# Responses to Significant First-Round Comments on the Draft Guidance Documents on the Implementation of the Exceptional Events Rule

U.S. Environmental Protection Agency

June 2012Draft for Public Notice and Comment
Revision Date: June 2012 2



## Table of Contents

List of Acronyms .............................................................................................................. ............................ 4

List of First-Round Commenters ................................................................................................ .................. 5

A. INTRODUCTION ............................................................................................................... ................. 6

B. RESPONSES TO SIGNIFICANT FIRST-ROUND COMMENTS ON THE EPA’S DRAFT

GUIDANCE DOCUMENTS ON THE IMPLEMENTATION OF THE EXCEPTIONAL EVENTS

RULE .......................................................................................................................... .................................. 7

1. Timing of EER Demonstration Package Submittal and Review ......................................................... 7

1.1. Resource availability .................................................................................................... ............. 7

1.2. Letter of intent ......................................................................................................... ................ 12

1.3. Air agency submittal of demonstration package ..................................................................... 12

1.4. EPA prioritization of submitte d demonstration packages ....................................................... 13

1.5. EPA review and response timeframes..................................................................................... 16

2. Exceptional Event Website .................................................................................................. ........... 19

2.1. Templates for demonstration documents ................................................................................ 19

3. Draft Guidance Documents Still under Development .................................................................... 20

3.1. Exceptional event wildfire / ozone guidance .......................................................................... 20

3.2. Fire Policy .............................................................................................................. ................. 22

3.3. General .................................................................................................................. .................. 23

4. General AQ S Procedures ..................................................................................................... ........... 23

4.1. Data flagging schedules .................................................................................................. ........ 23

4.2. Use of flags ............................................................................................................. ................ 24

4.3. Exclusion of data that do not meet “but for” ........................................................................... 2 6

5. Exceptional Event Data Flagging for Air Quality Concentrations that Could Contribute to an

Exceedance or Violation of the National Ambient Air Quality Standards ............................................. 27

6. General Exceptional Events Rule App licability and Implementation Issues .................................. 28

6.1. Guidance versus rule ..................................................................................................... .......... 28

6.2. Public availability of demonstrations and associ ated EPA decisions ..................................... 30

6.3. Mitigation requirement s of 40 CFR 51.930 ............................................................................ 33

6.4. Reasonable controls for sources outside of state/local/tribal jurisdiction ............................... 33

6.5. Other .................................................................................................................... ................... 35

7. Guidance Specific to High Wind Dust Events ................................................................................ 39

7.1. Definition of “event” for high wind dust events ..................................................................... 39

7.2. Conceptual model ......................................................................................................... .......... 39

7.3. High wind threshold ...................................................................................................... .......... 40Draft for Public Notice and Comment
Revision Date: June 2012 3

7.4. Recurrence ............................................................................................................... ............... 50

7.5. Reasonable controls ...................................................................................................... .......... 55

7.6. Historical fluctuations .................................................................................................. ........... 72

7.7. High Wind Action Plan .................................................................................................... ....... 73

7.8. Checklist for demonstration submission ................................................................................. 7 6

7.9. Recommended framework for high wind dust exceptional event demonstration package ..... 76

7.10. General ................................................................................................................. ............... 77

8. Treatment of Technical Criteria for Excl usion of Data Affected by Events ................................... 80

8.1. Not reasonably controllable or preventable ............................................................................ 80

8.2. Natural event ............................................................................................................ ............... 81

8.3. Clear causal relationship ........................................................................................... .............. 81

8.4. Historical fluctuations .................................................................................................. ........... 82

8.5. But for .................................................................................................................. ................... 83Draft for Public Notice and Comment
Revision Date: June 2012 4



## List of Acronyms

AAQ Affects Air Quality

ADEQ Arizona Department of Environmental Quality

APCD Air Pollution Control District

AQS Air Quality System

BACM Best Available Control Measures

BAM Beta Attenuation Monitor

BMP Best Management Practices

CAA Clean Air Act

CAPCOA California Air Pollution Control Officers Association

CARB California Air Resources Board

CCR Clear Causal Relationship

CFR Code of Federal Regulation

CO Carbon Monoxide

EE Exceptional Event

EER Exceptional Events Rule

EPA Environmental Protection Agency

GRIC Gila River Indian Community

HAURL Human Activity Unlikely to Recur at a particular Location

HF Historical Fluctuations

HWAP High Wind Action Plan

HYSPLIT HYbrid Single-Particle Lagrangian Integrated Trajectory

MAG Maricopa Association of Governments (Arizona)

MM5 Pennsylvania State University / National Center for Atmospheric Research Mesoscale
Model

mph Miles Per Hour

nRCP not Reasonably Controllable or Preventable

NAAQS National Ambient Air Quality Standards

NACAA National Association of Clean Air Agencies

NAM North American Mesoscale Model

NASA National Aeronautics and Space Administration

NEAP Natural Events Action Plan

NEBF No Exceedance But For the event

NOAA National Oceanic and Atmospheric Administration

NO

x Nitrogen Oxides

NWCG National Wildfire Coordinating GroupDraft for Public Notice and Comment
Revision Date: June 2012 5

NWS National Weather Service

OAQPS Office of Air Quality Planning and Standards (U.S. EPA)

PM Particulate Matter

Q&A Question and Answer

QA/QC Quality Assurance/Quality Control

RACM Reasonably Available Control Measures

SIP State Implementation Plan

UNLV University of Nevada, Las Vegas

USDA United States Department of Agriculture

USFS United States Forest Service

VOC Volatile Organic Compounds

WESTAR Western States Air Resources Council

WOE Weight-of-evidence

WRAP Western Regional Air Partnership

WRF Weather Research and Forecasting Model



## List of First-Round Commenters

1. Chattanooga-Hamilton County Air Pollution Control
2. Torres Martinez Desert Cahuilla Indians 3. City of Albuquerque
4. California Air Pollution Control Officers Association
5. Great Basin Unified Air Pollution Control District 6. Pinal County (Arizona) Air Quality - comments from Mr. DiBiase 7. Santa Barbara County Air Pollution Control District
8. California Air Resources Board 9. South Coast Air Quality Management District 10. Gila River Indian Community 11. San Joaquin Valley Air Pollution Control District 12. Imperial County Air Pollution Control District

13. WESTAR 14. Clark County (Nevada) Department of Ai r Quality and Environm ental Management 15. Maricopa Association of Governments

16. NACAA 17. Sacramento Metropolitan Air Quality Management District 18. State of Wyoming 19. Placer County (California) Air Pollution Control District 20. North Carolina Department of Environment and Natural Resources - Division of Air Quality 21. BP America Production Company 22. San Luis Obispo County Air Pollution Control District 23. Arizona Department of Environmental Quality 24. Georgia Air Protection Branch 25. Pinal County (Arizona) Air Quality - comments from Mr. Gabrielson 26. Washington Department of Ecology 27. Intertribal Council of Arizona, Inc. 28. Pete Lahm, USDA Forest ServiceDraft for Public Notice and Comment
Revision Date: June 2012 6



## Responses to Significant First-Round Comments on the Draft Guidance Documents on the Implementation of the Exceptional Events Rule

A. INTRODUCTION On May 2, 2011, the U.S. Environmental Protecti on Agency (EPA) released draft guidance on the implementation of the Exceptional Events Rule (EER ). The released draft guidance documents included the “Draft Guidance to Implement Requirements for the Treatment of Air Quality Monitoring Data Influenced by Exceptional Events” (the Overview document), the “Draft Exceptional Events Rule Frequently Asked Questions” (the draft Q&A docum ent), the “Draft Guidance on the Preparation of Demonstrations in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds under the Exceptional Events Rule” (the draft High Winds Guidance document), and the “Request for Comments on the Draft Guidance Documents on the Impl ementation of the Exceptional Events Rule” (the Request for Comments document). Together, these dr aft documents were intended to clarify key provisions of the 2007 Exceptional Events Rule (EER) and respond to questions and issues that stakeholders have raised since the EPA promulgate d the rule. The EPA provided the draft guidance, along with examples of approved dem onstrations on the EPA’s website (http://www.epa.gov/ttn/analysis/exevents.htm), to state, local, and tribal agencies, etc. and to other parties as requested, to solicit comment and help ensure that the EPA’s final guidance provides an efficient and effective process to make determinations regarding air quality data affected by events.

This document, together with the revised draf t guidance documents identified above, presents the EPA’s response to the 28 commenters who subm itted numerous comments on the draft guidance documents. The EPA has addressed all significant issu es raised during the initial comment period ending on June 30, 2011.

As reflected in the Table of Contents, the EPA or ganized the responses by the specific draft guidance document, where appropriate, or by general issues that transcend the three revised draft guidance documents. The EPA responses presented in this docum ent explain the changes incorporated into the revised draft guidance documents or address comments th at did not result in changes in the revised draft guidance documents.

At this time, as indicated in previous communicati ons with reviewers, the EPA intends to solicit comments on the revised draft guidance documents by publishing a Notice of Availability with a 60-day comment period in the Federal Register. Following th is comment period, the EPA will determine whether to pursue issuing final guidance or final guidance as an interim step prior to revising the Exceptional
Events Rule.

The EPA intends to follow the revised draft gui dance during the review and document finalization process because we believe it is consistent with th e Exceptional Events Rule and the guidance already provided in the preamble to the rule.Draft for Public Notice and Comment
Revision Date: June 2012 7

B. RESPONSES TO SIGNIFICANT FIRST-ROUND COMMENTS ON THE EPA’S DRAFT

GUIDANCE DOCUMENTS ON THE IMPLEMENTATION OF THE EXCEPTIONAL

EVENTS RULE

1. Timing of EER Demonstration Package Submittal and Review

1.1. Resource availability

1.1.1. Comment: “There is a discrepancy between what a large agency and a small agency are able to do for documentation for exceptional ev ents. On some past events, large agencies in the southeast have put 4 to 7 people wo rking full-time on an ev ent package. A small agency usually has one person working part -time on the package. A small agency does not usually have a meteorologist on staff or modeling capability....In some ways it has become a competition between agencies, and small agencies do not have the personnel or the financial resources to provide the sam e amount/types of documentation as a large agency.” Specific reference to guidance text: none Submitter: Kathy Jones, Air Monitoring Mana ger, Chattanooga-Hamilton County Air Pollution Control, 423-643-5970, jones_kathy@mail.chattanooga.gov

Date: 5/18/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA recognizes the challenges that air agencies 1 face in preparing exceptional event demonstration packages. The EPA also recognizes the limited resources of the agencies that prepare and submit exceptional event demonstration packages and of the EPA regional offices that review these demonstration packages. One of the EPA’s goals in developing excepti onal event implementation guidance is to establish clear expectations to enable affected agencies to better manage resources as they prepare the documentation required under the EER. The EPA expects submitters to prepare and submit the appropriate level of s upporting documentation, which will vary on a case-by-case basis using the weight-of-evi dence approach. The EPA’s draft guidance documents and the exceptional events website (http://www.epa.gov/ttn/analysis/exevents.htm) present examples to illustrate specific points and are not necessarily required for a ll demonstrations. The EPA further expects the resources required to prepare (and review) packages to decrease as we continue to identify ways to streamline the process and c ontinue to build our database of example demonstrations and analyses. In addition, the EPA acknowledges that certain extreme exceptional event cases may require more limited demonstration packages.

1.1.2. Comment: “Given the limited staff resources at the state, local, and federal levels, EPA must establish guidance that streamlines a nd focuses exceptional event documentation on the factors necessary to make defensible determ inations that comply with the Exceptional
Events Rule. We recommend that EPA work cl osely with CAPCOA and other state/local agencies to closely review and develop doc umentation guidance that is reasonable and consistent with prior approved exceptional events and the Exceptio nal Events Rule.” Specific reference to guidance text: none Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: The EPA will continue to work with state, local, and tribal air agencies as we finalize the guidance documents. As part of an upcoming public comment process, the

1 References to “air agencies” are meant to include state, local, and tribal air agencies responsible for implementing
the EER.Draft for Public Notice and Comment
Revision Date: June 2012 8

EPA will solicit feedback on a series of ques tions, some of which will seek specific, broadly applicable, streamlining mechanisms.

1.1.3. Comment: ... in light of likely adoption of a mo re stringent federal ozone standard expected to drastically increase the number of non-attainment areas across the nation, EPA needs to give serious consideration to streamlining the guidance and the information required for demonstration submittals. It is equally important that EPA implement all necessary steps to assure EPA staff review submittals in a timely manner, especially those that affect attainment designations. In advance of the release of the wildfire exceptional events guidance, we also su ggest EPA step back to reflect on how streamlining measures can be worked into that guidance. Specific reference to guidance text: none Submitter: Brian Shafritz, Santa Barbara County Air Pollution Control District, ShafritzB@sbcapcd.org

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA will continue to work with state, local, and tribal air agencies as we finalize the guidance documents. As part of an upcoming public comment process, the EPA will solicit feedback on a series of ques tions, some of which will seek specific, broadly applicable, streamlining mechanisms. The EPA has not adopted the more stringent ozone National Ambient Air Quality Standards (NAAQS) referred to in the comment, and intends to complete its rec onsideration of the 2008 ozone NAAQS as part of the current five-year review.

1.1.4. Comment: It appears that EPA assumes that governmental entities with a large number of technical staff and other sophisticated t echnical resources will implement the guidance. These resources support air quality programs that have been in place for forty years or more. Although the Gila River Indian community (GRIC) air quality program has as much, if not more, resources devoted to protection of air quality as any tribe, it cannot match the resources in states and political subdi visions of states. Unfortunately, what is assumed to be the minimum level of information and data necessary to make the demonstration required by the guidance is fa r too resource intensive for GRIC or any other tribal environmental program with very limited staff and limited finances....it
assumes that there are mechanisms available to gather the required evidence. ...to devote the resources necessary to obtai n the evidence would require shifting the Community air quality effort away from permits, permit comp liance and ensuring regulatory compliance.
We do not believe that such a shift would be consistent with the highest and best use of our limited resources....An example of why the assumption as to necessary resources is problematic is the level of effort necessary to demonstrate that an event was not reasonably controllable or preventable [GRI C’s letter identifies the example components in the High Winds Guidance document and then says it does not have the resources to prepare a conceptual model, technical information for all six elements, time series graphs, etc. GRIC says that the examples provided are “complex” and “extensive.”] Specific reference to guidance text: High Winds Guidance document
Submitter: Leroy Williams (Environmental Engineer) for William Rhodes (Governor), Gila River Indian Community, williams@gilanet.net

Date: 6/23/2011 via letter to Gina with cc e-mail to EEGuidanceComments@epa.gov Response: The EPA’s guidance documents apply unif ormly to state and local air quality agencies and to tribal agencies that have im plemented air quality monitoring networks or have authority to implement air quality programs. We recognize that resources vary among agencies and we are developing exceptional event implementation guidance to establish clear expectations to enable affected agencies to better manage resources as they prepare the documentation required under th e EER. The EPA’s draft guidance documents and the exceptional events website (http ://www.epa.gov/ttn/analy sis/exevents.htm)Draft for Public Notice and Comment
Revision Date: June 2012 9

present examples and tools to assist submitting agencies prepare demonstration packages. The EPA further expects the resources require d to prepare (and review) packages to decrease as we continue to identify ways to streamline the process and continue to build our database of example demonstrations and analyses.

1.1.5. Comment: Overall, the District is concerned that the draft guidance released by EPA will require significant additional, potentially una vailable resources to prepare documentation for exceptional events, and will subsequently require additional EPA resources for the
review of this documentation. The District notes that EPA’s draft guidance documents include “requirements that appear to go beyond the EER...[and create] additional requirements [such as] a comprehensive contro l analysis that includes back trajectories indicating specific sources in the upwind area, an inventory of the contribution for the significant sources, and detailed descripti ons of controls and their effective implementation and enforcement....” The Di strict recommends that EPA undertake a comprehensive review of its draft guidan ce and prior exceptional event approvals to develop revised guidance that provides fo r reasonable, robust, and streamlined exceptional event documentation.” Specific reference to guidance text: none Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: One of the required elements that air agencies must demonstrate under the Exceptional Events Rule for the EPA’s conc urrence is whether the event was “not reasonably controllable or preventable.” Becau se neither the Clean Air Act nor the EER defines “reasonable,” the EPA provides example factors in the revised draft High Winds Guidance document that air agencies can cons ider when determining the reasonableness of controls. The EPA notes that the presented factors are examples to illustrate specific points and not requirements for all demonstrations.

1.1.6. Comment: “The draft guidance, other backgroun d documents, and examples provided on EPA’s website imply a level of expertise and resources that is simply not available in some State and local agencies, underscoring th e importance of differentiating the simple cases from the more complicated. In this rega rd, a means of dispute resolution can reduce repeated requests for additional information where little gain may be realized. In any event, clear communication between EPA and th e State on what is needed to approve a particular request is essential so that Stat es can make informed decisions about whether
to commit the resources to the task.” Specific reference to guidance text: none Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA’s draft guidance documents and the exceptional events website (http://www.epa.gov/ttn/analysis/exevents.htm) present examples to illustrate specific points. The example analyses and level of rigor are not necessarily required for all demonstrations. The EPA encourages subm itting agencies to use the review and prioritization process identified in the draf t guidance documents and to communicate with the reviewing EPA regional office to dete rmine the appropriate level of rigor needed for a complete demonstration package. As part of an upcoming public comment process, the EPA will solicit feedback on a series of qu estions, some of which will seek specific, broadly applicable streamlining mechanisms.

1.1.7. Comment: “Various requirements in the draft guidance and related documents, as well as the examples EPA provides on its website, assume a level of expertise and resources that some states and localities do not have. Accordingly, it is extremely important forDraft for Public Notice and Comment
Revision Date: June 2012 10

EPA to distinguish between the more strai ght-forward cases and the more complex and to communicate clearly to states and localities what their exceptional events demonstration package must include in order for a particular request to be approved, thus allowing them to determine whether and how they will proceed.” Specific reference to guidance text: none Submitter: Tad Aburn (Co-Chair), NACAA Criteria Pollutants Committee

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA’s draft guidance documents and the exceptional events website (http://www.epa.gov/ttn/analysis/exevents.htm) present examples to illustrate specific points. The example analyses and level of rigor are not necessarily required for all demonstrations. The preamble to the Excepti onal Events Rule at 72 FR 13569 recognizes that the weight-of-evidence approach means that in straightforward cases agencies may
submit less information/evid ence whereas complex events will likely require more documentation. The EPA encourages submitting agencies to use the review and prioritization process identified in the draf t guidance documents and to communicate with the reviewing EPA regional office to dete rmine the appropriate level of rigor needed for a complete demonstration package. As part of an upcoming public comment process, the EPA will solicit feedback on a series of qu estions, some of which will seek specific, broadly applicable, streamlining mechanisms.

1.1.8. Comment: Given the limited staff resources at the state, local and federal levels, EPA
must establish future rule revisions th at streamlines and focuses exceptional event documentation on the factors necessary to make defensible determinations that comply with the Exceptional Events Rule. Specific reference to guidance text: none Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control District

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: As part of an upcoming public comment process, the EPA will solicit feedback on a series of questions, some of which will seek specific, broadly applicable, streamlining mechanisms.

1.1.9. Comment: Georgia states that EPA should strive for a more streamlined approach for state submittals. Georgia further notes that the EPA’s responses in the draft Q&A document do not reflect streamlining. Specifically, Question 24 says that states need to present information to support their claim that emissions from wildfires are “not reasonably controllable or preventable.” Geor gia believes this requirement is ambiguous and puts the demonstration burden back on the state. Georgia believes that states should not have to provide information to suppor t that wildfires are not controllable or preventable. Specific reference to guidance text: Q&A document #24
Submitter: Jac Capp (Chief, Air Protection Branch), Georgia Environmental Protection
Division

Date: 7/1/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA recognizes that emissions from wildfires are generally not reasonable to prevent or control. The EPA u ses “generally” in this statement because the current United States Forest Service (USFS) definitions of “wildfire” and “prescribed fire” define these events in terms of purpo se and deliberateness of ignition. Based on the USFS definitions, a wildfire may have starte d from an unintentional ignition, but the land manager may have allowed the fire to con tinue to burn although it could have been extinguished. In such a case, some of the explanation of the reasonableness of this decision is needed. Similarly, a prescribed fire might be one that could have been prevented but would be unreasonable to not undertake.Draft for Public Notice and Comment
Revision Date: June 2012 11

The EPA’s expectation is that air agencies identify the origin and evolution of the wildfire in simple terms when documen ting the “not reasonably controllable or preventable” criterion in their demonstrati on submittal. Fires started by lightning, volcanoes, unauthorized activity, or accide ntal human-caused actions are unplanned and unwanted fires and; therefore, despite ef forts to prevent or control such fires 2 the emissions may not be reasonably controllable or preventable. In these cases, it is often sufficient for agencies to provide a statement such as the following to document the “not reasonably controllable or preventable” criterion: “Based on the documentation provided in [section X] of this submittal, [lightni ng] caused the unplanned, unwanted wildfire event. The responsible agencies did their reas onable best to control the extent of and extinguish the fire by taking the following actions [insert list or description of actions taken]. Therefore, emissions from this fi re were ‘not reasonably controllable or preventable.’” Emissions from intentionally i gnited fires and escaped prescribed fires that burners allow to burn require additional supporting documentation to demonstrate the “not reasonably controllable or preventabl e” criterion. In these cases, the submitting agency must explain how the fire escaped or why the land manager allowed the fire to burn. Although the EPA expects to discuss the i ssue of control/prevention of wildfires in future guidance, the EPA also addresses this question in the draft Q&A document.

1.1.10. Comment: In the response to Question 24, the EPA should make it clear that a mitigation plan is not needed for wildfire s. The EPA should also provide examples of
information that states should submit to demonstrate that wildfire emissions are not reasonably controllable or preventable. Specific reference to guidance text: Q&A document #24
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The Exceptional Events Rule does not contain a requirement to submit a mitigation plan for any type of event, and the EPA is not creating such a requirement with this guidance. Air agencies must take m itigation actions, but no plan is required. In every event demonstration package, an air ag ency must demonstrate that the event was not reasonably controllable or preventable. See the response to comment 1.1.9. for additional information regarding demonstr ation examples for the “not reasonably controllable or preventable” criterion for wildfires.

1.1.11. Comment: “[Studies] show that the stratosphe ric contribution to surface ozone is significant and can lead to exceedances of the ozone NAAQS for a large area.” EPA should allow states to work together on dem onstration submittals to conserve resources. EPA requires separate demonstrations when the same pollutant and event result in exceedances of multiple NAAQS (e.g., differe nt averaging periods). The averaging period should not matter. “Re quiring multiple submittals for the same pollutant is only adding unnecessary work for the states and EPA.” Specific reference to guidance text: none Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA encourages states and air agencies to coordinate with each other in compiling demonstration package components, and these agencies may submit some of the same data and analyses when a single event affects multiple jurisdictions. Each NAAQS exceedance, however, will likely have some unique properties (e.g., unique monitoring locations, different surrounding and potentially contributing sources with

2 Prevention/control efforts could include posting High Fire Danger signs to make people more careful and prevent accidental fires, or taking reasonable actio n to contain a fire once it has started.Draft for Public Notice and Comment
Revision Date: June 2012 12

varying levels of control, different historical concentration patterns, etc.). States/agencies need to address these unique characteristics in individual submittal packages. Similarly, where a single event results in exceedances of multiple NAAQS (e.g., annual and 24-hour PM), the submitting agency needs to ad dress the unique features of each NAAQS exceedance or violation (e.g., potentially different monitoring locations, different historical concentration patterns). An air agency could submit a single demonstration package for a single event affecting multip le NAAQS provided the air agency clearly identifies the unique characteristics of each NAAQS.

1.1.12. Comment: “Tribes do not have the level of techni cal staff that more developed state and county air quality programs have. Even the mi nimum demonstration expectations are too
resource intensive for tribes to fulfill on th eir own. Tribes do not have the budgets to fulfill the required expectations for excluding exceptional events data. Tribes request that EPA work with them through the demonstrati on process; providing assistance in the form of expertise, direct technical assistance and funding.” Specific reference to guidance text: none Submitter: John R. Lewis (Executive Director), Inter Tribal Council of Arizona, Inc.

Date: 7/15/2011 via e-mail to Beth Palma and Rhea Jones Response: The EPA’s guidance documents apply un iformly to state and local air quality agencies and to tribal agencies that have im plemented air quality monitoring networks or have authority to implement air quality programs. We recognize that resources vary among agencies. In general, the EPA will not prepare analyses or additional arguments to be included as components in a submitted de monstration package. Rather, the EPA will recommend demonstration package improveme nts to the submitting agency. However, the EPA may either assist with or independe ntly prepare supporting analyses that could become part of the submission package or an EPA-prepared technical support document if a demonstration package is associated w ith an imminent regulatory action and the EPA’s action will best serve the public interest. Analyses prepared by the EPA could support either approval or disapproval of an air agency’s request for concurrence on flagged data.

1.2. Letter of intent

1.2.1. Comment: “When agencies have submitted letters of intent, EPA in several regions has briefly evaluated the “dates” listed in the inte nt letter, denied the event, and never looked
at the documentation that followed....There s hould be no denial of an event based on the
“dates” submitted in the letter of intent.” Specific reference to guidance text: Overview document, page 4
Submitter: Kathy Jones, Air Monitoring Mana ger, Chattanooga-Hamilton County Air Pollution Control, 423-643-5970, jones_kathy@mail.chattanooga.gov

Date: 5/13/2011 via e-mail to EEGuidanceComments@epa.gov Response: A letter of intent is an option for an air agency to use in situations where it may help communication and prioritization. It is not a requirement, and may not be useful in every case. The EPA will generally give pr iority to exceptional event determinations that affect near-term regulatory decisions. Under the revised draft guidance, the EPA intends to respond to such a letter within 60 days, thus allowing an agency to prioritize resources for those packages that the EPA inte nds to review in the near-term. The EPA response will provide the regional office’s best assessment of the priority that can be given to the submission once received and an y case-specific advice the EPA may have to offer for the preparation of the demonstration.

1.3. Air agency submittal of demonstration package

1.3.1. Comment: “...supplemental information must be provided back to EPA as required in the review letter "typically be 60 days from receipt of the letter from EPA." DependingDraft for Public Notice and Comment
Revision Date: June 2012 13

on the information request from EPA, the Ag encies may need more time to obtain this data. The District is requesting that language be included to allow this time frame to be negotiated on a case-by-case basis depending on the type of information being requested by EPA.” Specific reference to guidance text: High Winds Guidance document, page 28
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA is willing to work with agencies on timeframes for supplying supplemental information. The mandatory tim ing of EPA actions may limit the response time the EPA allows. The revised draft gui dance documents indicate this willingness.

1.4. EPA prioritization of submitte d demonstration packages

1.4.1. Comment: “EPA acknowledges the resource intensive process surrounding the preparation and submittal of demonstration packages but the guidance fails to explain EPA’s process and intention on handling the t housands of submittals that have been submitted prior to this draft guidance being released that may have an impact on agency planning efforts. EPA only states that they will be prioritizing review on those submittals that have near term impacts on rule a pprovals or SIP submittals. How will those submittals that do not rise to this prioritization level be handled? Will there be an effort to establish an amnesty on those submittals? CAPCOA would like to see a clear explanation on how EPA will be handling those types of submittals and on what timeline.” Specific reference to guidance text: none Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: The Exceptional Events Rule requires air agencies to notify the EPA that exceptional events have influenced data by Ju ly 1 of the calendar year following the year
in which the event occurred. Air agencies complete this notification process by flagging the data in AQS and providing an initial even t description. Although flagging an event provides an initial notification to the EPA of potential exceptional event demonstration submittals, the EPA does not act on an agency’s initial flags. The EPA acts on submitted demonstration packages and, if the EPA concurs with the submittal, the EPA indicates agreement in AQS by concurring with the flag (or flags) identified in the demonstration package. Not all agency-submitted flags in AQS have corresponding exceptional event demonstration submittals; therefore, it ma y appear that the EPA has not acted upon numerous flags. Once an air agency submits a demonstration package, the reviewing EPA regional office will prioritize the package. The EPA will generally give priority to exceptional event determinations that affect near-term regulatory decisions. Prioritization of in-process submittals may change as the EPA promulgates new rules and then makes decisions based on data that may be infl uenced by exceptional events (e.g., new or revised NAAQS, new attainment de terminations).

