Advanced Air Permitting Seminar
The Odyssey Continues
October 16, 2014
Introduction and Background
Air dispersion modeling guidance for New Source Review (NSR) permitting has not kept
pace with changes made to the National Ambient Air Quality Standards (NAAQS) and
Prevention of Significant Deterioration (PSD) increments.
The lack of a settled modeling process directly affects the Air Permits Division’s mission
and ability to meet permit timeframe goals. This uncertainty impacts the TCEQ staff,
applicants, and the public.
The United States Environmental Protection Agency (EPA) has not provided clear and
effective air permitting rules, policy, and guidance when it adopted the NAAQS and
increments. This serious shortfall is significant because of the profound changes made
to the NAAQS and increment. Without this key component of the air permitting
program, the TCEQ has struggled to balance regulatory requirements with economic
growth.
This paper updates the Expanded Outline for the Modeling Update presented at the
Advanced Air Permitting Seminar, September 25, 2013. Last year’s presentation
identified the problem; explained how we got there; outlined EPA’s plan to resolve the
problem; and described how the TCEQ staff could help applicants.
This paper will briefly discuss EPA’s roadmap to update national modeling guidelines
and the recently updated TCEQ modeling guidelines. In addition, it will provide general
comments on how TCEQ can help applicants demonstrate compliance. Modelers have
provided answers and examples for frequently asked questions related to EPA’s
implementation guidance to demonstrate compliance with new national ambient air
quality standards (NAAQS). Their presentations and expanded outlines will be available
online as well.
EPA’s Roadmap
Background
The fact that we are having problems is not new -- we have always had issues when the
EPA has adopted new standards or increments. While we have always asked the EPA to
provide NSR implementation rules, policy, and guidance at or before adoption, this has
rarely occurred and the lack of implementation guidance has limited the staff's ability to
maintain an effective permitting strategy. Over the years, the implementation dilemma
significantly increased as multiple rules became effective without a permit
implementation plan. The resolution of these obstacles is ongoing and will evolve
slowly.
At the 10th Modeling Conference (March 2012) it was apparent that EPA’s Guideline on
Air Quality Models (GAQM) contained in Appendix W - 40 Code of Federal Regulations
(CFR) Part 51 (November 2005, page 68229) needed to be updated. EPA recognized
that old policy and practices and lack of updated technical models, tools, and techniques
were having a negative effect on the issuance of air permits. Continued technical
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challenges related to the 24-hour and annual standards for PM2.5, initially adopted in
1997 and updated in 2006, and the adoption of new national ambient air quality
standards (NAAQS) for 1-hour NO2 and SO2 NAAQS in 2010 were straining state
resources and the delicate balance between economic development and air quality.
It took Ulysses 20 years to fight in a war and then find his way home. It may take EPA
as long to address continuing technical modeling challenges with implementation of
ozone, PM2.5, NO2, and SO2 primary standards. These challenges are likely to continue
with planned secondary standards for these pollutants. Unlike other projects that have
a clear beginning and end, the modeling improvement process must continue to address
identified problems and to ensure timely implementation of future standards in the air
permitting process.
More detailed information on EPA’s "Roadmap of the Day" can be found on EPA’s
Support Center for Atmospheric Models. Additional information is also included in
presentations from the 2014 national modeling workshop.
Research, Models, and Tools
EPA continues to partner with other federal agencies and has established formal
working groups of Office of Air Quality Planning and Standards (OAQPS) and Regional
Office Modelers to conduct research and resolve technical issues. EPA’s technical
improvement efforts will address limitations affecting the permitting process for 1-hour
NO2 and SO2 NAAQS, involvement of precursor emissions in secondary formation of
PM2.5, and single-source ozone evaluations. EPA’s workgroups and project leads consist
of:
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AERMOD Development & Evaluation (Roger Brode)
Screening Techniques (James Thurman)
NO2 Modeling (Chris Owen)
Near-road Modeling (Chris Owen)
Meteorological Inputs (James Thurman)
Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 3: Near-field
impacts and long-range transport (EPA and Federal Land Managers). This littleknown workgroup began in July 2013 to provide a mechanism for updating Appendix
W and related guidance documents in partnership with the Regional offices and other
Federal Agencies.
