[Federal Register Volume 82, Number 120 (Friday, June 23, 2017)]
[Proposed Rules]
[Pages 28605-28611]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-13190]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R07-OAR-2017-0251; FRL-9963-75-Region 7]


Approval of Missouri Air Quality Implementation Plans; 
Determination of Attainment for the 2010 1-Hour Primary Sulfur Dioxide 
National Ambient Air Quality Standard; Jefferson County Nonattainment 
Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
determine that the Jefferson County nonattainment area, in Missouri, 
has attained the 2010 1-hour primary Sulfur Dioxide (SO2) 
National Ambient Air Quality Standard (NAAQS) per the EPA's Clean Data 
Policy. This proposed determination of attainment is based upon 
complete, quality assured, and certified ambient air monitoring data 
from the 2014-2016 monitoring period, associated dispersion modeling, 
and supplemental emissions inventory information, which demonstrate 
that the Jefferson County area attained the 2010 1-hour primary 
SO2 NAAQS.

DATES: Comments must be received on or before July 24, 2017.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R07-
OAR-2017-0251, to https://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from 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 https://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Ms. Tracey Casburn, Environmental 
Protection Agency, Air Planning and Development Branch, 11201 Renner 
Boulevard, Lenexa, Kansas 66219 at (913) 551-7016, or by email at 
[email protected].

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and 
``our'' refer to the EPA. This section provides additional information 
by addressing the following:

I. What action is the EPA proposing?
II. What is the background of this action?
    a. Nonattainment Designation
    b. Clean Data Policy
    c. How does a Nonattainment Area achieve ``Clean Data'' for the 
2010 1-hour primary SO2 NAAQS?
    d. What information did the state provide to the EPA to 
demonstrate that the area has attained the NAAQS?
    e. What is the EPA's rationale for proposing this action?
III. What is the EPA's analysis of the state's Air Quality 
Monitoring and Modeling Data, and the state's Supplemental Emissions 
Inventory Information?
    a. Ambient Air Quality Monitoring Data Evaluation
    b. Modeling Data and Supplemental 2016 Emissions Information 
Evaluation
IV. What would be the effects of this action, if promulgated?
V. Statutory and Executive Order Reviews

I. What action is the EPA proposing?

    The EPA is proposing to determine that the Jefferson County 2010 1-
hour primary SO2 nonattainment area (hereby referred to as 
``the nonattainment area''), in Missouri, has attained the 2010 1-hour 
primary SO2 NAAQS.\1\ This proposed determination of 
attainment is based on a February 2016 request from the state (as later 
supplemented) that the EPA consider information--including complete, 
quality assured, and certified ambient air monitoring data from the 
2013-2015 monitoring period, with additional certified monitoring data 
from 2016, associated dispersion modeling for the 2013-2015 emission 
years, as well as supplemental 2016 emissions inventory information--
which show that the nonattainment area has attained the 2010 1-hour 
primary SO2 NAAQS.2 3
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    \1\ In accordance with Appendix T to 40 CFR part 50, the 1-hour 
primary SO2 NAAQS is met at an ambient air quality 
monitoring site when the valid 1-hour primary standard design value 
is less than or equal to 75 parts per billion (ppb). 40 CFR 
50.17(b).
    \2\ In accordance with Appendix T to 40 CFR part 50, a 1-hour 
primary SO2 NAAQS design value is valid if it encompasses 
three consecutive calendar years of complete data. A year meets data 
completeness requirements when all 4 quarters are complete. A 
quarter is complete when at least 75 percent of the sampling days 
for each quarter have complete data. A sampling day has complete 
data if 75 percent of the hourly concentration values, including 
state-flagged data affected by exceptional events which have been 
approved for exclusion by the Administrator, are reported.
    \3\ Monitoring data must be reported, quality assured, and 
certified in accordance with the requirements set forth in 40 CFR 
part 58.
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    The EPA has made the monitoring data, the modeling data, the 
supplemental emissions inventory information and additional information 
submitted by the state to support this proposed action available in the 
docket to this rulemaking through www.regulations.gov and/or at the EPA 
Region 7 Office (please contact the person identified in the FOR 
FURTHER INFORMATION CONTACT section of this preamble for more 
information).

