[Federal Register Volume 77, Number 130 (Friday, July 6, 2012)]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-16308]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 50 and 51
Draft Guidance To Implement Requirements for the Treatment of Air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binding guidance titled, Draft Guidance to Implement Requirements for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Events draft guidance.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
ADDRESSES: Access to the draft guidance: Please see the EPA's Web site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on the draft non-binding guidance titled, Draft Guidance to Implement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: email@example.com. 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
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)
FOR FURTHER INFORMATION CONTACT: Beth W. Palma, U.S. EPA, Office of Air
Quality Planning and Standards, Air Quality Policy Division, Mail Code
C539-04, Research Triangle Park, NC 27711, telephone (919) 541-5432,
email at firstname.lastname@example.org.
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
email@example.com, Attention Docket ID No. EPA-HQ-OAR-2011-0887.
2. Tips for Preparing Your Comments. When submitting comments,
Identify this notice by docket number and other
identifying information (subject heading, Federal Register date, and
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
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
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
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
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
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,
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]
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