1.4.2. Comment: Will EPA accept exceptional events pack ages for 2007 and the first half of 2008 events (past the 3-year submittal window ) since it took so long for EPA to develop and release draft guidance? Specific reference to guidance text: none Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: Yes, if the demonstration is associated with a near-term regulatory decision. See response to comment 1.4.1. As indicated in the final area designations for the 2008 ozone NAAQS, the EPA based final area d esignations on air quality monitoring dataDraft for Public Notice and Comment
Revision Date: June 2012 14

from 2008-2010 or 2009-2011, if states early certified these data (See 77 FR 30088 and 77 FR 34221).

1.4.3. Comment: During the June 9, 2011 EPA Region 9 sponsored exceptional events conference call, EPA staff stated that they will pick and choose which exceptional events packages they will review. According to them “If they don’t matter, we won’t act on
them.” What is the purpose of having a rule a nd providing guidance on that rule if EPA does not plan to review some or all submitted packages? Specific reference to guidance text: none Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: This comment is not in the draft guidance documents on which the EPA sought public comment. However, as indicated in the responses to previous comments in this section, not every requested excepti onal event data exclusion has regulatory consequence. The EPA will place lower prio rity on demonstration submittals with no regulatory consequence.

1.4.4. Comment: In offline discussions with EPA, EPA staff have stated that they will not review any exceptional events packages subm itted by certain agencies since according to EPA, a nonattainment designation is a foregone conclusion. However, EPA fails to see the relationship between exceptional events and potential design values and/or episode days associated with planning purposes for St ate Implementation Plans (SIP). This EPA attitude and practice appears to be arbitrary and capricious. Specific reference to guidance text: none Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: This comment is not in the draft guidance documents on which the EPA sought public comment. The EPA does, however, address the subject of this comment in Question 13 of the revised draft Q&A document.

1.4.5. Comment: South Coast Air Quality Management District staff greatly appreciates the efforts to provide guidance that will assist in both the preparation and the timely review of exceptional event documentation. It is our position that Agencies should flag all data that qualifies for exclusion under the Exceptional Events Rule so that the data are treated appropriately in regulatory decisions, progr ess demonstrations and strategic planning for air quality improvement. As such, EPA should review all exceptional events documentation for concurrence regardless of whether a pending regulatory decision hinges on that data. Inaction by U.S. EPA currently lapses to a non-concurrence with time. The proper treatment of data during ex ceptional events affects public perception of air quality and trends, as well as the use proper use of the data by researchers and air quality planners, with ramifications to pla nning of future control strategies and design
values used for attainment demonstrations . Such considerations can extend beyond a simple view of pending regulatory decisi ons. Streamlining the event documentation, along with clear guidance as to what U.S. EPA will consider to concur with an exceptional event, will help everyone involve d.... No submitted events should lapse into nonconcurrence by inaction on U.S. EPA's pa rt. No nonconcurrence decision should be made by U.S. EPA without ample opportunity for discussion with the affected agency and opportunities to provide additional evidence or clarification. Communication through the process is critical. Specific reference to guidance text: High Winds Guidance document
Submitter: Barry Wallerstein, South Coast Air Quality Management District

Date: 6/28/2011 via e-mail to Matt Lakin and EEGuidanceComments@epa.govDraft for Public Notice and Comment
Revision Date: June 2012 15

Response: The EPA developed the draft guidance documents to aid submitting agencies as they internally prioritize and prepare demonstration packages. The EPA encourages submitting agencies to communicate with the reviewing EPA regional office to determine the appropriate level of rigor needed for a complete demonstration package. The EPA hopes that the submittal preparation, submi ssion, and review process becomes more
streamlined and efficient as both submitters a nd the EPA begin adhering to the principles in the draft guidance documents. Initially, this iterative process will require prioritization with higher priority given to exceptional ev ent determinations that affect near-term regulatory decisions. The EPA encourages subm itters to use query functions within AQS to include/exclude all flagged data or only concurred data to conduct “what if” analyses for planning purposes. The AQS scenarios may aid the submitter’s and the EPA’s prioritization efforts.

1.4.6. Comment: EPA has not reviewed or acted on a backlog of Exceptional Event
documentation submittals. The District has e xpended significant resources in developing, compiling, composing, and submitting this documentation to EPA. The District is currently awaiting EPA review for the fo llowing exceptional events: July 4-5, 2007 (PM 2.5 ) Fireworks, October 9 and 30, 2008 (PM 10 ) High Winds, and October 13 and 27, 2009 (PM 10 ) High Winds. The District is currently compiling documentation for an April 11, 2010 (PM 10 ) High Winds. The guidance document does not clearly state if and how EPA will act on past submittals. Specific reference to guidance text: none Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA will generally prioritize exceptiona l event determinations that affect near-term regulatory decisions. The EPA will follow-up with the commenter regarding
the status of the identified submittals.

1.4.7. Comment: “We are impressed with the extent of the existing backlog of unanswered demonstration packages. We would encourage EPA to go beyond acting only on events upon which regulatory actions may be pending. The flagged data, much of which we think would be concurred (and excluded from th e regulatory database) distorts the air quality values that are used for ongoing pla nning and regulatory purposes. It also affects eligibility for Limited Maintenance Plans.” Specific reference to guidance text: none Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA considers eligibility for a Limited Maintenance Plan to be a regulatory concern and would prioritize the related demonstration package. Submitters should clearly identify the Limited Maintena nce Plan regulatory implications in the
demonstration submittal cover letter.

1.4.8. Comment: “In San Luis Obispo County and elsewhere, exceedences caused by Exceptional Events can affect our nonattainment severity classification and pollutant design values that could result in unwarrant ed additional regulatory requirements that would cause negative economic impacts to indu stry. If such exceedances are not deemed exceptional by EPA, industry may be required to implement costly controls that will not solve the problem causing the exceedance. T hus, we believe it imperative that EPA Region 9 review and respond to all Exceptiona l Event submittals and request a definitive answer on whether or not EPA will be acting on San Luis Obispo County APCD
submittals and on what timeline.” Specific reference to guidance text: noneDraft for Public Notice and Comment
Revision Date: June 2012 16

Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control District

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA refers the commenter to Question 13 of the revised draft Q&A
document.

1.5. EPA review and response timeframes

1.5.1. Comment: Perhaps EPA Region 9 can elaborate on the exact internal office flow of exceptional events review a nd concurrence/nonconcurrence. Specific reference to guidance text: none Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: Demonstration package characteristics and prioritization dictate the precise review process and internal office flow. Typi cally, the EPA will prioritize review of the package based on whether it affects near-ter m regulatory decisions and any additional considerations raised by the submitting agen cy. In all cases, multiple regional staff and managers are involved in concurrence and nonconcurrence decisions. Depending on the nature of the event, the location, and the po llutant involved, the EPA review in Region 9 may also include discussions with other EPA regional offices and the EPA headquarters’ staff. Other EPA regional offices follow a similar review and decision-making process for submitted demonstration packages.

1.5.2. Comment: GRIC provides a solution to their general comment that, even with the exceptional event guidance, demonstrations s till require more resources than what GRIC can dedicate. GRIC states that they will file a notice of intent when an exceedance based on QA/QC’d data is attributed to an excep tional event and the Arizona Department of Environmental Quality makes the qualitative j udgment that the exceedance is attributed to an exceptional event. The EPA will then de termine the need for a demonstration based on regulatory significance. If the EPA determin es that the exceptional event will affect a regulatory determination, then “EPA will co llaborate with and assist the Community in preparing the exceptional event demonstrati on. Otherwise, no demonstration will be prepared.” Specific reference to guidance text: High Winds Guidance document
Submitter: Leroy Williams (Environmental Engineer) for William Rhodes (Governor), Gila River Indian Community, williams@gilanet.net

Date: 6/23/2011 via letter to Gina with cc e-mail to EEGuidanceComments@epa.gov Response: The EPA agrees that the commenter’s proposed prioritization process follows the prioritization process identified in th e draft guidance documents. The EPA may choose to either assist with or independently prepare supporting analyses that could become part of the submission package or an EPA-prepared technical support document if a demonstration package is associated w ith an imminent regulatory action and the EPA’s action will best serve the public interest. Analyses prepared by the EPA could support either approval or disapproval of an air agency’s request for concurrence on flagged data.

1.5.3. Comment: “ EPA should accelerate the contemplated timeframes for review and decisions on [submitted exceptional event demonstrations] and not require up to 18 months for Agency review of complete requ ests for treatment of data as an [exceptional event]. ” Specific reference to guidance text: varies (additional documentation to support recommendation is provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf )Draft for Public Notice and Comment
Revision Date: June 2012 17

Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA will strive to review packages in less than 18 months, but the EPA’s
review of some demonstrations may take a full 18 months.

1.5.4. Comment: “Demonstration package submittal and re view - We suggest that the guidance encourage 60 day response period for any EPA request for additional or supplemental information, and request that EPA acknowledge that they will work with state/locals on a case-by-case basis and provide additional ti me for requests, where appropriate...we suggest the following language change to ‘Re quested within timeframe identified by EPA in the initial review letter (step 6). EPA will work with agenci es on a case-by-case basis if additional time is needed to provide the requested supplemental information.’” Specific reference to guidance text: High Winds Guidance document, Section 5.2, EE Demonstrations Action #7, Timing, page 28
Submitter: Larry Greene (Executive Director), Sacramento Metropolitan Air Quality Management District

Date: 6/30/2011 letter via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: The EPA agrees with the commenter and can work with agencies on the timeframes for supplying supplemental information, provided the timing of associated
EPA actions allows for the extended timelines. The EPA has clarified this concept in the revised draft guidance documents. See also response to 1.3.1.

1.5.5. Comment: Wyoming Air Quality Division supports the identified review timeframes. Specific reference to guidance text: none Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

1.5.6. Comment: The North Carolina Division of Air Quality believes that submitting a data exclusion package within 12 months of th e event occurrence may not be possible in
situations where the basis of the exclusion is violating an annual standard or a 3-year design value. For example, in the case of an annual standard, one needs all 12 months of data to know what the annual average is going to be. If the event occurred during first quarter of the year, the necessary data to calculate the annual average may not be available until the end of the first quarter of the following year. Thus, the state could not notify the EPA of its intent to submit a data exclusion package until possibly 15 months
after the event occurrence.

EPA also needs to provide guidance for th e schedule for excluding exceptional event influenced data that result in violations of 3-year design values. The state may not know that data influenced by an exceptional ev ent caused the design va lue exeeedance until 3 years after the event occurren ce. How should the states handle these types of situations?
When should the letter of intent be su bmitted and when should the demonstration package be submitted in these types of cases? The EPA should provide more guidance in Attachment 1 Section C Exceptional Event Data Flagging Schedules on how states should go about flagging and excluding a data point that only meets the criteria to be excluded after the deadline of July 1 of the calendar year following the datum year. Specific reference to guidance text: Overview guidance document, page 4
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA acknowledges the possible occurre nce of the scenario identified in several parts of the comment. The Excepti onal Events Rule and the draft guidanceDraft for Public Notice and Comment
Revision Date: June 2012 18

documents provide timeframes for the separate and distinct tasks of initial event flagging
and for demonstration submittals. The EPA w ill review data submitted outside of these timeframes where the air agen cy presents good reason for a “late” submittal. Adherence
to timeframes is more critical with near-ter m, nondiscretionary regulatory action, such as an initial designation under a new or revised NAAQS.

1.5.7. Comment: 60 days to provide complicated supplemental information (e.g., modeling) is insufficient. San Luis Obispo County APCD recommends at least a 120-day timeframe for complicated analyses. Specific reference to guidance text:
Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control District

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA agrees that in some limited instances a 60-day response time may be insufficient. The EPA is willing to work with agencies on timeframes for supplying supplemental information when the ag encies present good reason to do so. The mandatory timing of EPA actions may limit the response time the EPA allows. The revised draft guidance documents indicate this willingness.

1.5.8. Comment: Georgia states that EPA’s use of the word “intends” when referring to EPA’s anticipated review timeframes (120 days and 18 months) does not “reflect a strong commitment...to work towards a timely resolution.” Specific reference to guidance text: Q&A #27
Submitter: Jac Capp (Chief, Air Protection Branch), Georgia Environmental Protection
Division

Date: 7/1/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA and air agencies are working towards the timely resolution of prioritized exceptional event demonstrati on submittals. Limited resources and changing regulatory promulgation dates create a need fo r flexibility for both air agency information submittal timeframes and for the EPA respon se timeframes. The EPA believes the word “intends” appropriately characterizes our desire for an expedient process.

1.5.9. Comment: Arizona Department of Environmental Quality (ADEQ) offers the following suggestions regarding the prioritization a nd response process identified in the draft guidance documents. ADEQ questions the valu e of the Letter of Intent given the requirement to provide initial descriptions by July 1. If EPA determines that a Letter of Intent is needed, ADEQ recommends that the letter be submitted annually, not after each

event occurs so as to eliminate unnecessary work.

“During a May 11, 2011, briefing EPA indicated that up to five people, including other regions would be responsible for reviewi ng each exceptional event demonstration. ADEQ
contends that this amount of review will lead to unnecessary delay and recommends that the number of layers of review be reduced to three including: the assigned staffer, the staff supervisor, and a coordi nating manager in each EPA regional office. Issuance of a guidance document to the Regions should be sufficient to ensure consistency between EPA regional offices in handling exceptional events.”

“ADEQ also requests that the concept of regul atory action in draft Section 5 "if needed for regulatory action" include determinations of eligibility and continuing eligibility for Limited Maintenance Plans as well as Clean Data Findings.”Draft for Public Notice and Comment
Revision Date: June 2012 19

ADEQ questions EPA’s need for 18 months to make a decision on a submittal and suggests 6 months after completeness and decision deadlines. ADEQ also suggests that EPA add these deadlines to the EER regulatory text. Specific reference to guidance text: none Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: As the commenter indicates, t he Exceptional Events Rule requires air agencies to notify the EPA that exceptional events have influenced data by July 1 of the calendar year following the year in which th e event occurred. Although flagging an event provides an initial notification to the EPA of potential exceptional event demonstration submittals, the EPA does not act on an air agency’s initial flags. The EPA acts on submitted demonstration packages that may follo w the data flagging task by as much as 3 years. It is the EPA’s experience that not all agency-submitted flags in AQS result in corresponding exceptional event demonstrati on submittals. An air agency may flag
numerous data entries and submit demonstra tions for significantly fewer entries. The letter of intent is an option for the air agen cy to use in situations where it may help communication and prioritization. Air agenci es could consider submitting an annual letter
of intent if annual submittal makes sense fo r resource planning or for historically seasonal events. The EPA has clarified this concept in the revised draft guidance
documents.

The commenter notes that the EPA has indicated that up to five people are responsible for reviewing each exceptional event demonstrati on and recommends reducing the layers of review. In most cases, demonstration review consists of the assigned staff, the staff supervisor, and a coordinating manager. Staff review, however, may consist of multiple, parallel reviewers. For example, the regional st aff lead, a modeler, and a technical staffer from another EPA region with particular past wildfire event experience may all simultaneously review a submitted wildfire demonstration submittal. The intent of multiple reviewers is to expedite, rath er than delay, the review process.

The EPA considers determinations of elig ibility and continuing eligibility for Limited Maintenance Plans and Clean Data Findings to be types of regulatory actions that would result in prioritized demonstration submittal packages. The EPA has clarified this in the revised draft guidance documents. The EPA is deferring a decision on whether to include additional air agency or EPA timeframes in regulatory text.

1.5.10. Comment: EPA’s suggested timeframes for subm itting data exclusion packages (within 12 months of the event) and providing supplemental information (60 days) are insufficient. In addition, EPA’s giving itsel f 18 months to make a decision effectively
reduces the allowable time for states. Specific reference to guidance text: none Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA is willing to work with agencies on timeframes for supplying supplemental information. The mandatory tim ing of EPA actions may limit the response
time the EPA allows. The revised draft guidance documents indicate this willingness.

2. Exceptional Event Website

2.1. Templates for demonstration documents

2.1.1. Comment: NCDAQ believed that the EPA would provide a website with tools needed to perform the data exclusion analyses. For exam ple, the existing Data Fed website provides all of the tools (satellite imagery, fire modeling tools, trajectory analysis, multiple datasets, and browser/editor) that the NC DAQ would like to see made available. TheDraft for Public Notice and Comment
Revision Date: June 2012 20

NCDAQ would like to hear comments on the status of the functionality of this website or similar web sites where data exclusion analysis can be performed. The NCDAQ would
also like to see a database established that provided the information needed on prescribed burns and wildfires for preparing excep tional event data exclusion packages. Specific reference to guidance text:
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA has added links to publicly available tools on the EPA Exceptional Events web page at http://www.epa.gov/ttn/analysis/exevents.htm under the heading Publicly Available Support Information and T ools. The EPA will also continue to post examples of successful demonstrations.

2.1.2. Comment: The EPA must develop quantitative crite ria along with efficient protocols and analytical tools for evaluating exceptional ev ents. There are no tools or protocols that have been developed by EPA to assist states in identifying and demonstrating exceptional events other than those developed by Rudy Husar for PM 2.5 /fires ( http://wiki.esipfed.org/index.php/Evid ence_for_Flagging_Exceptional_Events ). The EPA should develop peer-reviewed tools a nd protocols. This would ease the resource burden, expedite the demonstration process, and reduce the subjectiveness of the EPA’s “weight-of-evidence” review. Specific reference to guidance text: none Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA believes that the variability of exceptional events prevents the development of a set of “one size fits all” tools (or quantitative protocols) to support exceptional event demonstrations. The EPA be lieves that our guidance in combination with existing community-based analytical t ools, such as those identified on the EPA Exceptional Events web page at http://www.epa.gov/ttn/analysis/exevents.htm , provides air agencies with the flexib ility needed to develop exceptional event demonstration materials. The EPA will update the Excepti onal Events web page with additional appropriate community tools and examples of successful demonstrations as they become
available.

3. Draft Guidance Documents Still under Development

3.1. Exceptional event wildfire / ozone guidance

3.1.1. Comment: The wildfire event guidance document that the EPA is currently developing should address long-range smoke transport a nd documentation expectations. A satellite picture showing smoke over the location and a Calipso vertical profile showing mixing to the surface and/or a HYSPLIT showing mixing to the surface should be enough. The EPA has previously denied fairly well-docu mented long-range smoke transport events even though NOAA and NASA acknowledge them. Specific reference to guidance text: General comment re ozone/wildfire event methodology
Submitter: Kathy Jones, Air Monitoring Mana ger, Chattanooga-Hamilton County Air Pollution Control, 423-643-5970, jones_kathy@mail.chattanooga.gov

Date: 5/13/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA’s future wildfire / ozone exceptional event guidance document intends to include example applications of satellite imagery and HYSPLIT trajectories. The commenter’s example evidence may satisfy one of the criteria, e.g., the Clear Causal Relationship criteria, in an exceptional even ts demonstration. This same evidence, however, may not be sufficient to meet othe r criteria such as the No Exceedance But For criteria. Without additional supporting inform ation, satellite imagery with a Calipso profile and/or a HYSPLIT trajectory does not show that the measured concentrationDraft for Public Notice and Comment
Revision Date: June 2012 21

would have been below the applicable NAAQS in the absence of the event. Providing an analysis of event and non-event contributions or a seasonal analysis of concentrations might be ways to demonstrate the “but for” prong.

3.1.2. Comment: The EPA has indicated that concurrence on exceptional event demonstrations
for ozone exceedances related to wildfires will be difficult due to several reasons. These include wildfire smoke reducing solar radiati on that is necessary for ozone formation and the fact that wildfires generally occur duri ng the same seasons that exhibit high ozone making it difficult to differentiate betwee n anthropogenic and wildfire precursor emissions. While we agree that wildfires may occur under the same meteorological
conditions that are conducive to higher ozone concentrations , we believe that evidence the EPA has required thus far for exceptiona l event demonstrations is particularly rigorous, burdensome, and res ource intensive. We suggest that the EPA develop a simplified and streamlined approach that stat e and local agencies can utilize as part of the “but for” test in cases relating to potential wildfire impacts on ozone concentrations. A simplified analysis could include the combination of trajectory analyses, satellite imagery and local observations, photogr aphs and news reports. These straightforward and readily available tools should provide adequate evid ence regarding the influence of wildfire
smoke on ozone concentrations. This more st raightforward approach would enable the development of exceptional event demonstrations that are much less onerous than what is suggested by the EPA (modeling, regression an alyses, chemical speciation, etc.) and that would expedite the preparation and review of exceptional event demonstrations related to wildfire impacts. Specific reference to guidance text: Q&A document #6 (page 8)
Submitter: Brian Shafritz, Santa Barbara County Air Pollution Control District, ShafritzB@sbcapcd.org

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: The example evidence identified in this comment may satisfy one criterion of the EER, for example the Clear Causal Relati onship criterion, in an exceptional events demonstration. This same evidence, however, may not be sufficient to satisfy another
criterion and demonstrate the No Exceedance But For criteria. The “but for” criteria requires an analysis showing that the measure d concentration would have been below the applicable NAAQS in the absence of the event. Providing an analysis of event and nonevent contributions is needed to demonstrate the “but for” prong.

The EPA has not specified, and does not inte nd to specify, a particular analysis or approach for any of the required exceptiona l event demonstration criteria. The draft guidance documents and the demonstration submittals posted on the Exceptional Events website contain example analyses prepared to illustrate specific points that may not apply to all exceptional events. The EPA encourag es submitting agencies to use the review and prioritization process identified in the draf t guidance documents and to communicate with the reviewing EPA regional office to dete rmine the appropriate level of rigor needed for a complete demonstration package. As part of an upcoming public comment process, the EPA will solicit feedback on a series of qu estions, some of which will seek specific, broadly applicable, streamlining mechanisms.

3.1.3. Comment: The draft guidance document states that the EPA is developing an Interim Fire Policy and Fire Guidance document; the District requests the opportunity to actively participate in the development of this guid ance. Ideally, this engagement would occur early in the drafting stages so the Distri ct can assist the EPA given our extensive experience in forest fire issues in the San Joaquin Valley Air Basin. Specific reference to guidance text:Draft for Public Notice and Comment
Revision Date: June 2012 22

Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA intends to develop a draft wildfire / ozone exceptional events guidance document and expects using an open process for its development and the development of the document to replace the Interim Air Quality Policy on Wildland and
Prescribed Fires

.

3.1.4. Comment: “We would also like to add a word about another issue of great importance to NACAA members, also related to exceptional events – that of fires. We anxiously await the opportunity to review and comment on dr aft guidance on exceptional events affected by fires and the fire policy itself, which is long overdue, and look forward to having the opportunity to work collaboratively with EPA on this very important issue. In addition, once the fire policy is issued, we request a chance to review again the draft Exceptional Events Rule Frequently Asked Qu estions relative to fire issues.” Specific reference to guidance text:
Submitter: Tad Aburn (Co-Chair), NACAA Criteria Pollutants Committee

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA expects using open processes for policy and guidance development. See response to comment 3.1.3. for additional detail.

3.1.5. Comment: Georgia requests the opportunity to review the ozone/wildfire guidance
document once released. Specific reference to guidance text:
Submitter: Jac Capp (Chief, Air Protection Branch), Georgia Environmental Protection
Division

Date: 7/1/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA expects using open processes for policy and guidance development. See response to comment 3.1.3. for additional detail.

3.1.6. Comment: Washington Department of Ecology requests the opportunity to review the ozone/wildfire guidance doc once released. Specific reference to guidance text:
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of Ecology

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA expects using open processes for policy and guidance development. See response to comment 3.1.3. for additional detail.

3.2. Fire Policy

3.2.1. Comment: Georgia asks to be involved in the development of the Fire Policy Specific reference to guidance text:
Submitter: Jac Capp (Chief, Air Protection Branch), Georgia Environmental Protection
Division

Date: 7/1/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA expects using open processes for policy and guidance development. See response to comment 3.1.3. for additional detail.

3.2.2. Comment: Washington Department of Ecology requests the opportunity to review the Fire Policy once released. Specific reference to guidance text:
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of EcologyDraft for Public Notice and Comment
Revision Date: June 2012 23

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA expects using open processes for policy and guidance development. See response to comment 3.1.3. for additional detail.

3.3. General

3.3.1. Comment: Please clarify the relationship between wildfires and “areas burned by anthropogenic fires.” ADEQ recommends that the EPA recognize that emissions from large scale wildfires are beyond the agency’s control whether or not the initiating event
was natural or human caused. The demonstra tion should not only consider the ignition event but also the other factors (wind conditions , humidity, fuel type, fuel moisture, etc.) that contributed to the extent and progression of the wildfire. Specific reference to guidance text: see also comment at 7.5.19
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Propose Response : The EPA has revised the language in the revised draft High Winds
Guidance document that refers to “areas burne d by anthropogenic fires.” The EPA further recognizes that emissions from wildfires are generally not reasonable to control or prevent. See also the response to comment 1.1.9, which further discusses the EPA’s expectations regarding the “not reasonabl y controllable or preventable” criterion for
wildfires.

3.3.2. Comment: In the response to Question 24 of the Q&A document, please strike “ignited by natural sources” from the sentence that r eads, “Similarly, emissions from wildfires ignited by natural sources are also generally not reasonable to control.” Wildfires are, by definition, ignited by natural sources, making the addition of this language redundant and confusing. Specific reference to guidance text: Q&A#24
Submitter: Pete Lahm (Smoke Manager), USDA Forest Service

Date: 7/14/2011 via phone conversation with Beth Palma Response: The EPA has rewritten the Q&A, which primarily relates to emissions from
natural deserts.

4. General AQS Procedures

4.1. Data flagging schedules

4.1.1. Comment: The guidance is unclear regarding data processing requirements, which appear to conflict with data certification requirements due May 1. ''The placement of flags and the submittal of an initial event d escription should be done concurrently with the submission of data to the AQS database (within 90 days of the end of the quarterly reporting period) but must be done not later than July 1 st of the calendar year following the year in which the flagged measurement occurred." Please provide clarification on how an agency should handle data certification. Specific reference to guidance text: High Winds Guidance document, page 7.
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: Unless the EPA establishes a new schedule for flagging certain data (e.g., as part of a rule), air agencies must submit data flags and an initial event description to AQS no later than July 1 st of the calendar year following the year in which the flagged data occurred. While the EPA encourages flagging prior the May 1 st deadline, flagging is not linked to the AQS data certification schedules. The EPA’s Final Rule on the Treatment of Data Influenced by Exceptional Events; Correction (72 FR 28612) amended 40 CFR 50.14 (c)(2)(i) to make this clarification. The EPA has also revised the text of theDraft for Public Notice and Comment
Revision Date: June 2012 24

referenced bullet in the “Process Requirements per EER” section of the revised draft High Winds Guidance document to reflect this amendment.

4.2. Use of flags

4.2.1. Comment: Wildland Fire Use Fire - US (IU) flag. The draft guidance requires the use of the Wildland Fire Use Fire flag in AQS. The te rm 'Wildland Fire Use' is no longer used or accepted by Land Management Agencies and do es not apply to their current practices. There are only two types of fire: Wildfires and Prescribed fires. The only difference
between the two is how the fire is started: planned verses unplanned. Both types of fire are managed identically. The EPA should consid er identifying an adequate flag to be used to characterize a fire in AQS. Specific reference to guidance text:
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The NWCG (National Wildfire Coordina ting Group) considers fires as either planned ignitions (prescribed fire) or unplanned ignitions (wildfire). However, NWCG recognizes that objectives may change regardi ng the fire’s management throughout the duration of either type of fire. A comprehe nsive demonstration would explain the details of the fire’s management, as well as its i gnition, to address criteria “not reasonably controllable or preventable” and “clear causal relationship.”

To respond to the commenter and to be cons istent with land management agencies, the EPA will eliminate from AQS the Wildland Fire Use Fire – US (“IU”) and (“RU”) flags and the Forest Fire (“E”) flag. The EPA w ill continue to use the following flags to
describe fires:

 IF – Fire – Canadian (Informational Only)

 IG – Fire – Mexico/Central America (Informational Only)

 IM – Prescribed Fire (Informational Only)

 IP – Structural Fire (Informational Only)

 IT – Wildfire – US (Informational Only)

 RF – Fire – Canadian (Request Exclusion)

 RG – Fire – Mexico/Central America (Request Exclusion)

 RM – Prescribed Fire (Request Exclusion)

 RP – Structural Fire (Request Exclusion)

 RT – Wildfire – US (Request Exclusion)

The EPA believes it is appropriate to retain the Fire – Canadian (“IF/RF”) and Fire – Mexico/Central America (“IG/RG”) flags b ecause these flags indicate the jurisdictional origin of the fire (i.e., outside of the subm itting state/outside of the US) rather than the ignition source. The EPA has added a related question on this topic to the revised draft Q&A document.