II. What is the background of this action?

a. Nonattainment Designation

    On June 2, 2010 (75 FR 35520), the EPA established a health-based 
1-hour primary SO2 NAAQS at 75 ppb. Upon promulgation of a 
new or revised NAAQS, section 107(d) of the Clean Air

[[Page 28606]]

Act (CAA) requires the EPA to designate any area that does not meet (or 
that contributes to ambient air quality in a nearby area that does not 
meet) the NAAQS as nonattainment. On August 5, 2013, the EPA designated 
a portion of Jefferson County, Missouri, as nonattainment for the 2010 
1-hour primary SO2 NAAQS, effective October 4, 2013.\4\ The 
designation was based on 2008-2010 monitoring data in Herculaneum, 
Missouri, which monitored violations of the standard (see section III 
of this document for additional monitoring information). The effective 
date of the nonattainment designation was October 4, 2013. This action 
established an attainment date five years after the effective date for 
the areas designated as nonattainment for the 2010 SO2 NAAQS 
(i.e., by October 4, 2018). The state was also required to submit a 
State Implementation Plan (SIP) for the nonattainment area to the EPA 
that meets the requirements of CAA sections 110, 172(c) and 191-192 
within 18 months following the October 4, 2013, effective date of 
designation (i.e., by April 4, 2015). The State of Missouri submitted 
the ``Nonattainment Area Plan for the 2010 1-Hour Sulfur Dioxide 
National Ambient Air Quality Standard Jefferson County Sulfur Dioxide 
Nonattainment Area'' on June 5, 2015.
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    \4\ 78 FR 47191 (August 5, 2013), codified at 40 CFR 81.326.
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b. Clean Data Policy

    Where states request a clean data determination of a designated 
SO2 NAAQS nonattainment area, the EPA will determine whether 
or not an area has attained the NAAQS based on air quality monitoring 
data (when available) and air quality dispersion modeling information 
for the affected area as necessary. The EPA issued ``Clean Data'' 
policy memoranda for SO2 and other NAAQS describing reduced 
attainment planning requirements for nonattainment areas that attain 
the NAAQS, but have not yet been redesignated as 
attainment.5 6 Additionally, the EPA has issued national 
rulemakings that have codified this policy for ozone and fine 
particulate matter (PM2.5) NAAQS.\7\ Under the Clean Data 
policy, the EPA interprets the requirements of the CAA that are 
specifically designed to help an area achieve attainment, such as 
attainment demonstrations and implementation of reasonably available 
control measures (including reasonably available control technology), 
reasonable further progress (RFP) demonstrations, and contingency 
measures, to be suspended as long as air quality continues to meet the 
standard.
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    \5\ Memorandum of December 14, 2004, from Steve Page, Director, 
EPA Office of Air Quality Planning and Standards to the EPA Air 
Division Directors, ``Clean Data Policy for the Fine Particle 
National Ambient Air Quality Standards.'' This document is available 
at: http://www.epa.gov/pmdesignations/guidance.htm.
    \6\ The memorandum of April 23, 2014, from Steve Page, Director, 
EPA Office of Air Quality Planning and Standards to the EPA Air 
Division Directors ``Guidance for 1-hr SO2 Nonattainment 
Area SIP Submissions'' provides guidance for the application of the 
clean data policy to the 2010 1-hour primary SO2 NAAQS. 
This document is available at https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf.
    \7\ See, e.g., 81 FR 58010, 81 FR 58127-58129 (August 24, 2016) 
(promulgating 40 CFR 51.1015); 80 FR 12264, 80 FR 12296 
(promulgating 51.1118). See also 70 FR 71612, 70 FR 71664-46 
(November 29, 2005); 72 FR 20585, 72 FR 20603-20605 (April 25, 
2007).
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    In the memorandum of April 23, 2014, from Steve Page, Director, EPA 
Office of Air Quality Planning and Standards to the EPA Air Division 
Directors ``Guidance for 1-hr SO2 Nonattainment Area SIP 
Submissions'' (2014 SO2 Nonattainment Area Guidance), the 
EPA explained its intention to extend the Clean Data Policy to 1-hour 
SO2 nonattainment areas that attained the standard. As noted 
therein, the legal bases set forth in the various guidance documents 
and regulations establishing the Clean Data Policy for other pollutants 
are equally pertinent to all NAAQS.\8\ This proposed rule is also 
consistent with prior actions of the EPA applying the Clean Data Policy 
to two other nonattainment areas under the 2010 SO2 
NAAQS.\9\
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    \8\ See court cases upholding legal basis for the EPA's Clean 
Data Determination Policy, NRDC v. EPA, 571 F.3d at 1258-61 (D.C. 
Cir. 2009); Sierra Club v. EPA, 99 F.3d 1551 (10th Cir. 1996); 
Latino Issues Forum v. EPA, 315 Fed. App. 651, 652 (9th Cir. 2009).
    \9\ 82 FR 13227 (March 10, 2016) and 81 FR 28718 (May 10, 2016).
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    Clean data determinations are not redesignations to attainment. For 
the EPA to redesignate an area to attainment, a state must submit and 
receive full approval of a redesignation request that satisfies all of 
the statutory criteria for redesignation to attainment, including a 
demonstration that the improvement in the area's air quality is due to 
permanent and enforceable reductions; have a fully approved SIP that 
meets all of the applicable requirements under CAA section 110 and CAA 
part D; and have a fully approved maintenance plan.

c. How does a nonattainment area achieve ``clean data'' for the 2010 1-
hour primary SO2 NAAQS?