The goals of the workgroup increase knowledge regarding the NSR PSD program and
single source secondary impacts; understand and evaluate modeling techniques for
single source secondary impacts; inform and support regulatory revisions to
Appendix W.
The GAQM and Other Rules
EPA will propose changes to the GAQM in spring 2015 and hold the rulemaking public
hearing during the 11th Conference on Air Quality Modeling at Research Triangle Park,
North Carolina. The final rulemaking date will be sometime in spring 2016.
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The GAQM rulemaking should incorporate new analytical techniques to address ozone
and secondary PM2.5 formation; provide updates for conducting individual source and
cumulative impact analysis for new 1-hour NAAQS; and update, as appropriate, current
EPA-preferred models to address model input and science issues. EPA’s goal is to
develop appropriate rules that will be relevant over the long term to minimize the need
for future GAQM updates. The technical details and adjustments to techniques or
model application would be in the guidance documents, which should be more
responsive to the dynamics of NAAQS changes or development of model modules.
However, we would caution EPA that there is a fine line between rule and guidance, and
guidance may need to follow the rulemaking process to ensure it is fully vetted by states
and the public. In addition, EPA should seek input from states before any changes are
made to regulatory models or input data processors to ensure the states can implement
them. For example, changes to the AERMET meteorological data preprocessor may
require existing meteorological data sets to be updated before AERMOD can be run.
In addition, EPA plans an Ozone PSD and Nonattainment NSR Requirements Rule to:
 address revising the significant emission rates (SERs) for VOC and NOX as ozone
precursors and of having VOC and NOX triggers for requiring an ozone air quality
analysis in PSD areas, set higher than the SERs;
 establish significant impact levels (SILs) for ozone, so the PSD rule’s default SIL of
zero does not apply to ozone; and
 use new ozone SILs once the planned Appendix W revisions provide approaches to
quantify ozone impacts. This rulemaking will lag the rulemaking for the Appendix W
revisions.
Also, in early 2015 EPA plans to initiate a PM2.5 SILs Reconsideration Rule. This
rulemaking should:
 Establish legal and technical bases for PM2.5 SILs and their use in the PSD air quality
analysis, and
 Address SERs for SO2 and NOx as PM2.5 precursors and possibly a new SER for
ammonia!
TCEQ Modeling Guidelines
The lack of established permit modeling guidance, technical procedures, and tools add
to permitting challenges because we do not have the ability to delay the issuance of
permits until we have all the implementation pieces in place. Some (not all) of the
modeling guidance and technical issues are out of TCEQ's control to fix. In addition,
without EPA’s planned updates, applicants will continue to have difficulty
demonstrating compliance with 1-hour NO2 and SO2 NAAQS and the PM2.5 NAAQS and
increments.
Rather than continue to wait until EPA updates the GAQM in 2016, the ADMT
developed a guideline that contains general modeling procedures, that are not likely to
change frequently, with a series of appendices that either outline established procedures
or the most current interim procedures. Stakeholders had considerable opportunity to
comment on a draft document.
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Once EPA has built the modeling process foundation, TCEQ can update its modeling
guidelines. Hopefully, it will not take too many iterations before we can give applicants
what they want, to address their business needs.
Updated TCEQ Modeling Guidelines
TCEQ’s draft Air Permits Division Guidance document (APDG 6232 Air Quality
Modeling Guidelines) will be final in fall 2014. However, as with the EPA GAQM and
certain pollutant technical guidance, the modeling guidelines will be in flux for the
foreseeable future to ensure they integrate new EPA modeling guidance as applicable.
