[Federal Register Volume 77, Number 130 (Friday, July 6, 2012)]
[Proposed Rules]
[Pages 39959-39962]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-16308]



40 CFR Parts 50 and 51

[EPA-HQ-OAR-2011-0887; FRL-9696-1]
RIN 2060-AN40

Draft Guidance To Implement Requirements for the Treatment of Air 
Quality Monitoring Data Influenced by Exceptional Events

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability and public comment period.


SUMMARY: Notice is hereby given that the EPA has posted its draft non-
binding guidance titled, Draft Guidance to Implement Requirements for 
the Treatment of Air Quality Monitoring Data Influenced by Exceptional 
Events and associated attachments, on the agency's Internet Web site. 
The EPA invites public comments on this guidance document and plans to 
issue an updated version of the guidance after reviewing timely 
submitted comments. The EPA intends to hold a conference call to 
provide interested stakeholders with an overview of the Exceptional 
Events draft guidance.

DATES: Comments must be received on or before September 4, 2012. Please 
refer to SUPPLEMENTARY INFORMATION for additional information on the 
comment period.

ADDRESSES: Access to the draft guidance: Please see the EPA's Web site 
at http://www.epa.gov/ttn/analysis/exevents.htm for additional details 
on the draft non-binding guidance titled, Draft Guidance to Implement 
Requirements for the Treatment of Air Quality Monitoring Data 
Influenced by Exceptional Events and associated attachments and the 
conference call for interested stakeholders.
    Comments: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2011-0887, by one of the following methods:
     http://www.regulations.gov. Follow the online instructions 
for submitting comments. Attention Docket ID No. EPA-HQ-OAR-2011-0887.
     Email: a-and-r-docket@epa.gov. Attention Docket ID No. 
     Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-
     Mail: Air Docket, Attention Docket ID No. EPA-HQ-OAR-2011-
0887, U.S. Environmental Protection Agency, Mail Code: 6102T, 1200 
Pennsylvania Ave. NW., Washington, DC 20460. Please include a total of 
two copies.
     Hand Delivery: EPA Docket Center, 1301 Constitution Avenue 
NW., Room 3334, Washington, DC, Attention Docket ID No. EPA-HQ-OAR-
2011-0887. Such deliveries are only accepted during the Docket Center's 
normal hours of operation, and special arrangements should be made for 
deliveries of boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2011-0887. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through www.regulations.gov 
or email. The www.regulations.gov Web site is an ``anonymous access'' 
system, which means the EPA will not know your identity or contact 
information unless you provide it in the body of your comment. If you 
send an email comment directly to the EPA without going through 
www.regulations.gov, your email address will be automatically captured 
and included as part of the comment that is placed in the public docket 
and made available on the Internet. If you submit an electronic 
comment, the EPA recommends that you include your name and other 
contact information in the body of your comment and with any disk or 
CD-ROM you submit. If the EPA is unable to read your comment and cannot 
contact you for clarification due to technical difficulties, the EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, avoid any form of encryption, and be 
free of any defects or viruses. For additional information about the 
EPA's public docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm. For additional instructions on 
submitting comments, go to Section II of the SUPPLEMENTARY INFORMATION 
section of this document.
    Docket. All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically in www.regulations.gov or 
in hard copy at the EPA Docket Center, EPA West, Room 3334, 1301 
Constitution Avenue NW., Washington, DC. The Public Reading Room is 
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding 
legal holidays. The telephone number for the Public Reading Room is 
(202) 566-1744, and the telephone number for the Air Docket is (202) 


[[Page 39960]]

Quality Planning and Standards, Air Quality Policy Division, Mail Code 
C539-04, Research Triangle Park, NC 27711, telephone (919) 541-5432, 
email at palma.elizabeth@epa.gov.


I. Instructions for Submitting Public Comments

What should I consider as I prepare my comments for the EPA?