    Generally, the EPA relies on ambient air quality monitoring data 
alone in order to make determinations of attainment for areas 
designated nonattainment for a particular NAAQS. However, given the 
Agency's historical approach toward SO2, the source-specific 
nature of SO2 emissions, and the localized effect of those 
emissions, in the preamble to the 2010 1-hour primary SO2 
NAAQS rulemaking, the EPA stated that it did not expect to rely solely 
on monitored air quality data in all areas when determining if an area 
has attained the 2010 1-hour primary SO2 NAAQS (75 FR 
35551). As the EPA noted in the preamble, in order for the EPA to 
determine that an area is attaining the 2010 1-hour primary 
SO2 NAAQS, dispersion modeling may be needed to show no 
violating receptors even if a monitoring site showed no violations.\10\ 
This was because, as the EPA explained in the preamble, the Agency did 
not expect that most existing SO2 monitors were well sited 
to record maximum 1-hour ambient SO2 concentrations under 
the new NAAQS. The 2014 SO2 Nonattainment Area Guidance 
states that, in order for a nonattainment area that was designated 
based on air quality monitoring data to be determined as attaining the 
NAAQS, the state would need to meet a series of criteria. First, the 
state would need to demonstrate that the area is meeting the standard 
based on three consecutive calendar years of air quality monitoring 
that is complete and quality-assured (consistent with 40 CFR part 58 
requirements). Second, the state would need to either (1) provide 
modeling of the most recent three years of actual

[[Page 28607]]

