
[Federal Register Volume 84, Number 43 (Tuesday, March 5, 2019)]
[Proposed Rules]
[Pages 7846-7854]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-03867]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2018-0235-; FRL-9988-59-Region 8]


Approval and Promulgation of Air Quality Implementation Plans; 
State of Montana; Missoula PM10 Nonattainment Area Limited 
Maintenance Plan and Redesignation Request

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
fully approve the Limited Maintenance Plan (LMP), submitted by the 
State of Montana to the EPA on August 3, 2016, for the Missoula 
moderate particulate matter with an aerodynamic diameter less than or 
equal to a nominal 10

[[Page 7847]]

micrometers (PM10) nonattainment area (Missoula NAA) and 
concurrently redesignate the Missoula NAA to attainment of the 24-hour 
PM10 National Ambient Air Quality Standard (NAAQS). In order 
to approve the LMP and redesignation, the EPA is proposing to determine 
that the Missoula NAA has attained the 1987 24-hour PM10 
NAAQS of 150 [micro]g/m\3\. This determination is based upon monitored 
air quality data for the PM10 NAAQS during the years 2015-
2017. The EPA is also proposing to approve the Missoula LMP as meeting 
the appropriate transportation conformity requirements. Lastly, the EPA 
is proposing to approve certain rule revisions the Missoula City-County 
Air Pollution Control Program submitted on August 3, 2016 and August 
22, 2018.

DATES: Written comments must be received on or before April 4, 2019.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2018-0235 at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from www.regulations.gov The EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    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, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in www.regulations.gov or in hard copy at the Air Program, U.S. 
Environmental Protection Agency (EPA), Region 8, 1595 Wynkoop Street, 
Denver, Colorado 80202-1129. The EPA requests that if at all possible, 
you contact the individual listed in the FOR FURTHER INFORMATION 
CONTACT section to view the hard copy of the docket. You may view the 
hard copy of the docket Monday through Friday, 8:00 a.m. to 4:00 p.m., 
excluding federal holidays.

FOR FURTHER INFORMATION CONTACT: James Hou, Air Program, U.S. 
Environmental Protection Agency (EPA), Region 8, Mail Code 8P-AR, 1595 
Wynkoop Street, Denver, Colorado 80202-1129, (303) 312-6210, 
hou.james@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,'' 
``us,'' or ``our'' is used, we mean the EPA.

I. Background

A. Description of the Missoula Nonattainment Area

    The Missoula NAA encompasses the City of Missoula and was 
designated nonattainment for the 1987 24-hour PM10 NAAQS and 
classified as moderate under section 107(d)(4)(B), following enactment 
of the Clean Air Act (CAA) Amendments of 1990. See 56 FR 56694 
(November 6, 1991). States containing initial moderate PM10 
nonattainment areas were required to submit, by November 15, 1991, a 
moderate nonattainment area State Implementation Plan (SIP) that, among 
other requirements, implemented Reasonably Available Control Measures 
(RACM) by December 10, 1993, and demonstrated whether it was 
practicable to attain the PM10 NAAQS by December 31, 1994. 
See generally 57 FR 13498 (April 16, 1992); see also 57 FR 18070 (April 
28, 1992).
    The State of Montana submitted an initial PM10 SIP to 
the EPA on August 21, 1991, and subsequently submitted three additional 
submittals between 1991and 1994. The State of Montana's SIP for the 
Missoula moderate nonattainment area included, among other things: a 
comprehensive emissions inventory; RACM; a demonstration that 
attainment of the PM10 NAAQS would be achieved in Missoula 
by December 31, 1994; Reasonable Further Progress (RFP) requirements; 
and control measures that satisfy the contingency measures requirement 
of section 172(c)(9) of the CAA. The EPA fully approved the Missoula 
NAA PM10 attainment plan on August 30, 1995 (60 FR 45051).

II. Requirements for Redesignation

A. CAA Requirements for Redesignation of Nonattainment Areas

    Nonattainment areas can be redesignated to attainment after the 
area has measured air quality data showing it has attained the NAAQS 
and when certain planning requirements are met. Section 107(d)(3)(E) of 
the CAA, and the General Preamble to Title I provide the criteria for 
redesignation. See 57 FR 13498 (April 16, 1992). These criteria are 
further clarified in a policy and guidance memorandum from John 
Calcagni, Director, Air Quality Management Division, EPA Office of Air 
Quality Planning and Standards dated September 4, 1992, ``Procedures 
for Processing Requests to Redesignate Areas to Attainment.'' \1\ The 
criteria for redesignation are:
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    \1\ The ``Procedures for Processing Requests to Redesignate 
Areas to Attainment'' (Calcagni memo) outlines the criteria for 
redesignation. The Calcagni memo can be found at https://www.epa.gov/sites/production/files/2016-03/documents/calcagni_memo_-_procedures_for_processing_requests_to_redesignate_areas_to_attainment_090492.pdf.
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    (1) The Administrator has determined that the area has attained the 
applicable NAAQS;
    (2) The Administrator has fully approved the applicable SIP for the 
area under section 110(k) of the CAA;
    (3) The state containing the area has met all requirements 
applicable to the area under section 110 and part D of the CAA;
    (4) The Administrator has determined that the improvement in air 
quality is due to permanent and enforceable reductions in emissions; 
and
    (5) The Administrator has fully approved a maintenance plan for the 
area as meeting the requirements of section 175A of the CAA.