4.2.2. Comment: The EPA often uses the term "flag." The EPA should make it clear that when they are using the term "flag" they are talk ing about adding "R" data validation codes to the data. The NCDAQ believes the guidance woul d be more helpful if it clearly stated earlier in the document than Question 10 that AQS has two types of data validation codes for exceptional events - "I" data validation c odes and "R" data validation codes and then
describe how each code should be used. The EPA should also state that when they use the term "flag" throughout this document they are referring to "R" data validation codes unless other types of data validation codes are explicitly mentioned. Alternatively, Question 10 could be moved to be before Qu estion 8 and the entire section moved to theDraft for Public Notice and Comment
Revision Date: June 2012 25

beginning of the document. The EPA should also indicate when it is appropriate to turn
an "I" data validation code into an "R" data validation code, and this also harkens back to the last comment which requests more guidance for the schedule for excluding exceptional event influenced data that result in violations of three-year design values.

Contrary to what the EPA says in Question 8, the NCDAQ believes that states should flag any data influenced by an exceptional event w ith an "I" data validation code whether or not the state plans to request the data be ex cluded. Information about whether or not data are influenced by an exceptional event is n ecessary for doing the atypical analysis. If data have been influenced by an exceptional even t and these influences have not been tracked and documented in some way, it may hinder the ability to get data excluded as being influenced by an exceptional ev ent in the future because it w ill bias the data used for the historical fluctuations analysis.

In Question 9 the EPA should make it clear that states can use a reference to a website as the initial description when the "R" data valida tion code is added to AQS. It would also be good if the EPA clarified that initial descriptions are not required for "I" data validation codes. The answer to Question 9 also begs the question of why the states
should have to make the extra effort to s ubmit a letter of intent to the EPA when the answer to Question 9 indicates that the initia l description in AQS serves as the notice to the EPA of an intent by the state to submit a data exclusion package.

Specific reference to guidance text: Q&A Q#8, 9, 10
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA does not require initial descriptions for “I” series data flags, although AQS allows initial descriptions to be included with “I” seri es flags. Air agencies may initially flag data they believe to be in fluenced by an exceptio nal event with an “I” series flag with no associated initial descripti on. Later, the air agency may change the flag to an “R” series flag and add the initial description, but the air agency must do so before July 1 st of the year following the year the data occurred.

An initial description provides a preliminary ex planation of why the air agency believes the accompanying flagged data may be consider ed as affected by an exceptional event. The initial description is a required part of the data flagging process, and it is recorded in AQS with the flags and the data. A letter of intent, on the other hand, is optional and is not part of the AQS record. The air agency may choose to submit a letter of intent to ascertain the EPA’s timetable for reviewing any associated demonstration; this information may be valuable to the air agency in allocating resources.

A reference to a website does satisfy the re quirements of an initial description when an “R” series data flag is used.

The EPA has clarified these points in the revised draft guidance documents.

4.2.3. Comment: The responses to Q#10 and Q#12 in the Q&A document seem to conflict. In Q#12, the EPA says that a state does not have access rights to apply flags to data from monitors operated by the National Park Servi ce or other federal agencies, but that states must work with the agency or seek assistan ce from the EPA regional office. The response to Q#10 says that states should flag data by July 1. “How are states to ensure that the data is flagged by July 1 or by other [applicable deadlines] if they are not allowed to flag the
data themselves?” The EPA should allow States to flag the data for the monitors in their state for which they must prepare the demonstration pack and develop a SIP.Draft for Public Notice and Comment
Revision Date: June 2012 26

Specific reference to guidance text: Q&A #10 and 12
Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: To maintain data integrity, AQS is gene rally designed so that only the agency operating a monitoring site may enter or alter data for that site. Under normal circumstances, an air agency will not have acce ss rights to apply event flags to data from monitors operated by other entities, such as the National Park Service or other state, local, or tribal agencies. When an air agency believes that an exceptional event affected the concentration recorded by monitors oper ated by other agencies, the air agency should contact the agency operating the monitor and request that the operating agency flag the identified data range for exclusion. The a ffected air agency should also develop and forward to the operating agency an initial ev ent description that the operating agency can enter in AQS. If an air agency is unsuccessful in requesting that another agency apply exceptional event flags to that agency’s data, the air agency should contact the EPA regional office. If the EPA regional office is aware of the request, and if the request was prior to July 1 st of the year following the datum year, the EPA will generally still consider the affected air agency’s request. However, this may not always be the case. Air agencies should notify the EPA regional office of such an instance as soon as possible. (Note that the EPA has reordered some of the questions in the revised draft Q&A document in response to commenter suggestions. As a result, Question 10 is now Question 8.)

4.3. Exclusion of data that do not meet “but for”

4.3.1. Comment: The NCDAQ also requests that the guidance be clearer on how states and local programs should handle data impacted by exceptional events that were exceedances
but would have also been exceedances without the exceptional event. For example, the exceptional event caused a value to be 45 but without the exceptional event it would have been 37. Even though this value cannot be excluded for the purposes of determining design values unless it can be shown that it causes the design value to exceed the standard, there should be some way for the states and local programs to be able to exclude these types of data from calculations of statistics made from data sets containing typical data required to demonstrate that the data inf1uenced by the exceptional event are atypical.

Obviously, it should be no problem excluding data influenced by exceptional events where the state has requested the data to be excluded and the EPA concurred. However, there may be some days when the data are influenced by an ex ceptional event but the
criteria to have the data excluded are not met because the hourly or daily value is not high enough to cause an exceedance or violation of the standard or the "But For" test is not met. The NCDAQ believes these data where values are clearly impacted but do not qualify to be excluded should be excluded fro m the historical database used in calculating typical fluctuations used to demonstrate the data meeting the exclusion criteria are atypical. What evidence does the state need to provide to demonstrate to the EPA that the
above stated data are not typical data and should not be considered as typical in the historical fluctuations analysis? Specific reference to guidance text:
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: An air agency may apply “informational” flags to a concentration it believes is influenced by exceptional events even if the air agency knows the concentration is not eligible for exclusion.

The historical fluctuations analysis is releva nt to the “but for” criterion since comparisons to non-event affected days can be a type of evidence for that criterion. Each situation mayDraft for Public Notice and Comment
Revision Date: June 2012 27

be different, so the EPA cannot provide simple universal rules for how an air agency can show whether data were influenced by an ev ent or not, and by how much. However, the types of evidence and techniques used to asses s “clear causal relationship” and “but for” generally should be applicable to showing that an ineligible data point was affected and should not be taken to represent normal air quality.

Since the EPA does not evaluate the historical fluctuations analysis against a threshold, including previously excluded data in the historical database is unlikely to have a negative effect. The preamble to the Excep tional Events Rule states, “The general statistical approach of using all measured data during the past several years is independent of historical flagging practices and allows States to accurately represent events not likely to recur by including all monitoring data in analyses.” 72 FR 13569 (emphasis added).

While air agencies should “use” all historical data points in their analyses, they can present the data as a concentration time series, relative to annual data, or relative to seasonal data (see additional discussion of historical fluctuation analyses in the draft Q&A document). The Exceptional Events web page www.epa.gov/ttn/analysis/exevents.htm contains examples of historical fluctuations analyses that included all measured data . In these examples, the submitting agencies identified and explained high concentration va lues that associated with other events as part of their analyses: Summer 2007 Wildfires: Plumas Demonstration (6/17/09), Fig. 10 EPA Technical Support Document (3/11/10), Table 3, Fig. 6. July 2007 Wildfire: Lindon Demonstration (12/24/07), pp. 16-17

5. Exceptional Event Data Flagging for Air Quality Concentrations that Could Contribute to an Exceedance or Violation of the National Ambient Air Quality Standards
5.1. Comment: In footnote 6 on page 22 of Attachment 1, the EPA states that 5-minute sulfur dioxide data should not be flagged for exclusion because they are not used to compare against a standard. However, states shoul d be allowed to flag 5-minute sulfur dioxide data with informational ("I") data validation codes if they choose to do so. States probably would not
choose to do so because it would be too labor in tensive, however, that option should exist and it should be clear that states have that option.

For several pollutant situations in Table Q30-2, the EPA states, "it is possible for a specific hourly concentration that was not originally conc urred to be concurred as part of the new 8-hour maximum period." How can this be? If the 1-hour co ncentration was in the original 8-hour block that met the criteria for exclusion, the 1-hour c oncentration would have been excluded if it too met the criteria for being excluded. If it did not meet the criteria to be excluded initially and it finds itself in the second 8-hour block being evaluated, even if the second 8-hour block meets the criteria exclusion, the 1-hour value still will not meet the criteria for 1-hour values if it did not meet the criteria initially. It seems what the EPA may really mean is that it is possible for additional hourly concentrations that were not included in the original 8-hour block to be excluded as part of a second 8-hour block. It mi ght be helpful if the EPA actually provided an example of how this type of calculation is performed. Specific reference to guidance text: Q&A footnote 6, Table Q30-2
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.govDraft for Public Notice and Comment
Revision Date: June 2012 28

Response: The EPA agrees with the commenter and has added clarifying language in the revised draft Q&A document to Table Q30-2 and foot note 15 (i.e., footnote 6 in the May 2, 2011 draft Q&A document).

6. General Exceptional Events Rule A pplicability and Implementation Issues

6.1. Guidance versus rule

6.1.1. Comment: “To be clear, we agree on the necessity for clarity and streamlining efforts to ensure that the Exceptional Events Rule is applied consistently. These efforts also enhance the planning agencies’ understanding of the requirements in a submittal package for EPA concurrence. The Exceptional Events Ru le is a useful and needed tool for air agencies in our planning efforts. We also f eel that, while guidance can be helpful, the appropriate mechanism to address the shortcomi ngs of the rule is to work through the formal rule revision process. We believe th e rule revision path more effectively and efficiently establishes clear regulatory language so that actions taken based on the rule will face fewer challenges.” Specific reference to guidance text: none Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: The EPA developed the revised draft exceptional events guidance documents to help air agencies comply with the Excepti onal Events Rule by clarifying the rule requirements. Guidance documents do not change, increase, or decrease rule requirements; they assist by providing information and illustrations for better understanding of and compliance with the ru le. The EPA is deferring a decision on whether to revise exceptional events regulatory text.

6.1.2. Comment: “...the current draft guidance falls short of providing the necessary definitiveness, clarity, and streamlining that was at the crux of this re view and subsequent guidance and/or rule revision. ...While guida nce can be helpful, the Imperial County APCD feels the appropriate mechanism to a ddress the issues surrounding the rule is to work through the formal rule revision process. We believe the rule revision path is more effective in establishing clear regulatory language.” Specific reference to guidance text: none Submitter: Brad Poiriez, Imperial County Air Pollution Control District, bradpoiriez@co.imerial.ca.us

Date: 6/14/2011 via e-mail to Gina McCarthy Response: See response to comment 6.1.1.

6.1.3. Comment: “NACAA is concerned that under the draft guidance, if specific actions are not taken or criteria are not met by states and localities, the request that data be excluded may be denied. Such mandatory requirements appear to cross the line between guidance and regulation. Where requirements are to be established, rulemaking and not guidance is the appropriate administrative process.” Specific reference to guidance text:
Submitter: Tad Aburn (Co-Chair), NACAA Criteria Pollutants Committee

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.1.1. The EPA’s draft guidance documents and the exceptional events website (http://www.epa. gov/ttn/analysis/exevents.htm) present examples to illustrate specific points rather than requirements that all submitters must
follow in all demonstrations.

6.1.4. Comment: “Guidance that has the effect of re quiring specific actions or establishes criteria that, if not met, results in denial of a State’s request for data exclusion is notDraft for Public Notice and Comment
Revision Date: June 2012 29

guidance but is regulation through guidan ce. WESTAR reiterates its view that the appropriate mechanism to address several of the implementation issues addressed in the draft guidance is to revise the regulation.” Specific reference to guidance text: none Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.1.1. The EPA’s draft guidance documents and the exceptional events website (http://www.epa. gov/ttn/analysis/exevents.htm) present examples to illustrate specific points rather than requirements that all submitters must
follow in all demonstrations.

6.1.5. Comment: “The San Luis Obispo County Air Pollution Control District (SLOAPCD) believes the rule revision path would more e ffectively provide regulatory language so that EPA actions, based on the rule, will face fewer challenges.” SLOAPCD expresses specific concern that the guidance adds ne w requirements (e.g., comprehensive control analysis with back trajectory, slide 29 of R9 6/9/11 presentation that “requires” a quantitative “but for” demonstration that the event emissions caused the concentration to exceed the standard). Specific reference to guidance text: none Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control District

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.1.1. The EPA’s draft guidance documents and the exceptional events website (http://www.epa. gov/ttn/analysis/exevents.htm) present examples to illustrate specific points rather than requirements that all submitters must
follow in all demonstrations. The EPA believes that a qualitative demonstration of “but for” may be appropriate for some demonstr ations but also believes that available quantitative approaches provide more a ssurance regarding concurrence.

6.1.6. Comment: Georgia states that the EPA should use the regulatory process which includes public notice and comment versus guidance as the regulatory approach provides the “most open and transparent process for devel oping new requirements and allowing input from co-regulators, regulated sources, and the public.” Specific reference to guidance text:
Submitter: Jac Capp (Chief, Air Protection Branch), Georgia Environmental Protection
Division

Date: 7/1/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA is not introducing new requirements with the draft exceptional event guidance documents. Rather, the EPA ’s draft guidance documents and the exceptional events website (http://www.epa. gov/ttn/analysis/exevents.htm) present examples to illustrate specific points. The le vel of rigor for demonstrations may vary from those in the example analyses dependi ng on various factors such as the type of event, its location, and other factors. As we finalize the exceptional event guidance documents, the EPA intends to pursue a public notice and comment period to allow input from co-regulators, regulated sources, and the public.

6.1.7. Comment: While the draft guidance represents much needed progress, it is ultimately limited in its usefulness, as guidance ca nnot carry the weight of rule. The process described in the guidance is useful for ensuring consistency amongst the EPA regional offices, but it provides little relief for States should the EPA miss a deadline or otherwise fail to follow the process outlined in the guidan ce. In addition, several of the approaches in the EPA's guidance, including proposed changes to the "But For" test and historicalDraft for Public Notice and Comment
Revision Date: June 2012 30

fluctuations appear to require rule re visions before the guidance can be fully implemented. ADEQ maintains that additional rulemaking remains necessary. Specific reference to guidance text:
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA is not introducing new requirements with the draft exceptional event guidance documents. Rather, the EPA’s draf t guidance documents and the exceptional events website (http://www.epa.gov/ttn/analy sis/exevents.htm) present examples to illustrate specific points and are intended to help air agencies comply with the Exceptional Events Rule. The EPA will consider each request to exclude data on its own
merits.

6.1.8. Comment: Pursue rule changes to see full extent of needed changes. Guidance is limited in usefulness. “The current regulatory framewo rk for dealing with exceptional events is not sufficient to deal with the anticipated very large increase in the number of events that will need to be analyzed as a result of re vising the ozone NAAQS into the range of or lower than background levels.... [if] EPA plans to use the EER to handle background caused ozone exceedances under a new NAAQS, th e rule must be revised to include a provision which allows the exclusion of background.” Specific reference to guidance text: none Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: See response to comment 6.1.1.

6.2. Public availability of demonstrations and associated EPA decisions

6.2.1. Comment: Section 5.3 (page 29) of the High Wind document provides for the possibility of public comment. How will the EPA determin e if public comment is required? Great
Basin believes that all efforts to excuse m onitored exceedances of National Ambient Air Quality Standards should include an opportunity for the public to comment. Excluding real health-threatening air pollution from the r ecord, regardless of reason, is not an action that should be handled solely by bureaucrats behind closed doors. Specific reference to guidance text: page 29 of High Winds Guidance document
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: As indicated in the “Public Comments” section of the draft High Winds Guidance document, an air agency may need to provide an additional opportunity for public comment if the EPA requests and/or if the air agency provides supplemental information not included in the original documentation made available for public comment. The EPA will make a case-by-case decision regarding supplemental opportunities for public comment during the de monstration preparation, submittal, and review process. As part of this decision, the EPA may consider potential impact and/or expressed public interest in the claimed event, data uncertainty, historical application of demonstration approach, etc. Additionally, certain regulatory actions that may rely on exceptional event data exclusions (e.g ., proposed designation or redesignation classifications and attainment determinations) require the EPA to provide an opportunity for public comment prior to the EPA’s taking final agency action. The EPA added Question 14a to the revised draft Q&A document to clarify the issue of public comment.

6.2.2. Comment: “The guidance documents do not indicate how agencies can challenge a determination by EPA on the non-concurrence of an Exceptional Event submittal. While we prefer to work through the submittal pr ocess with EPA to address any issue that may arise before submittal, both the air district s and the California Air Resources Board haveDraft for Public Notice and Comment
Revision Date: June 2012 31

submitted what we thought was the require d documentation to show an Exceptional Event only to see that EPA failed to agree. Currently, if EPA makes a finding of nonconcurrence on a submittal, the only recourse left to the planning agency is to wait until that finding affects a formal action taken by EPA on a rule or State Implementation Plan at which time the agency can proceed with a le gal action. In an effo rt to avoid spending precious resources and time on costly litigation processes, we recommend that the guidance document include a mechanism to s eek resolution of disagreement regarding non-concurrence on submittal packages for ex clusions of data due to Exceptional

Events.” Specific reference to guidance text: none Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: Several mechanisms currently exist that air agencies can use at various points in the exceptional events process:

 Engage in early dialogue with the appropriate EPA regional office as issues arise.

 Submit requests for reconsideration to the official who made the determination if a request identifies a clear error or if information submitted by the agency was
overlooked.

 Elevate the concern within the EPA’s chain of command.

 Participate in the public notice and co mment process (see response to comment 6.2.1 and Question 14a in the draft Q&A document).

 Challenge in an appropriate court the re gulatory decision subsequently made that is based on the EPA’s exceptional event determination. In addition, for complex exceptional events clai ms or those with significant regulatory or other impacts (e.g., those claims that di rectly influence proposed designation or redesignation, classifications, and attainment determinations), EPA regional office staff will generally seek input from other EPA re gional offices and/or the EPA headquarters staff. The EPA has also added Question 28a in the revised draft Q&A document to address this dispute resolution comment.

6.2.3. Comment: An appeals process for disagreement on nonconcurrence decisions would be
beneficial. Specific reference to guidance text: High Winds Guidance Document
Submitter: Barry Wallerstein, South Coast Air Quality Management District

Date: 6/28/2011 via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.4. Comment: The Exceptional Events Rule and the guidance documents do not have a mechanism to challenge an EPA non-concurre nce determination on an agency submittal. The only recourse available when the EPA ma kes a finding of nonconcurrence is to wait until the finding impacts a formal action taken by the EPA on a rule or State Implementation Plan. At that time, legal ac tion may be the only recourse available. The District recommends that the EPA provide a mechanism that allows for the appeal and
additional review for determ inations of nonconcurrence. Specific reference to guidance text:
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.5. Comment: “Currently in the draft guidance ther e is no mechanism by which agencies can challenge a determination by EPA on th e non-concurrence of an Exceptional EventDraft for Public Notice and Comment
Revision Date: June 2012 32

submittal. Imperial County APCD would pref er to work through the submittal process with EPA to address any issues that may ari se before submittal, however there are times when both the air district and CARB believe they have fully established the required documentation required to show an Exceptional Event and EPA ultimately fails to agree. As it stands now, if EPA makes a finding of non-concurrence on a submittal, the only recourse left to the air districts is to wait until that finding impacts a formal action taken by EPA on a rule or State Implementation Plan (SIP), at which time the district can proceed with a legal action; this is exactly the position that Imperial County APCD finds itself in right now. In an effort to avoid spending precious resources and time on costly litigation processes, it would be more beneficial to EPA and the air districts and state air agencies if there were a mechanism by which to seek resolution of disagreement regarding non-concurrence on submittal pack ages for exclusions of data due to Exceptional Events.” Specific reference to guidance text:
Submitter: Brad Poiriez, Imperial County Air Pollution Control District, bradpoiriez@co.imperial.ca.us

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.6. Comment: “ WESTAR believes that the guidance sh ould include a section on dispute resolution. While we acknowledge the im portance of having EPA regional office personnel with an understanding of local conditions evaluate exceptional event requests,
we remain concerned about inconsistenc ies between regions in their respective evaluations of substantially similar events. We believe state and local regulatory agencies should have the opportunity to challenge non- concurrence rather than waiting for EPA regulatory action based on event-caused high values. A decision of non-concurrence and a subsequent regulatory action, such as non-a ttainment designation could be separated by several years, resulting in significant dup licative resource expenditure challenging the non-attainment designation while developing a non-attainment SIP to meet the submittal timing requirements.” Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.7. Comment: “Recourse for inaction or denial of an exceptional event request - We suggest the guidance incorporate a conflict resolu tion process to address circumstances where there is no regulatory action associated with EPA's decision, where EPA has not taken action on a request, and to ensure c onsistency among EPA regional offices.” Specific reference to guidance text:
Submitter: Larry Greene (Executive Director), Sacramento Metropolitan Air Quality Management District

Date: 6/30/2011 letter via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.8. Comment: “We are concerned that there is no avenue available to states and localities that wish to challenge an EPA denial of an exceptional events request or a failure by EPA to respond to a request (which equates to a denial of a request for an exclusion in that, absent a decision by EPA, the data will remain in the data set). While we appreciate and value EPA regional office staff knowledge and understanding of local conditions, we are keenly aware of the potential for inconsistenc y between regions in how they evaluate and act upon similar events and circumstances. Therefore, we recommend that EPA establishDraft for Public Notice and Comment
Revision Date: June 2012 33

a process for dispute resolution and would welc ome the opportunity to work with you to design such a process.” Specific reference to guidance text:
Submitter: Tad Aburn (Co-Chair), NACAA Criteria Pollutants Committee

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.9. Comment: San Luis Obispo County APCD recommends the Rule Revision include a
structured mechanism to seek resolution of any disagreement regarding non-concurrence on submittal packages. Specific reference to guidance text:
Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control District

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.2.10. Comment: ADEQ recommends the Rule Revision in clude a structured mechanism to seek resolution of any disagreement regard ing non-concurrence on submittal packages. Specific reference to guidance text:
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.2.2.

6.3. Mitigation requirements of 40 CFR 51.930

6.3.1. Comment: In the response to Question 22, the EPA encourages the submittal of a mitigation plan with the demonstration packag e. What does the EPA expect to see in this mitigation plan? The NCDAQ believes submitting a mitigation plan is not a reasonable requirement for an event that is not expected to reoccur. Specific reference to guidance text: Q&A #22
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: Although the language at 40 CFR § 51.930 requires air agencies to take mitigation steps, the rule does not contain a requirement to submit a mitigation plan for any type of event. The EPA is not creating a submittal requirement with this guidance. We do, however, encourage agencies to s ubmit a mitigation plan for those events expected to recur. If submitted, the EPA will consider the mitigation plan independent of the demonstration package. The EPA will not use the mitigation plan to determine
concurrence or nonconcurrence for the submitte d demonstration package. In every event demonstration package, an air agency must demonstrate that the event was not reasonably controllable or preventable. The EPA has clarif ied this point in Question 22 of the revised draft Q&A document.

6.4. Reasonable controls for sources outside of state/local/tribal jurisdiction

6.4.1. Comment: The draft guidance does not discuss how ev ents that involve in-state transport from sources outside of one county or nonattainment area that cause exceedances at
monitors within another should be handled. ADEQ is concerned that there is currently no EPA methodology or mechanism to deal with these situations and recommends that the EPA include specific guidance on how intra-stat e, interstate, and international transport of air pollution should be addressed. Specific reference to guidance text:
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.govDraft for Public Notice and Comment
Revision Date: June 2012 34

Response: Under the Clean Air Act, the EPA generally considers a state (not including areas of Indian country) to be a single responsible actor. Accordingly, neither the EPA nor the Exceptional Events Rule provides special considerations for intra state scenarios when an event in one county affects air qua lity in another county in the same state, assuming that the event occurs on land subj ect to state authority (versus tribal government authority). For cases involving intrastate transport, the state or local air agency must evaluate whether emissions fro m neighboring (or contributing) counties are not reasonably controllable or preventable. As discussed in greater detail in the draft guidance documents, the assessment of “not r easonably controllable or preventable” is based on existing level of required control, and, for high wind dust events, wind speed and other factors. States and tribes should consult with their EPA regional office early in the development of an exceptional event dem onstration package if they believe that emissions from sources on federally-owned and managed land (e.g., national parks within the state) have been affected by an event in a way that raises issues of reasonable control.

Interstate and international transport events are different than intrastate events. As indicated in the response to Question 23 in the draft Q&A document, the EPA believes it is not reasonable to expect the downwind state (i.e., the state submitting the demonstration) to have convinced the upwi nd country or state to have implemented
controls on sources sufficient to limit event-re lated air concentrations in the downwind state. As with any demonstr ation submittal, the submi tting (downwind) state should sufficiently identify all natural and anthropoge nic contributing sources of emissions (both in-state and out-of-state) to show the causal connection between an event and the affected air concentration values. A submitting state may provide a less detailed characterization of sources in the upwind state or country than of sources within its jurisdiction. After completing the source characterization, the submitting state should assess whether emissions from sources within its jurisdiction (i .e., in-state sources) were not reasonably controllable or preventable. Although the s ubmitting state should also provide available
information on the status of control measur es for emissions from out-of-state sources, the submitting state may determine based on ava ilable information that the implemented
controls on out-of state sources constitute reasonable controls and that the “not reasonably controllable or preventable” criterion is satisfied. When assessing emissions transported from other states or countries, the submitting state can say that it characterized the out of state sources, dete rmined that these sources contributed to the noted exceedance or violation, and determ ined, based on jurisdictional boundaries and other available information, that contributing emissions from the upwind state or country were not reasonably controllable or preventabl e. Submitting states are further required to submit evidence/statements supporting the other exceptional event criteria (i.e., clear causal relationship, but for, human activity unlik ely to recur or a natural event, affects air quality, and historical fluctuations).

The EPA recommends a similar approach to significant out-of-state anthropogenic sources in the case of a mixed natural/anthropogenic event that the submitting state
wishes to consider a natural event of the grounds that all significant anthropogenic sources were reasonably controlled.

As with all exceptional event demonstrations, the EPA will evaluate the information on a case-by-case basis based on the facts of a pa rticular exceptional event including any information and arguments presented in public comments received by the state in its public comment process or by the EPA in a notice-and-comment regulatory action that depends on the data exclusion. This respon se is not intended to discourage states from working cooperatively to plan and apply controls on both sides of a state boundary for
their mutual benefit.Draft for Public Notice and Comment
Revision Date: June 2012 35

In addition to the provisions in the EER, the Clean Air Act provides mechanisms in sections 110(a)(2)(D) and 126 to address intersta te transport issues and mechanisms in section 179(b) to address international transport issues.

6.5. Other

6.5.1. Comment: A Concentration Effect on Design Value but not NAAQS - There are times
when a District cannot meet the “but for” test for an event because the District would have exceeded an applicable NAAQS anyway . The EPA gives two examples that impact
classification and attainment demonstration in the answer to Question 13 in the Q&A document. The EPA states that on a case-by case basis, the EPA may choose to exclude the data from determining design values or attainment classification. The District supports this position since including that event would artificially increase the design values, potentially requiring excess emission reductions or assigning an inappropriate classification. The District requests the EPA to develop a method that will exclude these days from standardized and official reports produced by AQS or other parts of the EPA. Specific reference to guidance text: Q#13 in the Q&A document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The Exceptional Events data flagging, demonstration submittal, and review process provides a retrospective determination of whether emissions from an event contributed to a violation of a NAAQS. Under the Exceptional Events Rule, concurred upon event-affected data are excluded in their entirety from regulatory decisions. The Exceptional Events Rule does not address data handling associated with events that are not considered “exceptional” under the EER. The EPA suggests that air agencies use “informational only” (“I”) flags to identify event-related data not meeting the definition of an exceptional event. Air agencies can ex tract “I” flagged data in AQS reports.