emissions for the area or (2) provide a demonstration that the affected 
monitor(s) is or are located in the area of maximum concentration. As 
explained in more detail later in this section, the EPA believes that 
it is permissible to substitute current source-specific allowable 
emissions for actual emissions for the purpose of demonstrating (1) in 
this paragraph.
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    \10\ As noted in the preamble to the 2010 1-hour primary 
SO2 NAAQS (75 FR 35551), this has been the EPA's general 
position throughout the history of implementation of the 
SO2 NAAQS program. See, e.g., ``Air Quality Control 
Regions, Criteria, and Control techniques; Attainment Status 
Designations,'' 43 FR 40412, 43 FR 40415-43 FR 40416 (September 11, 
1978); ``Air Quality Control Regions, Criteria, and Control 
Techniques,'' 43 FR 45993, 43 FR 46000-43 FR 46002 (October 5, 
1978); ``Air Quality Implementation Plans: State Implementation 
Plans; General Preamble,'' 57 FR 13498, 57 FR 13545, 57 FR 13547-57 
FR 13557, 57 FR 13548 (April 16, 1992); ``Approval and Promulgation 
of State Implementation Plans; Call for Sulfur Dioxide SIP Revisions 
for Billings/Laurel, MT,'' 58 FR 41430 (August 4, 1993); 
``Designation of Areas for Air Quality Planning Purposes; Ohio,'' 59 
FR 12886, 59 FR 12887 (March 18, 1994); ``Ambient Air Quality 
Standards, National and Implementation Plans for Sulfur Oxides 
(Sulfur Dioxide),'' 60 FR 12492, 60 FR 12494-60 FR 12495 (March 7, 
1995); ``Air Quality Implementation Plans; Approval and 
Promulgation: Various States: Montana,'' 67 FR 22167, 67 FR 22170-67 
FR 22171, 67 FR 22183-67 FR 22887 (May 2, 2002).
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    If a demonstration shows that the monitor(s) is or are located in 
the area of maximum concentration, the EPA believes that it may be 
appropriate to determine that the nonattainment area is attaining the 
standard based on monitoring data alone. The state did not submit a 
demonstration that the monitor was located in the area of maximum 
concentration, therefore its submittal needed to provide a modeling 
demonstration in support of a clean data determination.
    The 2014 SO2 Nonattainment Area Guidance states that, 
when air agencies provide monitoring and/or modeling to support clean 
data determinations, the monitoring data provided by the state should 
follow the EPA's ``SO2 NAAQS Designations Source-Oriented 
Monitoring Technical Assistance Document'' (SO2 monitoring 
TAD) and the modeling provided by the state should follow the EPA's 
``SO2 NAAQS Designations Modeling Technical Assistance 
Document'' (SO2 Modeling TAD).11 12 The 
SO2 Modeling TAD outlines modeling approaches for future 
SO2 NAAQS attainment status designations and states that, 
for the purposes of modeling to characterize air quality for use in 
SO2 designations, the EPA recommends using a minimum of the 
most recent three years of actual emissions data and concurrent 
meteorological data to allow the modeling to simulate what a monitor 
would observe. Additionally, the SO2 Modeling TAD indicates 
that it is acceptable to use allowable emission rates instead of actual 
emission rates. Although past actual emissions could have been higher 
than those under the most recent allowable rate, the SO2 
Modeling TAD reflects the EPA's belief that it is reasonable to account 
for any lower allowable limits currently in place when determining if 
an area is attaining the NAAQS. In addition, the SO2 
Modeling TAD indicates that, where an allowable emissions limit has 
been lowered during the relevant three-year period (such as through the 
implementation of emissions controls), the air agency may rely on the 
new limit in demonstrating that the modeled limit assures attainment. 
In this fashion, the most recent permitted or potential to emit rate 
should be used along with a minimum of the most recent three years of 
meteorological data.\13\
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    \11\ The SO2 NAAQS Designations Source-Oriented 
Monitoring Draft Technical Assistance Document, Office of Air 
Quality Planning and Standards, Air Quality Assessment Division, May 
2013, can be found at https://www.epa.gov/sites/production/files/2016-06/documents/so2monitoringtad.pdf.
    \12\ The SO2 NAAQS Designations Modeling Technical 
Assistance Document, Office of Air Quality Planning and Standards, 
Air Quality Assessment Division, May 2013, can be found at https://www.epa.gov/sites/production/files/2016-06/documents/so2modelingtad.pdf.
    \13\ See page 10 of the SO2 Modeling TAD.
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    The EPA believes that modeling a mix of current allowable emissions 
and actual emissions would be permissible in such an analysis as long 
as the same type of emissions are used for each source for all three 
years. For instance, if a state decided to use current allowables for a 
facility in a modeling analysis, the state would need to use current 
allowables for all three years of the analysis for that facility. The 
state would not necessarily need to use current allowables for the 
other sources in the analysis (i.e., actuals would be permissible for 
all three years for other sources in the area). The EPA believes this 
kind of analysis is appropriate for both designations and clean data 
determinations, both of which use the analysis to determine whether the 
area is currently meeting the NAAQS.
    The EPA recognizes that its 2014 SO2 Nonattainment Area 
Guidance does not on its face suggest that modeling allowable emissions 
would be an acceptable alternative to modeling actual emissions in the 
clean data determination or redesignations contexts. However, the 
Agency considers it to have been an oversight on its part not to have 
addressed this alternative possibility in the 2014 SO2 
Nonattainment Area Guidance, as the Agency clearly has endorsed the use 
of both actual emissions and allowable emissions in the SO2 
Modeling TAD in general and in the recent rounds of area designations 
under the SO2 NAAQS, in contexts where, as here, the Agency 
is making a factual judgment about whether an area has attained the 
NAAQS. Moreover, the 2014 guidance also suggests that modeling of 
allowables emissions, combined with other information, could also be 
used to determine whether, after the attainment deadline has passed, 
areas in fact timely attained the NAAQS under CAA section 179. 
Therefore, although the SO2 Nonattainment Area Guidance was 
silent on using allowable emissions in the clean data determination and 
redesignations contexts, the EPA believes it is not inconsistent with 
the guidance to endorse that practice now, provided the allowables-
based modeling is conducted appropriately pursuant to the 
SO2 Modeling TAD and applicable EPA regulations such as 
those governing stack heights and dispersion techniques at 40 CFR 
51.100 and 40 CFR 51.118.

d. What information did the state provide to the EPA to demonstrate 
that the area attained the NAAQS?

    On February 2, 2016, the state submitted a request asking the EPA 
to determine that the nonattainment area attained the 2010 1-hour 
primary SO2 NAAQS per the EPA's Clean Data Policy. The 
request included the most recent three years of complete, quality 
assured, and certified ambient air monitoring data from the 2013-2015 
monitoring period; the design value for 2013-2015 was 66.0 ppb. In a 
response letter, dated March 4, 2016, the EPA stated that, because the 
request did not include a modeling demonstration showing attainment 
utilizing the most recent three years of actual emissions or a 
demonstration that the monitor was located in the area of maximum 
concentration for the nonattainment area, the state's request did not 
contain the necessary supporting information as outlined in the EPA's 
2014 SO2 Nonattainment Area Guidance. In a letter dated 
August 4, 2016, the state provided modeling of the most recent three 
years of actual emissions (2013-2015) for the nonattainment area. 
However, in the provided modeling, the Doe Run Herculaneum facility was 
zeroed out despite the fact that the facility was still operating in 
2013.\14\ On November 9, 2016, the EPA asked the state (via email) to 
provide additional information regarding the exclusion of emissions 
from the Doe Run Herculaneum facility for the 2013-2015 emission years 
from the modeling demonstration as well as additional information 
regarding its selection of the 2014 emissions data year as a surrogate 
for the interactive sources' emissions.\15\ The state submitted 
supporting information to the EPA on November 21, 2016. In its November