B. The LMP Option for PM10 Nonattainment Areas

    On August 9, 2001, the EPA issued guidance on streamlined 
maintenance plan provisions for certain moderate PM10 
nonattainment areas seeking redesignation to attainment (Memo from 
Lydia Wegman, Director, Air Quality Standards and Strategies Division, 
entitled ``Limited Maintenance Plan Option for Moderate PM10 
Nonattainment Areas,'' (hereafter the LMP Option memo)).\2\ The LMP 
Option memo contains a statistical demonstration that areas meeting 
certain air quality criteria will, with a

[[Page 7848]]

high degree of probability, maintain the standard 10 years into the 
future. Thus, the EPA has already provided the maintenance 
demonstration for areas meeting the criteria outlined in the LMP Option 
memo. It follows that future year emission inventories for these areas, 
and some of the standard analyses to determine transportation 
conformity with the SIP are no longer necessary.
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    \2\ The ``Limited Maintenance Plan Option for Moderate 
PM10 Nonattainment Areas'' outlines the criteria for 
development of a PM10 limited maintenance plan and can be 
found at https://www.epa.gov/sites/production/files/2016-06/documents/2001lmp-pm10.pdf.
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    To qualify for the LMP Option, the area should have attained the 
1987 24-hour PM10 NAAQS, based upon the most recent 5 years 
of air quality data at all monitors in the area, and the 24-hour design 
value should be at or below the Critical Design Value (CDV). The CDV is 
a calculated design value that indicates that the area has a low 
probability (1 in 10) of exceeding the NAAQS in the future. For the 
purposes of qualifying for the LMP option, a presumptive CDV of 98 
[micro]g/m\3\ is most often employed, but an area may elect to use a 
site-specific CDV should the average design value be above 98 [micro]g/
m\3\, while demonstrating that the area has a low probability of 
exceeding the NAAQS in the future. The annual PM10 standard 
was effectively revoked on December 18, 2006 (71 FR 61143), and as such 
will not be discussed as a requirement for qualifying for the LMP 
option. In addition, the area should expect only limited growth in on-
road motor vehicle PM10 emissions (including fugitive dust) 
and should have passed a motor vehicle regional emissions analysis 
test. The LMP Option memo also identifies core provisions that must be 
included in the LMP. These provisions include an attainment year 
emissions inventory, assurance of continued operation of an EPA-
approved air quality monitoring network, and contingency provisions.

C. Conformity Under the LMP Option

    The transportation conformity rule (40 CFR parts 51 and 93) and the 
general conformity rule (40 CFR parts 51 and 93) apply to nonattainment 
areas and maintenance areas covered by an approved maintenance plan. 
Under either conformity rule, an acceptable method of demonstrating 
that a federal action conforms to the applicable SIP is to demonstrate 
that expected emissions from the planned action are consistent with the 
emissions budget for the area.
    While the EPA's LMP Option does not exempt an area from the need to 
affirm conformity, it explains that the area may demonstrate conformity 
without submitting an emissions budget. Under the LMP Option, emissions 
budgets are treated as essentially not constraining for the length of 
the maintenance period because it is unreasonable to expect that the 
qualifying areas would experience so much growth in that period that a 
violation of the PM10 NAAQS would result. For transportation 
conformity purposes, the EPA would conclude that emissions in these 
areas need not be capped for the maintenance period; and therefore, a 
regional emissions analysis would not be required. Similarly, federal 
actions subject to the general conformity rule could be considered to 
satisfy the ``budget test'' specified in 40 CFR 93.158(a)(5)(i)(A) for 
the same reasons that the budgets are essentially considered not 
limited.

III. Review of the Montana State Submittal Addressing the Requirements 
for Redesignation and Limited Maintenance Plans

A. Has the Missoula NAA attained the applicable NAAQS?

    States must demonstrate that an area has attained the 24-hour 
PM10 NAAQS through analysis of ambient air quality data from 
an ambient air monitoring network representing peak PM10 
concentrations. The data should be stored in the EPA Air Quality System 
(AQS) database. The EPA is proposing to determine that the Missoula NAA 
has attained the PM10 NAAQS based on monitoring data from 
calendar years 2015-2017. The 24-hour standard is attained when the 
expected number of days with levels above 150 [micro]g/m\3\ (averaged 
over a 3-year period) is less than or equal to one. 40 CFR 50.6(a). 
Three consecutive years of air quality data are generally necessary to 
show attainment of the 24-hour and annual standards for 
PM10. See 40 CFR part 50, appendix K. A complete year of air 
quality data, as referred to in 40 CFR part 50, appendix K, is 
comprised of all four calendar quarters with each quarter containing 
data from at least 75% of the scheduled sampling days.
    The Missoula NAA has one State and Local Air Monitoring Station 
(SLAMS) monitor operated by the Montana Department of Environmental 
Quality (MDEQ). Table 1 summarizes the PM10 data collected 
from 2013-2017. The EPA deems the data collected from this monitor 
valid, and the data has been submitted by the MDEQ to be included in 
AQS.

         Table 1--Summary of Maximum 24-Hour PM10 Concentrations ([micro]g/m\3\) for Missoula 2013-2017
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                                      Maximum          2nd maximum
              Year                 concentration      concentration        Number of          Monitoring site
                                  ([micro]g/m\3\)    ([micro]g/m\3\)      exceedances
----------------------------------------------------------------------------------------------------------------
                   Based on Data from Boyd Park Station, AQS Identification Number 30-063-0024
----------------------------------------------------------------------------------------------------------------
2013...........................                 59                 58                  0  Boyd Park.
2014...........................                 92                 88                  0  Boyd Park.
2015...........................                 90                 78                  0  Boyd Park.
2016...........................                 73                 65                  0  Boyd Park.
2017...........................                 86                 86                  0  Boyd Park.
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    The PM10 concentrations reported at the Missoula 
monitoring site showed no measured exceedances of the 24-hour 
PM10 NAAQS, and as such, the EPA proposes to determine that 
the Missoula Moderate NAA has attained the standard for the 24-hour 
PM10 NAAQS.

