2021-23116. Air Plan Approval; Michigan; Base Year Emissions Inventory for the 2010 Sulfur Dioxide Standard

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to approve, under the Clean Air Act (CAA), revisions to the State Implementation Plan (SIP) submitted by the Michigan department of Environment, Great Lakes, and Energy (EGLE) on June 30, 2021. The revisions address the emission inventory requirements for the St. Clair County nonattainment area under the 2010 sulfur dioxide (SO₂) National Ambient Air Quality Standard (NAAQS or standard). The CAA requires states to develop and submit, as SIP revisions, emission inventories for all areas designated as nonattainment for any NAAQS.

DATES:

Comments must be received on or before November 26, 2021.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R05-OAR-2021-0441 at http://www.regulations.gov or via email to [e-mail]. For comments submitted at Regulations.gov , follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov . For either manner of submission, 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. 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, please contact the person identified in the FOR FURTHER INFORMATION CONTACT section. For 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.

FOR FURTHER INFORMATION CONTACT:

Emily Crispell, Environmental Scientist, Control Strategies Section, Air Programs Branch (AR-18J), Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, Illinois 60604, [phone], [e-mail]. The EPA Region 5 office is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding Federal holidays and facility closures due to COVID-19.

SUPPLEMENTARY INFORMATION:

Throughout this document whenever “we,” “us,” or “our” is used, we mean EPA.

I. The 2010 SO₂ NAAQS Emissions Inventory Requirements

On June 22, 2010, EPA promulgated a revised 1-hour SO₂ NAAQS of 75 parts per billion (ppb) (75 FR 35520). On September 12, 2016 the partial St. Clair County area was designated as nonattainment (St. Clair nonattainment area) for the 2010 1-hour SO₂ NAAQS. The St. Clair nonattainment area is defined by the St. Clair River for the eastern boundary, an extension from the St. Clair River directly west to the intersection of State Highway M-29 and St. Clair River Drive, continuing west on State Highway M-29 to Church Road to Arnold Road to County Line Road for the southern boundary, County Line Road and the Macomb/St. Clair County boundary to Stoddard Road to Wales Ridge Road for the western boundary, and Alpine Road to Fitz Road to Smith Creek Road to Range Road to Huron Avenue, extending directly east from the intersection of Huron Road and River Road to the St. Clair River for the northern boundary (83 FR 1098, January 9, 2018).

CAA section 172(c)(3), 42 U.S.C. 7502(c)(3), requires states to develop and submit, as SIP revisions, emission inventories for all areas designated as nonattainment for any NAAQS. An emission inventory for SO₂ is an estimation of actual emissions of sulfur oxides (SO_X) in an area. SO₂ is the component of greatest concern and is used as the indicator for the larger group of gaseous SO_X . SO₂ is a gas that is formed by the burning of fossil fuels by power plants and other industrial facilities such as extracting metal from ore; natural sources such as volcanoes; and locomotives, ships and other vehicles and heavy equipment that burn fuel with a high sulfur content. Control measures that reduce SO₂ can generally be expected to reduce people's exposures to all gaseous SO_X . Therefore, an emission inventory for SO_X focuses on the emissions of SO₂ .

Emission inventories provide emissions data for a variety of air quality planning tasks, including establishing baseline emission levels (anthropogenic [manmade] emissions associated with SO₂ standard violations), calculating emission reduction targets needed to attain the NAAQS, determining emission inputs for SO₂ air quality modeling analyses, and tracking emissions over time to determine progress toward achieving air quality and emission reduction goals. As stated above, the CAA requires the states to submit emission inventories for areas designated as nonattainment for SO₂ . For the 2010 1-hour SO₂ NAAQS, EPA specifies that states submit SO₂ emission estimates for an inventory calendar year preceding the year of the area's effective date of designation as a nonattainment area (75 FR 35520). States are required to submit estimates of SO₂ emissions for four general classes of anthropogenic sources: stationary point sources; area sources; on-road mobile sources; and off-road mobile sources.