The EPA addresses this issue in Question 13 in the draft Q&A document and intends to further address this topic in the proposed 2008 ozone NAAQS implementation rule. Air agencies should consult with their EPA regional office if they face this situation.

6.5.2. Comment: Need for clear definitions: “CAPC OA believes that the Exceptional Events Rule must have clear definitions throug hout the document and any future guidance documents. For example, the guidance docume nt uses the important term ‘reasonable’ without defining what is ‘reasonable.’ Much of the guidance seems general in nature leaving the assessment and implementation up to interpretation by EPA. The document needs to strike the balance of providing speci fic guidance to the agencies, while retaining the goal of providing EPA with the ability to evaluate each unique case. At this point, the guidance document fails to meet this goal.” Specific reference to guidance text: none Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: The EPA agrees that assessing “reasonable” is not amenable to a prior generally applicable definition. The EPA be lieves, however, that as the EPA decides more exceptional events demonstrations, air ag encies will be able to anticipate what the EPA considers to be “reasonable.” Because “reasonable” varies by location / attainment status, pollutant, contributing sources, and ev ent type, the EPA encourages air agencies to consider developing a High Wind Action Plan or a prospective controls analysis for high wind dust events to reach mutual agreemen t on “reasonable” in advance of an event.Draft for Public Notice and Comment
Revision Date: June 2012 36

6.5.3. Comment: “Imperial County APCD is adamant that there needs to be clear definitions throughout the rule and any potential guidance. Case in point, the heavily relied upon term of "reasonable" is used throughout the guidance document but it is not defined which is counter-productive to providing clar ity. Much of the guidance seems open ended in nature leaving the assessment and implementation up to interpretation by EPA.” Specific reference to guidance text: none Submitter: Brad Poiriez, Imperial County Air Pollution Control District, bradpoiriez@co.imerial.ca.us

Date: 6/14/2011 via e-mail to Gina McCarthy Response: Where appropriate, the EPA has develope d or incorporated definitions into the revised draft guidance documents. In some cases, generally applicable definitions are not appropriate (see the response to comment 6.5.2.).

6.5.4. Comment: “The revised Exceptional Events Rule must have clear definitions. For example, the revised rule and guidance documents should not use the important term “reasonable” without defining what is “reasonable.”.” Specific reference to guidance text:
Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control District

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: Where appropriate, the EPA has develope d or incorporated definitions into the revised draft guidance documents. In some cases, generally applicable definitions are not appropriate (see the response to comment 6.5.2.).

6.5.5. Comment: “The draft guidance includes significant new documentation requirements that appear to be unreasonable and un necessary and should be reconsidered. For example, EPA's request that exceptional ev ent documentation include a comprehensive control analysis that includes a back traj ectory indicating specific sources in the upwind area, an inventory of the contribution for th e significant sources, and detailed descriptions of controls and their implementation and en forcement effectiveness is an excessive requirement that will require extensive staff effo rt to not only prepare, but to ultimately review by EPA. Many of these new requirem ents exceed the Exceptional Events Rule, and add layers of supplemental, unnecessary work to precedent already established through prior EPA approvals of we ll-documented exceptional events.” Specific reference to guidance text: none Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: The EPA’s draft guidance documents and the exceptional events website (http://www.epa.gov/ttn/analysis/exevents.htm) present examples to illustrate specific points. The example analyses and level of rigor are not necessarily required for all demonstrations. The draft High Winds Gu idance document provides examples (e.g., comprehensive control analysis with back trajectory, significant source contribution inventory, and deta iled control descriptions with evidence of implementation and enforcement) of effective evidence that air agencies can use to demonstrate “not reasonably controllable or preventable.” Air agencies can provide, and the EPA will consider, types of evidence other than t hose provided as examples in the draft High Winds Guidance document. The EPA encourag es submitting agencies to use the review and prioritization process identified in the dr aft guidance documents and to communicate with the reviewing EPA regional office to dete rmine the appropriate level of rigor needed for a complete demonstration package.Draft for Public Notice and Comment
Revision Date: June 2012 37

6.5.6. Comment: “In the Conclusion section of the Overview of the Draft Guidance Documents, EPA states ‘EPA expects to adhe re to the draft guidance provided in this
overview document and its attachments durin g the review and document finalization process....’ With so many areas of the guidan ce still causing concerns due to such things as lack of definitiveness and clarity, EPA should not move forward on implementing guidance until it has been fully reviewed, comme nted on, or even formally approved. For an air quality issue that is very technical a nd has the potential to have great consequences on both EPA staff and local and state air pla nning agencies, this does not seem to be the appropriate pathway to move forward in dete rmining adequacy and ev entual concurrence, or not, of the submittal.” Specific reference to guidance text: conclusion of Overview document
Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California
Air Pollution Control Officers As sociation, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: The EPA believes that the revised draft guidance documents are consistent with the Exceptional Events Rule and the gui dance already provided in the preamble to
the rule. The EPA intends to follow the re vised draft guidance as the EPA developed these documents to assist air agencies in submitting complete and effective demonstration packages.

6.5.7. Comment: From the Overview of Draft Guidance Documents Conclusion section, "EPA expects to adhere to the draft guidance provided in this overview document and its attachments during the review and document finalization process ... " The current draft guidance contains a number of deficiencies a nd issues as discussed in this comment letter that need to be addressed prior to bein g considered operational and ready for implementation. Specific reference to guidance text:
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 6.5.6.

6.5.8. Comment: We greatly appreciate the hard work being done by the U.S. EPA and, in particular, the recognition that certain impact ed values could be re moved in determining design values in cases where an exceptional even t increased the level of an exceedance.
This will allow states to assemble more realis tic tools to attain and maintain the National Ambient Air Quality Standards. Specific reference to guidance text: none Submitter: Lynn Terry (Deputy Executive Office r) for James Goldstene (Executive Officer), California Air Resources Board, ksnyder@arb.ca.gov

Date: 6/24/2011 letter to Gina via e-mail to EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support and refers to the response provided in 6.5.1. and Question 13 of the draft Q&A document.

6.5.9. Comment: “In assessing whether violations of the ambient standards for particulate matter deserve regulatory forbearance based on designations as a wind-related ‘exceptional event,’ the EPA should give full consideration to the practical impacts of those events on public health and the public welfare. At least in areas where history shows acute, deadly and recurring threats to transportation and public health resulting from wind-blown dust events, the EPA should condition ‘exceptional event’ approval upon obligatory implementation of a program that provides meaningful highway-oriented mitigation of activities and surface conditi ons that would otherwise compound those
threats.”Draft for Public Notice and Comment
Revision Date: June 2012 38

Specific reference to guidance text:
Submitter: Don Gabrielson (Director), Pinal County Air Quality Control District

Date: 7/1/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA agrees with the commenter that the “reasonableness” of control measures depends on the nature and frequenc y of local events and the air quality problems, which they cause or to which th ey contribute. The EPA believes that the revised draft guidance documents express this concept.

6.5.10. Comment: ADEQ recommends that the EPA's concurrence be based upon a "preponderance of the evidence" rather than “weight of the evidence” as WOE does not go far enough to protect the interests of th e states and it is unclear as to what evidence holds “weight” with the EPA. Specific reference to guidance text:
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA believes we should consider all relevant evidence and qualitatively “weigh” this evidence based on its relevan ce to the EER criterion being addressed, the degree of certainty, its persuasiveness, and other considerations appropriate to the individual pollutant and the nature and type of event. The EPA has clarified this position by adding Question 19a to the revised draft Q&A document.

6.5.11. Comment: BP recommends that the EPA conduct a public meeting as part of the EER guidance document comment process to di scuss implementation issues specifically regarding the ozone NAAQS implementation a nd EER guidance. Concern is that “but for” and “historical fluctuations” provisions of rule would specifically disallow the exclusion of some ozone EEs because policy re levant background is nearing or at the anticipated level of the new/reconsidered ozone NAAQS. Specific reference to guidance text: none Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA believes that a first-round written comment process, supplemented by clarifying phone calls (and one meeting in Region 9) with commenters as needed, was the most useful approach for obtaining public comment on the draft guidance materials. The EPA invites BP to clarify its comments during the second-round comment period.

Regarding the commenters’ concern abou t “policy relevant background” ozone concentrations and exceptional events, the EPA notes that these concepts are related and partially overlap. The 2007 Staff Paper 3 defines policy relevant background ozone “as the distribution of [ozone] concentrations that would be observed in the U.S. in the absence of anthropogenic (man-made) emissions of precursor emissions (e.g., VOC, NO

x , and CO) in the U.S., Canada, and Mexico.” An exceptional event is a natural event (excluding stagnations, inversions, high temperatures, or precipitation) or an anthropogenic event that is unlikely to re cur in the same location. Both exceptional events and policy relevant background include emissions from natural events like forest wildfires or stratospheric ozone intrusio ns. However, exceedances due to natural emissions that occur every day and contribute to policy relevant background, such as biogenic emissions, do not meet the definition of an exceptional event and are thus not eligible for exclusion under the EER. Rou tine anthropogenic emissions outside of the

3 Environmental Protection Agency (2007a) Review of the national ambient air quality standards for ozone:
assessment of scientific and technical information. OAQPS staff paper. (Upd ated Final) July 2007. Research Triangle Park, NC: Office of Air Qua lity Planning and Standards; EPA report no. EPA-452/R-07-007. Available
online at: http://epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_sp.html

.Draft for Public Notice and Comment
Revision Date: June 2012 39

U.S. contribute to policy relevant background, but are not exceptional events. State/local/tribal preparation of a demons tration package and the EPA’s subsequent review of the demonstration package is case-by-case based on a weight-of-evidence approach and does not explicitly consider wh ether the event type might contribute to policy relevant background. However, if a natural event that contributes to policy relevant background causes an observed concentr ation that meets the statutory definition of an exceptional event and fulfills all of the exceptional event criteria, the EPA would
consider the event to be an exceptional event.

The EPA has added Question 16a to the re vised draft Q&A document to address this
issue.

7. Guidance Specific to High Wind Dust Events

7.1. Definition of “event” for high wind dust events

7.1.1. Comment: ADEQ agrees that definitions of natural and anthropogenic windblown emissions developed in the WRAP handbook are appropriate. ADEQ further supports the analysis and recommendations provided by MAG on aerodynamic entrainment. Specific reference to guidance text:
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

7.2. Conceptual model

7.2.1. Comment: Requirement for a Conceptual Model - The guidance requires exceptional events packages to contain a “conceptual model” (High Wind document, Section 6.2.1, page 32). All exceptional events packages s hould provide a narrative description of the event. However, characterizing the “story” as a model is not appropriate. Great Basin believes the packages should contain real models of the event using wind speeds, wind directions, monitor locations, and monitor va lues. “Stories” should not be substituted for
science and science should be used to the ex tent possible to verify exceptional event
claims. Specific reference to guidance text: page 32 of High Winds Guidance document
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA uses the term “conceptual mode l” to mean the “story” or “executive summary” of the event. The conceptual model should provide an overview of the
technical information in the demonstrati on package and help identify relevant quantitative information critical in satisfying the EER criteria.

7.2.2. Comment: Page 48, bullet #3 – Description of weather conditions that created high winds (as part of Clear Causal Relationship) . Isn’t this duplicating the effort in the conceptual model section? Specific reference to guidance text:
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: The conceptual model summarizes the “story” presented in the demonstration package and, as such, is likely to repeat some information a ppearing in more detail in
other sections of the demonstration. The “c onceptual model” approach is similar to abstract or executive summary repeating information contained in the body of a
document. As the EPA receives demonstration packages that contain conceptual models, the EPA will post them on the exceptional events website.Draft for Public Notice and Comment
Revision Date: June 2012 40

7.2.3. Comment: “A conceptual model is not a required component of an exceptional event demonstration package, but we think a comp rehensive narrative lays the groundwork for
the technical demonstrations and assists with weight-of-evidence showings. As such, it can be a positive addition to the demonstrati on package. This would be particularly helpful in reducing the need for detaile d explanations later in each package.” Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

7.2.4. Comment: ADEQ agrees that a narrative summary at the beginning of a demonstration package which explains how the event unfol ded will provide context for the data and analysis provided in the demonstration. Specific reference to guidance text:
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

7.3. High wind threshold

7.3.1. Comment: We request that the EPA clarify the definition of a High Wind Dust Event
and in Section 3.1.4 Consideration of Recurre nce. Questions: 1. Is it a high wind dust event only when the standard is exceeded? 2. Is it a high wind dust event when the winds exceed 25 MPH sustained and shows only elev ated particulate (but does not exceed the standard)? Specific reference to guidance text: threshold
Submitter: Dan Gates, City of Albuquerque EHD-AQD, dgates@cabq.gov

Date: 6/2/2011 via e-mail to Jim Afghani in EPA Region 6 Response: The commenter asks whether a high wind dust event must exceed the NAAQS to be considered an excep tional event. In general, a PM concentration below the level of the NAAQS would not be an exceedance and would not affect compliance with the NAAQS. Therefore, the EPA will generally not exclude a concentration below the level of the PM NAAQS created by a high wind dust event. The EPA’s guidance does, however, note in Questions 19, 29, and 30 of the revised draft Q&A document, a few limited situations in which an air quality c oncentration for particulate matter and other pollutants could contribute to an exceedance or violation and be below the level of a given NAAQS (and, as a result, be considered an exceptional event).

The commenter further asks whether a high wind dust event must exceed the high wind threshold of 25 mph and exceed the standard to be exceptional. The EPA has modified the high wind threshold concept and refers the commenter to the response to comment 7.3.2. regarding high wind thresholds. As the EPA states in this document and in the revised draft High Winds Guidance document, th e high wind threshold is intended to help inform the rigor with which the EPA will re view the “not reasonably controllable or preventable” criterion rather than a level above which the EPA would automatically consider an event to be exceptional. The EPA expects that only in very rare cases would an event be both below the NAAQS and below a given high wind threshold and be “exceptional.” As with all exceptional event demonstrations, the EPA will review each
case on its own merits.

7.3.2. Comment: 25 Miles per Hour Default Threshold Wind Speed “ By far, Great Basin’s greatest issue of concern is the proposed use of 25 miles per hour (MPH) as the assumed minimum threshold wind speed necessary to entrain particles from stable (natural and controlled anthropogenic) surfaces. Any defa ult wind speed, especially a low one like 25Draft for Public Notice and Comment
Revision Date: June 2012 41

mph, provides an excuse for not controlling serious PM sources and may encourage facilities to refrain from implementing dust c ontrols where and when they are needed most. It is very important that 25 mph not be set as the hard, bright line as to what constitutes high wind events for all arid areas. Depending on the many variable local circumstances and conditions, the actual wi nd speed required to produce emissions from undisturbed and reasonably controlled surface s will vary greatly from the 25 mph set forth in the draft guidance. In addition, the Di strict contends such a default threshold is not allowed by the EER. The proposed guidan ce refers to ‘empirical evidence’ and ‘numerous studies’ (High Winds Guidance docum ent, pages 3 and 14) as justification for using 25 mph. It is unfortunate that EPA used only three limited studies to derive a proposed threshold number. None of the studies were designed to be used to set national air pollution guidance. In fact, based on Great Basin’s decades of studying this issue, we contend that there are virtually no undisturbe d natural surfaces in the arid west with PM 10 emission thresholds as low as 25 mph. PM 10 emissions that occur at 25 mph almost certainly come from disturbed uncontrolled or poorly controlled surfaces. Please refer to the attached information discussing the propo sed 25 mph threshold wind speed in more technical detail. Another concern regarding th e concept of a default threshold wind speed is that it does not appear to be allowed by the EER. On page 14 of the proposed High Winds Guidance document it states, “In the ab sence of local studies, EPA intends to use 25 mph as the minimum sustained wind speed.” In contrast, Section VII.B.2. of the rule states: “In this rule, EPA is not identifying a specific wind speed which should be considered when making a determination c oncerning whether an event should qualify as exceptional. Instead, EPA is requiring that States submit appropriate documentation that demonstrates why a particular event should be considered exceptional for the affected area. The EPA will review the documentation submitted by States concerning high wind events and will make decisions concerning whether to exclude the data as being influenced by an exceptiona l event on a case-by-case basis.” This makes is clear that EPA cannot set a threshold wind speed, but must require the states to submit appropriate documentation to exclude data that may be in fluenced by exceptionally high winds that
would overwhelm BACM and reasonable dust c ontrol measures. As required by the rule, it is important that a case-by-case analysis by done for each area since BACM regulations and compliance needs are different in all stat es and areas. EPA should follow the rule and require every area to submit an exceptional ev ents analysis based on real, area specific evidence. A presumed default threshold wi nd speed applicable to all areas under all
circumstances is in conflict with the EER and is not the appropriately conservative approach that protection of public health requires. Finally, a concerning consequence of setting a low default wind speed threshold will be the pressure on local agencies from air polluters to flag the PM 10 data that occur any day the winds exceed 25 mph. It is certainly simpler (and less expensive) to claim an excep tional event than it is to deploy effective
controls. Specific reference to guidance text: High Winds Guidance document, reasonable
controls
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: In identifying a high wind threshold, the EPA does NOT intend to set a bright line as to what speed constitutes a high wind dust event or to categorically concur with all events with sustained winds above a given threshold. Both the nullified preamble language and current EPA inte rpretation require appropriate event-specific information that the EPA will review on a case-by-case basis. The high wind threshold is the minimum threshold wind speed capable of overwhelming reasonable controls on anthropogenic sources (i.e. significant emi ssions from controlled sources) or causing
emissions from natural undisturbed areas. This threshold is intended to help inform theDraft for Public Notice and Comment
Revision Date: June 2012 42

rigor with which the EPA will review the “ not reasonably controllable or preventable” criterion. Above this threshold wind speed, a lesser amount of information and data could show that the event was not reasonably controllable or preventable. Conversely, more information might be required when demons trating the not reasonably controllable or preventable criterion when sustained winds are below the threshold speed. The EPA further agrees with the commenter that wind speed, area-specific regulations, and compliance needs determine “reasonableness. ” The EPA expects all agencies submitting high wind dust event demonstrations to address not only wind speed but also required controls, regulations and compliance, and public health needs.

In its guidance documents, the EPA identifies that air agencies may establish a different
threshold based on local studies. Given num erous commenter concerns regarding the EPA’s use of a default threshold, the EPA has modified its revised draft guidance. The EPA now suggests that agencies develop a high wind threshold for each area experiencing high wind dust events. Appropriate area-specific thresholds would consider
local conditions and the variation in contro l strategies and specify a speed above which
these controls would be overwhelmed. This a pproach is consistent with the Natural Events Policy where the EPA required the air ag encies to define the conditions in which
BACM level controls were overwhelmed. If an agency is unable to develop an areaspecific wind threshold, the EPA will accept a threshold of 25 mph for areas in the West provided the agencies provide evidence of this as the level at which they expect stable surfaces (i.e., controlled anthropogenic a nd undisturbed natural surfaces) to be overwhelmed. And, provided the agencies are able to show that conditions in that area are similar to conditions in Clark County, NV where studies show that 25 mph winds
overwhelmed reasonable controls. 4 The EPA provides additional rationale for the development and use of high wind thresholds in the revised draft High Winds Guidance
document.

Air agencies wishing to prepare and submit a high wind threshold analysis can do so at any of the following times: 1. In advance of agency submittal and the EPA review of any specific demonstration
submittal
2. With a letter of intent 3. With a demonstration package 4. As a component in a prospective controls analysis or High Wind Action Plan. The response to comment 7.4.1. presents additi onal information on prospective controls analyses.

As described in later responses to comments and in the revised draft High Winds Guidance document, the EPA has also revised the intended lifespan of High Wind Action Plans. Once the EPA has approved these plans a nd they have gone through the notice and comment process, they will be effective for a minimum of 3 years with some possibility to be reopened and reviewed. (See response to comment 7.4.1.)

7.3.3. Comment: Sustained Wind – “In addition to contending that 25 mph is too low for adefault threshold wind speed (and is, in fact, prohibited by the EER), the use of oneminute averages to determine an exceptional event is inappropriate and, for most monitoring agencies, impractical. The PM 10 standard is a 24-hour standard. How can one minute of 25 mph wind in a 24-hour period be considered exceptional? If control

4 EPA intends to evaluate whether an event was not reasonably controllable or preventable at the time of the event by taking into account the wind speed and the reasonable controls in place, which is dependent on an area’s attainment status, the frequency and severity of exceed ances, benefits of the controls, and other factors.Draft for Public Notice and Comment
Revision Date: June 2012 43

measures are in place, it is extraordinarily unlikely that a one to five minutes high wind could have a meaningful impact on the 24-hour PM 10 standard. Many arid areas of the west experience episodic wind events. At Owe ns and Mono Lakes, it is not uncommon to experience high winds, with attendant elevated PM 10 levels, for short periods (1 to 2 hours) within the monitoring day, while the remaining hours of the day have much lower
winds and PM 10 levels. The few high wind/high PM 10 hours are cancelled out by the
numerous low wind/low PM 10 hours and there is no exceedance. These frequent occurrences should not be grounds for excluding air quality data. We would argue that the truly exceptional events are the rare even ts with sustained high winds occurring over many hours or extreme winds (much higher than 25 mph) with extreme PM 10 levels that occur for brief periods of time. An exceptional event is certainly not any day with one minute of 25 mph winds. It is our understanding that, although many agencies collect one-minute (or more frequent) wind speeds, th e archived frequency is typically one hour. Great Basin normally samples at two-second intervals (to determine highest hourly gusts), but logs only hourly averages and the highest 2-second gust for every hour. The EPA’s “Quality Assurance Handbook for Air Pollution Measurement Systems (Volume 4: Meteorological Measurements Versi on 2.0)” [EPA-454/B-08-002, March 2008] requires non-Ncore stations to collect at least 1 minute raw data, but the minimum sample frequency is hourly (Table 0-5). It would be appropriate to match exceptional event data requirements with the EPA’s own meteorologi cal monitoring requirements. Exceptional winds should be at least one-hour average winds.”

Great Basin also provided supplemental information re the use of a 25 mph wind speed threshold (see Submitted Comments\Great Basin APCD comments on draft EER guidance.pdf ) Specific reference to guidance text: High Winds Guidance document, reasonable
controls
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: Commenters providing feedback regarding high wind threshold averaging times have generally made two points: (1) an area is unlikely to see PM emissions that are significant enough to cause violations of the NAAQS during a 1 to 5 minute period and (2) the availability of 5 minute data is li mited and requiring this type of information adds a burden to the air agencies. Further, agencies who have conducted wind tunnel
studies in areas of the Southwest have histor ically extrapolated the minute-level wind tunnel data to hourly high wind thresholds. On these bases, the EPA has revised the draft guidance to focus on hourly wind data for the high wind threshold and; therefore, define “sustained wind” as an hourly average (i.e., the default wind threshold of 25 mph will be based on an hourly average).

The EPA notes that the National Climate Center has started archiving the 2-minute winds for every 2-minute period of each hour for all ASOS stations in the country. Almost all sites have data since March 2005, with most archiving data since 2000. The EPA has further developed a preprocessor to AERMOD, called AERMINUTE, that takes minute observations and calculates an hourly averag e wind that can be fed into AERMET, the AERMOD meteorological processor. The AERMINUTE output is user friendly. AERMET can also accept, process, and calcu late hourly average wind speeds from subhourly data with a resolution equal or gr eater than 5-minutes from sources other than

AERMINUTE.

The EPA will consider shorter-term “snapshot s” of wind data such as National Weather Service hourly summaries as part of the we ight-of-evidence demonstration. The EPADraft for Public Notice and Comment
Revision Date: June 2012 44

intends to allow air agencies to use wind data from a multitude of sources and with different averaging times, including model outputs (e.g., MM5, WRF) in the development of high wind thresholds. The EPA further in tends to solicit feedback on the available
sources of wind data and their use in the second round of comments on the revised draft guidance documents.

7.3.4. Comment: “CAPCOA understands the rationale be hind establishing a default high-wind threshold to assist EPA in determining th e required level of review and documentation necessary to make exceptional event determina tions. However, it is very important that 25 miles per hour not be set as the hard, bright line for what constitutes high wind events for all arid areas. Depending on local circ umstances and conditions, the actual wind speed required to cause emissions from undist urbed and reasonably controlled surfaces will vary greatly from the 25 miles per hour set forth in the draft guidance. Some areas of the arid west may be able to demonstrate that a lower threshold is justified for their area while others could prove that the threshold should be higher. Examples of existing data for some areas of California indicate the threshold could be as low as 16 miles per hour in the San Joaquin Valley to 45 miles per hour or more in the Owens Valley. EPA selected the 25 mile per hour default threshold afte r reviewing a limited number of studies not
intended for such a determination. EPA h as acknowledged that alternative thresholds
could be considered for individual areas with appropriate justification, but the guidance fails to set forth exactly what and how mu ch documentation would be required for EPA to approve an alternative threshold.” Specific reference to guidance text: High Winds Guidance document
Submitter: Ken Koyama (Exec Director) for Thomas J. Christofk (President), California Air Pollution Control Officers Association, kenk@capcoa.org

Date: 6/14/2011 via e-mail to Gina McCarthy Response: As indicated in the response to comment 7.3.2., the high wind threshold is not intended to be a “bright line.” The EPA ’s guidance indicates that the wind speed will help inform the rigor needed to satisfy th e not reasonably controllable or preventable requirement of the EER. The EPA will revi ew wind speed, along with the submitter’s analysis of implemented reasonable contro ls, using a weight-of-evidence approach. Therefore, events with wind speeds below the high wind threshold may qualify as high wind exceptional events. Though these events may qualify as “exceptional,” the EPA expects submitters to develop more rigorous and convincing supporting documentation to demonstrate that the events in question we re, in fact, not reasonably controllable or preventable.

Also, as indicated in the response to comment 7.3.2., local high wind thresholds should define the local conditions capable overw helming reasonable controls or causing
emissions from natural undisturbed areas and should be supported and justified by local
research. If local research or studies are not av ailable, agencies may use a threshold of 25 mph or consider appropriate, relevant info rmation from other areas that share similar characteristics including similar soil types, land uses, and meteorological conditions.

Please see the revisions to the revised draft High Winds Guidance document for additional information regarding develo pment of high wind thresholds.

7.3.5. Comment: Why did the EPA not include wind gust/max. in its guidance? Wind gusts/max play a vital role in the formati on of haboobs/dust storms (“The Impact of Exceptional Events ‘Unusual Winds’ on PM 10 Concentrations in Arizona, ” Arizona Department of Environmental Quality (ADEQ), 10/15/09, online at http://www.azdeq.gov/environ/air/plan/ download/assessments_white/091015%20The%2Draft for Public Notice and Comment
Revision Date: June 2012 45

0Impact%20of%20Exceptional%20Events%20'Unusual%20Winds'%20on%20PM10%2 0Concentrations%20in%20Arizona.pdf Specific reference to guidance text: High Winds Guidance document
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: While this information may be usef ul in the overall weight-of-evidence, information concerning maximum wind gusts should not serve as the primary basis for determining whether the wind speeds associated with the event in question are capable of overwhelming reasonable controls or causi ng emissions from natural undisturbed areas. Maximum wind speeds or wind gusts are ofte n measured on an instantaneous basis, ranging from less than one second to multiple seconds. It is unlikely that one second of high wind would be sufficient to entrain dus t from stable surfaces or cause an exceedance
of the 24-hour PM 10 or PM 2.5 NAAQS and; therefore, the EPA is using “sustained” wind speeds as the appropriate measure for ex ceptional event purposes. The EPA supports inclusion of available gust inform ation as additional information.

7.3.6. Comment: Would it be possible for the EPA to put together a summary table and/or bibliography of specific studies related to choos ing an alternative high wind threshold? It makes more sense to have a list prior to s ubmitting a package to the EPA rather than the EPA waiting until a package is submitted before providing the information to a state/local

agency. Specific reference to guidance text: Page 14, section 3.1.3, bottom of paragraph 2, High
Winds Guidance document
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: Yes, the EPA will provide a list of ava ilable relevant literature on this subject in an Appendix to the revised draft High Winds Guidance document.

