6PD-
L), Environmental Protection Agency, 1445 Ross Avenue, Suite 1200,
Dallas, Texas 75202-2733.
Hand or Courier Delivery: Mr. Thomas Diggs, Chief, Air
Planning Section (6PD-L), Environmental Protection Agency, 1445 Ross
Avenue, Suite 1200, Dallas, Texas 75202-2733. Such deliveries are
accepted only between the hours of 8 am and 4 pm weekdays except for
legal holidays. Special arrangements should be made for deliveries of
boxed information.
Instructions: Direct your comments to Regional Material in EDocket
(RME) ID No. R06-OAR-2005-ST-0018. EPA's policy is that all comments
received will be included in the public file without change, and may be
made available online at http://docket.epa.gov/rmepub/, including any
personal information provided, unless the comment includes information
claimed to be Confidential Business Information (CBI) or other
information the disclosure of which is restricted by statute. Do not
submit information through Regional Material in EDocket (RME),
regulations.gov, or e-mail if you believe that it is CBI or otherwise
protected from disclosure. The EPA RME website and the Federal
regulations.gov are ``anonymous access'' systems, which means EPA will
not know your identity or contact information unless you provide it in
the body of your comment. If you send an e-mail comment directly to EPA
without going through RME or regulations.gov, your e-mail address will
be automatically captured and included as part of the comment that is
placed in the public file and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses.
Docket: All documents in the electronic docket are listed in the
Regional Material in EDocket (RME) index at http://docket.epa.gov/rmepub/. Although listed in the index, some information is not publicly
available, i.e., 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 in RME or in the official file which is
available 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 am and 4:30 pm
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 of the visit, please check in at the EPA Region 6 reception
area at 1445 Ross Avenue, Suite 700, Dallas, Texas.
The State submittal 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: Guy R. Donaldson, Air Planning Section
(6PD-L), Environmental Protection Agency, Region 6, 1445 Ross Avenue,
Suite 700, Dallas, Texas 75202-2733, telephone (214) 665-7242 fax
number 214-665-7263; e-mail address [email protected].
SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us,'' or ``our'' is used, we mean the EPA.
Table of Contents
I. Background
A. What Are the Actions Being Proposed Here?
B. Why Control Ozone?
C. What Does the Currently Approved SIP for HGB Contain?
D. What Revisions to State Implementation Plan Are Being
Considered Here?
E. What General Criteria Must These Revisions Meet To Be
Approvable?
II. Evaluation
A. One Hour Attainment Demonstration
1. What Modeling Approaches Were Used for This Attainment
Demonstration?
2. What Is a Photochemical Grid Model?
3. What Episode Did Texas Choose To Model?
4. How Well Did the Model perform?
5. What Did the Results of Modeling Routine Emissions Show?
6. What Did the Results of the Emission Event Modeling Show?
7. How Did Texas Handle Questions About Emission Estimates?
8. What Actions Are Being Taken To Improve Emissions Estimates
of HRVOCs?
9. What About Estimates of Less-Reactive VOC Emissions?
[[Page 58120]]
10. What Additional Evidence Did Texas Provide?
11. Is the One-Hour Attainment Demonstration Approvable?
B. New Control Measures
1. What Are the New Control Measures in these SIP revisions?
2. What Are the Annual Cap and Short-Term Limit on HRVOC
Emissions?
3. How Are Annual Cap and Short-Term Limits Related?
4. Can Reductions in Less-Reactive VOCs Be Made Instead of
Reductions in HRVOCs?
5. What Estimates of Flare Efficiency Are Made in the SIP
Revision?
6. How Has the Texas Leak Detection and Repair Program Been
Strengthened?
7. How Have the Benefits of the Leak Detection and Repair
Program Been Projected?
8. What Are the Requirements for Portable Gasoline Containers?
C. Revised Control Measures
1. What Control Measures Have Been Revised or Repealed?
D. Reasonably Available Control Measures
1. What Are the RACM Requirements?
2. How Has Texas Insured With This Plan Revision That all RACM
are Being Implemented?
E. Section 110(l) Analysis
1. What Does Section 110(l) Require?
2. How Has Texas Shown These Revisions Do Not Interfere With
Attainment of the 8-Hour Standard?
3. What About Possible Interference With the 1-Hour Ozone
Standard?
4. How Has Texas Shown These Revisions do not Interfere With
Rate of Progress?
5. Do These Revisions Interfere With Attainment of other
Standards Besides Ozone?
6. Do the Revisions Interfere With any Other Applicable
Requirements of the Act?
F. Enforceable Commitments
1. What Is an Enforceable Commitment?
2. What Were the Enforceable Commitments in the 2001 Approved
SIP and Have They Been Fulfilled?
G. Motor Vehicle Emissions Budgets
1. What Is a Motor Vehicle Emissions Budget and Why Is it
Important?
2. What Are the Motor Vehicle Emissions Budgets Being Proposed
for Approval?
III. Statutory and Executive Order Reviews
I. Background
A. What Are the Actions Being Proposed Here?
EPA is proposing to approve the following revisions to the approved
1-hour ozone attainment plan for the HGB area:
TCEQ's revised demonstration, submitted December 2004,
that the 1-hour ozone standard will be achieved in 2007.
The revised motor vehicle emissions budgets associated
with the revised attainment demonstration.
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 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 are as effective in reducing ozone levels.
Revisions to the industrial NOX rules submitted
January 2003, which included several miscellaneous changes and the
reduction in stringency from a nominal 90% to 80% control.
Revisions to the Texas Inspection and Maintenance (I/M)
rules that drop three counties from the I/M program. In addition,
several miscellaneous changes are proposed for approval.
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
(VMEP).
To replace the above measures being repealed or relaxed, Texas has
adopted the following new control measures:
Annual Cap on HRVOC emissions.
Hourly (short-term) limit on HRVOC emissions.
Improved requirements for HRVOC fugitive emissions.
Requirements for Portable Gasoline containers.
Separately, EPA has proposed or is proposing to approve the newly
adopted measures. Comments on the proposed approval of the new control
measures should be directed to these separate Federal Register actions.
The actions addressed in this rulemaking in conjunction with the new
HRVOC rules, if approved, will provide for timely attainment as
demonstrated through the modeling analysis. In addition, 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 this Act. (Section 110(l)
demonstration).
B. Why Control Ozone?
Inhaling even low levels of ozone can trigger a variety of health
problems including chest pains, coughing, nausea, throat irritation,
and congestion. It can also worsen bronchitis and asthma and reduce
lung capacity. EPA has established National Ambient Air Quality
Standards (NAAQS) for ozone. The standard of 0.12 ppm averaged over a
1-hour period was adopted in 1979. In July 1997, EPA adopted a revised
standard of 0.08 ppm averaged over an 8-hour period. In the Phase I
Implementation Rule (April 30, 2005, 69 FR 23951) for the 8-hour
standard, EPA provided for revocation of the 1-hour standard for most
areas including HGB on June 15, 2005. Also, EPA established anti-
backsliding provisions to insure that areas maintain the progress
expected under the requirements of the 1-hour standard as areas
transition to developing programs to meet the 8-hour standard.
C. What Does the Currently Approved SIP for HGB Contain?
On November 14, 2001, EPA approved the 1-hour ozone attainment plan
for the HGB nonattainment area. This plan relied primarily on
reductions in emissions of NOX to project attainment. The
plan included a wide variety of controls on NOX emissions
including an approximately 90% reduction in industrial NOX
emissions, vehicle inspection and maintenance in eight counties, and
the Texas Emission Reduction Program (TERP). The plan, however, did not
contain sufficient adopted control measures as needed to demonstrate
attainment. Because the State had adopted NOX measures more
stringent than any where else in the country and was unable to identify
specific NOX measures by which to achieve all of the needed
emission reductions, the State included an enforceable commitment to
adopt rules to achieve the 56 tpd of additional emission reductions
which were necessary to demonstrate attainment. The additional measures
were to be adopted in two phases; measures to achieve 25% of the needed
reductions were to be adopted by December 2002 with measures to achieve
the remaining emission reductions to be adopted by May 2004. In
addition, Texas committed to perform a mid-course review, evaluating
the modeling, inventory data and other tools and assumptions used to
develop the plan and make adjustments to the plan to provide for timely
and cost effective attainment. If, based on the mid-course review, more
or fewer NOX reductions were necessary, Texas committed to
provide the revised analysis to EPA for review.
Texas, however, was sued in State court on its plan for the Houston
area. The litigants alleged that the controls on industrial
NOX emissions of approximately 90% would not be effective
and that instead the State should be controlling releases of HRVOCs.
Texas entered into a settlement agreement with the litigants whereby
one facet of the mid-course
[[Page 58121]]
review was accelerated to determine if the point source NOX
controls could be relaxed and replaced with controls on HRVOCs. This
study and any consequent rule changes were to be completed by December
2002.
D. What Revisions to the State Implementation Plan Are Being Considered
Here?
The following submissions which impact the HGB attainment plan are
being considered :
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 relaxed and controls on
HRVOCs could be substituted. Based on the study, the commission adopted
relaxed controls on NOX emissions from industrial sources
and 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 TERP emission reductions would be sufficient to
achieve the 25% of the NOX reductions needed to demonstrate
attainment (i.e., about 14 tpd).
October 16, 2003: This submission delayed compliance for the I/M
program in Chambers, Liberty and Waller Counties. (RME R06-OAR-2005-TX-
0035)
October 6, 2004: This submission repealed the I/M program in
Chambers, Liberty and Waller Counties.(RME 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 was submitted to meet 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 (Docket R06-
OAR-2005-TX-0013), the speed limit strategy, the voluntary mobile
emissions program (VMEP) and the commitment to achieve NOX
reductions reductions beyond the initial 25% provided in January 2003
(i.e., revoked the State's commitment to achieve 42 tpd of the
NOX reductions that were included in the enforceable
commitment as part of the prior attainment demonstration).
E. What General Criteria Must These Revisions Meet To Be Approvable?
To be approved, the revisions to the attainment demonstration must
meet several requirements. First, the State submission must demonstrate
that the revised plan, as a whole, will result in attainment of the 1-
hour as expeditiously as practicable but no later than 2007. This is
necessary, even though the 1-hour standard was revoked on June 15,
2005, because the approved SIP commits the State to adopt 56 tons/day
of additional NOX reductions unless, based on the mid-course
review analysis, the area can show attainment of the 1-hour standard by
2007 with a different mix of emission reductions.\1\ In Section II.A.
we discuss TCEQ's revised 1-hour attainment demonstration. Second, the
measures in the revised control strategy must meet the requirements for
being creditable under the Clean Air Act and must be permanent,
surplus, quantifiable and enforceable and achieve the necessary amount
of reductions. The new and revised measures are discussed in Section
II.B. and II.C. Some of these control measures have been or are being
reviewed in separately proposed rules. Before the revisions to the
attainment plan can be finally approved, all of the control measures
relied on in the attainment plan must also be approved. Third, the
State must show that the revised control strategy includes all
reasonably available control measures (RACM). This showing is discussed
in Section II.D. Fourth, the State must show, as required by section
110(l) of the Clean Air Act, that the revisions to the plan will not
interfere with attainment or reasonable further progress or any other
applicable requirement of the Act. Compliance with 110(l) is discussed
in Section II.E. Finally, the State must show that it has met all of
the enforceable commitments contained in the approved SIP. (Instead of
meeting the enforceable commitment to achieve the remaining 42 tpd
NOX reductions, the State has adopted controls on HRVOCs and
submitted modeling to demonstrate that the 42 tons/day of
NOX reductions is not necessary for the HGB area to attain
by November 2007.) Enforceable commitments are discussed in Section
II.F.