    1. Submitting CBI. Do not submit this information to the EPA 
through www.regulations.gov or email. Clearly mark the part or all of 
the information that you claim to be CBI. For CBI information in a disk 
or CD-ROM that you mail to the EPA, mark the outside of the disk or CD-
ROM as CBI and then identify electronically within the disk or CD-ROM 
the specific information that is claimed as CBI. In addition to one 
complete version of the comment that includes information claimed as 
CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2. Send or deliver information 
identified as CBI only to the following address: Roberto Morales, U.S. 
EPA, Office of Air Quality Planning and Standards, Mail Code C404-02, 
Research Triangle Park, NC 27711, telephone (919) 541-0880, email at 
morales.roberto@epa.gov, Attention Docket ID No. EPA-HQ-OAR-2011-0887.
    2. Tips for Preparing Your Comments. When submitting comments, 
remember to:
     Identify this notice by docket number and other 
identifying information (subject heading, Federal Register date, and 
page number).
     Follow directions--The agency may ask you to respond to 
specific questions or organize comments by referencing a Code of 
Federal Regulations (CFR) part or section number in the guidance.
     Explain why you agree or disagree; suggest alternatives 
and substitute language for your requested changes.
     Describe any assumptions and provide any technical 
information and/or data that you used.
     If you estimate potential costs or burdens, explain how 
you arrived at your estimate in sufficient detail to allow for it to be 
     Provide specific examples to illustrate your concerns, and 
suggest alternatives.
     Explain your views as clearly as possible, avoiding the 
use of profanity or personal threats.
     Make sure to submit your comments by the comment period 
deadline identified.

II. Background

    The purpose of this document is to solicit public comments on the 
EPA's recently posted draft non-binding guidance on the implementation 
of the March 22, 2007, Exceptional Events Rule (72 FR at 13560). These 
documents are available online at http://www.epa.gov/ttn/analysis/exevents.htm or within the associated docket, EPA-HQ-OAR-2011-0887.
    The draft guidance consists of an overview document, titled Draft 
Guidance to Implement Requirements for the Treatment of Air Quality 
Monitoring Data Influenced by Exceptional Events and its attachments: 
Attachment 1, Draft Exceptional Events Rule Frequently Asked Questions; 
Attachment 2, 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 (High Winds Guidance 
Document); and Attachment 3, Request for Comments on the Draft Guidance 
Documents on the Implementation of the Exceptional Events Rule. 
Together, these documents clarify key provisions and respond to 
questions and issues that have arisen since the EPA promulgated the 
Treatment of Data Influenced by Exceptional Events; Final Rule (72 FR 
at 13560), known as the Exceptional Events Rule (EER), pursuant to the 
2005 amendment of Clean Air Act (CAA) Section 319.
    The EPA provided previous versions of these draft guidance 
documents to state, local, and tribal agencies, and to other parties as 
requested, in May of 2011 to solicit preliminary comments. The EPA has 
prepared the document Responses to Significant First-Round Comments on 
the Draft Guidance Documents on the Implementation of the Exceptional 
Events Rule (the Response to Comments document), to track these 
preliminary comments and the EPA's responses.
    During this preliminary review period, the EPA received numerous 
comments, some of which the EPA has incorporated into the revised draft 
guidance documents. For example, the EPA has added an optional 
prospective controls analysis process and revised the discussion of the 
optional High Wind Action Plan; both of these are voluntary analyses 
that can facilitate agreement between states/local agencies/tribes and 
the EPA as to what measures constitute ``reasonable'' controls in 
advance of an actual event. Once the plans have gone through a notice 
and comment process at the state/local/tribal level and the EPA has 
approved these plans, the EPA generally anticipates that they will be 
effective for three years. Both of these approaches are described in 
more detail in the revised, draft High Winds Guidance document. The EPA 
solicits feedback on the anticipated use and functionality of these 
plans. Initial commenter feedback also asked the EPA to identify 
timelines for steps in the exceptional event submittal and review 
process. In the draft guidance documents, the EPA identifies suggested 
review and response timeframes, and indicates willingness to work with 
agencies on these timeframes to the extent the mandatory timing of the 
EPA regulatory actions allows.
    The EPA has also begun applying the principles in the draft 
guidance documents as we receive exceptional event submittal packages. 
For example, the EPA's Region 9 office worked with agencies in Arizona 
to incorporate approaches presented in the draft guidance documents 
into a consolidated exceptional events demonstration package that 
addresses numerous exceedances of the PM10 standard. The EPA 
hopes that, once finalized, much of the information included in this 
streamlined exceptional events demonstration submittal could be 
transferable and serve as a model for future events for both Arizona 
and other areas experiencing high wind dust events.
    While the EPA incorporated some comments into the revised draft 
guidance documents, the EPA did not incorporate all aspects of 
commenter feedback. For example, multiple commenters suggested that 
Exceptional Events Rule revisions are the appropriate mechanism to 
implement some of the approaches described in the guidance documents. 
The EPA maintains that 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 rule. 
The EPA is deferring a decision on whether to revise the Exceptional 
Events Rule.
    Initial feedback on the draft guidance documents also raised the 
following questions on which the EPA is specifically seeking comment:
     The EPA has developed draft exceptional event 
implementation guidance with the goal of establishing clear 
expectations to enable affected agencies to better manage resources as 
they prepare the documentation required under the EER. These draft