B. Does the Missoula NAA have a fully approved SIP under CAA section 
110(k)?

    In order to qualify for redesignation, the SIP for the area must be 
fully approved under CAA section 110(k) and must satisfy all 
requirements that apply to the area. Section 189 of the CAA contains 
requirements and milestones for all initial moderate nonattainment area 
SIPs including: (1) Provisions to assure that RACM (including such 
reductions in emissions from existing sources in the area as may be 
obtained through the adoption, at a minimum, of Reasonably Available 
Control Technology--RACT) shall be implemented no later than December 
10, 1993; (2) A demonstration (including air quality modeling) that the

[[Page 7849]]

plan will provide for attainment as expeditiously as practicable by no 
later than December 31, 1994, or, where the state is seeking an 
extension of the attainment date under section 188(e), a demonstration 
that attainment by December 31, 1994, is impracticable and that the 
plan provides for attainment by the most expeditious alternative date 
practicable (CAA sections 189(a)(1)(A)); (3) Quantitative milestones 
which are to be achieved every 3 years and which demonstrate RFP toward 
attainment by December 31, 1994, (CAA sections 172(c)(2) and 189(c)); 
and (4) Contingency measures to be implemented if the area fails to 
make RFP or attain by its attainment deadline. These contingency 
measures are to take effect without further action by the State or the 
EPA. (CAA section 172(c)(9)).
    On August 30, 1995, the EPA approved Missoula moderate area plan 
including RACM, an attainment demonstration, emissions inventory, 
quantitative milestones, and control and contingency measure 
requirements. As such, the area has a fully approved nonattainment area 
SIP under section 110(k) of the CAA. 60 FR 45051.

C. Has the State met all applicable requirements under Section 110 and 
Part D of the CAA?

    Section 107(d)(3)(E) of the CAA requires that a state containing a 
nonattainment area must meet all applicable requirements under section 
110 and Part D of the CAA for an area to be redesignated to attainment. 
The EPA interprets this to mean that the state must meet all 
requirements that applied to the area prior to, and at the time of, the 
submission of a complete redesignation request. The following is a 
summary of how Montana meets these requirements.
(1) CAA Section 110 Requirements
    Section 110(a)(2) of the CAA contains general requirements for 
state implementation plans. These requirements include, but are not 
limited to, submittal of a SIP that has been adopted by the state after 
reasonable notice and public hearing; provisions for establishment and 
operation of appropriate apparatus, methods, systems and procedures 
necessary to monitor ambient air quality; implementation of a permit 
program; provisions for Part C--Prevention of Significant Deterioration 
(PSD) and Part D--New Source Review (NSR) permit programs; criteria for 
stationary source emission control measures, monitoring and reporting, 
provisions for modeling; and provisions for public and local agency 
participation. See the General Preamble for further explanation of 
these requirements. 57 FR 13498 (April 16, 1992).
    For purposes of redesignation, the EPA's review of the Montana SIP 
shows that the State has satisfied all requirements under section 
110(a)(2) of the CAA. Further, in 40 CFR 52.1372, the EPA has approved 
Montana's plan for the attainment and maintenance of the national 
standards under section 110.
(2) Part D Requirements
    Part D contains general requirements applicable to all areas 
designated nonattainment. The general requirements are followed by a 
series of subparts specific to each pollutant. All PM10 
nonattainment areas must meet the general provisions of Subpart 1 and 
the specific PM10 provisions in Subpart 4, ``Additional 
Provisions for Particulate Matter Nonattainment Areas.'' The following 
paragraphs discuss these requirements as they apply to the Missoula 
NAA.
(3) Subpart 1, Section 172(c)
    Subpart 1, section 172(c) contains general requirements for 
nonattainment area plans. A thorough discussion of these requirements 
may be found in the General Preamble. See 57 FR 13538 (April 16, 1992). 
CAA section 172(c)(2) requires nonattainment plans to provide for RFP. 
Section 171(1) of the CAA defines RFP as ``such annual incremental 
reductions in emissions of the relevant air pollutant as are required 
by this part (part D of title I) or may reasonably be required by the 
Administrator for the purpose of ensuring attainment of the applicable 
national ambient air quality standard by the applicable date.'' Since 
the EPA is proposing to determine that the Missoula NAA is in 
attainment of the PM10 NAAQS, we believe that no further 
showing of RFP or quantitative milestones is necessary.
(4) Section 172(c)(3)--Emissions Inventory Section
    Section 172(c)(3) of the CAA requires a comprehensive, accurate, 
current inventory of actual emissions from all sources in the Missoula 
PM10 nonattainment area. Montana included an emissions 
inventory for the calendar year 2010 with its August 3, 2016 submittal 
of the LMP for the Missoula NAA. The LMP Option memo states that an 
attainment inventory should represent emissions during the same 5-year 
period associated with the air quality data used to determine that the 
area meets the applicability requirements of the LMP option. The 
Missoula LMP includes an emission inventory from 2010, representative 
of the 2009-2013 5-year period which served as the 5-year period relied 
upon in the Missoula LMP as meeting the air quality data requirements 
of the LMP option memo. The LMP option memo goes on to state that ``If 
the attainment inventory year is not one of the most recent 5 years, 
but the State can show that the attainment inventory did not change 
significantly during that 5-year period, it may still be used to 
satisfy the policy.'' An evaluation of the Missoula County 2011 
National Emissions Inventory (NEI) compared to the Missoula County 2014 
NEI indicates that the county experienced a roughly 50% decrease in 
PM10 emissions. When comparing the 2011 NEI to the 2014 NEI 
and removing wildfires from both inventories, the area still 
experienced a decrease in PM10 emissions. Noting the overall 
decrease in PM10 emissions for Missoula County, the 2010 
base year emissions inventory represents a current, accurate and 
comprehensive emission inventory; and therefore, meets the requirements 
of Section 172(c)(3) of the CAA.
(5) Section 172(c)(5)--NSR
    The 1990 CAA Amendments contained revisions to the NSR program 
requirements for the construction and operation of new and modified 
major stationary sources located in nonattainment areas. The CAA 
requires states to amend their SIPs to reflect these revisions, but 
does not require submittal of this element along with the other SIP 
elements. The CAA established June 30, 1992, as the submittal date for 
the revised NSR programs (Section 189 of the CAA).
    Montana has a fully approved nonattainment NSR program, most 
recently approved on August 30, 1995 (60 FR 45051). Montana also has a 
fully approved PSD program, most recently approved on August 30, 1995 
(60 FR 45051). Upon the effective date of redesignation of an area from 
nonattainment to attainment, the requirements of the Part D NSR program 
will be replaced by the PSD program and the maintenance area NSR 
program.
(6) Section 172(c)(7)--Compliance with CAA Section 110(a)(2): Air 
Quality Monitoring Requirements
    Once an area is redesignated, the state must continue to operate an 
appropriate air monitoring network in accordance with 40 CFR part 58 to 
verify attainment status of the area. The State of Montana and the City 
of Missoula operate one PM10 SLAMS in the Missoula NAA. The