7.3.7. Comment: AQMD staff applauds the effort to develop a tiered approach where the stronger wind events (25 mph sustained thr eshold used in the guidance) may need less analysis and documentation than those that are not clear cut. The most obvious, extremely high wind events should require even less analysis and event documentation. Hopefully, this will also result in quicker concu rrence with the obvious events. For the most obvious high wind cases, a checklist appro ach with key supporting data should be adequate. We hope to continue to work with you to streamline the process and the
documentation. Specific reference to guidance text: High Winds Guidance document
Submitter: Barry Wallerstein, South Coast Air Quality Management District

Date: 6/28/2011 via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

7.3.8. Comment: First, the level of complexity of the demonstration decreases significantly if the event was caused by sustained winds exceed ing 25 mph. The 25 mph threshold is met by most of the exceedance measured on the Community for which exceptional event status might be sought. Nevertheless, long e xperience shows that significant levels of dust can be entrained by winds at levels well below 25 mph. The guidance suggests that the EPA may find that the lower wind speeds may pass muster as being sufficient to cause exceptional events, but there is no description in the guidance as to how a
demonstration can be made to have the lo wer wind levels accepted. Moreover, it is unclear whether, once a demonstration is made that wind conditions, topography, the aerodynamic characteristics of the soil, and other Community-specific conditions are such that a lower wind velocity threshold can be substituted for the 25 mph presumptive
threshold that the demonstration will be required each time an exceptional eventsDraft for Public Notice and Comment
Revision Date: June 2012 46

demonstration is made. In add ition, if the quantum of information necessary to lower the presumptive threshold will have to match that presented by Clark County (e.g., wind tunnel testing) to establish the 25 mph threshol d in the first place, the Community's task will always be cost prohibitive. Specific reference to guidance text: High Winds Guidance document
Submitter: Leroy Williams (Environmental Engineer) for William Rhodes (Governor), Gila River Indian Community, williams@gilanet.net

Date: 6/23/2011 via letter to Gina with cc e-mail to EEGuidanceComments@epa.gov Response: As indicated in the response to comme nt 7.3.2., agencies can develop local high wind thresholds that define the local conditions capable of overwhelming reasonable controls or causing emissions from natural undi sturbed areas. These thresholds should be supported and justified by local research. If local research or studies are not available, agencies may consider appropriate, relevant information from other areas that share similar characteristics including similar soil types, land uses, and meteorological conditions or identify 25 mph as the level at which they expect stable surfaces (i.e., controlled anthropogenic and natural undis turbed areas) to be overwhelmed.

7.3.9. Comment: The usage of 25 mph as a default high wind speed threshold is inappropriate for the San Joaquin Valley and many other regions as it was derived from studies conducted in the desert, arid environments of Nevada and Arizona. The desert soil types are not representative of soil types found in other regions. For example, in the San Joaquin Valley, soil types are heavily composed of clay, and the District has scientifically documented a wind entrainment threshold of 17.9 mph that has been included and approved in prior exceptional event submittals to the EPA. The draft guidance is unclear regarding what information would be needed to demonstrate an alternative wind speed entrainment threshold. Given the prior appr oval of exceptional events by the EPA, the District requests that EPA approve 17.9 m ph as the wind speed entrainment threshold for the San Joaquin Valley Air Basin in the draft guidance or provide clear direction to obtain approval for the lower high wind speed threshold. Specific reference to guidance text: High Winds Guidance document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See responses to comments 7.3.2. and 7.3.8.

7.3.10. Comment: The guidance document states "sustained wind speed data are typically available from sources such as local air monitoring stations and National Weather Service stations." Most high wind events in the Sa n Joaquin Valley air basin occur in remote areas where wind speed information is genera lly unavailable. The installation of wind speed equipment is extremely labor intensive and cost ineffective in trying to fulfill EPA's wind data requirements. On page 34, sustained wind speeds are determined by averaging times of one to five minutes. The NWS data is a snap shot (2-minute average) of the data toward the end of the hour, and there is no way to capture wind speed information during other parts of the hour. The data available from NWS are unlikely to capture the event. Wind speed measurements of this resolution are not readily available. The District recommends using MM5 or any other model output (for example CANSAC or NAM) to provide wind speed information. The guidance document should allow for alternative sources of wind speed measurements. Specific reference to guidance text: High Winds Guidance document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.govDraft for Public Notice and Comment
Revision Date: June 2012 47

Response: In response to comments and as describ ed in 7.3.3., the EPA has modified our approach to high wind threshold averag ing times to allow extrapolating minute level data to hourly high wind thresholds. Even with this modified approach, the EPA understands that dense meteorological networks are not always available. A high wind exceptional event demonstration should include all relevant meteorological data from any available source. Generally, the EPA reco mmends using NWS data or the National Climate Center. Where meteorological data are not available for a particular area and
such data are critical for the demonstrati on, agencies may substitute modeled wind speed
surface measurements for actual measured data. Models that agencies can use to develop estimates for actual measured wind speed surface measurements include MM5, WRF, and, possibly, NAM.

7.3.11. Comment: “Imperial County APCD understands the rationale behind establishing a default 25 M.P.H. high wind threshold fo r determining the level of review and documentation necessary to make an exceptional ev ent determination. However, it is very important that the 25 M.P.H not be the "bright" line as to what constitutes high wind events for all areas. Imperial County appreci ates EPA's acknowledgement that alternative
thresholds could be considered for individua l areas with appropriate justification but the guidance does not establish what type and how much documentation would be required for EPA to approve an alternative threshold. Agreeing that this should be a case-by-case evaluation, appropriate guidance on how and wh at is required to establish a different threshold would save all agencies involved valuable time and resources if they understood what needed to be provided to EPA.” Specific reference to guidance text: none Submitter: Brad Poiriez, Imperial County Air Pollution Control District, bradpoiriez@co.imerial.ca.us

Date: 6/14/2011 via e-mail to Gina McCarthy Response: See response to comment 7.3.2.

7.3.12. Comment: “ EPA should not specify a minimum wind speed for defin i tion of an exceptional event ("EE") or create a regu l atory presumption as to minimum wind speed .” Specific reference to guidance text: varies (additional documentation to support recommendation is provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf )
Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 7.3.2.

7.3.13. Comment: “ EPA should consider additional technical information with regard to wind speed and aerodynamic entrainment (such as that provided in the attached detailed comments) and correct errors in its analysis of these matters. ” Specific reference to guidance text: varies (additional documentation re aerodynamic entrainment and soil disturbance provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf )
Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response : The Maricopa Association of Governments (MAG) asserts that a 25 mph high wind threshold is not supportable and discusse s a number of factors that may affect the level of wind speed associated with high wind dust events, which include surface roughness, soil disturbance, and aerodynamic entrainment. The EPA based the 25 mph
threshold on extensive windblown dust emissions research performed by the UniversityDraft for Public Notice and Comment
Revision Date: June 2012 48

of Nevada, Las Vegas (UNLV). During UNLV’s studies, researchers used a wind tunnel to quantify emissions from undisturbed areas meeting the stabilization requirements of Clark County’s (Nevada) BACM level fug itive dust regulations and mechanically disturbed open areas. The research performed by UNLV is one of the few field studies that clearly relates BACM level control of windblown dust from open areas and PM 10 emissions. The EPA believes that for Clark County and areas similar to it, the study results clearly differentiate emissions from these two types of conditions and provide a reasonable baseline for establishing a high wind threshold for exceptional events

purposes.

While the information presented in M AG’s detailed comments provides useful information on the mechanics of windblown dust in some areas, the high wind threshold is intended to represent the conditions that are capable of overwhelming reasonable controls on anthropogenic sources (i.e., signi ficant emissions from controlled sources) or causing emissions from natural undisturbed areas, not the wind speed at which any level
of emissions could occur from any source. This approach is also consistent with the Natural Events Policy where the EPA required air agencies to define the conditions in
which BACM level contro ls were overwhelmed.

In its guidance documents, the EPA notes that air agencies may establish a different
threshold based on local studies. Given num erous commenter concerns regarding the EPA’s use of a default threshold, the EPA has revised the draft guidance. The EPA now suggests that agencies develop a high wi nd threshold for each area experiencing high wind dust events. As indicated in the response to comment 7.3.2., local high wind
thresholds should define the local conditions capable overwhelming reasonable controls on anthropogenic sources (i.e., significant em issions from controlled sources) or causing
emissions from natural undisturbed areas and should be supported and justified by local
research.

7.3.14. Comment: Clarify the timing for a state to submit a recommended alternative wind speed based on local studies. “A state may con duct a study after a high wind event occurs and submit that as part of the demonstra tion package.” Sacramento Metropolitan Air Quality Management District requests that the guidance allow all studies to be included in a demonstration package. Specific reference to guidance text: High Winds Guidance document
Submitter: Larry Greene (Executive Director), Sacramento Metropolitan Air Quality Management District

Date: 6/30/2011 letter via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: The EPA agrees that agencies can submit high wind threshold analyses as part of a demonstration package. Agencies may also submit these analyses as part of other submittals as identified in the response to comment 7.3.2.

7.3.15. Comment: Wyoming Air Quality Division supports a high wind threshold and believes that 25 mph is appropriate based on their e xperience. Wyoming Air Quality Division is, however, concerned that the EPA has “alread y determined that exceedances which occur or recur when winds are regularly greater than 25 mph will require a more detailed control analysis and enhanced controls. The purpose of the Guidance is to deal with high wind events defined as greater than 25 mph. To further caveat and categorize high winds greater than 25 mph is unwarranted given the level of documentation already being requested.” Specific reference to guidance text: High Winds Guidance document, Section 3.1.4
Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.govDraft for Public Notice and Comment
Revision Date: June 2012 49

Response: Both this document (in the response to comment 7.3.2.) and the revised draft High Winds Guidance document now contain la nguage to clarify the development and application of high wind thresholds.

7.3.16. Comment: ADEQ requests that the EPA identify in the guidance, the literature, methods, and analytical process that the EPA used to define the 25 mile per hour threshold. This type of baseline would help agencies that wa nt to conduct relevant local studies to submit alternative high wind thresholds more appr opriate for specific areas. ADEQ recommends that the EPA change the guidance such that it is clear that the 25 mile per hour or other negotiated threshold will be used only to assess the amount of documentation necessary to support an exceptional event demonstrati on rather the status of the event as being exceptional. Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: Appendix A of the revised draft High Winds Guidance document contains the rationale for the 25 mph threshold. As discu ssed in response to comment 7.3.13, the EPA based the 25 mph threshold on extensive wi ndblown dust emissions research performed by the University of Nevada, Las Vegas (UNLV). During UNLV’s studies, researchers used a wind tunnel to quantify emissions from undisturbed areas meeting the stabilization requirements of Clark County’s (Nevada) BACM level fugitive dust regulations and mechanically disturbed open areas. The EPA believes that for areas similar to Clark County the study results clearly differentiate emissions from these two types of sources and provide a reasonable baseline for establishing a high wind threshold for exceptional
events purposes.

As previously noted in this document, the EPA is modifying its approach to high wind thresholds as discussed in the response to co mment 7.3.2. and will no longer specify 25 mph as a broadly applicable default threshold. The EPA maintains, however, that UNLV’s approach and results are sufficient to support a 25 mph high wind threshold for the Clark County, Nevada area and other areas that share similar characteristics including similar soil types, land uses, and meteorological conditions.

7.3.17. Comment: Requiring agencies to use sustained wind speed data on the order of 1-5 minute averages adds burdens to monitoring programs. Most meteorological data collected by agencies is in the form of hourly averages. While adjusting data logger programs to capture 1-5 minute averages is po ssible, this will increase data storage, staff time, and complexity of data review and quality assurance. Should the EPA use 1-5 minute averages as a measure of sustained winds, ADEQ recommends that the EPA provide a conversion calculation from hourly average to the selected averaging time interval. Otherwise, ADEQ recommends the use of a comparable hourly average high
wind threshold. Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 7.3.3.

7.3.18. Comment: “...soils in the Columbia Plateau of eastern Washington are powdery and easily raised by high winds. Research indicat es that a much lower wind speed is a more
suitable default for the Columbia Plateau. This research is discussed in Ecology’s Natural Events Action Plan for the Columbia Plateau .” Specific reference to guidance text: High Winds Guidance documentDraft for Public Notice and Comment
Revision Date: June 2012 50

Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of Ecology

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See responses to comments 7.3.2. and 7.3.8.

7.4. Recurrence

7.4.1. Comment: Clarification is requested in the definition of a High Wind Dust Event and in
Section 3.1.4 Consideration of Recurrence. Questions: 3. Is recurrence based only on the high wind dust event definition? 4. Is recu rrence based on the particulate standard being exceeded? 5. Is recurrence based only on the da ta that has been flagged over the three years? 6. What role does wind direction play in the definition and the recurrence
evaluation?

Example 1: The agency has implemented RACM on industry. Due to this most events, where the winds exceed 25 MPH, are controlled and only show elevated particulate (dust). Are these controlled events considered part of the recurrence evaluation or are only those
events that result in an exceedance of th e standard considered for the recurrence
evaluation?

Example 2:
In those events where the standard is exceeded wind direction plays an important role in determining where the dust originated. Ther e can be situations where the high wind
threshold has been exceeded but the wind dir ection is from an area that may not entrain sufficient dust (or is sufficiently controlled) to exceed a standard, or the wind speed and
directions were from an unusual direction a nd is not a common seasonal occurrence. It would seem appropriate to consider wind direction as an important aspect in the
recurrence evaluation.

Specific reference to guidance text: High Winds Guidance document definition of

recurrence Submitter: Dan Gates, City of Albuquerque EHD-AQD, dgates@cabq.gov

Date: 6/2/2011 via e-mail to Jim Afghani in R6 Response: The draft guidance said that in assessing whether an event was not reasonably controllable, the EPA would take into account whether the high wind event type was recurring such that more effective, but costly , controls would be reasonable compared to the situation in which a high wind event had b een a unique occurrence. In response to this and other comments, the EPA has reconsider ed this approach and is de-emphasizing recurrence. Although rare exceptions may exis t, the EPA does not expect to receive or review demonstrations for non-recurring high wind dust events because these nonrecurring events will generally not violate the NAAQS. As an example, everyday sampling allows for one exceedance of the st andard per year without causing a violation
of the 24 hour PM 10 NAAQS, unless sampling completeness is inadequate.

In response to comments received, in an effo rt to streamline the demonstration process, and based on the recurrence premise stated above, the EPA has modified the recurrence discussion in the revised draft High Winds Guidance document in the following ways:

 De-emphasized recurrence frequenc y when assessing “not reasonably controllable or preventable” analysis

 Made basic controls analysis slightly more robust (more like recurring above 25 mph case) to reflect vast majority of cases that are recurring.Draft for Public Notice and Comment
Revision Date: June 2012 51

 Added a Prospective Controls Analysis . Described in greater detail in section 3.7.1 of the revised draft High Winds Guidance document, a prospective controls analysis is a generic 5 review of an area’s current windblown dust controls and high wind threshold. In the prospective controls analysis, the air agency would provide information on attainment status, identify natural and anthropogenic windblown dust sources and emissions, provi de the status of SIP submittals (if applicable), and identify the high wind threshold up to which the collective windblown dust controls are expected to be effective. Once the EPA approves the prospective controls analysis, an air ag ency’s subsequent high wind exceptional event packages could reference the approve d set of controls in the prospective controls analysis and show that the wind speed for the event in question is at or above the high wind threshold established in the prospective controls analysis. Air agencies would also include in thei r demonstration some positive showingthat control requirements were being met on the day in question. An EPAapproved prospective controls analysis would generally be effective for a minimum of three years.

 Described the High Wind Action Plan (HWA P) more thoroughly in Section 3.7.2 of the High Wind Guidance document.

o Air agencies can develop HWAPs to document their plans to 

### implement needed controls on newly-identified sources that could emit dust during subsequent high wind even ts (similar to the process used in a Natural Events Action Plan).

o The HWAP is an optional mechanis m to implement necessary controls more expeditiously than with the normal regulatory planning process.

o Preparation of a HWAP and its approval by the EPA could promote a common understanding between the air agency and the EPA about whether subsequent high wind dust events are not reasonably controllable or preventable.

o The HWAP could document current wi ndblown dust controls and current and/or planned mitigation me asures as part of §51.930.

 The EPA review and approval of controls and an appropriate high wind threshold is typically effective for a minimum of three years

o The EPA does not expect to reconsider the determination of reasonablecontrols and high wind threshold for at least three years. After the threeyear time period, the EPA will notify the agency if the EPA intends to rereview the controls and high wind threshold. In some limited cases, the EPA may re-review the controls and high wind threshold within the three-year timeframe, such as if information on sources, enforcement, etc. suggests that controls may be inadequate or not implemented/enforced. The EPA may al so re-evaluate the controls when an area that does not typically have recurring high wind dust events experiences unexpected recurrent events.

o If an agency submits a package for an event with a wind speed below a previously EPA-approved high wind threshold, the submitting agency should also submit a new prospective controls analysis documenting the appropriateness of the lower threshold.

o If the EPA has approved a SIP containing wind-blown dust controls within the past three years, then the submitting agency has the option of using the SIP-approved controls in place of the prospective controls analysis. The submitting agency would, however, need to specify a high
wind threshold to which the controls are expected to be effective.

5 “Generic” means a general review rather than a review specific to an identified event.Draft for Public Notice and Comment
Revision Date: June 2012 52

Together, the SIP-approved controls and the high wind threshold would
constitute the set of controls that would have been reasonable to implement.

If the EPA’s review reveals inadequacies in currently implemented agency controls, then the EPA may pursue subsequent action, such as a SIP call, to secure controls as quickly and effectively as possible. In many cases, submitting agencies should pursue regulatory planning, but in some cases an area can make significant progress quickly by addressing the high wind dust issues using the HWAP. Once adopted by the state/local jurisdiction, these mechanisms would be mandatory. As pa rt of the exceptional event process, the EPA intends to promote both the regulatory planning mechanism and the HWAP approach for attainment areas.

7.4.2 . Comment: Frequency of Exceptional Events - The Overview document states (page 6 of 8): “A natural event would not have to be infrequent to qualify as an exceptional event under the EER.” How can a frequent event be exceptional? If the event is frequent, then reasonable controls should be developed for th at event. For example, winds over 25 mph are frequent in the Owens Valley. During the 26-year period between March 1985 and May 2011, there were 3,408 days with hourly average (as opposed to 1-minute average) wind speeds greater than 25 mph. This is an average of 130 days per year . Even if the threshold was raised to a 45 mph (hourly) aver age, the Owens Valley experienced almost 5 days per year (4.8) that exceeded this in creased threshold during the 26-year period. High wind days are not infrequent or exceptional in the Owens Valley and the arid west—we expect the deployment of measur es that control anthropogenic emissions on these days. Protecting public health requires as much. Specific reference to guidance text: Overview document, page 6
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: The statutory definition of an exceptional event at Clean Air Act section 319 recognizes that natural events can be both recurring and exceptional. However, the EPA also agrees with the commenter that “fre quent” and “exceptional” are area and event specific and must consider public health. As stated previously in this document, exceeding a specific wind speed does not, on its own, make an event “exceptional.” Rather the high wind threshold informs the rigor of the documentation required to support an exceptional events claim and also the rigor with which the EPA will review the “not reasonably controllable or prev entable” criterion. The EPA agrees with the commenter that agencies should deploy reas onable controls to control emissions. The
EPA’s intention is that indi vidual areas identify a high wind threshold that defines the local conditions capable overwhelming r easonable controls on anthropogenic sources (i.e., significant emissions from controlled sources) or causing emissions from natural undisturbed areas. The Owens Valley situation is unique or nearly unique, and requires careful application of these general concepts . The high wind threshold addresses one of the exceptional event criterion. A demonstra tion package would need to address all the other exceptional event criteria.

7.4.3. Comment: Is recurrence frequency calculated for all flagged high wind events or by site? Specific reference to guidance text: High Winds Guidance document
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: See response to comment 7.4.1Draft for Public Notice and Comment
Revision Date: June 2012 53

7.4.4. Comment: It should be made clear that reasonable controls are not required to be in place for the first high wind dust exceptional event in a PM 10 attainment area. This is important since PM 10 attainment areas will likely not ha ve any SIP approved or local dust control rules in place for sources like agri cultural operations, and thus it would be impossible to make the control findings. (Note: Santa Barbara County has historically
been in attainment of the federal PM 2.5 and PM 10 standards, and has no PM dust control rules in place for agricultural sources. The north ern half of the County has large stretches of contiguous agricultural lands that at times get wind whipped, producing visible
emissions and above normal PM 10 concentrations). Specific reference to guidance text: High Winds Guidance Document, Section 3.1.2
Submitter: Brian Shafritz, Santa Barbara County Air Pollution Control District, ShafritzB@sbcapcd.org

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: As directed by the comment, this response is specific to attainment areas. The EPA agrees that controls are not expected for the first high wind dust exceptional event in

a PM 10 attainment area. However, the EPA is unlikely to consider a first high wind dust event, because the first event is unlikely to result in a violation of the NAAQS. In response to comment, the EPA has added language to the revised draft High Winds Guidance document stating that the EPA does not expect PM controls in areas with no “history” of high wind dust exceedances. If an area is violating the standard because of more than one high wind dust event in a thr ee-year period, then the EPA will consider the area to “have a history” of high wind dust events. If wind speeds exceed a predetermined wind threshold, then the EPA may not consider the implementation of controls at the time
of the event to be a condition for a determ ination that the event was not reasonably controllable. The EPA will determine this during the review process. The EPA does not expect to simply concur on events where sources that were not controlled caused a violation just because the area was previously in attainment. The EPA expects to look closely exceedances that occurred with wi nd speeds below the wind threshold to
overwhelm reasonable controls or cause emis sions from natural undisturbed areas. If an
attainment area has violations below the high wind threshold and the EPA determines
that the concentrations are attributable to sources that could be reasonably controlled going forward, the EPA will do one of the following:

1. Request that the submitting agency de velop and implement an adequate HWAP and concur upon approval of the HWAP going forw ard if all other EER criteria have been

met.

2. Nonconcur. If the nonconcurrence results in an area’s designation as non-attainment,
then this nonconcurrence would also tri gger preparation of a SIP incorporating appropriate PM controls.

7.4.5. Comment: We are also concerned that the U.S. EPA's proposal implies that if a high wind event occurs more than once, new cont rol measures would be more feasible and cost effective. The frequency of unpreventable high wind events should not change the
assessment of what constitutes reasonable controls for windblown dust.

To address the U.S. EPA concerns that we be lieve underlie this proposal, ARB plans to develop a technical document which discusses the nature of sources for key regions, a conceptual model of the types of conditions under which high wind events occur, and an analysis of reasonable controls for that region. Subsequent requests for approval of specific events would then focus on documen ting the technical aspects of that individual event rather than a re-analysis of reasonabl e controls each time. This provides for region specific considerations. For example, Califo rnia State law provides unique authority forDraft for Public Notice and Comment
Revision Date: June 2012 54

the Great Basin Unified Air Pollution Control to establish mitigation requirements for the Owens dry lakebed, which does not apply elsewhere in the State. Specific reference to guidance text: none Submitter: Lynn Terry (Deputy Executive Office r) for James Goldstene (Executive Officer), California Air Resources Board, ksnyder@arb.ca.gov

Date: 6/24/2011 letter to Gina via e-mail to EEGuidanceComments@epa.gov Response: Based on CARB’s and other’s comments, the EPA has modified its approach to high wind thresholds and High Wind Action Plans and has added a prospective controls analysis, with elements similar to those proposed by CARB (see responses to comments 7.3.2. and 7.4.1.). The EPA still ma intains that the reasonableness of controls can depend on the number of days per year on wh ich they will have an air quality benefit.

7.4.6. Comment: The methodology used to determine recurrence frequency applies to high wind events. Will this also be applied to other event types? Specific reference to guidance text: High Winds Guidance document, Section 6.2.2.3
Submitter: Unnamed commenter

Date: 6/29/2011 via e-mail to EEGuidanceComments@epa.gov Response: The draft High Winds Guidance document raised the concept of recurrence as it pertains to the reasonableness of controls with the belief that a natural event that recurs
merits more effort at control than a one-tim e or very infrequent type of event. The EPA still adheres to this general concept for hi gh wind dust events. The EPA does not expect
the recurrence/reasonable control issue to ari se for other types of natural events, either because the event is expected to be highly in frequent (e.g., 2008 California wildfires) or because controls are unlikely to be applied a nd/or effective (e.g., volcanic eruptions). If the EPA discovers that the recurrence concep t described above applies to other event types, the EPA would apply the principles in the revised draft High Winds Guidance document and note this added application in further guidance.

7.4.7. Comment: The guidance does not provide much streamlining for ADEQ as most of their submittals would require the “most compre hensive evaluations” as described in the EPA’s sliding scales. ADEQ has provided alte rnative approaches to handling High Wind Action Plans and believes that these approach es would provide some resource relief as well as regulatory certainty. Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA has incorporated some of the commenters’ approaches into our revised draft guidance documents. Since recei ving this comment, staff in the EPA Region 9 office have been working with staff at Ar izona Department of Environmental Quality, Maricopa County, and Maricopa Associa tion of Governments (MAG) to develop a consolidated exceptional events demonstr ation package that addresses 29 exceedances of
the PM 10 standard in 2011 that can serve as a model for future events. The collaborative effort is nearing completion with slightly mo re effort than it has historically taken to address a single high wind exceptional event. Mu ch of the informati on included in the current demonstration package could be tran sferable to the remaining exceedances that are flagged as exceptional events, which w ill further aid the streamlining process. See also our response to comment 7.4.1.

7.4.8. Comment: The draft guidance is unclear regardi ng the determination of recurrence for exceptional events. For example, establishi ng recurrence appears to rely heavily on commonly occurring "informational" flags, as opposed to more appropriate "request to exclude" flags. Additionally, consecutive day high wind events are not clearly addressed by the draft guidance, and should be cons idered as a single event, and not multipleDraft for Public Notice and Comment
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events. Furthermore, the draft guidance includes additional documentation requirements
for events determined to be recurrent that can otherwise clearly be demonstrated to be exceptional, including natural events. The Di strict recommends that the EPA closely reevaluate its consideration of recurrent even ts to ensure that documentation beyond that needed to demonstrate compliance with the EER are not added through the draft guidance. Specific reference to guidance text: High Winds Guidance document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA has modified its approach w ith respect to recurrence. See response

to comment 7.4.1.

7.4.9. Comment: “EPA should not link the ‘recurrence’ cr iteria in the statutory EE definition to requirements for additional controls or to otherwise establish a "more than once a year"
definition of recurrence.” Specific reference to guidance text: varies (additional documentation to support recommendation is provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf )
Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 7.4.1.

7.4.10. Comment: ADEQ questions the value of the EPA’s requiring additional analysis of air pollution controls for events that occur more than 1 time per year. Agencies typically review (and flag) events when they occur. Th e EPA has indicated that they likely will not
review information until there is a related re gulatory decision. If there are fewer than 3 exceedances, then there will not be a regulatory decision, so the EPA’s approach really does not streamline the process. ADEQ recomme nds that the EPA not use recurrence of high wind events as a threshold for determining the extent of documentation needed to make the demonstration. Streamlining should be based on the merits of each event. Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 7.4.1.

7.4.11. Comment: WA ECY does not believe that it is appropriate to treat recurring high wind events differently than “one-time” events, particularly for agricultural areas where the amount of dust raised by high winds at on e time and not another does not reflect better and worse levels of control but the cycle of agricultural practices. “While the draft guidance specifies a 3-year period to de termine recurrence, we suggest basing ‘recurrence’ on a longer period of record such as 10-to-20 years or even more.” Specific reference to guidance text: High Winds Guidance document
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of Ecology

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 7.4.1.

7.5. Reasonable controls

7.5.1. Comment: It is noted within the guidance that “HWD EE packages must address whether reasonable controls were in place for anthropogenic sources contributing to the event.” In the subject of agricultural operations within rule 403, most of these operationsDraft for Public Notice and Comment
Revision Date: June 2012 56

are exempt from stringent dust controls and are obligated under “best management practices” (BMP) compliance, which in most cases are voluntary. It seems a contradiction to demonstrate or demand that reasonable controls may or may not have been in place during the EE, when BMP, at the very best, are voluntary. Again, agricultural operations are basically exempt in the area of the Coachella Valley, California, from stringent dust control compliance. Specific reference to guidance text: High Winds Guidance document, reasonable
controls
Submitter: Jonathan Chapman, Torres Martinez De sert Cahuilla Indians, 760-397-0300 ext 1224, jchapman@torresmartinez.org

Date: 6/13/2011 via e-mail to EEGuidanceComments@epa.gov Response: The fact that a particular “best management practice” is not mandatory for a specific source in a given area does not mean that it would not have been reasonable for air agencies to make it mandatory. Similarly, in light of the historical frequency and nature of high wind events in the area, it may have been reasonable for air agencies to encourage agricultural sources to implemen t the voluntary BMP more broadly or effectively. The EPA will assess scenarios on a case-by-case basis.