II. Evaluation
A. One Hour Attainment Demonstration
1. What Modeling Approaches Were Used for This 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 by 2007. Also, as allowed 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.
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\1\ In addition, EPA has retained the 1-hour attainment
demonstration requirement as an applicable requirement under the
Phase I rules antibacksliding provisions. See 40 CFR 51.900(f).
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The SIP revision actually relies on two sets of modeling analyses.
First, the SIP 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 to 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, ``Variable Industrial VOC Emissions and Their Impact on Ozone
Formation in the Houston Galveston Area,'' April 16, 2004. This second
modeling effort was used to estimate the impact of non-routine emission
events on ozone levels. This two pronged approach is consistent with
observations that indicate that Houston's air quality problems stem
from the combination of two phenomena, normal routine emissions and
large non-routine releases of HRVOC emissions. For a more complete
description of the modeling procedures and EPA's evaluation of these
procedures, see the Technical Support Document (TSD) in the Docket for
this action (RO6-OAR-2005-TX-0018).
2. What Is a Photochemical Grid Model?
Photochemical grid models are the state-of-the-art method for
predicting the effectiveness of control strategies in reducing ozone
levels. The model uses a three-dimensional grid to represent conditions
in the area of interest. In this case, TCEQ has developed a grid system
that stretches from beyond Austin to the west, to Georgia to the east,
to Nebraska to the north and into the Gulf of Mexico to the south. The
model uses nested grid cells of 36 km on the outer portions, 12 km in
east Texas and portions of nearby States and a 4 kilometer grid cell
covering the HGB and Beaumont Port Arthur (BPA) areas. For more
information on the modeling domain, please see the TSD. The model
simulates the movement of air and emissions into and out of the three-
dimensional grid cells (advection and
[[Page 58122]]
dispersion); mixes pollutants upward and downward among layers; injects
new emissions from sources such as point, area, mobile (both on-road
and nonroad), and biogenic into each cell; and uses chemical reaction
equations to calculate ozone concentrations based on the concentration
of ozone precursors and incoming solar radiation within each cell.
Air quality planners choose an historical episode of high ozone
levels to apply the model. Running the model requires large amounts of
data inputs regarding the emissions and meteorological conditions
during an episode. Modeling to duplicate conditions during an
historical episode is referred to as the base case modeling and is used
to verify that the model system can predict the historical ozone levels
with an acceptable degree of accuracy. If the model can predict the
ozone levels in the base case, it can then be used to project the
response of future ozone levels to proposed emission control
strategies.
3. What Episode Did Texas Choose To Model?
Texas chose an historical episode, August 19-September 6, 2000,
that encompassed the time period of the Texas Air Quality Study (TxAQS)
2000. During this study, researchers from around the country
participated in an intensive study of ozone formation in the HGB area,
collecting additional meteorological and chemical data. This study has
provided a wealth of information to test the assumptions in the model.
EPA believes that the extended episode from August 19-September 6,
2000, is an acceptable episode for development of the 1-hour attainment
plan. It encompasses 13 exceedance days and contains a variety of
meteorological conditions which resulted in high concentrations of
ozone in the area as measured on both a 1-hour and 8-hour basis.
4. How Well did the Model Perform?
Model performance is a term used to describe how well the model
predicts the ozone levels in an historical episode. As models have to
make numerous simplifying assumptions and the system being modeled is
very complex, model predictions will never be perfect. EPA has
developed various diagnostic, statistical and graphical analyses that
TCEQ has performed to evaluate the model's performance and determine if
the model is working adequately to test control strategies. For a
subset of days, August 25, 26, 29, 30, 31, September 1-4 and 6, TCEQ
deemed the model's performance adequate for control strategy
development to address routine emissions. EPA agrees that the overall
model performance is adequate but notes that the model tends to under-
predict on high days and over-predict on low days raising some
uncertainty in the control strategy modeling. At least part of the
under prediction has been attributed to non-routine emissions not
captured in the modeling. This is discussed further in the section on
alternative design values. It is also worth noting that, to achieve
adequate performance, TCEQ adjusted the amount of HRVOC emissions in
the model above the reported emission inventory values based on ambient
measurements which demonstrated that reported HRVOC emissions were
underestimated. This adjustment is discussed in more detail in later
sections.
5. What Did the Results of the Modeling of Routine Emissions Show?
The results of modeling the revised control strategy are shown in
Table 1.
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Modeled peak
Episode day Measured peak Modeled peak (future case
(base case) \2\)
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August 25................................................ 194 156.5 121.6
August 26................................................ 140 149.4 113.6
August 29................................................ 146.7 151.2 113.6
August 30................................................ 200.5 137.2 122.5
August 31................................................ 175.5 173.0 147.6
September 1.............................................. 163.7 136.7 119.5
September 2.............................................. 125.5 152.7 128.6
September 3.............................................. 127.2 139.3 115.0
September 4.............................................. 145.0 158.0 125.2
September 6.............................................. 156.0 152.9 125.1
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Table 1 shows that on all of the days except August 31, the modeled
control strategy was predicted to bring the area under or very near the
one-hour standard of 125 ppb. The modeling, however, incorporates only
routine emissions in the future case and reported non-routine emissions
in the base case. As will be discussed in more detail in later
sections, TCEQ believes that large non-routine emission events not
included in the modeling also contribute to high ozone levels in the
HGB area. These non-routine emission events explain, in part, the
model's under-prediction on several days such as August 25th, 30th, and
September 1st.
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\2\ These values also do not include the impact of wildfires as
discussed in the WOE section.
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As discussed in the weight of evidence section regarding
alternative design values, the TCEQ believes that without the influence
of emission events, an alternative design value of 144 ppb can be
estimated. If 144 ppb is a reasonable representation of the area's
ozone levels due to routine emissions, then the modeling results in
Table 1 indicate sufficient reductions in ozone levels due to routine
events. In addition to the modeling results and the alternative design
value approach which is explained later in this notice, TCEQ has
presented other evidence to demonstrate that attainment will be
reached. These additional demonstrations are included in the weight of
evidence section.
To address the part of the ozone levels due to non-routine
emissions, TCEQ established a short term limit of 1200 lb/hr on
emissions of HRVOCs. The development of this limit is discussed in the
next section on emission event modeling. The purpose of this limit is
to reduce the frequency of non-routine emission events sufficiently so
that emission events impacting peak ozone levels will be reduced in
frequency to less than 1 event per year and thus will not impact
attainment of the 1-hour standard.
We recognize that there is considerable uncertainty regarding the
impact of emission events on peak ozone. As we discuss in the next
section on emission event modeling, the project H13 study seems to
indicate a smaller impact of emission events on peak ozone levels than
the alternative design value approach. The projected smaller
[[Page 58123]]
impact could stem from the following reasons. First, the H13 study
looked at the impact of emission releases after the institution of
NOX controls, whereas the alternative design value analysis
performed by TCEQ is based on historic data before the institution of
controls. Thus, the impact of emission events in the past is likely to
be larger than events in the future when there is less NOX
with which to react. Second, the frequency of events was based only on
detected and reported events. Past monitoring and reporting techniques
may not have detected all events. The improved HRVOC reporting rules
should help address this possible problem. Finally, project H13's
assumptions regarding the frequency of events looked only at events
occurring at the most sensitive times and location. Larger events
occurring at slightly less sensitive times and locations could also be
impacting peak ozone. On the other hand, it is likely that the
alternative design value approach overstates the impact of emission
events. Some of the rapid rises in monitored ozone that are filtered
out in the alternative design value approach could be caused by narrow
continuous plumes of ozone sweeping across a monitor as winds shift
direction. Weighing the available information, EPA believes that the
occurrence of emission events in the HGB area that are not included in
the model contribute at least in part to the model's under prediction
of some measured ozone levels. The short-term limit will address these
non-routine emission events. In addition, the controls on routine
emissions will provide the reductions in the ozone due to routine
emissions necessary to reach attainment. In addition, Texas has
considered other weight of evidence information indicating there will
be more improvement in air quality than can be expected demonstrated by
the modeling of routine emissions.
6. What Did the Results of the Emission Event Modeling Show?
Traditionally ozone control plans have been based on the assumption
that emissions for an area do not change significantly from day to day
and differences in pollution levels are caused by changes in the
meteorological conditions between days. This assumption has been
reexamined for the Houston area because of the number of non-routine
emissions that are reported in the Houston area from the refining and
petrochemical industry.
The project H13 report, ``Variable Industrial VOC Emissions and
Their Impact on Ozone Formation in the Houston Galveston Area,'' April
16, 2004, looked at the potential impact of emission releases in the
area. It determined, by examining the TCEQ emission events data base
and records of emissions from sources with monitors on flares and
cooling towers, that ``variability in HRVOC emissions from point
sources is significant and due to both variability in continuous
emissions and discrete emission events.'' The area wide variability had
the following characteristics:2-3 times per month HRVOC emissions
variability > 10,000 lbs/hour,2-3 times per month HRVOC emissions
variability 5,000-10,000 lbs/hour, daily HRVOC emissions variability >
100 lbs/hour.
Based on the above findings, the researchers then examined the
impact that emissions variability could have on peak ozone levels by
modeling the impact of emission events of various sizes at various
locations and times. It was determined that an event of 1,000 lbs in
the most sensitive area and during the most sensitive time could have a
1-2 ppb impact on the peak ozone level within the fine grid modeling
domain. Larger events would have correspondingly larger impacts on
ozone levels. A 10,000 lb release at the most sensitive place could
have a 10-20 ppb impact on ozone levels.
The study, based on assumptions regarding the frequency of ozone
conducive weather conditions, the time window most sensitive to
releases and the location of most sensitive releases, presented the
results of a Monte Carlo simulation to estimate the probability and
expected magnitude of emission events that would impact peak ozone
levels. The report states that if no actions were taken to reduce
emissions variability, an air quality plan should anticipate that at
least one event per year of 1,000 lbs would happen at the right time
and the right place to impact peak ozone. Based on this finding, TCEQ
adopted a short-term limit on HRVOC emissions designed to reduce the
magnitude and frequency of emissions events. This is not to say that a
1-2 ppb increase in ozone is not significant, but that with the short
term limit, the occurrence of non-routine events at the times and
places to impact peak ozone will be diminished sufficiently as not to
impact attainment with the 1-hour ozone standard. Because facilities
would be expected to take action to avoid events of 1,200 lbs/hr, the
frequency of such events in the future will be lower than in the past
and therefore less than 1 event per year impacting peak ozone should be
expected. As discussed, some non-routine emissions, in the past, may
not have been detected or reported in which case the actual frequency
of events impacting peak ozone levels may be higher than projected in
project H13, which as discussed previously, would help explain the
under-prediction in the routine modeling. The improved monitoring
requirements in chapter 115 should serve to prevent undetected HRVOC
releases in the future and the specter of enforcement will cause
facilities to take measures to prevent emission events. This is further
discussed in the section on the short term and long term cap.