[[Page 7850]]

Boyd Park monitoring site meets EPA SLAMS network design and siting 
requirements set forth at 40 CFR part 58, appendices D and E. In 
Section 7.3 of the LMP that we are proposing to approve, the State 
commits to continued operation of the monitoring network.
(7) Section 172(c)(9)--Contingency Measures
    The CAA requires that contingency measures take effect if the area 
fails to meet RFP requirements or fails to attain the NAAQS by the 
applicable attainment date. Since the Missoula NAA attained the 1987 
24-hour PM10 NAAQS by the applicable attainment date of 
December 31, 1994, contingency measures are no longer required under 
Section 172(c)(9) of the CAA. However, contingency provisions are 
required for maintenance plans under Section 175(a)(d). We describe the 
contingency provisions Montana provided in the Missoula LMP below.
(8) Part D Subpart 4
    Part D Subpart 4, Section 189(a), (c) and (e) requirements apply to 
any moderate nonattainment area before the area can be redesignated to 
attainment. The requirements which were applicable prior to the 
submission of the request to redesignate the area must be fully 
approved into the SIP before redesignating the area to attainment. 
These requirements include: (a) Provisions to assure that RACM was 
implemented by December 10, 1993; (b) Either a demonstration that the 
plan provided for attainment as expeditiously as practicable but not 
later than December 31, 1994, or a demonstration that attainment by 
that date was impracticable; (c) Quantitative milestones which were 
achieved every 3 years and which demonstrate RFP toward attainment by 
December 31, 1994; and (d) Provisions to assure that the control 
requirements applicable to major stationary sources of PM10 
also apply to major stationary sources of PM10 precursors 
except where the Administrator determined that such sources do not 
contribute significantly to PM10 levels which exceed the 
NAAQS in the area. These provisions were fully approved into the SIP 
upon the EPA's approval of the PM10 moderate area plan for 
the Missoula NAA on August 30, 1995 (see 60 FR 45051).

D. Has the State demonstrated that the air quality improvement is due 
to permanent and enforceable reductions?

    The state must be able to reasonably attribute the improvement in 
air quality to permanent and enforceable emission reductions. In making 
this showing, the state must demonstrate that air quality improvements 
are the result of actual enforceable emission reductions. This showing 
should consider emission rates, production capacities, and other 
related information. The analysis should assume that sources are 
operating at permitted levels (or historic peak levels) unless evidence 
is presented that such an assumption is unrealistic. Permanent and 
enforceable control measures in the Missoula NAA SIP include RACM. 
Emission sources in the Missoula NAA have been implementing RACM for at 
least 10 years. The State demonstrated that, by applying control 
measures for outdoor burning, controlling fugitive particulates from 
street sweeping and sanding, establishing paving requirements within 
the Air Stagnation Zone, restricting the use of solid fuel burning 
devices, establishing permit requirements for stationary sources (e.g., 
emission control requirements and opacity restrictions), and 
prohibiting visible emissions from four-cycle gasoline powered 
vehicles, Missoula has effectively controlled PM10 emissions 
from the largest contributing source categories of PM10. 
Specifically, the Missoula NAA has not experienced a violation of the 
PM10 NAAQS since 1989, reasonably indicating that the 
attainment of the PM10 NAAQS is both permanent and 
enforceable.
    Areas that qualify for the LMP will meet the NAAQS, even under 
worst case meteorological conditions. Under the LMP option, the 
maintenance demonstration is presumed to be satisfied if an area meets 
the qualifying criteria. Thus, by qualifying for the LMP, Montana has 
demonstrated that the air quality improvements in the Missoula area are 
the result of permanent emission reductions and not a result of either 
economic trends or meteorology. A description of the LMP qualifying 
criteria and how the Missoula area meets these criteria is provided in 
the following section.

E. Does the area have a fully approved maintenance plan pursuant to 
Section 175A of the CAA?

    In this action, we are proposing to approve the Limited Maintenance 
Plan in accordance with the principles outlined in the LMP Option.