[[Page 28608]]

2016 submittal the state spoke to the complexity of modeling fugitive 
emissions from the Doe Run Herculaneum facility and the appropriateness 
of utilizing 2014 emissions as a surrogate for the interactive sources. 
On February 22, 2017, the state provided additional supplemental 
information that consisted of available 2016 emissions inventory 
information. On May 1, 2017, the EPA received email notification from 
the state that its 2016 ambient air quality data was certified as 
complete and continues to show attainment of the standard; the design 
value for 2014-2016 is 23.0 ppb. These communications are available in 
the docket for this action.
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    \14\ The Doe Run Herculaneum (Herculaneum) facility was a lead 
smelting facility identified by the state and the EPA as the largest 
source of SO2 emissions in Jefferson County at the time 
of the promulgation of nonattainment designations in 2013. The 
facility ceased operations in December 2013. Although the source 
operated in 2013, emitting 11,477 tons of SO2, the state 
zeroed out its emissions in each of the 2013-2015 emission years in 
the modeling information.
    \15\ The state modeled all interactive sources utilizing the 
sources' 2014 emission limits (essentially modeling the 2014 
emissions input three times). The EPA requested that the state 
confirm that utilizing 2014 as a surrogate for 2013 and 2015 was 
appropriate.
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e. What is the EPA's rationale for proposing this action?

    The EPA is proposing to issue a determination of attainment for the 
nonattainment area based on the area's 2013-2015 modeling 
demonstration, which is supported by monitoring data from the Mott 
Street monitor. The 2014 SO2 Nonattainment Area Guidance and 
the accompanying 2016 SO2 Modeling TAD allow for 
nonattainment areas to model a mix of actual emissions and current 
allowable emissions, and as noted previously, we interpret that 
document to also allow this approach for a clean data determination.
    The state modeled actual emissions for all sources except for the 
Doe Run Herculaneum facility, which was modeled at zero emissions, 
since the facility shut down in December 2013.\16\ This treatment of 
the Doe Run Herculaneum facility is appropriate because the 
demonstration includes emissions for Doe Run Herculaneum using the most 
recent allowable emissions rate, which has been permanently and 
enforceably lowered during the relevant period. The maximum modeled 
impact from the model scenario is 172.8 [mu]g/m3, or 66 ppb, which 
complies with the 1-hour standard of 75 ppb. The model results satisfy 
the criteria for determinations of attainment according to the EPA's 
guidance and policy.
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    \16\ The Doe Run was limited to the terms of a consent decree 
applicable to the Herculaneum facility entered into by Doe Run, 
Missouri, and EPA in the United States District Court in the Eastern 
District of Missouri, Case No. 4:10-cv-01895-JCH on December 21, 
2011 (2011 Consent Decree). On December 31, 2013, pursuant to the 
terms of the 2011 Consent Decree, Doe Run permanently ceased 
operations of the sintering plant. The 2011 Consent Decree also 
required Doe Run to permanently cease smelting operations and retire 
the blast furnaces by April 30, 2014; Doe Run ceased operation of 
the blast furnaces on December 31, 2013, concurrently with the 
cessation of operation of the sintering plant.
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III. What is the EPA's analysis of the state's air quality monitoring 
and modeling data, and the state's supplemental emissions inventory 
information?

a. Ambient Air Quality Monitoring Data Evaluation

    According to the 2014 SO2 Nonattainment Area Guidance, 
to support a clean data determination based on monitoring, the state 
needs to demonstrate that the area is meeting the standard based on 
three consecutive calendar years of complete and quality-assured air 
quality monitoring data (consistent with 40 CFR part 58 requirements). 
The EPA has determined that three complete consecutive calendar years 
of quality-assured air quality monitoring data from the Mott Street 
monitor have been recorded in the EPA's Air Quality System (AQS), and 
the data meets the requirements of Appendix T to 40 CFR part 50 and 40 
CFR part 58. This data suggests improved air quality in the 
nonattainment area. As shown in Table 1, the 99th percentile 1-hour 
average (in ppb) at the Mott Street Monitor has decreased after 2013, 
when the Doe Run Herculaneum facility ceased primary smelting 
operations. As shown in Table 2, during the 2014-2016 monitoring 
period, the nonattainment area met the 2010 1-hour primary 
SO2 NAAQS. The certified annual design value for the 
nonattainment area for the 2014-2016 monitoring period is 23.0 ppb. 
Although clean data at a monitor sited in the area of maximum 
concentration could be sufficient for purposes of a clean data 
determination under the EPA's guidance, the state did not submit a 
demonstration showing that the Mott Street monitor is located in the 
area of maximum concentration. Thus, the monitoring data on its own is 
not sufficient to support a clean data determination in this case, and, 
as such, the state submitted modeling to support the clean data 
determination.