7.5.2. Comment: Use of USDA Best Management Practices The guidance suggests that U.S. Department of Agriculture best management practices (BMPs) could be a source of reasonable c ontrols for exceptional events (High Wind document, pages 3 and 12). USDA BMPs are developed to prevent soil loss—they are not intended to protect public health. BM Ps are not BACM and it is certainly not appropriate to use such measures as a surrogate for public health protection. Specific reference to guidance text: High Winds Guidance document, pages 3 and 12
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: While many of the U.S. Department of Agriculture’s best management practices focus on soil loss/erosion prevention approaches, other BMPs are designed to effectively reduce fugitive dust emissions and prevent loss of soil during high winds. (See http://www.nrcs.usda.gov/wps/portal/nrcs/main/ ) The EPA has clarified in the revised draft guidance documents that implemented BMPs that reduce air and dust emissions may be part of the menu of controls that the EPA would consider to be reasonable.

7.5.3. Comment: Definition of “Reasonable”- The terms “reasonable,” “reasonably controllable” and “reasonably controlled” are used throughout the documents and are crucial in deciding whether monitored emissi ons are exceptional or are the result of inadequate (or nonexistent) controls. For ser ious nonattainment areas, like the Southern Owens Valley (Owens Lake) and Mono Basi n (Mono Lake), Best Available Control Measures (BACM) must be required to be in place and fully operational on all anthropogenic sources that cause or contribut e to PM standard exceedances. Reasonably Available Controls (RACM) or other lesser leve ls of control are not sufficient for serious nonattainment areas. It appears that this may be required by the current draft guidance; however, the requirement is a footnote (#16) on page 13 of the High Winds document. This requirement should be made very clear . Effective BACM developed specifically for
the source areas to be controlled should be eff ective in controlling emissions in all but the very highest winds—this is, after all, the whole point of a Best Available Control Measure. In addition, agencies must prove that actual controls were in place and operational—not just that controls are require d by rule or regulation and are presumed to be in place. Our guiding principle of protecti ng public health requires us to do our very best to control anthropogenic sources on hi gh wind days, especially if the winds cause PM emissions from undisturbed areas. These are just the conditions that cause theDraft for Public Notice and Comment
Revision Date: June 2012 57

greatest threat to public health and are the conditions under whic h we should be making our best efforts at public protection. Specific reference to guidance text: High Winds Guidance document, reasonable
controls
Submitter: Ted Schade, Great Basin Unified Air Pollution Control District, tschade@gbuapcd.org

Date: 6/15/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA agrees with the commenter and has clarified the revised draft High Winds Guidance document by moving the referenced footnote into the body of the
document.

7.5.4. Comment: Page 14 of the High Winds Guidance document says “ In areas where events continue to recur, EPA may consider BACM, or greater levels of control, as the appropriate starting point, regar dless of attainment status.” Where does the EPA attain the legal right to consider BACM or greater levels of control as the appropriate starting point regardless of attainment status for areas where events continue to recur? There is nowhere in the Clean Air Act that give th e EPA that authority. General RACM is required for nonattainment plans (CAA Sec tion 172(c)(1), CAA Section 182(a)(2)(A) – RACT for Marginal ozone nonattainment areas, CAA Section 182(b)(2) – RACT for Moderate ozone nonattainment areas, CAA Section 189(a)(1)(C) – RACT for moderate

PM 10 NAA, Section 190 – RACM and BACM guida nce. Further, page 2 of the High Winds Guidance document “....states are expected to consider and implement further
controls as events continue to recur.” How are areas that are designated attainment for

PM 10 (and PM 2.5 ) at the time of the exceptional events supposed to implement further controls (i.e. more stringent controls) on sources that will not even voluntarily commit to
emissions reductions controls? There is no le gal requirement for them to do so. Most
sources that contribute to PM 10 exceedances will not commit to control measures until forced to (i.e. nonattainment designation/threat of loss of highway funds). Specific reference to guidance text: High Winds Guidance document, pages 2 and 14
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: The NAAQS are established for polluta nts considered harmful to public
health and the environment. When the EPA c oncurs on an air agency’s request to exclude data attributed to an exceptional event, the EPA must ensure that the concurred upon events are, in fact, exceptional and meet both statutory and regulatory requirements. The Exceptional Events Rule allows air agencies to request the EPA to disregard certain exceedances which meet the requirements of the Clean Air Act and the EER, including the requirement to implement reasonable cont rols. Air agencies are not required to flag data, petition the EPA, or meet the requiremen ts of the EER; these actions are voluntary. Air agencies not petitioning the EPA to excl ude certain exceedances might be designated to nonattainment, with BACM requirements following. Before submitting an exceptional events request to the EPA, air agencies may have voluntarily chosen to pursue controls, including RACM, BACM, or other controls, to avert an eventual nonattainment designation. These measures should be viewed as voluntary proactive control strategies, not as EPA required actions, as the exceptional event identification, demonstration, and review process is voluntary for state, local and tribal agencies.

By starting point, the EPA m eans that the final analysis of reasonable controls could
include either fewer or more controls than identified in the reference list of RACM or BACM measures depending on the specifics of th e case as they existed at the time of the event. The EPA has modified the language in the revised draft High Winds guidance document. The EPA also notes that while RACM or BACM may be appropriate to implement under the specific sections of the CAA identified by the commenter, theDraft for Public Notice and Comment
Revision Date: June 2012 58

exceptional event requirements under section 319 of the CAA are separate and distinct. To qualify as an exceptional event under sec tion 319 of the CAA and the associated promulgated regulations, submitting agencies must meet the underlying requirements including identifying what cons tituted reasonable controls for a particular event. The lack of a formal area designation does not, in itself, mean that no controls would have been reasonable to have been in place. Rather, the physical facts related to the event determine
what constitutes “reasonable controls.” S ee also the response to comment 7.4.4.

7.5.5. Comment: It should be made clear that reasonable controls are not required to be in place for the first high wind dust exceptional event in a PM 10 attainment area. This is important since PM 10 attainment areas will likely not ha ve any SIP approved or local dust control rules in place for sources like agri cultural operations, and thus it would be impossible to make the control findings. (Note: Santa Barbara County has historically
been in attainment of the federal PM 2.5 and PM 10 standards, and has no PM dust control rules in place for agricultural sources. The north ern half of the County has large stretches of contiguous agricultural lands that at times get wind whipped, producing visible
emissions and above normal PM 10 concentrations). Specific reference to guidance text: High Winds Guidance Document, Section 3.1.2
Submitter: Brian Shafritz, Santa Barbara County Air Pollution Control District, ShafritzB@sbcapcd.org

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: See response to comment 7.4.4. and 7.5.4.

7.5.6. Comment: The U.S. EPA's first principle in developing the Draft Guidance states,
"States should not be held accountable for exceedances due to events that were beyond their control at the time of the event." High wind events will recur in the naturally dry arid regions of the West. Although reasonable measures to help mitigate the impact of these events should be implemented, su ch exceedances are fundamentally not preventable. We are especially concerned th at the Draft Guidance suggests that despite a
state's documentation that an uncontrollable wind event occurred, the U.S. EPA could still disapprove the exceptional event based on th e U.S. EPA’s staff’s concerns regarding the adequacy of PM 10 control measures. The determination as to whether a state has reasonable control measures in place should be an independent analysis taking into account technical feasibility and cost-effectiveness.

If the U.S. EPA were to implement the guida nce as proposed, states could be required to develop an attainment demonstration base d on a value that is the result of an uncontrollable wind event. Such a State Impl ementation Plan would not be approvable, since there is no attainment strategy that can prevent exceedances caused by high Wind events. This is precisely the situation the U.S. EPA's first principal is designed to prevent. Specific reference to guidance text: none Submitter: Lynn Terry (Deputy Executive Office r) for James Goldstene (Executive Officer), California Air Resources Board, ksnyder@arb.ca.gov

Date: 6/24/2011 letter to Gina via e-mail to EEGuidanceComments@epa.gov Response: As previously discussed, local high wind thresholds should define the conditions capable overwhelming reasonable controls on anthropogenic sources (i.e., significant emissions from controlled sources) or causing emissions from natural undisturbed areas. The EPA supports the approach of a priori determining whether controls are adequate for exceptional even ts purposes as long as an analysis of an applicable high wind threshold is included (or referenced). For example, we could prospectively agree that a reasonable set of high wind dust controls are effective only up to sustained winds of 25 mph. Subsequently, events with wind speeds at or above 25 mph where such controls are in place generally would be considered to be not reasonablyDraft for Public Notice and Comment
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controllable or preventable. In this case, any exceedances resulting from events with wind speeds less than 25 mph wind would either not be submitted to the EPA for data exclusion approval or would need additiona l justification. See response to comment

7.4.1.

In response to the commenter’s second point re garding the development of an attainment
demonstration based on a value that is the result of an uncontrollable wind event, the EPA refers to the commenter to response to comment 6.5.1. and Question 13 in the revised draft Q&A document. The EPA has al so added language addressing this point in the revised draft High Winds Guidance document.

7.5.7. Comment: Contrary to the U.S. EPA's interpretation, the Clean Air Act does not authorize the U.S. EPA to require that anth ropogenic sources of emissions be "reasonably controlled" in order to exclude a high wind event. Section 319(b)(1)(A) of the Clean Air Act defines the term "exceptional event" and includes the requirement that the event "is not reasonably controllable or preventable." U nder the statute, the relevant criterion is whether the event itself is reasonably controlla ble, not whether the effects of the event
could have been limited or controlled. Ther e are two types of exceptional events: those caused by human activity that is unlikely to recur, and those cause by "natural events." While the degree of control on anthropogenic sources may be relevant to an exceptional event caused by human activity (e.g. a chemical spill), by the plain language of the statute
it is not relevant to whether a natural event "is not reasonably controllable or preventable." In short, an agency cannot do anything to "control or prevent” the wind. The U.S. EPA has attempted to address this c oncern by redefining the term "event" to include both the high wind and the resulting dust emissions. This definition is illogical
and convoluted. There is a clear difference be tween an event (high winds) and the results of the event (dust emissions). With respect to "natural events," the relevant consideration
under the statute is whether the event itself is controllable or preventable. The Clean Air Act may allow consideration of controls on anthropogenic sources in deciding whether an exceptional event due to human activity is cont rollable, but the wind event itself is not
controllable.

Whether reasonable controls are applied to anthropogenic sources may be relevant to a separate provision of the Clean Air Act, but under that provision, the U.S. EPA's Exceptional Events Rule has already expressly decided that a demonstration of the degree of control will not be required. Therefore, to the extent the proposed Guidance would require a state to demonstrate that it has a pplied "reasonable controls" before excluding an exceptional event it violates the Exceptiona l Events Rule. The U.S. EPA's Exceptional Events regulation is authorized to consider several principles, including "the principle that each state must take necessary measures to safeguard public health, regardless of the source of the pollution." CAA section 319(b)(3)(iv). Under this principle, the U.S. EPA has already decided that it will not require st ates to control anthropogenic sources. In implementing this principle, the Exceptional Events Rule says that mitigation measures a state may take "may or may not include the implementation of control measures on contributing anthropogenic sources related to an event." 72 Fed. Reg. 13560, 13576. (March 22, 2007). Thus, control of anthropoge nic sources is not automatically required. Further, the U.S. EPA said that "the implem entation of RACM or BACM is not required ... " (id.) Finally, the U.S. EPA expressly ruled that it "will not be requiring States to submit documentation concerning the actions that it (sic) took to mitigate the impact of exceptional events, in order for U.S. EPA to exclude data from regulatory consideration." The U.S. EPA's Proposed Guidance thus viol ates its own Exceptional Events Rule as well as the express terms of the Clean Air Act. This issue is currently being litigated inDraft for Public Notice and Comment
Revision Date: June 2012 60

Imperial County Air Pollution Control District v. U.S. EPA, Ninth Circuit Court of Appeals No.10-72709.

The term "reasonable" is used in terms of controls in relation to the "not reasonably controllable or preventable" discussion. As di scussed above, the U.S. EPA's use of this phrase to require that the effects of the event, rather than the event itself, be reasonably controllable or preventable, is not authori zed by the Clean Air Act or the U.S. EPA's Exceptional Events Rule. While we agree that effective controls should be in place to protect public health, which is our most importa nt consideration, the cost versus benefit of controls plays role in determining what control measures are reasonable in a given area
or situation. Additional clarification in th e guidance and the language of the Exceptional Events Rule itself may help state and local agencies identify the wind-driven anthropogenic sources in the area and to assess what controls could be applied.

If the U.S. EPA continues to take the po sition that anthropogenic sources must be reasonably controlled in order to exclude data, it must at least recognize that in some cases, even reasonable controls would not ha ve prevented the exceedance. States must have the ability to make the case to the U. S. EPA that those sources were reasonably
controlled at the time of the exceedance and that the exceedance occurred despite the implementation of those controls, or that if th e controls were not in place, they would not have prevented the exceedance in any case. The discussion of reasonable controls (Section 3.1.2) seems to indicate that agenci es may only know the U.S. EPA's assessment of our control strategy for future events b ased on notice from the U.S. EPA that the U.S. EPA "considers controls on particular uncont rolled sources to be reasonable (e.g., as part of a previous exceptional event review)." Table 2 of the guidance provides some good insight into the thought process that th e U.S. EPA will use for determining the reasonableness of controls. The difficulty is in how to best assess the adequacy of controls for events without that history of the U.S. EPA concurrence. Furthermore,
additional clarification is needed on how s ource contributions that cross jurisdictional boundaries should be treated. One such example is particulates entrained from
thunderstorms outflows over the deserts of northern Mexico or Arizona that affect
measurements in California where the winds rema in low. It is not completely clear what level of analysis is needed for such a tran sport case and whether a controls analysis is needed when anthropogenic sources are out of the air agency's jurisdiction.

While AQMD has one of the most comprehens ive and highly effective control programs in the country, there is concern that a minor source that is not considered fully controlled
in the U.S. EPA assessment could stall this process. Do all known anthropogenic sources
in an area need to be controlled to the full extent possible for BACM to be considered to be in place? Additional discussion in th e guidance will help submitting agencies
determine if their controls s hould be adequate and will help provide consistency within the U.S. EPA among the reviewers of excepti onal event documents. To illustrate this concern, the example of reasonable agricultura l controls is used. Can agricultural sources be adequately controlled with existing soil management practices (such as those from the U.S. Department of Agriculture's Natura l Resources Conservation Service) or could stabilization of plowed or otherwise disturbe d farmland be required, similar to what is often required of construction sites? Many w ould argue that such agricultural controls would be neither appropriate nor reasonable, for both economic and ecological reasons. Would air agency rulemaking to require best soil management practices on agricultural
lands be needed in order to be able to co nsider agricultural source contributions to be reasonably controlled, or is soil management guidance adequate? Therefore, if the U.S. EPA elects to incorporate "reasonable control" in spite of our comments, any use of the term "reasonable control" must be clearly defined.Draft for Public Notice and Comment
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Specific reference to guidance text: High Winds Guidance document
Submitter: Barry Wallerstein, South Coast Air Quality Management District

Date: 6/28/2011 via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: The EPA agrees with the commenter that in some cases, there are no feasible
and reasonable cost controls that would ha ve prevented the exceedance. This is the concept behind the development of the pros pective controls analysis (described in additional detail in the response to comment 7.4. 1.). In a prospective controls analysis, air agencies should first identify an appropriate high wind threshold for an area and identify and implement “reasonable” controls that are exp ected to be effective up to that threshold speed. Once the EPA agrees with the identified controls and high wind threshold for that area, then, events with wind speeds above th e high wind threshold would generally be assumed to be not reasonably controllable or preventable since implemented controls would be overwhelmed above the high wind th reshold. Further, the EPA would generally
assume that PM emissions below the wind th reshold have been re asonably controlled. See responses to comments 6.5.2. and 7.3.2. In addition, as noted in the response to comment 7.4.1., the prospective controls anal ysis can be prepared and submitted to the EPA in advance of any event as CARB suggests, with a letter of intent, or as a component of a demonstration package. The EPA encourages submitters to use prospective analyses as a means of communicating and reaching a common understanding in advance of an event.

The EPA further agrees with the commenter th at the mitigation requirements discussed at 72 FR 13576 allow air agencies to make dete rminations regarding reasonable mitigation
measures and that these reasonable meas ures “may or may not include the implementation of control measures on contri buting anthropogenic sources related to an event...” The EPA notes, however, that m itigation plans address measures that an air agency takes after an event. These meas ures may or may not be “reasonable” when addressing the “not reasonably controllable or preventable” criterion within an event demonstration package.

The EPA does not intend to determine the adequacy of any individual control measures or practices in this response to comments document or in the revised draft guidance documents. Rather, we will assess reasonabl e controls as part of a demonstration submittal or as part of a prospective controls analysis. The EPA is not taking any position in this document on what controls may or ma y not be reasonable for plowed or otherwise
disturbed farmland.

The commenter also requests clarification re garding cross-jurisdictional boundary issues.
The EPA addresses both interstate and interna tional transport in the response to comment 6.4.1. and in Question 23 in the revised draft Q&A document. The EPA refers the commenter to these responses.

7.5.8. Comment: The "reasonableness of existing controls" and the required controls analysis assumes a regulatory structure that does not exist on the Community. GRIC has two adopted RACT level regulations for the significant PM-10 point source categories. Ordinances also are in place for area sources such as earth moving, material handling unpaved parking lots, disturbed surface areas, et c. However, agriculture does not have a regulatory program, other than for the control of pesticide application, specifically applicable to it. Thus, if the phrase "contro l measures in place" means controls necessary to satisfy a regulatory requirement, GRIC does not meet the requirement. The reason is primarily cultural and traditional properties of the Community that are protected by both tribal and federal regulation. The central cu ltural concern for the Gila River Community is agriculture. The Akimel O'odham peop le are culturally and traditionallyDraft for Public Notice and Comment
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"agriculturalists" as opposed to "hunters and ga therers." The Community's very existence is founded upon agriculture and farming activiti es with a relationship and respect for the land and water. Any attempt to regulate ho w farming is conducted will be immediately opposed by the Community's decision makers. Of course, regulation of activities that directly relate to the safety of workers or Community members is as stringent as elsewhere, but regulation of the methods of tilla ge or the nature of how crops are grown is an anathema to the Community. This be ing said, the Community appreciates the need to control and mitigate dust from farming activities and has led the local farming jurisdictions in their ability to respond to the mitigation of dust issues. While the Community has developed and voluntarily im plemented significant Best Management Practices, they have not been imposed as regulations but rather are adopted as Community farming methods. It is important to note that this is a voluntary, not a regulatory program, and the controls analysis contemplated by this guidance appears to be based entirely on the effectiveness of regula tion, not the effectiveness of the voluntary control measures being implemented. It woul d be unreasonable to assume that cultural and traditional practices would be regulated under this guidance and such regulation would be unnecessary.

“...there is a requirement that if dust fro m undisturbed natural desert is cited as a contributing cause of an exceedance, which causal connection must have "appropriate supporting documentation." The Community is entir ely rural in character with large tracts of land that are undisturbed desert. However, it is unclear what documentation EPA expects to verify this condition or the fact that dust can be entrained from these tracts of
land.” Specific reference to guidance text: High Winds Guidance document
Submitter: Leroy Williams (Environmental Engineer) for William Rhodes (Governor), Gila River Indian Community, williams@gilanet.net

Date: 6/23/2011 via letter to Gina with cc e-mail to EEGuidanceComments@epa.gov Response: The EPA commends the Community for recognizing the need to control and mitigate dust from farming activities and for lead ing the local farming jurisdiction in their ability to respond to mitigation of dust issu es. The commenter notes that the Community has developed and voluntarily implemented significant Best Management Practices. They have not been imposed as regulations but rather are adopted as Community farming methods. The EPA will consider currently im plemented controls at the time the event occurred, including voluntarily developed a nd implemented Best Ma nagement Practices in reviewing the "not reasonably controllable or preventable" element when reviewing tribal exceptional event demonstration submittals. The EPA may consider such implemented controls to be "reasonable" depe nding on the event. Conversely, it may be
unreasonable not to have had certain controls in place when the even t occurred. Thus, the EPA's controls analysis is not restricted "en tirely on the effectiveness of regulation, [but could also consider] the effectiveness of the voluntary control measures being implemented."

Additionally, the commenter makes a second point regarding the need for "appropriate supporting material" where dust from undisturbed natural desert is cited as a contributingcause of an exceedance. While the EPA’s position is generally that impacts from windblown dust from undisturbed natural deserts are inherently not reasonable to control, the tribe (or state) would need to assert this and provide a ppropriate supporting documentation in its demonstration pack age. The supporting documentation should include descriptions of the geographic area (with maps or available visuals) and a discussion of the historical land use, including prior disturbances, water diversions and other historical practices which may have o ccurred on the land, even if the land seems or is considered to be “undisturbed” at presen t. Submitting agencies should also identify allDraft for Public Notice and Comment
Revision Date: June 2012 63

sources contributing to an event and identif y appropriate control strategies for each anthropogenic source.

7.5.9. Comment: “EPA's requests to provide a comprehens ive controls analysis that has back trajectories indicating specific sources in the upwind area, an inventory of the contribution for the significant sources, and detailed descriptions of controls and their effective implementation and enforcement is an excessive and unreasonable requirement. EPA needs to be realistic in establishing requirements for determining that reasonable controls were in place for the exceptional event documentation process. As in past approvals, EPA should recognize and streamline the approval process for areas that have implemented comprehensive BACM controls, such as the San Joaquin Valley. Similarly, the draft guidance includes a requirement that analyses be performed to determine whether natural sources were reasonably c ontrolled during exceptional events. In an example included in the draft guidance, EPA cites performing an analysis of whether windbreaks and other potential controls are fe asible as part of establishing whether reasonable controls were in place. Given the large potential geographic areas that contribute to exceptional events, and the implementation of comprehensive BACM controls, this requirement seems onerous and unreasonable.” Specific reference to guidance text: High Winds Guidance document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: In response to comments received, th e EPA has developed the concept of a prospective controls analysis that includes in formation on attainment status, identification of natural and anthropogenic windblown dust sources and emissions, the status of SIP submittals (if applicable), and identification of the high wind threshold up to which the collective windblown dust controls are expected to be effective. (The EPA describes this concept in additional detail in the revised draft High Winds Guidance document and in the response to comment 7.4.1.) In addition, as indicated in the response to comment 7.4.1., the submitting agency can use SIP-appr oved controls in place of the prospective controls analysis if the following conditions are met:

 The EPA has approved the SIP within the past three years 6

 The SIP contains controls specifically for high wind dust events. The EPA will only consider as relevant, BACM or RACM for high wind dust for serious or moderate non-attainment areas, respectiv ely (i.e., the EPA would consider BACM for harvesting operations irrelevant).

 The submitting agency has specified a high wind threshold up to which the controls are expected to be effective.

Once the EPA determines that the currently implemented controls are reasonable and the high wind threshold is appropriate, then the submitting agency can reference the prospective controls analysis in the “not reasonably controllable or preventable” portion of submitted packages for events exceeding the high wind threshold rather than preparing new controls analyses and “not reasonably c ontrollable or preventable” demonstrations. The EPA has clarified this position in the revised draft High Winds Guidance document.

6 EPA has identified 3 years as the “approvable” timefra me for SIPs. EPA believes that 3 years is reasonable because it corresponds to the minimum ti me used to represent recurrence and historical fluctua tions. EPA further believes that BACM measures in a SIP older than 3 y ears may not constitute all “reasonable” measures because physical conditions in the SIP area may have changed, new monitoring sites may show air quality impacts not previously realized, control technology may have advanced, and the resources available in the community to apply controls may have increased.Draft for Public Notice and Comment
Revision Date: June 2012 64

7.5.10. Comment: The draft policy requires that a determ ination be made that controls were properly enforced during an exceptional ev ent, and suggests that the number of inspections and notices of violations in upw ind areas be considered as evidence that all reasonable controls were implemented and func tioning appropriately. This requirement is unreasonable and inappropriate for areas that have successfully implemented comprehensive BACM controls through ma ture permitting and enforcement programs, such as in the San Joaquin Valley. Additiona lly, Exceptional Events can occur during off hours with limited staffing or in remote ar eas and the requirement to enforce controls appears unreasonable in these situations. Specific reference to guidance text: High Winds Guidance document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA has revised the draft High Wi nds Guidance document to state that agencies should submit available inspection reports and/or notices of violations (NOVs) in upwind areas as evidence regarding whether all reasonable controls were implemented and functioning properly at the time of the event. The EPA recognizes that agencies have varied methods of permitting and enforcement and does not expect all agencies to have these records for all events. The EPA does, how ever, expect agencies to make a general showing that controls are being enforced to a reasonable degree (not necessarily on the particular day of the event). The EPA does not expect detailed records for events with wind speeds above the high wind threshold.

7.5.11. Comment: “Imperial County APCD is extremely c oncerned with EPA's direction, which is at variance with the state's planning process for high wind events. Air Districts and states have to plan years ahead and setup th eir strategies to protect the public during a high wind episode. The air districts and states have to develop, adopt, and approve
RACM/BACM rules in efforts to meet state and national air quality standards and also do this in anticipation of high wind events. If EPA has concerns with RACM/BACM rules adopted and approved by the local air district board and which are further approved by the states, EPA should use the process of development of the rules to submit their potential deficiency comments to these rul es. The manner in which EPA proposes to evaluate RACM/BACM for high wind episodes in this draft guidance is not appropriate, nor productive. In this proposed draft guidan ce, EPA is evaluating rules in retrospect during which time it is highly unlikely that th e local agencies and states would be able to resolve the issue by rule making. Instead, Im perial County APCD feels that EPA should not use the process of high wind episodes to contest RACM/BACM rules and concentrate only on the actual enforceability of these rul es during the time of the event. If EPA finds
deficiencies with the rules and determines th at those rules need to be updated, EPA should work with the air districts and states by mutually agreeing on process and revision context of the rules to prevent any potential fu ture impacts to the public. Imperial County APCD strongly opposes EPA's proposed language that basically conditions approvability and concurrence, or not, of high wind or other exceptional events on EPA-perceived deficiencies with the RACM/BACM rules due, in part, to lack of EPA's timely action on reviewing and approving said rules.”

Imperial County APCD also provided inform ation re their review of the High Winds Guidance doc (see Submitted Comments\Need OCR\ICAPCD_Poiriez_062911- OCR.pdf )

Specific reference to guidance text: High Winds Guidance documentDraft for Public Notice and Comment
Revision Date: June 2012 65

Submitter: Brad Poiriez, Imperial County Air Pollution Control District, bradpoiriez@co.imperial.ca.us

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA does and will continue to use the rule process to comment on RACM/BACM. The EPA further proposes to address the commenter’s concerns by implementing a prospective review of contro ls/threshold – see also response to comment
7.4.1. and 7.5.9.