F. Has the State demonstrated that the Missoula NAA qualifies for the 
LMP Option?

    The LMP Option memo outlines the requirements for an area to 
qualify for the LMP Option. First, the area should be attaining the 
NAAQS. As stated above in Section III.A., the EPA has determined that 
the Missoula NAA is attaining the PM10 NAAQS, based upon 
2013-2017 data, and has had no exceedances between the years 2013-2017.
    Second, the average design value (ADV) for the past 5 years of 
monitoring data (2013-2017) must be at or below the CDV. As noted in 
Section II.B., the CDV is a margin of safety value and is the value at 
which an area has been determined to have a 1 in 10 probability of 
exceeding the NAAQS. The LMP Option memo provides two methods for 
review of monitoring data for the purpose of qualifying for the LMP 
option. The first method is a comparison of a site's ADV with the CDV 
of 98 [micro]g/m\3\ for the 24-hour PM10 NAAQS. A second 
method that applies to the 24-hour PM10 NAAQS is the 
calculation of a site-specific CDV and a comparison of the site-
specific CDV with the ADV for the past 5 years of monitoring data. 
Table 2 outlines the design values for the years 2013-2017, and 
presents the ADV.
    Table 3 summarizes a total of 19 wildfire related events that were 
excluded from the calculated design values in Table 2. This table 
includes regionally concurred exceptional events, as well as values 
between 98 [micro]g/m\3\ and 155 [micro]g/m\3\ which were treated in a 
manner analogous to exceedance data under the Exceptional Events Rule 
(EER) for the purpose of determining the LMP option eligibility.\3\ The 
EER can be found in 40 CFR 50.14 and 40 CFR 51.930, and outlines the 
requirements for the treatment of monitored air quality data that has 
been heavily influenced by an exceptional event. 40 CFR 50.1(j) defines 
an exceptional event as an event which affects air quality, is not 
reasonably controllable or preventable, is an event caused by human 
activity that is unlikely to recur at a particular location or a 
natural event and is determined by the Administrator in accordance with 
40 CFR 50.14 to be an exceptional event. Exceptional events do not 
include stagnation of air masses or meteorological inversions, 
meteorological events involving high temperatures or lack of 
precipitation, or air pollution relating to source noncompliance. 40 
CFR 50.14(b) states that the EPA shall exclude data from use in 
determinations of exceedances and NAAQS violations where a state 
demonstrates to the EPA's satisfaction that an exceptional event caused 
a specific air pollution concentration in excess of one or more NAAQS 
at a particular air quality monitoring location and otherwise satisfies 
the requirements of section 50.14.

[[Page 7851]]

    The Table 3 values between 98 [micro]g/m\3\ and 155 [micro]g/m\3\, 
were treated in a manner analogous to the exceedance data under the EER 
but will remain in the Air Quality System database for use in 
calculating DV's for every purpose besides determining LMP 
eligibility.\3\ Supporting documentation of EPA's concurrence with the 
19 wildfire related events can be found in the docket.\4\
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    \3\ Update on Application of the Exceptional Events Rule to the 
PM10 Limited Maintenance Plan Option, US EPA, William T. 
Harnett, Director, Air Quality Policy Division, OAQPS, May 7, 2009.
    \4\ February 8, 2019 letter to MDEQ, Re: Exceptional Events 
Requests Regarding Exceedances of the 24-hour PM10 NAAQS 
and the LMP Eligibility Threshold at Montana Monitoring Sites with 
PM10 Nonattainment Areas; and November 1, 2018 letter to 
MDEQ, Re: Request for EPA concurrence on exceptional event claims 
for fine (PM2.5) and coarse (PM10) particulate 
matter data impacted by wildfires in 2015 and 2016.

   Table 2--Summary of 24-Hour PM10 Design Values ([micro]g/m\3\) for
                           Missoula 2013-2017
------------------------------------------------------------------------
                                         Design
                                          value
          Design value years           ([micro]g/     Monitoring site
                                          m\3\)
------------------------------------------------------------------------
 Based on Data from Boyd Park Station, AQS Identification Number 30-063-
                                  0024
------------------------------------------------------------------------
2013-2015............................          78  Boyd Park
2014-2016............................          78  Boyd Park.
2015-2017............................          86  Boyd Park.
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Average DV based on highest DVs..................  81
------------------------------------------------------------------------


   Table 3--24-Hour PM10 Events Excluded From 2013-2017 Design Values
------------------------------------------------------------------------
                                         24-hour
                                          value
                 Date                  ([micro]g/     Monitoring site
                                          m\3\)
------------------------------------------------------------------------
8/15/2015............................         133  Boyd Park.
8/20/2105............................         101  Boyd Park.
8/21/2105............................         116  Boyd Park.
8/24/2015............................         104  Boyd Park.
8/25/2015............................         120  Boyd Park.
8/26/2015............................         104  Boyd Park.
8/27/2015............................         119  Boyd Park.
8/28/2015............................       * 181  Boyd Park.
8/29/2015............................       * 276  Boyd Park.
8/12/2017............................         105  Boyd Park.
8/23/2017............................         129  Boyd Park.
8/29/2017............................         105  Boyd Park.
8/30/2017............................         108  Boyd Park.
9/4/2017.............................       * 233  Boyd Park.
9/5/2017.............................         107  Boyd Park.
9/6/2017.............................       * 158  Boyd Park.
9/7/2017.............................       * 201  Boyd Park.
9/8/2017.............................       * 193  Boyd Park.
9/9/2017.............................         103  Boyd Park.
------------------------------------------------------------------------
* EPA-Concurred Exceptional Events.

    The ADV for the 24-hour PM10 NAAQS for Missoula, based 
on data from the collocated SLAMS monitors for the years 2013-2017, is 
81 [micro]g/m\3\. This value falls below the presumptive 24-hour CDV of 
98 [micro]g/m\3\. Therefore, Missoula meets the design value criteria 
outlined in the LMP Option memo. For the 2013-2017 ADV calculations for 
PM10 in Missoula, please see the supporting documents in the 
docket.\5\
---------------------------------------------------------------------------

    \5\ See memo to file dated October 23, 2018 titled ``PM10 24-
hour Design Concentration for Missoula Montana.''
---------------------------------------------------------------------------

    Third, the area must meet the motor vehicle regional emissions 
analysis test in attachment B of the LMP Option memo. Using the 
methodology outlined in the memo, based on monitoring data for the 
period 2015-2017, the EPA has determined that the Missoula NAA passes 
the motor vehicle regional emissions analysis test, with a projected DV 
of 90.3 [micro]g/m\3\ after 10 years, attributable to motor vehicle 
emission growth. For the calculations used to determine that Missoula 
has passed the motor vehicle regional analysis test, see the supporting 
documents in the docket.\6\
---------------------------------------------------------------------------