We are aware of applicant concerns that our guidance unnecessarily binds them and
may adversely affect their business needs. However, we believe our staff developed
guidance that will help applicants demonstrate compliance with federal and state air
standards and state effects screening levels. The guidelines provide flexibility and
certainty, and are quick and easy to use. In addition, the guidelines ensure TCEQ meets
it mission to balance economic benefit and environmental impact and APD’s goal to
issue quality permits in a timely manner.
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Staff Examples for Frequently (or Commonly) Asked Questions (FAQs)
General Guidance: How TCEQ Can Help Applicants Demonstrate Compliance
Air Permits Division staff have worked closely with applicants to help them demonstrate
compliance with NAAQS and PSD increments. Unfortunately, without settled
permitting guidance to implement new or modified NAAQS, applicants must take steps
to ensure their sources comply with all requirements, including protection of public
health and welfare.
There are several factors to consider regarding new standards. An applicant is not
shielded from demonstrating compliance with new standards if the standards become
effective after the administrative complete date. Per EPA policy, a PSD permit cannot
be issued without the demonstration. In addition, a nonattainment permit is required if
the area designation changes before a PSD permit is issued.
Other important factors applicants must consider are special conditions, controls, and
emission rates in existing permits and whether they apply to a new or modified facility
project undergoing review for a new standard and existing ambient air quality.
The Air Dispersion Modeling Team (ADMT) staff want to help you get your permit when
you want it. There are fixed times in the permit process related to public notice that the
permit reviewer cannot adjust. Therefore, an applicant must consider the potential for
refined air dispersion modeling as a potential chokepoint. In addition to ADMT
resource limitations, an applicant must consider EPA and other TCEQ staff’s time. For
example, EPA reviews and comments on all major source protocols, and Toxicology
Division staff may evaluate modeling results if the project includes contaminants with
effects screening levels.
Applicants should include extra time to prepare for and resolve issues related to permit
modeling to ensure permits are issued “on time.” They should anticipate the modeling
chokepoint and meet with staff before they submit an application. Modeling protocols
are required for major projects, and protocols or checklists are recommended for minor
projects.
ADMT will help you develop a modeling protocol. An applicant should not assume that
a protocol or checklist is not required because they have received a permit recently.
Since the EPA continues to develop or change interim guidance at the national level,
TCEQ does not have set modeling guidance yet for some pollutants and averaging times
-- what might have been acceptable previously will not be acceptable today.
Specific Examples for FAQs
Staff will provide answers and examples for FAQs related to ozone, PM2.5, NO2, and use
of monitored concentrations. Much of the information presented for NO2 and ambient
air monitors will apply to SO2 , as well.
Staff presentations and expanded outlines discuss the following topics and provide
examples:
 Ozone. When and how to conduct an ozone impacts analysis. Examples of different
approaches that can be used to address the various aspects of ozone impacts analysis,
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such as screening and impacts analysis; and quantitative and qualitative
demonstrations.
 PM2.5. When and how to conduct a PM2.5 impacts analysis. Examples of different
approaches that can be used to address the various aspects of a PM2.5 impacts
analysis, such as SIL justification; precursors; secondary formation; quantitative,
qualitative, and hybrid analysis; and increment.
 NO2. Modeling procedures for the 1-hour NO2 National Ambient Air Quality Standard
(NAAQS). Examples of different approaches that can be used to address the various
aspects of NO2 impacts analysis, such as intermittent emissions; in-stack ratio;
ambient ratio; background ozone analysis; and NOX-to-NO2 conversion.
 Ambient air monitors. How to select and calculate representative background
monitor concentrations. Examples of representative; justification; design value; and
background air quality are provided.
Summary
The TCEQ mission is to protect our state's public health and natural resources
consistent with sustainable economic development. To meet our clean air goal, the Air
Permits Division works closely with applicants to issue permits that balance regulatory
requirements with economic growth.
We are struggling now but look forward to participating with the EPA to improve the
modeling process.
The following are the key points to remember:
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The permitting process has changed and more changes are likely;
New standards create technical challenges for you and us;
Help us help you; and
Talk to us early -- and often!
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