          Table 1--99th Percentile 1-Hour Average in Parts per Billion (ppb) at the Mott Street Monitor
                                                   [2013-2016]
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            Monitor                 Site name          2013            2014            2015            2016
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29-099-0027...................  Mott Street.....             143              18              38              13
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 Table 2--1-Hour Primary SO2 NAAQS Design Value (dv) for the Mott Street Monitor 99th Percentile 1-Hour Average
                              in Parts per Billion (ppb) at the Mott Street Monitor
                                                   [2014-2016]
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               State                        County             Monitor           Site name              dv
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MO................................  Jefferson............     29-099-0027  Mott Street..........            23.0
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b. Modeling Data and Supplemental 2016 Emissions Information Evaluation

    As noted earlier, the 2014 SO2 Nonattainment Area 
Guidance states that, in order for the EPA to make a clean data 
determination, the state may need to submit information in addition to 
monitoring data if the area was designated nonattainment based on air 
quality monitoring data. In August 2016, the state submitted modeling 
data for the most recent three years (2013-2015).\17\ In February 2017, 
the state submitted supplemental preliminary 2016 emissions data in 
support of assumptions made in the 2013-2015 modeling 
demonstration.\18\ The EPA reviewed the submitted modeling data

[[Page 28609]]

and supporting 2016 preliminary emissions data information for the 
nonattainment area to determine consistency with the EPA's Clean Data 
Policy, the 2014 SO2 Nonattainment Area Guidance and the 
2016 SO2 Modeling TAD.
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    \17\ The state's submittal included 2013-2015 emissions data as 
it was the complete and quality assured data set at the time of the 
submittal. The submittal includes a table of the sources included in 
the model and the emission rates used in the model. This information 
is provided in the docket.
    \18\ 2016 emissions data submitted by the state in February 2017 
included only data quality assured as of September 2016.
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    The EPA reviewed the August 2016 submittal to determine if the 
appropriate meteorological inputs were utilized. The state determined 
that the 2013-2015 meteorological data collected at the Doe Run 
Herculaneum meteorological sites were inappropriate for use in the 
model analysis as the data were disjointed. The data were disjointed 
due to a 2013 Consent Judgment between the state and Doe Run that 
allowed Doe Run Herculaneum to cease meteorological measurements at 
certain towers and to move the remaining tower to allow for site 
remediation. The state elected to use the most recent full three-year 
period (2013-2015) of data as measured at a spatially representative 
NWS airport site. The state utilized the St. Louis, Missouri downtown 
airport (Cahokia) for surface data and the Lincoln, Illinois site for 
upper air data. The meteorological data from the time period of 2013-
2015 was processed and paired with the emissions data as discussed 
later in this preamble. The EPA believes that the utilization of 
meteorological data from these sites was appropriate.\19\
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    \19\ See the state's August 2016 modeling demonstration, 
provided in the docket to this action, for model selection 
information (i.e., receptor grid selection).
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    The EPA finds that the state sufficiently considered all 
significant sources of SO2 emissions for inclusion in the 
modeling demonstration, including permitted sources of SO2 
emissions inside of the nonattainment area boundary, nearby sources 
(located within 20 kilometers (km) of the nonattainment area boundary 
and emitting greater than 1 ton per year (tpy) of SO2) 
outside the nonattainment area boundary, and large sources (sources 
that emit greater than 2,000 tpy of SO2) located within 50 
km of the nonattainment boundary. The EPA finds the modeled source 
inventory was created in accordance with the 2014 SO2 
Nonattainment Area Guidance and the 2016 SO2 Modeling TAD.
    To characterize the emissions from the sources in the modeling 
inventory, the state used hourly varying emissions, as reported to the 
EPA's Clean Air Markets Division (CAMD) program database, for three of 
the fifteen sources, and the 2014 actual emissions, as reported in the 
Missouri Emission Inventory System (MoEIS), for the remaining twelve 
sources. For the remaining twelve sources, the state converted the 
annual emissions to hourly emission rates utilizing operational hours 
reported by the facilities (as hourly emissions were not available for 
these twelve sources). The state's November 2016 supplemental 
information indicated that the state evaluated actual emissions for 
each year in the three-year period (2013-2015) separately. As can be 
expected, there were variations in hourly emissions during the modeled 
time period (2013-2015); emissions from either 2013 or 2015 were 
slightly higher than the 2014 emissions for six of the twelve sources. 
As such, in the November 2016 supplemental information, the state 
revised the modeling to reflect the highest hourly emissions (either 
reported to CAMD or converted to hourly emission rates by the State) 
for each interactive source during the three-year period. The variation 
in emissions resulted in only a 0.02 percent increase on the model-
predicted concentrations; the highest modeled impact increased from 
172.82 [mu]g/m\3\ to 172.85 [mu]g/m\3\. Considering the variation 
resulted in only a 0.02 percent increase on the predicted modeling 
concentrations, the EPA agrees with the state's assertion that the use 
of hourly emission data (either reported to CAMD or converted to hourly 
emission rates by the State) from 2014 for the interactive sources was 
a reasonable representation of the time period.
    The state did not include emissions from Doe Run Herculaneum in the 
modeling demonstration for any of the 2013-2015 emission years. The 
state modeled the facility at zero emissions from 2013-2015 even though 
the facility's primary smelting operation was active during 2013.\20\ 
The EPA believes that this modeling analysis supports the rationale 
outlined in section II.e. for proposing the clean data determination. 
The EPA believes that modeling the Doe Run Herculaneum facility at zero 
emissions is in accordance with the 2016 SO2 Modeling TAD as 
it is representative of current allowable emissions at the source. 
Because the EPA is interpreting that the 2016 SO2 Modeling 
TAD's provision for modeling a mix of current allowables and actuals 
for area designations is also appropriate for purposes of a clean data 
determination, the EPA finds that the emissions from all modeled 
sources were characterized appropriately in the model.
---------------------------------------------------------------------------