    \6\ See memo to file dated October 24, 2018 titled ``Missoula 
Motor Vehicle Regional Emissions Analysis.''
---------------------------------------------------------------------------

    The monitoring data for the period 2015-2017 shows that Missoula 
has attained the 24-hour NAAQS for PM10, and the 24-hour ADV 
for Missoula is less than the 24-hour PM10 CDV. Finally, the 
area has met the regional vehicle emissions analysis test. Thus, the 
Missoula NAA qualifies for the LMP Option described in the LMP Option 
memo. The LMP Option memo also indicates that once a state selects the 
LMP Option and it is in effect, the state will be expected to 
determine, on an annual basis, that the LMP criteria are still being 
met. If the state determines that the LMP criteria are not being met, 
it should take action to reduce PM10 concentrations enough 
to requalify for the LMP. One possible approach the state could take is 
to implement contingency measures. Please see Section 6.3. for a 
description of contingency provisions submitted as part of the State's 
submittal.

G. Does the State have an approved attainment emissions inventory which 
can be used to demonstrate attainment of the NAAQS?

    The state's approved attainment plan should include an emissions 
inventory (attainment inventory) which can be used to demonstrate 
attainment of the NAAQS. The inventory should represent emissions 
during the same 5-year period associated with air quality data used to 
determine whether the area meets the applicability requirements of the 
LMP Option. The state should review its inventory every 3 years to 
ensure emissions growth is incorporated in the attainment inventory if 
necessary. In this instance, Montana completed an attainment year 
inventory for the attainment year 2010. The EPA has reviewed the 2010 
emissions inventory and determined that it is current, accurate and 
complete. The EPA has also reviewed monitoring data for the years 2013-
2017 and determined that the 2010 emissions inventory is representative 
of the attainment year inventory since the NAAQS was not violated 
during 2010. In addition, the emissions inventory submitted with the 
LMP for the calendar year 2010 is representative of the level of 
emissions during the time period used to calculate the average design 
value since 2010 is included in the 5-year period used to calculate the 
design value (2013-2017).

H. Does the LMP include an assurance of continued operation of an 
appropriate EPA-approved air quality monitoring network, in accordance 
with 40 CFR part 58?

    A PM10 monitoring network was established in the 
Missoula NAA in the 1980's and has been developed and maintained in 
accordance with federal siting and design criteria in 40 CFR part 58, 
Appendices D and E and in consultation with the EPA Region 8. In 2009 
the Health Department monitoring site was discontinued, leaving the 
Boyd Park as the one PM10/PM2.5 SLAMS/National 
Air Monitoring Stations (NAMS) monitors for the Missoula NAA. In 
Section 7.3 of the Missoula LMP, Montana states that it will continue 
to operate its monitoring network to meet EPA requirements.

I. Does the plan meet the CAA requirements for contingency provisions 
for maintenance plans?

    Section 175A of the CAA states that a maintenance plan must include 
contingency provisions, as necessary, to promptly correct any violation 
of the NAAQS which may occur after redesignation of the area to 
attainment. As explained in the LMP Option memo, these contingency 
measures do not have to be fully adopted at the time of redesignation. 
As noted above, CAA section 175A requirements are distinct from CAA 
section 172(c)(9) contingency measures. Section 6.3 of the Missoula 
Limited Maintenance Plan describes a process and timeline to identify 
and evaluate appropriate contingency measures in the event of a quality 
assured violation of the PM10 NAAQS. Within 60 days of 
notification of a PM10 exceedance, the MDEQ and the

[[Page 7852]]

Missoula City-County Health Department (MCCHD) will determine the 
significant contributor to the violation using chemical or microscopic 
analysis of exposed PM10 filters. If the major contributing 
source is re-entrained road dust, the MCCHD will implement Rule 8.304, 
which expands the area of regulated road sanding materials to East 
Missoula, Southwest Missoula near Buckhouse Bridge, West Missoula 
between the Clark Fork and Bitterroot Rivers, and Northwest Missoula in 
the Grant Creek area. If the major contributing source is wood burning, 
the MCCHD will implement Rules 4.113 and 9.601. Rule 4.113 mandates 
extensive nighttime enforcement of wood burning regulations when a 
Stage 1 Alert is declared. Rule 9.601 rescinds and/or voids Missoula 
City-County Air Pollution Control Program rules that allow certain 
solid fuel burning devices with an alert permit to produce visible 
emissions during air pollution alerts. If neither wood burning nor re-
entrained road dust is the major contributing source, the MCCHD will 
still implement one of the above contingency measures.
    The Missoula LMP will retain the existing contingency provisions 
identified in the Missoula LMP which include the following:
     Expanding the areas subject to road sanding materials 
regulation under Subchapter 3;
     Extensive nighttime enforcement of wood burning 
regulations during a Stage I Alert; and
     Mandatory wood burning curtailment.
    The current and proposed contingency provisions in the Missoula LMP 
meet the requirements for contingency provisions as outlined in the LMP 
Option memo.