[[Page 39961]]

guidance documents identify mechanisms (e.g., demonstration 
prioritization, review time lines, High Wind Action Plans) to 
streamline the demonstration development, submittal, and review 
process. The EPA seeks comment regarding other specific, broadly 
applicable, streamlining mechanisms that the EPA could incorporate into 
the exceptional event implementation process.
     The EPA has modified the exceptional events Web site at 
http://www.epa.gov/ttn/analysis/exevents.htm to include additional 
links to tools, such as the DataFed Web site, that submitting agencies 
may use in the development of their demonstration submittals. The EPA 
has also posted exceptional event demonstrations that have already been 
reviewed and acted upon by the EPA. The EPA solicits feedback regarding 
other web-based information, links, tools, or methodologies that we can 
similarly post on our Web site.
     In the draft exceptional events guidance documents, the 
EPA defines the high wind threshold as the minimum threshold wind speed 
capable of overwhelming reasonable controls on anthropogenic sources 
(i.e., capable of causing significant dust emissions from controlled 
sources) or causing emissions from natural undisturbed areas. The EPA 
further notes that this area-specific threshold, along with the 
submitter's analysis of implemented reasonable controls and other 
factors, helps inform the analysis of the ``not reasonably controllable 
or preventable'' criterion. The EPA intends to allow air agencies to 
use wind data from a multitude of sources in the development of high 
wind thresholds. The EPA has identified several sources of local wind 
speed data including the National Weather Service, the National Climate 
Center, and local air monitoring stations. In addition, air agencies 
may use models such as Fifth Generation Pennsylvania State University/
National Center for Atmospheric Research Mesoscale Mode (MM5), Weather 
Research and Forecasting Model (WRF) and North American Mesoscale Model 
(NAM), to develop local wind speed data. The EPA solicits feedback on 
additional available sources of wind data and their applicability in 
informing local high wind analyses.
     As previously mentioned, demonstrations for high wind dust 
events necessarily include wind speed analyses. Generally, the EPA will 
accept that high winds could be the cause of a high 24-hour average 
PM10 or PM2.5 concentration if there was at least 
one full hour in which the hourly average wind speed was above area-
specific high wind threshold. Potential issues arise when determining 
the hourly average wind speed if wind speeds are not recorded at 
specified intervals throughout each hour. While some sources of wind 
speed data use hourly averages, other data sources employ 1-5 minute 
(``short-period'') averages. When the available wind speed data consist 
of only the wind speed during a fixed short period of each hour (e.g., 
the first or last 5 minutes of each hour) or the wind speed during the 
variable short period when wind speed was at its maximum during the 
hour, the EPA will generally accept that the hourly average wind speed 
was above the threshold if the reported short-period wind speed was 
above the threshold. Where wind speed is recorded at specified 
intervals throughout each hour, agencies should use all recorded data 
to calculate the hourly average wind speed. AERMINUTE, a preprocessor 
to AERMOD that takes short-period wind speed observations and 
calculates an hourly average wind, can assist in this calculation. 
AERMINUTE data, or other sub-hourly data with a resolution equal or 
greater than 5 minutes, can be fed into AERMET, the AERMOD 
meteorological processor, to get a user-friendly output. The EPA 
solicits additional feedback and tools to convert 1-5 minute wind speed 
data to hourly averages.
     Within the EPA's Air Quality System (AQS), monitoring 
agencies can use two types of data validation, or data qualifier, 
codes: the Request Exclusion flags (R) and the Informational Only flags 
(I). Agencies should use the I series flags when identifying 
informational data and the R series flags to identify data points for 
which the agency intends to request an exceptional event exclusion and 
the EPA's concurrence. Given that the EPA can act/concur only on R 
flags, some agencies have questioned the utility of I flags. Do AQS 
users find I flags in AQS useful? If so, how do users employ these 
     In response to comments received and in an effort to 
streamline the development of high wind demonstrations, the EPA has 
added an optional ``Prospective Controls Analysis'' process by which 
states, local agencies, and tribes can voluntarily provide information 
on attainment status, identify natural and anthropogenic windblown dust 
sources and emissions, provide the status of SIP submittals (if 
applicable), and identify the wind speed up to which the collective 
windblown dust controls are expected to be effective. This optional 
analysis can facilitate agreement between states/local agencies/tribes 
and the EPA as to what constitutes ``reasonable'' controls in advance 
of an actual event. The EPA has also added an optional ``High Wind 
Action Plan'' that states/local agencies/tribes can use to document 
current in-place controls, document controls on new sources that need 
reasonable controls for future events, and/or document current and/or 
planned mitigation measures. Both of these approaches are described in 
more detail in the revised draft High Winds Guidance document. The EPA 
anticipates that air agencies would submit the prospective controls 
analysis in advance of or with a demonstration package and similarly 
expects that air agencies would submit the High Wind Action Plan 
following the EPA's initial review of a demonstration package. The EPA 
recognizes that the information contained in the prospective controls 
analysis and the High Wind Action Plan is likely to overlap. The EPA 
solicits feedback on the anticipated use and functionality of these 
plans. Specifically, the EPA requests that commenters identify: (1) 
Specific elements in the prospective controls analysis and High Wind 
Action Plan that are useful, (2) whether these concepts should be 
combined or kept separate and (3) whether the flexibility to implement 
needed dust controls provided by the High Wind Action Plan as a 
voluntary alternative to the traditional regulatory nonattainment 
designation process is helpful.
     In Table 3 of the revised draft High Winds Guidance 
document, the EPA identifies example technical analyses that air 
agencies should consider when preparing their high wind dust event 
controls analysis to demonstrate the not reasonably controllable or 
preventable criterion. The EPA solicits comment on the identified 
analyses and any additional technical analyses that air agencies could 
use to demonstrate that the wind exceeded an identified high wind 
threshold and that the exceedance was caused by emissions that were not 
reasonably controllable.
     The EPA acknowledges that certain extreme exceptional 
event cases may require more limited demonstration packages. Whether a 
particular event should be considered ``extreme'' for this purpose 
depends on the type and severity of the event, pollutant concentration, 
spatial extent, temporal extent, and proximity of the event to the 
violating monitor. Several meteorological phenomena that could be 
considered extreme events include hurricanes, tornadoes, haboobs, and 
catastrophic volcanic eruptions. The EPA addresses ``extreme'' high 
wind dust events in the draft Q&A document,