7. How Did Texas Handle Questions About Emission Estimates?
TCEQ has followed acceptable procedures for the development of the
base case inventory, following or building upon EPA guidance. Despite
these efforts, one of the findings of the TexAQS 2000 study was that
observed concentrations of certain compounds, especially light olefins
such as ethylene and propylene, were much larger than represented in
the reported emission inventory. This conclusion has been reviewed and
documented in numerous scientific journals. For more information on
these studies see the TSD.
Emissions of these compounds principally come from the
petrochemical industry. While it is clear that the reported emissions
are too low, the ambient data does not show, however, which types of
facilities and equipment are the source of the underestimated
emissions. Various methods have been attempted to estimate the actual
emissions of VOCs in the HGB area based on the available ambient
measurements. TCEQ decided to use data from aircraft flights which
indicated NOX emissions were similar to VOC emissions when
considered on a molar basis. Therefore, TCEQ adjusted the molar
emission rate of HRVOC emissions at each facility to match the
NOX emission rate. This adjustment is more fully described
in Chapter 3 of the SIP revision. The adjustment had the effect of
substantially increasing the level of HRVOC emissions in the modeled
emissions inventory. Prior to adjusting the inventory, the model did
not perform well. Model performance was improved after the adjustment.
The adjusted inventory became the basis for achieving acceptable model
performance and for the control strategy development.
Clearly, this type of across-the-board adjustment of emissions is
not the preferable way to estimate emissions and makes control strategy
targeting and development difficult. Unfortunately, using established
methods for estimating source emissions has been
[[Page 58124]]
demonstrated to be inaccurate. As support for their adjustment
approach, TCEQ points out the amount of emissions added to the
inventory is corroborated by a study conducted by Environ ATop Down
Evaluation of the Houston Emissions Inventory Using Inverse Modeling''
(Yarwood et al., 2003) which indicated that approximately the right
amount of reactivity had been added to the model and that further
adjustment was not warranted under the then-current model formulation.
EPA believes that the approach Texas has taken to estimate the
inventory of HRVOCs is acceptable given the information that is
available. This conclusion is supported by the available aircraft data
and Environ inverse modeling study. Clearly, this is an area that
should be improved as the State develops future SIP revisions.
8. What Actions Are Being Taken To Improve the Emissions Estimates of
HRVOCs?
It was the consensus at a conference of emissions inventory experts
held in Clear Lake, Texas in 2001, that the errors in the inventory
were most likely from errors in the estimates of emissions from cooling
towers, flares, fugitive emissions and start-up, shutdown and
malfunction events. Texas has moved forward to improve the inventory of
HRVOCs in all of these areas by requiring monitoring of cooling towers,
flares, pressure relief devices and process vents in HRVOC service.
This source monitoring, which will be in place by the end of 2006,
should dramatically reduce the amount of error in the HRVOC inventory
by more directly measuring both continuous emissions and emissions
events. In addition, for all VOCs, Texas is now requiring that
correlation equations be used for the estimation of fugitive emissions.
This will reduce the amount of error in fugitive emission estimates.
9. What About Estimates of Less-Reactive VOC Emissions?
Texas elected to adjust the reported emission rates of only HRVOCs.
Other less-reactive chemicals are also released from flares, cooling
towers, fugitive sources and during start up/shutdown and malfunction
events and traditional emissions estimation techniques for less-
reactive VOCs are the same as those for HRVOC. Thus, it is reasonable
to suspect that these chemicals are also under-represented in the
inventory. If these chemicals are under-represented in the inventory,
the degree of underestimation may be less than for HRVOCs. One reason
is that the processes that emit HRVOCs, such as ethylene plants, are
often under very high pressures and this may increase the degree of
underestimation more than would occur for emissions in lower pressure
processes as one would expect leaks under higher pressures would tend
to release a greater mass of emissions than lower pressure leaks. Also,
many less-reactive VOCs are much lower in volatility than the HRVOCs
which could also serve to reduce the amount of emissions
underestimation.
There is some evidence from ambient measurements that the less-
reactive chemicals are underestimated in the emission inventory, but
there are not yet the number of peer reviewed studies regarding these
other VOCs that exist for HRVOCs making determination of appropriate
adjustment factors problematic. Therefore, Texas chose not to adjust
the reported inventory for the less-reactiveVOCs for the attainment
demonstration modeling because of the lack of information regarding the
appropriate level of emissions. TCEQ did conduct a study of ambient
data, referred to in the SIP revision, indicating that emissions might
be underestimated by a factor of 4.8. Based on this study, Texas
performed a sensitivity run with the model to evaluate the impact
potential errors in less-reactive VOC emissions might have on projected
attainment. This sensitivity analysis indicated that the addition of
less-reactive VOCs using a factor of 4.8 could have an impact of 2-29
ppb on the peak ozone depending on the day. The performance of the
model, however, was slightly worsened by the addition of the less-
reactive VOCs indicating that possibly too much reactivity had been
added. Other analyses performed by the University of North Carolina
(Role of Modeling Assumptions in Mid-Course Review, HARC 12.2004.8HRB,
2005) adjusting only fugitive emissions of less-reactive VOCs by lower
factors indicated no more than a 0.5 ppb increase in ozone levels. The
main differences between the analyses were the assumptions regarding
the amount of additional less-reactive VOCs and the amount of HRVOCs in
the model.
EPA is proposing to accept the attainment demonstration based on
TCEQ's approach to less reactive VOCs, because of the uncertainty on
what adjustments might be appropriate and what impact those adjustments
might have on the model. We understand that TCEQ is continuing to
evaluate ambient data to determine what adjustments to the inventory
might be appropriate. Texas has also undertaken a stakeholder process
to identify additional ways to improve the emissions inventory. This
stakeholder process will be vital to the improvement of future SIP
revisions. EPA expects that future SIPs revisions will be based on
improved emissions inventories of both less-reactive VOCs and HRVOCs.
We note that the move to require the correlation equations for the
estimation of less-reactive VOC will serve to improve the estimate of
fugitive emissions. Improvements to the emission estimates for cooling
towers and flares in less reactive VOC service should also be
considered. Roles should also be found for emerging remote sensing
technologies that have been shown to detect leaks from sources which
have not been traditionally considered such as barge hatches and
fittings on floating roof storage tanks.
10. What Additional Evidence Did Texas Provide?
The EPA's 1996 guidance entitled ``Guidance on Use of Modeled
Results to Demonstrate Attainment of the Ozone NAAQS'' allows for the
use of alternative analyses, called weight-of-evidence (WOE), to
provide additional evidence that the proposed control strategy,
although not modeling attainment, is nonetheless expected to achieve
attainment by the attainment date. More specifically, the intent of
this guidance was to be cognizant of the ozone NAAQS, which allows for
the occurrence of some exceedances and to consider potential
uncertainty in the modeling system. Thus, even though the specific
control strategy modeling may predict some areas to be above the NAAQS,
this does not necessarily mean that with the implementation of the
control strategy, monitored attainment will not be achieved. As with
other predictive tools, there are inherent uncertainties associated
with modeling and its results. For example, there are uncertainties in
the meteorological and emissions inputs and in the methodology used to
assess the severity of an exceedance at individual sites. The EPA's
guidance recognizes these limitations, and provides a means for
considering other evidence to help assess whether attainment of the
NAAQS is likely.
Since the future control case modeling in the Texas SIP revision
predicts some areas still exceeding the ozone NAAQS, the TCEQ elected
to supplement the control strategy modeling with WOE analyses. Texas
submitted the following analysis as WOE: August 31st rare meteorology;
additional reductions that were not modeled; comprehensive ozone
metrics and ambient trends; alternative design value and addressing
short-term excursions; and unusual wildfire
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activity. Each of these is discussed below.
August 31st Rare Meteorology
A combination of unusual meteorological conditions, extremely high
temperatures and winds from the west, occurred on August 31, 2005. The
record high temperatures recorded during the August 30-September 5,
2000 period, with several days of maximum temperature >=104[deg]F
(40[deg]C), have occurred in this geographic area only once before in
the previous 57 years. On August 31st, the Houston Intercontinental
Airport observed its highest temperature ever recorded in the month of
August. High temperatures throughout the region led to higher than
normal estimated biogenic emissions as the calculation of biogenic
emissions is a strong function of temperature. Texas calculated that
biogenic emissions within the HGB area were approximately 400 tons/day
higher on August 31st than on August 25th which had more moderate
temperatures. The elevated biogenic emissions in rural areas west of
Houston were also high and, because of somewhat atypical winds from the
west, available for transport into HGB. Texas used the source
apportionment tool (OSAT) to analyze the contributing emissions to high
ozone. The OSAT tool indicated that on the 31st, 78 ppb of the peak
ozone could be attributed to biogenics as compared to 24 ppb that could
be attributed to biogenics on the 25th. Other days of the episode also
had high temperatures but only when combined with the west winds did
the unusual impact of biogenics result. Texas points out that winds
from the west are not typical of the days that have high ozone in
Houston which usually occur on days with a flow reversal due to the
land sea breeze effect.
EPA agrees that the meteorological conditions on August 31st, which
combined record high temperatures and winds from the west, were not
typical of the conditions that lead to high ozone in the HGB area. The
higher than normal biogenic emissions and winds from the west appear to
have caused the 31st to be a day that did not respond well to the
adopted control strategy which is weighted toward control of point
sources that are predominant in eastern Harris County. This strategy
has been effective in reducing ozone levels on other days of the
episode. On the 31st, it appears much of the elevated ozone resulted
from the increased biogenic emissions mixing with the NOX
emissions present in the western portion of the HGB area. In this
portion of the area, NOX emissions are primarily from on-
and off-road mobile sources. To control ozone levels on days with
routine conditions similar to August 31st would require substantial
additional controls on mobile and area sources beyond the levels in the
current strategy. But because the conditions on the 31st are atypical,
we believe the HGB area can attain and a shift in strategy is not
warranted.
EPA's rules at 40 CFR 50, Appendix I permit the Regional
Administrator to exclude values caused by stratospheric ozone intrusion
or natural events in determining whether a NAAQS has been exceeded or
violated. Additionally, EPA's long-standing policy and guidance on the
handling of air quality data affected by exceptional or natural events
permits special consideration to be given to recorded air quality
measurements that are affected by unusual events under certain
circumstances. See, e.g., ``Guidance on the Identification and Use of
Air Quality Data Affected by Exceptional Events (July 1986)''. However,
this guidance and other guidance distinguish between those types of
events which directly produce emissions of a pollutant or its
precursors and meteorological conditions that may affect concentrations
of a pollutant emitted by sources. In particular, EPA guidance provides
that no consideration is given in determining whether the NAAQS are
exceeded or violated for such things as inversions, stagnation of air
masses, high temperatures or lack of rainfall. This language has
recently been codified in an amendment to section 319 of the Clean Air
Act by P.L. 109-59 [SAFETEA]. However, a reasonable distinction may be
drawn between the determination of whether NAAQS are exceeded or
violated during times when such meteorological conditions exist and the
meteorological and emissions data sets used in prospective
demonstrations of attainment. In the latter, our policy has been for
States to examine the typical conditions that lead to high ozone when
modeling to determine whether their control strategies are sufficient
to provide for attainment and maintenance of NAAQS. (U.S. EPA, (1996),
``Guidance on Use of Modeled Results to Demonstrate Attainment of the
Ozone NAAQS'', EPA-454/B-95-007.) In this case, the combination of
conditions on the 31st are not typical and, in fact are quite rare.