J. Has the State met transportation and general conformity 
requirements?

(1) Transportation Conformity
    Transportation conformity is required by section 176(c) of the CAA. 
Conformity to a SIP means that transportation activities will not 
produce new air quality violations, worsen existing violations, or 
delay timely attainment of the NAAQS (CAA section 176(c)(1)(B)). The 
EPA's conformity rule at 40 CFR part 93, subpart A requires that 
transportation plans, programs and projects conform to SIPs and 
establishes the criteria and procedures for determining whether or not 
they conform. To effectuate its purpose, the conformity rule typically 
requires a demonstration that emissions from the Regional 
Transportation Plan, if applicable, and the Transportation Improvement 
Program are consistent with the motor vehicle emission budget (MVEB) 
contained in the control strategy SIP revision or maintenance plan (40 
CFR 93.101, 93.118, and 93.124). The EPA notes that a MVEB is usually 
defined as the level of mobile source emissions of a pollutant relied 
upon in the attainment or maintenance demonstration to attain or 
maintain compliance with the NAAQS in the nonattainment or maintenance 
areas. MVEBs are, however, treated differently with respect to LMP 
areas.\7\
---------------------------------------------------------------------------

    \7\ Further information concerning the EPA's interpretations 
regarding MVEBs can be found in the preamble to the EPA's November 
24, 1993, transportation conformity rule (see 58 FR 62193-62196).
---------------------------------------------------------------------------

    Our LMP Option memorandum does not require that MVEBs be identified 
in the maintenance plan. While the EPA's LMP Option memorandum does not 
exempt an area from the need to affirm conformity, it explains that the 
area may demonstrate transportation conformity without identifying and 
submitting a MVEB. The basis for this provision is that it is 
unreasonable to expect that an LMP area will experience so much growth 
during the maintenance period that a violation of the PM10 
NAAQS would result. Therefore, for transportation conformity purposes, 
the EPA has concluded that mobile source emissions in LMP areas need 
not be capped, with respect to a MVEB, for the maintenance period and a 
regional emissions analysis (40 CFR 93.118), for transportation 
conformity purposes, is also not required. We discussed the above in 
additional detail in our Missoula PM10 LMP Adequacy 
Determination Finding Federal Register Notice of September 27, 2018 (83 
FR 48715).
    However, since LMP areas are still maintenance areas, certain 
aspects will continue to be required for transportation projects 
located within the Missoula PM10 maintenance area. 
Specifically, for conformity determinations, projects will have to 
demonstrate that they are fiscally constrained (40 CFR 93.108) and meet 
the criteria for consultation and timely implementation (as applicable) 
of Transportation Control Measures (40 CFR 93.112 and 40 CFR 93.113, 
respectively). In addition, projects located within the Missoula 
PM10 LMP area will be required to be evaluated for potential 
PM10 hot-spot issues in order to satisfy the ``project 
level'' conformity determination requirements. As appropriate, a 
project may then need to address the applicable criteria for a 
PM10 hot-spot analysis as provided in 40 CFR 93.116 and 40 
CFR 93.123.
    Finally, our proposed approval of the Missoula PM10 LMP 
affects future PM10 project-level transportation conformity 
determinations as prepared by the Montana Department of Transportation 
in conjunction with the Federal Highway Administration and the Federal 
Transit Administration. See 40 CFR 93.100. As such, the EPA is 
proposing to approve the Missoula LMP as meeting the appropriate 
transportation conformity requirements found in 40 CFR part 93, subpart 
A.

(2) General Conformity

    Federal actions, other than transportation conformity, that meet 
specific criteria need to be evaluated with respect to the requirements 
of 40 CFR part 93, subpart B. The EPA's general conformity rule 
requirements are designed to ensure that emissions from a federal 
action will not cause or contribute to new violations of the NAAQS, 
exacerbate current violations, or delay timely attainment. However, as 
noted in our LMP Option memorandum and similar to the above discussed 
transportation conformity provisions, federal actions subject to our 
general conformity requirements would be considered to satisfy the 
``budget test,'' as specified in 40 CFR 93.158(a)(5)(i)(A). As 
discussed above, the basis for this provision in the LMP Option 
memorandum is that it is unreasonable to expect that an LMP area will 
experience so much growth during the maintenance period that a 
violation of the PM10 NAAQS would result. Therefore, for 
purposes of general conformity, a general conformity PM10 
emissions budget does not need to be identified in the maintenance 
plan, nor submitted, and the emissions from federal agency actions are 
essentially considered to not be limited.

IV. EPA's Review of the State of Montana's August 3, 2016 and August 
22, 2018 Submittals (Regulatory Text)

    We evaluated Montana's August 3, 2016 submittal regarding revisions 
to the Missoula City-County Air Pollution Control Program (MCCACP), and 
Montana's August 22, 2018 submittal withdrawing items from the August 
3, 2016 submittal. The August 3, 2016 submittal contained rule 
revisions to Chapter 4: Emergency Episode Avoidance Plan; Chapter 6: 
Industrial Sources; Chapter 9: Solid Fuel Burning Devices; and Chapter 
14: Administrative Procedures, which were made State effective on May 
14, 2010. Additionally, the August 3, 2016 submittal contained rule 
revisions to Chapter 2: Definitions;

[[Page 7853]]

Chapter 4: Emergency Episode Avoidance Plan; Chapter 6: Industrial 
Sources; Chapter 9: Solid Fuel Burning Devices; Chapter 14: 
Administrative Procedures; and Chapter 15: Penalties, which were made 
State effective on March 21, 2014. The August 22, 2018 submittal 
contained revisions to Chapter 4: Emergency Episode Avoidance Plan and 
was made State effective on April 6, 2018. We are proposing to approve 
some of the revisions and not act on others.

A. August 3, 2016 SIP Submittal

    The August 3, 2016 SIP submittal includes revisions to eight 
chapters on Definitions, Failure to Attain Standards, Emergency Episode 
Avoidance Plan, Industrial Sources, Fugitive Particulate, Solid Fuel 
Burning Devices, Administrative Procedures, and Penalties. A summary of 
the changes that EPA is proposing to approve can be found Table 4 
below. A detailed analysis of the revisions can be found in the docket. 
Not included in Table 4 is a revision to Chapter 9: Solid Fuel Burning 
Devices, Rule 9.204, which prescribes the permit requirements for solid 
fuel burning devices outside of the air stagnation zone. The EPA is not 
acting on the submitted revision to Chapter 9, Rule 9.204 in the August 
3, 2016 submittal in this action.