II. EGLE's Emissions Inventory

On June 30, 2021, EGLE submitted a SIP revision addressing the emissions inventory requirement of CAA section 172(c)(3). EGLE also clarified that Michigan has a fully approved Nonattainment New Source Review (NSR) program, which is set forth in Part 19 of Michigan's rules (R 336.2901 through R 336.2908). EPA confirms that this NSR program was approved by the EPA into the SIP on December 16, 2013 (78 FR 76064). EGLE provided documentation for the 2014 SO₂ base year emissions inventory for the St. Clair County nonattainment area. EGLE selected 2014 because this was one of the three years of SO₂ data indicating a violation of the SO₂ standard that were used to designate the areas as nonattainment for the 2010 SO₂ NAAQS (83 FR 1098). In addition, the 2014 emissions inventory was the most recent comprehensive, accurate, and quality assured (QA) triennial emissions inventory in the National Emissions Inventory (NEI) database, available at the time the state began preparing the emissions inventory submittal for the partial St. Clair County area. Table 1 summarizes the 2014 SO₂ emissions for the partial St. Clair County area in tons of emissions per year.

Table 1—2014 SO ₂ Emissions

County/NAA	2014 SO 2 Emissions (tons/year)
	EGU 1	Non-EGU point	Area	Non-road	On-road	Total SO 2
Partial St. Clair	51,920	1,632	74.4	0.59	12.2	53,639.19
1  Electric Generating Units (EGU).

A. Base Year Inventory

EGLE estimated SO₂ emissions for all source categories in the St. Clair County SO₂ nonattainment area. Emissions for the St. Clair County SO₂ nonattainment area were totaled by source category.

a. Point Sources

To develop the SO₂ point source emissions inventory, EGLE used the annual emissions data contained in EPA's Clean Air Markets Division database for emissions from EGU point sources and annual emissions data reported by facility operators to EGLE's air emissions inventory database for non-EGU point sources.

b. Area Sources

To develop the SO₂ area source emissions inventories, EGLE used the annual emissions data contained in EPA's 2014 NEI to estimate 2014 emissions.

c. On-Road and Non-Road Sources

To develop the SO₂ non-road and on-road source emissions inventories, EGLE used the annual emissions data contained in EPA's 2014 NEI to estimate 2014 emissions.

III. EPA's Evaluation

A. Emissions Inventory

EPA has reviewed EGLE's June 30, 2021, requested SIP revision for consistency with section 172(c)(3) CAA and with EPA's emission inventory requirements. In particular, EPA has reviewed the techniques used by EGLE to quantify and quality assure the emission estimates. EPA has also considered whether EGLE has provided the public with the opportunity to review and comment on the development of the emission estimates, and whether the State has addressed all public comments. EGLE received no comments during the comment period but did receive a comment from EPA Region 5. The comment asked that the emission inventory include the 2014 NEI emissions for 3 other categories of sources: on-road, non-road, and area. EGLE addressed this comment by adding on-road, non-road, and area SO₂ emissions estimates for the St. Clair County nonattainment area to their emissions inventory submittal. EGLE documented the procedures used to estimate the emissions for each of the major source types. Our review finds that EGLE followed acceptable procedures to estimate the emissions.

Accordingly, we propose to conclude that EGLE has developed an inventory of SO₂ sources that is comprehensive and complete. EGLE's submittal of a complete emission inventory and certification of an approved NSR program in addition to a Clean Data Determination, proposed in a separate action on August 17, 2021 (86 FR 45947), addresses deficiencies identified in the September 20, 2019 (84 FR 49463) finding of failure to submit a nonattainment plan for the St. Clair area, and will stop the sanctions clocks applicable to those deficiencies.

IV. EPA Action

EPA is proposing to approve EGLE's SIP revision submitted to address the SO₂ -related emission inventory and NSR certification requirements for the partial St. Clair County SO₂ nonattainment area for the 2010 SO₂ NAAQS. The emission inventory we are approving into the SIP is specified in Table 1. We are also proposing to approve the emission inventory because it contains comprehensive, accurate, and current inventories of actual emissions for all relevant sources in accordance with CAA section 172(c)(3), and because EGLE adopted the emission inventories after providing for reasonable public notice. EPA also proposes to approve the certification of Michigan's fully approved NSR program, which was approved by the EPA into the SIP on December 16, 2013 (78 FR 76064) and meets the requirements of CAA section 172(c)(5).

V. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action merely approves 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);

• 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 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 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).

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Incorporation by reference, sulfur oxides

Dated: October 19, 2021.

Cheryl Newton,

Acting Regional Administrator, Region 5.