7.5.12. Comment: “As a condition for approval of an exceptional event request, the draft guidance requires a State to demonstrate, to the satisfaction of the EPA regional office, that any control measures that could “reasonably” have been in place at the time of the event must have been in place, including escalating control measures in areas subject to recurring dust events. WESTAR reiterates its view that if a specific set of controls is required that is not currently in the State Im plementation Plan, it is EPA’s responsibility to notify the State of the SIP deficiency or to clearly articulate in the regulation what emission controls are required as a conditi on of an exceptional events approval.” Specific reference to guidance text: none Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA proposes to address this by de-emphasizing recurrence and by providing an opportunity for developing a nd implementing a prospective review of controls/threshold – see response to comment 7.4.1. and 7.5.9

7.5.13. Comment: “The Clean Air Act § 110 provides a clear process that EPA must follow when requiring an increase in stringency of controls on significant sources of air pollution, including the requirement that EPA issue a SIP call, give public notice, provide the public an opportunity to comment, and res pond to public comments. EPA’s intent to circumvent §110 of the Act under cover of the draft guidance is set forth in § 3.1.2 in footnote 16 on Page 13: Legally, EPA believ es the event-relevant measures that have already been included in the approved SIP as RACM or BACM to be an essential part of the set of controls that need to be in place for an event to be considered “not reasonably controllable or preventable,” but they may not be sufficient by themselves particularly if the SIP has not been recently reviewed or revised. (emphasis added) Clark County believes that control measures in an approved SIP should always meet the “...reasonable and appropriate measures (72 Fe d. Reg. 13560, 13566 (Mar. 22, 2007))” criteria of the EER. Clark County believes that any action by EPA to require revisions to a state’s SIP control measures without following the Clean Air Act § 110 processes exceeds EPA’s authority under the Act and falls outside the purview of the EER. Clark County therefore encourages EPA to revise the draft guidance to indicate that where states are not under the provisions of an attainment/maintenance SIP, RACM level controls on affected anthropogenic sources will comply with the reasonable and appropriate measures requirements of the EER. Where the state falls under the provisions of an attainment or maintenance SIP, the approved control measures in the SIP will meet the reasonable and appropriate measures requirements of the EER.” Specific reference to guidance text: High Winds Guidance document
Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EER does not impose new control requirements on sources or areas; rather, it defines the conditions under which certain exceedances and violations of the NAAQS are excluded when determining attainment. Per Section 319 of the Clean Air Act, reasonable measures to control wind-b lown dust are a precondition for the EPA concurrence. This does not, however, impo se mandatory requirements on agencies or districts. Requesting exclusion of data under the EER is optional and voluntary.Draft for Public Notice and Comment
Revision Date: June 2012 66

To make the exceptional events process more efficient for those who choose to pursue it, the EPA proposes to make the determination of the adequacy of controls for exceptional events purposes in advance of reviewing a complete exceptional event demonstration package by implementing a prospective review of controls including a high wind threshold. We have revised the draft High Winds Guidance document to indicate that implementing windblown dust BACM that has been recently approved or reviewed (within the past three years) generally should be adequate to satisfy the “not reasonably controllable” element provided the high wind threshold is exceeded. Further, we have revised the BACM/RACM language in the revised draft High Winds Guidance document to clarify that we will only consider wi ndblown dust BACM as relevant BACM measures to reasonably control windblown dust during high wind events. See also the response to
comment 7.4.1. and 7.5.9.

7.5.14. Comment: The second guiding principle of the draft guidance states that it is desirable to implement reasonable controls to protect public health (draft guidance, p 1, emphasis added) which suggests RACM for attainment, unclassifiable, or moderate nonattainment areas and BACM or Most Stringent Measures for serious nonattainment areas. “Section 3.1 et. seq. of the draft guidance, which est ablishes criteria for when an event is not reasonably controllable or preventable, sets forth de facto requirements which significantly exceed those set forth in the EER and which supersed e the § 110 planning provisions of the Clean Air Act. In § 3.1.2 of the draft guidance the EPA states: If a set of control measures could reasonably have been in place for contributing sources at the time of the event, then they must have been in place for the event to qualify as an exceptional event under the EER. (p 12) This is one of several provisions in the guidance which exceed the scope of the EER and effectivel y turns the draft guidance document into a regulation. In § 3.1.2 on Page 14 of the draft guidance, the EPA states “. . . it could be reasonable to require controls more stringent than BACM or RACM, particularly in areas with recurring exceedances.” The EPA’s expect ation that states would need controls “more stringent than BACM” to establish that an event was “not reasonably controllable or preventable” is illogical and is not suppor ted by the language in the regulation. This expectation would also place extreme financ ial burdens on both air regulatory agencies and stakeholders that likely cannot be supported in the current economy.” Specific reference to guidance text: High Winds Guidance document
Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: Developing a prospective review of controls allows resolution in the planning/rules context before the exceptional event demonstration review process. We have revised the draft High Winds Guidance document to indicate that implementing windblown dust BACM that has been recently approved or reviewed (within the past three years) generally should be adequate to satisfy the “not reasonably controllable” element provided the high wind threshold is exceeded. Further, we have revised the BACM/RACM language in the revised draft High Winds Guidance document to clarify that we will only consider windblown dust BACM as relevant BACM measures to reasonably control windblown dust during high wind events.

7.5.15. Comment: “ EPA should prov i de that implementation of Reasonably Available Control Measures ("RACM") and Best Available Control Measures ("BACM") will be
considered to meet EER requirements related to "reasonably controllab l e or preventable." Specific reference to guidance text: varies (additional documentation to support recommendation is provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf )Draft for Public Notice and Comment
Revision Date: June 2012 67

Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See responses to comments 7. 4.1., 7.5.9., and 7.5.14.

7.5.16. Comment: Not reasonably controllable or preventable – “The guidance incorrectly treats reasonable controls as a pre-requisite fo r concurring with an exceptional event demonstration, regardless of whether the r easonable controls woul d have prevented the
exceedance.”

EPA considers a source that is "reasonably controlled" to be one whose emissions were not reasonably controllable or prevent able"; therefore, these terms are used interchangeably throughout this do cument for anthropogenic controls. Comment: We suggest deleting this senten ce (High Winds Guidance document, Section 3.1, page 13)

EPA also generally considers that wind-genera ted dust from previously disturbed land ... is also not reasonably controllable or preventable, provided that there are no reasonable active measures that could be taken to control dust during the transition back to natural
conditions. Comment - This incorrectly omits consideration of whether the "reasonable active measures" would have prevented the exceedance . We suggest adding the following to the end of this sentence, "unless the reasonable active measures would not have prevented the exceedance." (High Winds Guidance doc ument, Section 3.1. 1, paragraph 2)

"If reasonable controls on wind-driven anthropo genic sources were not in place, then the
event would not be considered "not reasonabl y controllable or preventable" and would not satisfy the nRCP element of the definition of an exceptional event. That is, to meet the EER the state should identify wind-driven contributing anthropogenic sources and show that reasonable controls were in place." Comment - This incorrectly eliminates "prevent able." We believe that concurrence with a
demonstration in areas where "reasonable contro ls" were not in· place is required if the area can show that that winds were so high th at even reasonable controls could not have prevented the exceedance. We suggest adding the following sentence; "However, in areas where reasonable controls were not in place, the NRCP element could be satisfied if the
area can show that those "reasonable co ntrols" would not have prevented the exceedance." (High Winds Guidance docum ent, Section 3.1.1, paragraph 3)

"Under the EER the event must be "not reasonably controllable or preventable" [emphasis added]; therefore, controls need not prevent the exceedance altogether to be
reasonable." Comment - We agree that whether the contro ls prevent the exceedance has nothing to do
with the reasonableness of the control. We al so agree that it is appropriate to emphasize
the word "or.” We believe the error occurs in next sentence of that paragraph. "If a set of control measures could reasonably have been in place for contributing sources at the

time of the event, then they mu st have been in place for the event to qualify as an exceptional event under the EER." That sentence either ignores "preventable" or effectively replaces "or" with "and" by requiring that both conditions "reasonable controls" AND "preventable" to be satisfied . We suggest that the following clause be added to the third sentence in the paragraph, "unless the state/local can show that the reasonable controls would not have prev ented the exceedance.” (High Winds Guidance document, Section 3.1.2, paragraph 1)Draft for Public Notice and Comment
Revision Date: June 2012 68

Specific reference to guidance text: varies – see notes
Submitter: Larry Greene (Executive Director), Sacramento Metropolitan Air Quality Management District

Date: 6/30/2011 letter via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: The EPA generally agrees with the commenter on these issues and believes that the revised draft guidance reflects th e spirit of the above comment. The EPA’s revised draft guidance includes a prospective c ontrols analysis (discussed in more detail in the response to comment 7.4.1.). The pros pective controls analysis should identify the set of reasonable controls and the wind speed up to which the rules are expected to be effective. The EPA expects that when winds are above the established high wind threshold, the set of pre-approved reasonable controls for the identified sources could be overwhelmed, resulting in the event being not reasonably controllable or preventable. In determining whether the event is not reasonabl y controllable or preventable, the EPA will
consider whether the collection of anthropogenic sources has been reasonably controlled. For the EPA to consider the event to have been not reasonably controllable or preventable requires, among other considerations, th at reasonable controls were in place on contributing anthropogenic sources. Since each source contributes incrementally, it is unlikely that controls on any one source w ould prevent an exceedance. Therefore, the EPA’s approach is to consider the collection of controls in its assessment of whether the event was not reasonably controllable or preven table. See response to comment 7.4.4. for areas that are attaining the standard.

7.5.17. Comment: “What constitutes ’reasonable control’ - We suggest that the guidance rely on or more closely follow the process used wh en states conduct control measure analysis procedures used in plan preparation (e.g. RACT demonstrations) and not expect more stringent controls than required by the areas nonattainment designation and classification status without adequate notice by EPA to th e state/local.” Sacramento Metropolitan Air Quality Management District supports Table 2 in Section 3.1.2 but suggests revisions that more closely follow the state (RACT/RACM) analyses process.”

Comment – “We suggest revising Table 2 to first identify ’reasonable controls,’ and IF a reasonable control is identified that was NOT in place, the state/local then conducts an analysis to show whether the reasonable c ontrol would have prevented the exceedance. Only if ’reasonable controls’ are identified that are not in place would you evaluate whether the exceedance is preventable. If mu ltiple ‘missing’ reasonable controls are identified, then, similar to EPA's RACM guidan ce, the state must show that the collective benefit of all missing reasonable controls would not have prevented the exceedance. If they would not have prevented the exceedance, then we believe EPA should not object to the exceptional event request.”

Comment – “We suggest reordering the discussions in Table 2. Items numbered 1, 2, 4, 5, and 6 relate to identifying what are the ‘reasonable controls’ and should be grouped together as the first part of the analysis. Items 3 and 8 would go next. Item number 3 relates to whether the ‘preventable’ analysis is required. Item 8 appears to reflect
consideration of whether ‘de minimis’ cont rols would have prevented the exceedance and are not required. Item 7 relates to whether th e collection of all reasonable controls would have prevented the exceedance. We suggest that item 8 be a component of the analysis to determine whether control(s) would have ’p revented’ the exceedance. We suggest that item 7 be the last step in the analysis and add the following sentence. ‘Reasonable controls are not a required condition for an exceptional event determination, if the
collective benefits of all reasonable controls would not have prevented the exceedance.’”Draft for Public Notice and Comment
Revision Date: June 2012 69

Comment –“If a state/local has recently submitted a plan containing a RACM or BACM analysis (as required for the area), that anal ysis should suffice to identify what is a ‘reasonable control’ and the appropriate im plementation timeframe for controls. If the state has implemented those RACM/BACM contro ls, then we believe the state/local has satisfied the ‘not reasonably controllabl e or preventable’ requirement unless EPA previously objected to the state's plan RA CM/BACM analysis. If the state/local has not implemented a control, but is on schedule to implement the reasonable controls, then we
believe the state/local has also satisfied the ‘not reasonably controllable or preventable’ requirement, absent a prior EPA objection to the schedule. We acknowledge the guidance suggests that the state could include justifica tion for why the controls are not in place, but
believe that EPA discretion should be more explicitly limited in these circumstances. We suggest that EPA's concurrence on the initial event should be accompanied by a notification to the state (e.g. SIP call) of the additional required control and to give reasonable opportunity for the state to avoid effects of a future nonconcurrence.”

Specific reference to guidance text: High Winds Guidance document, Table 2 in
Section 3.1.2
Submitter: Larry Greene (Executive Director), Sacramento Metropolitan Air Quality Management District

Date: 6/30/2011 letter via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: See also responses to comments 7.4.1. , 7.4.4., and 7.5.9. If an area is implementing its EPA-approved SIP which includes dust control measures and has been approved within 3 years, has met any other applicable regulatory requirements, and has high wind dust events only when the wind speeds are above the established local high wind threshold, then the EPA would generally consider these events to be not reasonably controllable or preventable. The EPA does not expect additional controls to be put in place if the exceedances only occur when th e wind speed is above the high wind
threshold under conditions when sources ha ve been reasonably controlled. The EPA encourages agencies to address this issue in the prospective controls analysis.

7.5.18. Comment: “ Th e WAQD has se riou s conce rn s regardin g e l ements that are r eq uired fo r the comprehe nsi ve c ont ro l s ana lys is

. The tools tha t EPA has propo se d w ill resu lt i n high ly ina cc urat e r es ult s

. In particu l ar, an e m issi on s in ve nto ry of a s hort

- term fugiti ve dust even t i s unreas o na b l e

. Emission fac t ors currentl y ava ilable for fugi t i ve du s t add a
d eg ree of u n ce r tai nt y to e mi ssio n es tim ate s w h e n taking i nto account th e s hort

- term

natur e and exace rbati on of h igh w ind o n the s ource

. To use a n inventory wit h l ittle or n o

co nfidence in the e mi ss ion rate s in source apportionment modelin g i s in e ffe ct ive

. Additionally, the tool s t hat EPA has spe c ified to p e rform a back

- traj ec tory wi ll require
locali ze d wind fi e ld s to be developed

. Thi s is not alway s possib l e in areas where

n e twork s are s parse w ith lar ge distances ( 5 0

- 100 miles) b e tween m e t eoro lo g i ca l

m o nitoring lo c ation s .” Specific reference to guidance text: High Winds Guidance document
Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA’s approval of an agency’s prospective controls analysis (see response to comment 7.4.1.) should help agencies know if currently implemented controls are reasonable. Demonstration p ackages with wind speeds below the approved high wind threshold will require more rigorous analyses. The rigor of the analyses will depend on how much below the threshold the wind was and the weight-of-evidence from other analyses. The EPA intends to take comme nt on technical analyses that can be used
to demonstrate that the wind exceeded the hi gh wind threshold and that the exceedance was caused by emissions that were not reas onably controllable. The EPA cannot concurDraft for Public Notice and Comment
Revision Date: June 2012 70

on cases where no information on wind speed and reasonable controls is available or provided, regardless of the technical difficulties that this might impose.

7.5.19. Comment: Are wildfires included when we say “areas burned by anthropogenic fires”? Reference is to windblown dust from surfaces that have been significantly disturbed or altered by humans and t hus should be categorized as anthropogenic emissions. Specific reference to guidance text: High Winds Guidance document, page 11, Section

3.1.1
Submitter: Ann Hobbs (Air Quality Specialist), Placer County Air Pollution Control
District

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA has modified the language in the revised draft High Winds
Guidance document that refers to “are as burned by anthropogenic fires.”

7.5.20. Comment: “ADEQ is concerned that the draft guidance does not provide any certainty regarding what control measures qualify as reasonable control measures during an exceptional event. Instead, the guidance appears to indicate that the more often an event occurs, the less exceptional it becomes, ev en though the event is overwhelming the control measures that are in a SIP.” The SIP approval process is the appropriate process for determining the reasonableness of contro l measures based on the classification of the planning area. “ADEQ recognizes that the excessive recurrence of exceedances of the standard would be cause for reconsidering the c ontrol strategy in place. In order to offer States more certainty, it is recommended that EPA consider rule changes that would allow a State and EPA to agree (perhaps through a mechanism such as a High Wind Action Plan) that the selected control measures are reasonable for a period of three to five years. During that time, a State would not need to review the controls that were in place at the time of the event(s) in order to bene fit from the use of the Exceptional Events Rule. After that time period, should exceedances pe rsist or excessively recur, the State and
EPA could review the control measures in the SI P. If additional controls are deemed to be necessary, EPA could use the provisions of Cl ean Air Act Section 11 0(k)(5) to call for an update to the SIP. If no additional controls appear reasonable or necessary at that time,
EPA and the State could enter into an additio nal three to five year agreement that the controls in place are reasonable for that area thereby streamlining exceptional event analyses and providing longer-term certaint y for air quality planning areas.” Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA proposes to address this by pr oviding air agencies an opportunity to engage in implementing a prospective review of controls including a high wind threshold. See response to comments 7.4.1., 7.5.9. and 7.5.13.

7.5.21. Comment: Monitoring sites in rural areas may not collect as much data as those in urban
areas. Has the EPA considered how a control analysis for rural sites for which direct inspection and enforcement data specific to before, during, and after the event are not available? ADEQ recommends that the EPA include a section in the proposed guidance along with comparable examples that represent EE demonstrations in an area with a single filter-based monitor and for which meteor ological data within the direct vicinity
are not available. Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: At this time, the EPA does not have an example of an approvable exceptional event demonstration package for an area w ith no local meteorology and a single filter-Draft for Public Notice and Comment
Revision Date: June 2012 71

based monitor. As demonstrations for unique situations, such as the one identified by the commenter, become available, the EPA will update the Exceptional Events website to include such examples. The EPA has, however, modified the language in the revised draft High Winds Guidance document to address the availability of inspection/enforcement records and local meteorology. The EPA refe rs the commenter to this document and to the responses to comments 7.5.10. and 7.3.10. In addition, during the public review of the revised draft guidance documents, the EPA intends to take comment on technical analyses that can be used to demonstrate th at the wind exceeded the high wind threshold
and also that the exceedance was caused by emissions that were not reasonably
controllable. The EPA cannot concur on case s where no information on wind speed and reasonable controls is available or provided, regardless of the technical difficulties that this might impose.

7.5.22. Comment: “The draft guidance appears to indicate that it is important for submitting agencies to indicate whether natural sources could have been reasonably controlled. ADEQ opposes any suggestion that natural, undisturbed, non-anthropogenic sources should require controls. Such controls on na tural sources might inherently disturb those sources, rendering them anthropogenic sources in EPA's view. ADEQ recommends that EPA revise the draft guidance to make it clear that there is no requirement to investigate
whether natural sources could have been controlled during an event.” Specific reference to guidance text: High Winds Guidance document
Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The statutory definition of an excepti onal event, including a natural event, requires that the event be one that is not reasonably controllable and preventable. For a high wind event implicating only natural, undisturbed and non-anthropogenic sources, not having controls on these sources may be reas onable and therefore considered to meet the not reasonably controllable or preventa ble requirement. Agencies can indicate this point in demonstration subm ittals with a few sentences.

7.5.23. Comment: Washington Department of Ecology believes that the guidance docs describe an escalating series of controls that is outs ide of the statutory framework established by the Clean Air Act. “Should EPA wish to require controls that go beyond a state’s SIP and voluntary commitments under a Natural Events Action Plan or High Wind Action Plan, EPA should not be establishing requirements through guidance. Instead EPA should establish control requirements through notice-and-comment rulemaking.” Specific reference to guidance text: High Winds Guidance document
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of Ecology

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA’s draft guidance documents and the exceptional events website (http://www.epa.gov/ttn/analysis/exevents.htm) present examples to illustrate specific points and are not necessarily required for all demonstrations. See also the response to

comment 7.5.13.

7.5.24. Comment: “ Regional v. Local events. There is another aspect to the requirement in the guidance that controls were implemented “at the time of an event.” This seems to be a reasonable requirement for an event that invol ves local sources. However, many events in Washington’s Columbia Plateau are regional in scope and involve distant sources and can extend for as much as a couple hundred miles.” Specific reference to guidance text: High Winds Guidance document
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of EcologyDraft for Public Notice and Comment
Revision Date: June 2012 72

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA addresses intrastate, interstate , and international transport in the response to comment 6.4.1. and in Question 23 in the revised draft Q&A document. The EPA refers the commenter to these responses.

7.5.25. Comment: “ Relation to agriculture . Attendees at EPA Region 9’s June 9, 2011, workshop on the draft guidance were informed that the EPA had decided not to consider agriculture in developing the guidance. Yet, the draft guidance brings both a state and the EPA face-to-face with agricultural practices and controls... One set of recommended Best Management Practices to deal with “farming with the wind” is various crop rotations. These involve recurring cycles of greater and less vulnerability to wind erosion dust generation depending upon such factors su ch as the specific crops or fallow periods in the rotation, agricultural activity such as tilling and harvest, and the state of crop development and the protection that affords against wind erosion.” Specific reference to guidance text: High Winds Guidance document
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of Ecology

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: At the EPA Region 9 workshop on June 9, 2011, the EPA staff stated that we do not intend to address agriculture as a sepa rate and distinct category with unique high winds exceptional events issues. Rather, we w ill treat agriculture as we treat all other
sources of dust.

7.5.26. Comment: The language in the first (partial) paragr aph on page 11 needs to be clarified
and made consistent with the Fire Polic y/Forest Service language. The commenter recommends that the phrase “areas burned by anthropogenic fires” be removed from the text as emissions from surfaces disturbed by large-scale fires, whether or not the initiating event was natural or human caused, are be yond “reasonable” control and should not be considered as anthropogenic. In the last sentence in paragraph 1 on page 11, the EPA identifies “naturally-ignited fires” as a natural source. Change this to “wildfires” to be consistent with Fire Policy/Forest Service language. Specific reference to guidance text: High Winds Guidance document, page 11
Submitter: Pete Lahm (Smoke Manager), USDA Forest Service

Date: 7/14/2011 via phone conversation with Beth Palma Response: The EPA has modified the language in the revised draft High Winds
Guidance document that refers to “ar eas burned by anthropogenic fires.”

7.6. Historical fluctuations

7.6.1. Comment: How can an agency address the wind parameters and historical exceptional events if their temporal wind data is collect ed differently than what is in the draft guidance? Will the EPA accept the agency’s curre nt wind data in different format (i.e. different data collection and handling than the EPA’s defined in the draft guidance: maximum sustained 1-5 minute average)? Also, wh at if an agency’s current equipment is incapable of collecting and/or storing wind data in those intervals? Does that preclude the agency from any future exceptional events submittals? Specific reference to guidance text: High Winds Guidance document
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: The “in excess of historical fluctuations” requirement in the EER only applies to the exceedace of the standard, not to the level of wind speed associated with an event. Furthermore, based on comments, the EPA has revised the draft guidance to rely primarily on hourly average wind data since air monitoring stations now typically collect
data in this form or in a form that allows this to be calculated. The EPA also refers theDraft for Public Notice and Comment
Revision Date: June 2012 73

commenter to responses to comments 7.3.3. and 7.3.10. for additional information regarding wind speed data availability and averaging times.

7.6.2. Comment: “Clark County does not believe that an an alysis of historical fluctuations adds value to exceptional event documentation and in fact may be misleading to reviewers and the public...Clark County recommends that EPA revise the draft guidance to reduce the time period and number of data points for whic h the analysis must cover. The standard period used to calculate the design value for an attainment SIP is three years, and Clark County believes that this is also the appropr iate time period for an historical analysis.” Specific reference to guidance text: High Winds Guidance document
Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA agrees that generally three years is an appropriate period for the historical fluctuations analysis. The revised guidance will rely on three years but allow a longer timeframe if an agency chooses to provide it; for example, a longer timeframe may be useful to support the “but-for” criterion.

7.7. High Wind Action Plan

7.7.1. Comment: Please clarify how a High Wind Action Plan becomes enforceable without formal rulemaking. In addition, since it woul d take time to develop and implement a High Wind Action Plan, other high wind dust exceptional events that might occur subsequent to the first event but prior to implementation of the Plan should also be excused from the requirement to have reasonable controls in place. This is even more critical in light of the potential for the EPA to adopt more stringent PM 10 ambient standards. Attainment areas with windy conditions but no histor ical exceedances of the current PM 10 standard could now suddenly experience an uptick in high wind dust events that drive PM 10 concentrations over a reduced standard w ithout any lead time to get controls in place. EPA needs to make exceptions for the control demonstration under this circumstance, as the rulemaking process to get controls in place may take considerable
time. Specific reference to guidance text: High Winds Guidance document, Section 3.1.6
Submitter: Brian Shafritz, Santa Barbara County Air Pollution Control District, ShafritzB@sbcapcd.org

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: Air agency or source implementation of measures in a High Wind Action Plan (HWAP) that are not in an approved SIP is not federally enforceable but the measures within it may still be enforceable (e.g., agencies may incorporate measures in the HWAP into state or local law). While the HWAP is not in itself federally enforceable, the EPA’s concurrences on exceptional events rely upon it so that if it is not implemented effectively then exceptional events may not be concurrable. An agency will have six months to submit an adequate HWAP and th e EPA’s concurrence on the specific event(s) in question and those going forward are c ontingent upon the EPA’s approval of the HWAP (i.e., the newly-identified sources woul d not be considered to meet the nRCP criterion if the HWAP is violated). If the ag ency meets this timeframe, then the EPA will consider high wind exceptional events that occur within that timeframe to be not reasonable controllable or preventable, assuming any “on-the-books” controls were
enforced.

7.7.2. Comment: The idea of a High Wind Action Plan, that could identify a mutually agreeable set of reasonable controls for an area with recurring events, has merit. This would also help streamline the documentation for recurring events, since it could be used as a reference for background information. Unfo rtunately, this may not apply to initial or infrequent events or when new monitoring or unforeseen conditions change the types ofDraft for Public Notice and Comment
Revision Date: June 2012 74

sources that could impact a monitor. AQMD staff will continue to work with the U.S. EPA to explore this option. Specific reference to guidance text: High Winds Guidance document
Submitter: Barry Wallerstein, South Coast Air Quality Management District

Date: 6/28/2011 via e-mail to Matt Lakin and EEGuidanceComments@epa.gov Response: The EPA agrees that the HWAP will be most useful to areas that have frequent high wind dust events. Areas with in frequent/non-recurring events are unlikely to violate the PM standards due to high wind events and, therefore, the EPA would not likely review demonstration packages associ ated with these events because they would not be associated with near-term regulator y decisions. The EPA encourages agencies to submit a letter of intent, the review of which may prevent agencies from preparing documents (e.g., HWAP) for events with no re gulatory bearing that the EPA may give low priority.

7.7.3. Comment: If potential sources are not identified to EPA's satisfaction through the submittal of an "optional" HWAP, EPA may potentially find that reasonable controls were not in place during subsequent events, ev en in areas such as the San Joaquin Valley that implement comprehensive, approved Best Available Control Measures (BACM). For recurring events, the EPA will need to re-a pprove the High Wind Action Plan regardless
of whether it is revised or remains as-is. For recurring natural events above the wind entrainment threshold, this additional do cumentation and review by the EPA does not seem appropriate or necessary. Additionally, th e District has a Natural Event Action Plan (NEAP) that has been approved by the EPA. Can the District use the NEAP in place of the High Wind Action Plan (HWAP)? If not, how much more information is necessary to make the NEAP approvable? The draft guid ance does not address what new information
is needed when a NEAP is already in place. Specific reference to guidance text: High Winds Guidance document
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA is de-emphasizing consider ation of recurrence and altering the HWAP concept to be more similar to a NEAP in some respects (see section 3.7.2.4 of the revised draft High Winds Guidance document). A NEAP provides a good framework for the HWAP and an existing NEAP may be acceptable as a HWAP in some cases. The EPA has also revised the draft guidance docum ents to include a prospective controls analysis that would prevent the issue rai sed by the commenter. See response to comment

7.4.1.

7.7.4. Comment: “We are very uncomfortable with EPA’s expectation that States implement successive High Wind Action Plans with escala ting emission control programs, outside of the statutory framework of the Clean Air Act, as a precondition of concurrence of recurring exceptional events. We are very uncom fortable with BACM, or greater levels of control, as the appropriate starting point for consideration of reasonable control measures in attainment, maintenance, and moderate areas.” Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The development of a HWAP is voluntary (see comment 7.4.4). Agencies also have two options: pursuing the regul atory process and accepting a non-concurrence or preparing and submitting demonstrations s howing that reasonable controls are in place for each flagged exceedance. The regulatory pr ocess would follow the normal path of the SIP process to implement reasonable controls.Draft for Public Notice and Comment
Revision Date: June 2012 75

In response to the commenter’s next point regarding the EPA’s reference to “starting point,” the EPA uses the term “starting point” to mean a point of reference at which to begin the evaluation. “Starting point” is not intended to indicate the lowest level for consideration. We have clarified this poi nt in the revised draft guidance documents.