 Table 4--Summary of Revisions to the Missoula City-County Air Pollution
                 Control Program, Proposed for Approval
------------------------------------------------------------------------
          Chapter revised                 Description of revisions
------------------------------------------------------------------------
Chapter 2: Definitions............  --Adds definition of PM2.5 and
                                     Impact Zone M.
Chapter 3: Failure to Attain        --Corrects reference errors.
 Standards.
Chapter 4: Emergency Episode        --Sets area for Air Quality Alerts
 Avoidance Plan.                     to Air Stagnation Zone and area for
                                     Stage II Warnings to Impact Zone M.
                                    --Creates Wildfire Emergency Plan
                                     Authority.
Chapter 6: Industrial Sources.....  --Requires Solid Fuel Burning
                                     Sources of 1,000,000 Btu heat input
                                     per hour or more to receive an air
                                     quality permit.
                                    --Sets Emission Limit of 0.1 pounds
                                     per million Btu/hr heat inputs and
                                     requires LAER for solid fuel
                                     boilers with heat input capacity to
                                     burn 1,000,000 Btu/hr or more in
                                     the Air Stagnation Zone.
                                    --Sets Emission Limit of 0.2 pounds
                                     per million Btu/hr heat inputs and
                                     requires BACT for solid fuel
                                     boilers with heat input capacity to
                                     burn 1,000,000 Btu/hr or more
                                     outside the Air Stagnation Zone.
Chapter 8: Fugitive Particulate...  --Allows the use of block pavers as
                                     an alternative to asphalt or
                                     concrete paving where feasible.
Chapter 9: Solid Fuel Burning       --Requires permits for all new
 Devices.                            installations of solid fuel burning
                                     devices throughout the county,
                                     excluding Airshed 2.
                                    --Sets emissions standards for new
                                     installations of solid fuel burning
                                     devices.
                                    --Expands solid fuel burning device
                                     enforcement areas during Alerts to
                                     Air Stagnation Zone and during
                                     Warnings Impact Zone M.
                                    --Sets County Wide Opacity Limit of
                                     40% for solid fuel burning devices
                                     outside of start-up times.
                                    --Allows licensed mobile food
                                     service establishments to obtain a
                                     solid fuel burning device permit
                                     throughout the county.
                                    --Changes labeling requirements for
                                     businesses that sell solid fuel
                                     burning devices.
Chapter 14: Administrative          --Clarifies that those individuals
 Procedures.                         who are adversely affected by the
                                     department's decision to deny,
                                     modify, or issue a permit are
                                     entitled to request an
                                     administrative review by the Health
                                     Officer.
Chapter 15: Penalties.............  --Corrects reference errors.
------------------------------------------------------------------------

B. August 22, 2018 Submittal

    On August 22, 2018 the State of Montana submitted two revisions, 
one pertaining to Incorporation by Reference (IBR) and a second 
submittal with revisions to Chapter 4: Missoula County Air Stagnation 
and Emergency Episode Avoidance Plan. The EPA's proposed action 
pertains exclusively to the Chapter 4 revisions, which withdraws 
previous references to PM2.5 in Chapter 4, denoting that 
those requirements are effective at the State and County level only. 
The EPA is proposing to approve the August 22, 2018 revisions to 
Chapter 4: Missoula County Air Stagnation and Emergency Episode 
Avoidance Plan and will act on the IBR revisions in a future action.

V. The EPA's Proposed Action

    For the reasons explained in Section III, we are proposing to 
approve the LMP for the Missoula NAA and the State's request to 
redesignate the Missoula NAA from nonattainment to attainment for the 
1987 24-hour PM10 NAAQS. Additionally, the EPA is proposing 
to determine that the Missoula NAA has attained the NAAQS for 
PM10. This determination is based upon monitored air quality 
data for the PM10 NAAQS during the years 2015-2017. The EPA 
is proposing to approve the Missoula LMP as meeting the appropriate 
transportation conformity requirements found in 40 CFR part 93, subpart 
A. Lastly, the EPA is proposing to approve most of the revisions 
submitted on August 3, 2016 and August 22, 2018 (Chapter 4 revisions), 
to the eight chapters on Definitions, Failure to Attain Standards, 
Emergency Episode Avoidance Plan, Industrial Sources, Fugitive 
Particulate, Solid Fuel Burning Devices, Administrative Procedures, and 
Penalties. As identified in Section IV, the EPA is not acting on 
Chapter 9, rule 9.204 in the August 3, 2016 submittal or the IBR 
revisions in the August 22, 2018 submittal.

VI. Incorporation by Reference

    In this rule, the EPA is proposing to include regulatory text in an 
EPA final rule that includes incorporation by reference. In accordance 
with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by 
reference MDEQ regulations discussed in Section IV, EPA's Review of the 
State of Montana's August 3, 2016 and August 22, 2018 Submittals 
(Regulatory Text), of this preamble. The EPA has made,

[[Page 7854]]

and will continue to make, these materials generally available through 
www.regulations.gov and at the EPA Region 8 Office (please contact the 
person identified in the FOR FURTHER INFORMATION CONTACT section of 
this preamble for more information).

VII. Statutory and Executive Orders Review

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely proposes to approve state law as meeting federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide the EPA with the discretionary authority 
to address, as appropriate, disproportionate human health or 
environmental effects, using practicable and legally permissible 
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where the EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction. In those areas of 
Indian country, the proposed rule does not have tribal implications and 
will not impose substantial direct costs on tribal governments or 
preempt tribal law as specified by Executive Order 13175 (65 FR 67249, 
November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Particulate matter, Reporting 
and recordkeeping requirements.

    Authority: 42 U.S.C. 7401 et seq.

    Dated: February 27, 2019.
Douglas Benevento,
Regional Administrator, EPA Region 8.
[FR Doc. 2019-03867 Filed 3-4-19; 8:45 am]
 BILLING CODE 6560-50-P