    \20\ Herculaneum emitted an estimated 11,477 tons of 
SO2 in 2013 prior to it ceasing operations in December of 
2013.
---------------------------------------------------------------------------

    As previously described, the state submitted additional information 
to the EPA in February 2017. In this submittal, the state acknowledged 
that that emissions data for the 4th quarter of 2016 was not yet 
available nor quality assured for modeling purposes. Most of the 
modeled source inventory data will not be available until at least mid-
2017. However, the state compared ``data elements of 2016'' to 2013 to 
determine whether the 2013 data could serve as a surrogate for 2016 
data.\21\ The state asserted that, because the August 2016 modeling 
demonstration used actual emissions for the period 2013-2015 for all 
sources except Doe Run Herculaneum, a modeling demonstration for the 
period 2014-2016 would likely yield similar results because Doe Run 
Herculaneum was not operational in any of those three years.
---------------------------------------------------------------------------

    \21\ Key data elements included meteorological data, available 
emission data and monitoring data.
---------------------------------------------------------------------------

    The supplemental information submitted by the state included an 
examination of variations in meteorology and in modeled source 
inventory emissions. This included a qualitative climatological 
comparison between the years 2013 and 2016 for the St. Louis, Missouri 
downtown airport location and highlighted the similarities and 
differences observed in those years. The state asserted that the 
meteorological information indicates that the differences in 
meteorological conditions from 2013 to 2016 are insignificant.
    The state also provided 2016 emissions information, as reported to 
CAMD, for the three EGUs (Ameren's Labadie, Meramec and Rush Island 
facilities) and compared them to the modeled 2013 emissions data. 
Partial data for 2016 (through September 30, 2016) emissions data was 
provided in CAMD; the state compared available 2016 emissions data 
(January 1, 2016-September 30, 2016) to 2013 emissions data for these 
three sources.22 23 For 2016, the three reported quarters 
were extrapolated to a full year for an annual comparison.\24\ This 
extrapolation assumed a continuation of comparable

[[Page 28610]]

emission levels. The extrapolated 2016 data indicated that the Labadie 
facility's SO2 emissions decreased 21 percent, the Meramec 
facility's SO2 emissions decreased 23 percent and the Rush 
Island facility's SO2 emissions decreased 3 percent from 
2013 annual emission rates. The state also asserted that updating the 
modeling data to include 2014-2016 emissions and meteorological 
information would not change the outcome of the previously submitted 
modeling information (which utilized 2013-2015 data) that modeled 
attainment of the NAAQS. Essentially, the state claimed, the maximum 
modeled impact from the model scenario (172.8 [mu]g/m\3\ or 66 ppb in 
the northwest portion of the nonattainment area) utilizing 2013-2015 
emission data without Doe Run Herculaneum emissions, is indicative of 
2014-2016 air quality without contributions from the Doe Run 
Herculaneum facility and demonstrates that the nonattainment area has 
attained the standard of 75 ppb.
---------------------------------------------------------------------------

    \22\ Ameren's Labadie and Meramec facilities are not in the 
nonattainment area but are within 50 km of the nonattainment area 
and emit greater than 2,000 tpy of SO2. Therefore, they 
were included in the state's modeling demonstration and subsequent 
supplemental information.
    \23\ All emissions data used in the analysis are available 
through the EPA's CAMD database online. https://www.epa.gov/airmarkets/clean-air-markets-data-resources.
    \24\ The first three quarters of 2016 were extrapolated to a 
full year for annual comparison by multiplying by 75 percent (x/
0.75).
---------------------------------------------------------------------------