Therefore, EPA does not believe a shift in control strategy is
warranted to address the unusual conditions on August 31st that are
expected to occur so infrequently as to be unlikely to impact the
area's ability to attain the NAAQS.
Additional Reductions Not Modeled
The TCEQ believes potential additional emissions reductions will
take place as a result of programs which have been and will be
implemented in the HGB area but which are not reflected in the
modeling. These reductions are not included in the modeling because, at
present, these reductions are not quantifiable. Emission reductions
that were not included in the model should improve the probability of
HGB achieving attainment of the ozone NAAQS. First, as industries
improve their monitoring capabilities and reduce their HRVOC emissions,
the TCEQ anticipates collateral reductions of other VOCs that are
present in HRVOC streams. For instance, the TCEQ developed regulations
requiring owner/operator of flares in HRVOC service to install flow-
meters and comply with maximum tip velocity and minimum heat content
requirements to ensure proper combustion by the flare. The tip velocity
and heat content requirements apply at all times, not only when the
flare is combusting HRVOC streams. Because many of these flares are
also used for non-HRVOC streams, the regulations will often result in a
reduction of less-reactive VOCs as well. Similarly, TCEQ has improved
the leak detection and repair program for streams with more than 5%
HRVOC content. When leaks from streams containing both HRVOCs and less
reactive VOCs are repaired, other less-reactive VOCs will also be
reduced. EPA agrees that these collateral reductions are likely to
occur, but we believe the potential benefit of these unmodeled emission
reductions has been partially lost because TCEQ allows emission
reductions of less-reactive VOCs to offset small increases in HRVOCs
using the Maximum Incremental Reactivity (MIR) scale (see Section
II.B.4.). It is likely that some of the benefit will be realized
because we do not expect that many companies will implement the
additional monitoring of less reactive VOCs that would be necessary to
establish baselines necessary to participate in the trading program.
Also, under the TCEQ rules, less reactive fugitive emissions reductions
cannot be credited toward HRVOC increases so collateral reductions in
fugitive emissions should be fully realized. Another issue is the
uncertainty in the less-reactive VOC inventory. As discussed in the
section on emissions inventory uncertainty, it may be that less-
reactive VOCs are under-represented in the base case
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inventory. Because of uncertainty about the inventory, these collateral
reductions may not serve to reduce VOC emissions below what was assumed
in the model. These collateral reductions will serve to reduce the
degree of any potential under-representation in the inventory and thus
reduce this area of uncertainty in the attainment demonstration.
A second program that should result in additional reductions is the
Environmental Monitoring Response System (EMRS). The TCEQ and the HRVOC
regulated community have expanded the real-time ambient monitoring
network of specific VOCs in the HGB area. A primary goal of EMRS is to
prevent HRVOC emissions from creating situations that may lead to high
levels of ozone. The near real time monitoring and response built into
the program, which is further described in the TSD, will provide rapid
feed back that should help identify and quickly correct the releases
that can lead to high levels of ozones. EPA believes this added
scrutiny of ambient VOC levels will result in improved overall program
effectiveness, and could identify previously unknown sources of
emissions that could be controlled to further reduce emissions.
The TCEQ believes that additional reductions will also be achieved
through its public web-based access to an emission event database
incorporating lower reportable quantities of VOCs beyond just the
HRVOCs of most concern. This database puts facility performance
regarding unauthorized emission releases at the public's fingertips. As
public awareness of the number and amount of these releases increases,
industry is expected to respond in a manner similar to its response to
the Toxics Release Inventory program which has resulted in large
reductions in Toxic emissions. EPA agrees awareness and documentation
of these events should prompt industry to begin to evaluate the causes
of these events and institute an enhanced program to ensure that the
potential of an event is significantly minimized.
Texas believes the projected emissions for electric generating
units outside the nonattainment area are probably too high. The current
HGB SIP attainment demonstration modeling only excludes from the future
case emissions projections for units that have formally indicated an
intent to cease operation or that will be retired/reduced under agreed
orders. The future projected case modeling inventory may include
sources that will in fact be retired in (and/or prior to) 2007 as
newer, more cost effective plants come online as Texas utilities
continue the transition to a fully deregulated market. If this occurs,
additional reductions could result which are not accounted for in the
current SIP because the newer facilities would have lower emission
rates. EPA agrees that deregulation will encourage the retirement of
less efficient plants. Some of the benefit of this process may already
be incorporated in the projections because Texas has projected newly
permitted units will operate at 75% capacity in its projection of
future emissions for electric utility emissions. It may be that newly
permitted plants operate closer to full capacity as less efficient
plants are curtailed or retired such that overall projected emission
levels do not decrease as much. Some reductions should still occur
because the newer plants will be cleaner than the older plants. A
factor that weighs toward the projections of future emissions outside
the nonattainment being too low is the findings of a report on
emissions from offshore facilities too recent to be included in the SIP
which indicates that projected emissions from these facilities may be
significantly higher than what was modeled. Considering these factors
together, EPA believes that NOX emissions outside the
nonattainment area are slightly if at all less than projected and
provide little additional evidence the area will attain.
Texas also believes that NOX emission projections inside
the nonattainment area are overestimated. Inside the eight county
nonattainment area, the Mass Emissions Cap and Trade (MECT) program for
NOX applies. For sources with permits in hand when the first
cap allocations were established but which had not yet operated, TCEQ
issued allowances based on the allowable emissions in the permit (so
called ``allowable allowances''). Allowable allowances are those
allocated to sources based on permits issued prior to the initiation of
the MECT program, but not in operation for sufficient time to establish
a baseline. During the interim period, until a baseline is established,
sources operate complying with the ``allowable allowances.'' Then,
based on the actual emissions during the baseline period, the State
grants ``actual allowances.'' Because typically these facilities are
not operating at their full allowable rates, but significantly below
those values, a source will get fewer ``actual allowances'' than the
``allowable allowances'' it was granted based on the permit. Therefore,
as these newly permitted facilities establish baselines from which to
grant ``actual'' allowances, the NOX cap in the HGB will
decrease overall. The TCEQ examined the 2002 and 2003 permit database
and found that only 33 to 39 percent of the allowable allowances for
permitted facilities were used. The modeling was based on the
``allowable allowances'' because it was not possible to predict how
much lower the actual allowances will be than allowable allowances. The
number of allowable allowances is not insignificant. The TCEQ registry
currently carries 18,658 allowable allowances for 2007 which could
translate into a potential additional NOX emissions
reduction beyond what was modeled of up to 31 tpd if current trends for
the conversion of allowable allowances to actual allowances continue.
EPA agrees that as allowable allowances are converted to actual
allowances, actual emissions will be less than the emissions that were
modeled which should result in greater improvement in air quality than
projected in the model.
In summary, EPA believes that TCEQ has provided sufficient evidence
that NOX emission levels will be lower than those projected
in the model and thus, air quality improvements should be better than
predicted by the model. We also believe the reductions that will occur
due to collateral VOC reductions and brought about by the EMRS system
and emission events data base will reduce the uncertainty in the model
due to uncertainty in the VOC inventory.
Comprehensive Ozone Metrics And Ambient Trends
Based on the ambient data, the 1-hour ozone design values for the
HGB area have decreased significantly from 260 ppb in 1982 to 175 ppb
in 2003. Texas used this initial data to estimate a trend that
demonstrated that attainment of the 1-hour standard would be reached
sometime after 2020. The area's design value dropped significantly
during the 1980s, then flattened out during the 1990s, hovering around
200 ppb. Design values recently have resumed their downward trend and
are at the lowest values seen in at least the last twenty years. EPA
notes that the 2004 design value has further decreased to 169 ppb. The
current trend may be partly due to meteorological conditions in recent
years, but it is almost certainly accelerated by emission reductions
made since the 2000 SIP revision. If the design value continues to drop
at a rate comparable to that seen in the most recent five-year period,
then attainment would occur sometime around 2010. But the amount of
emissions reductions is expected to increase each year until 2007 as a
result of rules adopted in the
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2000 SIP revision and in this SIP revision. Consequently, the design
values are expected to decrease more rapidly as 2007 approaches. This
simplistic analysis alone by no means proves the area will attain the
standard by 2007, but EPA agrees the recent design value trends are
consistent with reaching attainment by 2007.
Alternative Design Value And Addressing Short-Term Excursions
As discussed previously, 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 believes the traditional modeling
does not replicate ozone produced by the sudden sharp increases in
HRVOC emissions that can occur in the HGB area due to non-routine
emission releases. TCEQ argues that this technical deficiency provides
an explanation for why the model's peak simulated ozone concentrations
were all below the HGB area's design value in 2000. The actual design
value calculated for the years 1999-2001 was 182 ppb, while base case
simulated peak ozone concentrations were below 160 ppb on every day but
August 31st. The TCEQ believes that the influence from short-term
releases should 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 the influence of
short-term releases, TCEQ applied Blanchard's technique (Statistical
Characterization of Transient High Ozone Events Interim Report;
December 21, 2001) to the 1999-2001 AIRS data. This technique uses a
threshold of a 40 ppb rise in ozone concentration in 1 hour to
distinguish between sudden rises in ozone 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. The base case includes seven days
with modeled peak ozone greater than 144 ppb, so the modeled peaks, in
fact, correspond well with the (non-SOCI) design value and in fact the
model may be over-predicting the ozone resulting from routine
emissions. If the model is over-predicting the ozone due to routine
emissions in the base case, then it is likely the model is over-
predicting the ozone due to routine emissions in the future case
projections providing additional evidence that the control strategy
will sufficiently reduce the ozone from routine emissions.
EPA considers the alternative design value approach one tool in
evaluating the possible impact of non-routine emission releases,
particularly releases of HRVOCs on the design value. By removing the
days that have rapid ozone formation and therefore are possibly the
result of large releases, it is possible to get a sense of the
potential impact of large emission releases on the design value. We are
not convinced, as yet, 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. Wind shifts are a common occurrence in the
HGB area and are likely responsible for some of these SOCI events. The
TCEQ analysis also did not screen out widespread exceedences unlikely
to be the result of a non-routine event. Still, we agree that emission
events do impact the design value to a degree that is difficult to
quantify. 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 as Texas has developed a
strategy to control both routine and event emissions, thus reducing
both contributions to the design value.
Wildfire Activity: In 2000, there was an unusually large amount of
wildfire activity in Southeast Texas due to drought conditions and
extreme temperatures in the August-September time frame. This is
documented in Section 3.7.2 of the SIP that shows that more than 5
times as many acres burned in 2000 as in any of the other years between
1999 and 2003. It is not expected the number and scope of fires modeled
in the current SIP attainment demonstration modeling would be
reasonably expected in future years. A sensitivity analysis was
conducted to quantify the impact of wildfires on the future year ozone
level in the HGB indicating wildfire activity does have an impact on
the HGB future ozone levels (i.e., 0.1 ppb to 1.7. ppb). EPA agrees
that the amount of wildfire activity was unusual in 2000 and should not
generally be expected in most years. Therefore, we agree that this is
additional evidence that indicates improved probability that the area
will attain in future years because the projected modeled emissions are
higher due to wildfires than should generally be encountered in future
years.