7.7.5. Comment: “In § 3.1.6, EPA suggests that states de aling with recurring high-wind events develop a high-wind action plan that woul d “...identify mutually agreed upon reasonable controls that a state could implement for subsequent high wind events.” Although not expressly stated, the implication of this section is that states having recurring high-wind events that do not submit and obtain ap proval of high-wind action plans would not
receive EPA concurrence for exclusion of futu re high-wind events. As set forth on page 19 of the draft guidance, EPA will evaluate the long-term adequacy of the high-wind action plan and the ‘reasonableness’ of the pl an’s control measures as follows: ‘Once the state has begun implementation of the measures approved by EPA and EPA has formally recognized implementation of the High Wind Action Plan, EPA would consider the controls to be reasonable as long as events do not recur . (emphasis added).’ This criterion is apparently based on the flawed assumption that if states and regulated entities will invest enough financial resources and e ffort on controls, then uncontrollable highwind driven events can be controlled. EPA has not provided any documentation to support the concept of high-wind driven events controllability and it is the experience of Clark County that such events are not controllable with any measures that could be implemented.” Specific reference to guidance text: High Winds Guidance document
Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA is de-emphasizing consid eration of recurrence and adding a prospective controls analysis, which should address these concerns. See also responses to
comment 7.4.1. and 7.5.9.

7.7.6. Comment: “If EPA decides to allow for voluntar y High Wind Action Plans, the Agency should not require continual revision and upda ting of the plans (e.g., upon recurrence of EEs).” MAG states that linking the High Wi nd Action Plan to recurrence provides no incentive for a state to develop a plan because there is little benefit to develop a publicly reviewed, “SIP-like” plan for one event pe r year. MAG suggests that an incentive for completing a plan should be that the state w ould have “some assurance ahead of time that EPA finds their existing controls and im plementation measures adequate.” Specific reference to guidance text: varies (additional documentation to support recommendation is provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf )
Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA is de-emphasizing consideration of recurrence and adding a prospective controls analysis, which shou ld address these concerns. See response to
comment 7.4.1. and 7.5.9.

7.7.7. Comment: Wyoming Air Quality Division asks that EPA develop a process to include Natural Events Action Plans (NEAP) into High Wind Action Plans as many places in the West continue to rely on these agreements between EPA, States, industry and the public and the plans include many of the elemen ts identified to be part of HWAPs. Specific reference to guidance text: High Winds Guidance document
Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.govDraft for Public Notice and Comment
Revision Date: June 2012 76

Response: An existing NEAP can be the basis of a HWAP. The EPA has revised the draft High Winds Guidance document to clarif y the relationship between a NEAP and the HWAP (see section 3.7.2.4 of the revised draft High Winds Guidance document).

7.7.8. Comment: Washington Department of Ecolog y asks that EPA address using or incorporating previously developed and curren tly used Natural Events Action Plans in the High Wind Action Plan as NEAPs proved the “core” components of a HWAP as envisioned by the draft guidance. Specific reference to guidance text: High Winds Guidance document
Submitter: Stuart Clark (Air Quality Program Manager), Washington Department of Ecology

Date: 7/5/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: An existing NEAP can be the basis of a HWAP. The EPA has revised the draft High Winds Guidance document to clarif y the relationship between a NEAP and the HWAP (see section 3.7.2.4 of the revised draft High Winds Guidance document).

7.8. Checklist for demonstration submission

7.8.1. Comment: The draft guidance appears to require the submittal of a fully completed checklist and associated documentation requirements found in Appendix B of the draft guidance. The requirement that all of the se items be included in all exceptional event submittals to the EPA goes against the spirit of the EER that allows for a weight-ofevidence approach to demonstrating the occu rrence of exceptional events. The District recommends that flexibility be allowed to provide the relevant documentation necessary to demonstrate exceptional events and not be prescriptive in completing the checklist. Specific reference to guidance text: High Winds Guidance document checklist
Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA has revised the checklist. The EPA has also clarified which elements are relevant, factoring in the poten tial for a prospective controls analysis and HWAP. The EPA believes that the tools provided in the draft guidance materials support the weight-of-evidence approach intended by the Exceptional Events Rule (see also response to comment 6.5.10. for a discussion of “weight-of-evidence”).

7.8.2. Comment: Clark County states that the caveat on the checklist stating, “...This checklist represents the minimum information that must be included in a package and serves to identify packages that are incomplete rather than show that a package is complete...” suggests that if “all of the items in the ch ecklist are not included in the demonstration package, EPA will not review the package, leading to an automatic non-concurrence. Clark County requests refinement of the checklist and revision of the prefacing statement to clarify that where elements on the checklis t are not required due to very high winds or other factors, EPA will review the demonstration documentation.” Specific reference to guidance text: High Winds Guidance document, page 60
Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA has modified the Completeness Checklist for High Wind Dust Exceptional Events. See also the response to comment 7.8.1.

7.9. Recommended framework for high wind dust exceptional event demonstration package
7.9.1. Comment: “We are very supportive of the process timeframes and action steps outlined in the proposed guidance. They represent steps forward to resolve a number of longstanding issues of uncertainty about timing of communications and reducing unnecessary delays in processing exceptional events request s. We are also supportive of the optionalDraft for Public Notice and Comment
Revision Date: June 2012 77

process steps to prioritize actions in recognitio n of the very limited resources we all have. The guidance should encourage continuing communication and negotiation of issues between states and EPA to make the process work.... We also are supportive of the overall recommended methods of preparing each of the technical elements and recommended order of analyses to facilitate using the technical work developed in support of one showing to suppor t more than one element.” Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

7.10. General

7.10.1. Comment: The figures on page 50 (measurements from monitoring stations) are
unreadable. Specific reference to guidance text: High Winds Guidance document, page 50
Submitter: Scott DiBiase, Pinal County Air Quality, scott.dibiase@pinalcountyaz.gov

Date: 6/23/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA appreciates the feedback and incorporated figures with improved
resolution.

7.10.2. Comment: The EPA guidance documents provide for the use of chemical speciation as supporting evidence to assist in establishing a Clear Causal Relationship. Because of the size of the air basin, the District, in a stra tegic effort to streamline staff time spent changing filters, is shifting PM collection from filter-based to real time with TEOMS monitors. However, this action will cause the District to potentially not have filters for a mandatory chemical speciation analysis. The draft guidance should be not requiring the use of chemical speciation to establish a Clear Causal Relationship, but leave as optional criteria in a weight-of-evidence approach. Specific reference to guidance text: none Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control District

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: In the draft High Winds Guidance document, the EPA identified several types of analyses that agen cies can use to show a “clear causal relationship.” These analyses, including the use of chemical speciation, are “possible” analyses versus “required” analyses. Agencies may need some, all, or other analyses to demonstrate the clear causal relationship criterion. The EPA will evaluate the clear causal relationship criterion on a weight-of-evidence approach b ased on available information for each case. The EPA encourages areas with recurring high wind dust events to consider what information will be useful in a high wind dust exceptional events demonstration package when designing their monitoring networks. The EPA also recognizes that, due to limited resources and the unpredictability of high wind dust events, agencies may not have all the information listed in the “clear causal relationship” table for every event.

7.10.3. Comment: The District has experienced and is expected to continue experiencing high
wind PM 2.5 exceptional events. The guidance doc ument does not address documentation requirements for PM 2.5 exceptional events. Towards that end, the District recommends
that PM 10 and PM 2.5 documentation be handled within the same submittal to the extent possible, and that the EPA develop a test method for analyzing Beta Attenuation Monitor tape to assist in preparing the support documentation. Specific reference to guidance text: none Submitter: Samir Sheikh (Director of Strategies and Incentives), San Joaquin Valley Air
Pollution Control DistrictDraft for Public Notice and Comment
Revision Date: June 2012 78

Date: 6/29/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The revised draft High Winds Guidance document states in the opening paragraph that the document applies to both PM 10 and PM 2.5 high wind dust events. Many of the examples contained in the document, however, are for PM 10 because PM 10 exceptional events (and associated demonstra tion submittals) are more prevalent than

PM 2.5 high wind dust events.

At this point, the EPA does not believe that there is a need to develop a test method for chemically analyzing the PM spot on the Beta Attenuation Monitor (BAM) tape. Agencies can obtain chemical speciation data by using the filter media from the existing filter based sampling technologies. While this a pproach may be limited in its ability to provide short-term event characterization, agencies can still use it to support an event demonstration package. Additionally, em erging commercially available technologies have the potential to support higher time resolution of chemical speciation. The PM Integrated Science Assessment at http://w ww.epa.gov/ncea/isa/pm.htm details such technologies as does the following presentation made at the 2011 National Air Quality
Conference: Evaluation of Simultaneous PM 10 , PM 2.5 , and PM 10-2.5 Measurements Conducted in Bakersfield, CA with the Teledyne-API Model 602 Beta PLUS Particle Measurement System available on the web at http://www.airnow.gov/index. cfm?action=naq_conf_2011.aq3

.

7.10.4. Comment: “Most of the examples throughout the guidance assume more extensive meteorological monitoring than exists in ma ny areas of the west. Source wind data do not typically exist when events cover large dist ances, for example, when the source is the southwest desert. Meteorological data are sometimes available from local airports. We suggest allowing the use of available regiona l wind data as surrogate for source data as
needed.” Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA recognizes the sometimes limited spatial coverage of wind data needed for high wind dust EE demonstrati ons and supports using all available meteorological networks and data sources (s ee responses to comments 7.3.3. and 7.3.10. for additional information). The EPA welcomes additional information on meteorological
networks.

7.10.5. Comment: “We generally support the proposed [mitigation] guidance as written, which interprets actions to protect public health through individual actions as mitigation of exposure to exceedances from any source of ai r pollution, as distinguished from measures that control or prevent emissions. Emission control measures are covered in section 3.1, Not Reasonably Controllable or Preventable (including High Wind Action Plans), about which we have strong concerns.” Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA appreciates the feedback on mitigation and seeks additional feedback regarding analyses to support the “ not reasonably controllable or preventable” criterion. See response to comment 7.4.1.

7.10.6. Comment: “In this [public comment] section of the proposed guidance, EPA asserts, “the state should submit the public comments al ong with the state’s responses, if any, to EPA within 10 days of the close of the comment period.” In many cases, response to public comments within 10 days will not be possible.”Draft for Public Notice and Comment
Revision Date: June 2012 79

Specific reference to guidance text: High Winds Guidance document
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA has revised the draft High Winds Guidance document to allow air agencies to submit public comments along with the air agency’s response within 30 days of the close of the comment period.

7.10.7. Comment: Clark County DAQEM agrees with guiding principles, but suggests that a 4 th
principle, “It is desirable to implement a reasonable and cost-effective process for the development and EPA review of state excepti onal events” be added to “allow both states and EPA to efficiently use scarce resources during this period of economic austerity.” Specific reference to guidance text: High Winds Guidance document, Critical Elements on page 2
Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: While the EPA agrees with the co mmenter, the EPA has not added the suggested language as a 4 th guiding principle. One of the EPA’s goals in developing exceptional event implementation guidance is to establish clear expectations to enable affected agencies to better manage resources as they prepare the documentation required under the EER. As part of an upcoming public comment process, the EPA will solicit feedback on a series of questions, some of which will seek specific, broadly applicable, streamlining mechanisms.

7.10.8. Comment: “ EPA should recognize that EEs can and do occur at one monitor while other

mon i tors in the same area may not vio l ate an air quality standard. ” Specific reference to guidance text: varies (additional documentation to support recommendation is provided in comment attachment at Submitted Comments\Need OCR\MAG_063011-ocr.pdf ), comment refers to page 22 of HIGH WINDS GUIDANCE DOCUMENT doc that says “For example, a hypothesis that an exceedance was caused by a large-scale wind event is inconsistent with a situation where an isolated monitor exceeds while nearby monitors do not.”
Submitter: Thomas Schoaf (Mayor, City of Litchf ield Park and MAG Chair), Maricopa
Association of Governments

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA agrees that high wind dust events can affect one monitor and not others and has revised the draft High Winds Guidance document to more clearly reflect this point. Agencies believing this scenario occurred in their areas are encouraged to explain the spatial extent of the exceed ance in the conceptual model of their demonstration. For example, if the agency describ es the event as a regional dust storm, then the EPA would expect monitors within the same regional scale to be similarly affected by the dust storm. Note that if an exceedance is due to low wind speeds, or sources that should have been reasonably c ontrolled (e.g., lack of implementation or enforcement of controls) then this event would not meet the “not reasonably controllable or preventable” requirement.

7.10.9. Comment: “If the six elements must be met for qualifying under the Exceptional Events (EE), and if wind direction, wind speed and recurrence are separate from HF, but are clearly “vital” as to how there was an excepti onal exceedance, why are they not a part of
the Critical Elements? These same Critical Elements are called technical elements on page 11. It is confusing with two different terms. ” Specific reference to guidance text: High Winds Guidance document, Critical Elements on page 2Draft for Public Notice and Comment
Revision Date: June 2012 80

Submitter: Ann Hobbs (Air Quality Specialist), Placer County Air Pollution Control
District

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The Exceptional Events Rule at 40 CF R §50.14 identifies both technical and process requirements for exceptional event (including high wind dust event) demonstration packages. The EPA tried to distinguish these in the draft guidance documents. In addition to the specific require ments of the regulatory language, there are additional technical analyses that agencies need to include in any high wind dust exceptional event demonstration. The EPA does not consider these analyses “critical elements” because they are not specifically id entified by regulation nor are they standalone criteria. Rather, these analyses info rm and support those criteria specifically required by the rule. There are linkages among most of the technical elements, making it more challenging to treat each criterion as an independent element. The EPA has clarified this in the revised draft guidance documents.

7.10.10. Comment: Wyoming Air Quality Division asks that the following terms be defined: Anthropogeni c fi r es (p. 11), Severe exceptional even t s (p.12), Mild isolated exceedances (p.12), Frequent [except io nal eve nt s] (p.12), Rare [excee danc es] (p

. 12), S tabl e surfaces (p.3) Specific reference to guidance text: High Winds Guidance document, varies
Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA has clarified or defined the following in footnotes in the revised draft guidance documents:

 Anthropogenic fires –The EPA has revised the language in the revised draft High
Winds Guidance document.

 Severe exceptional events - e.g., 24-hour average PM 10 >250μg/m3

 Mild isolated exceedances - e.g., exceedance at one site close to the standard

 Change rare to non-recurring - <1 high wind dust event per year

 Frequent - enough exceedances from high wind dust events to cause a violation of the NAAQS.

 Stable surfaces - defined in the “Consideration of Wind Speed” section of the draft High Winds Guidance document

8. Treatment of Technical Criteria for Exclusion of Data Affected by Events

8.1. Not reasonably controllable or preventable

8.1.1. Comment: “State Implementation Plans define the measures states must take to attain and maintain compliance with NAAQS. Section 110 of the Clean Air Act requires each
State’s SIP to include enforceable emission limits and other control measures to prevent NAAQS violations and holds EPA responsib le for ensuring that these measures are sufficient. If not, EPA’s responsibility is to require the State to revise its SIP to address any identified deficiencies through a SIP ca ll.” WESTAR believes that “EPA proposes to implement this provision in such a way that for recurring events, States must implement escalating emission control measures, beyond those required under Section 110 and Part D (for nonattainment areas) of the Act, to be eligible for exclusion of data under the Exceptional Events Rule.” Specific reference to guidance text: Additional information on comments at Submitted Comments\WESTAReerfinal063011.pdf
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA’s draft guidance documents and the exceptional events website (http://www.epa.gov/ttn/analysis/exevents.htm) present examples to illustrate specificDraft for Public Notice and Comment
Revision Date: June 2012 81

points. They do not establish any new requirements. The revised draft High Winds Guidance document does not require that ai r agencies implement escalating control measures beyond those required in their SIP. Rather, the document states that, in the interest of protecting public health, it ma y be appropriate to implement escalating
controls for events that recur. The EPA furt her identifies in the revised draft High Winds Guidance document that RACM/BACM measures may be a reference point, but not the

sole means , by which the EPA assesses the reasonableness of controls. In its revisions to the draft guidance documents, the EPA has introduced the concept of a prospective controls analysis that could incorporat e SIP-approved controls. See response to
comments 7.4.1. and 7.5.9.

8.1.2. Comment: “WESTAR is also concerned about EPA’s expectation that States show reasonable controls were implemented “at the time of the event.” While this is a reasonable requirement for local sources and sources addressed in the State Implementation Plan, it is ambiguous for many sources in the West. For example: For dust raised from distant sources by high winds, documentation of specific control measures underway “at the time of the event” is unlikely to be available. For many states, high wind events are regional in scope and can extend for hundreds of miles rather than being localized events and thus difficult to characterize because of their scope. Crop rotations, which are Best Management Practic es for preventing agricultural wind erosion, are multi-year practices that include recurring cycles of greater and less vulnerability to wind erosion depending upon such factors such as the specific crops or fallow periods, tilling, crop development, and harvest. In su mmary, if EPA intends to require emission control measures beyond those required under Section 110 and Part D requirements, those requirements should be included in an amendment to the regulation with appropriate citations to the authorizing provi sions of the Act. Until such a rulemaking has been completed, we reiterate that the test of reasonable controls should be limited to an evaluation of whether or not the State implemented the applicable provisions of their State Implementation Plan and any applicable High Wind Action Plan.” Specific reference to guidance text: Additional information on comments at Submitted Comments\WESTAReerfinal063011.pdf
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 7.4.1. and 7.5.9.

8.2. Natural event

8.2.1. Comment: ADEQ agrees that a natural event does not need to be infrequent to qualify as

an EE. Specific reference to guidance text: none Submitter: Eric Massey (Director), Arizona Air Quality Division

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

8.3. Clear causal relationship

8.3.1. Comment: “We think the section on process provides a good framework for review and timelines including early consultations a nd notifications of additional needed
information. Our concerns remain as to the ability of agencies to produce ’all’ information requested. For example, the Clear Causal guidance in Section 3.3, Table 4, nos. 2. and 4 suggests an analysis to demons trate temporal relationships, ’Wind direction data showing that emissions from sources iden tified as part of nRCP demonstration were upwind of the monitor(s) in question, sate llite imagery,’ and, ’24-hour time series showing PM concentration at the monitor in question in combination with sustained and maximum wind speed data at area where dust was entrained.’ Examples of analyses areDraft for Public Notice and Comment
Revision Date: June 2012 82

given, but these are in areas that are ex tensively monitored. There are numerous areas throughout the arid west where source-recepto r relationships are re gional in scope, and
where dust sources are remote from ambient monito rs that may detect the event. In most such areas meteorological information at the source would not exist, because there are no wind instruments deployed there. Satellite im agery can be a matter of luck, with cloud cover or other visibility obscuring conditions. We would expect EPA to take such factors
into consideration as well as resource commitmen ts when determining the information to be requested from the State and level of an alyses needed to demonstrate Clear Causal relationship.” Specific reference to guidance text: High Winds Guidance document, section 3.3, Table 4, nos. 2 and 4
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: In the draft High Winds Guidance documen t, the EPA identified several types of analyses that air agencies can use to s how a “clear causal relationship.” These analyses are “possible” analyses versus “required” analyses. Agencies may need some, all, or other analyses to demonstrate the clear causal relationship criterion. The EPA will evaluate the clear causal relationship criter ion on a weight-of-evidence approach based
on available information for each case. The EPA also recognizes that, due to limited resources and the unpredictability of high wind dust events, agencies may not have all the information listed in the “clear causal relationship” table for every event.

8.3.2. Comment: “ The Wyoming Air Quality Division wo uld l ike EPA to take into
consideration the r eso urces and r e quir eme nt s of s tates when eva luating e l e m e nt s in this

sec tion. Many o f th e typ es o f information to support th ese analyses are not avai l ab l e in
states with s maller populations and l ess required monitoring. For in s tance

, the Wyoming Air Quality Division 's n e twork of visibi lity monit o ring is sparse and i s not lo ca ted near
the indu s trial areas where exceedances u s ually occur. Additionally, the Wyoming Air Quality Division i s only r eq uir e d to have speciated particu l ate monitorin g at one l ocat ion
in the State.” Specific reference to guidance text: none Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: See response to comment 8.3.1.

8.4. Historical fluctuations

8.4.1. Comment: “We support the approach in the proposed guidance to demonstrate historical
fluctuation.” Specific reference to guidance text: none Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The EPA acknowledges commenter’s support.

8.4.2. Comment: Presenting evidence that an event is “in excess of normal historical fluctuations including background” becom es increasingly difficult as NAAQS levels are set close to or below the level of the poli cy relevant background (ozone is particular issue). Specific reference to guidance text: none Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: As described in the EPA’s revised draft Q&A document, the EPA will use a weight-of-evidence approach to assess each demonstration on a case-by-case basis. The air agency’s obligation in satisfying this elem ent is to provide analyses and statistics. TheDraft for Public Notice and Comment
Revision Date: June 2012 83

submittal of data showing how the event concentration compared with historical concentrations will help the EPA determine whether the “clear causal relationship,” “but for,” and “affects air quality” criteria have been satisfied.

8.5. But for

8.5.1. Comment: “EPA’s draft guidance retains the requirement for a State to show that there would not have been a NAAQS exceedance but for the event without a clear explanation of how such a showing can be made. In fact , in the preamble to the Exceptional Events Rule, EPA commits to publishing, in a notice of proposed rulemaking, the means by which a state could make this showing on ce the techniques for adjusting data are sufficiently well documented. Until this rulemaking is completed, WESTAR sees no alternative but for EPA to revise the Excepti onal Events Rule to remove the ‘but for’

test.” Specific reference to guidance text: Q&A document #13
Submitter: David Collier (President), WESTAR

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: The preamble to the Exceptional Events Rule states at 72 FR 13572, “When we determine that techniques for adjustmentof air quality data are sufficiently welldemonstrated for use in exceptional events determinations, we will publish a notice of proposed rulemaking to seek comment on the a ppropriateness and scope of such use and its impact on the requirements set forth in this rule for determining an exceptional event.” This language refers to the partial adjustment of a 24-hour value rather than the exclusion of the entire 24-hour value, which is how the EPA handles concurred upon exceptional event data. Air agencies can satisfy the “but for” criterion with reasonably supportable adjustments, and in some cases, a qualitative analysis.

As indicated in the draft guidance documen ts, the EPA has retained the “but for” provision and continues to believe that this regulatory criterion in the Exceptional Events Rule implements the Clean Air Act language that specifies that “a clear causal relationship must exist between the meas ured exceedances of a national ambient air quality standard and the exceptional event to demonstrate that the exceptional event caused a specific air pollution concentration at a particular air quality monitoring
location...” and that States can petition the EPA to “exclude air quality monitoring data that is directly due to exceptional events from use in determinations...with respect to
exceedances or violations .” (emphasis added)

8.5.2. Comment: Clark County DAQEM believes that a quantitative NEBF analysis exceeds the provisions of the EER and “conflicts with the EER preamble, which states in part: The EPA will consider such [quantitative] anal yses as part of the weight-of-evidence to judge ‘but-for,’ but will not make quantitativ e adjustments to reported measured values
because the EPA does not believe sufficient quantitative methods are available at this

time . (emphasis added) (72 Fed. Reg. 1 3560, 13572 (Mar. 22, 2007))...Clark County encourages EPA to remove this de facto requirement from the draft guidance.” Specific reference to guidance text: none Submitter: Tina Gingras (Assistant Director), Clark County DAQEM

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 8.5.1.

8.5.3. Comment: “The requirement for [the but for] test is included in EPA’s EER along with a commitment by EPA, in the rule’s preamble, to publish a proposed rule that would establish the parameters for making a demonstr ation once the agency “determine[s] that techniques for adjustment of air quality data are sufficiently well demonstrated for use in exceptional events determinations.” That prop osal has not yet materialized, nor has theDraft for Public Notice and Comment
Revision Date: June 2012 84

agency provided a clear explanation of how to make such a demonstration. Therefore,
NACAA believes that until such time as EPA is able to identify and promulgate technically feasible techniques for “backing out” that portion of the monitored data determined to have resulted from the excep tional event, EPA should revise the EER to
remove the ‘but for’ test.” Specific reference to guidance text: none Submitter: Tad Aburn (Co-Chair), NACAA Criteria Pollutants Committee

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 8.5.1.

8.5.4. Comment: “ There are no exa mpl es of a quantitative analysis o f NEBF included in thi s document. Without do c umented examp l es, th e requirement of a quantit a tiv e NEBF
should b e r e mov e d from the Guidance. ” Specific reference to guidance text: none Submitter: Steven Dietrich (Administrator), Wyoming Air Quality Division

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA refers the commenter to the ozone/wildfire demonstration package on the exceptional events website at http://www.epa.gov/ttn/analysis/exevents.htm . This package uses regression and related additional statistical evaluation, surrogate day and rule of thumb analysis, and evaluation of the frequency of high ozone concentrations as part of a quantitative “but for” submission. See also the response to comment 8.5.1.

8.5.5. Comment: The NCDAQ requests that the U.S. EPA provide more guidance on what the EPA is willing to accept for weight-of-evidence for values that are just barely over the standard. For example, if the daily standa rd is 35 and the value impacted by the exceptional event is 37, what types of eviden ce will the U.S. EPA accept as proof that the value would have been 34 or 35 "but for" the exceptional event?

NCDAQ would also like the EPA to provide additional guidance on what the EPA is willing to accept for weight-of-evidence for va lues that are between the annual and daily standard, for example, if the annual standard is 15, the daily standard is 35 and the value measured is 27. What types of evidence should the NCDAQ provide to demonstrate to the USEPA that but for the exceptional event, the value would have been 14 or 15?

The EPA only discusses the "But For" test for ozone. The NCDAQ recommends that the
EPA also include similar discussions for "But For" tests for sulfur dioxide and perhaps nitrogen dioxide too. If data collected by a su lfur dioxide monitor are influenced by an exceptional event such as a volcano or an industrial mishap, how would a state go about demonstrating that the exceptional even t caused the exceedance? What weight-ofevidence would be required? Similarly, if data collected by a near road nitrogen dioxide monitor were influenced by an exceptional event, what weight-of-evidence would the EPA be looking forward to demonstrate the "But For" test? Specific reference to guidance text: Q&A document #13
Submitter: Sheila Holman (Director), NC Division of Air Quality

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: See response to comment 8.5.4.

8.5.6. Comment: “EPA should provide examples of analyses that will be accepted to demonstrate a quantitative ‘but for’ test and what analysis is acceptable to distinguish
between an event contribution and a non-event contribution.” Specific reference to guidance text: none Submitter: Larry Allen (Air Pollution Control Officer), San Luis Obispo Air Pollution
Control DistrictDraft for Public Notice and Comment
Revision Date: June 2012 85

Date: 6/30/2011 via e-mail to Gina McCarthy and EEGuidanceComments@epa.gov Response: See response to comment 8.5.4.

8.5.7. Comment: It is very difficult to demonstrate “ but for,” particularly for ozone-related events. Most air pollutant exceedance events consist of contributions from multiple sources. The EPA’s guidance seems to apply differently for PM vs. ozone events. The EER preamble and the high winds guidance acknowledge that a PM exceedance can be exceptional even with contributions from natural and anthropogenic sources, but the answer to Q&A #6 implies that if an ozone /wildfire event has a contribution from an anthropogenic source as well as the fire, the event cannot be excluded under the EER. Further, demonstrating “that a fire plume h as passed over a monitor is extremely difficult. All the methods that EPA suggested for demons trating that a fire plume passed a monitor are insufficient as discussed below...” BP provides examples of satellite, modeling, and monitoring limitations and then identifies that if complete, detailed analyses are performed, they would likely exceed the desired response time and monetary resource availability. Specific reference to guidance text: Q&A document #6 (see document for additional
detail: Submitted Comments\BP_063011pdf.pdf )
Submitter: Karen St. John (Sr. Director, Regulatory Affairs), BP America, Inc.

Date: 6/30/2011 via e-mail to EEGuidanceComments@epa.gov Response: The EPA disagrees with the commenter’s interpretation of Q&A 6 that an ozone/wildfire-related exceptional event w ith contributions from the fire and anthropogenic sources cannot be excluded unde r the EER. In the response to Q&A 6 in the revised draft Q&A document, the EPA st ates that because the effects of a fire on ozone are complex, the ensuing “but for” demonstration may be more complicated than a
“but for” demonstration for another pollutant, like particulate matter. The EPA can, and has, concurred on ozone/wildfire related excep tional events and refers the commenter to the website: http://www.epa.gov/ttn /analysis/exevents.htm

The EPA recognizes that some demonstration an alyses are resource intensive, but given the importance of accurately evaluating excep tional events, the EPA expects submitters to prepare and submit the appropriate level of supporting documentation, which will vary on a case-by-case basis using the weight-of-e vidence approach. The EPA further notes that the CAA does not give the EPA the authorit y to exclude data if the air agency has not
met and demonstrated each criterion.