    While the state's analysis of available 2016 emissions and 
meteorology data is informative, the EPA interprets that the 2014 
SO2 Nonattainment Area Guidance and the 2016 SO2 
Modeling TAD allows for modeling of a mix of actual emissions and 
current allowable emissions to support a clean data determination, and 
therefore the state's 2013-2015 modeling demonstration is sufficient to 
allow an assessment as to whether the area has achieved clean data.
    The EPA acknowledges the Doe Run Herculaneum facility's primary 
smelting operation is permanently shut down and recognizes the 
corresponding relationship between the decrease in the emissions from 
Doe Run Herculaneum and the decreased monitored concentrations at the 
Mott Street monitor as seen in table 3. The maximum hourly 
SO2 concentration was reduced by 87 percent from 2013 (143 
ppb) to 2014 (18 ppb) after the Doe Run Herculaneum facility closed. A 
comparison of the 99th percentile 1-hr average from the last full 
production year (2012) to the first post-shutdown year (2014) shows a 
93 percent reduction in monitored SO2 concentrations.

 Table 3--Decrease in Doe Run Herculaneum SO2 Emissions vs. the Decrease
              in Monitored 99th Percentile 1-Hour Averages
                               [2012-2015]
------------------------------------------------------------------------
                                               99th
                                           percentile 1-    Herculaneum
                  Year                     hour  average   SO2 emissions
                                               (ppb)           (tpy)
------------------------------------------------------------------------
2012....................................             268          17,894
2013....................................             143          11,477
2014....................................              18              <1
2015....................................              38              <1
------------------------------------------------------------------------

    The maximum modeled impact from the 2013-2015 model scenario is 
172.8 [mu]g/m\3\ or 66 ppb which complies with the 1-hour standard of 
75 ppb. The model results, along with monitored attainment of the NAAQS 
at the Mott Street monitor for the same time period, satisfies the 
criteria for clean data according to the EPA's guidance. Certified and 
quality assured 2016 air quality monitoring data is indicative of a 
substantial improvement in SO2 air quality in the 
nonattainment area; the design value for 2014-2016 is 23.0 ppb. 
Missouri's monitoring data, technical modeling analysis and 
supplemental information all support an EPA determination, consistent 
with its Clean Data Policy, that the nonattainment area has clean data 
and warrants a clean data determination.

VI. What would be the effects of this action, if promulgated?

    If this proposed determination is made final, the requirements for 
the state to submit an attainment demonstration, a reasonable further 
progress plan, contingency measures, and other planning SIPs revisions 
related to attainment of the 2010 1-hour primary SO2 NAAQS 
shall be suspended until such time, if any, that the EPA subsequently 
determines, after notice-and-comment rulemaking in the Federal 
Register, that the area has violated the 2010 1-hour primary 
SO2 NAAQS. If this were to occur, the basis for the 
suspension of the specific SIP requirements would no longer exist, and 
the state would thereafter have to address the pertinent requirements. 
If finalized, this determination of attainment would not shield the 
area from other required actions, such as provisions to address 
pollution transport, which could require emission reductions at sources 
or other types of emission activities contributing significantly to 
nonattainment in other areas or states, or interfering with maintenance 
in those areas. The EPA has the authority to require emissions 
reductions as necessary and appropriate to deal with transported air 
pollution situations. See CAA sections 110(a)(2)(D), 110(a)(2)(A), and 
126.
    If, after considering any comments received on this proposal, the 
EPA finalizes a clean data determination for this area, the state would 
need to continue to monitor and/or model air quality to verify 
continued attainment. The air agency would be expected to continue to 
operate an appropriate air quality monitoring network in the affected 
area, in accordance with the EPA regulations, to verify the attainment 
status of the area (see 40 CFR part 58).
    This proposed clean data determination is limited to a 
determination that the area attained the 2010 1-hour primary 
SO2 NAAQS as evidenced by the state's monitoring data and 
modeling analysis; this proposed action, if finalized, would not 
constitute a redesignation to attainment under section 107(d)(3) of the 
CAA. The designation status of the nonattainment area will remain 
nonattainment for the 2010 1-hour primary SO2 NAAQS until 
such time as the state submits an approvable redesignation request and 
maintenance plan, and the EPA takes final rulemaking action to 
determine that such submission meets the CAA requirements for 
redesignation to attainment.

V. Statutory and Executive Order Reviews

    This action proposes to make a determination based on air quality 
monitoring data and modeling and would, if finalized, result in the 
suspension of certain Federal requirements and would not impose any 
additional requirements. For that reason, this proposed 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);
     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

[[Page 28611]]

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, this proposed action does not 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 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, Sulfur dioxide, attainment determination.

    Dated: June 5, 2017.
Edward H, Chu,
Acting Regional Administrator, Region 7.
[FR Doc. 2017-13190 Filed 6-22-17; 8:45 am]
BILLING CODE 6560-50-P