11. Is the One-Hour Attainment Demonstration Approvable?
EPA believes that the combination of photochemical modeling and
other evidence (WOE) indicates that the revised control strategy will
bring the area into attainment. This demonstration is based on new
information not available at the time the currently approved SIP was
developed and represents a significant improvement over past efforts to
model Houston. Specific improvements include:
Improved representation of Houston's complex meteorology.
Recognition of the importance of HRVOCs.
Recognition that HRVOCs are underestimated in the
emissions inventory.
Recognition of the potential impact of emissions
variability on ozone levels.
EPA believes that the modeling projects significant improvement due
to reductions in routine emissions. EPA believes TCEQ has shown through
the modeling of routine emissions that the portion of the ozone due to
routine emissions will be sufficiently reduced. The modeling of routine
emissions does not predict attainment on all days. The circumstances
that led to the very high exceedance on August 31, have been shown to
be unusual and thus EPA concludes the 31st should not be used to drive
the control strategy. On other days of the episode, ozone levels have
been shown to be reduced to below or just slightly above the standard.
The wildfires that occurred during the episode also are a rare event
occurring because of the high temperatures and drought conditions.
Removing the influence of wildfires from the modeling brings all of the
days with the exception of August 31 within 3.8 ppb of the standard.
Texas has provided evidence that additional emission reductions will
occur of both VOC and NOX. EPA particularly believes the
expected additional NOX reductions will provide additional
ozone benefit that could offset the small amount the modeling of
routine emissions shows the area to be above the standard. The
additional reductions in VOC expected from collateral reductions due to
the HRVOC rules and due to the implementation of the EMRS system and
the event reporting data base should at least partially mitigate any
errors in the non-HRVOC inventory used for the attainment modeling.
The model's under-prediction of high ozone levels using routine
emissions have been examined by TCEQ. TCEQ has proposed that two
phenomena (routine and non-routine emissions) drive the HGB design
value and that it is appropriate to estimate an alternative design
value that does not include the effects of non-routine emissions. If
[[Page 58128]]
TCEQ's estimated alternative design value (144 ppb) is an accurate
representation of the design value due to routine emissions, then the
control strategy modeling should reduce ozone levels due to routine
emissions below the ozone standard. TCEQ addresses the non-routine
emissions with the short-term limit that is expected to reduce the
contribution to the HGB area's ozone level due to non-routine emissions
such that non-routine emissions should not occur frequently enough at
sensitive locations and times to impact the area's attainment of the 1-
hour standard. As discussed in the TSD, the alternative design value
probably overestimates, to some degree, the impact of short-term
releases but still provides evidence that the current strategy to
reduce routine emissions should be successful in addressing that
portion of the 1-hour problem due to routine emissions and supports
TCEQ's two pronged approach to achieving attainment of the 1-hour
standard.
Finally, EPA believes the evaluation of ambient data trends
indicates that the area is on a track that is consistent with achieving
attainment of the one-hour standard by 2007.
B. New Control Measures
1. What Are the New Control Measures in These SIP revisions?
TCEQ has adopted the following new control measures since the
previously approved SIP revision:
Annual Cap on HRVOC emissions
Hourly (short-term) limit on HRVOC emissions
Improved requirements for HRVOC fugitive emissions
Requirements for Portable Gasoline containers
2. What Are the Annual Cap and Short-term Limit on HRVOC emissions?
As discussed in Section II.A.1, Texas relied primarily on two sets
of modeling in developing its control strategy. One set of modeling,
performed by TCEQ, is largely a traditional model formulation that
examines the routinely variable emissions which occur in the HGB area.
Through this modeling, TCEQ established that NOX emissions
would not have to be reduced as much as previously planned and routine
emissions of highly-reactive VOC emissions would have to be reduced.
Through the second set of modeling, examining the impact of large non-
routine releases of HRVOCs, it was established that the frequency and
magnitude of large non-routine releases of HRVOCs should also be
reduced.
To reduce the routine emissions of highly-reactive VOCs, Texas
adopted an HRVOC emissions cap-and-trade (HECT) program. This program
establishes an annual cap on emissions of ethylene, propylene,
butadiene and butenes from cooling tower heat exchange systems, flares,
and vent gas streams in Harris County. The rules establishing the cap-
and-trade system are contained in 30 TAC Chapter 101, Subchapter H,
Division 6. The rules establishing the monitoring and record keeping
necessary to determine compliance with the HECT are contained in 30 TAC
, Chapter 115, Subchapter H. EPA has reviewed the monitoring rules and
proposed approval of the Chapter 115 rules. (See E-Docket R6-OAR-2005-
TX-0014 ) EPA is reviewing the HECT program rules with respect to EPA's
Economic Incentive Program guidance and a separate proposed rule is
being developed. (See E-Docket R06-OAR-2005-TX-016) Because the
emission reductions achieved by the HECT program are relied on in the
attainment demonstration, EPA cannot finalize an approval of the
attainment demonstration unless or until the HECT program and the
Chapter 115 rules have been approved. In this document, we discuss how
the controls on HRVOCs have been modeled and support the attainment
demonstration.
In projecting the HRVOC emissions that would occur after the HECT
annual cap was implemented, TCEQ included a 5 percent safety factor in
the attainment demonstration modeling. In other words, rather than
model the levels established by the cap, Texas included 5 percent
additional emissions of HRVOCs in the model. This safety factor was
necessary because of the uncertainty that is introduced into the
modeling by using an annual cap to achieve a short-term standard such
as the National Ambient Air Quality Standard for ozone. On any given
day more sources could be operating above their annual average
emissions than below their annual average emissions. The 5 percent
safety margin provides some room to account for this day-to-day
variation in routine emissions.
As discussed previously, a large number of scenarios were simulated
in the Project H13 work, examining the impact of releases of various
sizes, times and locations. This study demonstrated that releases at
the worst-case place and time of 1000 lb/hour could have a 1-2ppb
impact on peak ambient ozone levels. To minimize frequency of these
events, TCEQ established an hourly limit on emissions from process
vents, flares, cooling towers and pressure relief devices. The hourly
limit on emissions is 1200 lbs/hour and is established at Sec. Sec.
115.722 and 115.761.
3. How Are the Annual Cap and the Short-Term Limit Related?
Texas has included features in the rules defining the interaction
between the annual cap and short-term limit that are unique to the
HECT. Typically, all emissions during the year would be counted toward
compliance with an annual cap. In establishing a cap-and-trade system
for the petrochemical industry in the HGB area, TCEQ felt it necessary
to consider the possibility of major upsets. TCEQ believed that non-
routine emissions from process upsets, while likely to occur, are not
predictable and therefore could make management of emissions under an
annual cap difficult. Therefore, TCEQ established in its rule that
emissions above the 1200 lb/hr short-term limit are not counted toward
compliance with the annual cap but rather expected to be controlled by
the short term limit. TCEQ was particularly concerned about the
potential situation where a single large release could force a smaller
source to shut down for the remainder of the year because its
allowances had been exhausted.
Although EPA agrees that a forced shutdown of smaller sources is
possible, it believes that many upsets can be avoided by a source
through the development and implementation of operation and maintenance
plans that address start-up, shutdown and malfunction of process
equipment and application of good air pollution control practices such
as required by 40 CFR 60.18(d). EPA notes that application of the
aforementioned procedures would significantly reduce the emissions
associated with such start-up, shutdown and malfunction events and
could avoid a the need for a forced shutdown. In addition, planning and
management of emissions by the source including participation in the
credit market should also avoid a forced shutdown while ensuring
compliance with the annual cap.
Emissions above the short-term limit would still be subject to
enforcement as a violation of the short-term limit, but only 1200 lbs
would be reported for compliance with the annual cap during those hours
where emissions exceed 1200 lbs. It is our expectation that the root
cause of the conditions giving rise to the emissions above the short-
term cap will be identified and corrected. Moreover, the source is
still required to use good air pollution control practices consistent
with the applicable NSPS (40 CFR 60.11(d)) and MACT standards or
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other applicable Federal or State programs.
The structure of the Texas HECT program, which does not require
emissions above the short-term limit to be counted against the long-
term cap, is a significant departure from past practices for cap-and-
trade programs such as the Title IV Acid Rain program and the Houston
NOX cap-and-trade programs. EPA's Economic Incentive Program
guidance regarding mass emissions cap-and-trade programs indicates that
all sources in the program should account for all of their emissions.
See section 7.4 of the EIP Guidance. We believe, in this instance, the
approach of not counting emissions above the short-term limit toward
the annual cap has both advantages and disadvantages as discussed
below. We are inviting comment on approving a program with this
structure, as we remain concerned about excess emissions resulting from
poor operation and/or poor maintenance.
We believe the structure of the TCEQ HECT rule has the advantage
that it establishes a clear procedure for how emissions during non-
routine events will be handled. For every hour during a large emissions
event, the source will include 1200 lbs toward meeting its annual cap.
This will avoid disputes about the validity of data during large
emission events, when monitoring may be less reliable. The rule clearly
defines the procedures to be followed during an emission event. Sources
will have no choice but to ensure that at the end of the compliance
period they have sufficient allowances to cover all of the emissions up
to the 1200 lb limit, or else face deductions from their compliance
account and other potential penalties. In addition, emissions above
that level would be subject to enforcement under the short term limit.
On the other hand, the structure of the rule has the disadvantage
that some of the incentive to prevent large releases is lost by
excluding emissions above the short-term limit from the annual cap. In
addition, some of the incentive for reducing the size of large events,
when they occur, may also be lost. With the annual cap-and-trade
program's exclusion of emissions above the hourly (short-term) limit,
it is probable that fewer violations of the annual cap will occur than
if the exclusion had not been provided. For sources that would have
violated the annual cap if emissions above the short-term limit were
considered, it may be harder to promote systemic changes at those
sources to reduce overall emissions.
Having looked at the advantages and disadvantages, we are proposing
approval of the program. We are proposing approval because, even though
it provides an exclusion for non-routine emissions above short-term
limit from the annual cap, it provides new enforceable limits that are
an improvement on the status quo, and we believe the annual cap in
conjunction with the short term limit will achieve the goals of the
attainment demonstration as indicated by the modeling analysis. The
annual cap should result in the necessary reductions in routine
emissions and the short-term cap should result in the necessary
reduction in the amount and frequency of non-routine emission events.
We note that the program rules require TCEQ to audit the HECT program
every three years, and facilities have to provide compliance reports
annually, so it will be readily apparent if the goals of the rules are
being achieved.
We believe the program will achieve the necessary reductions in
routine emissions because the size of the short-term limit is such that
only truly non-routine emissions will not be counted toward the annual
cap. Based on evaluation of the emission rates that were modeled in the
January 2003 SIP, the 1200 lb/hour limit is expected to be about ten
times larger than the average hourly emission rate at the largest
sources of HRVOCs. This order of magnitude difference between the
short-term limit and the average annual hourly emissions ensures that
sources will not routinely operate near or above the short-term limit,
thus achieving the goal of reducing routine emissions.