[[Page 39962]]

but solicits comment on whether and how specific events of various 
types should be considered to be ``extreme.''
    With this document, the EPA is announcing the availability of 
revised draft guidance, along with examples of approved demonstrations 
on the EPA's Web site at http://www.epa.gov/ttn/analysis/exevents.htm. 
The EPA is providing the draft guidance to facilitate review of these 
materials by outside parties and to help ensure that the EPA's final 
guidance provides an efficient and effective process to make 
determinations regarding air quality data affected by events. The EPA 
notes that these draft guidance documents and the exceptional events 
Web site present examples to illustrate specific points. The example 
analyses and level of rigor are not necessarily required for all 
    After receiving timely submitted public comments on the draft 
guidance, the EPA plans to issue updated non-binding guidance. In 
addition, the EPA will continue to work closely with state, local, and 
tribal agencies to address issues arising during the development and 
submittal of exceptional event demonstration packages. The EPA is 
deferring a decision on whether to revise the Exceptional Events Rule.
    The EPA invites public comment on all aspects of this draft 
guidance during the 60-day comment period. The draft guidance is not a 
regulation or any other kind of final action and does not establish 
binding requirements on the EPA or any state, local, or tribal agency 
or any emissions source. While the EPA has established a docket and is 
requesting public comment on the draft guidance, this procedure does 
not alter the nature or effect of the draft guidance and does not 
constitute a formal rulemaking process or require the EPA to respond to 
public comments in the updated guidance before the EPA or other 
agencies may use the guidance in reaching decisions making related 
exceptional event demonstration submittals. The EPA retains the 
discretion to revise its guidance, issue additional guidance, propose 
regulations as appropriate, and to use information submitted in public 
comments to inform future decisions. Because this draft guidance does 
not constitute a formal rulemaking action, the EPA is not required to 
respond to comments, but intends to consider significant comments in 
amending or updating the non-binding guidance. Following the 60-day 
comment period and review and incorporation of comments, the EPA 
expects to post the revised, final guidance documents at http://www.epa.gov/ttn/analysis/exevents.htm.
    Please refer to the ADDRESSES section above in this document for 
specific instructions on submitting comments.

III. Internet Web Site for Guidance Information

    Interested parties can find the draft guidance titled, Draft 
Guidance Documents on the Implementation of the Exceptional Events 
Rule, on the Exceptional Events Web site for this rulemaking at http://www.epa.gov/ttn/analysis/exevents.htm. The Web site includes examples 
of reviewed exceptional event submissions, best practices components, 
and links to publicly available support information and tools that the 
public may find useful.

    Dated: June 26, 2012.
Mary E. Henigin,
Acting Director, Office of Air Quality Planning and Standards.
[FR Doc. 2012-16308 Filed 7-5-12; 8:45 am]