Also, while the structure of the HRVOC rules anticipates that
emission events will not be completely eliminated, EPA believes that it
provides sufficient disincentives that sources will reduce the
frequency and magnitude of large emissions events such that emission
events would not be expected to frequently impact peak ozone levels.
The Project H13 report 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. This indicates that while emission
events are frequent in the Houston area, emission releases at the place
and time that impact peak ozone do not occur nearly as frequently. As
noted elsewhere, it is possible that events are more frequent than
found in the project H13 report as past monitoring practices may not
have detected all releases.
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 exceedence per year. Based on the
study, we believe the hourly emission limit will achieve this goal.
After the institution of the short term limit, EPA expects that
emissions events impacting peak ozone levels will be reduced in
frequency to fewer than one per year. The frequency of emission events
will be reduced as facilities take actions to prevent violations of the
short term limit such as adding additional flare gas recovery capacity
so more releases can be captured and routed back to the process.
Sources that fail to take appropriate actions and which violate the
short term limit will be subject to enforcement. While events may occur
that impact ozone levels at other locations than where the peak ozone
level occurs, these events, because they are occurring in areas with
lower ozone levels, would not be expected to impact attainment of the
1-hour NAAQS.
Again, EPA recognizes that the approach of providing this partial
exclusion for emissions above the short-term cap 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 may never be completely
eliminated in the petrochemical industry. Because of the uniqueness of
this approach, however, we invite comment on our proposed approval of
this facet of the Texas plan.
4. Can Reductions in Less-reactive VOCs Be Made Instead of Reductions
in HRVOCs?
One feature of the Texas rules for capping HRVOCs is that sources
can make reductions in other less-reactive VOCs to generate allowances
for the HRVOC cap. The VOC reductions are used to generate emission
reduction credits (ERCs), in accordance with the Emission Credit
Banking and Trading Program, referred to as the ERC rule, established
at 30 TAC Chapter 101, Subchapter H, Division 1. These ERCs can then be
converted to allowances under the HECT program. The amount of
allowances is determined based on the ratio of the reactivity for the
speciated VOCs being reduced to the
[[Page 58130]]
reactivity of an HRVOC. Reactivity values are obtained from the Maximum
Incremental Reactivity Scale (MIR), California Code of Regulations,
Title 17, Chapter 1, Section 94700, concerning MIR values for
Compounds. The amount of allowances that can be generated is limited to
5% of a facility's cap. To generate less-reactive VOC emission
reduction credits, sources must meet the same monitoring requirements
for the less-reactive VOC streams that are required for HRVOCs streams.
As mentioned earlier, EPA is evaluating the HECT rule in a separate
Federal Register notice being developed concurrently. In addition, EPA
is evaluating TCEQ's ERC rule in a separate Federal Register also being
developed concurrently. (See E-dockets R06-OAR-2005-TX-0016 and R06-
OAR-2005-TX-0006). Since this attainment demonstration depends on the
reductions achieved by the HECT program, we cannot approve the
attainment demonstration unless the HECT rules are first approved.
Also, the conversion of ERCs to HECT allowances will not be approved
until the underlying ERC rules are approved.
Below we describe the impact of the conversion of allowances based
on the MIR scale on the attainment demonstration. EPA has generally
classed VOCs into two groups: reactive and non-reactive. All reactive
VOCs have traditionally been treated equally for regulatory purposes.
The findings of the TxAQS study, indicate that reactivity of certain
chemicals and their prevalence in the HGB area are causing a
disproportionate impact on ozone levels in the area. Thus, these HRVOCs
were targeted for control. Texas is making an allowance for a small
increase in HRVOCs (up to 5%) above the new emissions levels to be
offset with larger reductions in less-reactive VOCs. Modeling
sensitivity analyses were performed by the University of Texas and
documented in a report, titled ``Survey of Technological and Other
Measures to Control HRVOC Event Emissions.'' In this report, trades of
less-reactive VOCs much larger than would be allowed with the 5% cap
were considered. In the sensitivity runs, the impacts ranged from a 2.1
ppb increase to a 3 ppb decrease in the peak ozone, depending on the
episode day and the assumptions made about the less-reactive chemical
that was reduced. The researchers looked at the impact of adding
between 15 and 33 tpd of HRVOC to the model while removing the
requisite amount of less reactive VOCs. Under the rule, capping trades
at a 5% increase in highly reactive VOCs, an increase of less than 2
tpd of HRVOCs would be all that could be allowed. Therefore, the impact
of the actual program will be quite small.
We believe that the generation of HRVOC allowances of up to 5% of a
sources annual cap using reductions in less-reactive VOCs will not
interfere with the area's ability to attain the NAAQS. We are proposing
approval because the impact on the attainment demonstration will be
very small. In addition, for sources that participate in the program,
it will have the advantage of implementing additional source monitoring
on less-reactive VOCs. Our proposed approval does not represent a
general endorsement of the use of the MIR scale for use in SIPs. In
this instance, with the aforementioned technical support, we believe
this is an acceptable approach which is consistent with EPA's recently
issued ``Interim Guidance on the Control of Volatile Organic Compounds
in Ozone State Implementation Plans'' (August 25, 2005). EPA will
continue investigating how best to incorporate reactivity in the
regulation of VOCs.
5. What Estimates of Flare Efficiency Are Made in the SIP Revision?
For purposes of estimating emissions for compliance with the Cap,
the TCEQ rule requires companies to assume that properly operated
flares achieve 99% destruction efficiency for C2 and C3 hydrocarbons
and 98% destruction efficiency for all other hydrocarbons. To insure
these destruction efficiencies are achieved, the TCEQ rules require
sources to monitor continuously to demonstrate compliance with the
operating parameters of 40 CFR 60.18. Sources not operating in
compliance with 60.18 are subject to enforcement. In addition, during
periods when a flare operates outside the parameters of 60.18,
companies are to assume 93% destruction efficiency. EPA has proposed
approval of these rules. (See E-Docket R6-OAR-2005-TX-0014 ) The
assumptions regarding destruction efficiency impact the projected
emissions in the model. TCEQ has provided the justification for these
assumptions in Appendix L of the SIP. TCEQ relies on data from flare
studies initiated by EPA in the early 1980's that indicate that a
properly operated flare should achieve destruction efficiencies of 98%.
(Flare Efficiency Study, July 1983, PB83-261644, Evaluation of
Efficiency of Industrial Flares: Test Results, May, 1984, PB84-199371)
These studies provided the basis for the development of 40 CFR 60.18.
Texas used the data from these studies on ethylene and propylene to
estimate that for these chemicals destruction efficiencies of 99%
should be achieved by a properly operated flare.
Emission estimates from flares will always be a source of
uncertainty because emissions from flares cannot be directly measured
with today's technology. EPA is proposing to accept 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.
6. How has the Texas Leak Detection and Repair Program Been
Strengthened?
For a number of years, TCEQ has implemented a leak detection and
repair program as part of its program to control VOCs. When TCEQ
determined that additional reductions of HRVOCs were needed, they
established 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 a full discussion of the improvements to the program, see the
Technical Support Document for this action. We have proposed approval
of
[[Page 58131]]
these changes. (See E-Docket R6-OAR-2005-TX-0014 )
7. How Have the Benefits of the Leak Detection and Repair Program Been
Projected?
The nature of fugitive emissions introduces a great deal of
uncertainty in estimating fugitive emission rates. Much of this
uncertainty is unavoidable given the impossibility of estimating
emissions from each leaking component. In this SIP revision, TCEQ has
increased the amount of modeled HRVOC emissions above reported levels
based on ambient measurements as described previously. As part of this
adjustment, fugitive emissions were also increased above reported
levels. Below we explain why this increase in the modeled emissions to
match ambient measures may have been necessary because of possible
problems with assumptions regarding control efficiency and rule
effectiveness for fugitive emissions that were made in the State's
emissions inventory. EPA also believes these past practices are being
improved to reduce the uncertainty of future estimates.
Control Efficiency: Past TCEQ emission inventory practices allowed
companies the option of using average Synthetic Organic Chemical
Manufacturing Industry emission factors in combination with estimated
control efficiencies to estimate emissions. Since this approach does
not employ the data on the number of leaking components or the
concentrations of leaks, it potentially misjudges emissions. The
control efficiencies TCEQ has allowed sources to assume are higher than
EPA has projected for similar control programs. For example, in past
estimates for a similar program to the Texas program, EPA had estimated
a 92% control efficiency, where Texas has allowed sources to assume a
97% control efficiency. See the TSD for a more complete discussion. The
adjustment to the inventory based on ambient measurements could account
for discrepancies in assumed control efficiencies.
Rule Effectiveness: Rule effectiveness is a concept that tries to
account for difference between reported emissions and actual emissions.
Sources generally assume ideal program implementation in reporting
emissions when actual program implementation may be less than ideal. In
the case of fugitive emissions, a 100% rule effectiveness would assume
that facilities are completely accurate in their component counts and
detect and repair all of the leaking components. Clearly, in practice,
100% effectiveness is only a goal that can be strived for. Again, the
adjustment to the emissions inventory based on ambient measurement is
necessary, in part, due to rule effectiveness issues.
It is EPA's understanding that, prior to adjusting the inventory,
TCEQ assumed a rule effectiveness of 100% for sources that participated
in its special inventory.\3\ Because of the number of sources in the
special inventory, it is believed that the rule effectiveness is nearly
100%. EPA's National Enforcement Investigations Center has performed
leak surveys at refineries and has generally found more leaking
equipment than estimated by facilities. Surveys at 17 refineries across
the country found on average that facilities found 1.7% of their
components to be leaking. Where as the NEIC surveys found on average 5%
leaking components. Emissions based on the NEIC surveys were 2.4 times
as high as the emission estimates based on the facility surveys.
---------------------------------------------------------------------------
\3\ The special inventory was developed by asking the largest
facilities in the HGB area to provide daily emission estimates for
the time period of the TxAQS 2000 study.
---------------------------------------------------------------------------
Taken together, the control efficiency and rule effectiveness
determine the overall program effectiveness. TCEQ's addition of imputed
emissions based on actual ambient measurements is one way to account
for the program effectiveness issues described above and other
potential problems such as leaks from non-traditional components such
as heat exchanger bonnets and man-way covers.
The changes to the program will make strides to address these
issues. First, TCEQ has expanded the leak detection and repair program
to include connectors and non-traditional components. This will
increase the probability that leaks from unsurveyed equipment will be
detected and repaired. Second, TCEQ is requiring, starting with the
2004 inventory, that all sources use correlation equations instead of
assuming a control efficiency. Correlation equations are the most
sophisticated approach to estimating emissions, short of bagging
studies on each valve. As a result, future emission estimates will be
based on the actual leaks found. In addition, the institution of third
party audits should improve the performance of leak survey technicians
so that more leaks are detected and repaired. Finally, more valves will
be repaired as companies are required to employ ``extraordinary
efforts'' to repair a leaking valve before allowing the repair to be
delayed until the next shutdown. New technologies for repair, coming
under the heading of ``extraordinary efforts'' should greatly reduce
the number of valves that go unrepaired.
In summary, EPA believes that part of the reason it was necessary
to adjust the base inventory to increase the emissions above reported
levels based on ambient measurements, was to account for problems in
assumptions for control efficiency, rule effectiveness and leaks from
non-traditional components. The changes to the program will address
each of these areas. EPA believes that the combination of the
improvements to the program and the institution of third party audits
can result in the projected 64% reduction in emissions. The addition of
new components to the program and the requirement for extraordinary
repair effort will improve the control efficiency. The requirement for
third party audits and other changes will improve the rule
effectiveness. EPA's policy on credit for rule effectiveness
improvements requires that States commit to perform a study to
determine if the rule effectiveness improvements are in practice
realized. In response to comments on this issue, TCEQ has committed to
conducting a rule effectiveness study based on the third party audit
program after the program has progressed and data is available. EPA
notes the first third party audits will be completed December 31, 2005.
EPA would expect a rule effectiveness study summarizing the results of
the first third party audits could be completed during the 2006
calender year. Using the rule effectiveness study and the results of
the improved emission inventory estimates based on correlation
equations, Texas will be able to determine if the emissions targets
that have been modeled have been reached. In addition, this data will
be useful in developing the 8-hour attainment plan.
EPA is proposing to approve 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.
8. What Are the 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 has
approved the TCEQ rules on February 10, 2005 (70 FR 7041). TCEQ has
projected 2.9 tons/day
[[Page 58132]]
of emission reductions. We are proposing approval of the modeling with
the inclusion of these projected emission reductions.
C. Revised Control Measures
1. What Control Measures Have Been Revised or Repealed?
Texas has revised a number of control strategies that were included
in the approved State Implementation Plan. A description of the
revisions follows.
Industrial NOX Controls: Texas revised its NOX rules to
relax the controls from a nominal 90% control to 80% control. Both the
90% level of control and the 80% level of control are far more
stringent than the levels of control EPA previously approved as meeting
the NOX RACT requirements of Section 182 (65 FR 53172,
September 1, 2000). Therefore, the 90% level of control is a
discretionary control measure as considered in the Phase 1 rules
because the 90% level of control was not mandated by Subpart 2 of the
Clean Air Act but was chosen as necessary for the area to demonstrate
attainment of the 1-hour standard. Discretionary measures are not
subject to the antibacksliding provisions of the Phase 1 rule, but any
revisions of such measures are subject to Section 110(l) of the Act. In
Section II.E., we discuss the revised plan's compliance with Section
110(l) of the Act. In Section II.B., we discuss why we believe, taken
together with other changes, the plan continues to demonstrate
attainment of the 1-hour standard. In section II.D., we explain why we
believe this measure is not necessary to meet the Act's RACM
requirement. For the above reasons, we are proposing approval of the
revisions to the TCEQ Chapter 117 rules reducing the stringency from a
nominal 90% control to a nominal 80% control.
In addition to a change in stringency of the rules, TCEQ made a
number of less significant changes that are discussed in appendix 1 of
the TSD. These changes include the repeal of outdated sections, rule
clarifications, stylistic changes in response to Texas Register
guidelines, minor changes to monitoring requirements, corrections to
cross references and improved recordkeeping requirements for
consistency with Title V requirements. We are also proposing approval
of these less substantive changes.
Vehicle Inspection and Maintenance Program in Three Rural Counties:
TCEQ has dropped the requirement for I/M in Waller, Liberty and
Chambers Counties. These counties are not included in the urbanized
area and are therefore not required by Subpart 2 of the Act to
implement an I/M program. Therefore, I/M in these three counties is a
discretionary measure that is not subject to the antibacksliding
provisions of the Phase 1 rule, but any revisions to the SIP approved
I/M requirements must comply with section 110(l) of the Act. In Section
II.E., we discuss the revised plan's compliance with Section 110(l) of
the Act. In Section II.B we discuss why we believe, taken together with
other changes, the plan continues to demonstrate attainment of the 1-
hour standard. In section II.D., we explain why we believe this measure
is not necessary for the area to meet the Act's RACM requirement.
Therefore, EPA is proposing to approve the repeal of the I/M program
for these three counties.
The TCEQ also made a number of nonsubstantive changes to the I/M
program that are discussed in Appendix 2 of the TSD. These changes were
corrections to cross references and stylistic changes. We are also
proposing approval of these additional nonsubstantive changes.
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. This
measure is not required by Subpart 2 of the Clean Air Act. Therefore,
it is a discretionary measure that is not subject to the
antibacksliding provisions of the Phase 1 rule, but any revision to the
approved SIP must comply with section 110(l) of the Act. In Section
II.E., we discuss the plan's compliance with Section 110(l) of the Act.
In Section II.B., we discuss why we believe, taken together with other
changes in the plan, the revised plan continues to demonstrate
attainment of the 1-hour standard. In section II.D., we explain why we
believe this measure is not necessary to meet the Act's RACM
requirement. Therefore, EPA is proposing approval of this change.
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. Calculated using Mobile 6, the
reductions from this measure are much smaller than as calculated under
Mobile 5 in the previous SIP. This measure is not required by Subpart 2
of the Clean Air Act. Therefore, it is a discretionary measure that is
not subject to the antibacksliding provisions of the Phase 1 rule, but
any revision to the approved SIP must comply with section 110(l) of the
Act. In Section II.E., we discuss the plan's compliance with Section
110(l) of the Act. In Section II.B., we discuss why we believe, taken
together with other changes in the plan, the revised plan continues to
demonstrate attainment of the 1-hour standard. In section II.D., we
explain why we believe this measure is not needed to meet the Act's
RACM requirement. For the above reasons, EPA is proposing approval of
this revision of the State's plan.
Removal of the Vehicle Idling Restriction: This measure that would
have prohibited prolonged idling of heavy duty diesel vehicles has been
repealed. This measure is not required by Subpart 2 of the Clean Air
Act. Therefore, it is a discretionary measure which is not subject to
the antibacksliding provisions of the Phase 1 rules, but any revision
to the approved SIP must comply with section 110(l) of the Act. In
Section II.E., we discuss the plan's compliance with Section 110(l) of
the Act. In Section II.B., we discuss why we believe, taken together
with other changes in the plan, the revised plan continues to
demonstrate attainment of the 1-hour standard. In section II.D., we
explain why we believe this measure is not necessary to meet the Act's
RACM requirement. For the above reasons, we are proposing approval of
this change.
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. A delay in the compliance date results
in reduced emission reductions because there is less time for old water
heaters to be replaced with new water heaters through normal turnover.
Texas has accounted for these lost reductions in its attainment
modeling. This measure is not required by Subpart 2 of the Clean Air
Act. Therefore, it is a discretionary measure that is not subject to
the antibacksliding provisions of the Phase 1 rule, but any revision to
the approved SIP must comply with section 110(l) of the Act. In Section
II.E., we discuss the plan's compliance with Section 110(l) of the Act.
In Section II.B., we discuss why we believe, taken together with other
changes in the plan, the revised plan continues to demonstrate
attainment of the 1-hour standard. In section II.D., we explain why we
believe earlier
[[Page 58133]]
implementation of this measure is not necessary to meet the Act's RACM
requirement.
We are not proposing approval of this change 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 State
Implementation Plan. This portion of the plan, which was approved in
2001, was projected to achieve 23 tpd of emission reduction through
various voluntary and often innovative measures. Experience and the
recalculation of the benefits with Mobile 6 has resulted in a much
lower expectation for the program which now is expected to only achieve
10.6 tpd of emission reductions. The details of changes to the program
are contained in appendix O of the SIP. These measures are not required
by Subpart 2 of the Clean Air Act and therefore, are discretionary
measures that are not subject to the antibacksliding rules provisions
of Phase 1 rule, but revisions to the approved 1-hour SIP must comply
with section 110(l) of the Act. In Section II.E., we discuss the plan's
compliance with Section 110(l) of the Act. In Section II.B., we discuss
why we believe, taken together with other changes in the plan, the
revised plan continues to demonstrate attainment of the 1-hour
standard. In section II.D, we explain why we believe these measures are
not necessary for the area to meet the Act's RACM requirement. For the
above reasons, EPA is proposing approval of the revisions to the VMEP
measures.
D. Reasonably Available Control Measures
1. What Are the RACM Requirements?
Section 172(c)(1) of the Clean Air Act requires that each
nonattainment plan provide for the implementation of all reasonably
available control measures as expeditiously as practicable (including
such reductions in emissions from existing sources in the area as may
be obtained through the adoption, at a minimum of reasonably available
control technology) and shall provide for attainment of the national
primary ambient air quality standards. EPA has provided guidance
interpreting section 172(c)(1) of the Act. See 57 FR 13498, 13560,
April 16, 1992. In that guidance, EPA indicates that potentially
available control measures, which would not advance the attainment date
for an area or contribute to reasonable further progress, would not be
considered RACM under the Act. EPA's guidance also indicates that
States should consider all potentially available measures to determine
whether they are reasonably available for implementation in the area
including whether or not they would advance attainment. Further, the
guidance calls for states to indicate in their SIP submissions whether
measures considered are reasonably available or not, and if so the
measures must be adopted as RACM. Finally, the guidance indicates that
States could reject potential RACM measures either because they would
not advance the attainment date or would cause substantial widespread
and long-term adverse impacts or for various reasons related to local
conditions. See ``Guidance on Reasonably Available Control Measures
(RACM) Requirement and Attainment Demonstration Submissions for Ozone
Nonattainment Areas,'' John Seitz, Director, Office of Air Quality
Planning and Standards, November 30, 1999.
2. How Has Texas Insured With This Plan Revision That All RACM Are
Being Implemented?
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. In
section II.A. of this notice, we discuss how EPA found that the revised
plan for HGB will achieve attainment of the 1-hour standard, based on
the controls that will be in place by the beginning of the ozone season
of 2007. 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 described in Section II.C., Texas believes the
RACM requirement is still being met. What follows is a summary of EPA's
evaluation of each of the revisions.
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 considered 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 and therefore is not RACM. 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. (See the Technical
Support Document for more information)
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. These 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
.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
[[Page 58134]]
expected to advance attainment. Thus, EPA proposes that implementation
of I/M in these three counties is not required to meet the RACM
requirement.
Removal of Small Spark Operating Restrictions: This measure would
prohibit lawn and garden service contractors for operation in the
morning hours from 6 a.m. to 10 a.m.--a time during which emissions
have been found to contribute most significantly to ozone production.
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 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 Mobile 6, lowering speeds all the way to 55 mph would be
expected to reduce emissions 2-3 tons/day. This is a lower estimate of
emission reductions than predicted by Mobile 5 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 decide 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.
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 and would not be RACM.
E. Section 110(l) Analysis
1. What Does Section 110(l) Require?
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.''
2. How Has Texas Shown These Revisions Do Not Interfere With Attainment
of the 8-hour Standard?
Texas must consider whether the new strategy which relies on fewer
reductions of NOX and more reductions of VOC will interfere
with attainment or reasonable further progress or any other applicable
requirement under the Act. A strict interpretation of this requirement
would allow EPA to approve a SIP revision removing a SIP requirement
only after determining, based on a completed attainment demonstration,
that it would not interfere with applicable requirements concerning
attainment and reasonable further progress. As discussed above, Texas
has completed a revised attainment demonstration with respect to the 1-
hour standard. Attainment demonstrations for the 8-hour standard are
not due for several years. EPA recognizes that prior to the time areas
are required to submit full attainment demonstrations for the 8-hour
ozone standard, this strict interpretation could prevent any changes to
the SIP control measures. EPA does not believe this strict
interpretation is necessary or appropriate.
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.
For example, different mixes of NOX or VOC and industrial or
mobile source controls may result in attainment. 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 the control measures being removed from
the approved SIP. EPA believes preservation of the status quo air
quality during the time new attainment demonstrations are being
developed will prevent interference with the States' obligations to
develop timely attainment demonstrations and to attain as expeditiously
as practicable.
``Equivalent'' emission reductions mean reductions which result in
equal or greater air quality benefit than those reductions being
removed. To show the compensating emission reductions are equivalent,
modeling or adequate justification must be provided (EPA Memorandum
from John Calcagni, Director Air Quality Management Division, to the
Air Directors in EPA Regions 1-10, September 4, 1992). The compensating
emission reductions must represent 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,
quantifiable, and surplus to be approved into the SIP.
As discussed previously, Texas has chosen to substitute actual,
reductions of HRVOCs for some of the NOX reductions in the
approved SIP. This approach is evaluated below with respect section
110(l) and the criteria described above.
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
[[Page 58135]]
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--March 31, 2004, HRVOC cap-monitoring 2005, full cap
compliance 2006, gas can rule-2007. The measures being replaced, which
are listed in section II.D., 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% and 80% control on NOX, was not scheduled to be
put in place until 2007. It is worth noting that reductions that would
have been achieved by controls adopted to meet the enforceable
commitment to reduce NOX did not have a specified compliance
date. The commitment 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 as 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 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 would have occurred due
to measures to meet the enforceable commitments. Several 8-hour ozone
metrics were calculated. The results indicated that the revised SIP is
slightly more effective in reducing 8-hour ozone than the previously
approved SIP in both average relative reduction factor (0.931 vs.
0.940) and in average future design value (107 vs 108 ppb). Although
some monitoring stations fare slightly worse under the new control
strategy, others fare slightly better. In addition, for both peak 8-
hour ozone concentration and exposure metrics, the benefits of the new
strategy exceed those of the old on every day except September 6, where
the old strategy is slightly better. Considering, the modeled predicted
area of exceedance, however, the comparison is less clear-cut. The
older strategy shows more of a benefit on six of ten days and the new
strategy shows a greater benefit on three days. Both strategies
indicate the same benefit on one day. In summary, EPA believes that the
new strategy and the old strategy are approximately equivalent in eight
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 exceedence. 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 is reviewing the enforceability of the substitute
measures in separate rules. The Gas Can Rule was approved on February
10, 2005, 70 FR 7041. EPA has proposed approval of the fugitive
emission controls and improved monitoring requirements for HRVOCs on
April 7, 2005, 70 FR 17640 . Finally, concurrent with this Federal
Register notice EPA is proposing approval of the HECT program. In each
of these rulemakings, EPA will evaluate 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. As discussed elsewhere, the
revisions to the attainment plan including the NOX rule
repeals and revisions that reduce the projected amount on
NOX emission reductions cannot be approved unless final
approval of the substitute rules is completed. If approved, these
substitute rules will be 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.
3. What About Possible Interference With the 1-Hour Ozone 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, unless the State could show that these
NOX reductions were not needed for attainment of the 1-hour
standard. We have discussed, in Section II.A., EPA's evaluation of the
revised 1-hour attainment demonstration and are proposing approval of
that strategy as demonstrating attainment of the 1-hour standard.
4. How Has Texas Shown These Revisions Do Not Interfere With Rate of
Progress?
Texas submitted, and EPA has approved, revisions to the rate of
progress plan (February 14, 2005 70 FR 7407) based on the revised
strategy. These revisions will ensure that 1-hour ROP is met for each
3-year period out to the 1-hour attainment date. (See the Federal
Register cited above for further explanation of the approved ROP
demonstration.)
5. Do These Revisions Interfere With Attainment of Other Standards
Besides Ozone?
The HGB area currently meets all other National Ambient Air Quality
Standards besides ozone. 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 still reduce NO2 emissions
considerably from today's levels and thus will not interfere with
maintenance of the NO2 standard.
Similarly, the HGB area currently meets the NAAQS for PM fine.
NOX and VOCs are precursors to the formation of PM fine. The
revised plan will result in additional NOX and VOC
reductions beyond today's levels. Therefore, the revised plan will not
interfere with the continued attainment of the PM fine standard.
[[Page 58136]]
6. Do the Revisions Interfere With Any Other Applicable Requirements of
the Act?
Section 110(l) applies to all requirements of the 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 Act'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 thus these revisions
do not interfere with meeting the I/M requirements of the Act.
Air Toxics: There are no federal ambient standards for air toxics
and these rules do not impact compliance with any federal MACT
standards so these rule revisions do not interfere with compliance with
any air toxics standards. We note that air toxic levels of butadiene
and formaldehyde are expected to decrease as a result of the revised
plan. Butadiene emissions are directly regulated by the new HRVOC
rules. Formaldehyde is formed from ethylene in the photochemical
reactions leading to ozone.
F. Enforceable Commitments
1. What Is an Enforceable Commitment?
An enforceable commitment is a written commitment that is approved
into the SIP that is enforceable against the State. 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.
To be enforceable, commitments must be approved as part of the SIP
and, therefore, the State must have given notice and taken comment on
the commitment, held a public hearing and submitted it as a SIP
revision. The commitments must be specific as to the state agency's
future plans for adoption of specified control measures. The dates for
implementation of, or compliance with, the future to-be-adopted
specified control measures must be included in the commitments and be
as expeditious as practicable. If the State does not follow through
with the commitment, EPA can find that the State failed to implement
the SIP. Further, the public can seek enforcement of the obligations
under Section 304(a) of the CAA.
2. What Were the Enforceable Commitments in the 2001 Approved SIP and
Have They Been Fulfilled?
In the approved SIP, there are a number of enforceable commitments.
In this section we evaluate whether these enforceable commitments have
been met. The State made the following commitments which were approved
in the November 2001 Federal Register.
To perform a mid-course review (including evaluation of
all modeling, inventory data, and other tools and assumptions used to
develop this attainment demonstration) and to submit a mid-course
review SIP revision, with recommended mid-course corrective actions, to
the EPA by May 1, 2004.
Discussion: Texas provided the mid-course review in the December
2004 submission. It included new modeling with new more recent episodes
based on the Texas 2000 study. Virtually all of the inputs to the model
were updated and improved, making the 2004 SIP the best modeling ever
performed for the Houston area. Additionally, 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.
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 midcourse review modeling employed MOBILE6 for the
on-road mobile source inputs satisfying this 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 conformity was not performed during the time period.
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.
See below.
To adopt measures to achieve 25% of the needed additional
reductions (56 tpd) and submit those adopted measures to EPA as a SIP
revision by December 2002.
Discussion: This commitment required TCEQ to find measures to
achieve an additional 14 tons/day of NOX emission reductions
and to submit adopted control measures by December 2002. 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.
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: Texas determined that these additional NOX
reductions would not be necessary for the area to attain. Instead, as
discussed elsewhere in this document, 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
[[Page 58137]]
discussed in Section II.B. regarding the review of the attainment
demonstration and Section II.E regarding whether section 110(l) of the
Act has been met.
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.
That the State would concurrently revise the Motor Vehicle
Emissions Budgets (MVEBs) and submit them as a revision to the
attainment SIP if additional control measures reduce on-road motor
vehicle emissions. Texas stated that measures which could limit future
highway construction, such as growth restrictions, may not be included.
Discussion: Texas has revised the mobile source budget to account
for TERP reductions and other adjustments to the mobile source
emissions estimates.
Summary: Based on the above analysis, we propose that TCEQ has
satisfied the requirements of the enforceable commitments contained in
the approved HGB SIP.
G. Motor Vehicle Emissions Budgets
1. What Is a Motor Vehicle Emissions Budget and Why Is It Important?
The MVEB is the level of total allowable on-road emissions
established by a control strategy implementation plan or maintenance
plan. In this case, the MVEB establishes the maximum level of on-road
emissions that can be produced in 2007, when considered with emissions
from all other sources, which demonstrate attainment of the NAAQS. It
is important because the MVEB is used to determine the conformity of
transportation plans and programs to the SIP, as described by section
176(c)(2)(A) of the Act.
2. What Are the Motor Vehicle Emissions Budgets Being Proposed for
Approval?
The MVEBs established by this plan and that the EPA is proposing to
approve are contained in Table 2. The development of the MVEBs are
discussed in section 3.5 of the SIP and reviewed in the TSD. We are
proposing approval because we find the MVEB 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. General Information
A. Tips for Preparing Your Comments
When submitting comments, remember to:
1. Identify the rulemaking by File ID number and other identifying
information (subject heading, Federal Register date and page number).
2. Follow directions--The agency may ask you to respond to specific
questions or organize comments by referencing a Code of Federal
Regulations (CFR) part or section number.
3. Explain why you agree or disagree; suggest alternatives and
substitute language for your requested changes.
4. Describe any assumptions and provide any technical information
and/or data that you used.
5. If you estimate potential costs or burdens, explain how you
arrived at your estimate in sufficient detail to allow for it to be
reproduced.
6. Provide specific examples to illustrate your concerns, and
suggest alternatives.
7. Explain your views as clearly as possible, avoiding the use of
profanity or personal threats.
8. Make sure to submit your comments by the comment period deadline
identified.
B. Submitting Confidential Business Information (CBI)
Do not submit this information to EPA through regulations.gov or e-
mail. Clearly mark the part or all of the information that you claim to
be CBI. For CBI information in a disk or CD ROM that you mail to EPA,
mark the outside of the disk or CD ROM as CBI and then identify
electronically within the disk or CD ROM the specific information that
is claimed as CBI). In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the official file. Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
IV. Statutory and Executive Order Reviews
Under Executive Order 12866 (58 FR 51735, October 4, 1993), this
proposed action is not a ``significant regulatory action'' and
therefore is not subject to review by the Office of Management and
Budget. For this reason, 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
proposed action merely proposes to approve state law as meeting Federal
requirements and imposes no additional requirements beyond those
imposed by state law. Accordingly, the Administrator certifies that
this proposed 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 proposes to approve 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 proposed rule also does not have tribal implications because
it will not have a substantial direct effect on one or more 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 proposes to approve a state rule implementing a Federal
standard, and does not alter the relationship or the distribution of
power and responsibilities established in the Clean Air Act. This
proposed 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, EPA's role is to approve state
choices, provided that they meet the criteria of the Clean Air Act. 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
[[Page 58138]]
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 Clean Air Act. Thus, the requirements
of section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (15 U.S.C. 272 note) do not apply. This proposed 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.).
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.
Authority: 42 U.S.C. 7401 et seq.
Dated: September 27, 2005.
Richard Greene,
Regional Administrator, Region 6.
[FR Doc. 05-19994 Filed 10-4-05; 8:45 am]
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